Science.gov

Sample records for effective mass approximation

  1. Rational approximations of effectiveness factor and general diagnostic criteria for heat and mass transport limitations

    SciTech Connect

    Gonzo, E.E.; Gottifredi, J.C.

    1983-01-01

    Many efforts have been made to predict the effect of diffusion on the observed rate of reaction and its role in modifying the activity and selectivity of porous catalysts. The discussion of rational approximation predicts the effect of diffusional phenomena on the overall rate of reaction under a great variety of circumstances and shows how some part of the theoretical development can be used to deduce two general criteria to establish the conditions where diffusional phenomena can be safely neglected. The reviewed approximations give accurate results with minimal computational effort as long as multiplicity is absent. The expression is given that accurately predicts effectiveness factor values under isothermal conditions provided the apparent reaction order is greater than 0.5. Expressions have been previously reported that are applicable under nonisothermal conditions. The review of the 54 references was devoted to the single reaction case because not much work has been done on complex reaction systems. (BLM)

  2. Two-loop QCD corrections to the MSSM Higgs masses beyond the effective-potential approximation

    NASA Astrophysics Data System (ADS)

    Degrassi, G.; Di Vita, S.; Slavich, P.

    2015-02-01

    We compute the two-loop QCD corrections to the neutral Higgs-boson masses in the Minimal Supersymmetric Standard Model, including the effect of non-vanishing external momenta in the self-energies. We obtain corrections of and , i.e., all two-loop corrections that involve the strong gauge coupling when the only non-vanishing Yukawa coupling is the top one. We adopt either the renormalization scheme or a mixed on-shell (OS)- scheme where the top/stop parameters are renormalized on-shell. We compare our results with those of earlier calculations, pointing out an inconsistency in a recent result obtained in the mixed OS- scheme. The numerical impact of the new corrections on the prediction for the lightest-scalar mass is moderate, but already comparable to the accuracy of the Higgs-mass measurement at the Large Hadron Collider.

  3. Study of Odor Approximation by Using Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Ohno, Masashi; Nihei, Yasunori; Nakamoto, Takamichi

    2011-09-01

    Since a set of odor components to cover wide range of smells has not been revealed yet, we studied the selection of odor components using essential-oil mass spectrum database. Basis vectors were extracted using non-negative matrix factorization method1 and then non-negative least squares method was used to determine the recipe. The odor approximations of three typical essential oils were confirmed by the sensory test. It was found that the mass spectrum data were correlated with the sensory test result. Moreover, this correlation was remarkable in the high m/z region.

  4. Approximate methods for building extreme mass ratio inspiral waveforms

    NASA Astrophysics Data System (ADS)

    Hughes, Scott

    2007-04-01

    The ``extreme mass ratio inspiral'' (or EMRI) problem has captured much attention in recent years. This is due to its relevance at describing a potentially important gravitational-wave source, and to the elegance of techniques which are being developed to solve it. A complete, self-consistent solution to this problem will require detailed knowledge of the self-interaction of a small body orbiting a Kerr black hole, taken (at least in part) to second order. This challenge will consume much time and effort. In the meantime, there is an exigent need for waveforms which, though not correct in all details, are sufficiently reliable that they can be used to understand how to measure these waves with space-based gravitational-wave antennae. I will describe in this talk results from a crude but surprisingly effective ``kludge'' approximation. The kludge produces waves which match well with available strong-field results, requiring only a fraction of the computational effort. Motivated by how the kludge operates, I will argue that a good medium between the kludge and the full solution is a ``hybrid'' approach to waveform generation. This hybrid combines the best features of both time and frequency domain approaches to black hole perturbation theory, using them to make EMRI waves that are as accurate as is possible without incorporating self-force information.

  5. Very extended shpaes in the A {approximately} 150 mass region

    SciTech Connect

    Chasman, R.R.

    1995-08-01

    There was a report of a rotational band in {sup 152}Dy or {sup 153}Dy that is characterized by a dynamic moment of inertia of 130h{sup 2} MeV{sup -1}. For purposes of orientation, it should be noted that the well known superdeformed bands in this region are characterized by moments of inertia of {approximately}90. Some calculations were carried out in two- and three-dimensional shape spaces, in order to understand this experimental observation. These calculations show either very shallow minima and/or minima that do not become yrast below I = 90 at the very large deformations that would seem to be required to explain such a large moment of inertia. We extended our four-dimensional deformation space Strutinsky calculations to a study of this mass region, with the hope of gaining some insight into the nature of this band. We are also analyzing the other nuclides of this mass region with the hope of finding other instances of such very extended shapes. This analysis is almost complete.

  6. QCD Phase Diagram and the Constant Mass Approximation

    NASA Astrophysics Data System (ADS)

    Ahmad, A.; Ayala, A.; Bashir, A.; Gutiérrez, E.; Raya, A.

    2015-11-01

    Dynamical generation of quark masses in the infrared region of QCD plays an important role to understand the peculiar nature of the physics of hadrons. As it is known, the solution of QCD gap equation for the quark mass function is flat for low momentum, but smoothly evolves to the perturbative behavior at high momentum. In this work, we use an effective truncation of QCD gap equation valid up to 1 GeV, and implement it at finite temperature and chemical potential to understand the QCD phase diagram for chiral symmetry breaking-chiral symmetry restoration, and confinement-deconfinement phase transitions from the Schwinger-Dysin equations point of view. Our effective kernel contains a gluon dressing function with two light quark flavors Nf = 2, with current quark mass 0.0035 GeV. An effective coupling, adjusted to reproduce the behavior of the chiral condensate at finite T complements our truncation. We find the critical end point of the phase diagram located at the temperature TE = 0.1245 GeV and the baryonic chemical potential μEB = 0.211 GeV.

  7. Chiral Magnetic Effect in Hydrodynamic Approximation

    NASA Astrophysics Data System (ADS)

    Zakharov, Valentin I.

    We review derivations of the chiral magnetic effect (ChME) in hydrodynamic approximation. The reader is assumed to be familiar with the basics of the effect. The main challenge now is to account for the strong interactions between the constituents of the fluid. The main result is that the ChME is not renormalized: in the hydrodynamic approximation it remains the same as for non-interacting chiral fermions moving in an external magnetic field. The key ingredients in the proof are general laws of thermodynamics and the Adler-Bardeen theorem for the chiral anomaly in external electromagnetic fields. The chiral magnetic effect in hydrodynamics represents a macroscopic manifestation of a quantum phenomenon (chiral anomaly). Moreover, one can argue that the current induced by the magnetic field is dissipation free and talk about a kind of "chiral superconductivity". More precise description is a quantum ballistic transport along magnetic field taking place in equilibrium and in absence of a driving force. The basic limitation is the exact chiral limit while temperature—excitingly enough—does not seemingly matter. What is still lacking, is a detailed quantum microscopic picture for the ChME in hydrodynamics. Probably, the chiral currents propagate through lower-dimensional defects, like vortices in superfluid. In case of superfluid, the prediction for the chiral magnetic effect remains unmodified although the emerging dynamical picture differs from the standard one.

  8. Analytic approximate radiation effects due to Bremsstrahlung

    SciTech Connect

    Ben-Zvi I.

    2012-02-01

    The purpose of this note is to provide analytic approximate expressions that can provide quick estimates of the various effects of the Bremsstrahlung radiation produced relatively low energy electrons, such as the dumping of the beam into the beam stop at the ERL or field emission in superconducting cavities. The purpose of this work is not to replace a dependable calculation or, better yet, a measurement under real conditions, but to provide a quick but approximate estimate for guidance purposes only. These effects include dose to personnel, ozone generation in the air volume exposed to the radiation, hydrogen generation in the beam dump water cooling system and radiation damage to near-by magnets. These expressions can be used for other purposes, but one should note that the electron beam energy range is limited. In these calculations the good range is from about 0.5 MeV to 10 MeV. To help in the application of this note, calculations are presented as a worked out example for the beam dump of the R&D Energy Recovery Linac.

  9. Improved effective vector boson approximation revisited

    NASA Astrophysics Data System (ADS)

    Bernreuther, Werner; Chen, Long

    2016-03-01

    We reexamine the improved effective vector boson approximation which is based on two-vector-boson luminosities Lpol for the computation of weak gauge-boson hard scattering subprocesses V1V2→W in high-energy hadron-hadron or e-e+ collisions. We calculate these luminosities for the nine combinations of the transverse and longitudinal polarizations of V1 and V2 in the unitary and axial gauge. For these two gauge choices the quality of this approach is investigated for the reactions e-e+→W-W+νeν¯ e and e-e+→t t ¯ νeν¯ e using appropriate phase-space cuts.

  10. Quark mass effect on axial charge dynamics

    NASA Astrophysics Data System (ADS)

    Guo, Er-dong; Lin, Shu

    2016-05-01

    We studied the effect of finite quark mass on the dynamics of the axial charge using the D3/D7 model in holography. The mass term in the axial anomaly equation affects both the fluctuation (generation) and dissipation of the axial charge. We studied the dependence of the effect on quark mass and an external magnetic field. For axial charge generation, we calculated the mass diffusion rate, which characterizes the helicity flipping rate. The rate is a nonmonotonous function of mass and can be significantly enhanced by the magnetic field. The diffusive behavior is also related to a divergent susceptibility of the axial charge. For axial charge dissipation, we found that in the long time limit, the mass term dissipates all the charge effectively generated by parallel electric and magnetic fields. The result is consistent with a relaxation time approximation. The rate of dissipation through mass term is a monotonous increasing function of both quark mass and a magnetic field.

  11. Missing mass approximations for the partition function of stimulus driven Ising models

    PubMed Central

    Haslinger, Robert; Ba, Demba; Galuske, Ralf; Williams, Ziv; Pipa, Gordon

    2013-01-01

    Ising models are routinely used to quantify the second order, functional structure of neural populations. With some recent exceptions, they generally do not include the influence of time varying stimulus drive. Yet if the dynamics of network function are to be understood, time varying stimuli must be taken into account. Inclusion of stimulus drive carries a heavy computational burden because the partition function becomes stimulus dependent and must be separately calculated for all unique stimuli observed. This potentially increases computation time by the length of the data set. Here we present an extremely fast, yet simply implemented, method for approximating the stimulus dependent partition function in minutes or seconds. Noting that the most probable spike patterns (which are few) occur in the training data, we sum partition function terms corresponding to those patterns explicitly. We then approximate the sum over the remaining patterns (which are improbable, but many) by casting it in terms of the stimulus modulated missing mass (total stimulus dependent probability of all patterns not observed in the training data). We use a product of conditioned logistic regression models to approximate the stimulus modulated missing mass. This method has complexity of roughly O(LNNpat) where is L the data length, N the number of neurons and Npat the number of unique patterns in the data, contrasting with the O(L2N) complexity of alternate methods. Using multiple unit recordings from rat hippocampus, macaque DLPFC and cat Area 18 we demonstrate our method requires orders of magnitude less computation time than Monte Carlo methods and can approximate the stimulus driven partition function more accurately than either Monte Carlo methods or deterministic approximations. This advance allows stimuli to be easily included in Ising models making them suitable for studying population based stimulus encoding. PMID:23898262

  12. Twisted mass finite volume effects

    SciTech Connect

    Colangelo, Gilberto; Wenger, Urs; Wu, Jackson M. S.

    2010-08-01

    We calculate finite-volume effects on the pion masses and decay constant in twisted mass lattice QCD at finite lattice spacing. We show that the lighter neutral pion in twisted mass lattice QCD gives rise to finite-volume effects that are exponentially enhanced when compared to those arising from the heavier charged pions. We demonstrate that the recent two flavor twisted mass lattice data can be better fitted when twisted mass effects in finite-volume corrections are taken into account.

  13. Born-Oppenheimer approximation for mass scaling of cold-collision properties

    SciTech Connect

    Falke, Stephan; Tiemann, Eberhard; Lisdat, Christian

    2007-07-15

    Asymptotic levels of the A {sup 1}{sigma}{sub u}{sup +} state of the two isotopomers {sup 39}K{sub 2} and {sup 39}K{sup 41}K up to the dissociation limit are investigated with a Doppler-free high resolution laser-spectroscopic experiment in a molecular beam. The observed level structure can be reproduced correctly only if a mass dependent correction term is introduced for the interaction potential. The applied relative correction in the depth of the potential is 10{sup -6}, which is in the order of magnitude expected for corrections of the Born-Oppenheimer approximation. A similar change in ground state potentials might lead to significant changes of mass-scaled properties describing cold collisions like the s-wave scattering length.

  14. Effective medium approximations for anisotropic composites with arbitrary component orientation

    NASA Astrophysics Data System (ADS)

    Levy, Ohad; Cherkaev, Elena

    2013-10-01

    A Maxwell Garnett approximation (MGA) and a symmetric effective medium approximation (SEMA) are derived for anisotropic composites of host-inclusion and symmetric-grains morphologies, respectively, with ellipsoidal grains of arbitrary intrinsic, shape and orientation anisotropies. The effect of anisotropy on the effective dielectric tensor is illustrated in both cases. The MGA shows negative and non-monotonic off-diagonal elements for geometries where the host and inclusions are not mutually aligned. The SEMA leads to an anisotropy-dependent nonlinear behaviour of the conductivity as a function of volume fraction above a percolation threshold of conductor-insulator composites, in contrast to the well-known linear behaviour of the isotropic effective medium model. The percolation threshold obtained for composites of aligned ellipsoids is isotropic and independent of the ellipsoids aspect ratio. Thus, the common identification of the percolation threshold with the depolarization factors of the grains is unjustified and a description of anisotropic percolation requires explicit anisotropic geometric characteristics.

  15. Approximations for column effect in airplane wing spars

    NASA Technical Reports Server (NTRS)

    Warner, Edward P; Short, Mac

    1927-01-01

    The significance attaching to "column effect" in airplane wing spars has been increasingly realized with the passage of time, but exact computations of the corrections to bending moment curves resulting from the existence of end loads are frequently omitted because of the additional labor involved in an analysis by rigorously correct methods. The present report represents an attempt to provide for approximate column effect corrections that can be graphically or otherwise expressed so as to be applied with a minimum of labor. Curves are plotted giving approximate values of the correction factors for single and two bay trusses of varying proportions and with various relationships between axial and lateral loads. It is further shown from an analysis of those curves that rough but useful approximations can be obtained from Perry's formula for corrected bending moment, with the assumed distance between points of inflection arbitrarily modified in accordance with rules given in the report. The discussion of general rules of variation of bending stress with axial load is accompanied by a study of the best distribution of the points of support along a spar for various conditions of loading.

  16. Damping effects in doped graphene: The relaxation-time approximation

    NASA Astrophysics Data System (ADS)

    Kupčić, I.

    2014-11-01

    The dynamical conductivity of interacting multiband electronic systems derived by Kupčić et al. [J. Phys.: Condens. Matter 90, 145602 (2013), 10.1088/0953-8984/25/14/145602] is shown to be consistent with the general form of the Ward identity. Using the semiphenomenological form of this conductivity formula, we have demonstrated that the relaxation-time approximation can be used to describe the damping effects in weakly interacting multiband systems only if local charge conservation in the system and gauge invariance of the response theory are properly treated. Such a gauge-invariant response theory is illustrated on the common tight-binding model for conduction electrons in doped graphene. The model predicts two distinctly resolved maxima in the energy-loss-function spectra. The first one corresponds to the intraband plasmons (usually called the Dirac plasmons). On the other hand, the second maximum (π plasmon structure) is simply a consequence of the Van Hove singularity in the single-electron density of states. The dc resistivity and the real part of the dynamical conductivity are found to be well described by the relaxation-time approximation, but only in the parametric space in which the damping is dominated by the direct scattering processes. The ballistic transport and the damping of Dirac plasmons are thus the problems that require abandoning the relaxation-time approximation.

  17. Quantum anti-Zeno effect without rotating wave approximation

    SciTech Connect

    Ai Qing; Sun, C. P.; Li Yong; Zheng Hang

    2010-04-15

    In this article, we systematically study the spontaneous decay phenomenon of a two-level system under the influences of both its environment and repetitive measurements. In order to clarify some well-established conclusions about the quantum Zeno effect (QZE) and the quantum anti-Zeno effect (QAZE), we do not use the rotating wave approximation (RWA) in obtaining an effective Hamiltonian. We examine various spectral distributions by making use of our present approach in comparison with other approaches. It is found that with respect to a bare excited state even without the RWA, the QAZE can still happen for some cases, for example, the interacting spectra of hydrogen. However, for a physical excited state, which is a renormalized dressed state of the atomic state, the QAZE disappears and only the QZE remains. These discoveries inevitably show a transition from the QZE to the QAZE as the measurement interval changes.

  18. Double Photoionization of Beryllium atoms using Effective Charge approximation

    NASA Astrophysics Data System (ADS)

    Saha, Haripada

    2016-05-01

    We plan to report the results of our investigation on double photoionization K-shell electrons from Beryllium atoms. We will present the results of triple differential cross sections at excess energy of 20 eV using our recently extended MCHF method. We will use multiconfiguration Hartree Fock method to calculate the wave functions for the initial state. The final state wave functions will be obtained in the angle depended Effective Charge approximation which accounts for electron correlation between the two final state continuum electrons. We will discuss the effect of core correlation and the valence shell electrons in the triple differential cross section. The results will be compared with the available accurate theoretical calculations and experimental findings.

  19. Mass-independent isotope effects.

    PubMed

    Buchachenko, Anatoly L

    2013-02-28

    Three fundamental properties of atomic nuclei-mass, spin (and related magnetic moment), and volume-are the source of isotope effects. The mostly deserved and popular, with almost hundred-year history, is the mass-dependent isotope effect. The first mass-independent isotope effect which chemically discriminates isotopes by their nuclear spins and nuclear magnetic moments rather than by their masses was detected in 1976. It was named as the magnetic isotope effect because it is controlled by magnetic interaction, i.e., electron-nuclear hyperfine coupling in the paramagnetic species, the reaction intermediates. The effect follows from the universal physical property of chemical reactions to conserve angular momentum (spin) of electrons and nuclei. It is now detected for oxygen, silicon, sulfur, germanium, tin, mercury, magnesium, calcium, zinc, and uranium in a great variety of chemical and biochemical reactions including those of medical and ecological importance. Another mass-independent isotope effect was detected in 1983 as a deviation of isotopic distribution in reaction products from that which would be expected from the mass-dependent isotope effect. On the physical basis, it is in fact a mass-dependent effect, but it surprisingly results in isotope fractionation which is incompatible with that predicted by traditional mass-dependent effects. It is supposed to be a function of dynamic parameters of reaction and energy relaxation in excited states of products. The third, nuclear volume mass-independent isotope effect is detected in the high-resolution atomic and molecular spectra and in the extraction processes, but there are no unambiguous indications of its importance as an isotope fractionation factor in chemical reactions. PMID:23301791

  20. Nuclear energy surfaces at high-spin in the A{approximately}180 mass region

    SciTech Connect

    Chasman, R.R.; Egido, J.L.; Robledo, L.M.

    1995-08-01

    We are studying nuclear energy surfaces at high spin, with an emphasis on very deformed shapes using two complementary methods: (1) the Strutinsky method for making surveys of mass regions and (2) Hartree-Fock calculations using a Gogny interaction to study specific nuclei that appear to be particularly interesting from the Strutinsky method calculations. The great advantage of the Strutinsky method is that one can study the energy surfaces of many nuclides ({approximately}300) with a single set of calculations. Although the Hartree-Fock calculations are quite time-consuming relative to the Strutinsky calculations, they determine the shape at a minimum without being limited to a few deformation modes. We completed a study of {sup 182}Os using both approaches. In our cranked Strutinsky calculations, which incorporate a necking mode deformation in addition to quadrupole and hexadecapole deformations, we found three well-separated, deep, strongly deformed minima. The first is characterized by nuclear shapes with axis ratios of 1.5:1; the second by axis ratios of 2.2:1 and the third by axis ratios of 2.9:1. We also studied this nuclide with the density-dependent Gogny interaction at I = 60 using the Hartree-Fock method and found minima characterized by shapes with axis ratios of 1.5:1 and 2.2:1. A comparison of the shapes at these minima, generated in the two calculations, shows that the necking mode of deformation is extremely useful for generating nuclear shapes at large deformation that minimize the energy. The Hartree-Fock calculations are being extended to larger deformations in order to further explore the energy surface in the region of the 2.9:1 minimum.

  1. The Cauchy convergence of T and P-approximant templates for test-mass Kerr binary systems

    NASA Astrophysics Data System (ADS)

    Porter, Edward K.

    2006-06-01

    In this work, we examine the Cauchy convergence of both post-Newtonian (T-approximant) and re-summed post-Newtonian (P-approximant) templates for the case of a test-mass orbiting a Kerr black hole along a circular equatorial orbit. The Cauchy criterion demands that the inner product between the n and n + 1 order approximation approaches unity, as we increase the order of approximation. In previous works, it has been shown that we achieve greater fitting factors and better parameter estimation using the P-approximant templates for both Schwarzschild and Kerr black holes. In this work, we show that the P-approximant templates also display a faster Cauchy convergence making them a superior template to the standard post-Newtonian templates.

  2. Electrospray ionization mass spectrometric determination of the molecular mass of the approximately 200-kDa globin dodecamer subassemblies in hexagonal bilayer hemoglobins.

    PubMed

    Green, B N; Bordoli, R S; Hanin, L G; Lallier, F H; Toulmond, A; Vinogradov, S N

    1999-10-01

    Hexagonal bilayer hemoglobins (Hbs) are approximately 3.6-MDa complexes of approximately 17-kDa globin chains and 24-32-kDa, nonglobin linker chains in a approximately 2:1 mass ratio found in annelids and related species. Studies of the dissociation and reassembly of Lumbricus terrestris Hb have provided ample evidence for the presence of a approximately 200-kDa linker-free subassembly consisting of monomer (M) and disulfide-bonded trimer (T) subunits. Electrospray ionization mass spectrometry (ESI-MS) of the subassemblies obtained by gel filtration of partially dissociated L. terrestris and Arenicola marina Hbs showed the presence of noncovalent complexes of M and T subunits with masses in the 213. 3-215.4 and 204.6-205.6 kDa ranges, respectively. The observed mass of the L. terrestris subassembly decreased linearly with an increase in de-clustering voltage from approximately 215,400 Da at 60 V to approximately 213,300 Da at 200 V. In contrast, the mass of the A. marina complex decreased linearly from 60 to 120 V and reached an asymptote at approximately 204,600 Da (180-200 V). The decrease in mass was probably due to the progressive removal of complexed water and alkali metal cations. ESI-MS at an acidic pH showed both subassemblies to consist of only M and T subunits, and the experimental masses demonstrated them to have the composition M(3)T(3). Because there are three isoforms of M and four isoforms of T in Lumbricus and two isoforms of M and 5 isoforms of T in Arenicola, the masses of the M(3)T(3) subassemblies are not unique. A random assembly model was used to calculate the mass distributions of the subassemblies, using the known ESI-MS masses and relative intensities of the M and T subunit isforms. The expected mass of randomly assembled subassemblies was 213,436 Da for Lumbricus Hb and 204,342 Da for Arenicola Hb, in good agreement with the experimental values. PMID:10497174

  3. Detecting gravitational waves from test-mass bodies orbiting a Kerr black hole with P-approximant templates

    NASA Astrophysics Data System (ADS)

    Porter, Edward K.

    2005-09-01

    In this study, we apply post-Newtonian (T-approximants) and resummed post-Newtonian (P-approximants) to the case of a test particle in equatorial orbit around a Kerr black hole. We compare the two approximants by measuring their effectualness (i.e., larger overlaps with the exact signal) and faithfulness (i.e., smaller biases while measuring the parameters of the signal) with the exact (numerical) waveforms. We find that in the case of prograde orbits, T-approximant templates obtain an effectualness of ~0.99 for spins q <= 0.75. For 0.75 < q < 0.95, the effectualness drops to about 0.82. The P-approximants achieve effectualness of >0.99 for all spins up to q = 0.95. The bias in the estimation of parameters is much lower in the case of P-approximants than T-approximants. We find that P-approximants are both effectual and faithful and should be more effective than T-approximants as a detection template family when q > 0. For q < 0, both T- and P-approximants perform equally well so that either of them could be used as a detection template family. However, for parameter estimation, the P-approximant templates still outperform the T-approximants.

  4. Accuracy of the Michaelis-Menten approximation when analysing effects of molecular noise.

    PubMed

    Lawson, Michael J; Petzold, Linda; Hellander, Andreas

    2015-05-01

    Quantitative biology relies on the construction of accurate mathematical models, yet the effectiveness of these models is often predicated on making simplifying approximations that allow for direct comparisons with available experimental data. The Michaelis-Menten (MM) approximation is widely used in both deterministic and discrete stochastic models of intracellular reaction networks, owing to the ubiquity of enzymatic activity in cellular processes and the clear biochemical interpretation of its parameters. However, it is not well understood how the approximation applies to the discrete stochastic case or how it extends to spatially inhomogeneous systems. We study the behaviour of the discrete stochastic MM approximation as a function of system size and show that significant errors can occur for small volumes, in comparison with a corresponding mass-action system. We then explore some consequences of these results for quantitative modelling. One consequence is that fluctuation-induced sensitivity, or stochastic focusing, can become highly exaggerated in models that make use of MM kinetics even if the approximations are excellent in a deterministic model. Another consequence is that spatial stochastic simulations based on the reaction-diffusion master equation can become highly inaccurate if the model contains MM terms. PMID:25833240

  5. Vibration energy harvesting from a nonlinear standing beam-mass system using a two-mode approximation

    NASA Astrophysics Data System (ADS)

    Lajimi, S. A. M.; Friswell, M. I.

    2015-04-01

    For a nonlinear beam-mass system used to harvest vibratory energy, the two-mode approximation of the response is computed and compared to the single-mode approximation of the response. To this end, the discretized equations of generalized coordinates are developed and studied using a computational method. By obtaining phase-portraits and time-histories of the displacement and voltage, it is shown that the strong nonlinearity of the system affects the system dynamics considerably. By comparing the results of single- and two-mode approximations, it is shown that the number of mode shapes affects the dynamics of the response. Varying the tip-mass results in different structural configurations namely linear, pre-buckled nonlinear, and post-buckled nonlinear configurations. The nonlinear dynamics of the system response are investigated for vibrations about static equilibrium points arising from the buckling of the beam. Furthermore, it is demonstrated that the harvested power is affected by the system configuration.

  6. Thermal effects and sudden decay approximation in the curvaton scenario

    SciTech Connect

    Kitajima, Naoya; Takesako, Tomohiro; Yokoyama, Shuichiro; Langlois, David; Takahashi, Tomo E-mail: langlois@apc.univ-paris7.fr E-mail: takesako@icrr.u-tokyo.ac.jp

    2014-10-01

    We study the impact of a temperature-dependent curvaton decay rate on the primordial curvature perturbation generated in the curvaton scenario. Using the familiar sudden decay approximation, we obtain an analytical expression for the curvature perturbation after the decay of the curvaton. We then investigate numerically the evolution of the background and of the perturbations during the decay. We first show that the instantaneous transfer coefficient, related to the curvaton energy fraction at the decay, can be extended into a more general parameter, which depends on the net transfer of the curvaton energy into radiation energy or, equivalently, on the total entropy ratio after the complete curvaton decay. We then compute the curvature perturbation and compare this result with the sudden decay approximation prediction.

  7. Mass-selective neutron spectroscopy of lithium hydride and deuteride: Experimental assessment of the harmonic and impulse approximations

    NASA Astrophysics Data System (ADS)

    Krzystyniak, Maciej; Richards, Selena E.; Seel, Andrew G.; Fernandez-Alonso, Felix

    2013-11-01

    Neutron Compton scattering experiments on crystalline lithium hydride and deuteride are presented and compared with existing experimental data and first-principles predictions. With currently available instrumentation, these measurements demonstrate sufficient mass selectivity for studies of nuclear-momentum distributions of protons, deuterons, and lithium using forward and backscattering geometries. In both materials, spectral discrimination of lithium-recoil features is highest in backscattering geometry, although mass isolation is also possible in the forward-scattering direction. These results evince the possibility of performing simultaneous mass-selective neutron spectroscopic studies for nuclei with m>4 amu. We also provide an in-depth analysis and assessment of departures from the harmonic and impulse approximations as described by the celebrated Sears expansion of the dynamic structure factor, as well as how these can manifest themselves in the experimental data. We close by outlining the potential of our experimental strategy for mass-selective spectroscopic studies of materials containing protons and other light nuclides.

  8. Analytical mass formula and nuclear surface properties in the ETF approximation. Part II: asymmetric nuclei

    NASA Astrophysics Data System (ADS)

    Aymard, François; Gulminelli, Francesca; Margueron, Jérôme

    2016-08-01

    We have recently addressed the problem of the determination of the nuclear surface energy for symmetric nuclei in the framework of the extended Thomas-Fermi (ETF) approximation using Skyrme functionals. We presently extend this formalism to the case of asymmetric nuclei and the question of the surface symmetry energy. We propose an approximate expression for the diffuseness and the surface energy. These quantities are analytically related to the parameters of the energy functional. In particular, the influence of the different equation of state parameters can be explicitly quantified. Detailed analyses of the different energy components (local/non-local, isoscalar/isovector, surface/curvature and higher order) are also performed. Our analytical solution of the ETF integral improves previous models and leads to a precision of better than 200 keV per nucleon in the determination of the nuclear binding energy for dripline nuclei.

  9. Analytical mass formula and nuclear surface properties in the ETF approximation. Part I: symmetric nuclei

    NASA Astrophysics Data System (ADS)

    Aymard, François; Gulminelli, Francesca; Margueron, Jérôme

    2016-08-01

    The problem of determination of nuclear surface energy is addressed within the framework of the extended Thomas Fermi (ETF) approximation using Skyrme functionals. We propose an analytical model for the density profiles with variationally determined diffuseness parameters. In this first paper, we consider the case of symmetric nuclei. In this situation, the ETF functional can be exactly integrated, leading to an analytical formula expressing the surface energy as a function of the couplings of the energy functional. The importance of non-local terms is stressed and it is shown that they cannot be deduced simply from the local part of the functional, as it was suggested in previous works.

  10. The Two-Body Problem in the Point Mass Approximation Field. II. Escape and Near-Escape Dynamics

    NASA Astrophysics Data System (ADS)

    Mioc, Vasile; Stavinschi, Magda

    The study of the two-body problem in the point mass approximation field (featured by the potential A/r+Br2, with r=distance between particles, and A, B=real nonzero constants) is continued by tackling the situation r→∞. The infinity singularity is blown up via McGehee-type transformations, and the infinity manifold is pasted on the phase space. The fictitious flow on this manifold is described, and the local flow near infinity, too.

  11. Low-energy parameters of neutron-neutron interaction in the effective-range approximation

    SciTech Connect

    Babenko, V. A.; Petrov, N. M.

    2013-06-15

    The effect of the mass difference between the charged and neutral pions on the low-energy parameters of nucleon-nucleon interaction in the {sup 1}S{sub 0} state is studied in the effective-range approximation. On the basis of experimental values of the singlet parameters of neutron-proton scattering and the experimental value of the virtual-state energy for the neutron-neutron systemin the {sup 1}S{sub 0} state, the following values were obtained for the neutron-neutron scattering length and effective range: a{sub nn} = -16.59(117) fm and r{sub nn} = 2.83(11) fm. The calculated values agree well with present-day experimental results.

  12. Electron correlation effects beyond the random phase approximation

    NASA Astrophysics Data System (ADS)

    Fan, J. D.; Malozovsky, Y. M.

    2016-04-01

    The methods that have been used to deal with a many-particle system can be basically sorted into three types: Hamiltonian, field theory and phenomenological method. The first two methods are more popular. Traditionally, the Hamiltonian method has been widely adopted in the conventional electronic theory for metals, alloys and semiconductors. Basically, the mean-field approximation (MFA) that has been working well for a weakly coupled system like a metal is employed to simplify a Hamiltonian corresponding to a particular electron system. However, for a strongly coupled many-particle system like a cuprate superconductor MFA should in principle not apply. Therefore, the field theory on the basis of Green’s function and the Feynman diagrams must be invoked. In this method, one is however more familiar with the random phase approximation (RPA) that gives rise to the same results as MFA because of being short of the information for higher-order terms of interaction. For a strongly coupled electron system, it is obvious that one has to deal with higher-order terms of a pair interaction to get a correct solution. Any ignorance of the higher-order terms implies that the more sophisticated information contained in those terms is discarded. However, to date one has not reached a consensus on how to deal with the higher-order terms beyond RPA. We preset here a method that is termed the diagrammatic iteration approach (DIA) and able to derive higher-order terms of the interaction from the information of lower-order ones on the basis of Feynman diagram, with which one is able to go beyond RPA step by step. It is in principle possible that all of higher-order terms can be obtained, and then sorted to groups of diagrams. It turns out that each of the groups can be replaced by an equivalent one, forming a diagrammatic Dyson-equation-like relation. The diagrammatic solution is eventually “translated” to a four-dimensional integral equation. The method can be applied to a

  13. Effective Masses of Vector Polarons

    NASA Astrophysics Data System (ADS)

    Foell, Charles; Clougherty, Dennis

    2006-03-01

    We consider the vector polarons of a one-dimensional model of an electron in a doubly (or nearly) degenerate band that couples to two elastic distortions, as described previously by Clougherty and Foell [1]. A variational approach is used to analytically and numerically calculate effective masses of the three types of vector polarons. [1] D. P. Clougherty and C. A. Foell, Phys. Rev. B 70, 052301 (2004).

  14. Effective medium approximation for effective propagation constant calculation in a dense random medium. [electromagnetic wave scattering

    NASA Technical Reports Server (NTRS)

    Zhu, P. Y.; Fung, A. K.

    1986-01-01

    The effective medium approximation (EMA) formalism developed for scalar wave calculations in solid state physics is generalized to electromagnetic wave scattering in a dense random medium. Results are applied to compute the effective propagation constant in a dense medium involving discrete spherical scatterers. When compared with a common quasicrystalline approximation (QCA), it is found that EMA accounts for backward scattering and the effect of correlation among three scatterers which are not available in QCA. It is also found that there is not much difference in the calculated normalized phase velocity between the use of these two approximations. However, there is a significant difference in the computed effective loss tangent in a nonabsorptive random medium. The computed effective loss tangent using EMA and measurements from a snow medium are compared, showing good agreement.

  15. Effective-range approximations for resonant scattering of cold atoms

    NASA Astrophysics Data System (ADS)

    Blackley, Caroline L.; Julienne, Paul S.; Hutson, Jeremy M.

    2014-04-01

    Studies of cold atom collisions and few-body interactions often require the energy dependence of the scattering phase shift, which is usually expressed in terms of an effective-range expansion. We use accurate coupled-channel calculations on 6Li, 39K, and 133Cs to explore the behavior of the effective range in the vicinity of both broad and narrow Feshbach resonances. We show that commonly used expressions for the effective range break down dramatically for narrow resonances and near the zero crossings of broad resonances. We present an alternative parametrization of the effective range that is accurate through both the pole and the zero crossing for both broad and narrow resonances. However, the effective-range expansion can still fail at quite low collision energies, particularly around narrow resonances. We demonstrate that an analytical form of an energy and magnetic-field-dependent phase shift, based on multichannel quantum defect theory, gives accurate results for the energy-dependent scattering length.

  16. Analytical approximation of the neutrino oscillation matter effects at large θ 13

    NASA Astrophysics Data System (ADS)

    Agarwalla, Sanjib Kumar; Kao, Yee; Takeuchi, Tatsu

    2014-04-01

    We argue that the neutrino oscillation probabilities in matter are best understood by allowing the mixing angles and mass-squared differences in the standard parametrization to `run' with the matter effect parameter a = , where N e is the electron density in matter and E is the neutrino energy. We present simple analytical approximations to these `running' parameters. We show that for the moderately large value of θ 13, as discovered by the reactor experiments, the running of the mixing angle θ 23 and the CP violating phase δ can be neglected. It simplifies the analysis of the resulting expressions for the oscillation probabilities considerably. Approaches which attempt to directly provide approximate analytical expressions for the oscillation probabilities in matter suffer in accuracy due to their reliance on expansion in θ 13, or in simplicity when higher order terms in θ 13 are included. We demonstrate the accuracy of our method by comparing it to the exact numerical result, as well as the direct approximations of Cervera et al., Akhmedov et al., Asano and Minakata, and Freund. We also discuss the utility of our approach in figuring out the required baseline lengths and neutrino energies for the oscillation probabilities to exhibit certain desirable features.

  17. Model of neutrino effective masses

    SciTech Connect

    Dinh Nguyen Dinh; Nguyen Thi Hong Van; Nguyen Anh Ky; Phi Quang Van

    2006-10-01

    It is shown that an effective (nonrenormalizable) coupling of lepton multiplets to scalar triplets in the 331 model with sterile/exotic neutrinos, can be a good way for generating neutrino masses of different types. The method is simple and avoids radiative/loop calculations which, sometimes, are long and complicated. Basing on some astrophysical arguments it is also stated that the scale of SU(3){sub L} symmetry breaking is at TeV scale, in agreement with earlier investigations. Or equivalently, starting from this symmetry breaking scale we could have sterile/exotic neutrinos with mass of a few keV's which could be used to explain several astrophysical and cosmological puzzles, such as the dark matter, the fast motion of the observed pulsars, the re-ionization of the Universe, etc.

  18. The Two-Body Problem in the Point Mass Approximation Field. I. Collision and Near-Collision Dynamics

    NASA Astrophysics Data System (ADS)

    Mioc, Vasile; Stavinschi, Magda

    Newton's theorem about the point mass approximation is fully correct only in fields with potentials of the form A/r+Br2. Here r is the distance between particles, and A, B are real parameters. A systematic qualitative study of the two-body problem in such a field is being started here. The equations of motion are written in Hamiltonian formalism, and the first integrals of energy and angular momentum are pointed out. Using McGehee's transformation, the motion equations are regularized, and the collision singularity is replaced by the collision manifold. The flow on this manifold and in its neighbourhood is depicted.

  19. Accuracy of the post-Newtonian approximation for extreme mass ratio inspirals from a black-hole perturbation approach

    NASA Astrophysics Data System (ADS)

    Sago, Norichika; Fujita, Ryuichi; Nakano, Hiroyuki

    2016-05-01

    We revisit the accuracy of the post-Newtonian (PN) approximation and its region of validity for quasicircular orbits of a point particle in the Kerr spacetime, by using an analytically known highest post-Newtonian order gravitational energy flux and accurate numerical results in the black hole perturbation approach. It is found that regions of validity become larger for higher PN order results although there are several local maximums in regions of validity for relatively low-PN order results. This might imply that higher PN order calculations are also encouraged for comparable-mass binaries.

  20. Coriolis-effect in mass flow metering

    NASA Astrophysics Data System (ADS)

    Raszillier, H.; Durst, F.

    The physical background for the so-called Coriolis mass flow meter is described. The vibration modes of a fluid conveying straight pipe segment are analyzed. These modes deviate in shape from those appearing in the absence of fluid motion. The effect of fluid inertia may be exploited for the purpose of flow measurement. The analysis is performed under a simplifying approximation: the pipe is considered as a beam, the fluid as a moving string. The equations describing the vibrations are derived variationally, with the constraint of a common vibration amplitude of both fluid and pipe. The Lagrange multiplier associated with the constraint gives the interaction force between pipe and fluid. The modes are determined by a perturbation procedure. The analysis shows how the time delay between the vibrations of two appropriately chosen points of the pipe may serve to determine the mass flow rate of the fluid. The precise role of the Coriolis force is considered. The improvements of the used approximation are discussed.

  1. Gravitational mass-shift effect in the standard model

    NASA Astrophysics Data System (ADS)

    Kazinski, P. O.

    2012-02-01

    The gravitational mass-shift effect is investigated in the framework of the standard model with the energy cutoff regularization both for stationary and nonstationary backgrounds at the one-loop level. The problem of singularity of the effective potential of the Higgs field on the horizon of a black hole, which was reported earlier, is resolved. The equations characterizing the properties of a vacuum state are derived and solved in a certain approximation for the Schwarzschild black hole. The gravitational mass-shift effect is completely described in this case. The behavior of masses of the massive particles of the standard model depends on the value of the Higgs boson mass in a flat spacetime. If the Higgs boson mass in a flat spacetime is less than 263.6 GeV then a mass of any massive particle approaching a gravitating object grows. If the Higgs boson mass in a flat spacetime is greater than or equal to 278.2 GeV, the masses of all the massive particles decrease in a strong gravitational field. The Higgs boson masses lying between these two values prove to lead to instability, at least at the one-loop level, and so they are excluded. It turns out that the vacuum possesses the same properties as an ultrarelativistic fluid in a certain approximation. The expression for the entropy and enthalpy densities and the pressure of this fluid are obtained. The sound speed in this fluid is also derived.

  2. Sub-luminous type Ia supernovae from the mergers of equal-mass white dwarfs with mass approximately 0.9M[symbol: see text].

    PubMed

    Pakmor, Rüdiger; Kromer, Markus; Röpke, Friedrich K; Sim, Stuart A; Ruiter, Ashley J; Hillebrandt, Wolfgang

    2010-01-01

    Type Ia supernovae are thought to result from thermonuclear explosions of carbon-oxygen white dwarf stars. Existing models generally explain the observed properties, with the exception of the sub-luminous 1991bg-like supernovae. It has long been suspected that the merger of two white dwarfs could give rise to a type Ia event, but hitherto simulations have failed to produce an explosion. Here we report a simulation of the merger of two equal-mass white dwarfs that leads to a sub-luminous explosion, although at the expense of requiring a single common-envelope phase, and component masses of approximately 0.9M[symbol: see text]. The light curve is too broad, but the synthesized spectra, red colour and low expansion velocities are all close to what is observed for sub-luminous 1991bg-like events. Although the mass ratios can be slightly less than one and still produce a sub-luminous event, the masses have to be in the range 0.83M[symbol: see text] to 0.9M[symbol: see text]. PMID:20054390

  3. Virtual mass effect in dynamic micromechanical mass sensing in liquids

    NASA Astrophysics Data System (ADS)

    Peiker, P.; Oesterschulze, E.

    2016-06-01

    Weighing individual micro- or nanoscale particles in solution using dynamic micromechanical sensors is quite challenging: viscous losses dramatically degrade the sensor's performance by both broadening the resonance peak and increasing the effective total mass of the resonator by the dragged liquid. While the virtual mass of the resonator was discussed frequently, little attention has been paid to the virtual mass of particles attached to the resonator's surface and its impact on the accuracy of mass sensing. By means of the in situ detection of a polystyrene microbead in water using a bridge-based microresonator, we demonstrate that the virtual mass of the bead significantly affects the observed frequency shift. In fact, 55 % of the frequency shift was caused by the virtual mass of the adsorbed bead, predicted by Stoke's theory. Based on the observed shift in the resonator's quality factor during particle adsorption, we confirm this significant effect of the virtual mass. Thus, a quantitative analysis of the mass of a single adsorbed particle is strongly diminished if dynamic micromechanical sensors are operated in a liquid environment.

  4. Surface term effects on mass estimators

    NASA Astrophysics Data System (ADS)

    Membrado, M.; Pacheco, A. F.

    2016-05-01

    Context. We propose a way of estimating the mass contained in the volume occupied by a sample of galaxies in a virialized system. Aims: We analyze the influence of surface effects and the contribution of the cosmological constant terms on our mass estimations of galaxy systems. Methods: We propose two equations that contain surface terms to estimate galaxy sample masses. When the surface terms are neglected, these equations provide the so-called virial and projected masses. Both equations lead to a single equation that allows sample masses to be estimated without the need for calculating surface terms. Sample masses for some nearest galaxy groups are estimated and compared with virialized masses determined from turn-around radii and results of a spherical infall model. Results: Surface effects have a considerable effect on the mass estimations of the studied galaxy groups. According to our results, they lead sample masses of some groups to being less than half the virial mass estimations and even less than 10% of projected mass estimations. However, the contributions of cosmological constant terms to mass estimations are smaller than 2% for the majority of the virialized groups studied. Our estimations are in agreement with virialized masses calculated from turn-around radii. Virialized masses for complexes were found to be: (8.9 ± 2.8) × 1011 M⊙ for the Milky Way - M 31; (12.5 ± 2.5) × 1011 M⊙ for M 81 - NGC 2403; (21.5 ± 7.7) × 1011 M⊙. for Cantaurs A - M 83; and (7.9 ± 2.6) × 1011 M⊙. for IC 324 - Maffei. Conclusions: The nearest galaxy groups located inside a sphere of 5 Mpc have been addressed to explore the performance of our mass estimator. We have seen that surface effects make mass estimations of galaxy groups rather smaller than both virial and projected masses. In mass calculations, cosmological constant terms can be neglected; nevertheless, the collapse of cold dark matter leading to virialized structures is strongly affected by the

  5. Mass Fractionation Laws, Mass-Independent Effects, and Isotopic Anomalies

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Schauble, Edwin A.

    2016-06-01

    Isotopic variations usually follow mass-dependent fractionation, meaning that the relative variations in isotopic ratios scale with the difference in mass of the isotopes involved (e.g., δ17O ≈ 0.5×δ18O). In detail, however, the mass dependence of isotopic variations is not always the same, and different natural processes can define distinct slopes in three-isotope diagrams. These variations are subtle, but improvements in analytical capabilities now allow precise measurement of these effects and make it possible to draw inferences about the natural processes that caused them (e.g., reaction kinetics versus equilibrium isotope exchange). Some elements, in some sample types, do not conform to the regularities of mass-dependent fractionation. Oxygen and sulfur display a rich phenomenology of mass-independent fractionation, documented in the laboratory, in the rock record, and in the modern atmosphere. Oxygen in meteorites shows isotopic variations that follow a slope-one line (δ17O ≈ δ18O) whose origin may be associated with CO photodissociation. Sulfur mass-independent fractionation in ancient sediments provides the tightest constraint on the oxygen partial pressure in the Archean and the timing of Earth's surface oxygenation. Heavier elements also show departures from mass fractionation that can be ascribed to exotic effects associated with chemical reactions such as magnetic effects (e.g., Hg) or the nuclear field shift effect (e.g., U or Tl). Some isotopic variations in meteorites and their constituents cannot be related to the terrestrial composition by any known process, including radiogenic, nucleogenic, and cosmogenic effects. Those variations have a nucleosynthetic origin, reflecting the fact that the products of stellar nucleosynthesis were not fully homogenized when the Solar System formed. Those anomalies are found at all scales, from nanometer-sized presolar grains to bulk terrestrial planets. They can be used to learn about stellar

  6. Effective Mass of an Oscillating Spring

    ERIC Educational Resources Information Center

    Rodriguez, Eduardo E.; Gesnouin, Gabriel A.

    2007-01-01

    We present an experimental method to obtain the effective mass of an unloaded oscillating spring. We measure the period "T"("n") of the partial springs that result when hanging "n" of the total "N" coils of a given spring. Data are correlated with the expectation of a simple model for "T"("n") that takes into account the effective mass of the…

  7. An analytical effective tensor and its approximation properties for upscaling flows through generalized composites

    NASA Astrophysics Data System (ADS)

    Sviercoski, R. F.

    2010-07-01

    The direct numerical simulation of flows through composites is difficult due to the fine-scale heterogeneity in the media and also due to the complexity of the dynamic systems. Thus, flow based on upscaling of the effective diffusion has become an important step in practical simulations of flow through composites. In this paper, an analytical form for computing the effective diffusion tensor is proposed when the variable coefficient is locally isotropic, K( x) = k( x) I, where k(x) is a scalar function, not necessarily periodic, and may be defined as a step function. Currently, similar results are obtained by numerical means and require a special (re)design of a numerical code and may be computationally demanding. The proposed analytical upscaled tensor approximates the one obtained from the periodic cell-problem in the context of classical homogenization theory. The diagonal values are computed by an averaging procedure of the well known Cardwell and Parsons bounds. The off-diagonals are derived from the rotation of an angle related to the center of mass of the unit cell or representative elementary volume (REV). When comparing the proposed form with various known analytical and numerical results, it shows to be accurate within less than 3% on average. The comparisons include realistic reservoirs description and analytical results, such as the concentric spheres of Hashin-Shtrikman and the two and four-phase checkerboard geometries. Moreover, convergence results corroborate theoretical ones from classical homogenization literature. Convergence is obtained by performing successive refinement from an initial coarse description of a given heterogeneous medium, which include the SPE10 comparative solution project.

  8. Effects of the Mass Media of Communication.

    ERIC Educational Resources Information Center

    Weiss, Walter

    The mass media are considered to be television, radio, movies, and newspapers. They may generate changes in cognition and comprehension. They do effect emotional arousal, sex and behavior identification, and changes in allocation of time, consumer purchase, and voting behavior. The only data which show a clear relationship between the mass media…

  9. Relativistic effects on electric properties of many-electron systems in spin-averaged Douglas-Kroll and Pauli approximations

    NASA Astrophysics Data System (ADS)

    Kellö, Vladimir; Sadlej, Andrzej J.; Hess, Bernd A.

    1996-08-01

    Relativistic effects and electron correlation effects on the dipole moments of the coinage metal hydrides are investigated and compared employing one-component (scalar) relativistic approximations based on the mass-velocity and Darwin operator and, alternatively, the Douglas-Kroll-transformed spin-averaged no-pair Hamiltonian. The former of the two operators is found to perform quite accurately for CuH and AgH. For AuH the limits of the Pauli approximation seem to be reached, as can be inferred from a comparison with the values obtained within the spin-averaged Douglas-Kroll no-pair formalism. The coupled cluster calculations in the Douglas-Kroll no-pair approximation for relativistic effects establish the dipole moment values of the coinage metal hydrides as equal to 1.05 a.u. for CuH, 1.14 a.u. for AgH and 0.52 for AuH. The corresponding non-relativistic results are 1.14 a.u., 1.36 a.u., and 1.22 a.u., respectively. Some formal problems arising in applications of the Douglas-Kroll no-pair approximation are discussed. It is shown that the Hellmann-Feynman theorem leads to a rather complicated form of the first-order energy change due to external perturbation. The usual expectation value formula is, however, valid through terms proportional to 1/c4 and can be used in most applications. The invariance property with respect to a shift in the external potential is addressed for the Douglas-Kroll no-pair approximation in a finite basis set.

  10. Measuring the Mass Distribution in Z is Approximately 0.2 Cluster Lenses with XMM, HST and CFHT

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Being the most massive gravitationally bound objects in the Universe, clusters of galaxies are prime targets for studies of structure formation and evolution. Specifically the comoving space density of virialized clusters of a given mass (or X-ray temperature), but also the frequency and degree of substructure, as well as the shape of the cluster mass profile are quantities whose current values and evolution as a function of lookback time can provide important constraints on the cosmological and physical parameters of structure formation theories. The project funded by NASA grant NAG 5-10041 intended to take such studies to a new level by combining observations of a well-selected cluster sample by three state-of-the-art telescopes: HST, to accurately measure the mass distribution in the cluster core (approx. 0.5 h(sup -1)(sub 50) Mpc) via strong gravitational lensing; CFHT, to measure the large scale mass distribution out to approx. 3 Mpc via weak lensing; and XMM, to measure the gas density and temperature distribution accurately on intermediate scales < 1.5 Mpc. XMM plays a pivotal role in this context as the calibration of X-ray mass measurements through accurate, spatially resolved X-ray temperature measurements (particularly in the cosmologically most sensitive range of kT> 5 keV) is central to the questions outlined above. This set of observations promised to yield the best cluster mass measurements obtained so far for a representative sample, thus allowing us to: 1) Measure the high-mass end of the local cluster mass function; 2) Test predictions of a universal cluster mass profile; 3) calibrate the mass-temperature and temperature-luminosity relations for clusters and the scatter around these relations, which is vital for studies of cluster evolution using the X-ray temperature and X-ray luminosity functions.

  11. An Extension of the Krieger-Li-Iafrate Approximation to the Optimized-Effective-Potential Method

    SciTech Connect

    Wilson, B.G.

    1999-11-11

    The Krieger-Li-Iafrate approximation can be expressed as the zeroth order result of an unstable iterative method for solving the integral equation form of the optimized-effective-potential method. By pre-conditioning the iterate a first order correction can be obtained which recovers the bulk of quantal oscillations missing in the zeroth order approximation. A comparison of calculated total energies are given with Krieger-Li-Iafrate, Local Density Functional, and Hyper-Hartree-Fock results for non-relativistic atoms and ions.

  12. Bias in Dobson total ozone measurements at high latitudes due to approximations in calculations of ozone absorption coefficients and air mass

    NASA Astrophysics Data System (ADS)

    Bernhard, G.; Evans, R. D.; Labow, G. J.; Oltmans, S. J.

    2005-05-01

    The Dobson spectrophotometer is the primary standard instrument for ground-based measurements of total column ozone. The accuracy of its data depends on the knowledge of ozone absorption coefficients used for data reduction. We document an error in the calculations that led to the set of absorption coefficients currently recommended by the World Meteorological Organisation (WMO). This error has little effect because an empirical adjustment was applied to the original calculations before the coefficients were adopted by WMO. We provide evidence that this adjustment was physically sound. The coefficients recommended by WMO are applied in the Dobson network without correction for the temperature dependence of the ozone absorption cross sections. On the basis of data measured by Dobson numbers 80 and 82, which were operated by the National Oceanic and Atmospheric Administration (NOAA) Climate Monitoring and Diagnostics Laboratory at the South Pole, we find that omission of temperature corrections may lead to systematic errors in Dobson ozone data of up to 4%. The standard Dobson ozone retrieval method further assumes that the ozone layer is located at a fixed height. This approximation leads to errors in air mass calculations, which are particularly relevant at high latitudes where ozone measurements are performed at large solar zenith angles (SZA). At the South Pole, systematic errors caused by this approximation may exceed 2% for SZAs larger than 80°. The bias is largest when the vertical ozone distribution is distorted by the "ozone hole" and may lead to underestimation of total ozone by 4% at SZA = 85° (air mass 9). Dobson measurements at the South Pole were compared with ozone data from a collocated SUV-100 UV spectroradiometer and Version 8 overpass data from NASA's Total Ozone Mapping Spectrometer (TOMS). Uncorrected Dobson ozone values tend to be lower than data from the two other instruments when total ozone is below 170 Dobson units or SZAs are larger than

  13. Mass partitioning effects in diffusion transport.

    PubMed

    Kojic, Milos; Milosevic, Miljan; Wu, Suhong; Blanco, Elvin; Ferrari, Mauro; Ziemys, Arturas

    2015-08-28

    Frequent mass exchange takes place in a heterogeneous environment among several phases, where mass partitioning may occur at the interface of phases. Analytical and computational methods for diffusion do not usually incorporate molecule partitioning masking the true picture of mass transport. Here we present a computational finite element methodology to calculate diffusion mass transport with a partitioning phenomenon included and the analysis of the effects of partitioning. Our numerical results showed that partitioning controls equilibrated mass distribution as expected from analytical solutions. The experimental validation of mass release from drug-loaded nanoparticles showed that partitioning might even dominate in some cases with respect to diffusion itself. The analysis of diffusion kinetics in the parameter space of partitioning and diffusivity showed that partitioning is an extremely important parameter in systems, where mass diffusivity is fast and that the concentration of nanoparticles can control payload retention inside nanoparticles. The computational and experimental results suggest that partitioning and physiochemical properties of phases play an important, if not crucial, role in diffusion transport and should be included in the studies of mass transport processes. PMID:26204522

  14. Comparisons of interacting-boson-fermion approximation and triaxial calculations for odd-mass N =80 nuclei

    SciTech Connect

    Aryaeinejad, R.; Chou, W.; McHarris, W.C. )

    1989-09-01

    The interacting-boson-fermion-approximation and triaxial models were used to calculate excitation energies and mixing ratios for the {ital N}=80 nuclei, {sup 139}Pr, {sup 141}Pm, and {sup 143}Eu. For low-lying negative- and positive-parity states both models yield roughly the same numbers, in good agreement with experimental results. For high-lying states we find that the interacting-boson-fermion-approximation model describes the level structure considerably better than the triaxial model. On the other hand, the triaxial model gives more satisfactory results in predicting the mixing ratios.

  15. The Effect of Increasing Mass upon Locomotion

    NASA Technical Reports Server (NTRS)

    DeWitt, John; Hagan, Donald

    2007-01-01

    The purpose of this investigation was to determine if increasing body mass while maintaining bodyweight would affect ground reaction forces and joint kinetics during walking and running. It was hypothesized that performing gait with increased mass while maintaining body weight would result in greater ground reaction forces, and would affect the net joint torques and work at the ankle, knee and hip when compared to gait with normal mass and bodyweight. Vertical ground reaction force was measured for ten subjects (5M/5F) during walking (1.34 m/s) and running (3.13 m/s) on a treadmill. Subjects completed one minute of locomotion at normal mass and bodyweight and at four added mass (AM) conditions (10%, 20%, 30% and 40% of body mass) in random order. Three-dimensional joint position data were collected via videography. Walking and running were analyzed separately. The addition of mass resulted in several effects. Peak impact forces and loading rates increased during walking, but decreased during running. Peak propulsive forces decreased during walking and did not change during running. Stride time increased and hip extensor angular impulse and positive work increased as mass was added for both styles of locomotion. Work increased at a greater rate during running than walking. The adaptations to additional mass that occur during walking are different than during running. Increasing mass during exercise in microgravity may be beneficial to increasing ground reaction forces during walking and strengthening hip musculature during both walking and running. Future study in true microgravity is required to determine if the adaptations found would be similar in a weightless environment.

  16. Dynamical equation of the effective gluon mass

    SciTech Connect

    Aguilar, A. C.; Binosi, D.; Papavassiliou, J.

    2011-10-15

    In this article, we derive the integral equation that controls the momentum dependence of the effective gluon mass in the Landau gauge. This is accomplished by means of a well-defined separation of the corresponding ''one-loop dressed'' Schwinger-Dyson equation into two distinct contributions, one associated with the mass and one with the standard kinetic part of the gluon. The entire construction relies on the existence of a longitudinally coupled vertex of nonperturbative origin, which enforces gauge invariance in the presence of a dynamical mass. The specific structure of the resulting mass equation, supplemented by the additional requirement of a positive-definite gluon mass, imposes a rather stringent constraint on the derivative of the gluonic dressing function, which is comfortably satisfied by the large-volume lattice data for the gluon propagator, both for SU(2) and SU(3). The numerical treatment of the mass equation, under some simplifying assumptions, is presented for the aforementioned gauge groups, giving rise to a gluon mass that is a nonmonotonic function of the momentum. Various theoretical improvements and possible future directions are briefly discussed.

  17. Phonon effects on the double mass differences in magic nuclei

    NASA Astrophysics Data System (ADS)

    Saperstein, E. E.; Baldo, M.; Gnezdilov, N. V.; Tolokonnikov, S. V.

    2016-03-01

    Odd-even double mass differences (DMDs) of magic nuclei are found within an approach starting from the free N N interaction, accounting for particle-phonon coupling (PC) effects. We consider three PC effects: the phonon-induced effective interaction, the renormalization of the "ends" due to the pole PC contribution to the nucleon mass operator, and the change of the single-particle energies. The perturbation theory in gL2, where gL is the vertex of the creation of the L -multipole phonon, is used for PC calculations. PC corrections to single-particle energies are found with an approximate accounting for the tadpole diagram. Results for magic Ca,4840, Ni,7856, Sn,132100, and 208Pb nuclei are presented. For the lighter part of this set of nuclei, from 40Ca to 56Ni, the cases divide approximately in half, between those where the PC corrections to DMD values are in good agreement with the data and the ones with the opposite result. In the major part of the cases of worsening description of DMD, a poor applicability of the perturbation theory for the induced interaction is the most probable reason of the phenomenon. For intermediate nuclei, 78Ni and 100Sn, there are no sufficiently accurate data on masses of nuclei necessary for finding DMD values. Finally, for heavier nuclei, 132Sn and 208Pb, PC corrections always result in better agreement with experiment.

  18. Spatial averaging effects of hydrophone on field characterization of planar transducer using Fresnel approximation.

    PubMed

    Xing, Guangzhen; Yang, Ping; He, Longbiao; Feng, Xiujuan

    2016-09-01

    The purpose of this work was to improve the existing models that allow spatial averaging effects of piezoelectric hydrophones to be accounted for. The model derived in the present study is valid for a planar source and was verified using transducers operating at 5 and 20MHz. It is based on Fresnel approximation and enables corrections for both on-axis and off-axis measurements. A single-integral approximate formula for the axial acoustic pressure was derived, and the validity of the Fresnel approximation in the near field of the planar transducer was examined. The numerical results obtained using 5 and 20MHz planar transmitters with an effective diameter of 12.7mm showed that the derived model could account for spatial averaging effects to within 0.2% with Beissner's exact integral (Beissner, 1981), for k(a+b)2≫π (where k is the circular wavenumber, and a and b are the effective radii of the transmitter and hydrophone, respectively). The field distributions along the acoustic axis and the beam directivity patterns are also included in the model. The spatial averaging effects of the hydrophone were generally observed to cause underestimation of the absolute pressure amplitudes of the acoustic beam, and overestimation of the cross-sectional size of the beam directivity pattern. However, the cross-sectional size of the directivity pattern was also found to be underestimated in the "far zone" (beyond Y0=a(2)/λ) of the transmitter. The results of this study indicate that the spatial averaging effect on the beam directivity pattern is negligible for π(γ(2)+4γ)s≪1 (where γ=b/a, and s is the normalized distance to the planar transducer). PMID:27268164

  19. Dielectric Matrix Formulation of Correlation Energies in the Random Phase Approximation: Inclusion of Exchange Effects.

    PubMed

    Mussard, Bastien; Rocca, Dario; Jansen, Georg; Ángyán, János G

    2016-05-10

    Starting from the general expression for the ground state correlation energy in the adiabatic-connection fluctuation-dissipation theorem (ACFDT) framework, it is shown that the dielectric matrix formulation, which is usually applied to calculate the direct random phase approximation (dRPA) correlation energy, can be used for alternative RPA expressions including exchange effects. Within this famework, the ACFDT analog of the second order screened exchange (SOSEX) approximation leads to a logarithmic formula for the correlation energy similar to the direct RPA expression. Alternatively, the contribution of the exchange can be included in the kernel used to evaluate the response functions. In this case, the use of an approximate kernel is crucial to simplify the formalism and to obtain a correlation energy in logarithmic form. Technical details of the implementation of these methods are discussed, and it is shown that one can take advantage of density fitting or Cholesky decomposition techniques to improve the computational efficiency; a discussion on the numerical quadrature made on the frequency variable is also provided. A series of test calculations on atomic correlation energies and molecular reaction energies shows that exchange effects are instrumental for improvement over direct RPA results. PMID:26986444

  20. On the two-point approximation to the effective chiral action for large solitons

    SciTech Connect

    Zuk, J.A. ); Adjali, I. )

    1992-06-20

    In this paper the two-point approximation to the effective chiral action with finite cut-off - as used to provide a low-energy soliton description of the nucleon - is studied in the limit of large soliton sizes, R. For some soliton profiles, the expectation that, in the large-R limit, the Casimir energy approaches a term linear in R with leading correction of order R{sup {minus}1} is not fulfilled. The authors classify these profiles and show that the two-point approximation can be used to elucidate the true behavior in such cases. For the linear profile, the asymptotic curve is found to run parallel to the linear kinetic energy, but displaced by an analytically computable negative constant.

  1. The Effect of Area Averaging on the Approximated Profile of the H α Spectral Line

    NASA Astrophysics Data System (ADS)

    Bodnárová, M.; Utz, D.; Rybák, J.

    2016-04-01

    The Hα line is massively used as a diagnostics of the chromosphere. Often one needs to average the line profile over some area to increase the signal to noise ratio. Thus it is important to understand how derived parameters vary with changing approximations. In this study we investigate the effect of spatial averaging of a selected area on the temporal variations of the width, the intensity and the Dopplershift of the Hα spectral line profile. The approximated profile was deduced from co-temporal observations in five points throughout the Hα line profile obtained by the tunable Lyot filter installed on the Dutch Open Telescope. We found variations of the intensity and the Doppler velocities, which were independent of the size of the area used for the computation of the area averaged Hα spectral line profile.

  2. The effects of hyper-spherical approximation of Yukawa potential to diffusion properties

    NASA Astrophysics Data System (ADS)

    Kim, In Gee; Murillo, Michael S.

    2015-11-01

    The effects of Yukawa potential to the diffusion properties of binary ionic mixtures are investigated in terms of both the classical molecular dynamics and the kinetic theory. The Yukawa interatomic potential is treated by means of the hyper-spherical approximation, which replaces the Ewald summation by a multiple of the hyperbolic trigonometric functions and the lattice summation of screening. The influence of the hyper-spherical approximation of the Yukawa potential is able to be understood through the calculations of transport coefficients with the relationship to Coulomb logarithm. Numerical studies over a various range of the Debye-Hückel screening parameter and of the plasma coupling parameter to binary ionic mixtures will be provided. We consider primarily the interdiffusion coefficients and then discuss about the mixing properties of self-diffusion coefficients.

  3. Validity of approximate methods in molecular scattering. III - Effective potential and coupled states approximations for differential and gas kinetic cross sections

    NASA Technical Reports Server (NTRS)

    Monchick, L.; Green, S.

    1977-01-01

    Two dimensionality-reducing approximations, the j sub z-conserving coupled states (sometimes called the centrifugal decoupling) method and the effective potential method, were applied to collision calculations of He with CO and with HCl. The coupled states method was found to be sensitive to the interpretation of the centrifugal angular momentum quantum number in the body-fixed frame, but the choice leading to the original McGuire-Kouri expression for the scattering amplitude - and to the simplest formulas - proved to be quite successful in reproducing differential and gas kinetic cross sections. The computationally cheaper effective potential method was much less accurate.

  4. Effective medium approximation for deeply subwavelength all-dielectric multilayers: when does it break down?

    NASA Astrophysics Data System (ADS)

    Lavrinenko, Andrei V.; Zhukovsky, Sergei V.; Andryieuski, Andrei; Takayama, Osamu; Shkondin, Evgeniy; Malureanu, Radu; Jensen, Flemming

    2016-04-01

    We report on theoretical analysis and experimental validation of the applicability of the effective medium approximation to deeply subwavelength (period ⩽λ/30) all-dielectric multilayer structures. Following the theoretical prediction of the anomalous breakdown of the effective medium approximation [H. H. Sheinfux et al., Phys. Rev. Lett. 113, 243901 (2014)] we thoroughly elaborate on regimes, when an actual multilayer stack exhibits significantly different properties compared to its homogenized model. Our findings are fully confirmed in the first direct experimental demonstration of the breakdown effect. Multilayer stacks are composed of alternating alumina and titania layers fabricated using atomic layer deposition. For light incident on such multilayers at angles near the total internal reflection, we observe pronounced differences in the reflectance spectra (up to 0.5) for structures with different layers ordering and different but still deeply subwavelength thicknesses. Such big reflectance difference values resulted from the special geometrical configuration with an additional resonator layer underneath the multilayers employed for the enhancement of the effect. Our results are important for the development of new homogenization approaches for metamaterials, high-precision multilayer ellipsometry methods and in a broad range of sensing applications.

  5. On The Effectiveness Of The Negative Binomial Approximation In A Multi-Echelon Inventory Model: A Mathematical Analysis

    NASA Astrophysics Data System (ADS)

    Solis, Adriano O.; Schmidt, Charles P.; Conerly, Michael D.

    2007-09-01

    Graves (1996) developed a multi-echelon inventory model and used a negative binomial distribution to approximate the distribution of a random variable in the model. Two earlier multi-echelon inventory studies (Graves, 1985; Lee and Moinzadeh, 1987) have similarly used negative binomial approximations. Only computational evidence has been offered in support of the approximations. We provide, for the latest model (Graves, 1996), a mathematical analysis of the effectiveness of such an approximation.

  6. Degeneracy effects of neutrino mass ejection in supernovae

    NASA Technical Reports Server (NTRS)

    Mazurek, T. J.

    1974-01-01

    A neutrino mechanism is discussed in order to explain supernovae in massive stars. An argument is presented for supernova mass ejection through leptonic neutrino transport characteristics suppressed by the arbitrary zero chemical potential condition. Results show that lepton conservation effects may be important in supernova neutrino transport. At low temperature and density the diffusion approximation becomes less precise because of the long mean free paths of low energy neutrinos. The amount of equilibrium neutrino spectrum affected here is small over most of the collapsing supernova structure.

  7. Rough-surface effects on incoherent scattering from random volumetric scatterers: Approximate analytic series solution

    SciTech Connect

    Bilgen, M.; Rose, J.H. )

    1994-11-01

    An approximate analytic series solution is obtained for the effects of randomly rough surfaces on the time-dependent ultrasonic backscatter that are due to beam-microstructure interactions. The transmission of sound through the rough surface is modeled by scalar waves by use of the phase-screen and Fresnel approximations, whereas the transducer is assumed to produce a focused normally oriented Gaussian beam. The beam-microstructure interaction is described by a simple, generic model that attributes backscattering to inhomogeneities in the elastic constants of the sample; density variations are ignored. Key predictions of the approximate series solution are that (a) acoustic backscatter is relatively insensitive to surface roughness for unfocused probes, (b) roughness can dramatically reduce the backscatter noise seen by focused probes, (c) backscatter is increased at early times because of weak localization, and (d) backscatter is reduced at late times because of increased diffraction. The predictions of the series solution are briefly compared with available experiment. 32 refs., 10 figs.

  8. Mass transfer effects in a gasification riser

    SciTech Connect

    Breault, Ronald W; Li, Tingwen; Nicoletti, Phillip

    2013-01-01

    In the development of multiphase reacting computational fluid dynamics (CFD) codes, a number of simplifications were incorporated into the codes and models. One of these simplifications was the use of a simplistic mass transfer correlation for the faster reactions and omission of mass transfer effects completely on the moderate speed and slow speed reactions such as those in a fluidized bed gasifier. Another problem that has propagated is that the mass transfer correlation used in the codes is not universal and is being used far from its developed bubbling fluidized bed regime when applied to circulating fluidized bed (CFB) riser reactors. These problems are true for the major CFD codes. To alleviate this problem, a mechanistic based mass transfer coefficient algorithm has been developed based upon an earlier work by Breault et al. This fundamental approach uses the local hydrodynamics to predict a local, time varying mass transfer coefficient. The predicted mass transfer coefficients and the corresponding Sherwood numbers agree well with literature data and are typically about an order of magnitude lower than the correlation noted above. The incorporation of the new mass transfer model gives the expected behavior for all the gasification reactions evaluated in the paper. At the expected and typical design values for the solid flow rate in a CFB riser gasifier an ANOVA analysis has shown the predictions from the new code to be significantly different from the original code predictions. The new algorithm should be used such that the conversions are not over predicted. Additionally, its behaviors with changes in solid flow rate are consistent with the changes in the hydrodynamics.

  9. The effects of body mass on cremation weight.

    PubMed

    May, Shannon E

    2011-01-01

    Cremains have become increasingly frequent in forensic contexts, while higher body mass in the general population has simultaneously made cremation a more cost-effective mortuary practice. This study analyzed the relationship between body mass and bone mass, as reflected through cremation weight. Antemortem data were recorded for samples used in the multi-regional data set. Each was rendered through commercial crematoriums and reweighed postincineration. Pearson's correlation demonstrates clear association between body mass and cremation weight (r=0.56; p<0.0001). However, multiple linear regression revealed sex and age variables also have a significant relationship (t=7.198; t=-2.5, respectively). Regressed in conjunction, body mass, sex, and age contribute approximately 67% of all variation observed in cremation weight (r=0.668). Analysis of covariance indicates significant regional variation in body and cremation weight. Explanations include bone modification resulting from increased loading stress, as well as glucose intolerance and altered metabolic pathways related to obesity. PMID:20735701

  10. Gravitational and mass distribution effects on stationary superwinds.

    NASA Astrophysics Data System (ADS)

    Añorve-Zeferino, G. A.

    2016-08-01

    Here, we model the effect of non-uniform dynamical mass distributions and their associated gravitational fields on the stationary galactic superwind solution. We do this by considering an analogue injection of mass and energy from stellar winds and SNe. We consider both compact dark-matter and baryonic haloes that does not extend further from the galaxies optical radii Ropt as well as extended gravitationally-interacting ones. We consider halo profiles that emulate the results of recent cosmological simulations and coincide also with observational estimations from galaxy surveys. This allows to compare the analytical superwind solution with outflows from different kinds of galaxies. We give analytical formulae that establish when an outflow is possible and also characterize distinct flow regimes and enrichment scenarios. We also constraint the parameter space by giving approximate limits above which gravitation, self-gravitation and radiative cooling can inhibit the stationary flow. We obtain analytical expressions for the free superwind hydrodynamical profiles. We find that the existence or inhibition of the superwind solution highly depends on the steepness and concentration of the dynamical mass and the mass and energy injection rates. We compare our results with observational data and a recent numerical work. We put our results in the context of the mass-metallicity relationship to discuss observational evidence related to the selective loss of metals from the least massive galaxies and also discuss the case of massive galaxies.

  11. Improving the In-Medium Similarity Renormalization Group via approximate inclusion of three-body effects

    NASA Astrophysics Data System (ADS)

    Morris, Titus; Bogner, Scott

    2015-10-01

    The In-Medium Similarity Renormalization Group (IM-SRG) has been applied successfully not only to several closed shell finite nuclei, but has recently been used to produce effective shell model interactions that are competitive with phenomenological interactions in the SD shell. A recent alternative method for solving of the IM-SRG equations, called the Magnus expansion, not only provides a computationally feasible route to producing observables, but also allows for approximate handling of induced three-body forces. Promising results for several systems, including finite nuclei, will be presented and discussed.

  12. p-barp-Annihilation processes in the tree approximation of SU(3) chiral effective theory

    SciTech Connect

    Tarasov, V. E.; Kudryavtsev, A. E. Romanov, A. I.; Weinberg, V. M.

    2012-12-15

    The p-barp-annihilation reactions p-barp {yields} {eta}{eta} {eta} and p-barp {yields} {eta}KK-bar at rest are considered in the tree approximation in the framework of SU(3) chiral effective theory at leading order. The calculated branchings are compared with the data. The results for neutral ({eta}{eta}{eta}, K{sup 0}K-bar{sup 0}{sub {eta}}) and charged (K{sup +}K{sup -}{sub {eta}}) channels are essentially different.

  13. Effects beyond the random-phase approximation in calculating the interaction between metal films

    NASA Astrophysics Data System (ADS)

    Jung, J.; García-González, P.; Dobson, J. F.; Godby, R. W.

    2004-11-01

    The performance of the adiabatic-connection fluctuation-dissipation theorem is discussed through the implementation of a non-local energy optimized exchange-correlation kernel to account for short-range correlation effects. We evaluate the jellium surface energy, through a painstaking extrapolation of single slab calculations, as well as the binding and interaction energies between two and three jellium slabs. Whereas total electron correlation energies are rather sensitive to the details of the kernel, any physically well-motivated approximation within our framework describes binding energies (including surface energies) within the same level of accuracy.

  14. Diffusive superconductors beyond the Usadel approximation: Electron-hole asymmetry and large photoelectric effect

    NASA Astrophysics Data System (ADS)

    Kalenkov, Mikhail S.; Zaikin, Andrei D.

    2015-07-01

    We extend the quasiclassical formalism for diffusive superconductors by deriving anisotropic (gradient) corrections to the Usadel equation. We demonstrate that in a number of physical situations such corrections may play a crucial role, being responsible for the effects which cannot be recovered within the standard Usadel approximation. One of them is the so-called photoelectric effect in superconductors and superconducting-normal (SN) hybrid structures. Provided a superconducting part of the system is irradiated by an external ac electromagnetic field, the charge imbalance develops and a nonvanishing dc voltage is induced across the SN interface. In the presence of magnetic impurities in a superconductor the magnitude of this effect becomes large and can easily be detected in modern experiments.

  15. Effective-medium approximation for lattice random walks with long-range jumps.

    PubMed

    Thiel, Felix; Sokolov, Igor M

    2016-07-01

    We consider the random walk on a lattice with random transition rates and arbitrarily long-range jumps. We employ Bruggeman's effective-medium approximation (EMA) to find the disorder-averaged (coarse-grained) dynamics. The EMA procedure replaces the disordered system with a cleverly guessed reference system in a self-consistent manner. We give necessary conditions on the reference system and discuss possible physical mechanisms of anomalous diffusion. In the case of a power-law scaling between transition rates and distance, lattice variants of Lévy-flights emerge as the effective medium, and the problem is solved analytically, bearing the effective anomalous diffusivity. Finally, we discuss several example distributions and demonstrate very good agreement with numerical simulations. PMID:27575104

  16. Effective-medium approximation for lattice random walks with long-range jumps

    NASA Astrophysics Data System (ADS)

    Thiel, Felix; Sokolov, Igor M.

    2016-07-01

    We consider the random walk on a lattice with random transition rates and arbitrarily long-range jumps. We employ Bruggeman's effective-medium approximation (EMA) to find the disorder-averaged (coarse-grained) dynamics. The EMA procedure replaces the disordered system with a cleverly guessed reference system in a self-consistent manner. We give necessary conditions on the reference system and discuss possible physical mechanisms of anomalous diffusion. In the case of a power-law scaling between transition rates and distance, lattice variants of Lévy-flights emerge as the effective medium, and the problem is solved analytically, bearing the effective anomalous diffusivity. Finally, we discuss several example distributions and demonstrate very good agreement with numerical simulations.

  17. Isotopic mass and alpha heating effects in TFTR DT plasmas

    SciTech Connect

    Budny, R.V.; Bell, M.G.; Mansfield, D.K.

    1994-09-01

    Sets of similar TFTR discharges with varying amounts of D and T are compared. The T content is altered by varying the mix of D and T NBI at approximately constant total NBI power. The total plasma current, toroidal field, central Z{sub eff}, and wall conditions are very similar in each set. The electron density profiles are approximately similar. The sets contain pairs of discharges with D-only and DT-NBI. Several sets also contain discharges with T-only NBI. The discharges are analyzed using the TRANSP plasma analysis code. Good agreement with measured parameters is achieved. Profiles are computed for the isotopic mass of the hydrogenic thermal species A, and for the hydrogenic thermal plus beam species A{sub tot}. Their volume averages increase approximately linearly as the fraction of T-NBI power increases, and they are slightly peaked for DT and T-only NBI discharges. The total energy and the total energy confinement time increase approximately linearly with A{sub tot} up to 30%. The beam fraction of the total energy at 0.5 sec of NBI remains relatively constant, {approx} 40--50% as A{sub tot} varies. The thermal ion fraction increases slightly, and the electron fraction decreases. The isotopic and alpha heating effects contribute in roughly equal amounts to the increase in central T{sub e}.

  18. Slope-dependent nuclear-symmetry energy within the effective-surface approximation

    NASA Astrophysics Data System (ADS)

    Blocki, J. P.; Magner, A. G.; Ring, P.

    2015-12-01

    The effective-surface approximation is extended taking into account derivatives of the symmetry-energy density per particle with respect to the mean particle density. The isoscalar and isovector particle densities in this extended effective-surface approximation are derived. The improved expressions of the surface symmetry energy, in particular, its surface tension coefficients in the sharp-edged proton-neutron asymmetric nuclei take into account important gradient terms of the energy density functional. For most Skyrme forces the surface symmetry-energy constants and the corresponding neutron skins and isovector stiffnesses are calculated as functions of the Swiatecki derivative of the nongradient term of the symmetry-energy density per particle with respect to the isoscalar density. Using the analytical isovector surface-energy constants in the framework of the Fermi-liquid droplet model we find energies and sum rules of the isovector giant dipole-resonance structure in a reasonable agreement with the experimental data, and they are compared with other theoretical approaches.

  19. Approximate techniques for predicting size effects on cleavage fracture toughness (J{sub c})

    SciTech Connect

    Kirk, M.T.; Dodds, R.H. Jr.

    1993-07-01

    This investigation examines the ability of an elastic T-stress analysis coupled with modified boundary layer (MBL) solution to predict stresses ahead of a crack tip in a variety of planar geometries. The approximate stresses are used as input to estimate the effective driving force for cleavage fracture (J{sub 0}) using the micromechanically based approach introduced by Dodds and Anderson. Finite element analyses for a wide variety of planar cracked geometries are conducted which have elastic biaxiality parameters ({beta}) ranging from {minus}0.99 (very low constraint) to +2.96 (very high constraint). The magnitude and sign of {beta} indicate the rate at which crack-tip constraint changes with increasing applied load. All results pertain to a moderately strain hardening material (strain hardening exponent ({eta}) of 10). These analyses suggest that {beta} is an effective indicator of both the accuracy of T-MBL estimates of J{sub 0} and of applicability limits on evolving fracture analysis methodologies (i.e. T-MBL, J-Q, and J/J{sub 0}). Specifically, when 1{beta}1>0.4 these analyses show that the T-MBL approximation of J{sub 0} is accurate to within 20% of a detailed finite-element analysis. As ``structural type`` configurations, i.e. shallow cracks in tension, generally have 1{beta}1>0.4, it appears that only an elastic analysis may be needed to determine reasonably accurate J{sub 0} values for structural conditions.

  20. The Ill-Effects of Traditional Approximation in Exoplanet Atmospheric Flow Modeling

    NASA Astrophysics Data System (ADS)

    Cho, J. Y.-K.; Polichtchouk, I.

    2011-10-01

    We investigate the effects of imposing the traditional approximation restriction in large-scale atmospheric flow models of exoplanets. In the traditional hydrostatic primitive equations, solved by general circulation and global climate models, terms associated with the horizontal components of the Coriolis acceleration and the metric terms are omitted. However, scale analysis suggests that the neglected terms may be up to ˜20% of the included terms in the traditional equations. In this work, we enhance a well-tested general circulation model to include the omitted terms consistently. In direct comparisons of simulations appropriate for hot extrasolar giant planets, we demonstrate a significant difference when the terms normally neglected in the approximation are retained; for example, large warm/cool regions (of up to ˜300K) persist and large-scale jets disappear. The effect is most prominent when rotation does not strongly suppress vertical motion, as in most close-in exoplanets. It is also prominent during the early stages of any planet simulation, in which the atmosphere/climate is spun up from rest.

  1. Observation of large, non-covalent globin subassemblies in the approximately 3600 kDa hexagonal bilayer hemoglobins by electrospray ionization time-of-flight mass spectrometry.

    PubMed

    Green, B N; Gotoh, T; Suzuki, T; Zal, F; Lallier, F H; Toulmond, A; Vinogradov, S N

    2001-06-01

    A non-covalent globin subassembly comprising 12 globin chains (204 to 214 kDa) was observed directly by electrospray ionization time-of-flight mass spectrometry in the native hexagonal bilayer hemoglobins from the oligochaetes Lumbricus terrestris and Tubifex tubifex, the polychaetes Tylorrhynchus heterochaetus, Arenicola marina, Amphitrite ornata and Alvinella pompejana, the leeches Macrobdella decora, Haemopis grandis and Nephelopsis oscura and the chlorocruorin from the polychaete Myxicola infundibulum, over the pH range 3.5-7.0. The Hb from the deep-sea polychaete Alvinella exhibited in addition, peaks at approximately 107 kDa and at approximately 285 kDa, which were assigned to subassemblies of six globin chains and of 12 globin chains with three non-globin linker chains, respectively. The experimental masses decreased slightly with increased de-clustering potential (60 to 160 V) and were generally 0.1 to 0.2 % higher than the calculated masses, due probably to complexation with cations and water molecules. PMID:11397079

  2. On the unreasonable effectiveness of the post-Newtonian approximation in gravitational physics

    PubMed Central

    Will, Clifford M.

    2011-01-01

    The post-Newtonian approximation is a method for solving Einstein’s field equations for physical systems in which motions are slow compared to the speed of light and where gravitational fields are weak. Yet it has proven to be remarkably effective in describing certain strong-field, fast-motion systems, including binary pulsars containing dense neutron stars and binary black hole systems inspiraling toward a final merger. The reasons for this effectiveness are largely unknown. When carried to high orders in the post-Newtonian sequence, predictions for the gravitational-wave signal from inspiraling compact binaries will play a key role in gravitational-wave detection by laser-interferometric observatories. PMID:21447714

  3. Phase velocity and attenuation predictions of waves in cancellous bone using an iterative effective medium approximation.

    PubMed

    Potsika, Vassiliki T; Protopappas, Vasilios C; Vavva, Maria G; Polyzos, Demosthenes; Fotiadis, Dimitrios I

    2013-01-01

    The quantitative determination of wave dispersion and attenuation in bone is an open research area as the factors responsible for ultrasound absorption and scattering in composite biological tissues have not been completely explained. In this study, we use the iterative effective medium approximation (IEMA) proposed in [1] so as to calculate phase velocity and attenuation in media with properties similar to those of cancellous bones. Calculations are performed for a frequency range of 0.4-0.8 MHz and for different inclusions' volume concentrations and sizes. Our numerical results are compared with previous experimental findings so as to assess the effectiveness of IEMA. It was made clear that attenuation and phase velocity estimations could provide supplementary information for cancellous bone characterization. PMID:24111396

  4. Effects of different wave free surface approximations on the response of a TLP in deep water

    SciTech Connect

    Mekha, B.B.; Johnson, C.P.; Roesset, J.M.

    1994-12-31

    This paper is based on work conducted at the Offshore Technology Research Center to investigate the relative importance of different types of nonlinearities on the dynamic response of tension leg platforms. A time domain solution using Morison`s equation with several modifications and allowing to include or neglect various sources of nonlinearities was implemented and used in the dynamic analysis. This paper focuses on the non-linear effect of evaluating the wave forces up to the free surface using different approximate methods. A TLP hull model with time varying tendon forces is subjected to regular and irregular waves with and without current. The effects on calculating the wave kinematics up to the mean water level or up to the actual free surface, making use of various extrapolation or stretching techniques are then discussed.

  5. Missing mass effect in biosensor's QCM applications.

    PubMed

    Voinova, M V; Jonson, M; Kasemo, B

    2002-10-01

    Nowadays, liquid applications of quartz crystal microbalance (QCM) opened a way for in situ studies of proteins, vesicles and cells adsorbed from the solution onto the QCM surface. The sensitivity of QCM to the viscoelasticity of the adsorbed biomaterial can be a reason of the experimentally observed deviation from a linear dependence of QCM resonant frequency on mass deposition (the so-called Sauerbrey relation) and can limit its application for biosensoring. Presented here rigorous theoretical analysis explains the deviation from ideal mass response of soft overlayers in the contact with liquid. The fundamental result of the theory is the analog of Sauerbrey relation for layered viscous/viscoelastic medium which can be exploited for the correct physical interpretation of QCM experimental data in biofluids, in particular for measurements of the 'true' surface mass of adsorbed biomolecular films. We predict a new physical effect 'missing mass' of the sample in liquid phase measurements and compare the results given by our theory with QCM measurements on supported membranes. PMID:12243901

  6. Systematic approximations to the optimized effective potential: Application to orbital-density-functional theory

    NASA Astrophysics Data System (ADS)

    Krieger, J. B.; Li, Yan; Iafrate, G. J.

    1992-11-01

    The integral equation originally derived by Sharp and Horton for the optimized effective potential (OEP) is exactly transformed into an equivalent form from which it is manifestly clear that the OEP, V0xσ(r), is an implicit functional of only \\{niσ\\}, the orbital densities of the occupied states \\{ψiσ\\}, and the corresponding single-particle exchange potentials \\{viσ\\}. Furthermore, the transformed OEP has exactly the same form as one recently developed by the authors [Phys. Rev. A 45, 101 (1992)] from a more heuristic approach, the only difference being that in the present work a term proportional to the gradient of niσ is added to each viσ whose average value when taken over the iσ state is zero. This result leads to the natural development of an iterative approximation for V0xσ, with the zeroth approximation being given by our previous result. The application of this technique to the calculation of the total energy and highest-energy single-particle eigenvalue for selected atoms is presented. In addition, we note that our results are applicable to the calculation of the OEP for any assumed exchange-correlation functional Exc[\\{ψiσ\\}], where viσ is taken as the appropriate functional derivative of Exc. In the case that Exc is a functional of \\{niσ\\} only, as in the case of the local-density approximation with self-interaction correction, the resulting V0xcσ is a functional of the \\{niσ\\} only.

  7. Thermal conductivity in porous media: Percolation-based effective-medium approximation

    NASA Astrophysics Data System (ADS)

    Ghanbarian, Behzad; Daigle, Hugh

    2016-01-01

    Knowledge of porosity and saturation-dependent thermal conductivities is necessary to investigate heat and water transfer in natural porous media such as rocks and soils. Thermal conductivity in a porous medium is affected by the complicated relationship between the topology and geometry of the pore space and the solid matrix. However, as water content increases from completely dry to fully saturated, the effect of the liquid phase on thermal conductivity may increase substantially. Although various methods have been proposed to model the porosity and saturation dependence of thermal conductivity, most are empirical or quasiphysical. In this study, we present a theoretical upscaling framework from percolation theory and the effective-medium approximation, which is called percolation-based effective-medium approximation (P-EMA). The proposed model predicts the thermal conductivity in porous media from endmember properties (e.g., air, solid matrix, and saturating fluid thermal conductivities), a scaling exponent, and a percolation threshold. In order to evaluate our porosity and saturation-dependent models, we compare our theory with 193 porosity-dependent thermal conductivity measurements and 25 saturation-dependent thermal conductivity data sets and find excellent match. We also find values for the scaling exponent different than the universal value of 2, in insulator-conductor systems, and also different from 0.76, the exponent in conductor-superconductor mixtures, in three dimensions. These results indicate that the thermal conductivity under fully and partially saturated conditions conforms to nonuniversal behavior. This means the value of the scaling exponent changes from medium to medium and depends not only on structural and geometrical properties of the medium but also characteristics (e.g., wetting or nonwetting) of the saturating fluid.

  8. Effects of Approximate Filtering on the Appearance of Bidirectional Texture Functions.

    PubMed

    Jarabo, Adrian; Wu, Hongzhi; Dorsey, Julie; Rushmeier, Holly; Gutierrez, Diego

    2014-06-01

    The BTF data structure was a breakthrough for appearance modeling in computer graphics. More research is needed though to make BTFs practical in rendering applications. We present the first systematic study of the effects of Approximate filtering on the appearance of BTFs, by exploring the spatial, angular and temporal domains over a varied set of stimuli. We perform our initial experiments on simple geometry and lighting, and verify our observations on more complex settings. We consider multi-dimensional filtering versus conventional mipmapping, and find that multi-dimensional filtering produces superior results. We examine the tradeoff between under- and oversampling, and find that different filtering strategies can be applied in each domain, while maintaining visual equivalence with respect to a ground truth. For example, we find that preserving contrast is more important in static than dynamic images, indicating greater levels of spatial filtering are possible for animations. We find that filtering can be performed more aggressively in the angular domain than in the spatial. Additionally, we find that high-level visual descriptors of the BTF are linked to the perceptual performance of pre-filtered approximations. In turn, some of these high-level descriptors correlate with low level statistics of the BTF. We show six different practical applications of applying our findings to improving filtering, rendering and compression strategies. PMID:26357305

  9. The optimized effective potential of meta-generalized gradient approximations in solids

    NASA Astrophysics Data System (ADS)

    Yang, Zenghui; Perdew, John

    Unlike the local density approximation(LDA) and the generalized gradient approximation(GGA), calculations with meta-GGAs are usually done according to the generalized Kohn-Sham(gKS) formalism. The exchange-correlation potential of the gKS equation is non-multiplicative, which prevents systematic comparison of meta-GGA bandstructures to those of the LDA and the GGA. We implement the optimized effective potential(OEP) of the meta-GGA for periodic systems, which allows us to carry out meta-GGA calculations in the same KS manner as for the LDA and the GGA. We apply the OEP to several popular meta-GGAs, including the new SCAN functional[Phys. Rev. Lett. 115, 036402 (2015)]. We find that the KS gaps of meta-GGAs are close to those of GGAs, and they are smaller than the gKS gaps of meta-GGAs. The well-known grid sensitivity of meta-GGAs is much more severe in OEP calculations. The authors are supported by the National Science Foundation(Grant No. DMR-1305135).

  10. Anomalous scaling in magnetohydrodynamic turbulence: Effects of anisotropy and compressibility in the kinematic approximation

    NASA Astrophysics Data System (ADS)

    Antonov, N. V.; Kostenko, M. M.

    2015-11-01

    The field-theoretic renormalization group and the operator product expansion are applied to the model of passive vector (magnetic) field advected by a random turbulent velocity field. The latter is governed by the Navier-Stokes equation for compressible fluid, subject to external random force with the covariance ∝δ (t -t') k4 -d -y , where d is the dimension of space and y is an arbitrary exponent. From physics viewpoints, the model describes magnetohydrodynamic turbulence in the so-called kinematic approximation, where the effects of the magnetic field on the dynamics of the fluid are neglected. The original stochastic problem is reformulated as a multiplicatively renormalizable field-theoretic model; the corresponding renormalization group equations possess an infrared attractive fixed point. It is shown that various correlation functions of the magnetic field and its powers demonstrate anomalous scaling behavior in the inertial-convective range already for small values of y . The corresponding anomalous exponents, identified with scaling (critical) dimensions of certain composite fields ("operators" in the quantum-field terminology), can be systematically calculated as series in y . The practical calculation is performed in the leading one-loop approximation, including exponents in anisotropic contributions. It should be emphasized that, in contrast to Gaussian ensembles with finite correlation time, the model and the perturbation theory presented here are manifestly Galilean covariant.

  11. Anomalous scaling in magnetohydrodynamic turbulence: Effects of anisotropy and compressibility in the kinematic approximation.

    PubMed

    Antonov, N V; Kostenko, M M

    2015-11-01

    The field-theoretic renormalization group and the operator product expansion are applied to the model of passive vector (magnetic) field advected by a random turbulent velocity field. The latter is governed by the Navier-Stokes equation for compressible fluid, subject to external random force with the covariance ∝ δ(t-t')k(4-d-y), where d is the dimension of space and y is an arbitrary exponent. From physics viewpoints, the model describes magnetohydrodynamic turbulence in the so-called kinematic approximation, where the effects of the magnetic field on the dynamics of the fluid are neglected. The original stochastic problem is reformulated as a multiplicatively renormalizable field-theoretic model; the corresponding renormalization group equations possess an infrared attractive fixed point. It is shown that various correlation functions of the magnetic field and its powers demonstrate anomalous scaling behavior in the inertial-convective range already for small values of y. The corresponding anomalous exponents, identified with scaling (critical) dimensions of certain composite fields ("operators" in the quantum-field terminology), can be systematically calculated as series in y. The practical calculation is performed in the leading one-loop approximation, including exponents in anisotropic contributions. It should be emphasized that, in contrast to Gaussian ensembles with finite correlation time, the model and the perturbation theory presented here are manifestly Galilean covariant. PMID:26651785

  12. Spin contamination for Hartree-Fock, optimized effective potential, and density functional approximations.

    PubMed

    Theophilou, Iris; Thanos, S; Theophilou, A K

    2007-12-21

    In an earlier paper [S. Thanos and A. K. Theophilou J. Chem. Phys. 124, 204109 (2006)], we found an explicit formula for the expansion of a Slater determinant |Phi(M)> in terms of eigenstates of S(2). In this paper, we use the same formula to determine the spin contamination S(con) of the unrestricted single determinant approximations, i.e., Hartree-Fock, optimized effective potential, and density functional theory. We derived an expression which gives S(con) in terms of the overlap of the spatial parts of the spin up and spin down "corresponding" orbitals. It was found that S(con) does not depend on M, the eigenvalue of S(z), at least for the lower order approximations, i.e., when || is large. In this case, the predominant coefficient of the expansion assumes its maximum value when S=M. However, for the class of solutions that || is small, the spin L of the largest coefficient increases with the number of unpaired electrons. We also derived the explicit form of the expansion states. PMID:18154371

  13. Parametric effects of CFL number and artificial smoothing on numerical solutions using implicit approximate factorization algorithm

    NASA Technical Reports Server (NTRS)

    Daso, E. O.

    1986-01-01

    An implicit approximate factorization algorithm is employed to quantify the parametric effects of Courant number and artificial smoothing on numerical solutions of the unsteady 3-D Euler equations for a windmilling propeller (low speed) flow field. The results show that propeller global or performance chracteristics vary strongly with Courant number and artificial dissipation parameters, though the variation is such less severe at high Courant numbers. Candidate sets of Courant number and dissipation parameters could result in parameter-dependent solutions. Parameter-independent numerical solutions can be obtained if low values of the dissipation parameter-time step ratio are used in the computations. Furthermore, it is realized that too much artificial damping can degrade numerical stability. Finally, it is demonstrated that highly resolved meshes may, in some cases, delay convergence, thereby suggesting some optimum cell size for a given flow solution. It is suspected that improper boundary treatment may account for the cell size constraint.

  14. Casimir effect for curved geometries: proximity-force-approximation validity limits.

    PubMed

    Gies, Holger; Klingmüller, Klaus

    2006-06-01

    We compute Casimir interaction energies for the sphere-plate and cylinder-plate configuration induced by scalar-field fluctuations with Dirichlet boundary conditions. Based on a high-precision calculation using world-line numerics, we quantitatively determine the validity bounds of the proximity-force approximation (PFA) on which the comparison between all corresponding experiments and theory are based. We observe the quantitative failure of the PFA on the 1% level for a curvature parameter a/R>0.00755. Even qualitatively, the PFA fails to predict reliably the correct sign of genuine Casimir curvature effects. We conclude that data analysis of future experiments aiming at a precision of 0.1% must no longer be based on the PFA. PMID:16803290

  15. Fluctuations of spherical waves in a turbulent atmosphere: effect of the axisymmetric approximation in computational methods.

    PubMed

    Salomons, E M

    2000-10-01

    The validity of the axisymmetric parabolic-equation (PE) method for line-of-sight sound propagation in a turbulent atmosphere is investigated. The axisymmetric PE method is a finite-difference method for solving a 2D parabolic wave equation, which follows from the 3D wave equation by the assumption of axial symmetry around the vertical axis through the source. It is found that this axisymmetric approximation has a considerable spurious effect on the fluctuations of the sound field. This is concluded from analytical expressions for the log-amplitude and phase variances, derived both for isotropic turbulence and for axisymmetric turbulence. The expressions for axisymmetric turbulence are compared with the results of numerical computations with the PE method. PMID:11051480

  16. Feasibility study of using a two-plate model to approximate the TDRSS solar pressure effects

    NASA Technical Reports Server (NTRS)

    Chan, F. K.

    1980-01-01

    An investigation was performed to determine the feasibility of using a two plate model to approximate the Tracking and Data Relay Satellite (TDRS) in orbit propagation, taking into account the effects of solar radiation pressure. The two plate model comprises one plate which always points to the Earth, and the other which is hinged to an axis normal to the orbital plane and is always rotated so that its normal makes a minimum angle with the direction of the sun. The results indicate that it is sufficient to take three parameters, the areas of the two plates and the reflectivity of the Earth pointing plate, to achieve an accuracy of one meter during a 24 hour orbit propagation.

  17. Applicability of the effective-medium approximation to heterogeneous aerosol particles

    NASA Astrophysics Data System (ADS)

    Mishchenko, Michael I.; Dlugach, Janna M.; Liu, Li

    2016-07-01

    The effective-medium approximation (EMA) is based on the assumption that a heterogeneous particle can have a homogeneous counterpart possessing similar scattering and absorption properties. We analyze the numerical accuracy of the EMA by comparing superposition T-matrix computations for spherical aerosol particles filled with numerous randomly distributed small inclusions and Lorenz-Mie computations based on the Maxwell-Garnett mixing rule. We verify numerically that the EMA can indeed be realized for inclusion size parameters smaller than a threshold value. The threshold size parameter depends on the refractive-index contrast between the host and inclusion materials and quite often does not exceed several tenths, especially in calculations of the scattering matrix and the absorption cross section. As the inclusion size parameter approaches the threshold value, the scattering-matrix errors of the EMA start to grow with increasing the host size parameter and/or the number of inclusions. We confirm, in particular, the existence of the effective-medium regime in the important case of dust aerosols with hematite or air-bubble inclusions, but then the large refractive-index contrast necessitates inclusion size parameters of the order of a few tenths. Irrespective of the highly restricted conditions of applicability of the EMA, our results provide further evidence that the effective-medium regime must be a direct corollary of the macroscopic Maxwell equations under specific assumptions.

  18. Approximation to the Distribution of Fitness Effects across Functional Categories in Human Segregating Polymorphisms

    PubMed Central

    Racimo, Fernando; Schraiber, Joshua G.

    2014-01-01

    Quantifying the proportion of polymorphic mutations that are deleterious or neutral is of fundamental importance to our understanding of evolution, disease genetics and the maintenance of variation genome-wide. Here, we develop an approximation to the distribution of fitness effects (DFE) of segregating single-nucleotide mutations in humans. Unlike previous methods, we do not assume that synonymous mutations are neutral or not strongly selected, and we do not rely on fitting the DFE of all new nonsynonymous mutations to a single probability distribution, which is poorly motivated on a biological level. We rely on a previously developed method that utilizes a variety of published annotations (including conservation scores, protein deleteriousness estimates and regulatory data) to score all mutations in the human genome based on how likely they are to be affected by negative selection, controlling for mutation rate. We map this and other conservation scores to a scale of fitness coefficients via maximum likelihood using diffusion theory and a Poisson random field model on SNP data. Our method serves to approximate the deleterious DFE of mutations that are segregating, regardless of their genomic consequence. We can then compare the proportion of mutations that are negatively selected or neutral across various categories, including different types of regulatory sites. We observe that the distribution of intergenic polymorphisms is highly peaked at neutrality, while the distribution of nonsynonymous polymorphisms has a second peak at . Other types of polymorphisms have shapes that fall roughly in between these two. We find that transcriptional start sites, strong CTCF-enriched elements and enhancers are the regulatory categories with the largest proportion of deleterious polymorphisms. PMID:25375159

  19. Perturbative approximation to hybrid equation of motion coupled cluster/effective fragment potential method

    SciTech Connect

    Ghosh, Debashree

    2014-03-07

    Hybrid quantum mechanics/molecular mechanics (QM/MM) methods provide an attractive way to closely retain the accuracy of the QM method with the favorable computational scaling of the MM method. Therefore, it is not surprising that QM/MM methods are being increasingly used for large chemical/biological systems. Hybrid equation of motion coupled cluster singles doubles/effective fragment potential (EOM-CCSD/EFP) methods have been developed over the last few years to understand the effect of solvents and other condensed phases on the electronic spectra of chromophores. However, the computational cost of this approach is still dominated by the steep scaling of the EOM-CCSD method. In this work, we propose and implement perturbative approximations to the EOM-CCSD method in this hybrid scheme to reduce the cost of EOM-CCSD/EFP. The timings and accuracy of this hybrid approach is tested for calculation of ionization energies, excitation energies, and electron affinities of microsolvated nucleic acid bases (thymine and cytosine), phenol, and phenolate.

  20. Perturbative approximation to hybrid equation of motion coupled cluster/effective fragment potential method.

    PubMed

    Ghosh, Debashree

    2014-03-01

    Hybrid quantum mechanics/molecular mechanics (QM/MM) methods provide an attractive way to closely retain the accuracy of the QM method with the favorable computational scaling of the MM method. Therefore, it is not surprising that QM/MM methods are being increasingly used for large chemical/biological systems. Hybrid equation of motion coupled cluster singles doubles/effective fragment potential (EOM-CCSD/EFP) methods have been developed over the last few years to understand the effect of solvents and other condensed phases on the electronic spectra of chromophores. However, the computational cost of this approach is still dominated by the steep scaling of the EOM-CCSD method. In this work, we propose and implement perturbative approximations to the EOM-CCSD method in this hybrid scheme to reduce the cost of EOM-CCSD/EFP. The timings and accuracy of this hybrid approach is tested for calculation of ionization energies, excitation energies, and electron affinities of microsolvated nucleic acid bases (thymine and cytosine), phenol, and phenolate. PMID:24606347

  1. Restricted mass transport effects on free radical reactions

    NASA Astrophysics Data System (ADS)

    Buchanan, A. C., III; Britt, P. F.; Thomas, K. B.

    Coal possesses a complex chemical and physical structure. The cross-linked, network structure can lead to alterations in normal thermally-induced, free-radical decay pathways as a consequence of restrictions on mass transport. Moreover, in coal liquefaction, access of an external hydrogen donor to a reactive radical site can be hindered by the substantial domains of microporosity present in coals. However, previous work indicates that diffusion effects do not appear to be playing an important role in this coal conversion chemistry. Several possible explanations for this phenomenon were advanced including the potential involvement of a hydrogen hopping/radical relay mechanism recently discovered model systems in the authors' laboratories. The authors have employed silica-anchored compounds to explore the effects of restricted mass transport on the pyrolysis mechanisms of coal model compounds. In studies of two-component systems, cases have been discovered where radical centers can be rapidly relocated in the diffusionally constrained environment as a consequence of rapid serial hydrogen atom transfers. This chemistry can have substantial effects on thermal decomposition rates and on product selectivities. In this study, the authors examine additional surfaces to systematically investigate the impact of molecular structure on the hydrogen atom transfer promoted radical relay mechanism. Silica-attached 1,3-diphenylpropane (approximately Ph(CH2)3Ph, or approximately DPP) was chosen as the thermally reactive component, since it can be considered prototypical of linkages in coal that do not contain weak bonds easily cleaved at coal liquefaction temperatures (ca. 4000 C), but which crack at reasonable rates if benzylic radicals can be generated by hydrogen abstraction. The rate of such hydrogen transfers under restricted diffusion will be highly dependent on the structure and proximity of neighboring molecules.

  2. An Approximate Formulation of the Effective Indentation Modulus of Elastically Anisotropic Film-on-Substrate Systems

    SciTech Connect

    Li, Tianlei; Lee, Jinhaeng; Gao, Yanfei

    2009-01-01

    Frictionless contact between an arbitrarily-shaped rigid indenter and an elastically anisotropic film-on-substrate system can be regarded as being superposed incrementally by a flat-ended punch contact, the shape and size of which are determined by the indenter shape, indentation depth (or applied load) and elastic properties of film and substrate. For typical nanoindentation applications, the indentation modulus can thus be approximated from the response of a circular contact with pressure of the form of [1 - (r/a){sup 2}]{sup -1/2}, where r is the radial coordinate and a is the contact radius. The surface-displacement Green's function for elastically anisotropic film-on-substrate system is derived in closed-form by using the Stroh formalism and the two-dimensional Fourier transform. The predicted dependence of the effective modulus on the ratio of film thickness to contact radius agrees well with detailed finite element simulations. Implications in evaluating film modulus by nanoindentation technique are also discussed.

  3. Porosity measurements of interstellar ice mixtures using optical laser interference and extended effective medium approximations

    NASA Astrophysics Data System (ADS)

    Bossa, J.-B.; Isokoski, K.; Paardekooper, D. M.; Bonnin, M.; van der Linden, E. P.; Triemstra, T.; Cazaux, S.; Tielens, A. G. G. M.; Linnartz, H.

    2014-01-01

    Aims: This article aims to provide an alternative method of measuring the porosity of multi-phase composite ices from their refractive indices and of characterising how the abundance of a premixed contaminant (e.g., CO2) affects the porosity of water-rich ice mixtures during omni-directional deposition. Methods: We combine optical laser interference and extended effective medium approximations (EMAs) to measure the porosity of three astrophysically relevant ice mixtures: H2O:CO2 = 10:1, 4:1, and 2:1. Infrared spectroscopy is used as a benchmarking test of this new laboratory-based method. Results: By independently monitoring the O-H dangling modes of the different water-rich ice mixtures, we confirm the porosities predicted by the extended EMAs. We also demonstrate that CO2 premixed with water in the gas phase does not significantly affect the ice morphology during omni-directional deposition, as long as the physical conditions favourable to segregation are not reached. We propose a mechanism in which CO2 molecules diffuse on the surface of the growing ice sample prior to being incorporated into the bulk and then fill the pores partly or completely, depending on the relative abundance and the growth temperature.

  4. Electrical transport anisotropy of uniaxial polycrystalline samples and the effective medium approximation: An application to HTS

    NASA Astrophysics Data System (ADS)

    Cruz-García, A.; Muné, P.

    2016-08-01

    In this paper we have applied the effective medium approximation (EMA) to a polycrystalline sample made up of uniaxial crystallites with similar behavior to the high critical temperature superconductors (HTS) at the normal state (σab ≫ σc). As a result the dependence of the anisotropy parameter at the level of the sample, μ =σx /σz , on orientation probability of the grains' a-axes along a certain preferential direction, γxa is obtained. The intrinsic and shape anisotropy parameters of the crystallites constitute input data. In addition, the dependence of the orientation factor, f, which has been introduced in current models on the transport properties of HTS, is calculated as a function of γxa. These results offer a tool to interpret electrical transport measurements at normal state in granular uniaxial superconducting materials with certain texture degree, by means of the correlation between microstructure and electrical transport properties. Moreover, the comparison between the model and some experimental data suggests the presence of intragranular planar defects in the polycrystalline superconductors. They may affect the measurement of paracoherent resistivity and consequently the determination of f mainly in Bi based samples.

  5. Beyond the born approximation: Measuring the two-photon exchange effect at CLAS

    SciTech Connect

    Bennett, Robert Paul

    2012-04-01

    Recent results from experiments at Jefferson Laboratory, Newport News VA, which measured the ratio of the electric to magnetic form factors of the proton, G{sub E}/G{sub M}, have forced us to reexamine the single photon exchange approximation in lepton-proton elastic scattering. Discrepancies between the ratio obtained via the time-tested Rosenbluth separation method and newer polarization transfer measurements, which differ by as much as a factor of three, may be resolved by considering the effect of two photon exchange (TPE) processes. The CLAS TPE experiment at Jefferson Laboratory, will determine the effect of two-photon exchange in elastic lepton-proton scattering by precisely measuring the ratio of positron-proton to electron-proton elastic cross sections over a large kinematic range (0.1 < {xi} < 0.96, 0.2 {ge} Q{sup 2} {le} 2.0 GeV{sup 2}). We accomplish this by directing the 5.5 GeV primary electron beam, provided by the Continuous Electron Beam Accelerator Facility (CEBAF), onto a set of radiators and converters to produce simultaneous and identical beams of electron and positrons which collide with our proton target. Acceptance and efficiency concerns are minimized by only considering the ratios of the elastic cross sections and by switching polarity of magnets in the beamline and the spectrometer. Guided by the results of a short 2006 test run and extensive GEANT based modeling, new shielding and beamline components were designed to maximize luminosity. We took data from November 2010 - February 2011. The unique experimental design and challenges of the TPE experiment and the current analysis status will be presented.

  6. Beyond the born approximation: Measuring the two-photon exchange effect at CLAS

    NASA Astrophysics Data System (ADS)

    Bennett, Robert Paul

    2012-09-01

    Recent results from experiments at Jefferson Laboratory, Newport News VA, which measured the ratio of the electric to magnetic form factors of the proton, GE/GM, have forced us to reexamine the single photon exchange approximation in lepton-proton elastic scattering. Discrepancies between the ratio obtained via the time-tested Rosenbluth separation method and newer polarization transfer measurements, which differ by as much as a factor of three, may be resolved by considering the effect of two photon exchange (TPE) processes. The CLAS TPE experiment at Jefferson Laboratory, will determine the effect of two-photon exchange in elastic lepton-proton scattering by precisely measuring the ratio of positron-proton to electron-proton elastic cross sections over a large kinematic range (0.1 < ɛ < 0.96,0.2 ≥ Q2 ≤ 2.0GeV2). We accomplish this by directing the 5.5 GeV primary electron beam, provided by the Continuous Electron Beam Accelerator Facility (CEBAF), onto a set of radiators and converters to produce simultaneous and identical beams of electron and positrons which collide with our proton target. Acceptance and efficiency concerns are minimized by only considering the ratios of the elastic cross sections and by switching polarity of magnets in the beamline and the spectrometer. Guided by the results of a short 2006 test run and extensive GEANT based modeling, new shielding and beamline components were designed to maximize luminosity. We took data from November 2010 - February 2011. The unique experimental design and challenges of the TPE experiment and the current analysis status will be presented.

  7. Cancellation of environmental effects in resonant mass sensors based on resonance mode and effective mass

    SciTech Connect

    Naeli, Kianoush; Brand, Oliver

    2009-06-15

    A novel technique is developed to cancel the effect of environmental parameters, e.g., temperature and humidity, in resonant mass sensing. Utilizing a single resonator, the environmental cancellation is achieved by monitoring a pair of resonant overtones and the effective sensed mass in those overtones. As an eminent advantage, especially compared to dual-mode temperature compensation techniques, the presented technique eliminates any need for previously measured look-up tables or fitting the measurement data. We show that a resonant cantilever beam is an appropriate platform for applying this technique, and derive an analytical expression to relate the actual and effective sensed masses on a cantilever beam. Thereby, it is shown that in applying the presented technique successfully, the effective sensed masses must not be the same in the investigated pair of resonance overtones. To prove the feasibility of the proposed technique, flexural resonance frequencies of a silicon cantilever are measured before and after loading with a strip of photoresist. Applying the presented technique shows significant reductions in influence of environmental parameters, with the temperature and humidity coefficients of frequency being improved from -19.5 to 0.2 ppm deg. C{sup -1} and from 0.7 to -0.03 ppm %RH{sup -1}, respectively.

  8. Approximations used in calculating many-body effects in resonant ((dt. mu. )dee) formation

    SciTech Connect

    Cohen, J.S.; Leon, M.

    1989-02-01

    The approximations needed to treat the resonant formation of the compound molecule ((dt..mu..)dee)/sup */ as a line-broadening process are examined. The necessary criteria for applying the impact (Lorentzian) approximation are shown to be seriously violated under the usual conditions of muon-catalyzed fusion. Neither the condition for binary collisions nor the requirement that the detuning not be too large holds. A much more appropriate description is the many-body quasistatic approximation, which is valid for large detunings at any density and for practically the whole profile at high densities. The convenient factorization of the three-body rate into a convolution of a two-body rate with a broadening factor is shown to hold within some approximations, but the broadening factor itself depends on the transition being considered.

  9. β -decay rates of odd-mass neutron-rich isotopes in the deformed quasiparticle random-phase approximation with realistic interactions

    NASA Astrophysics Data System (ADS)

    Ni, Dongdong; Ren, Zhongzhou

    2015-09-01

    The deformed quasiparticle random-phase approximation with realistic nucleon-nucleon interactions is extended for the β- decay of odd-mass neutron-rich Kr, Sr, Zr, and Mo isotopes, from their longest-lived isotopes to the experimentally unknown nuclei. The particle-particle and particle-hole channels of residual interactions are handled in large single-particle model spaces, based on the Brückner G matrix with charge-dependent Bonn nucleon-nucleon forces. Both allowed Gamow-Teller and first-forbidden transitions are considered and different treatments for odd-mass systems are emphasized. The sensitivity of the calculated results to the single-particle level scheme and the particle-particle strength is discussed. The calculated Gamow-Teller strengths are analyzed, together with the contributions from first-forbidden transitions. The calculated half-lives are found to agree well with the experimental data over the orders of magnitude from 10-2 to 103 s.

  10. Effective continuum approximation for modeling fluid and heat flow in fractured porous tuff: Nevada Nuclear Waste Storage Investigations Project

    SciTech Connect

    Pruess, K.; Wang, J.S.Y.; Tsang, Y.W.

    1988-05-01

    Fluid and heat flow in fractured porous media can be of great complexity, and a quantitative description requires the development of simplified mathematical and numerical methods. This report presents a detailed formulation, and partial evaluation, of an ``effective continuum approximation`` for non-isothermal multi-phase flow, which had been introduced previously only in a heuristic fashion. The key concept on which the effective continuum approach must rely is (approximate) local thermodynamic equilibrium between fractures and rock matrix. The applicability of this approximation is discussed and studied by means of numerical simulations for emplacement of high-level waste packages in partially saturated fractured tuff. The simulations demonstrate that the validity of the effective continuum approximation cannot be ascertained in general terms. The approximation will break down for rapid transients in flow systems with low matrix permeability and/or large fracture spacing, so that its applicability needs to be carefully evaluated for the specific processes and conditions under study. The effective continuum approximation has been applied for a preliminary study of fluid and heat flow near a high-level nuclear waste repository on a regional scale, employing a highly simplified strtatigraphic description. It was found that substantial gas phase convection was taking place, with convection velocities being sensitive to permeability, porosity, and tortuosity of the fracture network. 18 refs., 27 figs., 7 tabs.

  11. One-dimensional model of a liquid metal in the effective-medium approximation in the random limit

    NASA Astrophysics Data System (ADS)

    Hasbun, Javier E.

    1989-08-01

    In this paper it is shown that the effective-medium approximation (EMA) of Roth [Phys. Rev. B 9, 2476 (1974)] corresponds to the approximation No. 5 of Klauder [Ann. Phys. 14, 43 (1961)] in the random limit for the one-dimensional delta-function model of a liquid metal. The random EMA results are compared with the exact results obtained by Frisch and Lloyd [Phys. Rev. 120, 1175 (1960)] for this model.

  12. The lens effect of a big spherical inhomogeneity in the linear approximation

    SciTech Connect

    Moreno, J.; Portilla, M. )

    1990-04-01

    The paper addresses a large gravitational lens, of dimensions comparable with observer-lens-source distances, for arbitrary lens-observer-source angles. The lens is approximated by a small, pressureless, spsherically symmetric perturbation in a Einstein-de Sitter universe. The deflection angle contains essential terms which do not appear when the lens is approximated by an isolated body in a Minkowskian space. These terms should be considered to study the optical appearance of the inhomogeneity. The lens equation explicitly conserves brightness over the whole celestial sphere of the observer. 8 refs.

  13. Quantum Transport in Crystals: Effective Mass Theorem and K·P Hamiltonians

    NASA Astrophysics Data System (ADS)

    Barletti, Luigi; Ben Abdallah, Naoufel

    2011-11-01

    In this paper the effective mass approximation and the k·p multi-band models, describing quantum evolution of electrons in a crystal lattice, are discussed. Electrons are assumed to move in both a periodic potential and a macroscopic one. The typical period {ɛ} of the periodic potential is assumed to be very small, while the macroscopic potential acts on a much bigger length scale. Such homogenization asymptotic is investigated by using the envelope-function decomposition of the electron wave function. If the external potential is smooth enough, the k·p and effective mass models, well known in solid-state physics, are proved to be close (in the strong sense) to the exact dynamics. Moreover, the position density of the electrons is proved to converge weakly to its effective mass approximation.

  14. Effective Utilization of the Mass Media.

    ERIC Educational Resources Information Center

    Turner, Norma Haston

    The question of whether or not the mass media can successfully be used as a vehicle for creative social and individual change is discussed and brief descriptions are given of successful and unsuccessful campaigns that attempted to improve public attitudes toward certain health problems. Ten recommendations are made for using the mass media…

  15. Mass and Isospin Effects in Multifragmentation

    NASA Astrophysics Data System (ADS)

    Sfienti, C.; Adrich, P.; Aumann, T.; Bacri, C. O.; Barczyk, T.; Bassini, R.; Boiano, C.; Botvina, A. S.; Boudard, A.; Brzychczyk, J.; Chbihi, A.; Cibor, J.; Czech, B.; De Napoli, M.; Ducret, J.-E.; Emling, H.; Frankland, J.; Hellström, M.; Henzlova, D.; Kezzar, K.; Immé, G.; Iori, I.; Johansson, H.; Lafriakh, A.; Le Fèvre, A.; Le Gentil, E.; Leifels, Y.; Lynch, W. G.; Lühning, J.; Łukasik, J.; Lynen, U.; Majka, Z.; Mocko, M.; Müller, W. F. J.; Mykulyak, A.; Orth, H.; Otte, A. N.; Palit, R.; Pullia, A.; Raciti, G.; Rapisarda, E.; Sann, H.; Schwarz, C.; Simon, H.; Sokolov, A.; Sümmerer, K.; Trautmann, W.; Tsang, M. B.; Verde, G.; Volant, C.; Wallace, M.; Weick, H.; Wiechula, J.; Wieloch, A.; Zwieglinski, B.

    2005-03-01

    A systematic study of isospin effects in the breakup of projectile spectators at relativistic energies has been performed with the ALADiN spectrometer at the GSI laboratory (Darmstadt). Four different projectiles 197Au, 124La, 124Sn and 107Sn, all with an incident energy of 600 AMeV, have been used, thus allowing a study of various combinations of masses and N/Z ratios in the entrance channel. The measurement of the momentum vector and of the charge of all projectile fragments with Z > 1 entering the acceptance of the ALADiN magnet has been performed with the high efficiency and resolution achieved with the TP-MUSIC IV detector. The Rise and Fall behavior of the mean multiplicity of IMFs as a function of Zbound and its dependence on the isotopic composition has been determined for the studied systems. Other observables investigated so far include mean N/Z values of the emitted light fragments and neutron multiplicities. Qualitative agreement has been obtained between the observed gross properties and the predictions of the Statistical Multifragmentation Model.

  16. Systematic effects of the quenched approximation on the strong penguin contribution to epsilon-prime / epsilon

    SciTech Connect

    Aubin, C.; Christ, N.H.; Dawson, C.; Laiho, J.W.; Noaki, J.; Li, S.; Soni, A.; /Brookhaven

    2006-03-01

    We discuss the implementation and properties of the quenched approximation in the calculation of the left-right, strong penguin contributions (i.e. Q{sub 6}) to {epsilon}{prime}/{epsilon}. The coefficient of the new chiral logarithm, discovered by Golterman and Pallante, which appears at leading order in quenched chiral perturbation theory is evaluated using both the method proposed by those authors and by an improved approach which is free of power divergent corrections. The result implies a large quenching artifact in the contribution of Q{sub 6} to {epsilon}{prime}/{epsilon}. This failure of the quenched approximation affects only the strong penguin operators and so does not affect the Q8 contribution to {epsilon}{prime}/{epsilon} nor ReA{sub 0}, ReAP{sub 2} and thus, the {Delta}I = 1/2 rule at tree level in chiral perturbation theory.

  17. Systematic effects of the quenched approximation on the strong penguin contribution to {epsilon}{sup '}/{epsilon}

    SciTech Connect

    Aubin, C.; Christ, N. H.; Li, S.; Dawson, C.; Noaki, J.; Laiho, J. W.; Soni, A.

    2006-08-01

    We discuss the implementation and properties of the quenched approximation in the calculation of the left-right, strong penguin contributions (i.e. Q{sub 6}) to {epsilon}{sup '}/{epsilon}. The coefficient of the new chiral logarithm, discovered by Golterman and Pallante, which appears at leading order in quenched chiral perturbation theory is evaluated using both the method proposed by those authors and by an improved approach which is free of power divergent corrections. The result implies a large quenching artifact in the contribution of Q{sub 6} to {epsilon}{sup '}/{epsilon}. This failure of the quenched approximation affects only the strong penguin operators and so does not affect the Q{sub 8} contribution to {epsilon}{sup '}/{epsilon} nor ReA{sub 0}, ReA{sub 2} and thus, the {delta}I=1/2 rule at tree level in chiral perturbation theory.

  18. Challenges within the linear response approximation when studying enzyme catalysis and effects of mutations.

    PubMed

    Sharir-Ivry, Avital; Varatharaj, Rajapandian; Shurki, Avital

    2015-01-13

    Various aspects of the linear response approximation (LRA) approach were examined when calculating reaction barriers within an enzyme and its different mutants. Scaling the electrostatic interactions is shown to slightly affect the absolute values of the barriers but not the overall trend when comparing wild-type and mutants. Convergence of the overall energetics was shown to depend on the sampling. Finally, the contribution of particular residues was shown to be significant, despite its small value. PMID:26574227

  19. An isotopic mass effect on the intermolecular potential

    NASA Astrophysics Data System (ADS)

    Herman, Michael F.; Currier, Robert P.; Clegg, Samuel M.

    2015-10-01

    The impact of isotopic variation on the electronic energy and intermolecular potentials is often suppressed when calculating isotopologue thermodynamics. Intramolecular potential energy surfaces for distinct isotopologues are in fact equivalent under the Born-Oppenheimer approximation, which is sometimes used to imply that the intermolecular interactions are independent of isotopic mass. In this communication, the intermolecular dipole-dipole interaction between hetero-nuclear diatomic molecules is considered. It is shown that the intermolecular potential contains mass-dependent terms even though each nucleus moves on a Born-Oppenheimer surface. The analysis suggests that mass dependent variations in intermolecular potentials should be included in comprehensive descriptions of isotopologue thermodynamics.

  20. Mass loss from warm giants: Magnetic effects

    NASA Technical Reports Server (NTRS)

    Mullan, D. J.

    1980-01-01

    Among warm giant stars, rapid mass loss sets in along a well defined velocity dividing line (VDL). Hot corona also disappear close to the VDL and thermal pressure cannot drive the observed rapid mass loss in these stars. The VDL may be associated with magnetic fields changing from closed to open. Such a change is consistent with the lack of X-rays from late-type giants. A magnetic transition locus based on Pneuman's work on helmet streamer stability agrees well with the empirical VDL. The change from closed to open fields not only makes rapid mass loss possible, but also contributes to energizing the mass loss in the form of discrete bubbles.

  1. The effect of Livermore OPAL opacities on the evolutionary masses of RR Lyrae stars

    NASA Technical Reports Server (NTRS)

    Yi, Sukyoung; Lee, Young-Wook; Demarque, Pierre

    1993-01-01

    We have investigated the effect of the new Livermore OPAL opacities on the evolution of horizontal-branch (HB) stars. This work was motivated by the recent stellar pulsation calculations using the new Livermore opacities, which suggest that the masses of double-mode RR Lyrae stars are 0.1-0.2 solar mass larger than those based on earlier opacities. Unlike the pulsation calculations, we find that the effect of opacity change on the evolution of HB stars is not significant. In particular, the effect of the mean masses of RR Lyrae stars is very small, showing a decrease of only 0.01-0.02 solar mass compared to the models based on old Cox-Stewart opacities. Consequently, with the new Livermore OPAL opacities, both the stellar pulsation and evolution models now predict approximately the same masses for the RR Lyrae stars. Our evolutionary models suggest that the mean masses of the RR Lyrae stars are about 0.76 and about 0.71 solar mass for M15 (Oosterhoff group II) and M3 (group I), respectively. If (alpha/Fe) = 0.4, these values are decreased by about 0.03 solar mass. Variations of the mean masses of RR Lyrae stars with HB morphology and metallicity are also presented.

  2. Decoherence effects in the quantum qubit flip game using Markovian approximation

    NASA Astrophysics Data System (ADS)

    Gawron, Piotr; Kurzyk, Dariusz; Pawela, Łukasz

    2013-11-01

    We are considering a quantum version of the penny flip game, whose implementation is influenced by the environment that causes decoherence of the system. In order to model the decoherence, we assume Markovian approximation of open quantum system dynamics. We focus our attention on the phase damping, amplitude damping and amplitude raising channels. Our results show that the Pauli strategy is no longer a Nash equilibrium under decoherence. We attempt to optimize the players' control pulses in the aforementioned setup to allow them to achieve higher probability of winning the game compared with the Pauli strategy.

  3. Space inhomogeneity and detuning effects in a laser with a saturable absorber: a first-order approximation

    SciTech Connect

    Garcia-Fernandez, P.; Velarde, M.G.

    1988-05-01

    To a first approximation the effects of detuning and/or space inhomogeneity on the stability domain of a model for a laser with a saturable absorber are presented. It appears that the space dependence increases the domain of the emissionless state, thus delaying the laser action.

  4. Charts and approximate formulas for the estimation of aeroelastic effects on the loading of swept and unswept wings

    NASA Technical Reports Server (NTRS)

    Diederich, Franklin W; Foss, Kenneth A

    1953-01-01

    Charts and approximate formulas are presented for the estimation of aeroelastic effects on the spanwise lift distribution, lift-curve slope, aerodynamic center, and damping in roll of swept and unswept wings at subsonic and supersonic speeds. Some design considerations brought out by the results of this report are discussed.

  5. New effective moduli of isotropic viscoelastic composites. Part II. Comparison of approximate calculation with the analytical solution

    NASA Astrophysics Data System (ADS)

    Kupriyanov, N. A.; Simankin, F. A.; Manabaev, K. K.

    2016-04-01

    A new approximate algorithm for calculating a stress-strain state of viscoelastic bodies is used. The algorithm is based on the derivation of the expressions of time-effective modules. These modules are obtained by iterative changes, compressing the fork of Voigt-Reuss. As an example the analytic solution about the action of a concentrated force on the viscoelastic half-space is compared with the approximate solution. Numerical calculations are performed for a wide range of relaxation characteristics of a viscoelastic half-space. Results of the comparison of stresses and displacements with the analytic solution give coincidence within 3... 15%.

  6. Mass Media Effects and Black Americans.

    ERIC Educational Resources Information Center

    Stroman, Carolyn A.

    1984-01-01

    Black Americans' use of and belief in the credibility of the mass media is no less extensive than that of the general population. In fact, television and radio use by blacks exceeds that of whites and research shows the broadcast media to be particularly important sources of information for blacks on consumer and political affairs. But many…

  7. Effect of initial phase on error in electron energy obtained using paraxial approximation for a focused laser pulse in vacuum

    SciTech Connect

    Singh, Kunwar Pal; Arya, Rashmi; Malik, Anil K.

    2015-09-14

    We have investigated the effect of initial phase on error in electron energy obtained using paraxial approximation to study electron acceleration by a focused laser pulse in vacuum using a three dimensional test-particle simulation code. The error is obtained by comparing the energy of the electron for paraxial approximation and seventh-order correction description of the fields of Gaussian laser. The paraxial approximation predicts wrong laser divergence and wrong electron escape time from the pulse which leads to prediction of higher energy. The error shows strong phase dependence for the electrons lying along the axis of the laser for linearly polarized laser pulse. The relative error may be significant for some specific values of initial phase even at moderate values of laser spot sizes. The error does not show initial phase dependence for a circularly laser pulse.

  8. Intrinsic Carrier Concentration and Electron Effective Mass in Hg(1-x) Zn(x) Te

    NASA Technical Reports Server (NTRS)

    Sha, Yi-Gao; Su, Ching-Hua; Lehoczky, S. L.

    1997-01-01

    In this work, the intrinsic carrier concentration and electron effective mass in Hg(l-x)Zn(x)Te were numerically calculated. We adopt the procedures similar to those used by Su et. al. for calculating intrinsic carrier concentrations in Hg(1-x)Cd(x)Te which solve the exact dispersion relation in Kane model for the calculation of the conduction band electron concentrations and the corresponding electron effective masses. No approximation beyond those inherent in the k centered dot p model was used here.

  9. Influence of the superposition approximation on calculated effective dose rates from galactic cosmic rays at aerospace-related altitudes

    NASA Astrophysics Data System (ADS)

    Copeland, Kyle

    2015-07-01

    The superposition approximation was commonly employed in atmospheric nuclear transport modeling until recent years and is incorporated into flight dose calculation codes such as CARI-6 and EPCARD. The useful altitude range for this approximation is investigated using Monte Carlo transport techniques. CARI-7A simulates atmospheric radiation transport of elements H-Fe using a database of precalculated galactic cosmic radiation showers calculated with MCNPX 2.7.0 and is employed here to investigate the influence of the superposition approximation on effective dose rates, relative to full nuclear transport of galactic cosmic ray primary ions. Superposition is found to produce results less than 10% different from nuclear transport at current commercial and business aviation altitudes while underestimating dose rates at higher altitudes. The underestimate sometimes exceeds 20% at approximately 23 km and exceeds 40% at 50 km. Thus, programs employing this approximation should not be used to estimate doses or dose rates for high-altitude portions of the commercial space and near-space manned flights that are expected to begin soon.

  10. Finite volume effects for nucleon and heavy meson masses

    SciTech Connect

    Colangelo, Gilberto; Fuhrer, Andreas; Lanz, Stefan

    2010-08-01

    We apply the resummed version of the Luescher formula to analyze finite volume corrections to the mass of the nucleon and of heavy mesons. We show that by applying the subthreshold expansion of the scattering amplitudes one can express the finite volume corrections in terms of only a few physical observables and the size of the box. In the case of the nucleon, the available information about the quark mass dependence of these physical quantities is discussed and used to assess the finite volume corrections to the nucleon mass as a function of the quark mass including a detailed analysis of the remaining uncertainties. For heavy mesons, the Luescher formula is derived both fully relativistically and in a nonrelativistic approximation and a first attempt at a numerical analysis is made.

  11. Minimization of the effect of errors in approximate radiation view factors

    SciTech Connect

    Clarksean, R.; Solbrig, C.

    1993-09-01

    The maximum temperature of irradiated fuel rods in storage containers was investigated taking credit only for radiation heat transfer. Estimating view factors is often easy but in many references the emphasis is placed on calculating the quadruple integrals exactly. Selecting different view factors in the view factor matrix as independent, yield somewhat different view factor matrices. In this study ten to twenty percent error in view factors produced small errors in the temperature which are well within the uncertainty due to the surface emissivities uncertainty. However, the enclosure and reciprocity principles must be strictly observed or large errors in the temperatures and wall heat flux were observed (up to a factor of 3). More than just being an aid for calculating the dependent view factors, satisfying these principles, particularly reciprocity, is more important than the calculation accuracy of the view factors. Comparison to experiment showed that the result of the radiation calculation was definitely conservative as desired in spite of the approximations to the view factors.

  12. THE ZEEMAN EFFECT IN THE SOBOLEV APPROXIMATION: SPLIT MONOPOLE FIELDS AND THE 'HEARTBEAT' STOKES V PROFILE

    SciTech Connect

    Gayley, K. G.; Ignace, R.

    2010-01-01

    We calculate the circularly polarized Stokes V(lambda) profile for emission lines, formed in hot-star winds threaded with a weak radial magnetic field. For simplicity, the field is treated as a split monopole under the assumptions that it has been radially combed by the wind, and rotation is not playing a central role. Invoking the weak-field approximation, we find that the V(lambda) profile has a characteristic 'heartbeat' shape exhibiting multiple sign inversions, which might be mistaken for noise in the absence of theoretical guidance. We also conclude that there is a tendency for the V(lambda) profile to integrate to zero on each side of the line separately. The overall scale of V(lambda)/I(lambda) is set by the ratio of the field strength to the flow speed, B/v, characteristic of the line-forming region, and is of the order of 0.1% for a wind magnetic field B approx = 100G at depths where the wind speed is v approx = 100 km s{sup -1}.

  13. Analytical approximations for matter effects on CP violation in the accelerator-based neutrino oscillations with E ≲ 1 GeV

    NASA Astrophysics Data System (ADS)

    Xing, Zhi-zhong; Zhu, Jing-yu

    2016-07-01

    Given an accelerator-based neutrino experiment with the beam energy E ≲ 1 GeV, we expand the probabilities of ν μ → ν e and {overline{ν}}_{μ}to {overline{ν}}_e oscillations in matter in terms of two small quantities Δ21 /Δ31 and A/Δ31, where Δ 21≡ m 2 2 - m 1 2 and Δ 31≡ m 3 2 - m 1 2 are the neutrino mass-squared differences, and A measures the strength of terrestrial matter effects. Our analytical approximations are numerically more accurate than those made by Freund in this energy region, and thus they are particularly applicable for the study of leptonic CP violation in the low-energy MOMENT, ESS νSM and T2K oscillation experiments. As a by-product, the new analytical approximations help us to easily understand why the matter-corrected Jarlskog parameter tilde{J} peaks at the resonance energy E ∗ ≃ 0 .14GeV (or 0 .12 GeV) for the normal (or inverted) neutrino mass hierarchy, and how the three Dirac unitarity triangles are deformed due to the terrestrial matter contamination. We also affirm that a medium-baseline neutrino oscillation experiment with the beam energy E lying in the E ∗ ≲ E ≲ 2 E ∗ range is capable of exploring leptonic CP violation with little matter-induced suppression.

  14. A non-resonant mass sensor to eliminate the "missing mass" effect during mass measurement of biological materials

    NASA Astrophysics Data System (ADS)

    Shrikanth, V.; Bobji, M. S.

    2014-10-01

    Resonant sensors and crystal oscillators for mass detection need to be excited at very high natural frequencies (MHz). Use of such systems to measure mass of biological materials affects the accuracy of mass measurement due to their viscous and/or viscoelastic properties. The measurement limitation of such sensor system is the difficulty in accounting for the "missing mass" of the biological specimen in question. A sensor system has been developed in this work, to be operated in the stiffness controlled region at very low frequencies as compared to its fundamental natural frequency. The resulting reduction in the sensitivity due to non-resonant mode of operation of this sensor is compensated by the high resolution of the sensor. The mass of different aged drosophila melanogaster (fruit fly) is measured. The difference in its mass measurement during resonant mode of operation is also presented. That, viscosity effects do not affect the working of this non-resonant mass sensor is clearly established by direct comparison.

  15. Many-Body Effects on Bandgap Shrinkage, Effective Masses, and Alpha Factor

    NASA Technical Reports Server (NTRS)

    Li, Jian-Zhong; Ning, C. Z.; Woo, Alex C. (Technical Monitor)

    2000-01-01

    Many-body Coulomb effects influence the operation of quantum-well (QW) laser diode (LD) strongly. In the present work, we study a two-band electron-hole plasma (EHP) within the Hatree-Fock approximation and the single plasmon pole approximation for static screening. Full inclusion of momentum dependence in the many-body effects is considered. An empirical expression for carrier density dependence of the bandgap renormalization (BGR) in an 8 nm GaAs/Al(0.3)G(4.7)As single QW will be given, which demonstrates a non-universal scaling behavior for quasi-two-dimension structures, due to size-dependent efficiency of screening. In addition, effective mass renormalization (EMR) due to momentum-dependent self-energy many-body correction, for both electrons and holes is studied and serves as another manifestation of the many-body effects. Finally, the effects on carrier density dependence of the alpha factor is evaluated to assess the sensitivity of the full inclusion of momentum dependence.

  16. Direct Demonstration of the Concept of Unrestricted Effective-Medium Approximation

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.; Dlugach, Zhanna M.; Zakharova, Nadezhda T.

    2014-01-01

    The modified unrestricted effective-medium refractive index is defined as one that yields accurate values of a representative set of far-field scattering characteristics (including the scattering matrix) for an object made of randomly heterogeneous materials. We validate the concept of the modified unrestricted effective-medium refractive index by comparing numerically exact superposition T-matrix results for a spherical host randomly filled with a large number of identical small inclusions and Lorenz-Mie results for a homogeneous spherical counterpart. A remarkable quantitative agreement between the superposition T-matrix and Lorenz-Mie scattering matrices over the entire range of scattering angles demonstrates unequivocally that the modified unrestricted effective-medium refractive index is a sound (albeit still phenomenological) concept provided that the size parameter of the inclusions is sufficiently small and their number is sufficiently large. Furthermore, it appears that in cases when the concept of the modified unrestricted effective-medium refractive index works, its actual value is close to that predicted by the Maxwell-Garnett mixing rule.

  17. Assessment of density-functional approximations: Long-range correlations and self-interaction effects

    SciTech Connect

    Jung, J.; Alvarellos, J.E.; Garcia-Gonzalez, P.; Godby, R.W.

    2004-05-01

    The complex nature of electron-electron correlations is made manifest in the very simple but nontrivial problem of two electrons confined within a sphere. The description of highly nonlocal correlation and self-interaction effects by widely used local and semilocal exchange-correlation energy density functionals is shown to be unsatisfactory in most cases. Even the best such functionals exhibit significant errors in the Kohn-Sham potentials and density profiles.

  18. Effect of various approximations on predicted progressive failure in plain weave composites

    NASA Technical Reports Server (NTRS)

    Whitcomb, John; Srirengan, Kanthikannan

    1995-01-01

    Three-dimensional finite element analysis was used to simulate progressive failure of a plain weave composite subjected to in-plane extension. The loading was parallel to one of the tow directions. The effects of various characteristics of the finite element model on predicted behavior were examined. The predicted behavior was found to be sensitive to quadrature order, mesh refinement, and the material degradation model. Also the sensitivity of the predictions to the tow waviness was studied. The predicted strength decreased considerably with increased waviness. More numerical studies and comparisons with experimental data are needed to establish reliable guidelines for accurate progressive failure prediction.

  19. Excited-State Effective Masses in Lattice QCD

    SciTech Connect

    George Fleming, Saul Cohen, Huey-Wen Lin

    2009-10-01

    We apply black-box methods, i.e. where the performance of the method does not depend upon initial guesses, to extract excited-state energies from Euclidean-time hadron correlation functions. In particular, we extend the widely used effective-mass method to incorporate multiple correlation functions and produce effective mass estimates for multiple excited states. In general, these excited-state effective masses will be determined by finding the roots of some polynomial. We demonstrate the method using sample lattice data to determine excited-state energies of the nucleon and compare the results to other energy-level finding techniques.

  20. High resonant mass sensor evaluation: An effective method

    SciTech Connect

    Tseytlin, Yakov M.

    2005-11-15

    Micro- and nanocantilever mass sensors in higher resonant oscillation modes are very sensitive to an additional mass, which is positioned along their length except for the nodal points. However, the known evaluation methods of this sensitivity are usually complicated, which is not effective in applications for atomic force microscopy. Our solution is simple, unified, and based on the superposition force method, which allows us to estimate effective spring constants, effective mass factors, and correct prediction of sensitivity for nano- and microcantilevers along their length in higher resonant modes. Simple analytical and computer aided calculation algorithms are developed. Calculation results are close to the experimental and computer simulation data within a few percent.

  1. A 30-month longitudinal study of the effects of some oral hygiene measures on Streptococcus mutans and approximal dental caries.

    PubMed

    Axelsson, P; Kristoffersson, K; Karlsson, R; Bratthall, D

    1987-03-01

    The effects of some oral hygiene measures on Streptococcus mutants and approximal dental caries were evaluated. One hundred and eighty-seven 13-year-old individuals with high levels of salivary S. mutans (greater than 10(6)/mL) were selected. They were randomly distributed into three groups. Group I initially received professional mechanical tooth-cleaning, tongue-scraping, chlorhexidine treatment, and oral hygiene instructions concentrated on the approximal surfaces most colonized by S. mutans. The treatment was given four times with intervals of two days, followed by one single treatment every six months throughout the experimental period. The initial treatment period for group II, also consisting of four visits, included the same oral hygiene instructions as for group I. The instructions were repeated every six months. Group III was maintained in the preventive program provided by the local Dental Health Office, based on mechanical plaque control and topical use of fluorides and chlorhexidine at individualized intervals. Group I showed a significant immediate reduction of S. mutans in saliva as well as an approximal tooth surfaces. After six months, there were no differences among the three groups regarding these variables. Compared with baseline, there was a significant reduction of S. mutans in all groups. There was no significant difference in caries progression among the three groups. However, the selected "high-risk" individuals in group I developed 0.25 new manifest caries lesions approximally/year, compared with 0.27 for all children of the same age group in the area. Seventeen individuals had approximal surfaces with consistently high or consistently low S. mutans levels. Forty-six percent of the surfaces with high values developed new or progressive caries, compared with 2% of the surfaces with low values. PMID:3475309

  2. Gluon transport equation with effective mass and dynamical onset of Bose–Einstein condensation

    DOE PAGESBeta

    Blaizot, Jean-Paul; Jiang, Yin; Liao, Jinfeng

    2016-05-01

    In this paper we study the transport equation describing a dense system of gluons, in the small scattering angle approximation, taking into account medium-generated effective masses of the gluons. We focus on the case of overpopulated systems that are driven to Bose–Einstein condensation on their way to thermalization. Lastly, the presence of a mass modifies the dispersion relation of the gluon, as compared to the massless case, but it is shown that this does not change qualitatively the scaling behavior in the vicinity of the onset.

  3. Gluon transport equation with effective mass and dynamical onset of Bose-Einstein condensation

    NASA Astrophysics Data System (ADS)

    Blaizot, Jean-Paul; Jiang, Yin; Liao, Jinfeng

    2016-05-01

    We study the transport equation describing a dense system of gluons, in the small scattering angle approximation, taking into account medium-generated effective masses of the gluons. We focus on the case of overpopulated systems that are driven to Bose-Einstein condensation on their way to thermalization. The presence of a mass modifies the dispersion relation of the gluon, as compared to the massless case, but it is shown that this does not change qualitatively the scaling behavior in the vicinity of the onset.

  4. Mass

    SciTech Connect

    Chris Quigg

    2007-12-05

    In the classical physics we inherited from Isaac Newton, mass does not arise, it simply is. The mass of a classical object is the sum of the masses of its parts. Albert Einstein showed that the mass of a body is a measure of its energy content, inviting us to consider the origins of mass. The protons we accelerate at Fermilab are prime examples of Einsteinian matter: nearly all of their mass arises from stored energy. Missing mass led to the discovery of the noble gases, and a new form of missing mass leads us to the notion of dark matter. Starting with a brief guided tour of the meanings of mass, the colloquium will explore the multiple origins of mass. We will see how far we have come toward understanding mass, and survey the issues that guide our research today.

  5. Natural Higgs mass in supersymmetry from nondecoupling effects.

    PubMed

    Lu, Xiaochuan; Murayama, Hitoshi; Ruderman, Joshua T; Tobioka, Kohsaku

    2014-05-16

    The Higgs mass implies fine-tuning for minimal theories of weak-scale supersymmetry (SUSY). Nondecoupling effects can boost the Higgs mass when new states interact with the Higgs boson, but new sources of SUSY breaking that accompany such extensions threaten naturalness. We show that two singlets with a Dirac mass can increase the Higgs mass while maintaining naturalness in the presence of large SUSY breaking in the singlet sector. We explore the modified Higgs phenomenology of this scenario, which we call the "Dirac next-to-minimal supersymmetric standard model." PMID:24877931

  6. Total Ionizing Dose Effects in 12-Bit Successive-Approximation Analog-To-Digital Converters

    NASA Technical Reports Server (NTRS)

    Lee, C. I.; Rax, B. G.; Johnston, A. H.

    1993-01-01

    Analog-to-digital (A/D) converters are critical components in many space and military systems, and there have been numerous advances in A/D converter technology that have increased the resolution and conversion time. The increased performance is due to two factors: (1) advances in circuit design and complexity, which have increased the number of components and the integration density; and (2) new process technologies, such as BiCMOS, which provide better performance, cost, and smaller size in mixed-signal circuits. High-speed A/D converters, with conversion rates above 1 MHz, present a challenge to circuit designers and test engineers. Their complex architectures and high-performance specifications result in numerous possible failure modes when they are subjected to ionizing radiation. The dominant failure mode may depend on the specific application because the fundamental effects on MOS and bipolar transistors are strongly affected by bias conditions.

  7. Molecular electrostatic potential at the atomic sites in the effective core potential approximation.

    PubMed

    Lesiuk, Michał; Zachara, Janusz

    2013-02-21

    Considering calculations of the molecular electrostatic potential at the atomic sites (MEP@AS) in the presence of effective core potentials (ECP), we found that the consequent use of the definition of MEP@AS based on the energy derivative with respect to nuclear charge leads to a formula that differs by one term from the result of simple application of Coulomb's law. We have developed a general method to analytically treat derivatives of ECP with respect to nuclear charge. Benchmarking calculations performed on a set of simple molecules show that our formula leads to a systematic decrease in the error connected with the introduction of ECP when compared to all-electron results. Because of a straightforward implementation and relatively low costs of the developed procedure we suggest to use it by default. PMID:23444997

  8. Molecular electrostatic potential at the atomic sites in the effective core potential approximation

    NASA Astrophysics Data System (ADS)

    Lesiuk, Michał; Zachara, Janusz

    2013-02-01

    Considering calculations of the molecular electrostatic potential at the atomic sites (MEP@AS) in the presence of effective core potentials (ECP), we found that the consequent use of the definition of MEP@AS based on the energy derivative with respect to nuclear charge leads to a formula that differs by one term from the result of simple application of Coulomb's law. We have developed a general method to analytically treat derivatives of ECP with respect to nuclear charge. Benchmarking calculations performed on a set of simple molecules show that our formula leads to a systematic decrease in the error connected with the introduction of ECP when compared to all-electron results. Because of a straightforward implementation and relatively low costs of the developed procedure we suggest to use it by default.

  9. Investigating the Effectiveness of Wavelet Approximations in Resizing Images for Ultrasound Image Classification.

    PubMed

    Manzoor, Umar; Nefti, Samia; Ferdinando, Milella

    2016-10-01

    Images are difficult to classify and annotate but the availability of digital image databases creates a constant demand for tools that automatically analyze image content and describe it with either a category or a set of variables. Ultrasound Imaging is very popular and is widely used to see the internal organ(s) condition of the patient. The main target of this research is to develop a robust image processing techniques for a better and more accurate medical image retrieval and categorization. This paper looks at an alternative to feature extraction for image classification such as image resizing technique. A new mean for image resizing using wavelet transform is proposed. Results, using real medical images, have shown the effectiveness of the proposed technique for classification task comparing to bi-cubic interpolation and feature extraction. PMID:27586590

  10. Effective Stress Approximation using Geomechanical Formulation of Fracturing Technology (GFFT) in Petroleum Reservoirs

    NASA Astrophysics Data System (ADS)

    Haghi, A.; Asef, M.; Kharrat, R.

    2010-12-01

    Recently, rock mechanics and geophysics contribution in petroleum industry has been significantly increased. Wellbore stability analysis in horizontal wells, sand production problem while extracting hydrocarbon from sandstone reservoirs, land subsidence due to production induced reservoir compaction, reservoir management, casing shearing are samples of these contributions. In this context, determination of the magnitude and orientation of the in-situ stresses is an essential parameter. This paper is presenting new method to estimate the magnitude of in-situ stresses based on fracturing technology data. Accordingly, kirsch equations for the circular cavities and fracturing technology models in permeable formations have been used to develop an innovative Geomechanical Formulation (GFFT). GFFT introduces a direct reasonable relation between the reservoir stresses and the breakdown pressure of fracture, while the concept of effective stress was employed. Thus, this complex formula contains functions of some rock mechanic parameters such as poison ratio, Biot’s coefficient, Young’s modulus, rock tensile strength, depth of reservoir and breakdown/reservoir pressure difference. Hence, this approach yields a direct method to estimate maximum and minimum effective/insitu stresses in an oil field and improves minimum in-situ stress estimation compared to previous studies. In case of hydraulic fracturing; a new stress analysis method is developed based on well known Darcy equations for fluid flow in porous media which improves in-situ stress estimation using reservoir parameters such as permeability, and injection flow rate. The accuracy of the method would be verified using reservoir data of a case history. The concepts discussed in this research would eventually suggest an alternative methodology with sufficient accuracy to derive in-situ stresses in hydrocarbon reservoirs, while no extra experimental work is accomplished for this purpose.

  11. Space Weather Effects of Coronal Mass Ejection

    NASA Astrophysics Data System (ADS)

    Iyer, K. N.; Jadav, R. M.; Jadeja, A. K.; Manoharan, P. K.; Sharma, Som; Vats, Hari Om

    2006-09-01

    This paper describes the space weather effects of a major CME which was accompanied by extremely violent events on the Sun. The signatures of the event in the interplanetary medium (IPM) sensed by Ooty Radio Telescope, the solar observations by LASCO coronagraph onboard SOHO, GOES X-ray measurements, satellite measurements of the interplanetary parameters, GPS based ionospheric measurements, the geomagnetic storm parameter Dst and ground based ionosonde data are used in the study to understand the space weather effects in the different regions of the solar-terrestrial environment. The effects of this event are compared and possible explanations attempted.

  12. SEASONALITY AND THE EFFECTIVENESS OF MASS VACCINATION

    PubMed Central

    Chao, Dennis L.; Dimitrov, Dobromir T.

    2016-01-01

    Many infectious diseases have seasonal outbreaks, which may be driven by cyclical environmental conditions (e.g., an annual rainy season) or human behavior (e.g., school calendars or seasonal migration). If a pathogen is only transmissible for a limited period of time each year, then seasonal outbreaks could infect fewer individuals than expected given the pathogen’s in-season transmissibility. Influenza, with its short serial interval and long season, probably spreads throughout a population until a substantial fraction of susceptible individuals are infected. Dengue, with a long serial interval and shorter season, may be constrained by its short transmission season rather than the depletion of susceptibles. Using mathematical modeling, we show that mass vaccination is most efficient, in terms of infections prevented per vaccine administered, at high levels of coverage for pathogens that have relatively long epidemic seasons, like influenza, and at low levels of coverage for pathogens with short epidemic seasons, like dengue. Therefore, the length of a pathogen’s epidemic season may need to be considered when evaluating the costs and benefits of vaccination programs. PMID:27105983

  13. Effective medium approximation of the optical properties of electrochromic cerium-titanium oxide compounds

    SciTech Connect

    Rottkay, K. von; Richardson, T.; Rubin, M.; Slack, J.

    1997-07-01

    Cerium titanium oxide samples derived from a solution have been compared against sputtered films over a wide range of different compositions. X-ray diffraction was used to investigate the structural properties of the compound material existing in a two-phase mixture M{sub A}O{sub 2}-M{sub B}O{sub 2}. The optical properties were evaluated over the whole solar spectrum by variable angle spectroscopic ellipsometry combined with spectrophotometry. The spectral complex refractive index was determined for CeO{sub 2} and TiO{sub 2}, as well as for their compounds. To reduce the large number of permutations in composition of multi-component oxides it would be useful to be able to predict the properties of the mixtures from the pure oxide components. Therefore these results were compared to those obtained by effective medium theory utilizing the optical constants of CeO{sub 2} and TiO{sub 2}. In order to investigate the performance as passive counter-electrode in Li{sup +} based electrochromic devices the films were tested by cyclic voltammetry with in-situ transmission control. Chemical composition was measured by Rutherford backscattering spectrometry. Surface morphology was analyzed by atomic force microscopy.

  14. Effective medium approximation of the optical properties of electrochromic cerium-titanium oxide compounds

    NASA Astrophysics Data System (ADS)

    von Rottkay, Nik; Richardson, Terry J.; Rubin, Michael; Slack, J.; Masetti, Enrico; Dautzenberg, G.

    1997-10-01

    Cerium titanium oxide samples produced by sol-gel have been compared against sputtered and pulsed laser deposited films over a wide range of different compositions. X-ray diffraction was used to investigate the structural properties of the compound material existing in a two-phase mixture MAO2-MBO2. The optical properties were evaluated over the whole solar spectrum by variable angle spectroscopic ellipsometry combined with spectrophotometry. The spectral complex refractive index was determined for CeO2 and TiO2, as well as for their compounds. To reduce the large number of permutations in composition of multi-component oxides it would be useful to be able to predict the properties of the mixtures from the pure oxide components. Therefore these results were compared to those obtained by effective medium theory utilizing the optical constants of CeO2 and TiO2. In order to investigate the performance as passive counter-electrode in Li+ based electrochromic devices the films were tested by cyclic voltammetry with in-situ transmission control. Chemical composition was measured by Rutherford backscattering spectrometry. Surface morphology was analyzed by atomic force microscopy.

  15. Alternative approximation concepts for space frame synthesis

    NASA Technical Reports Server (NTRS)

    Lust, R. V.; Schmit, L. A.

    1985-01-01

    A method for space frame synthesis based on the application of a full gamut of approximation concepts is presented. It is found that with the thoughtful selection of design space, objective function approximation, constraint approximation and mathematical programming problem formulation options it is possible to obtain near minimum mass designs for a significant class of space frame structural systems while requiring fewer than 10 structural analyses. Example problems are presented which demonstrate the effectiveness of the method for frame structures subjected to multiple static loading conditions with limits on structural stiffness and strength.

  16. Effects of BMI, Fat Mass, and Lean Mass on Asthma in Childhood: A Mendelian Randomization Study

    PubMed Central

    Granell, Raquel; Henderson, A. John; Evans, David M.; Smith, George Davey; Ness, Andrew R.; Lewis, Sarah; Palmer, Tom M.; Sterne, Jonathan A. C.

    2014-01-01

    Background Observational studies have reported associations between body mass index (BMI) and asthma, but confounding and reverse causality remain plausible explanations. We aim to investigate evidence for a causal effect of BMI on asthma using a Mendelian randomization approach. Methods and Findings We used Mendelian randomization to investigate causal effects of BMI, fat mass, and lean mass on current asthma at age 7½ y in the Avon Longitudinal Study of Parents and Children (ALSPAC). A weighted allele score based on 32 independent BMI-related single nucleotide polymorphisms (SNPs) was derived from external data, and associations with BMI, fat mass, lean mass, and asthma were estimated. We derived instrumental variable (IV) estimates of causal risk ratios (RRs). 4,835 children had available data on BMI-associated SNPs, asthma, and BMI. The weighted allele score was strongly associated with BMI, fat mass, and lean mass (all p-values<0.001) and with childhood asthma (RR 2.56, 95% CI 1.38–4.76 per unit score, p = 0.003). The estimated causal RR for the effect of BMI on asthma was 1.55 (95% CI 1.16–2.07) per kg/m2, p = 0.003. This effect appeared stronger for non-atopic (1.90, 95% CI 1.19–3.03) than for atopic asthma (1.37, 95% CI 0.89–2.11) though there was little evidence of heterogeneity (p = 0.31). The estimated causal RRs for the effects of fat mass and lean mass on asthma were 1.41 (95% CI 1.11–1.79) per 0.5 kg and 2.25 (95% CI 1.23–4.11) per kg, respectively. The possibility of genetic pleiotropy could not be discounted completely; however, additional IV analyses using FTO variant rs1558902 and the other BMI-related SNPs separately provided similar causal effects with wider confidence intervals. Loss of follow-up was unlikely to bias the estimated effects. Conclusions Higher BMI increases the risk of asthma in mid-childhood. Higher BMI may have contributed to the increase in asthma risk toward the end of the 20th century. Please see

  17. Predicting Mass Media Effects: A Cognitive Approach.

    ERIC Educational Resources Information Center

    Gordon, Thomas F.

    In this theoretical working paper, an attempt is made to pull together the two areas of cognitive information processing and emotional arousal, in order to provide a fuller framework for examining media effects. The development of a cognitive-behavioral index is proposed as a research tool resulting from this merger of areas, as are a number of…

  18. Search for effects beyond the Born approximation in polarization transfer observables in e(pol)p elastic scattering.

    SciTech Connect

    Meziane, M.; Brash, E. J.; Jones, M. K.; Luo, W.; Pentchev, L.; Arrington, J.; Hafidi, K.; Reimer, P.; Solvignon, P.; Gep2 Collaboration

    2011-03-29

    Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, G{sub E}/G{sub M}, obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic H({rvec e}, e' {rvec p}) reaction for three different beam energies at a Q{sup 2} = 2.5 GeV{sup 2}, spanning a wide range of the kinematic parameter {epsilon}. The ratio R, which equals {mu}{sub p}G{sub E}/G{sub M} in the Born approximation, is found to be independent of {epsilon} at the 1.5% level. The {epsilon} dependence of the longitudinal polarization transfer component P{sub {ell}} shows an enhancement of (2.3 {+-} 0.6)% relative to the Born approximation at large {epsilon}.

  19. The Effect of Approximating Some Molecular Integrals in Coupled-Cluster Calculations: Fundamental Frequencies and Rovibrational Spectroscopic Constants of Cyclopropenylidene

    NASA Technical Reports Server (NTRS)

    Lee, Timothy J.; Dateo, Christopher E.

    2005-01-01

    The singles and doubles coupled-cluster method that includes a perturbational estimate of connected triple excitations, denoted CCSD(T), has been used, in conjunction with approximate integral techniques, to compute highly accurate rovibrational spectroscopic constants of cyclopropenylidene, C3H2. The approximate integral technique was proposed in 1994 by Rendell and Lee in order to avoid disk storage and input/output bottlenecks, and today it will also significantly aid in the development of algorithms for distributed memory, massively parallel computer architectures. It is shown in this study that use of approximate integrals does not impact the accuracy of CCSD(T) calculations. In addition, the most accurate spectroscopic data yet for C3H2 is presented based on a CCSD(T)/cc-pVQZ quartic force field that is modified to include the effects of core-valence electron correlation. Cyclopropenylidene is of great astronomical and astrobiological interest because it is the smallest aromatic ringed compound to be positively identified in the interstellar medium, and is thus involved in the prebiotic processing of carbon and hydrogen. The singles and doubles coupled-cluster method that includes a perturbational estimate of

  20. Search for effects beyond the Born approximation in polarization transfer observables in $\\vec{e}p$ elastic scattering

    SciTech Connect

    Meziane, M; Brash, E J; Jones, M K; Luo, W; Pentchev, L; Perdrisat, C F; Puckett, A J.R.; Punjabi, V; Wesselmann, F R; Ahmidouch, A; Albayrak, I; Aniol, K A; Arrington, J; Asaturyan, A; Ates, O; Baghdasaryan, H; Benmokhtar, F; Bertozzi, W; Bimbot, L; Bosted, P; Boeglin, W; Butuceanu, C; Carter, P; Chernenko, S; Christy, E; Commisso, M; Cornejo, J C; Covrig, S; Danagoulian, S; Daniel, A; Davidenko, A; Day, D; Dhamija, S; Dutta, D; Ent, R; Frullani, S; Fenker, H; Frlez, E; Garibaldi, F; Gaskell, D; Gilad, S; Goncharenko, Y; Hafidi, K; Hamilton, D; Higinbothan, D W; Hinton, W; Horn, T; Hu, B; Huang, J; Huber, G M; Jensen, E; Kang, H; Keppel, C; Khandaker, M; King, P; Kirillov, D; Kohl, M; Kravtsov, V; Kumbartzki, G; Li, Y; Mamyan, V; Margaziotis, D J; Markowitz, P; Marsh, A; Matulenko, Y; Maxwell, J; Mbianda, G; Meekins, D; Melnick, Y; Miller, J; Mkrtchyan, A; Mkrtchyan, H; Moffit, B; Moreno, O; Mulholland, J; Narayan, A; Nuruzzaman,; Nedev, S; Piasetzky, E; Pierce, W; Piskunov, N M; Prok, Y; Ransome, R D; Razin, D S; Reimer, P E; Reinhold, J; Rondon, O; Shabestari, M; Shahinyan, A; Shestermanov, K; Sirca, S; Sitnik, I; Smykov, L; Smith, G; Solovyev, L; Solvignon, P; Subedi, R; Suleiman, R; Tomasi-Gustafsson, E; Vasiliev, A; Vanderhaeghen, M; Veilleux, M; Wojtsekhowski, B B; Wood, S; Ye, Z; Zanevsky, Y; Zhang, X; Zhang, Y; Zheng, X; Zhu, L

    2011-04-01

    Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, $G_{E}/G_{M}$, obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange (TPEX) contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic $H(\\vec{e},e'\\vec{p})$ reaction for three different beam energies at a fixed squared momentum transfer $Q^2 = 2.5$ GeV$^2$, spanning a wide range of the virtual photon polarization parameter, $\\epsilon$. From these measured polarization observables, we have obtained separately the ratio $R$, which equals $\\mu_p G_{E}/G_{M}$ in the Born approximation, and the longitudinal polarization transfer component $P_\\ell$, with statistical and systematic uncertainties of $\\Delta R \\approx \\pm 0.01 \\mbox{(stat)} \\pm 0.013 \\mbox{(syst)}$ and $\\Delta P_\\ell/P^{Born}_{\\ell} \\approx \\pm 0.006 \\mbox{(stat)}\\pm 0.01 \\mbox{(syst)}$. The ratio $R$ is found to be independent of $\\epsilon$ at the 1.5% level, while the $\\epsilon$ dependence of $P_\\ell$ shows an enhancement of $(2.3 \\pm 0.6) %$ relative to the Born approximation at large $\\epsilon$.

  1. Search for effects beyond the born approximation in polarization transfer observables in e(over→)p elastic scattering.

    PubMed

    Meziane, M; Brash, E J; Gilman, R; Jones, M K; Luo, W; Pentchev, L; Perdrisat, C F; Puckett, A J R; Punjabi, V; Wesselmann, F R; Ahmidouch, A; Albayrak, I; Aniol, K A; Arrington, J; Asaturyan, A; Ates, O; Baghdasaryan, H; Benmokhtar, F; Bertozzi, W; Bimbot, L; Bosted, P; Boeglin, W; Butuceanu, C; Carter, P; Chernenko, S; Christy, E; Commisso, M; Cornejo, J C; Covrig, S; Danagoulian, S; Daniel, A; Davidenko, A; Day, D; Dhamija, S; Dutta, D; Ent, R; Frullani, S; Fenker, H; Frlez, E; Garibaldi, F; Gaskell, D; Gilad, S; Goncharenko, Y; Hafidi, K; Hamilton, D; Higinbotham, D W; Hinton, W; Horn, T; Hu, B; Huang, J; Huber, G M; Jensen, E; Kang, H; Keppel, C; Khandaker, M; King, P; Kirillov, D; Kohl, M; Kravtsov, V; Kumbartzki, G; Li, Y; Mamyan, V; Margaziotis, D J; Markowitz, P; Marsh, A; Matulenko, Y; Maxwell, J; Mbianda, G; Meekins, D; Melnik, Y; Miller, J; Mkrtchyan, A; Mkrtchyan, H; Moffit, B; Moreno, O; Mulholland, J; Narayan, A; Nuruzzaman; Nedev, S; Piasetzky, E; Pierce, W; Piskunov, N M; Prok, Y; Ransome, R D; Razin, D S; Reimer, P E; Reinhold, J; Rondon, O; Shabestari, M; Shahinyan, A; Shestermanov, K; Širca, S; Sitnik, I; Smykov, L; Smith, G; Solovyev, L; Solvignon, P; Subedi, R; Suleiman, R; Tomasi-Gustafsson, E; Vasiliev, A; Vanderhaeghen, M; Veilleux, M; Wojtsekhowski, B B; Wood, S; Ye, Z; Zanevsky, Y; Zhang, X; Zhang, Y; Zheng, X; Zhu, L

    2011-04-01

    Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, G(E)/G(M), obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic H(e[over →],e(')p[over →]) reaction for three different beam energies at a Q(2)=2.5  GeV(2), spanning a wide range of the kinematic parameter ε. The ratio R, which equals μ(p)G(E)/G(M) in the Born approximation, is found to be independent of ε at the 1.5% level. The ε dependence of the longitudinal polarization transfer component P(ℓ) shows an enhancement of (2.3±0.6)% relative to the Born approximation at large ε. PMID:21520982

  2. Gas and solute diffusion in partially saturated porous media: Percolation theory and Effective Medium Approximation compared with lattice Boltzmann simulations

    NASA Astrophysics Data System (ADS)

    Ghanbarian, Behzad; Daigle, Hugh; Hunt, Allen G.; Ewing, Robert P.; Sahimi, Muhammad

    2015-01-01

    Understanding and accurate prediction of gas or liquid phase (solute) diffusion are essential to accurate prediction of contaminant transport in partially saturated porous media. In this study, we propose analytical equations, using concepts from percolation theory and the Effective Medium Approximation (EMA) to model the saturation dependence of both gas and solute diffusion in porous media. The predictions of our theoretical approach agree well with the results of nine lattice Boltzmann simulations. We find that the universal quadratic scaling predicted by percolation theory, combined with the universal linear scaling predicted by the EMA, describes diffusion in porous media with both relatively broad and extremely narrow pore size distributions.

  3. Charts and approximate formulas for the estimation of aeroelastic effects of the lateral control of swept and unswept wings

    NASA Technical Reports Server (NTRS)

    Foss, Kenneth A; Diederich, Franklin W

    1953-01-01

    Charts and approximate formulas are presented for the estimation of static aeroelastic effects on the spanwise lift distribution, rolling-moment coefficient, and rate of roll due to the deflection of ailerons on swept and unswept wings at subsonic and supersonic speeds. Some design considerations brought out by the results of this report are discussed. This report treats the lateral-control case in a manner similar to that employed in NACA Report 1140 for the symmetric-flight case, and is intended to be used in conjunction with NACA Report 1140 and the charts and formulas presented therein.

  4. Spin-current Seebeck effect in an interacting quantum dot: Atomic approximation for the Anderson impurity model

    NASA Astrophysics Data System (ADS)

    Ramos, E.; Silva-Valencia, J.; Franco, R.; Siqueira, E. C.; Figueira, M. S.

    2015-11-01

    We study the spin-current Seebeck effect through an immersed gate defined quantum dot, employing the U-finite atomic method for the single impurity Anderson model. Our description qualitatively confirms some of the results obtained by an earlier Hartree-Fock work, but as our calculation includes the Kondo effect, some new features will appear in the spin-current Seebeck effect S, which as a function of the gate voltage present an oscillatory shape. At intermediate temperatures, our results show a three zero structure and at low temperatures, our results are governed by the emergence of the Kondo peak in the transmittance, which defines the behavior of the shape of the S coefficient as a function of the parameters of the model. The oscillatory behavior obtained by the Hartree-Fock approximation reproduces the shape obtained by us in a non-interacting system (U=0). The S sign is sensitive to different polarization of the quantum dot, and as a consequence the device could be employed to experimentally detect the polarization states of the system. Our results also confirm that the large increase of S upon increasing U, obtained by the mean field approximation, is correct only for low temperatures. We also discuss the role of the Kondo peak in defining the behavior of the spin thermopower at low temperatures.

  5. Covariant approximation averaging

    NASA Astrophysics Data System (ADS)

    Shintani, Eigo; Arthur, Rudy; Blum, Thomas; Izubuchi, Taku; Jung, Chulwoo; Lehner, Christoph

    2015-06-01

    We present a new class of statistical error reduction techniques for Monte Carlo simulations. Using covariant symmetries, we show that correlation functions can be constructed from inexpensive approximations without introducing any systematic bias in the final result. We introduce a new class of covariant approximation averaging techniques, known as all-mode averaging (AMA), in which the approximation takes account of contributions of all eigenmodes through the inverse of the Dirac operator computed from the conjugate gradient method with a relaxed stopping condition. In this paper we compare the performance and computational cost of our new method with traditional methods using correlation functions and masses of the pion, nucleon, and vector meson in Nf=2 +1 lattice QCD using domain-wall fermions. This comparison indicates that AMA significantly reduces statistical errors in Monte Carlo calculations over conventional methods for the same cost.

  6. Terrestrial Planet Formation around Low-Mass Stars: Effect of the Mass of Central Stars

    NASA Astrophysics Data System (ADS)

    Oshino, Shoichi; Matsumoto, Yuji; Kokubo, Eiichiro

    2015-12-01

    The Kepler space telescope has detected several thousand planets and candidates.Their central stars are mainly FGK-type stars.It is difficult to observe M-stars by using visible light since M-stars have their peak radiation in the infrared region.However, recently there are several survey projects for planets around M-stars such as the InfraRed Doppler (IRD) survey of the Subaru telescope.Therefore it is expected that the number of planets around M-stars will increase in the near future.The habitable zone of M-stars is closer to the stars than that of G-stars.For this reason, the possibility of finding habitable planets is expected to be higher.Here we study the formation of close-in terrestrial planets by giant impacts of protoplanets around low-mass stars by using N-body simulations.An important parameter that controls formation processes is the ratio between the physical radius of a planet and its Hill radius, which decreases with the stellar mass.We systematically change the mass of the central stars and investigate its effects on terrestrial planet formation.We find that the mass of the maximum planet decreases with the mass of central stars, while the number of planets in the system increases.We also find that the orbital separation of adjacent planets normalized by their Hill radius increases with the stellar mass.

  7. Effective kaon masses in dense nuclear and neutron matter

    NASA Astrophysics Data System (ADS)

    Waas, T.; Kaiser, N.; Weise, W.

    1996-02-01

    The effective mass and decay width of kaonic modes in baryonic matter are studied within a coupled-channel approach based on the Chiral SU(3) Effective Lagrangian which describes all available low energy data of the coupled overlineKN, π∑, πΛ system. Including Pauli blocking and Fermi motion in the kaon dispersion relation, we find a strong non-linear density dependence of the K - effective mass and decay width in symmetric nuclear matter at densities around 0.1 times normal nuclear matter density ϱ0 due to the in-medium dynamics of the Λ(1405) resonance. At higher densities the K - effective mass decreases slowly but stays above 0.5 mK at least up to densities below 3 ϱ0. In neutron matter the K - effective mass decreases almost linearly with increasing density but remains relatively large ( m K∗ > 0.65 m K) for ϱn ≲ 3 ϱ0. The K + effective mass turns out to increase very slowly with rising density.

  8. Is effective mass in combat sports punching above its weight?

    PubMed

    Lenetsky, Seth; Nates, Roy J; Brughelli, Matt; Harris, Nigel K

    2015-04-01

    The segmental and muscular complexity of the human body can result in challenges when examining the kinetics of impacts. To better understand this complexity, combat sports literature has selected effective mass as a measure of an athlete's inertial contribution to the momentum transfer during the impact of strikes. This measure helps to clarify the analysis of striking kinetics in combat sports. This paper will review: (1) effective mass as a concept and its usage as a measure of impact intensity in combat sports, (2) the neuromuscular pattern known as "double peak muscle activation" which has been theorized to help enhance initial hand velocity upon impact and joint stiffening during impact, (3) the methods and equations used to calculate effective mass, and (4) practitioner recommendations based on the literature. We will argue in this manuscript that the act of punching presents unique challenges to the current understanding of effective mass due to additional force application during impact. This review will improve the understanding of effective mass and its roles in effective striking serving to underpin future research into performance enhancement in striking based combat sports. PMID:25544341

  9. Differential equation based method for accurate approximations in optimization

    NASA Technical Reports Server (NTRS)

    Pritchard, Jocelyn I.; Adelman, Howard M.

    1990-01-01

    A method to efficiently and accurately approximate the effect of design changes on structural response is described. The key to this method is to interpret sensitivity equations as differential equations that may be solved explicitly for closed form approximations, hence, the method is denoted the Differential Equation Based (DEB) method. Approximations were developed for vibration frequencies, mode shapes and static displacements. The DEB approximation method was applied to a cantilever beam and results compared with the commonly-used linear Taylor series approximations and exact solutions. The test calculations involved perturbing the height, width, cross-sectional area, tip mass, and bending inertia of the beam. The DEB method proved to be very accurate, and in most cases, was more accurate than the linear Taylor series approximation. The method is applicable to simultaneous perturbation of several design variables. Also, the approximations may be used to calculate other system response quantities. For example, the approximations for displacements are used to approximate bending stresses.

  10. The effect of rheological approximations on the dynamics and topography in 3D subduction-collision models

    NASA Astrophysics Data System (ADS)

    Pusok, Adina E.; Kaus, Boris J. P.; Popov, Anton A.

    2016-04-01

    Most of the major mountain belts and orogenic plateaus are found within the overlying plate of active or fossil subduction and/or collision zones. Moreover, they evolve differently from one another as the result of specific combinations of surface and mantle processes. These differences arise for several reasons, such as different rheological properties, different amounts of regional isostatic compensation, and different mechanisms by which forces are applied to the convergent plates. Previous 3D geodynamic models of subduction/collision processes have used various rheological approximations, making numerical results difficult to compare, since there is no clear image on the extent of these approximations on the dynamics. Here, we employ the code LaMEM to perform high-resolution long-term 3D simulations of subduction/continental collision in an integrated lithospheric and upper-mantle scale model. We test the effect of rheological approximations on mantle and lithosphere dynamics in a geometrically simplified model setup that resembles a tectonic map of the India-Asia collision zone. We use the "sticky-air" approach to allow for the development of topography and the dynamics of subduction and collision is entirely driven by slab-pull (i.e. "free subduction"). The models exhibit a wide range of behaviours depending on the rheological law employed: from linear to temperature-dependent visco-elasto-plastic rheology that takes into account both diffusion and dislocation creep. For example, we find that slab dynamics varies drastically between end member models: in viscous approximations, slab detachment is slow following a viscous thinning, while for a non-linear visco-elasto-plastic rheology, slab detachment is relatively fast, inducing strong mantle flow in the slab window. We also examine the stress states in the subducting and overriding plates and topography evolution in the upper plate, and we discuss the implications on lithosphere dynamics at convergent margins

  11. Anisotropy of effective electron masses in highly doped nonpolar GaN

    SciTech Connect

    Feneberg, Martin Lange, Karsten; Lidig, Christian; Wieneke, Matthias; Witte, Hartmut; Bläsing, Jürgen; Dadgar, Armin; Krost, Alois; Goldhahn, Rüdiger

    2013-12-02

    The anisotropic effective electron masses in wurtzite GaN are determined by generalized infrared spectroscopic ellipsometry. Nonpolar (112{sup ¯}0) oriented thin films allow accessing both effective masses, m{sub ⊥}{sup *} and m{sub ∥}{sup *}, by determining the screened plasma frequencies. A n-type doping range up to 1.7 × 10{sup 20} cm{sup −3} is investigated. The effective mass ratio m{sub ⊥}{sup *}/m{sub ∥}{sup *} is obtained with highest accuracy and is found to be 1.11 independent on electron concentration up to 1.2 × 10{sup 20} cm{sup −3}. For higher electron concentrations, the conduction band non-parabolicity is mirrored in changes. Absolute values for effective electron masses depend on additional input of carrier concentrations determined by Hall effect measurements. We obtain m{sub ⊥}{sup *}=(0.239±0.004)m{sub 0} and m{sub ∥}{sup *}=(0.216±0.003)m{sub 0} for the parabolic range of the GaN conduction band. Our data are indication of a parabolic GaN conduction band up to an energy of approximately 400 meV above the conduction band minimum.

  12. Active and sterile neutrino mass effects on beta decay spectra

    SciTech Connect

    Boillos, Juan Manuel; Moya de Guerra, Elvira

    2013-06-10

    We study the spectra of the emitted charged leptons in charge current weak nuclear processes to analyze the effect of neutrino masses. Standard active neutrinos are studied here, with masses of the order of 1 eV or lower, as well as sterile neutrinos with masses of a few keV. The latter are warm dark matter (WDM) candidates hypothetically produced or captured as small mixtures with the active neutrinos. We compute differential decay or capture rates spectra in weak charged processes of different nuclei ({sup 3}H, {sup 187}Re, {sup 107}Pd, {sup 163}Ho, etc) using different masses of both active and sterile neutrinos and different values of the mixing parameter.

  13. Higgs mechanism and the added-mass effect

    PubMed Central

    Krishnaswami, Govind S.; Phatak, Sachin S.

    2015-01-01

    In the Higgs mechanism, mediators of the weak force acquire masses by interacting with the Higgs condensate, leading to a vector boson mass matrix. On the other hand, a rigid body accelerated through an inviscid, incompressible and irrotational fluid feels an opposing force linearly related to its acceleration, via an added-mass tensor. We uncover a striking physical analogy between the two effects and propose a dictionary relating them. The correspondence turns the gauge Lie algebra into the space of directions in which the body can move, encodes the pattern of gauge symmetry breaking in the shape of an associated body and relates symmetries of the body to those of the scalar vacuum manifold. The new viewpoint is illustrated with numerous examples, and raises interesting questions, notably on the fluid analogues of the broken symmetry and Higgs particle, and the field-theoretic analogue of the added mass of a composite body.

  14. Probing effective nucleon masses with heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Coupland, D. D. S.; Youngs, M.; Chajecki, Z.; Lynch, W. G.; Tsang, M. B.; Zhang, Y. X.; Famiano, M. A.; Ghosh, T. K.; Giacherio, B.; Kilburn, M. A.; Lee, Jenny; Liu, H.; Lu, F.; Morfouace, P.; Russotto, P.; Sanetullaev, A.; Showalter, R. H.; Verde, G.; Winkelbauer, J.

    2016-07-01

    It has been generally accepted that momentum-dependent potentials for neutrons and protons at energies well away from the Fermi surface cause both to behave as if their inertial masses are effectively 70% of the vacuum values. This similarity in effective masses may no longer hold in dense neutron-rich regions within neutron stars, core-collapse supernovas, and nuclear collisions. There differences in the momentum-dependent symmetry potentials may cause neutron and proton effective masses to differ significantly. We investigate this effect by measuring the energy spectra of neutrons, protons, and charged particles emitted in 112Sn+112Sn and 124Sn+124Sn collisions at Ebeam/A =50 and 120 MeV with precision sufficient to distinguish, in principle, between effective interactions with very different values of the neutron and proton effective masses. These data and model comparisons point the way towards future advances in our capabilities to understand the density and momentum dependence of the nuclear symmetry energy.

  15. An Approach to Rapid Calculation of Temperature Change in Tissue Using Spatial Filters to Approximate Effects of Thermal Conduction

    PubMed Central

    Carluccio, Giuseppe; Erricolo, Danilo; Oh, Sukhoon

    2014-01-01

    We present an approach to performing rapid calculations of temperature within tissue by interleaving, at regular time intervals, 1) an analytical solution to the Pennes (or other desired) bioheat equation excluding the term for thermal conduction and 2) application of a spatial filter to approximate the effects of thermal conduction. Here, the basic approach is presented with attention to filter design. The method is applied to a few different cases relevant to magnetic resonance imaging, and results are compared to those from a full finite-difference (FD) implementation of the Pennes bio-heat equation. It is seen that results of the proposed method are in reasonable agreement with those of the FD approach, with about 15% difference in the calculated maximum temperature increase, but are calculated in a fraction of the time, requiring less than 2% of the calculation time for the FD approach in the cases evaluated. PMID:23358947

  16. Effect of Gauge Boson Mass on the Phase Structure of QED3

    NASA Astrophysics Data System (ADS)

    Li, Jian-Feng; Zhou, Yu-Qing; Feng, Hong-Tao; Sun, Wei-Min; Zong, Hong-Shi

    Dynamical chiral symmetry breaking (DCSB) in QED3 with finite gauge boson mass is studied in the framework of the rainbow approximation of Dyson-Schwinger equations. By adopting a simple gauge boson propagator ansatz at finite temperature, we first numerically solve the Dyson-Schwinger equation for the fermion self-energy to determine the chiral phase diagram of QED3 with finite gauge boson mass at finite chemical potential and finite temperature, then we study the effect of the finite gauge mass on the phase diagram of QED3. It is found that the gauge boson mass ma suppresses the occurrence of DCSB. The area of the region in the chiral phase diagram corresponding to DCSB phase decreases as the gauge boson mass ma increases. In particular, chiral symmetry gets restored when ma is above a certain critical value. In this paper, we use DCSB to describe the antiferromagnetic order and use the gauge boson mass to describe the superconducting order. Our results give qualitatively a physical picture on the competition and coexistence between antiferromagnetic order and superconducting orders in high temperature cuprate superconductors.

  17. Visual stimulus parameters seriously compromise the measurement of approximate number system acuity and comparative effects between adults and children.

    PubMed

    Szűcs, Dénes; Nobes, Alison; Devine, Amy; Gabriel, Florence C; Gebuis, Titia

    2013-01-01

    It has been suggested that a simple non-symbolic magnitude comparison task is sufficient to measure the acuity of a putative Approximate Number System (ANS). A proposed measure of the ANS, the so-called "internal Weber fraction" (w), would provide a clear measure of ANS acuity. However, ANS studies have never presented adequate evidence that visual stimulus parameters did not compromise measurements of w to such extent that w is actually driven by visual instead of numerical processes. We therefore investigated this question by testing non-symbolic magnitude discrimination in seven-year-old children and adults. We manipulated/controlled visual parameters in a more stringent manner than usual. As a consequence of these controls, in some trials numerical cues correlated positively with number while in others they correlated negatively with number. This congruency effect strongly correlated with w, which means that congruency effects were probably driving effects in w. Consequently, in both adults and children congruency had a major impact on the fit of the model underlying the computation of w. Furthermore, children showed larger congruency effects than adults. This suggests that ANS tasks are seriously compromised by the visual stimulus parameters, which cannot be controlled. Hence, they are not pure measures of the ANS and some putative w or ratio effect differences between children and adults in previous ANS studies may be due to the differential influence of the visual stimulus parameters in children and adults. In addition, because the resolution of congruency effects relies on inhibitory (interference suppression) function, some previous ANS findings were probably influenced by the developmental state of inhibitory processes especially when comparing children with developmental dyscalculia and typically developing children. PMID:23882245

  18. Nuclear induces effects and mass correlations in low and multiply charged helium-like ions

    NASA Astrophysics Data System (ADS)

    Stoyanov, Zh K.; Pavlov, R. L.; Mihailov, L. M.; Velchev, Ch J.; Mutafchieva, Y. D.; Tonev, D.; Chamel, N.

    2016-06-01

    The ground-state electron energies, the mass correction and mass polarization of low and multiply charged helium-like ions are analytically and numerically calculated. Approximately 3500 different kinds of ions with charge Z = 2 ÷ 118 are considered. The two-electron Schrodinger equation was solved using a discrete variational-perturbation approach developed by the authors and based on explicitly correlated wave functions. This approach takes into account the motion of the nucleus and yields accurate values for the electron characteristics. The results are presented with and without the inclusion of the mass polarization in the minimization procedure. The relative importance of mass correlations and relativistic effects in the formation of the electron energy characteristics of the helium-like ions are studied for different values of Z. The role of the inclusion of the mass polarization in the minimization procedure as an instrument to present and take into account the effects induced by the nuclear properties, structure and characteristics has been shown.

  19. Vibration of a carbyne nanomechanical mass sensor with surface effect

    NASA Astrophysics Data System (ADS)

    Agwa, M. A.; Eltaher, M. A.

    2016-04-01

    This paper presents a comprehensive model to investigate the influence of surface elasticity and residual surface tension on the natural frequency of flexural vibrations of nanomechanical mass sensor using a carbyne resonator. Carbyne is modeled as an equivalent continuum circular cross-section Timoshenko nanobeam including rotary inertia and shear deformation effects. Surface stress and surface elasticity are presented via the Young-Laplace equation. The analytical solution is presented and verified with molecular dynamics solution. The results show that the carbyne resonator can measure a very small mass with weight below 10-3 zg. The effects of surface elasticity, residual surface tension, carbyne length, and mass position on the fundamental frequencies are illustrated. This study is helpful for characterizing the mechanical behavior of high-precision measurement devices such as chemical and biological sensor.

  20. Inhomogeneities and Effective Mass in Doped Mg2Si

    NASA Astrophysics Data System (ADS)

    Stefanaki, E. C.; Polymeris, G. S.; Ioannou, M.; Pavlidou, E.; Hatzikraniotis, E.; Kyratsi, Th.; Paraskevopoulos, K. M.

    2016-03-01

    Magnesium silicide (Mg2Si)-based materials are promising candidates as thermoelectric components for mid-temperature range (500-900 K) energy conversion. Many different approaches for determining the parabolicity of the conduction band have been suggested in the literature, while the values of the effective mass m* dL reported, lie between 0.46 and 1.1 m0. The aim of this work is to contribute in elucidating the discrepancy observed in the effective mass values of the lower conduction band of highly doped Mg2Si and examine whether this discrepancy could be attributed to the method of determination or to the sample's characteristics. We present the results of effective mass calculations at room temperature (RT) by applying different experimental methods and models (parabolic and non-parabolic) in two different groups of samples; one yielding profound inhomogeneities (Sb-doped) and one yielding homogeneous (Bi-doped) samples. Concluding this analysis, it seems that the lower conduction band of Mg2Si is more likely described as non-parabolic. Comparing the two groups of samples, our analysis indicated that the effective mass may be significantly underestimated for samples with dopant and content-modulated composition.

  1. Intracranial hypertension secondary to a skull lesion without mass effect.

    PubMed

    Serlin, Yonatan; Benifla, Mony; Kesler, Anat; Cohen, Avi; Shelef, Ilan

    2016-09-01

    We report and discuss five patients with intracranial hypertension due to a skull lesion reducing cerebral sinus patency with a compressive, non-thrombotic mechanism. We illustrate the importance of a high level of suspicion for this condition in patients presenting with headache, papilledema and increased intracranial pressure in the absence of focal signs or radiological evidence of mass effect. PMID:27283387

  2. Evaluating the Effectiveness of a Mass Media Ethics Course.

    ERIC Educational Resources Information Center

    Lee, Byung; Padgett, George

    2000-01-01

    Examines the effectiveness of an ethics education component in a media law and ethics course. Suggests that a short-term mass media ethics study could not develop values considered essential for ethical behavior. Argues that students developed more complexity in their reasoning not measurable by the scale. Suggests a course or module on ethics…

  3. Resonance Effects in Magnetically Driven Mass-Spring Oscillations

    ERIC Educational Resources Information Center

    Taylor, Ken

    2011-01-01

    Resonance effects are among the most intriguing phenomena in physics and engineering. The classical case of a mass-spring oscillator driven at its resonant frequency is one of the earliest examples that students encounter. Perhaps the most commonly depicted method of driving the vibrating system is mechanical. An alternative approach presented in…

  4. Approximate kernel competitive learning.

    PubMed

    Wu, Jian-Sheng; Zheng, Wei-Shi; Lai, Jian-Huang

    2015-03-01

    Kernel competitive learning has been successfully used to achieve robust clustering. However, kernel competitive learning (KCL) is not scalable for large scale data processing, because (1) it has to calculate and store the full kernel matrix that is too large to be calculated and kept in the memory and (2) it cannot be computed in parallel. In this paper we develop a framework of approximate kernel competitive learning for processing large scale dataset. The proposed framework consists of two parts. First, it derives an approximate kernel competitive learning (AKCL), which learns kernel competitive learning in a subspace via sampling. We provide solid theoretical analysis on why the proposed approximation modelling would work for kernel competitive learning, and furthermore, we show that the computational complexity of AKCL is largely reduced. Second, we propose a pseudo-parallelled approximate kernel competitive learning (PAKCL) based on a set-based kernel competitive learning strategy, which overcomes the obstacle of using parallel programming in kernel competitive learning and significantly accelerates the approximate kernel competitive learning for large scale clustering. The empirical evaluation on publicly available datasets shows that the proposed AKCL and PAKCL can perform comparably as KCL, with a large reduction on computational cost. Also, the proposed methods achieve more effective clustering performance in terms of clustering precision against related approximate clustering approaches. PMID:25528318

  5. Evaluation of theoretical critical angle including mass effects for channeling by computer simulation

    NASA Astrophysics Data System (ADS)

    Takeuchi, Wataru

    2011-06-01

    The calculated critical angles using the theory included mass effects of Zheng et al. for the axial channeling of ion have been investigated by the computer simulations, making comparisons with the theory of Lindhard and the precise formula of Barrett's numerical simulations. The computer simulations employing the ACOCT program code, which treats the atomic collisions three-dimensionally and is based on the binary collision approximation (BCA), were carried out for the channeling of He, Ne, Ar, Kr, Xe and Rn ions incident along the <1 0 0> axis in Al, Cu, Ag and Pt crystals. A slight dependence of the channeling critical angle on the atomic number of incident ion in the ACOCT results is in agreement with that in the calculated ones using the theory of mass effects. The average critical angles in the ACOCT results for the channeling of six rare gas ions are approximately 5.0/ Z2 times the magnitude of the theoretical critical angles with mass effects, where Z2 is the atomic number of crystal atom. Besides, the results show that the calculated critical angles using the theory with mass effects are substantially larger than those using the theory of Lindhard, the Barrett's formula and the formula by the ACOCT simulations for He ions impinging on Al, Cu, Ag and Pt crystals, and that the channeling critical angles in the ACOCT results agree well with those in the calculated ones using Barrett's formula for 0.6-50 MeV He ions incident on Cu and Ag crystals and 5-50 MeV He ions impinging on Al and Pt crystals.

  6. Estimation of a 2p2h effect on Gamow-Teller transitions within the second Tamm-Dancoff approximation

    NASA Astrophysics Data System (ADS)

    Minato, F.

    2016-04-01

    Two-particle two-hole (2p2h) effect on the Gamow-Teller (GT) transition for neutron-rich nuclei is studied by the second Tamm-Dancoff approximation (STDA) with the Skyrme interaction. Unstable 24O and 34Si and stable 48Ca nuclei are chosen to study the quenching and fragmentation of the GT strengths. Correlation of the 2p2h configurations causes about 20 % quenching and downward shift of GT giant resonances (GTGRs). The residual interaction changing relative angular momentum that appeared in the tensor force part gives a meaningful effect to the GT strength distributions. In this work, 17 - 26 % of the total GT strengths are brought to high-energy region above GTGRs. In particular, the tensor force brings strengths to high energy more than 50 MeV. STDA calculation within a small model space for 2p2h configuration is also performed and experimental data of 48Ca is reproduced reasonably.

  7. Approximate entropy detects the effect of a secondary cognitive task on postural control in healthy young adults: a methodological report

    PubMed Central

    Cavanaugh, James T; Mercer, Vicki S; Stergiou, Nicholas

    2007-01-01

    Background Biomechanical measures of postural stability, while generally useful in neuroscience and physical rehabilitation research, may be limited in their ability to detect more subtle influences of attention on postural control. Approximate entropy (ApEn), a regularity statistic from nonlinear dynamics, recently has demonstrated relatively good measurement precision and shown promise for detecting subtle change in postural control after cerebral concussion. Our purpose was to further explore the responsiveness of ApEn by using it to evaluate the immediate, short-term effect of secondary cognitive task performance on postural control in healthy, young adults. Methods Thirty healthy, young adults performed a modified version of the Sensory Organization Test featuring single (posture only) and dual (posture plus cognitive) task trials. ApEn values, root mean square (RMS) displacement, and equilibrium scores (ES) were calculated from anterior-posterior (AP) and medial-lateral (ML) center of pressure (COP) component time series. For each sensory condition, we compared the ability of the postural control parameters to detect an effect of cognitive task performance. Results COP AP time series generally became more random (higher ApEn value) during dual task performance, resulting in a main effect of cognitive task (p = 0.004). In contrast, there was no significant effect of cognitive task for ApEn values of COP ML time series, RMS displacement (AP or ML) or ES. Conclusion During dual task performance, ApEn revealed a change in the randomness of COP oscillations that occurred in a variety of sensory conditions, independent of changes in the amplitude of COP oscillations. The finding expands current support for the potential of ApEn to detect subtle changes in postural control. Implications for future studies of attention in neuroscience and physical rehabilitation are discussed. PMID:17971209

  8. Precise effective masses from density functional perturbation theory

    NASA Astrophysics Data System (ADS)

    Laflamme Janssen, J.; Gillet, Y.; Poncé, S.; Martin, A.; Torrent, M.; Gonze, X.

    2016-05-01

    The knowledge of effective masses is a key ingredient to analyze numerous properties of semiconductors, like carrier mobilities, (magneto)transport properties, or band extrema characteristics yielding carrier densities and density of states. Currently, these masses are usually calculated using finite-difference estimation of density functional theory (DFT) electronic band curvatures. However, finite differences require an additional convergence study and are prone to numerical noise. Moreover, the concept of effective mass breaks down at degenerate band extrema. We assess the former limitation by developing a method that allows to obtain the Hessian of DFT bands directly, using density functional perturbation theory. Then, we solve the latter issue by adapting the concept of "transport equivalent effective mass" to the k .p ̂ framework. The numerical noise inherent to finite-difference methods is thus eliminated, along with the associated convergence study. The resulting method is therefore more general, more robust, and simpler to use, which makes it especially appropriate for high-throughput computing. After validating the developed techniques, we apply them to the study of silicon, graphane, and arsenic. The formalism is implemented into the abinit software and supports the norm-conserving pseudopotential approach, the projector augmented-wave method, and the inclusion of spin-orbit coupling. The derived expressions also apply to the ultrasoft pseudopotential method.

  9. Gravity effects on neutrino masses in split supersymmetry

    SciTech Connect

    Diaz, Marco Aurelio; Koch, Benjamin; Panes, Boris

    2009-06-01

    The mass differences and mixing angles of neutrinos can neither be explained by R-parity violating split supersymmetry nor by flavor blind quantum gravity alone. It is shown that combining both effects leads, within the allowed parameter range, to good agreement with the experimental results. The atmospheric mass is generated by supersymmetry through mixing between neutrinos and neutralinos, while the solar mass is generated by gravity through flavor blind dimension five operators. Maximal atmospheric mixing forces the tangent squared of the solar angle to be equal to 1/2. The scale of the quantum gravity operator is predicted within a 5% error, implying that the reduced Planck scale should lie around the grand unified theory scale. In this way, the model is very predictive and can be tested at future experiments.

  10. Approximate convective heating equations for hypersonic flows

    NASA Technical Reports Server (NTRS)

    Zoby, E. V.; Moss, J. N.; Sutton, K.

    1979-01-01

    Laminar and turbulent heating-rate equations appropriate for engineering predictions of the convective heating rates about blunt reentry spacecraft at hypersonic conditions are developed. The approximate methods are applicable to both nonreacting and reacting gas mixtures for either constant or variable-entropy edge conditions. A procedure which accounts for variable-entropy effects and is not based on mass balancing is presented. Results of the approximate heating methods are in good agreement with existing experimental results as well as boundary-layer and viscous-shock-layer solutions.

  11. Effect of body mass and clothing on carrion entomofauna.

    PubMed

    Matuszewski, Szymon; Frątczak, Katarzyna; Konwerski, Szymon; Bajerlein, Daria; Szpila, Krzysztof; Jarmusz, Mateusz; Szafałowicz, Michał; Grzywacz, Andrzej; Mądra, Anna

    2016-01-01

    Carcass mass largely affects pattern and rate of carrion decomposition. Supposedly, it is similarly important for carrion entomofauna; however, most of its likely effects have not been tested experimentally. Here, simultaneous effects of carcass mass and clothing are analyzed. A factorial block experiment with four levels of carcass mass (small carcasses 5-15 kg, medium carcasses 15.1-30 kg, medium/large carcasses 35-50 kg, large carcasses 55-70 kg) and two levels of carcass clothing (clothed and unclothed) was made in a grassland habitat of Western Poland. Pig carcasses (N = 24) were grouped into spring, early summer, and late summer blocks. Insects were sampled manually and with pitfall traps. Results demonstrate that insect assemblages are more complex, abundant, and long-lasting on larger carcasses, whereas clothing is of minor importance in this respect. Only large or medium/large carcasses were colonized by all guilds of carrion insects, while small or medium carcasses revealed high underrepresentation of late-colonizing insects (e.g., Cleridae or Nitidulidae). This finding indicates that carcasses weighing about 23 kg-a standard in forensic decomposition studies-give an incomplete picture of carrion entomofauna. Residencies of all forensically relevant insects were distinctly prolonged on larger carcasses, indicating that cadaver mass is a factor of great importance in this respect. The pre-appearance interval of most taxa was found to be unrelated to mass or clothing of a carcass. Moreover, current results suggest that rate of larval development is higher on smaller carcasses. In conclusion, this study demonstrates that carcass mass is a factor of crucial importance for carrion entomofauna, whereas the importance of clothing is small. PMID:25874664

  12. Homogenization limit for a multiband effective mass model in heterostructures

    SciTech Connect

    Morandi, O.

    2014-06-15

    We study the homogenization limit of a multiband model that describes the quantum mechanical motion of an electron in a quasi-periodic crystal. In this approach, the distance among the atoms that constitute the material (lattice parameter) is considered a small quantity. Our model include the description of materials with variable chemical composition, intergrowth compounds, and heterostructures. We derive the effective multiband evolution system in the framework of the kp approach. We study the well posedness of the mathematical problem. We compare the effective mass model with the standard kp models for uniform and non-uniforms crystals. We show that in the limit of vanishing lattice parameter, the particle density obtained by the effective mass model, converges to the exact probability density of the particle.

  13. On the validity of the effective density fluid model as an approximation of a poroelastic sediment layer.

    PubMed

    Bonomo, Anthony L; Chotiros, Nicholas P; Isakson, Marcia J

    2015-08-01

    The effective density fluid model (EDFM) was developed to approximate the behavior of sediments governed by Biots theory of poroelasticity. Previously, it has been shown that the EDFM predicts reflection coefficients and backscattering strengths that are in close agreement with those of the full Biot model for the case of a homogeneous poroelastic half-space. However, it has not yet been determined to what extent the EDFM can be used in place of the full Biot-Stoll model for other cases. Using the finite element method, the flat-interface reflection and rough-interface backscattering predictions of the Biot-Stoll model and the EDFM are compared for the case of a poroelastic layer overlying an elastic substrate. It is shown that considerable differences between the predictions of the two models can exist when the layer is very thin and has a thickness comparable to the wavelength of the shear wave supported by the layer, with a particularly strong disparity under the conditions of a shear wave resonance. For thicker layers, the predictions of the two models are found to be in closer agreement, approaching nearly exact agreement as the layer thickness increases. PMID:26328691

  14. Probing the hydrophobic effect of noncovalent complexes by mass spectrometry.

    PubMed

    Bich, Claudia; Baer, Samuel; Jecklin, Matthias C; Zenobi, Renato

    2010-02-01

    The study of noncovalent interactions by mass spectrometry has become an active field of research in recent years. The role of the different noncovalent intermolecular forces is not yet fully understood since they tend to be modulated upon transfer into the gas phase. The hydrophobic effect, which plays a major role in protein folding, adhesion of lipid bilayers, etc., is absent in the gas phase. Here, noncovalent complexes with different types of interaction forces were investigated by mass spectrometry and compared with the complex present in solution. Creatine kinase (CK), glutathione S-transferase (GST), ribonuclease S (RNase S), and leucine zipper (LZ), which have dissociation constants in the nM range, were studied by native nanoelectrospray mass spectrometry (nanoESI-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with chemical cross-linking (XL). Complexes interacting with hydrogen bonds survived the transfer into gas phase intact and were observed by nanoESI-MS. Complexes that are bound largely by the hydrophobic effect in solution were not detected or only at very low intensity. Complexes with mixed polar and hydrophobic interactions were detected by nanoESI-MS, most likely due to the contribution from polar interactions. All noncovalent complexes could easily be studied by XL MALDI-MS, which demonstrates that the noncovalently bound complexes are conserved, and a real "snap-shot" of the situation in solution can be obtained. PMID:19931466

  15. Normalizing the thermal effects of radiofrequency radiation: body mass versus total body surface area

    SciTech Connect

    Gordon, C.J.

    1987-01-01

    The current guideline for exposure to radiofrequency radiation (RFR) was developed through assessment of the biological effects data collected primarily from the rat. The consensus that a lack of hazardous biological effects occurred below a whole-body-averaged specific absorption rate (SAR) of 4.0 W/kg led to the proposition of a 0.4 W/kg guideline with a built-in safety factor of 10. This paper demonstrates that if the RFR absorption rate in the rat had been normalized with respect to total body surface area rather than body mass, the exposure guideline would be 2.3 W/m2, which translates to an SAR of approximately 0.06 W/kg for an adult human. It is further shown that a given RFR absorption rate, normalized as a fraction of a species' heat loss per unit of surface area, is independent of body mass over a range of 0.03-100 kg; however, a normalization of the RFR absorption rate to heat loss per unit of body mass is highly dependent on the species' mass. Normalizing the rate of RFR absorption to the surface area of the rat indicates that the current RFR exposure guideline of 0.4 W/kg may be too high.

  16. Interactions effectives, théories de champ moyen masses et rayons nucléaires

    NASA Astrophysics Data System (ADS)

    Meyer, J.

    2003-05-01

    Effective interactions, mean field theories, masses and nuclear radii A review of effective interactions used in mean field theories for the description of properties of atomic nuclei is presented. Relativistic as well as non relativistic theories are discussed with a special attention to the cases where their results are very different. We will concentrate on the effective forces built up to investigate the nuclear medium in extreme conditions. Masses and r.m.s. radii along long chain of isotopes will be discussed. Large deformations, as observed in the fission of heavy nuclei, and exotic neutron rich nuclei will be taken as examples of these extreme conditions. Le principal propos de cet ouvrage est : (i) de passer en revue les outils théoriques utilisés sous le sigle ”théories microscopiques de champ moyen ”. Sans entrer dans le détail des formalismes (le lecteur sera systématiquement renvoyé ”pour en savoir plus ” à des cours plus complets qui ont déjà été donnés dans le passé à l'École Joliot-Curie) il s'agira surtout de préciser le contexte, les hypothèses et les approximations qui se cachent sous les sigles : Hartree-Fock (HF), Hartree-Fock-Bogoliubov (HFB), Approximation BCS (HFBCS), Champ Moyen Relativiste (RMF), Approximations Hartree (RH), Hartree-Fock (RHF) et Hartree-Bogoliubov (RHB) Relativistes, ... ; (ii) de présenter la procédure générale et les ingrédients qui entrent dans la construction d'une interaction effective, élément de base de ces théories dont l'intérêt majeur est de livrer des résultats comparables à l'expérience sans paramètre ajustable ; (iii) de discuter des effets des différentes approximations ou interactions effectives sur des résultats expérimentaux pris dans diverses zones de noyaux. Ces discussions seront surtout centrées sur les masses et les rayons des noyaux mais aussi sur certaines quantités plus significatives que l'on peut en extraire : énergies de séparation de deux neutrons

  17. Convective heat and mass transfer on MHD peristaltic flow of Williamson fluid with the effect of inclined magnetic field

    NASA Astrophysics Data System (ADS)

    Veera Krishna, M.; Swarnalathamma, B. V.

    2016-05-01

    In this paper, we discussed the peristaltic MHD flow of an incompressible and electrically conducting Williamson fluid in a symmetric planar channel with heat and mass transfer under the effect of inclined magnetic field. Viscous dissipation and Joule heating are also taken into consideration. Mathematical model is presented by using the long wavelength and low Reynolds number approximations. The differential equations governing the flow are highly nonlinear and thus perturbation solution for small Weissenberg number (We < 1) is presented. Effects of the heat and mass transfer on the longitudinal velocity, temperature and concentration are studied in detail. Main observations are presented in the concluding section. The streamlines pattern is also given due attention.

  18. Effective Power-Law Dependence of Lyapunov Exponents on the Central Mass in Galaxies

    NASA Technical Reports Server (NTRS)

    Delis, N.; Efthymiopoulos, C.; Kalapotharakos, C.

    2015-01-01

    Using both numerical and analytical approaches, we demonstrate the existence of an effective power-law relation L alpha m(sup p) between themean Lyapunov exponent L of stellar orbits chaotically scattered by a supermassive black hole (BH) in the centre of a galaxy and the mass parameter m, i.e. ratio of the mass of the BH over the mass of the galaxy. The exponent p is found numerically to obtain values in the range p approximately equals 0.3-0.5. We propose a theoretical interpretation of these exponents, based on estimates of local 'stretching numbers', i.e. local Lyapunov exponents at successive transits of the orbits through the BH's sphere of influence. We thus predict p = 2/3 - q with q approximately equaling 0.1-0.2. Our basic model refers to elliptical galaxy models with a central core. However, we find numerically that an effective power-law scaling of L with m holds also in models with central cusp, beyond a mass scale up to which chaos is dominated by the influence of the cusp itself. We finally show numerically that an analogous law exists also in disc galaxies with rotating bars. In the latter case, chaotic scattering by the BH affects mainly populations of thick tube-like orbits surrounding some low-order branches of the x(sub 1) family of periodic orbits, as well as its bifurcations at low-order resonances, mainly the inner Lindblad resonance and the 4/1 resonance. Implications of the correlations between L and m to determining the rate of secular evolution of galaxies are discussed.

  19. Galaxy Cluster Gas Mass Fractions From Sunyaev-Zeldovich Effect Measurements: Constraints on Omega(M)

    NASA Technical Reports Server (NTRS)

    Grego, Laura; Carlstrom, John E.; Reese, Erik D.; Holder, Gilbert P.; Holzapfel, William L.; Joy, Marshall K.; Mohr, Joseph J.; Patel, Sandeep

    2001-01-01

    Using sensitive centimeter-wave receivers mounted on the Owens Valley Radio Observatory and Berkeley-Illinois-Maryland-Association millimeter arrays, we have obtained interferometric measurements of the Sunyaev-Zeldovich(SZ) effect toward massive galaxy clusters. We use the SZ data to determine the pressure distribution of the cluster gas and, in combination with published X-ray temperatures, to infer the gas mass and total gravitational mass of 18 clusters. The gas mass fraction, f(g), is calculated for each cluster and is extrapolated to the fiducial radius r(500) using the results of numerical simulations. The mean f(g) within r(500) is 0.081(+ 0.009 / - 0.011) per h(100) (statistical uncertainty at 68% confidence level, assuming Omega(M) = 0.3, Omega(Lambda) = 0.7). We discuss possible sources of systematic errors in the mean f(sub g) measurement. We derive an upper limit for Omega(M) from this sample under the assumption that the mass composition of clusters within r(500) reflects the universal mass composition: Omega(M)h is less than or equal to Omega(B)/f(g). The gas mass fractions depend on cosmology through the angular diameter distance and the r(500) correction factors. For a flat universe (Omega(Lambda) is identical with 1 - Omega(M)) and h = 0.7, we find the measured gas mass fractions are consistent with Omega(M) is less than 0.40, at 68% confidence. Including estimates of the baryons contained in galaxies and the baryons which failed to become bound during the cluster formation process, we find Omega(M) is approximately equal to 0.25.

  20. Mass Effect of Pulmonary Sequestration: Multiloculated–Multiseptated Pneumomediastinum

    PubMed Central

    Unal, Sezin; Türkyılmaz, Canan; Derinkuyu, Betül Emine; Aktaş, Selma; Ergenekon, Ebru; Boyunağa, Öznur; Atalay, Yıldız

    2016-01-01

    Pulmonary sequestration (PS) and pneumomediastinum are two rare clinical diseases. Pneumomediastinum was generally observed in infants either with diseased lungs or who were performed assisted ventilation or resuscitation following birth. It was reported in patients with existing ectopic thoracic kidney and laryngeal cysts however, no coexisting congenital lung anomalies were reported. Here, we report the pneumomediastinum occurred due the extralobar PS because of the mass effect of the lesion. PMID:27123402

  1. Mass and isotopic effects in the Li-Li+ collision

    NASA Astrophysics Data System (ADS)

    Bouledroua, Moncef; Bouchelaghem, Fouzia

    2011-10-01

    We suggest in this work to deal with the ion-atom collision. More precisely, the transport coefficients, the temperature-dependant mobilities, and the charge-transfer phenomena are examined quatum-mechanically. Also is examined the mass and isotopic effects and their behaviour with temperature. To do so, the interatomic potentials are constructed and then injected in the radial wave equation to determine the phase shifts.

  2. Mass Effect of Pulmonary Sequestration: Multiloculated-Multiseptated Pneumomediastinum.

    PubMed

    Unal, Sezin; Türkyılmaz, Canan; Derinkuyu, Betül Emine; Aktaş, Selma; Ergenekon, Ebru; Boyunağa, Öznur; Atalay, Yıldız

    2016-01-01

    Pulmonary sequestration (PS) and pneumomediastinum are two rare clinical diseases. Pneumomediastinum was generally observed in infants either with diseased lungs or who were performed assisted ventilation or resuscitation following birth. It was reported in patients with existing ectopic thoracic kidney and laryngeal cysts however, no coexisting congenital lung anomalies were reported. Here, we report the pneumomediastinum occurred due the extralobar PS because of the mass effect of the lesion. PMID:27123402

  3. Exploring Systematic Effects in the Mass-Metallicity-SFR Relation

    NASA Astrophysics Data System (ADS)

    Telford, O. G.; Dalcanton, J.; Skillman, E.; Conroy, C.

    2016-06-01

    There is evidence that the well-established mass-metallicity relation in galaxies is correlated with a third parameter: star formation rate (SFR). The strength of the correlation between metallicity and SFR may be used along with chemical evolution models to disentangle the relative importance of different physical processes (e.g., infall of pristine gas, metal-enriched outflows), but the observed strength of this correlation varies widely among studies using both single-fiber and IFU spectroscopy. We analyze possible sources of systematic error that could affect the observed strength of this correlation, including choice of metallicity calibration. We present the first analysis of the relation between stellar mass, gas phase metallicity and SFR using a new set of theoretically calibrated abundance diagnostics from Dopita et al. (2013) for ~150,000 star-forming galaxies in the Sloan Digital Sky Survey. Using any of these new strong emission line abundance diagnostics yields a relatively weak correlation between metallicity and SFR at fixed stellar mass, in contrast to the stronger correlation found by some previous studies using other metallicity diagnostics. We also consider other possible sources of bias that can affect the metallicity correlation with SFR, including uncertainty in stellar mass determination, aperture effects, and dust. Finally, we present preliminary results from current work investigating the effect of the choice of binning technique on derivations of direct method metallicities for stacked galaxy spectra and the subsequent impact on the correlation between metallicity and SFR. The large uncertainty in the true strength of the relation between mass, metallicity, and SFR must be carefully accounted for in theoretical studies of chemical evolution.

  4. Isotope mass and charge effects in tokamak plasmas

    SciTech Connect

    Pusztai, I.; Candy, J.; Gohil, P.

    2011-12-15

    The effect of primary ion species of differing charge and mass - specifically, deuterium, hydrogen, and helium - on instabilities and transport is studied in DIII-D plasmas through gyrokinetic simulations with gyro [J. Candy and E. Belli, General Atomics Technical Report No. GA-A26818, 2010]. In linear simulations under imposed similarity of the profiles, there is an isomorphism between the linear growth rates of hydrogen isotopes, but the growth rates are higher for Z > 1 main ions due to the appearance of the charge in the Poisson equation. On ion scales the most significant effect of the different electron-to-ion mass ratio appears through collisions stabilizing trapped electron modes. In nonlinear simulations, significant favorable deviations from pure gyro-Bohm scaling are found due to electron-to-ion mass ratio effects and collisions. The presence of any non-trace impurity species cannot be neglected in a comprehensive simulation of the transport; including carbon impurity in the simulations caused a dramatic reduction of energy fluxes. The transport in the analyzed deuterium and helium discharges could be well reproduced in gyrokinetic and gyrofluid simulations while the significant hydrogen discrepancy is the subject of ongoing investigation.

  5. Improving approximate-optimized effective potentials by imposing exact conditions: Theory and applications to electronic statics and dynamics

    NASA Astrophysics Data System (ADS)

    Kurzweil, Yair; Head-Gordon, Martin

    2009-07-01

    We develop a method that can constrain any local exchange-correlation potential to preserve basic exact conditions. Using the method of Lagrange multipliers, we calculate for each set of given Kohn-Sham orbitals a constraint-preserving potential which is closest to the given exchange-correlation potential. The method is applicable to both the time-dependent (TD) and independent cases. The exact conditions that are enforced for the time-independent case are Galilean covariance, zero net force and torque, and Levy-Perdew virial theorem. For the time-dependent case we enforce translational covariance, zero net force, Levy-Perdew virial theorem, and energy balance. We test our method on the exchange (only) Krieger-Li-Iafrate (xKLI) approximate-optimized effective potential for both cases. For the time-independent case, we calculated the ground state properties of some hydrogen chains and small sodium clusters for some constrained xKLI potentials and Hartree-Fock (HF) exchange. The results (total energy, Kohn-Sham eigenvalues, polarizability, and hyperpolarizability) indicate that enforcing the exact conditions is not important for these cases. On the other hand, in the time-dependent case, constraining both energy balance and zero net force yields improved results relative to TDHF calculations. We explored the electron dynamics in small sodium clusters driven by cw laser pulses. For each laser pulse we compared calculations from TD constrained xKLI, TD partially constrained xKLI, and TDHF. We found that electron dynamics such as electron ionization and moment of inertia dynamics for the constrained xKLI are most similar to the TDHF results. Also, energy conservation is better by at least one order of magnitude with respect to the unconstrained xKLI. We also discuss the problems that arise in satisfying constraints in the TD case with a non-cw driving force.

  6. Improving approximate-optimized effective potentials by imposing exact conditions: Theory and applications to electronic statics and dynamics

    SciTech Connect

    Kurzweil, Yair; Head-Gordon, Martin

    2009-07-15

    We develop a method that can constrain any local exchange-correlation potential to preserve basic exact conditions. Using the method of Lagrange multipliers, we calculate for each set of given Kohn-Sham orbitals a constraint-preserving potential which is closest to the given exchange-correlation potential. The method is applicable to both the time-dependent (TD) and independent cases. The exact conditions that are enforced for the time-independent case are Galilean covariance, zero net force and torque, and Levy-Perdew virial theorem. For the time-dependent case we enforce translational covariance, zero net force, Levy-Perdew virial theorem, and energy balance. We test our method on the exchange (only) Krieger-Li-Iafrate (xKLI) approximate-optimized effective potential for both cases. For the time-independent case, we calculated the ground state properties of some hydrogen chains and small sodium clusters for some constrained xKLI potentials and Hartree-Fock (HF) exchange. The results (total energy, Kohn-Sham eigenvalues, polarizability, and hyperpolarizability) indicate that enforcing the exact conditions is not important for these cases. On the other hand, in the time-dependent case, constraining both energy balance and zero net force yields improved results relative to TDHF calculations. We explored the electron dynamics in small sodium clusters driven by cw laser pulses. For each laser pulse we compared calculations from TD constrained xKLI, TD partially constrained xKLI, and TDHF. We found that electron dynamics such as electron ionization and moment of inertia dynamics for the constrained xKLI are most similar to the TDHF results. Also, energy conservation is better by at least one order of magnitude with respect to the unconstrained xKLI. We also discuss the problems that arise in satisfying constraints in the TD case with a non-cw driving force.

  7. Fractionated Mercury Isotopes in Fish: The Effects of Nuclear Mass, Spin, and Volume

    NASA Astrophysics Data System (ADS)

    Das, R.; Odom, A. L.

    2007-12-01

    Mercury is long known as a common environmental contaminant. In methylated form it is even more toxic and the methylation process is facilitated by microbial activities. Methyl mercury easily crosses cell membrane and accumulates in soft tissues of fishes and finally biomagnifies with increasing trophic levels. Natural variations in the isotopic composition of mercury have been reported and such variations have emphasized mass dependent fractionations, while theory and laboratory experiments indicate that mass-independent isotopic fractionation (MIF) effects are likely to be found as well. This study focuses on the MIF of mercury isotopes in the soft tissues of fishes. Samples include both fresh water and marine fish, from different continents and oceans. Approximately 1 gm of fish soft tissue was dissolved in 5 ml of conc. aqua regia for 24 hrs and filtered through a ¬¬¬100 μm filter paper and diluted with DI water. Hg is measured as a gaseous phase generated by reduction of the sample with SnCl2 in a continuous- flow cold-vapor generator connected to a Thermo-Finnigan Neptune MC-ICPMS. To minimize instrumental fractionation isotope ratios were measured by sample standard bracketing and reported as δ‰ relative to NIST SRM 3133 Hg standard where δAHg = [(A Hg/202Hg)sample/(A Hg/202Hg)NIST313] -1 ×1000‰. In this study we have measured the isotope ratios 198Hg/202Hg, 199Hg/202Hg, 200Hg/202Hg, 201Hg/202Hg and 204Hg/202Hg. In all the fish samples δ198Hg, δ200Hg, δ202Hg, δ204Hg define a mass- dependent fractionation sequence, where as the δ199Hg and δ201Hg depart from the mass- dependent fractionation line and indicate an excess of the odd-N isotopes. The magnitude of the deviation (ΔAHg where A=199 or 201) as obtained by difference between the measured δ199Hg and δ201Hg of the samples and the value obtained by linear scaling defined by the even-N isotopes ranges from approximately 0.2 ‰ to 3‰. The ratios of Δ199Hg /Δ201Hg range from 0.8 to 1

  8. Effective-mass theory of collapsed carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Nakanishi, Takeshi; Ando, Tsuneya

    2015-04-01

    Band structure is theoretically studied in partially flattened carbon nanotubes within an effective-mass scheme. Effects of interwall interactions are shown to be important in nonchiral nanotubes such as zigzag and armchair and can essentially be neglected in chiral nanotubes except in the close vicinity of nonchiral tubes. In fact, interwall interactions significantly modify states depending on relative displacement in the flattened region in nonchiral tubes and can convert semiconducting tubes into metallic and vice versa. They diminish rapidly when the chiral angle deviates from that of the zigzag or armchair tube, although the decay is slower in the vicinity of armchair tubes.

  9. Effects of a mass mortality event on gorgonian reproduction

    NASA Astrophysics Data System (ADS)

    Linares, C.; Coma, R.; Zabala, M.

    2008-03-01

    The impact of a disturbance is normally measured in terms of its effects on adult mortality, whilst the less obvious impact on reproductive biology is generally ignored. Although previous studies have contributed to understanding the effects of a mass mortality of gorgonians in 1999 at NW Mediterranean Sea, none of them have considered its impact on reproduction. The goal of this study was to determine the impact of mass mortality events on the reproduction of the gorgonian Paramuricea clavata, and examine the effect of the damage 1 year (June 2000) and 2 years (June 2001) after the event. The reproductive parameters of female colonies were more affected than those of males. In female colonies that were moderately or severely damaged, the proportion of fertile polyps decreased by about 22-35%, whilst in the worst affected males there was only a 12% decrease. Female colonies showed a progressive decrease in gonadal biomass with increasing damage to a maximum reduction of 73-75% of oocyte production observed in colonies with >33% injury. In contrast, in males, the gonadal biomass decreased rapidly for colonies with 5% of injured surface, with a reduction in spermary production of 49-64%. The same pattern of decrease in gonadal output compared to the extent of the injury was observed in 2001, two years after the mass mortality event. This indicated that the observed pattern was a response to the extent of the injury rather than a direct effect of the event. These severe effects on the reproduction of the red gorgonian species have implications for the recovery of affected populations in the long-term. This study demonstrated that an evaluation of the impact over different demographic parameters is needed to understand all the consequences of these disturbances.

  10. The Effective Temperatures, Radii and Masses of Dwarf Cepheids

    NASA Astrophysics Data System (ADS)

    Kim, Chulhee

    1996-02-01

    Using the flux values determined with the infrared flux method (IRFM) developed by Blackwell and Lynas-Gray (1993), we derived the empirical relationship between flux (F v ) and (V — K) colour appropriate to Dwarf Cepheids. For three Dwarf Cepheids CY Aqr, YZ Boo and SZ Lyn where both VK photometry and radial velocities were available from the literature, effective temperatures were determined using the intrinsic Strömgren indices, model atmosphere grids for (V — K) and the relation between temperature and (V — K) colour. Then, by applying the infrared surface brightness method, radii and distances and hence masses and absolute magnitudes were estimated with effective temperatures determined by three different methods. It was found that the average mass of these variables is about 0.5 solar mass and this result supports the hypothesis that Dwarf Cepheids are pre-white dwarf objects. It was also confirmed that the temperatures determined with the IRFM are most successful in the application of the surface brightness method to the radius estimation of Dwarf Cepheids.

  11. Effects of Distortion on Mass Flow Plug Calibration

    NASA Technical Reports Server (NTRS)

    Sasson, Jonathan; Davis, David O.; Barnhart, Paul J.

    2015-01-01

    A numerical, and experimental investigation to study the effects of flow distortion on a Mass Flow Plug (MFP) used to control and measure mass-flow during an inlet test has been conducted. The MFP was first calibrated using the WIND-US flow solver for uniform (undistorted) inflow conditions. These results are shown to compare favorably with an experimental calibration under similar conditions. The effects of distortion were investigated by imposing distorted flow conditions taken from an actual inlet test to the inflow plane of the numerical simulation. The computational fluid dynamic (CFD) based distortion study only showed the general trend in mass flow rate. The study used only total pressure as the upstream boundary condition, which was not enough to define the flow. A better simulation requires knowledge of the turbulence structure and a specific distortion pattern over a range of plug positions. It is recommended that future distortion studies utilize a rake with at least the same amount of pitot tubes as the AIP rake.

  12. Mass and size effects in three-dimensional vibrofluidized granular mixtures

    NASA Astrophysics Data System (ADS)

    Krouskop, Peter E.; Talbot, Julian

    2003-08-01

    We examine the steady state properties of binary systems of driven inelastic hard spheres. The spheres, which move under the influence of gravity, are contained in a vertical cylinder with a vibrating base. We computed the trajectories of the spheres using an event-driven molecular dynamics algorithm. In the first part of the study, we chose simulation parameters that match those of experiments published by Wildman and Parker. Various properties computed from the simulation including the density profile, granular temperature, and circulation pattern are in good qualitative agreement with the experiments. We then studied the effect of varying the mass ratio and the size ratio independently while holding the other parameters constant. The mass and size ratio are shown to affect the distribution of the energy. The changes in the energy distributions affect the packing fraction and temperature of each component. The temperature of the heavier component has a nonlinear dependence on the mass of the lighter component, while the temperature of the lighter component is approximately proportional to its mass. The temperature of both components is inversely dependent on the size of the smaller component.

  13. Heavy-quark mass effects in Higgs plus jets production

    NASA Astrophysics Data System (ADS)

    Frederix, R.; Frixione, S.; Vryonidou, E.; Wiesemann, M.

    2016-08-01

    We study the production of a Standard Model Higgs boson in the gluon-fusion channel at the 13 TeV LHC. Our results are accurate to the next-to-leading order in QCD, bar for the lack of some two-loop amplitudes, for up to two extra jets and are matched to the P ythia8 Monte Carlo. We address the impact, at the level of inclusive rates and of differential distributions, of the merging of samples characterised by different final-state multiplicities, and of the effects induced by top and bottom masses through heavy-quark loop diagrams. We find that both the merging and the heavy-quark masses must be included in the calculation in order to realistically predict observables of experimental interest.

  14. Mass discharge assessment at a brominated DNAPL site: Effects of known DNAPL source mass removal

    NASA Astrophysics Data System (ADS)

    Johnston, C. D.; Davis, G. B.; Bastow, T. P.; Woodbury, R. J.; Rao, P. S. C.; Annable, M. D.; Rhodes, S.

    2014-08-01

    Management and closure of contaminated sites is increasingly being proposed on the basis of mass flux of dissolved contaminants in groundwater. Better understanding of the links between source mass removal and contaminant mass fluxes in groundwater would allow greater acceptance of this metric in dealing with contaminated sites. Our objectives here were to show how measurements of the distribution of contaminant mass flux and the overall mass discharge emanating from the source under undisturbed groundwater conditions could be related to the processes and extent of source mass depletion. In addition, these estimates of mass discharge were sought in the application of agreed remediation targets set in terms of pumped groundwater quality from offsite wells. Results are reported from field studies conducted over a 5-year period at a brominated DNAPL (tetrabromoethane, TBA; and tribromoethene, TriBE) site located in suburban Perth, Western Australia. Groundwater fluxes (qw; L3/L2/T) and mass fluxes (Jc; M/L2/T) of dissolved brominated compounds were simultaneously estimated by deploying Passive Flux Meters (PFMs) in wells in a heterogeneous layered aquifer. PFMs were deployed in control plane (CP) wells immediately down-gradient of the source zone, before (2006) and after (2011) 69-85% of the source mass was removed, mainly by groundwater pumping from the source zone. The high-resolution (26-cm depth interval) measures of qw and Jc along the source CP allowed investigation of the DNAPL source-zone architecture and impacts of source mass removal. Comparable estimates of total mass discharge (MD; M/T) across the source zone CP reduced from 104 g day- 1 to 24-31 g day- 1 (70-77% reductions). Importantly, this mass discharge reduction was consistent with the estimated proportion of source mass remaining at the site (15-31%). That is, a linear relationship between mass discharge and source mass is suggested. The spatial detail of groundwater and mass flux distributions also

  15. Mass discharge assessment at a brominated DNAPL site: Effects of known DNAPL source mass removal.

    PubMed

    Johnston, C D; Davis, G B; Bastow, T P; Woodbury, R J; Rao, P S C; Annable, M D; Rhodes, S

    2014-08-01

    Management and closure of contaminated sites is increasingly being proposed on the basis of mass flux of dissolved contaminants in groundwater. Better understanding of the links between source mass removal and contaminant mass fluxes in groundwater would allow greater acceptance of this metric in dealing with contaminated sites. Our objectives here were to show how measurements of the distribution of contaminant mass flux and the overall mass discharge emanating from the source under undisturbed groundwater conditions could be related to the processes and extent of source mass depletion. In addition, these estimates of mass discharge were sought in the application of agreed remediation targets set in terms of pumped groundwater quality from offsite wells. Results are reported from field studies conducted over a 5-year period at a brominated DNAPL (tetrabromoethane, TBA; and tribromoethene, TriBE) site located in suburban Perth, Western Australia. Groundwater fluxes (qw; L(3)/L(2)/T) and mass fluxes (Jc; M/L(2)/T) of dissolved brominated compounds were simultaneously estimated by deploying Passive Flux Meters (PFMs) in wells in a heterogeneous layered aquifer. PFMs were deployed in control plane (CP) wells immediately down-gradient of the source zone, before (2006) and after (2011) 69-85% of the source mass was removed, mainly by groundwater pumping from the source zone. The high-resolution (26-cm depth interval) measures of qw and Jc along the source CP allowed investigation of the DNAPL source-zone architecture and impacts of source mass removal. Comparable estimates of total mass discharge (MD; M/T) across the source zone CP reduced from 104gday(-1) to 24-31gday(-1) (70-77% reductions). Importantly, this mass discharge reduction was consistent with the estimated proportion of source mass remaining at the site (15-31%). That is, a linear relationship between mass discharge and source mass is suggested. The spatial detail of groundwater and mass flux distributions

  16. Effects of anions on the positive ion electrospray ionization mass spectra of peptides and proteins.

    PubMed

    Mirza, U A; Chait, B T

    1994-09-15

    Positive ion electrospray ionization mass spectra of polypeptides are usually obtained from solutions that are acidified and therefore contain relatively high concentrations of anions. The present study describes an investigation of the effects of these ubiquitous anions on the positive ion electrospray ionization mass spectra of peptides and proteins. Certain anionic species in the spray solutions were observed to cause a marked decrease in the net average charge of peptide and protein ions in the mass spectra compared to the average charge measured in the absence of these anions. This charge neutralization effect was found to depend solely on the nature of the anionic species and was independent of the source of the anion (acid or salt), with the propensity for neutralization following the order: CCl3COO- > CF3COO- > CH3COO- approximately Cl-. A mechanism for the observed charge reduction effect is proposed that involves two steps. The first step occurs in solution, where an anion pairs with a positively charged basic group on the peptide. The second step occurs during the process of desolvation or in the gas phase, where the ion pair dissociates to yield the neutral acid and the peptide with reduced charge state. The different propensities for charge neutralization of the different anionic species is presumed to reflect the avidity of the anion-peptide interaction. These findings demonstrate that any attempt to correlate the distribution of charge states observed on proteins in the gas phase (by positive ion electrospray ionization mass spectrometry) with the net charge residing on the protein in solution will require that the described anion effect be taken into account. In addition, it appears that some control over the distribution of charge states on peptides and protein ions can be exercised by an appropriate choice of anion in the electrospray solution. PMID:7978296

  17. Nucleon effective E-mass in neutron-rich matter from the Migdal-Luttinger jump

    NASA Astrophysics Data System (ADS)

    Cai, Bao-Jun; Li, Bao-An

    2016-06-01

    The well-known Migdal-Luttinger theorem states that the jump of the single-nucleon momentum distribution at the Fermi surface is equal to the inverse of the nucleon effective E-mass. Recent experiments studying short-range correlations (SRC) in nuclei using electron-nucleus scatterings at the Jefferson National Laboratory (JLAB) together with model calculations constrained significantly the Migdal-Luttinger jump at saturation density of nuclear matter. We show that the corresponding nucleon effective E-mass is consequently constrained to M0*,E / M ≈ 2.22 ± 0.35 in symmetric nuclear matter (SNM) and the E-mass of neutrons is smaller than that of protons in neutron-rich matter. Moreover, the average depletion of the nucleon Fermi sea increases (decreases) approximately linearly with the isospin asymmetry δ according to κp/n ≈ 0.21 ± 0.06 ± (0.19 ± 0.08) δ for protons (neutrons). These results will help improve our knowledge about the space-time non-locality of the single-nucleon potential in neutron-rich nucleonic matter useful in both nuclear physics and astrophysics.

  18. Isotope mass and charge effects in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Pusztai, I.; Candy, J.; Gohil, P.

    2011-12-01

    The effect of primary ion species of differing charge and mass—specifically, deuterium, hydrogen, and helium—on instabilities and transport is studied in DIII-D plasmas through gyrokinetic simulations with gyro [J. Candy and E. Belli, General Atomics Technical Report No. GA-A26818, 2010]. In linear simulations under imposed similarity of the profiles, there is an isomorphism between the linear growth rates of hydrogen isotopes, but the growth rates are higher for Z > 1 main ions due to the appearance of the charge in the Poisson equation. On ion scales the most significant effect of the different electron-to-ion mass ratio appears through collisions stabilizing trapped electron modes. In nonlinear simulations, significant favorable deviations from pure gyro-Bohm scaling are found due to electron-to-ion mass ratio effects and collisions. The presence of any non-trace impurity species cannot be neglected in a comprehensive simulation of the transport; including carbon impurity in the simulations caused a dramatic reduction of energy fluxes. The transport in the analyzed deuterium and helium discharges could be well reproduced in gyrokinetic and gyrofluid simulations while the significant hydrogen discrepancy is the subject of ongoing investigation.

  19. Holographic lattices give the graviton an effective mass.

    PubMed

    Blake, Mike; Tong, David; Vegh, David

    2014-02-21

    We discuss the dc conductivity of holographic theories with translational invariance broken by a background lattice. We show that the presence of the lattice induces an effective mass for the graviton via a gravitational version of the Higgs mechanism. This allows us to obtain, at leading order in the lattice strength, an analytic expression for the dc conductivity in terms of the size of the lattice at the horizon. In locally critical theories this leads to a power law resistivity that is in agreement with an earlier field theory analysis of Hartnoll and Hofman. PMID:24579588

  20. Violence and mass media: are laws and regulations effective?

    PubMed

    Wulff, Christian

    2007-10-01

    In Germany, there are several laws and legal and administrative regulations restricting presentation and propagation of violence in mass media. They have proven to be partly effective. Whilst control and supervision of public media is feasible, the containment of what is distributed over the internet proves to be very difficult. It is well recognized that laws and regulations can be only one part of protection for children and youngsters; school, kindergarten and above all the parents must be educated and held responsible for creating media competence in children and adolescents. PMID:17890154

  1. Isospin effects on the mass dependence of the balance energy

    SciTech Connect

    Gautam, Sakshi; Sood, Aman D.

    2010-07-15

    We study the effect of isospin degree of freedom on balance energy throughout the mass range between 50 and 350 for two sets of isotopic systems with N/A= 0.54 and 0.57 as well as isobaric systems with N/A= 0.5 and 0.58. Our findings indicate that different values of balance energy for two isobaric systems may be mainly due to the Coulomb repulsion. We also demonstrate clearly the dominance of Coulomb repulsion over symmetry energy.

  2. Effects of vertex corrections on diagrammatic approximations applied to the study of transport through a quantum dot

    NASA Astrophysics Data System (ADS)

    Tosi, Leandro; Roura-Bas, Pablo; Llois, Ana María; Manuel, Luis O.

    2011-02-01

    In the present work, we calculate the conductance through a single quantum dot weakly coupled to metallic contacts. We use the spin-1/2 Anderson model to describe the quantum dot, while considering a finite Coulomb repulsion. We solve the interacting system using the noncrossing approximation (NCA) and the one-crossing approximation (OCA). We obtain the linear response conductance as a function of temperature and energy position of the localized level. From the comparison of both approximations we extract the role of the vertex corrections, which are introduced in the OCA calculations and neglected in the NCA scheme. As a function of the energy position, we observe that the diagrams omitted within the NCA are really important for appropriately describing transport phenomena in Kondo systems as well as in the mixed valence regime. On the other hand, as a function of temperature, the corrections introduced by the OCA partly recover the universal scaling properties known from numerical approaches such as the numerical renormalization group.

  3. The Effects of Partial Ionization on Prominence Mass Formation

    NASA Astrophysics Data System (ADS)

    Karpen, J. T.; Olson, K.; DeVore, C. R.; Martinez Gomez, D.; Sokolov, I.

    2015-12-01

    The origin of the prominence mass has been an open question since this cool plasma suspended in the hot corona was first discovered. We have known for a long time that the mass must come from the chromosphere, but it is unclear whether this mass is lifted bodily through magnetic levitation, injected by reconnection-driven upflows, or driven from the chromosphere by evaporation and then condensed. One evaporation-condensation scenario, the thermal nonequilibrium (TNE) model, is the most fully developed, quantitative model for the prominence plasma to date. In the TNE scenario, localized heating concentrated at the coronal loop footpoints produces chromospheric evaporation, filling the flux tube with hot, dense plasma that subsequently collapses radiatively to form cool condensations. Thus far this model has been successful in explaining the key properties of the long, persistent threads and small, highly dynamic, transient blobs in prominences, the damping of large-amplitude field-aligned prominence oscillations, the appearance of horn-shaped features above the cool prominence in EUV images of coronal cavities, and coronal rain in the ambient corona. To date, all studies of TNE have assumed that the plasma is fully ionized, which is appropriate for the hot coronal gas but unrealistic for the cool plasma below ~30,000 K. The energetics, dynamics, and evolutionary time scales of the TNE process are expected to be altered when the effects of ionization and recombination are considered. We have modified ARGOS, our 1D hydrodynamic code with adaptive mesh refinement, to include an equation of state that accounts for the effects of partial ionization of the plasma over a wide range of temperatures and densities. We will discuss the results of these simulations and their comparison with our previous studies of TNE in typical filament-supporting flux tubes. This work was partially supported by NASA's LWS Strategic Capability program.

  4. Strong washout approximation to resonant leptogenesis

    NASA Astrophysics Data System (ADS)

    Garbrecht, Björn; Gautier, Florian; Klaric, Juraj

    2014-09-01

    We show that the effective decay asymmetry for resonant Leptogenesis in the strong washout regime with two sterile neutrinos and a single active flavour can in wide regions of parameter space be approximated by its late-time limit ɛ=Xsin(2varphi)/(X2+sin2varphi), where X=8πΔ/(|Y1|2+|Y2|2), Δ=4(M1-M2)/(M1+M2), varphi=arg(Y2/Y1), and M1,2, Y1,2 are the masses and Yukawa couplings of the sterile neutrinos. This approximation in particular extends to parametric regions where |Y1,2|2gg Δ, i.e. where the width dominates the mass splitting. We generalise the formula for the effective decay asymmetry to the case of several flavours of active leptons and demonstrate how this quantity can be used to calculate the lepton asymmetry for phenomenological scenarios that are in agreement with the observed neutrino oscillations. We establish analytic criteria for the validity of the late-time approximation for the decay asymmetry and compare these with numerical results that are obtained by solving for the mixing and the oscillations of the sterile neutrinos. For phenomenologically viable models with two sterile neutrinos, we find that the flavoured effective late-time decay asymmetry can be applied throughout parameter space.

  5. Improved approximations for control augmented structural synthesis

    NASA Technical Reports Server (NTRS)

    Thomas, H. L.; Schmit, L. A.

    1990-01-01

    A methodology for control-augmented structural synthesis is presented for structure-control systems which can be modeled as an assemblage of beam, truss, and nonstructural mass elements augmented by a noncollocated direct output feedback control system. Truss areas, beam cross sectional dimensions, nonstructural masses and rotary inertias, and controller position and velocity gains are treated simultaneously as design variables. The structural mass and a control-system performance index can be minimized simultaneously, with design constraints placed on static stresses and displacements, dynamic harmonic displacements and forces, structural frequencies, and closed-loop eigenvalues and damping ratios. Intermediate design-variable and response-quantity concepts are used to generate new approximations for displacements and actuator forces under harmonic dynamic loads and for system complex eigenvalues. This improves the overall efficiency of the procedure by reducing the number of complete analyses required for convergence. Numerical results which illustrate the effectiveness of the method are given.

  6. Approximate analysis of effects of large deflections and initial twist on torsional stiffness of a cantilever plate subjected to thermal stresses

    NASA Technical Reports Server (NTRS)

    Heldenfels, Richard R; Vosteen, Louis F

    1958-01-01

    An approximate analysis of the nonlinear effects of initial twist and large deflections on the torsional stiffness of a cantilever plate subjected to a nonuniform temperature distribution is presented. The Von Karman large-deflection equations are satisfied through the use of a variational principle. The results show that initial twist and applied moments can have significant effects on the changes in stiffness produced by nonuniform heating, particularly in the region of the buckling temperature difference. Results calculated by this approximate analysis are in satisfactory agreement with measured torsional deformations and changes in natural frequency. (author)

  7. The Effect of Mergers on Galaxy Cluster Mass Estimates

    NASA Astrophysics Data System (ADS)

    Johnson, Ryan E.; Zuhone, John A.; Thorsen, Tessa; Hinds, Andre

    2015-08-01

    At vertices within the filamentary structure that describes the universal matter distribution, clusters of galaxies grow hierarchically through merging with other clusters. As such, the most massive galaxy clusters should have experienced many such mergers in their histories. Though we cannot see them evolve over time, these mergers leave lasting, measurable effects in the cluster galaxies' phase space. By simulating several different galaxy cluster mergers here, we examine how the cluster galaxies kinematics are altered as a result of these mergers. Further, we also examine the effect of our line of sight viewing angle with respect to the merger axis. In projecting the 6-dimensional galaxy phase space onto a 3-dimensional plane, we are able to simulate how these clusters might actually appear to optical redshift surveys. We find that for those optical cluster statistics which are most often used as a proxy for the cluster mass (variants of σv), the uncertainty due to an inprecise or unknown line of sight may alter the derived cluster masses moreso than the kinematic disturbance of the merger itself. Finally, by examining these, and several other clustering statistics, we find that significant events (such as pericentric crossings) are identifiable over a range of merger initial conditions and from many different lines of sight.

  8. Stellar evolution at high mass including the effect of a stellar wind

    NASA Technical Reports Server (NTRS)

    Stothers, R.; Chin, C.-W.

    1979-01-01

    The effect of a stellar wind on the evolution of stars in the mass range from 15 to 120 solar masses is investigated. All the stellar models are constructed with the use of Cox-Stewart opacities. Four possible cases of mass loss are considered: (1) no mass loss at all; (2) substantial mass loss from stars in all stages of evolution; (3) heavy mass loss from red supergiants only; and (4) sudden and very heavy mass loss from luminous yellow supergiants. The assumption of mass loss during the main-sequence phase of evolution is found to lead to a lowering of the luminosity and, unless the mass loss is extremely heavy, of the effective temperature as well. A comparison of the adopted mass-loss rates with observed rates suggests that stellar winds are probably not an important factor in the evolution of main-sequence stars and supergiants unless the initial masses are greater than about 30 solar masses.

  9. The Effect of QBO on the Total Mass Density

    NASA Astrophysics Data System (ADS)

    Saǧır, Selçuk; Atıcı, Ramazan

    2016-07-01

    The relationship between Quasi-Biennial Oscillation (QBO) measured at 10 hPa altitude and total mass density (TMD) values obtained from NRLMSIS-00 model for 90 km altitude of ionosphere known as Mesosphere-Lower Thermosphere (MLT) region is statistically investigated. For this study, multiple-regression model is used. To see the effect on TMD of QBO directions, Dummy variables are also added to model. In the result of calculations, it is observed that QBO is effected on TMD. It is determined that 69% of variations at TMD can be explainable by QBO. It is determined that the explainable ratio is at the rate of 5%. Also, it is seen that an increase/a decrease of 1 meter per second at QBO give rise to an increase/a decrease of 7,2x10-4 g/cm3 at TMD.

  10. Effect of the pair-structure factor of a particulate medium on scalar wave scattering in the first Born approximation.

    PubMed

    Sahin, Serkan; Korotkova, Olga

    2009-06-15

    Using scattering matrices and the angular spectrum representation of waves, we develop the analytical theory of scattering of random scalar waves from random collections of particles, valid under the first Born approximation. We demonstrate that in the calculation of far-field statistics, such as the spectral density and the spectral degree of coherence, the knowledge of the pair-structure factor of the collection is crucial. We illustrate our analytical approach by considering a numerical example involving scattering of two partially correlated plane waves from a random distribution of spheres. PMID:19529695

  11. Osteocalcin Effect on Human β-Cells Mass and Function.

    PubMed

    Sabek, Omaima M; Nishimoto, Satoru Ken; Fraga, Daniel; Tejpal, Neelam; Ricordi, Camillo; Gaber, A O

    2015-09-01

    The osteoblast-specific hormone osteocalcin (OC) was found to regulate glucose metabolism, fat mass, and β-cell proliferation in mice. Here, we investigate the effect of decarboxylated OC (D-OC) on human β-cell function and mass in culture and in vivo using a Nonobese diabetic-severe combined immunodeficiency mouse model. We found that D-OC at dose ranges from 1.0 to 15 ng/mL significantly augmented insulin content and enhanced human β-cell proliferation of cultured human islets. This was paralleled by increased expression of sulfonylurea receptor protein; a marker of β-cell differentiation and a component of the insulin-secretory apparatus. Moreover, in a Nonobese diabetic-severe combined immunodeficiency mouse model, systemic administration of D-OC at 4.5-ng/h significantly augmented production of human insulin and C-peptide from the grafted human islets. Finally, histological staining of the human islet grafts showed that the improvement in the β-cell function was attributable to an increase in β-cell mass as a result of β-cell proliferation indicated by MKI67 staining together with the increased β-cell number and decreased α-cell number data obtained using laser scanning cytometry. Our data for the first time show D-OC-enhanced β-cell function in human islets and support future exploitation of D-OC-mediated β-cell regulation for developing useful clinical treatments for patients with diabetes. PMID:26151356

  12. Drying temperature effects on fish dry mass measurements

    USGS Publications Warehouse

    Lantry, B.F.; O'Gorman, R.

    2007-01-01

    Analysis of tissue composition in fish often requires dry samples. Time needed to dry fish decreases as temperature is increased, but additional volatile material may be lost. Effects of 10??C temperature increases on percentage dry mass (%DM) were tested against 60??C controls for groups of lake trout Salvelinus namaycush, rainbow smelt Osmerus mordax, slimy sculpin Cottus cognatus, and alewife Alosa pseudoharengus. Lake trout %DMs were lower at greater temperatures, but not significantly different from 60??C controls. Rainbow smelt and slimy sculpin %DMs were lower at greater temperatures and differences were significant when test temperatures reached 90??C. Significant differences were not found in tests using alewives because variability in %DM was high between fish. To avoid inter-fish variability, 30 alewives were each dried successively at 60, 70, 80, and then 90??C and for all fish %DM declined at each higher temperature. In general, %DMs were lower at greater temperatures and after reaching a stable dry weight, fish did not lose additional mass if temperature remained constant. Results indicate that caution should be used when comparing dry mass related indices from fish dried at different temperatures because %DM was negatively related to temperature. The differences in %DM observed with rising temperature could account for substantial portions of the variability in reported energy values for the species tested. Differences in %DM means for the 60 vs. 80??C and 60 vs. 90??C tests for rainbow smelt and alewife could represent of from 8 to 38% of observed annual energy cycles for Lakes Ontario and Michigan.

  13. Diffuse supernova neutrinos: oscillation effects, stellar cooling and progenitor mass dependence

    SciTech Connect

    Lunardini, Cecilia; Tamborra, Irene E-mail: tamborra@mpp.mpg.de

    2012-07-01

    We estimate the diffuse supernova neutrino background (DSNB) using the recent progenitor-dependent, long-term supernova simulations from the Basel group and including neutrino oscillations at several post-bounce times. Assuming multi-angle matter suppression of collective effects during the accretion phase, we find that oscillation effects are dominated by the matter-driven MSW resonances, while neutrino-neutrino collective effects contribute at the 5–10% level. The impact of the neutrino mass hierarchy, of the time-dependent neutrino spectra and of the diverse progenitor star population is 10% or less, small compared to the uncertainty of at least 25% of the normalization of the supernova rate. Therefore, assuming that the sign of the neutrino mass hierarchy will be determined within the next decade, the future detection of the DSNB will deliver approximate information on the MSW-oscillated neutrino spectra. With a reliable model for neutrino emission, its detection will be a powerful instrument to provide complementary information on the star formation rate and for learning about stellar physics.

  14. Effect of body mass index on outcome of labour induction.

    PubMed

    Yousuf, Farheen; Naru, Tahira; Sheikh, Sana

    2016-05-01

    The retrospective study to explore the adverse effect of obesity on pregnancy and labour was conducted at Aga Khan University Hospital, Karachi, Pakistan, and comprised data of all patients booked between 12-14 weeks and required induction of labour from January 1 to December 31, 2012. Women were grouped into two body mass index categories: normal weight (<22.9 kg/ m2) as controls and exposed group (>23 kg/m2). Obesity increased the risk of development of gestational hypertension and diabetes. Therefore obese women were more likely to be induced due to medical indication whether primiparous or multiparous adjusted odds ratio =2.89(95% confidence interval 1.29-6.48) and 2.77 (95% confidence interval 1.07-7.19) respectively. There was increased chance of having caesarean section in primigravida adjusted odds ratio = 1.45 (95% confidence interval 0.72-2.92), duration of caesarean section and blood loss during the procedure were not significantly associated with high body mass index (p>0.05). Obesity may lead to a lot of problems in primigravida, but it did not have major impact. PMID:27183944

  15. Matrix Effects in Biological Mass Spectrometry Imaging: Identification and Compensation

    SciTech Connect

    Lanekoff, Ingela T.; Stevens, Susan; Stenzel-Poore, Mary; Laskin, Julia

    2014-07-21

    Matrix effects in mass spectrometry imaging (MSI) may affect the observed molecular distribution in chemical and biological systems. In this study, we introduce an experimental approach that efficiently compensates for matrix effects in nanospray desorption electrospray ionization (nano-DESI) MSI without introducing any complexity into the experimental protocol. We demonstrate compensation for matrix effects in nano-DESI MSI of phosphatidylcholine (PC) in normal and ischemic mouse brain tissue by doping the nano-DESI solvent with PC standards. Specifically, we use mouse brain tissue of a middle cerebral artery occlusion (MCAO) stroke model with an ischemic region localized to one hemisphere of the brain. Due to similar suppression in ionization of endogenous PC molecules extracted from the tissue and PC standards added to the solvent, matrix effects are eliminated by normalizing the intensity of the sodium and potassium adducts of endogenous PC to the intensity of the corresponding adduct of the PC standard. This approach efficiently compensates for signal variations resulting from differences in the local concentrations of sodium and potassium in tissue sections and from the complexity of the extracted analyte mixture derived from local variations in molecular composition.

  16. Analysis of the spin Hall effect in CuIr alloys: Combined approach of density functional theory and Hartree-Fock approximation

    SciTech Connect

    Xu, Zhuo Gu, Bo; Mori, Michiyasu; Maekawa, Sadamichi; Ziman, Timothy

    2015-05-07

    We analyze the spin Hall effect in CuIr alloys in theory by the combined approach of the density functional theory (DFT) and Hartree-Fock (HF) approximation. The spin Hall angle (SHA) is obtained to be negative without the local correlation effects. After including the local correlation effects of the 5d orbitals of Ir impurities, the SHA becomes positive with realistic correlation parameters and consistent with experiment [Niimi et al., Phys. Rev. Lett. 106, 126601 (2011)]. Moreover, our analysis shows that the DFT + HF approach is a convenient and general method to study the influence of local correlation effects on the spin Hall effect.

  17. Mass effects on angular distribution of sputtered atoms

    NASA Technical Reports Server (NTRS)

    Olson, R. R.; King, M. E.; Wehner, G. K.

    1979-01-01

    Sputtering metal targets at low ion energies (Hg or Ar at less than 300 eV) under normal ion incidence causes the lighter atoms (lighter isotopes or lighter elements of alloys) to be preferentially ejected in a direction normal to the target surface. Experimental results are shown for several elements and alloys at various bombardment energies. The amount of enrichment of the lighter species normal to the target surface decreases quite rapidly with increasing ion energy. The phenomenon is a result of reflective collisions because lighter atoms can be backscattered from heavier ones underneath but not vice versa. The effect provides an explanation of why solar-wind-exposed lunar material is enriched in the heavier isotopes, since sputtered lower-mass elements have a higher chance of achieving the lunar escape velocity.

  18. Mass Loss: Its Effect on the Evolution and Fate of High-Mass Stars

    NASA Astrophysics Data System (ADS)

    Smith, Nathan

    2014-08-01

    Our understanding of massive star evolution is in flux due to recent upheavals in our view of mass loss and observations of a high binary fraction among O-type stars. Mass-loss rates for standard metallicity-dependent winds of hot stars are lower by a factor of 2-3 compared with rates adopted in modern stellar evolution codes, due to the influence of clumping on observed diagnostics. Weaker hot star winds shift the burden of H-envelope removal to the winds, pulsations, and eruptions of evolved supergiants, as well as binary mass transfer. Studies of stripped-envelope supernovae, in particular, require binary mass transfer. Dramatic examples of eruptive mass loss are seen in Type IIn supernovae, which have massive shells ejected just a few years earlier. These eruptions are a prelude to core collapse, and may signify severe instabilities in the latest nuclear burning phases. We encounter the predicament that the most important modes of mass loss are also the most uncertain, undermining the predictive power of single-star evolution models. Moreover, the influence of winds and rotation has been evaluated by testing single-star models against observed statistics that, it turns out, are heavily influenced by binary evolution. Altogether, this may alter our view about the most basic outcomes of massive-star mass loss—are Wolf-Rayet stars and Type Ibc supernovae the products of winds, or are they mostly the result of binary evolution and eruptive mass loss? This is not fully settled, but mounting evidence points toward the latter. This paradigm shift impacts other areas of astronomy, because it changes predictions for ionizing radiation and wind feedback from stellar populations, it may alter conclusions about star-formation rates and initial mass functions, it affects the origin of compact stellar remnants, and it influences how we use supernovae as probes of stellar evolution across cosmic time.

  19. Bounds on the overlap of the Hartree-Fock, optimized effective potential, and density functional approximations with the exact energy eigenstates.

    PubMed

    Thanos, S; Theophilou, A K

    2006-05-28

    In this paper, we examine the limits of accuracy of the single determinant approximations (Hartree-Fock, optimized effective potential, and density functional theory) to the exact energy eigenstates of many electron systems. We show that an approximate Slater determinant of S(z)=M gives maximum accuracy for states with S=M, provided that perturbation theory for the spin up minus spin down potential is applicable. The overlap with the exact energy eigenstates with S not equal M is much smaller. Therefore, for the case that the emphasis is on wave functions, one must use symmetry preserving theories, although this is at the expense of accuracy in energy. PMID:16774321

  20. The effect of local approximations in the ground-state coupled cluster wave function on electron affinities of large molecules

    NASA Astrophysics Data System (ADS)

    Korona, Tatiana

    2012-02-01

    A possibility to calculate electron affinities (EAs) by a software devised for electron excitations is exploited to examine the accuracy of a partly local EA-EOM-CCSD method. In the proposed approach local approximations are applied to the ground-state coupled cluster wave function, while the EAs themselves are obtained in a full configurational space. The results of a numerical test for 14 molecules show that already with standard local settings the method reproduces the nonlocal EAs with the average error of 0.009 eV. Since the EA-EOM step of the calculation requires less computational resources than the computation of the CCSD ground state, the proposed hybrid approach can become a valuable tool for obtaining the EAs for molecules, which are too large for a canonical CCSD calculation, but still small enough for the EA-EOM step to be performed in a nonlocal way.

  1. The Effective Mass of a Ball in the Air

    ERIC Educational Resources Information Center

    Messer, J.; Pantaleone, J.

    2010-01-01

    The air surrounding a projectile affects the projectile's motion in three very different ways: the drag force, the buoyant force, and the added mass. The added mass is an increase in the projectile's inertia from the motion of the air around it. Here we experimentally measure the added mass of a spherical projectile in air. The results agree well…

  2. Mass-dependent and non-mass-dependent isotope effects in ozone photolysis: Resolving theory and experiments

    SciTech Connect

    Cole, Amanda S.; Boering, Kristie A.

    2006-11-14

    In addition to the anomalous {sup 17}O and {sup 18}O isotope effects in the three-body ozone formation reaction O+O{sub 2}+M, isotope effects in the destruction of ozone by photolysis may also play a role in determining the isotopic composition of ozone and other trace gases in the atmosphere. While previous experiments on ozone photolysis at 254 nm were interpreted as evidence for preferential loss of light ozone that is anomalous (or 'non-mass-dependent'), recent semiempirical theoretical calculations predicted a preferential loss of heavy ozone at that wavelength that is mass dependent. Through photochemical modeling results presented here, we resolve this apparent contradiction between experiment and theory. Specifically, we show that the formation of ozone during the UV photolysis experiments is not negligible, as had been assumed, and that the well-known non-mass-dependent isotope effects in ozone formation can account for the non-mass-dependent enrichment of the heavy isotopologs of ozone observed in the experiment. Thus, no unusual non-mass-dependent fractionation in ozone photolysis must be invoked to explain the experimental results. Furthermore, we show that theoretical predictions of a mass-dependent preferential loss of the heavy isotopologs of ozone during UV photolysis are not inconsistent with the experimental data, particularly if mass-dependent isotope effects in the chemical loss reactions of ozone during the photolysis experiments or experimental artifacts enrich the remaining ozone in {sup 17}O and {sup 18}O. Before the calculated fractionation factors can be quantitatively evaluated, however, further investigation of possible mass-dependent isotope effects in the reactions of ozone with O({sup 1}D), O({sup 3}P), O{sub 2}({sup 1}{delta}), and O{sub 2}({sup 1}{sigma}) is needed through experiments we suggest here.

  3. Effect of semi-annual applications of a chlorhexidine/fluoride varnish mixture on approximal caries incidence in schoolchildren. A three-year radiographic study.

    PubMed

    Petersson, L G; Magnusson, K; Andersson, H; Deierborg, G; Twetman, S

    1998-04-01

    Development and progression of approximal caries is still difficult to prevent and control even in societies with declining caries prevalence. In this study, a test group of 115 12-yr old children were treated semi-annually with a mixture (1:1) of a varnish containing 0.1% F (Fluor Protector) and 1.0% chlorhexidine (Cervitec). A reference group of 104 children received fluoride varnish treatment (Fluor Protector) semi-annually. Approximal caries was recorded from bitewing radiographs at baseline and after 3 yr. At baseline, total decayed and filled surfaces (DFS) including enamel caries were 1.79+/-2.36 in the reference group and 2.0+/-2.77 in the test group. After 3 yr, the mean approximal caries incidence including enamel caries was 3.01+/-3.74 and 3.78+/-4.32, respectively. The differences at baseline as well as after 3 yr were not statistically significant. The results showed that both groups had a comparatively low incidence of approximal caries during the experimental period, and suggest that a mixture of fluoride and antibacterial varnish had no additional preventive effect on approximal caries incidence compared with fluoride varnish treatments alone. PMID:9584908

  4. Changes in Kicking Pattern: Effect of Experience, Speed, Accuracy, and Effective Striking Mass

    ERIC Educational Resources Information Center

    Southard, Dan L.

    2014-01-01

    Purpose: The purposes of this study were to: (a) examine the effect of experience and goal constraints (speed, accuracy) on kicking patterns; (b) determine if effective striking mass was independent of ankle velocity at impact; and (c) determine the accuracy of kicks relative to independent factors. Method: Twenty participants were recruited to…

  5. Mass transfer effects on the unsteady mhd radiative- convective flow of a micropolar fluid past a vertical porous plate with variable heat and mass fluxes

    NASA Astrophysics Data System (ADS)

    Reddy, M. Gnaneswara

    2013-03-01

    The problem of unsteady two-dimensional laminar flow of a viscous incompressible micropolar fluid past a vertical porous plate in the presence of a transverse magnetic field and thermal radiation with variable heat and mass fluxes is considered. The free stream velocity is subjected to exponentially increasing or decreasing small perturbations. A uniform magnetic field acts perpendicularly to a porous surface where a micropolar fluid is absorbed with a suction velocity varying with time. The Rosseland approximation is used to describe radiative heat transfer in the limit of optically thick fluids. The effects of the flow parameters and thermophysical properties on the velocity and temperature fields across the boundary layer are investigated. The effects of various parameters on the velocity, microrotation velocity, temperature, and concentration profiles are given graphically, and the values of the skin friction and couple stress coefficients are presented.

  6. Understanding ligand effects in gold clusters using mass spectrometry.

    PubMed

    Johnson, Grant E; Laskin, Julia

    2016-06-21

    This review summarizes recent research on the influence of phosphine ligands on the size, stability, and reactivity of gold clusters synthesized in solution. Sub-nanometer clusters exhibit size- and composition-dependent properties that are unique from those of larger nanoparticles. The highly tunable properties of clusters and their high surface-to-volume ratio make them promising candidates for a variety of technological applications. However, because "each-atom-counts" toward defining cluster properties it is critically important to develop robust synthesis methods to efficiently prepare clusters of predetermined size. For decades phosphines have been known to direct the size-selected synthesis of gold clusters. Despite the preparation of numerous species it is still not understood how different functional groups at phosphine centers affect the size and properties of gold clusters. Using electrospray ionization mass spectrometry (ESI-MS) it is possible to characterize the effect of ligand substitution on the distribution of clusters formed in solution at defined reaction conditions. In addition, ligand exchange reactions on preformed clusters may be monitored using ESI-MS. Collision induced dissociation (CID) may also be employed to obtain qualitative insight into the fragmentation of mixed ligand clusters and the relative binding energies of differently substituted phosphines. Quantitative ligand binding energies and cluster stability may be determined employing surface induced dissociation (SID) in a custom-built Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). Rice-Ramsperger-Kassel-Marcus (RRKM) based modeling of the SID data allows dissociation energies and entropy values to be extracted. The charge reduction and reactivity of atomically precise gold clusters, including partially ligated species generated in the gas-phase by in source CID, on well-defined surfaces may be explored using ion soft landing (SL) in a custom

  7. The effect of measurement errors and computational approximations on a perspective ILM radar image. [airport runways and the microwave landing system

    NASA Technical Reports Server (NTRS)

    Bundick, W. T.

    1975-01-01

    The effect was examined of aircraft position and attitude, of measurement errors, and of computational approximations on the size, shape, and position of a perspective radar image of an airport runway as might be displayed by an independent landing monitor in transport aircraft. The effect on runway image geometry was examined for different aircraft attitudes and different aircraft positions relative to a standard three degree glide slope. Measurement errors investigated were errors in radar azimuth angle and range, and errors in those aircraft parameters supplied to the radar for use in converting the radar image into a perspective format (namely pitch, roll, and altitude). Also investigated were the effects of using certain mathematical approximations, such as small angle, in the coordinate transformation which converts the image to a perspective format.

  8. Strain effects on the optical conductivity of gapped graphene in the presence of Holstein phonons beyond the Dirac cone approximation

    NASA Astrophysics Data System (ADS)

    Yarmohammadi, Mohsen

    2016-08-01

    In this paper we study the optical conductivity and density of states (DOS) of doped gapped graphene beyond the Dirac cone approximation in the presence of electron-phonon (e-ph) interaction under strain, i.e., within the framework of a full π-band Holstein model, by using the Kubo linear response formalism that is established upon the retarded self-energy. A new peak in the optical conductivity for a large enough e-ph interaction strength is found which is associated to transitions between the midgap states and the Van Hove singularities of the main π-band. Optical conductivity decreases with strain and at large strains, the system has a zero optical conductivity at low energies due to optically inter-band excitations through the limit of zero doping. As a result, the Drude weight changes with e-ph interaction, temperature and strain. Consequently, DOS and optical conductivity remains stable with temperature at low e-ph coupling strengths.

  9. On the evaluation of effective density for plate- and membrane-type acoustic metamaterials without mass attached.

    PubMed

    Huang, Tai-Yun; Shen, Chen; Jing, Yun

    2016-08-01

    The effective densities of plate- and membrane-type acoustic metamaterials (AMMs) without mass attached are studied theoretically and numerically. Three models, including the analytic model (based on the plate flexural wave equation and the membrane wave equation), approximate model (under the low frequency approximation), and the finite element method (FEM) model, are first used to calculate the acoustic impedance of square and clamped plates or membranes. The effective density is then obtained using the resulting acoustic impedance and a lumped model. Pressure transmission coefficients of the AMMs are computed using the obtained densities. The effect of the loss from the plate is also taken into account. Results from different models are compared and good agreement is found, particularly between the analytic model and the FEM model. The approximate model is less accurate when the frequency of interest is above the first resonance frequency of the plate or membrane. The approximate model, however, provides simple formulae to predict the effective densities of plate- or membrane-type AMMs and is accurate for the negative density frequency region. The methods presented in this paper are useful in designing AMMs for manipulating acoustic waves. PMID:27586723

  10. Approximate flavor symmetries

    SciTech Connect

    Rasin, A.

    1994-04-01

    We discuss the idea of approximate flavor symmetries. Relations between approximate flavor symmetries and natural flavor conservation and democracy models is explored. Implications for neutrino physics are also discussed.

  11. Effects of mass on aircraft sidearm controller characteristics

    NASA Technical Reports Server (NTRS)

    Wagner, Charles A.

    1994-01-01

    When designing a flight simulator, providing a set of low mass variable-characteristic pilot controls can be very difficult. Thus, a strong incentive exists to identify the highest possible mass that will not degrade the validity of a simulation. The NASA Dryden Flight Research Center has conducted a brief flight program to determine the maximum acceptable mass (system inertia) of an aircraft sidearm controller as a function of force gradient. This information is useful for control system design in aircraft as well as development of suitable flight simulator controls. A modified Learjet with a variable-characteristic sidearm controller was used to obtain data. A boundary was defined between mass considered acceptable and mass considered unacceptable to the pilot. This boundary is defined as a function of force gradient over a range of natural frequencies. This investigation is limited to a study of mass-frequency characteristics only. Results of this investigation are presented in this paper.

  12. Matrix effects in inductively coupled plasma mass spectrometry

    SciTech Connect

    Chen, Xiaoshan

    1995-07-07

    The inductively coupled plasma is an electrodeless discharge in a gas (usually Ar) at atmospheric pressure. Radio frequency energy generated by a RF power source is inductively coupled to the plasma gas through a water cooled load coil. In ICP-MS the {open_quotes}Fassel{close_quotes} TAX quartz torch commonly used in emission is mounted horizontally. The sample aerosol is introduced into the central flow, where the gas kinetic temperature is about 5000 K. The aerosol is vaporized, atomized, excited and ionized in the plasma, and the ions are subsequently extracted through two metal apertures (sampler and skimmer) into the mass spectrometer. In ICP-MS, the matrix effects, or non-spectroscopic interferences, can be defined as the type of interferences caused by dissolved concomitant salt ions in the solution. Matrix effects can be divided into two categories: (1) signal drift due to the deposition of solids on the sampling apertures; and/or (2) signal suppression or enhancement by the presence of the dissolved salts. The first category is now reasonably understood. The dissolved salts, especially refractory oxides, tend to deposit on the cool tip of the sampling cone. The clogging of the orifices reduces the ion flow into the ICP-MS, lowers the pressure in the first stage of ICP-MS, and enhances the level of metal oxide ions. Because the extent of the clogging increases with the time, the signal drifts down. Even at the very early stage of the development of ICP-MS, matrix effects had been observed. Houk et al. found out that the ICP-MS was not tolerant to solutions containing significant amounts of dissolved solids.

  13. Effects of Spaced versus Massed Training in Function Learning

    ERIC Educational Resources Information Center

    McDaniel, Mark A.; Fadler, Cynthia L.; Pashler, Harold

    2013-01-01

    A robust finding in the literature is that spacing material leads to better retention than massing; however, the benefit of spacing for concept learning is less clear. When items are massed, it may help the learner to discover the relationship between instances, leading to better abstraction of the underlying concept. Two experiments addressed…

  14. Modeling multi-layer effects in passive microwave remote sensing of dry snow using Dense Media Radiative Transfer Theory (DMRT) based on quasicrystalline approximation

    USGS Publications Warehouse

    Liang, D.; Xu, X.; Tsang, L.; Andreadis, K.M.; Josberger, E.G.

    2008-01-01

    The Dense Media Radiative Transfer theory (DMRT) of Quasicrystalline Approximation of Mie scattering by sticky particles is used to study the multiple scattering effects in layered snow in microwave remote sensing. Results are illustrated for various snow profile characteristics. Polarization differences and frequency dependences of multilayer snow model are significantly different from that of the single-layer snow model. Comparisons are also made with CLPX data using snow parameters as given by the VIC model. ?? 2007 IEEE.

  15. Effects of intermediate mass black holes on nuclear star clusters

    SciTech Connect

    Mastrobuono-Battisti, Alessandra; Perets, Hagai B.; Loeb, Abraham

    2014-11-20

    Nuclear star clusters (NSCs) are dense stellar clusters observed in galactic nuclei, typically hosting a central massive black hole. Here we study the possible formation and evolution of NSCs through the inspiral of multiple star clusters hosting intermediate mass black holes (IMBHs). Using an N-body code, we examine the dynamics of the IMBHs and their effects on the NSC. We find that IMBHs inspiral to the core of the newly formed NSC and segregate there. Although the IMBHs scatter each other and the stars, none of them is ejected from the NSC. The IMBHs are excited to high eccentricities and their radial density profile develops a steep power-law cusp. The stars also develop a power-law cusp (instead of the central core that forms in their absence), but with a shallower slope. The relaxation rate of the NSC is accelerated due to the presence of IMBHs, which act as massive perturbers. This in turn fills the loss cone and boosts the tidal disruption rate of stars both by the MBH and the IMBHs to a value excluded by rate estimates based on current observations. Rate estimates of tidal disruptions can therefore provide a cumulative constraint on the existence of IMBHs in NSCs.

  16. Does Taste Perception Effect Body Mass Index in Preschool Children?

    PubMed Central

    Markam, Vandana; Singh, Garima; Chakravarthy, Kalyan; Gupta, Manoj

    2015-01-01

    Introduction Eating trends established early in life leads to chronic life style disorders such as obesity, which is hard to overcome as child comes of age. Energy expenditure is less but caloric intake is high leading to disparity of energy balance in turn leading to obesity. Obesity is the outcome of a disparity between energy expenditure and caloric intake. Genes play a role in establishing eating habits, which is termed as genetic sensitivity to taste. Aim To determine taste perception effect on body mass index (BMI) in preschool central Indian urban children. Materials and Methods A total of 500 children of 3-6 years were selected and genetic taste perception was assessed using PROP sensitivity test. Anthropometric measurements were recorded to obtain BMI value. Categorical variables were analysed using Pearson’s Chi square test. Results Non tasters were mostly in overweight category i.e. 73.30% where as more number of tasters i.e. 59.70% were in underweight category. A significant correlation is seen between BMI and taste perception. No statistically significant correlation was seen between oral hygiene and taste perception. Females were predominant in both the tasters and non tasters categories. Conclusion Taste perception showed significant relationship with BMI of children between 3-6-year-old children. PMID:26816983

  17. Device-Level Models Using Multi-Valley Effective Mass

    NASA Astrophysics Data System (ADS)

    Baczewski, Andrew D.; Frees, Adam; Gamble, John King; Gao, Xujiao; Jacobson, N. Tobias; Mitchell, John A.; Montaño, Inès; Muller, Richard P.; Nielsen, Erik

    2015-03-01

    Continued progress in quantum electronics depends critically on the availability of robust device-level modeling tools that capture a wide range of physics and effective mass theory (EMT) is one means of building such models. Recent developments in multi-valley EMT show quantitative agreement with more detailed atomistic tight-binding calculations of phosphorus donors in silicon (Gamble, et. al., arXiv:1408.3159). Leveraging existing PDE solvers, we are developing a framework in which this multi-valley EMT is coupled to an integrated device-level description of several experimentally active qubit technologies. Device-level simulations of quantum operations will be discussed, as well as the extraction of process matrices at this level of theory. The authors gratefully acknowledge support from the Sandia National Laboratories Truman Fellowship Program, which is funded by the Laboratory Directed Research and Development (LDRD) Program. 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 Security Administration under contract DE-AC04-94AL85000.

  18. Multivalley effective mass theory simulation of donors in silicon

    NASA Astrophysics Data System (ADS)

    Gamble, John King; Jacobson, N. Tobias; Nielsen, Erik; Baczewski, Andrew D.; Moussa, Jonathan E.; Montaño, Inès; Muller, Richard P.

    2015-06-01

    Last year, Salfi et al. made the first direct measurements of a donor wave function and found extremely good theoretical agreement with atomistic tight-binding theory results [Salfi et al., Nat. Mater. 13, 605 (2014), 10.1038/nmat3941]. Here, we show that multivalley effective mass theory, applied properly, does achieve close agreement with tight-binding results and hence gives reliable predictions. To demonstrate this, we variationally solve the coupled six-valley Shindo-Nara equations, including silicon's full Bloch functions. Surprisingly, we find that including the full Bloch functions necessitates a tetrahedral, rather than spherical, donor central cell correction to accurately reproduce the experimental energy spectrum of a phosphorus impurity in silicon. We cross-validate this method against atomistic tight-binding calculations, showing that the two theories agree well for the calculation of donor-donor tunnel coupling. Further, we benchmark our results by performing a statistical uncertainty analysis, confirming that derived quantities such as the wave function profile and tunnel couplings are robust with respect to variational energy fluctuations. Finally, we apply this method to exhaustively enumerate the tunnel coupling for all donor-donor configurations within a large search volume, demonstrating conclusively that the tunnel coupling has no spatially stable regions. Although this instability is problematic for reliably coupling donor pairs for two-qubit operations, we identify specific target locations where donor qubits can be placed with scanning tunneling microscopy technology to achieve reliably large tunnel couplings.

  19. Entrainment coefficient and effective mass for conduction neutrons in neutron star crust: simple microscopic models

    NASA Astrophysics Data System (ADS)

    Carter, Brandon; Chamel, Nicolas; Haensel, Pawel

    2005-02-01

    In the inner crust of a neutron star, at densities above the "drip" threshold, unbound "conduction" neutrons can move freely past through the ionic lattice formed by the nuclei. The relative current density ni=nv¯i of such conduction neutrons will be related to the corresponding mean particle momentum pi by a proportionality relation of the form ni=Kpi in terms of a physically well defined mobility coefficient K whose value in this context has not been calculated before. Using methods from ordinary solid state and nuclear physics, a simple quantum mechanical treatment based on the independent particle approximation, is used here to formulate K as the phase space integral of the relevant group velocity over the neutron Fermi surface. The result can be described as an "entrainment" that changes the ordinary neutron mass m to a macroscopic effective mass per neutron that will be given—subject to adoption of a convention specifying the precise number density n of the neutrons that are considered to be "free"—by m⋆=n/K. The numerical evaluation of the mobility coefficient is carried out for nuclear configurations of the "lasagna" and "spaghetti" type that may be relevant at the base of the crust. Extrapolation to the middle layers of the inner crust leads to the unexpected prediction that m⋆ will become very large compared with m.

  20. NIMROD: a program for inference via a normal approximation of the posterior in models with random effects based on ordinary differential equations.

    PubMed

    Prague, Mélanie; Commenges, Daniel; Guedj, Jérémie; Drylewicz, Julia; Thiébaut, Rodolphe

    2013-08-01

    Models based on ordinary differential equations (ODE) are widespread tools for describing dynamical systems. In biomedical sciences, data from each subject can be sparse making difficult to precisely estimate individual parameters by standard non-linear regression but information can often be gained from between-subjects variability. This makes natural the use of mixed-effects models to estimate population parameters. Although the maximum likelihood approach is a valuable option, identifiability issues favour Bayesian approaches which can incorporate prior knowledge in a flexible way. However, the combination of difficulties coming from the ODE system and from the presence of random effects raises a major numerical challenge. Computations can be simplified by making a normal approximation of the posterior to find the maximum of the posterior distribution (MAP). Here we present the NIMROD program (normal approximation inference in models with random effects based on ordinary differential equations) devoted to the MAP estimation in ODE models. We describe the specific implemented features such as convergence criteria and an approximation of the leave-one-out cross-validation to assess the model quality of fit. In pharmacokinetics models, first, we evaluate the properties of this algorithm and compare it with FOCE and MCMC algorithms in simulations. Then, we illustrate NIMROD use on Amprenavir pharmacokinetics data from the PUZZLE clinical trial in HIV infected patients. PMID:23764196

  1. Effective gravitational mass of the Ayón-Beato and García metric

    NASA Astrophysics Data System (ADS)

    Sinha, A. K.; Pandey, G. K.; Bhaskar, A. K.; Rai, B. C.; Jha, A. K.; Kumar, S.; Xulu, S. S.

    2015-06-01

    In this paper, we calculate the effective gravitational mass of Ayón-Beato and García (AG) regular (nonsingular) static spherically symmetric asymptotically Minkowskian metric that is a solution to Einstein’s equations coupled with a nonlinear electromagnetic field. The effective gravitational mass is negative, zero, or positive that depends on the ratio of magnitude of electric charge to the ADM mass and the ratio of the radial distance to the ADM mass. As expected, at large values of radial distance, our result gives effective gravitational mass of the Reissner-Nordström metric.

  2. Tunneling effects in electromagnetic wave scattering by nonspherical particles: A comparison of the Debye series and physical-geometric optics approximations

    NASA Astrophysics Data System (ADS)

    Bi, Lei; Yang, Ping

    2016-07-01

    The accuracy of the physical-geometric optics (PG-O) approximation is examined for the simulation of electromagnetic scattering by nonspherical dielectric particles. This study seeks a better understanding of the tunneling effect on the phase matrix by employing the invariant imbedding method to rigorously compute the zeroth-order Debye series, from which the tunneling efficiency and the phase matrix corresponding to the diffraction and external reflection are obtained. The tunneling efficiency is shown to be a factor quantifying the relative importance of the tunneling effect over the Fraunhofer diffraction near the forward scattering direction. Due to the tunneling effect, different geometries with the same projected cross section might have different diffraction patterns, which are traditionally assumed to be identical according to the Babinet principle. For particles with a fixed orientation, the PG-O approximation yields the external reflection pattern with reasonable accuracy, but ordinarily fails to predict the locations of peaks and minima in the diffraction pattern. The larger the tunneling efficiency, the worse the PG-O accuracy is at scattering angles less than 90°. If the particles are assumed to be randomly oriented, the PG-O approximation yields the phase matrix close to the rigorous counterpart, primarily due to error cancellations in the orientation-average process. Furthermore, the PG-O approximation based on an electric field volume-integral equation is shown to usually be much more accurate than the Kirchhoff surface integral equation at side-scattering angles, particularly when the modulus of the complex refractive index is close to unity. Finally, tunneling efficiencies are tabulated for representative faceted particles.

  3. Modification of nuclear mass formula by considering isospin effects

    SciTech Connect

    Wang Ning; Liu Min; Wu Xizhen

    2010-04-15

    We propose a semiempirical nuclear mass formula based on the macroscopic-microscopic method in which the isospin and mass dependence of model parameters are investigated with the Skyrme energy density functional. The number of model parameters is considerably reduced compared with the finite range droplet model. The rms deviation with respect to 2149 measured nuclear masses is reduced by 21%, falling to 0.516 MeV. The new magic number N=16 in light neutron-rich nuclei and the shape coexistence phenomena for some nuclei have been examined with the model. The shell corrections of superheavy nuclei are also predicted.

  4. Differential equation based method for accurate approximations in optimization

    NASA Technical Reports Server (NTRS)

    Pritchard, Jocelyn I.; Adelman, Howard M.

    1990-01-01

    This paper describes a method to efficiently and accurately approximate the effect of design changes on structural response. The key to this new method is to interpret sensitivity equations as differential equations that may be solved explicitly for closed form approximations, hence, the method is denoted the Differential Equation Based (DEB) method. Approximations were developed for vibration frequencies, mode shapes and static displacements. The DEB approximation method was applied to a cantilever beam and results compared with the commonly-used linear Taylor series approximations and exact solutions. The test calculations involved perturbing the height, width, cross-sectional area, tip mass, and bending inertia of the beam. The DEB method proved to be very accurate, and in msot cases, was more accurate than the linear Taylor series approximation. The method is applicable to simultaneous perturbation of several design variables. Also, the approximations may be used to calculate other system response quantities. For example, the approximations for displacement are used to approximate bending stresses.

  5. The effects of damping on the approximate teleportation and nonclassical properties in the atom-field interaction

    NASA Astrophysics Data System (ADS)

    Daneshmand, R.; Tavassoly, M. K.

    2016-04-01

    Based on the Jaynes-Cummings interaction model of a Ξ-type three-level atom with a single-mode quantized field, the effect of damping on teleportation is studied. To achieve this purpose, we have taken into account the decay rates of the two upper atomic levels. The influences of such atomic damping on the teleportation of atomic as well as field states are evaluated. It is shown that, by increasing the damping parameter the fidelity and success probability is decreased. Finally, beside our main motivation of the paper, we end it with some marginal, however, of interest purposes like the analyzing the dynamics of a few interesting physical properties such as entanglement, Mandel parameter and quadrature squeezing in the presence of damping.

  6. A self-consistent, microenvironment modulated screened coulomb potential approximation to calculate pH-dependent electrostatic effects in proteins.

    PubMed

    Mehler, E L; Guarnieri, F

    1999-07-01

    An improved approach is presented for calculating pH-dependent electrostatic effects in proteins using sigmoidally screened Coulomb potentials (SCP). It is hypothesized that a key determinant of seemingly aberrant behavior in pKa shifts is due to the properties of the unique microenvironment around each residue. To help demonstrate this proposal, an approach is developed to characterize the microenvironments using the local hydrophobicity/hydrophilicity around each residue of the protein. The quantitative characterization of the microenvironments shows that the protein is a complex mosaic of differing dielectric regions that provides a physical basis for modifying the dielectric screening functions: in more hydrophobic microenvironments the screening decreases whereas the converse applies to more hydrophilic regions. The approach was applied to seven proteins providing more than 100 measured pKa values and yielded a root mean square deviation of 0.5 between calculated and experimental values. The incorporation of the local hydrophobicity characteristics into the algorithm allowed the resolution of some of the more intractable problems in the calculation of pKa. Thus, the divergent shifts of the pKa of Glu-35 and Asp-66 in hen egg white lysozyme, which are both about 90% buried, was correctly predicted. Mechanistically, the divergence occurs because Glu-35 is in a hydrophobic microenvironment, while Asp-66 is in a hydrophilic microenvironment. Furthermore, because the calculation of the microenvironmental effects takes very little CPU time, the computational speed of the SCP formulation is conserved. Finally, results from different crystal structures of a given protein were compared, and it is shown that the reliability of the calculated pKa values is sufficient to allow identification of conformations that may be more relevant for the solution structure. PMID:10388736

  7. Exponential approximations in optimal design

    NASA Technical Reports Server (NTRS)

    Belegundu, A. D.; Rajan, S. D.; Rajgopal, J.

    1990-01-01

    One-point and two-point exponential functions have been developed and proved to be very effective approximations of structural response. The exponential has been compared to the linear, reciprocal and quadratic fit methods. Four test problems in structural analysis have been selected. The use of such approximations is attractive in structural optimization to reduce the numbers of exact analyses which involve computationally expensive finite element analysis.

  8. Strong washout approximation to resonant leptogenesis

    SciTech Connect

    Garbrecht, Björn; Gautier, Florian; Klaric, Juraj E-mail: florian.gautier@tum.de

    2014-09-01

    We show that the effective decay asymmetry for resonant Leptogenesis in the strong washout regime with two sterile neutrinos and a single active flavour can in wide regions of parameter space be approximated by its late-time limit ε=Xsin(2φ)/(X{sup 2}+sin{sup 2}φ), where X=8πΔ/(|Y{sub 1}|{sup 2}+|Y{sub 2}|{sup 2}), Δ=4(M{sub 1}-M{sub 2})/(M{sub 1}+M{sub 2}), φ=arg(Y{sub 2}/Y{sub 1}), and M{sub 1,2}, Y{sub 1,2} are the masses and Yukawa couplings of the sterile neutrinos. This approximation in particular extends to parametric regions where |Y{sub 1,2}|{sup 2}>> Δ, i.e. where the width dominates the mass splitting. We generalise the formula for the effective decay asymmetry to the case of several flavours of active leptons and demonstrate how this quantity can be used to calculate the lepton asymmetry for phenomenological scenarios that are in agreement with the observed neutrino oscillations. We establish analytic criteria for the validity of the late-time approximation for the decay asymmetry and compare these with numerical results that are obtained by solving for the mixing and the oscillations of the sterile neutrinos. For phenomenologically viable models with two sterile neutrinos, we find that the flavoured effective late-time decay asymmetry can be applied throughout parameter space.

  9. Schottky effect in the i -Zn-Ag-Sc-Tm icosahedral quasicrystal and its 1/1 Zn-Sc-Tm approximant

    NASA Astrophysics Data System (ADS)

    Jazbec, S.; Kashimoto, S.; Koželj, P.; Vrtnik, S.; Jagodič, M.; Jagličić, Z.; Dolinšek, J.

    2016-02-01

    The analysis of low-temperature specific heat of rare-earth (RE)-containing quasicrystals and periodic approximants and consequent interpretation of their electronic properties in the T →0 limit is frequently hampered by the Schottky effect, where crystalline electric fields lift the degeneracy of the RE-ion Hund's rule ground state and introduce additional contribution to the specific heat. In this paper we study the low-temperature specific heat of a thulium-containing i -Zn-Ag-Sc-Tm icosahedral quasicrystal and its 1/1 Zn-Sc-Tm approximant, both being classified as "Schottky" systems. We have derived the crystal-field Hamiltonian for pentagonal symmetry of the crystalline electric field, pertinent to the class of Tsai-type icosahedral quasicrystals and their approximants, where the RE ions are located on fivefold axes of the icosahedral atomic cluster. Using the leading term of this Hamiltonian, we have calculated analytically the Schottky specific heat in the presence of an external magnetic field and made comparison to the experimental specific heat of the investigated quasicrystal and approximant. When the low-temperature specific heat C is analyzed in a C /T versus T2 scale (as it is customarily done for metallic specimens), the Schottky specific heat yields an upturn in the T →0 limit that cannot be easily distinguished from a similar upturn produced by the electron-electron interactions in exchange-enhanced systems and strongly correlated systems. Our results show that extraction of the electronic properties of RE-containing quasicrystals from their low-temperature specific heat may be uncertain in the presence of the Schottky effect.

  10. Anabolic implant effects on visceral organ mass, chemical body composition, and estimated energetic efficiency in cloned (genetically identical) beef steers.

    PubMed

    Hutcheson, J P; Johnson, D E; Gerken, C L; Morgan, J B; Tatum, J D

    1997-10-01

    Six sets of four genetically identical Brangus steers (n = 24; X BW 409 kg) were used to determine the effect of different anabolic implants on visceral organ mass, chemical body composition, estimated tissue deposition, and energetic efficiency. Steers within a clone set were randomly assigned to one of the following implant treatments: C, no implant; E, estrogenic; A, androgenic, or AE, androgenic + estrogenic. Steers were slaughtered 112 d after implanting; visceral organs were weighed and final body composition determined by mechanical grinding and chemical analysis of the empty body. Mass of the empty gastrointestinal tract (GIT) was reduced approximately 9% (P < .10) in steers implanted with estrogen alone or in combination with an androgen. Liver mass was increased (P < .10) from 6 to 14% by implants. Steers implanted with the AE combination had greater (P < .10) daily protein accretion (163.4 g/d) than either E (128.8 g/d) or A (137.1 g/d), and, because the combination improved gain above C (101.1 g/d), this demonstrates the additive effects of a combination implant on protein deposition. Anabolic implants did not alter (P > .10) the efficiency of ME utilization. In general, estrogenic implants decreased GIT, androgenic implants increased liver, and all implants increased hide mass. Steers implanted with an AE combination had additive effects on protein deposition compared with either implant alone. The NEg requirements for body gain are estimated to be reduced 19% by estrogenic or combination implants. PMID:9331863

  11. Approximate spatial reasoning

    NASA Technical Reports Server (NTRS)

    Dutta, Soumitra

    1988-01-01

    A model for approximate spatial reasoning using fuzzy logic to represent the uncertainty in the environment is presented. Algorithms are developed which can be used to reason about spatial information expressed in the form of approximate linguistic descriptions similar to the kind of spatial information processed by humans. Particular attention is given to static spatial reasoning.

  12. Exoplanetary System Dynamics: Planetary Multiplicity and Mass Effects

    NASA Astrophysics Data System (ADS)

    Isoe, Mari; Kokubo, Eiichiro; Turner, Edwin

    2015-12-01

    Recently numerous systems consisting of multiple exoplanets have been discovered. Using a dataset of 375 systems (500 planets) discovered by the radial velocity method and 365 systems (899 planets) containing planet candidates found by the Kepler Mission, we investigate the dependence of the dynamical structure of planetary systems on their multiplicity and the masses of the member planets. We classify the planetary system by three parameters: planetary multiplicity, planetary mass, and the evolutionary stage of the central star. We normalize planetary masses by the mass of the central star and divide the planets into small and large categories by a cut at $10^{-4}$. The central star is classified into main-sequence or giant according to its evolutionary stage. We focus on the angular momentum deficit (AMD) of the systems and the orbital separation between adjacent planets normalized by their Hill radii. We find that in all categories the system AMD decreases with increasing multiplicity. This suggests that in order for multiple systems to be stable, each planet's orbit must be relatively circular. In addition, we find that the distribution of orbital eccentricities of the massive planets and low-mass planets differs. In particular, only high-mass planets have eccentricities larger than 0.4. In the low-mass systems around main sequence stars, we find that the orbital separation decreases with increasing multiplicity. In addition, the orbital separation around main-sequence stars is wider than that around giants. Furthermore, the minimum orbital separation is about 6.4 for non-resonant pairs. This paper presents the statistical properties of the dynamical structure of multiple planetary systems and discusses their formation.

  13. Effective mass from microwave photoresistance measurements in GaAs/AlGaAs quantum wells

    NASA Astrophysics Data System (ADS)

    Hatke, A. T.; Zudov, M. A.; Watson, J. D.; Manfra, M. J.; Pfeiffer, L. N.; West, K. W.

    2013-08-01

    We have performed microwave photoresistance measurements in high mobility GaAs/AlGaAs quantum wells and investigated the value of the effective mass. The effective mass, obtained from the period of microwave-induced resistance oscillations (MIRO), was found to be about 12 % lower than the band mass in GaAs, m*b. In contrast, the measured magneto-plasmon dispersion (MPR) revealed an effective mass which is close to m*b, in accord with previous studies. These findings suggest that, in contrast to MPR, the MIRO dispersion contains corrections due to electron-electron interaction effects.

  14. Mass Polarization Effect in He-like Systems

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.; Drachman, Richard J.; Fisher, Richard R. (Technical Monitor)

    2002-01-01

    Eigenvalues for the ground state S and excited S and P states have been calculated for He-like systems, He, Li(+), Be(+2), and Ne(+8), using Hylleraas-type wave functions. These calculations have been carried out for a number of mass ratios R=mu/M=m(sub e)/(m(sub e)+M), where m(sub e) is the mass of the electron and M is the arbitrary mass of the nucleus. The eigenvalues are fitted to a 5th degree polynomial in R giving the mass polarization term (Delta (sub 1) x Delta (sub 2) and higher order corrections. The mass polarization term obtained from the fitting procedure agrees very well with the first-order result obtained directly. For example, in He we find E=E(sub 0)+Sigma(sup 5)(sub n=1)R(sup n)C(sub n), where E(sub 0)=-5.807448754 Ry and C(sub 1)=0.318138927 which agrees very well with the directly obtained first-order value 0.318138966083 and the result 0.318372 obtained by Yamanaka, using wave functions of the configuration-interaction form. We have carried out a similar calculation for the bound state of H(-).

  15. Approximate Bayesian multibody tracking.

    PubMed

    Lanz, Oswald

    2006-09-01

    Visual tracking of multiple targets is a challenging problem, especially when efficiency is an issue. Occlusions, if not properly handled, are a major source of failure. Solutions supporting principled occlusion reasoning have been proposed but are yet unpractical for online applications. This paper presents a new solution which effectively manages the trade-off between reliable modeling and computational efficiency. The Hybrid Joint-Separable (HJS) filter is derived from a joint Bayesian formulation of the problem, and shown to be efficient while optimal in terms of compact belief representation. Computational efficiency is achieved by employing a Markov random field approximation to joint dynamics and an incremental algorithm for posterior update with an appearance likelihood that implements a physically-based model of the occlusion process. A particle filter implementation is proposed which achieves accurate tracking during partial occlusions, while in cases of complete occlusion, tracking hypotheses are bound to estimated occlusion volumes. Experiments show that the proposed algorithm is efficient, robust, and able to resolve long-term occlusions between targets with identical appearance. PMID:16929730

  16. Testing molecular effects for tritium-based neutrino mass measurements

    NASA Astrophysics Data System (ADS)

    Parno, Diana; Bodine, Laura; Robertson, R. G. Hamish

    2015-10-01

    The upcoming KATRIN experiment will use the kinematics of tritium beta decay to probe the neutrino mass. The tritium source is molecular, however, and one of KATRIN's largest expected systematic uncertainties arises from the population of molecular final states following beta decay. To study this uncertainty, the Tritium Recoil-Ion Mass Spectrometer will measure the dissociation probability of the daughter molecule following beta decay, addressing a discrepancy between modern, high-precision theoretical calculations and two mass spectrometry measurements from the 1950s. We will describe the novel measurement technique and the commissioning of the experiment. This research is supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics under Award Number DE-FG02-97ER41020.

  17. Co-Seismic Mass Dislocation and its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, B. F.; Gross, R. S.

    2002-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the shaking that is the earthquake, leaves behind permanent (step-function-like) dislocations in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field (in terms of spherical harmonic Stokes coefficients). The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results based on Chao & Gross (1987). The calculation uses the normal mode summation scheme, applied to nearly twenty thousand major earthquakes that occurred during 1976-2002, according to source mechanism solutions given by the Harvard Central Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies. For example, earthquakes conspire to decrease J2 and J22 while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to nudge the Earth rotation pole towards approximately 140 degrees E, roughly opposite to the observed polar drift direction. The geophysical significance and implications will be further studied.

  18. New Stringy Instanton Effects And Neutrino Majorana Masses

    SciTech Connect

    Cvetic, M.; Richter, R.; Weigand, T.

    2007-10-03

    D-brane instantons can generate open string couplings in the superpotential which violate global abelian symmetries and are therefore perturbatively forbidden. After discussing the main ingredients, focussing for concretenes on Type IIA orientifold compactifications, we exemplify the computation of instanton-induced Majorana mass terms for right-handed neutrinos in a local SU(5) GUT-like model. In particular, we show that the instanton allows for naturally engineering the intermediate scale of the Majorana masses, thereby realizing the seesaw mechanism for neutrinos.

  19. Neutron-proton effective mass splitting in terms of symmetry energy and its density slope

    SciTech Connect

    Chakraborty, S.; Sahoo, B.; Sahoo, S.

    2015-01-15

    Using a simple density-dependent finite-range effective interaction having Yukawa form, the density dependence of isoscalar and isovector effective masses is studied. The isovector effective mass is found to be different for different pairs of like and unlike nucleons. Using HVH theorem, the neutron-proton effective mass splitting is represented in terms of symmetry energy and its density slope. It is again observed that the neutron-proton effective mass splitting has got a positive value when isoscalar effective mass is greater than the isovector effective mass and has a negative value for the opposite case. Furthermore, the neutron-proton effective mass splitting is found to have a linear dependence on asymmetry β. The second-order symmetry potential has a vital role in the determination of density slope of symmetry energy but it does not have any contribution on neutron-proton effective mass splitting. The finite-range effective interaction is compared with the SLy2, SKM, f{sub −}, f{sub 0}, and f{sub +} forms of interactions.

  20. Real-time optical monitoring of thin film growth by in situ pyrometry through multiple layers and effective media approximation modeling

    SciTech Connect

    Benedic, F.; Bruno, P.; Pigeat, Ph.

    2007-03-26

    A model combining multiple layer description and effective media approximation is developed for pyrometry in the case of thin film synthesis, in order to estimate the film property evolution along its thickness during the growth process in real time. The model is used to investigate optical properties of polycrystalline diamond film prepared by H{sub 2}/CH{sub 4}/N{sub 2} microwave plasma. It is shown that in the presence of nitrogen, the growth is strongly nonhomogeneous. The deposit, initially composed of large amounts of void and nondiamond phases, evolves rapidly towards highest quality dense film where the diamond phase is predominant.

  1. Review of rigorous coupled-wave analysis and of homogeneous effective medium approximations for high spatial-frequency surface-relief gratings

    NASA Technical Reports Server (NTRS)

    Glytsis, Elias N.; Brundrett, David L.; Gaylord, Thomas K.

    1993-01-01

    A review of the rigorous coupled-wave analysis as applied to the diffraction of electro-magnetic waves by gratings is presented. The analysis is valid for any polarization, angle of incidence, and conical diffraction. Cascaded and/or multiplexed gratings as well as material anisotropy can be incorporated under the same formalism. Small period rectangular groove gratings can also be modeled using approximately equivalent uniaxial homogeneous layers (effective media). The ordinary and extraordinary refractive indices of these layers depend on the gratings filling factor, the refractive indices of the substrate and superstrate, and the ratio of the freespace wavelength to grating period. Comparisons of the homogeneous effective medium approximations with the rigorous coupled-wave analysis are presented. Antireflection designs (single-layer or multilayer) using the effective medium models are presented and compared. These ultra-short period antireflection gratings can also be used to produce soft x-rays. Comparisons of the rigorous coupled-wave analysis with experimental results on soft x-ray generation by gratings are also included.

  2. Mass drivers. 3: Engineering

    NASA Technical Reports Server (NTRS)

    Arnold, W.; Bowen, S.; Cohen, S.; Fine, K.; Kaplan, D.; Kolm, M.; Kolm, H.; Newman, J.; Oneill, G. K.; Snow, W.

    1979-01-01

    The last of a series of three papers by the Mass-Driver Group of the 1977 Ames Summer Study is presented. It develops the engineering principles required to implement the basic mass-driver. Optimum component mass trade-offs are derived from a set of four input parameters, and the program used to design a lunar launcher. The mass optimization procedures is then incorporated into a more comprehensive mission optimization program called OPT-4, which evaluates an optimized mass-driver reaction engine and its performance in a range of specified missions. Finally, this paper discusses, to the extent that time permitted, certain peripheral problems: heating effects in buckets due to magnetic field ripple; an approximate derivation of guide force profiles; the mechanics of inserting and releasing payloads; the reaction mass orbits; and a proposed research and development plan for implementing mass drivers.

  3. Finite volume effects in the chiral extrapolation of baryon masses

    NASA Astrophysics Data System (ADS)

    Lutz, M. F. M.; Bavontaweepanya, R.; Kobdaj, C.; Schwarz, K.

    2014-09-01

    We perform an analysis of the QCD lattice data on the baryon octet and decuplet masses based on the relativistic chiral Lagrangian. The baryon self-energies are computed in a finite volume at next-to-next-to-next-to-leading order (N3LO), where the dependence on the physical meson and baryon masses is kept. The number of free parameters is reduced significantly down to 12 by relying on large-Nc sum rules. Altogether we describe accurately more than 220 data points from six different lattice groups, BMW, PACS-CS, HSC, LHPC, QCDSF-UKQCD and NPLQCD. Values for all counterterms relevant at N3LO are predicted. In particular we extract a pion-nucleon sigma term of 39-1+2 MeV and a strangeness sigma term of the nucleon of σsN=84-4+28 MeV. The flavor SU(3) chiral limit of the baryon octet and decuplet masses is determined with (802±4) and (1103±6) MeV. Detailed predictions for the baryon masses as currently evaluated by the ETM lattice QCD group are made.

  4. Effects of mass transfer between Martian satellites on surface geology

    NASA Astrophysics Data System (ADS)

    Nayak, Michael; Nimmo, Francis; Udrea, Bogdan

    2016-03-01

    Impacts on planetary bodies can lead to both prompt secondary craters and projectiles that reimpact the target body or nearby companions after an extended period, producing so-called "sesquinary" craters. Here we examine sesquinary cratering on the moons of Mars. We model the impact that formed Voltaire, the largest crater on the surface of Deimos, and explore the orbital evolution of resulting high-velocity ejecta across 500 years using four-body physics and particle tracking. The bulk of mass transfer to Phobos occurs in the first 102 years after impact, while reaccretion of ejecta to Deimos is predicted to continue out to a 104 year timescale (cf. Soter, S. [1971]. Studies of the Terrestrial Planets. Cornell University). Relative orbital geometry between Phobos and Deimos plays a significant role; depending on the relative true longitude, mass transfer between the moons can change by a factor of five. Of the ejecta with a velocity range capable of reaching Phobos, 25-42% by mass reaccretes to Deimos and 12-21% impacts Phobos. Ejecta mass transferred to Mars is <10%. We find that the characteristic impact velocity of sesquinaries on Deimos is an order of magnitude smaller than those of background (heliocentric) hypervelocity impactors and will likely result in different crater morphologies. The time-averaged flux of Deimos material to Phobos can be as high as 11% of the background (heliocentric) direct-to-Phobos impactor flux. This relatively minor contribution suggests that spectrally red terrain on Phobos (Murchie, S., Erard, S. [1996]. Icarus 123, 63-86) is not caused by Deimos material. However the high-velocity ejecta mass reaccreted to Deimos from a Voltaire-sized impact is comparable to the expected background mass accumulated on Deimos between Voltaire-size events. Considering that the high-velocity ejecta contains only 0.5% of the total mass sent into orbit, sesquinary ejecta from a Voltaire-sized impact could feasibly resurface large parts of the Moon

  5. Evidence for effective mass reduction in GaAs/AlGaAs quantum wells

    NASA Astrophysics Data System (ADS)

    Hatke, A. T.; Zudov, M. A.; Watson, J. D.; Manfra, M. J.; Pfeiffer, L. N.; West, K. W.

    2013-04-01

    We have performed microwave photoresistance measurements in high mobility GaAs/AlGaAs quantum wells and investigated the value of the effective mass. Surprisingly, the effective mass, obtained from the period of microwave-induced resistance oscillations, is found to be about 12% lower than the band mass in GaAs, mb. This finding provides strong evidence for electron-electron interactions which can be probed by microwave photoresistance in very high Landau levels. In contrast, the measured magnetoplasmon dispersion revealed an effective mass which is close to mb, in accord with previous studies.

  6. The Joint Effects of Body Mass Index and MAOA Gene Polymorphism on Depressive Symptoms.

    PubMed

    Liu, Yangyang

    2015-07-01

    The objective of the present study was to examine the joint effects of the body mass index and the MAOA gene polymorphism on depressive symptoms. In two independent Chinese samples, we measured adolescents' depressive symptoms and body mass index and collected their DNA. The results indicated that the main effects of the MAOA gene polymorphism on depressive symptoms were significant. However, the main effects of body mass index and the interaction of the MAOA gene polymorphism and body mass index on depressive symptoms were not significant. By using Chinese adolescents, this study confirmed that the MAOA gene polymorphism directly influenced adolescents' depressive symptoms. PMID:26207137

  7. The Joint Effects of Body Mass Index and MAOA Gene Polymorphism on Depressive Symptoms

    PubMed Central

    2015-01-01

    The objective of the present study was to examine the joint effects of the body mass index and the MAOA gene polymorphism on depressive symptoms. In two independent Chinese samples, we measured adolescents' depressive symptoms and body mass index and collected their DNA. The results indicated that the main effects of the MAOA gene polymorphism on depressive symptoms were significant. However, the main effects of body mass index and the interaction of the MAOA gene polymorphism and body mass index on depressive symptoms were not significant. By using Chinese adolescents, this study confirmed that the MAOA gene polymorphism directly influenced adolescents' depressive symptoms. PMID:26207137

  8. Calculator Function Approximation.

    ERIC Educational Resources Information Center

    Schelin, Charles W.

    1983-01-01

    The general algorithm used in most hand calculators to approximate elementary functions is discussed. Comments on tabular function values and on computer function evaluation are given first; then the CORDIC (Coordinate Rotation Digital Computer) scheme is described. (MNS)

  9. Testing the frozen flow approximation

    NASA Technical Reports Server (NTRS)

    Lucchin, Francesco; Matarrese, Sabino; Melott, Adrian L.; Moscardini, Lauro

    1993-01-01

    We investigate the accuracy of the frozen-flow approximation (FFA), recently proposed by Matarrese, et al. (1992), for following the nonlinear evolution of cosmological density fluctuations under gravitational instability. We compare a number of statistics between results of the FFA and n-body simulations, including those used by Melott, Pellman & Shandarin (1993) to test the Zel'dovich approximation. The FFA performs reasonably well in a statistical sense, e.g. in reproducing the counts-in-cell distribution, at small scales, but it does poorly in the crosscorrelation with n-body which means it is generally not moving mass to the right place, especially in models with high small-scale power.

  10. Ladder operators and associated algebra for position-dependent effective mass systems

    NASA Astrophysics Data System (ADS)

    Amir, Naila; Iqbal, Shahid

    2015-07-01

    An algebraic treatment of shape-invariant quantum-mechanical position-dependent effective mass systems is discussed. Using shape invariance, a general recipe for construction of ladder operators and associated algebraic structure of the pertaining system, is obtained. These operators are used to find exact solutions of general one-dimensional systems with spatially varying mass. We apply our formalism to specific translationally shape-invariant potentials having position-dependent effective mass.

  11. THE EFFECT OF MAGNETIC FIELDS AND AMBIPOLAR DIFFUSION ON CORE MASS FUNCTIONS

    SciTech Connect

    Bailey, Nicole D.; Basu, Shantanu E-mail: basu@uwo.ca

    2013-03-20

    Linear analysis of the formation of protostellar cores in planar magnetic interstellar clouds yields information about length scales involved in star formation. Combining these length scales with various distributions of other environmental variables (i.e., column density and mass-to-flux ratio) and applying Monte Carlo methods allow us to produce synthetic core mass functions (CMFs) for different environmental conditions. Our analysis shows that the shape of the CMF is directly dependent on the physical conditions of the cloud. Specifically, magnetic fields act to broaden the mass function and develop a high-mass tail while ambipolar diffusion will truncate this high-mass tail. In addition, we analyze the effect of small number statistics on the shape and high-mass slope of the synthetic CMFs. We find that observed CMFs are severely statistically limited, which has a profound effect on the derived slope for the high-mass tail.

  12. Approximate spatial reasoning

    NASA Technical Reports Server (NTRS)

    Dutta, Soumitra

    1988-01-01

    Much of human reasoning is approximate in nature. Formal models of reasoning traditionally try to be precise and reject the fuzziness of concepts in natural use and replace them with non-fuzzy scientific explicata by a process of precisiation. As an alternate to this approach, it has been suggested that rather than regard human reasoning processes as themselves approximating to some more refined and exact logical process that can be carried out with mathematical precision, the essence and power of human reasoning is in its capability to grasp and use inexact concepts directly. This view is supported by the widespread fuzziness of simple everyday terms (e.g., near tall) and the complexity of ordinary tasks (e.g., cleaning a room). Spatial reasoning is an area where humans consistently reason approximately with demonstrably good results. Consider the case of crossing a traffic intersection. We have only an approximate idea of the locations and speeds of various obstacles (e.g., persons and vehicles), but we nevertheless manage to cross such traffic intersections without any harm. The details of our mental processes which enable us to carry out such intricate tasks in such apparently simple manner are not well understood. However, it is that we try to incorporate such approximate reasoning techniques in our computer systems. Approximate spatial reasoning is very important for intelligent mobile agents (e.g., robots), specially for those operating in uncertain or unknown or dynamic domains.

  13. Galaxy Cluster Gas Mass Fractions From Sunyaev-Zel'dovich Effect Measurement: Constraints on Omega_M

    NASA Technical Reports Server (NTRS)

    Grego, Laura; Carlstrom, John E.; Reese, Erik D.; Holder, Gilbert P.; Holzapfel, William L.; Joy, Marshall K.; Mohr, Joseph J.; Patel, Sandeep; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Using sensitive centimeter-wave receivers mounted on the Owens Valley Radio Observatory and Berkeley-Illinois-Maryland-Association millimeter arrays, we have obtained interferometric measurements of the Sunyaev-Zei'dovich (SZ) effect toward massive galaxy clusters. We use the SZ data to determine the pressure distribution of the cluster gas and, in combination with published X-ray temperatures, to infer the gas mass and total gravitational mass of 18 clusters. The gas mass fraction, fg, is calculated for each cluster, and is extrapolated to the fiducial radius r_{500} using the results of numerical simulations. The mean f_g within r_{500} is 0.081 + 0.009 - 0.011/(h_{100} (statistical uncertainty at 68% confidence level, assuming OmegaM=0.3, OmegaL=0.7). We discuss possible sources of systematic errors in the mean f 9 measurement. We derive an upper limit for OmegaM from this sample under the assumption that the mass composition of clusters within r_{500} reflects the universal mass composition: Omega_M h mass f on cosmology through the angular diameter distance and the r_{500} correction factors. For a flat universe (Omegal, = 1 - OmegaM) and h=0.7, we find the measured gas mass fractions are consistent with OmegaM less than 0.40, at 68% confidence. Including estimates of the baryons contained in galaxies and the baryons which failed to become bound during the cluster formation process, we find OmegaM\\approximately 0.25.

  14. Colloquy: Information Processing: A More Inclusive Paradigm for the Study of Mass Media Effects.

    ERIC Educational Resources Information Center

    Newhagen, John E.

    2000-01-01

    Argues that the information-processing paradigm can both revitalize so-called strong-effects theories in mass media research and make them more inclusive. Discusses how the four previous studies in this issue show the use of simple solutions to problems that have plagued mass-media-effects research and call out for further inclusion of discussions…

  15. Androgens exert opposite effects on body mass of heavy and light meadow voles.

    PubMed

    Dark, J; Whaling, C S; Zucker, I

    1987-12-01

    The influence of gonadal hormones on body mass of adult male meadow voles varied systematically as a function of the animals' baseline body weight; heavier voles decreased and lighter voles increased their body mass after castration. Testosterone replacement reversed the effects of castration; changes in body mass during hormone treatment were negatively correlated with changes observed after castration. Body mass of intact males was not correlated with plasma testosterone titers. Individual differences in body mass of male voles appear to reflect variations among animals in substrate responsiveness to hormones rather than differences in circulating hormone levels. PMID:3323026

  16. Reaction dynamics of D+H2 --> DH+H: Effects of potential energy surface topography and usefulness of the constant centrifugal potential approximation

    NASA Astrophysics Data System (ADS)

    Takada, Shoji; Ohsaki, Akihiko; Nakamura, Hiroki

    1992-01-01

    Two findings are reported for the D+H2→DH+H reaction on the basis of the exact quantum mechanical calculation for J=0, where J is total angular momentum. First, with use of the Liu-Siegbahn-Truhlar-Horowitz (LSTH) surface and the Varandas surface, we demonstrate that a rather small difference in potential energy surface (PES) induces a surprisingly large effect on reaction dynamics. Two origins of the discrepancy are pointed out and analyzed: (1) Noncollinear conformation in the reaction zone contributes to the reaction significantly despite the fact that the minimum energy path and the saddle point are located in the collinear configuration. (2) A difference in the distant part of PES also causes a discrepancy in the reaction dynamics indirectly, although this effect is much smaller than (1). Secondly, we investigate the validity of the constant centrifugal potential approximation (CCPA) based on the accurate results for J=0. The use of CCPA to estimate total cross section and rate constant is again proved to have practical utility as in the cases of the sudden and adiabatic approximations.

  17. Temperature and density effects on the nucleon mass splitting

    SciTech Connect

    Christiansen, H.R.; Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A.

    1996-04-01

    The finite temperature and finite density dependence of the neutron-proton mass difference is analyzed in a purely hadronic framework where the {rho}-{omega} mixing is crucial for this isospin symmetry breakdown. The problem is handled within thermofield dynamics. The present results, consistent with partial chiral and charge symmetry restoration, improve the experimental data fit for the energy difference between mirror nuclei. {copyright} {ital 1996 The American Physical Society.}

  18. Some Exotic Models in Statistical Physics. I. The Coherent Potential Approximation is a Realizable Effective Medium Scheme. I. Anomalous First-Order Transitions

    NASA Astrophysics Data System (ADS)

    Milton, Graeme Walter

    In the two separate parts of this thesis, some special exactly solvable models are defined and analysed. In Part I it is proved rigorously that the coherent potential approximation is exact for the effective conductivity of a wide class of hierarchical models made of spherical grains of various conductivities. In Part II the existence of continuum fluid models that exhibit a discontinuity in the pressure versus density isotherms is established by explicit construction of a class of examples. Part II also incorporates a broad study of discontinuities in thermodynamic variables. The basic models of Part I are constructed as follows: the starting material 0 in the hierarchy is chosen arbitrarily, otherwise material j = 1, 2, ..., consists of equisized spheres, say j-spheres, of arbitrary conductivities embedded in material (j - 1). The distribution of the j-spheres must satisfy a mild homogeneity condition and their radius r(,j) must, asymptotically, increase faster than expotentially with j. The minimum spacing, 2s(,j), between the j-spheres is such that s(,j)/r(,j) diverges. On the basis of these and other ancillary conditions it is established that the coherent potential approximation becomes exact for the effective conductivity (or the dielectric constant or the magnetic permeability) of material j ( --->) (INFIN). The model composites and the proof of realizability may be generalised to allow non-spherical grains. By introducing ensembles of composites the homogeneity condition and the spacing condition can be relaxed somewhat. Another related approximation, the iterated dilute limit approximation is also proved to be realizable. In Part II, one-dimensional continuum models are defined in which classical particles interact through many -body potentials meeting conditions sufficient to ensure a proper thermodynamic limit. An exact analysis proves that for certain ranges of parameter values the pressure versus density isotherms are discontinuous. Extended models

  19. GIA models with composite rheology and 3D viscosity: effect on GRACE mass balance in Antarctica

    NASA Astrophysics Data System (ADS)

    van der Wal, Wouter; Whitehouse, Pippa; Schrama, Ernst

    2014-05-01

    Most Glacial Isostatic Adjustment (GIA) models that have been used to correct GRACE data for the influence of GIA assume a radial stratification of viscosity in the Earth's mantle (1D viscosity). Seismic data in Antarctica indicate that there are large viscosity variations in the horizontal direction (3D viscosity). The purpose of this research is to determine the effect of 3D viscosity on GIA model output, and hence mass balance estimates in Antarctica. We use a GIA model with 3D viscosity and composite rheology in combination with ice loading histories ICE-5G and W12a. From comparisons with uplift and sea-level data in Fennoscandia and North America three preferred viscosity models are selected. For two of the 3D viscosity models the maximum gravity rate due to ICE-5G forcing is located over the Ronne-Filchner ice shelf. This is in contrast with the results obtained using a 1D model, in which the maximum gravity rate due to ICE-5G forcing is always located over the Ross ice shelf. This demonstrates that not all 3D viscosity models can be approximated with a 1D viscosity model. Using CSR release 5 GRACE data from February 2003 to June 2013 mass balance estimates for the three preferred viscosity models are -131 to -171 Gt/year for the ICE-5G model, and -48 to -57 Gt/year for the W12a model. The range due to Earth model uncertainty is larger than the error bar for GRACE (10 Gt/year), but smaller than the range resulting from the difference in ice loading histories.

  20. Wavelet Sparse Approximate Inverse Preconditioners

    NASA Technical Reports Server (NTRS)

    Chan, Tony F.; Tang, W.-P.; Wan, W. L.

    1996-01-01

    There is an increasing interest in using sparse approximate inverses as preconditioners for Krylov subspace iterative methods. Recent studies of Grote and Huckle and Chow and Saad also show that sparse approximate inverse preconditioner can be effective for a variety of matrices, e.g. Harwell-Boeing collections. Nonetheless a drawback is that it requires rapid decay of the inverse entries so that sparse approximate inverse is possible. However, for the class of matrices that, come from elliptic PDE problems, this assumption may not necessarily hold. Our main idea is to look for a basis, other than the standard one, such that a sparse representation of the inverse is feasible. A crucial observation is that the kind of matrices we are interested in typically have a piecewise smooth inverse. We exploit this fact, by applying wavelet techniques to construct a better sparse approximate inverse in the wavelet basis. We shall justify theoretically and numerically that our approach is effective for matrices with smooth inverse. We emphasize that in this paper we have only presented the idea of wavelet approximate inverses and demonstrated its potential but have not yet developed a highly refined and efficient algorithm.

  1. Scale effects and morphological diversification in hindlimb segment mass proportions in neognath birds

    PubMed Central

    2014-01-01

    Introduction In spite of considerable work on the linear proportions of limbs in amniotes, it remains unknown whether differences in scale effects between proximal and distal limb segments has the potential to influence locomotor costs in amniote lineages and how changes in the mass proportions of limbs have factored into amniote diversification. To broaden our understanding of how the mass proportions of limbs vary within amniote lineages, I collected data on hindlimb segment masses – thigh, shank, pes, tarsometatarsal segment, and digits – from 38 species of neognath birds, one of the most speciose amniote clades. I scaled each of these traits against measures of body size (body mass) and hindlimb size (hindlimb length) to test for departures from isometry. Additionally, I applied two parameters of trait evolution (Pagel’s λ and δ) to understand patterns of diversification in hindlimb segment mass in neognaths. Results All segment masses are positively allometric with body mass. Segment masses are isometric with hindlimb length. When examining scale effects in the neognath subclade Land Birds, segment masses were again positively allometric with body mass; however, shank, pedal, and tarsometatarsal segment masses were also positively allometric with hindlimb length. Methods of branch length scaling to detect phylogenetic signal (i.e., Pagel’s λ) and increasing or decreasing rates of trait change over time (i.e., Pagel’s δ) suffer from wide confidence intervals, likely due to small sample size and deep divergence times. Conclusions The scaling of segment masses appears to be more strongly related to the scaling of limb bone mass as opposed to length, and the scaling of hindlimb mass distribution is more a function of scale effects in limb posture than proximo-distal differences in the scaling of limb segment mass. Though negative allometry of segment masses appears to be precluded by the need for mechanically sound limbs, the positive allometry of

  2. Effect of neutrino rest mass on ionization equilibrium freeze-out

    NASA Astrophysics Data System (ADS)

    Grohs, E.; Fuller, G. M.; Kishimoto, C. T.; Paris, M. W.

    2015-12-01

    We show how small neutrino rest masses can increase the expansion rate near the photon decoupling epoch in the early Universe, causing an earlier, higher temperature freeze-out for ionization equilibrium compared to the massless neutrino case. This yields a larger free-electron fraction, thereby affecting the photon diffusion length differently than the sound horizon at photon decoupling. This neutrino-mass and recombination effect depends strongly on the neutrino rest masses. Though below current sensitivity, this effect could be probed by next-generation cosmic microwave background experiments, giving another observational handle on neutrino rest mass.

  3. Effect of neutrino rest mass on ionization equilibrium freeze-out

    DOE PAGESBeta

    Grohs, Evan Bradley; Fuller, George M.; Kishimoto, Chad T.; Paris, Mark W.

    2015-12-23

    We show how small neutrino rest masses can increase the expansion rate near the photon decoupling epoch in the early Universe, causing an earlier, higher temperature freeze-out for ionization equilibrium compared to the massless neutrino case. This yields a larger free-electron fraction, thereby affecting the photon diffusion length differently than the sound horizon at photon decoupling. This neutrino-mass and recombination effect depends strongly on the neutrino rest masses. Ultimately, though below current sensitivity, this effect could be probed by next-generation cosmic microwave background experiments, giving another observational handle on neutrino rest mass.

  4. The measurement and evaluation of the effect of fuse materials and masses on railgun performance

    SciTech Connect

    Baker, M.C.; Tanner, M.R.

    1994-12-31

    The HERA railgun device at Texas Tech University has been used to investigate the effects of armature fuses on plasma armature railguns. The fuse mass (thickness) was varied for both copper and aluminum fuses over a range of 0.1 mm to 1.5 mm in a 1 cm round bore geometry. Armature velocity and velocity saturation effects were observed. While holding railgun current and total projectile mass constant the fuse mass and material were varied. This paper will present the current findings from the research, including representative data on velocity vs. fuse material and mass, and velocity saturation. The experimental setup and methods will also be described.

  5. Extreme mass-ratio inspirals in the effective-one-body approach: Quasicircular, equatorial orbits around a spinning black hole

    SciTech Connect

    Yunes, Nicolas; Buonanno, Alessandra; Pan Yi; Barausse, Enrico; Hughes, Scott A.; Throwe, William; Miller, M. Coleman

    2011-02-15

    We construct effective-one-body waveform models suitable for data analysis with the Laser Interferometer Space Antenna for extreme mass-ratio inspirals in quasicircular, equatorial orbits about a spinning supermassive black hole. The accuracy of our model is established through comparisons against frequency-domain, Teukolsky-based waveforms in the radiative approximation. The calibration of eight high-order post-Newtonian parameters in the energy flux suffices to obtain a phase and fractional amplitude agreement of better than 1 rad and 1%, respectively, over a period between 2 and 6 months depending on the system considered. This agreement translates into matches higher than 97% over a period between 4 and 9 months, depending on the system. Better agreements can be obtained if a larger number of calibration parameters are included. Higher-order mass-ratio terms in the effective-one-body Hamiltonian and radiation reaction introduce phase corrections of at most 30 rad in a 1 yr evolution. These corrections are usually 1 order of magnitude larger than those introduced by the spin of the small object in a 1 yr evolution. These results suggest that the effective-one-body approach for extreme mass-ratio inspirals is a good compromise between accuracy and computational price for Laser Interferometer Space Antenna data-analysis purposes.

  6. Extreme mass-ratio inspirals in the effective-one-body approach: Quasicircular, equatorial orbits around a spinning black hole

    NASA Astrophysics Data System (ADS)

    Yunes, Nicolás; Buonanno, Alessandra; Hughes, Scott A.; Pan, Yi; Barausse, Enrico; Miller, M. Coleman; Throwe, William

    2011-02-01

    We construct effective-one-body waveform models suitable for data analysis with the Laser Interferometer Space Antenna for extreme mass-ratio inspirals in quasicircular, equatorial orbits about a spinning supermassive black hole. The accuracy of our model is established through comparisons against frequency-domain, Teukolsky-based waveforms in the radiative approximation. The calibration of eight high-order post-Newtonian parameters in the energy flux suffices to obtain a phase and fractional amplitude agreement of better than 1 rad and 1%, respectively, over a period between 2 and 6 months depending on the system considered. This agreement translates into matches higher than 97% over a period between 4 and 9 months, depending on the system. Better agreements can be obtained if a larger number of calibration parameters are included. Higher-order mass-ratio terms in the effective-one-body Hamiltonian and radiation reaction introduce phase corrections of at most 30 rad in a 1 yr evolution. These corrections are usually 1 order of magnitude larger than those introduced by the spin of the small object in a 1 yr evolution. These results suggest that the effective-one-body approach for extreme mass-ratio inspirals is a good compromise between accuracy and computational price for Laser Interferometer Space Antenna data-analysis purposes.

  7. Fast approximate motif statistics.

    PubMed

    Nicodème, P

    2001-01-01

    We present in this article a fast approximate method for computing the statistics of a number of non-self-overlapping matches of motifs in a random text in the nonuniform Bernoulli model. This method is well suited for protein motifs where the probability of self-overlap of motifs is small. For 96% of the PROSITE motifs, the expectations of occurrences of the motifs in a 7-million-amino-acids random database are computed by the approximate method with less than 1% error when compared with the exact method. Processing of the whole PROSITE takes about 30 seconds with the approximate method. We apply this new method to a comparison of the C. elegans and S. cerevisiae proteomes. PMID:11535175

  8. The Guiding Center Approximation

    NASA Astrophysics Data System (ADS)

    Pedersen, Thomas Sunn

    The guiding center approximation for charged particles in strong magnetic fields is introduced here. This approximation is very useful in situations where the charged particles are very well magnetized, such that the gyration (Larmor) radius is small compared to relevant length scales of the confinement device, and the gyration is fast relative to relevant timescales in an experiment. The basics of motion in a straight, uniform, static magnetic field are reviewed, and are used as a starting point for analyzing more complicated situations where more forces are present, as well as inhomogeneities in the magnetic field -- magnetic curvature as well as gradients in the magnetic field strength. The first and second adiabatic invariant are introduced, and slowly time-varying fields are also covered. As an example of the use of the guiding center approximation, the confinement concept of the cylindrical magnetic mirror is analyzed.

  9. Electron flood gun damage effects in 3D secondary ion mass spectrometry imaging of organics.

    PubMed

    Havelund, Rasmus; Seah, Martin P; Shard, Alexander G; Gilmore, Ian S

    2014-09-01

    Electron flood guns used for charge compensation in secondary ion mass spectrometry (SIMS) cause chemical degradation. In this study, the effect of electron flood gun damage on argon cluster depth profiling is evaluated for poly(vinylcarbazole), 1,4-bis((1-naphthylphenyl)amino)biphenyl and Irganox 3114. Thin films of these three materials are irradiated with a range of doses from a focused beam of 20 eV electrons used for charge neutralization. SIMS chemical images of the irradiated surfaces show an ellipsoidal damaged area, approximately 3 mm in length, created by the electron beam. In depth profiles obtained with 5 keV Ar(2000)(+) sputtering from the vicinity of the damaged area, the characteristic ion signal intensity rises from a low level to a steady state. For the damaged thin films, the ion dose required to sputter through the thin film to the substrate is higher than for undamaged areas. It is shown that a damaged layer is formed and this has a sputtering yield that is reduced by up to an order of magnitude and that the thickness of the damaged layer, which increases with the electron dose, can be as much as 20 nm for Irganox 3114. The study emphasizes the importance of minimizing the neutralizing electron dose prior to the analysis. PMID:24912434

  10. Evaluating chlorine isotope effects from isotope ratios and mass spectra of polychlorinated molecules.

    PubMed

    Elsner, Martin; Hunkeler, Daniel

    2008-06-15

    Compound-specific chlorine isotope analysis receives much interest to assess the fate of chlorinated hydrocarbons in contaminated environments. This paper provides a theoretical basis to calculate isotope ratios and quantify isotope fractionation from ion-current ratios of molecular- and fragment-ion multiplets. Because both (35)Cl and (37)Cl are of high abundance, polychlorinated hydrocarbons consist of molecules containing different numbers of (37)Cl denoted as isotopologues. We show that, during reactions, the changes in isotopologue ratios are proportional to changes in the isotope ratio assuming a nonselective isotope distribution in the initial compound. This proportionality extents even to fragments formed in the ion source of a mass spectrometer such as C 2Cl 2 (double dechlorinated fragment of perchloroethylene, PCE). Fractionation factors and kinetic isotope effects (KIE) may, therefore, be evaluated from isotope, isotopologue or even fragment ratios according to conventional simple equations. The proportionality is exact with symmetric molecules such as dichloroethylene (DCE) and PCE, whereas it is approximately true with molecules containing nonreactive positions such as trichloroethylene (TCE). If in the latter case isotope ratios are derived from dechlorinated fragments, e.g., C 2HCl 2, it is important that fragmentation in the ion source affect all molecular positions alike, as otherwise isotopic changes in reactive positions may be underrepresented. PMID:18484745

  11. Left ventricular mass: allometric scaling, normative values, effect of obesity, and prognostic performance.

    PubMed

    Chirinos, Julio A; Segers, Patrick; De Buyzere, Marc L; Kronmal, Richard A; Raja, Muhammad W; De Bacquer, Dirk; Claessens, Tom; Gillebert, Thierry C; St John-Sutton, Martin; Rietzschel, Ernst R

    2010-07-01

    The need for left ventricular mass (LVM) normalization to body size is well recognized. Currently used allometric exponents to normalize LVM may not account for the confounding effect of sex. Because sex is a strong determinant of body size and LVM, we hypothesized that these are subject to potential bias. We analyzed data from 7528 subjects enrolled in the Asklepios Study (n=2524) and the Multiethnic Study of Atherosclerosis (limited access data set; n=5,004) to assess metric relationships between LVM and body size, generate normative data for indexed LVM, and compare the ability of normalization methods to predict cardiovascular events. The allometric exponent that adequately described the LVM-body height relationship was 1.7 in both studies and significantly different from both the unity and 2.7, whereas the LVM-body surface area relationship was approximately linear. LVM/height(2.7) consistently demonstrated important residual relationships with body height and systematically misclassified subjects regarding the presence of LVH. LVH defined by LVM/height(1.7) was more sensitive than LVM/body surface area to identify obesity-related LVH and was most consistently associated with cardiovascular events and all-cause death. In contrast to current assumptions, LVM/height(2.7) is not an adequate method to normalize LVM for body size. We provide more appropriate normalization methods, normative data by 2D echocardiography and gradient-echo cardiac MRI, and cutoffs for defining LVH, along with prognostic validation data. PMID:20458004

  12. Multi-valley effective mass treatment of donor-dot tunneling in silicon

    NASA Astrophysics Data System (ADS)

    Frees, Adam; Baczewski, Andrew D.; Gamble, John King; Jacobson, N. Tobias; Muller, Richard P.; Nielsen, Erik

    2015-03-01

    Many cutting-edge experiments in silicon-based devices for quantum information processing involve the tunneling of an individual electron from a donor atom within the material to the interface of the heterostructure. Understanding how this tunneling process varies among different realistic devices is therefore of great interest. Using a multi-valley effective mass approximation method, we find the tunnel coupling, adiabatic min-gap, and ionizing electric field strength between a phosphorous donor in silicon and a nearby quantum dot at a Si/SiO2 interface. Additionally, we calculate these quantities for a phosphorous donor in strained silicon and a Si/SiGe interface. We consider how these properties change as a function of relative position between the donor and the dot. The authors gratefully acknowledge support from the Sandia National Laboratories Truman Fellowship Program, which is funded by the Laboratory Directed Research and Development (LDRD) Program. Sandia is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.

  13. Monotone Boolean approximation

    SciTech Connect

    Hulme, B.L.

    1982-12-01

    This report presents a theory of approximation of arbitrary Boolean functions by simpler, monotone functions. Monotone increasing functions can be expressed without the use of complements. Nonconstant monotone increasing functions are important in their own right since they model a special class of systems known as coherent systems. It is shown here that when Boolean expressions for noncoherent systems become too large to treat exactly, then monotone approximations are easily defined. The algorithms proposed here not only provide simpler formulas but also produce best possible upper and lower monotone bounds for any Boolean function. This theory has practical application for the analysis of noncoherent fault trees and event tree sequences.

  14. Direct effect of increased hemodynamic load on cardiac mass.

    PubMed

    Korecky, B; Masika, M

    1991-04-01

    The hearts of rats were transplanted into the abdomens of recipients of the same inbred strain by attaching the stumps of aorta and pulmonary artery end to side to the abdominal aorta and inferior vena cava, respectively, of the recipient. The transplant functions as a denervated "nonworking" Langendorff heart; the recipient in situ heart serves as a normal control. One week after surgery, an onset of atrophy is observed in the transplanted heart, which stabilizes after 2 weeks; the in situ heart grows normally. Using this model, we increased the load of the left ventricle (LV) in the transplant by inserting a permanent polyethylene cannula into its aortic orifice during surgery to induce valvular incompetence and/or stenosis (TPE group). This resulted in significantly increased LV systolic pressure (115 +/- 5 versus 95 +/- 3 mm Hg) and a significantly increased rate-pressure product (34.7 +/- 1.7 versus 24.4 +/- 1.4 mm Hg.min-1 x 10(3) as compared with rats with control transplants (TC group). The LV mass in the TPE group decreased to only 85 +/- 4.8% of the mass of the corresponding in situ recipient heart as compared with 59 +/- 2.6% in the TC group (p less than 0.001). In three cases in the TPE group with highest overload, we observed about 20% larger LV mass in transplanted hearts as compared with the corresponding recipient in situ hearts. These results indicate that the increased load significantly attenuated the atrophy observed in LV of the isotransplants. This attenuation could be correlated with the increment of load as indicated by higher peak LV pressures and higher rate-pressure products. PMID:2009614

  15. Energy balance of stellar coronae. III - Effect of stellar mass and radius

    NASA Technical Reports Server (NTRS)

    Hammer, R.

    1984-01-01

    A homologous transformation is derived which permits the application of the numerical coronal models of Hammer from a star with solar mass and radius to other stars. This scaling requires a few approximations concerning the lower boundary conditions and the temperature dependence of the conductivity and emissivity. These approximations are discussed and found to be surprisingly mild. Therefore, the scaling of the coronal models to other stars is rather accurate; it is found to be particularly accurate for main-sequence stars. The transformation is used to derive an equation that gives the maximum temperature of open coronal regions as a function of stellar mass and radius, the coronal heating flux, and the characteristic damping length over which the corona is heated.

  16. Effect of gas mass flux on cryogenic liquid jet breakup

    NASA Astrophysics Data System (ADS)

    Ingebo, R. D.

    A scattered-light scanning instrument developed at NASA Lewis Research Center was used to measure the characteristic drop size of clouds of liquid nitrogen droplets. The instrument was calibrated with suspensions of monosized polystyrene spheres. In this investigation of the mechanism of liquid nitrogen jet disintegration in a high-velocity gas flow, the Sauter mean diameter, D32, was found to vary inversely with the nitrogen gas mass flux raised to the power 1.33. Values of D32 varied from 5 to 25 microns and the mass flux exponent of 1.33 agrees well with theory for liquid jet breakup in high-velocity gas flows. The loss of very small droplets due to the high vaporization rate of liquid nitrogen was avoided by sampling the spray very close to the atomizer, i.e., 1.3 cm downstream of the nozzle orifice. The presence of high velocity and thermal gradients in the gas phase also made sampling of the particles difficult. As a result, it was necessary to correct the measurements for background noise produced by both highly turbulent gas flows and thermally induced density gradients in the gas phase.

  17. Charged Kaon Mass Measurement using the Cherenkov Effect

    SciTech Connect

    Graf, N.; Lebedev, A.; Abrams, R.J.; Akgun, U.; Aydin, G.; Baker, W.; Barnes, P.D., Jr.; Bergfeld, T.; Beverly, L.; Bujak, A.; Carey, D.; /Fermilab /Virginia U. /Iowa U.

    2009-09-01

    The two most recent and precise measurements of the charged kaon mass use X-rays from kaonic atoms and report uncertainties of 14 ppm and 22 ppm yet differ from each other by 122 ppm. We describe the possibility of an independent mass measurement using the measurement of Cherenkov light from a narrow-band beam of kaons, pions, and protons. This technique was demonstrated using data taken opportunistically by the Main Injector Particle Production experiment at Fermi National Accelerator Laboratory which recorded beams of protons, kaons, and pions ranging in momentum from +37 GeV/c to +63 GeV/c. The measured value is 491.3 {+-} 1.7 MeV/c{sup 2}, which is within 1.4{sigma} of the world average. An improvement of two orders of magnitude in precision would make this technique useful for resolving the ambiguity in the X-ray data and may be achievable in a dedicated experiment.

  18. Approximating Integrals Using Probability

    ERIC Educational Resources Information Center

    Maruszewski, Richard F., Jr.; Caudle, Kyle A.

    2005-01-01

    As part of a discussion on Monte Carlo methods, which outlines how to use probability expectations to approximate the value of a definite integral. The purpose of this paper is to elaborate on this technique and then to show several examples using visual basic as a programming tool. It is an interesting method because it combines two branches of…

  19. Multicriteria approximation through decomposition

    SciTech Connect

    Burch, C. |; Krumke, S.; Marathe, M.; Phillips, C.; Sundberg, E. |

    1997-12-01

    The authors propose a general technique called solution decomposition to devise approximation algorithms with provable performance guarantees. The technique is applicable to a large class of combinatorial optimization problems that can be formulated as integer linear programs. Two key ingredients of the technique involve finding a decomposition of a fractional solution into a convex combination of feasible integral solutions and devising generic approximation algorithms based on calls to such decompositions as oracles. The technique is closely related to randomized rounding. The method yields as corollaries unified solutions to a number of well studied problems and it provides the first approximation algorithms with provable guarantees for a number of new problems. The particular results obtained in this paper include the following: (1) The authors demonstrate how the technique can be used to provide more understanding of previous results and new algorithms for classical problems such as Multicriteria Spanning Trees, and Suitcase Packing. (2) They show how the ideas can be extended to apply to multicriteria optimization problems, in which they wish to minimize a certain objective function subject to one or more budget constraints. As corollaries they obtain first non-trivial multicriteria approximation algorithms for problems including the k-Hurdle and the Network Inhibition problems.

  20. Multicriteria approximation through decomposition

    SciTech Connect

    Burch, C.; Krumke, S.; Marathe, M.; Phillips, C.; Sundberg, E.

    1998-06-01

    The authors propose a general technique called solution decomposition to devise approximation algorithms with provable performance guarantees. The technique is applicable to a large class of combinatorial optimization problems that can be formulated as integer linear programs. Two key ingredients of their technique involve finding a decomposition of a fractional solution into a convex combination of feasible integral solutions and devising generic approximation algorithms based on calls to such decompositions as oracles. The technique is closely related to randomized rounding. Their method yields as corollaries unified solutions to a number of well studied problems and it provides the first approximation algorithms with provable guarantees for a number of new problems. The particular results obtained in this paper include the following: (1) the authors demonstrate how the technique can be used to provide more understanding of previous results and new algorithms for classical problems such as Multicriteria Spanning Trees, and Suitcase Packing; (2) they also show how the ideas can be extended to apply to multicriteria optimization problems, in which they wish to minimize a certain objective function subject to one or more budget constraints. As corollaries they obtain first non-trivial multicriteria approximation algorithms for problems including the k-Hurdle and the Network Inhibition problems.

  1. Mass spectrometric analysis of isotope effects in bioconversion of benzene to cyclohexanone

    NASA Astrophysics Data System (ADS)

    Nam, In-Hyun; Murugesan, Kumarasamy; Kim, Young-Mo; Yang, In-Hee; Chang, Yoon-Seok

    2006-06-01

    Pseudomonas veronii strain PH-03 has been shown to convert benzene to cyclohexanone through phenol. Mass spectrometry results revealed that unusual isotopic effects have been occurred in the transformation product, cyclohexanone. The isotopic composition was strongly depends on the compound specific hydrogen or oxygen source. The exchange of labile deuterium atoms has been investigated through electrospray ionization liquid chromatography mass spectrometry. The mass spectrometric analysis of biotransformation products enabled the proposal of a corresponding bioconversion pathway.

  2. Producing approximate answers to database queries

    NASA Technical Reports Server (NTRS)

    Vrbsky, Susan V.; Liu, Jane W. S.

    1993-01-01

    We have designed and implemented a query processor, called APPROXIMATE, that makes approximate answers available if part of the database is unavailable or if there is not enough time to produce an exact answer. The accuracy of the approximate answers produced improves monotonically with the amount of data retrieved to produce the result. The exact answer is produced if all of the needed data are available and query processing is allowed to continue until completion. The monotone query processing algorithm of APPROXIMATE works within the standard relational algebra framework and can be implemented on a relational database system with little change to the relational architecture. We describe here the approximation semantics of APPROXIMATE that serves as the basis for meaningful approximations of both set-valued and single-valued queries. We show how APPROXIMATE is implemented to make effective use of semantic information, provided by an object-oriented view of the database, and describe the additional overhead required by APPROXIMATE.

  3. Coupled effects of temperature and mass transport on the isotope fractionation of zinc during electroplating

    NASA Astrophysics Data System (ADS)

    Black, Jay R.; John, Seth G.; Kavner, Abby

    2014-01-01

    The isotopic composition of zinc metal electrodeposited on a rotating disc electrode from a Zn-citrate aqueous solution was investigated as a function of overpotential (electrochemical driving force), temperature, and rotation rate. Zn metal was measured to be isotopically light with respect to Zn+2 in solution, with observed fractionations varying from Δ66/64Znmetal-aqueous = -1.0‰ to -3.9‰. Fractionation varies continuously as a function of a dimensionless parameter described by the ratio of observed deposition rate to calculated mass-transport limiting rate, where larger fractionations are observed at lower deposition rates, lower temperature, and at faster electrode rotation rates. Thus, the large fractionation and its rate dependence is interpreted as a competition between the two kinetic processes with different effective activation energies: mass-transport-limited (diffusion limited) kinetics with a large activation energy, which creates small fractionations close to the predicted diffusive fractionation; and electrochemical deposition kinetics, with a smaller effective activation energy, which creates large fractionations at low deposition rates and high hydrodynamic fluxes of solute to the electrode. The results provide a framework for predicting isotope fractionation in processes controlled by two competing reactions with different kinetic isotope effects. Light isotopes are electroplated. In all cases light stable isotopes of the metals are preferentially electroplated, with mass-dependent behavior evident where three or more isotopes are measured. Fractionation is time-independent, meaning that the fractionation factor does not vary with the extent of reaction. In most of our experiments, we have controlled the extent of reaction such that only a small amount of metal is deposited from the stock solution, thus avoiding significant evolution of the reservoir composition. In such experiments, the observed isotope fractionation is constant as a

  4. Electronic band structure and effective mass parameters of Ge1-xSnx alloys

    NASA Astrophysics Data System (ADS)

    Lu Low, Kain; Yang, Yue; Han, Genquan; Fan, Weijun; Yeo, Yee-Chia

    2012-11-01

    This work investigates the electronic band structures of bulk Ge1-xSnx alloys using the empirical pseudopotential method (EPM) for Sn composition x varying from 0 to 0.2. The adjustable form factors of EPM were tuned in order to reproduce the band features that agree well with the reported experimental data. Based on the adjusted pseudopotential form factors, the band structures of Ge1-xSnx alloys were calculated along high symmetry lines in the Brillouin zone. The effective masses at the band edges were extracted by using a parabolic line fit. The bowing parameters of hole and electron effective masses were then derived by fitting the effective mass at different Sn compositions by a quadratic polynomial. The hole and electron effective mass were examined for bulk Ge1-xSnx alloys along specific directions or orientations on various crystal planes. In addition, employing the effective-mass Hamiltonian for diamond semiconductor, band edge dispersion at the Γ-point calculated by 8-band k.p. method was fitted to that obtained from EPM approach. The Luttinger-like parameters were also derived for Ge1-xSnx alloys. They were obtained by adjusting the effective-mass parameters of k.p method to fit the k.p band structure to that of the EPM. These effective masses and derived Luttinger parameters are useful for the design of optical and electronic devices based on Ge1-xSnx alloys.

  5. Increasing the Thermal Conductivity of Graphene-Polyamide-6,6 Nanocomposites by Surface-Grafted Polymer Chains: Calculation with Molecular Dynamics and Effective-Medium Approximation.

    PubMed

    Gao, Yangyang; Müller-Plathe, Florian

    2016-02-25

    By employing reverse nonequilibrium molecular dynamics simulations in a full atomistic resolution, the effect of surface-grafted chains on the thermal conductivity of graphene-polyamide-6.6 (PA) nanocomposites has been investigated. The interfacial thermal conductivity perpendicular to the graphene plane is proportional to the grafting density, while it first increases and then saturates with the grafting length. Meanwhile, the intrinsic in-plane thermal conductivity of graphene drops sharply as the grafting density increases. The maximum overall thermal conductivity of nanocomposites appears at an intermediate grafting density because of these two competing effects. The thermal conductivity of the composite parallel to the graphene plane increases with the grafting density and grafting length which is attributed to better interfacial coupling between graphene and PA. There exists an optimal balance between grafting density and grafting length to obtain the highest interfacial and parallel thermal conductivity. Two empirical formulas are suggested, which quantitatively account for the effects of grafting length and density on the interfacial and parallel thermal conductivity. Combined with effective medium approximation, for ungrafted graphene in random orientation, the model overestimates the thermal conductivity at low graphene volume fraction (f < 10%) compared with experiments, while it underestimates it at high graphene volume fraction (f > 10%). For unoriented grafted graphene, the model matches the experimental results well. In short, this work provides some valuable guides to obtain the nanocomposites with high thermal conductivity by grafting chain on the surface of graphene. PMID:26800434

  6. Fitting Nonlinear Ordinary Differential Equation Models with Random Effects and Unknown Initial Conditions Using the Stochastic Approximation Expectation-Maximization (SAEM) Algorithm.

    PubMed

    Chow, Sy-Miin; Lu, Zhaohua; Sherwood, Andrew; Zhu, Hongtu

    2016-03-01

    The past decade has evidenced the increased prevalence of irregularly spaced longitudinal data in social sciences. Clearly lacking, however, are modeling tools that allow researchers to fit dynamic models to irregularly spaced data, particularly data that show nonlinearity and heterogeneity in dynamical structures. We consider the issue of fitting multivariate nonlinear differential equation models with random effects and unknown initial conditions to irregularly spaced data. A stochastic approximation expectation-maximization algorithm is proposed and its performance is evaluated using a benchmark nonlinear dynamical systems model, namely, the Van der Pol oscillator equations. The empirical utility of the proposed technique is illustrated using a set of 24-h ambulatory cardiovascular data from 168 men and women. Pertinent methodological challenges and unresolved issues are discussed. PMID:25416456

  7. Rack Distribution Effects on MPLM Center of Mass

    NASA Technical Reports Server (NTRS)

    Tester, John T.

    2005-01-01

    This research was in support of exploring the need for more flexible "center of gravity (CG) specifications than those currently established by NASA for the Multi-Purpose Logistics Module (MPLM). The MPLM is the cargo carrier for International Space Station (ISS) missions. The MPLM provides locations for 16 standard racks, as shown in Figure 1; not all positions need to be filled in any given flight. The MPLM coordinate system (X(sub M), Y(sub M), Z(sub M)) is illustrated as well. For this project, the primary missions of interest were those which supply the ISS and remove excess materials on the return flights. These flights use a predominate number of "Resupply Stowage Racks" (RSR) and "Resupply Stowage Platforms" (RSP). In these two types of racks, various smaller items are stowed. Hence, these racks will exhibit a considerable range of mass values as well as a range as to where their individual CG are located.

  8. Effective mass from microwave photoresistance in high-mobility 2D electron systems

    NASA Astrophysics Data System (ADS)

    Zudov, Michael; Hatke, Anthony; Watson, John; Manfra, Michael; Pfeiffer, Loren; West, Kenneth

    2013-03-01

    We have performed microwave photoresistance measurements in high mobility GaAs/AlGaAs quantum wells and investigated the value of the effective mass. Surprisingly, the effective mass, obtained from the period of microwave-induced resistance oscillations, is found to be considerably lower than the band mass in GaAs. This finding provides evidence for electron-electron interactions which can be probed by microwave photoresistance in very high Landau levels. In contrast, the measured magneto-plasmon dispersion revealed an effective mass which is close to the band mass, in accord with previous studies. The work at Minnesota and Purdue was supported by the DOE Grant Nos. DE-SC002567 and DE-SC0006671, respectively. The work at Princeton was partially funded by the Gordon and Betty Moore Foundation Foundation and the NSF MRSEC Program..

  9. Optimizing the Zeldovich approximation

    NASA Technical Reports Server (NTRS)

    Melott, Adrian L.; Pellman, Todd F.; Shandarin, Sergei F.

    1994-01-01

    We have recently learned that the Zeldovich approximation can be successfully used for a far wider range of gravitational instability scenarios than formerly proposed; we study here how to extend this range. In previous work (Coles, Melott and Shandarin 1993, hereafter CMS) we studied the accuracy of several analytic approximations to gravitational clustering in the mildly nonlinear regime. We found that what we called the 'truncated Zeldovich approximation' (TZA) was better than any other (except in one case the ordinary Zeldovich approximation) over a wide range from linear to mildly nonlinear (sigma approximately 3) regimes. TZA was specified by setting Fourier amplitudes equal to zero for all wavenumbers greater than k(sub nl), where k(sub nl) marks the transition to the nonlinear regime. Here, we study the cross correlation of generalized TZA with a group of n-body simulations for three shapes of window function: sharp k-truncation (as in CMS), a tophat in coordinate space, or a Gaussian. We also study the variation in the crosscorrelation as a function of initial truncation scale within each type. We find that k-truncation, which was so much better than other things tried in CMS, is the worst of these three window shapes. We find that a Gaussian window e(exp(-k(exp 2)/2k(exp 2, sub G))) applied to the initial Fourier amplitudes is the best choice. It produces a greatly improved crosscorrelation in those cases which most needed improvement, e.g. those with more small-scale power in the initial conditions. The optimum choice of kG for the Gaussian window is (a somewhat spectrum-dependent) 1 to 1.5 times k(sub nl). Although all three windows produce similar power spectra and density distribution functions after application of the Zeldovich approximation, the agreement of the phases of the Fourier components with the n-body simulation is better for the Gaussian window. We therefore ascribe the success of the best-choice Gaussian window to its superior treatment

  10. Thermal radiation effects on magnetohydrodynamic flow past a semi-infinite vertical plate in the presence of mass diffusion

    NASA Astrophysics Data System (ADS)

    Aboeldahab, E. M.; Azzam, G. E. A.

    2005-03-01

    Magnetohydrodynamic (MHD) mixed free-forced heat and mass convective steady incompressible laminar boundary layer flow of a gray optically thick electrically conducting viscous fluid past a semi-infinite vertical plate for high temperature and concentration differences is studied. A uniform magnetic field is applied perpendicular to the plate. The density of the fluid is assumed to reduce exponentially with temperature and concentration. The usual Boussinesq approximation is neglected because of the high temperature and concentration differences between the plate and the ambient fluid. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The boundary layer equations governing the flow are reduced to ordinary differential equations, which are numerically solved by applying an efficient technique. The effects of the density-temperature parameter n, the density-concentration parameter m, the local magnetic parameter M-x, and the radiation parameter R are examined on the velocity, temperature, and con- centration distributions as well as the coefficients of skin-friction, heat flux, and mass flux.

  11. Introduction to Chemistry and Applications in Nature of Mass Independent Isotope Effects Special Feature

    PubMed Central

    Thiemens, Mark H.

    2013-01-01

    Stable isotope ratio variations are regulated by physical and chemical laws. These rules depend on a relation with mass differences between isotopes. New classes of isotope variation effects that deviate from mass dependent laws, termed mass independent isotope effects, were discovered in 1983 and have a wide range of applications in basic chemistry and nature. In this special edition, new applications of these effects to physical chemistry, solar system origin models, terrestrial atmospheric and biogenic evolution, polar paleo climatology, snowball earth geology, and present day atmospheric sciences are presented. PMID:24167299

  12. Introduction to chemistry and applications in nature of mass independent isotope effects special feature.

    PubMed

    Thiemens, Mark H

    2013-10-29

    Stable isotope ratio variations are regulated by physical and chemical laws. These rules depend on a relation with mass differences between isotopes. New classes of isotope variation effects that deviate from mass dependent laws, termed mass independent isotope effects, were discovered in 1983 and have a wide range of applications in basic chemistry and nature. In this special edition, new applications of these effects to physical chemistry, solar system origin models, terrestrial atmospheric and biogenic evolution, polar paleo climatology, snowball earth geology, and present day atmospheric sciences are presented. PMID:24167299

  13. [The effect of anthropometric factors on human cerebellar mass and its age dynamics].

    PubMed

    Stepanenko, A Iu

    2014-01-01

    The purpose of this work was to examine the dependence of human cerebellar mass and its age dynamics on the body length and body-build type. The study was carried out on 295 objects--the corpses of the individuals of both sexes (173 males and 122 females) who died at the age of 20-99 years. The length of the body, the transverse diameter of the chest and the cerebellar mass were measured. Somatotype was determined by the Rees-Eysenck index. It was found that human cerebellar mass ranged from 103 to 197 g (with the average of 144 ± 1.0 g) and was significantly greater in men than in women (150.5 ± 1.3 g vs. 133.9 ± 1.2 g, P < 0.001). Age affected cerebellar mass in men (R = -0.46) more, than in women (R = -0.43). In men, a period of relative stability of the cerebellar mass lasted up to about 50 years and then was followed by a period of its decrease. In women, the stable period was observed until approximately 70 years. The cerebellar mass was related to the body length (R = 0.35 for men and R = 0.36 for women). The dependence of the cerebellar mass on the body length was greater in men (1.0 g/cm) greater than in women (0.5 g/cm): with the increase of the body length the difference in the values of the cerebellar mass between men and women was found to grow. The cerebellar mass in the individuals with various body-build types was not significantly different PMID:25552081

  14. THE EFFECT OF MASS LOSS ON THE TIDAL EVOLUTION OF EXTRASOLAR PLANET

    SciTech Connect

    Guo, J. H.

    2010-04-01

    By combining mass loss and tidal evolution of close-in planets, we present a qualitative study on their tidal migrations. We incorporate mass loss in tidal evolution for planets with different masses and find that mass loss could interfere with tidal evolution. In an upper limit case (beta = 3), a significant portion of mass may be evaporated in a long evolution timescale. Evidence of greater modification of the planets with an initial separation of about 0.1 AU than those with a = 0.15 AU can be found in this model. With the assumption of a large initial eccentricity, the planets with initial mass <=1 M{sub J} and initial distance of about 0.1 AU could not survive. With the supposition of beta = 1.1, we find that the loss process has an effect on the planets with low mass at a {approx} 0.05 AU. In both cases, the effect of evaporation on massive planets can be neglected. Also, heating efficiency and initial eccentricity have significant influence on tidal evolution. We find that even low heating efficiency and initial eccentricity have a significant effect on tidal evolution. Our analysis shows that evaporation on planets with different initial masses can accelerate (decelerate) the tidal evolution due to the increase (decrease) in tide of the planet (star). Consequently, the effect of evaporation cannot be neglected in evolutionary calculations of close-in planets. The physical parameters of HD 209458b can be fitted by our model.

  15. Effect of Accretion of Phantom Energy on Initial Mass of a Primordial Black Hole

    NASA Astrophysics Data System (ADS)

    Naz, Sumaira; Qadir, Asghar

    2012-03-01

    Hawking had shown that black holes radiate with a temperature inversely proportional to their mass, thereby losing energy and hence mass. For sufficiently small masses (less than 1015 g) the black hole would evaporate today and hence has a "life" equal to the present age of the universe. One explanation of the observed acceleration of the universe is by phantom energy. In 2010 Jamil and Qadir have showed that this energy enhances the rate of evaporation. Thus, to have a primordial black hole evaporating today, its initial mass should be larger than 1015 g or the primordial black holes of mass less than 1015 g should evaporate earlier. In fact, it was claimed that the black holes would be ten orders of magnitude larger! This effect is revisited and its dependence on the value of equation of state parameter is studied. It is found that the effect of phantom energy for the 1015 g black hole is negligible but for a 1022 g black hole would be significant. In that case, though, the black hole would not be now exploding. The mass at which the effect of phantom energy equals the effect of Hawking radiation has been called the transition mass. The transition mass has been discussed and the correction term in the lifetime for primordial black holes is computed.

  16. Effect of mass and pole strength on the levitation height of a magnet over a superconductor

    SciTech Connect

    Williams, R.; Matey, J.R.; Arie, Y.; Rathee, J.

    1989-05-01

    We have measured the effect of the mass and pole strength of a magnet on its equilibrium levitation height z over a superconducting disk of YBa/sub 2/Cu/sub 3/O/sub 7/. A simple image force model gives the observed dependence of z on the mass and pole strength, but not the observed proportionality factor.

  17. Extracting the effective mass of electrons in transparent conductive oxide thin films using Seebeck coefficient

    SciTech Connect

    Wang, Yaqin; Zhu, Junhao; Tang, Wu

    2014-05-26

    A method is proposed that combines Seebeck coefficient and carrier concentration to determine the electron effective mass of transparent conductive oxide (TCO) thin films. Experiments were conducted to test the validity of this approach on the transparent conductive Ga-doped ZnO thin films deposited by magnetron sputtering. An evident agreement of the calculated electron effective mass of the films is observed between the proposed approach and the previous studies. Besides, the optical carrier concentration and mobility derived from the calculated electron effective mass and spectroscopic ellipsometry using a complex dielectric function are consistent with those from direct Hall-effect measurement. The agreements suggest that Seebeck coefficient can serve as an alternative tool for extracting the effective mass of electrons in TCO films.

  18. Coupled effects of temperature and mass transport on the isotope fractionation of zinc during electroplating

    NASA Astrophysics Data System (ADS)

    Black, Jay R.; John, Seth G.; Kavner, Abby

    2014-01-01

    The isotopic composition of zinc metal electrodeposited on a rotating disc electrode from a Zn-citrate aqueous solution was investigated as a function of overpotential (electrochemical driving force), temperature, and rotation rate. Zn metal was measured to be isotopically light with respect to Zn+2 in solution, with observed fractionations varying from Δ66/64Znmetal-aqueous = -1.0‰ to -3.9‰. Fractionation varies continuously as a function of a dimensionless parameter described by the ratio of observed deposition rate to calculated mass-transport limiting rate, where larger fractionations are observed at lower deposition rates, lower temperature, and at faster electrode rotation rates. Thus, the large fractionation and its rate dependence is interpreted as a competition between the two kinetic processes with different effective activation energies: mass-transport-limited (diffusion limited) kinetics with a large activation energy, which creates small fractionations close to the predicted diffusive fractionation; and electrochemical deposition kinetics, with a smaller effective activation energy, which creates large fractionations at low deposition rates and high hydrodynamic fluxes of solute to the electrode. The results provide a framework for predicting isotope fractionation in processes controlled by two competing reactions with different kinetic isotope effects. Light isotopes are electroplated. In all cases light stable isotopes of the metals are preferentially electroplated, with mass-dependent behavior evident where three or more isotopes are measured. Fractionation is time-independent, meaning that the fractionation factor does not vary with the extent of reaction. In most of our experiments, we have controlled the extent of reaction such that only a small amount of metal is deposited from the stock solution, thus avoiding significant evolution of the reservoir composition. In such experiments, the observed isotope fractionation is constant as a

  19. Effects of maternal characteristics and climatic variation on birth masses of Alaskan caribou

    USGS Publications Warehouse

    Adams, L.G.

    2005-01-01

    Understanding factors that influence birth mass of mammals provides insights to nutritional trade-offs made by females to optimize their reproduction, growth, and survival. I evaluated variation in birth mass of caribou (Rangifer tarandus) in central Alaska relative to maternal characteristics (age, body mass, cohort, and nutritional condition as influenced by winter severity) during 11 years with substantial variation in winter snowfall. Snowfall during gestation was the predominant factor explaining variation in birth masses, influencing birth mass inversely and through interactions with maternal age and lactation status. Maternal age effects were noted for females ??? 5 years old, declining in magnitude with each successive age class. Birth mass as a proportion of autumn maternal mass was inversely related to winter snowfall, even though there was no decrease in masses of adult females in late winter associated with severe winters. I found no evidence of a hypothesized intergenerational effect of lower birth masses for offspring of females born after severe winters. Caribou produce relatively small offspring but provide exceptional lactation support for those that survive. Conservative maternal investment before parturition may represent an optimal reproductive strategy given that caribou experience stochastic variation in winter severity during gestation, uncertainty of environmental conditions surrounding the birth season, and intense predation on neonates. ?? 2005 American Society of Mammalogists.

  20. Effects of reservoir heterogeneity on scaling of effective mass transfer coefficient for solute transport.

    PubMed

    Leung, Juliana Y; Srinivasan, Sanjay

    2016-09-01

    Modeling transport process at large scale requires proper scale-up of subsurface heterogeneity and an understanding of its interaction with the underlying transport mechanisms. A technique based on volume averaging is applied to quantitatively assess the scaling characteristics of effective mass transfer coefficient in heterogeneous reservoir models. The effective mass transfer coefficient represents the combined contribution from diffusion and dispersion to the transport of non-reactive solute particles within a fluid phase. Although treatment of transport problems with the volume averaging technique has been published in the past, application to geological systems exhibiting realistic spatial variability remains a challenge. Previously, the authors developed a new procedure where results from a fine-scale numerical flow simulation reflecting the full physics of the transport process albeit over a sub-volume of the reservoir are integrated with the volume averaging technique to provide effective description of transport properties. The procedure is extended such that spatial averaging is performed at the local-heterogeneity scale. In this paper, the transport of a passive (non-reactive) solute is simulated on multiple reservoir models exhibiting different patterns of heterogeneities, and the scaling behavior of effective mass transfer coefficient (Keff) is examined and compared. One such set of models exhibit power-law (fractal) characteristics, and the variability of dispersion and Keff with scale is in good agreement with analytical expressions described in the literature. This work offers an insight into the impacts of heterogeneity on the scaling of effective transport parameters. A key finding is that spatial heterogeneity models with similar univariate and bivariate statistics may exhibit different scaling characteristics because of the influence of higher order statistics. More mixing is observed in the channelized models with higher-order continuity. It

  1. Effects of reservoir heterogeneity on scaling of effective mass transfer coefficient for solute transport

    NASA Astrophysics Data System (ADS)

    Leung, Juliana Y.; Srinivasan, Sanjay

    2016-09-01

    Modeling transport process at large scale requires proper scale-up of subsurface heterogeneity and an understanding of its interaction with the underlying transport mechanisms. A technique based on volume averaging is applied to quantitatively assess the scaling characteristics of effective mass transfer coefficient in heterogeneous reservoir models. The effective mass transfer coefficient represents the combined contribution from diffusion and dispersion to the transport of non-reactive solute particles within a fluid phase. Although treatment of transport problems with the volume averaging technique has been published in the past, application to geological systems exhibiting realistic spatial variability remains a challenge. Previously, the authors developed a new procedure where results from a fine-scale numerical flow simulation reflecting the full physics of the transport process albeit over a sub-volume of the reservoir are integrated with the volume averaging technique to provide effective description of transport properties. The procedure is extended such that spatial averaging is performed at the local-heterogeneity scale. In this paper, the transport of a passive (non-reactive) solute is simulated on multiple reservoir models exhibiting different patterns of heterogeneities, and the scaling behavior of effective mass transfer coefficient (Keff) is examined and compared. One such set of models exhibit power-law (fractal) characteristics, and the variability of dispersion and Keff with scale is in good agreement with analytical expressions described in the literature. This work offers an insight into the impacts of heterogeneity on the scaling of effective transport parameters. A key finding is that spatial heterogeneity models with similar univariate and bivariate statistics may exhibit different scaling characteristics because of the influence of higher order statistics. More mixing is observed in the channelized models with higher-order continuity. It

  2. Effect of injecting primary myoblasts versus putative muscle-derived stem cells on mass and force generation in mdx mice.

    PubMed

    Mueller, Gunhild M; O'Day, Terry; Watchko, Jon F; Ontell, Marcia

    2002-06-10

    It is well established that the injection of normal myoblasts or of muscle-derived stem cells (MDSCs) into the muscle of dystrophin-deficient mdx mice results in the incorporation of a number of donor myoblasts into the host muscle. However, the effect of the injected exogenous cells on mdx muscle mass and functional capacity has not been evaluated. This study evaluates the mass and functional capacity of the extensor digitorum longus (EDL) muscles of adult, male mdx mice that received intramuscular injections of primary myoblasts or of MDSCs (isolated by a preplating technique; Qu, Z., Balkir, L., van Deutekom, J.C., Robbins, P.D., Pruchnic, R., and Huard, J., J. Cell Biol. 1998;142:1257-1267) derived from normal mice. Evaluations were made 9 weeks after cell transplantation. Uninjected mdx EDL muscles have a mass 50% greater than that of age-matched C57BL/10J (normal) EDL muscles. Injections of either primary myoblasts or MDSCs have no effect on the mass of mdx EDL muscles. EDL muscles of mdx mice generate 43% more absolute twitch tension and 43% less specific tetanic tension then do EDL muscles of C57BL/10J mice. However, the absolute tetanic and specific twitch tension of mdx and C57BL/10J EDL muscles are similar. Injection of either primary myoblasts or MDSCs has no effect on the absolute or specific twitch and tetanic tensions of mdx muscle. Approximately 25% of the myofibers in mdx EDL muscles that received primary myoblasts react positively with antibody to dystrophin. There is no significant difference in the number of dystrophin-positive myofibers when MDSCs are injected. Regardless of the source of donor cells, dystrophin is limited to short distances (60-900 microm) along the length of the myofibers. This may, in part, explain the failure of cellular therapy to alter the contractile properties of murine dystrophic muscle. PMID:12067441

  3. Hole effective masses and subband splitting in type-II superlattice infrared detectors

    NASA Astrophysics Data System (ADS)

    Ting, David Z.; Soibel, Alexander; Gunapala, Sarath D.

    2016-05-01

    We explore band structure effects to help determine the suitability of n-type type-II superlattice (T2SL) absorbers for infrared detectors. It is often assumed that the exceedingly large growth-direction band-edge curvature hole effective mass in n-type long wavelength infrared (LWIR) T2SL would lead to low hole mobility and therefore low detector collection quantum efficiency. We computed the thermally averaged conductivity effective mass and show that the LWIR T2SL hole conductivity effective mass along the growth direction can be orders of magnitude smaller than the corresponding band-edge effective mass. LWIR InAs/GaSb T2SL can have significantly smaller growth-direction hole conductivity effective mass than its InAs/InAsSb counterpart. For the InAs/InAsSb T2SL, higher Sb fraction is more favorable for hole transport. Achieving long hole diffusion length becomes progressively more difficult for the InAs/InAsSb T2SL as the cutoff wavelength increases, since its growth-direction hole conductivity effective mass increases significantly with decreasing band gap. However, this is mitigated by the fact that the splitting between the top valence subbands also increases with the cutoff wavelength, leading to reduced inter-subband scattering and increased relaxation time.

  4. Main-Sequence Effective Temperatures from a Revised Mass-Luminosity Relation Based on Accurate Properties

    NASA Astrophysics Data System (ADS)

    Eker, Z.; Soydugan, F.; Soydugan, E.; Bilir, S.; Yaz Gökçe, E.; Steer, I.; Tüysüz, M.; Şenyüz, T.; Demircan, O.

    2015-04-01

    The mass-luminosity (M-L), mass-radius (M-R), and mass-effective temperature (M-{{T}eff}) diagrams for a subset of galactic nearby main-sequence stars with masses and radii accurate to ≤slant 3% and luminosities accurate to ≤slant 30% (268 stars) has led to a putative discovery. Four distinct mass domains have been identified, which we have tentatively associated with low, intermediate, high, and very high mass main-sequence stars, but which nevertheless are clearly separated by three distinct break points at 1.05, 2.4, and 7 {{M}⊙ } within the studied mass range of 0.38-32 {{M}⊙ }. Further, a revised mass-luminosity relation (MLR) is found based on linear fits for each of the mass domains identified. The revised, mass-domain based MLRs, which are classical (L\\propto {{M}α }), are shown to be preferable to a single linear, quadratic, or cubic equation representing an alternative MLR. Stellar radius evolution within the main sequence for stars with M\\gt 1 {{M}⊙ } is clearly evident on the M-R diagram, but it is not clear on the M-{{T}eff} diagram based on published temperatures. Effective temperatures can be calculated directly using the well known Stephan-Boltzmann law by employing the accurately known values of M and R with the newly defined MLRs. With the calculated temperatures, stellar temperature evolution within the main sequence for stars with M\\gt 1 {{M}⊙ } is clearly visible on the M-{{T}eff} diagram. Our study asserts that it is now possible to compute the effective temperature of a main-sequence star with an accuracy of ˜6%, as long as its observed radius error is adequately small (\\lt 1%) and its observed mass error is reasonably small (\\lt 6%).

  5. Effect of virtual mass on the characteristics and the numerical stability in two-phase flows

    SciTech Connect

    No, H.C.; Kazimi, M.S.

    1981-04-01

    It is known that the typical six equation two-fluid model of the two-phase flow possesses complex characteristics, exhibits unbounded instabilities in the short-wavelength limit and constitutes an ill-posed initial value problem. Among the suggestions to overcome these difficulties, one model for the virtual mass force terms were studied here, because the virtual mass represents real physical effects to accomplish the dissipation for numerical stability. It was found that the virtual mass has a profound effect upon the mathematical characteristic and numerical stability. Here a quantitative bound on the coefficient of the virtual mass terms was suggested for mathematical hyperbolicity and numerical stability. It was concluded that the finite difference scheme with the virtual mass model is restricted only by the convective stability conditions with the above suggested value.

  6. The Effect of Flow Pulsations on Coriolis Mass Flow Meters

    NASA Astrophysics Data System (ADS)

    Cheesewright, R.; Clark, C.

    1998-11-01

    It has been reported that the accuracy of Coriolis mass flow meters can be adversely affected by the presence of pulsations (at particular frequencies) in the flow. A full analysis of the transient performance of a commercial Coriolis meter is only possible using finite element techniques. However, this is a transient, nonlinear problem in which the space and time variables are not (strictly) separable and the finite element techniques for tackling such problems make it desirable to have an analytical solution for a simplified meter, against which the finite element solution can be compared. This paper reports such a solution. The solution will also provide guidance for experiments. Existing analytical solutions for the performance of Coriolis meters in steady flow (a complex eigenvalue problem) are not easily extended to the transient flow case. The paper thus begins with the presentation of an alternative solution for steady flow through a simple, straight tube, Coriolis meter and it is notable that this solution gives a simple analytical expression for the experimentally observed small change in the resonant frequency of the meter, with flow rate, as well as an analytical expression for the meter sensitivity. The analysis is extended to the transient case, using classical, forced vibration, modal decomposition techniques. The solution shows that, unlike the steady flow case where the detector signals contain components at the drive frequency and the second mode frequency (Coriolis frequency), for pulsatile flow the detector signals will in general contain components involving at least four frequencies. It is demonstrated that the meter error depends on the algorithm used to estimate the phase difference from the detector signals. The particular flow pulsation frequencies which could possibly lead to large meter errors are identified.

  7. Determination of PM mass emissions from an aircraft turbine engine using particle effective density

    NASA Astrophysics Data System (ADS)

    Durdina, L.; Brem, B. T.; Abegglen, M.; Lobo, P.; Rindlisbacher, T.; Thomson, K. A.; Smallwood, G. J.; Hagen, D. E.; Sierau, B.; Wang, J.

    2014-12-01

    Inventories of particulate matter (PM) emissions from civil aviation and air quality models need to be validated using up-to-date measurement data corrected for sampling artifacts. We compared the measured black carbon (BC) mass and the total PM mass determined from particle size distributions (PSD) and effective density for a commercial turbofan engine CFM56-7B26/3. The effective density was then used to calculate the PM mass losses in the sampling system. The effective density was determined using a differential mobility analyzer and a centrifugal particle mass analyzer, and increased from engine idle to take-off by up to 60%. The determined mass-mobility exponents ranged from 2.37 to 2.64. The mean effective density determined by weighting the effective density distributions by PM volume was within 10% of the unit density (1000 kg/m3) that is widely assumed in aircraft PM studies. We found ratios close to unity between the PM mass determined by the integrated PSD method and the real-time BC mass measurements. The integrated PSD method achieved higher precision at ultra-low PM concentrations at which current mass instruments reach their detection limit. The line loss model predicted ∼60% PM mass loss at engine idle, decreasing to ∼27% at high thrust. Replacing the effective density distributions with unit density lead to comparable estimates that were within 20% and 5% at engine idle and high thrust, respectively. These results could be used for the development of a robust method for sampling loss correction of the future PM emissions database from commercial aircraft engines.

  8. Nonequilibrium Green's function formulation of intersubband absorption for nonparabolic single-band effective mass Hamiltonian

    SciTech Connect

    Kolek, Andrzej

    2015-05-04

    The formulas are derived that enable calculations of intersubband absorption coefficient within nonequilibrium Green's function method applied to a single-band effective-mass Hamiltonian with the energy dependent effective mass. The derivation provides also the formulas for the virtual valence band components of the two-band Green's functions which can be used for more exact estimation of the density of states and electrons and more reliable treatment of electronic transport in unipolar n-type heterostructure semiconductor devices.

  9. The Additional-Mass Effect of Plates as Determined by Experiments

    NASA Technical Reports Server (NTRS)

    Gracey, William

    1941-01-01

    The apparent increase in the inertia properties of a body moving in a fluid medium has been called the additional-mass effect. This report presents a resume of test procedures and results of experimental determinations of the additional-mass effect of flat plates. In addition to data obtained from various foreign sources and from a NACA investigation in 1933, the results of tests recently conducted by the National Advisory Committee for Aeronautics are included.

  10. Approximate option pricing

    SciTech Connect

    Chalasani, P.; Saias, I.; Jha, S.

    1996-04-08

    As increasingly large volumes of sophisticated options (called derivative securities) are traded in world financial markets, determining a fair price for these options has become an important and difficult computational problem. Many valuation codes use the binomial pricing model, in which the stock price is driven by a random walk. In this model, the value of an n-period option on a stock is the expected time-discounted value of the future cash flow on an n-period stock price path. Path-dependent options are particularly difficult to value since the future cash flow depends on the entire stock price path rather than on just the final stock price. Currently such options are approximately priced by Monte carlo methods with error bounds that hold only with high probability and which are reduced by increasing the number of simulation runs. In this paper the authors show that pricing an arbitrary path-dependent option is {number_sign}-P hard. They show that certain types f path-dependent options can be valued exactly in polynomial time. Asian options are path-dependent options that are particularly hard to price, and for these they design deterministic polynomial-time approximate algorithms. They show that the value of a perpetual American put option (which can be computed in constant time) is in many cases a good approximation to the value of an otherwise identical n-period American put option. In contrast to Monte Carlo methods, the algorithms have guaranteed error bounds that are polynormally small (and in some cases exponentially small) in the maturity n. For the error analysis they derive large-deviation results for random walks that may be of independent interest.

  11. Social Effects of Mass Media Advertising on the Elderly.

    ERIC Educational Resources Information Center

    Smith, Ruth B.; And Others

    A study examined the effects of media advertising on the elderly to determine whether they use the media to help combat social disengagement, whether they perceived the elderly as positively portrayed in advertising, whether they perceive their role as consumer as declining, whether television advertising reinforced sex roles, and whether the…

  12. Beyond the Kirchhoff approximation

    NASA Technical Reports Server (NTRS)

    Rodriguez, Ernesto

    1989-01-01

    The three most successful models for describing scattering from random rough surfaces are the Kirchhoff approximation (KA), the small-perturbation method (SPM), and the two-scale-roughness (or composite roughness) surface-scattering (TSR) models. In this paper it is shown how these three models can be derived rigorously from one perturbation expansion based on the extinction theorem for scalar waves scattering from perfectly rigid surface. It is also shown how corrections to the KA proportional to the surface curvature and higher-order derivatives may be obtained. Using these results, the scattering cross section is derived for various surface models.

  13. On the computation of finite bottom-quark mass effects in Higgs boson production

    NASA Astrophysics Data System (ADS)

    Mueller, Romain; Öztürk, Deniz Gizem

    2016-08-01

    We present analytic results for the partonic cross-sections contributing to the top-bottom interference in Higgs production via gluon fusion at hadron colliders at NLO accuracy in QCD. We develop a method of expansion in small bottom-mass for master integrals and combine it with the usual infinite top-mass effective theory. Our method of expansion admits a simple algorithmic description and can be easily generalized to any small parameter. These results for the integrated cross-sections will be needed in the computation of the renormalization counter-terms entering the computation of finite bottom-quark mass effects at NNLO.

  14. Oscillator strengths and radiative decay rates for spin-changing S-P transitions in helium: finite nuclear mass effects

    NASA Astrophysics Data System (ADS)

    Morton, Donald C.; Schulhoff, Eva E.; Drake, G. W. F.

    2015-12-01

    We have calculated the electric dipole (E1) and magnetic quadrupole (M2) oscillator strengths and spontaneous decay rates for 24 spin-changing transitions of atomic helium. We included the effects of the finite nuclear mass and the anomalous magnetic moment of the electron augmented by the recently derived Pachucki term. The specific transitions for 4He are n{ }1{{{S}}}0-{n}\\prime { }3{{{P}}}{1,2} and n{ }3{{{S}}}1-{n}\\prime { }1{{{P}}}1 with n,{n}\\prime ≤slant 3 and n≤slant 10 for {n}\\prime =n. For the E1 calculations we used the Breit approximation and pseudostate expansions to perform the perturbation sums over intermediate states in both the length and velocity gauge as a check on both numerical accuracy and validity of the transition operators. The corrections for the nuclear mass and the electron anomaly tend to cancel, indicating that if one is included, then so should be the other. The tables give mass- and anomaly-dependent coefficients permitting the easy generation of results for the other isotopes of helium.

  15. RETIRED A STARS: THE EFFECT OF STELLAR EVOLUTION ON THE MASS ESTIMATES OF SUBGIANTS

    SciTech Connect

    Johnson, John Asher; Morton, Timothy D.; Wright, Jason T.

    2013-01-20

    Doppler surveys have shown that the occurrence rate of Jupiter-mass planets appears to increase as a function of stellar mass. However, this result depends on the ability to accurately measure the masses of evolved stars. Recently, Lloyd called into question the masses of subgiant stars targeted by Doppler surveys. Lloyd argues that very few observable subgiants have masses greater than 1.5 M {sub Sun }, and that most of them have masses in the range 1.0-1.2 M {sub Sun }. To investigate this claim, we use Galactic stellar population models to generate an all-sky distribution of stars. We incorporate the effects that make massive subgiants less numerous, such as the initial mass function and differences in stellar evolution timescales. We find that these effects lead to negligibly small systematic errors in stellar mass estimates, in contrast to the Almost-Equal-To 50% errors predicted by Lloyd. Additionally, our simulated target sample does in fact include a significant fraction of stars with masses greater than 1.5 M {sub Sun }, primarily because the inclusion of an apparent magnitude limit results in a Malmquist-like bias toward more massive stars, in contrast to the volume-limited simulations of Lloyd. The magnitude limit shifts the mean of our simulated distribution toward higher masses and results in a relatively smaller number of evolved stars with masses in the range 1.0-1.2 M {sub Sun }. We conclude that, within the context of our present-day understanding of stellar structure and evolution, many of the subgiants observed in Doppler surveys are indeed as massive as main-sequence A stars.

  16. The effects of loaded carrier mass and formulation mass on aerosolization efficiency in dry powder inhaler devices.

    PubMed

    Ooi, Jesslynn; Gill, Charlotte; Young, Paul M; Traini, Daniela

    2015-01-01

    Previous studies have suggested that particle-particle impaction may influence aerosolization properties in carrier-based dry powder inhalers, through transfer of kinetic energy from large carriers to surface-deposited active drug. The importance of particle-particle collision has yet to be compared against other mechanisms that could lead to drug liberation, such as particle-wall impaction and turbulence. In particular, particle-particle collisions are difficult to model in silico due to computational restrictions. This study investigated the effects of dry powder inhaler particle-particle collisions in vitro using an established carrier-drug model dry powder inhalation formulation. Spherical polystyrene beads of median size 82.80 μm were chosen as a model carrier as they were of uniform size, shape, surface area, density, porosity and hardness and thus eliminated potential variables that would have conflicted with the study. This model carrier was geometrically blended with micronized salbutamol sulphate (loaded blend). The correlation between the mass of loaded blend (5-40 mg) in the Rotahaler® DPI device and resulting fine particle fraction (FPF) was examined at a constant flow rate of 60 L.min(-1). In a second experiment, the mass of loaded blend was kept constant and a variable amount of blank carrier particles were added to the Rotahaler® device to ascertain if additional "blank" carrier particles affected the final FPF. The efficiency of aerosolization remained constant with varying amounts of blank carrier particles as determined by the fine particle fraction of the emitted dose (FPFED) and fine particle fraction of the loaded dose (FPFLD). No statistical difference in FPFED and FPFLD values were observed for increasing masses of blank carrier. In addition, no statistical difference in FPFED and FPFLD between the two experiments was obtained. These observations suggest that particle-particle collisions are not a driving mechanism responsible for

  17. Effective photon mass and exact translating quantum relativistic structures

    NASA Astrophysics Data System (ADS)

    Haas, Fernando; Manrique, Marcos Antonio Albarracin

    2016-04-01

    Using a variation of the celebrated Volkov solution, the Klein-Gordon equation for a charged particle is reduced to a set of ordinary differential equations, exactly solvable in specific cases. The new quantum relativistic structures can reveal a localization in the radial direction perpendicular to the wave packet propagation, thanks to a non-vanishing scalar potential. The external electromagnetic field, the particle current density, and the charge density are determined. The stability analysis of the solutions is performed by means of numerical simulations. The results are useful for the description of a charged quantum test particle in the relativistic regime, provided spin effects are not decisive.

  18. Modelling non-adiabatic effects in H{sub 3}{sup +}: Solution of the rovibrational Schrödinger equation with motion-dependent masses and mass surfaces

    SciTech Connect

    Mátyus, Edit; Szidarovszky, Tamás

    2014-10-21

    Introducing different rotational and vibrational masses in the nuclear-motion Hamiltonian is a simple phenomenological way to model rovibrational non-adiabaticity. It is shown on the example of the molecular ion H{sub 3}{sup +}, for which a global adiabatic potential energy surface accurate to better than 0.1 cm{sup −1} exists [M. Pavanello, L. Adamowicz, A. Alijah, N. F. Zobov, I. I. Mizus, O. L. Polyansky, J. Tennyson, T. Szidarovszky, A. G. Császár, M. Berg et al., Phys. Rev. Lett. 108, 023002 (2012)], that the motion-dependent mass concept yields much more accurate rovibrational energy levels but, unusually, the results are dependent upon the choice of the embedding of the molecule-fixed frame. Correct degeneracies and an improved agreement with experimental data are obtained if an Eckart embedding corresponding to a reference structure of D{sub 3h} point-group symmetry is employed. The vibrational mass of the proton in H{sub 3}{sup +} is optimized by minimizing the root-mean-square (rms) deviation between the computed and recent high-accuracy experimental transitions. The best vibrational mass obtained is larger than the nuclear mass of the proton by approximately one third of an electron mass, m{sub opt,p}{sup (v)}=m{sub nuc,p}+0.31224 m{sub e}. This optimized vibrational mass, along with a nuclear rotational mass, reduces the rms deviation of the experimental and computed rovibrational transitions by an order of magnitude. Finally, it is shown that an extension of the algorithm allowing the use of motion-dependent masses can deal with coordinate-dependent mass surfaces in the rovibrational Hamiltonian, as well.

  19. Stochastic and compensatory effects limit persistence of variation in body mass of young caribou

    USGS Publications Warehouse

    Dale, B.W.; Adams, L.G.; Collins, W.B.; Joly, Kyle; Valkenburg, P.; Tobey, R.

    2008-01-01

    Nutritional restriction during growth can have short- and long-term effects on fitness; however, animals inhabiting uncertain environments may exhibit adaptations to cope with variation in food availability. We examined changes in body mass in free-ranging female caribou (Rangifer tarandus) by measuring mass at birth and at 4, 11, and 16 months of age to evaluate the relative importance of seasonal nutrition to growth, the persistence of cohort-specific variation in body mass through time, and compensatory growth of individuals. Relative mean body mass of cohorts did not persist through time. Compensatory growth of smaller individuals was not observed in summer; however, small calves exhibited more positive change in body mass than did large calves. Compensation occurred during periods of nutritional restriction (winter) rather than during periods of rapid growth (summer) thus differing from the conventional view of compensatory growth. ?? 2008 American Society of Mammalogists.

  20. SU-E-T-510: Mathematical Analysis of Approximate Biological Effective Dose (BED) Calculation for Multi-Phase Radiotherapy Treatment Plans

    SciTech Connect

    Kauweloa, K; Gutierrez, A; Bergamo, A; Stathakis, S; Papanikolaou, N; Mavroidis, P

    2014-06-01

    Purpose: There is growing interest about biological effective dose (BED) and its application in treatment plan evaluation due to its stronger correlation with treatment outcome. An approximate biological effective dose (BEDA) equation was introduced to simplify BED calculations by treatment planning systems in multi-phase treatments. The purpose of this work is to reveal its mathematical properties relative to the true, multi-phase BED (BEDT) equation. Methods: The BEDT equation was derived and used to reveal the mathematical properties of BEDA. MATLAB (MathWorks, Natick, MA) was used to simulate and analyze common and extreme clinical multi-phase cases. In those cases, percent error (Perror) and Bland-Altman analysis were used to study the significance of the inaccuracies of BEDA for different combinations of total doses, numbers of fractions, doses per fractions and α over β values. All the calculations were performed on a voxel-basis in order to study how dose distributions would affect the accuracy of BEDA. Results: When the voxel dose-per-fractions (DPF) delivered by both phases are equal, BEDA and BEDT are equal. In heterogeneous dose distributions, which significantly vary between the phases, there are fewer occurrences of equal DPFs and hence the imprecision of BEDA is greater. It was shown that as the α over β ratio increased the accuracy of BEDA would improve. Examining twenty-four cases, it was shown that the range of DPF ratios for a 3 Perror varied from 0.32 to 7.50Gy, whereas for Perror of 1 the range varied from 0.50 to 2.96Gy. Conclusion: The DPF between the different phases should be equal in order to render BEDA accurate. OARs typically receive heterogeneous dose distributions hence the probability of equal DPFs is low. Consequently, the BEDA equation should only be used for targets or OARs that receive uniform or very similar dose distributions by the different treatment phases.

  1. The Effects of the Local Environment and Stellar Mass on Galaxy Quenching to z ∼ 3

    NASA Astrophysics Data System (ADS)

    Darvish, Behnam; Mobasher, Bahram; Sobral, David; Rettura, Alessandro; Scoville, Nick; Faisst, Andreas; Capak, Peter

    2016-07-01

    We study the effects of the local environment and stellar mass on galaxy properties using a mass complete sample of quiescent and star-forming systems in the COSMOS field at z≲ 3. We show that at z≲ 1 the median star formation rate (SFR) and specific SFR (sSFR) of all galaxies depend on the environment, but they become independent of the environment at z ≳ 1. However, we find that only for star-forming galaxies, the median SFR and sSFR are similar in different environments regardless of redshift and stellar mass. We find that the quiescent fraction depends on the environment at z ≲ 1 and on stellar mass out to z ∼ 3. We show that at z ≲ 1 galaxies become quiescent faster in denser environments and that the overall environmental quenching efficiency increases with cosmic time. Environmental and mass quenching processes depend on each other. At z ≲ 1 denser environments more efficiently quench galaxies with higher masses (log(M/{M}ȯ ) ≳ 10.7), possibly due to a higher merger rate of massive galaxies in denser environments. We also show that mass quenching is more efficient in denser regions. We show that the overall mass quenching efficiency ({ε }{mass}) for more massive galaxies (log(M/{M}ȯ ) ≳ 10.2) rises with cosmic time until z ∼ 1 and then flattens out. However, for less massive galaxies, the rise in {ε }{mass} continues to the present time. Our results suggest that environmental quenching is only relevant at z ≲ 1 and is likely a fast process, whereas mass quenching is the dominant mechanism at z ≳ 1 with a possible stellar feedback physics.

  2. Global nitrogen cycle: pre-Anthropocene mass and isotope fluxes and effects of human perturbations

    NASA Astrophysics Data System (ADS)

    Joo, Y.; Li, D. D.; Lerman, A.; Mackenzie, F. T.

    2012-12-01

    The size of the largest nitrogen reservoir -- the Earth atmosphere -- and its long residence time of approximately 17 million years suggest that the global N cycle was likely to be balanced at geological time scales. After the industrial revolution, human activities, such as mining, fossil fuel burning, land use change, and artificial fertilization, have resulted in perturbations and numerous flux changes of the N cycle. The effects of human activities on the mass and isotopic composition of the N reservoirs can be predicted using a detailed N cycle model with estimated additions. For the pre-Anthropocene period, a balanced steady-state N cycle model was constructed based on the Redfield ratios and an extensive literature review. The model includes 14 N reservoirs in the domains of the atmosphere, land, and ocean. The biotic reservoirs on land and in the ocean (land plants and marine biota) interact with atmospheric N2 and dissolved inorganic N (DIN) in ocean and soil waters. DIN further interacts with dissolved organic N (DON), particulate organic matter (POM), and ocean sediments. Atmosphere supplies N to land and ocean domains mainly by N fixation, deposition, and dissolution, and these fluxes are balanced by denitrification and volatilization back to atmosphere. Riverine transport of dissolved and particulate N connects land and ocean domains. Once the cycle is mass-balanced, the isotopic composition of reservoir and the size of fractionation accompanying microbial transformations and transfers of N species between the reservoirs were estimated by numerical iteration of the flux equations based on the reported δ15N values and fractionation factors. The calculated fractionation factors tend to be smaller in magnitude than the experimentally measured ones in natural systems, which can be interpreted as an indication of N-limited conditions prevailing in pre-Anthropocene world: a smaller isotope fractionation can be interpreted as an indication of nitrogen

  3. Oblique incidence effects in direct x-ray detectors: A first-order approximation using a physics-based analytical model

    SciTech Connect

    Badano, Aldo; Freed, Melanie; Fang Yuan

    2011-04-15

    Purpose: The authors describe the modifications to a previously developed analytical model of indirect CsI:Tl-based detector response required for studying oblique x-ray incidence effects in direct semiconductor-based detectors. This first-order approximation analysis allows the authors to describe the associated degradation in resolution in direct detectors and compare the predictions to the published data for indirect detectors. Methods: The proposed model is based on a physics-based analytical description developed by Freed et al. [''A fast, angle-dependent, analytical model of CsI detector response for optimization of 3D x-ray breast imaging systems,'' Med. Phys. 37(6), 2593-2605 (2010)] that describes detector response functions for indirect detectors and oblique incident x rays. The model, modified in this work to address direct detector response, describes the dependence of the response with x-ray energy, thickness of the transducer layer, and the depth-dependent blur and collection efficiency. Results: The authors report the detector response functions for indirect and direct detector models for typical thicknesses utilized in clinical systems for full-field digital mammography (150 {mu}m for indirect CsI:Tl and 200 {mu}m for a-Se direct detectors). The results suggest that the oblique incidence effect in a semiconductor detector differs from that in indirect detectors in two ways: The direct detector model produces a sharper overall PRF compared to the response corresponding to the indirect detector model for normal x-ray incidence and a larger relative increase in blur along the x-ray incidence direction compared to that found in indirect detectors with respect to the response at normal incidence angles. Conclusions: Compared to the effect seen in indirect detectors, the direct detector model exhibits a sharper response at normal x-ray incidence and a larger relative increase in blur along the x-ray incidence direction with respect to the blur in the

  4. A unified approach to the Darwin approximation

    SciTech Connect

    Krause, Todd B.; Apte, A.; Morrison, P. J.

    2007-10-15

    There are two basic approaches to the Darwin approximation. The first involves solving the Maxwell equations in Coulomb gauge and then approximating the vector potential to remove retardation effects. The second approach approximates the Coulomb gauge equations themselves, then solves these exactly for the vector potential. There is no a priori reason that these should result in the same approximation. Here, the equivalence of these two approaches is investigated and a unified framework is provided in which to view the Darwin approximation. Darwin's original treatment is variational in nature, but subsequent applications of his ideas in the context of Vlasov's theory are not. We present here action principles for the Darwin approximation in the Vlasov context, and this serves as a consistency check on the use of the approximation in this setting.

  5. Nuclear point mass effects in the interaction of energetic ion with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zheng, Li-Ping; Yan, Long; Zhu, Zhi-Yong; Ma, Guo-Liang

    2016-03-01

    We have calculated deposited energies of various energetic ions in carbon nanotubes, to study nuclear point mass effects, with the help of a static Monte Carlo (MC) simulation program. As a result of nuclear point mass effects, we show that at the same incident energy, the ion-deposited energy maximizes, while its mass has intermediate mass values, such as 11B, 12C and 14N ion masses, under hundreds keV 4He, 11B, 12C, 14N, 20Ne, 28Si and 40Ar ion irradiations of a thin-walled carbon nanotube. We also show that at the same incident energy, the coordination defect number maximizes, while its mass has an intermediate mass (20Ne) value, under hundreds keV 4He, 20Ne and 40Ar ion irradiations of the thin-walled nanotube. We derive an ion-deposited energy formula to analyze these maximum phenomena, and compare the MC simulation results with the MD (molecular dynamics) ones.

  6. Light attenuation - a more effective basis for the management of fine suspended sediment than mass concentration?

    PubMed

    Davies-Colley, Robert J; Ballantine, Deborah J; Elliott, Sandy H; Swales, Andrew; Hughes, Andrew O; Gall, Mark P

    2014-01-01

    Fine sediment continues to be a major diffuse pollution concern with its multiple effects on aquatic ecosystems. Mass concentrations (and loads) of fine sediment are usually measured and modelled, apparently with the assumption that environmental effects of sediment are predictable from mass concentrations. However, some severe impacts of fine sediment may not correlate well with mass concentration, notably those related to light attenuation by suspended particles. Light attenuation per unit mass concentration of suspended particulate matter in waters varies widely with particle size, shape and composition. Data for suspended sediment concentration, turbidity and visual clarity (which is inversely proportional to light beam attenuation) from 77 diverse New Zealand rivers provide valuable insights into the mutual relationships of these quantities. Our analysis of these relationships, both across multiple rivers and within individual rivers, supports the proposition that light attenuation by fine sediment is a more generally meaningful basis for environmental management than sediment mass. Furthermore, optical measurements are considerably more practical, being much cheaper (by about four-fold) to measure than mass concentrations, and amenable to continuous measurement. Mass concentration can be estimated with sufficient precision for many purposes from optical surrogates locally calibrated for particular rivers. PMID:24804661

  7. Normalizing the thermal effects of radiofrequency radiation: body mass versus total body surface area

    SciTech Connect

    Gordon, C.J.

    1987-01-01

    The current guideline for exposure to radiofrequency radiation (RFR) of 0.4 W/kg may have inadvertently been set too high. The guideline is based on the rate of RFR absorption normalized with respect to body mass. Based primarily on data for work stoppage in the rat, the 0.4 W/kg guideline was calculated by the dividing the 4.0 W/kg dose by a safety factor of 10. However, if the RFR dose in the rat had been normalized with respect to surface area rather than body mass, the exposure guideline would be 2.3 W/sq m which translates, for a 80 kg adult, to an SAR of approximately 0.06 W/kg. Thus, the current RF exposure guideline may be several-fold greater than originally intended.

  8. How effective and cost-effective was the national mass media smoking cessation campaign ‘Stoptober’?☆

    PubMed Central

    Brown, Jamie; Kotz, Daniel; Michie, Susan; Stapleton, John; Walmsley, Matthew; West, Robert

    2014-01-01

    Background A national smoking cessation campaign based on behaviour change theory and operating through both traditional and new media was launched across England during late 2012 (‘Stoptober’). In addition to attempting to start a movement in which smokers would quit at the same time in response to a positive mass quitting trigger, the campaign set smokers the goal of being smoke-free for October and embodied other psychological principles in a range of tools and communications. Methods Data on quit attempts were obtained from 31,566 past-year smokers during nationally representative household surveys conducted monthly between 2007 and 2012. The effectiveness of the campaign was assessed by the increase in national quit attempt rate in October relative to other months in 2012 vs. 2007–2011. Results Relative to other months in the year, more people tried to quit in October in 2012 compared with 2007–2011 (OR = 1.79, 95%CI = 1.20–2.68). In 2012 there was an approximately 50% increase in quitting during October compared with other months of the same year (9.6% vs. 6.6%; OR = 1.50, 95%CI = 1.05–2.15), whereas in 2007–2011 the rate in October was non-significantly less than in other months of the same period (6.4% vs. 7.5%; OR = 0.84, 95%CI = 0.70–1.00). Stoptober is estimated to have generated an additional 350,000 quit attempts and saved 10,400 discounted life years (DLY) at less than £415 per DLY in the modal age group. Conclusions Designing a national public health campaign with a clear behavioural target (making a serious quit attempt) using key psychological principles can yield substantial behaviour change and public health impact. PMID:24322004

  9. Uniform synthetic magnetic field and effective mass for cold atoms in a shaken optical lattice.

    NASA Astrophysics Data System (ADS)

    Sols, Fernando; Creffield, Charles E.; Pieplow, Gregor; Goldman, Nathan

    2016-05-01

    Cold atoms can be made to experience synthetic magnetic fields when placed in a suitably driven optical lattice. For coherent systems the switching protocol plays an essential role in determining the long time behavior. Relatively simple driving schemes may generate a uniform magnetic flux but an inhomogeneous effective mass. A two-stage split driving scheme can recover a uniform effective mass but at the price of rendering the magnetic field space dependent. We propose a four-stage split driving that generates uniform field and mass of arbitrary values for all driving amplitudes. Finally, we study a modified two-stage split driving approach that enables uniform field and mass for most of but not all values of the magnetic field. Work supported by MINECO (Spain) under Grant FIS2013-41716-P, by FRS-FNRS (Belgium), and by BSPO under PAI Project No. P7/18 DYGEST.

  10. EFFECT OF UNCERTAINTIES IN STELLAR MODEL PARAMETERS ON ESTIMATED MASSES AND RADII OF SINGLE STARS

    SciTech Connect

    Basu, Sarbani; Verner, Graham A.; Chaplin, William J.; Elsworth, Yvonne E-mail: gav@bison.ph.bham.ac.uk E-mail: y.p.elsworth@bham.ac.uk

    2012-02-10

    Accurate and precise values of radii and masses of stars are needed to correctly estimate properties of extrasolar planets. We examine the effect of uncertainties in stellar model parameters on estimates of the masses, radii, and average densities of solar-type stars. We find that in the absence of seismic data on solar-like oscillations, stellar masses can be determined to a greater accuracy than either stellar radii or densities; but to get reasonably accurate results the effective temperature, log g, and metallicity must be measured to high precision. When seismic data are available, stellar density is the most well-determined property, followed by radius, with mass the least well-determined property. Uncertainties in stellar convection, quantified in terms of uncertainties in the value of the mixing length parameter, cause the most significant errors in the estimates of stellar properties.

  11. Relativistic scattering with a spatially dependent effective mass in the Dirac equation

    SciTech Connect

    Alhaidari, A. D.; Bahlouli, H.; Abdelmonem, M. S.; Al-Hasan, A.

    2007-06-15

    We formulate a relativistic algebraic method of scattering for systems with spatially dependent mass based on the J-matrix method. The reference Hamiltonian is the three-dimensional Dirac Hamiltonian but with a mass that is position-dependent with a constant asymptotic limit. Additionally, this effective mass distribution is locally represented in a finite dimensional function subspace. The spinor couples to spherically symmetric vector and pseudo scalar potentials that are short-range such that they are accurately represented by their matrix elements in the same finite dimensional subspace. We calculate the relativistic phase shift as a function of energy for a given configuration and study the effect of spatial variation of the mass on the energy resonance structure.

  12. Effect of tip mass on frequency response and sensitivity of AFM cantilever in liquid.

    PubMed

    Farokh Payam, Amir; Fathipour, Morteza

    2015-03-01

    The effect of tip mass on the frequency response and sensitivity of atomic force microscope (AFM) cantilever in the liquid environment is investigated. For this purpose, using Euler-Bernoulli beam theory and considering tip mass and hydrodynamic functions in a liquid environment, an expression for the resonance frequencies of AFM cantilever in liquid is derived. Then, based on this expression, the effect of the surface contact stiffness on the flexural mode of a rectangular AFM cantilever in fluid is investigated and compared with the case where the AFM cantilever operates in the air. The results show that in contrast with an air environment, the tip mass has no significant impact on the resonance frequency and sensitivity of the AFM cantilever in the liquid. Hence, analysis of AFM behaviour in liquid environment by neglecting the tip mass is logical. PMID:25562584

  13. Modeling the effect of engine assembly mass on engine friction and vehicle fuel economy

    NASA Astrophysics Data System (ADS)

    An, Feng; Stodolsky, Frank

    An analytical model is developed to estimate the impact of reducing engine assembly mass (the term engine assembly refers to the moving components of the engine system, including crankshafts, valve train, pistons, and connecting rods) on engine friction and vehicle fuel economy. The relative changes in frictional mean effective pressure and fuel economy are proportional to the relative change in assembly mass. These changes increase rapidly as engine speed increases. Based on the model, a 25% reduction in engine assembly mass results in a 2% fuel economy improvement for a typical mid-size passenger car over the EPA Urban and Highway Driving Cycles.

  14. Effects of mass layer imperfect bonding on the electrical impedance of a quartz crystal microbalance

    NASA Astrophysics Data System (ADS)

    Chen, YangYang; Wang, Ji; Du, JianKe; Yang, JiaShi

    2013-11-01

    We study electrically forced vibrations of a crystal plate of AT-cut quartz carrying a thin mass layer operating as a quartz crystal microbalance for mass sensing. The mass layer is imperfectly bonded to the crystal plate with their interface described by the so-called interface-slip model which allows a discontinuity of the tangential interface displacement. Mindlin's equations for piezoelectric plates are used. An analytical solution is obtained. The electrical impedance is calculated. The effects of an elastic interface and a viscoelastic interface are examined.

  15. Black hole mass measurements using ionized gas discs: systematic dust effects

    SciTech Connect

    Baes, Maarten

    2008-10-08

    Using detailed Monte Carlo radiative transfer simulations in realistic models for galactic nuclei, we investigate the influence of interstellar dust in ionized gas discs on the rotation curves and the resulting black hole mass measurements. We find that absorption and scattering by interstellar dust leaves the shape of the rotation curves basically unaltered, but slightly decreases the central slope of the rotation curves. As a result, the ''observed'' black hole masses are systematically underestimated by some 10 to 20% for realistic optical depths. We therefore argue that the systematic effect of dust attenuation should be taken into account when estimating SMBH masses using ionized gas kinematics.

  16. Countably QC-Approximating Posets

    PubMed Central

    Mao, Xuxin; Xu, Luoshan

    2014-01-01

    As a generalization of countably C-approximating posets, the concept of countably QC-approximating posets is introduced. With the countably QC-approximating property, some characterizations of generalized completely distributive lattices and generalized countably approximating posets are given. The main results are as follows: (1) a complete lattice is generalized completely distributive if and only if it is countably QC-approximating and weakly generalized countably approximating; (2) a poset L having countably directed joins is generalized countably approximating if and only if the lattice σc(L)op of all σ-Scott-closed subsets of L is weakly generalized countably approximating. PMID:25165730

  17. Sample-matrix effects in infrared laser neutral desorption, multiphoton-ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Beavis, R. C.; Lindner, J.; Grotemeyer, J.; Schlag, E. W.

    1988-05-01

    Sample-matrix effects in laser evaporation of intact neutral molecules (LEIM) prior to multiphoton ionization mass spectrometry (MUPI MS) are studied. The results show that a strong influence exists in adding matrix materials to the sample upon the desorption step. Using sugars as matrix leads to a suppression of pyrolysis products in small peptides by the laser desorption. As a result mass spectrometric signals due to the pyrolysis products are avoided.

  18. Thermal effects on mass detection sensitivity of carbon nanotube resonators in nonlinear oscillation regime

    NASA Astrophysics Data System (ADS)

    Kang, Dong-Keun; Yang, Hyun-Ik; Kim, Chang-Wan

    2015-11-01

    A mass sensor using a nano-resonator has high detection sensitivity, and mass sensitivity is higher with smaller resonators. Therefore, carbon nanotubes (CNTs) are the ultimate materials for these applications and have been actively studied. In particular, CNT-based nanomechanical devices may experience high temperatures that lead to thermal expansion and residual stress in devices, which affects the device reliability. In this letter, to demonstrate the influence of the temperature change (i.e., thermal effect) on the mass detection sensitivity of CNT-based mass sensor, dynamic analysis is carried out for a CNT resonator with thermal effects in both linear and nonlinear oscillation regimes. Based on the continuum mechanics model, the analytical solution method with an assumed deflection eigenmode is applied to solve the nonlinear differential equation which involves the von Karman nonlinear strain-displacement relation and the additional axial force associated with thermal effects. A thermal effect on the fundamental resonance behavior and resonance frequency shift due to adsorbed mas, i.e., mass detection sensitivity, is examined in high-temperature environment. Results indicate a valid improvement of fundamental resonance frequency by using nonlinear oscillation in a thermal environment. In both linear and nonlinear oscillation regimes, the mass detection sensitivity becomes worse due to the increasing of temperature in a high-temperature environment. The thermal effect on the detection sensitivity is less effective in the nonlinear oscillation regime. It is concluded that a temperature change of a mass sensor with a CNT-based resonator can be utilized to enhance the detection sensitivity depending on the CNT length, linear/nonlinear oscillation behaviors, and the thermal environment.

  19. A study of the effect of mass loading on the shock environment

    NASA Astrophysics Data System (ADS)

    Wang, Q. Z.; Lin, H. B.

    1984-06-01

    The weight variations in mounted subassemblies have relatively little effect on the pyrotechnic shock environment at the mounting point. This is the so-called mass loading effect. A mechanical model which attempts to explain theoretically the mechanism of the mass loading effect is given. A drop test and a structural striking test are conducted to simulate the pyrotechnic shock. The experimental results agree well with the predictions of the model analysis. A local and an entire body shock environment of a system and their shock test specifications are briefly discussed.

  20. The physical chemistry of mass-independent isotope effects and their observation in nature.

    PubMed

    Thiemens, Mark H; Chakraborty, Subrata; Dominguez, Gerardo

    2012-01-01

    Historically, the physical chemistry of isotope effects and precise measurements in samples from nature have provided information on processes that could not have been obtained otherwise. With the discovery of a mass-independent isotopic fractionation during the formation of ozone, a new physical chemical basis for isotope effects required development. Combined theoretical and experimental developments have broadened this understanding and extended the range of chemical systems where these unique effects occur. Simultaneously, the application of mass-independent isotopic measurements to an extensive range of both terrestrial and extraterrestrial systems has furthered the understanding of events such as solar system origin and evolution and planetary atmospheric chemistry, present and past. PMID:22475336

  1. Approximate analysis method for statistical properties of seismic response of secondary system

    SciTech Connect

    Aoki, Shigeru

    1996-12-01

    In this paper, effectiveness of a stationary approximation is examined. The mean square response and the first excursion probability of the secondary system such as pipings and mechanical equipment installed in the primary system such as building subjected to nonstationary random excitation are obtained. Results obtained by stationary approximation are compared with those obtained by nonstationary analysis for various values of damping ratio, natural period and mass ratio of the secondary system to the primary system.

  2. Mass attenuation coefficients, effective atomic numbers and effective electron densities for some polymers.

    PubMed

    Kucuk, Nil; Cakir, Merve; Isitman, Nihat Ali

    2013-01-01

    In this study, the total mass attenuation coefficients (μ(m)) for some homo- and hetero-chain polymers, namely polyamide-6 (PA-6), poly-methyl methacrylate (PMMA), low-density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS) were measured at 59.5, 511, 661.6, 1173.2, 1274.5 and 1332.5 keV photon energies. The samples were separately irradiated with (241)Am, (22)Na, (137)Cs and (60)Co (638 kBq) radioactive gamma sources. The measurements were made by performing transmission experiments with a 2″×2″ NaI(Tl) scintillation detector having an energy resolution of 7 % at 662 keV gamma ray from the decay of (137)Cs. The effective atomic numbers (Z(eff)) and the effective electron densities (N(eff)) were determined experimentally and theoretically using the obtained μ(m) values for the investigated samples. Furthermore, Z(eff) and N(eff) of each polymer were computed for total photon interaction cross-sections using theoretical data over a wide energy region from 1 keV to 10 MeV. The experimental values of the selected polymers were found to be in good agreement with the theoretical values. PMID:22645382

  3. Experimental investigation of added mass effects on a hydrofoil under cavitation conditions

    NASA Astrophysics Data System (ADS)

    De La Torre, O.; Escaler, X.; Egusquiza, E.; Farhat, M.

    2013-05-01

    The influence of leading edge sheet cavitation and supercavitation on the added mass effects experienced by a 2-D NACA0009 truncated hydrofoil has been experimentally investigated in a hydrodynamic tunnel. A non-intrusive excitation and measuring system based on piezoelectric patches mounted on the hydrofoil surface was used to determine the natural frequencies of the fluid-structure system. The appropriate hydrodynamic conditions were selected to generate a range of stable partial cavities of various sizes and also to minimize the effects of other sources of flow noise and vibrations. The main tests were performed for different sigma values under a constant flow velocity of 14m/s and for incident angles of both 1° and 2°. Additionally, a series of experiments in which the hydrofoil was submerged in air, partially and completely submerged in still water and without cavitation at 7 and 14m/s were also performed. The maximum added mass effect occurs with still water. When cavitation appears, the added mass decreases because the cavity length is increased, and the added mass is minimum for supercavitation. A linear correlation is found between the added mass coefficients and the entrained mass that accounts for the mean density of the cavity, its dimensions and its location relative to the specific mode shape deformation.

  4. Computer Experiments for Function Approximations

    SciTech Connect

    Chang, A; Izmailov, I; Rizzo, S; Wynter, S; Alexandrov, O; Tong, C

    2007-10-15

    This research project falls in the domain of response surface methodology, which seeks cost-effective ways to accurately fit an approximate function to experimental data. Modeling and computer simulation are essential tools in modern science and engineering. A computer simulation can be viewed as a function that receives input from a given parameter space and produces an output. Running the simulation repeatedly amounts to an equivalent number of function evaluations, and for complex models, such function evaluations can be very time-consuming. It is then of paramount importance to intelligently choose a relatively small set of sample points in the parameter space at which to evaluate the given function, and then use this information to construct a surrogate function that is close to the original function and takes little time to evaluate. This study was divided into two parts. The first part consisted of comparing four sampling methods and two function approximation methods in terms of efficiency and accuracy for simple test functions. The sampling methods used were Monte Carlo, Quasi-Random LP{sub {tau}}, Maximin Latin Hypercubes, and Orthogonal-Array-Based Latin Hypercubes. The function approximation methods utilized were Multivariate Adaptive Regression Splines (MARS) and Support Vector Machines (SVM). The second part of the study concerned adaptive sampling methods with a focus on creating useful sets of sample points specifically for monotonic functions, functions with a single minimum and functions with a bounded first derivative.

  5. A discussion of Cepheid masses

    NASA Technical Reports Server (NTRS)

    Cox, A. N.

    1980-01-01

    Masses and compositions of Cepheids are essential to map the places in the Hertzsprung-Russell diagram where various radial pulsation modes occur. Luminosity observations and stellar evolution theory give masses for Cepheids which range from 10 percent to a factor of four more than those given by pulsation theory. Combining the evolution and pulsation theories, a theoretical mass was determined using only the period and an approximate surface effective temperature. The ratio of the theoretical to evolutionary masses averaged 0.99 + or - 0.07 for 16 Cepheids.

  6. Effect of Coolant Temperature and Mass Flow on Film Cooling of Turbine Blades

    NASA Technical Reports Server (NTRS)

    Garg, Vijay K.; Gaugler, Raymond E.

    1997-01-01

    A three-dimensional Navier Stokes code has been used to study the effect of coolant temperature, and coolant to mainstream mass flow ratio on the adiabatic effectiveness of a film-cooled turbine blade. The blade chosen is the VKI rotor with six rows of cooling holes including three rows on the shower head. The mainstream is akin to that under real engine conditions with stagnation temperature = 1900 K and stagnation pressure = 3 MPa. Generally, the adiabatic effectiveness is lower for a higher coolant temperature due to nonlinear effects via the compressibility of air. However, over the suction side of shower-head holes, the effectiveness is higher for a higher coolant temperature than that for a lower coolant temperature when the coolant to mainstream mass flow ratio is 5% or more. For a fixed coolant temperature, the effectiveness passes through a minima on the suction side of shower-head holes as the coolant to mainstream mass flow, ratio increases, while on the pressure side of shower-head holes, the effectiveness decreases with increase in coolant mass flow due to coolant jet lift-off. In all cases, the adiabatic effectiveness is highly three-dimensional.

  7. Effect of a hypocaloric diet, increased protein intake and resistance training on lean mass gains and fat mass loss in overweight police officers.

    PubMed

    Demling, R H; DeSanti, L

    2000-01-01

    We compare the effects of a moderate hypocaloric, high-protein diet and resistance training, using two different protein supplements, versus hypocaloric diet alone on body compositional changes in overweight police officers. A randomized, prospective 12-week study was performed comparing the changes in body composition produced by three different treatment modalities in three study groups. One group (n = 10) was placed on a nonlipogenic, hypocaloric diet alone (80% of predicted needs). A second group (n = 14) was placed on the hypocaloric diet plus resistance exercise plus a high-protein intake (1.5 g/kg/day) using a casein protein hydrolysate. In the third group (n = 14) treatment was identical to the second, except for the use of a whey protein hydrolysate. We found that weight loss was approximately 2.5 kg in all three groups. Mean percent body fat with diet alone decreased from a baseline of 27 +/- 1.8 to 25 +/- 1.3% at 12 weeks. With diet, exercise and casein the decrease was from 26 +/- 1.7 to 18 +/- 1.1% and with diet, exercise and whey protein the decrease was from 27 +/- 1.6 to 23 +/- 1.3%. The mean fat loss was 2. 5 +/- 0.6, 7.0 +/- 2.1 and 4.2 +/- 0.9 kg in the three groups, respectively. Lean mass gains in the three groups did not change for diet alone, versus gains of 4 +/- 1.4 and 2 +/- 0.7 kg in the casein and whey groups, respectively. Mean increase in strength for chest, shoulder and legs was 59 +/- 9% for casein and 29 +/- 9% for whey, a significant group difference. This significant difference in body composition and strength is likely due to improved nitrogen retention and overall anticatabolic effects caused by the peptide components of the casein hydrolysate. PMID:10838463

  8. Effects of independently altering body weight and body mass on the metabolic cost of running.

    PubMed

    Teunissen, Lennart P J; Grabowski, Alena; Kram, Rodger

    2007-12-01

    The metabolic cost of running is substantial, despite the savings from elastic energy storage and return. Previous studies suggest that generating vertical force to support body weight and horizontal forces to brake and propel body mass are the major determinants of the metabolic cost of running. In the present study, we investigated how independently altering body weight and body mass affects the metabolic cost of running. Based on previous studies, we hypothesized that reducing body weight would decrease metabolic rate proportionally, and adding mass and weight would increase metabolic rate proportionally. Further, because previous studies show that adding mass alone does not affect the forces generated on the ground, we hypothesized that adding mass alone would have no substantial effect on metabolic rate. We manipulated the body weight and body mass of 10 recreational human runners and measured their metabolic rates while they ran at 3 m s(-1). We reduced weight using a harness system, increased mass and weight using lead worn about the waist, and increased mass alone using a combination of weight support and added load. We found that net metabolic rate decreased in less than direct proportion to reduced body weight, increased in slightly more than direct proportion to added load (added mass and weight), and was not substantially different from normal running with added mass alone. Adding mass alone was not an effective method for determining the metabolic cost attributable to braking/propelling body mass. Runners loaded with mass alone did not generate greater vertical or horizontal impulses and their metabolic costs did not substantially differ from those of normal running. Our results show that generating force to support body weight is the primary determinant of the metabolic cost of running. Extrapolating our reduced weight data to zero weight suggests that supporting body weight comprises at most 74% of the net cost of running. However, 74% is probably an

  9. Birthdate, mass and survival in mountain goat kids: effects of maternal characteristics and forage quality.

    PubMed

    Côté, S D; Festa-Bianchet, M

    2001-04-01

    In temperate environments, early-born ungulates may enjoy a longer growth period before winter, and so attain a higher body mass and an increased probability of survival compared to late-born ones. We assessed the effects of maternal characteristics, forage quality and population density on kid birthdate, mass and survival in a population of marked mountain goats (Oreamnos americanus) in Alberta. The duration and timing of the birth season were similar in all years. Births were highly synchronised: 80% of kids were born within 2 weeks of the first birth. Maternal age, maternal social rank and density did not affect kid birthdate or mass. Previous breeding experience was not related to kid birthdate, but kids born to pluriparous mothers were heavier during summer than kids born to primiparous mothers. Male and female kids had similar mass and accumulated mass linearly during summer. Early-born kids were heavier than late-born kids. Faecal crude protein (FCP) in late spring and maternal mass were positively related to kid mass. Survival to weaning appeared higher for males (90%) than for females (78%), but survival to 1 year was 65% for both sexes. FCP in late spring, density, birthdate and mass did not affect kid survival to weaning in either sex. Survival to 1 year increased with FCP in late spring for females, but not for males. Survival to 1 year was independent of birthdate for both sexes, but heavy females survived better than light ones. Multiple logistic regression revealed a positive effect of mass on survival to 1 year when the sexes were pooled. Our results suggest that mountain goats are constrained to give birth in a short birth season synchronised with forage productivity. PMID:24577654

  10. Apparent mass of the human body in the vertical direction: Effect of seat backrest

    NASA Astrophysics Data System (ADS)

    Toward, Martin G. R.; Griffin, Michael J.

    2009-11-01

    The transmission of vibration through a seat depends on various characteristics of the seat and the dynamic response of the human body. The dynamic response of the body can be represented by its apparent mass, but the effect of the seat on the apparent mass of the body is not well understood. This study was designed to quantify the effect of foam and rigid backrests on the vertical apparent mass of the human measured at the seat surface supporting the body. The apparent masses of 12 subjects were measured during exposure to random vertical vibration (1.0 ms -2 rms from 0.125 to 40 Hz) in a seat with a rigid backrest, in the same rigid seat with three thicknesses of foam backrest (50, 100 and 150 mm), and in the same seat with no backrest. The backrests were inclined at various angles: 0°, 5°, 10°, 15°, 20°, 25° and 30° for the rigid and 100 mm foam backrests, and 0°, 10°, 20° and 30° for the 50 and 150 mm foam backrests. With all vertical backrests (i.e., 0° inclination), there were resonances in the apparent mass of the body around 5 and 10 Hz. With no backrest, the apparent mass was increased at frequencies less than the resonance frequency but decreased at frequencies between 8 and 20 Hz, relative to the apparent mass with the vertical rigid and foam backrests. With the rigid backrest, the primary resonance frequencies in the apparent mass increased with increasing backrest inclination. With the foam backrests, the resonance frequencies decreased with increasing backrest inclination. At frequencies less than the primary resonance, the apparent mass decreased with increasing backrest inclination, particularly with the rigid backrest. Between 8 and 15 Hz, the apparent mass decreased with increasing inclination, most notably with the foam backrests. At inclinations less than 30°, there was little effect of foam thickness on the apparent mass, but at 30° an increase in the thickness of the foam decreased the frequency of the first resonances. Since

  11. The effects of layers in dry snow on its passive microwave emissions using dense media radiative transfer theory based on the quasicrystalline approximation (QCA/DMRT)

    USGS Publications Warehouse

    Liang, D.; Xu, X.; Tsang, L.; Andreadis, K.M.; Josberger, E.G.

    2008-01-01

    A model for the microwave emissions of multilayer dry snowpacks, based on dense media radiative transfer (DMRT) theory with the quasicrystalline approximation (QCA), provides more accurate results when compared to emissions determined by a homogeneous snowpack and other scattering models. The DMRT model accounts for adhesive aggregate effects, which leads to dense media Mie scattering by using a sticky particle model. With the multilayer model, we examined both the frequency and polarization dependence of brightness temperatures (Tb's) from representative snowpacks and compared them to results from a single-layer model and found that the multilayer model predicts higher polarization differences, twice as much, and weaker frequency dependence. We also studied the temporal evolution of Tb from multilayer snowpacks. The difference between Tb's at 18.7 and 36.5 GHz can be S K lower than the single-layer model prediction in this paper. By using the snowpack observations from the Cold Land Processes Field Experiment as input for both multi- and single-layer models, it shows that the multilayer Tb's are in better agreement with the data than the single-layer model. With one set of physical parameters, the multilayer QCA/DMRT model matched all four channels of Tb observations simultaneously, whereas the single-layer model could only reproduce vertically polarized Tb's. Also, the polarization difference and frequency dependence were accurately matched by the multilayer model using the same set of physical parameters. Hence, algorithms for the retrieval of snowpack depth or water equivalent should be based on multilayer scattering models to achieve greater accuracy. ?? 2008 IEEE.

  12. Approximation by hinge functions

    SciTech Connect

    Faber, V.

    1997-05-01

    Breiman has defined {open_quotes}hinge functions{close_quotes} for use as basis functions in least squares approximations to data. A hinge function is the max (or min) function of two linear functions. In this paper, the author assumes the existence of smooth function f(x) and a set of samples of the form (x, f(x)) drawn from a probability distribution {rho}(x). The author hopes to find the best fitting hinge function h(x) in the least squares sense. There are two problems with this plan. First, Breiman has suggested an algorithm to perform this fit. The author shows that this algorithm is not robust and also shows how to create examples on which the algorithm diverges. Second, if the author tries to use the data to minimize the fit in the usual discrete least squares sense, the functional that must be minimized is continuous in the variables, but has a derivative which jumps at the data. This paper takes a different approach. This approach is an example of a method that the author has developed called {open_quotes}Monte Carlo Regression{close_quotes}. (A paper on the general theory is in preparation.) The author shall show that since the function f is continuous, the analytic form of the least squares equation is continuously differentiable. A local minimum is solved for by using Newton`s method, where the entries of the Hessian are estimated directly from the data by Monte Carlo. The algorithm has the desirable properties that it is quadratically convergent from any starting guess sufficiently close to a solution and that each iteration requires only a linear system solve.

  13. Negative mass

    NASA Astrophysics Data System (ADS)

    Hammond, Richard T.

    2015-03-01

    Some physical aspects of negative mass are examined. Several unusual properties, such as the ability of negative mass to penetrate any armor, are analysed. Other surprising effects include the bizarre system of negative mass chasing positive mass, naked singularities and the violation of cosmic censorship, wormholes, and quantum mechanical results as well. In addition, a brief look into the implications for strings is given.

  14. Quantum tunneling beyond semiclassical approximation

    NASA Astrophysics Data System (ADS)

    Banerjee, Rabin; Ranjan Majhi, Bibhas

    2008-06-01

    Hawking radiation as tunneling by Hamilton-Jacobi method beyond semiclassical approximation is analysed. We compute all quantum corrections in the single particle action revealing that these are proportional to the usual semiclassical contribution. We show that a simple choice of the proportionality constants reproduces the one loop back reaction effect in the spacetime, found by conformal field theory methods, which modifies the Hawking temperature of the black hole. Using the law of black hole mechanics we give the corrections to the Bekenstein-Hawking area law following from the modified Hawking temperature. Some examples are explicitly worked out.

  15. Hall and radial magnetic field effects on radiative peristaltic flow of Carreau-Yasuda fluid in a channel with convective heat and mass transfer

    NASA Astrophysics Data System (ADS)

    Hayat, T.; Farooq, S.; Alsaedi, A.; Ahmad, B.

    2016-08-01

    The purpose of present investigation is to study the Hall and MHD effects on peristaltic flow of Carreau-Yasuda fluid in a convectively curved configuration. Thermal radiation, Soret and Dufour effects are also accounted. The channel walls comprised the no slip and compliant properties. Constitutive equations for mass, momentum, energy and concentration are first modeled in view of considered assumptions and then simplified under long wavelength and low Reynolds number approximation. Solution of the resulting system of equations is carried out via a regular perturbation technique. Physical behaviors of velocity, temperature, concentration and streamlines are discussed with the help of graphical representation.

  16. Effect of enhanced manganese oxidation in the hyporheic zone on basin-scale geochemical mass balance

    NASA Astrophysics Data System (ADS)

    Harvey, Judson W.; Fuller, Christopher C.

    1998-04-01

    hyporheic exchange in Pinal Creek basin was to remove approximately 20% of the dissolved manganese flowing out of the drainage basin. Our results illustrate that the cumulative significance of reactive uptake in the hyporheic zone depends on the balance between chemical reaction rates, hyporheic porewater residence time, and turnover of streamflow through hyporheic flow paths. The similarity between the hyporheic reaction timescale (1/λs ≈ 1.3 hours), and the hyporheic porewater residence timescale (ts ≈ 8 min) ensured that there was adequate time for the reaction to progress. Furthermore, it was the similarity between the turnover length for stream water flow through hyporheic flow paths (Ls = stream velocity/storage-zone exchange coefficient ≈ 1.3 km) and the length of Pinal Creek (L ≈ 7 km), which ensured that all stream water passed through hyporheic flow paths several times. As a means to generalize our findings to other sites where similar types of hydrologic and chemical information are available, we suggest a cumulative significance index for hyporheic reactions, Rs = λstsL/Ls (dimensionless); higher values indicate a greater potential for hyporheic reactions to influence geochemical mass balance. Our experience in Pinal Creek basin suggests that values of Rs > 0.2 characterize systems where hyporheic reactions are likely to influence geochemical mass balance at the drainage-basin scale.

  17. Effect of enhanced manganese oxidation in the hyporheic zone on basin-scale geochemical mass balance

    USGS Publications Warehouse

    Harvey, J.W.; Fuller, C.C.

    1998-01-01

    cumulative effect of hyporheic exchange in Pinal Creek basin was to remove approximately 20% of the dissolved manganese flowing out of the drainage basin. Our results illustrate that the cumulative significance of reactive uptake in the hyporheic zone depends on the balance between chemical reaction rates, hyporheic porewater residence time, and turnover of streamflow through hyporheic flow paths. The similarity between the hyporheic reaction timescale (1??(s) ??? 1.3 hours), and the hyporheic porewater residence timescale (t(s) ??? 8 min) ensured that there was adequate time for the reaction to progress. Furthermore, it was the similarity between the turnover length for stream water flow through hyporheic flow paths (L(s) = stream velocity/storage-zone exchange coefficient ??? 1.3 km) and the length of Pinal Creek (L ??? 7 km), which ensured that all stream water passed through hyporheic flow paths several times. As a means to generalize our findings to other sites where similar types of hydrologic and chemical information are available, we suggest a cumulative significance index for hyporheic reactions, R(s) = ??(s)t(s)L/L(s) (dimensionless); higher values indicate a greater potential for hyporheic reactions to influence geochemical mass balance. Our experience in Pinal Creek basin suggests that values of R(s) > 0.2 characterize systems where hyporheic reactions are likely to influence geochemical mass balance at the drainage-basin scale.

  18. Effects of varying gravity levels in parabolic flight on the size-mass illusion.

    PubMed

    Clément, Gilles

    2014-01-01

    When an observer lifts two objects with the same weight but different sizes, the smaller object is consistently reported to feel heavier than the larger object even after repeated trials. Here we explored the effect of reduced and increased gravity on this perceptual size-mass illusion. Experiments were performed on board the CNES Airbus A300 Zero-G during parabolic flights eliciting repeated exposures to short periods of zero g, 0.16 g, 0.38 g, one g, and 1.8 g. Subjects were asked to assess perceived heaviness by actively oscillating objects with various sizes and masses. The results showed that a perceptual size-mass illusion was clearly present at all gravity levels. During the oscillations, the peak arm acceleration varied as a function of the gravity level, irrespective of the mass and size of the objects. In other words we did not observe a sensorimotor size-mass illusion. These findings confirm dissociation between the sensorimotor and perceptual systems for determining object mass. In addition, they suggest that astronauts on the Moon or Mars with the eyes closed will be able to accurately determine the relative difference in mass between objects. PMID:24901519

  19. Effects of Varying Gravity Levels in Parabolic Flight on the Size-Mass Illusion

    PubMed Central

    Clément, Gilles

    2014-01-01

    When an observer lifts two objects with the same weight but different sizes, the smaller object is consistently reported to feel heavier than the larger object even after repeated trials. Here we explored the effect of reduced and increased gravity on this perceptual size-mass illusion. Experiments were performed on board the CNES Airbus A300 Zero-G during parabolic flights eliciting repeated exposures to short periods of zero g, 0.16 g, 0.38 g, one g, and 1.8 g. Subjects were asked to assess perceived heaviness by actively oscillating objects with various sizes and masses. The results showed that a perceptual size-mass illusion was clearly present at all gravity levels. During the oscillations, the peak arm acceleration varied as a function of the gravity level, irrespective of the mass and size of the objects. In other words we did not observe a sensorimotor size-mass illusion. These findings confirm dissociation between the sensorimotor and perceptual systems for determining object mass. In addition, they suggest that astronauts on the Moon or Mars with the eyes closed will be able to accurately determine the relative difference in mass between objects. PMID:24901519

  20. Effects of body mass and water temperature on routine metabolism of American paddlefish Polyodon spathula.

    PubMed

    Patterson, J T; Mims, S D; Wright, R A

    2013-04-01

    This study quantified the effects of temperature and fish mass on routine metabolism of the American paddlefish Polyodon spathula. Thermal sensitivity, as measured by Q(10) value, was low in P. spathula. Mean Q(10) was 1·78 while poikilotherms are generally expected to have Q(10) values in the 2·00-2·50 range. Mass-specific metabolism did not decrease with increased fish size to the extent that this phenomenon is observed in teleosts, as evidenced by a mass exponent (β) value of 0·92 for P. spathula compared with 0·79 in a review of teleost species. Other Acipenseriformes have exhibited relatively high β values for mass-specific respiration. Overall P. spathula metabolism appears to be more dependent on body mass and less dependent on temperature than for many other fishes. An equation utilizing temperature and fish mass to estimate gross respiration for P. spathula was derived and this equation was applied to respiratory data from other Acipenseriformes to assess inter-species variation. Polyodon spathula respiration rates across water temperature and fish mass appear most similar to those of Atlantic sturgeon Acipenser naccarii and white sturgeon Acipenser transmontanus. PMID:23557305

  1. A mass-independent sulfur isotope effect in the nonthermal formation

    NASA Technical Reports Server (NTRS)

    Bains-Sahota, Swroop K.; Thiemens, Mark H.

    1989-01-01

    A nonmass-dependent sulfur isotope effect is present in the rotationally symmetric S2F10 molecule, produced in an electrical discharge through sulfur tetrafluoride. A similar isotopic fractionation was observed in the product S2F10 from the electrodissociation of SF5Cl and in the reaction between fluorine atoms produced by F2 photolysis and SF2, collectively ruling out the SF5 formation process as the source of the mass-independent fractionation. The secondary dissociation of S2F10 as a source of the mass-independent fractionation is ruled out by control S2F10 dissociation experiments which are shown to produce small mass-dependent fractionations. Mass-dependent effects such as sulfur isotopic exchange and secondary dissociation reactions are significant processes for the system under study, and have been quantitatively accounted for. The role of symmetry in nonmass-dependent isotope effects is strengthened by the present experiments, and the search and characterization of mass-independent effects is extended to sulfur-containing molecules.

  2. Meson effective mass in the isospin medium in hard-wall AdS/QCD model

    NASA Astrophysics Data System (ADS)

    Mamedov, Shahin

    2016-02-01

    We study a mass splitting of the light vector, axial-vector, and pseudoscalar mesons in the isospin medium in the framework of the hard-wall model. We write an effective mass definition for the interacting gauge fields and scalar field introduced in gauge field theory in the bulk of AdS space-time. Relying on holographic duality we obtain a formula for the effective mass of a boundary meson in terms of derivative operator over the extra bulk coordinate. The effective mass found in this way coincides with the one obtained from finding of poles of the two-point correlation function. In order to avoid introducing distinguished infrared boundaries in the quantization formula for the different mesons from the same isotriplet we introduce extra action terms at this boundary, which reduces distinguished values of this boundary to the same value. Profile function solutions and effective mass expressions were found for the in-medium ρ , a_1, and π mesons.

  3. Multiple vantage points on the mental health effects of mass shootings.

    PubMed

    Shultz, James M; Thoresen, Siri; Flynn, Brian W; Muschert, Glenn W; Shaw, Jon A; Espinel, Zelde; Walter, Frank G; Gaither, Joshua B; Garcia-Barcena, Yanira; O'Keefe, Kaitlin; Cohen, Alyssa M

    2014-09-01

    The phenomenon of mass shootings has emerged over the past 50 years. A high proportion of rampage shootings have occurred in the United States, and secondarily, in European nations with otherwise low firearm homicide rates; yet, paradoxically, shooting massacres are not prominent in the Latin American nations with the highest firearm homicide rates in the world. A review of the scientific literature from 2010 to early 2014 reveals that, at the individual level, mental health effects include psychological distress and clinically significant elevations in posttraumatic stress, depression, and anxiety symptoms in relation to the degree of physical exposure and social proximity to the shooting incident. Psychological repercussions extend to the surrounding affected community. In the aftermath of the deadliest mass shooting on record, Norway has been in the vanguard of intervention research focusing on rapid delivery of psychological support and services to survivors of the "Oslo Terror." Grounded on a detailed review of the clinical literature on the mental health effects of mass shootings, this paper also incorporates wide-ranging co-author expertise to delineate: 1) the patterning of mass shootings within the international context of firearm homicides, 2) the effects of shooting rampages on children and adolescents, 3) the psychological effects for wounded victims and the emergency healthcare personnel who care for them, 4) the disaster behavioral health considerations for preparedness and response, and 5) the media "framing" of mass shooting incidents in relation to the portrayal of mental health themes. PMID:25085235

  4. Geometry of the effective Majorana neutrino mass in the 0νββ decay

    NASA Astrophysics Data System (ADS)

    Xing, Zhi-zhong; Zhou, Ye-Ling

    2015-01-01

    The neutrinoless double-beta (0νββ) decay is a unique process used to identify the Majorana nature of massive neutrinos, and its rate depends on the size of the effective Majorana neutrino mass ee. We put forward a novel ‘coupling-rod’ diagram to describe ee in the complex plane, by which the effects of the neutrino mass ordering and CP-violating phases on ee are intuitively understood. We show that this geometric language allows us to easily obtain the maximum and minimum of |ee|. It remains usable even if there is a kind of new physics contributing to ee, and it can also be extended to describe the effective Majorana masses eμ, eτ, μτ and ττ which may appear in some other lepton-number violating processes.

  5. Positive and negative effective mass of classical particles in oscillatory and static fields.

    PubMed

    Dodin, I Y; Fisch, N J

    2008-03-01

    A classical particle oscillating in an arbitrary high-frequency or static field effectively exhibits a modified rest mass m(eff) derived from the particle averaged Lagrangian. Relativistic ponderomotive and diamagnetic forces, as well as magnetic drifts, are obtained from the m(eff) dependence on the guiding center location and velocity. The effective mass is not necessarily positive and can result in backward acceleration when an additional perturbation force is applied. As an example, adiabatic dynamics with m||>0 and m||<0 is demonstrated for a wave-driven particle along a dc magnetic field, m|| being the effective longitudinal mass derived from m(eff). Multiple energy states are realized in this case, yielding up to three branches of m|| for a given magnetic moment and parallel velocity. PMID:18517528

  6. First-principle study of the electronic band structure and the effective mass of the ternary alloy GaxIn1-xP

    NASA Astrophysics Data System (ADS)

    Yang, H. Q.; Song, T. L.; Liang, X. X.; Zhao, G. J.

    2015-01-01

    In this work, the electronic band structure and the effective mass of the ternary alloy GaxIn1-xP are studied by the first principle calculations. The software QUANTUM ESPRESSO and the generalized gradient approximation (GGA) for the exchange correlations have been used in the calculations. We calculate the lattice parameter, band gap and effective mass of the ternary alloy GaxIn1-xP for the Ga composition x varying from 0.0 to 1.0 by the step of 0.125. The effect of the Ga composition on the lattice parameter and the electronic density of states are discussed. The results show that the lattice parameter varies with the composition almost linearly following the Vegard's law. A direct-to-indirect band-gap crossover is found to occur close to x = 0.7. The effective masses are also calculated at Γ(000) high symmetry point along the [100] direction. The results show that the band gap and the electron effective mass vary nonlinearly with composition x.

  7. The effect of active galactic nuclei feedback on the halo mass function

    NASA Astrophysics Data System (ADS)

    Cui, Weiguang; Borgani, Stefano; Murante, Giuseppe

    2014-06-01

    We investigate baryon effects on the halo mass function (HMF), with emphasis on the role played by active galactic nuclei (AGN) feedback. Haloes are identified with both friends-of-friends (FoF) and spherical overdensity (SO) algorithms. We embed the standard SO algorithm into a memory-controlled frame program and present the Python spherIcAl Overdensity code - PIAO (Chinese character: ). For both FoF and SO haloes, the effect of AGN feedback is that of suppressing the HMFs to a level even below that of dark matter (DM) simulations. The ratio between the HMFs in the AGN and in the DM simulations is ˜0.8 at overdensity Δc = 500, a difference that increases at higher overdensity Δc = 2500, with no significant redshift and mass dependence. A decrease of the halo masses ratio with respect to the DM case induces the decrease of the HMF in the AGN simulation. The shallower inner density profiles of haloes in the AGN simulation witnesses that mass reduction is induced by the sudden displacement of gas induced by thermal AGN feedback. We provide fitting functions to describe halo mass variations at different overdensities, which can recover the HMFs with a residual random scatter ≲5 per cent for halo masses larger than 1013 h-1 M⊙.

  8. Binary black hole evolutions of approximate puncture initial data

    SciTech Connect

    Bode, Tanja; Laguna, Pablo; Shoemaker, Deirdre M.; Hinder, Ian; Herrmann, Frank; Vaishnav, Birjoo

    2009-07-15

    Approximate solutions to the Einstein field equations are valuable tools to investigate gravitational phenomena. An important aspect of any approximation is to investigate and quantify its regime of validity. We present a study that evaluates the effects that approximate puncture initial data, based on skeleton solutions to the Einstein constraints as proposed by [G. Faye, P. Jaranowski, and G. Schaefer, Phys. Rev. D 69, 124029 (2004).], have on numerical evolutions. Using data analysis tools, we assess the effectiveness of these constraint-violating initial data for both initial and advanced LIGO and show that the matches of waveforms from skeleton data with the corresponding waveforms from constraint-satisfying initial data are > or approx. 0.97 when the total mass of the binary is > or approx. 40M{sub {center_dot}}. In addition, we demonstrate that the differences between the skeleton and the constraint-satisfying initial data evolutions, and thus waveforms, are due to negative Hamiltonian constraint violations present in the skeleton initial data located in the vicinity of the punctures. During the evolution, the skeleton data develops both Hamiltonian and momentum constraint violations that decay with time, with the binary system relaxing to a constraint-satisfying solution with black holes of smaller mass and thus different dynamics.

  9. Peak acceleration during impact with helmet materials: effects of impactor mass and speed.

    PubMed

    Hutchinson, Timothy Paul

    2014-01-01

    The impact properties of six foam materials used for energy absorption as the liner of children's helmets, reported by Gimbel and Hoshizaki are considered further. In high-energy impacts, almost complete compression of the energy-absorbing material (bottoming out) may occur, and the severity of the impact increases greatly. Too soft a material means bottoming out occurs at low speeds, but if it is too stiff, the material itself is injurious. The fitting of equations to results in 'no bottoming out' and 'bottoming out' conditions may help assessment of what compromise is appropriate. The equations in this article correspond to peak acceleration being proportional to power functions of impactor speed and mass. 1. When there was no bottoming out, peak acceleration was found to be proportional to m (∧)(c-1).v (∧)(2c), with c being approximately 0.25. 2. For bottoming out, peak acceleration was found to be proportional to m (∧)(p).v (∧)(q), with p and q being approximately 2 and approximately 3. 3. The constants of proportionality were related to material density in a regular way. PMID:24444232

  10. Mass flow meter using the triboelectric effect for measurement in cryogenics

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Henry; Cunningham, Jock; Wolff, Steve

    1987-01-01

    The use of triboelectric charge to measure the mass flow rate of cryogens for the Space Shuttle Main Engine was investigated. Cross correlation of the triboelectric charge signals was used to determine the transit time of the cryogen between two sensor locations in a .75-in tube. The ring electrode sensors were mounted in a removable spool piece. Three spool pieces were constructed for delivery, each with a different design. One set of electronics for implementation of the cross correlation and flow calculation was constructed for delivery. Tests were made using a laboratory flow loop using liquid freon and transformer oil. The measured flow precision was 1 percent and the response was linear. The natural frequency distribution of the triboelectric signal was approximately 1/f. The sensor electrodes should have an axial length less than approximately one/tenth pipe diameter. The electrode spacing should be less than approximately one pipe diameter. Tests using liquid nitrogen demonstrated poor tribo-signal to noise ratio. Most of the noise was microphonic and common to both electrode systems. The common noise rejection facility of the correlator was successful in compensating for this noise but the signal was too small to enable reliable demonstration of the technique in liquid nitrogen.

  11. The nucleon and Delta-resonance masses in relativistic chiral effective-field theory

    SciTech Connect

    V. Pascalutsa; M. Vanderhaeghen

    2005-11-28

    We study the chiral behavior of the nucleon and De-isobar masses within a manifestly covariant chiral effective-field theory, consistent with the analyticity principle. We compute the {pi} N and {pi}{Delta} one-loop contributions to the mass and field-normalization constant, and find that they can be described in terms of universal relativistic loop functions, multiplied by appropriate spin, isospin and coupling constants. We show that these relativistic one-loop corrections, when properly renormalized, obey the chiral power-counting and vanish in the chiral limit. The results including only the {pi} N-loop corrections compare favorably with the lattice QCD data for the pion-mass dependence of the nucleon and De masses, while inclusion of the {pi}/De loops tends to spoil this agreement.

  12. The effect of cellulose molar mass on the properties of palmitate esters.

    PubMed

    Willberg-Keyriläinen, Pia; Talja, Riku; Asikainen, Sari; Harlin, Ali; Ropponen, Jarmo

    2016-10-20

    Nowadays one of the growing trends is to replace oil-based products with cellulose-based materials. Currently most cellulose esters require a huge excess of chemicals and have therefore, not been broadly used in the industry. Here, we show that decreasing the molar mass of cellulose by ozone hydrolysis provides cellulose functionalization with less chemical consumption. To reveal the differences in reactivity and chemical consumption, we showed esterification of both native cellulose and ozone treated hydrolyzed cellulose. Based on the results, the molar mass of the starting cellulose has a significant effect on the end product's degree of substitution and properties. Furthermore, molar mass controlled palmitate esters form mechanically strong, flexible and optically transparent films with excellent water barrier properties. We anticipate that molar mass controlled cellulose will provide a starting point for the greater use of cellulose based materials, in various application, such as films and composites. PMID:27474646

  13. Effects of Tip Mass on Stability of Rotating Cantilever Pipe Conveying Fluid with Crack

    NASA Astrophysics Data System (ADS)

    Son, In Soo; Yoon, Han Ik; Lee, Sang Pil; Kim, Dong Jin

    In this paper, the dynamic stability of a rotating cantilever pipe conveying fluid with a crack and tip mass is investigated by numerical method. That is, the effects of the rotating the rotating angular velocity, the mass ratio, the crack and tip mass on the critical flow velocity for flutter instability of system are studied. The equations of motion of rotating pipe are derived by using the extended Hamilton's principle. The crack section of pipe is represented by a local flexibility matrix connecting two undamaged pipe segments. The crack is assumed to be in the first mode of fracture and always opened during the vibrations. Finally, the stability maps of the cracked rotating pipe system as a rotating angular velocity and mass ratio β are presented.

  14. On the nucleon effective mass role to the high energy proton spallation reactions

    NASA Astrophysics Data System (ADS)

    Santos, B. M.; Pinheiro, A. R. C.; Gonçalves, M.; Duarte, S. B.; Cabral, R. G.

    2016-04-01

    We explore the effect of the nucleon effective mass to the dynamic evolution of the rapid phase of proton-nucleus spallation reactions. The analysis of the relaxation time for the non-equilibrium phase is studied by variations in the effective mass parameter. We determine the final excitation energy of the hot residual nucleus at the end of cascade phase and the de-excitation of the nuclear system is carried out considering the competition of particle evaporation and fission processes. It was shown that the excitation energy depends of the hot compound residual nucleus at the end of the rapid phase on the changing effective mass. The multiplicity of particles was also analyzed in cascade and evaporation phase of the reaction. The use of nucleon effective mass during cascade phase can be considered as an effect of the many-body nuclear interactions not included explicitly in a treatment to the nucleon-nucleon interaction inside the nucleus. This procedure represents a more realistic scenario to obtain the neutron multiplicity generated in this reaction, which is a benchmark for the calculation of the neutronic in the ADS reactors.

  15. The Effect of Halo Mass on the H I Content of Galaxies in Groups and Clusters

    NASA Astrophysics Data System (ADS)

    Yoon, Ilsang; Rosenberg, Jessica L.

    2015-10-01

    We combine data from the Sloan Digital Sky Survey (SDSS) and the Arecibo Legacy Fast ALFA Survey (ALFALFA) to study the cold atomic gas content of galaxies in groups and clusters in the local universe. A careful cross-matching of galaxies in the SDSS, ALFALFA, and SDSS group catalogs provides a sample of group galaxies with stellar masses {10}8.4{M}⊙ ≤slant {M}*≤slant {10}10.6{M}⊙ and group halo masses {10}12.5{h}-1{M}⊙ ≤slant {M}h≤slant {10}15.0{h}-1{M}⊙ . Controlling our sample in stellar mass and redshift, we find no significant radial variation in the galaxy H i gas-to-stellar mass ratio for the halo mass range in our sample. However, the fraction of galaxies detected in ALFALFA declines steadily toward the centers of groups, with the effect being most prominent in the most massive halos. In the outskirts of massive halos a hint of a depressed detection fraction for low-mass galaxies suggests pre-processing that decreases the H i in these galaxies before they fall into massive clusters. We interpret the decline in the ALFALFA detection of galaxies in the context of a threshold halo mass for ram pressure stripping for a given galaxy stellar mass. The lack of an observable decrease in the galaxy H i gas-to-stellar mass ratio with the position of galaxies within groups and clusters highlights the difficulty of detecting the impact of environment on the galaxy H i content in a shallow H i survey.

  16. The Effect of Halo Mass on the H I Content of Galaxies in Groups and Clusters

    NASA Astrophysics Data System (ADS)

    Yoon, Ilsang; Rosenberg, Jessica L.

    2015-10-01

    We combine data from the Sloan Digital Sky Survey (SDSS) and the Arecibo Legacy Fast ALFA Survey (ALFALFA) to study the cold atomic gas content of galaxies in groups and clusters in the local universe. A careful cross-matching of galaxies in the SDSS, ALFALFA, and SDSS group catalogs provides a sample of group galaxies with stellar masses {10}8.4{M}ȯ ≤slant {M}*≤slant {10}10.6{M}ȯ and group halo masses {10}12.5{h}-1{M}ȯ ≤slant {M}h≤slant {10}15.0{h}-1{M}ȯ . Controlling our sample in stellar mass and redshift, we find no significant radial variation in the galaxy H i gas-to-stellar mass ratio for the halo mass range in our sample. However, the fraction of galaxies detected in ALFALFA declines steadily toward the centers of groups, with the effect being most prominent in the most massive halos. In the outskirts of massive halos a hint of a depressed detection fraction for low-mass galaxies suggests pre-processing that decreases the H i in these galaxies before they fall into massive clusters. We interpret the decline in the ALFALFA detection of galaxies in the context of a threshold halo mass for ram pressure stripping for a given galaxy stellar mass. The lack of an observable decrease in the galaxy H i gas-to-stellar mass ratio with the position of galaxies within groups and clusters highlights the difficulty of detecting the impact of environment on the galaxy H i content in a shallow H i survey.

  17. The effect of center-of-mass motion on photon statistics

    SciTech Connect

    Zhang, Yang; Zhang, Jun; Wu, Shao-xiong; Yu, Chang-shui

    2015-10-15

    We analyze the photon statistics of a weakly driven cavity quantum electrodynamics system and discuss the effects of photon blockade and photon-induced tunneling by effectively utilizing instead of avoiding the center-of-mass motion of a two-level atom trapped in the cavity. With the resonant interaction between atom, photon and phonon, it is shown that the bunching and anti-bunching of photons can occur with properly driving frequency. Our study shows the influence of the imperfect cooling of atom on the blockade and provides an attempt to take advantage of the center-of-mass motion.

  18. Effect of laminar and turbulent fluid flow on mass transfer in some electrochemical systems

    NASA Astrophysics Data System (ADS)

    Chen, Qian

    2000-10-01

    The influence of fluid flow on electrode-shape change that results from electrodeposition in the presence of a model leveling agent is simulated and discussed. The treatment is more rigorous than past studies in that flow and concentration fields are recalculated as the electrode shape changes. It is shown that uncertainties due to approximate treatments of fluid flow may be as significant as existing discrepancies between experiment and theory. The mass transfer characteristics of a turbulent slot jet impinging normally on a target wall are examined using numerical simulations. Fluid flow is modeled using the k-turbulence model of Wilcox [1]. The computations are validated against existing experimental fluid flow, heat transfer and mass transfer data. The range of Reynolds numbers examined is from 450 to 20,000 with Prandtl or Schmidt numbers from 1 to 2,400. The distance of the target plate from the slot jet varies between 2 to 8 times the slot jet width. The study reveals computational aspects that are unique to the solution of flow and mass transfer problems with the combination of high Schmidt numbers and turbulent flows. A low order "coherent structure" near-wall flow model first proposed by Chapman and Kuhn [2] is used to obtain the near-wall fluid flow field. This flow field is then used to compute high Schmidt number mass transfer for a turbulent boundary layer flow. It is shown that useful insight can be obtained into high Schmidt number mass transfer for a turbulent fluid flow using this model. The boundary conditions for this near-wall field for more complicated flow or geometries may be obtained either from experimental turbulent velocity and frequency data or from a k-o type of turbulence model.

  19. Effect of mass ratio on fluid induced motions of a circular cylinder with strips

    NASA Astrophysics Data System (ADS)

    Vinod, Ashwin; Banerjee, Arindam

    2014-11-01

    The objective of the current experimental work is to investigate the effects of mass ratio on Fluid Induced Motions, such as vortex induced vibration (VIV) and galloping, of elastically mounted circular cylinders attached with strips to their outer surface. Although the effect of mass ratio on VIV of a smooth circular cylinder is well documented in literature, however, their effects on circular cylinders with strips, capable of inciting galloping oscillations haven't been investigated and could have potential applications in the domain of vibration based energy harvesters. In the current work, three different mass ratios were tested, out of which, one falls below the critical mass in vortex induced vibration of a circular cylinder. The strips used for the experiments included sandpaper strips of prescribed roughness and smooth strips with no roughness, both of which served as surface protrusion based mechanisms of altering the flow around the cylinder. Interesting variations were observed in the amplitude, frequency response and the power spectrum, depending on the mass ratio of the oscillating system tested. The authors acknowledge support of the Office of Naval Research (Grant # ONR-000141210495 - Dr. Ron Joslin).

  20. Fluidic oscillator-mediated microbubble generation to provide cost effective mass transfer and mixing efficiency to the wastewater treatment plants.

    PubMed

    Rehman, Fahad; Medley, Gareth J D; Bandulasena, Hemaka; Zimmerman, William B J

    2015-02-01

    Aeration is one of the most energy intensive processes in the waste water treatment plants and any improvement in it is likely to enhance the overall efficiency of the overall process. In the current study, a fluidic oscillator has been used to produce microbubbles in the order of 100 μm in diameter by oscillating the inlet gas stream to a pair of membrane diffusers. Volumetric mass transfer coefficient was measured for steady state flow and oscillatory flow in the range of 40-100l/min. The highest improvement of 55% was observed at the flow rates of 60, 90 and 100l/min respectively. Standard oxygen transfer rate and efficiency were also calculated. Both standard oxygen transfer rate and efficiency were found to be considerably higher under oscillatory air flow conditions compared to steady state airflow. The bubble size distributions and bubble densities were measured using an acoustic bubble spectrometer and confirmed production of monodisperse bubbles with approximately 100 μm diameters with fluidic oscillation. The higher number density of microbubbles under oscillatory flow indicated the effect of the fluidic oscillation in microbubble production. Visual observations and dissolved oxygen measurements suggested that the bubble cloud generated by the fluidic oscillator was sufficient enough to provide good mixing and to maintain uniform aerobic conditions. Overall, improved mass transfer coefficients, mixing efficiency and energy efficiency of the novel microbubble generation method could offer significant savings to the water treatment plants as well as reduction in the carbon footprint. PMID:25483415

  1. Performance of a hollow-fiber spiral disk for effective gas dispersion toward high mass transfer rate

    SciTech Connect

    Tsuchiya, Katsumi; Haryono, M.H.; Tomida, Tahei; Hatano, Hiroyuki; Oaki, Hiroshi

    1996-02-01

    Gas-dispersive capability of a hollow-fiber membrane, manufactured specifically for the use in fine bubbles generation, is tested for attaining high gas-liquid mass transfer rate under low-gas-throughput, shallow-sparging (at depths < 0.7 m) conditions. The hollow fiber is wound in a plane spiral form, each of which can be piled in a cylindrical module. A bubble column is used in the presence as well as absence of a draft tube, which the module can fit to and serve as part of. To enhance the effectiveness in the module`s generating fine bubbles, electrolytes are added to the liquid phase, water. Over a superficial gas velocity range of 0.1--2 mm/s, the hollow-fiber module (in comparison to conventional perforated-plate distributors) demonstrates, even with moderate gas-supply pressures (< 0.3 MPa), as high as 3-fold and 20-fold increases in the volumetric mass transfer coefficient in the absence and presence of the electrolytes, respectively. The former has been attained with a negligible increase in the gas holdup; the latter has accompanied a large ({approximately} 20-fold) increase in the gas holdup. While in the latter case the bubbles are very finely dispersed, the draft-tube model of operation secures still reasonable liquid circulation with nonclustering, spherical bubbles uniformly dispersed in each of the core and annular regions of the bubble column.

  2. CIRCUMSTELLAR ENVIRONMENT AND EFFECTIVE TEMPERATURE OF THE YOUNG SUBSTELLAR ECLIPSING BINARY 2MASS J05352184-0546085

    SciTech Connect

    Mohanty, Subhanjoy; Stassun, Keivan G.; Mathieu, Robert D.

    2009-05-20

    We present new Spitzer IRAC/PU/MIPS photometry from 3.6 to 24 {mu}m, and new Gemini GMOS photometry at 0.48 {mu}m, of the young brown dwarf eclipsing binary 2MASS J05352184-0546085, located in the Orion Nebula Cluster. No excess disk emission is detected. The measured fluxes at {lambda} {<=} 8 {mu}m are within 1{sigma} ({approx}<0.1 mJy) of a bare photosphere, and the 3{sigma} upper limit at 16 {mu}m is a mere 0.04 mJy above the bare photospheric level. Together with the known properties of the system, this implies the absence of optically thick disks around the individual components. It also implies that if any circumbinary disk is present, it must either be optically thin and extremely tenuous (10{sup -10} M {sub sun}) if it extends in to within {approx}0.1 AU of the binary (the approximate tidal truncation radius), or it must be optically thick with a large inner hole, >0.6-10 AU in radius depending on degree of flaring. The consequence in all cases is that disk accretion is likely to be negligible or absent. This supports the recent proposal that the strong H{alpha} emission in the primary (more massive) brown dwarf results from chromospheric activity, and thereby bolsters the hypothesis that the surprising T {sub eff} inversion observed between the components is due to strong magnetic fields on the primary. Our data also set constraints on the T {sub eff} of the components independent of spectral type, and thereby on models of the aforementioned magnetic field effects. We discuss the consequences for the derived fundamental properties of young brown dwarfs and very low mass stars in general. Specifically, if very active isolated young brown dwarfs and very low mass stars suffer the same activity/field related effects as the 2M0535-05 primary, the low-mass stellar/substellar initial mass function currently derived from standard evolutionary tracks may be substantially in error.

  3. Sensitivity of β -decay rates to the radial dependence of the nucleon effective mass

    NASA Astrophysics Data System (ADS)

    Severyukhin, A. P.; Margueron, J.; Borzov, I. N.; Van Giai, N.

    2015-03-01

    We analyze the sensitivity of β -decay rates in 78Ni and Sn,132100 to a correction term in Skyrme energy-density functionals (EDFs) which modifies the radial shape of the nucleon effective mass. This correction is added on top of several Skyrme parametrizations which are selected from their effective mass properties and predictions about the stability properties of 132Sn . The impact of the correction on high-energy collective modes is shown to be moderate. From the comparison of the effects induced by the surface-peaked effective mass in the three doubly magic nuclei, it is found that 132Sn is largely impacted by the correction, while 78Ni and 100Sn are only moderately affected. We conclude that β -decay rates in these nuclei can be used as a test of different parts of the nuclear EDF: 78Ni and 100Sn are mostly sensitive to the particle-hole interaction through the B (GT) values, while 132Sn is sensitive to the radial shape of the effective mass. Possible improvements of these different parts could therefore be better constrained in the future.

  4. The effect of centre of mass location on sagittal plane moments around the centre of mass in trotting horses.

    PubMed

    Hobbs, Sarah Jane; Richards, Jim; Clayton, Hilary M

    2014-04-11

    The diagonal limb support pattern at trot provides pitch and roll stability, but little is known about the control of moments about the centre of mass (COM) in horses. Correct COM location is critical in the calculation of pitching moments. The objectives were to determine the effect of COM location on pitching moments in trotting horses and explore how COM location could influence balance. Kinematic (120 Hz) and GRF (4 force plates, 960 Hz) data were collected at trot from three trials of eight horses. The position of the COM was determined from the weighted summation of the segmental COMs and this was then manipulated cranially and caudally to test the model. Sagittal-plane moments around the COM were calculated for each manipulation of the model and their relationship determined using reduced major axis regression. Over the stride, the moments must sum to zero to prevent accumulation of rotational motion. This was found when the weight on the forelimbs in standing was 58.7% ± 3% (mean ± 95% C.I.), which corresponded closely to the COP ratio in standing. Moments were typically nose-up at foot strike changing to nose-down prior to midstance, and then reversing to nose-up in late stance. Mean moments were larger in the hindlimbs and more sensitive to COM location changes. Divergence of the COM from the COP creating a vertical force moment arm prior to midstance may assist the hindlimb in relation to propulsive effort. A similar effect is seen in the forelimb during single limb support. PMID:24636530

  5. Biological Matrix Effects in Quantitative Tandem Mass Spectrometry-Based Analytical Methods: Advancing Biomonitoring

    PubMed Central

    Panuwet, Parinya; Hunter, Ronald E.; D’Souza, Priya E.; Chen, Xianyu; Radford, Samantha A.; Cohen, Jordan R.; Marder, M. Elizabeth; Kartavenka, Kostya; Ryan, P. Barry; Barr, Dana Boyd

    2015-01-01

    The ability to quantify levels of target analytes in biological samples accurately and precisely, in biomonitoring, involves the use of highly sensitive and selective instrumentation such as tandem mass spectrometers and a thorough understanding of highly variable matrix effects. Typically, matrix effects are caused by co-eluting matrix components that alter the ionization of target analytes as well as the chromatographic response of target analytes, leading to reduced or increased sensitivity of the analysis. Thus, before the desired accuracy and precision standards of laboratory data are achieved, these effects must be characterized and controlled. Here we present our review and observations of matrix effects encountered during the validation and implementation of tandem mass spectrometry-based analytical methods. We also provide systematic, comprehensive laboratory strategies needed to control challenges posed by matrix effects in order to ensure delivery of the most accurate data for biomonitoring studies assessing exposure to environmental toxicants. PMID:25562585

  6. Effects of dynamical masses of gluons and quarks on hadronic B decays

    SciTech Connect

    Zanetti, C. M.; Natale, A. A.

    2010-11-12

    We study hadronic annihilation decays of B mesons within the perturbative QCD at collinear approximation. The regulation of endpoint divergences is performed with the help of an infrared finite gluon propagator characterized by a non-perturbative dynamical gluon mass. The divergences at twist-3 are regulated by a dynamical quark mass. Our results fit quite well the existent data of B{sup 0}{yields}D{sub s}{sup -}K{sup +} and B{sup 0}{yields}D{sub s}{sup -*}K{sup +} for the expected range of dynamical gluon masses. We also make predictions for the rare decays B{sup 0}{yields}K{sup -}K{sup +}, B{sub s}{sup 0}{yields}{pi}{sup -}{pi}{sup +}, {pi}{sup 0}{pi}{sup 0}, B{sup +}{yields}D{sub s}{sup (*)+}K-bar{sup 0}, B{sup 0}{yields}D{sub s}{sup {+-}(*)}K{sup {+-}} and B{sub s}{sup 0}{yields}D{sup {+-}(*)}{pi}{sup {+-}}, D{sup 0}{pi}{sup 0}.

  7. Semiphenomenological approximation of the sums of experimental radiative strength functions for dipole gamma transitions of energy E{sub {gamma}}below the neutron binding energy B{sub n} for mass numbers in the range 40 {<=} A {<=} 200

    SciTech Connect

    Sukhovoj, A. M. Furman, W. I. Khitrov, V. A.

    2008-06-15

    The sums of radiative strength functions for primary dipole gamma transitions, k(E1) + k(M1), are approximated to a high precision by a superposition of two functional dependences in the energy range 0.5 < E{sub 1} < B{sub n} - 0.5 MeV for the {sup 40}K, {sup 60}Co, {sup 71,74}Ge, {sup 80}Br, {sup 114}Cd, {sup 118}Sn, {sup 124,125}Te, {sup 128}I, {sup 137,138,139}Ba, {sup 140}La, {sup 150}Sm, {sup 156,158}Gd, {sup 160}Tb, {sup 163,164,165}Dy, {sup 166}Ho, {sup 168}Er, {sup 170}Tm, {sup 174}Yb, {sup 176,177}Lu, {sup 181}Hf, {sup 182}Ta, {sup 183,184,185,187}W, {sup 188,190,191,193}Os, {sup 192}Ir, {sup 196}Pt, {sup 198}Au, and {sup 200}Hg nuclei. It is shown that, in any nuclei, radiative strength functions are a dynamical quantity and that the values of k(E1) + k(M1) for specific energies of gamma transitions and specific nuclei are determined by the structure of decaying and excited levels, at least up to the neutron binding energy B{sub n}.

  8. The Nc dependencies of baryon masses: Analysis with Lattice QCD and Effective Theory

    SciTech Connect

    Calle Cordon, Alvaro C.; DeGrand, Thomas A.; Goity, Jose L.

    2014-07-01

    Baryon masses at varying values of Nc and light quark masses are studied with Lattice QCD and the results are analyzed in a low energy effective theory based on a combined framework of the 1/Nc and Heavy Baryon Chiral Perturbation Theory expansions. Lattice QCD results for Nc=3, 5 and 7 obtained in quenched calculations, as well as results for unquenched calculations for Nc=3, are used for the analysis. The results are consistent with a previous analysis of Nc=3 LQCD results, and in addition permit the determination of sub-leading in 1/Nc effects in the spin-flavor singlet component of the baryon masses as well as in the hyperfine splittings.

  9. Cluster Masses Derived from X-ray and Sunyaev-Zeldovich Effect Measurements

    NASA Technical Reports Server (NTRS)

    Laroque, S.; Joy, Marshall; Bonamente, M.; Carlstrom, J.; Dawson, K.

    2003-01-01

    We infer the gas mass and total gravitational mass of 11 clusters using two different methods; analysis of X-ray data from the Chandra X-ray Observatory and analysis of centimeter-wave Sunyaev-Zel'dovich Effect (SZE) data from the BIMA and OVRO interferometers. This flux-limited sample of clusters from the BCS cluster catalogue was chosen so as to be well above the surface brightness limit of the ROSAT All Sky Survey; this is therefore an orientation unbiased sample. The gas mass fraction, f_g, is calculated for each cluster using both X-ray and SZE data, and the results are compared at a fiducial radius of r_500. Comparison of the X-ray and SZE results for this orientation unbiased sample allows us to constrain cluster systematics, such as clumping of the intracluster medium. We derive an upper limit on Omega_M assuming that the mass composition of clusters within r_500 reflects the universal mass composition Omega_M h_100 is greater than Omega _B / f-g. We also demonstrate how the mean f_g derived from the sample can be used to estimate the masses of clusters discovered by upcoming deep SZE surveys.

  10. Effect of Fully Grouted Passive Bolts on Joint Shear Strength Parameters in a Blocky Mass

    NASA Astrophysics Data System (ADS)

    Srivastava, Lok Priya; Singh, Mahendra

    2015-05-01

    The present paper discusses an experimental study on shear strength response of unreinforced and reinforced block masses to find out the effect of fully grouted passive bolts on the shear strength parameters of joints in a mass. Direct shear tests were conducted on specimens of large-sized blocky masses, each with a dimension of 750 × 750 × 900 mm. Each blocky mass was assembled by piling elemental blocks of size 150 × 150 × 150 mm. For the reinforced condition, the mass was reinforced with three, five, and nine bolts perpendicular to the shear plane. The tests were conducted at different normal stress levels ranging from 0 to 2 MPa, which are common in rock slopes. Results from the tests show that passive bolts enhance the joint shear strength parameters. The strength enhancement is mainly due to improved interlocking and therefore, enhanced cohesion. The value of enhanced cohesion depends on the bolt area, the ratio of bolt spacing to block size and the strength of the intact material for a given set of steel and grout. A correlation has been established to find out enhanced cohesion for the given joints in the mass.

  11. An integrating matrix formulation for buckling of rotating beams including the effects of concentrated masses

    NASA Technical Reports Server (NTRS)

    Lakin, William D.; Kvaternik, Raymond G.

    1989-01-01

    The integrating matrix technique of computational mechanics is extended to include the effects of concentrated masses. The stability of a flexible rotating beam with discrete masses is analyzed to determine the critical rotational speeds for buckling in the inplane and out-of-plane directions. In this problem, the beam is subjected to compressive centrifugal forces arising from steady rotation about an axis which does not pass through the clamped end of the beam. To determine the eigenvalues from which stability is assessed, the differential equations of motion are solved numerically by combining the extended integrating matrix method with an eigenanalysis. Stability boundaries for a discrete mass representation of a uniform beam are shown to asymptotically approach the stability boundaries for the corresponding continuous mass beam as the number of concentrated masses is increased. An error in the literature is also noted for the discrete mass problem concerning the behavior of the critical rotational speed for inplane buckling as the radius of rotation of the clamped end of the beam is reduced.

  12. HALOGEN: Approximate synthetic halo catalog generator

    NASA Astrophysics Data System (ADS)

    Avila Perez, Santiago; Murray, Steven

    2015-05-01

    HALOGEN generates approximate synthetic halo catalogs. Written in C, it decomposes the problem of generating cosmological tracer distributions (eg. halos) into four steps: generating an approximate density field, generating the required number of tracers from a CDF over mass, placing the tracers on field particles according to a bias scheme dependent on local density, and assigning velocities to the tracers based on velocities of local particles. It also implements a default set of four models for these steps. HALOGEN uses 2LPTic (ascl:1201.005) and CUTE (ascl:1505.016); the software is flexible and can be adapted to varying cosmologies and simulation specifications.

  13. Structural, mechanical, electronic, optical properties and effective masses of CuMO2 (M = Sc, Y, La) compounds: First-principles calculations

    NASA Astrophysics Data System (ADS)

    Liu, Qi-Jun; Zhang, Ning-Chao; Sun, Yan-Yun; Liu, Fu-Sheng; Liu, Zheng-Tang

    2014-05-01

    The structural, elastic, mechanical, electronic, optical properties and effective masses of CuMIIIBO2 (MIIIB = Sc, Y, La) compounds have been investigated by the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory under local density approximation. The equilibrium structural parameters are in good agreement with previous experimental and theoretical data. To our knowledge, there are no available data of elastic constants for comparison. The bulk, shear and Young's modulus, ratio of B/G, Poisson's ratio and Lamé's constants of CuMIIIBO2 have been studied. The electronic structures of CuMIIIBO2 are consistent with other calculations. The population analysis, charge densities and effective masses have been shown and analyzed. The imaginary and real parts of the dielectric function, refractive index and extinction coefficient of CuMIIIBO2 are calculated. The interband transitions to absorption of CuMIIIBO2 have been analyzed.

  14. Mass effect on the lithium abundance evolution of open clusters: Hyades, NGC 752, and M 67

    NASA Astrophysics Data System (ADS)

    Castro, M.; Duarte, T.; Pace, G.; do Nascimento, J.-D.

    2016-05-01

    Lithium abundances in open clusters provide an effective way of probing mixing processes in the interior of solar-type stars and convection is not the only mixing mechanism at work. To understand which mixing mechanisms are occurring in low-mass stars, we test non-standard models, which were calibrated using the Sun, with observations of three open clusters of different ages, the Hyades, NGC 752, and M 67. We collected all available data, and for the open cluster NGC 752, we redetermine the equivalent widths and the lithium abundances. Two sets of evolutionary models were computed, one grid of only standard models with microscopic diffusion and one grid with rotation-induced mixing, at metallicity [Fe/H] = 0.13, 0.0, and 0.01 dex, respectively, using the Toulouse-Geneva evolution code. We compare observations with models in a color-magnitude diagram for each cluster to infer a cluster age and a stellar mass for each cluster member. Then, for each cluster we analyze the lithium abundance of each star as a function of mass. The data for the open clusters Hyades, NGC 752, and M 67, are compatible with lithium abundance being a function of both age and mass for stars in these clusters. Our models with meridional circulation qualitatively reproduce the general trend of lithium abundance evolution as a function of stellar mass in all three clusters. This study points out the importance of mass dependence in the evolution of lithium abundance as a function of age. Comparison between models with and without rotation-induced mixing shows that the inclusion of meridional circulation is essential to account for lithium depletion in low-mass stars. However, our results suggest that other mechanisms should be included to explain the Li-dip and the lithium dispersion in low-mass stars.

  15. Effects of Parental Status on Male Body Mass in the Monogamous, Biparental California Mouse

    PubMed Central

    Saltzman, Wendy; Harris, Breanna N.; de Jong, Trynke R.; Nguyen, Pauline P.; Cho, Julia T.; Hernandez, Mindy; Perea-Rodriguez, Juan P.

    2014-01-01

    Studies of biparental mammals demonstrate that males may undergo systematic changes in body mass as a consequence of changes in reproductive status; however, these studies typically have not teased apart effects of specific social and reproductive factors, such as cohabitation with a female per se, cohabitation with a breeding female specifically, and engagement in paternal care. We aimed to determine whether California mouse (Peromyscus californicus) fathers undergo systematic changes in body mass and if so, which specific social/reproductive factor(s) might contribute to these changes. We compared mean weekly body masses over a 5-week period in 1) males housed with another male vs. males housed with a non-reproductive (tubally ligated) female; 2) males housed with a tubally ligated female vs. males housed with a female that was undergoing her first pregnancy; and 3) experienced fathers housed with vs. without pups during their mate’s subsequent pregnancy. Body mass did not differ between males housed with another male and those housed with a non-reproductive female; however, males housed with a non-reproductive female were significantly heavier than those housed with a primiparous female. Among experienced fathers, those housed with pups from their previous litter underwent significant increases in body mass across their mates’ pregnancy, whereas fathers housed without pups did not. These results suggest that male body mass is reduced by cohabitation with a breeding (pregnant) female, but not by cohabitation with a non-reproductive female, and that increases in body mass across the mate’s pregnancy are associated with concurrent care of offspring rather than cohabitation with a pregnant female. Additional work is needed to determine the mechanisms and functional significance, if any, of these changes in male body mass with reproductive condition. PMID:26005292

  16. Mass media campaigns within reach: effective efforts with limited resources in Russia's capital city.

    PubMed

    Perl, Rebecca; Stebenkova, Ludmila; Morozova, Irina; Murukutla, Nandita; Kochetova, Veronika; Kotov, Alexey; Voylokova, Tatiana; Baskakova, Julia

    2011-11-01

    Mass media campaigns, while often expensive, are proven, cost-effective interventions and should not be considered out-of-reach, especially where governments have some sway over media markets, where large media discounts are possible or where other novel strategies can be employed. PMID:21685490

  17. Opportunities to investigate the effects of ivermectin mass drug administration on scabies.

    PubMed

    Engelman, Daniel; Martin, Diana L; Hay, Roderick J; Chosidow, Olivier; McCarthy, James S; Fuller, L Claire; Steer, Andrew C

    2013-01-01

    The recent article by Mohammed et al. demonstrates an impressive effect of ivermectin mass drug administration for lymphatic filariasis on the burden of scabies. Partnering scabies research within the evaluation and monitoring of Neglected Tropical Disease programmes could potentially increase our understanding of the epidemiology and control of scabies and its important bacterial complications. PMID:23594459

  18. Influence of interface potential on the effective mass in Ge nanostructures

    SciTech Connect

    Barbagiovanni, E. G. Cosentino, S.; Terrasi, A.; Mirabella, S.; Lockwood, D. J.; Costa Filho, R. N.

    2015-04-21

    The role of the interface potential on the effective mass of charge carriers is elucidated in this work. We develop a new theoretical formalism using a spatially dependent effective mass that is related to the magnitude of the interface potential. Using this formalism, we studied Ge quantum dots (QDs) formed by plasma enhanced chemical vapour deposition (PECVD) and co-sputtering (sputter). These samples allowed us to isolate important consequences arising from differences in the interface potential. We found that for a higher interface potential, as in the case of PECVD QDs, there is a larger reduction in the effective mass, which increases the confinement energy with respect to the sputter sample. We further understood the action of O interface states by comparing our results with Ge QDs grown by molecular beam epitaxy. It is found that the O states can suppress the influence of the interface potential. From our theoretical formalism, we determine the length scale over which the interface potential influences the effective mass.

  19. Effect of mass transfer on the oxygen reduction reaction catalyzed by platinum dendrimer encapsulated nanoparticles

    PubMed Central

    Dumitrescu, Ioana; Crooks, Richard M.

    2012-01-01

    Here we report on the effect of the mass transfer rate (kt) on the oxygen reduction reaction (ORR) catalyzed by Pt dendrimer-encapsulated nanoparticles (DENs) comprised of 147 and 55 atoms (Pt147 and Pt55). The experiments were carried out using a dual-electrode microelectrochemical device, which enables the study of the ORR under high kt conditions with simultaneous detection of H2O2. At low kt (0.02 to 0.12 cm s-1) the effective number of electrons involved in ORR, neff, is 3.7 for Pt147 and 3.4 for Pt55. As kt is increased, the mass-transfer-limited current for the ORR becomes significantly lower than the value predicted by the Levich equation for a 4-electron process regardless of catalyst size. However, the percentage of H2O2 detected remains constant, such that neff barely changes over the entire kt range explored (0.02 cm s-1). This suggests that mass transfer does not affect neff, which has implications for the mechanism of the ORR on Pt nanoparticles. Interestingly, there is a significant difference in neff for the two sizes of Pt DENs (neff = 3.7 and 3.5 for Pt147 and Pt55, respectively) that cannot be assigned to mass transfer effects and that we therefore attribute to a particle size effect. PMID:22665772

  20. Application of Berry's Phase to the Effective Mass of Bloch Electrons

    ERIC Educational Resources Information Center

    Rave, M. J.; Kerr, W. C.

    2010-01-01

    Berry's phase, although well known since 1984, has received little attention among textbook authors of solid state physics. We attempt to address this lack by showing how the presence of the Berry's phase significantly changes a standard concept (effective mass) found in most solid state texts. Specifically, we show that the presence of a non-zero…

  1. Measurement of [N] dependence of electron effective mass in GaAsN

    NASA Astrophysics Data System (ADS)

    Dannecker, Tassilo; Jin, Yu; Buckeridge, John; Uher, Ctirad; Kurdak, Cagliyan; Fahy, Stephen; Goldman, Rachel S.

    2010-03-01

    The electron effective mass of GaAs1-xNx is predicted to be dependent on N-composition, x; however, conflicting results have been observed using cyclotron resonance and thermomagnetic measurements. Using room temperature thermopower and Hall measurements, in conjunction with assumptions of parabolic bands and Fermi-Dirac statistics, we determined the N composition dependence of the electron effective mass of GaAs1-xNx, in comparison with that of GaAs. Measurements of the Seebeck coefficient, S, for N compositions ranging from x=0 to 0.018, reveal a decrease in S with increasing x. The free carrier concentration, [n], for all GaAsN is lower than for GaAs. For GaAs, we extract an effective mass value of 0.052me, slightly lower than the literature value of 0.067m0. For GaAsN, the effective mass apparently is in all cases greater than for GaAs but varies non-monotonically with x, revealing a minimum at x=0.010 and maxima at x=0.004 and 0.018. This non-monotonic dependence of m* on x cannot be explained with a simple band anti-crossing (BAC) model. Interestingly, this data is consistent with the predictions of Lindsay et al, suggesting the presence of resonances between N-related states and the GaAsN conduction band edge.

  2. Scattering and Bound States of Klein-Gordon Particle with Hylleraas Potential Within Effective Mass Formalism

    NASA Astrophysics Data System (ADS)

    Onyeaju, M. C.; Ikot, A. N.; Chukwuocha, E. O.; Obong, H. P.; Zare, S.; Hassanabadi, H.

    2016-06-01

    Scattering and bound states solution for the one-dimensional Klein-Gordon particle with Hylleraas potential is presented within the frame work of position dependent effective mass formalism. We calculate in detail the reflection and transmission coefficients using the properties of hypergeometric functions and the equation of continuity of the wave functions.

  3. Introducing the Notion of Bare and Effective Mass via Newton's Second Law of Motion

    ERIC Educational Resources Information Center

    Pinto, Marcus Benghi

    2007-01-01

    The concepts of bare and effective mass are widely used within modern physics. Their meaning is discussed in advanced undergraduate and graduate courses such as solid state physics, nuclear physics and quantum field theory. Here I discuss how these concepts may be introduced together with the discussion of Newton's second law of motion. The…

  4. A Bioecological Model of Mass Trauma: Individual, Community, and Societal Effects

    ERIC Educational Resources Information Center

    Hoffman, Mary Ann; Kruczek, Theresa

    2011-01-01

    Biopsychosocial consequences of catastrophic events create an ongoing need for research that examines the effects of mass traumas, developing psychosocial interventions, and advocacy to address the needs of affected individuals, systems, and communities. Because it is neither possible nor necessarily desirable to intervene with all touched by…

  5. Influence of interface potential on the effective mass in Ge nanostructures

    NASA Astrophysics Data System (ADS)

    Barbagiovanni, E. G.; Cosentino, S.; Lockwood, D. J.; Costa Filho, R. N.; Terrasi, A.; Mirabella, S.

    2015-04-01

    The role of the interface potential on the effective mass of charge carriers is elucidated in this work. We develop a new theoretical formalism using a spatially dependent effective mass that is related to the magnitude of the interface potential. Using this formalism, we studied Ge quantum dots (QDs) formed by plasma enhanced chemical vapour deposition (PECVD) and co-sputtering (sputter). These samples allowed us to isolate important consequences arising from differences in the interface potential. We found that for a higher interface potential, as in the case of PECVD QDs, there is a larger reduction in the effective mass, which increases the confinement energy with respect to the sputter sample. We further understood the action of O interface states by comparing our results with Ge QDs grown by molecular beam epitaxy. It is found that the O states can suppress the influence of the interface potential. From our theoretical formalism, we determine the length scale over which the interface potential influences the effective mass.

  6. Effects of Massed, Distributed, and Spaced Trial Sequencing on Severely Handicapped Students' Performance.

    ERIC Educational Resources Information Center

    Mulligan, Marilyn; And Others

    1982-01-01

    During training of cognitive and motor skills, the effects of massed, distributed, and spaced trial sequencing were evaluated relative to performance of 11 severely handicapped students (5-19 years old). Results supported the addition of distributed trial sequencing to the technology of instruction for severely handicapped learners. (Author/CL)

  7. Supersymmetry and coherent states for the displacement-operator-derived effective mass system

    NASA Astrophysics Data System (ADS)

    Vubangsi, M.; Tchoffo, M.; Fai, L. C.; Pis'mak, Yu. M.

    2015-01-01

    Applying the supersymmetric quantum mechanics approach, we derive shape-invariant trigonometric potentials for the displacement-operator-derived effective mass Hamiltonian. By linearizing the algebra resulting from SUSY-QM factorization of the constructed systems, their coherent states are defined and shown to be exponentially dependent on a function of the quantum numbers.

  8. Effects of Massed vs. Distributed Practice and Word Frequency on Young Children's Free Recall.

    ERIC Educational Resources Information Center

    Hohn, Robert L.

    Research on massed practice (MP) and distributed practice effects to preschool children in free recall tasks is reported. A total of 40 kindergarten children were randomly assigned to High Frequency and Low Frequency word groups. No significant differences were found between the two groups on the dimensions of IQ and age. Lists of 32 high…

  9. Gastrointestinal absorption of neptunium in primates: effect of ingested mass, diet, and fasting

    SciTech Connect

    Metivier, H.; Bourges, J.; Fritsch, P.; Nolibe, D.; Masse, R.

    1986-05-01

    Absorption and retention of neptunium were determined in baboons after intragastric administration of neptunium nitrate solutions at pH 1. The effects of mass, diet, and fasting on absorption were studied. At higher mass levels (400-800 micrograms Np/kg), absorption was about 1%; at lower mass intakes (0.0009-0.005 micrograms Np/kg), absorption was reduced by 10- to 20-fold. The addition of an oxidizing agent (Fe3+) increased gastrointestinal absorption and supported the hypothesis of a reduction of Np (V) when loss masses were ingested. Diets depleted of or enriched with hydroxy acids did not modify retention of neptunium but increased urinary excretion with increasing hydroxy acid content. The diet enriched with milk components reduced absorption by a factor of 5. Potatoes increased absorption and retention by a factor 5, not necessarily due to the effect of phytate. Fasting for 12 or 24 h increased retention and absorption by factors of about 3 and 10, respectively. Data obtained in baboons when low masses of neptunium were administered suggest that the f1 factor used by ICRP should be decreased. However, fasting as encountered in certain nutritional habits is a factor to be taken into consideration.

  10. Structural design of a double-layered porous hydrogel for effective mass transport

    PubMed Central

    Kim, Hyejeong; Kim, Hyeon Jeong; Huh, Hyung Kyu; Hwang, Hyung Ju; Lee, Sang Joon

    2015-01-01

    Mass transport in porous materials is universal in nature, and its worth attracts great attention in many engineering applications. Plant leaves, which work as natural hydraulic pumps for water uptake, have evolved to have the morphological structure for fast water transport to compensate large water loss by leaf transpiration. In this study, we tried to deduce the advantageous structural features of plant leaves for practical applications. Inspired by the tissue organization of the hydraulic pathways in plant leaves, analogous double-layered porous models were fabricated using agarose hydrogel. Solute transport through the hydrogel models with different thickness ratios of the two layers was experimentally observed. In addition, numerical simulation and theoretical analysis were carried out with varying porosity and thickness ratio to investigate the effect of structural factors on mass transport ability. A simple parametric study was also conducted to examine unveiled relations between structural factors. As a result, the porosity and thickness ratio of the two layers are found to govern the mass transport ability in double-layered porous materials. The hydrogel models with widely dispersed pores at a fixed porosity, i.e., close to a homogeneously porous structure, are mostly turned out to exhibit fast mass transport. The present results would provide a new framework for fundamental design of various porous structures for effective mass transport. PMID:25825619

  11. Assessment of molecular effects on neutrino mass measurements from tritium β decay

    NASA Astrophysics Data System (ADS)

    Bodine, L. I.; Parno, D. Â. S.; Robertson, R. Â. G. Â. H.

    2015-03-01

    The β decay of molecular tritium currently provides the highest sensitivity in laboratory-based neutrino mass measurements. The upcoming Karlsruhe Tritium Neutrino (KATRIN) experiment will improve the sensitivity to 0.2 eV, making a percent-level quantitative understanding of molecular effects essential. The modern theoretical calculations available for neutrino mass experiments agree with spectroscopic data. Moreover, when neutrino mass experiments performed in the 1980s with gaseous tritium are reevaluated using these modern calculations, the extracted neutrino mass squared values are consistent with zero instead of being significantly negative. However, the calculated molecular final-state branching ratios are in conflict with dissociation experiments performed in the 1950s. We reexamine the theory of the final-state spectrum of molecular-tritium decay and its effect on the determination of the neutrino mass, with an emphasis on the role of the vibrational- and rotational-state distribution in the ground electronic state. General features can be reproduced quantitatively from considerations of kinematics and zero-point motion. We summarize the status of validation efforts and suggest means for resolving the apparent discrepancy in dissociation rates.

  12. Effect of electric fields on mass transfer to droplets. Final report

    SciTech Connect

    Carleson, T.E.; Budwig, R.

    1994-02-01

    During the six year funding period, the effects of a direct and alternating field upon single drop hydrodynamics and mass transfer were evaluated both experimentally and theoretically. Direct current field effects upon drop size, velocity and mass transfer rates were also observed for multiple drops formed in a three stage sieve tray column. Drop size, velocity, and mass transfer rates were measured experimentally and compared to simple models for direct current electric fields. Agreement between theory and experiment was found for drop charge, size, and velocity. Drop mass transfer coefficients were substantially larger than theoretical predictions while extraction efficiencies were moderately higher. Drop distortion and oscillation were observed and are thought to result in the experimentally observed higher values. For alternating current fields, drop flow streamlines and oscillations were measured and found to compare well with predictions from a solved mathematical model. In addition, equipment was constructed to determine mass transfer rates to oscillating drops. Concentration profiles in still and oscillating drops were measured and qualitatively compared to theoretical predictions.

  13. The effect on empirical atmospheric modeling of the mass-flux as an independent parameter. [in sun and Be stars

    NASA Technical Reports Server (NTRS)

    Thomas, R. N.

    1982-01-01

    Observational data on atmospheric structure and mass fluxes from the sun and Be stars are applied to test the adequacy of the original Parker 'hot corona' approach to predicting atmospheric structure and the size of the mass flux from only the radiative and nonradiative energy fluxes, and from gravity, and imposing the condition that thermal and escape points must coincide. Observations do not support this latter condition. It is concluded that the Parker approach is an asymptotic approximation to the very low mass flux limit in a nonvariable stellar atmosphere.

  14. Seed-mass effects in four Mediterranean Quercus species (Fagaceae) growing in contrasting light environments.

    PubMed

    Quero, José Luis; Villar, Rafael; Marañón, Teodoro; Zamora, Regino; Poorter, Lourens

    2007-11-01

    Three hypotheses have been proposed to explain the functional relationship between seed mass and seedling performance: the reserve effect (larger seeds retain a larger proportion of reserves after germinating), the metabolic effect (seedlings from larger seeds have slower relative growth rates), and the seedling-size effect (larger seeds produce larger seedlings). We tested these hypotheses by growing four Mediterranean Quercus species under different light conditions (3, 27, and 100% of available radiation). We found evidence for two of the three hypotheses, but none of the four species complied with all three hypotheses at the same time. The reserve effect was not found in any species, the metabolic effect was found in three species (Q. ilex, Q. pyrenaica, and Q. suber), and the seedling-size effect in all species. Light availability significantly affected the relationships between seed size and seedling traits. For Q. ilex and Q. canariensis, a seedling-size effect was found under all three light conditions, but only under the lowest light (3%) for Q. suber and Q. pyrenaica. In all species, the correlation between seed mass and seedling mass increased with a decrease in light, suggesting that seedlings growing in low light depend more upon their seed reserves. A causal model integrates the three hypotheses, suggesting that larger seeds generally produced larger seedlings. PMID:21636374

  15. ENVIRONMENTAL EFFECTS ON THE METAL ENRICHMENT OF LOW-MASS GALAXIES IN NEARBY CLUSTERS

    SciTech Connect

    Petropoulou, V.; Vilchez, J.; Iglesias-Paramo, J.

    2012-04-20

    In this paper, we study the chemical history of low-mass star-forming (SF) galaxies in the local universe clusters Coma, A1367, A779, and A634. The aim of this work is to search for the imprint of the environment on the chemical evolution of these galaxies. Galaxy chemical evolution is linked to the star formation history, as well as to the gas interchange with the environment, and low-mass galaxies are well known to be vulnerable systems to environmental processes affecting both these parameters. For our study we have used spectra from the SDSS-III DR8. We have examined the spectroscopic properties of SF galaxies of stellar masses 10{sup 8}-10{sup 10} M{sub Sun }, located from the core to the cluster's outskirts. The gas-phase O/H and N/O chemical abundances have been derived using the latest empirical calibrations. We have examined the mass-metallicity relation of cluster galaxies, finding well-defined sequences. The slope of these sequences, for galaxies in low-mass clusters and galaxies at large cluster-centric distances, follows the predictions of recent hydrodynamic models. A flattening of this slope has been observed for galaxies located in the core of the two more massive clusters of the sample, principally in Coma, suggesting that the imprint of the cluster environment on the chemical evolution of SF galaxies should be sensitive to both the galaxy mass and the host cluster mass. The H I gas content of Coma and A1367 galaxies indicates that low-mass SF galaxies, located at the core of these clusters, have been severely affected by ram-pressure stripping (RPS). The observed mass-dependent enhancement of the metal content of low-mass galaxies in dense environments seems plausible, according to hydrodynamic simulations. This enhanced metal enrichment could be produced by the combination of effects such as wind reaccretion, due to pressure confinement by the intracluster medium (ICM), and the truncation of gas infall, as a result of the RPS. Thus, the

  16. Effect of Halo Mass on HI Gas Content of Galaxies in Groups and Clusters

    NASA Astrophysics Data System (ADS)

    Yoon, Ilsang; Rosenberg, J. L.

    2014-01-01

    We combine the Sloan Digital Sky Survey (SDSS) and the Arecibo Legacy Fast ALFA (ALFALFA) Survey to study the distribution of cold atomic gas fraction of galaxies that reside in groups and clusters in local Universe. A careful cross-matching between galaxies in SDSS, ALFALFA, and SDSS halo group catalog produces a sample of galaxies with decent statistics in the stellar mass range 108.4 M⊙ ≦ M* ≦ 1010.6 M⊙ and the halo mass range 1012.5 h-1 M⊙ ≦ Mh ≦ 1015.0 h-1 M⊙ for a range of projected distance from the group center 0.04 ≦ r/rvir ≦ 2.0. In order to limit our study to group and cluster interaction processes (not tidal stripping in pairs), we remove close pairs that may be undergoing tidal interactions from the sample. We construct a comparison sample from the isolated field galaxies and investigate the radial distribution of the gas-to-stellar mass ratio for galaxies in groups and clusters relative to the comparison samples with similar stellar mass and redshift. We find that the gas-to-stellar mass ratio decreases toward the centers of groups with halo mass greater than ≈ 1013.8 h-1 M⊙ but find no such trend for galaxies in small halo mass groups. This halo mass dependent effect suggests that there is a threshold for efficient gas stripping due to interaction between galaxies and intracluster medium (ICM). This trend together with the HI line profile properties of our sample galaxies in groups and clusters is consistent with the ram pressure stripping. In particular, the observed relationship between stripping and halo mass is predicted by the classical Gunn-Gott ram pressure stripping criterion modified by scaling relations for galaxies and dark matter halo, which indicates that there is a threshold halo mass for efficient ram pressure stripping for given galaxy stellar mass and ICM temperature. This study was funded by NSF grant AST-000167932.

  17. Mass spectrometer with electron source for reducing space charge effects in sample beam

    DOEpatents

    Houk, Robert S.; Praphairaksit, Narong

    2003-10-14

    A mass spectrometer includes an ion source which generates a beam including positive ions, a sampling interface which extracts a portion of the beam from the ion source to form a sample beam that travels along a path and has an excess of positive ions over at least part of the path, thereby causing space charge effects to occur in the sample beam due to the excess of positive ions in the sample beam, an electron source which adds electrons to the sample beam to reduce space charge repulsion between the positive ions in the sample beam, thereby reducing the space charge effects in the sample beam and producing a sample beam having reduced space charge effects, and a mass analyzer which analyzes the sample beam having reduced space charge effects.

  18. Effect of body mass and clothing on decomposition of pig carcasses.

    PubMed

    Matuszewski, Szymon; Konwerski, Szymon; Frątczak, Katarzyna; Szafałowicz, Michał

    2014-11-01

    Carcass mass and carcass clothing are factors of potential high forensic importance. In casework, corpses differ in mass and kind or extent of clothing; hence, a question arises whether methods for post-mortem interval estimation should take these differences into account. Unfortunately, effects of carcass mass and clothing on specific processes in decomposition and related entomological phenomena are unclear. In this article, simultaneous effects of these factors are analysed. The experiment followed a complete factorial block design with four levels of carcass mass (small carcasses 5-15 kg, medium carcasses 15.1-30 kg, medium/large carcasses 35-50 kg, large carcasses 55-70 kg) and two levels of carcass clothing (clothed and unclothed). Pig carcasses (N = 24) were grouped into three blocks, which were separated in time. Generally, carcass mass revealed significant and frequently large effects in almost all analyses, whereas carcass clothing had only minor influence on some phenomena related to the advanced decay. Carcass mass differently affected particular gross processes in decomposition. Putrefaction was more efficient in larger carcasses, which manifested itself through earlier onset and longer duration of bloating. On the other hand, active decay was less efficient in these carcasses, with relatively low average rate, resulting in slower mass loss and later onset of advanced decay. The average rate of active decay showed a significant, logarithmic increase with an increase in carcass mass, but only in these carcasses on which active decay was driven solely by larval blowflies. If a blowfly-driven active decay was followed by active decay driven by larval Necrodes littoralis (Coleoptera: Silphidae), which was regularly found in medium/large and large carcasses, the average rate showed only a slight and insignificant increase with an increase in carcass mass. These results indicate that lower efficiency of active decay in larger carcasses is a consequence

  19. Investigating the effect of mixing ratio on molar mass distributions of synthetic polymers determined by MALDI-TOF mass spectrometry using design of experiments.

    PubMed

    Brandt, Heike; Ehmann, Thomas; Otto, Matthias

    2010-11-01

    It is well known that the mixing ratio affects the molar mass distribution of synthetic polymers determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Surely, the molar mixing ratio determines whether a mass spectrum will be obtained or not. However, depending on the mass range, several effects such as multimer formation occur, which might be a source of errors in molar mass distribution calculations. In this study, the effect of mixing ratio was investigated for several synthetic polymers, including polystyrene (PS), poly(dimethylsiloxane) (PDMS), poly(ethylene glycol) (PEG), and poly(methyl methacrylate) (PMMA) using statistical designs of experiments. The 2(3) full factorial design was found to be suitable in the study of more than 1000 samples. The obtained MALDI mass spectra as well as the ANOVA statistics show that the mixing ratio affects the molar mass distribution. The optimal mixing ratio for a defined synthetic polymer depends on the studied combination (matrix, cationization reagent, solvent). PMID:20685132

  20. Effective impact ionization threshold and piecewise linear approximation for impact ionization coefficients in a theory of superfast ionizing fronts in semiconductors

    NASA Astrophysics Data System (ADS)

    Minarsky, Andrey; Rodin, Pavel

    2013-04-01

    We focus on theoretical description of superfast ionizing fronts in semiconductor p+-n-n+ structures and argue that in the context of this problem, Townsend's type field dependence of impact ionization coefficients α(E)=α0 exp[(-E0/E)m] can be well approximated by a threshold piecewise linear dependence α(E)=α0'(E -Eb)Θ(E -Eb), where Θ(x) is the unit step function. The possibility of such approximation explains the threshold square dependence υf˜(Em-Eb)2 of the front velocity υf on the maximum electric field Em that the theory of TRAPATT-like ionizing fronts predicts even for threshold-free Townsend's approximation. We suggest a procedure for finding the best-fit parameters of the piecewise linear dependence and determine the values Eb≈0.21 E0, α0'≈0.46α0/E0 for the power m =1 and Eb≈0.5 E0, α0'≈0.7α0/E0 for the power m =2.

  1. Effective density and mass attenuation coefficient for building material in Brazil.

    PubMed

    Salinas, I C P; Conti, C C; Lopes, R T

    2006-01-01

    This paper presents values for density and mass attenuation coefficient of building materials commonly used in Brazil. Transmission measurements were performed to provide input information for simulations with MCNP4B code. The structure for the clay bricks was simulated as a mix of all material layers and an effective density determined. The mass attenuation coefficients were determined for the 50-3,000 keV gamma-ray energy range. A comparison with results for similar materials found in the literature showed good agreement. PMID:16257357

  2. Isoconversion effective activation energies derived from repetitive injection fast gas chromatography/mass spectrometry

    NASA Astrophysics Data System (ADS)

    White, Robert L.

    2009-10-01

    Evolved gas analysis by using fast temperature programmed gas chromatography/mass spectrometry is described. A small volume gas chromatograph oven is used to permit rapid heating and cooling of a capillary gas chromatography column, resulting in short analysis cycle times. This capability permits automated sampling and analysis of a purge gas effluent stream generated during thermal analysis of a solid sample. Species-specific mass spectral information extracted from successively acquired chromatograms can be used to generate concentration profiles for volatile products produced during sample heating. These species-specific profiles can be used for calculation of isoconversion effective activation energies that are useful for characterizing the thermal reaction processes.

  3. Cost-effectiveness of trachoma control measures: comparing targeted household treatment and mass treatment of children.

    PubMed Central

    Frick, K. D.; Lietman, T. M.; Holm, S. O.; Jha, H. C.; Chaudhary, J. S.; Bhatta, R. C.

    2001-01-01

    OBJECTIVE: The present study compares the cost-effectiveness of targeted household treatment and mass treatment of children in the most westerly part of Nepal. METHODS: Effectiveness was measured as the percentage point change in the prevalence of trachoma. Resource measures included personnel time required for treatment, transportation, the time that study subjects had to wait to receive treatment, and the quantity of azithromycin used. The costs of the programme were calculated from the perspectives of the public health programme sponsor, the study subjects, and the society as a whole. FINDINGS: Previous studies have indicated no statistically significant differences in effectiveness, and the present work showed no significant differences in total personnel and transportation costs per child aged 1-10 years, the total time that adults spent waiting, or the quantity of azithromycin per child. However, the mass treatment of children was slightly more effective and used less of each resource per child aged 1-10 years than the targeted treatment of households. CONCLUSION: From all perspectives, the mass treatment of children is at least as effective and no more expensive than targeted household treatment, notwithstanding the absence of statistically significant differences. Less expensive targeting methods are required in order to make targeted household treatment more cost-effective. PMID:11285663

  4. Photon mass and quantum effects of the Aharonov-Bohm type

    SciTech Connect

    Spavieri, G.; Rodriguez, M.

    2007-05-15

    The magnetic field due to the photon rest mass m{sub ph} modifies the standard results of the Aharonov-Bohm effect for electrons, and of other recent quantum effects. For the effect involving a coherent superposition of beams of particles with opposite electromagnetic properties, by means of a tabletop experiment, the limit m{sub ph}{approx_equal}10{sup -51} g is achievable, improving by 6 orders of magnitude that derived by Boulware and Deser for the Aharonov-Bohm effect.

  5. Higgs boson production via gluon fusion: Soft-gluon resummation including mass effects

    NASA Astrophysics Data System (ADS)

    Schmidt, Timo; Spira, Michael

    2016-01-01

    We analyze soft and collinear gluon resummation effects at the N3LL level for Standard Model Higgs boson production via gluon fusion g g →H and the neutral scalar and pseudoscalar Higgs bosons of the minimal supersymmetric extension at the next-to-next-to-next-to-leading-log (N3LL ) and next-to-next-to-leading-log (NNLL) level, respectively. We introduce refinements in the treatment of quark mass effects and subleading collinear gluon effects within the resummation. Soft and collinear gluon resummation effects amount to up to about 5% beyond the fixed-order results for scalar and pseudoscalar Higgs boson production.

  6. Investigation of the dispersion and the effective masses of excitons in bulk 2 H -MoS2 using transition electron energy-loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Habenicht, Carsten; Knupfer, Martin; Büchner, Bernd

    2015-06-01

    We have investigated the electronic excitations in bulk 2 H -MoS2 using electron energy-loss spectroscopy. The electron energy-loss spectra in the Γ M and Γ K directions were measured for various momentum transfer values. The results allow the identification of the A1 and B1 exciton peaks and in particular their energy-momentum dispersion. The dispersions exhibit approximately quadratic upward trends and slight anisotropies in the Γ M and Γ K directions. The fitted energy-momentum transfer functions allow the estimation of the effective masses of the excitons which are in close proximity to predicted values.

  7. Effect of Probiotics Supplementation on Bone Mineral Content and Bone Mass Density

    PubMed Central

    Parvaneh, Kolsoom; Jamaluddin, Rosita; Karimi, Golgis; Erfani, Reza

    2014-01-01

    A few studies in animals and a study in humans showed a positive effect of probiotic on bone metabolism and bone mass density. Most of the investigated bacteria were Lactobacillus and Bifidobacterium . The positive results of the probiotics were supported by the high content of dietary calcium and the high amounts of supplemented probiotics. Some of the principal mechanisms include (1) increasing mineral solubility due to production of short chain fatty acids; (2) producing phytase enzyme by bacteria to overcome the effect of mineral depressed by phytate; (3) reducing intestinal inflammation followed by increasing bone mass density; (4) hydrolysing glycoside bond food in the intestines by Lactobacillus and Bifidobacteria. These mechanisms lead to increase bioavailability of the minerals. In conclusion, probiotics showed potential effects on bone metabolism through different mechanisms with outstanding results in the animal model. The results also showed that postmenopausal women who suffered from low bone mass density are potential targets to consume probiotics for increasing mineral bioavailability including calcium and consequently increasing bone mass density. PMID:24587733

  8. Algebraic solutions of shape-invariant position-dependent effective mass systems

    NASA Astrophysics Data System (ADS)

    Amir, Naila; Iqbal, Shahid

    2016-06-01

    Keeping in view the ordering ambiguity that arises due to the presence of position-dependent effective mass in the kinetic energy term of the Hamiltonian, a general scheme for obtaining algebraic solutions of quantum mechanical systems with position-dependent effective mass is discussed. We quantize the Hamiltonian of the pertaining system by using symmetric ordering of the operators concerning momentum and the spatially varying mass, initially proposed by von Roos and Lévy-Leblond. The algebraic method, used to obtain the solutions, is based on the concepts of supersymmetric quantum mechanics and shape invariance. In order to exemplify the general formalism a class of non-linear oscillators has been considered. This class includes the particular example of a one-dimensional oscillator with different position-dependent effective mass profiles. Explicit expressions for the eigenenergies and eigenfunctions in terms of generalized Hermite polynomials are presented. Moreover, properties of these modified Hermite polynomials, like existence of generating function and recurrence relations among the polynomials have also been studied. Furthermore, it has been shown that in the harmonic limit, all the results for the linear harmonic oscillator are recovered.

  9. Biotic effects of late Maastrichtian mantle plume volcanism: implications for impacts and mass extinctions

    NASA Astrophysics Data System (ADS)

    Keller, Gerta

    2005-02-01

    During the late Maastrichtian, DSDP Site 216 on Ninetyeast Ridge, Indian Ocean, passed over a mantle plume leading to volcanic eruptions, islands built to sea level, and catastrophic environmental conditions for planktic and benthic foraminifera. The biotic effects were severe, including dwarfing of all benthic and planktic species, a 90% reduction in species diversity, exclusion of all ecological specialists, near-absence of ecological generalists, and dominance of the disaster opportunist Guembelitria alternating with low O 2-tolerant species. These faunal characteristics are identical to those of the K-T boundary mass extinction, except that the fauna recovered after Site 216 passed beyond the influence of mantle plume volcanism about 500 kyr before the K-T boundary. Similar biotic effects have been observed in Madagascar, Israel, and Egypt. The direct correlation between mantle plume volcanism and biotic effects on Ninetyeast Ridge and the similarity to the K-T mass extinction, which is generally attributed to a large impact, reveal that impacts and volcanism can cause similar environmental catastrophes. This raises the inevitable question: Are mass extinctions caused by impacts or mantle plume volcanism? The unequivocal correlation between intense volcanism and high-stress assemblages necessitates a review of current impact and mass extinction theories.

  10. Conditions for Circumstellar Disc Formation II: Effects of Initial Cloud Stability and Mass Accretion Rate

    NASA Astrophysics Data System (ADS)

    Machida, Masahiro N.; Matsumoto, Tomoaki; Inutsuka, Shu-ichiro

    2016-09-01

    Disc formation in strongly magnetized cloud cores is investigated using a three-dimensional magnetohydrodynamic simulation with a focus on the effects of the initial cloud stability and the mass accretion rate. The initial cloud stability greatly alters the disc formation process even for prestellar clouds with the same mass-to-flux ratio. A high mass accretion rate onto the disc-forming region is realized in initially unstable clouds, and a large angular momentum is introduced into the circumstellar region in a short time. The region around the protostar has both a thin infalling envelope and a weak magnetic field, which both weaken the effect of magnetic braking. The growth of the rotation-supported disc is promoted in such unstable clouds. Conversely, clouds in an initially near-equilibrium state show lower accretion rates of mass and angular momentum. The angular momentum is transported to the outer envelope before protostar formation. After protostar formation, the circumstellar region has a thick infalling envelope and a strong magnetic field that effectively brake the disc. As a result, disc formation is suppressed when the initial cloud is in a nearly stable state. The density distribution of the initial cloud also affects the disc formation process. Disc growth strongly depends on the initial conditions when the prestellar cloud has a uniform density, whereas there is no significant difference in the disc formation process in prestellar clouds with nonuniform densities.

  11. Effect of probiotics supplementation on bone mineral content and bone mass density.

    PubMed

    Parvaneh, Kolsoom; Jamaluddin, Rosita; Karimi, Golgis; Erfani, Reza

    2014-01-01

    A few studies in animals and a study in humans showed a positive effect of probiotic on bone metabolism and bone mass density. Most of the investigated bacteria were Lactobacillus and Bifidobacterium. The positive results of the probiotics were supported by the high content of dietary calcium and the high amounts of supplemented probiotics. Some of the principal mechanisms include (1) increasing mineral solubility due to production of short chain fatty acids; (2) producing phytase enzyme by bacteria to overcome the effect of mineral depressed by phytate; (3) reducing intestinal inflammation followed by increasing bone mass density; (4) hydrolysing glycoside bond food in the intestines by Lactobacillus and Bifidobacteria. These mechanisms lead to increase bioavailability of the minerals. In conclusion, probiotics showed potential effects on bone metabolism through different mechanisms with outstanding results in the animal model. The results also showed that postmenopausal women who suffered from low bone mass density are potential targets to consume probiotics for increasing mineral bioavailability including calcium and consequently increasing bone mass density. PMID:24587733

  12. Color-magnitude relations within globular cluster systems of giant elliptical galaxies: The effects of globular cluster mass loss and the stellar initial mass function

    SciTech Connect

    Goudfrooij, Paul; Kruijssen, J. M. Diederik E-mail: kruijssen@mpa-garching.mpg.de

    2014-01-01

    Several recent studies have provided evidence for a 'bottom-heavy' stellar initial mass function (IMF) in massive elliptical galaxies. Here we investigate the influence of the IMF shape on the recently discovered color-magnitude relation (CMR) among globular clusters (GCs) in such galaxies. To this end we use calculations of GC mass loss due to stellar and dynamical evolution to evaluate (1) the shapes of stellar mass functions in GCs after 12 Gyr of evolution as a function of current GC mass along with their effects on integrated-light colors and mass-to-light ratios, and (2) their impact on the effects of GC self-enrichment using the 2009 'reference' model of Bailin and Harris. As to the class of metal-poor GCs, we find the observed shape of the CMR (often referred to as the 'blue tilt') to be very well reproduced by Bailin and Harris's reference self-enrichment model once 12 Gyr of GC mass loss is taken into account. The influence of the IMF on this result is found to be insignificant. However, we find that the observed CMR among the class of metal-rich GCs (the 'red tilt') can only be adequately reproduced if the IMF was bottom-heavy (–3.0 ≲ α ≲ –2.3 in dN/dM∝M{sup α}), which causes the stellar mass function at subsolar masses to depend relatively strongly on GC mass. This constitutes additional evidence that the metal-rich stellar populations in giant elliptical galaxies were formed with a bottom-heavy IMF.

  13. Studies on effective atomic numbers, electron densities and mass attenuation coefficients in Au alloys.

    PubMed

    Han, I; Demir, L

    2010-01-01

    The total mass attenuation coefficients (mu/rho) for pure Au and Au99Be1, Au88Ge12, Au95Zn5 alloys were measured at 59.5 and 88.0 keV photon energies. The samples were irradiated with 241Am and 109Cd radioactive point source using transmission arrangement. The gamma- rays were counted by a Si(Li) detector with resolution of 160 eV at 5.9 keV. Total atomic and electronic cross-sections (sigmat and sigmae), effective atomic and electron densities (Zeff and Nel) were determined using the obtained mass attenuation coefficients for investigated Au alloys. The theoretical mass attenuation coefficients of each alloy were estimated using mixture rule. PMID:20421703

  14. A simple modelling of mass diffusion effects on condensation with noncondensable gases for the CATHARE Code

    SciTech Connect

    Coste, P.; Bestion, D.

    1995-09-01

    This paper presents a simple modelling of mass diffusion effects on condensation. In presence of noncondensable gases, the mass diffusion near the interface is modelled using the heat and mass transfer analogy and requires normally an iterative procedure to calculate the interface temperature. Simplifications of the model and of the solution procedure are used without important degradation of the predictions. The model is assessed on experimental data for both film condensation in vertical tubes and direct contact condensation in horizontal tubes, including air-steam, Nitrogen-steam and Helium-steam data. It is implemented in the Cathare code, a french system code for nuclear reactor thermal hydraulics developed by CEA, EDF, and FRAMATOME.

  15. Influence of fluid dynamic conditions on enzymatic hydrolysis of lignocellulosic biomass: Effect of mass transfer rate.

    PubMed

    Wojtusik, Mateusz; Zurita, Mauricio; Villar, Juan C; Ladero, Miguel; Garcia-Ochoa, Felix

    2016-09-01

    The effect of fluid dynamic conditions on enzymatic hydrolysis of acid pretreated corn stover (PCS) has been assessed. Runs were performed in stirred tanks at several stirrer speed values, under typical conditions of temperature (50°C), pH (4.8) and solid charge (20% w/w). A complex mixture of cellulases, xylanases and mannanases was employed for PCS saccharification. At low stirring speeds (<150rpm), estimated mass transfer coefficients and rates, when compared to chemical hydrolysis rates, lead to results that clearly show low mass transfer rates, being this phenomenon the controlling step of the overall process rate. However, for stirrer speed from 300rpm upwards, the overall process rate is controlled by hydrolysis reactions. The ratio between mass transfer and overall chemical reaction rates changes with time depending on the conditions of each run. PMID:27233094

  16. OMOSHI Effect: A New Mechanism for Mass Accretion under the Radiation Pressure in Massive Star Formation

    NASA Astrophysics Data System (ADS)

    Tanaka, Kei; Nakamoto, Taishi

    2009-08-01

    In a massive-star formation process, a high-mass accretion rate is considered to be needed to overcome the strong radiation pressure at the dust sublimation front. We examined the accretion structure near the dust sublimation front and found a new mechanism to overcome this radiation pressure. The weight of the accumulated mass in a stagnant flow near the dust sublimation front helps with the mass accretion. We call this mechanism the ``OMOSHI effect,'' where OMOSHI is an acronym for ``One Mechanism for Overcoming Stellar High radiation pressure by weight.'' OMOSHI is also a Japanese noun meaning a weight that is put on something to prevent it from moving. This mechanism relaxes the condition for the massive star formation.

  17. The Effect of Manipulating Subject Mass on Lower Extremity Torque Patterns During Locomotion

    NASA Technical Reports Server (NTRS)

    DeWitt, John K.; Cromwell, Ronita L.; Hagan, R. Donald

    2007-01-01

    During locomotion, humans adapt their motor patterns to maintain coordination despite changing conditions (Reisman et al., 2005). Bernstein (1967) proposed that in addition to the present state of a given joint, other factors, including limb inertia and velocity, must be taken into account to allow proper motion to occur. During locomotion with added mass counterbalanced using vertical suspension to maintain body weight, vertical ground reaction forces (GRF's) increase during walking but decrease during running, suggesting that adaptation may be velocity-specific (De Witt et al., 2006). It is not known, however, how lower extremity joint torques adapt to changes in inertial forces. The purpose of this investigation was to examine the effects of increasing body mass while maintaining body weight upon lower-limb joint torque during walking and running. We hypothesized that adaptations in joint torque patterns would occur with the addition of body mass.

  18. The Effect of Mission Location on Mission Costs and Equivalent System Mass

    NASA Technical Reports Server (NTRS)

    Fisher, John W.; Levri, Julie A.; Jones, Harry W.

    2003-01-01

    Equivalent System Mass (ESM) is used by the Advanced Life Support (ALS) community to quantify mission costs of technologies for space applications (Drysdale et al, 1999, Levri et al, 2000). Mass is used as a cost measure because the mass of an object determines propulsion (acceleration) cost (i.e. amount of fuel needed), and costs relating to propulsion dominate mission cost. Mission location drives mission cost because acceleration is typically required to initiate and complete a change in location. Total mission costs may be reduced by minimizing the mass of materials that must be propelled to each distinct location. In order to minimize fuel requirements for missions beyond low-Earth orbit (LEO), the hardware and astronauts may not all go to the same location. For example, on a Lunar or Mars mission, some of the hardware or astronauts may stay in orbit while the rest of the hardware and astronauts descend to the planetary surface. In addition, there may be disposal of waste or used hardware at various mission locations to avoid propulsion of mass that is no longer needed in the mission. This paper demonstrates how using location factors in the calculation of ESM can account for the effects of various acceleration events and can improve the accuracy and value of the ESM metric to mission planners. Even a mission with one location can benefit from location factor analysis if the alternative technologies under consideration consume resources at different rates. For example, a mission that regenerates resources will have a relatively constant mass compared to one that uses consumables and vents/discards mass along the way. This paper shows examples of how location factors can affect ESM calculations and how the inclusion of location factors can change the relative value of technologies being considered for development.

  19. Cosmology with galaxy clusters: Systematic effects in the halo mass function

    NASA Astrophysics Data System (ADS)

    Paranjape, Aseem

    2014-07-01

    We investigate potential systematic effects in constraining the amplitude of primordial fluctuations σ8 arising from the choice of halo mass function in the likelihood analysis of current and upcoming galaxy cluster surveys. We study the widely used N-body simulation fit of Tinker et al. (T08) and, as an alternative, the recently proposed analytical model of excursion set peaks (ESP). We first assess the relative bias between these prescriptions when constraining σ8 by sampling the ESP mass function to generate mock catalogs and using the T08 fit to analyze them, for various choices of survey selection threshold, mass definition and statistical priors. To assess the level of absolute bias in each prescription, we then repeat the analysis on dark matter halo catalogs in N-body simulations designed to mimic the mass distribution in the current data release of Planck Sunyaev-Zel'dovich clusters. This N-body analysis shows that using the T08 fit without accounting for the scatter introduced when converting between mass definitions (alternatively, the scatter induced by errors on the parameters of the fit) can systematically overestimate the value of σ8 by as much as 2σ for current data, while analyses that account for this scatter should be close to unbiased in σ8. With an increased number of objects as expected in upcoming data releases, regardless of accounting for scatter, the T08 fit could overestimate the value of σ8 by ˜1.5σ. The ESP mass function leads to systematically more biased but comparable results. A strength of the ESP model is its natural prediction of a weak nonuniversality in the mass function which closely tracks the one measured in simulations and described by the T08 fit. We suggest that it might now be prudent to build new unbiased ESP-based fitting functions for use with the larger data sets of the near future.

  20. 3D viscosity maps for Greenland and effect on GRACE mass balance estimates

    NASA Astrophysics Data System (ADS)

    van der Wal, Wouter; Xu, Zheng

    2016-04-01

    The GRACE satellite mission measures mass loss of the Greenland ice sheet. To correct for glacial isostatic adjustment numerical models are used. Although generally found to be a small signal, the full range of possible GIA models has not been explored yet. In particular, low viscosities due to a wet mantle and high temperatures due to the nearby Iceland hotspot could have a significant effect on GIA gravity rates. The goal of this study is to present a range of possible viscosity maps, and investigate the effect on GRACE mass balance estimates. Viscosity is derived using flow laws for olivine. Mantle temperature is computed from global seismology models, based on temperature derivatives for different mantle compositions. An indication for grain sizes is obtained by xenolith findings at a few locations. We also investigate the weakening effect of the presence of melt. To calculate gravity rates, we use a finite-element GIA model with the 3D viscosity maps and the ICE-5G loading history. GRACE mass balances for mascons in Greenland are derived with a least-squares inversion, using separate constraints for the inland and coastal areas in Greenland. Biases in the least-squares inversion are corrected using scale factors estimated from a simulation based on a surface mass balance model (Xu et al., submitted to The Cryosphere). Model results show enhanced gravity rates in the west and south of Greenland with 3D viscosity maps, compared to GIA models with 1D viscosity. The effect on regional mass balance is up to 5 Gt/year. Regional low viscosity can make present-day gravity rates sensitivity to ice thickness changes in the last decades. Therefore, an improved ice loading history for these time scales is needed.

  1. Strain engineering band gap, effective mass and anisotropic Dirac-like cone in monolayer arsenene

    NASA Astrophysics Data System (ADS)

    Wang, Can; Xia, Qinglin; Nie, Yaozhuang; Rahman, Mavlanjan; Guo, Guanghua

    2016-03-01

    The electronic properties of two-dimensional puckered arsenene have been investigated using first-principles calculations. The effective mass of electrons exhibits highly anisotropic dispersion in intrinsic puckered arsenene. Futhermore, we find that out-of-plane strain is effective in tuning the band gap, as the material undergoes the transition into a metal from an indirect gap semiconductor. Remarkably, we observe the emergence of Dirac-like cone with in-plane strain. Strain modulates not only the band gap of monolayer arsenene, but also the effective mass. Our results present possibilities for engineering the electronic properties of two-dimensional puckered arsenene and pave a way for tuning carrier mobility of future electronic devices.

  2. Meta-atom cluster acoustic metamaterial with broadband negative effective mass density

    SciTech Connect

    Chen, Huaijun; Zhai, Shilong; Ding, Changlin; Liu, Song; Luo, Chunrong; Zhao, Xiaopeng

    2014-02-07

    We design a resonant meta-atom cluster, via which a two-dimensional (2D) acoustic metamaterial (AM) with broadband negative effective mass density from 1560 Hz to 5580 Hz is fabricated. Experimental results confirm that there is only weak interaction among the meta-atoms in the cluster. And then the meta-atoms in the cluster independently resonate, resulting in the cluster becoming equivalent to a broadband resonance unit. Extracted effective refractive indices from reflection and transmission measurements of the 2D AM appear to be negative from 1500 Hz to 5480 Hz. The broadband negative refraction has also been demonstrated by our further experiments. We expect that this meta-atom cluster AM will significantly contribute to the design of broadband negative effective mass density AM.

  3. [Study on spectrum analysis of X-ray based on rotational mass effect in special relativity].

    PubMed

    Yu, Zhi-Qiang; Xie, Quan; Xiao, Qing-Quan

    2010-04-01

    Based on special relativity, the formation mechanism of characteristic X-ray has been studied, and the influence of rotational mass effect on X-ray spectrum has been given. A calculation formula of the X-ray wavelength based upon special relativity was derived. Error analysis was carried out systematically for the calculation values of characteristic wavelength, and the rules of relative error were obtained. It is shown that the values of the calculation are very close to the experimental values, and the effect of rotational mass effect on the characteristic wavelength becomes more evident as the atomic number increases. The result of the study has some reference meaning for the spectrum analysis of characteristic X-ray in application. PMID:20545180

  4. Copernicus ultraviolet observations of mass-loss effects in O and B stars

    NASA Technical Reports Server (NTRS)

    Snow, T. P., Jr.; Morton, D. C.

    1976-01-01

    Far-UV spectra of 47 O, B, and A stars obtained with the Copernicus satellite are examined for P Cygni profiles. For all 40 stars with displaced absorption lines, values are given for the velocities of the short-wavelength edge, the line center, and the emission peak (if present). Parts of the spectra of 42 stars are reproduced, evidence for mass motions in ground-based spectra is discussed, and the best available data are summarized on the wavelengths and oscillator strengths of most lines likely to show mass-loss effects in either visual or UV spectra. The main conclusions are that: (1) the far-UV transitions, especially resonance lines, show that mass flow is present over a much wider group of stars than revealed by visible data on subordinate lines; (2) most of the line shifts imply mass motion away from the stars; (3) mass flow occurs in all but one star brighter than a bolometric magnitude of -6.0; and (4) the observed terminal velocities generally exhibit no significant correlation with temperature, luminosity, gravity, rotational velocity, or line strength.

  5. Theoretical approach for enhanced mass transfer effects in-duct flue gas desulfurization processes

    SciTech Connect

    Not Available

    1990-08-22

    While developing dry sorbent duct injection flue gas desulfurization processes may offer significant improvement in capital cost and process simplicity compared to wet scrubbing systems, the economics of this technology can be improved significantly by an improvement in sorbent utilization. While a general understanding of the mechanism by which the sorbents operate is known, a much more detailed knowledge of reaction rate-controlling phenomena, the role of inherent reactivity, and mass transfer effects and their interaction in needed. Objectives of this project are threefold: 1. Mass transfer investigation--determine the controlling physical and chemical processes that limit sorbent utilization. In particular, determine whether mass transfer is a controlling factor in in-duct flue gas desulfurization and establish the relative contributions of gas- and liquid-phase mass transfer and inherent sorbent reactivity. 2. Field test support--evaluate various sorbents, operating conditions and process schemes to support large-scale field testings at Meredosia and Beverly. 3. Mass transfer enhancement--examine various techniques that will enable sorbent utilization rates of at least 75 percent to be achieved. Sorbents investigated were Ca(OH){sub 2}, Mississippi hydrate and Mississippi slaked lime. Epsom Salt was investigated as an additive. Agglomeration of Ca(OH){sub 2} solids was also investigated. 3 refs., 92 figs., 23 tabs.

  6. Effect of the equation of state on the maximum mass of differentially rotating neutron stars

    NASA Astrophysics Data System (ADS)

    Studzińska, A. M.; Kucaba, M.; Gondek-Rosińska, D.; Villain, L.; Ansorg, M.

    2016-08-01

    Knowing the value of the maximum mass of a differentially rotating relativistic star is a key-step toward the understanding of the signals to be expected from the merger of binary neutron stars, one of the most awaited alternative sources of gravitational waves after binary black holes. In this article, we study the effects of differential rotation and of the equation of state on the maximum mass of rotating neutron stars modeled as relativistic polytropes with various adiabatic indices. Calculations are performed using a highly accurate numerical code, based on a multi-domain spectral method. We thoroughly explore the parameter space and determine how the maximum mass depends on the stiffness, on the degree of differential rotation and on the maximal density, taking into account all the types of solutions that were proven to exist in a preceding article (Ansorg et al. 2009). The highest increase with respect to the maximum mass for non-rotating stars with the same equation of state is reached for a moderate stiffness. With differential rotation, the maximum mass can even be 3-4 times higher than it is for static stars. This result may have important consequences for the gravitational wave signal from coalescing neutron star binaries or for some supernovae events.

  7. Negative effective mass density of acoustic metamaterial plate decorated with low frequency resonant pillars

    NASA Astrophysics Data System (ADS)

    Oudich, Mourad; Djafari-Rouhani, Bahram; Pennec, Yan; Assouar, M. Badreddine; Bonello, Bernard

    2014-11-01

    We investigate the elastic wave dispersion by a phononic metamaterial plate containing low frequency resonator stubs arranged periodically over the plate. We show that this system not only provides stop bands for wavelengths much larger than the periodicity but also displays negative behavior of its effective mass density under the homogenization assumption. A numerical method is used to calculate the plate's effective dynamic mass density as function of the frequency where the metamaterial is considered as homogeneous plate for these large wavelengths. Strong anisotropy of the effective mass density matrix is observed around the resonance frequencies where the gaps are opened. In these regions, we demonstrate that the effective matrix density components take negative values. For each of these components, the negative behavior is studied by taking into account the polarization of the involved resonant modes as well as their associated partial band gaps opened for each specific Lamb symmetry modes. We found that coupling between Lamb waves and resonant modes strongly affects the effective density of the whole plate especially in the coupling frequency regions of the gaps.

  8. Contrasting the Effects of Maternal and Behavioral Characteristics on Fawn Birth Mass in White-Tailed Deer

    PubMed Central

    2015-01-01

    Maternal care influences offspring quality and can improve a mother’s inclusive fitness. However, improved fitness may only occur when offspring quality (i.e., offspring birth mass) persists throughout life and enhances survival and/or reproductive success. Although maternal body mass, age, and social rank have been shown to influence offspring birth mass, the inter-dependence among these variables makes identifying causation problematic. We established that fawn birth mass was related to adult body mass for captive male and female white-tailed deer (Odocoileus virginianus), thus maternal care should improve offspring fitness. We then used path analysis to identify which maternal characteristic(s) most influenced fawn birth mass of captive female white-tailed deer. Maternal age, body mass and social rank had varying effects on fawn birth mass. Maternal body mass displayed the strongest direct effect on fawn birth mass, followed by maternal age and social rank. Maternal body mass had a greater effect on social rank than age. The direct path between social rank and fawn birth mass may indicate dominance as an underlying mechanism. Our results suggest that heavier mothers could use dominance to improve access to resources, resulting in increased fitness through production of heavier offspring. PMID:26288141

  9. Communication: An effective linear-scaling atomic-orbital reformulation of the random-phase approximation using a contracted double-Laplace transformation

    NASA Astrophysics Data System (ADS)

    Schurkus, Henry F.; Ochsenfeld, Christian

    2016-01-01

    An atomic-orbital (AO) reformulation of the random-phase approximation (RPA) correlation energy is presented allowing to reduce the steep computational scaling to linear, so that large systems can be studied on simple desktop computers with fully numerically controlled accuracy. Our AO-RPA formulation introduces a contracted double-Laplace transform and employs the overlap-metric resolution-of-the-identity. First timings of our pilot code illustrate the reduced scaling with systems comprising up to 1262 atoms and 10 090 basis functions.

  10. Generalized Korteweg-de Vries equation induced from position-dependent effective mass quantum models and mass-deformed soliton solution through inverse scattering transform

    SciTech Connect

    Ganguly, A. E-mail: aganguly@maths.iitkgp.ernet.in; Das, A.

    2014-11-15

    We consider one-dimensional stationary position-dependent effective mass quantum model and derive a generalized Korteweg-de Vries (KdV) equation in (1+1) dimension through Lax pair formulation, one being the effective mass Schrödinger operator and the other being the time-evolution of wave functions. We obtain an infinite number of conserved quantities for the generated nonlinear equation and explicitly show that the new generalized KdV equation is an integrable system. Inverse scattering transform method is applied to obtain general solution of the nonlinear equation, and then N-soliton solution is derived for reflectionless potentials. Finally, a special choice has been made for the variable mass function to get mass-deformed soliton solution. The influence of position and time-dependence of mass and also of the different representations of kinetic energy operator on the nature of such solitons is investigated in detail. The remarkable features of such solitons are demonstrated in several interesting figures and are contrasted with the conventional KdV-soliton associated with constant-mass quantum model.

  11. An effective selection method for low-mass active black holes and first spectroscopic identification

    NASA Astrophysics Data System (ADS)

    Morokuma, Tomoki; Tominaga, Nozomu; Tanaka, Masaomi; Yasuda, Naoki; Furusawa, Hisanori; Taniguchi, Yuki; Kato, Takahiro; Jiang, Ji-an; Nagao, Tohru; Kuncarayakti, Hanindyo; Morokuma-Matsui, Kana; Ikeda, Hiroyuki; Blinnikov, Sergei; Nomoto, Ken'ichi; Kokubo, Mitsuru; Doi, Mamoru

    2016-06-01

    We present a new method for effectively selecting objects which may be low-mass active black holes (BHs) at galaxy centers using high-cadence optical imaging data, and our first spectroscopic identification of an active 2.7 × 106 M⊙ BH at z = 0.164. This active BH was originally selected due to its rapid optical variability, from a few hours to a day, based on Subaru Hyper Suprime-Cam g-band imaging data taken with a 1 hr cadence. Broad and narrow Hα lines and many other emission ones are detected in our optical spectra taken with Subaru FOCAS, and the BH mass is measured via the broad Hα emission line width (1880 km s-1) and luminosity (4.2 × 1040 erg s-1) after careful correction to the atmospheric absorption around 7580-7720 Å. We measure the Eddington ratio and find it to be as low as 0.05, considerably smaller than those in a previous SDSS sample with similar BH mass and redshift, which indicates one of the special potentials of our Subaru survey. The g - r color and morphology of the extended component indicate that the host galaxy is a star-forming galaxy. We also show the effectiveness of our variability selection for low-mass active BHs.

  12. An effective selection method for low-mass active black holes and first spectroscopic identification

    NASA Astrophysics Data System (ADS)

    Morokuma, Tomoki; Tominaga, Nozomu; Tanaka, Masaomi; Yasuda, Naoki; Furusawa, Hisanori; Taniguchi, Yuki; Kato, Takahiro; Jiang, Ji-an; Nagao, Tohru; Kuncarayakti, Hanindyo; Morokuma-Matsui, Kana; Ikeda, Hiroyuki; Blinnikov, Sergei; Nomoto, Ken'ichi; Kokubo, Mitsuru; Doi, Mamoru

    2016-04-01

    We present a new method for effectively selecting objects which may be low-mass active black holes (BHs) at galaxy centers using high-cadence optical imaging data, and our first spectroscopic identification of an active 2.7 × 106 M⊙ BH at z = 0.164. This active BH was originally selected due to its rapid optical variability, from a few hours to a day, based on Subaru Hyper Suprime-Cam g-band imaging data taken with a 1 hr cadence. Broad and narrow Hα lines and many other emission ones are detected in our optical spectra taken with Subaru FOCAS, and the BH mass is measured via the broad Hα emission line width (1880 km s-1) and luminosity (4.2 × 1040 erg s-1) after careful correction to the atmospheric absorption around 7580-7720 Å. We measure the Eddington ratio and find it to be as low as 0.05, considerably smaller than those in a previous SDSS sample with similar BH mass and redshift, which indicates one of the special potentials of our Subaru survey. The g - r color and morphology of the extended component indicate that the host galaxy is a star-forming galaxy. We also show the effectiveness of our variability selection for low-mass active BHs.

  13. Effect of radiator position and mass flux on the dryer room heat transfer rate

    NASA Astrophysics Data System (ADS)

    Mirmanto, M.; Sulistyowati, E. D.; Okariawan, I. D. K.

    A room radiator as usually used in cold countries, is actually able to be used as a heat source to dry goods, especially in the rainy season where the sun seldom shines due to much rain and cloud. Experiments to investigate effects of radiator position and mass flux on heat transfer rate were performed. This study is to determine the best position of the radiator and the optimum mass flux. The radiator used was a finned radiator made of copper pipes and aluminum fins with an overall dimension of 220 mm × 50 mm × 310 mm. The prototype room was constructed using plywood and wood frame with an overall size of 1000 mm × 1000 mm × 1000 mm. The working fluid was heated water flowing inside the radiator and air circulating naturally inside the prototype room. The nominal mass fluxes employed were 800, 900 and 1000 kg/m2 s. The water was kept at 80 °C at the radiator entrance, while the initial air temperature inside the prototype room was 30 °C. Three positions of the radiator were examined. The results show that the effect of the mass flux on the forced and free convection heat transfer rate is insignificant but the radiator position strongly affects the heat transfer rate for both forced and free convection.

  14. Determination of effective axion masses in the helium-3 buffer of CAST

    SciTech Connect

    Ruz, J

    2011-11-18

    The CERN Axion Solar Telescope (CAST) is a ground based experiment located in Geneva (Switzerland) searching for axions coming from the Sun. Axions, hypothetical particles that not only could solve the strong CP problem but also be one of the favored candidates for dark matter, can be produced in the core of the Sun via the Primakoff effect. They can be reconverted into X-ray photons on Earth in the presence of strong electromagnetic fields. In order to look for axions, CAST points a decommissioned LHC prototype dipole magnet with different X-ray detectors installed in both ends of the magnet towards the Sun. The analysis of the data acquired during the first phase of the experiment yielded the most restrictive experimental upper limit on the axion-to-photon coupling constant for axion masses up to about 0.02 eV/c{sup 2}. During the second phase, CAST extends its mass sensitivity by tuning the electron density present in the magnetic field region. Injecting precise amounts of helium gas has enabled CAST to look for axion masses up to 1.2 eV/c{sup 2}. This paper studies the determination of the effective axion masses scanned at CAST during its second phase. The use of a helium gas buffer at temperatures of 1.8 K has required a detailed knowledge of the gas density distribution. Complete sets of computational fluid dynamic simulations validated with experimental data have been crucial to obtain accurate results.

  15. Anomalous coupling, top-mass and parton-shower effects in W + W - production

    NASA Astrophysics Data System (ADS)

    Bellm, J.; Gieseke, S.; Greiner, N.; Heinrich, G.; Plätzer, S.; Reuschle, C.; von Soden-Fraunhofen, J. F.

    2016-05-01

    We calculate the process ppto {W}+{W}-to {e}+{ν}_e{μ}-{overline{ν}}_{μ } at NLO QCD, including also effective field theory (EFT) operators mediating the ggW + W - interaction, which first occur at dimension eight. We further combine the NLO and EFT matrix elements produced by G oS am with the H erwig7/M atchbox framework, which offers the possibility to study the impact of a parton shower. We assess the effects of the anomalous couplings by comparing them to top-mass effects as well as uncertainties related to variations of the renormalisation, factorisation and hard shower scales.

  16. Negative effect of the arthropod parasite, Sarcoptes scabiei, on testes mass in Iberian ibex, Capra pyrenaica.

    PubMed

    Sarasa, Mathieu; Serrano, Emmanuel; Soriguer, Ramón C; Granados, José-Enrique; Fandos, Paulino; Gonzalez, Georges; Joachim, Jean; Pérez, Jesús M

    2011-02-10

    Testes mass is a key factor in male reproductive success and is potentially exposed to so-called 'parasitic castration'. This is the result of the direct destruction or alteration of reproductive cell lineages (parasitic castration sensu stricto), or the indirect detrimental effects - for example, via body condition - on the ability of progenitors to produce or rear offspring (parasitic castration sensu lato). There are enormous gaps in our knowledge on the effects of parasites on the testes of wild mammals and in an attempt to rectify this dearth of data we examined the relationship between the skin parasite Sarcoptes scabiei and testes mass in Iberian ibex Capra pyrenaica. We considered data from 222 males that were culled in the population from the Sierra Nevada in Spain. Our results provide evidence that sarcoptic mange is associated with reduced size-corrected testes mass in Iberian ibex which supports the hypothesis that parasitism is a determining factor in gonad plasticity in male mammals. We discuss several hypothetical causes of this relationship and highlight the need to deepen the sub-lethal effects of pathogens if we are to accurately understand their modulator effects on host population dynamics. PMID:21074328

  17. Effects of first-order correction to eikonal approximation in the analysis of {sup 9}Be({sup 15}C,{sup 14}C + n){sup 9}Be stripping reaction

    SciTech Connect

    Singh, M.; Kharab, R.; Singh, R. M.

    2015-09-15

    We have studied the effects of the first-order correction to the eikonal approximation for {sup 9}Be({sup 15}C,{sup 14}C + n){sup 9}Be stripping reactions at 54A MeV incident energy and have found that the correction term slightly changes the tail of the longitudinal momentum distribution of the core fragment.

  18. APPROXIMATING LIGHT RAYS IN THE SCHWARZSCHILD FIELD

    SciTech Connect

    Semerák, O.

    2015-02-10

    A short formula is suggested that approximates photon trajectories in the Schwarzschild field better than other simple prescriptions from the literature. We compare it with various ''low-order competitors'', namely, with those following from exact formulas for small M, with one of the results based on pseudo-Newtonian potentials, with a suitably adjusted hyperbola, and with the effective and often employed approximation by Beloborodov. Our main concern is the shape of the photon trajectories at finite radii, yet asymptotic behavior is also discussed, important for lensing. An example is attached indicating that the newly suggested approximation is usable—and very accurate—for practically solving the ray-deflection exercise.

  19. On the Effective Thermal Conductivity of Frost Considering Mass Diffusion and Eddy Convection

    NASA Technical Reports Server (NTRS)

    Kandula, Max

    2010-01-01

    A physical model for the effective thermal conductivity of water frost is proposed for application to the full range of frost density. The proposed model builds on the Zehner-Schlunder one-dimensional formulation for porous media appropriate for solid-to-fluid thermal conductivity ratios less than about 1000. By superposing the effects of mass diffusion and eddy convection on stagnant conduction in the fluid, the total effective thermal conductivity of frost is shown to be satisfactorily described. It is shown that the effects of vapor diffusion and eddy convection on the frost conductivity are of the same order. The results also point out that idealization of the frost structure by cylindrical inclusions offers a better representation of the effective conductivity of frost as compared to spherical inclusions. Satisfactory agreement between the theory and the measurements for the effective thermal conductivity of frost is demonstrated for a wide range of frost density and frost temperature.

  20. SUSY Threshold Effects on Quark and Lepton Masses at the GUT Scale

    SciTech Connect

    Antusch, Stefan

    2008-11-23

    We discuss the impact of supersymmetric (SUSY) threshold corrections on the values of the running quark and charged lepton masses at the GUT scale within the large tan{beta} regime of the MSSM. In addition to the typically dominant SUSY QCD contributions for the quarks, we also include the electroweak contributions for quarks and leptons which can have significant effects. We provide the GUT scale ranges of quark and charged lepton Yukawa couplings as well as of the ratios m{sub {mu}}/m{sub s}, m{sub e}/m{sub d}, y{sub {tau}}/y{sub b} and y{sub t}/y{sub b} for three example ranges of SUSY parameters and discuss how the enlarged ranges due to threshold effects might open up new possibilities for constructing GUT models of fermion masses and mixings. This is a brief summary of the work of Ref. [1].