Evaluation of the mass transfer process on thin layer drying of papaya seeds from the perspective of diffusive models

NASA Astrophysics Data System (ADS)

Dotto, Guilherme Luiz; Meili, Lucas; Tanabe, Eduardo Hiromitsu; Chielle, Daniel Padoin; Moreira, Marcos Flávio Pinto

2018-02-01

The mass transfer process that occurs in the thin layer drying of papaya seeds was studied under different conditions. The external mass transfer resistance and the dependence of effective diffusivity ( D EFF ) in relation to the moisture ratio ( \\overline{MR} ) and temperature ( T) were investigated from the perspective of diffusive models. It was verified that the effective diffusivity was affected by the moisture content and temperature. A new correlation was proposed for drying of papaya seeds in order to describe these influences. Regarding the use of diffusive models, the results showed that, at conditions of low drying rates ( T ≤ 70 °C), the external mass transfer resistance, as well as the dependence of the effective diffusivity with respect to the temperature and moisture content should be considered. At high drying rates ( T > 90 °C), the dependence of the effective diffusivity with respect to the temperature and moisture content can be neglected, but the external mass transfer resistance was still considerable in the range of air velocities used in this work.

The kinetic energy operator for distance-dependent effective nuclear masses: Derivation for a triatomic molecule.

PubMed

Khoma, Mykhaylo; Jaquet, Ralph

2017-09-21

The kinetic energy operator for triatomic molecules with coordinate or distance-dependent nuclear masses has been derived. By combination of the chain rule method and the analysis of infinitesimal variations of molecular coordinates, a simple and general technique for the construction of the kinetic energy operator has been proposed. The asymptotic properties of the Hamiltonian have been investigated with respect to the ratio of the electron and proton mass. We have demonstrated that an ad hoc introduction of distance (and direction) dependent nuclear masses in Cartesian coordinates preserves the total rotational invariance of the problem. With the help of Wigner rotation functions, an effective Hamiltonian for nuclear motion can be derived. In the derivation, we have focused on the effective trinuclear Hamiltonian. All necessary matrix elements are given in closed analytical form. Preliminary results for the influence of non-adiabaticity on vibrational band origins are presented for H 3 + .

Wave packet dynamics for a system with position and time-dependent effective mass in an infinite square well

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

Vubangsi, M.; Tchoffo, M.; Fai, L. C.

The problem of a particle with position and time-dependent effective mass in a one-dimensional infinite square well is treated by means of a quantum canonical formalism. The dynamics of a launched wave packet of the system reveals a peculiar revival pattern that is discussed. .

Bargmann's theorem and position-dependent effective mass

NASA Astrophysics Data System (ADS)

Kawamura, Kiyoshi; Brown, Ronald A.

1988-03-01

The physical significance of Galilean transformations applied to effective-mass (EM) equations for Bloch electrons in Wannier representation is discussed and contrasted with that of Galilean coordinate transformations applied to the free-particle Schrödinger equation. Mass constraints imposed on the latter by Bargmann's (1954) superselection rule do not extend to the EM, and criticisms of the position-dependent EM concept which have invoked Bargmann's theorem are shown to be without foundation. Other criticisms concerning the nonuniqueness and non-Hermiticity of effective Hamiltonians which employ this concept to describe crystals of graded composition are discussed, and it is argued that the problems are associated with the heuristic nature of the virtual-crystal model which is adopted rather than with the position-dependent EM.

Study of the scan uniformity from an i-CAT cone beam computed tomography dental imaging system.

PubMed

Bryant, J A; Drage, N A; Richmond, S

2008-10-01

As part of an ongoing programme to improve diagnosis and treatment planning relevant to implant placement, orthodontic treatment and dentomaxillofacial surgery, a study has been made of the spatial accuracy and density response of an i-CAT, a cone beam CT (CBCT) dental imaging system supplied by Imaging Sciences International Inc. Custom-made phantoms using acrylic sheet and water were used for measurements on spatial accuracy, density response and noise. The measurements were made over a period of several months on a clinical machine rather than on a machine dedicated to research. Measurements on a precision grid showed the spatial accuracy to be universally within the tolerance of +/-1 pixel. The density response and the noise in the data were found to depend strongly on the mass in the slice being scanned. The density response was subject to two effects. The first effect changes the whole slice uniformly and linearly depends on the total mass in the slice. The second effect exists when there is mass outside the field of view, dubbed the "exo-mass" effect. This effect lowers the measured CT number rapidly at the scan edge furthest from the exo-mass and raises it on the adjacent edge. The noise also depended quasi-linearly on the mass in the slice. Some general performance rules were drafted to describe these effects and a preliminary correction algorithm was constructed.

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.

Quasi-stationary states of an electron with linearly dependent effective mass in an open nanostructure within transmission coefficient and S-matrix methods

NASA Astrophysics Data System (ADS)

Seti, Julia; Tkach, Mykola; Voitsekhivska, Oxana

2018-03-01

The exact solutions of the Schrödinger equation for a double-barrier open semiconductor plane nanostructure are obtained by using two different approaches, within the model of the rectangular potential profile and the continuous position-dependent effective mass of the electron. The transmission coefficient and scattering matrix are calculated for the double-barrier nanostructure. The resonance energies and resonance widths of the electron quasi-stationary states are analyzed as a function of the size of the near-interface region between wells and barriers, where the effective mass linearly depends on the coordinate. It is established that, in both methods, the increasing size affects in a qualitatively similar way the spectral characteristics of the states, shifting the resonance energies into the low- or high-energy region and increasing the resonance widths. It is shown that the relative difference of resonance energies and widths of a certain state, obtained in the model of position-dependent effective mass and in the widespread abrupt model in physically correct range of near-interface sizes, does not exceed 0.5% and 5%, respectively, independently of the other geometrical characteristics of the structure.

Gravitational lensing of supernovae by dark matter candidates of mass M greater than about 0.001 solar masses

NASA Technical Reports Server (NTRS)

Wagoner, Robert V.; Linder, Eric V.

1987-01-01

A review is presented concerning the gravitational lensing of supernovae by intervening condensed objects, including dark matter candidates such as dim stars and black holes. the expansion of the supernova beam within the lens produces characteristic time-dependent amplification and polarization which depend upon the mass of the lens. The effects of the shearing of the beam due to surrounding masses are considered, although the study of these effects is confined to isolated masses whose size is much less than that of the supernova (about 10 to the 15th cm). Equations for the effects of lensing and graphs comparing these effects in different classes of supernovae are compared. It is found that candidates for lensing would be those supernovae at least as bright as their parent galaxy, or above the range of luminosities expected for their spectral class.

Target mass effects in parton quasi-distributions

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

Radyushkin, A. V.

We study the impact of non-zero (and apparently large) value of the nucleon mass M on the shape of parton quasi-distributions Q(y,p 3), in particular on its change with the change of the nucleon momentum p 3. We observe that the usual target-mass corrections induced by the M-dependence of the twist-2 operators are rather small. Moreover, we show that within the framework based on parametrizations by transverse momentum dependent distribution functions (TMDs) these corrections are canceled by higher-twist contributions. Lastly, we identify a novel source of kinematic target-mass dependence of TMDs and build models corrected for such dependence. We findmore » that resulting changes may be safely neglected for p 3≳2M.« less

Target mass effects in parton quasi-distributions

DOE PAGES

Radyushkin, A. V.

2017-05-11

We study the impact of non-zero (and apparently large) value of the nucleon mass M on the shape of parton quasi-distributions Q(y,p 3), in particular on its change with the change of the nucleon momentum p 3. We observe that the usual target-mass corrections induced by the M-dependence of the twist-2 operators are rather small. Moreover, we show that within the framework based on parametrizations by transverse momentum dependent distribution functions (TMDs) these corrections are canceled by higher-twist contributions. Lastly, we identify a novel source of kinematic target-mass dependence of TMDs and build models corrected for such dependence. We findmore » that resulting changes may be safely neglected for p 3≳2M.« less

Composite system in rotationally invariant noncommutative phase space

NASA Astrophysics Data System (ADS)

Gnatenko, Kh. P.; Tkachuk, V. M.

2018-03-01

Composite system is studied in noncommutative phase space with preserved rotational symmetry. We find conditions on the parameters of noncommutativity on which commutation relations for coordinates and momenta of the center-of-mass of composite system reproduce noncommutative algebra for coordinates and momenta of individual particles. Also, on these conditions, the coordinates and the momenta of the center-of-mass satisfy noncommutative algebra with effective parameters of noncommutativity which depend on the total mass of the system and do not depend on its composition. Besides, it is shown that on these conditions the coordinates in noncommutative space do not depend on mass and can be considered as kinematic variables, the momenta are proportional to mass as it has to be. A two-particle system with Coulomb interaction is studied and the corrections to the energy levels of the system are found in rotationally invariant noncommutative phase space. On the basis of this result the effect of noncommutativity on the spectrum of exotic atoms is analyzed.

Dynamical Friction in Multi-component Evolving Globular Clusters

NASA Astrophysics Data System (ADS)

Alessandrini, Emiliano; Lanzoni, Barbara; Miocchi, Paolo; Ciotti, Luca; Ferraro, Francesco R.

2014-11-01

We use the Chandrasekhar formalism and direct N-body simulations to study the effect of dynamical friction on a test object only slightly more massive than the field stars, orbiting a spherically symmetric background of particles with a mass spectrum. The main goal is to verify whether the dynamical friction time (t DF) develops a non-monotonic radial dependence that could explain the bimodality of the blue straggler radial distributions observed in globular clusters. In these systems, in fact, relaxation effects lead to a mass and velocity radial segregation of the different mass components, so that mass-spectrum effects on t DF are expected to be dependent on radius. We find that in spite of the presence of different masses, t DF is always a monotonic function of radius, at all evolutionary times and independently of the initial concentration of the simulated cluster. This is because the radial dependence of t DF is largely dominated by the total mass density profile of the background stars (which is monotonically decreasing with radius). Hence, a progressive temporal erosion of the blue straggler star (BSS) population at larger and larger distances from the cluster center remains the simplest and the most likely explanation of the shape of the observed BSS radial distributions, as suggested in previous works. We also confirm the theoretical expectation that approximating a multi-mass globular cluster as made of (averaged) equal-mass stars can lead to significant overestimations of t DF within the half-mass radius.

Plasmon mass scale in two-dimensional classical nonequilibrium gauge theory

NASA Astrophysics Data System (ADS)

Lappi, T.; Peuron, J.

2018-02-01

We study the plasmon mass scale in classical gluodynamics in a two-dimensional configuration that mimics the boost-invariant initial color fields in a heavy-ion collision. We numerically measure the plasmon mass scale using three different methods: a hard thermal loop (HTL) expression involving the quasiparticle spectrum constructed from Coulomb gauge field correlators, an effective dispersion relation, and the measurement of oscillations between electric and magnetic energies after introducing a spatially uniform perturbation to the electric field. We find that the HTL expression and the uniform electric field measurement are in rough agreement. The effective dispersion relation agrees with other methods within a factor of 2. We also study the dependence on time and occupation number, observing similar trends as in three spatial dimensions, where a power-law dependence sets in after an occupation-number-dependent transient time. We observe a decrease of the plasmon mass squared as t-1 / 3 at late times.

Insulin Resistance Negatively Influences the Muscle-Dependent IGF-1-Bone Mass Relationship in Premenarcheal Girls.

PubMed

Kindler, J M; Pollock, N K; Laing, E M; Jenkins, N T; Oshri, A; Isales, C; Hamrick, M; Lewis, R D

2016-01-01

IGF-1 promotes bone growth directly and indirectly through its effects on skeletal muscle. Insulin and IGF-1 share a common cellular signaling process; thus, insulin resistance may influence the IGF-1-muscle-bone relationship. We sought to determine the effect of insulin resistance on the muscle-dependent relationship between IGF-1 and bone mass in premenarcheal girls. This was a cross-sectional study conducted at a university research center involving 147 girls ages 9 to 11 years. Glucose, insulin, and IGF-1 were measured from fasting blood samples. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated from glucose and insulin. Fat-free soft tissue (FFST) mass and bone mineral content (BMC) were measured by dual-energy x-ray absorptiometry. Our primary outcome was BMC/height. In our path model, IGF-1 predicted FFST mass (b = 0.018; P = .001), which in turn predicted BMC/height (b = 0.960; P < .001). IGF-1 predicted BMC/height (b = 0.001; P = .002), but not after accounting for the mediator of this relationship, FFST mass. The HOMA-IR by IGF-1 interaction negatively predicted FFST mass (b = -0.044; P = .034). HOMA-IR had a significant and negative effect on the muscle-dependent relationship between IGF-1 and BMC/height (b = -0.151; P = .047). Lean body mass is an important intermediary factor in the IGF-1-bone relationship. For this reason, bone development may be compromised indirectly via suboptimal IGF-1-dependent muscle development in insulin-resistant children.

Annealing effect on effective mass of two-dimensional electrons in InGaAsN/GaAsSb type II quantum well

NASA Astrophysics Data System (ADS)

Kawamata, Shuichi; Tanaka, Sho; Hibino, Akira; Kawamura, Yuichi

2018-03-01

The InP-based InGaAs/GaAsSb type II multiple quantum well is the system for developing optical devices for 2 – 3 μm wavelength regions. By doping nitrogen into InGaAs layers, the system becomes effective to fabricate the optical devices with longer wavelength. The epitaxial layers of InGaAsN/GaAsSb on InP substrates are grown by the molecular beam epitaxy. The electrical resistance has been measured as a function of the magnetic field up to 9 Tesla at several temperatures between 2 and 8 K. The effective mass is obtained from the temperature dependence of the amplitude of the Shubnikov-de Haas oscillations. We have reported the nitrogen concentration dependence of the effective mass on the InGaAsN/GaAsSb type II system. The effective mass increases as the nitrogen concentration increases from 0.0 to 1.5 %. In this report, the annealing effect on the effective mass is investigated. The effective mass decreases by the annealing. This result suggests that some amount of nitrogen atoms of the InGaAsN layers are considered to diffuse to the GaAsSb layers by the annealing.

An Investigation of Intracluster Light Evolution Using Cosmological Hydrodynamical Simulations

NASA Astrophysics Data System (ADS)

Tang, Lin; Lin, Weipeng; Cui, Weiguang; Kang, Xi; Wang, Yang; Contini, E.; Yu, Yu

2018-06-01

Intracluster light (ICL) in observations is usually identified through the surface brightness limit (SBL) method. In this paper, for the first time we produce mock images of galaxy groups and clusters, using a cosmological hydrodynamical simulation to investigate the ICL fraction and focus on its dependence on observational parameters, e.g., the SBL, the effects of cosmological redshift-dimming, point-spread function (PSF), and CCD pixel size. Detailed analyses suggest that the width of the PSF has a significant effect on the measured ICL fraction, while the relatively small pixel size shows almost no influence. It is found that the measured ICL fraction depends strongly on the SBL. At a fixed SBL and redshift, the measured ICL fraction decreases with increasing halo mass, while with a much fainter SBL, it does not depend on halo mass at low redshifts. In our work, the measured ICL fraction shows a clear dependence on the cosmological redshift-dimming effect. It is found that there is more mass locked in the ICL component than light, suggesting that the use of a constant mass-to-light ratio at high surface brightness levels will lead to an underestimate of ICL mass. Furthermore, it is found that the radial profile of ICL shows a characteristic radius that is almost independent of halo mass. The current measurement of ICL from observations has a large dispersion due to different methods, and we emphasize the importance of using the same definition when observational results are compared with theoretical predictions.

One possible source of mass-independent fractionation of sulfur isotopes in the Archean atmosphere of Earth

NASA Astrophysics Data System (ADS)

Babikov, Dmitri; Semenov, Alexander; Teplukhin, Alexander

2017-05-01

Energy transfer mechanism for recombination of two sulfur atoms into a diatomic molecule, S2, is studied theoretically and computationally to determine whether the rate coefficient of this process can be significantly affected by isotopic substitutions, and whether the resultant isotope effect is expected to be mass-dependent or mass-independent. This is one of sulfur polymerization processes thought to be important in the anoxic atmosphere of the Archean Earth and, potentially, relevant to mass-independent fractionation of sulfur isotopes. A simplified theoretical approach is employed, in which all properties of S2 molecule are characterized rather accurately, whereas the process of stabilization of metastable S2∗ by bath gas collisions is described approximately. Properties of individual scattering resonances in S2 are studied in detail, and it is found that most important contributions to the recombination process come from ro-vibrational states formed near the top of centrifugal barrier, and that the number of such states is about 50 (in 32S32S). Absolute value of recombination rate coefficient is computed to be 1.22 × 10-33 cm6/s (for 32S32S at room temperature and atmospheric pressure), close to experimental result. Two distinct isotope effects are identified. One is a classical mass-dependent effect due to translational partition function, which leads to a weak, smooth, and negative mass-dependence of rate coefficient (4% decrease when the mass is raised from 32S32S to 34S34S). Second effect, due to quantized resonances, is two orders of magnitude stronger, but is local. In practice, due to presence of multiple individual resonances, this phenomenon leads to irregular mass-independent variations of rate coefficients in the ranges ±5%. It is also demonstrated that in real molecules this irregular behavior is expected to be somewhat smoother, and the isotope effect is somewhat smaller, due to dependence of stabilization cross section on properties of individual resonances (not described by present model). Thus, additional calculations of stabilization cross sections are needed in order to give quantitative prediction of this mass-independent isotope effect, and to determine its relevance to mass-independent fractionation of sulfur isotopes in the Archean rock record.

Quark-mass dependence of two-nucleon observables

NASA Astrophysics Data System (ADS)

Chen, Jiunn-Wei; Lee, Tze-Kei; Liu, C.-P.; Liu, Yu-Sheng

2012-11-01

We study the potential implications of lattice QCD determinations of the S-wave nucleon-nucleon scattering lengths with unphysical light quark masses. If the light quark masses are small enough such that nuclear effective field theory (NEFT) can be used to perform quark-mass extrapolations, then the leading quark-mass dependence of not only the effective range and the two-body current, but also all the low-energy deuteron matrix elements up to next-to-leading-order in NEFT can be obtained. As a proof of principle, we compute the quark-mass dependence of the deuteron charge radius, magnetic moment, polarizability, and the deuteron photodisintegration cross section using the lattice calculation of the scattering lengths at 354 MeV pion mass by the ``Nuclear Physics with Lattice QCD'' (NPLQCD) collaboration and the NEFT power counting scheme of Beane, Kaplan, and Vuorinen (BKV), even though it is not yet established that the 354 MeV pion mass is within the radius of convergence of the BKV scheme. Once the lattice result with quark mass within the NEFT radius of convergence is obtained, our observation can be used to constrain the time variation of isoscalar combination of u and d quark mass mq, to help the anthropic principle study to find the mq range that allows the existence of life, and to provide a weak test of the multiverse conjecture.

Modeling of laser-induced ionization of solid dielectrics for ablation simulations: role of effective mass

NASA Astrophysics Data System (ADS)

Gruzdev, Vitaly

2010-11-01

Modeling of laser-induced ionization and heating of conduction-band electrons by laser radiation frequently serves as a basis for simulations supporting experimental studies of laser-induced ablation and damage of solid dielectrics. Together with band gap and electron-particle collision rate, effective electron mass is one of material parameters employed for the ionization modeling. Exact value of the effective mass is not known for many materials frequently utilized in experiments, e.g., fused silica and glasses. Because of that reason, value of the effective mass is arbitrary varied around "reasonable values" for the ionization modeling. In fact, it is utilized as a fitting parameter to fit experimental data on dependence of ablation or damage threshold on laser parameters. In this connection, we study how strong is the influence of variations of the effective mass on the value of conduction-band electron density. We consider influence of the effective mass on the photo-ionization rate and rate of impact ionization. In particular, it is shown that the photo-ionization rate can vary by 2-4 orders of magnitude with variation of effective mass by 50%. Impact ionization shows a much weaker dependence on effective mass, but it significantly enhances the variations of seed-electron density produced by the photo-ionization. Utilizing those results, we demonstrate that variation of effective mass by 50% produces variations of conduction-band electron density by 6 orders of magnitude. In this connection, we discuss the general issues of the current models of laser-induced ionization.

Nuclear symmetry energy in terms of single-nucleon potential and its effect on the proton fraction of β-stable npeμ matter

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

Sahoo, Babita, E-mail: patra-babita@rediffmail.com; Chakraborty, Suparna, E-mail: banerjee.suparna@hotmail.com; Sahoo, Sukadev, E-mail: sukadevsahoo@yahoo.com

2016-01-15

Momentum and density dependence of single-nucleon potential u{sub τ} (k, ρ, β) is analyzed using a density dependent finite range effective interaction of the Yukawa form. Depending on the choice of the strength parameters of exchange interaction, two different trends of the momentum dependence of nuclear symmetry potential are noticed which lead to two opposite types of neutron and proton effective mass splitting. The 2nd-order and 4th-order symmetry energy of isospin asymmetric nuclear matter are expressed analytically in terms of the single-nucleon potential. Two distinct behavior of the density dependence of 2nd-order and 4th-order symmetry energy are observed depending onmore » neutron and proton effective mass splitting. It is also found that the 4th-order symmetry energy has a significant contribution towards the proton fraction of β-stable npeμ matter at high densities.« less

Differential effects of massed and spaced training on place and response learning: A memory systems perspective.

PubMed

Wingard, Jeffrey C; Goodman, Jarid; Leong, Kah-Chung; Packard, Mark G

2015-09-01

Studies employing brain lesion or intracerebral drug infusions in rats have demonstrated a double dissociation between the roles of the hippocampus and dorsolateral striatum in place and response learning. The hippocampus mediates a rapid cognitive learning process underlying place learning, whereas the dorsolateral striatum mediates a relatively slower learning process in which stimulus-response habits underlying response learning are acquired in an incremental fashion. One potential implication of these findings is that hippocampus-dependent learning may benefit from a relative massing of training trials, whereas dorsal striatum-dependent learning may benefit from a relative distribution of training trials. In order to examine this hypothesis, the present study compared the effects of massed (30s inter-trial interval; ITI) or spaced (30min ITI) training on acquisition of a hippocampus-dependent place learning task, and a dorsolateral striatum-dependent response task in a plus-maze. In the place task rats swam from varying start points (N or S) to a hidden escape platform located in a consistent spatial location (W). In the response task rats swam from varying start points (N or S) to a hidden escape platform located in the maze arm consistent with a body-turn response (left). In the place task, rats trained with the massed trial schedule acquired the task quicker than rats trained with the spaced trial schedule. In the response task, rats trained with the spaced trial schedule acquired the task quicker than rats trained with the massed trial schedule. The double dissociation observed suggests that the reinforcement parameters most conducive to effective learning in hippocampus-dependent and dorsolateral striatum-dependent learning may have differential temporal characteristics. Copyright © 2015 Elsevier B.V. All rights reserved.

Hadron mass corrections in semi-inclusive deep-inelastic scattering

DOE PAGES

Guerrero Teran, Juan Vicente; Ethier, James J.; Accardi, Alberto; ...

2015-09-24

We found that the spin-dependent cross sections for semi-inclusive lepton-nucleon scattering are derived in the framework of collinear factorization, including the effects of masses of the target and produced hadron at finite Q 2. At leading order the cross sections factorize into products of parton distribution and fragmentation functions evaluated in terms of new, mass-dependent scaling variables. Furthermore, the size of the hadron mass corrections is estimated at kinematics relevant for current and future experiments, and the implications for the extraction of parton distributions from semi-inclusive measurements are discussed.

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

Bellomo, Nicola; Bellini, Emilio; Hu, Bin

Cosmological observables show a dependence with the neutrino mass, which is partially degenerate with parameters of extended models of gravity. We study and explore this degeneracy in Horndeski generalized scalar-tensor theories of gravity. Using forecasted cosmic microwave background and galaxy power spectrum datasets, we find that a single parameter in the linear regime of the effective theory dominates the correlation with the total neutrino mass. For any given mass, a particular value of this parameter approximately cancels the power suppression due to the neutrino mass at a given redshift. The extent of the cancellation of this degeneracy depends on themore » cosmological large-scale structure data used at different redshifts. We constrain the parameters and functions of the effective gravity theory and determine the influence of gravity on the determination of the neutrino mass from present and future surveys.« less

Acquiring information about neutrino parameters by detecting supernova neutrinos

NASA Astrophysics Data System (ADS)

Huang, Ming-Yang; Guo, Xin-Heng; Young, Bing-Lin

2010-08-01

We consider the supernova shock effects, the Mikheyev-Smirnov-Wolfenstein effects, the collective effects, and the Earth matter effects in the detection of type II supernova neutrinos on the Earth. It is found that the event number of supernova neutrinos depends on the neutrino mass hierarchy, the neutrino mixing angle θ13, and neutrino masses. Therefore, we propose possible methods to identify the mass hierarchy and acquire information about θ13 and neutrino masses by detecting supernova neutrinos. We apply these methods to some current neutrino experiments.

Quark-mass dependence of the H dibaryon in Λ Λ scattering

NASA Astrophysics Data System (ADS)

Yamaguchi, Yasuhiro; Hyodo, Tetsuo

2016-12-01

We study the quark mass dependence of the H dibaryon in the strangeness S =-2 baryon-baryon scattering. A low-energy effective field theory is used to describe the coupled-channel scattering, in which the quark mass dependence is incorporated so as to reproduce the lattice QCD data by the HAL QCD collaboration in the SU(3) limit. We point out the existence of the Castillejo-Dalitz-Dyson pole in the Λ Λ scattering amplitude below the threshold in the SU(3) limit, which may cause the Ramsauer-Townsend effect near the N Ξ threshold at the physical point. The H dibaryon is unbound at the physical point, and a resonance appears just below the N Ξ threshold. As a consequence of the coupled-channel dynamics, the pole associated with the resonance is not continuously connected to the bound state in the SU(3) limit. Through the extrapolation in quark masses, we show that the unitary limit of the Λ Λ scattering is achieved between the physical point and the SU(3) limit. We discuss the possible realization of the "H matter" in the unphysical quark mass region.

Observational constraints on varying neutrino-mass cosmology

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

Geng, Chao-Qiang; Lee, Chung-Chi; Myrzakulov, R.

We consider generic models of quintessence and we investigate the influence of massive neutrino matter with field-dependent masses on the matter power spectrum. In case of minimally coupled neutrino matter, we examine the effect in tracker models with inverse power-law and double exponential potentials. We present detailed investigations for the scaling field with a steep exponential potential, non-minimally coupled to massive neutrino matter, and we derive constraints on field-dependent neutrino masses from the observational data.

QUENCHING OF STAR FORMATION IN SLOAN DIGITAL SKY SURVEY GROUPS: CENTRALS, SATELLITES, AND GALACTIC CONFORMITY

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

Knobel, Christian; Lilly, Simon J.; Woo, Joanna

2015-02-10

We re-examine the fraction of low-redshift Sloan Digital Sky Survey satellites and centrals in which star formation has been quenched, using the environment quenching efficiency formalism that separates out the dependence of stellar mass. We show that the centrals of the groups containing the satellites are responding to the environment in the same way as their satellites (at least for stellar masses above 10{sup 10.3} M {sub ☉}), and that the well-known differences between satellites and the general set of centrals arise because the latter are overwhelmingly dominated by isolated galaxies. The widespread concept of ''satellite quenching'' as the causemore » of environmental effects in the galaxy population can therefore be generalized to ''group quenching''. We then explore the dependence of the quenching efficiency of satellites on overdensity, group-centric distance, halo mass, the stellar mass of the satellite, and the stellar mass and specific star formation rate (sSFR) of its central, trying to isolate the effect of these often interdependent variables. We emphasize the importance of the central sSFR in the quenching efficiency of the associated satellites, and develop the meaning of this ''galactic conformity'' effect in a probabilistic description of the quenching of galaxies. We show that conformity is strong, and that it varies strongly across parameter space. Several arguments then suggest that environmental quenching and mass quenching may be different manifestations of the same underlying process. The marked difference in the apparent mass dependencies of environment quenching and mass quenching which produces distinctive signatures in the mass functions of centrals and satellites will arise naturally, since, for satellites at least, the distributions of the environmental variables that we investigate in this work are essentially independent of the stellar mass of the satellite.« less

Evaporation and scattering of momentum- and velocity-dependent dark matter in the Sun

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

Busoni, Giorgio; Simone, Andrea De; Scott, Pat

Dark matter with momentum- or velocity-dependent interactions with nuclei has shown significant promise for explaining the so-called Solar Abundance Problem, a longstanding discrepancy between solar spectroscopy and helioseismology. The best-fit models are all rather light, typically with masses in the range of 3–5 GeV. This is exactly the mass range where dark matter evaporation from the Sun can be important, but to date no detailed calculation of the evaporation of such models has been performed. Here we carry out this calculation, for the first time including arbitrary velocity- and momentum-dependent interactions, thermal effects, and a completely general treatment valid frommore » the optically thin limit all the way through to the optically thick regime. We find that depending on the dark matter mass, interaction strength and type, the mass below which evaporation is relevant can vary from 1 to 4 GeV. This has the effect of weakening some of the better-fitting solutions to the Solar Abundance Problem, but also improving a number of others. As a by-product, we also provide an improved derivation of the capture rate that takes into account thermal and optical depth effects, allowing the standard result to be smoothly matched to the well-known saturation limit.« less

Baryons in the plasma: In-medium effects and parity doubling

NASA Astrophysics Data System (ADS)

Aarts, Gert; Allton, Chris; de Boni, Davide; Hands, Simon; Jäger, Benjamin; Praki, Chrisanthi; Skullerud, Jon-Ivar

2018-02-01

We investigate the fate of baryons made out of u, d and s quarks in the hadronic gas and the quark-gluon plasma, using nonperturbative lattice simulations, employing the FASTSUManisotropic Nf = 2+1 ensembles. In the confined phase a strong temperature dependence is seen in the masses of the negative-parity groundstates, while the positiveparity groundstate masses are approximately temperature independent, within the error. At high temperature parity doubling emerges. A noticeable effect of the heavier s quark is seen. We give a simple description of the medium-dependent masses for the negativeparity states and speculate on the relevance for heavy-ion phenomenology via the hadron resonance gas.

Effect of neutrino rest mass on ionization equilibrium freeze-out

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

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

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.

Model-dependence of neutrino emissivities and neutrino luminosities of neutron stars from the direct Urca processes and the modified Urca processes

NASA Astrophysics Data System (ADS)

Yin, Peng; Fan, Xiaohua; Dong, Jianmin; Guo, Wenmei; Zuo, Wei

2017-05-01

The neutrino emissivities in β-stable neutron star matter from the direct Urca (DU) processes and the modified Urca (MU) processes have been investigated by adopting 26 Skyrme interactions. Several physical quantities related to the MU processes and the DU processes have been calculated and discussed. The model-dependence of the neutrino emissivities from the DU processes is found to stem mainly from the model-dependence of the effective mass, while the neutrino emissivities from the MU processes are determined by the competition between the effects of the symmetry energy and the effective mass. Besides, we have investigated the total neutrino luminosities of neutron stars, with the masses of 1.2 , 1.4 , 1.6 and 1.8M⊙, from the DU processes and the MU processes. The neutrino luminosity of a neutron star is found to be primarily determined by whether the electron DU process is allowed or not. As long as the electron DU process can occur, the total luminosity turns out to be 5 to 8 orders of magnitude larger as compared with the case that the DU process is forbidden, which indicates that the strongest model-dependence of the neutrino luminosity comes from that of the symmetry energy and the equation of state (EOS) of neutron star matter. In the case that the DU processes are allowed, the discrepancy of the calculated neutrino luminosity using various Skyrme interactions remains noticeable, which is essentially attributed to the model-dependence of the symmetry energy, the EOS of NS matter and the effective masses.

Time-dependent view of an isotope effect in electron-nuclear nonequilibrium dynamics with applications to N2.

PubMed

Ajay, Jayanth S; Komarova, Ksenia G; Remacle, Francoise; Levine, R D

2018-06-05

Isotopic fractionation in the photodissociation of N 2 could explain the considerable variation in the 14 N/ 15 N ratio in different regions of our galaxy. We previously proposed that such an isotope effect is due to coupling of photoexcited bound valence and Rydberg electronic states in the frequency range where there is strong state mixing. We here identify features of the role of the mass in the dynamics through a time-dependent quantum-mechanical simulation. The photoexcitation of N 2 is by an ultrashort pulse so that the process has a sharply defined origin in time and so that we can monitor the isolated molecule dynamics in time. An ultrafast pulse is necessarily broad in frequency and spans several excited electronic states. Each excited molecule is therefore not in a given electronic state but in a superposition state. A short time after excitation, there is a fairly sharp onset of a mass-dependent large population transfer when wave packets on two different electronic states in the same molecule overlap. This coherent overlap of the wave packets on different electronic states in the region of strong coupling allows an effective transfer of population that is very mass dependent. The extent of the transfer depends on the product of the populations on the two different electronic states and on their relative phase. It is as if two molecules collide but the process occurs within one molecule, a molecule that is simultaneously in both states. An analytical toy model recovers the (strong) mass and energy dependence.

Modelling non-adiabatic effects in H{sub 3}{sup +}: Solution of the rovibrational Schrödinger equation with motion-dependent masses and mass surfaces

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

Mátyus, Edit, E-mail: matyus@chem.elte.hu; Szidarovszky, Tamás; Császár, Attila G., E-mail: csaszar@chem.elte.hu

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 themore » 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.« less

Modelling non-adiabatic effects in H_3^+: Solution of the rovibrational Schrödinger equation with motion-dependent masses and mass surfaces

NASA Astrophysics Data System (ADS)

Mátyus, Edit; Szidarovszky, Tamás; Császár, Attila G.

2014-10-01

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_3^+, for which a global adiabatic potential energy surface accurate to better than 0.1 cm-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 D3h point-group symmetry is employed. The vibrational mass of the proton in H_3^+ 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^(v)_opt,p=m_nuc,p+0.31224 m_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.

Excited-State Effective Masses in Lattice QCD

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

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.

Strong bimodality in the host halo mass of central galaxies from galaxy-galaxy lensing

NASA Astrophysics Data System (ADS)

Mandelbaum, Rachel; Wang, Wenting; Zu, Ying; White, Simon; Henriques, Bruno; More, Surhud

2016-04-01

We use galaxy-galaxy lensing to study the dark matter haloes surrounding a sample of locally brightest galaxies (LBGs) selected from the Sloan Digital Sky Survey. We measure mean halo mass as a function of the stellar mass and colour of the central galaxy. Mock catalogues constructed from semi-analytic galaxy formation simulations demonstrate that most LBGs are the central objects of their haloes, greatly reducing interpretation uncertainties due to satellite contributions to the lensing signal. Over the full stellar mass range, 10.3 < log [M*/M⊙] < 11.6, we find that passive central galaxies have haloes that are at least twice as massive as those of star-forming objects of the same stellar mass. The significance of this effect exceeds 3σ for log [M*/M⊙] > 10.7. Tests using the mock catalogues and on the data themselves clarify the effects of LBG selection and show that it cannot artificially induce a systematic dependence of halo mass on LBG colour. The bimodality in halo mass at fixed stellar mass is reproduced by the astrophysical model underlying our mock catalogue, but the sign of the effect is inconsistent with recent, nearly parameter-free age-matching models. The sign and magnitude of the effect can, however, be reproduced by halo occupation distribution models with a simple (few-parameter) prescription for type dependence.

In-medium effects via nuclear stopping in asymmetric colliding nuclei

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

Kaur, Mandeep

2016-05-06

The nuclear stopping is studied using isospin-dependent quantum molecular dynamics (IQMD) model in asymmetric colliding nuclei by varying mass asymmetry. The calculations have been done at incident energies varying between 50 and 400 MeV/nucleon for different impact parameters. We investigate the relative role of constant scaled and density-dependent scaled cross-sections. Our study reveals that nuclear stopping depends on the mass asymmetry, incident energy and impact parameter, however, it is independent of the way of scaling the cross-section.

Sex-dependent effects of larval food stress on adult performance under semi-natural conditions: only a matter of size?

PubMed

Rosa, Elena; Saastamoinen, Marjo

2017-07-01

Organisms with complex life-cycles acquire essential nutrients as juveniles, and hence even a short-term food stress during development can impose serious fitness costs apparent in adults. We used the Glanville fritillary butterfly to investigate the effects of larval food stress on adult performance under semi-natural conditions in a population enclosure. We were specifically interested in whether the negative effects observed were due to body mass reduction only or whether additional effects unrelated to pupal mass were evident. The two sexes responded differently to the larval food stress. In females, larval food stress reduced pupal mass and reproductive performance. The reduced reproductive performance was partially mediated by pupal mass reduction. Food stressed females also had reduced within-patch mobility, and this effect was not dependent on pupal mass. Conversely, food stress had no effect on male pupal mass, suggesting a full compensation via prolonged development time. Nonetheless, food stressed males were less likely to sire any eggs, potentially due to changes in their territorial behavior, as indicated by food stress also increasing male within-patch mobility (i.e., patrolling behavior). When males did sire eggs, the offspring number and viability were unaffected by male food stress treatment. Viability was in general higher for offspring sired by lighter males. Our study highlights how compensatory mechanisms after larval food stress can act in a sex-specific manner and that the alteration in body mass is only partially responsible for the reduced adult performance observed.

An isotopic mass effect on the intermolecular potential

DOE PAGES

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

2015-09-28

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 paper, 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. Finally, the analysis suggests that mass dependent variations in intermolecular potentials should be included in comprehensive descriptions of isotopologuemore » thermodynamics.« less

Layer-dependent Band Alignment and Work Function of Few-Layer Phosphorene

PubMed Central

Cai, Yongqing; Zhang, Gang; Zhang, Yong-Wei

2014-01-01

Using first-principles calculations, we study the electronic properties of few-layer phosphorene focusing on layer-dependent behavior of band gap, work function band alignment and carrier effective mass. It is found that few-layer phosphorene shows a robust direct band gap character, and its band gap decreases with the number of layers following a power law. The work function decreases rapidly from monolayer (5.16 eV) to trilayer (4.56 eV), and then slowly upon further increasing the layer number. Compared to monolayer phosphorene, there is a drastic decrease of hole effective mass along the ridge (zigzag) direction for bilayer phosphorene, indicating a strong interlayer coupling and screening effect. Our study suggests that 1). Few-layer phosphorene with a layer-dependent band gap and a robust direct band gap character is promising for efficient solar energy harvest. 2). Few-layer phosphorene outperforms monolayer counterpart in terms of a lighter carrier effective mass, a higher carrier density and a weaker scattering due to enhanced screening. 3). The layer-dependent band edges and work functions of few-layer phosphorene allow for modification of Schottky barrier with enhanced carrier injection efficiency. It is expected that few-layer phosphorene will present abundant opportunities for a plethora of new electronic applications. PMID:25327586

Analysis of EDZ Development of Columnar Jointed Rock Mass in the Baihetan Diversion Tunnel

NASA Astrophysics Data System (ADS)

Hao, Xian-Jie; Feng, Xia-Ting; Yang, Cheng-Xiang; Jiang, Quan; Li, Shao-Jun

2016-04-01

Due to the time dependency of the crack propagation, columnar jointed rock masses exhibit marked time-dependent behaviour. In this study, in situ measurements, scanning electron microscope (SEM), back-analysis method and numerical simulations are presented to study the time-dependent development of the excavation damaged zone (EDZ) around underground diversion tunnels in a columnar jointed rock mass. Through in situ measurements of crack propagation and EDZ development, their extent is seen to have increased over time, despite the fact that the advancing face has passed. Similar to creep behaviour, the time-dependent EDZ development curve also consists of three stages: a deceleration stage, a stabilization stage, and an acceleration stage. A corresponding constitutive model of columnar jointed rock mass considering time-dependent behaviour is proposed. The time-dependent degradation coefficient of the roughness coefficient and residual friction angle in the Barton-Bandis strength criterion are taken into account. An intelligent back-analysis method is adopted to obtain the unknown time-dependent degradation coefficients for the proposed constitutive model. The numerical modelling results are in good agreement with the measured EDZ. Not only that, the failure pattern simulated by this time-dependent constitutive model is consistent with that observed in the scanning electron microscope (SEM) and in situ observation, indicating that this model could accurately simulate the failure pattern and time-dependent EDZ development of columnar joints. Moreover, the effects of the support system provided and the in situ stress on the time-dependent coefficients are studied. Finally, the long-term stability analysis of diversion tunnels excavated in columnar jointed rock masses is performed.

Influence of indoor environmental factors on mass transfer parameters and concentrations of semi-volatile organic compounds.

PubMed

Wei, Wenjuan; Mandin, Corinne; Ramalho, Olivier

2018-03-01

Semi-volatile organic compounds (SVOCs) in indoor environments can partition among the gas phase, airborne particles, settled dust, and available surfaces. The mass transfer parameters of SVOCs, such as the mass transfer coefficient and the partition coefficient, are influenced by indoor environmental factors. Subsequently, indoor SVOC concentrations and thus occupant exposure can vary depending on environmental factors. In this review, the influence of six environmental factors, i.e., indoor temperature, humidity, ventilation, airborne particle concentration, source loading factor, and reactive chemistry, on the mass transfer parameters and indoor concentrations of SVOCs was analyzed and tentatively quantified. The results show that all mass transfer parameters vary depending on environmental factors. These variations are mostly characterized by empirical equations, particularly for humidity. Theoretical calculations of these parameters based on mass transfer mechanisms are available only for the emission of SVOCs from source surfaces when airborne particles are not present. All mass transfer parameters depend on the temperature. Humidity influences the partition of SVOCs among different phases and is associated with phthalate hydrolysis. Ventilation has a combined effect with the airborne particle concentration on SVOC emission and their mass transfer among different phases. Indoor chemical reactions can produce or eliminate SVOCs slowly. To better model the dynamic SVOC concentration indoors, the present review suggests studying the combined effect of environmental factors in real indoor environments. Moreover, interactions between indoor environmental factors and human activities and their influence on SVOC mass transfer processes should be considered. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effective Mass Calculations for Two-dimensional Gas of Dipolar Fermions

NASA Astrophysics Data System (ADS)

Seydi, I.; Abedinpour, S. H.; Tanatar, B.

2017-06-01

We consider a two-dimensional system of ultracold dipolar fermions with dipole moments aligned in the perpendicular direction. We use the static structure factor information from Fermi-Hypernetted-Chain calculations to obtain the effective many-body dipole-dipole interaction and calculate the many-body effective mass of the system within the G0W approximation to the self-energy. A large cancellation between different contributions to the self-energy results in a weak dependence of the effective mass on the interaction strength over a large range of coupling constants.

First-principles X-ray absorption dose calculation for time-dependent mass and optical density.

PubMed

Berejnov, Viatcheslav; Rubinstein, Boris; Melo, Lis G A; Hitchcock, Adam P

2018-05-01

A dose integral of time-dependent X-ray absorption under conditions of variable photon energy and changing sample mass is derived from first principles starting with the Beer-Lambert (BL) absorption model. For a given photon energy the BL dose integral D(e, t) reduces to the product of an effective time integral T(t) and a dose rate R(e). Two approximations of the time-dependent optical density, i.e. exponential A(t) = c + aexp(-bt) for first-order kinetics and hyperbolic A(t) = c + a/(b + t) for second-order kinetics, were considered for BL dose evaluation. For both models three methods of evaluating the effective time integral are considered: analytical integration, approximation by a function, and calculation of the asymptotic behaviour at large times. Data for poly(methyl methacrylate) and perfluorosulfonic acid polymers measured by scanning transmission soft X-ray microscopy were used to test the BL dose calculation. It was found that a previous method to calculate time-dependent dose underestimates the dose in mass loss situations, depending on the applied exposure time. All these methods here show that the BL dose is proportional to the exposure time D(e, t) ≃ K(e)t.

Dependence of Halo Bias and Kinematics on Assembly Variables

NASA Astrophysics Data System (ADS)

Xu, Xiaoju; Zheng, Zheng

2018-06-01

Using dark matter haloes identified in a large N-body simulation, we study halo assembly bias, with halo formation time, peak maximum circular velocity, concentration, and spin as the assembly variables. Instead of grouping haloes at fixed mass into different percentiles of each assembly variable, we present the joint dependence of halo bias on the values of halo mass and each assembly variable. In the plane of halo mass and one assembly variable, the joint dependence can be largely described as halo bias increasing outward from a global minimum. We find it unlikely to have a combination of halo variables to absorb all assembly bias effects. We then present the joint dependence of halo bias on two assembly variables at fixed halo mass. The gradient of halo bias does not necessarily follow the correlation direction of the two assembly variables and it varies with halo mass. Therefore in general for two correlated assembly variables one cannot be used as a proxy for the other in predicting halo assembly bias trend. Finally, halo assembly is found to affect the kinematics of haloes. Low-mass haloes formed earlier can have much higher pairwise velocity dispersion than those of massive haloes. In general, halo assembly leads to a correlation between halo bias and halo pairwise velocity distribution, with more strongly clustered haloes having higher pairwise velocity and velocity dispersion. However, the correlation is not tight, and the kinematics of haloes at fixed halo bias still depends on halo mass and assembly variables.

Sperm competition games: sperm size (mass) and number under raffle and displacement, and the evolution of P2.

PubMed

Parker, G A; Immler, S; Pitnick, S; Birkhead, T R

2010-06-07

We examine models for evolution of sperm size (i.e. mass m) and number (s) under three mechanisms of sperm competition at low 'risk' levels: (i) raffle with no constraint on space available for competing sperm, (ii) direct displacement mainly by seminal fluid, and (iii) direct displacement mainly by sperm mass. Increasing sperm mass increases a sperm's 'competitive weight' against rival sperm through a diminishing returns function, r(m). ESS total ejaculate expenditure (the product m(*)s(*)) increases in all three models with sperm competition risk, q. If r(m), or ratio r'(m)/r(m), is independent of ESS sperm numbers, ESS sperm mass remains constant, and the sperm mass/number ratio (m(*)/s(*)) therefore decreases with risk. Dependency of sperm mass on risk can arise if r(m) depends on competing sperm density (sperm number / space available for sperm competition). Such dependencies generate complex relationships between sperm mass and number with risk, depending both on the mechanism and how sperm density affects r(m). While numbers always increase with risk, mass can either increase or decrease, but m(*)/s(*) typically decreases with risk unless sperm density strongly influences r(m). Where there is no extrinsic loading due to mating order, ESS paternity of the second (i.e. last) male to mate (P(2)) under displacement always exceeds 0.5, and increases with risk (in the raffle P(2)=0.5). Caution is needed when seeking evidence for a sperm size-number trade off. Although size and number trade-off independently against effort spent on acquiring matings, their product, m(*)s(*), is invariant or fixed at a given risk level, effectively generating a size-number trade off. However, unless controlled for the effects of risk, the relation between m(*) and s(*) can be either positive or negative (a positive relation is usually taken as evidence against a size-number trade off). Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Determination of beam-position dependent transfer functions of LCR-G gravimeters by means of moving mass calibration device in the Mátyáshegy Gravity and Geodynamical Observatory, Budapest

NASA Astrophysics Data System (ADS)

Koppán, András; Kis, Márta; Merényi, László; Papp, Gábor; Benedek, Judit; Meurers, Bruno

2017-04-01

In this presentation authors propose a method for the determination of transfer characteristics and fine calibration of LCR relative gravimeters used for earth-tide recordings, by means of the moving-mass gravimeter calibration device of Budapest-Mátyáshegy Gravity and Geodynamical Observatory. Beam-position dependent transfer functions of four relative LCR G type gravimeters were determined and compared. In order to make these instruments applicable for observatory tidal recordings, there is a need for examining the unique characteristics of equipments and adequately correcting these inherent distorting effects. Thus, the sensitivity for the tilting, temporal changes of scale factors and beam-position dependent transfer characteristics are necessary to be determined for observatory use of these instruments. During the calibration a cylindrical ring of 3200 kg mass is vertically moving around the equipment, generating gravity variations. The effect of the moving mass can be precisely calculated from the known mass and geometrical parameters. The maximum theoretical gravity variation produced by the vertical movement of the mass is ab. 110 microGal, so it provides excellent possibility for the fine calibration of gravimeters in the tidal range. Magnetic experiments were also carried out on the pillar of the calibration device as well, in order to analyse the magnetic effect of the moving stainless steel-mass. According to the magnetic measurements, a correction for the magnetic effect was applied on the measured gravimetric data series. The calibration process is aided by intelligent controller electronics. A PLC-based system has been developed to allow easy control of the movement of the calibrating mass and to measure the mass position. It enables also programmed steps of movements (waiting positions and waiting times) for refined gravity changes. All parameters (position of the mass, CPI data, X/Y leveling positions) are recorded with 1/sec. sampling rate. The system can be controlled remotely through the internet. Authors wish to express their thanks to OTKA (Hungarian Scientific Research Fund) for their support (OTKA-K101603, OTKA K109060).

On the Klein–Gordon oscillator subject to a Coulomb-type potential

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

Bakke, K., E-mail: kbakke@fisica.ufpb.br; Furtado, C., E-mail: furtado@fisica.ufpb.br

2015-04-15

By introducing the scalar potential as modification in the mass term of the Klein–Gordon equation, the influence of a Coulomb-type potential on the Klein–Gordon oscillator is investigated. Relativistic bound states solutions are achieved to both attractive and repulsive Coulomb-type potentials and the arising of a quantum effect characterized by the dependence of angular frequency of the Klein–Gordon oscillator on the quantum numbers of the system is shown. - Highlights: • Interaction between the Klein–Gordon oscillator and a modified mass term. • Relativistic bound states for both attractive and repulsive Coulomb-type potentials. • Dependence of the Klein–Gordon oscillator frequency on themore » quantum numbers. • Relativistic analogue of a position-dependent mass system.« less

Rotating field mass and velocity analyzer

NASA Technical Reports Server (NTRS)

Smith, Steven Joel (Inventor); Chutjian, Ara (Inventor)

1998-01-01

A rotating field mass and velocity analyzer having a cell with four walls, time dependent RF potentials that are applied to each wall, and a detector. The time dependent RF potentials create an RF field in the cell which effectively rotates within the cell. An ion beam is accelerated into the cell and the rotating RF field disperses the incident ion beam according to the mass-to-charge (m/e) ratio and velocity distribution present in the ion beam. The ions of the beam either collide with the ion detector or deflect away from the ion detector, depending on the m/e, RF amplitude, and RF frequency. The detector counts the incident ions to determine the m/e and velocity distribution in the ion beam.

Dependence of GAMA galaxy halo masses on the cosmic web environment from 100 deg2 of KiDS weak lensing data

NASA Astrophysics Data System (ADS)

Brouwer, Margot M.; Cacciato, Marcello; Dvornik, Andrej; Eardley, Lizzie; Heymans, Catherine; Hoekstra, Henk; Kuijken, Konrad; McNaught-Roberts, Tamsyn; Sifón, Cristóbal; Viola, Massimo; Alpaslan, Mehmet; Bilicki, Maciej; Bland-Hawthorn, Joss; Brough, Sarah; Choi, Ami; Driver, Simon P.; Erben, Thomas; Grado, Aniello; Hildebrandt, Hendrik; Holwerda, Benne W.; Hopkins, Andrew M.; de Jong, Jelte T. A.; Liske, Jochen; McFarland, John; Nakajima, Reiko; Napolitano, Nicola R.; Norberg, Peder; Peacock, John A.; Radovich, Mario; Robotham, Aaron S. G.; Schneider, Peter; Sikkema, Gert; van Uitert, Edo; Verdoes Kleijn, Gijs; Valentijn, Edwin A.

2016-11-01

Galaxies and their dark matter haloes are part of a complex network of mass structures, collectively called the cosmic web. Using the tidal tensor prescription these structures can be classified into four cosmic environments: voids, sheets, filaments and knots. As the cosmic web may influence the formation and evolution of dark matter haloes and the galaxies they host, we aim to study the effect of these cosmic environments on the average mass of galactic haloes. To this end we measure the galaxy-galaxy lensing profile of 91 195 galaxies, within 0.039 < z < 0.263, from the spectroscopic Galaxy And Mass Assembly survey, using {˜ }100 ° ^2 of overlapping data from the Kilo-Degree Survey. In each of the four cosmic environments we model the contributions from group centrals, satellites and neighbouring groups to the stacked galaxy-galaxy lensing profiles. After correcting the lens samples for differences in the stellar mass distribution, we find no dependence of the average halo mass of central galaxies on their cosmic environment. We do find a significant increase in the average contribution of neighbouring groups to the lensing profile in increasingly dense cosmic environments. We show, however, that the observed effect can be entirely attributed to the galaxy density at much smaller scales (within 4 h-1 Mpc), which is correlated with the density of the cosmic environments. Within our current uncertainties we find no direct dependence of galaxy halo mass on their cosmic environment.

Primordial SdS universe from a 5D vacuum: scalar field fluctuations on Schwarzschild and Hubble horizons

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

Aguilar, José Edgar Madriz; Bellini, Mauricio, E-mail: jemadriz@fisica.ugto.mx, E-mail: mbellini@mdp.edu.ar

2010-11-01

We study scalar field fluctuations of the inflaton field in an early inflationary universe on an effective 4D Schwarzschild-de Sitter (SdS) metric, which is obtained after make a planar coordinate transformation on a 5D Ricci-flat Schwarzschild-de Sitter (SdS) static metric. We obtain the important result that the spectrum of fluctuations at zeroth order is independent of the scalar field mass M on Schwarzschild scales, while on cosmological scales it exhibits a mass dependence. However, in the first-order expansion, the spectrum depends of the inflaton mass and the amplitude is linear with the Black-Hole (BH) mass m.

Finite volume effects on the electric polarizability of neutral hadrons in lattice QCD

NASA Astrophysics Data System (ADS)

Lujan, M.; Alexandru, A.; Freeman, W.; Lee, F. X.

2016-10-01

We study the finite volume effects on the electric polarizability for the neutron, neutral pion, and neutral kaon using eight dynamically generated two-flavor nHYP-clover ensembles at two different pion masses: 306(1) and 227(2) MeV. An infinite volume extrapolation is performed for each hadron at both pion masses. For the neutral kaon, finite volume effects are relatively mild. The dependence on the quark mass is also mild, and a reliable chiral extrapolation can be performed along with the infinite volume extrapolation. Our result is αK0 phys=0.356 (74 )(46 )×10-4 fm3 . In contrast, for neutron, the electric polarizability depends strongly on the volume. After removing the finite volume corrections, our neutron polarizability results are in good agreement with chiral perturbation theory. For the connected part of the neutral pion polarizability, the negative trend persists, and it is not due to finite volume effects but likely sea quark charging effects.

Quark ACM with topologically generated gluon mass

NASA Astrophysics Data System (ADS)

Choudhury, Ishita Dutta; Lahiri, Amitabha

2016-03-01

We investigate the effect of a small, gauge-invariant mass of the gluon on the anomalous chromomagnetic moment (ACM) of quarks by perturbative calculations at one-loop level. The mass of the gluon is taken to have been generated via a topological mass generation mechanism, in which the gluon acquires a mass through its interaction with an antisymmetric tensor field Bμν. For a small gluon mass ( < 10 MeV), we calculate the ACM at momentum transfer q2 = -M Z2. We compare those with the ACM calculated for the gluon mass arising from a Proca mass term. We find that the ACM of up, down, strange and charm quarks vary significantly with the gluon mass, while the ACM of top and bottom quarks show negligible gluon mass dependence. The mechanism of gluon mass generation is most important for the strange quarks ACM, but not so much for the other quarks. We also show the results at q2 = -m t2. We find that the dependence on gluon mass at q2 = -m t2 is much less than at q2 = -M Z2 for all quarks.

A position-dependent mass model for the Thomas–Fermi potential: Exact solvability and relation to δ-doped semiconductors

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

Schulze-Halberg, Axel, E-mail: xbataxel@gmail.com; García-Ravelo, Jesús; Pacheco-García, Christian

We consider the Schrödinger equation in the Thomas–Fermi field, a model that has been used for describing electron systems in δ-doped semiconductors. It is shown that the problem becomes exactly-solvable if a particular effective (position-dependent) mass distribution is incorporated. Orthogonal sets of normalizable bound state solutions are constructed in explicit form, and the associated energies are determined. We compare our results with the corresponding findings on the constant-mass problem discussed by Ioriatti (1990) [13]. -- Highlights: ► We introduce an exactly solvable, position-dependent mass model for the Thomas–Fermi potential. ► Orthogonal sets of solutions to our model are constructed inmore » closed form. ► Relation to delta-doped semiconductors is discussed. ► Explicit subband bottom energies are calculated and compared to results obtained in a previous study.« less

Constraining the mass–richness relationship of redMaPPer clusters with angular clustering

DOE PAGES

Baxter, Eric J.; Rozo, Eduardo; Jain, Bhuvnesh; ...

2016-08-04

The potential of using cluster clustering for calibrating the mass–richness relation of galaxy clusters has been recognized theoretically for over a decade. In this paper, we demonstrate the feasibility of this technique to achieve high-precision mass calibration using redMaPPer clusters in the Sloan Digital Sky Survey North Galactic Cap. By including cross-correlations between several richness bins in our analysis, we significantly improve the statistical precision of our mass constraints. The amplitude of the mass–richness relation is constrained to 7 per cent statistical precision by our analysis. However, the error budget is systematics dominated, reaching a 19 per cent total errormore » that is dominated by theoretical uncertainty in the bias–mass relation for dark matter haloes. We confirm the result from Miyatake et al. that the clustering amplitude of redMaPPer clusters depends on galaxy concentration as defined therein, and we provide additional evidence that this dependence cannot be sourced by mass dependences: some other effect must account for the observed variation in clustering amplitude with galaxy concentration. Assuming that the observed dependence of redMaPPer clustering on galaxy concentration is a form of assembly bias, we find that such effects introduce a systematic error on the amplitude of the mass–richness relation that is comparable to the error bar from statistical noise. Finally, the results presented here demonstrate the power of cluster clustering for mass calibration and cosmology provided the current theoretical systematics can be ameliorated.« less

Position dependent mass Schroedinger equation and isospectral potentials: Intertwining operator approach

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

Midya, Bikashkali; Roy, B.; Roychoudhury, R.

2010-02-15

Here, we have studied first- and second-order intertwining approaches to generate isospectral partner potentials of position dependent (effective) mass Schroedinger equation. The second-order intertwiner is constructed directly by taking it as second-order linear differential operator with position dependent coefficients, and the system of equations arising from the intertwining relationship is solved for the coefficients by taking an ansatz. A complete scheme for obtaining general solution is obtained, which is valid for any arbitrary potential and mass function. The proposed technique allows us to generate isospectral potentials with the following spectral modifications: (i) to add new bound state(s), (ii) to removemore » bound state(s), and (iii) to leave the spectrum unaffected. To explain our findings with the help of an illustration, we have used point canonical transformation to obtain the general solution of the position dependent mass Schrodinger equation corresponding to a potential and mass function. It is shown that our results are consistent with the formulation of type A N-fold supersymmetry [T. Tanaka, J. Phys. A 39, 219 (2006); A. Gonzalez-Lopez and T. Tanaka, J. Phys. A 39, 3715 (2006)] for the particular cases N=1 and N=2, respectively.« less

Transmission of vibration through glove materials: effects of contact force.

PubMed

Md Rezali, Khairil Anas; Griffin, Michael J

2018-04-26

This study investigated effects of applied force on the apparent mass of the hand, the dynamic stiffness of glove materials and the transmission of vibration through gloves to the hand. For 10 subjects, 3 glove materials and 3 contact forces, apparent masses and glove transmissibilities were measured at the palm and at a finger at frequencies in the range 5-300 Hz. The dynamic stiffnesses of the materials were also measured. With increasing force, the dynamic stiffnesses of the materials increased, the apparent mass at the palm increased at frequencies greater than the resonance and the apparent mass at the finger increased at low frequencies. The effects of force on transmissibilities therefore differed between materials and depended on vibration frequency, but changes in apparent mass and dynamic stiffness had predictable effects on material transmissibility. Depending on the glove material, the transmission of vibration through a glove can be increased or decreased when increasing the applied force. Practitioner summary: Increasing the contact force (i.e. push force or grip force) can increase or decrease the transmission of vibration through a glove. The vibration transmissibilities of gloves should be assessed with a range of contact forces to understand their likely influence on the exposure of the hand and fingers to vibration.

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. © 2013 The Authors. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles.

An Update on the Non-Mass-Dependent Isotope Fractionation under Thermal Gradient

NASA Technical Reports Server (NTRS)

Sun, Tao; Niles, Paul; Bao, Huiming; Socki, Richard; Liu, Yun

2013-01-01

Mass flow and compositional gradient (elemental and isotope separation) occurs when flu-id(s) or gas(es) in an enclosure is subjected to a thermal gradient, and the phenomenon is named thermal diffusion. Gas phase thermal diffusion has been theoretically and experimentally studied for more than a century, although there has not been a satisfactory theory to date. Nevertheless, for isotopic system, the Chapman-Enskog theory predicts that the mass difference is the only term in the thermal diffusion separation factors that differs one isotope pair to another,with the assumptions that the molecules are spherical and systematic (monoatomic-like structure) and the particle collision is elastic. Our previous report indicates factors may be playing a role because the Non-Mass Dependent (NMD) effect is found for both symmetric and asymmetric, linear and spherical polyatomic molecules over a wide range of temperature (-196C to +237C). The observed NMD phenomenon in the simple thermal-diffusion experiments demands quantitative validation and theoretical explanation. Besides the pressure and temperature dependency illustrated in our previous reports, efforts are made in this study to address issues such as the role of convection or molecular structure and whether it is a transient, non-equilibrium effect only.

The effect of mass loading on the temperature of a flowing plasma. [in vicinity of Io

NASA Technical Reports Server (NTRS)

Linker, Jon A.; Kivelson, Margaret G.; Walker, Raymond J.

1989-01-01

How the addition of ions at rest (mass loading) affects the temperature of a flowing plasma in a MHD approximation is investigated, using analytic theory and time dependent, three-dimensional MHD simulations of plasma flow past Io. The MHD equations show that the temperature can increase or decrease relative to the background, depending on the local sonic Mach number M(S), of the flow. For flows with M(S) of greater than sq rt 9/5 (when gamma = 5/3), mass loading increases the plasma temperature. However, the simulations show a nonlinear response to the addition of mass. If the mass loading rate is large enough, the temperature increase may be smaller than expected, or the temperature may actually decrease, because a large mass loading rate slows the flow and decreases the thermal energy of the newly created plasma.

Mass Independent Fractionation of Cadmium Isotopes During Thermal Ionization

NASA Astrophysics Data System (ADS)

Abouchami, W.; Galer, S. J.; Feldmann, H.; Schmitt, A. D.

2008-12-01

We have previously reported that Cd isotopes exhibit anomalous, non-mass dependent fractionation of odd versus even isotopes when measured by TIMS using silica gel-phosphoric acid activator. The deviation from mass dependent fractionation (MDF) on the odd masses 111 and 113 varies by fractions of a per-cent between runs. The effects cannot be explained by isobaric interferences, but seem, instead, to reflect mass independent fractionation (MIF) of Cd isotopes, much like that recently documented for Hg isotopes in natural systems (Bergquist and Blum, 2007). The absence of comparable Cd isotope anomalies in the ICP torch, and during extreme in-vacuo volatilization of Cd metal (Wombacher et al., 2004) conclusively implicates the silica gel activator in the process. So far, MIF has been documented for Cd, Zn and Pb isotopes when measured using the silica gel technique (Thirlwall, 2000; Schmitt et al., 2006; Manhes and Göpel, 2007). These MIF effects on Cd isotopes might perhaps be related to the non-mass dependence of nuclear volume with mass number, as described by Bigeleisen (1996) - also known as the "nuclear field shift". The MIF caused by the nuclear field shift results is a departure from MDF broadly characterized by a odd-even staggering with mass number. These effects have been quantified by Schauble (2007) who showed that the magnitude of the non-mass dependence for Hg and Tl isotopes lies in the ppm range for some simple reactions. Such MIF effects would appear, overall, far too small to account for our data, which require MIF offsets on the odd masses 111 and 113 approaching a per-cent. Moreover, an in-depth examination along the lines of Fujii et al. (2006) predicts tell-tale offsets for the even-even isotope pairs 114Cd/112Cd and 116Cd/112Cd as well, based upon the theory and the respective nuclear radii, but such accompanying offsets are unequivocally absent in our data. The odd-even isotope effects seen in our runs using silica gel activator are better explained by appealing to the nuclear spin (and magnetic moment) of odd nuclei alone. The "magnetic isotope effect" is a consequence of hyperfine coupling, in which an electron interacts with a nucleus of non-zero magnetic moment - i.e. one that has an odd number of nucleons (Turro, 1983; Buchachenko, 1995, 2001). This is purely a kinetic phenomenon in which the life-time, and thus the outcome, of reaction transition states is altered by the hyperfine splitting present in atoms with odd nuclei. The mechanism by which silica gel activator enhances the thermal ionization of elements such as Cd, Pb and Zn has been outlined by Kessinger and Delmore (2002). The first step involves the in-situ reduction of Cd2+ ions to Cd metal in the molten silica gel-phosphoric acid glass. It is most likely in this step - whereby two electrons are added - that a suitably long-lived transition state exists, during which the magnetic isotope effect enhances (or inhibits) reduction of masses 111 and 113 to metal species compared to those of even isotopes of Cd. The resulting "odd" and "even" populations of Cd-metal in the molten silica gel then cannot be related simply in terms of MDF. Overall, the magnetic isotope effect provides the best explanation of the MIF effects observed for Pb, Cd and Zn during thermal ionization with silica gel activator, and, probably, why the measured fractionation is always biased towards light isotopes.

Detecting effects of filaments on galaxy properties in the Sloan Digital Sky Survey III

NASA Astrophysics Data System (ADS)

Chen, Yen-Chi; Ho, Shirley; Mandelbaum, Rachel; Bahcall, Neta A.; Brownstein, Joel R.; Freeman, Peter E.; Genovese, Christopher R.; Schneider, Donald P.; Wasserman, Larry

2017-04-01

We study the effects of filaments on galaxy properties in the Sloan Digital Sky Survey (SDSS) Data Release 12 using filaments from the 'Cosmic Web Reconstruction' catalogue, a publicly available filament catalogue for SDSS. Since filaments are tracers of medium- to high-density regions, we expect that galaxy properties associated with the environment are dependent on the distance to the nearest filament. Our analysis demonstrates that a red galaxy or a high-mass galaxy tends to reside closer to filaments than a blue or low-mass galaxy. After adjusting the effect from stellar mass, on average, early-forming galaxies or large galaxies have a shorter distance to filaments than late-forming galaxies or small galaxies. For the main galaxy sample, all signals are very significant (>6σ). For the LOWZ and CMASS sample, the stellar mass and size are significant (>2σ). The filament effects we observe persist until z = 0.7 (the edge of the CMASS sample). Comparing our results to those using the galaxy distances from redMaPPer galaxy clusters as a reference, we find a similar result between filaments and clusters. Moreover, we find that the effect of clusters on the stellar mass of nearby galaxies depends on the galaxy's filamentary environment. Our findings illustrate the strong correlation of galaxy properties with proximity to density ridges, strongly supporting the claim that density ridges are good tracers of filaments.

Cosmic web and environmental dependence of screening: Vainshtein vs. chameleon

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

Falck, Bridget; Koyama, Kazuya; Zhao, Gong-Bo, E-mail: bridget.falck@port.ac.uk, E-mail: kazuya.koyama@port.ac.uk, E-mail: gong-bo.zhao@port.ac.uk

Theories which modify general relativity to explain the accelerated expansion of the Universe often use screening mechanisms to satisfy constraints on Solar System scales. We investigate the effects of the cosmic web and the local environmental density of dark matter halos on the screening properties of the Vainshtein and chameleon screening mechanisms. We compare the cosmic web morphology of dark matter particles, mass functions of dark matter halos, mass and radial dependence of screening, velocity dispersions and peculiar velocities, and environmental dependence of screening mechanisms in f(R) and nDGP models. Using the ORIGAMI cosmic web identification routine we find thatmore » the Vainshtein mechanism depends on the cosmic web morphology of dark matter particles, since these are defined according to the dimensionality of their collapse, while the chameleon mechanism shows no morphology dependence. The chameleon screening of halos and their velocity dispersions depend on halo mass, and small halos and subhalos can be environmentally screened in the chameleon mechanism. On the other hand, the screening of halos in the Vainshtein mechanism does not depend on mass nor environment, and their velocity dispersions are suppressed. The peculiar velocities of halos in the Vainshtein mechanism are enhanced because screened objects can still feel the fifth force generated by external fields, while peculiar velocities of chameleon halos are suppressed when the halo centers are screened.« less

On the link between energy equipartition and radial variation in the stellar mass function of star clusters

NASA Astrophysics Data System (ADS)

Webb, Jeremy J.; Vesperini, Enrico

2017-01-01

We make use of N-body simulations to determine the relationship between two observable parameters that are used to quantify mass segregation and energy equipartition in star clusters. Mass segregation can be quantified by measuring how the slope of a cluster's stellar mass function α changes with clustercentric distance r, and then calculating δ _α = d α (r)/d ln(r/r_m), where rm is the cluster's half-mass radius. The degree of energy equipartition in a cluster is quantified by η, which is a measure of how stellar velocity dispersion σ depends on stellar mass m via σ(m) ∝ m-η. Through a suite of N-body star cluster simulations with a range of initial sizes, binary fractions, orbits, black hole retention fractions, and initial mass functions, we present the co-evolution of δα and η. We find that measurements of the global η are strongly affected by the radial dependence of σ and mean stellar mass and the relationship between η and δα depends mainly on the cluster's initial conditions and the tidal field. Within rm, where these effects are minimized, we find that η and δα initially share a linear relationship. However, once the degree of mass segregation increases such that the radial dependence of σ and mean stellar mass become a factor within rm, or the cluster undergoes core collapse, the relationship breaks down. We propose a method for determining η within rm from an observational measurement of δα. In cases where η and δα can be measured independently, this new method offers a way of measuring the cluster's dynamical state.

Origins of mass-dependent and mass-independent Ca isotope variations in meteoritic components and meteorites

NASA Astrophysics Data System (ADS)

Bermingham, K. R.; Gussone, N.; Mezger, K.; Krause, J.

2018-04-01

The Ca isotope composition of meteorites and their components may vary due to mass-dependent and/or -independent isotope effects. In order to evaluate the origin of these effects, five amoeboid olivine aggregates (AOAs), three calcium aluminum inclusions (CAIs), five chondrules (C), a dark inclusion from Allende (CV3), two dark fragments from North West Africa 753 (NWA 753; R3.9), and a whole rock sample of Orgueil (CI1) were analyzed. This is the first coupled mass-dependent and -independent Ca isotope dataset to include AOAs, a dark inclusion, and dark fragments. Where sample masses permit, Ca isotope data are reported with corresponding petrographic analyses and rare earth element (REE) relative abundance patterns. The CAIs and AOAs are enriched in light Ca isotopes (δ44/40Ca -5.32 to +0.72, where δ44/40Ca is reported relative to SRM 915a). Samples CAI 5 and AOA 1 have anomalous Group II REE patterns. These REE and δ44/40Ca data suggest that the CAI 5 and AOA 1 compositions were set via kinetic isotope fractionation during condensation and evaporation. The remaining samples show mass-dependent Ca isotope variations which cluster between δ44/40Ca +0.53 and +1.59, some of which are coupled with unfractionated REE abundance patterns. These meteoritic components likely formed through the coaccretion of the evaporative residue and condensate following Group II CAI formation or their chemical and isotopic signatures were decoupled (e.g., via nebular or parent-body alteration). The whole rock sample of Orgueil has a δ44/40Ca +0.67 ± 0.18 which is in agreement with most published data. Parent-body alteration, terrestrial alteration, and variable sampling of Ca-rich meteoritic components can have an effect on δ44/40Ca compositions in whole rock meteorites. Samples AOA 1, CAI 5, C 2, and C 4 display mass-independent 48/44Ca anomalies (ε48/44Ca +6 to +12) which are resolved from the standard composition. Other samples measured for these effects (AOA 5, CAI 1, CAI 2, C 3, D 1, D 2, D 3) possess the same 48/44Ca isotope composition as the standard within analytical uncertainty. These data indicate a heterogeneous distribution of 48Ca in the early solar nebula during formation of CAIs, AOAs, and chondrules. In a ε48/44Ca vs. δ44/40Ca plot, no strong correlation is evident which suggests that the thermal processing event which caused a heterogeneous distribution of ε48/44Ca in the solar nebula is unlikely to be directly related to the thermal processing event that caused coupled REE and Ca mass-dependent isotopic fractionation in meteoritic components.

Revisiting the bulge-halo conspiracy - II. Towards explaining its puzzling dependence on redshift

NASA Astrophysics Data System (ADS)

Shankar, Francesco; Sonnenfeld, Alessandro; Grylls, Philip; Zanisi, Lorenzo; Nipoti, Carlo; Chae, Kyu-Hyun; Bernardi, Mariangela; Petrillo, Carlo Enrico; Huertas-Company, Marc; Mamon, Gary A.; Buchan, Stewart

2018-04-01

We carry out a systematic investigation of the total mass density profile of massive (log Mstar/M⊙ ˜ 11.5) early-type galaxies and its dependence on redshift, specifically in the range 0 ≲ z ≲ 1. We start from a large sample of Sloan Digital Sky Survey early-type galaxies with stellar masses and effective radii measured assuming two different profiles, de Vaucouleurs and Sérsic. We assign dark matter haloes to galaxies via abundance matching relations with standard ΛCDM profiles and concentrations. We then compute the total, mass-weighted density slope at the effective radius γ΄, and study its redshift dependence at fixed stellar mass. We find that a necessary condition to induce an increasingly flatter γ΄ at higher redshifts, as suggested by current strong lensing data, is to allow the intrinsic stellar profile of massive galaxies to be Sérsic and the input Sérsic index n to vary with redshift as n(z) ∝ (1 + z)δ, with δ ≲ -1. This conclusion holds irrespective of the input Mstar-Mhalo relation, the assumed stellar initial mass function (IMF), or even the chosen level of adiabatic contraction in the model. Secondary contributors to the observed redshift evolution of γ΄ may come from an increased contribution at higher redshifts of adiabatic contraction and/or bottom-light stellar IMFs. The strong lensing selection effects we have simulated seem not to contribute to this effect. A steadily increasing Sérsic index with cosmic time is supported by independent observations, though it is not yet clear whether cosmological hierarchical models (e.g. mergers) are capable of reproducing such a fast and sharp evolution.

Pebble-isolation mass: Scaling law and implications for the formation of super-Earths and gas giants

NASA Astrophysics Data System (ADS)

Bitsch, Bertram; Morbidelli, Alessandro; Johansen, Anders; Lega, Elena; Lambrechts, Michiel; Crida, Aurélien

2018-04-01

The growth of a planetary core by pebble accretion stops at the so-called pebble isolation mass, when the core generates a pressure bump that traps drifting pebbles outside its orbit. The value of the pebble isolation mass is crucial in determining the final planet mass. If the isolation mass is very low, gas accretion is protracted and the planet remains at a few Earth masses with a mainly solid composition. For higher values of the pebble isolation mass, the planet might be able to accrete gas from the protoplanetary disc and grow into a gas giant. Previous works have determined a scaling of the pebble isolation mass with cube of the disc aspect ratio. Here, we expand on previous measurements and explore the dependency of the pebble isolation mass on all relevant parameters of the protoplanetary disc. We use 3D hydrodynamical simulations to measure the pebble isolation mass and derive a simple scaling law that captures the dependence on the local disc structure and the turbulent viscosity parameter α. We find that small pebbles, coupled to the gas, with Stokes number τf < 0.005 can drift through the partial gap at pebble isolation mass. However, as the planetary mass increases, particles must be decreasingly smaller to penetrate the pressure bump. Turbulent diffusion of particles, however, can lead to an increase of the pebble isolation mass by a factor of two, depending on the strength of the background viscosity and on the pebble size. We finally explore the implications of the new scaling law of the pebble isolation mass on the formation of planetary systems by numerically integrating the growth and migration pathways of planets in evolving protoplanetary discs. Compared to models neglecting the dependence of the pebble isolation mass on the α-viscosity, our models including this effect result in higher core masses for giant planets. These higher core masses are more similar to the core masses of the giant planets in the solar system.

Correlations of neutron multiplicity and γ -ray multiplicity with fragment mass and total kinetic energy in spontaneous fission of Cf 252

DOE PAGES

Wang, Taofeng; Li, Guangwu; Zhu, Liping; ...

2016-01-08

The dependence of correlations of neutron multiplicity ν and γ-ray multiplicity M γ in spontaneous fission of 252Cf on fragment mass A* and total kinetic energy (TKE) have been investigated by employing the ratio of M γ/ν and the form of M γ(ν). We show for the first time that M γ and ν have a complex correlation for heavy fragment masses, while there is a positive dependence of Mγ for light fragment masses and for near-symmetric mass splits. The ratio M γ/ν exhibits strong shell effects for neutron magic number N=50 and near doubly magic number shell closure atmore » Z=50 and N=82. The γ-ray multiplicity Mγ has a maximum for TKE=165-170 MeV. Above 170 MeV M γ(TKE) is approximately linear, while it deviates significantly from a linear dependence at lower TKE. The correlation between the average neutron and γ-ray multiplicities can be partly reproduced by model calculations.« less

The harmonic oscillator and the position dependent mass Schroedinger equation: isospectral partners and factorization operators

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

Morales, J.; Ovando, G.; Pena, J. J.

2010-12-23

One of the most important scientific contributions of Professor Marcos Moshinsky has been his study on the harmonic oscillator in quantum theory vis a vis the standard Schroedinger equation with constant mass [1]. However, a simple description of the motion of a particle interacting with an external environment such as happen in compositionally graded alloys consist of replacing the mass by the so-called effective mass that is in general variable and dependent on position. Therefore, honoring in memoriam Marcos Moshinsky, in this work we consider the position-dependent mass Schrodinger equations (PDMSE) for the harmonic oscillator potential model as former potentialmore » as well as with equi-spaced spectrum solutions, i.e. harmonic oscillator isospectral partners. To that purpose, the point canonical transformation method to convert a general second order differential equation (DE), of Sturm-Liouville type, into a Schroedinger-like standard equation is applied to the PDMSE. In that case, the former potential associated to the PDMSE and the potential involved in the Schroedinger-like standard equation are related through a Riccati-type relationship that includes the equivalent of the Witten superpotential to determine the exactly solvable positions-dependent mass distribution (PDMD)m(x). Even though the proposed approach is exemplified with the harmonic oscillator potential, the procedure is general and can be straightforwardly applied to other DEs.« less

Considering the effect of the logging cable stretching under the influence of its own mass in the well on the accuracy of geophysical parameters determining

NASA Astrophysics Data System (ADS)

Kozhushko, A. A.; Pahotin, A. N.; Mal'tsev, V. N.; Bojarnikova, L. V.; Stepanova, E. P.

2018-04-01

The technology of carrying out various geophysical studies of oil wells using a carrying well-logging cable for the delivery of geophysical instruments and equipment is considered in the article. The relevance of the topic results from the need to evaluate the effect of well-logging cable stretching in the well under the influence of its own mass and mass of geophysical instruments and equipment on the accuracy and adequacy geophysical studies. Calculation formulas for determining the well-logging cable stretching under the influence of the geophysical tools and equipment mass without taking into account and taking into account the influence of the carrying well-logging cable mass are also presented. For three types of carrying well-logging cables, calculations were made of their stretching in the oil well under the mass of geophysical instruments and equipment and its own mass, depending on the depth of the investigated well. The analysis of the obtained results made it possible to numerically evaluate the extension of the carrying well-logging cable depending on the depth of the investigated well and by correcting the obtained results it allows to provide the required depth accuracy and reliability of the interpreted results of the geophysical studies.

Halo histories versus Galaxy properties at z = 0 - I. The quenching of star formation

NASA Astrophysics Data System (ADS)

Tinker, Jeremy L.; Wetzel, Andrew R.; Conroy, Charlie; Mao, Yao-Yuan

2017-12-01

We test whether halo age and galaxy age are correlated at fixed halo and galaxy mass. The formation histories, and thus ages, of dark matter haloes correlate with their large-scale density ρ, an effect known as assembly bias. We test whether this correlation extends to galaxies by measuring the dependence of galaxy stellar age on ρ. To clarify the comparison between theory and observation, and to remove the strong environmental effects on satellites, we use galaxy group catalogues to identify central galaxies and measure their quenched fraction, fQ, as a function of large-scale environment. Models that match halo age to central galaxy age predict a strong positive correlation between fQ and ρ. However, we show that the amplitude of this effect depends on the definition of halo age: assembly bias is significantly reduced when removing the effects of splashback haloes - those haloes that are central but have passed through a larger halo or experienced strong tidal encounters. Defining age using halo mass at its peak value rather than current mass removes these effects. In Sloan Digital Sky Survey data, at M* ≳ 1010 M⊙ h-2, there is a ∼5 per cent increase in fQ from low-to-high densities, which is in agreement with predictions of dark matter haloes using peak halo mass. At lower stellar mass there is little to no correlation of fQ with ρ. For these galaxies, age matching is inconsistent with the data across the range of halo formation metrics that we tested. This implies that halo formation history has a small but statistically significant impact on quenching of star formation at high masses, while the quenching process in low-mass central galaxies is uncorrelated with halo formation history.

Unexpected variations in the triple oxygen isotope composition of stratospheric carbon dioxide

NASA Astrophysics Data System (ADS)

Wiegel, Aaron A.; Cole, Amanda S.; Hoag, Katherine J.; Atlas, Elliot L.; Schauffler, Sue M.; Boering, Kristie A.

2013-10-01

We report observations of stratospheric CO2 that reveal surprisingly large anomalous enrichments in 17O that vary systematically with latitude, altitude, and season. The triple isotope slopes reached 1.95 ± 0.05(1σ) in the middle stratosphere and 2.22 ± 0.07 in the Arctic vortex versus 1.71 ± 0.03 from previous observations and a remarkable factor of 4 larger than the mass-dependent value of 0.52. Kinetics modeling of laboratory measurements of photochemical ozone-CO2 isotope exchange demonstrates that non-mass-dependent isotope effects in ozone formation alone quantitatively account for the 17O anomaly in CO2 in the laboratory, resolving long-standing discrepancies between models and laboratory measurements. Model sensitivities to hypothetical mass-dependent isotope effects in reactions involving O3, O(1D), or CO2 and to an empirically derived temperature dependence of the anomalous kinetic isotope effects in ozone formation then provide a conceptual framework for understanding the differences in the isotopic composition and the triple isotope slopes between the laboratory and the stratosphere and between different regions of the stratosphere. This understanding in turn provides a firmer foundation for the diverse biogeochemical and paleoclimate applications of 17O anomalies in tropospheric CO2, O2, mineral sulfates, and fossil bones and teeth, which all derive from stratospheric CO2.

Isotope fractionation by multicomponent diffusion (Invited)

NASA Astrophysics Data System (ADS)

Watkins, J. M.; Liang, Y.; Richter, F. M.; Ryerson, F. J.; DePaolo, D. J.

2013-12-01

Isotope fractionation by multicomponent diffusion The isotopic composition of mineral phases can be used to probe the temperatures and rates of mineral formation as well as the degree of post-mineralization alteration. The ability to interpret stable isotope variations is limited by our knowledge of three key parameters and their relative importance in determining the composition of a mineral grain and its surroundings: (1) thermodynamic (equilibrium) partitioning, (2) mass-dependent diffusivities, and (3) mass-dependent reaction rate coefficients. Understanding the mechanisms of diffusion and reaction in geological liquids, and how these mass transport processes discriminate between isotopes, represents an important problem that is receiving considerable attention in the geosciences. Our focus in this presentation will be isotope fractionation by chemical diffusion. Previous studies have documented that diffusive isotope effects vary depending on the cation as well as the liquid composition, but the ability to predict diffusive isotope effects from theory is limited; for example, it is unclear whether the magnitude of diffusive isotopic fractionations might also vary with the direction of diffusion in composition space. To test this hypothesis and to further guide the theoretical treatment of isotope diffusion, two chemical diffusion experiments and one self diffusion experiment were conducted at 1250°C and 0.7 GPa. In one experiment (A-B), CaO and Na2O counter-diffuse rapidly in the presence of a small SiO2 gradient. In the other experiment (D-E), CaO and SiO2 counter-diffuse more slowly in a small Na2O gradient. In both chemical diffusion experiments, Ca isotopes become fractionated by chemical diffusion but by different amounts, documenting for the first time that the magnitude of isotope fractionation by diffusion depends on the direction of diffusion in composition space. The magnitude of Ca isotope fractionation that develops is positively correlated with the rate of CaO diffusion; in A-B, the total variation is 2.5‰ whereas in D-E it is only 1.3‰. The diffusion of isotopes in a multicomponent system is modeled using a new expression for the isotope-specific diffusive flux that includes self diffusion terms in addition to the multicomponent chemical diffusion matrix. Kinetic theory predicts a mass dependence on isotopic mobility, i.e., self diffusivity, but it is unknown whether or how the mass dependence on self diffusivity translates into a mass dependence on chemical diffusion coefficients. The new experimental results allow us to assess several empirical expressions relating the self diffusivity and its mass dependence to the elements of the diffusion matrix and their mass dependence. Several plausible theoretical treatments can fit the data equally well. We are currently at the stage where experiments are guiding the theoretical treatment of the isotope fractionation by diffusion problem, underscoring the importance of experiments for aiding interpretations of isotopic variations in nature.

Isospin splitting of nucleon effective mass and symmetry energy in isotopic nuclear reactions

NASA Astrophysics Data System (ADS)

Guo, Ya-Fei; Chen, Peng-Hui; Niu, Fei; Zhang, Hong-Fei; Jin, Gen-Ming; Feng, Zhao-Qing

2017-10-01

Within an isospin and momentum dependent transport model, the dynamics of isospin particles (nucleons and light clusters) in Fermi-energy heavy-ion collisions are investigated for constraining the isospin splitting of nucleon effective mass and the symmetry energy at subsaturation densities. The impacts of the isoscalar and isovector parts of the momentum dependent interaction on the emissions of isospin particles are explored, i.e., the mass splittings of and (). The single and double neutron to proton ratios of free nucleons and light particles are thoroughly investigated in the isotopic nuclear reactions of 112Sn+112Sn and 124Sn+124Sn at incident energies of 50 and 120 MeV/nucleon, respectively. It is found that both the effective mass splitting and symmetry energy impact the kinetic energy spectra of the single ratios, in particular at the high energy tail (larger than 20 MeV). The isospin splitting of nucleon effective mass slightly impacts the double ratio spectra at the energy of 50 MeV/nucleon. A soft symmetry energy with stiffness coefficient of γ s=0.5 is constrained from the experimental data with the Fermi-energy heavy-ion collisions. Supported by Major State Basic Research Development Program in China (2014CB845405, 2015CB856903), National Natural Science Foundation of China (11722546, 11675226, 11675066, U1332207) and Youth Innovation Promotion Association of Chinese Academy of Sciences

On the evaluation of air mass factors for atmospheric near-ultraviolet and visible absorption spectroscopy

NASA Technical Reports Server (NTRS)

Perliski, Lori M.; Solomon, Susan

1993-01-01

The interpretation of UV-visible twilight absorption measurements of atmospheric chemical constituents is dependent on how well the optical path, or air mass factor, of light collected by the spectrometer is understood. A simple single scattering model and a Monte Carlo radiative transfer scheme have been developed to study the effects of multiple scattering, aerosol scattering, surface albedo and refraction on air mass factors for scattered light observations. At fairly short visible wavelengths (less than about 450 nm), stratospheric air mass factors are found to be relatively insensitive to multiple scattering, surface albedo and refraction, as well as aerosol scattering by background aerosols. Longer wavelengths display greater sensitivity to refraction and aerosol scattering. Tropospheric air mass factors are found to be highly dependent on aerosol scattering, surface albedo and, at long visible wavelengths (about 650 nm), refraction. Absorption measurements of NO2 and O4 are shown to support these conclusions.

Hydromechanical coupling in fractured rock masses: mechanisms and processes of selected case studies

NASA Astrophysics Data System (ADS)

Zangerl, Christian

2015-04-01

Hydromechanical (HM) coupling in fractured rock play an important role when events including dam failures, landslides, surface subsidences due to water withdrawal or drainage, injection-induced earthquakes and others are analysed. Generally, hydromechanical coupling occurs when a rock mass contain interconnected pores and fractures which are filled with water and pore/fracture pressures evolves. In the on hand changes in the fluid pressure can lead to stress changes, deformations and failures of the rock mass. In the other hand rock mass stress changes and deformations can alter the hydraulic properties and fluid pressures of the rock mass. Herein well documented case studies focussing on surface subsidence due to water withdrawal, reversible deformations of large-scale valley flanks and failure as well as deformation processes of deep-seated rock slides in fractured rock masses are presented. Due to pore pressure variations HM coupling can lead to predominantly reversible rock mass deformations. Such processes can be considered by the theory of poroelasticity. Surface subsidence reaching magnitudes of few centimetres and are caused by water drainage into deep tunnels are phenomenas which can be assigned to processes of poroelasticity. Recently, particular focus was given on large tunnelling projects to monitor and predict surface subsidence in fractured rock mass in oder to avoid damage of surface structures such as dams of large reservoirs. It was found that surface subsidence due to tunnel drainage can adversely effect infrastructure when pore pressure drawdown is sufficiently large and spatially extended and differential displacements which can be amplified due to topographical effects e.g. valley closure are occurring. Reversible surface deformations were also ascertained on large mountain slopes and summits with the help of precise deformation measurements i.e. permanent GPS or episodic levelling/tacheometric methods. These reversible deformations are often in the range of millimetres to a very few centimetres and can be linked to annual groundwater fluctuations. Due to pore pressure variations HM coupling can influence seepage forces and effective stresses in the rock mass. Effective stress changes can adversely affect the stability and deformation behaviour of deep-seated rock slides by influencing the shear strength or the time dependent (viscous) material behaviour of the basal shear zone. The shear strength of active shear zones is often reasonably well described by Coulomb's law. In Coulomb's law the operative normal stresses to the shear surface/zone are effective stresses and hence pore pressures which should be taken into account reduces the shear strength. According to the time dependent material behaviour a few effective stress based viscous models exists which are able to consider pore pressures. For slowly moving rock slides HM coupling could be highly relevant when low-permeability clayey-silty shear zones (fault gouges) are existing. An important parameters therefore is the hydraulic diffusivity, which is controlled by the permeability and fluid-pore compressibility of the shear zone, and by fluid viscosity. Thus time dependent pore pressure diffusion in the shear zone can either control the stability condition or the viscous behaviour (creep) of the rock slide. Numerous cases studies show that HM coupling can effect deformability, shear strength and time dependent behaviour of fractured rock masses. A process-based consideration can be important to avoid unexpected impacts on infrastructures and to understand complex rock mass as well rock slide behaviour.

Halo Intrinsic Alignment: Dependence on Mass, Formation Time, and Environment

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

Xia, Qianli; Kang, Xi; Wang, Peng

In this paper we use high-resolution cosmological simulations to study halo intrinsic alignment and its dependence on mass, formation time, and large-scale environment. In agreement with previous studies using N -body simulations, it is found that massive halos have stronger alignment. For the first time, we find that for a given halo mass older halos have stronger alignment and halos in cluster regions also have stronger alignment than those in filaments. To model these dependencies, we extend the linear alignment model with inclusion of halo bias and find that the halo alignment with its mass and formation time dependence canmore » be explained by halo bias. However, the model cannot account for the environment dependence, as it is found that halo bias is lower in clusters and higher in filaments. Our results suggest that halo bias and environment are independent factors in determining halo alignment. We also study the halo alignment correlation function and find that halos are strongly clustered along their major axes and less clustered along the minor axes. The correlated halo alignment can extend to scales as large as 100 h {sup −1} Mpc, where its feature is mainly driven by the baryon acoustic oscillation effect.« less

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.

Neutron-proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon-nucleus scattering data within an isospin dependent optical model

NASA Astrophysics Data System (ADS)

Li, Xiao-Hua; Guo, Wen-Jun; Li, Bao-An; Chen, Lie-Wen; Fattoyev, Farrukh J.; Newton, William G.

2015-04-01

The neutron-proton effective mass splitting in asymmetric nucleonic matter of isospin asymmetry δ and normal density is found to be mn-p* ≡ (mn* - mp*) / m = (0.41 ± 0.15) δ from analyzing globally 1088 sets of reaction and angular differential cross sections of proton elastic scattering on 130 targets with beam energies from 0.783 MeV to 200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets with beam energies from 0.05 MeV to 200 MeV within an isospin dependent non-relativistic optical potential model. It sets a useful reference for testing model predictions on the momentum dependence of the nucleon isovector potential necessary for understanding novel structures and reactions of rare isotopes.

Delay-dependent stability and added damping of SDOF real-time dynamic hybrid testing

NASA Astrophysics Data System (ADS)

Chi, Fudong; Wang, Jinting; Jin, Feng

2010-09-01

It is well-recognized that a transfer system response delay that reduces the test stability inevitably exists in real-time dynamic hybrid testing (RTDHT). This paper focuses on the delay-dependent stability and added damping of SDOF systems in RTDHT. The exponential delay term is transferred into a rational fraction by the Padé approximation, and the delay-dependent stability conditions and instability mechanism of SDOF RTDHT systems are investigated by the root locus technique. First, the stability conditions are discussed separately for the cases of stiffness, mass, and damping experimental substructure. The use of root locus plots shows that the added damping effect and instability mechanism for mass are different from those for stiffness. For the stiffness experimental substructure case, the instability results from the inherent mode because of an obvious negative damping effect of the delay. For the mass case, the delay introduces an equivalent positive damping into the inherent mode, and instability occurs at an added high frequency mode. Then, the compound stability condition is investigated for a general case and the results show that the mass ratio may have both upper and lower limits to remain stable. Finally, a high-emulational virtual shaking table model is built to validate the stability conclusions.

Electron Mobilities and Effective Masses in InGaAs/InAlAs HEMT Structures with High In Content

NASA Astrophysics Data System (ADS)

Yuzeeva, N. A.; Sorokoumova, A. V.; Lunin, R. A.; Oveshnikov, L. N.; Galiev, G. B.; Klimov, E. A.; Lavruchin, D. V.; Kulbachinskii, V. A.

2016-12-01

InxGa_{1-{x}}As/InyAl_{1-{y}}As HEMT structures {δ}-doped by Si were grown by molecular beam epitaxy on InP substrate. We investigated the influence of the In content on the electron mobilities and effective masses in dimensionally quantized subbands. The electron effective masses were determined by the temperature dependence of the amplitude of the Shubnikov-de Haas effect at 1.6 and 4.2 K. We found that the more the In content in quantum well (QW), the less the electron effective masses. The mobilities are higher in HEMT structures with wider and deeper QW. The energy band diagrams were calculated by using Vegard's law for basic parameters. The calculated band diagrams are in a good agreement with the experimental data of photoluminescence spectra.

Time-dependent mass of cosmological perturbations in the hybrid and dressed metric approaches to loop quantum cosmology

NASA Astrophysics Data System (ADS)

Elizaga Navascués, Beatriz; Martín de Blas, Daniel; Mena Marugán, Guillermo A.

2018-02-01

Loop quantum cosmology has recently been applied in order to extend the analysis of primordial perturbations to the Planck era and discuss the possible effects of quantum geometry on the cosmic microwave background. Two approaches to loop quantum cosmology with admissible ultraviolet behavior leading to predictions that are compatible with observations are the so-called hybrid and dressed metric approaches. In spite of their similarities and relations, we show in this work that the effective equations that they provide for the evolution of the tensor and scalar perturbations are somewhat different. When backreaction is neglected, the discrepancy appears only in the time-dependent mass term of the corresponding field equations. We explain the origin of this difference, arising from the distinct quantization procedures. Besides, given the privileged role that the big bounce plays in loop quantum cosmology, e.g. as a natural instant of time to set initial conditions for the perturbations, we also analyze the positivity of the time-dependent mass when this bounce occurs. We prove that the mass of the tensor perturbations is positive in the hybrid approach when the kinetic contribution to the energy density of the inflaton dominates over its potential, as well as for a considerably large sector of backgrounds around that situation, while this mass is always nonpositive in the dressed metric approach. Similar results are demonstrated for the scalar perturbations in a sector of background solutions that includes the kinetically dominated ones; namely, the mass then is positive for the hybrid approach, whereas it typically becomes negative in the dressed metric case. More precisely, this last statement is strictly valid when the potential is quadratic for values of the inflaton mass that are phenomenologically favored.

Large magnetoresistance in the type-II Weyl semimetal WP 2

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

Wang, Aifeng; Graf, D.; Liu, Yu

In this paper, we report a magnetotransport study on type-II Weyl semimetal WP 2 single crystals. Magnetoresistance exhibits a nonsaturating H n field dependence (14 300% at 2 K and 9 T), whereas systematic violation of Kohler's rule was observed. Quantum oscillations reveal a complex multiband electronic structure. The cyclotron effective mass close to the mass of free electron m e was observed in quantum oscillations along the b axis, while a reduced effective mass of about 0.5 m e was observed in α-axis quantum oscillations, suggesting Fermi surface anisotropy. The temperature dependence of the resistivity shows a large upturnmore » that cannot be explained by the multiband magnetoresistance of conventional metals. Finally, even though the crystal structure of WP 2 is not layered as in transition-metal dichalcogenides, quantum oscillations suggest partial two-dimensional character.« less

Large magnetoresistance in the type-II Weyl semimetal WP 2

DOE PAGES

Wang, Aifeng; Graf, D.; Liu, Yu; ...

2017-09-11

In this paper, we report a magnetotransport study on type-II Weyl semimetal WP 2 single crystals. Magnetoresistance exhibits a nonsaturating H n field dependence (14 300% at 2 K and 9 T), whereas systematic violation of Kohler's rule was observed. Quantum oscillations reveal a complex multiband electronic structure. The cyclotron effective mass close to the mass of free electron m e was observed in quantum oscillations along the b axis, while a reduced effective mass of about 0.5 m e was observed in α-axis quantum oscillations, suggesting Fermi surface anisotropy. The temperature dependence of the resistivity shows a large upturnmore » that cannot be explained by the multiband magnetoresistance of conventional metals. Finally, even though the crystal structure of WP 2 is not layered as in transition-metal dichalcogenides, quantum oscillations suggest partial two-dimensional character.« less

Near-infrared reddening of extra-galactic giant molecular clouds in a face-on geometry

NASA Astrophysics Data System (ADS)

Kainulainen, J.; Juvela, M.; Alves, J.

2008-04-01

Aims: We describe the near-infrared reddening signature of giant molecular clouds (GMCs) in external galaxies. In particular, we examine the EJ-H and EH-K color excesses and the effective extinction law observed in discrete GMC regions. We also study the effect of the relative scale height of the GMC distribution to the color excesses, and to the observed mass function of GMCs when the masses are derived using color excess as a linear estimator of mass. Methods: We performed Monte Carlo radiative transfer simulations with 3D models of stellar radiation and clumpy dust distributions, resembling a face-on geometry. The scattered light is included in the models, and near-infrared color maps were calculated from the simulated data. We performed the simulations with different scale heights of GMCs and compared the color excesses and attenuation of light in different geometries. We extracted GMCs from the simulated color maps and compared the mass functions to the input mass functions. Results: The effective near-infrared reddening law, i.e. the ratio EJ-H/EH-K, has a value close to unity in GMC regions. The ratio depends significantly on the relative scale height of GMCs, ξ, and for ξ values 0.1...0.75, we find the typical ratios of 0.6...1.1. The effective extinction law turns out to be very flat in GMC regions. We find the ratios of apparent extinctions of AH^a/AKa = 1.35...1.55 and AJ^a/AHa = 1.15. The effect of the scattered flux on the effective reddening law, as well as on the effective extinction law, is significant. Regarding the GMC mass function, we find no correlation between the input and observed slopes of the mass functions. Instead, the observed slope reflects the parameter ξ and the dynamical range of the mass function. As the observed slope depends on the geometric parameters, which are not known, it is not possible to constrain the slope of the mass function using this technique. We estimate that only a fraction of 10...20% of the total mass of GMCs is recovered, if the observed color excess values are transformed to masses using the Galactic reddening law. In the case of individual clouds, the fraction can vary between ~0...50%.

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

Eich, F. G.; Agostini, Federica, E-mail: agostini@mpi-halle.mpg.de

We propose a procedure to analyze the relation between the exact factorization of the electron-nuclear wave function and the Born-Oppenheimer approximation. We define the adiabatic limit as the limit of infinite nuclear mass. To this end, we introduce a unit system that singles out the dependence on the electron-nuclear mass ratio of each term appearing in the equations of the exact factorization. We observe how non-adiabatic effects induced by the coupling to the nuclear motion affect electronic properties and we analyze the leading term, connecting it to the classical nuclear momentum. Its dependence on the mass ratio is tested numericallymore » on a model of proton-coupled electron transfer in different non-adiabatic regimes.« less

The rise and fall of stellar across the peak of cosmic star formation history: effects of mergers versus diffuse stellar mass acquisition

NASA Astrophysics Data System (ADS)

Welker, C.; Dubois, Y.; Devriendt, J.; Pichon, C.; Kaviraj, S.; Peirani, S.

2017-02-01

Building galaxy merger trees from a state-of-the-art cosmological hydrodynamical simulation, Horizon-AGN, we perform a statistical study of how mergers and diffuse stellar mass acquisition processes drive galaxy morphologic properties above z > 1. By diffuse mass acquisition here, we mean both accretion of stars by unresolved mergers (relative stellar mass growth smaller than 4.5 per cent) as well as in situ star formation when no resolved mergers are detected along the main progenitor branch of a galaxy. We investigate how stellar densities, galaxy sizes and galaxy morphologies (defined via shape parameters derived from the inertia tensor of the stellar density) depend on mergers of different mass ratios. We investigate how stellar densities, effective radii and shape parameters derived from the inertia tensor depend on mergers of different mass ratios. We find strong evidence that diffuse stellar accretion and in situ formation tend to flatten small galaxies over cosmic time, leading to the formation of discs. On the other hand, mergers, and not only the major ones, exhibit a propensity to puff up and destroy stellar discs, confirming the origin of elliptical galaxies. We confirm that mergers grow galaxy sizes more efficiently than diffuse processes (r_{0.5}∝ M_s^{0.85} and r_{0.5}∝ M_s^{0.1} on average, respectively) and we also find that elliptical galaxies are more susceptible to grow in size through mergers than disc galaxies with a size-mass evolution r_{0.5}∝ M_s^{1.2} instead of r_{0.5}∝ M_s^{-0.5}-M^{0.5} for discs depending on the merger mass ratio. The gas content drives the size-mass evolution due to merger with a faster size growth for gas-poor galaxies r_{0.5}∝ M_s2 than for gas-rich galaxies r0.5 ∝ Ms.

The immitigable nature of assembly bias: the impact of halo definition on assembly bias

NASA Astrophysics Data System (ADS)

Villarreal, Antonio S.; Zentner, Andrew R.; Mao, Yao-Yuan; Purcell, Chris W.; van den Bosch, Frank C.; Diemer, Benedikt; Lange, Johannes U.; Wang, Kuan; Campbell, Duncan

2017-11-01

Dark matter halo clustering depends not only on halo mass, but also on other properties such as concentration and shape. This phenomenon is known broadly as assembly bias. We explore the dependence of assembly bias on halo definition, parametrized by spherical overdensity parameter, Δ. We summarize the strength of concentration-, shape-, and spin-dependent halo clustering as a function of halo mass and halo definition. Concentration-dependent clustering depends strongly on mass at all Δ. For conventional halo definitions (Δ ∼ 200 - 600 m), concentration-dependent clustering at low mass is driven by a population of haloes that is altered through interactions with neighbouring haloes. Concentration-dependent clustering can be greatly reduced through a mass-dependent halo definition with Δ ∼ 20 - 40 m for haloes with M200 m ≲ 1012 h-1M⊙. Smaller Δ implies larger radii and mitigates assembly bias at low mass by subsuming altered, so-called backsplash haloes into now larger host haloes. At higher masses (M200 m ≳ 1013 h-1M⊙) larger overdensities, Δ ≳ 600 m, are necessary. Shape- and spin-dependent clustering are significant for all halo definitions that we explore and exhibit a relatively weaker mass dependence. Generally, both the strength and the sense of assembly bias depend on halo definition, varying significantly even among common definitions. We identify no halo definition that mitigates all manifestations of assembly bias. A halo definition that mitigates assembly bias based on one halo property (e.g. concentration) must be mass dependent. The halo definitions that best mitigate concentration-dependent halo clustering do not coincide with the expected average splashback radii at fixed halo mass.

Pressure Dependence of the Specific-Heat Jump at the Superfluid Transition and the Effective Mass of 3He

NASA Astrophysics Data System (ADS)

Alvesalo, T. A.; Haavasoja, T.; Manninen, M. T.; Soinne, A. T.

1980-04-01

The specific heat of liquid 3He has been measured from 1 to 10 mK between 0 and 32.5 bars. The values implied for the effective mass are considerably smaller than the currently accepted ones. Near zero pressure the specific-heat jump is close to the BCS value 1.43, and at 32.5 bars it has reached 1.90 in the B phase and 2.04 in the A phase. The temperature dependence of the specific heat in the B phase agrees with a model of Serene and Rainer. The latent heat at the A-B transition has been measured.

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

Carbone, L.; Ciani, G.; Dolesi, R.

The low frequency sensitivity of space-borne gravitational wave observatories will depend critically on the geodesic purity of the trajectories of orbiting test masses. Fluctuations in the temperature difference across the enclosure surrounding the free-falling test mass can produce noisy forces through several processes, including the radiometric effect, radiation pressure, and outgassing. We present here a detailed experimental investigation of thermal gradient-induced forces for the Laser Interferometer Space Antenna (LISA) gravitational wave mission and the LISA Pathfinder, employing high resolution torsion pendulum measurements of the torque on a LISA-like test mass suspended inside a prototype of the LISA gravitational reference sensormore » that will surround the test mass in orbit. The measurement campaign, accompanied by numerical simulations of the radiometric and radiation pressure effects, allows a more accurate and representative characterization of thermal-gradient forces in the specific geometry and environment relevant to LISA free-fall. The pressure dependence of the measured torques allows clear identification of the radiometric effect, in quantitative agreement with the model developed. In the limit of zero gas pressure, the measurements are most likely dominated by outgassing, but at a low level that does not threaten the current LISA noise estimate, which assumes a maximum net force per degree of temperature difference of 100(pN/K) for the overall thermal gradient-induced effects.« less

Transgenic rescue of adipocyte glucose-dependent insulinotropic polypeptide receptor expression restores high fat diet-induced body weight gain.

PubMed

Ugleholdt, Randi; Pedersen, Jens; Bassi, Maria Rosaria; Füchtbauer, Ernst-Martin; Jørgensen, Signe Marie; Kissow, Hanne-Louise; Nytofte, Nikolaj; Poulsen, Steen Seier; Rosenkilde, Mette Marie; Seino, Yutaka; Thams, Peter; Holst, Peter Johannes; Holst, Jens Juul

2011-12-30

The glucose-dependent insulinotropic polypeptide receptor (GIPr) has been implicated in high fat diet-induced obesity and is proposed as an anti-obesity target despite an uncertainty regarding the mechanism of action. To independently investigate the contribution of the insulinotropic effects and the direct effects on adipose tissue, we generated transgenic mice with targeted expression of the human GIPr to white adipose tissue or beta-cells, respectively. These mice were then cross-bred with the GIPr knock-out strain. The central findings of the study are that mice with GIPr expression targeted to adipose tissue have a similar high fat diet -induced body weight gain as control mice, significantly greater than the weight gain in mice with a general ablation of the receptor. Surprisingly, this difference was due to an increase in total lean body mass rather than a gain in total fat mass that was similar between the groups. In contrast, glucose-dependent insulinotropic polypeptide-mediated insulin secretion does not seem to be important for regulation of body weight after high fat feeding. The study supports a role of the adipocyte GIPr in nutrient-dependent regulation of body weight and lean mass, but it does not support a direct and independent role for the adipocyte or beta-cell GIPr in promoting adipogenesis.

Mass-improvement of the vector current in three-flavor QCD

NASA Astrophysics Data System (ADS)

Fritzsch, P.

2018-06-01

We determine two improvement coefficients which are relevant to cancel mass-dependent cutoff effects in correlation functions with operator insertions of the non-singlet local QCD vector current. This determination is based on degenerate three-flavor QCD simulations of non-perturbatively O( a) improved Wilson fermions with tree-level improved gauge action. Employing a very robust strategy that has been pioneered in the quenched approximation leads to an accurate estimate of a counterterm cancelling dynamical quark cutoff effects linear in the trace of the quark mass matrix. To our knowledge this is the first time that such an effect has been determined systematically with large significance.

Temporally dependent pollinator competition and facilitation with mass flowering crops affects yield in co-blooming crops

PubMed Central

Grab, Heather; Blitzer, Eleanor J.; Danforth, Bryan; Loeb, Greg; Poveda, Katja

2017-01-01

One of the greatest challenges in sustainable agricultural production is managing ecosystem services, such as pollination, in ways that maximize crop yields. Most efforts to increase services by wild pollinators focus on management of natural habitats surrounding farms or non-crop habitats within farms. However, mass flowering crops create resource pulses that may be important determinants of pollinator dynamics. Mass bloom attracts pollinators and it is unclear how this affects the pollination and yields of other co-blooming crops. We investigated the effects of mass flowering apple on the pollinator community and yield of co-blooming strawberry on farms spanning a gradient in cover of apple orchards in the landscape. The effect of mass flowering apple on strawberry was dependent on the stage of apple bloom. During early and peak apple bloom, pollinator abundance and yield were reduced in landscapes with high cover of apple orchards. Following peak apple bloom, pollinator abundance was greater on farms with high apple cover and corresponded with increased yields on these farms. Spatial and temporal overlap between mass flowering and co-blooming crops alters the strength and direction of these dynamics and suggests that yields can be optimized by designing agricultural systems that avoid competition while maximizing facilitation. PMID:28345653

Effect of Mass Proportion of Municipal Solid Waste Incinerator Bottom Ash Layer to Municipal Solid Waste Layer on the Cu and Zn Discharge from Landfill.

PubMed

Kong, Qingna; Yao, Jun; Qiu, Zhanhong; Shen, Dongsheng

2016-01-01

Municipal solid waste incinerator (MSWI) bottom ash is often used as the protection layer for the geomembrane and intermediate layer in the landfill. In this study, three sets of simulated landfills with different mass proportion of MSWI bottom ash layer to municipal solid waste (MSW) layer were operated. Cu and Zn concentrations in the leachates and MSW were monitored to investigate the effect of MSWI bottom ash layer on the Cu and Zn discharge from the landfill. The results showed that the Zn discharge was dependent on the mass proportion of MSWI bottom ash layer. The pH of landfill was not notably increased when the mass proportion of MSWI bottom ash layer to MSW layer was 1 : 9, resulting in the enhancement of the Zn discharge. However, Zn discharge was mitigated when the mass proportion was 2 : 8, as the pH of landfill was notably promoted. The discharge of Cu was not dependent on the mass proportion, due to the great affinity of Cu to organic matter. Moreover, Cu and Zn contents of the sub-MSW layer increased due to the MSWI bottom ash layer. Therefore, the MSWI bottom ash layer can increase the potential environmental threat of the landfill.

Effect of scaled Gaussian width (SGW) on fragment flow and multifragmentation in heavy-ion collisions

NASA Astrophysics Data System (ADS)

Rajni; Kumar, Suneel

2012-02-01

We have analyzed the role of interaction range on multifragmentation within the isospin-dependent quantum molecular dynamic (IQMD) model. We find that the effect of width of Gaussian wave packet associated with a nucleon depends on the mass of the colliding system. For a given set of input parameters, we find that width has a sizable effect. At the same time, we know that a different set of parameters can influence the reaction dynamics drastically. Hence, in our opinion it may not be possible to pin down the width to a very narrow level. A systematic study of mass effect ( 197Au, 124La, 124Sn, 107Sn in the breakup of a projectile spectator at intermediate energies has been performed. We also studied the disapperance of flow which demonstrates the effect of the scaled Gaussian width (SGW). Our studies shows that SGW influences the reaction dynamics.

The 4-dimensional Langevin approach to low energy nuclear fission

NASA Astrophysics Data System (ADS)

Ivanyuk, F. A.; Ishizuka, C.; Usang, M. D.; Chiba, S.

2018-03-01

We applied the four-dimensional Langevin approach to the description of fission of 235U by neutrons and calculated the dependence of the excitation energy of fission fragments on their mass number. For this we have fitted the compact just-before-scission configuration obtained by the Langevin calculations by the two separated fragments and calculated the intrinsic excitation and the deformation energy of each fragment accurately taking into account the shell and pairing effects and their dependence on the temperature and mass of the fragments. For the sharing of energy between the fission fragments we have used the simplest and most reliable assumption - the temperature of each fragment immediately after the neck rupture is the same as the temperature of mother nucleus just before scission. The calculated excitation energy of fission fragments clearly demonstrates the saw-tooth structure in the dependence on fragment mass number.

Model prediction for temperature dependence of meson pole masses from lattice QCD results on meson screening masses

NASA Astrophysics Data System (ADS)

Ishii, Masahiro; Kouno, Hiroaki; Yahiro, Masanobu

2017-06-01

We propose a practical effective model by introducing temperature (T ) dependence to the coupling strengths of four-quark and six-quark Kobayashi-Maskawa-'t Hooft interactions in the 2 +1 flavor Polyakov-loop extended Nambu-Jona-Lasinio model. The T dependence is determined from lattice QCD (LQCD) data on the renormalized chiral condensate around the pseudocritical temperature Tcχ of chiral crossover and the screening-mass difference between π and a0 mesons in T >1.1 Tcχ where only the U (1 )A-symmetry breaking survives. The model well reproduces LQCD data on screening masses Mξscr(T ) for both pseudoscalar mesons (ξ =π ,K ,η ,η' ) and scalar ones (ξ =a0,κ ,σ ,f0 ), particularly in T ≳Tcχ . Using this effective model, we predict meson pole masses Mξpole(T ) for scalar and pseudoscalar mesons. For η' meson, the prediction is consistent with the experimental value at finite T measured in heavy-ion collisions. We point out that the relation Mξscr(T )-Mξpole(T )≈Mξ' scr(T )-Mξ' pole(T ) is pretty good when ξ and ξ' are the scalar mesons, and show that the relation Mξscr(T )/Mξ' scr(T )≈Mξpole(T )/Mξ' pole(T ) is well satisfied within 20% error when ξ and ξ' are the pseudoscalar mesons and also when ξ and ξ' are the scalar mesons.

Mass dependence of HBT correlations in e+e- annihilation

NASA Astrophysics Data System (ADS)

Bialas, A.; Kucharczyk, M.; Palka, H.; Zalewski, K.

2000-12-01

The mass dependence of the effective source radii, observed in hadronic Z0 decays by several CERN LEP I experiments, is analyzed in a model which assumes proportionality between the four-momentum of a produced particle and the four-vector describing its space-time position at freeze-out. It is shown that this relation (commonly accepted in the description of high-energy collisions) can explain the data, provided all particles are emitted from a ``tube'' of ~1 fm in diameter at a constant proper time ~1.5 fm.

Anomalous frequency and temperature-dependent scattering and Hund's coupling in the almost quantum critical heavy-fermion system CeFe2Ge2

NASA Astrophysics Data System (ADS)

Bossé, G.; Pan, LiDong; Li, Yize S.; Greene, L. H.; Eckstein, J.; Armitage, N. P.

2016-02-01

We present THz range optical conductivity data of a thin film of the near quantum critical heavy-fermion compound CeFe2Ge2 . Our complex conductivity measurements find a deviation from conventional Drude-like transport in a temperature range previously reported to exhibit unconventional behavior. We calculate the frequency-dependent effective mass and scattering rate using an extended Drude model analysis. We find the inelastic scattering rate can be described by a temperature-dependent power law ωn (T ), where n (T ) approaches ˜1.0 ±0.2 at 1.5 K. This is compared to the ρ ˜T1.5 behavior claimed in dc resistivity data and the ρ ˜T2 expected from Fermi-liquid theory. In addition to a low-temperature mass renormalization, we find an anomalous mass renormalization that persists to high temperature. We attribute this to a Hund's coupling in the Fe states in a manner similar to that recently proposed in the ferropnictides. CeFe2Ge2 appears to be a very interesting system where one may study the interplay between the usual 4 f lattice Kondo effect and this Hund's enhanced Kondo effect in the 3 d states.

Size, History-Dependent, Activation and Three-Dimensional Effects on the Work and Power Produced During Cyclic Muscle Contractions.

PubMed

Ross, Stephanie A; Ryan, David S; Dominguez, Sebastian; Nigam, Nilima; Wakeling, James M

2018-05-03

Muscles undergo cycles of length change and force development during locomotion, and these contribute to their work and power production to drive body motion. Muscle fibres are typically considered to be linear actuators whose stress depends on their length, velocity, and activation state, and whose properties can be scaled up to explain the function of whole muscles. However, experimental and modelling studies have shown that a muscle's stress additionally depends on inactive and passive tissues within the muscle, the muscle's size, and its previous contraction history. These effects have not been tested under common sets of contraction conditions, especially the cyclic contractions that are typical of locomotion. Here we evaluate the relative effects of size, history-dependent, activation and three-dimensional effects on the work and power produced during cyclic contractions of muscle models. Simulations of muscle contraction were optimized to generate high power outputs: this resulted in the muscle models being largely active during shortening, and inactive during lengthening. As such, the history-dependent effects were dominated by force depression during simulated active shortening rather than force enhancement during active stretch. Internal work must be done to deform the muscle tissue, and to accelerate the internal muscle mass, resulting in reduced power and work that can be done on an external load. The effect of the muscle mass affects the scaling of muscle properties, with the inertial costs of contraction being relatively greater at larger sizes and lower activation levels.

Properties of JP=1/2+ baryon octets at low energy

NASA Astrophysics Data System (ADS)

Kaur, Amanpreet; Gupta, Pallavi; Upadhyay, Alka

2017-06-01

The statistical model in combination with the detailed balance principle is able to phenomenologically calculate and analyze spin- and flavor-dependent properties like magnetic moments (with effective masses, with effective charge, or with both effective mass and effective charge), quark spin polarization and distribution, the strangeness suppression factor, and \\overline{d}-\\overline{u} asymmetry incorporating the strange sea. The s\\overline{s} in the sea is said to be generated via the basic quark mechanism but suppressed by the strange quark mass factor ms>m_{u,d}. The magnetic moments of the octet baryons are analyzed within the statistical model, by putting emphasis on the SU(3) symmetry-breaking effects generated by the mass difference between the strange and non-strange quarks. The work presented here assumes hadrons with a sea having an admixture of quark gluon Fock states. The results obtained have been compared with theoretical models and experimental data.

Radiation-reaction force on a small charged body to second order

NASA Astrophysics Data System (ADS)

Moxon, Jordan; Flanagan, Éanna

2018-05-01

In classical electrodynamics, an accelerating charged body emits radiation and experiences a corresponding radiation-reaction force, or self-force. We extend to higher order in the total charge a previous rigorous derivation of the electromagnetic self-force in flat spacetime by Gralla, Harte, and Wald. The method introduced by Gralla, Harte, and Wald computes the self-force from the Maxwell field equations and conservation of stress-energy in a limit where the charge, size, and mass of the body go to zero, and it does not require regularization of a singular self-field. For our higher-order computation, an adjustment of the definition of the mass of the body is necessary to avoid including self-energy from the electromagnetic field sourced by the body in the distant past. We derive the evolution equations for the mass, spin, and center-of-mass position of the body through second order. We derive, for the first time, the second-order acceleration dependence of the evolution of the spin (self-torque), as well as a mixing between the extended body effects and the acceleration-dependent effects on the overall body motion.

The effect of polar caps on obliquity

NASA Technical Reports Server (NTRS)

Lindner, B. L.

1993-01-01

Rubincam has shown that the Martian obliquity is dependent on the seasonal polar caps. In particular, Rubincam analytically derived this dependence and showed that the change in obliquity is directly proportional to the seasonal polar cap mass. Rubincam concludes that seasonal friction does not appear to have changed Mars' climate significantly. Using a computer model for the evolution of the Martian atmosphere, Haberle et al. have made a convincing case for the possibility of huge polar caps, about 10 times the mass of the current polar caps, that exist for a significant fraction of the planet's history. Since Rubincam showed that the effect of seasonal friction on obliquity is directly proportional to polar cap mass, a scenario with a ten-fold increase in polar cap mass over a significant fraction of the planet's history would result in a secular increase in Mars' obliquity of perhaps 10 degrees. Hence, the Rubincam conclusion of an insignificant contribution to Mars' climate by seasonal friction may be incorrect. Furthermore, if seasonal friction is an important consideration in the obliquity of Mars, this would significantly alter the predictions of past obliquity.

Interacting effects of water temperature and swimming activity on body composition and mortality of fasted juvenile rainbow trout

USGS Publications Warehouse

Simpkins, D.G.; Hubert, W.A.; Martinez Del Rio, C.; Rule, D.C.

2003-01-01

Abstract: We assessed changes in proximate body composition, wet mass, and the occurrence of mortality among sedentary and actively swimming (15 cm/s) juvenile rainbow trout (Oncorhynchus mykiss) (120-142 mm total length) that were held at 4.0, 7.5, or 15.0 ??C and fasted for 140 days. Warmer water temperatures and swimming activity accentuated declines in lipid mass, but they did not similarly affect lean mass and wet mass. Swimming fish conserved lean mass independent of water temperature. Because lean mass exceeded lipid mass, wet mass was not affected substantially by decreases in lipid mass. Consequently, wet mass did not accurately reflect the effects that water temperature and swimming activity had on mortality of fasted rainbow trout. Rather, lipid mass was more accurate in predicting death from starvation. Juvenile rainbow trout survived long periods without food, and fish that died of starvation appeared to have similar body composition. It appears that the ability of fish to endure periods without food depends on the degree to which lipid mass and lean mass can be utilized as energy sources.

Meson spectroscopy, quark mixing and quantum chromodynamics

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

Filippov, A.T.

1979-04-01

A semiphenomenological theory of the quark-antiquark meson mass spectrum is presented. Relativistic kinematic effects due to unequal quark masses and SU (3) -breaking effects in the slopes of Regge trajectories and in radially excited states are taken into account. Violation of the OZI rule is accounted for by means of a mixing matrix for the quark wave functions, which is given by QCD. To describe the dependence of the mixing parameters on the meson masses, a simple extrapolation of the QCD expressions is proposed from the ''asymptotic-freedom'' region to the ''infrared-slavery'' region. To calculate the masses and mixing angles ofmore » the pseudoscalar mesons, the condition for a minimal pion mass is proposed. The eta-meson mass is then shown to be close to its maximum. The predictions of the theory for meson masses and mixing angles are in good agreement with experiment.« less

Effects of heavy sea quarks at low energies.

PubMed

Bruno, Mattia; Finkenrath, Jacob; Knechtli, Francesco; Leder, Björn; Sommer, Rainer

2015-03-13

We present a factorization formula for the dependence of light hadron masses and low energy hadronic scales on the mass M of a heavy quark: apart from an overall mass-independent factor Q, ratios such as r_{0}(M)/r_{0}(0) are computable in perturbation theory at large M. The perturbation theory part is stable concerning different loop orders. Our nonperturbative Monte Carlo results obtained in a model calculation, where a doublet of heavy quarks is decoupled, match quantitatively to the perturbative prediction. Upon taking ratios of different hadronic scales at the same mass, the perturbative function drops out and the ratios are given by the decoupled theory up to M^{-2} corrections. We verify-in the continuum limit-that the sea quark effects of quarks with masses around the charm mass are very small in such ratios.

Baryon Effective Theories and Phenomenology in the 1/N c Expansion

NASA Astrophysics Data System (ADS)

Fernando, Ishara Priyasad

Chiral perturbation theory (ChPT) and the 1/Nc expansion provide systematic frameworks to investigate the strong interaction at low energy. There are two main focuses of this dissertation. First, analyzing the masses of baryons in the framework of the 1/Nc expansion, using the available physical masses and masses calculated in lattice QCD. Second, combining both ChPT and the 1/Nc expansion into a single framework and applying it to the phenomenology of baryons with three light-quark flavors. In the first focus, the baryon states are organized into irreducible representa- tions of SU(6) x O(3), where the [56, ℓ P = 0+] contains the ground state and radially excited baryons, and the [56, 2+] and [70, 1 -] contain orbitally excited states are analyzed. The analyses are carried out to O(1/Nc) and first order in the quark masses. The issue of state identifications is discussed. Numerous parameter independent mass relations and the famous Gell-Mann-Okubo (GMO) and Equal-Spacing (ES) relations are tested. Also, the quark mass dependence of the operator coefficients for baryon mass is discussed. In the second focus, a small scale expansion of the combined approach is defined as the xi-expansion, in which the power counting of 1/Nc and chiral expansions are linked as O(p) = O(1/Nc) = O(xi). A calculation of one-loop corrections to the ground state baryon masses, vector and axial-vector currents up to O(xi 3) is presented. Moreover, the physical and lattice QCD masses are considered in order to understand the quark mass dependence, along with an analysis of the violations to GMO, ES and Gursey-Radicati (GR) mass relations, and their dependence on Nc.

The isospin strange asymmetry from the chiral effective theory

NASA Astrophysics Data System (ADS)

Trevisan, Luis Augusto; Mirez, Carlos

2018-05-01

The proposal of the present work is to study the difference between the strange quark-antiquark amount in the proton and neutron. For this purpose, the possible nucleon-hyperon-kaon fluctuations are analyzed with the effective chiral theory. The small difference of particle masses is shown to be in the origin of this isospin asymmetry. The dependence of the results on the mass cutoff parameter and with the coupling constants is analyzed.

Bulk viscosity of strongly interacting matter in the relaxation time approximation

DOE PAGES

Czajka, Alina; Hauksson, Sigtryggur; Shen, Chun; ...

2018-04-24

Here, we show how thermal mean field effects can be incorporated consistently in the hydrodynamical modeling of heavy-ion collisions. The nonequilibrium correction to the distribution function resulting from a temperature-dependent mass is obtained in a procedure which automatically satisfies the Landau matching condition and is thermodynamically consistent. The physics of the bulk viscosity is studied here for Boltzmann and Bose-Einstein gases within the Chapman-Enskog and 14-moment approaches in the relaxation time approximation. Constant and temperature-dependent masses are considered in turn. It is shown that, in the small mass limit, both methods lead to the same value of the ratio ofmore » the bulk viscosity to its relaxation time. The inclusion of a temperature-dependent mass leads to the emergence of the β λ function in that ratio, and it is of the expected parametric form for the Boltzmann gas, while for the Bose-Einstein case it is affected by the infrared cutoff. This suggests that the relaxation time approximation may be too crude to obtain a reliable form of ς/τ R for gases obeying Bose-Einstein statistics.« less

Bulk viscosity of strongly interacting matter in the relaxation time approximation

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

Czajka, Alina; Hauksson, Sigtryggur; Shen, Chun

Here, we show how thermal mean field effects can be incorporated consistently in the hydrodynamical modeling of heavy-ion collisions. The nonequilibrium correction to the distribution function resulting from a temperature-dependent mass is obtained in a procedure which automatically satisfies the Landau matching condition and is thermodynamically consistent. The physics of the bulk viscosity is studied here for Boltzmann and Bose-Einstein gases within the Chapman-Enskog and 14-moment approaches in the relaxation time approximation. Constant and temperature-dependent masses are considered in turn. It is shown that, in the small mass limit, both methods lead to the same value of the ratio ofmore » the bulk viscosity to its relaxation time. The inclusion of a temperature-dependent mass leads to the emergence of the β λ function in that ratio, and it is of the expected parametric form for the Boltzmann gas, while for the Bose-Einstein case it is affected by the infrared cutoff. This suggests that the relaxation time approximation may be too crude to obtain a reliable form of ς/τ R for gases obeying Bose-Einstein statistics.« less

Bulk viscosity of strongly interacting matter in the relaxation time approximation

NASA Astrophysics Data System (ADS)

Czajka, Alina; Hauksson, Sigtryggur; Shen, Chun; Jeon, Sangyong; Gale, Charles

2018-04-01

We show how thermal mean field effects can be incorporated consistently in the hydrodynamical modeling of heavy-ion collisions. The nonequilibrium correction to the distribution function resulting from a temperature-dependent mass is obtained in a procedure which automatically satisfies the Landau matching condition and is thermodynamically consistent. The physics of the bulk viscosity is studied here for Boltzmann and Bose-Einstein gases within the Chapman-Enskog and 14-moment approaches in the relaxation time approximation. Constant and temperature-dependent masses are considered in turn. It is shown that, in the small mass limit, both methods lead to the same value of the ratio of the bulk viscosity to its relaxation time. The inclusion of a temperature-dependent mass leads to the emergence of the βλ function in that ratio, and it is of the expected parametric form for the Boltzmann gas, while for the Bose-Einstein case it is affected by the infrared cutoff. This suggests that the relaxation time approximation may be too crude to obtain a reliable form of ζ /τR for gases obeying Bose-Einstein statistics.

Pion decay constant and the {rho}-meson mass at finite temperature in hidden local symmetry

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

Harada, M.; Shibata, A.

1997-06-01

We study the temperature dependence of the pion decay constant and {rho}-meson mass in the hidden local symmetry model at one loop. Using the standard imaginary time formalism, we include the thermal effect of the {rho} meson as well as that of the pion. We show that the pion gives a dominant contribution to the pion decay constant and the {rho}-meson contribution slightly decreases the critical temperature. The {rho}-meson pole mass increases as T{sup 4}/m{sub {rho}}{sup 2} at low temperature, dominated by the pion-loop effect. At high temperature, although the pion-loop effect decreases the {rho}-meson mass, the {rho}-loop contribution overcomesmore » the pion-loop contribution and the {rho}-meson mass increases with temperature. We also show that the conventional parameter a is stable as the temperature increases. {copyright} {ital 1997} {ital The American Physical Society}« less

A stable partitioned FSI algorithm for rigid bodies and incompressible flow. Part I: Model problem analysis

NASA Astrophysics Data System (ADS)

Banks, J. W.; Henshaw, W. D.; Schwendeman, D. W.; Tang, Qi

2017-08-01

A stable partitioned algorithm is developed for fluid-structure interaction (FSI) problems involving viscous incompressible flow and rigid bodies. This added-mass partitioned (AMP) algorithm remains stable, without sub-iterations, for light and even zero mass rigid bodies when added-mass and viscous added-damping effects are large. The scheme is based on a generalized Robin interface condition for the fluid pressure that includes terms involving the linear acceleration and angular acceleration of the rigid body. Added-mass effects are handled in the Robin condition by inclusion of a boundary integral term that depends on the pressure. Added-damping effects due to the viscous shear forces on the body are treated by inclusion of added-damping tensors that are derived through a linearization of the integrals defining the force and torque. Added-damping effects may be important at low Reynolds number, or, for example, in the case of a rotating cylinder or rotating sphere when the rotational moments of inertia are small. In this first part of a two-part series, the properties of the AMP scheme are motivated and evaluated through the development and analysis of some model problems. The analysis shows when and why the traditional partitioned scheme becomes unstable due to either added-mass or added-damping effects. The analysis also identifies the proper form of the added-damping which depends on the discrete time-step and the grid-spacing normal to the rigid body. The results of the analysis are confirmed with numerical simulations that also demonstrate a second-order accurate implementation of the AMP scheme.

Mapping the core mass function to the initial mass function

NASA Astrophysics Data System (ADS)

Guszejnov, Dávid; Hopkins, Philip F.

2015-07-01

It has been shown that fragmentation within self-gravitating, turbulent molecular clouds (`turbulent fragmentation') can naturally explain the observed properties of protostellar cores, including the core mass function (CMF). Here, we extend recently developed analytic models for turbulent fragmentation to follow the time-dependent hierarchical fragmentation of self-gravitating cores, until they reach effectively infinite density (and form stars). We show that turbulent fragmentation robustly predicts two key features of the initial mass function (IMF). First, a high-mass power-law scaling very close to the Salpeter slope, which is a generic consequence of the scale-free nature of turbulence and self-gravity. We predict the IMF slope (-2.3) is slightly steeper than the CMF slope (-2.1), owing to the slower collapse and easier fragmentation of large cores. Secondly, a turnover mass, which is set by a combination of the CMF turnover mass (a couple solar masses, determined by the `sonic scale' of galactic turbulence, and so weakly dependent on galaxy properties), and the equation of state (EOS). A `soft' EOS with polytropic index γ < 1.0 predicts that the IMF slope becomes `shallow' below the sonic scale, but fails to produce the full turnover observed. An EOS, which becomes `stiff' at sufficiently low surface densities Σgas ˜ 5000 M⊙ pc-2, and/or models, where each collapsing core is able to heat and effectively stiffen the EOS of a modest mass (˜0.02 M⊙) of surrounding gas, are able to reproduce the observed turnover. Such features are likely a consequence of more detailed chemistry and radiative feedback.

The P-factor and atomic mass systematics: Application to medium mass nuclei

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

Brenner, D.S.; Haustein, P.E.; Casten, R.F.

1988-01-01

The P formalism was applied to atomic mass systematics for medium and heavy nuclei. The P-factor linearizes the structure-dependent part of the nuclear mass in those regions which are free from subshell effects indicating that the attractive quadrupole p-n force plays an important role in determining the binding of valence nucleons. Where marked non-linearities occur, the P-factor provides a means for recognizing subshell closures and/or other structural features not embodied in the simple assumptions of abrupt shell or subshell changes. These are thought to be regions where the monopole part of the p-n interaction is highly orbit dependent and altersmore » the underlying single-particle structure as a function of A, N or Z. Finally, in those regions where the systematics are smooth and subshells are absent, the P-factor provides a means for predicting masses of some nuclei far-from-stability by interpolation rather than by extrapolation. 5 figs.« less

On the Formation of Massive Stars

NASA Technical Reports Server (NTRS)

Yorke, Harold W.; Sonnhalter, Cordula

2002-01-01

We calculate numerically the collapse of slowly rotating, nonmagnetic, massive molecular clumps of masses 30,60, and 120 Stellar Mass, which conceivably could lead to the formation of massive stars. Because radiative acceleration on dust grains plays a critical role in the clump's dynamical evolution, we have improved the module for continuum radiation transfer in an existing two-dimensional (axial symmetry assumed) radiation hydrodynamic code. In particular, rather than using "gray" dust opacities and "gray" radiation transfer, we calculate the dust's wavelength-dependent absorption and emission simultaneously with the radiation density at each wavelength and the equilibrium temperatures of three grain components: amorphous carbon particles. silicates, and " dirty ice " -coated silicates. Because our simulations cannot spatially resolve the innermost regions of the molecular clump, however, we cannot distinguish between the formation of a dense central cluster or a single massive object. Furthermore, we cannot exclude significant mass loss from the central object(s) that may interact with the inflow into the central grid cell. Thus, with our basic assumption that all material in the innermost grid cell accretes onto a single object. we are able to provide only an upper limit to the mass of stars that could possibly be formed. We introduce a semianalytical scheme for augmenting existing evolutionary tracks of pre-main-sequence protostars by including the effects of accretion. By considering an open outermost boundary, an arbitrary amount of material could, in principal, be accreted onto this central star. However, for the three cases considered (30, 60, and 120 Stellar Mass originally within the computation grid), radiation acceleration limited the final masses to 3 1.6, 33.6, and 42.9 Stellar Mass, respectively, for wavelength-dependent radiation transfer and to 19.1, 20.1, and 22.9 Stellar Mass. for the corresponding simulations with gray radiation transfer. Our calculations demonstrate that massive stars can in principle be formed via accretion through a disk. The accretion rate onto the central source increases rapidly after one initial free-fall time and decreases monotonically afterward. By enhancing the nonisotropic character of the radiation field, the accretion disk reduces the effects of radiative acceleration in the radial direction - a process we call the "flashlight effect." The flashlight effect is further amplified in our case by including the effects of frequency-dependent radiation transfer. We conclude with the warning that a careful treatment of radiation transfer is a mandatory requirement for realistic simulations of the formation of massive stars.

Thermophoretic torque in colloidal particles with mass asymmetry

NASA Astrophysics Data System (ADS)

Olarte-Plata, Juan; Rubi, J. Miguel; Bresme, Fernando

2018-05-01

We investigate the response of anisotropic colloids suspended in a fluid under a thermal field. Using nonequilibrium molecular dynamics computer simulations and nonequilibrium thermodynamics theory, we show that an anisotropic mass distribution inside the colloid rectifies the rotational Brownian motion and the colloids experience transient torques that orient the colloid along the direction of the thermal field. This physical effect gives rise to distinctive changes in the dependence of the Soret coefficient with colloid mass, which features a maximum, unlike the monotonic increase of the thermophoretic force with mass observed in homogeneous colloids.

Model Independent Determination of Electron Fraction for Individual SNIa

NASA Astrophysics Data System (ADS)

De, Soma; Timmes, F.; Hawley, W.; Chamulak, D.; Athanassiadou, T.; Jack, D.; Calder, A.; Brown, E.; Townsley, D.

2013-01-01

Ye of individual supernova Type Ia at the time of explosion by using the silicon, sulfur, and calcium features from single epoch and multi-epoch spectra near maximum light. Most one-dimensional Chandrasekhar mass models of supernova Type Ia in the single-degenerate scenario produce their intermediate-mass elements in a burn to quasi-nuclear statistical equilibrium between the mass shells 0.8 and 1.1 M. We find a near linear dependence of the intermediate-mass element nuclear yields on the white dwarf’s initial metallicity from such SNe Ia explosion models, and the effect this dependence has on synthetic spectra near maximum light. We demonstrate that these metallicity signatures are only due to material achieving the necessary thermodynamic conditions. In addition, we find that global abundance of silicon is insensitive to change in metallicity but sulfur and calcium abundances change significantly

Polar alignment of a protoplanetary disc around an eccentric binary II: Effect of binary and disc parameters

NASA Astrophysics Data System (ADS)

Martin, Rebecca G.; Lubow, Stephen H.

2018-06-01

In a recent paper Martin & Lubow showed that a circumbinary disc around an eccentric binary can undergo damped nodal oscillations that lead to the polar (perpendicular) alignment of the disc relative to the binary orbit. The disc angular momentum vector aligns to the eccentricity vector of the binary. We explore the robustness of this mechanism for a low mass disc (0.001 of the binary mass) and its dependence on system parameters by means of hydrodynamic disc simulations. We describe how the evolution depends upon the disc viscosity, temperature, size, binary mass ratio, orbital eccentricity and inclination. We compare results with predictions of linear theory. We show that polar alignment of a low mass disc may occur over a wide range of binary-disc parameters. We discuss the application of our results to the formation of planetary systems around eccentric binary stars.

THE IMPACT OF MASS SEGREGATION AND STAR FORMATION ON THE RATES OF GRAVITATIONAL-WAVE SOURCES FROM EXTREME MASS RATIO INSPIRALS

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

Aharon, Danor; Perets, Hagai B.

Compact stellar objects inspiraling into massive black holes (MBHs) in galactic nuclei are some of the most promising gravitational-wave (GWs) sources for next-generation GW detectors. The rates of such extreme mass ratio inspirals (EMRIs) depend on the dynamics and distribution of compact objects (COs) around the MBH. Here, we study the impact of mass-segregation processes on EMRI rates. In particular, we provide the expected mass function (MF) of EMRIs, given an initial MF of stellar black holes (SBHs), and relate it to the mass-dependent detection rate of EMRIs. We then consider the role of star formation (SF) on the distributionmore » of COs and its implication on EMRI rates. We find that the existence of a wide spectrum of SBH masses leads to the overall increase of EMRI rates and to high rates of the EMRIs from the most massive SBHs. However, it also leads to a relative quenching of EMRI rates from lower-mass SBHs, and together produces a steep dependence of the EMRI MF on the highest-mass SBHs. SF history plays a relatively small role in determining the EMRI rates of SBHs, since most of them migrate close to the MBH through mass segregation rather than forming in situ. However, the EMRI rate of neutron stars (NSs) can be significantly increased when they form in situ close to the MBH, as they can inspiral before relaxation processes significantly segregate them outward. A reverse but weaker effect of decreasing the EMRI rates from NSs and white dwarfs occurs when SF proceeds far from the MBH.« less

The realistic models of relativistic stars in f (R) = R + αR 2 gravity

NASA Astrophysics Data System (ADS)

Astashenok, Artyom V.; Odintsov, Sergei D.; de la Cruz-Dombriz, Álvaro

2017-10-01

In the context of f(R)=R+α R2 gravity, we study the existence of neutron and quark stars for various α with no intermediate approximation in the system of equations. Analysis shows that for positive α the scalar curvature does not drop to zero at the star surface (as in general relativity) but exponentially decreases with distance. Also the stellar mass bounded by star surface decreases when the value α increases. Nonetheless distant observers would observe a gravitational mass due to appearance of a so-called gravitational sphere around the star. The non-zero curvature contribution to the gravitational mass eventually is shown to compensate the stellar mass decrease for growing α’s. We perform our analysis for several equations of state including purely hadronic configurations as well as hyperons and quark stars. In all cases, we assess that the relation between the parameter α and the gravitational mass weakly depends upon the chosen equation of state. Another interesting feature is the increase of the star radius in comparison with general relativity for stars with masses close to maximal, whereas for intermediate masses 1.4 -1.6 M_⊙ the radius of star depends upon α very weakly. Also the decrease in the mass bounded by star surface may cause the surface redshift to decrease in R 2-gravity when compared to Einsteinian predictions. This effect is shown to hardly depend upon the observed gravitational mass. Finally, for negative values of α our analysis shows that outside the star the scalar curvature has damped oscillations but the contribution of the gravitational sphere into the gravitational mass increases indefinitely with radial distance putting into question the very existence of such relativistic stars.

Reggi-Leduc and Maggi-Reggi-Leduc effects in conducting films with an anisotropic dispersion law

NASA Astrophysics Data System (ADS)

Askerov, B. M.; Guseinov, G. I.; Kuliev, B. I.; Figarova, S. R.

1989-06-01

The influence of the spectrum and bulk scattering anisotropies on the Reggi-Leduc and Maggi-Reggi-Leduc effects is investigated in semiconducting films of the electronic silicon type under classical dimensional effect conditions. It is shown that in contrast to a massive specimen these effects depend not only on a single parameter, the ratio between the anisotropy coefficients of the effective mass and the relaxation time but also on each of them separately, which permit their direct determination. It is also established that the Reggi-Leduc coefficient depends differently on the film thickness, depending on the relationship between the electron and phonon parts of the crystal heat conductivity.

A propulsion-mass tensor coupling in relativistic rocket motion

NASA Astrophysics Data System (ADS)

Brito, Hector Hugo

1998-01-01

Following earlier speculations about antigravity machines and works on the relativistic dynamics of constant and variable rest mass point particles, a mass tensor is found in connection with the closed system consisting of the rocket driven spaceship and its propellant mass, provided a ``solidification'' point other than the system center of mass is considered. Therefore, the mass tensor form depends on whether the system is open or closed, and upon where the ``solidification'' point is located. An alternative propulsion principle is subsequently derived from the tensor mass approach. The new principle, the covariant equivalent of Newton's Third Law for the physical interpretation of the relativistic rocket motion, reads: A spaceship undergoes a propulsion effect when the whole system mass 4-ellipsoid warps.

Mass effects and internal space geometry in triatomic reaction dynamics

NASA Astrophysics Data System (ADS)

Yanao, Tomohiro; Koon, Wang S.; Marsden, Jerrold E.

2006-05-01

The effect of the distribution of mass in triatomic reaction dynamics is analyzed using the geometry of the associated internal space. Atomic masses are appropriately incorporated into internal coordinates as well as the associated non-Euclidean internal space metric tensor after a separation of the rotational degrees of freedom. Because of the non-Euclidean nature of the metric in the internal space, terms such as connection coefficients arise in the internal equations of motion, which act as velocity-dependent forces in a coordinate chart. By statistically averaging these terms, an effective force field is deduced, which accounts for the statistical tendency of geodesics in the internal space. This force field is shown to play a crucial role in determining mass-related branching ratios of isomerization and dissociation dynamics of a triatomic molecule. The methodology presented can be useful for qualitatively predicting branching ratios in general triatomic reactions, and may be applied to the study of isotope effects.

Effective mass and Fermi surface complexity factor from ab initio band structure calculations

NASA Astrophysics Data System (ADS)

Gibbs, Zachary M.; Ricci, Francesco; Li, Guodong; Zhu, Hong; Persson, Kristin; Ceder, Gerbrand; Hautier, Geoffroy; Jain, Anubhav; Snyder, G. Jeffrey

2017-02-01

The effective mass is a convenient descriptor of the electronic band structure used to characterize the density of states and electron transport based on a free electron model. While effective mass is an excellent first-order descriptor in real systems, the exact value can have several definitions, each of which describe a different aspect of electron transport. Here we use Boltzmann transport calculations applied to ab initio band structures to extract a density-of-states effective mass from the Seebeck Coefficient and an inertial mass from the electrical conductivity to characterize the band structure irrespective of the exact scattering mechanism. We identify a Fermi Surface Complexity Factor: Nv*K* from the ratio of these two masses, which in simple cases depends on the number of Fermi surface pockets (Nv* ) and their anisotropy K*, both of which are beneficial to high thermoelectric performance as exemplified by the high values found in PbTe. The Fermi Surface Complexity factor can be used in high-throughput search of promising thermoelectric materials.

Strong Field Quenching of the Quasiparticle Effective Mass in Heavy Fermion Compound YbCo2Zn20

NASA Astrophysics Data System (ADS)

Masahiro Ohya,; Masaki Matsushita,; Shingo Yoshiuchi,; Tetsuya Takeuchi,; Fuminori Honda,; Rikio Settai,; Toshiki Tanaka,; Yasunori Kubo,; Yoshichika Ōnuki,

2010-08-01

We found a metamagnetic like anomaly at Hm≃ 5 kOe in a heavy fermion compound YbCo2Zn20 below the characteristic temperature Tχ_{max}=0.32 K where the ac-susceptibility shows a broad peak, suggesting that an electronic state with a very low Kondo temperature is realized. Interestingly, the metamagnetic like behavior was observed as two peaks at 4.0 and 7.5 kOe at 95 mK in the magnetic field dependence of the electronic specific heat C/T. The extremely large values of the electronic specific heat coefficient γ≃ 8000 mJ/(K2\\cdotmol) and A=160 μΩ\\cdotcm/K2 in the electrical resistivity ρ=ρ0+AT2 at H=0 kOe are most likely due to the very low Kondo temperature. The \\sqrt{A} value was, however, found to be strongly reduced from \\sqrt{A}=12.6 (μΩ\\cdotcm/K2)1/2 at 0 kOe to 0.145 (μΩ\\cdotcm/K2)1/2 at 150 kOe. Therefore, we considered that the corresponding cyclotron effective mass mc*, which was determined from the temperature dependence of the de Haas-van Alphen (dHvA) amplitude, is also reduced with increasing magnetic field and is in fact not large, ranging from 2 to 9m0 at 117 kOe. From the field dependence of \\sqrt{A} and mc*, we estimated the cyclotron effective mass at 0 kOe to be 100--500m0, revealing the largest cyclotron mass as far as we know.

The Interplay Between Fat Mass and Fat Distribution as Determinants of the Metabolic Syndrome Is Sex-Dependent.

PubMed

Lind, Lars; Ärnlöv, Johan; Lampa, Erik

2017-09-01

Fat mass and fat distribution are major determinants of the metabolic syndrome (MetS), but the interplay between them has not been thoroughly investigated. In addition, fat mass and fat distribution are generally different in men than in women. We aimed to determine whether the interplay between fat mass and fat distribution regarding MetS and its components is sex-dependent using data from the large-scale population-based sample EpiHealth. Occurrence of MetS and its components was determined together with fat mass by bioimpedance in 19,094 participants in the EpiHealth sample [mean age 61 years (SD 8.5), 56% females]. MetS was defined by the NCEP/ATPIII-criteria. MetS prevalence was 23.0%. Fat mass (percent of body weight) was more strongly related to MetS (and the number of MetS components) in men than in women (P < 0.0001 for interaction term) and in those with a high compared with those with a low waist/hip ratio (WHR). This modulating effect of WHR on the fat mass versus MetS-relationship was more pronounced in women than in men (P < 0.0001 for interaction term). When analyzing the MetS components one by one, fat mass was more closely related to all the individual MetS criteria in men than in women, except for the glucose criteria. Fat mass is more closely related to prevalent MetS in men than in women, but the modulating effect of an abdominal type of fat distribution on the fat mass versus MetS-relationship is stronger in women.

Effects of nonequilibrated topological charge distributions on pseudoscalar meson masses and decay constants

NASA Astrophysics Data System (ADS)

Bernard, C.; Toussaint, D.

2018-04-01

We study the effects of failure to equilibrate the squared topological charge Q2 on lattice calculations of pseudoscalar masses and decay constants. The analysis is based on chiral perturbation theory calculations of the dependence of these quantities on the QCD vacuum angle θ . For the light-light partially quenched case, we rederive the known chiral perturbation theory results of Aoki and Fukaya, but using the nonperturbatively valid chiral theory worked out by Golterman, Sharpe and Singleton, and by Sharpe and Shoresh. We then extend these calculations to heavy-light mesons. Results when staggered taste violations are important are also presented. The derived Q2 dependence is compared to that of simulations using the MILC Collaboration's ensembles of lattices with four flavors of dynamical highly improved staggered quarks. We find agreement, albeit with large statistical errors. These results can be used to correct for the leading effects of unequilibrated Q2, or to make estimates of the systematic error coming from the failure to equilibrate Q2. In an appendix, we show that the partially quenched chiral theory may be extended beyond a lower bound on valence masses discovered by Sharpe and Shoresh. Subtleties occurring when a sea-quark mass vanishes are discussed in another appendix.

Effect of Mass Proportion of Municipal Solid Waste Incinerator Bottom Ash Layer to Municipal Solid Waste Layer on the Cu and Zn Discharge from Landfill

PubMed Central

Kong, Qingna; Qiu, Zhanhong; Shen, Dongsheng

2016-01-01

Municipal solid waste incinerator (MSWI) bottom ash is often used as the protection layer for the geomembrane and intermediate layer in the landfill. In this study, three sets of simulated landfills with different mass proportion of MSWI bottom ash layer to municipal solid waste (MSW) layer were operated. Cu and Zn concentrations in the leachates and MSW were monitored to investigate the effect of MSWI bottom ash layer on the Cu and Zn discharge from the landfill. The results showed that the Zn discharge was dependent on the mass proportion of MSWI bottom ash layer. The pH of landfill was not notably increased when the mass proportion of MSWI bottom ash layer to MSW layer was 1 : 9, resulting in the enhancement of the Zn discharge. However, Zn discharge was mitigated when the mass proportion was 2 : 8, as the pH of landfill was notably promoted. The discharge of Cu was not dependent on the mass proportion, due to the great affinity of Cu to organic matter. Moreover, Cu and Zn contents of the sub-MSW layer increased due to the MSWI bottom ash layer. Therefore, the MSWI bottom ash layer can increase the potential environmental threat of the landfill. PMID:28044139

From the Cover: Adipose tissue mass can be regulated through the vasculature

NASA Astrophysics Data System (ADS)

Rupnick, Maria A.; Panigrahy, Dipak; Zhang, Chen-Yu; Dallabrida, Susan M.; Lowell, Bradford B.; Langer, Robert; Judah Folkman, M.

2002-08-01

Tumor growth is angiogenesis dependent. We hypothesized that nonneoplastic tissue growth also depends on neovascularization. We chose adipose tissue as an experimental system because of its remodeling capacity. Mice from different obesity models received anti-angiogenic agents. Treatment resulted in dose-dependent, reversible weight reduction and adipose tissue loss. Marked vascular remodeling was evident in adipose tissue sections, which revealed decreased endothelial proliferation and increased apoptosis in treated mice compared with controls. Continuous treatment maintained mice near normal body weights for age without adverse effects. Metabolic adaptations in food intake, metabolic rate, and energy substrate utilization were associated with anti-angiogenic weight loss. We conclude that adipose tissue mass is sensitive to angiogenesis inhibitors and can be regulated by its vasculature.

Full mass dependence in Higgs boson production in association with jets at the LHC and FCC

DOE PAGES

Greiner, Nicolas; Höche, Stefan; Luisoni, Gionata; ...

2017-01-23

The first computation of Higgs production in association with three jets at NLO in QCD has recently been performed using the effective theory, where the top quark is treated as an infinitely heavy particle and integrated out. This approach is restricted to the regions in phase space where the typical scales are not larger than the top quark mass. Here we investigate this statement at a quantitative level by calculating the leading-order contributions to the production of a Standard Model Higgs boson in association with up to three jets taking full top-quark and bottom-quark mass dependence into account. We findmore » that the transverse momentum of the hardest particle or jet plays a key role in the breakdown of the effective theory predictions, and that discrepancies can easily reach an order of magnitude for transverse momenta of about 1 TeV. The impact of bottom-quark loops is found to be visible in the small transverse momentum region, leading to corrections of up to 5 percent. Lastly, we further study the impact of mass corrections when VBF selection cuts are applied and when the center-of-mass energy is increased to 100 TeV.« less

Rapid profiling of polymeric phenolic acids in Salvia miltiorrhiza by hybrid data-dependent/targeted multistage mass spectrometry acquisition based on expected compounds prediction and fragment ion searching.

PubMed

Shen, Yao; Feng, Zijin; Yang, Min; Zhou, Zhe; Han, Sumei; Hou, Jinjun; Li, Zhenwei; Wu, Wanying; Guo, De-An

2018-04-01

Phenolic acids are the major water-soluble components in Salvia miltiorrhiza (>5%). According to previous studies, many of them contribute to the cardiovascular effects and antioxidant effects of S. miltiorrhiza. Polymeric phenolic acids can be considered as the tanshinol derived metabolites, e.g., dimmers, trimers, and tetramers. A strategy combined with tanshinol-based expected compounds prediction, total ion chromatogram filtering, fragment ion searching, and parent list-based multistage mass spectrometry acquisition by linear trap quadropole-orbitrap Velos mass spectrometry was proposed to rapid profile polymeric phenolic acids in S. miltiorrhiza. More than 480 potential polymeric phenolic acids could be screened out by this strategy. Based on the fragment information obtained by parent list-activated data dependent multistage mass spectrometry acquisition, 190 polymeric phenolic acids were characterized by comparing their mass information with literature data, and 18 of them were firstly detected from S. miltiorrhiza. Seven potential compounds were tentatively characterized as new polymeric phenolic acids from S. miltiorrhiza. This strategy facilitates identification of polymeric phenolic acids in complex matrix with both selectivity and sensitivity, which could be expanded for rapid discovery and identification of compounds from complex matrix. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Symmetry energy in cold dense matter

NASA Astrophysics Data System (ADS)

Jeong, Kie Sang; Lee, Su Houng

2016-01-01

We calculate the symmetry energy in cold dense matter both in the normal quark phase and in the 2-color superconductor (2SC) phase. For the normal phase, the thermodynamic potential is calculated by using hard dense loop (HDL) resummation to leading order, where the dominant contribution comes from the longitudinal gluon rest mass. The effect of gluonic interaction on the symmetry energy, obtained from the thermodynamic potential, was found to be small. In the 2SC phase, the non-perturbative BCS paring gives enhanced symmetry energy as the gapped states are forced to be in the common Fermi sea reducing the number of available quarks that can contribute to the asymmetry. We used high density effective field theory to estimate the contribution of gluon interaction to the symmetry energy. Among the gluon rest masses in 2SC phase, only the Meissner mass has iso-spin dependence although the magnitude is much smaller than the Debye mass. As the iso-spin dependence of gluon rest masses is even smaller than the case in the normal phase, we expect that the contribution of gluonic interaction to the symmetry energy in the 2SC phase will be minimal. The different value of symmetry energy in each phase will lead to different prediction for the particle yields in heavy ion collision experiment.

Dust formation at low metallicity

NASA Astrophysics Data System (ADS)

Ferrarotti, A. S.; Gail, H.-P.

Stars between 3Modot and 25Modot reach their final stages of stellar evolution either as AGB (asymptotic giant branch) stars and finally become white dwarfs, or end in a supernova explosion. The last evolutionary stages, shortly before the final state, are regularly accompanied by stellar winds which lead to substantial mass loss and develop optically very thick dust shells. Mass loss for smaller and medium sized stars higher up on the AGB depends predominantly on the metallicity of the star. For Pop I metallicity, the mass loss is caused by dust condensation. This process is not possible for stars of small Z. Thus, their final evolution strongly depends on the possibility of dust formation. Our research focuses on the dependence of dust formation of the first stellar generation on Z and on the initial mass of the star. Furthermore, we investigate when dust formation becomes possible in stellar winds and the effects this process has on the evolution of the star at the final evolutionary stages. With synthetic AGB evolution models some important issues in stellar evolution can tried to be answered: (1) mass loss on the AGB, (2) the shift of the limit (γ>1) for the onset of dust driven winds with Z and (3) the critical Z when dust formation becomes possible.

On the scatter in the relation between stellar mass and halo mass: random or halo formation time dependent?

NASA Astrophysics Data System (ADS)

Wang, Lan; De Lucia, Gabriella; Weinmann, Simone M.

2013-05-01

The empirical traditional halo occupation distribution (HOD) model of Wang et al. fits, by construction, both the stellar mass function and correlation function of galaxies in the local Universe. In contrast, the semi-analytical models of De Lucia & Blazoit (hereafter DLB07) and Guo et al. (hereafter Guo11), built on the same dark matter halo merger trees than the empirical model, still have difficulties in reproducing these observational data simultaneously. We compare the relations between the stellar mass of galaxies and their host halo mass in the three models, and find that they are different. When the relations are rescaled to have the same median values and the same scatter as in Wang et al., the rescaled DLB07 model can fit both the measured galaxy stellar mass function and the correlation function measured in different galaxy stellar mass bins. In contrast, the rescaled Guo11 model still overpredicts the clustering of low-mass galaxies. This indicates that the detail of how galaxies populate the scatter in the stellar mass-halo mass relation does play an important role in determining the correlation functions of galaxies. While the stellar mass of galaxies in the Wang et al. model depends only on halo mass and is randomly distributed within the scatter, galaxy stellar mass depends also on the halo formation time in semi-analytical models. At fixed value of infall mass, galaxies that lie above the median stellar mass-halo mass relation reside in haloes that formed earlier, while galaxies that lie below the median relation reside in haloes that formed later. This effect is much stronger in Guo11 than in DLB07, which explains the overclustering of low mass galaxies in Guo11. Assembly bias in Guo11 model might be overly strong. Nevertheless, in case that a significant assembly bias indeed exists in the real Universe, one needs to use caution when applying current HOD and abundance matching models that employ the assumption of random scatter in the relation between stellar and halo mass.

Ultra-high-precision Nd-isotope measurements of geological materials by MC-ICPMS

PubMed Central

Saji, Nikitha Susan; Wielandt, Daniel; Paton, Chad; Bizzarro, Martin

2016-01-01

We report novel techniques allowing the measurement of Nd-isotope ratios with unprecedented accuracy and precision by multi-collector inductively coupled plasma mass spectrometry. Using the new protocol, we have measured the Nd-isotopic composition of rock and synthetic Nd standards as well as that of the Allende carbonaceous chondrite. Analyses of BCR-2, BHVO-2 and GSP-2 rock standards yield mass-independent compositions identical to the JNdi-1 Nd-reference standard, with an external reproducibility of 2.4, 1.6, 1.6 and 3.5 ppm respectively, on μ142Nd, μ145Nd, μ146Nd and μ150Nd (μ representing the ppm-deviation of the ratios from JNdi-1) using 148Nd/144Nd for internal normalization. This represents an improvement in precision by a factor of 2, 7 and 9 respectively for μ142Nd, μ145Nd and μ150Nd. Near-quantitative recovery from purification chemistry and sample-standard bracketing allow for the determination of mass-dependent Nd-isotopic composition of samples. Synthetic standards, namely La Jolla and AMES, record mass-dependent variability of up to 1.2 ε per atomic mass unit and mass-independent compositions resolvable by up to 3 ppm for μ142Nd and 8 ppm for μ150Nd, relative to JNdi-1. The mass-independent compositions are consistent with equilibrium mass fractionation during purification. The terrestrial rock standards define a uniform stable ε145Nd of −0.24 ± 0.19 (2SD) relative to JNdi-1, indistinguishable from the mean Allende ε145Nd of −0.19 ± 0.09. We consider this value to represent the mass-dependent Nd-isotope composition of Bulk Silicate Earth (BSE). The modest mass-dependent fractionation of JNdi-1 relative to BSE results in potential effects on mass-independent composition that cannot be resolved within the reproducibility of our analyses when correcting for natural and instrumental mass fractionation by kinetic law, making it a suitable reference standard for analysis of unknowns. Analysis of Allende (CV3) carbonaceous chondrite returns an average μ142Nd deficit of −30.1 ± 3.7 ppm in agreement with previous studies. The apparent deficit is, however, lowered to −23.8 ± 4.0 ppm while normalizing to 148Nd/144Nd instead of 146Nd/144Nd. We interpret this as the effect of a possible nucleosynthetic anomaly of −6.3 ± 0.5 ppm in μ146Nd. As 142Nd and 146Nd are both s-process-dominated nuclides, this hints at the possibility that terrestrial μ142Nd excess may not reflect 146Sm decay as widely accepted. PMID:27429505

Rehearsal strategies can enlarge or diminish the spacing effect: pure versus mixed lists and encoding strategy.

PubMed

Delaney, Peter F; Verkoeijen, Peter P J L

2009-09-01

Using 5 experiments, the authors explored the dependency of spacing effects on rehearsal patterns. Encouraging rehearsal borrowing produced opposing effects on mixed lists (containing both spaced and massed repetitions) and pure lists (containing only one or the other), magnifying spacing effects on mixed lists but diminishing spacing effects on pure lists. Rehearsing with borrowing produced large spacing effects on mixed lists but not on pure lists for both free recall (Experiment 1) and recognition (Experiment 2). In contrast, rehearsing only the currently visible item produced spacing effects on both mixed lists and pure lists in free recall (Experiment 3) and recognition (Experiment 4). Experiment 5 demonstrated these effects using a fully within-subjects design. Rehearse-aloud protocols showed that rehearsal borrowing redistributed study from massed to spaced items on mixed lists, especially during massed presentations. (c) 2009 APA, all rights reserved.

Large-scale assembly bias of dark matter halos

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

Lazeyras, Titouan; Musso, Marcello; Schmidt, Fabian, E-mail: titouan@mpa-garching.mpg.de, E-mail: mmusso@sas.upenn.edu, E-mail: fabians@mpa-garching.mpg.de

We present precise measurements of the assembly bias of dark matter halos, i.e. the dependence of halo bias on other properties than the mass, using curved 'separate universe' N-body simulations which effectively incorporate an infinite-wavelength matter overdensity into the background density. This method measures the LIMD (local-in-matter-density) bias parameters b {sub n} in the large-scale limit. We focus on the dependence of the first two Eulerian biases b {sup E} {sup {sub 1}} and b {sup E} {sup {sub 2}} on four halo properties: the concentration, spin, mass accretion rate, and ellipticity. We quantitatively compare our results with previous worksmore » in which assembly bias was measured on fairly small scales. Despite this difference, our findings are in good agreement with previous results. We also look at the joint dependence of bias on two halo properties in addition to the mass. Finally, using the excursion set peaks model, we attempt to shed new insights on how assembly bias arises in this analytical model.« less

The effects of temperature, hydrostatic pressure and size on optical gain for GaAs spherical quantum dot laser with hydrogen impurity

NASA Astrophysics Data System (ADS)

Owji, Erfan; Keshavarz, Alireza; Mokhtari, Hosein

2016-10-01

In this paper, the effects of temperature, hydrostatic pressure and size on optical gain for GaAs spherical quantum dot laser with hydrogen impurity are investigated. For this purpose, the effects of temperature, pressure and quantum dot size on the band gap energy, effective mass, and dielectric constant are studied. The eigenenergies and eigenstates for valence and conduction band are calculated by using Runge-Kutta numerical method. Results show that changes in the temperature, pressure and size lead to the alteration of the band gap energy and effective mass. Also, increasing the temperature redshifts the optical gain peak and at special temperature ranges lead to increasing or decreasing of it. Further, by reducing the size, temperature-dependent of optical gain is decreased. Additionally, enhancing of the hydrostatic pressure blueshifts the peak of optical gain, and its behavior as a function of pressure which depends on the size. Finally, increasing the radius rises the redshifts of the peak of optical gain.

Isospin effects on the system mass dependence of nuclear stopping around the energy of vanishing flow

NASA Astrophysics Data System (ADS)

Jain, Anupriya; Kumar, Suneel

2014-10-01

We study the effect of isospin degree of freedom on nuclear stopping throughout the mass range 50 and 350 for two sets of isotopic systems with N/Z ≈ 1.5 and 1.8, as well as isobaric systems with N/Z = 1.0 and 1.4. Analysis is carried out at incident energies below, at, and above the energy of vanishing flow (EVF) using the isospin-dependent quantum molecular dynamics model. Our findings reveal that nuclear stopping does not show any particular behavior at the EVF. Moreover, system size effects dominate the isospin effects throughout the range of colliding geometry. The Coulomb effects, however, become important at peripheral geometry. The comparative study of the counterbalancing of Coulomb and mean field by removing the nucleon-nucleon collisions and symmetry potential clearly indicates the dominance of nucleon-nucleon cross-section over the Coulomb repulsions. Moreover, the theoretical results presented in this manuscript for the set of reactions can be experimentally verified.

Connecting massive galaxies to dark matter haloes in BOSS - I. Is galaxy colour a stochastic process in high-mass haloes?

NASA Astrophysics Data System (ADS)

Saito, Shun; Leauthaud, Alexie; Hearin, Andrew P.; Bundy, Kevin; Zentner, Andrew R.; Behroozi, Peter S.; Reid, Beth A.; Sinha, Manodeep; Coupon, Jean; Tinker, Jeremy L.; White, Martin; Schneider, Donald P.

2016-08-01

We use subhalo abundance matching (SHAM) to model the stellar mass function (SMF) and clustering of the Baryon Oscillation Spectroscopic Survey (BOSS) `CMASS' sample at z ˜ 0.5. We introduce a novel method which accounts for the stellar mass incompleteness of CMASS as a function of redshift, and produce CMASS mock catalogues which include selection effects, reproduce the overall SMF, the projected two-point correlation function wp, the CMASS dn/dz, and are made publicly available. We study the effects of assembly bias above collapse mass in the context of `age matching' and show that these effects are markedly different compared to the ones explored by Hearin et al. at lower stellar masses. We construct two models, one in which galaxy colour is stochastic (`AbM' model) as well as a model which contains assembly bias effects (`AgM' model). By confronting the redshift dependent clustering of CMASS with the predictions from our model, we argue that that galaxy colours are not a stochastic process in high-mass haloes. Our results suggest that the colours of galaxies in high-mass haloes are determined by other halo properties besides halo peak velocity and that assembly bias effects play an important role in determining the clustering properties of this sample.

Elucidating mechanisms for insect body size: partial support for the oxygen-dependent induction of moulting hypothesis.

PubMed

Kivelä, Sami M; Viinamäki, Sonja; Keret, Netta; Gotthard, Karl; Hohtola, Esa; Välimäki, Panu

2018-01-25

Body size is a key life history trait, and knowledge of its mechanistic basis is crucial in life history biology. Such knowledge is accumulating for holometabolous insects, whose growth is characterised and body size affected by moulting. According to the oxygen-dependent induction of moulting (ODIM) hypothesis, moult is induced at a critical mass at which oxygen demand of growing tissues overrides the supply from the tracheal respiratory system, which principally grows only at moults. Support for the ODIM hypothesis is controversial, partly because of a lack of proper data to explicitly test the hypothesis. The ODIM hypothesis predicts that the critical mass is positively correlated with oxygen partial pressure ( P O 2 ) and negatively with temperature. To resolve the controversy that surrounds the ODIM hypothesis, we rigorously test these predictions by exposing penultimate-instar Orthosia gothica (Lepidoptera: Noctuidae) larvae to temperature and moderate P O 2  manipulations in a factorial experiment. The relative mass increment in the focal instar increased along with increasing P O 2 , as predicted, but there was only weak suggestive evidence of the temperature effect. Probably owing to a high measurement error in the trait, the effect of P O 2  on the critical mass was sex specific; high P O 2  had a positive effect only in females, whereas low P O 2  had a negative effect only in males. Critical mass was independent of temperature. Support for the ODIM hypothesis is partial because of only suggestive evidence of a temperature effect on moulting, but the role of oxygen in moult induction seems unambiguous. The ODIM mechanism thus seems worth considering in body size analyses. © 2018. Published by The Company of Biologists Ltd.

Group quenching and galactic conformity at low redshift

NASA Astrophysics Data System (ADS)

Treyer, M.; Kraljic, K.; Arnouts, S.; de la Torre, S.; Pichon, C.; Dubois, Y.; Vibert, D.; Milliard, B.; Laigle, C.; Seibert, M.; Brown, M. J. I.; Grootes, M. W.; Wright, A. H.; Liske, J.; Lara-Lopez, M. A.; Bland-Hawthorn, J.

2018-06-01

We quantify the quenching impact of the group environment using the spectroscopic survey Galaxy and Mass Assembly to z ˜ 0.2. The fraction of red (quiescent) galaxies, whether in groups or isolated, increases with both stellar mass and large-scale (5 Mpc) density. At fixed stellar mass, the red fraction is on average higher for satellites of red centrals than of blue (star-forming) centrals, a galactic conformity effect that increases with density. Most of the signal originates from groups that have the highest stellar mass, reside in the densest environments, and have massive, red only centrals. Assuming a colour-dependent halo-to-stellar-mass ratio, whereby red central galaxies inhabit significantly more massive haloes than blue ones of the same stellar mass, two regimes emerge more distinctly: at log (Mhalo/M⊙) ≲ 13, central quenching is still ongoing, conformity is no longer existent, and satellites and group centrals exhibit the same quenching excess over field galaxies at all mass and density, in agreement with the concept of `group quenching'; at log (Mh/M⊙) ≳ 13, a cut-off that sets apart massive (log (M⋆/M⊙) > 11), fully quenched group centrals, conformity is meaningless, and satellites undergo significantly more quenching than their counterparts in smaller haloes. The latter effect strongly increases with density, giving rise to the density-dependent conformity signal when both regimes are mixed. The star formation of blue satellites in massive haloes is also suppressed compared to blue field galaxies, while blue group centrals and the majority of blue satellites, which reside in low-mass haloes, show no deviation from the colour-stellar mass relation of blue field galaxies.

Timing of Bag Application and Removal in Controlled Mass Pollination

Treesearch

F.E. Bridgwater; D.L. Bramlett; V.D. Hipkins

1999-01-01

Controlled mass pollination (CMP) among outstanding parents is one way to increase genetic gains from traditional wind-pollinated seed orchards, but the economic success of CMP depends on both genetic gains and costs. CMP has been shown. to be cost-effective (Bridgwater et al. 1998) even when costs were adjusted for risk (Byram and Bridgwater 1999, These Proceedings...

The He I 2.06 microns/Br-gamma ratio in starburst galaxies - An objective constraint on the upper mass limit to the initial mass function

NASA Technical Reports Server (NTRS)

Doyon, Rene; Puxley, P. J.; Joseph, R. D.

1992-01-01

The use of the He I 2.06 microns/Br-gamma ratio as a constraint on the massive stellar population in star-forming galaxies is developed. A theoretical relationship between the He I 2.06 microns/Br-gamma ratio and the effective temperature of the exciting star in H II regions is derived. The effects of collisional excitation and dust within the nebula on the ratio are also considered. It is shown that the He I 2.06 microns/Br-gamma ratio is a steep function of the effective temperature, a property which can be used to determine the upper mass limit of the initial mass function (IMF) in galaxies. This technique is reliable for upper mass limits less than about 40 solar masses. New near-infrared spectra of starburst galaxies are presented. The He I 2.06 microns/Br-gamma ratios observed imply a range of upper mass limits from 27 to over 40 solar masses. There is also evidence that the upper mass limit is spatially dependent within a given galaxy. These results suggest that the upper mass limit is not a uniquely defined parameter of the IMF and probably varies with local physical conditions.

Mass-loss evolution of close-in exoplanets: Evaporation of hot Jupiters and the effect on population

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

Kurokawa, H.; Nakamoto, T., E-mail: kurokawa@nagoya-u.jp

2014-03-01

During their evolution, short-period exoplanets may lose envelope mass through atmospheric escape owing to intense X-ray and extreme ultraviolet (XUV) radiation from their host stars. Roche-lobe overflow induced by orbital evolution or intense atmospheric escape can also contribute to mass loss. To study the effects of mass loss on inner planet populations, we calculate the evolution of hot Jupiters considering mass loss of their envelopes and thermal contraction. Mass loss is assumed to occur through XUV-driven atmospheric escape and the following Roche-lobe overflow. The runaway effect of mass loss results in a dichotomy of populations: hot Jupiters that retain theirmore » envelopes and super Earths whose envelopes are completely lost. Evolution primarily depends on the core masses of planets and only slightly on migration history. In hot Jupiters with small cores (≅ 10 Earth masses), runaway atmospheric escape followed by Roche-lobe overflow may create sub-Jupiter deserts, as observed in both mass and radius distributions of planetary populations. Comparing our results with formation scenarios and observed exoplanets populations, we propose that populations of closely orbiting exoplanets are formed by capturing planets at/inside the inner edges of protoplanetary disks and subsequent evaporation of sub-Jupiters.« less

Anatomy of the magnetic catalysis by renormalization-group method

NASA Astrophysics Data System (ADS)

Hattori, Koichi; Itakura, Kazunori; Ozaki, Sho

2017-12-01

We first examine the scaling argument for a renormalization-group (RG) analysis applied to a system subject to the dimensional reduction in strong magnetic fields, and discuss the fact that a four-Fermi operator of the low-energy excitations is marginal irrespective of the strength of the coupling constant in underlying theories. We then construct a scale-dependent effective four-Fermi interaction as a result of screened photon exchanges at weak coupling, and establish the RG method appropriately including the screening effect, in which the RG evolution from ultraviolet to infrared scales is separated into two stages by the screening-mass scale. Based on a precise agreement between the dynamical mass gaps obtained from the solutions of the RG and Schwinger-Dyson equations, we discuss an equivalence between these two approaches. Focusing on QED and Nambu-Jona-Lasinio model, we clarify how the properties of the interactions manifest themselves in the mass gap, and point out an importance of respecting the intrinsic energy-scale dependences in underlying theories for the determination of the mass gap. These studies are expected to be useful for a diagnosis of the magnetic catalysis in QCD.

Transepithelial ultrafiltration and fractal power diffusion of D-glucose in the perfused rat intestine.

PubMed

Kochak, Gregory M; Mangat, Surinder

2002-12-23

Despite an enormous body of research investigating the mass transfer of D-glucose through biological membranes, carrier-mediated and first-order models have remained the prevalent models describing glucose's quantitative behavior even though they have proven to be inadequate over extended concentration ranges. Recent evidence from GLUT2 knockout studies further questions our understanding of molecular models, especially those employing Michaelis-Menten (MM)-type kinetic models. In this report, evidence is provided that D-glucose is absorbed by rat intestinal epithelium by a combination of convective ultrafiltration and nonlinear diffusion. The diffusive component of mass transfer is described by a concentration-dependent permeability coefficient, modeled as a fractal power function. Glucose and sodium chloride-dependent-induced aqueous convection currents are the result of prevailing oncotic and osmotic pressure effects, and a direct effect of glucose and sodium chloride on intestinal epithelium resulting in enhanced glucose, sodium ion, and water mobility. The fractal power model of glucose diffusion was superior to the conventional MM description. A convection-diffusion model of mass transfer adequately characterized glucose mass transfer over a 105-fold glucose concentration range in the presence and absence of sodium ion.

Azimuthal asymmetry in the risetime of the surface detector signals of the Pierre Auger Observatory

DOE PAGES

Aab, Alexander

2016-04-07

The azimuthal asymmetry in the risetime of signals in Auger surface detector stations is a source of information on shower development. The azimuthal asymmetry is due to a combination of the longitudinal evolution of the shower and geometrical effects related to the angles of incidence of the particles into the detectors. The magnitude of the effect depends upon the zenith angle and state of development of the shower and thus provides a novel observable, (secθ) max, sensitive to the mass composition of cosmic rays above 3 x 10 18 eV. By comparing measurements with predictions from shower simulations, we findmore » for both of our adopted models of hadronic physics (QGSJETII-04 and EPOS-LHC) an indication that the mean cosmic-ray mass increases slowly with energy, as has been inferred from other studies. However, the mass estimates are dependent on the shower model and on the range of distance from the shower core selected. Furthermore, the method has uncovered further deficiencies in our understanding of shower modelling that must be resolved before the mass composition can be inferred from (secθ) max.« less

Effect of stray electric fields on cooling of center of mass motion of levitated graphite flakes

NASA Astrophysics Data System (ADS)

Nagornykh, Pavel; Coppock, Joyce; Kane, Bruce

2015-03-01

Levitation of charged multilayer graphene flakes in a quadrupole ion trap provides a unique way to study graphene in isolated conditions. Cooling of a flake in such a setup is necessary for high vacuum measurements of the flake and is achieved by using a parametric feedback scheme. We present data showing the strong dependence of the cooling of the flake's center of mass motion on the stray electric fields. We achieve this by using auxiliary electrodes to shift the position of the trap center in space. Once the point of minimum interaction between the stray fields and the particle is found (leading to cooling of the flake motion to temperatures below 20K at pressure of 10-7 Torr), we can estimate charge and mass of the flake by observing quantized discharge of the particle and measure transient dynamics of the center of mass motion by turning the cooling off and on. As an additional benefit, the behavior of the flake away from the optimum trap position can be used to quantify stray fields' effect on the particle motion by measuring its spinning orientation and frequency dependence on offset from the optimum position.

Triggering collective oscillations by three-flavor effects

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

Dasgupta, Basudeb; Raffelt, Georg G.; Tamborra, Irene

2010-04-01

Collective flavor transformations in supernovae, caused by neutrino-neutrino interactions, are essentially a two-flavor phenomenon driven by the atmospheric mass difference and the small mixing angle {theta}{sub 13}. In the two-flavor approximation, the initial evolution depends logarithmically on {theta}{sub 13} and the system remains trapped in an unstable fixed point for {theta}{sub 13}=0. However, any effect breaking exact {nu}{sub {mu}-{nu}{tau}}equivalence triggers the conversion. Such three-flavor perturbations include radiative corrections to weak interactions, small differences between the {nu}{sub {mu}}and {nu}{sub {tau}}fluxes, or nonstandard interactions. Therefore, extremely small values of {theta}{sub 13} are in practice equivalent, the fate of the system depending onlymore » on the neutrino spectra and their mass ordering.« less

Anisotropic electrodynamics of type-II Weyl semimetal candidate WTe 2

DOE PAGES

Frenzel, A. J.; Homes, C. C.; Gibson, Q. D.; ...

2017-06-30

We investigated the ab-plane optical properties of single crystals of WTe 2 for light polarized parallel and perpendicular to the W-chain axis over a broad range of frequency and temperature. At far-infrared frequencies, we observed a striking dependence of the reflectance edge on light polarization, corresponding to anisotropy of the carrier effective masses. We quantitatively studied the temperature dependence of the plasma frequency, revealing a modest increase of the effective mass anisotropy in the ab plane upon cooling. We also found strongly anisotropic interband transitions persisting to high photon energies. These results were analyzed by comparison with ab initio calculations.more » The calculated and measured plasma frequencies agree to within 10% for both polarizations, while the calculated interband conductivity shows excellent agreement with experiment.« less

Stellar Mass Versus Stellar Velocity Dispersion: Which is Better for Linking Galaxies to Their Dark Matter Halos?

NASA Astrophysics Data System (ADS)

Li, Cheng; Wang, Lixin; Jing, Y. P.

2013-01-01

It was recently suggested that compared to its stellar mass (M *), the central stellar velocity dispersion (σ*) of a galaxy might be a better indicator for its host dark matter halo mass. Here we test this hypothesis by estimating the dark matter halo mass for central galaxies in groups as a function of M * and σ*. For this we have estimated the redshift-space cross-correlation function (CCF) between the central galaxies at given M * and σ* and a reference galaxy sample, from which we determine both the projected CCF, wp (rp ), and the velocity dispersion profile. A halo mass is then obtained from the average velocity dispersion within the virial radius. At fixed M *, we find very weak or no correlation between halo mass and σ*. In contrast, strong mass dependence is clearly seen even when σ* is limited to a narrow range. Our results thus firmly demonstrate that the stellar mass of central galaxies is still a good (if not the best) indicator for dark matter halo mass, better than the stellar velocity dispersion. The dependence of galaxy clustering on σ* at fixed M *, as recently discovered by Wake et al., may be attributed to satellite galaxies, for which the tidal stripping occurring within halos has stronger effect on stellar mass than on central stellar velocity dispersion.

The Nc dependencies of baryon masses: Analysis with Lattice QCD and Effective Theory

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

Calle Cordon, Alvaro C.; DeGrand, Thomas A.; Goity, Jose L.

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 massesmore » as well as in the hyperfine splittings.« less

Diffusion of multi-isotopic chemical species in molten silicates

NASA Astrophysics Data System (ADS)

Watkins, James M.; Liang, Yan; Richter, Frank; Ryerson, Frederick J.; DePaolo, Donald J.

2014-08-01

Diffusion experiments in a simplified Na2O-CaO-SiO2 liquid system are used to develop a general formulation for the fractionation of Ca isotopes during liquid-phase diffusion. Although chemical diffusion is a well-studied process, the mathematical description of the effects of diffusion on the separate isotopes of a chemical element is surprisingly underdeveloped and uncertain. Kinetic theory predicts a mass dependence on isotopic mobility, but it is unknown how this translates into a mass dependence on effective binary diffusion coefficients, or more generally, the chemical diffusion coefficients that are housed in a multicomponent diffusion matrix. Our experiments are designed to measure Ca mobility, effective binary diffusion coefficients, the multicomponent diffusion matrix, and the effects of chemical diffusion on Ca isotopes in a liquid of single composition. We carried out two chemical diffusion experiments and one self-diffusion experiment, all at 1250 °C and 0.7 GPa and using a bulk composition for which other information is available from the literature. The self-diffusion experiment is used to determine the mobility of Ca in the absence of diffusive fluxes of other liquid components. The chemical diffusion experiments are designed to determine the effect on Ca isotope fractionation of changing the counter-diffusing component from fast-diffusing Na2O to slow-diffusing SiO2. When Na2O is the main counter-diffusing species, CaO diffusion is fast and larger Ca isotopic effects are generated. When SiO2 is the main counter-diffusing species, CaO diffusion is slow and smaller Ca isotopic effects are observed. In both experiments, the liquid is initially isotopically homogeneous, and during the experiment Ca isotopes become fractionated by diffusion. The results are used as a test of a new general expression for the diffusion of isotopes in a multicomponent liquid system that accounts for both self diffusion and the effects of counter-diffusing species. Our results show that (1) diffusive isotopic fractionations depend on the direction of diffusion in composition space, (2) diffusive isotopic fractionations scale with effective binary diffusion coefficient, as previously noted by Watkins et al. (2011), (3) self-diffusion is not decoupled from chemical diffusion, (4) self diffusion can be faster than or slower than chemical diffusion and (5) off-diagonal terms in the chemical diffusion matrix have isotopic mass-dependence. The results imply that relatively large isotopic fractionations can be generated by multicomponent diffusion even in the absence of large concentration gradients of the diffusing element. The new formulations for isotope diffusion can be tested with further experimentation and provide an improved framework for interpreting mass-dependent isotopic variations in natural liquids.

Time-Dependent Damage Investigation of Rock Mass in an In Situ Experimental Tunnel

PubMed Central

Jiang, Quan; Cui, Jie; Chen, Jing

2012-01-01

In underground tunnels or caverns, time-dependent deformation or failure of rock mass, such as extending cracks, gradual rock falls, etc., are a costly irritant and a major safety concern if the time-dependent damage of surrounding rock is serious. To understand the damage evolution of rock mass in underground engineering, an in situ experimental testing was carried out in a large belowground tunnel with a scale of 28.5 m in width, 21 m in height and 352 m in length. The time-dependent damage of rock mass was detected in succession by an ultrasonic wave test after excavation. The testing results showed that the time-dependent damage of rock mass could last a long time, i.e., nearly 30 days. Regression analysis of damage factors defined by wave velocity, resulted in the time-dependent evolutional damage equation of rock mass, which corresponded with logarithmic format. A damage viscoelastic-plastic model was developed to describe the exposed time-dependent deterioration of rock mass by field test, such as convergence of time-dependent damage, deterioration of elastic modules and logarithmic format of damage factor. Furthermore, the remedial measures for damaged surrounding rock were discussed based on the measured results and the conception of damage compensation, which provides new clues for underground engineering design.

An Alternative Approach to the Extended Drude Model

NASA Astrophysics Data System (ADS)

Gantzler, N. J.; Dordevic, S. V.

2018-05-01

The original Drude model, proposed over a hundred years ago, is still used today for the analysis of optical properties of solids. Within this model, both the plasma frequency and quasiparticle scattering rate are constant, which makes the model rather inflexible. In order to circumvent this problem, the so-called extended Drude model was proposed, which allowed for the frequency dependence of both the quasiparticle scattering rate and the effective mass. In this work we will explore an alternative approach to the extended Drude model. Here, one also assumes that the quasiparticle scattering rate is frequency dependent; however, instead of the effective mass, the plasma frequency becomes frequency-dependent. This alternative model is applied to the high Tc superconductor Bi2Sr2CaCu2O8+δ (Bi2212) with Tc = 92 K, and the results are compared and contrasted with the ones obtained from the conventional extended Drude model. The results point to several advantages of this alternative approach to the extended Drude model.

Spherical collapse of dark matter haloes in tidal gravitational fields

NASA Astrophysics Data System (ADS)

Reischke, Robert; Pace, Francesco; Meyer, Sven; Schäfer, Björn Malte

2016-11-01

We study the spherical collapse model in the presence of external gravitational tidal shear fields for different dark energy scenarios and investigate the impact on the mass function and cluster number counts. While previous studies of the influence of shear and rotation on δc have been performed with heuristically motivated models, we try to avoid this model dependence and sample the external tidal shear values directly from the statistics of the underlying linearly evolved density field based on first-order Lagrangian perturbation theory. Within this self-consistent approach, in the sense that we restrict our treatment to scales where linear theory is still applicable, only fluctuations larger than the scale of the considered objects are included into the sampling process which naturally introduces a mass dependence of δc. We find that shear effects are predominant for smaller objects and at lower redshifts, I. e. the effect on δc is at or below the percent level for the ΛCDM model. For dark energy models we also find small but noticeable differences, similar to ΛCDM. The virial overdensity ΔV is nearly unaffected by the external shear. The now mass dependent δc is used to evaluate the mass function for different dark energy scenarios and afterwards to predict cluster number counts, which indicate that ignoring the shear contribution can lead to biases of the order of 1σ in the estimation of cosmological parameters like Ωm, σ8 or w.

Rehearsal Strategies Can Enlarge or Diminish the Spacing Effect: Pure versus Mixed Lists and Encoding Strategy

ERIC Educational Resources Information Center

Delaney, Peter F.; Verkoeijen, Peter P. J. L.

2009-01-01

Using 5 experiments, the authors explored the dependency of spacing effects on rehearsal patterns. Encouraging rehearsal borrowing produced opposing effects on mixed lists (containing both spaced and massed repetitions) and pure lists (containing only one or the other), magnifying spacing effects on mixed lists but diminishing spacing effects on…

Adiabatic invariants in stellar dynamics, 3: Application to globular cluster evolution

NASA Technical Reports Server (NTRS)

Weinberg, Martin D.

1994-01-01

The previous two companion papers demonstrate that slowly varying perturbations may not result in adiabatic cutoffs and provide a formalism for computing the long-term effects of time-dependent perturbations on stellar systems. Here, the theory is implemented in a Fokker-Planck code and a suite of runs illustrating the effects of shock heating on globular cluster evolution are described. Shock heating alone results in considerable mass loss for clusters with R(sub g) less than or approximately 8 kpc: a concentration c = 1.5 cluster with R(sub g) kpc loses up to 95% of its initial mass in 15 Gyr. Only those with concentration c greater than or approximately 1.3 survive disk shocks inside of this radius. Other effects, such as mass loss by stellar evolution, will decrease this survival bound. Loss of the initial halo together with mass segregation leads to mass spectral indices, x, which may be considerably larger than their initial values.

A representation for the turbulent mass flux contribution to Reynolds-stress and two-equation closures for compressible turbulence

NASA Technical Reports Server (NTRS)

Ristorcelli, J. R.

1993-01-01

The turbulent mass flux, or equivalently the fluctuating Favre velocity mean, appears in the first and second moment equations of compressible kappa-epsilon and Reynolds stress closures. Mathematically it is the difference between the unweighted and density-weighted averages of the velocity field and is therefore a measure of the effects of compressibility through variations in density. It appears to be fundamental to an inhomogeneous compressible turbulence, in which it characterizes the effects of the mean density gradients, in the same way the anisotropy tensor characterizes the effects of the mean velocity gradients. An evolution equation for the turbulent mass flux is derived. A truncation of this equation produces an algebraic expression for the mass flux. The mass flux is found to be proportional to the mean density gradients with a tensor eddy-viscosity that depends on both the mean deformation and the Reynolds stresses. The model is tested in a wall bounded DNS at Mach 4.5 with notable results.

LOW-MASS SUPPRESSION OF THE SATELLITE LUMINOSITY FUNCTION DUE TO THE SUPERSONIC BARYON-COLD-DARK-MATTER RELATIVE VELOCITY

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

Bovy, Jo; Dvorkin, Cora

We study the effect of the supersonic baryon-cold-dark-matter (CDM) flow, which has recently been shown to have a large effect on structure formation during the dark ages 10 {approx}< z {approx}< 1000, on the abundance of luminous, low-mass satellite galaxies around galaxies like the Milky Way. As the supersonic baryon-CDM flow significantly suppresses both the number of halos formed and the amount of baryons accreted onto such halos of masses 10{sup 6} < M{sub halo}/M{sub Sun} < 10{sup 8} at z {approx}> 10, a large effect results on the stellar luminosity function before reionization. As halos of these masses aremore » believed to have very little star formation after reionization due to the effects of photoheating by the ultraviolet background, this effect persists to the present day. We calculate that the number of low-mass 10{sup 6} < M{sub halo}/M{sub Sun} < 5 Multiplication-Sign 10{sup 7} halos that host luminous satellite galaxies today is typically suppressed by 50%, with values ranging up to 90% in regions where the initial supersonic velocity is high. We show that this previously ignored cosmological effect resolves some of the tension between the observed and predicted number of low-mass satellites in the Milky Way, reducing the need for other mass-dependent star-formation suppression before reionization.« less

A novel test of the phenotype-linked fertility hypothesis reveals independent components of fertility.

PubMed Central

Pizzari, Tommaso; Jensen, Per; Cornwallis, Charles K.

2004-01-01

The phenotype-linked fertility hypothesis predicts that male sexual ornaments signal fertilizing efficiency and that the coevolution of male ornaments and female preference for such ornaments is driven by female pursuit of fertility benefits. In addition, directional testicular asymmetry frequently observed in birds has been suggested to reflect fertilizing efficiency and to covary with ornament expression. However, the idea of a phenotypic relationship between male ornaments and fertilizing efficiency is often tested in populations where environmental effects mask the underlying genetic associations between ornaments and fertilizing efficiency implied by this idea. Here, we adopt a novel design, which increases genetic diversity through the crossing of two divergent populations while controlling for environmental effects, to test: (i) the phenotypic relationship between male ornaments and both, gonadal (testicular mass) and gametic (sperm quality) components of fertilizing efficiency; and (ii) the extent to which these components are phenotypically integrated in the fowl, Gallus gallus. We show that consistent with theory, the testosterone-dependent expression of a male ornament, the comb, predicted testicular mass. However, despite their functional inter-dependence, testicular mass and sperm quality were not phenotypically integrated. Consistent with this result, males of one parental population invested more in testicular and comb mass, whereas males of the other parental population had higher sperm quality. We found no evidence that directional testicular asymmetry covaried with ornament expression. These results shed new light on the evolutionary relationship between male fertilizing efficiency and ornaments. Although testosterone-dependent ornaments may covary with testicular mass and thus reflect sperm production rate, the lack of phenotypic integration between gonadal and gametic traits reveals that the expression of an ornament is unlikely to reflect the overall fertilizing efficiency of a male. PMID:15002771

Instrumental effects on the temperature and density derived from the light ion mass spectrometer

NASA Technical Reports Server (NTRS)

Craven, P. D.; Reasoner, D. L.

1983-01-01

An expression for the flux into a retarding potential analyzer (RPA) is derived which takes into account the instrumental effect of a dependence on energy of the solid angle of the acceptance cone. A second instrumental effect of a limited bandpass is briefly discussed. Using the (LIMS) instrument on SCATHA, it is shown that temperatures and densities derived without considering the effect of the solid angle dependence on energy will be too low, dramatically so for E(t) E(1), where E(1) is the e folding distance of the solid angle dependence and E(t) is the thermal energy of the plasma. For E(t) E(1), there is effectively no impact on the derived temperatures and densities if the solid angle effect is ignored.

Substructure of fuzzy dark matter haloes

NASA Astrophysics Data System (ADS)

Du, Xiaolong; Behrens, Christoph; Niemeyer, Jens C.

2017-02-01

We derive the halo mass function (HMF) for fuzzy dark matter (FDM) by solving the excursion set problem explicitly with a mass-dependent barrier function, which has not been done before. We find that compared to the naive approach of the Sheth-Tormen HMF for FDM, our approach has a higher cutoff mass and the cutoff mass changes less strongly with redshifts. Using merger trees constructed with a modified version of the Lacey & Cole formalism that accounts for suppressed small-scale power and the scale-dependent growth of FDM haloes and the semi-analytic GALACTICUS code, we study the statistics of halo substructure including the effects from dynamical friction and tidal stripping. We find that if the dark matter is a mixture of cold dark matter (CDM) and FDM, there will be a suppression on the halo substructure on small scales which may be able to solve the missing satellites problem faced by the pure CDM model. The suppression becomes stronger with increasing FDM fraction or decreasing FDM mass. Thus, it may be used to constrain the FDM model.

Effects of mass loading on dayside solar wind-magnetosphere interactions

NASA Astrophysics Data System (ADS)

Zhang, B.; Brambles, O.; Wiltberger, M. J.; Lyon, J.; Lotko, W.

2016-12-01

Satellite observations have shown that terrestrial-sourced plasmas mass load the dayside magnetopause and cause reductions in local reconnection rates. Whether the integrated dayside reconnection rate is affected by these local mass-loading processes is still an open question. Several mechanisms have been proposed to describe the control of dayside reconnection, including the local-control and global-control hypotheses. We have conducted a series of controlled numerical simulations to investigate the response of dayside solar wind-magnetopshere (SW-M) coupling to mass loading processes. Our simulation results show that the coupled SW-M system may exhibit both local and global control behaviors depending on the amount of mass loading. With a small amount of mass loading, the changes in the local reconnection rate does not affect magnetosheath properties and the geoeffective length in the upstream solar wind, resulting in the same integrated dayside reconnection rate. With a large amount of mass loading, the magnetosheath properties and the geoeffective length are significantly modified by slowing down the local reconnection rate, resulting in a significant reduction in the integrated dayside reconnection rate. The response of magnetosheath properties to mass loading is expected from the Cassak-Shay asymmetric reconnection theory through conservation of energy. The physical origin of the transition regime between local and global control is qualitatively explained. The parameters that determine the transition regime depend on the location, spatial extension and density of the mass loading process.

Position-Dependent Mass Schrödinger Equation for the Morse Potential

NASA Astrophysics Data System (ADS)

Ovando, G.; Peña, J. J.; Morales, J.; López-Bonilla, J.

2017-01-01

The position dependent mass Schrödinger equation (PDMSE) has a wide range of quantum applications such as the study of semiconductors, quantum wells, quantum dots and impurities in crystals, among many others. On the other hand, the Morse potential is one of the most important potential models used to study the electronic properties of diatomic molecules. In this work, the solution of the effective mass one-dimensional Schrödinger equation for the Morse potential is presented. This is done by means of the canonical transformation method in algebraic form. The PDMSE is solved for any model of the proposed kinetic energy operators as for example the BenDaniel-Duke, Gora-Williams, Zhu-Kroemer or Li-Kuhn. Also, in order to solve the PDMSE with Morse potential, we consider a superpotential leading to a special form of the exactly solvable Schrödinger equation of constant mass for a class of multiparameter exponential-type potential along with a proper mass distribution. The proposed approach is general and can be applied in the search of new potentials suitable on science of materials by looking into the viable choices of the mass function.

Missing Link: Bayesian detection and measurement of intermediate-mass black-hole binaries

NASA Astrophysics Data System (ADS)

Graff, Philip B.; Buonanno, Alessandra; Sathyaprakash, B. S.

2015-07-01

We perform Bayesian analysis of gravitational-wave signals from nonspinning, intermediate-mass black-hole binaries (IMBHBs) with observed total mass, Mobs, from 50 M⊙ to 500 M⊙ and mass ratio 1-4 using advanced LIGO and Virgo detectors. We employ inspiral-merger-ringdown waveform models based on the effective-one-body formalism and include subleading modes of radiation beyond the leading (2,2) mode. The presence of subleading modes increases signal power for inclined binaries and allows for improved accuracy and precision in measurements of the masses as well as breaking of degeneracies in distance, orientation and polarization. For low total masses, Mobs≲50 M⊙ , for which the inspiral signal dominates, the observed chirp mass Mobs=Mobsη3 /5 (η being the symmetric mass ratio) is better measured. In contrast, as increasing power comes from merger and ringdown, we find that the total mass Mobs has better relative precision than Mobs. Indeed, at high Mobs (≥300 M⊙ ), the signal resembles a burst and the measurement thus extracts the dominant frequency of the signal that depends on Mobs. Depending on the binary's inclination, at signal-to-noise ratio (SNR) of 12, uncertainties in Mobs can be as large as ˜20 - 25 % while uncertainties in Mobs are ˜50 - 60 % in binaries with unequal masses (those numbers become ˜17 % vs. ˜22 % in more symmetric mass-ratio binaries). Although large, those uncertainties in Mobs will establish the existence of IMBHs. We find that effective-one-body waveforms with subleading modes are essential to confirm a signal's presence in the data, with calculated Bayesian evidences yielding a false alarm probability below 10-5 for SNR ≳9 in Gaussian noise. Our results show that gravitational-wave observations can offer a unique tool to observe and understand the formation, evolution and demographics of IMBHs, which are difficult to observe in the electromagnetic window.

Nuclear Mass Predictions within the Skyrme HFB Theory

NASA Astrophysics Data System (ADS)

Samyn, M.; Goriely, S.; Pearson, J. M.

2005-05-01

To increase the reliability of predictions of highly neutron-rich nuclear masses we systematically analyze the sensitivity of Hartree-Fock-Bogoliubov (HFB) mass formulae to various physical inputs, such as a density dependence of the pairing interaction, a low effective mass, the particle-number projection, the symmetry energy, … We typically use a 10-parameter Skyrme force and a 4-parameter δ-function pairing force. The 14 degrees of freedom are adjusted to the masses of all measured nuclei with N,Z ⩾ 8 given in the 2001 and 2003 Audi et al. compilations. The masses of light and proton-rich nuclei are corrected by a 4-parameter phenomenological Wigner term. With more than ten such parameter sets complete mass tables are constructed, going from one drip line to the other, up to Z = 120.

Effects of solvent density on retention in gas-liquid chromatography. I. Alkanes solutes in polyethylene glycol stationary phases.

PubMed

González, F R; Pérez-Parajón, J; García-Domínguez, J A

2002-04-12

Gas-liquid chromatographic columns were prepared coating silica capillaries with poly(oxyethylene) polymers of different molecular mass distributions, in the range of low number-average molar masses, where the density still varies significantly. A novel, high-temperature, rapid evaporation method was developed and applied to the static coating of the low-molecular-mass stationary phases. The analysis of alkanes retention data from these columns reveals that the dependence of the partition coefficient with the solvent macroscopic density is mainly due to a variation of entropy. Enthalpies of solute transfer contribute poorly to the observed variations of retention. Since the alkanes solubility diminishes with the increasing solvent density, and this variation is weakly dependent with temperature, it is concluded that the decrease of free-volume in the liquid is responsible for this behavior.

Isotope effects in photo dissociation of ozone with visible light

NASA Astrophysics Data System (ADS)

Früchtl, Marion; Janssen, Christof; Röckmann, Thomas

2014-05-01

Ozone (O3) plays a key role for many chemical oxidation processes in the Earth's atmosphere. In these chemical reactions, ozone can transfer oxygen to other trace gases. This is particularly interesting, since O3 has a very peculiar isotope composition. Following the mass dependent fractionation equation δ17O = 0.52 * δ18O, most fractionation processes depend directly on mass. However, O3 shows an offset to the mass dependent fractionation line. Processes, which show such anomalies, are termed mass independent fractionations (MIF). A very well studied example for a chemical reaction that leads to mass independent fractionation is the O3 formation reaction. To what degree O3 destruction reactions need to be considered in order to understand the isotope composition of atmospheric O3 is still not fully understood and an open question within scientific community. We set up new experiments to investigate the isotope effect resulting from photo dissociation of O3 in the Chappuis band (R1). Initial O3 is produced by an electric discharge. After photolysis O3 is collected in a cold trap at the triple point temperature of nitrogen (63K). O3 is then converted to O2 in order to measure the oxygen isotopes of O3 using isotope ratio mass spectrometry. To isolate O3 photo dissociation (R1) from O3 decomposition (R2) and secondary O3 formation (R3), we use varying amounts of carbon monoxide (CO) as O atom quencher (R4). In this way we suppress the O + O3 reaction (R3) and determine the isotope fractionation in R1 and R2 separately. We present first results on the isotope effects in O3 photo dissociation with visible light in the presence of different bath gases. Results are interpreted based on chemical kinetics modeling. (R1) O3 + hυ → O (3P) + O2 (R2) O3 + O (3P) → 2 O2 (R3) O + O2 + M → O3 + M (R4) O (3P) + CO + M → CO2 + M

Empirical mass-loss rates for 25 O and early B stars, derived from Copernicus observations

NASA Technical Reports Server (NTRS)

Gathier, R.; Lamers, H. J. G. L. M.; Snow, T. P.

1981-01-01

Ultraviolet line profiles are fitted with theoretical line profiles in the cases of 25 stars covering a spectral type range from O4 to B1, including all luminosity classes. Ion column densities are compared for the determination of wind ionization, and it is found that the O VI/N V ratio is dependent on the mean density of the wind and not on effective temperature value, while the Si IV/N V ratio is temperature-dependent. The column densities are used to derive a mass-loss rate parameter that is empirically correlated against the mass-loss rate by means of standard stars with well-determined rates from IR or radio data. The empirical mass-loss rates obtained are compared with those derived by others and found to vary by as much as a factor of 10, which is shown to be due to uncertainties or errors in the ionization fractions of models used for wind ionization balance prediction.

Inertial ratchet driven by colored Lévy noise: current inversion and mass separation

NASA Astrophysics Data System (ADS)

Lü, Yan; Lu, Hong

2018-05-01

Transport of underdamped particles subjected to colored Lévy noise in an asymmetric periodic potential is investigated. Besides the competition between the long jumps and the noise correlation that leads to current inversion, the inertial effect is another important factor that can influence the transport behavior. Note that the critical correlation time at which the current inversion occurs depends on mass. This leads to the current reversals on varying mass and implies mass separation even in the absence of whatever additional load force. Additionally, we find that the region of allowed correlation times for mass separation moves toward a smaller value of with increasing Lévy index or noise intensity.

Effects of functional group mass variance on vibrational properties and thermal transport in graphene

DOE PAGES

Lindsay, L.; Kuang, Y.

2017-03-13

Intrinsic thermal resistivity critically depends on features of phonon dispersions dictated by harmonic interatomic forces and masses. We present the effects of functional group mass variance on vibrational properties and thermal conductivity (κ ) of functionalized graphene from first principles calculations. We also use graphane, a buckled graphene backbone with covalently bonded Hydrogen atoms on both sides, as the base material and vary the mass of the Hydrogen atoms to simulate the effect of mass variance from other functional groups. We find non-monotonic behavior of κ with increasing mass of the functional group and an unusual cross-over from acoustic-dominated tomore » optic-dominated thermal transport behavior. We connect this cross-over to changes in the phonon dispersion with varying mass which suppress acoustic phonon velocities, but also give unusually high velocity optic modes. Further, we show that out-of-plane acoustic vibrations contribute significantly more to thermal transport than in-plane acoustic modes despite breaking of a reflection symmetry based scattering selection rule responsible for their large contributions in graphene. Our work demonstrates the potential for manipulation and engineering of thermal transport properties in two dimensional materials toward targeted applications.« less

Effects of functional group mass variance on vibrational properties and thermal transport in graphene

NASA Astrophysics Data System (ADS)

Lindsay, L.; Kuang, Y.

2017-03-01

Intrinsic thermal resistivity critically depends on features of phonon dispersions dictated by harmonic interatomic forces and masses. Here we present the effects of functional group mass variance on vibrational properties and thermal conductivity (κ ) of functionalized graphene from first-principles calculations. We use graphane, a buckled graphene backbone with covalently bonded hydrogen atoms on both sides, as the base material and vary the mass of the hydrogen atoms to simulate the effect of mass variance from other functional groups. We find nonmonotonic behavior of κ with increasing mass of the functional group and an unusual crossover from acoustic-dominated to optic-dominated thermal transport behavior. We connect this crossover to changes in the phonon dispersion with varying mass which suppress acoustic phonon velocities, but also give unusually high velocity optic modes. Further, we show that out-of-plane acoustic vibrations contribute significantly more to thermal transport than in-plane acoustic modes despite breaking of a reflection-symmetry-based scattering selection rule responsible for their large contributions in graphene. This work demonstrates the potential for manipulation and engineering of thermal transport properties in two-dimensional materials toward targeted applications.

Effects of functional group mass variance on vibrational properties and thermal transport in graphene

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

Lindsay, L.; Kuang, Y.

Intrinsic thermal resistivity critically depends on features of phonon dispersions dictated by harmonic interatomic forces and masses. We present the effects of functional group mass variance on vibrational properties and thermal conductivity (κ ) of functionalized graphene from first principles calculations. We also use graphane, a buckled graphene backbone with covalently bonded Hydrogen atoms on both sides, as the base material and vary the mass of the Hydrogen atoms to simulate the effect of mass variance from other functional groups. We find non-monotonic behavior of κ with increasing mass of the functional group and an unusual cross-over from acoustic-dominated tomore » optic-dominated thermal transport behavior. We connect this cross-over to changes in the phonon dispersion with varying mass which suppress acoustic phonon velocities, but also give unusually high velocity optic modes. Further, we show that out-of-plane acoustic vibrations contribute significantly more to thermal transport than in-plane acoustic modes despite breaking of a reflection symmetry based scattering selection rule responsible for their large contributions in graphene. Our work demonstrates the potential for manipulation and engineering of thermal transport properties in two dimensional materials toward targeted applications.« less

Dipole moment and polarizability of impurity doped quantum dots under anisotropy, spatially-varying effective mass and dielectric screening function: Interplay with noise

NASA Astrophysics Data System (ADS)

Ghosh, Anuja; Ghosh, Manas

2018-01-01

Present work explores the profiles of polarizability (αp) and electric dipole moment (μ) of impurity doped GaAs quantum dot (QD) under the aegis of spatially-varying effective mass, spatially-varying dielectric constant and anisotropy of the system. Presence of noise has also been invoked to examine how its intervention further tunes αp and μ. Noise term maintains a Gaussian white feature and it has been incorporated to the system through two different roadways; additive and multiplicative. The various facets of influence of spatially-varying effective mass, spatially-varying dielectric constant and anisotropy on αp and μ depend quite delicately on presence/absence of noise and also on the mode through which noise has been administered. The outcomes of the study manifest viable routes to harness the dipole moment and polarizability of doped QD system through the interplay between noise, anisotropy and variable effective mass and dielectric constant of the system.

The tree balance signature of mass extinction is erased by continued evolution in clades of constrained size with trait-dependent speciation

PubMed Central

Yang, Guan-Dong; Agapow, Paul-Michael

2017-01-01

The kind and duration of phylogenetic topological “signatures” left in the wake of macroevolutionary events remain poorly understood. To this end, we examined a broad range of simulated phylogenies generated using trait-biased, heritable speciation probabilities and mass extinction that could be either random or selective on trait value, but also using background extinction and diversity-dependence to constrain clade sizes. In keeping with prior results, random mass extinction increased imbalance of clades that recovered to pre-extinction size, but was a relatively weak effect. Mass extinction that was selective on trait values tended to produce clades of similar or greater balance compared to random extinction or controls. Allowing evolution to continue past the point of clade-size recovery resulted in erosion and eventual erasure of this signal, with all treatments converging on similar values of imbalance, except for very intense extinction regimes targeted at taxa with high speciation rates. Return to a more balanced state with extended post-extinction evolution was also associated with loss of the previous phylogenetic root in most treatments. These results further demonstrate that while a mass extinction event can produce a recognizable phylogenetic signal, its effects become increasingly obscured the further an evolving clade gets from that event, with any sharp imbalance due to unrelated evolutionary factors. PMID:28644846

THE EVOLUTION OF THE STELLAR MASS FUNCTION OF GALAXIES FROM z = 4.0 AND THE FIRST COMPREHENSIVE ANALYSIS OF ITS UNCERTAINTIES: EVIDENCE FOR MASS-DEPENDENT EVOLUTION

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

Marchesini, Danilo; Van Dokkum, Pieter G.; Foerster Schreiber, Natascha M.

2009-08-20

We present the evolution of the stellar mass function (SMF) of galaxies from z = 4.0 to z = 1.3 measured from a sample constructed from the deep near-infrared Multi-wavelength Survey by Yale-Chile, the Faint Infrared Extragalactic Survey, and the Great Observatories Origins Deep Survey-Chandra Deep Field South surveys, all having very high-quality optical to mid-infrared data. This sample, unique in that it combines data from surveys with a large range of depths and areas in a self-consistent way, allowed us to (1) minimize the uncertainty due to cosmic variance and empirically quantify its contribution to the total error budget;more » (2) simultaneously probe the high-mass end and the low-mass end (down to {approx}0.05 times the characteristic stellar mass) of the SMF with good statistics; and (3) empirically derive the redshift-dependent completeness limits in stellar mass. We provide, for the first time, a comprehensive analysis of random and systematic uncertainties affecting the derived SMFs, including the effect of metallicity, extinction law, stellar population synthesis model, and initial mass function. We find that the mass density evolves by a factor of {approx}17{sup +7}{sub -10} since z = 4.0, mostly driven by a change in the normalization {phi}*. If only random errors are taken into account, we find evidence for mass-dependent evolution, with the low-mass end evolving more rapidly than the high-mass end. However, we show that this result is no longer robust when systematic uncertainties due to the SED-modeling assumptions are taken into account. Another significant uncertainty is the contribution to the overall stellar mass density of galaxies below our mass limit; future studies with WFC3 will provide better constraints on the SMF at masses below 10{sup 10} M{sub sun} at z>2. Taking our results at face value, we find that they are in conflict with semianalytic models of galaxy formation. The models predict SMFs that are in general too steep, with too many low-mass galaxies and too few high-mass galaxies. The discrepancy at the high-mass end is susceptible to uncertainties in the models and the data, but the discrepancy at the low-mass end may be more difficult to explain.« less

Charge carrier effective mass and concentration derived from combination of Seebeck coefficient and Te 125 NMR measurements in complex tellurides

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

Levin, E. M.

Thermoelectric materials utilize the Seebeck effect to convert heat to electrical energy. The Seebeck coefficient (thermopower), S, depends on the free (mobile) carrier concentration, n, and effective mass, m*, as S ~ m*/n 2/3. The carrier concentration in tellurides can be derived from 125Te nuclear magnetic resonance (NMR) spin-lattice relaxation measurements. The NMR spin-lattice relaxation rate, 1/T 1, depends on both n and m* as 1/T 1~(m*) 3/2n (within classical Maxwell-Boltzmann statistics) or as 1/T1~(m*) 2n 2/3 (within quantum Fermi-Dirac statistics), which challenges the correct determination of the carrier concentration in some materials by NMR. Here it is shown thatmore » the combination of the Seebeck coefficient and 125Te NMR spin-lattice relaxation measurements in complex tellurides provides a unique opportunity to derive the carrier effective mass and then to calculate the carrier concentration. This approach was used to study Ag xSb xGe 50–2xTe 50, well-known GeTe-based high-efficiency tellurium-antimony-germanium-silver thermoelectric materials, where the replacement of Ge by [Ag+Sb] results in significant enhancement of the Seebeck coefficient. Thus, values of both m* and n derived using this combination show that the enhancement of thermopower can be attributed primarily to an increase of the carrier effective mass and partially to a decrease of the carrier concentration when the [Ag+Sb] content increases.« less

Charge carrier effective mass and concentration derived from combination of Seebeck coefficient and Te 125 NMR measurements in complex tellurides

DOE PAGES

Levin, E. M.

2016-06-27

Thermoelectric materials utilize the Seebeck effect to convert heat to electrical energy. The Seebeck coefficient (thermopower), S, depends on the free (mobile) carrier concentration, n, and effective mass, m*, as S ~ m*/n 2/3. The carrier concentration in tellurides can be derived from 125Te nuclear magnetic resonance (NMR) spin-lattice relaxation measurements. The NMR spin-lattice relaxation rate, 1/T 1, depends on both n and m* as 1/T 1~(m*) 3/2n (within classical Maxwell-Boltzmann statistics) or as 1/T1~(m*) 2n 2/3 (within quantum Fermi-Dirac statistics), which challenges the correct determination of the carrier concentration in some materials by NMR. Here it is shown thatmore » the combination of the Seebeck coefficient and 125Te NMR spin-lattice relaxation measurements in complex tellurides provides a unique opportunity to derive the carrier effective mass and then to calculate the carrier concentration. This approach was used to study Ag xSb xGe 50–2xTe 50, well-known GeTe-based high-efficiency tellurium-antimony-germanium-silver thermoelectric materials, where the replacement of Ge by [Ag+Sb] results in significant enhancement of the Seebeck coefficient. Thus, values of both m* and n derived using this combination show that the enhancement of thermopower can be attributed primarily to an increase of the carrier effective mass and partially to a decrease of the carrier concentration when the [Ag+Sb] content increases.« less

The Effects of Parachute System Mass and Suspension-Line Elastic Properties on the LADT #3 Viking Parachute Inflation Load

NASA Technical Reports Server (NTRS)

Talay, Theodore A.; Poole, Lamont R.

1971-01-01

Analytical calculations have considered the effects of 1) varying parachute system mass, 2) suspension-line damping, and 3) alternate suspension-line force-elongation data on the canopy force history. Results indicate the canopy force on the LADT #3 parachute did not substantially exceed the recorded vehicle force reading and that the above factors can have significant effects on the canopy force history. Analytical calculations have considered the effects of i) varying parachute system mass, 2) suspension line damping, and 3) different suspension-line force-elongation data on the canopy force history. Based on the results of this study the following conclusions are drawn: Specifically, 1. At the LADT #3 failure time of 1.70 seconds, the canopy force ranged anywhere from 15.7% below to 2.4% above the vehicle force depending upon the model and data used. Therefore, the canopy force did not substantially exceed the recorded vehicle force reading. 2. At a predicted full inflation time of 1.80 seconds the canopy force would be greater than the vehicle force by from 1.1% to 10.6%, again depending upon the model and data used. Generally, 3. At low altitudes, enclosed and apparent air mass can significantly effect the canopy force calculated and should, therefore, not be neglected. 4. The canopy force calculations are sensitive to decelerator physical properties. In this case changes in the damping and/or force-elongation characteristics produced significant changes in the canopy force histories. Accurate prediction of canopy force histories requires accurate inputs in these areas.

GALAXY INFALL BY INTERACTING WITH ITS ENVIRONMENT: A COMPREHENSIVE STUDY OF 340 GALAXY CLUSTERS

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

Gu, Liyi; Wen, Zhonglue; Gandhi, Poshak

To study systematically the evolution of the angular extents of the galaxy, intracluster medium (ICM), and dark matter components in galaxy clusters, we compiled the optical and X-ray properties of a sample of 340 clusters with redshifts <0.5, based on all the available data from the Sloan Digital Sky Survey and Chandra / XMM-Newton . For each cluster, the member galaxies were determined primarily with photometric redshift measurements. The radial ICM mass distribution, as well as the total gravitational mass distribution, was derived from a spatially resolved spectral analysis of the X-ray data. When normalizing the radial profile of galaxymore » number to that of the ICM mass, the relative curve was found to depend significantly on the cluster redshift; it drops more steeply toward the outside in lower-redshift subsamples. The same evolution is found in the galaxy-to-total mass profile, while the ICM-to-total mass profile varies in an opposite way. The behavior of the galaxy-to-ICM distribution does not depend on the cluster mass, suggesting that the detected redshift dependence is not due to mass-related effects, such as sample selection bias. Also, it cannot be ascribed to various redshift-dependent systematic errors. We interpret that the galaxies, the ICM, and the dark matter components had similar angular distributions when a cluster was formed, while the galaxies traveling in the interior of the cluster have continuously fallen toward the center relative to the other components, and the ICM has slightly expanded relative to the dark matter although it suffers strong radiative loss. This cosmological galaxy infall, accompanied by an ICM expansion, can be explained by considering that the galaxies interact strongly with the ICM while they are moving through it. The interaction is considered to create a large energy flow of 10{sup 4445} erg s{sup 1} per cluster from the member galaxies to their environment, which is expected to continue over cosmological timescales.« less

Galaxy Infall by Interacting with Its Environment: A Comprehensive Study of 340 Galaxy Clusters

NASA Astrophysics Data System (ADS)

Gu, Liyi; Wen, Zhonglue; Gandhi, Poshak; Inada, Naohisa; Kawaharada, Madoka; Kodama, Tadayuki; Konami, Saori; Nakazawa, Kazuhiro; Xu, Haiguang; Makishima, Kazuo

2016-07-01

To study systematically the evolution of the angular extents of the galaxy, intracluster medium (ICM), and dark matter components in galaxy clusters, we compiled the optical and X-ray properties of a sample of 340 clusters with redshifts <0.5, based on all the available data from the Sloan Digital Sky Survey and Chandra/XMM-Newton. For each cluster, the member galaxies were determined primarily with photometric redshift measurements. The radial ICM mass distribution, as well as the total gravitational mass distribution, was derived from a spatially resolved spectral analysis of the X-ray data. When normalizing the radial profile of galaxy number to that of the ICM mass, the relative curve was found to depend significantly on the cluster redshift; it drops more steeply toward the outside in lower-redshift subsamples. The same evolution is found in the galaxy-to-total mass profile, while the ICM-to-total mass profile varies in an opposite way. The behavior of the galaxy-to-ICM distribution does not depend on the cluster mass, suggesting that the detected redshift dependence is not due to mass-related effects, such as sample selection bias. Also, it cannot be ascribed to various redshift-dependent systematic errors. We interpret that the galaxies, the ICM, and the dark matter components had similar angular distributions when a cluster was formed, while the galaxies traveling in the interior of the cluster have continuously fallen toward the center relative to the other components, and the ICM has slightly expanded relative to the dark matter although it suffers strong radiative loss. This cosmological galaxy infall, accompanied by an ICM expansion, can be explained by considering that the galaxies interact strongly with the ICM while they are moving through it. The interaction is considered to create a large energy flow of 1044-45 erg s-1 per cluster from the member galaxies to their environment, which is expected to continue over cosmological timescales.

Galaxy formation in the Planck cosmology - IV. Mass and environmental quenching, conformity and clustering

NASA Astrophysics Data System (ADS)

Henriques, Bruno M. B.; White, Simon D. M.; Thomas, Peter A.; Angulo, Raul E.; Guo, Qi; Lemson, Gerard; Wang, Wenting

2017-08-01

We study the quenching of star formation as a function of redshift, environment and stellar mass in the galaxy formation simulations of Henriques et al. (2015), which implement an updated version of the Munich semi-analytic model (L-GALAXIES) on the two Millennium Simulations after scaling to a Planck cosmology. In this model, massive galaxies are quenched by active galactic nucleus (AGN) feedback depending on both black hole and hot gas mass, and hence indirectly on stellar mass. In addition, satellite galaxies of any mass can be quenched by ram-pressure or tidal stripping of gas and through the suppression of gaseous infall. This combination of processes produces quenching efficiencies which depend on stellar mass, host halo mass, environment density, distance to group centre and group central galaxy properties in ways which agree qualitatively with observation. Some discrepancies remain in dense regions and close to group centres, where quenching still seems too efficient. In addition, although the mean stellar age of massive galaxies agrees with observation, the assumed AGN feedback model allows too much ongoing star formation at late times. The fact that both AGN feedback and environmental effects are stronger in higher density environments leads to a correlation between the quenching of central and satellite galaxies which roughly reproduces observed conformity trends inside haloes.

Plate Tectonics on Earth-like Planets: Implications for Habitability

NASA Astrophysics Data System (ADS)

Noack, L.; Breuer, D.

2011-12-01

Plate tectonics has been suggested to be essential for life (see e.g. [1]) due to the replenishment of nutrients and its role in the stabilization of the atmosphere temperature through the carbon-silicate cycle. Whether plate tectonics can prevail on a planet should depend on several factors, e.g. planetary mass, age of the planet, water content (at the surface and in the interior), surface temperature, mantle rheology, density variations in the mantle due to partial melting, and life itself by promoting erosion processes and perhaps even the production of continental rock [2]. In the present study, we have investigated how planetary mass, internal heating, surface temperature and water content in the mantle would factor for the probability of plate tectonics to occur on a planet. We allow the viscosity to be a function of pressure [3], an effect mostly neglected in previous discussions of plate tectonics on exoplanets [4, 5]. With the pressure-dependence of viscosity allowed for, the lower mantle may become too viscous in massive planets for convection to occur. When varying the planetary mass between 0.1 and 10 Earth masses, we find a maximum for the likelihood of plate tectonics to occur for planetary masses around a few Earth masses. For these masses the convective stresses acting at the base of the lithosphere are strongest and may become larger than the lithosphere yield strength. The optimum planetary mass varies slightly depending on the parameter values used (e.g. wet or dry rheology; initial mantle temperature). However, the peak in likelihood of plate tectonics remains roughly in the range of one to five Earth masses for reasonable parameter choices. Internal heating has a similar effect on the occurrence of plate tectonics as the planetary mass, i.e. there is a peak in the probability of plate tectonics depending on the internal heating rate. This result suggests that a planet may evolve as a consequence of radioactive decay into and out of the plate tectonics regime. References [1] Parnell, J. (2004): Plate tectonics, surface mineralogy, and the early evolution of life. Int. J. Astrobio. 3(2): 131-137. [2] Rosing, M.T.; D.K. Bird, N.H. Sleep, W. Glassley, and F. Albar (2006): The rise of continents - An essay on the geologic consequences of photosynthesis. Palaeogeography, Palaeoclimatology, Palaeoecology 232 (2006) 99-11. [3] Stamenkovic, V.; D. Breuer and T. Spohn (2011): Thermal and transport properties of mantle rock at high pressure: Applications to super-Earths. Submitted to Icarus. [4] Valencia, D., R.J. O'Connell and D.D. Sasselov (2007): Inevitability of plate tectonics on super-Earths. Astrophys. J. Let. 670(1): 45-48. [5] O'Neill, C. and A. Lenardic (2007). Geological consequences of super-sized Earths. GRL 34: 1-41.

The separate and combined effects of baryon physics and neutrino free streaming on large-scale structure

NASA Astrophysics Data System (ADS)

Mummery, Benjamin O.; McCarthy, Ian G.; Bird, Simeon; Schaye, Joop

2017-10-01

We use the cosmo-OWLS and bahamas suites of cosmological hydrodynamical simulations to explore the separate and combined effects of baryon physics (particularly feedback from active galactic nuclei, AGN) and free streaming of massive neutrinos on large-scale structure. We focus on five diagnostics: (I) the halo mass function, (II) halo mass density profiles, (III) the halo mass-concentration relation, (IV) the clustering of haloes and (v) the clustering of matter, and we explore the extent to which the effects of baryon physics and neutrino free streaming can be treated independently. Consistent with previous studies, we find that both AGN feedback and neutrino free streaming suppress the total matter power spectrum, although their scale and redshift dependences differ significantly. The inclusion of AGN feedback can significantly reduce the masses of groups and clusters, and increase their scale radii. These effects lead to a decrease in the amplitude of the mass-concentration relation and an increase in the halo autocorrelation function at fixed mass. Neutrinos also lower the masses of groups and clusters while having no significant effect on the shape of their density profiles (thus also affecting the mass-concentration relation and halo clustering in a qualitatively similar way to feedback). We show that, with only a small number of exceptions, the combined effects of baryon physics and neutrino free streaming on all five diagnostics can be estimated to typically better than a few per cent accuracy by treating these processes independently (I.e. by multiplying their separate effects).

The Effect of Body Mass on Outdoor Adult Human Decomposition.

PubMed

Roberts, Lindsey G; Spencer, Jessica R; Dabbs, Gretchen R

2017-09-01

Forensic taphonomy explores factors impacting human decomposition. This study investigated the effect of body mass on the rate and pattern of adult human decomposition. Nine males and three females aged 49-95 years ranging in mass from 73 to 159 kg who were donated to the Complex for Forensic Anthropology Research between December 2012 and September 2015 were included in this study. Kelvin accumulated degree days (KADD) were used to assess the thermal energy required for subjects to reach several total body score (TBS) thresholds: early decomposition (TBS ≥6.0), TBS ≥12.5, advanced decomposition (TBS ≥19.0), TBS ≥23.0, and skeletonization (TBS ≥27.0). Results indicate no significant correlation between body mass and KADD at any TBS threshold. Body mass accounted for up to 24.0% of variation in decomposition rate depending on stage, and minor differences in decomposition pattern were observed. Body mass likely has a minimal impact on postmortem interval estimation. © 2017 American Academy of Forensic Sciences.

Neutrino mass hierarchy and three-flavor spectral splits of supernova neutrinos

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

Dasgupta, Basudeb; Mirizzi, Alessandro; Tomas, Ricard

2010-05-01

It was recently realized that three-flavor effects could peculiarly modify the development of spectral splits induced by collective oscillations, for supernova neutrinos emitted during the cooling phase of a protoneutron star. We systematically explore this case, explaining how the impact of these three-flavor effects depends on the ordering of the neutrino masses. In inverted mass hierarchy, the solar mass splitting gives rise to instabilities in regions of the (anti)neutrino energy spectra that were otherwise stable under the leading two-flavor evolution governed by the atmospheric mass splitting and by the 1-3 mixing angle. As a consequence, the high-energy spectral splits foundmore » in the electron (anti)neutrino spectra disappear, and are transferred to other flavors. Imperfect adiabaticity leads to smearing of spectral swap features. In normal mass hierarchy, the three-flavor and the two-flavor instabilities act in the same region of the neutrino energy spectrum, leading to only minor departures from the two-flavor treatment.« less

The Pan-STARRS1 medium-deep survey: The role of galaxy group environment in the star formation rate versus stellar mass relation and quiescent fraction out to z ∼ 0.8

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

Lin, Lihwai; Chen, Chin-Wei; Coupon, Jean

2014-02-10

Using a large optically selected sample of field and group galaxies drawn from the Pan-STARRS1 Medium-Deep Survey (PS1/MDS), we present a detailed analysis of the specific star formation rate (SSFR)—stellar mass (M {sub *}) relation, as well as the quiescent fraction versus M {sub *} relation in different environments. While both the SSFR and the quiescent fraction depend strongly on stellar mass, the environment also plays an important role. Using this large galaxy sample, we confirm that the fraction of quiescent galaxies is strongly dependent on environment at a fixed stellar mass, but that the amplitude and the slope ofmore » the star-forming sequence is similar between the field and groups: in other words, the SSFR-density relation at a fixed stellar mass is primarily driven by the change in the star-forming and quiescent fractions between different environments rather than a global suppression in the star formation rate for the star-forming population. However, when we restrict our sample to the cluster-scale environments (M > 10{sup 14} M {sub ☉}), we find a global reduction in the SSFR of the star-forming sequence of 17% at 4σ confidence as opposed to its field counterpart. After removing the stellar mass dependence of the quiescent fraction seen in field galaxies, the excess in the quiescent fraction due to the environment quenching in groups and clusters is found to increase with stellar mass, although deeper and larger data from the full PS1/MDS will be required to draw firm conclusions. We argue that these results are in favor of galaxy mergers to be the primary environment quenching mechanism operating in galaxy groups whereas strangulation is able to reproduce the observed trend in the environment quenching efficiency and stellar mass relation seen in clusters. Our results also suggest that the relative importance between mass quenching and environment quenching depends on stellar mass—the mass quenching plays a dominant role in producing quiescent galaxies for more massive galaxies, while less massive galaxies are quenched mostly through the environmental effect, with the transition mass around 1-2 × 10{sup 10} M {sub ☉} in the group/cluster environment.« less

Effects of high-intensity exercise and protein supplement on muscle mass in ADL dependent older people with and without malnutrition: a randomized controlled trial.

PubMed

Carlsson, M; Littbrand, H; Gustafson, Y; Lundin-Olsson, L; Lindelöf, N; Rosendahl, E; Håglin, L

2011-08-01

Loss of muscle mass is common among old people living in institutions but trials that evaluate interventions aimed at increasing the muscle mass are lacking. Objective, participants and intervention: This randomized controlled trial was performed to evaluate the effect of a high-intensity functional exercise program and a timed protein-enriched drink on muscle mass in 177 people aged 65 to 99 with severe physical or cognitive impairments, and living in residential care facilities. Three-month high-intensity exercise was compared with a control activity and a protein-enriched drink was compared with a placebo drink. A bioelectrical impedance spectrometer (BIS) was used in the evaluation. The amount of muscle mass and body weight (BW) were followed-up at three and six months and analyzed in a 2 x 2 factorial ANCOVA, using the intention to treat principle, and controlling for baseline values. At 3-month follow-up there were no differences in muscle mass and BW between the exercise and the control group or between the protein and the placebo group. No interaction effects were seen between the exercise and nutritional intervention. Long-term negative effects on muscle mass and BW was seen in the exercise group at the 6-month follow-up. A three month high-intensity functional exercise program did not increase the amount of muscle mass and an intake of a protein-enriched drink immediately after the exercise did not induce any additional effect on muscle mass. There were negative long-term effects on muscle mass and BW, indicating that it is probably necessary to compensate for an increased energy demand when offering a high-intensity exercise program.

Computing Device Applications of Group IV Nanoparticle Spectroscopy

DTIC Science & Technology

2013-04-01

dependent on interband wavefunction symmetry. Second is the surface plasmon polariton (SPP) scattering lifetime. The SPP lifetime has two components...silicon nanoparticles for several minutes, then removed and allowed to air dry. The surface was then imaged using a scanning tunneling microscope. On...nominal q-dot boundary. This juxtaposition depends on particle effective masses and band curvatures.) SPP excitations require sufficient local charge

Quantitative proteomic analysis reveals a simple strategy of global resource allocation in bacteria

PubMed Central

Hui, Sheng; Silverman, Josh M; Chen, Stephen S; Erickson, David W; Basan, Markus; Wang, Jilong; Hwa, Terence; Williamson, James R

2015-01-01

A central aim of cell biology was to understand the strategy of gene expression in response to the environment. Here, we study gene expression response to metabolic challenges in exponentially growing Escherichia coli using mass spectrometry. Despite enormous complexity in the details of the underlying regulatory network, we find that the proteome partitions into several coarse-grained sectors, with each sector's total mass abundance exhibiting positive or negative linear relations with the growth rate. The growth rate-dependent components of the proteome fractions comprise about half of the proteome by mass, and their mutual dependencies can be characterized by a simple flux model involving only two effective parameters. The success and apparent generality of this model arises from tight coordination between proteome partition and metabolism, suggesting a principle for resource allocation in proteome economy of the cell. This strategy of global gene regulation should serve as a basis for future studies on gene expression and constructing synthetic biological circuits. Coarse graining may be an effective approach to derive predictive phenomenological models for other ‘omics’ studies. PMID:25678603

Mass-Related Dynamical Barriers in Triatomic Reactions

NASA Astrophysics Data System (ADS)

Yanao, T.; Koon, W. S.; Marsden, J. E.

2006-06-01

A methodology is given to determine the effect of different mass distributions for triatomic reactions using the geometry of shape space. Atomic masses are incorporated into the non-Euclidean shape space metric after the separation of rotations. Using the equations of motion in this non-Euclidean shape space, an averaged field of velocity-dependent fictitious forces is determined. This force field, as opposed to the force arising from the potential, dominates branching ratios of isomerization dynamics of a triatomic molecule. This methodology may be useful for qualitative prediction of branching ratios in general triatomic reactions.

Two-body contributions to the effective mass in nuclear effective interactions

NASA Astrophysics Data System (ADS)

Davesne, D.; Navarro, J.; Meyer, J.; Bennaceur, K.; Pastore, A.

2018-04-01

Starting from general expressions of well-chosen symmetric nuclear matter quantities derived for both zero- and finite-range effective theories, we derive some universal relations between them. We first show that, independently of the range, the two-body contribution is enough to describe correctly the saturation mechanism but gives an effective mass value around m*/m ≃0.4 when the other properties of the saturation point are set near their generally accepted values. Then, we show that a more elaborated interaction (for instance, an effective two-body density-dependent term on top of the pure two-body term) is needed to reach the accepted value m*/m ≃0.7 -0.8 .

Tidal Deformability from GW170817 as a Direct Probe of the Neutron Star Radius

NASA Astrophysics Data System (ADS)

Raithel, Carolyn A.; Özel, Feryal; Psaltis, Dimitrios

2018-04-01

Gravitational waves from the coalescence of two neutron stars were recently detected for the first time by the LIGO–Virgo Collaboration, in event GW170817. This detection placed an upper limit on the effective tidal deformability of the two neutron stars and tightly constrained the chirp mass of the system. We report here on a new simplification that arises in the effective tidal deformability of the binary, when the chirp mass is specified. We find that, in this case, the effective tidal deformability of the binary is surprisingly independent of the component masses of the individual neutron stars, and instead depends primarily on the ratio of the chirp mass to the neutron star radius. Thus, a measurement of the effective tidal deformability can be used to directly measure the neutron star radius. We find that the upper limit on the effective tidal deformability from GW170817 implies that the radius cannot be larger than ∼13 km, at the 90% level, independent of the assumed masses for the component stars. The result can be applied generally, to probe the stellar radii in any neutron star–neutron star merger with a measured chirp mass. The approximate mass independence disappears for neutron star–black hole mergers. Finally, we discuss a Bayesian inference of the equation of state that uses the measured chirp mass and tidal deformability from GW170817 combined with nuclear and astrophysical priors and discuss possible statistical biases in this inference.

MODEL-FREE MULTI-PROBE LENSING RECONSTRUCTION OF CLUSTER MASS PROFILES

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

Umetsu, Keiichi

2013-05-20

Lens magnification by galaxy clusters induces characteristic spatial variations in the number counts of background sources, amplifying their observed fluxes and expanding the area of sky, the net effect of which, known as magnification bias, depends on the intrinsic faint-end slope of the source luminosity function. The bias is strongly negative for red galaxies, dominated by the geometric area distortion, whereas it is mildly positive for blue galaxies, enhancing the blue counts toward the cluster center. We generalize the Bayesian approach of Umetsu et al. for reconstructing projected cluster mass profiles, by incorporating multiple populations of background sources for magnification-biasmore » measurements and combining them with complementary lens-distortion measurements, effectively breaking the mass-sheet degeneracy and improving the statistical precision of cluster mass measurements. The approach can be further extended to include strong-lensing projected mass estimates, thus allowing for non-parametric absolute mass determinations in both the weak and strong regimes. We apply this method to our recent CLASH lensing measurements of MACS J1206.2-0847, and demonstrate how combining multi-probe lensing constraints can improve the reconstruction of cluster mass profiles. This method will also be useful for a stacked lensing analysis, combining all lensing-related effects in the cluster regime, for a definitive determination of the averaged mass profile.« less

Effect of operating temperature on styrene mass transfer characteristics in a biotrickling filter.

PubMed

Parnian, Parham; Zamir, Seyed Morteza; Shojaosadati, Seyed Abbas

2017-05-01

To study the effect of operating temperature on styrene mass transfer from gas to liquid phase in biotrickling filters (BTFs), overall mass transfer coefficient (K L a) was calculated through fitting test data to a general mass balance model under abiotic conditions. Styrene was used as the volatile organic compound and the BTF was packed with a mixture of pall rings and pumice. Operating temperature was set at 30°C and 50°C for mesophilic and thermophilic conditions, respectively. K L a values increased from 54 to 70 h -1 at 30°C and from 60 to 90 h -1 at 50°C, respectively, depending on the countercurrent gas to liquid flow ratio that varied in the range of 7.5-32. Evaluation of styrene mass transfer capacity (MTC) showed that liquid-phase mass transfer resistance decreased as the flow ratio increased at constant temperature. MTC also decreased with an increase in operating temperature. Both gas-liquid partition coefficient and K L a increased with increasing temperature; however the effect on gas-liquid partition coefficient was more significant and served to increase mass transfer limitations. Thermophilic biofiltration on the one hand increases mass transfer limitations, but on the other hand may enhance the biodegradation rate in favor of enhancing BTFs' performance.

Relations between heavy-light meson and quark masses

NASA Astrophysics Data System (ADS)

Brambilla, N.; Komijani, J.; Kronfeld, A. S.; Vairo, A.; Tumqcd Collaboration

2018-02-01

The study of heavy-light meson masses should provide a way to determine renormalized quark masses and other properties of heavy-light mesons. In the context of lattice QCD, for example, it is possible to calculate hadronic quantities for arbitrary values of the quark masses. In this paper, we address two aspects relating heavy-light meson masses to the quark masses. First, we introduce a definition of the renormalized quark mass that is free of both scale dependence and renormalon ambiguities, and discuss its relation to more familiar definitions of the quark mass. We then show how this definition enters a merger of the descriptions of heavy-light masses in heavy-quark effective theory and in chiral perturbation theory (χ PT ). For practical implementations of this merger, we extend the one-loop χ PT corrections to lattice gauge theory with heavy-light mesons composed of staggered fermions for both quarks. Putting everything together, we obtain a practical formula to describe all-staggered heavy-light meson masses in terms of quark masses as well as some lattice artifacts related to staggered fermions. In a companion paper, we use this function to analyze lattice-QCD data and extract quark masses and some matrix elements defined in heavy-quark effective theory.

Relations between heavy-light meson and quark masses

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

Brambilla, N.; Komijani, J.; Kronfeld, A. S.

Here, the study of heavy-light meson masses should provide a way to determine renormalized quark masses and other properties of heavy-light mesons. In the context of lattice QCD, for example, it is possible to calculate hadronic quantities for arbitrary values of the quark masses. In this paper, we address two aspects relating heavy-light meson masses to the quark masses. First, we introduce a definition of the renormalized quark mass that is free of both scale dependence and renormalon ambiguities, and discuss its relation to more familiar definitions of the quark mass. We then show how this definition enters a mergermore » of the descriptions of heavy-light masses in heavy-quark effective theory and in chiral perturbation theory (χPT). For practical implementations of this merger, we extend the one-loop χPT corrections to lattice gauge theory with heavy-light mesons composed of staggered fermions for both quarks. Putting everything together, we obtain a practical formula to describe all-staggered heavy-light meson masses in terms of quark masses as well as some lattice artifacts related to staggered fermions. In a companion paper, we use this function to analyze lattice-QCD data and extract quark masses and some matrix elements defined in heavy-quark effective theory.« less

Relations between heavy-light meson and quark masses

DOE PAGES

Brambilla, N.; Komijani, J.; Kronfeld, A. S.; ...

2018-02-07

Here, the study of heavy-light meson masses should provide a way to determine renormalized quark masses and other properties of heavy-light mesons. In the context of lattice QCD, for example, it is possible to calculate hadronic quantities for arbitrary values of the quark masses. In this paper, we address two aspects relating heavy-light meson masses to the quark masses. First, we introduce a definition of the renormalized quark mass that is free of both scale dependence and renormalon ambiguities, and discuss its relation to more familiar definitions of the quark mass. We then show how this definition enters a mergermore » of the descriptions of heavy-light masses in heavy-quark effective theory and in chiral perturbation theory (χPT). For practical implementations of this merger, we extend the one-loop χPT corrections to lattice gauge theory with heavy-light mesons composed of staggered fermions for both quarks. Putting everything together, we obtain a practical formula to describe all-staggered heavy-light meson masses in terms of quark masses as well as some lattice artifacts related to staggered fermions. In a companion paper, we use this function to analyze lattice-QCD data and extract quark masses and some matrix elements defined in heavy-quark effective theory.« less

Modeling Kicks from the Merger of Generic Black-hole Binaries

NASA Technical Reports Server (NTRS)

Baker, John G.; Boggs, William D.; Centrella, Joan; Kelly, Bernard J.; McWilliams, Sean T.; Miller, M. Coleman; vanMeter, James R.

2008-01-01

Recent numerical relativistic results demonstrate that the merger of comparable-mass spinning black holes has a maximum "recoil kick" of up to approx. 4000 km/s. However the scaling of these recoil velocities with mass ratio is poorly understood. We present new runs showing that the maximum possible kick parallel to the orbital axis does not scale as approx. eta(sup 2) (where eta is the symmetric mass ratio), as previously proposed, but is more consistent with approx. eta(sup 3). We discuss the effect of this dependence on galactic ejection scenarios and retention of intermediate-mass black holes in globular clusters. S

Local-duality QCD sum rules for strong isospin breaking in the decay constants of heavy-light mesons.

PubMed

Lucha, Wolfgang; Melikhov, Dmitri; Simula, Silvano

2018-01-01

We discuss the leptonic decay constants of heavy-light mesons by means of Borel QCD sum rules in the local-duality (LD) limit of infinitely large Borel mass parameter. In this limit, for an appropriate choice of the invariant structures in the QCD correlation functions, all vacuum-condensate contributions vanish and all nonperturbative effects are contained in only one quantity, the effective threshold. We study properties of the LD effective thresholds in the limits of large heavy-quark mass [Formula: see text] and small light-quark mass [Formula: see text]. In the heavy-quark limit, we clarify the role played by the radiative corrections in the effective threshold for reproducing the pQCD expansion of the decay constants of pseudoscalar and vector mesons. We show that the dependence of the meson decay constants on [Formula: see text] arises predominantly (at the level of 70-80%) from the calculable [Formula: see text]-dependence of the perturbative spectral densities. Making use of the lattice QCD results for the decay constants of nonstrange and strange pseudoscalar and vector heavy mesons, we obtain solid predictions for the decay constants of heavy-light mesons as functions of [Formula: see text] in the range from a few to 100 MeV and evaluate the corresponding strong isospin-breaking effects: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text].

Evaluation of Mass Filtered, Time Dilated, Time-of-Flight Mass Spectrometry

DTIC Science & Technology

2010-01-01

Figure 4.4: Mass resolution dependence on field for selected actinides and surrogates...45 Figure 4.7: Mass resolution dependence on field for selected actinides and actinide surrogates, modeled with no initial...system. A somewhat better mass resolution would need to be achieved in order to separate hydride molecules in the actinide region. However, the

Mass Dependency of Isotope Fractionation of Gases Under Thermal Gradient and Its Possible Implications for Planetary Atmosphere Escaping Process

NASA Technical Reports Server (NTRS)

Sun, Tao; Niles, Paul; Bao, Huiming; Socki, Richard

2014-01-01

Physical processes that unmix elements/isotopes of gas molecules involve phase changes, diffusion (chemical or thermal), effusion and gravitational settling. Some of those play significant roles for the evolution of chemical and isotopic compositions of gases in planetary bodies which lead to better understanding of surface paleoclimatic conditions, e.g. gas bubbles in Antarctic ice, and planetary evolution, e.g. the solar-wind erosion induced gas escaping from exosphere on terrestrial planets.. A mass dependent relationship is always expected for the kinetic isotope fractionations during these simple physical processes, according to the kinetic theory of gases by Chapman, Enskog and others [3-5]. For O-bearing (O16, -O17, -O18) molecules the alpha O-17/ alpha O-18 is expected at 0.5 to 0.515, and for S-bearing (S32,-S33. -S34, -S36) molecules, the alpha S-33/ alpha S-34 is expected at 0.5 to 0.508, where alpha is the isotope fractionation factor associated with unmixing processes. Thus, one isotope pair is generally proxied to yield all the information for the physical history of the gases. However, we recently] reported the violation of mass law for isotope fractionation among isotope pairs of multiple isotope system during gas diffusion or convection under thermal gradient (Thermal Gradient Induced Non-Mass Dependent effect, TGI-NMD). The mechanism(s) that is responsible to such striking observation remains unanswered. In our past studies, we investigated polyatomic molecules, O2 and SF6, and we suggested that nuclear spin effect could be responsible to the observed NMD effect in a way of changing diffusion coefficients of certain molecules, owing to the fact of negligible delta S-36 anomaly for SF6.. On the other hand, our results also showed that for both diffusion and convection under thermal gradient, this NMD effect is increased by lower gas pressure, bigger temperature gradient and lower average temperature, which indicate that the nuclear spin effect may not be the significant contributor as the energies involved in the hyperfine effect are much smaller than those with molecular collisions, especially under convective conditions.

Effects of winter temperatures on gypsy moth egg masses in the Great Lakes region of the United States.

Treesearch

J.A. Andresen; D.G. McCullough; B.E. Potter; C.N. Koller; L.S. Bauer; C. W. Ramm

2001-01-01

Accurate prediction of winter survival of gypsy moth (Lymantria dispar L.) eggs and phenology of egg hatch in spring are strongly dependent on temperature and are critical aspects of gypsy moth management programs. We monitored internal temperatures of egg masses at three heights aboveground level and at the four cardinal aspects on oak tree stems at two different...

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

Grenon, Cedric; Lake, Kayll

We generalize the Swiss-cheese cosmologies so as to include nonzero linear momenta of the associated boundary surfaces. The evolution of mass scales in these generalized cosmologies is studied for a variety of models for the background without having to specify any details within the local inhomogeneities. We find that the final effective gravitational mass and size of the evolving inhomogeneities depends on their linear momenta but these properties are essentially unaffected by the details of the background model.

The dependence of galaxy clustering on tidal environment in the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Paranjape, Aseem; Hahn, Oliver; Sheth, Ravi K.

2018-06-01

The influence of the Cosmic Web on galaxy formation and evolution is of great observational and theoretical interest. We investigate whether the Cosmic Web leaves an imprint in the spatial clustering of galaxies in the Sloan Digital Sky Survey (SDSS), using the group catalogue of Yang et al. and tidal field estimates at ˜2 h-1 Mpc scales from the mass-tides-velocity data set of Wang et al. We use the tidal anisotropy α (Paranjape et al.) to characterize the tidal environment of groups, and measure the redshift-space 2-point correlation function (2pcf) of group positions and the luminosity- and colour-dependent clustering of group galaxies using samples segregated by α. We find that all the 2pcf measurements depend strongly on α, with factors of ˜20 between the large-scale 2pcf of objects in the most and least isotropic environments. To test whether these strong trends imply `beyond halo mass' effects for galaxy evolution, we compare our results with corresponding 2pcf measurements in mock catalogues constructed using a halo occupation distribution that uses only halo mass as an input. We find that this prescription qualitatively reproduces all observed trends, and also quantitatively matches many of the observed results. Although there are some statistically significant differences between our `halo mass only' mocks and the data - in the most and least isotropic environments - which deserve further investigation, our results suggest that if the tidal environment induces additional effects on galaxy properties other than those inherited from their host haloes, then these must be weak.

A possible explanation of the parallel tracks in kilohertz quasi-periodic oscillations from low-mass-X-ray binaries

NASA Astrophysics Data System (ADS)

Shi, Chang-Sheng; Zhang, Shuang-Nan; Li, Xiang-Dong

2018-05-01

We recalculate the modes of the magnetohydrodynamics (MHD) waves in the MHD model (Shi, Zhang & Li 2014) of the kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low mass X-ray binaries (NS-LMXBs), in which the compressed magnetosphere is considered. A method on point-by-point scanning for every parameter of a normal LMXBs is proposed to determine the wave number in a NS-LMXB. Then dependence of the twin kHz QPO frequencies on accretion rates (\\dot{M}) is obtained with the wave number and magnetic field (B*) determined by our method. Based on the MHD model, a new explanation of the parallel tracks, i.e. the slowly varying effective magnetic field leads to the shift of parallel tracks in a source, is presented. In this study, we obtain a simple power-law relation between the kHz QPO frequencies and \\dot{M}/B_{\\ast }^2 in those sources. Finally, we study the dependence of kHz quasi-periodic oscillation frequencies on the spin, mass and radius of a neutron star. We find that the effective magnetic field, the spin, mass and radius of a neutron star lead to the parallel tracks in different sources.

The stellar metallicity gradients in galaxy discs in a cosmological scenario

NASA Astrophysics Data System (ADS)

Tissera, Patricia B.; Machado, Rubens E. G.; Sanchez-Blazquez, Patricia; Pedrosa, Susana E.; Sánchez, Sebastián F.; Snaith, Owain; Vilchez, Jose

2016-08-01

Context. The stellar metallicity gradients of disc galaxies provide information on disc assembly, star formation processes, and chemical evolution. They also might store information on dynamical processes that could affect the distribution of chemical elements in the gas phase and the stellar components. Understanding their joint effects within a hierarchical clustering scenario is of paramount importance. Aims: We studied the stellar metallicity gradients of simulated discs in a cosmological simulation. We explored the dependence of the stellar metallicity gradients on stellar age and on the size and mass of the stellar discs. Methods: We used a catalogue of galaxies with disc components selected from a cosmological hydrodynamical simulation performed including a physically motivated supernova feedback and chemical evolution. Disc components were defined based on angular momentum and binding energy criteria. The metallicity profiles were estimated for stars with different ages. We confront our numerical findings with results from the Calar Alto Legacy Integral Field Area (CALIFA) Survey. Results: The simulated stellar discs are found to have metallicity profiles with slopes in global agreement with observations. Low stellar mass galaxies tend to have a larger variety of metallicity slopes. When normalized by the half-mass radius, the stellar metallicity gradients do not show any dependence and the dispersion increases significantly, regardless of the galaxy mass. Galaxies with stellar masses o f around 1010M⊙ show steeper negative metallicity gradients. The stellar metallicity gradients correlate with the half-mass radius. However, the correlation signal is not present when they are normalized by the half-mass radius. Stellar discs with positive age gradients are detected to have negative and positive metallicity gradients, depending on the relative importance of recent star formation activity in the central regions. Conclusions: Our results suggest that inside-out formation is the main process responsible for the metallicity and age profiles. The large dispersions in the metallicity gradients as a function of stellar mass could be ascribed to the effects of dynamical processes such as mergers, interactions and/or migration as well as those regulating the conversion of gas into stars. The fingerprints of the inside-out formation seem better preserved by the stellar metallicity gradients as a function of the half-mass radius.

Inertial effects in systems with magnetic charge

NASA Astrophysics Data System (ADS)

Armitage, N. P.

2018-05-01

This short article sets out some of the basic considerations that go into detecting the mass of quasiparticles with effective magnetic charge in solids. Effective magnetic charges may be appear as defects in particular magnetic textures. A magnetic monopole is a defect in this texture and as such these are not monopoles in the actual magnetic field B, but instead in the auxiliary field H. They may have particular properties expected for such quasiparticles such as magnetic charge and mass. This effective mass may-in principle-be detected in the same fashion that the mass is detected of other particles classically e.g. through their inertial response to time-dependent electromagnetic fields. I discuss this physics in the context of the "simple" case of the quantum spin ices, but aspects are broadly applicable. Based on extensions to Ryzkhin's model for classical spin ice, a hydrodynamic formulation can be given that takes into account inertial and entropic forces. Ultimately, a form for the susceptibility is obtained that is equivalent to the Rocard equation, which is a classic form used to account for inertial effects in the context of Debye-like relaxation.

Spin susceptibility and effective mass of two-dimensional electrons in MgxZn1-xO/ZnO heterostructures

NASA Astrophysics Data System (ADS)

Tsukazaki, A.; Ohtomo, A.; Kawasaki, M.; Akasaka, S.; Yuji, H.; Tamura, K.; Nakahara, K.; Tanabe, T.; Kamisawa, A.; Gokmen, T.; Shabani, J.; Shayegan, M.

2008-12-01

We report measurements of the spin susceptibility and the electron effective mass for two-dimensional electrons confined at the interfaces of MgxZn1-xO/ZnO single heterostructures ( x=0.05 , 0.08, and 0.11), grown by molecular-beam epitaxy on (0001) ZnO substrates. By tuning the built-in polarization through control of the barrier composition, the electron density was systematically varied in the range of 5.6×1011-1.6×1012cm-2 , corresponding to a range of 3.1≤rs≤5.2 , where rs is the average electron spacing measured in units of the effective Bohr radius. We used the coincidence technique, where crossings of the spin-split Landau levels occur at critical tilt angles of magnetic field, to evaluate the spin susceptibility. In addition, we determined the effective mass from the temperature dependence of the Shubnikov-de Haas oscillations measured at the coincidence conditions. The susceptibility and the effective mass both gradually increase with decreasing electron density, reflecting the role of electron-electron interaction.

Bile acids: analysis in biological fluids and tissues

PubMed Central

Griffiths, William J.; Sjövall, Jan

2010-01-01

The formation of bile acids/bile alcohols is of major importance for the maintenance of cholesterol homeostasis. Besides their functions in lipid absorption, bile acids/bile alcohols are regulatory molecules for a number of metabolic processes. Their effects are structure-dependent, and numerous metabolic conversions result in a complex mixture of biologically active and inactive forms. Advanced methods are required to characterize and quantify individual bile acids in these mixtures. A combination of such analyses with analyses of the proteome will be required for a better understanding of mechanisms of action and nature of endogenous ligands. Mass spectrometry is the basic detection technique for effluents from chromatographic columns. Capillary liquid chromatography-mass spectrometry with electrospray ionization provides the highest sensitivity in metabolome analysis. Classical gas chromatography-mass spectrometry is less sensitive but offers extensive structure-dependent fragmentation increasing the specificity in analyses of isobaric isomers of unconjugated bile acids. Depending on the nature of the bile acid/bile alcohol mixture and the range of concentration of individuals, different sample preparation sequences, from simple extractions to group separations and derivatizations, are applicable. We review the methods currently available for the analysis of bile acids in biological fluids and tissues, with emphasis on the combination of liquid and gas phase chromatography with mass spectrometry. PMID:20008121

The Influence of Planetary Mass on the Dynamical Lifetime of Planetary Systems

NASA Technical Reports Server (NTRS)

Lissauer, J. J.; Duncan, M. J.; Young, Richard E. (Technical Monitor)

1997-01-01

Recent numerical and analytic studies of planetary orbits have demonstrated the importance of resonances and chaos in destabilizing planetary systems. Newton's "clockwork" description of regular, predictable planetary orbits has been replaced by a view in which many systems can have long but finite lifetimes. This new knowledge has altered our perceptions of the later stages of planetary growth and of the stability of planetary systems. Stability criteria are inexact and time dependent. Most previous studies have focused on the effects in initial planetary orbits on the stability of the system. We are conducting an investigation which focuses on the dependence of stability criteria on planetary mass. Synthetic systems are created by increasing the masses of the planets in our Solar System or of the moons of a particular planet; these systems are then integrated until orbit crossing occurs. We have found that over some ranges, the time until orbit crossing varies to a good approximation as a power clothe factor by which the masses of the secondaries arc increased; some scatter occurs as a consequence of vie chaotic nature of orbital evolution. The slope of this power law varies substantially from system to system, and for moons it is mildly dependent on the inclusion of the planet's quadrupole moment in the gravitational potential.

Nuclear Mass Predictions within the Skyrme HFB Theory

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

Samyn, M.; Goriely, S.; Pearson, J.M.

To increase the reliability of predictions of highly neutron-rich nuclear masses we systematically analyze the sensitivity of Hartree-Fock-Bogoliubov (HFB) mass formulae to various physical inputs, such as a density dependence of the pairing interaction, a low effective mass, the particle-number projection, the symmetry energy, ... We typically use a 10-parameter Skyrme force and a 4-parameter {delta}-function pairing force. The 14 degrees of freedom are adjusted to the masses of all measured nuclei with N,Z {>=} 8 given in the 2001 and 2003 Audi et al. compilations. The masses of light and proton-rich nuclei are corrected by a 4-parameter phenomenological Wignermore » term. With more than ten such parameter sets complete mass tables are constructed, going from one drip line to the other, up to Z = 120.« less

Kinetics of gravity-driven slug flow in partially wettable capillaries of varying cross section

NASA Astrophysics Data System (ADS)

Nissan, Alon; Wang, Qiuling; Wallach, Rony

2016-11-01

A mathematical model for slug (finite liquid volume) motion in not-fully-wettable capillary tubes with sinusoidally varying cross-sectional areas was developed. The model, based on the Navier-Stokes equation, accounts for the full viscous terms due to nonuniform geometry, the inertial term, the slug's front and rear meniscus hysteresis effect, and dependence of contact angle on flow velocity (dynamic contact angle). The model includes a velocity-dependent film that is left behind the advancing slug, reducing its mass. The model was successfully verified experimentally by recording slug movement in uniform and sinusoidal capillary tubes with a gray-scale high-speed camera. Simulation showed that tube nonuniformity has a substantial effect on slug flow pattern: in a uniform tube it is monotonic and depends mainly on the slug's momentary mass/length; an undulating tube radius results in nonmonotonic flow characteristics. The static nonzero contact angle varies locally in nonuniform tubes owing to the additional effect of wall slope. Moreover, the nonuniform cross-sectional area induces slug acceleration, deceleration, blockage, and metastable-equilibrium locations. Increasing contact angle further amplifies the geometry effect on slug propagation. The developed model provides a modified means of emulating slug flow in differently wettable porous media for intermittent inlet water supply (e.g., raindrops on the soil surface).

Effects of subtle differences in ligand constitution and conformation in metallo-supramolecular self-assembled polygons.

PubMed

Brusilowskij, Boris; Dzyuba, Egor V; Troff, Ralf W; Schalley, Christoph A

2011-12-07

3,3'-Bis(pyridin-[n]-ylethynyl)biphenyl (n = 3, 4) and the corresponding 2,2'-bipyridines assemble with (dppp)Pt(II) triflate into metallo-supramolecular polygons. Depending on the position of the terminal pyridine N atoms, the assembly reaction leads to different equilibrium products. With the slow ligand exchange on Pt(II) complexes, the equilibrium is reached on a many-hour time-scale. During the assembly process, larger polygons form under kinetic control. This was confirmed by time-dependent (1)H and (31)P NMR spectroscopy in line with complementary ESI mass spectrometric experiments. The constitutional difference in the pyridine N-atom position is reflected in the tandem mass spectra of the complex ions. In addition, a highly specific fragmentation process of mass-selected M(3)L(3) ions was observed, which proceeds through a ring contraction yielding smaller M(2)L(2) ions.

On the study of rotational effects in mass asymmetric colliding nuclei at intermediate energies

NASA Astrophysics Data System (ADS)

Kaur, Kamaldeep; Kumar, Suneel

2018-05-01

The rotational dynamics has been studied for different mass asymmetric systems 49122In + 50126Sn, 48114Cs + 54134In, 40100Mo + 64148Gd, 3686Kr + 67162Ho, 3171Ga + 71177Lu, 2860Ni + 76188Os and 2450Cr + 78198 Pt for incident energies between 40 MeV/nucleon and 400 MeV/nucleon for impact parameter range 0.25 < b ˆ < 0.45 using isospin-dependent quantum molecular dynamics (IQMD) model. Our calculations reveal that the time evolutions of rotational observables for participant and spectator nuclear matter are different in mass asymmetric heavy ion reactions. Theoretical data of BUU model's azimuthal distributions for free protons have been compared successfully with IQMD model calculations. The rotational flow of free protons with increasing incident energies and elliptic flow (calculated from the fits of azimuthal distributions of free protons) dependence with energy has also been investigated.

Galaxy Cluster Mass Reconstruction Project – III. The impact of dynamical substructure on cluster mass estimates

DOE PAGES

Old, L.; Wojtak, R.; Pearce, F. R.; ...

2017-12-20

With the advent of wide-field cosmological surveys, we are approaching samples of hundreds of thousands of galaxy clusters. While such large numbers will help reduce statistical uncertainties, the control of systematics in cluster masses is crucial. Here we examine the effects of an important source of systematic uncertainty in galaxy-based cluster mass estimation techniques: the presence of significant dynamical substructure. Dynamical substructure manifests as dynamically distinct subgroups in phase-space, indicating an ‘unrelaxed’ state. This issue affects around a quarter of clusters in a generally selected sample. We employ a set of mock clusters whose masses have been measured homogeneously withmore » commonly used galaxy-based mass estimation techniques (kinematic, richness, caustic, radial methods). We use these to study how the relation between observationally estimated and true cluster mass depends on the presence of substructure, as identified by various popular diagnostics. We find that the scatter for an ensemble of clusters does not increase dramatically for clusters with dynamical substructure. However, we find a systematic bias for all methods, such that clusters with significant substructure have higher measured masses than their relaxed counterparts. This bias depends on cluster mass: the most massive clusters are largely unaffected by the presence of significant substructure, but masses are significantly overestimated for lower mass clusters, by ~ 10 percent at 10 14 and ≳ 20 percent for ≲ 10 13.5. Finally, the use of cluster samples with different levels of substructure can therefore bias certain cosmological parameters up to a level comparable to the typical uncertainties in current cosmological studies.« less

Galaxy Cluster Mass Reconstruction Project – III. The impact of dynamical substructure on cluster mass estimates

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

Old, L.; Wojtak, R.; Pearce, F. R.

With the advent of wide-field cosmological surveys, we are approaching samples of hundreds of thousands of galaxy clusters. While such large numbers will help reduce statistical uncertainties, the control of systematics in cluster masses is crucial. Here we examine the effects of an important source of systematic uncertainty in galaxy-based cluster mass estimation techniques: the presence of significant dynamical substructure. Dynamical substructure manifests as dynamically distinct subgroups in phase-space, indicating an ‘unrelaxed’ state. This issue affects around a quarter of clusters in a generally selected sample. We employ a set of mock clusters whose masses have been measured homogeneously withmore » commonly used galaxy-based mass estimation techniques (kinematic, richness, caustic, radial methods). We use these to study how the relation between observationally estimated and true cluster mass depends on the presence of substructure, as identified by various popular diagnostics. We find that the scatter for an ensemble of clusters does not increase dramatically for clusters with dynamical substructure. However, we find a systematic bias for all methods, such that clusters with significant substructure have higher measured masses than their relaxed counterparts. This bias depends on cluster mass: the most massive clusters are largely unaffected by the presence of significant substructure, but masses are significantly overestimated for lower mass clusters, by ~ 10 percent at 10 14 and ≳ 20 percent for ≲ 10 13.5. Finally, the use of cluster samples with different levels of substructure can therefore bias certain cosmological parameters up to a level comparable to the typical uncertainties in current cosmological studies.« less

PHIBSS: Unified Scaling Relations of Gas Depletion Time and Molecular Gas Fractions

NASA Astrophysics Data System (ADS)

Tacconi, L. J.; Genzel, R.; Saintonge, A.; Combes, F.; García-Burillo, S.; Neri, R.; Bolatto, A.; Contini, T.; Förster Schreiber, N. M.; Lilly, S.; Lutz, D.; Wuyts, S.; Accurso, G.; Boissier, J.; Boone, F.; Bouché, N.; Bournaud, F.; Burkert, A.; Carollo, M.; Cooper, M.; Cox, P.; Feruglio, C.; Freundlich, J.; Herrera-Camus, R.; Juneau, S.; Lippa, M.; Naab, T.; Renzini, A.; Salome, P.; Sternberg, A.; Tadaki, K.; Übler, H.; Walter, F.; Weiner, B.; Weiss, A.

2018-02-01

This paper provides an update of our previous scaling relations between galaxy-integrated molecular gas masses, stellar masses, and star formation rates (SFRs), in the framework of the star formation main sequence (MS), with the main goal of testing for possible systematic effects. For this purpose our new study combines three independent methods of determining molecular gas masses from CO line fluxes, far-infrared dust spectral energy distributions, and ∼1 mm dust photometry, in a large sample of 1444 star-forming galaxies between z = 0 and 4. The sample covers the stellar mass range log(M */M ⊙) = 9.0–11.8, and SFRs relative to that on the MS, δMS = SFR/SFR(MS), from 10‑1.3 to 102.2. Our most important finding is that all data sets, despite the different techniques and analysis methods used, follow the same scaling trends, once method-to-method zero-point offsets are minimized and uncertainties are properly taken into account. The molecular gas depletion time t depl, defined as the ratio of molecular gas mass to SFR, scales as (1 + z)‑0.6 × (δMS)‑0.44 and is only weakly dependent on stellar mass. The ratio of molecular to stellar mass μ gas depends on (1+z{)}2.5× {(δ {MS})}0.52× {({M}* )}-0.36, which tracks the evolution of the specific SFR. The redshift dependence of μ gas requires a curvature term, as may the mass dependences of t depl and μ gas. We find no or only weak correlations of t depl and μ gas with optical size R or surface density once one removes the above scalings, but we caution that optical sizes may not be appropriate for the high gas and dust columns at high z. Based on observations of an IRAM Legacy Program carried out with the NOEMA, operated by the Institute for Radio Astronomy in the Millimetre Range (IRAM), which is funded by a partnership of INSU/CNRS (France), MPG (Germany), and IGN (Spain).

The effects of mass and metallicity upon planetary nebula formation

NASA Astrophysics Data System (ADS)

Papp, K. A.; Purton, C. R.; Kwok, S.

1983-05-01

A parameterized function is constructed which describes the possible dependence of planetary nebula formation upon metal abundance and stellar mass. Data on galaxies in the Local Group compared with predictions made from the parameterized function indicate that heavy element abundance is the principal agent influencing the formation of planetary nebulae; stars which are rich in heavy elements are the progenitors of planetary nebulae. This analysis, when compared with the observations, argues for a modest degree of pre-enrichment in a few of the sample galaxies. The heavy element dependence of planetary nebula formation also accounts for the deficit of planetary nebulae in the nuclei of NGC 221 and NGC 224, and in the bulge of our Galaxy.

Estimating the HI gas fractions of galaxies in the local Universe

NASA Astrophysics Data System (ADS)

Zhang, Wei; Li, Cheng; Kauffmann, Guinevere; Zou, Hu; Catinella, Barbara; Shen, Shiyin; Guo, Qi; Chang, Ruixiang

2009-08-01

We use a sample of 800 galaxies with HI mass measurements from the HyperLeda catalogue and optical photometry from the fourth data release of the Sloan Digital Sky Survey (SDSS) to calibrate a new photometric estimator of the HI-to-stellar-mass ratio for nearby galaxies. Our estimator, which is motivated by the Kennicutt-Schmidt star formation law, is log10(GHI/S) = -1.73238(g - r) + 0.215182μi - 4.08451, where μi is the i-band surface brightness and g - r is the optical colour estimated from the g- and r-band Petrosian apparent magnitudes. This estimator has a scatter of σ = 0.31 dex in log (GHI/S), compared to σ ~ 0.4 dex for previous estimators that were based on colour alone. We investigate whether the residuals in our estimate of log (GHI/S) depend in a systematic way on a variety of different galaxy properties. We find no effect as a function of stellar mass or 4000 Å break strength, but there is a systematic effect as a function of the concentration index of the light. We then apply our estimator to a sample of 105 emission-line galaxies in the SDSS Data Release 4 (DR4) and derive an estimate of the HI mass function, which is in excellent agreement with recent results from HI blind surveys. Finally, we re-examine the well-known relation between gas-phase metallicity and stellar mass, and ask whether there is a dependence on HI-to-stellar-mass ratio, as predicted by chemical evolution models. We do find that gas-poor galaxies are more metal rich at fixed stellar mass. We compare our results with the semi-analytic models of De Lucia & Blaizot, which include supernova feedback, as well as the cosmological infall of gas.

The changing impact of snow conditions and refreezing on the mass balance of an idealized Svalbard glacier

NASA Astrophysics Data System (ADS)

Van Pelt, Ward; Pohjola, Veijo; Reijmer, Carleen

2016-11-01

Glacier surface melt and runoff depend strongly on seasonal and perennial snow (firn) conditions. Not only does the presence of snow and firn directly affect melt rates by reflecting solar radiation, it may also act as a buffer against mass loss by storing melt water in refrozen or liquid form. In Svalbard, ongoing and projected amplified climate change with respect to the global mean change has severe implications for the state of snow and firn and its impact on glacier mass loss. Model experiments with a coupled surface energy balance - firn model were done to investigate the surface mass balance and the changing role of snow and firn conditions for an idealized Svalbard glacier. A climate forcing for the past, present and future (1984-2104) is constructed, based on observational data from Svalbard Airport and a seasonally dependent projection scenario. Results illustrate ongoing and future firn degradation in response to an elevational retreat of the equilibrium line altitude (ELA) of 31 m decade-1. The temperate firn zone is found to retreat and expand, while cold ice in the ablation zone warms considerably. In response to pronounced winter warming and an associated increase in winter rainfall, the current prevalence of refreezing during the melt season gradually shifts to the winter season in a future climate. Sensitivity tests reveal that in a present and future climate the density and thermodynamic structure of Svalbard glaciers are heavily influenced by refreezing. Refreezing acts as a net buffer against mass loss. However, the net mass balance change after refreezing is substantially smaller than the amount of refreezing itself, which can be ascribed to melt-enhancing effects after refreezing, which partly offset the primary mass-retaining effect of refreezing.

The formation of protostellar disks. 2: Disks around intermediate-mass stars

NASA Technical Reports Server (NTRS)

Yorke, Harold W.; Bodenheimer, Peter; Laughlin, G.

1995-01-01

Hydrodynamical calculations of the evolution of a collapsing, rotating axisymmetric 10 solar masses molecular clump, including the effects of radiative acceleration but without magnetic fields, are represented. The initial cloud is assumed to be uniformly rotating, centrally condensed sphere with rho is proportional to r(exp -2). Several cases are considered, in which both the overall clump size and the total amount of angular momentum are varied. The calculations show how a warm, quasi-hydrostatic disk surrounding a central unresolved core of only a few solar masses forms and grows in size and mass. The disk is encased in two distinct accretion shock fronts, both of which are several scale heights above the equatorial plane. At the end of the calculation of our standard case, the central unresolved region is found to have a mass of 2.7 solar masses and a ratio of rotational to gravitational energy of approximately 0.45, sufficiently large to be unstable to nonaxisymmetric perturbations. In addition, the inner portions of the disk containing most of the mass are unstable according to the local Toomre criterion, implying that also in this region nonaxisymmetric perturbations will lead to rapid evolution. Under the assumption that gravitational torques would transport angular momentum out of this region, a central core of less than or approximately 8 solar masses with a stable disk of greater than or approximately = 2 solar masses should result. Frequency-dependent radiative transfer calculations of the standard case at selected ages show how the continuum spectrum of the structure depends on the disk's orientation and age and how the observed isophotal contours vary with wavelength. Because of the strong dependence on viewing angle, continuum spectra alone should not be used to estimate the evolutionary stage of development of these objects. Comparable results were obtained for the other cases considered.

New developments on size-dependent growth applied to the crystallization of sucrose

NASA Astrophysics Data System (ADS)

Martins, P. M.; Rocha, F.

2007-12-01

The effect of crystal size on the growth rate of sucrose (C 12H 22O 11) at 40 °C is investigated from a theoretical and an experimental point of view. Based on new perspectives resulting from the recently introduced spiral nucleation model [P.M. Martins, F. Rocha, Surf. Sci. 601 (2007) 3400], crystal growth rates are expressed in terms of mass deposition per time and crystal volume units. This alternative definition is demonstrated to be size-independent over the considered supersaturation range. The conventional overall growth rate expressed per surface area units is found to be linearly dependent on crystal size. The advantages of the "volumetric" growth rate concept are discussed. Sucrose dissolution rates were measured under reciprocal conditions of the growth experiments in order to investigate the two-way effect of crystal size on mass transfer rates and on the integration kinetics. Both effects are adequately described by combining a well-established diffusion-integration model and the spiral nucleation mechanism.

Mapping stellar content to dark matter haloes - III. Environmental dependence and conformity of galaxy colours

NASA Astrophysics Data System (ADS)

Zu, Ying; Mandelbaum, Rachel

2018-05-01

Recent studies suggest that the quenching properties of galaxies are correlated over several megaparsecs. The large-scale `galactic conformity' phenomenon around central galaxies has been regarded as a potential signature of `galaxy assembly bias' or `pre-heating', both of which interpret conformity as a result of direct environmental effects acting on galaxy formation. Building on the iHOD halo quenching framework developed in Zu and Mandelbaum, we discover that our fiducial halo mass quenching model, without any galaxy assembly bias, can successfully explain the overall environmental dependence and the conformity of galaxy colours in Sloan Digital Sky Survey, as measured by the mark correlation functions of galaxy colours and the red galaxy fractions around isolated primaries, respectively. Our fiducial iHOD halo quenching mock also correctly predicts the differences in the spatial clustering and galaxy-galaxy lensing signals between the more versus less red galaxy subsamples, split by the red-sequence ridge line at fixed stellar mass. Meanwhile, models that tie galaxy colours fully or partially to halo assembly bias have difficulties in matching all these observables simultaneously. Therefore, we demonstrate that the observed environmental dependence of galaxy colours can be naturally explained by the combination of (1) halo quenching and (2) the variation of halo mass function with environment - an indirect environmental effect mediated by two separate physical processes.

A study of environmental effects on galaxy spin using MaNGA data

NASA Astrophysics Data System (ADS)

Lee, Jong Chul; Hwang, Ho Seong; Chung, Haeun

2018-06-01

We investigate environmental effects on galaxy spin using the recent public data of Mapping Nearby Galaxies at APO (MaNGA) integral field spectroscopic survey containing ˜2800 galaxies. We measure the spin parameter of 1830 galaxies through the analysis of two-dimensional stellar kinematic maps within the effective radii, and obtain their large-scale (background mass density from 20 nearby galaxies) and small-scale (distance to and morphology of the nearest neighbour galaxy) environmental parameters for 1529 and 1767 galaxies, respectively. We first examine the mass dependence of galaxy spin, and find that the spin parameter of early-type galaxies decreases with stellar mass at log (M*/M⊙) ≳ 10, consistent with the results from previous studies. We then divide the galaxies into three subsamples using their stellar masses to minimize the mass effects on galaxy spin. The spin parameters of galaxies in each subsample do not change with background mass density, but do change with distance to and morphology of the nearest neighbour. In particular, the spin parameter of late-type galaxies decreases as early-type neighbours approach within the virial radius. These results suggest that the large-scale environments hardly affect the galaxy spin, but the small-scale environments such as hydrodynamic galaxy-galaxy interactions can play a substantial role in determining galaxy spin.

Bounds on an energy-dependent and observer-independent speed of light from violations of locality.

PubMed

Hossenfelder, Sabine

2010-04-09

We show that models with deformations of special relativity that have an energy-dependent speed of light have nonlocal effects. The requirement that the arising nonlocality is not in conflict with known particle physics allows us to derive strong bounds on deformations of special relativity and rule out a modification to first order in energy over the Planck mass.

Flow effects in a vertical CVD reactor

NASA Technical Reports Server (NTRS)

Young, G. W.; Hariharan, S. I.; Carnahan, R.

1992-01-01

A model is presented to simulate the non-Boussinesq flow in a vertical, two-dimensional, chemical vapor deposition reactor under atmospheric pressure. Temperature-dependent conductivity, mass diffusivity, viscosity models, and reactive species mass transfer to the substrate are incorporated. In the limits of small Mach number and small aspect ratio, asymptotic expressions for the flow, temperature, and species fields are developed. Soret diffusion effects are also investigated. Analytical solutions predict an inverse relationship between temperature field and concentration field due to Soret effects. This finding is consistent with numerical simulations, assisting in the understanding of the complex interactions amongst the flow, thermal, and species fields in a chemically reacting system.

Radiative acceleration in Schwarzschild space-times

NASA Astrophysics Data System (ADS)

Keane, A. J.; Barrett, R. K.; Simmons, J. F. L.

2001-03-01

We examine the radial motion of a material particle in the intense radiation field of a static spherically symmetric compact object with spherical emitting surface outside the Schwarzschild radius. This paper generalizes previous work which dealt with radial motion in the Thomson limit, where the radiation force is simply proportional to the radiative flux. In the general case the average time component of the 4-momentum transferred to the particle is not negligible compared with its rest mass. Consequently, we find that the frequency dependence of the radiation force owing to Compton scattering for highly energetic photons gives rise to an increase in the effective mass of the test particle. In this work we outline the effects of this frequency dependence and compare these with the results in the Thomson limit. We present the frequency dependent saturation velocity curves for a range of stellar luminosities and radiation frequencies and present the resulting phase-space diagrams corresponding to the radial test particle trajectories. In particular, the stable equilibrium points which exist in the Thomson limit are found to be absent in the general case.

The concentration dependence of the galaxy–halo connection: Modeling assembly bias with abundance matching

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

Lehmann, Benjamin V.; Mao, Yao -Yuan; Becker, Matthew R.

Empirical methods for connecting galaxies to their dark matter halos have become essential for interpreting measurements of the spatial statistics of galaxies. In this work, we present a novel approach for parameterizing the degree of concentration dependence in the abundance matching method. Furthermore, this new parameterization provides a smooth interpolation between two commonly used matching proxies: the peak halo mass and the peak halo maximal circular velocity. This parameterization controls the amount of dependence of galaxy luminosity on halo concentration at a fixed halo mass. Effectively this interpolation scheme enables abundance matching models to have adjustable assembly bias in the resulting galaxy catalogs. With the newmore » $$400\\,\\mathrm{Mpc}\\,{h}^{-1}$$ DarkSky Simulation, whose larger volume provides lower sample variance, we further show that low-redshift two-point clustering and satellite fraction measurements from SDSS can already provide a joint constraint on this concentration dependence and the scatter within the abundance matching framework.« less

The concentration dependence of the galaxy–halo connection: Modeling assembly bias with abundance matching

DOE PAGES

Lehmann, Benjamin V.; Mao, Yao -Yuan; Becker, Matthew R.; ...

2016-12-28

Empirical methods for connecting galaxies to their dark matter halos have become essential for interpreting measurements of the spatial statistics of galaxies. In this work, we present a novel approach for parameterizing the degree of concentration dependence in the abundance matching method. Furthermore, this new parameterization provides a smooth interpolation between two commonly used matching proxies: the peak halo mass and the peak halo maximal circular velocity. This parameterization controls the amount of dependence of galaxy luminosity on halo concentration at a fixed halo mass. Effectively this interpolation scheme enables abundance matching models to have adjustable assembly bias in the resulting galaxy catalogs. With the newmore » $$400\\,\\mathrm{Mpc}\\,{h}^{-1}$$ DarkSky Simulation, whose larger volume provides lower sample variance, we further show that low-redshift two-point clustering and satellite fraction measurements from SDSS can already provide a joint constraint on this concentration dependence and the scatter within the abundance matching framework.« less

Phonon-induced renormalization of the electron spectrum of biased bilayer graphene

NASA Astrophysics Data System (ADS)

Kryuchkov, S. V.; Kukhar, E. I.

2018-05-01

The effect of the electron-phonon interaction on the electron subsystem of the bilayer graphene has been investigated in the case when there is a potential bias between the graphene layers. The electron-phonon interaction has been shown to lead to increasing of the curvature of the lower dispersion branch of the conduction band of the bigraphene in the vicinity of the Dirac point. The latter corresponds to the decreasing of the absolute value of the electron effective mass. The corresponding correction to the effective mass has been calculated. Dependence of this correction on the bias has been investigated. Influence of such effect on the bigraphene conductivity is discussed.

Density functional theory and experimental study of the electronic structure and transport properties of La, V, Nb, and Ta doped SrTiO3

NASA Astrophysics Data System (ADS)

Baniecki, J. D.; Ishii, M.; Aso, H.; Kurihara, K.; Ricinschi, Dan

2013-01-01

The electronic structure and transport properties of donor doped SrTiO3 are studied using density functional theory with spin-orbit coupling and conductivity, Hall, and Seebeck effect measurements over a wide temperature range (100 K to 600 K). Split-off energies ΔSO are tunable through the dopant SO interaction strength and concentration varying from 28.1 meV for pure STO to 70.93 meV for SrTi0.5Nb0.5O3. At lower carrier concentrations and temperatures, SO coupling has a marked effect on both the filling dependence of the density-of-states mass as well as the temperature dependence of the Seebeck coefficient, with quantitative theoretical predictions based on DFT calculations that include the SO interaction in closer agreement to the experimental data. Moreover, the results suggest that the predictive power of the current theory is not unlimited, with less accuracy for the calculated S predicting the magnitude of the experimental S data at lower dopant concentrations than for degenerately doped systems. A concentration dependent mass enhancement of ˜2-5, relative to the density-of-states mass in the local density approximation, possibly due to the influence of electronic screening of the electron-phonon interaction, would bring the theoretical S in accord with the experimental S data. This additional carrier-dependent enhancement mechanism for S may give an additional degree of freedom in terms of designing new higher efficiency thermoelectric energy materials.

Modelling the effect of acoustic waves on the thermodynamics and kinetics of phase transformation in a solution: Including mass transportation

NASA Astrophysics Data System (ADS)

Haqshenas, S. R.; Ford, I. J.; Saffari, N.

2018-01-01

Effects of acoustic waves on a phase transformation in a metastable phase were investigated in our previous work [S. R. Haqshenas, I. J. Ford, and N. Saffari, "Modelling the effect of acoustic waves on nucleation," J. Chem. Phys. 145, 024315 (2016)]. We developed a non-equimolar dividing surface cluster model and employed it to determine the thermodynamics and kinetics of crystallisation induced by an acoustic field in a mass-conserved system. In the present work, we developed a master equation based on a hybrid Szilard-Fokker-Planck model, which accounts for mass transportation due to acoustic waves. This model can determine the kinetics of nucleation and the early stage of growth of clusters including the Ostwald ripening phenomenon. It was solved numerically to calculate the kinetics of an isothermal sonocrystallisation process in a system with mass transportation. The simulation results show that the effect of mass transportation for different excitations depends on the waveform as well as the imposed boundary conditions and tends to be noticeable in the case of shock waves. The derivations are generic and can be used with any acoustic source and waveform.

Modelling the effect of acoustic waves on the thermodynamics and kinetics of phase transformation in a solution: Including mass transportation.

PubMed

Haqshenas, S R; Ford, I J; Saffari, N

2018-01-14

Effects of acoustic waves on a phase transformation in a metastable phase were investigated in our previous work [S. R. Haqshenas, I. J. Ford, and N. Saffari, "Modelling the effect of acoustic waves on nucleation," J. Chem. Phys. 145, 024315 (2016)]. We developed a non-equimolar dividing surface cluster model and employed it to determine the thermodynamics and kinetics of crystallisation induced by an acoustic field in a mass-conserved system. In the present work, we developed a master equation based on a hybrid Szilard-Fokker-Planck model, which accounts for mass transportation due to acoustic waves. This model can determine the kinetics of nucleation and the early stage of growth of clusters including the Ostwald ripening phenomenon. It was solved numerically to calculate the kinetics of an isothermal sonocrystallisation process in a system with mass transportation. The simulation results show that the effect of mass transportation for different excitations depends on the waveform as well as the imposed boundary conditions and tends to be noticeable in the case of shock waves. The derivations are generic and can be used with any acoustic source and waveform.

Marangoni convection in Casson liquid flow due to an infinite disk with exponential space dependent heat source and cross-diffusion effects

NASA Astrophysics Data System (ADS)

Mahanthesh, B.; Gireesha, B. J.; Shashikumar, N. S.; Hayat, T.; Alsaedi, A.

2018-06-01

Present work aims to investigate the features of the exponential space dependent heat source (ESHS) and cross-diffusion effects in Marangoni convective heat mass transfer flow due to an infinite disk. Flow analysis is comprised with magnetohydrodynamics (MHD). The effects of Joule heating, viscous dissipation and solar radiation are also utilized. The thermal and solute field on the disk surface varies in a quadratic manner. The ordinary differential equations have been obtained by utilizing Von Kármán transformations. The resulting problem under consideration is solved numerically via Runge-Kutta-Fehlberg based shooting scheme. The effects of involved pertinent flow parameters are explored by graphical illustrations. Results point out that the ESHS effect dominates thermal dependent heat source effect on thermal boundary layer growth. The concentration and temperature distributions and their associated layer thicknesses are enhanced by Marangoni effect.

Neutron–proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon–nucleus scattering data within an isospin dependent optical model

DOE PAGES

Li, Xiao -Hua; Guo, Wen -Jun; Li, Bao -An; ...

2015-04-01

The neutron–proton effective mass splitting in asymmetric nucleonic matter of isospin asymmetry δ and normal density is found to be m* n-p≡(m* n – m* p)/m = (0.41 ± 0.15)δ from analyzing globally 1088 sets of reaction and angular differential cross sections of proton elastic scattering on 130 targets with beam energies from 0.783 MeV to 200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets with beam energies from 0.05 MeV to 200 MeV within an isospin dependent non-relativistic optical potential model. It sets a useful reference for testing model predictions on the momentum dependencemore » of the nucleon isovector potential necessary for understanding novel structures and reactions of rare isotopes.« less

Dynamic Jahn-Teller effect: Calculation of fine structure spectrum, isotope shift and Zeeman behavior at deep center Ni2+ in CdS

NASA Astrophysics Data System (ADS)

Schoepp, Juergen

The internal transition of the deep center Ni2+ in II to IV semiconductor cadmium sulfide is examined with reference to crystal field theory. An algorithm was developed for calculation, in a basis fitted to trigonal symmetry, of fine structure operator matrix which is made of the sum of operators from spin trajectory coupling, trigonal field and electron phonon coupling. The dependence of energy level on the mass was calculated in order to examine the isotropy effect at Ni2+ transition. The mass dependence of phonon energy was estimated in an atomic cluster by using a valence force model from Keating for elastic energy. The Zeeman behavior of Ni2+ transition was examined for magnetic fields; the Zeeman operator was added to the fine structure operator and the resulting matrix was diagonalized. It is noticed that calculations are quantitatively and qualitatively in agreement with experiments.

A Preliminary Study for Evaluating the Dose-Dependent Effect of d-Allulose for Fat Mass Reduction in Adult Humans: A Randomized, Double-Blind, Placebo-Controlled Trial.

PubMed

Han, Youngji; Kwon, Eun-Young; Yu, Mi Kyeong; Lee, Seon Jeong; Kim, Hye-Jin; Kim, Seong-Bo; Kim, Yang Hee; Choi, Myung-Sook

2018-01-31

d-allulose is a rare sugar with zero energy that can be consumed by obese/overweight individuals. Many studies have suggested that zero-calorie d-allulose has beneficial effects on obesity-related metabolism in mouse models, but only a few studies have been performed on human subjects. Therefore, we performed a preliminary study with 121 Korean subjects (aged 20-40 years, body mass index ≥ 23 kg/m²). A randomized controlled trial involving placebo control (sucralose, 0.012 g × 2 times/day), low d-allulose (d-allulose, 4 g × 2 times/day), and high d-allulose (d-allulose, 7 g × 2 times/day) groups was designed. Parameters for body composition, nutrient intake, computed tomography (CT) scan, and plasma lipid profiles were assessed. Body fat percentage and body fat mass were significantly decreased following d-allulose supplementation. The high d-allulose group revealed a significant decrease in not only body mass index (BMI), but also total abdominal and subcutaneous fat areas measured by CT scans compared to the placebo group. There were no significant differences in nutrient intake, plasma lipid profiles, markers of liver and kidney function, and major inflammation markers among groups. These results provide useful information on the dose-dependent effect of d-allulose for overweight/obese adult humans. Based on these results, the efficacy of d-allulose for body fat reduction needs to be validated using dual energy X-ray absorption.

The Diversity of Chemical Composition and the Effects on Stellar Evolution and Planetary Habitability

NASA Astrophysics Data System (ADS)

Truitt, Amanda R.

2017-08-01

I present a catalog of 1,794 stellar evolution models for solar-type and low-mass stars, which is intended to help characterize real host-stars of interest during the ongoing search for potentially habitable exoplanets. The main grid is composed of 904 tracks, for 0.5-1.2 M solar masses at scaled metallicity values of 0.1-1.5 Z solar masses and specific elemental abundance ratio values of 0.44-2.28 O/Fe solar masses, 0.58-1.72 C/Fe solar masses, 0.54-1.84 Mg/Fe solar masses, and 0.5-2.0 Ne/Fe solar masses. The catalog includes a small grid of late stage evolutionary tracks (25 models), as well as a grid of M-dwarf stars for 0.1-0.45 M solar masses (856 models). The time-dependent habitable zone evolution is calculated for each track, and is strongly dependent on stellar mass, effective temperature, and luminosity parameterizations. I have also developed a subroutine for the stellar evolution code TYCHO that implements a minimalist coupled model for estimating changes in the stellar X-ray luminosity, mass loss, rotational velocity, and magnetic activity over time; to test the utility of the updated code, I created a small grid (9 models) for solar-mass stars, with variations in rotational velocity and scaled metallicity. Including this kind of information in the catalog will ultimately allow for a more robust consideration of the long-term conditions that orbiting planets may experience. In order to gauge the true habitability potential of a given planetary system, it is extremely important to characterize the host-star's mass, specific chemical composition, and thus the timescale over which the star will evolve. It is also necessary to assess the likelihood that a planet found in the "instantaneous" habitable zone has actually had sufficient time to become "detectably" habitable. This catalog provides accurate stellar evolution predictions for a large collection of theoretical host-stars; the models are of particular utility in that they represent the real variation in stellar parameters that have been observed in nearby stars.

Quenching of Star-formation Activity of High-redshift Galaxies in Clusters and Field

NASA Astrophysics Data System (ADS)

Lee, Seong-Kook; Im, Myungshin; Kim, Jae-Woo; Lotz, Jennifer; McPartland, Conor; Peth, Michael; Koekemoer, Anton

At local, galaxy properties are well known to be clearly different in different environments. However, it is still an open question how this environment-dependent trend has been shaped. We present the results of our investigation about the evolution of star-formation properties of galaxies over a wide redshift range, from z ~ 2 to z ~ 0.5, focusing its dependence on their stellar mass and environment (Lee et al. 2015). In the UKIDSS/UDS region, covering ~2800 square arcmin, we estimated photometric redshifts and stellar population properties, such as stellar masses and star-formation rates, using the deep optical and near-infrared data available in this field. Then, we identified galaxy cluster candidates within the given redshift range. Through the analysis and comparison of star-formation (SF) properties of galaxies in clusters and in field, we found interesting results regarding the evolution of SF properties of galaxies: (1) regardless of redshifts, stellar mass is a key parameter controlling quenching of star formation in galaxies; (2) At z < 1, environmental effects become important at quenching star formation regardless of stellar mass of galaxies; and (3) However, the result of the environmental quenching is prominent only for low mass galaxies (M* < 1010 M⊙) since the star formation in most of high mass galaxies are already quenched at z > 1.

Reversibility between glass and melting transitions of poly(oxyethylene)

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

Qui, Wulin; Pyda, Marek; Nowak-Pyda, Elisabieta

2005-01-01

The heat capacities, C{sub p}, of poly(oxyethylene), POE, with molar masses from 1500 to 900,000 Da, were analyzed by differential scanning calorimetry (DSC), quasi-isothermal, temperature-modulated DSC (TMDSC), and wide-angle X-ray diffraction (WAXD). There is no change in crystal structure before melting, but the lattice parameters increase rapidly in the melting region. Perfected extended-chain and once- or twice-folded crystals of the oligomers with a molar mass above 1100 Da melt practically fully irreversibly and permit direct measurement of the thermodynamic C{sub p}. The folded-chain crystals of high molar mass show some locally reversible melting. The reversing, apparent C{sub p} depends onmore » molar mass and amplitude and frequency of modulation. After separation from the latent heat effects, the reversible, thermodynamic C{sub p} depends on the melting temperature for low molar masses and increases beyond the vibrational C{sub p} due to conformational motion. Molar masses of 8000-20,000 have almost the same C{sub p}. These observations permit a quantitative discussion of the thermodynamic C{sub p} and the locally reversible melting of the globally metastable POE in the melting range. The increase in C{sub p} between 250 K and the melting temperature is interpreted as a glass transition within the crystal.« less

Super-resolution imaging by resonant tunneling in anisotropic acoustic metamaterials.

PubMed

Liu, Aiping; Zhou, Xiaoming; Huang, Guoliang; Hu, Gengkai

2012-10-01

The resonant tunneling effects that could result in complete transmission of evanescent waves are examined in acoustic metamaterials of anisotropic effective mass. The tunneling conditions are first derived for the metamaterials composed of classical mass-in-mass structures. It is found that the tunneling transmission occurs when the total length of metamaterials is an integral number of half-wavelengths of the periodic Bloch wave. Due to the local resonance of building units of metamaterials, the Bloch waves are spatially modulated within the periodic structures, leading to the resonant tunneling occurring in the low-frequency region. The metamaterial slab lens with anisotropic effective mass is designed by which the physics of resonant tunneling and the features for evanescent field manipulations are examined. The designed lens interacts with evanescent waves in the way of the propagating wavenumber weakly dependent on the spatial frequency of evanescent waves. Full-wave simulations validate the imaging performance of the proposed lens with the spatial resolution beyond the diffraction limit.

Applications of QCD factorization in multiscale Hadronic scattering

NASA Astrophysics Data System (ADS)

Wang, Bowen

In this thesis I apply QCD factorization theorems to two important hadronic processes. In the first study, I treat the inclusive cross section of the production of massive quarks through neutral current deep inelasitc scattering (DIS): (n/a). In this study I work out a method to consistently organize the QCD radiative contributions up to O(alphas 3) (N3LO), with a proper inclusion of the heavy quark mass dependence at different momentum scales. The generic implementation of the mass dependence developed in this thesis can be used by calculations in both an intermediate-mass factorization scheme and a general-mass factorization scheme. The mass effect is relevant to the predictions for Higgs, and W and Z cross sections measured at the LHC. The second study examines the transverse-momentum distribution of the lepton-pair production in Drell-yan process. The theory predictions based on the Collins-Soper-Sterman (CSS) resummation formalism at NNLL accuracy are compared with the new data on the angular distribution *eta of Drell-Yan pairs measured at the Tevatron and the LHC. The main finding is that the nonperturbative component of the CSS resummed cross section plays a crucial part in explaining the data in the small transverse momentum region.

STAR FORMATION LAWS: THE EFFECTS OF GAS CLOUD SAMPLING

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

Calzetti, D.; Liu, G.; Koda, J., E-mail: calzetti@astro.umass.edu

Recent observational results indicate that the functional shape of the spatially resolved star formation-molecular gas density relation depends on the spatial scale considered. These results may indicate a fundamental role of sampling effects on scales that are typically only a few times larger than those of the largest molecular clouds. To investigate the impact of this effect, we construct simple models for the distribution of molecular clouds in a typical star-forming spiral galaxy and, assuming a power-law relation between star formation rate (SFR) and cloud mass, explore a range of input parameters. We confirm that the slope and the scattermore » of the simulated SFR-molecular gas surface density relation depend on the size of the sub-galactic region considered, due to stochastic sampling of the molecular cloud mass function, and the effect is larger for steeper relations between SFR and molecular gas. There is a general trend for all slope values to tend to {approx}unity for region sizes larger than 1-2 kpc, irrespective of the input SFR-cloud relation. The region size of 1-2 kpc corresponds to the area where the cloud mass function becomes fully sampled. We quantify the effects of selection biases in data tracing the SFR, either as thresholds (i.e., clouds smaller than a given mass value do not form stars) or as backgrounds (e.g., diffuse emission unrelated to current star formation is counted toward the SFR). Apparently discordant observational results are brought into agreement via this simple model, and the comparison of our simulations with data for a few galaxies supports a steep (>1) power-law index between SFR and molecular gas.« less

Genetics of fat intake in the determination of body mass.

PubMed

Chmurzynska, Agata; Mlodzik, Monika A

2017-06-01

Body mass and fat intake are multifactorial traits that have genetic and environmental components. The gene with the greatest effect on body mass is FTO (fat mass and obesity-associated), but several studies have shown that the effect of FTO (and of other genes) on body mass can be modified by the intake of nutrients. The so-called gene-environment interactions may also be important for the effectiveness of weight-loss strategies. Food choices, and thus fat intake, depend to some extent on individual preferences. The most important biological component of food preference is taste, and the role of fat sensitivity in fat intake has recently been pointed out. Relatively few studies have analysed the genetic components of fat intake or fatty acid sensitivity in terms of their relation to obesity. It has been proposed that decreased oral fatty acid sensitivity leads to increased fat intake and thus increased body mass. One of the genes that affect fatty acid sensitivity is CD36 (cluster of differentiation 36). However, little is known so far about the genetic component of fat sensing. We performed a literature review to identify the state of knowledge regarding the genetics of fat intake and its relation to body-mass determination, and to identify the priorities for further investigations.

Gas-surface interactions using accommodation coefficients for a dilute and a dense gas in a micro- or nanochannel: heat flux predictions using combined molecular dynamics and Monte Carlo techniques.

PubMed

Nedea, S V; van Steenhoven, A A; Markvoort, A J; Spijker, P; Giordano, D

2014-05-01

The influence of gas-surface interactions of a dilute gas confined between two parallel walls on the heat flux predictions is investigated using a combined Monte Carlo (MC) and molecular dynamics (MD) approach. The accommodation coefficients are computed from the temperature of incident and reflected molecules in molecular dynamics and used as effective coefficients in Maxwell-like boundary conditions in Monte Carlo simulations. Hydrophobic and hydrophilic wall interactions are studied, and the effect of the gas-surface interaction potential on the heat flux and other characteristic parameters like density and temperature is shown. The heat flux dependence on the accommodation coefficient is shown for different fluid-wall mass ratios. We find that the accommodation coefficient is increasing considerably when the mass ratio is decreased. An effective map of the heat flux depending on the accommodation coefficient is given and we show that MC heat flux predictions using Maxwell boundary conditions based on the accommodation coefficient give good results when compared to pure molecular dynamics heat predictions. The accommodation coefficients computed for a dilute gas for different gas-wall interaction parameters and mass ratios are transferred to compute the heat flux predictions for a dense gas. Comparison of the heat fluxes derived using explicit MD, MC with Maxwell-like boundary conditions based on the accommodation coefficients, and pure Maxwell boundary conditions are discussed. A map of the heat flux dependence on the accommodation coefficients for a dense gas, and the effective accommodation coefficients for different gas-wall interactions are given. In the end, this approach is applied to study the gas-surface interactions of argon and xenon molecules on a platinum surface. The derived accommodation coefficients are compared with values of experimental results.

The dependence of galaxy clustering on stellar mass, star-formation rate and redshift at z = 0.8-2.2, with HiZELS

NASA Astrophysics Data System (ADS)

Cochrane, R. K.; Best, P. N.; Sobral, D.; Smail, I.; Geach, J. E.; Stott, J. P.; Wake, D. A.

2018-04-01

The deep, near-infrared narrow-band survey HiZELS has yielded robust samples of H α-emitting star-forming galaxies within narrow redshift slices at z = 0.8, 1.47 and 2.23. In this paper, we distinguish the stellar mass and star-formation rate (SFR) dependence of the clustering of these galaxies. At high stellar masses (M*/M⊙ ≳ 2 × 1010), where HiZELS selects galaxies close to the so-called star-forming main sequence, the clustering strength is observed to increase strongly with stellar mass (in line with the results of previous studies of mass-selected galaxy samples) and also with SFR. These two dependencies are shown to hold independently. At lower stellar masses, however, where HiZELS probes high specific SFR galaxies, there is little or no dependence of the clustering strength on stellar mass, but the dependence on SFR remains: high-SFR low-mass galaxies are found in more massive dark matter haloes than their lower SFR counterparts. We argue that this is due to environmentally driven star formation in these systems. We apply the same selection criteria to the EAGLE cosmological hydrodynamical simulations. We find that, in EAGLE, the high-SFR low-mass galaxies are central galaxies in more massive dark matter haloes, in which the high SFRs are driven by a (halo-driven) increased gas content.

FGF signals from the nasal pit are necessary for normal facial morphogenesis.

PubMed

Szabo-Rogers, Heather L; Geetha-Loganathan, Poongodi; Nimmagadda, Suresh; Fu, Kathy K; Richman, Joy M

2008-06-15

Fibroblast growth factors (FGFs) are required for brain, pharyngeal arch, suture and neural crest cell development and mutations in the FGF receptors have been linked to human craniofacial malformations. To study the functions of FGF during facial morphogenesis we locally perturb FGF signalling in the avian facial prominences with FGFR antagonists, foil barriers and FGF2 protein. We tested 4 positions with antagonist-soaked beads but only one of these induced a facial defect. Embryos treated in the lateral frontonasal mass, adjacent to the nasal slit developed cleft beaks. The main mechanisms were a block in proliferation and an increase in apoptosis in those areas that were most dependent on FGF signaling. We inserted foil barriers with the goal of blocking diffusion of FGF ligands out of the lateral edge of the frontonasal mass. The barriers induced an upregulation of the FGF target gene, SPRY2 compared to the control side. Moreover, these changes in expression were associated with deletions of the lateral edge of the premaxillary bone. To determine whether we could replicate the effects of the foil by increasing FGF levels, beads soaked in FGF2 were placed into the lateral edge of the frontonasal mass. There was a significant increase in proliferation and an expansion of the frontonasal mass but the skeletal defects were minor and not the same as those produced by the foil. Instead it is more likely that the foil repressed FGF signaling perhaps mediated by the increase in SPRY2 expression. In summary, we have found that the nasal slit is a source of FGF signals and the function of FGF is to stimulate proliferation in the cranial frontonasal mass. The FGF independent regions correlate with those previously determined to be dependent on BMP signaling. We propose a new model whereby, FGF-dependent microenvironments exist in the cranial frontonasal mass and caudal maxillary prominence and these flank BMP-dependent regions. Coordination of the proliferation in these regions leads ultimately to normal facial morphogenesis.

A STELLAR-MASS-DEPENDENT DROP IN PLANET OCCURRENCE RATES

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

Mulders, Gijs D.; Pascucci, Ilaria; Apai, Dániel

2015-01-10

The Kepler spacecraft has discovered a large number of planets with up to one-year periods and down to terrestrial sizes. While the majority of the target stars are main-sequence dwarfs of spectral type F, G, and K, Kepler covers stars with effective temperatures as low as 2500 K, which corresponds to M stars. These cooler stars allow characterization of small planets near the habitable zone, yet it is not clear if this population is representative of that around FGK stars. In this paper, we calculate the occurrence of planets around stars of different spectral types as a function of planetmore » radius and distance from the star and show that they are significantly different from each other. We further identify two trends. First, the occurrence of Earth- to Neptune-sized planets (1-4 R {sub ⊕}) is successively higher toward later spectral types at all orbital periods probed by Kepler; planets around M stars occur twice as frequently as around G stars, and thrice as frequently as around F stars. Second, a drop in planet occurrence is evident at all spectral types inward of a ∼10 day orbital period, with a plateau further out. By assigning to each spectral type a median stellar mass, we show that the distance from the star where this drop occurs is stellar mass dependent, and scales with semi-major axis as the cube root of stellar mass. By comparing different mechanisms of planet formation, trapping, and destruction, we find that this scaling best matches the location of the pre-main-sequence co-rotation radius, indicating efficient trapping of migrating planets or planetary building blocks close to the star. These results demonstrate the stellar-mass dependence of the planet population, both in terms of occurrence rate and of orbital distribution. The prominent stellar-mass dependence of the inner boundary of the planet population shows that the formation or migration of planets is sensitive to the stellar parameters.« less

MASSCLEANCOLORS-MASS-DEPENDENT INTEGRATED COLORS FOR STELLAR CLUSTERS DERIVED FROM 30 MILLION MONTE CARLO SIMULATIONS

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

Popescu, Bogdan; Hanson, M. M.

2010-04-10

We present Monte Carlo models of open stellar clusters with the purpose of mapping out the behavior of integrated colors with mass and age. Our cluster simulation package allows for stochastic variations in the stellar mass function to evaluate variations in integrated cluster properties. We find that UBVK colors from our simulations are consistent with simple stellar population (SSP) models, provided the cluster mass is large, M {sub cluster} {>=} 10{sup 6} M {sub sun}. Below this mass, our simulations show two significant effects. First, the mean value of the distribution of integrated colors moves away from the SSP predictionsmore » and is less red, in the first 10{sup 7} to 10{sup 8} years in UBV colors, and for all ages in (V - K). Second, the 1{sigma} dispersion of observed colors increases significantly with lower cluster mass. We attribute the former to the reduced number of red luminous stars in most of the lower mass clusters and the latter to the increased stochastic effect of a few of these stars on lower mass clusters. This latter point was always assumed to occur, but we now provide the first public code able to quantify this effect. We are completing a more extensive database of magnitudes and colors as a function of stellar cluster age and mass that will allow the determination of the correlation coefficients among different bands, and improve estimates of cluster age and mass from integrated photometry.« less

Understanding leptin-dependent regulation of skeletal homeostasis

PubMed Central

Motyl, Katherine J.; Rosen, Clifford J.

2012-01-01

Despite growing evidence for adipose tissue regulation of bone mass, the role of the adipokine leptin in bone remodeling remains controversial. The majority of in vitro studies suggest leptin enhances osteoblastic proliferation and differentiation while inhibiting adipogenic differentiation from marrow stromal cells. Alternatively, some evidence demonstrates either no effect or a pro-apoptotic action of leptin on stromal cells. Similarly, in vivo work has demonstrated both positive and negative effects of leptin on bone mass. Most of the literature supports the idea that leptin suppresses bone mass by acting in the brainstem to reduce serotonin-dependent sympathetic signaling from the ventromedial hypothalamus to bone. However, other studies have found partly or entirely contrasting actions of leptin. Recently one study found a significant effect of surgery alone with intracerebroventricular administration of leptin, a technique crucial for understanding centrally-mediated leptin regulation of bone. Thus, two mainstream hypotheses for the role of leptin on bone emerge: 1) direct regulation through increased osteoblast proliferation and differentiation and 2) indirect suppression of bone formation through a hypothalamic relay. At the present time, it remains unclear whether these effects are relevant in only extreme circumstances (i.e. models with complete deficiency) or play an important homeostatic role in the regulation of peak bone acquisition and skeletal remodeling. Ultimately, determining the actions of leptin on the skeleton will be critical for understanding how the obesity epidemic may be impacting the prevalence of osteoporosis. PMID:22534195

New insights into the amphibious life of Biomphalaria glabrata and susceptibility of its egg masses to fungal infection.

PubMed

Duarte, Glennyha F; Rodrigues, Juscelino; Fernandes, Éverton K K; Humber, Richard A; Luz, Christian

2015-02-01

The air-breathing snail Biomphalaria glabrata proliferates in stagnant freshwater, and nothing is known about the survival of eggs in intermittently (rather than perpetually) wet habitats. In the present study their egg masses matured, and juveniles subsequently eclosed and were mobile in a stable water film of transitory habitats simulated by two different simple test devices described here. The viability of eggs maintained in an unstable film however, was diminished. The maturation of egg masses in a water film or in water was significantly prevented by the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae. The efficiency depended on the fungal propagule and test environment. Hyphal bodies were more effective against egg masses than conidia. This appears to be a first report of activity of either entomopathogen against a mollusc. Both devices offer accurate and reproducible conditions to test both biological questions and the effects of substances or pathogens against B. glabrata egg masses in water films. Copyright © 2015 Elsevier Inc. All rights reserved.

On a relativistic particle and a relativistic position-dependent mass particle subject to the Klein–Gordon oscillator and the Coulomb potential

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

Vitória, R.L.L.; Furtado, C., E-mail: furtado@fisica.ufpb.br; Bakke, K., E-mail: kbakke@fisica.ufpb.br

2016-07-15

The relativistic quantum dynamics of an electrically charged particle subject to the Klein–Gordon oscillator and the Coulomb potential is investigated. By searching for relativistic bound states, a particular quantum effect can be observed: a dependence of the angular frequency of the Klein–Gordon oscillator on the quantum numbers of the system. The meaning of this behaviour of the angular frequency is that only some specific values of the angular frequency of the Klein–Gordon oscillator are permitted in order to obtain bound state solutions. As an example, we obtain both the angular frequency and the energy level associated with the ground statemore » of the relativistic system. Further, we analyse the behaviour of a relativistic position-dependent mass particle subject to the Klein–Gordon oscillator and the Coulomb potential.« less

Rereading Effects Depend on Time of Test

ERIC Educational Resources Information Center

Rawson, Katherine A.; Kintsch, Walter

2005-01-01

Previous research has shown better text learning after rereading versus 1 reading of a text. However, rereading effects have only been explored using immediate tests, whereas most students face delays between study and test. In 2 experiments, 423 college students read a text once, twice in massed fashion, or twice with 1 week between trials.…

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Galaxy And Mass Assembly (GAMA): galaxy environments and star formation rate variations

NASA Astrophysics Data System (ADS)

Wijesinghe, D. B.; Hopkins, A. M.; Brough, S.; Taylor, E. N.; Norberg, P.; Bauer, A.; Brown, M. J. I.; Cameron, E.; Conselice, C. J.; Croom, S.; Driver, S.; Grootes, M. W.; Jones, D. H.; Kelvin, L.; Loveday, J.; Pimbblet, K. A.; Popescu, C. C.; Prescott, M.; Sharp, R.; Baldry, I.; Sadler, E. M.; Liske, J.; Robotham, A. S. G.; Bamford, S.; Bland-Hawthorn, J.; Gunawardhana, M.; Meyer, M.; Parkinson, H.; Drinkwater, M. J.; Peacock, J.; Tuffs, R.

2012-07-01

We present a detailed investigation into the effects of galaxy environment on their star formation rates (SFRs) using galaxies observed in the Galaxy And Mass Assembly (GAMA) survey. We use three independent volume-limited samples of galaxies within z < 0.2 and Mr < -17.8. We investigate the known SFR-density relationship and explore in detail the dependence of SFR on stellar mass and density. We show that the SFR-density trend is only visible when we include the passive galaxy population along with the star-forming population. This SFR-density relation is absent when we consider only the star-forming population of galaxies, consistent with previous work. While there is a strong dependence of the EWHα on density we find, as in previous studies, that these trends are largely due to the passive galaxy population and this relationship is absent when considering a 'star-forming' sample of galaxies. We find that stellar mass has the strongest influence on SFR and EWHα with the environment having no significant effect on the star formation properties of the star-forming population. We also show that the SFR-density relationship is absent for both early- and late-type star-forming galaxies. We conclude that the stellar mass has the largest impact on the current SFR of a galaxy, and any environmental effect is not detectable. The observation that the trends with density are due to the changing morphology fraction with density implies that the time-scales must be very short for any quenching of the SFR in infalling galaxies. Alternatively, galaxies may in fact undergo predominantly in situ evolution where the infall and quenching of galaxies from the field into dense environments is not the dominant evolutionary mode.

Pilot study to determine interest of adult civilian dependents of active duty military personnel in participation in a weight control program.

PubMed

Bukhari, Asma; Roberts, Susan B; Young, Andrew J; McGraw, Susan; Dallal, Gerard E; Das, Sai Krupa

2014-03-01

Adult civilian dependents of active duty military personnel (ADMP) may play a central role in influencing the home food environment and the risk of overweight and obesity in American Warfighters and military families. However, there is no information on whether this group would be receptive to weight control programs. We conducted a survey to determine the level of interest of adult civilian dependents of ADMP in participating in a group weight control program. Subjects were a convenience sample of 191 adult civilian dependents of ADMP (94% women, 6% men) based in Massachusetts and aged 33.8 ± 8.4 years, body mass index 25.5 ± 5.5 kg/m(2). Overall, there was a significant effect of body mass index on interest in program participation (p = 0.004). Eighty five percent of overweight participants and 100% of obese participants reported being Moderately Likely or Very Likely to participate in a provided weight control program. In overweight and obese survey respondents there was no significant effect of ADMP rank on interest in program participation (p = 0.34). These findings suggest that overweight and obese adult civilian dependents of ADMP may be very receptive targets for programs to control overweight and obesity in military families. Reprint & Copyright © 2014 Association of Military Surgeons of the U.S.

The effect of boron supplementation on lean body mass, plasma testosterone levels, and strength in male bodybuilders

NASA Technical Reports Server (NTRS)

Ferrando, A. A.; Green, N. R.

1993-01-01

The effect of boron supplementation was investigated in 19 male bodybuilders ages 20-27 years. Ten were given a 2.5-mg boron supplement while 9 were given a placebo every day for 7 weeks. Plasma total and free testosterone, plasma boron, lean body mass, and strength measurements were determined on Days 1 and 49 of the study. Plasma boron values were significantly (p < 0.05) different as the experimental group increased from (+/- SD) 20.1 +/- 7.7 ppb pretest to 32.6 +/- 27.6 ppb posttest, while the control group mean decreased from 15.1 +/- 14.4 ppb pretest to 6.3 +/- 5.5 ppb posttest. Analysis of variance indicated no significant effect of boron supplementation on any of the dependent variables. Both groups demonstrated significant increases in total testosterone, lean body mass, 1-RM squat, and 1-RM bench press. The findings suggest that 7 weeks of bodybuilding can increase total testosterone, lean body mass, and strength in lesser trained bodybuilders, and that boron supplementation had no effect on these measures.

The effect of boron supplementation on lean body mass, plasma testosterone levels, and strength in male bodybuilders.

PubMed

Ferrando, A A; Green, N R

1993-06-01

The effect of boron supplementation was investigated in 19 male bodybuilders ages 20-27 years. Ten were given a 2.5-mg boron supplement while 9 were given a placebo every day for 7 weeks. Plasma total and free testosterone, plasma boron, lean body mass, and strength measurements were determined on Days 1 and 49 of the study. Plasma boron values were significantly (p < 0.05) different as the experimental group increased from (+/- SD) 20.1 +/- 7.7 ppb pretest to 32.6 +/- 27.6 ppb posttest, while the control group mean decreased from 15.1 +/- 14.4 ppb pretest to 6.3 +/- 5.5 ppb posttest. Analysis of variance indicated no significant effect of boron supplementation on any of the dependent variables. Both groups demonstrated significant increases in total testosterone, lean body mass, 1-RM squat, and 1-RM bench press. The findings suggest that 7 weeks of bodybuilding can increase total testosterone, lean body mass, and strength in lesser trained bodybuilders, and that boron supplementation had no effect on these measures.

Effect of Various Sodium Chloride Mass Fractions on Wheat and Rye Bread Using Different Dough Preparation Techniques

PubMed Central

Tańska, Małgorzata; Rotkiewicz, Daniela; Piętak, Andrzej

2016-01-01

Summary This study assessed the selected properties of bread with reduced amount of sodium chloride. The bread was made from white and wholemeal wheat flour and rye flour. The dough was prepared using three techniques: with yeast, natural sourdough or starter sourdough. Sodium chloride was added to the dough at 0, 0.5, 1.0 and 1.5% of the flour mass. The following bread properties were examined in the study: yield and volume of the loaf, moisture content, crumb firmness and porosity, and organoleptic properties. Reducing the mass fraction of added sodium chloride was not found to have considerable effect on bread yield, whereas it had a significant and variable effect on the loaf volume, and crumb firmness and porosity. Organoleptic assessment showed diverse effects of sodium chloride addition on sensory properties of bread, depending on the type of bread and the dough preparation method. Reduced mass fractions of sodium chloride changed the organoleptic properties of bread made with yeast and with starter sourdough to a greater extent than of bread prepared with natural sourdough. PMID:27904407

Aerosol detection efficiency in inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Hubbard, Joshua A.; Zigmond, Joseph A.

2016-05-01

An electrostatic size classification technique was used to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Size-segregated particles were counted with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized by the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10- 5 to 10- 11. Free molecular heat and mass transfer theory was applied, but evaporative phenomena were not sufficient to explain the dependence of aerosol detection on particle diameter. Additional work is needed to correlate experimental data with theory for metal-oxides where thermodynamic property data are sparse relative to pure elements. Lastly, when matrix effects and the diffusion of ions inside the plasma were considered, mass loading was concluded to have had an effect on the dependence of detection efficiency on particle diameter.

Core-mass nonadiabatic corrections to molecules: H2, H2+, and isotopologues.

PubMed

Diniz, Leonardo G; Alijah, Alexander; Mohallem, José Rachid

2012-10-28

For high-precision calculations of rovibrational states of light molecules, it is essential to include non-adiabatic corrections. In the absence of crossings of potential energy surfaces, they can be incorporated in a single surface picture through coordinate-dependent vibrational and rotational reduced masses. We present a compact method for their evaluation and relate in particular the vibrational mass to a well defined nuclear core mass derived from a Mulliken analysis of the electronic density. For the rotational mass we propose a simple, but very effective parametrization. The use of these masses in the nuclear Schrödinger equation yields numerical data for the corrections of a much higher quality than can be obtained with optimized constant masses, typically better than 0.1 cm(-1). We demonstrate the method for H(2), H(2)(+), and singly deuterated isotopologues. Isotopic asymmetry does not present any particular difficulty. Generalization to polyatomic molecules is straightforward.

Muon reactivation in muon-catalyzed D-T fusion

NASA Astrophysics Data System (ADS)

Rafelski, H. E.; Müller, B.; Rafelski, J.; Trautmann, D.; Viollier, R. D.

We comprehensively reanalyze and search for the density dependence of the effective muon alpha sticking fraction ωsff observed experimentally in muon catalyzed deuterium-tritium fusion. In our work particular emphasis has been put on the density dependent dense hydrogen stopping power. The main technical details and improvements in this work are: The (αμ) + 2s and 2p states are treated independently and are assigned individual reaction rates. The essential muonic excitation rates have been recalculated taking into account finite nuclear mass effects. The stopping power for a charged projectile in liquid heavy hydrogen is modified to account for dynamic screening effects and a density dependent effective ionization potential. It is shown that the medium dependent stopping power for the (αμ) + ion is the crucial factor controlling the density dependence of the effective sticking fraction. It is also pointed out that the muonic helium K α X-ray yield and the sticking fraction at high density can not be simultaneously brought into agreement with the experimental results without invoking novel mechanisms suppressing Stark mixing in the (Heμ) L-shell.

Convective radiation fluid-dynamics: formation and early evolution of ultra low-mass objects

NASA Astrophysics Data System (ADS)

Wuchterl, G.

2005-12-01

The formation process of ultra low-mass objects is some kind of extension of the star formation process. The physical changes towards lower mass are discussed by investigating the collapse of cloud cores that are modelled as Bonnor-Ebert spheres. Their collapse is followed by solving the equations of fluid dynamics with radiation and a model of time-dependent convection that has been calibrated to the Sun. For a sequence of cloud-cores with 1 to 0.01 solar masses, evolutionary tracks and isochrones are shown in the mass-radius diagram, the Hertzsprung-Russel diagram and the effective temperature-surface gravity or Kiel diagram. The collapse and the early hydrostatic evolution to ages of few Ma are briefly discussed and compared to observations of objects in Upper Scorpius and the low-mass components of GG Tau.

Planning an effective anti-smoking mass media campaign targeting adolescents.

PubMed

Pechmann, C; Reibling, E T

2000-05-01

This article addresses the following issues: Can an anti-smoking campaign that depends largely on mass media vehicles effectively reduce adolescent tobacco use? Why is an integrated campaign recommended and what are the steps in designing such a campaign? How should the campaign be evaluated? Specific topics include recommended campaign expenditures, target audience identification, selection of persuasive message content, executional (stylistic) considerations, media buying decisions, the use of focus group research and advertising copy-testing research, and outcome evaluations. It is concluded that comprehensive strategic planning and extensive research at all phases of the campaign are essential to success.

Regular expansion solutions for small Peclet number heat or mass transfer in concentrated two-phase particulate systems

NASA Technical Reports Server (NTRS)

Yaron, I.

1974-01-01

Steady state heat or mass transfer in concentrated ensembles of drops, bubbles or solid spheres in uniform, slow viscous motion, is investigated. Convective effects at small Peclet numbers are taken into account by expanding the nondimensional temperature or concentration in powers of the Peclet number. Uniformly valid solutions are obtained, which reflect the effects of dispersed phase content and rate of internal circulation within the fluid particles. The dependence of the range of Peclet and Reynolds numbers, for which regular expansions are valid, on particle concentration is discussed.

Plant litter functional diversity effects on litter mass loss depend on the macro-detritivore community.

PubMed

Patoine, Guillaume; Thakur, Madhav P; Friese, Julia; Nock, Charles; Hönig, Lydia; Haase, Josephine; Scherer-Lorenzen, Michael; Eisenhauer, Nico

2017-11-01

A better understanding of the mechanisms driving litter diversity effects on decomposition is needed to predict how biodiversity losses affect this crucial ecosystem process. In a microcosm study, we investigated the effects of litter functional diversity and two major groups of soil macro-detritivores on the mass loss of tree leaf litter mixtures. Furthermore, we tested the effects of litter trait community means and dissimilarity on litter mass loss for seven traits relevant to decomposition. We expected macro-detritivore effects on litter mass loss to be most pronounced in litter mixtures of high functional diversity. We used 24 leaf mixtures differing in functional diversity, which were composed of litter from four species from a pool of 16 common European tree species. Earthworms, isopods, or a combination of both were added to each litter combination for two months. Litter mass loss was significantly higher in the presence of earthworms than in that of isopods, whereas no synergistic effects of macro-detritivore mixtures were found. The effect of functional diversity of the litter material was highest in the presence of both macro-detritivore groups, supporting the notion that litter diversity effects are most pronounced in the presence of different detritivore species. Species-specific litter mass loss was explained by nutrient content, secondary compound concentration, and structural components. Moreover, dissimilarity in N concentrations increased litter mass loss, probably because detritivores having access to nutritionally diverse food sources. Furthermore, strong competition between the two macro-detritivores for soil surface litter resulted in a decrease of survival of both macro-detritivores. These results show that the effects of litter functional diversity on decomposition are contingent upon the macro-detritivore community and composition. We conclude that the temporal dynamics of litter trait diversity effects and their interaction with detritivore diversity are key to advancing our understanding of litter mass loss in nature.

Plant litter functional diversity effects on litter mass loss depend on the macro-detritivore community

PubMed Central

Patoine, Guillaume; Thakur, Madhav P.; Friese, Julia; Nock, Charles; Hönig, Lydia; Haase, Josephine; Scherer-Lorenzen, Michael; Eisenhauer, Nico

2017-01-01

A better understanding of the mechanisms driving litter diversity effects on decomposition is needed to predict how biodiversity losses affect this crucial ecosystem process. In a microcosm study, we investigated the effects of litter functional diversity and two major groups of soil macro-detritivores on the mass loss of tree leaf litter mixtures. Furthermore, we tested the effects of litter trait community means and dissimilarity on litter mass loss for seven traits relevant to decomposition. We expected macro-detritivore effects on litter mass loss to be most pronounced in litter mixtures of high functional diversity. We used 24 leaf mixtures differing in functional diversity, which were composed of litter from four species from a pool of 16 common European tree species. Earthworms, isopods, or a combination of both were added to each litter combination for two months. Litter mass loss was significantly higher in the presence of earthworms than in that of isopods, whereas no synergistic effects of macro-detritivore mixtures were found. The effect of functional diversity of the litter material was highest in the presence of both macro-detritivore groups, supporting the notion that litter diversity effects are most pronounced in the presence of different detritivore species. Species-specific litter mass loss was explained by nutrient content, secondary compound concentration, and structural components. Moreover, dissimilarity in N concentrations increased litter mass loss, probably because detritivores having access to nutritionally diverse food sources. Furthermore, strong competition between the two macro-detritivores for soil surface litter resulted in a decrease of survival of both macro-detritivores. These results show that the effects of litter functional diversity on decomposition are contingent upon the macro-detritivore community and composition. We conclude that the temporal dynamics of litter trait diversity effects and their interaction with detritivore diversity are key to advancing our understanding of litter mass loss in nature. PMID:29180828

Effects of NOx and SO2 on the secondary organic aerosol formation from photooxidation of α-pinene and limonene

NASA Astrophysics Data System (ADS)

Zhao, Defeng; Schmitt, Sebastian H.; Wang, Mingjin; Acir, Ismail-Hakki; Tillmann, Ralf; Tan, Zhaofeng; Novelli, Anna; Fuchs, Hendrik; Pullinen, Iida; Wegener, Robert; Rohrer, Franz; Wildt, Jürgen; Kiendler-Scharr, Astrid; Wahner, Andreas; Mentel, Thomas F.

2018-02-01

Anthropogenic emissions such as NOx and SO2 influence the biogenic secondary organic aerosol (SOA) formation, but detailed mechanisms and effects are still elusive. We studied the effects of NOx and SO2 on the SOA formation from the photooxidation of α-pinene and limonene at ambient relevant NOx and SO2 concentrations (NOx: < 1to 20 ppb, SO2: < 0.05 to 15 ppb). In these experiments, monoterpene oxidation was dominated by OH oxidation. We found that SO2 induced nucleation and enhanced SOA mass formation. NOx strongly suppressed not only new particle formation but also SOA mass yield. However, in the presence of SO2 which induced a high number concentration of particles after oxidation to H2SO4, the suppression of the mass yield of SOA by NOx was completely or partly compensated for. This indicates that the suppression of SOA yield by NOx was largely due to the suppressed new particle formation, leading to a lack of particle surface for the organics to condense on and thus a significant influence of vapor wall loss on SOA mass yield. By compensating for the suppressing effect on nucleation of NOx, SO2 also compensated for the suppressing effect on SOA yield. Aerosol mass spectrometer data show that increasing NOx enhanced nitrate formation. The majority of the nitrate was organic nitrate (57-77 %), even in low-NOx conditions (< ˜ 1 ppb). Organic nitrate contributed 7-26 % of total organics assuming a molecular weight of 200 g mol-1. SOA from α-pinene photooxidation at high NOx had a generally lower hydrogen to carbon ratio (H / C), compared to low NOx. The NOx dependence of the chemical composition can be attributed to the NOx dependence of the branching ratio of the RO2 loss reactions, leading to a lower fraction of organic hydroperoxides and higher fractions of organic nitrates at high NOx. While NOx suppressed new particle formation and SOA mass formation, SO2 can compensate for such effects, and the combining effect of SO2 and NOx may have an important influence on SOA formation affected by interactions of biogenic volatile organic compounds (VOCs) with anthropogenic emissions.

The Fate of Super-AGB Stars at Low Metallicity

NASA Astrophysics Data System (ADS)

Decressin, T.; Siess, L.; Charbonnel, C.; Leclair, G.

2005-11-01

Super-AGBs are stars massive enough to ignite carbon off center and to climb the asymptotic giant branch (where they undergo thermal pulses) after core carbon exhaustion. The destiny of these stars, ONe white dwarfs or neutron stars, depends essentially on the ability of the mass loss to peel the stellar envelope before the core reaches the critical mass for electron captures to occur. Here, we focus on a super-AGB stars of 8.5 Msolar at Z=0.0001 and investigate the effects of various mass loss prescriptions. We study the interplay between mass loss and diffusive overshooting below the convective envelope. The former determines the duration of the AGB phase and the final state of the star; the latter affects the increase of the core mass and the nucleosynthesis as well.

Is drag luminosity effective in recurrent novae

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

Kato, Mariko; Hachisu, Izumi

1991-06-01

A study has been made of the efficiency of frictional processes in common envelope phase at outbursts of three recurrent novae T Pyx, U Sco, and RS Oph, by using steady-state wind models. The drag luminosity is found to depend strongly on the envelope mass. It may play an important role for a relatively massive envelope of about 0.0001 solar mass or more. For recurrent novae, however, acceleration due to the drag force is not important to eject the envelope mass because of its small envelope mass. Since the drag luminosity can be neglected at the extended phase of novamore » outburst, the light curves of these recurrent novae are determined only by the wind-driven mass loss as shown by Kato (1990). 23 refs.« less

Carbon Kinetic Isotope Effects in the Oxidation of Atmospheric Alkane and Aromatic Hydrocarbons by Hydroxyl Radicals

NASA Astrophysics Data System (ADS)

Anderson, R. S.; Thompson, A. E.; Rudolph, J.; Huang, L.

2001-12-01

To interpret measurements of stable carbon isotope ratios of ambient NMHC, we need to understand the isotopic composition of the emissions, and the isotope fractionation associated with the removal of NMHC from the atmosphere. Oxidation by OH-radicals is by far the most important atmospheric process for removal of NMHC. In this presentation measurements of the kinetic isotope effects (KIEs) for the reactions of hydroxyl radicals with several C5-C8 alkanes, including cyclic, branched and straight-chain alkanes, as well as C6-C9 aromatics are presented. All KIEs are positive: compounds containing only 12C atoms react faster than 13C labelled compounds. KIEs for light n-alkanes are typically between 1.5-4‰ and are larger than mass dependent collision frequencies, deviating from the collision frequency as carbon number increases. For n-alkanes there is no statistically significant difference between the KIEs of structural isomers. KIEs for the reactions of light alkenes and aromatics with OH-radicals are considerably higher than for alkane reactions, ranging from 3-18‰ . The KIEs for the aromatic reactions can be described by a 33.3+/-2.0‰ fractionation for the addition of an OH-radical to the aromatic ring and an inverse dependency on the number of carbon atoms, added to the mass dependent collision frequency. There are indications for minor structure specific effects, however the deviations from the idealised inverse carbon number dependence is relatively small and the limited number of studied alkyl benzenes does not yet allow the identification of systematic dependencies.

Microscopic model for the isotope effect in the high-Tc oxides

NASA Astrophysics Data System (ADS)

Kresin, V. Z.; Wolf, S. A.

1994-02-01

An unconventional microscopic mechanism relating Tc and the isotope substitution for the doped superconductors such as the high-Tc oxides is proposed. Strong nonadiabaticity, when it is impossible, strictly speaking, to separate fully the nuclear and electronic degrees of freedom, leads to a peculiar dependence of the carrier concentration n on the ionic mass M. This case corresponds, for example, to the isotopic substitution of the axial oxygen in YBa2Cu3O7-x. Because of the dependence of Tc on n, this leads to the dependence of Tc on M, that is to the isotope effect. The minimum value of the isotope coefficient corresponds to Tc=Tmaxc.

Ionisation in turbulent magnetic molecular clouds. I. Effect on density and mass-to-flux ratio structures

NASA Astrophysics Data System (ADS)

Bailey, Nicole D.; Basu, Shantanu; Caselli, Paola

2017-05-01

Context. Previous studies show that the physical structures and kinematics of a region depend significantly on the ionisation fraction. These studies have only considered these effects in non-ideal magnetohydrodynamic simulations with microturbulence. The next logical step is to explore the effects of turbulence on ionised magnetic molecular clouds and then compare model predictions with observations to assess the importance of turbulence in the dynamical evolution of molecular clouds. Aims: In this paper, we extend our previous studies of the effect of ionisation fractions on star formation to clouds that include both non-ideal magnetohydrodynamics and turbulence. We aim to quantify the importance of a treatment of the ionisation fraction in turbulent magnetised media and investigate the effect of the turbulence on shaping the clouds and filaments before star formation sets in. In particular, here we investigate how the structure, mass and width of filamentary structures depend on the amount of turbulence in ionised media and the initial mass-to-flux ratio. Methods: To determine the effects of turbulence and mass-to-flux ratio on the evolution of non-ideal magnetised clouds with varying ionisation profiles, we have run two sets of simulations. The first set assumes different initial turbulent Mach values for a fixed initial mass-to-flux ratio. The second set assumes different initial mass-to-flux ratio values for a fixed initial turbulent Mach number. Both sets explore the effect of using one of two ionisation profiles: step-like (SL) or cosmic ray only (CR-only). We compare the resulting density and mass-to-flux ratio structures both qualitatively and quantitatively via filament and core masses and filament fitting techniques (Gaussian and Plummer profiles). Results: We find that even with almost no turbulence, filamentary structure still exists although at lower density contours. Comparison of simulations shows that for turbulent Mach numbers above 2, there is little structural difference between the SL and CR-only models, while below this threshold the ionisation structure significantly affects the formation of filaments. This holds true for both sets of models. Analysis of the mass within cores and filaments shows that the mass decreases as the degree of turbulence increases. Finally, observed filaments within the Taurus L1495/B213 complex are best reproduced by models with supercritical mass-to-flux ratios and/or at least mildly supersonic turbulence, however, our models show that the sterile fibres observed within Taurus may occur in highly ionised, subcritical environments. Conclusions: From the analysis of the simulations, we conclude that in the presence of low turbulent velocities, the ionisation structure of the medium still plays a role in shaping the structure of the cloud, however, above Mach 2, the differences between the two profiles become indistinguishable. However, differences may be present in the underlying velocity structure. Kinematics studies will be the focus of the next paper in this series. Regions with fertile fibres likely indicate a trans- or supercritical mass-to-flux ratio within the region while sterile fibres are likely subcritical and transient.

Uncertainties and Systematic Effects on the estimate of stellar masses in high z galaxies

NASA Astrophysics Data System (ADS)

Salimbeni, S.; Fontana, A.; Giallongo, E.; Grazian, A.; Menci, N.; Pentericci, L.; Santini, P.

2009-05-01

We discuss the uncertainties and the systematic effects that exist in the estimates of the stellar masses of high redshift galaxies, using broad band photometry, and how they affect the deduced galaxy stellar mass function. We use at this purpose the latest version of the GOODS-MUSIC catalog. In particular, we discuss the impact of different synthetic models, of the assumed initial mass function and of the selection band. Using Chariot & Bruzual 2007 and Maraston 2005 models we find masses lower than those obtained from Bruzual & Chariot 2003 models. In addition, we find a slight trend as a function of the mass itself comparing these two mass determinations with that from Bruzual & Chariot 2003 models. As consequence, the derived galaxy stellar mass functions show diverse shapes, and their slope depends on the assumed models. Despite these differences, the overall results and scenario is observed in all these cases. The masses obtained with the assumption of the Chabrier initial mass function are in average 0.24 dex lower than those from the Salpeter assumption, at all redshifts, causing a shift of galaxy stellar mass function of the same amount. Finally, using a 4.5 μm-selected sample instead of a Ks-selected one, we add a new population of highly absorbed, dusty galaxies at z~=2-3 of relatively low masses, yielding stronger constraints on the slope of the galaxy stellar mass function at lower masses.

Is vacuum ultraviolet detector a concentration or a mass dependent detector?

PubMed

Liu, Huian; Raffin, Guy; Trutt, Guillaume; Randon, Jérôme

2017-12-29

The vacuum ultraviolet detector (VUV) is a very effective tool for chromatogram deconvolution and peak identification, and can also be used for quantification. To avoid quantitative issues in relation to time drift, such as variation of peak area or peak height, the detector response type has to be well defined. Due to the make-up flow and pressure regulation of make-up, the detector response (height of the peak) and peak area appeared to be dependent on experimental conditions such as inlet pressure and make-up pressure. Even if for some experimental conditions, VUV looks like mass-flow sensitive detector, it has been demonstrated that VUV is a concentration sensitive detector. Copyright © 2017 Elsevier B.V. All rights reserved.

Forensic engineering of advanced polymeric materials. Part III - Biodegradation of thermoformed rigid PLA packaging under industrial composting conditions.

PubMed

Musioł, Marta; Sikorska, Wanda; Adamus, Grazyna; Janeczek, Henryk; Richert, Jozef; Malinowski, Rafal; Jiang, Guozhan; Kowalczuk, Marek

2016-06-01

This paper presents a forensic engineering study on the biodegradation behaviour of prototype packaging thermoformed from PLA-extruded film and plain PLA film under industrial composting conditions. Hydrolytic degradation in water was conducted for reference. The effects of composting duration on changes in molar mass, glass transition temperature and degree of crystallinity of the polymeric material were monitored using gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The chemical structure of water soluble degradation products of the polymeric material was determined using nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI-MS). The results show that the biodegradation process is less dependent on the thermoforming process of PLA and more dependent on the composting/degradation conditions that are applied. The increase in the dispersity index, leading to the bimodal molar mass distribution profile, suggests an autocatalytic hydrolysis effect at the early stage of the composting process, during which the bulk hydrolysis mechanism dominantly operates. Both the prototype PLA-packaging and PLA rigid film samples were shown to have a gradual increase in opacity due to an increase in the degree of crystallinity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Gender-specific increase of bone mass by CART peptide treatment is ovary-dependent.

PubMed

Gerrits, Han; Bakker, Nicole Ec; van de Ven-de Laat, Cindy Jm; Bourgondien, Freek Gm; Peddemors, Carolien; Litjens, Ralph Hgm; Kok, Han J; Vogel, Gerard Mt; Krajnc-Franken, Magda Am; Gossen, Jan A

2011-12-01

Cocaine- and amphetamine-regulated transcript (CART) has emerged as a neurotransmitter and hormone that has been implicated in many processes including food intake, maintenance of body weight, and reward, but also in the regulation of bone mass. CART-deficient mice are characterized by an osteoporotic phenotype, whereas female transgenic mice overexpressing CART display an increase in bone mass. Here we describe experiments that show that peripheral subcutaneous sustained release of different CART peptide isoforms for a period up to 60 days increased bone mass by 80% in intact mice. CART peptides increased trabecular bone mass, but not cortical bone mass, and the increase was caused by reduced osteoclast activity in combination with normal osteoblast activity. The observed effect on bone was gender-specific, because male mice did not respond to treatment with CART peptides. In addition, male transgenic CART overexpressing mice did not display increased bone mass. Ovariectomy (OVX) completely abolished the increase of bone mass by CART peptides, both in CART peptide-treated wild-type mice and in CART transgenic mice. The effect of CART peptide treatment on trabecular bone was not mediated by 17β-estradiol (E(2)) because supplementation of OVX mice with E(2) could not rescue the effect of CART peptides on bone. Together, these results indicate that sustained release of CART peptides increases bone mass in a gender-specific way via a yet unknown mechanism that requires the presence of the ovary. Copyright © 2011 American Society for Bone and Mineral Research.

The transmission of vertical vibration through seats: Influence of the characteristics of the human body

NASA Astrophysics Data System (ADS)

Toward, Martin G. R.; Griffin, Michael J.

2011-12-01

The transmission of vibration through a seat depends on the impedance of the seat and the apparent mass of the seat occupant. This study was designed to determine how factors affecting the apparent mass of the body (age, gender, physical characteristics, backrest contact, and magnitude of vibration) affect seat transmissibility. The transmission of vertical vibration through a car seat was measured with 80 adults (41 males and 39 females aged 18-65) at frequencies between 0.6 and 20 Hz with two backrest conditions (no backrest and backrest), and with three magnitudes of random vibration (0.5, 1.0, and 1.5 m s -2 rms). Linear regression models were used to study the effects of subject physical characteristics (age, gender, and anthropometry) and features of their apparent mass (resonance frequency, apparent mass at resonance and at 12 Hz) on the measured seat transmissibility. The strongest predictor of both the frequency of the principal resonance in seat transmissibility and the seat transmissibility at resonance was subject age, with other factors having only marginal effects. The transmissibility of the seat at 12 Hz depended on subject age, body mass index, and gender. Although subject weight was strongly associated with apparent mass, weight was not strongly associated with seat transmissibility. The resonance frequency of the seat decreased with increases in the magnitude of the vibration excitation and increased when subjects made contact with the backrest. Inter-subject variability in the resonance frequency and transmissibility at resonance was less with greater vibration excitation, but was largely unaffected by backrest contact. A lumped parameter seat-person model showed that changes in seat transmissibility with age can be predicted from changes in apparent mass with age, and that the dynamic stiffness of the seat appeared to increase with increased loading so as to compensate for increases in subject apparent mass associated with increased sitting weight.

Valley polarization in bismuth

NASA Astrophysics Data System (ADS)

Fauque, Benoit

2013-03-01

The electronic structure of certain crystal lattices can contain multiple degenerate valleys for their charge carriers to occupy. The principal challenge in the development of valleytronics is to lift the valley degeneracy of charge carriers in a controlled way. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. According to our recent study of angle-dependent magnetoresistance in bismuth, a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. As a consequence of a unique combination of high mobility and extreme mass anisotropy in bismuth, the effect is visible even at room temperature in a magnetic field of 1 T. Thus, a modest magnetic field can be used as a valley valve in bismuth. The results of our recent investigation of angle-dependent magnetoresistance in other semi-metals and doped semiconductors suggest that a rotating magnetic field can behave as a valley valve in a multi-valley system with sizeable mass anisotropy.

Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis.

PubMed

Larsen, K K; Wielandt, D; Schiller, M; Bizzarro, M

2016-04-22

Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr(3+), CrCl(2+) and CrCl2(+)) with equilibrium mass-dependent isotope fractionation spanning a range of ∼1‰/amu and consistent with theory. The heaviest isotopes partition into Cr(3+), intermediates in CrCl(2+) and the lightest in CrCl2(+)/CrCl3°. Thus, for a typical reported loss of ∼25% Cr (in the form of Cr(3+)) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected (53)Cr/(52)Cr (μ(53)Cr* of 5.2 ppm) and (54)Cr/(52)Cr (μ(54)Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr(3+) by >5 days exposure to HNO3H2O2 solutions at room temperature, resulting in >∼98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a chromatographic elution strategy that takes advantage of the slow reaction kinetics of de-chlorination of Cr in dilute HCl at room temperature. These procedures significantly improve cation chromatographic purification of Cr over previous methods and allow for high-purity Cr isotope analysis with a total recovery of >95%. Copyright © 2016 Elsevier B.V. All rights reserved.

Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

PubMed Central

Larsen, K.K.; Wielandt, D.; Schiller, M.; Bizzarro, M.

2016-01-01

Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr3+, CrCl2+ and CrCl2+) with equilibrium mass-dependent isotope fractionation spanning a range of ~1‰/amu and consistent with theory. The heaviest isotopes partition into Cr3+, intermediates in CrCl2+ and the lightest in CrCl2+/CrCl3°. Thus, for a typical reported loss of ~25% Cr (in the form of Cr3+) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected 53Cr/52Cr (μ53 Cr* of 5.2 ppm) and 54Cr/52Cr (μ54Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr3+ by >5 days exposure to HNO3 —H2O2 solutions at room temperature, resulting in >~98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a chromatographic elution strategy that takes advantage of the slow reaction kinetics of de-chlorination of Cr in dilute HCl at room temperature. These procedures significantly improve cation chromatographic purification of Cr over previous methods and allow for high-purity Cr isotope analysis with a total recovery of >95%. PMID:27036208

Effect of collisions on neutrino flavor inhomogeneity in a dense neutrino gas

DOE PAGES

Cirigliano, Vincenzo; Paris, Mark W.; Shalgar, Shashank

2017-09-25

We investigate the stability, with respect to spatial inhomogeneity, of a two-dimensional dense neutrino gas. The system exhibits growth of seed inhomogeneity due to nonlinear coherent neutrino self-interactions. In the absence of incoherent collisional effects, we also observe a dependence of this instability growth rate on the neutrino mass spectrum: the normal neutrino mass hierarchy exhibits spatial instability over a larger range of neutrino number density compared to that of the inverted case. Furthermore, we consider the effect of elastic incoherent collisions of the neutrinos with a static background of heavy, nucleon-like scatterers. At small scales, the growth of flavormore » instability can be suppressed by collisions. At large length scales we find, perhaps surprisingly, that for inverted neutrino mass hierarchy incoherent collisions fail to suppress flavor instabilities, independent of the coupling strength.« less

Theoretical monochromatic-wave-induced currents in intermediate water with viscosity and nonzero mass transport

NASA Technical Reports Server (NTRS)

Talay, T. A.

1975-01-01

Wave-induced mass-transport current theories with both zero and nonzero net mass (or volume) transport of the water column are reviewed. A relationship based on the Longuet-Higgens theory is derived for wave-induced, nonzero mass-transport currents in intermediate water depths for a viscous fluid. The relationship is in a form useful for experimental applications; therefore, some design criteria for experimental wave-tank tests are also presented. Sample parametric cases for typical wave-tank conditions and a typical ocean swell were assessed by using the relation in conjunction with an equation developed by Unluata and Mei for the maximum wave-induced volume transport. Calculations indicate that substantial changes in the wave-induced mass-transport current profiles may exist dependent upon the assumed net volume transport. A maximum volume transport, corresponding to an infinite channel or idealized ocean condition, produces the largest wave-induced mass-transport currents. These calculations suggest that wave-induced mass-transport currents may have considerable effects on pollution and suspended-sediments transport as well as buoy drift, the surface and midlayer water-column currents caused by waves increasing with increasing net volume transports. Some of these effects are discussed.

A non-terrestrial 16O-rich isotopic composition for the protosolar nebula.

PubMed

Hashizume, Ko; Chaussidon, Marc

2005-03-31

The discovery in primitive components of meteorites of large oxygen isotopic variations that could not be attributed to mass-dependent fractionation effects has raised a fundamental question: what is the composition of the protosolar gas from which the host grains formed? This composition is probably preserved in the outer layers of the Sun, but the resolution of astronomical spectroscopic measurements is still too poor to be useful for comparison with planetary material. Here we report a precise determination of the oxygen isotopic composition of the solar wind from particles implanted in the outer hundreds of nanometres of metallic grains in the lunar regolith. These layers of the grains are enriched in 16O by >20 +/- 4 per thousand relative to the Earth, Mars and bulk meteorites, which implies the existence in the solar accretion disk of reactions--as yet unknown--that were able to change the 17O/16O and 18O/16O ratios in a way that was not dependent strictly on the mass of the isotope. Photochemical self-shielding of the CO gas irradiated by ultraviolet light may be one of these key processes, because it depends on the abundance of the isotopes, rather than their masses.

SDSS-IV MaNGA: environmental dependence of stellar age and metallicity gradients in nearby galaxies

NASA Astrophysics Data System (ADS)

Zheng, Zheng; Wang, Huiyuan; Ge, Junqiang; Mao, Shude; Li, Cheng; Li, Ran; Mo, Houjun; Goddard, Daniel; Bundy, Kevin; Li, Hongyu; Nair, Preethi; Lin, Lihwai; Long, R. J.; Riffel, Rogério; Thomas, Daniel; Masters, Karen; Bizyaev, Dmitry; Brownstein, Joel R.; Zhang, Kai; Law, David R.; Drory, Niv; Roman Lopes, Alexandre; Malanushenko, Olena

2017-03-01

We present a study on the stellar age and metallicity distributions for 1105 galaxies using the STARLIGHT software on MaNGA (Mapping Nearby Galaxies at APO) integral field spectra. We derive age and metallicity gradients by fitting straight lines to the radial profiles, and explore their correlations with total stellar mass M*, NUV - r colour and environments, as identified by both the large-scale structure (LSS) type and the local density. We find that the mean age and metallicity gradients are close to zero but slightly negative, which is consistent with the inside-out formation scenario. Within our sample, we find that both the age and metallicity gradients show weak or no correlation with either the LSS type or local density environment. In addition, we also study the environmental dependence of age and metallicity values at the effective radii. The age and metallicity values are highly correlated with M* and NUV - r and are also dependent on LSS type as well as local density. Low-mass galaxies tend to be younger and have lower metallicity in low-density environments while high-mass galaxies are less affected by environment.

Exact analytic solution of position-dependent mass Schrödinger equation

NASA Astrophysics Data System (ADS)

Rajbongshi, Hangshadhar

2018-03-01

Exact analytic solution of position-dependent mass Schrödinger equation is generated by using extended transformation, a method of mapping a known system into a new system equipped with energy eigenvalues and corresponding wave functions. First order transformation is performed on D-dimensional radial Schrödinger equation with constant mass by taking trigonometric Pöschl-Teller potential as known system. The exactly solvable potentials with position-dependent mass generated for different choices of mass functions through first order transformation are also taken as known systems in the second order transformation performed on D-dimensional radial position-dependent mass Schrödinger equation. The solutions are fitted for "Zhu and Kroemer" ordering of ambiguity. All the wave functions corresponding to nonzero energy eigenvalues are normalizable. The new findings are that the normalizability condition of the wave functions remains independent of mass functions, and some of the generated potentials show a family relationship among themselves where power law potentials also get related to non-power law potentials and vice versa through the transformation.

Band-to-band transitions, selection rules, effective mass, and excitonic contributions in monoclinic β -Ga2O3

NASA Astrophysics Data System (ADS)

Mock, Alyssa; Korlacki, Rafał; Briley, Chad; Darakchieva, Vanya; Monemar, Bo; Kumagai, Yoshinao; Goto, Ken; Higashiwaki, Masataka; Schubert, Mathias

2017-12-01

We employ an eigenpolarization model including the description of direction dependent excitonic effects for rendering critical point structures within the dielectric function tensor of monoclinic β -Ga2O3 yielding a comprehensive analysis of generalized ellipsometry data obtained from 0.75-9 eV. The eigenpolarization model permits complete description of the dielectric response. We obtain, for single-electron and excitonic band-to-band transitions, anisotropic critical point model parameters including their polarization vectors within the monoclinic lattice. We compare our experimental analysis with results from density functional theory calculations performed using the Gaussian-attenuation-Perdew-Burke-Ernzerhof hybrid density functional. We present and discuss the order of the fundamental direct band-to-band transitions and their polarization selection rules, the electron and hole effective mass parameters for the three lowest band-to-band transitions, and their excitonic contributions. We find that the effective masses for holes are highly anisotropic and correlate with the selection rules for the fundamental band-to-band transitions. The observed transitions are polarized close to the direction of the lowest hole effective mass for the valence band participating in the transition.

Magnetotransport properties of MoP 2

DOE PAGES

Wang, Aifeng; Graf, D.; Stein, Aaron; ...

2017-11-02

We report magnetotransport and de Haas–van Alphen (dHvA) effect studies on MoP 2 single crystals, predicted to be a type- II Weyl semimetal with four pairs of robust Weyl points located below the Fermi level and long Fermi arcs. The temperature dependence of resistivity shows a peak before saturation, which does not move with magnetic field. Large nonsaturating magnetoresistance (MR) was observed, and the field dependence of MR exhibits a crossover from semiclassical weak-field B 2 dependence to the high-field linear-field dependence, indicating the presence of Dirac linear energy dispersion. In addition, a systematic violation of Kohler's rule was observed,more » consistent with multiband electronic transport. Strong spin-orbit coupling splitting has an effect on dHvA measurements whereas the angular-dependent dHvA orbit frequencies agree well with the calculated Fermi surface. The cyclotron effective mass ~1.6m e indicates the bands might be trivial, possibly since the Weyl points are located below the Fermi level.« less

Temperature dependence of standard model CP violation.

PubMed

Brauner, Tomáš; Taanila, Olli; Tranberg, Anders; Vuorinen, Aleksi

2012-01-27

We analyze the temperature dependence of CP violation effects in the standard model by determining the effective action of its bosonic fields, obtained after integrating out the fermions from the theory and performing a covariant gradient expansion. We find nonvanishing CP violating terms starting at the sixth order of the expansion, albeit only in the C-odd-P-even sector, with coefficients that depend on quark masses, Cabibbo-Kobayashi-Maskawa matrix elements, temperature and the magnitude of the Higgs field. The CP violating effects are observed to decrease rapidly with temperature, which has important implications for the generation of a matter-antimatter asymmetry in the early Universe. Our results suggest that the cold electroweak baryogenesis scenario may be viable within the standard model, provided the electroweak transition temperature is at most of order 1 GeV.

Dynamic Effective Mass of Granular Media

NASA Astrophysics Data System (ADS)

Hsu, Chaur-Jian; Johnson, David L.; Ingale, Rohit A.; Valenza, John J.; Gland, Nicolas; Makse, Hernán A.

2009-02-01

We develop the concept of frequency dependent effective mass, Mtilde (ω), of jammed granular materials which occupy a rigid cavity to a filling fraction of 48%, the remaining volume being air of normal room condition or controlled humidity. The dominant features of Mtilde (ω) provide signatures of the dissipation of acoustic modes, elasticity, and aging effects in the granular medium. We perform humidity controlled experiments and interpret the data in terms of a continuum model and a “trap” model of thermally activated capillary bridges at the contact points. The results suggest that attenuation of acoustic waves in granular materials can be influenced significantly by the kinetics of capillary condensation between the asperities at the contacts.

Non-standard neutrino interactions in the mu–tau sector

DOE PAGES

Mocioiu, Irina; Wright, Warren

2015-04-01

We discuss neutrino mass hierarchy implications arising from the effects of non-standard neutrino interactions on muon rates in high statistics atmospheric neutrino oscillation experiments like IceCube DeepCore. We concentrate on the mu–tau sector, which is presently the least constrained. It is shown that the magnitude of the effects depends strongly on the sign of the ϵμτ parameter describing this non-standard interaction. A simple analytic model is used to understand the parameter space where differences between the two signs are maximized. We discuss how this effect is partially degenerate with changing the neutrino mass hierarchy, as well as how this degeneracymore » could be lifted.« less

Energy scale of compositional disorder in Ga(AsBi)

NASA Astrophysics Data System (ADS)

Shakfa, M. K.; Jandieri, K.; Wiemer, M.; Ludewig, P.; Volz, K.; Stolz, W.; Baranovskii, S. D.; Koch, M.

2015-10-01

We report on a study of compositional disorder in Ga(AsBi) structures. Temperature-dependent photoluminescence measurements on Ga(AsBi)/GaAs heterostructures with different Bi contents are performed. Experimental observations show an essentially non-monotonous dependence of the energy scale of disorder on the Bi content. Our theoretical analysis concludes that this peculiar behavior is a consequence of an essential bowing of the valence band edge as a function of Bi content and of a specific compositional dependence of the hole effective mass in Ga(AsBi) compounds.

Evaluation of species-dependent detection efficiencies in the aerosol mass spectrometer

USDA-ARS?s Scientific Manuscript database

Mass concentrations of chemical species calculated from the aerosol mass spectrometer (AMS) depend on two factors: particle collection efficiency (CE) and relative ionization efficiency (RIE, relative to the primary calibrant ammonium nitrate). While previous studies have characterized CE, RIE is re...

Mean-field study of hot β -stable protoneutron star matter: Impact of the symmetry energy and nucleon effective mass

NASA Astrophysics Data System (ADS)

Tan, Ngo Hai; Loan, Doan Thi; Khoa, Dao T.; Margueron, Jerome

2016-03-01

A consistent Hartree-Fock study of the equation of state (EOS) of asymmetric nuclear matter at finite temperature has been performed using realistic choices of the effective, density-dependent nucleon-nucleon (NN ) interaction, which were successfully used in different nuclear structure and reaction studies. Given the importance of the nuclear symmetry energy in the neutron star formation, EOSs associated with different behaviors of the symmetry energy were used to study hot asymmetric nuclear matter. The slope of the symmetry energy and nucleon effective mass with increasing baryon density was found to affect the thermal properties of nuclear matter significantly. Different density-dependent NN interactions were further used to study the EOS of hot protoneutron star (PNS) matter of the n p e μ ν composition in β equilibrium. The hydrostatic configurations of PNS in terms of the maximal gravitational mass Mmax and radius, central density, pressure, and temperature at the total entropy per baryon S /A =1 ,2 , and 4 have been determined in both the neutrino-free and neutrino-trapped scenarios. The obtained results show consistently a strong impact of the symmetry energy and nucleon effective mass on thermal properties and composition of hot PNS matter. Mmax values obtained for the (neutrino-free) β -stable PNS at S /A =4 were used to assess time tBH of the collapse of a 40 M⊙ protoneutron progenitor to a black hole, based on a correlation between tBH and Mmax found from the hydrodynamic simulation by Hempel et al. [Astrophys. J. 748, 70 (2012), 10.1088/0004-637X/748/1/70].

Long-term exercise in mice has sex-dependent benefits on body composition and metabolism during aging.

PubMed

McMullan, Rachel C; Kelly, Scott A; Hua, Kunjie; Buckley, Brian K; Faber, James E; Pardo-Manuel de Villena, Fernando; Pomp, Daniel

2016-11-01

Aging is associated with declining exercise and unhealthy changes in body composition. Exercise ameliorates certain adverse age-related physiological changes and protects against many chronic diseases. Despite these benefits, willingness to exercise and physiological responses to exercise vary widely, and long-term exercise and its benefits are difficult and costly to measure in humans. Furthermore, physiological effects of aging in humans are confounded with changes in lifestyle and environment. We used C57BL/6J mice to examine long-term patterns of exercise during aging and its physiological effects in a well-controlled environment. One-year-old male (n = 30) and female (n = 30) mice were divided into equal size cohorts and aged for an additional year. One cohort was given access to voluntary running wheels while another was denied exercise other than home cage movement. Body mass, composition, and metabolic traits were measured before, throughout, and after 1 year of treatment. Long-term exercise significantly prevented gains in body mass and body fat, while preventing loss of lean mass. We observed sex-dependent differences in body mass and composition trajectories during aging. Wheel running (distance, speed, duration) was greater in females than males and declined with age. We conclude that long-term exercise may serve as a preventive measure against age-related weight gain and body composition changes, and that mouse inbred strains can be used to characterize effects of long-term exercise and factors (e.g. sex, age) modulating these effects. These findings will facilitate studies on relationships between exercise and health in aging populations, including genetic predisposition and genotype-by-environment interactions. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Development of dissipative elastic metamaterials based on the layered cantilever-in-mass structure for attenuating the broad spectrum vibrations

NASA Astrophysics Data System (ADS)

Wang, Jun; Zhou, Xiaoqin; Wang, Rongqi; Lin, Jieqiong

2018-05-01

In this paper, the layered cantilever-in-mass structures (LCIMs) will be theoretically investigated to reveal the effects of the layered structures on band gaps, which have great potential to bring in many useful material properties without much increasing the manufacturing difficulty by stacking the damped layers or other different component layers. Firstly, the negative effective mass model of LCIMs is derived based on the mass-in-mass model, which is applied to analyze the effective parameters of band gaps in terms of the geometrical features and material properties, the analytical results indicate the negative effective masses of LCIMs depend highly on the material parameter and thicknesses of each constituent layers. Then the LCIMs consist of the same thickness layers are further researched, which has found that their resonance frequency are independent on the layer thickness, and the numeric values of resonance frequencies are between the maximum and minimum local resonance frequency of their constituent layers. To validate the above analytical model, the three-dimensional model and the two-dimensional shell model of LCIMs are constructed in COMSOL Multiphysics. The obtained results show well agreement with the derived model in both the three-dimensional model and shell model. Finally, the dissipative LCIMs modeled by stacking the damped layers and metal layers are studied and discussed.

ON THE HORSESHOE DRAG OF A LOW-MASS PLANET. I. MIGRATION IN ISOTHERMAL DISKS

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

Casoli, J.; Masset, F. S., E-mail: jules.casoli@cea.f, E-mail: frederic.masset@cea.f, E-mail: jules.casoli@cea.f

2009-09-20

We investigate the unsaturated horseshoe drag exerted on a low-mass planet by an isothermal gaseous disk. In the globally isothermal case, we use a formalism, based on the use of a Bernoulli invariant, that takes into account pressure effects, and that extends the torque estimate to a region wider than the horseshoe region. We find a result that is strictly identical to the standard horseshoe drag. This shows that the horseshoe drag accounts for the torque of the whole corotation region, and not only of the horseshoe region, thereby deserving to be called corotation torque. We find that evanescent wavesmore » launched downstream of the horseshoe U-turns by the perturbations of vortensity exert a feedback on the upstream region, that render the horseshoe region asymmetric. This asymmetry scales with the vortensity gradient and with the disk's aspect ratio. It does not depend on the planetary mass, and it does not have any impact on the horseshoe drag. Since the horseshoe drag has a steep dependence on the width of the horseshoe region, we provide an adequate definition of the width that needs to be used in horseshoe drag estimates. We then consider the case of locally isothermal disks, in which the temperature is constant in time but depends on the distance to the star. The horseshoe drag appears to be different from the case of a globally isothermal disk. The difference, which is due to the driving of vortensity in the vicinity of the planet, is intimately linked to the topology of the flow. We provide a descriptive interpretation of these effects, as well as a crude estimate of the dependency of the excess on the temperature gradient.« less

Electrostatic control of the coffee stain effect

NASA Astrophysics Data System (ADS)

Wray, Alex; Papageorgiou, Demetrios; Sefiane, Khellil; Matar, Omar

2013-11-01

The ``coffee stain effect,'' as first explained by Deegan et al. 1997, has received a great deal of attention amongst modellers and experimentalists in recent years, perhaps due in part to its obvious casual familiarity. However, it maintains interest because of its intriguing reliance on an interplay of a trio of effects: contact line pinning, inhomogeneous mass flux, and resulting capillarity-driven flow. What is more, the effect, and especially its suppression or reversal, find applications in fields as diverse as sample recovery, mass spectroscopy and the printing of Organic LEDs. We examine the motion a nanoparticle-laden droplet deposited on a precursor film, incorporating the effects of capillarity, concentration-dependent rheology, together with a heated substrate and resultant mass flux and Marangoni effects. We allow the substrate to act as an electrode and incorporate a second electrode above the droplet. The potential difference together with a disparity in electrical properties between the two regions results in electrical (Maxwell) stresses at the interface. We show via lubrication theory and via direct numerical simulations that the ring effect typically observed may be suppressed or augmented via appropriate use of electric fields. EPSRC DTG

Effective density and morphology of particles emitted from small-scale combustion of various wood fuels.

PubMed

Leskinen, Jani; Ihalainen, Mika; Torvela, Tiina; Kortelainen, Miika; Lamberg, Heikki; Tiitta, Petri; Jakobi, Gert; Grigonyte, Julija; Joutsensaari, Jorma; Sippula, Olli; Tissari, Jarkko; Virtanen, Annele; Zimmermann, Ralf; Jokiniemi, Jorma

2014-11-18

The effective density of fine particles emitted from small-scale wood combustion of various fuels were determined with a system consisting of an aerosol particle mass analyzer and a scanning mobility particle sizer (APM-SMPS). A novel sampling chamber was combined to the system to enable measurements of highly fluctuating combustion processes. In addition, mass-mobility exponents (relates mass and mobility size) were determined from the density data to describe the shape of the particles. Particle size, type of fuel, combustion phase, and combustion conditions were found to have an effect on the effective density and the particle shape. For example, steady combustion phase produced agglomerates with effective density of roughly 1 g cm(-3) for small particles, decreasing to 0.25 g cm(-3) for 400 nm particles. The effective density was higher for particles emitted from glowing embers phase (ca. 1-2 g cm(-3)), and a clear size dependency was not observed as the particles were nearly spherical in shape. This study shows that a single value cannot be used for the effective density of particles emitted from wood combustion.

Influence of viscoelastic nature on the intermittent peel-front dynamics of adhesive tape

NASA Astrophysics Data System (ADS)

Kumar, Jagadish; Ananthakrishna, G.

2010-07-01

We investigate the influence of viscoelastic nature of the adhesive on the intermittent peel front dynamics by extending a recently introduced model for peeling of an adhesive tape. As time and rate-dependent deformation of the adhesives are measured in stationary conditions, a crucial step in incorporating the viscoelastic effects applicable to unstable intermittent peel dynamics is the introduction of a dynamization scheme that eliminates the explicit time dependence in terms of dynamical variables. We find contrasting influences of viscoelastic contribution in different regions of tape mass, roller inertia, and pull velocity. As the model acoustic energy dissipated depends on the nature of the peel front and its dynamical evolution, the combined effect of the roller inertia and pull velocity makes the acoustic energy noisier for small tape mass and low-pull velocity while it is burstlike for low-tape mass, intermediate values of the roller inertia and high-pull velocity. The changes are quantified by calculating the largest Lyapunov exponent and analyzing the statistical distributions of the amplitudes and durations of the model acoustic energy signals. Both single and two stage power-law distributions are observed. Scaling relations between the exponents are derived which show that the exponents corresponding to large values of event sizes and durations are completely determined by those for small values. The scaling relations are found to be satisfied in all cases studied. Interestingly, we find only five types of model acoustic emission signals among multitude of possibilities of the peel front configurations.

Isotope effects on L-H threshold and confinement in tokamak plasmas

NASA Astrophysics Data System (ADS)

Maggi, C. F.; Weisen, H.; Hillesheim, J. C.; Chankin, A.; Delabie, E.; Horvath, L.; Auriemma, F.; Carvalho, I. S.; Corrigan, G.; Flanagan, J.; Garzotti, L.; Keeling, D.; King, D.; Lerche, E.; Lorenzini, R.; Maslov, M.; Menmuir, S.; Saarelma, S.; Sips, A. C. C.; Solano, E. R.; Belonohy, E.; Casson, F. J.; Challis, C.; Giroud, C.; Parail, V.; Silva, C.; Valisa, M.; Contributors, JET

2018-01-01

The dependence of plasma transport and confinement on the main hydrogenic ion isotope mass is of fundamental importance for understanding turbulent transport and, therefore, for accurate extrapolations of confinement from present tokamak experiments, which typically use a single hydrogen isotope, to burning plasmas such as ITER, which will operate in deuterium-tritium mixtures. Knowledge of the dependence of plasma properties and edge transport barrier formation on main ion species is critical in view of the initial, low-activation phase of ITER operations in hydrogen or helium and of its implications on the subsequent operation in deuterium-tritium. The favourable scaling of global energy confinement time with isotope mass, which has been observed in many tokamak experiments, remains largely unexplained theoretically. Moreover, the mass scaling observed in experiments varies depending on the plasma edge conditions. In preparation for upcoming deuterium-tritium experiments in the JET tokamak with the ITER-like Be/W Wall (JET-ILW), a thorough experimental investigation of isotope effects in hydrogen, deuterium and tritium plasmas is being carried out, in order to provide stringent tests of plasma energy, particle and momentum transport models. Recent hydrogen and deuterium isotope experiments in JET-ILW on L-H power threshold, L-mode and H-mode confinement are reviewed and discussed in the context of past and more recent isotope experiments in tokamak plasmas, highlighting common elements as well as contrasting observations that have been reported. The experimental findings are discussed in the context of fundamental aspects of plasma transport models.

Force properties of skinned cardiac muscle following increasing volumes of aerobic exercise in rats.

PubMed

Boldt, Kevin Rudi; Rios, Jaqueline Lourdes; Joumaa, Venus; Herzog, Walter

2018-05-03

The positive effects of chronic endurance exercise training on health and performance have been well documented. These positive effects have been evaluated primarily at the structural level, and work has begun to evaluate mechanical adaptations of the myocardium. However, it remains poorly understood how the volume of exercise training affects cardiac adaptation. In order to gain some understanding, we subjected three-month-old Sprague-Dawley rats (N=23) to treadmill running for eleven weeks at one of three exercise volumes (moderate, high, and extra high). Following training, hearts were excised and mechanical testing was completed on skinned trabecular fiber bundles. Performance on a maximal fitness test was dose-dependent upon training volume, where greater levels of training led to greater performance. No differences were observed between animals from any group for active stress production. Heart mass and passive stress increases in a dose-dependent manner for animals in the control, moderate, and high duration groups. However, hearts from animals in the extra high duration group presented with inhibited responses for heart mass and passive stress, despite performing greatest on a graded treadmill fitness test. These results suggest that heart mass and passive stress adapt in a dose-dependent manner, until exercise becomes excessive and adaptation is inhibited. Our findings are in agreement with the beneficial role exercise has in cardiac adaptation. However, excessive exercise comes with risks of maladaptation which must be weighed against the desire to increase performance.

Properties of nuclear matter from macroscopic-microscopic mass formulas

NASA Astrophysics Data System (ADS)

Wang, Ning; Liu, Min; Ou, Li; Zhang, Yingxun

2015-12-01

Based on the standard Skyrme energy density functionals together with the extended Thomas-Fermi approach, the properties of symmetric and asymmetric nuclear matter represented in two macroscopic-microscopic mass formulas: Lublin-Strasbourg nuclear drop energy (LSD) formula and Weizsäcker-Skyrme (WS*) formula, are extracted through matching the energy per particle of finite nuclei. For LSD and WS*, the obtained incompressibility coefficients of symmetric nuclear matter are K∞ = 230 ± 11 MeV and 235 ± 11 MeV, respectively. The slope parameter of symmetry energy at saturation density is L = 41.6 ± 7.6 MeV for LSD and 51.5 ± 9.6 MeV for WS*, respectively, which is compatible with the liquid-drop analysis of Lattimer and Lim [4]. The density dependence of the mean-field isoscalar and isovector effective mass, and the neutron-proton effective masses splitting for neutron matter are simultaneously investigated. The results are generally consistent with those from the Skyrme Hartree-Fock-Bogoliubov calculations and nucleon optical potentials, and the standard deviations are large and increase rapidly with density. A better constraint for the effective mass is helpful to reduce uncertainties of the depth of the mean-field potential.

Analyzing fragment production in mass-asymmetric reactions as a function of density dependent part of symmetry energy

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

Kaur, Amandeep; Deepshikha; Vinayak, Karan Singh

2016-07-15

We performed a theoretical investigation of different mass-asymmetric reactions to access the direct impact of the density-dependent part of symmetry energy on multifragmentation. The simulations are performed for a specific set of reactions having same system mass and N/Z content, using isospin-dependent quantum molecular dynamics model to estimate the quantitative dependence of fragment production on themass-asymmetry factor (τ) for various symmetry energy forms. The dynamics associated with different mass-asymmetric reactions is explored and the direct role of symmetry energy is checked. Also a comparison with the experimental data (asymmetric reaction) is presented for a different equation of states (symmetry energymore » forms).« less

Influence of muscle strength, physical activity and weight on bone mass in a population-based sample of 1004 elderly women.

PubMed

Gerdhem, P; Ringsberg, K A M; Akesson, K; Obrant, K J

2003-09-01

High physical activity level has been associated with high bone mass and low fracture risk and is therefore recommended to reduce fractures in old age. The aim of this study was to estimate the effect of potentially modifiable variables, such as physical activity, muscle strength, muscle mass and weight, on bone mass in elderly women. The influence of isometric thigh muscle strength, self-estimated activity level, body composition and weight on bone mineral density (dual energy X-ray absorptiometry; DXA) in total body, hip and spine was investigated. Subjects were 1004 women, all 75 years old, taking part in the Malmö Osteoporosis Prospective Risk Assessment (OPRA) study. Physical activity and muscle strength accounted for 1-6% of the variability in bone mass, whereas weight, and its closely associated variables lean mass and fat mass, to a much greater extent explained the bone mass variability. We found current body weight to be the variable with the most substantial influence on the total variability in bone mass (15-32% depending on skeletal site) in a forward stepwise regression model. Our findings suggest that in elderly women, the major fracture-preventive effect of physical activity is unlikely to be mediated through increased bone mass. Retaining or even increasing body weight is likely to be beneficial to the skeleton, but an excess body weight increase may have negative effects on health. Nevertheless, training in elderly women may have advantages by improving balance, co-ordination and mobility and therefore decreasing the risk of fractures.

New Equations of State Based on the Liquid Drop Model of Heavy Nuclei and Quantum Approach to Light Nuclei for Core-collapse Supernova Simulations

NASA Astrophysics Data System (ADS)

Furusawa, Shun; Sumiyoshi, Kohsuke; Yamada, Shoichi; Suzuki, Hideyuki

2013-08-01

We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to ~1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.

Effects of exendin-4 on glucose tolerance, insulin secretion, and beta-cell proliferation depend on treatment dose, treatment duration and meal contents

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

Arakawa, Masayuki; Ebato, Chie; Mita, Tomoya

2009-12-18

Beta-cell proliferation is regulated by various metabolic demands including peripheral insulin resistance, obesity, and hyperglycemia. In addition to enhancement of glucose-induced insulin secretion, agonists for glucagon-like peptide-1 receptor (GLP-1R) stimulate proliferation and inhibit apoptosis of beta-cells, thereby probably preserve beta-cell mass. To evaluate the beta-cell preserving actions of GLP-1R agonists, we assessed the acute and chronic effects of exendin-4 on beta-cell proliferation, mass and glucose tolerance in C57BL/6J mice under various conditions. Short-term administration of high-dose exendin-4 transiently stimulated beta-cell proliferation. Comparative transcriptomic analysis showed upregulation of IGF-1 receptor and its downstream effectors in islets. Treatment of mice with exendin-4more » daily for 4 weeks (long-term administration) and feeding high-fat diet resulted in significant inhibition of weight gain and improvement of glucose tolerance with reduced insulin secretion and beta-cell mass. These findings suggest that long-term GLP-1 treatment results in insulin sensitization of peripheral organs, rather than enhancement of beta-cell proliferation and function, particularly when animals are fed high-fat diet. Thus, the effects of exendin-4 on glucose tolerance, insulin secretion, and beta-cell proliferation largely depend on treatment dose, duration of treatment and meal contents. While GLP-1 enhances proliferation of beta-cells in some diabetic mice models, our results suggest that GLP-1 stimulates beta-cell growth only when expansion of beta-cell mass is required to meet metabolic demands.« less

Vacuum drying of apples (cv. Golden Delicious): drying characteristics, thermodynamic properties, and mass transfer parameters

NASA Astrophysics Data System (ADS)

Nadi, Fatemeh; Tzempelikos, Dimitrios

2018-01-01

In this work, apples of cv. Golden Delicious were cut into slices that were 5 and 7 mm thick and then vacuum dried at 50, 60 and 70 °C and pressure of 0.02 bar. The thin layer model drying kinetics was studied, and mass transfer properties, specifically effective moisture diffusivity and convective mass transfer coefficient, were evaluated using the Fick's equation of diffusion. Also, thermodynamic parameters of the process, i.e. enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG), were determined. Colour properties were evaluated as one of the important indicators of food quality and marketability. Determination of mass transfer parameters and thermodynamic properties of vacuum dried apple slices has not been discussed much in the literature. In conclusion, the Nadi's model fitted best the observed data that represent the drying process. Thermodynamic properties were determined based on the dependence of the drying constant of the Henderson and Pabis model on temperature, and it was concluded that the variation in drying kinetics depends on the energy contribution of the surrounding environment. The enthalpy and entropy diminished, while the Gibbs free energy increased with the increase of the temperature of drying; therefore, it was possible to verify that variation in the diffusion process in the apple during drying depends on energetic contributions of the environment. The obtained results showed that diffusivity increased for 69%, while the mass transfer coefficient increase was even higher, 75%, at the variation of temperature of 20 °C. The increase in the dimensionless Biot number was 20%.

Vacuum drying of apples (cv. Golden Delicious): drying characteristics, thermodynamic properties, and mass transfer parameters

NASA Astrophysics Data System (ADS)

Nadi, Fatemeh; Tzempelikos, Dimitrios

2018-07-01

In this work, apples of cv. Golden Delicious were cut into slices that were 5 and 7 mm thick and then vacuum dried at 50, 60 and 70 °C and pressure of 0.02 bar. The thin layer model drying kinetics was studied, and mass transfer properties, specifically effective moisture diffusivity and convective mass transfer coefficient, were evaluated using the Fick's equation of diffusion. Also, thermodynamic parameters of the process, i.e. enthalpy ( ΔH), entropy ( ΔS) and Gibbs free energy ( ΔG), were determined. Colour properties were evaluated as one of the important indicators of food quality and marketability. Determination of mass transfer parameters and thermodynamic properties of vacuum dried apple slices has not been discussed much in the literature. In conclusion, the Nadi's model fitted best the observed data that represent the drying process. Thermodynamic properties were determined based on the dependence of the drying constant of the Henderson and Pabis model on temperature, and it was concluded that the variation in drying kinetics depends on the energy contribution of the surrounding environment. The enthalpy and entropy diminished, while the Gibbs free energy increased with the increase of the temperature of drying; therefore, it was possible to verify that variation in the diffusion process in the apple during drying depends on energetic contributions of the environment. The obtained results showed that diffusivity increased for 69%, while the mass transfer coefficient increase was even higher, 75%, at the variation of temperature of 20 °C. The increase in the dimensionless Biot number was 20%.

Mass enhances speed but diminishes turn capacity in terrestrial pursuit predators.

PubMed

Wilson, Rory P; Griffiths, Iwan W; Mills, Michael G L; Carbone, Chris; Wilson, John W; Scantlebury, David M

2015-08-07

The dynamics of predator-prey pursuit appears complex, making the development of a framework explaining predator and prey strategies problematic. We develop a model for terrestrial, cursorial predators to examine how animal mass modulates predator and prey trajectories and affects best strategies for both parties. We incorporated the maximum speed-mass relationship with an explanation of why larger animals should have greater turn radii; the forces needed to turn scale linearly with mass whereas the maximum forces an animal can exert scale to a 2/3 power law. This clarifies why in a meta-analysis, we found a preponderance of predator/prey mass ratios that minimized the turn radii of predators compared to their prey. It also explained why acceleration data from wild cheetahs pursuing different prey showed different cornering behaviour with prey type. The outcome of predator prey pursuits thus depends critically on mass effects and the ability of animals to time turns precisely.

Prediction of Test Mass Thermal Noise by Measurement of the Anelastic Aftereffect

NASA Astrophysics Data System (ADS)

Beilby, Mark A.; Saulson, Peter R.; Abramovici, Alex

1997-04-01

The thermal noise from the internal modes of test masses of interferometric gravitational wave detectors depends on the dissipation at the frequencies of interest. To date, predictions have been based on the Qs of resonances, all at frequencies higher than the expected signals. We have developed a method to determine the dissipation of test masses in the signal band, using the anelastic aftereffect, the creep J(τ) of a test mass after a compressive stress has been released. The loss angle φ(ω) is approximately given by the logarithmic derivative of J(τ) evaluated at τ=1/ω. For a transparent material such as fused silica, a convenient way to measure J(τ) is via the photoelastic effect. We will describe the apparatus that we have constructed, present measurements of the losses in dummy test masses made from BK7 glass and fused silica, and discuss the application of this method to LIGO test masses.

Prediction of Test Mass Thermal Noise by Measurement of the Anelastic Aftereffect

NASA Astrophysics Data System (ADS)

Beilby, Mark A.; Saulson, Peter R.; Abramovici, Alex

1996-05-01

The thermal noise from the internal modes of the test masses of interferometric gravitational wave detectors depends on the dissipation at the frequencies of interest. To date, predictions have been based on the Q's of resonances, all at frequencies higher than the expected signals. We have developed a method to determine the dissipation of test masses in the signal band, using the anelastic aftereffect, the creep J(τ) of a test mass after a compressive stress has been released. The loss angle φ(ω) is approximately given by the logarithmic derivative of J(τ) evaluated at τ = 1/ω. For a transparent material such as fused silica, a convenient way to measure J(τ) is via the photoelastic effect. We will describe the apparatus that we have constructed, present measurements of the losses in a dummy test mass made from BK7 glass, and discuss the application of this method to LIGO test masses.

The role of environment in the observed Fundamental Plane of radio Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Shabala, Stanislav S.

2018-05-01

The optical Fundamental Plane of black hole activity relates radio continuum luminosity of Active Galactic Nuclei to [O III] luminosity and black hole mass. We examine the environments of low redshift (z < 0.2) radio-selected AGN, quantified through galaxy clustering, and find that halo mass provides similar mass scalings to black hole mass in the Fundamental Plane relations. AGN properties are strongly environment-dependent: massive haloes are more likely to host radiatively inefficient (low-excitation) radio AGN, as well as a higher fraction of radio luminous, extended sources. These AGN populations have different radio - optical luminosity scaling relations, and the observed mass scalings in the parent AGN sample are built up by combining populations preferentially residing in different environments. Accounting for environment-driven selection effects, the optical Fundamental Plane of supermassive black holes is likely to be mass-independent, as predicted by models.

The mass function and dynamical mass of young star clusters: why their initial crossing-time matters crucially

NASA Astrophysics Data System (ADS)

Parmentier, Geneviève; Baumgardt, Holger

2012-12-01

We highlight the impact of cluster-mass-dependent evolutionary rates upon the evolution of the cluster mass function during violent relaxation, that is, while clusters dynamically respond to the expulsion of their residual star-forming gas. Mass-dependent evolutionary rates arise when the mean volume density of cluster-forming regions is mass-dependent. In that case, even if the initial conditions are such that the cluster mass function at the end of violent relaxation has the same shape as the embedded-cluster mass function (i.e. infant weight-loss is mass-independent), the shape of the cluster mass function does change transiently during violent relaxation. In contrast, for cluster-forming regions of constant mean volume density, the cluster mass function shape is preserved all through violent relaxation since all clusters then evolve at the same mass-independent rate. On the scale of individual clusters, we model the evolution of the ratio of the dynamical mass to luminous mass of a cluster after gas expulsion. Specifically, we map the radial dependence of the time-scale for a star cluster to return to equilibrium. We stress that fields of view a few pc in size only, typical of compact clusters with rapid evolutionary rates, are likely to reveal cluster regions which have returned to equilibrium even if the cluster experienced a major gas expulsion episode a few Myr earlier. We provide models with the aperture and time expressed in units of the initial half-mass radius and initial crossing-time, respectively, so that our results can be applied to clusters with initial densities, sizes, and apertures different from ours.

Asymmetry dependence of the caloric curve for mononuclei

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

Hoel, C.; Sobotka, L. G.; Charity, R. J.

2007-01-15

The asymmetry dependence of the caloric curve, for mononuclear configurations, is studied as a function of neutron-to-proton asymmetry with a model that allows for independent variation of the neutron and proton surface diffusenesses. The evolution of the effective mass with density and excitation is included in a schematic fashion and the entropies are extracted in a local density approximation. The plateau in the caloric curve displays only a slight sensitivity to the asymmetry.

Field validation of recycled concrete fines usage.

DOT National Transportation Integrated Search

2015-03-01

The amount of recycled concrete fines permitted in concrete mixing water is limited by ASTM C 1602 to 5.0 percent of the mixing : water, by mass, in order to avoid detrimental effects on concrete properties. Depending upon the exact nature of the rec...

Excitation energy dependence of fragment-mass distributions from fission of 180,190Hg formed in fusion reactions of 36Ar + 144,154Sm

DOE PAGES

Nishio, K.; Andreyev, A. N.; Chapman, R.; ...

2015-06-30

Mass distributions of fission fragments from the compound nuclei 180Hg and 190 Hg formed in fusion reactions 36Ar + 144 Smand 36Ar + 154Sm, respectively, were measured at initial excitation energies of E*( 180Hg) = 33-66 MeV and E*( 190Hg) = 48-71 MeV. In the fission of 180Hg, the mass spectra were well reproduced by assuming only an asymmetric-mass division, with most probable light and heavy fragment masses more » $$\\overline{A}_L$$/ $$\\overline{A}_H$$ = 79/101. The mass asymmetry for 180Hg agrees well with that obtained in the low-energy β +/EC-delayed fission of 180Tl, from our earlier ISOLDE(CERN) experiment. Fission of 190Hg is found to proceed in a similar way, delivering the mass asymmetry of $$\\overline{A}_L$$/ $$\\overline{A}_H$$ = 83/107, throughout the measured excitation energy range. The persistence as a function of excitation energy of the mass-asymmetric fission for both proton-rich Hg isotopes gives strong evidence for the survival of microscopic effects up to effective excitation energies of compound nuclei as high as 40 MeV. In conclusion, this behavior is different from fission of actinide nuclei and heavier mercury isotope 198Hg.« less

Quantum effects of nuclear motion in three-particle diatomic ions

NASA Astrophysics Data System (ADS)

Baskerville, Adam L.; King, Andrew W.; Cox, Hazel

2016-10-01

A high-accuracy, nonrelativistic wave function is used to study nuclear motion in the ground state of three-particle {a1+a2+a3-} electronic and muonic molecular systems without assuming the Born-Oppenheimer approximation. Intracule densities and center-of-mass particle densities show that as the mass ratio mai/ma3 , i =1 ,2 , becomes smaller, the localization of the like-charged particles (nuclei) a1 and a2 decreases. A coordinate system is presented to calculate center-of-mass particle densities for systems where a1≠a2 . It is shown that the nuclear motion is strongly correlated and depends on the relative masses of the nuclei a1 and a2 rather than just their absolute mass. The heavier particle is always more localized and the lighter the partner mass, the greater the localization. It is shown, for systems with ma1

Solar System and stellar tests of a quantum-corrected gravity

NASA Astrophysics Data System (ADS)

Zhao, Shan-Shan; Xie, Yi

2015-09-01

The renormalization group running of the gravitational constant has a universal form and represents a possible extension of general relativity. These renormalization group effects on general relativity will cause the running of the gravitational constant, and there exists a scale of renormalization α ν , which depends on the mass of an astronomical system and needs to be determined by observations. We test renormalization group effects on general relativity and obtain the upper bounds of α ν in the low-mass scales: the Solar System and five systems of binary pulsars. Using the supplementary advances of the perihelia provided by INPOP10a (IMCCE, France) and EPM2011 (IAA RAS, Russia) ephemerides, we obtain new upper bounds on α ν in the Solar System when the Lense-Thirring effect due to the Sun's angular momentum and the uncertainty of the Sun's quadrupole moment are properly taken into account. These two factors were absent in the previous work. We find that INPOP10a yields the upper bound as α ν =(0.3 ±2.8 )×10-20 while EPM2011 gives α ν =(-2.5 ±8.3 )×10-21. Both of them are tighter than the previous result by 4 orders of magnitude. Furthermore, based on the observational data sets of five systems of binary pulsars: PSR J 0737 -3039 , PSR B 1534 +12 , PSR J 1756 -2251 , PSR B 1913 +16 , and PSR B 2127 +11 C , the upper bound is found as α ν =(-2.6 ±5.1 )×10-17. From the bounds of this work at a low-mass scale and the ones at the mass scale of galaxies, we might catch an updated glimpse of the mass dependence of α ν , and it is found that our improvement of the upper bounds in the Solar System can significantly change the possible pattern of the relation between log |α ν | and log m from a linear one to a power law, where m is the mass of an astronomical system. This suggests that |α ν | needs to be suppressed more rapidly with the decrease of the mass of low-mass systems. It also predicts that |α ν | might have an upper limit in high-mass astrophysical systems, which can be tested in the future.

Study of the dependence of direct soft photon production on the jet characteristics in hadronic Z 0 decays

NASA Astrophysics Data System (ADS)

Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G. J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Buschbeck, B.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crennell, D.; Cuevas, J.; D'Hondt, J.; da Silva, T.; da Silva, W.; Della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Hoffman, J.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Jackson, J. N.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kersevan, B. P.; Kerzel, U.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nemecek, S.; Nicolaidou, R.; Nikolenko, M.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Radojicic, D.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.-L.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zhuravlov, V.; Zimin, N. I.; Zintchenko, A.; Zupan, M.; DELPHI Collaboration

2010-06-01

An analysis of the direct soft photon production rate as a function of the parent jet characteristics is presented, based on hadronic events collected by the DELPHI experiment at LEP1. The dependences of the photon rates on the jet kinematic characteristics (momentum, mass, etc.) and on the jet charged, neutral and total hadron multiplicities are reported. Up to a scale factor of about four, which characterizes the overall value of the soft photon excess, a similarity of the observed soft photon behavior to that of the inner hadronic bremsstrahlung predictions is found for the momentum, mass, and jet charged multiplicity dependences. However for the dependence of the soft photon rate on the jet neutral and total hadron multiplicities a prominent difference is found for the observed soft photon signal as compared to the expected bremsstrahlung from final state hadrons. The observed linear increase of the soft photon production rate with the jet total hadron multiplicity and its strong dependence on the jet neutral multiplicity suggest that the rate is proportional to the number of quark pairs produced in the fragmentation process, with the neutral pairs being more effectively radiating than the charged ones.

Mode Transitions in Hall Effect Thrusters

DTIC Science & Technology

2013-07-01

bM = number of pixels per bin m = spoke order 0m = spoke order m = 0 em = electron mass, 9.1110 -31 kg im = Xe ion mass, 2.18×10 -25...periodogram spectral estimate, Arb Hz -1 eT = electron temperature eT = electron temperature parallel to magnetic field, eV eT  = electron ...Fourier transform of x(t)  = inverse angle from 2D DFT, deg-1  = mean electron energy, eV * = material dependent cross-over energy, eV xy

Remark on Majorana CP phases in neutrino mixing and leptogenesis

NASA Astrophysics Data System (ADS)

Kitabayashi, Teruyuki; Koizumi, Naoto

2014-05-01

We estimate Majorana CP phases for a simple flavor neutrino mixing matrix which has been reported by Qu and Ma. Sizes of Majorana CP phases are evaluated in the study of the neutrinoless double beta decay and a particular leptogenesis scenario. We find the dependence of the physically relevant Majorana CP phase on the mass of lightest right-handed neutrino in the minimal seesaw model and the effective Majorana neutrino mass which is related with the half-life of the neutrinoless double beta decay.

Gauge invariance and kaon production in deep inelastic scattering at low scales

NASA Astrophysics Data System (ADS)

Guerrero, Juan V.; Accardi, Alberto

2018-06-01

This paper focuses on hadron mass effects in calculations of semi-inclusive kaon production in lepton-Deuteron deeply inelastic scattering at HERMES and COMPASS kinematics. In the collinear factorization framework, the corresponding cross section is shown to factorize, at leading order and leading twist, into products of parton distributions and fragmentation functions evaluated in terms of kaon- and nucleon-mass-dependent scaling variables, and to respect gauge invariance. It is found that hadron mass corrections for integrated kaon multiplicities sizeably reduce the apparent large discrepancy between measurements of K++K- multiplicities performed by the two collaborations, and fully reconcile their K+/K- ratios.

Power and weight considerations in small, agile quadrotors

NASA Astrophysics Data System (ADS)

Mulgaonkar, Yash; Whitzer, Michael; Morgan, Brian; Kroninger, Christopher M.; Harrington, Aaron M.; Kumar, Vijay

2014-06-01

The development of autonomous Micro Aerial Vehicles (MAVs) is significantly constrained by their size, weight and power consumption. In this paper, we explore the energetics of quadrotor platforms and study the scaling of mass, inertia, lift and drag with their characteristic length. The effects of length scale on masses and inertias associated with various components are also investigated. Additionally, a study of Lithium Polymer battery performance is presented in terms of specific power and specific energy. Finally, we describe the power and energy consumption for different quadrotors and explore the dependence on size and mass for static hover tests as well as representative maneuvers.

Estimates of the organic aerosol volatility in a boreal forest using two independent methods

NASA Astrophysics Data System (ADS)

Hong, Juan; Äijälä, Mikko; Häme, Silja A. K.; Hao, Liqing; Duplissy, Jonathan; Heikkinen, Liine M.; Nie, Wei; Mikkilä, Jyri; Kulmala, Markku; Prisle, Nønne L.; Virtanen, Annele; Ehn, Mikael; Paasonen, Pauli; Worsnop, Douglas R.; Riipinen, Ilona; Petäjä, Tuukka; Kerminen, Veli-Matti

2017-03-01

The volatility distribution of secondary organic aerosols that formed and had undergone aging - i.e., the particle mass fractions of semi-volatile, low-volatility and extremely low volatility organic compounds in the particle phase - was characterized in a boreal forest environment of Hyytiälä, southern Finland. This was done by interpreting field measurements using a volatility tandem differential mobility analyzer (VTDMA) with a kinetic evaporation model. The field measurements were performed during April and May 2014. On average, 40 % of the organics in particles were semi-volatile, 34 % were low-volatility organics and 26 % were extremely low volatility organics. The model was, however, very sensitive to the vaporization enthalpies assumed for the organics (ΔHVAP). The best agreement between the observed and modeled temperature dependence of the evaporation was obtained when effective vaporization enthalpy values of 80 kJ mol-1 were assumed. There are several potential reasons for the low effective enthalpy value, including molecular decomposition or dissociation that might occur in the particle phase upon heating, mixture effects and compound-dependent uncertainties in the mass accommodation coefficient. In addition to the VTDMA-based analysis, semi-volatile and low-volatility organic mass fractions were independently determined by applying positive matrix factorization (PMF) to high-resolution aerosol mass spectrometer (HR-AMS) data. The factor separation was based on the oxygenation levels of organics, specifically the relative abundance of mass ions at m/z 43 (f43) and m/z 44 (f44). The mass fractions of these two organic groups were compared against the VTDMA-based results. In general, the best agreement between the VTDMA results and the PMF-derived mass fractions of organics was obtained when ΔHVAP = 80 kJ mol-1 was set for all organic groups in the model, with a linear correlation coefficient of around 0.4. However, this still indicates that only about 16 % (R2) of the variation can be explained by the linear regression between the results from these two methods. The prospect of determining of extremely low volatility organic aerosols (ELVOAs) from AMS data using the PMF analysis should be assessed in future studies.

Uncertainties in global aerosols and climate effects due to biofuel emissions

NASA Astrophysics Data System (ADS)

Kodros, J. K.; Scott, C. E.; Farina, S. C.; Lee, Y. H.; L'Orange, C.; Volckens, J.; Pierce, J. R.

2015-04-01

Aerosol emissions from biofuel combustion impact both health and climate; however, while reducing emissions through improvements to combustion technologies will improve health, the net effect on climate is largely unconstrained. In this study, we examine sensitivities in global aerosol concentration, direct radiative climate effect, and cloud-albedo aerosol indirect climate effect to uncertainties in biofuel emission factors, optical mixing-state, and model nucleation and background SOA. We use the Goddard Earth Observing System global chemical-transport model (GEOS-Chem) with TwO Moment Aerosol Sectional (TOMAS) microphysics. The emission factors include: amount, composition, size and hygroscopicity, as well as optical mixing-state properties. We also evaluate emissions from domestic coal use, which is not biofuel but is also frequently emitted from homes. We estimate the direct radiative effect assuming different mixing states (internal, core-shell, and external) with and without absorptive organic aerosol (brown carbon). We find the global-mean direct radiative effect of biofuel emissions ranges from -0.02 to +0.06 W m-2 across all simulation/mixing state combinations with regional effects in source regions ranging from -0.2 to +1.2 W m-2. The global-mean cloud-albedo aerosol indirect effect ranges from +0.01 to -0.02 W m-2 with regional effects in source regions ranging from -1.0 to -0.05 W m-2. The direct radiative effect is strongly dependent on uncertainties in emissions mass, composition, emissions aerosol size distributions and assumed optical mixing state, while the indirect effect is dependent on the emissions mass, emissions aerosol size distribution and the choice of model nucleation and secondary organic aerosol schemes. The sign and magnitude of these effects have a strong regional dependence. We conclude that the climate effects of biofuel aerosols are largely unconstrained, and the overall sign of the aerosol effects is unclear due to uncertainties in model inputs. This uncertainty limits our ability to introduce mitigation strategies aimed at reducing biofuel black carbon emissions in order to counter warming effects from greenhouse-gases. To better understand the climate impact of particle emissions from biofuel combustion, we recommend field/laboratory measurements to narrow constraints on: (1) emissions mass, (2) emission size distribution, (3) mixing state, and (4) ratio of black carbon to organic aerosol.

Uncertainties in global aerosols and climate effects due to biofuel emissions

NASA Astrophysics Data System (ADS)

Kodros, J. K.; Scott, C. E.; Farina, S. C.; Lee, Y. H.; L'Orange, C.; Volckens, J.; Pierce, J. R.

2015-08-01

Aerosol emissions from biofuel combustion impact both health and climate; however, while reducing emissions through improvements to combustion technologies will improve health, the net effect on climate is largely unconstrained. In this study, we examine sensitivities in global aerosol concentration, direct radiative climate effect, and cloud-albedo aerosol indirect climate effect to uncertainties in biofuel emission factors, optical mixing state, and model nucleation and background secondary organic aerosol (SOA). We use the Goddard Earth Observing System global chemical-transport model (GEOS-Chem) with TwO Moment Aerosol Sectional (TOMAS) microphysics. The emission factors include amount, composition, size, and hygroscopicity, as well as optical mixing-state properties. We also evaluate emissions from domestic coal use, which is not biofuel but is also frequently emitted from homes. We estimate the direct radiative effect assuming different mixing states (homogeneous, core-shell, and external) with and without absorptive organic aerosol (brown carbon). We find the global-mean direct radiative effect of biofuel emissions ranges from -0.02 to +0.06 W m-2 across all simulation/mixing-state combinations with regional effects in source regions ranging from -0.2 to +0.8 W m-2. The global-mean cloud-albedo aerosol indirect effect (AIE) ranges from +0.01 to -0.02 W m-2 with regional effects in source regions ranging from -1.0 to -0.05 W m-2. The direct radiative effect is strongly dependent on uncertainties in emissions mass, composition, emissions aerosol size distributions, and assumed optical mixing state, while the indirect effect is dependent on the emissions mass, emissions aerosol size distribution, and the choice of model nucleation and secondary organic aerosol schemes. The sign and magnitude of these effects have a strong regional dependence. We conclude that the climate effects of biofuel aerosols are largely unconstrained, and the overall sign of the aerosol effects is unclear due to uncertainties in model inputs. This uncertainty limits our ability to introduce mitigation strategies aimed at reducing biofuel black carbon emissions in order to counter warming effects from greenhouse gases. To better understand the climate impact of particle emissions from biofuel combustion, we recommend field/laboratory measurements to narrow constraints on (1) emissions mass, (2) emission size distribution, (3) mixing state, and (4) ratio of black carbon to organic aerosol.

How Massive Single Stars End Their Life

NASA Technical Reports Server (NTRS)

Heger, A.; Fryer, C. L.; Woosley, S. E.; Langer, N.; Hartmann, D. H.

2003-01-01

How massive stars die-what sort of explosion and remnant each produces-depends chiefly on the masses of their helium cores and hydrogen envelopes at death. For single stars, stellar winds are the only means of mass loss, and these are a function of the metallicity of the star. We discuss how metallicity, and a simplified prescription for its effect on mass loss, affects the evolution and final fate of massive stars. We map, as a function of mass and metallicity, where black holes and neutron stars are likely to form and where different types of supernovae are produced. Integrating over an initial mass function, we derive the relative populations as a function of metallicity. Provided that single stars rotate rapidly enough at death, we speculate on stellar populations that might produce gamma-ray bursts and jet-driven supernovae.

Tunneling through superlattices: the effect of anisotropy and kinematic coupling.

PubMed

Halilov, S V; Huang, X Y; Hytha, M; Stephenson, R; Yiptong, A; Takeuchi, H; Cody, N; Mears, R J

2012-12-12

The tunneling of carriers in stratified superlattice systems is analyzed in terms of the constituent effective mass tensor. The focus is on the effects on the tunneling which are caused by the side regions of an intervening barrier. Depending on the covalency and work function in the constituent layers of a superlattice, it is concluded that the kinematics in the regions on either side determined by the effective carrier mass and its interference with the band offset at heterojunctions leads to either a constructive or a destructive effect on the tunneling current. As an example, Si(1-x)Ge(x)/Si and Al(x)Ga(1-x)As/GaAs superlattices are demonstrated to reduce the tunneling current at certain fractional thicknesses and stoichiometries of the constituent slabs without affecting the lateral mobility. The findings show, in general, how manipulation of the carrier's effective mass tensor through stoichiometric/structural modulation of the heterostructure may be used to control the tunneling current through a given potential barrier, given that the characteristic de Broglie wavelength exceeds all the constituent dimensions, thus offering a method complementary to high-k technologies.

Effective-mass model and magneto-optical properties in hybrid perovskites

PubMed Central

Yu, Z. G.

2016-01-01

Hybrid inorganic-organic perovskites have proven to be a revolutionary material for low-cost photovoltaic applications. They also exhibit many other interesting properties, including giant Rashba splitting, large-radius Wannier excitons, and novel magneto-optical effects. Understanding these properties as well as the detailed mechanism of photovoltaics requires a reliable and accessible electronic structure, on which models of transport, excitonic, and magneto-optical properties can be efficiently developed. Here we construct an effective-mass model for the hybrid perovskites based on the group theory, experiment, and first-principles calculations. Using this model, we relate the Rashba splitting with the inversion-asymmetry parameter in the tetragonal perovskites, evaluate anisotropic g-factors for both conduction and valence bands, and elucidate the magnetic-field effect on photoluminescence and its dependence on the intensity of photoexcitation. The diamagnetic effect of exciton is calculated for an arbitrarily strong magnetic field. The pronounced excitonic peak emerged at intermediate magnetic fields in cyclotron resonance is assigned to the 3D±2 states, whose splitting can be used to estimate the difference in the effective masses of electron and hole. PMID:27338834

Effective-mass model and magneto-optical properties in hybrid perovskites.

PubMed

Yu, Z G

2016-06-24

Hybrid inorganic-organic perovskites have proven to be a revolutionary material for low-cost photovoltaic applications. They also exhibit many other interesting properties, including giant Rashba splitting, large-radius Wannier excitons, and novel magneto-optical effects. Understanding these properties as well as the detailed mechanism of photovoltaics requires a reliable and accessible electronic structure, on which models of transport, excitonic, and magneto-optical properties can be efficiently developed. Here we construct an effective-mass model for the hybrid perovskites based on the group theory, experiment, and first-principles calculations. Using this model, we relate the Rashba splitting with the inversion-asymmetry parameter in the tetragonal perovskites, evaluate anisotropic g-factors for both conduction and valence bands, and elucidate the magnetic-field effect on photoluminescence and its dependence on the intensity of photoexcitation. The diamagnetic effect of exciton is calculated for an arbitrarily strong magnetic field. The pronounced excitonic peak emerged at intermediate magnetic fields in cyclotron resonance is assigned to the 3D±2 states, whose splitting can be used to estimate the difference in the effective masses of electron and hole.

Effective-mass model and magneto-optical properties in hybrid perovskites

NASA Astrophysics Data System (ADS)

Yu, Z. G.

2016-06-01

Hybrid inorganic-organic perovskites have proven to be a revolutionary material for low-cost photovoltaic applications. They also exhibit many other interesting properties, including giant Rashba splitting, large-radius Wannier excitons, and novel magneto-optical effects. Understanding these properties as well as the detailed mechanism of photovoltaics requires a reliable and accessible electronic structure, on which models of transport, excitonic, and magneto-optical properties can be efficiently developed. Here we construct an effective-mass model for the hybrid perovskites based on the group theory, experiment, and first-principles calculations. Using this model, we relate the Rashba splitting with the inversion-asymmetry parameter in the tetragonal perovskites, evaluate anisotropic g-factors for both conduction and valence bands, and elucidate the magnetic-field effect on photoluminescence and its dependence on the intensity of photoexcitation. The diamagnetic effect of exciton is calculated for an arbitrarily strong magnetic field. The pronounced excitonic peak emerged at intermediate magnetic fields in cyclotron resonance is assigned to the 3D±2 states, whose splitting can be used to estimate the difference in the effective masses of electron and hole.

The effect of the earth's and stray magnetic fields on mobile mass spectrometer systems.

PubMed

Bell, Ryan J; Davey, Nicholas G; Martinsen, Morten; Short, R Timothy; Gill, Chris G; Krogh, Erik T

2015-02-01

Development of small, field-portable mass spectrometers has enabled a rapid growth of in-field measurements on mobile platforms. In such in-field measurements, unexpected signal variability has been observed by the authors in portable ion traps with internal electron ionization. The orientation of magnetic fields (such as the Earth's) relative to the ionization electron beam trajectory can significantly alter the electron flux into a quadrupole ion trap, resulting in significant changes in the instrumental sensitivity. Instrument simulations and experiments were performed relative to the earth's magnetic field to assess the importance of (1) nonpoint-source electron sources, (2) vertical versus horizontal electron beam orientation, and (3) secondary magnetic fields created by the instrument itself. Electron lens focus effects were explored by additional simulations, and were paralleled by experiments performed with a mass spectrometer mounted on a rotating platform. Additionally, magnetically permeable metals were used to shield (1) the entire instrument from the Earth's magnetic field, and (2) the electron beam from both the Earth's and instrument's magnetic fields. Both simulation and experimental results suggest the predominant influence on directionally dependent signal variability is the result of the summation of two magnetic vectors. As such, the most effective method for reducing this effect is the shielding of the electron beam from both magnetic vectors, thus improving electron beam alignment and removing any directional dependency. The improved ionizing electron beam alignment also allows for significant improvements in overall instrument sensitivity.

Effect of the universal acid-base indicator on the formation of the concentration-dependent diffusion instability

NASA Astrophysics Data System (ADS)

Mosheva, E. A.; Shmyrov, A. V.

2017-06-01

The effect of the universal acid-base indicator on the pattern formation and mass transfer in a two-layer system composed of two reactive miscible liquids in a vertical Hele-Shaw cell is studied experimentally. The reaction we study is a neutralization one. It turns out that the presence of the indicator leads to a change in the spatio-temporal characteristics of the system and even in the mass transfer mechanism near the reaction front—from diffusive to convective. The conditions, where the universal indicator does not affect the reaction and can be used as a visualizing mean, are reported.

XMM-Subaru:Complete High Precision Study of Galaxy Clusters for Modern Cosmology

NASA Astrophysics Data System (ADS)

Zhang, Yu-Ying

2011-10-01

We request 382 ks data for 12 clusters to complete our survey of a volume-limited sample of 55 clusters. We investigated the existing data, which hints a mass dependent bias in the X-ray to weak lensing mass ratios for disturbed ones. X-ray mass proxies, e.g., Yx, show low scatter, but the best fits, particularly the slopes, of the mass-observable relations may be biased due to this mass dependence. Our program will quantify any mass/radial dependent bias based on three independent probes (X-ray/lensing/velocity dispersion) for such a volume-limited sample, and deliver definitive constraints on systematics for upcoming cluster cosmology surveys. The dataset will be a major asset for programs aiming to measure dark energy and programs adding a multi-wavelength focus to studies of cluster physics.

Neutrino masses, scale-dependent growth, and redshift-space distortions

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

Hernández, Oscar F., E-mail: oscarh@physics.mcgill.ca

2017-06-01

Massive neutrinos leave a unique signature in the large scale clustering of matter. We investigate the wavenumber dependence of the growth factor arising from neutrino masses and use a Fisher analysis to determine the aspects of a galaxy survey needed to measure this scale dependence.

Investigating the quark flavor dependence of the chiral magnetic effect with a multiphase transport model

NASA Astrophysics Data System (ADS)

Huang, Ling; Ma, Chun-Wang; Ma, Guo-Liang

2018-03-01

Because the properties of the QCD phase transition and the chiral magnetic effect (CME) depend on the number of quark flavors (Nf) and quark mass, relativistic heavy-ion collisions provide a natural environment to investigate the flavor features if quark deconfinement occurs. We introduce an initial two-flavor or three-flavor dipole charge separation into a multiphase transport (AMPT) model to investigate the flavor dependence of the CME. By taking advantage of the recent ALICE data of charge azimuthal correlations with identified hadrons, we attempt to disentangle two-flavor and three-flavor CME scenarios in Pb+Pb collisions at 2.76 TeV. We find that the experimental data show a certain potential to distinguish the two scenarios, therefore we further suggest to collect more data to clarify the possible flavor dependence in future experiments.

Metal intercalation-induced selective adatom mass transport on graphene

DOE PAGES

Liu, Xiaojie; Wang, Cai -Zhuang; Hupalo, Myron; ...

2016-03-29

Recent experiments indicate that metal intercalation is a very effective method to manipulate the graphene-adatom interaction and control metal nanostructure formation on graphene. A key question is mass transport, i.e., how atoms deposited uniformly on graphene populate different areas depending on the local intercalation. Using first-principles calculations, we show that partially intercalated graphene, with a mixture of intercalated and pristine areas, can induce an alternating electric field because of the spatial variations in electron doping, and thus, an oscillatory electrostatic potential. As a result, this alternating field can change normal stochastic adatom diffusion to biased diffusion, leading to selective massmore » transport and consequent nucleation, on either the intercalated or pristine areas, depending on the charge state of the adatoms.« less

Microlensing of an extended source by a power-law mass distribution

NASA Astrophysics Data System (ADS)

Congdon, Arthur B.; Keeton, Charles R.; Osmer, S. J.

2007-03-01

Microlensing promises to be a powerful tool for studying distant galaxies and quasars. As the data and models improve, there are systematic effects that need to be explored. Quasar continuum and broad-line regions may respond differently to microlensing due to their different sizes; to understand this effect, we study microlensing of finite sources by a mass function of stars. We find that microlensing is insensitive to the slope of the mass function but does depend on the mass range. For negative-parity images, diluting the stellar population with dark matter increases the magnification dispersion for small sources and decreases it for large sources. This implies that the quasar continuum and broad-line regions may experience very different microlensing in negative-parity lensed images. We confirm earlier conclusions that the surface brightness profile and geometry of the source have little effect on microlensing. Finally, we consider non-circular sources. We show that elliptical sources that are aligned with the direction of shear have larger magnification dispersions than sources with perpendicular alignment, an effect that becomes more prominent as the ellipticity increases. Elongated sources can lead to more rapid variability than circular sources, which raises the prospect of using microlensing to probe source shape.

Validation of a numerical method for interface-resolving simulation of multicomponent gas-liquid mass transfer and evaluation of multicomponent diffusion models

NASA Astrophysics Data System (ADS)

Woo, Mino; Wörner, Martin; Tischer, Steffen; Deutschmann, Olaf

2018-03-01

The multicomponent model and the effective diffusivity model are well established diffusion models for numerical simulation of single-phase flows consisting of several components but are seldom used for two-phase flows so far. In this paper, a specific numerical model for interfacial mass transfer by means of a continuous single-field concentration formulation is combined with the multicomponent model and effective diffusivity model and is validated for multicomponent mass transfer. For this purpose, several test cases for one-dimensional physical or reactive mass transfer of ternary mixtures are considered. The numerical results are compared with analytical or numerical solutions of the Maxell-Stefan equations and/or experimental data. The composition-dependent elements of the diffusivity matrix of the multicomponent and effective diffusivity model are found to substantially differ for non-dilute conditions. The species mole fraction or concentration profiles computed with both diffusion models are, however, for all test cases very similar and in good agreement with the analytical/numerical solutions or measurements. For practical computations, the effective diffusivity model is recommended due to its simplicity and lower computational costs.

Systemic SMAD7 Gene Therapy Increases Striated Muscle Mass and Enhances Exercise Capacity in a Dose-Dependent Manner.

PubMed

Maricelli, Joseph W; Bishaw, Yemeserach M; Wang, Bo; Du, Min; Rodgers, Buel D

2018-03-01

Striated muscle wasting occurs with a variety of disease indications, contributing to mortality and compromising life quality. Recent studies indicate that the recombinant adeno-associated virus (serotype 6) Smad7 gene therapeutic, AVGN7, enhances skeletal and cardiac muscle mass and prevents cancer-induced wasting of both tissues. This is accomplished by attenuating ActRIIb intracellular signaling and, as a result, the physiological actions of myostatin and other ActRIIb ligands. AVGN7 also enhances isolated skeletal muscle twitch force, but is unknown to improve systemic muscle function similarly, especially exercise capacity. A 2-month-long dose-escalation study was therefore conducted using 5 × 10 11 , 1 × 10 12 , and 5 × 10 12 vg/mouse and different tests of systemic muscle function. Body mass, skeletal muscle mass, heart mass, and forelimb grip strength were all increased in a dose-dependent manner, as was the fiber cross-sectional area of tibialis anterior muscles. Maximal oxygen consumption (VO 2 max), a measure of metabolic rate, was similarly enhanced during forced treadmill running, and although the total distance traveled was only elevated by the highest dose, all doses reduced the energy expenditure rate compared to control mice injected with an empty vector. Such improvements in VO 2 max are consistent with physiological cardiac hypertrophy, which is highly beneficial and a normal adaptive response to exercise. This was particularly evident at the lowest dose tested, which had minimal significant effects on skeletal muscle mass and/or function, but increased heart weight and exercise capacity. These results together suggest that AVGN7 enhances striated muscle mass and systemic muscle function. They also define minimally effective and optimal doses for future preclinical trials and toxicology studies and in turn will aid in establishing dose ranges for clinical trials.

Dark matter versus Mach's principle.

NASA Astrophysics Data System (ADS)

von Borzeszkowski, H.-H.; Treder, H.-J.

1998-02-01

Empirical and theoretical evidence show that the astrophysical problem of dark matter might be solved by a theory of Einstein-Mayer type. In this theory up to global Lorentz rotations the reference system is determined by the motion of cosmic matter. Thus one is led to a "Riemannian space with teleparallelism" realizing a geometric version of the Mach-Einstein doctrine. The field equations of this gravitational theory contain hidden matter terms where the existence of hidden matter is inferred safely from its gravitational effects. It is argued that in the nonrelativistic mechanical approximation they provide an inertia-free mechanics where the inertial mass of a body is induced by the gravitational action of the comic masses. Interpreted form the Newtonian point of view this mechanics shows that the effective gravitational mass of astrophysical objects depends on r such that one expects the existence of dark matter.

Effects of non-uniform temperature gradients on surface tension driven two component magneto convection in a porous- fluid system

NASA Astrophysics Data System (ADS)

Manjunatha, N.; Sumithra, R.

2018-04-01

The problem of surface tension driven two component magnetoconvection is investigated in a Porous-Fluid system, consisting of anincompressible two component electrically conducting fluid saturatedporous layer above which lies a layer of the same fluid in the presence of a uniform vertical magnetic field. The lower boundary of the porous layeris rigid and the upper boundary of the fluid layer is free with surfacetension effects depending on both temperature and concentration, boththese boundaries are insulating to heat and mass. At the interface thevelocity, shear and normal stress, heat and heat flux, mass and mass fluxare assumed to be continuous suitable for Darcy-Brinkman model. Theeigenvalue problem is solved in linear, parabolic and inverted parabolictemperature profiles and the corresponding Thermal Marangoni Numberis obtained for different important physical parameters.

Study of X(3872) from effective field theory with pion-exchange interaction.

PubMed

Wang, P; Wang, X G

2013-07-26

We study DD[over ¯]* (D*D[over ¯]) scattering in the framework of unitarized heavy meson chiral perturbation theory with pion exchange and a contact interaction. 3S1-3D1 mixing effects are taken into account. A loosely bound state X(3872), with the pole position being Mpole}=(3871.70-i0.39)  MeV, is found. The result is not sensitive to the strength of the contact interaction. Our calculation provides a theoretical confirmation of the existence of the 1++ state X(3872). The light quark mass dependence of the pole position indicates it has a predominately DD[over ¯]* (D*D[over ¯]) molecular nature. When the π mass is larger than 142 MeV, the pole disappears, which makes impossible the lattice simulation of this state at large quark mass.

Merging black hole binaries: the effects of progenitor's metallicity, mass-loss rate and Eddington factor

NASA Astrophysics Data System (ADS)

Giacobbo, Nicola; Mapelli, Michela; Spera, Mario

2018-03-01

The first four gravitational wave events detected by LIGO were all interpreted as merging black hole binaries (BHBs), opening a new perspective on the study of such systems. Here we use our new population-synthesis code MOBSE, an upgraded version of BSE, to investigate the demography of merging BHBs. MOBSE includes metallicity-dependent prescriptions for mass-loss of massive hot stars. It also accounts for the impact of the electron-scattering Eddington factor on mass-loss. We perform >108 simulations of isolated massive binaries, with 12 different metallicities, to study the impact of mass-loss, core-collapse supernovae and common envelope on merging BHBs. Accounting for the dependence of stellar winds on the Eddington factor leads to the formation of black holes (BHs) with mass up to 65 M⊙ at metallicity Z ˜ 0.0002. However, most BHs in merging BHBs have masses ≲ 40 M⊙. We find merging BHBs with mass ratios in the 0.1-1.0 range, even if mass ratios >0.6 are more likely. We predict that systems like GW150914, GW170814 and GW170104 can form only from progenitors with metallicity Z ≤ 0.006, Z ≤ 0.008 and Z ≤ 0.012, respectively. Most merging BHBs have gone through a common envelope phase, but up to ˜17 per cent merging BHBs at low metallicity did not undergo any common envelope phase. We find a much higher number of mergers from metal-poor progenitors than from metal-rich ones: the number of BHB mergers per unit mass is ˜10-4 M_{⊙}^{-1} at low metallicity (Z = 0.0002-0.002) and drops to ˜10-7 M_{⊙}^{-1} at high metallicity (Z ˜ 0.02).

Exciton binding energy in a pyramidal quantum dot

NASA Astrophysics Data System (ADS)

Anitha, A.; Arulmozhi, M.

2018-05-01

The effects of spatially dependent effective mass, non-parabolicity of the conduction band and dielectric screening function on exciton binding energy in a pyramid-shaped quantum dot of GaAs have been investigated by variational method as a function of base width of the pyramid. We have assumed that the pyramid has a square base with area a× a and height of the pyramid H=a/2. The trial wave function of the exciton has been chosen according to the even mirror boundary condition, i.e. the wave function of the exciton at the boundary could be non-zero. The results show that (i) the non-parabolicity of the conduction band affects the light hole (lh) and heavy hole (hh) excitons to be more bound than that with parabolicity of the conduction band, (ii) the dielectric screening function (DSF) affects the lh and hh excitons to be more bound than that without the DSF and (iii) the spatially dependent effective mass (SDEM) affects the lh and hh excitons to be less bound than that without the SDEM. The combined effects of DSF and SDEM on exciton binding energy have also been calculated. The results are compared with those available in the literature.

Quark matter symmetry energy and quark stars

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

Chu, Peng-Cheng; Chen, Lie-Wen, E-mail: lwchen@sjtu.edu.cn

2014-01-10

We extend the confined-density-dependent-mass (CDDM) model to include isospin dependence of the equivalent quark mass. Within the confined-isospin-density-dependent-mass (CIDDM) model, we study the quark matter symmetry energy, the stability of strange quark matter, and the properties of quark stars. We find that including isospin dependence of the equivalent quark mass can significantly influence the quark matter symmetry energy as well as the properties of strange quark matter and quark stars. While the recently discovered large mass pulsars PSR J1614–2230 and PSR J0348+0432 with masses around 2 M {sub ☉} cannot be quark stars within the CDDM model, they can bemore » well described by quark stars in the CIDDM model. In particular, our results indicate that the two-flavor u-d quark matter symmetry energy should be at least about twice that of a free quark gas or normal quark matter within the conventional Nambu-Jona-Lasinio model in order to describe PSR J1614–2230 and PSR J0348+0432 as quark stars.« less

Enhanced Higgs mass in Compact Supersymmetry

DOE PAGES

Tobioka, Kohsaku; Kitano, Ryuichiro; Murayama, Hitoshi

2016-04-05

The current LHC results make weak scale supersymmetry difficult due to relatively heavy mass of the discovered Higgs boson and the null results of new particle searches. Geometrical supersymmetry breaking from extra dimensions, Scherk-Schwarz mechanism, is possible to accommodate such situations. A concrete example, the Compact Supersymmetry model, has a compressed spectrum ameliorating the LHC bounds and large mixing in the top and scalar top quark sector with (Formula presented.) which radiatively raises the Higgs mass. And while the zero mode contribution of the model has been considered, in this paper we calculate the Kaluza-Klein tower effect to the Higgsmore » mass. Although such contributions are naively expected to be as small as a percent level for 10 TeV Kaluza-Klein modes, we find the effect significantly enhances the radiative correction to the Higgs quartic coupling by from 10 to 50%. This is mainly because the top quark wave function is pushed out from the brane, which makes the top mass depend on higher powers in the Higgs field. And, as a result the Higgs mass is enhanced up to 15 GeV from the previous calculation. We also show the whole parameter space is testable at the LHC run II.« less

Dependence of Microlensing on Source Size and Lens Mass

NASA Astrophysics Data System (ADS)

Congdon, A. B.; Keeton, C. R.

2007-11-01

In gravitational lensed quasars, the magnification of an image depends on the configuration of stars in the lensing galaxy. We study the statistics of the magnification distribution for random star fields. The width of the distribution characterizes the amount by which the observed magnification is likely to differ from models in which the mass is smoothly distributed. We use numerical simulations to explore how the width of the magnification distribution depends on the mass function of stars, and on the size of the source quasar. We then propose a semi-analytic model to describe the distribution width for different source sizes and stellar mass functions.

Quark matter at high density based on an extended confined isospin-density-dependent mass model

NASA Astrophysics Data System (ADS)

Qauli, A. I.; Sulaksono, A.

2016-01-01

We investigate the effect of the inclusion of relativistic Coulomb terms in a confined-isospin-density-dependent-mass (CIDDM) model of strange quark matter (SQM). We found that if we include the Coulomb term in scalar density form, the SQM equation of state (EOS) at high densities is stiffer but if we include the Coulomb term in vector density form it is softer than that of the standard CIDDM model. We also investigate systematically the role of each term of the extended CIDDM model. Compared with what was reported by Chu and Chen [Astrophys. J. 780, 135 (2014)], we found the stiffness of SQM EOS is controlled by the interplay among the oscillator harmonic, isospin asymmetry and Coulomb contributions depending on the parameter's range of these terms. We have found that the absolute stable condition of SQM and the mass of 2 M⊙ pulsars can constrain the parameter of oscillator harmonic κ1≈0.53 in the case the Coulomb term is excluded. If the Coulomb term is included, for the models with their parameters are consistent with SQM absolute stability condition, the 2.0 M⊙ constraint more prefers the maximum mass prediction of the model with the scalar Coulomb term than that of the model with the vector Coulomb term. On the contrary, the high densities EOS predicted by the model with the vector Coulomb is more compatible with the recent perturbative quantum chromodynamics result [1] than that predicted by the model with the scalar Coulomb. Furthermore, we also observed the quark composition in a very high density region depends quite sensitively on the kind of Coulomb term used.

Body mass scaling of passive oxygen diffusion in endotherms and ectotherms

PubMed Central

Gillooly, James F.; Gomez, Juan Pablo; Mavrodiev, Evgeny V.; Rong, Yue; McLamore, Eric S.

2016-01-01

The area and thickness of respiratory surfaces, and the constraints they impose on passive oxygen diffusion, have been linked to differences in oxygen consumption rates and/or aerobic activity levels in vertebrates. However, it remains unclear how respiratory surfaces and associated diffusion rates vary with body mass across vertebrates, particularly in relation to the body mass scaling of oxygen consumption rates. Here we address these issues by first quantifying the body mass dependence of respiratory surface area and respiratory barrier thickness for a diversity of endotherms (birds and mammals) and ectotherms (fishes, amphibians, and reptiles). Based on these findings, we then use Fick’s law to predict the body mass scaling of oxygen diffusion for each group. Finally, we compare the predicted body mass dependence of oxygen diffusion to that of oxygen consumption in endotherms and ectotherms. We find that the slopes and intercepts of the relationships describing the body mass dependence of passive oxygen diffusion in these two groups are statistically indistinguishable from those describing the body mass dependence of oxygen consumption. Thus, the area and thickness of respiratory surfaces combine to match oxygen diffusion capacity to oxygen consumption rates in both air- and water-breathing vertebrates. In particular, the substantially lower oxygen consumption rates of ectotherms of a given body mass relative to those of endotherms correspond to differences in oxygen diffusion capacity. These results provide insights into the long-standing effort to understand the structural attributes of organisms that underlie the body mass scaling of oxygen consumption. PMID:27118837

Body mass scaling of passive oxygen diffusion in endotherms and ectotherms.

PubMed

Gillooly, James F; Gomez, Juan Pablo; Mavrodiev, Evgeny V; Rong, Yue; McLamore, Eric S

2016-05-10

The area and thickness of respiratory surfaces, and the constraints they impose on passive oxygen diffusion, have been linked to differences in oxygen consumption rates and/or aerobic activity levels in vertebrates. However, it remains unclear how respiratory surfaces and associated diffusion rates vary with body mass across vertebrates, particularly in relation to the body mass scaling of oxygen consumption rates. Here we address these issues by first quantifying the body mass dependence of respiratory surface area and respiratory barrier thickness for a diversity of endotherms (birds and mammals) and ectotherms (fishes, amphibians, and reptiles). Based on these findings, we then use Fick's law to predict the body mass scaling of oxygen diffusion for each group. Finally, we compare the predicted body mass dependence of oxygen diffusion to that of oxygen consumption in endotherms and ectotherms. We find that the slopes and intercepts of the relationships describing the body mass dependence of passive oxygen diffusion in these two groups are statistically indistinguishable from those describing the body mass dependence of oxygen consumption. Thus, the area and thickness of respiratory surfaces combine to match oxygen diffusion capacity to oxygen consumption rates in both air- and water-breathing vertebrates. In particular, the substantially lower oxygen consumption rates of ectotherms of a given body mass relative to those of endotherms correspond to differences in oxygen diffusion capacity. These results provide insights into the long-standing effort to understand the structural attributes of organisms that underlie the body mass scaling of oxygen consumption.

Revisiting the decoupling effects in the running of the Cosmological Constant

NASA Astrophysics Data System (ADS)

Antipin, Oleg; Melić, Blaženka

2017-09-01

We revisit the decoupling effects associated with heavy particles in the renormalization group running of the vacuum energy in a mass-dependent renormalization scheme. We find the running of the vacuum energy stemming from the Higgs condensate in the entire energy range and show that it behaves as expected from the simple dimensional arguments meaning that it exhibits the quadratic sensitivity to the mass of the heavy particles in the infrared regime. The consequence of such a running to the fine-tuning problem with the measured value of the Cosmological Constant is analyzed and the constraint on the mass spectrum of a given model is derived. We show that in the Standard Model (SM) this fine-tuning constraint is not satisfied while in the massless theories this constraint formally coincides with the well known Veltman condition. We also provide a remarkably simple extension of the SM where saturation of this constraint enables us to predict the radiative Higgs mass correctly. Generalization to constant curvature spaces is also given.

The dependence of cosmic ray-driven galactic winds on halo mass

NASA Astrophysics Data System (ADS)

Jacob, Svenja; Pakmor, Rüdiger; Simpson, Christine M.; Springel, Volker; Pfrommer, Christoph

2018-03-01

Galactic winds regulate star formation in disc galaxies and help to enrich the circum-galactic medium. They are therefore crucial for galaxy formation, but their driving mechanism is still poorly understood. Recent studies have demonstrated that cosmic rays (CRs) can drive outflows if active CR transport is taken into account. Using hydrodynamical simulations of isolated galaxies with virial masses between 1010 and 1013 M⊙, we study how the properties of CR-driven winds depend on halo mass. CRs are treated in a two-fluid approximation and their transport is modelled through isotropic or anisotropic diffusion. We find that CRs are only able to drive mass-loaded winds beyond the virial radius in haloes with masses below 1012 M⊙. For our lowest examined halo mass, the wind is roughly spherical and has velocities of ˜20 km s-1. With increasing halo mass, the wind becomes biconical and can reach 10 times higher velocities. The mass loading factor drops rapidly with virial mass, a dependence that approximately follows a power law with a slope between -1 and -2. This scaling is slightly steeper than observational inferences, and also steeper than commonly used prescriptions for wind feedback in cosmological simulations. The slope is quite robust to variations of the CR injection efficiency or the CR diffusion coefficient. In contrast to the mass loading, the energy loading shows no significant dependence on halo mass. While these scalings are close to successful heuristic models of wind feedback, the CR-driven winds in our present models are not yet powerful enough to fully account for the required feedback strength.

Leptin: a potential mediator for protective effects of fat mass on bone tissue.

PubMed

Thomas, Thierry

2003-02-01

Body weight is among the most powerful predictors of bone status, and adipose tissue plays a substantial role in weight-related protective effects on bone. An understanding of the mechanisms underlying the relation between adipose tissue and bone may open up new perspectives for treatment. Leptin, which is known to regulate appetite and energy expenditures, may also contribute to mediate the effects of fat mass on bone. Although reported data are somewhat conflicting, there is some evidence that leptin may decrease bone formation via a central nervous effect and may stimulate both bone formation and bone resorption via direct peripheral effects on stromal precursor cells. The net result of these central and peripheral effects may depend on serum leptin levels and blood-brain barrier permeability, of which the first increase and the second decrease as obesity develops. Further work is needed to improve our understanding of these effects.

Isotope effects of trapped electron modes in the presence of impurities in tokamak plasmas

NASA Astrophysics Data System (ADS)

Shen, Yong; Dong, J. Q.; Sun, A. P.; Qu, H. P.; Lu, G. M.; He, Z. X.; He, H. D.; Wang, L. F.

2016-04-01

The trapped electron modes (TEMs) are numerically investigated in toroidal magnetized hydrogen, deuterium and tritium plasmas, taking into account the effects of impurity ions such as carbon, oxygen, helium, tungsten and others with positive and negative density gradients with the rigorous integral eigenmode equation. The effects of impurity ions on TEMs are investigated in detail. It is shown that impurity ions have substantially-destabilizing (stabilizing) effects on TEMs in isotope plasmas for {{L}ez}\\equiv {{L}ne}/{{L}nz}>0 (<0 ), opposite to the case of ion temperature gradient (ITG) driven modes. Detailed analyses of the isotope mass dependence for TEM turbulences in hydrogenic isotope plasmas with and without impurities are performed. The relations between the maximum growth rate of the TEMs with respect to the poloidal wave number and the ion mass number are given in the presence of the impurity ions. The results demonstrate that the maximum growth rates scale as {γ\\max}\\propto Mi-0.5 in pure hydrogenic plasmas. The scale depends on the sign of its density gradient and charge number when there is a second species of (impurity) ions. When impurity ions have density profiles peaking inwardly (i.e. {{L}ez}\\equiv {{L}ne}/{{L}nz}>0 ), the scaling also depends on ITG parameter {ηi} . The maximum growth rates scale as {γ\\max}\\propto M\\text{eff}-0.5 for the case without ITG ({ηi}=0 ) or the ITG parameter is positive ({ηi}>0 ) but the impurity ion charge number is low (Z≤slant 5.0 ). However, when {ηi}>0 and the impurity ion charge number is moderate (Z=6.0-8.0 ), the scaling law is found as {γ\\max}\\propto M\\text{eff}-1.0 . Here, Z is impurity ion charge number, and the effective mass number, {{M}\\text{eff}}=≤ft(1-{{f}z}\\right){{M}i}+{{f}z}{{M}z} , with {{M}i} and {{M}Z} being the mass numbers of the hydrogenic and impurity ions, respectively, and {{f}z}=Z{{n}0z}/{{n}0e} being the charge concentration of impurity ions. In addition, with regard to the case of {{L}ez}<0 , the maximum growth rate scaling is {γ\\max}\\propto Mi-0.5 . The possible relations of the results with experimental observations are discussed.

Simultaneous effects of pressure and temperature on donor binding energy in Pöschl-Teller quantum well

NASA Astrophysics Data System (ADS)

Hakimyfard, Alireza; Barseghyan, M. G.; Duque, C. A.; Kirakosyan, A. A.

2009-12-01

In the frame of the variational method and the effective-mass approximation, the effects of hydrostatic pressure and temperature on the binding energy for donor impurities in the Pöschl-Teller quantum well are studied. The binding energy dependencies on the width of the quantum well, the hydrostatic pressure, the impurity position, the temperature, and the parameters of the confining potential are reported. The results show that the binding energy increases (decreases) with the increasing of the hydrostatic pressure (temperature). It is also found that, associated with the symmetry breaking in the Pöschl-Teller quantum well, and depending on the impurity position, the binding energy can increase or decrease.

The two-mass contribution to the three-loop gluonic operator matrix element Agg,Q(3)

NASA Astrophysics Data System (ADS)

Ablinger, J.; Blümlein, J.; De Freitas, A.; Goedicke, A.; Schneider, C.; Schönwald, K.

2018-07-01

We calculate the two-mass QCD contributions to the massive operator matrix element Agg,Q at O (αs3) in analytic form in Mellin N- and z-space, maintaining the complete dependence on the heavy quark mass ratio. These terms are important ingredients for the matching relations of the variable flavor number scheme in the presence of two heavy quark flavors, such as charm and bottom. In Mellin N-space the result is given in the form of nested harmonic, generalized harmonic, cyclotomic and binomial sums, with arguments depending on the mass ratio. The Mellin inversion of these quantities to z-space gives rise to generalized iterated integrals with square root valued letters in the alphabet, depending on the mass ratio as well. Numerical results are presented.

Merger-driven evolution of the effective stellar initial mass function of massive early-type galaxies

NASA Astrophysics Data System (ADS)

Sonnenfeld, Alessandro; Nipoti, Carlo; Treu, Tommaso

2017-02-01

The stellar initial mass function (IMF) of early-type galaxies is the combination of the IMF of the stellar population formed in situ and that of accreted stellar populations. Using as an observable the effective IMF αIMF, defined as the ratio between the true stellar mass of a galaxy and the stellar mass inferred assuming a Salpeter IMF, we present a theoretical model for its evolution as a result of dry mergers. We use a simple dry-merger evolution model, based on cosmological N-body simulations, together with empirically motivated prescriptions for the IMF to make predictions on how the effective IMF of massive early-type galaxies changes from z = 2 to z = 0. We find that the IMF normalization of individual galaxies becomes lighter with time. At fixed velocity dispersion, αIMF is predicted to be constant with redshift. Current dynamical constraints on the evolution of the IMF are in slight tension with this prediction, even though systematic uncertainties, including the effect of radial gradients in the IMF, prevent a conclusive statement. The correlation of αIMF with stellar mass becomes shallower with time, while the correlation between αIMF and velocity dispersion is mostly preserved by dry mergers. We also find that dry mergers can mix the dependence of the IMF on stellar mass and velocity dispersion, making it challenging to infer, from z = 0 observations of global galactic properties, what is the quantity that is originally coupled with the IMF.

Value and Anisotropy of the Electron and Hole Mass in Pure Wurtzite InP Nanowires.

PubMed

Tedeschi, D; De Luca, M; Granados Del Águila, A; Gao, Q; Ambrosio, G; Capizzi, M; Tan, H H; Christianen, P C M; Jagadish, C; Polimeni, A

2016-10-12

The effective mass of electrons and holes in semiconductors is pivotal in determining the dynamics of carriers and their confinement energy in nanostructured materials. Surprisingly, this quantity is still unknown in wurtzite (WZ) nanowires (NWs) made of III-V compounds (e.g., GaAs, InAs, GaP, InP), where the WZ phase has no bulk counterpart. Here, we investigate the magneto-optical properties of InP WZ NWs grown by selective-area epitaxy that provides perfectly ordered NWs featuring high-crystalline quality. The combined analysis of the energy of free exciton states and impurity levels under magnetic field (B up to 29 T) allows us to disentangle the dynamics of oppositely charged carriers from the Coulomb interaction and thus to determine the values of the electron and hole effective mass. By application of B⃗ along different crystallographic directions, we also assess the dependence of the transport properties with respect to the NW growth axis (namely, the WZ ĉ axis). The effective mass of electrons along ĉ is m e ∥ = (0.078 ± 0.002) m 0 (m 0 is the electron mass in vacuum) and perpendicular to ĉ is m e ⊥ = (0.093 ± 0.001) m 0 , resulting in a 20% mass anisotropy. Holes exhibit a much larger (∼320%) and opposite mass anisotropy with their effective mass along and perpendicular to ĉ equal to m h ∥ = (0.81 ± 0.18) m 0 and m h ⊥ = (0.250 ± 0.016) m 0 , respectively. While no full consensus is found with current theoretical results on WZ InP, our findings show trends remarkably similar to the experimental data available in WZ bulk materials, such as InN, GaN, and ZnO.

Landau problem with time dependent mass in time dependent electric and harmonic background fields

NASA Astrophysics Data System (ADS)

Lawson, Latévi M.; Avossevou, Gabriel Y. H.

2018-04-01

The spectrum of a Hamiltonian describing the dynamics of a Landau particle with time-dependent mass and frequency undergoing the influence of a uniform time-dependent electric field is obtained. The configuration space wave function of the model is expressed in terms of the generalised Laguerre polynomials. To diagonalize the time-dependent Hamiltonian, we employ the Lewis-Riesenfeld method of invariants. To this end, we introduce a unitary transformation in the framework of the algebraic formalism to construct the invariant operator of the system and then to obtain the exact solution of the Hamiltonian. We recover the solutions of the ordinary Landau problem in the absence of the electric and harmonic fields for a constant particle mass.

Aerosol detection efficiency in inductively coupled plasma mass spectrometry

DOE PAGES

Hubbard, Joshua A.; Zigmond, Joseph A.

2016-03-02

We used an electrostatic size classification technique to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Moreover, we counted size-segregated particles with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized bymore » the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10 -5 to 10 -11. Free molecular heat and mass transfer theory was applied, but evaporative phenomena were not sufficient to explain the dependence of aerosol detection on particle diameter. Additional work is needed to correlate experimental data with theory for metal-oxides where thermodynamic property data are sparse relative to pure elements. Finally, when matrix effects and the diffusion of ions inside the plasma were considered, mass loading was concluded to have had an effect on the dependence of detection efficiency on particle diameter.« less

Orientation of X Lines in Asymmetric Magnetic Reconnection-Mass Ratio Dependency

NASA Technical Reports Server (NTRS)

Liu, Yi-Hsin; Hesse, M.; Kuznetsova, M.

2015-01-01

Using fully kinetic simulations, we study the X line orientation of magnetic reconnection in an asymmetric configuration. A spatially localized perturbation is employed to induce a single X line, which has sufficient freedom to choose its orientation in three-dimensional systems. The effect of ion to electron mass ratio is investigated, and the X line appears to bisect the magnetic shear angle across the current sheet in the large mass ratio limit. The orientation can generally be deduced by scanning through the corresponding 2-D simulations to find the reconnection plane that maximizes the peak reconnection electric field. The deviation from the bisection angle in the lower mass ratio limit is consistent with the orientation shift of the most unstable linear tearing mode in an electron-scale current sheet.

An expanded set of brown dwarf and very low mass star models

NASA Technical Reports Server (NTRS)

Burrows, A.; Hubbard, W. B.; Saumon, D.; Lunine, J. I.

1993-01-01

We present in this paper updated and improved theoretical models of brown dwarfs and late M dwarfs. The evolution and characteristics of objects between 0.01 and 0.2 solar mass are exhaustively investigated and special emphasis is placed on their properties at early ages. The dependence on the helium fraction, deuterium fraction, and metallicity of the masses, effective temperature and luminosities at the edge of the hydrogen main sequence are calculated. We derive luminosity functions for representative mass functions and compare our predictions to recent cluster data. We show that there are distinctive features in the theoretical luminosity functions that can serve as diagnostics of brown dwarf physics. A zero-metallicity model is presented as a bound to or approximation of a putative extreme halo population.

The growth of discs and bulges during hierarchical galaxy formation - II. Metallicity, stellar populations and dynamical evolution

NASA Astrophysics Data System (ADS)

Tonini, C.; Mutch, S. J.; Wyithe, J. S. B.; Croton, D. J.

2017-03-01

We investigate the properties of the stellar populations of model galaxies as a function of galaxy evolutionary history and angular momentum content. We use the new semi-analytic model presented in Tonini et al. This new model follows the angular momentum evolution of gas and stars, providing the base for a new star formation recipe, and treatment of the effects of mergers that depends on the central galaxy dynamical structure. We find that the new recipes have the effect of boosting the efficiency of the baryonic cycle in producing and recycling metals, as well as preventing minor mergers from diluting the metallicity of bulges and ellipticals. The model reproduces the stellar mass-stellar metallicity relation for galaxies above 1010 solar masses, including Brightest Cluster Galaxies. Model discs, galaxies dominated by instability-driven components, and merger-driven objects each stem from different evolutionary channels. These model galaxies therefore occupy different loci in the galaxy mass-size relation, which we find to be in accord with the ATLAS 3D classification of disc galaxies, fast rotators and slow rotators. We find that the stellar populations' properties depend on the galaxy evolutionary type, with more evolved stellar populations being part of systems that have lost or dissipated more angular momentum during their assembly history.

Constraints on Coulomb energy, neutron skin thickness in 208Pb, and symmetry energy

NASA Astrophysics Data System (ADS)

Dong, J. M.; Wang, L. J.; Zuo, W.; Gu, J. Z.

2018-03-01

The charge-symmetry-breaking (CSB) effect in a nuclear medium that gives rise to the first-order symmetry energy in finite nuclei is discussed in detail in the present paper. For heavy and superheavy nuclei with large neutron excesses, it should be nonnegligible in high-precision mass predictions, and importantly it affects the stability of these nuclei. Combined with this CSB effect, the Coulomb energy is constrained by using the experimental Coulomb displacement energy of mirror nuclei, and then the mass-dependent symmetry energy coefficients of heavy nuclei are reextracted with the experimental β--decay energies of heavy odd-A nuclei and with the experimental mass differences. Based on these results, we probe the neutron skin thickness Δ Rn p of 208Pb and the density-dependent symmetry energy coefficient of nuclear matter. Δ Rn p in 208Pb is found to be 0.158 ±0.014 fm , and the slopes L of the symmetry energy coefficient at densities of ρ =0.16 and ρ =0.11 fm-3 are estimated to be 42 ±8 and 42 ±3 MeV , respectively. These results would be meaningful to discriminate between the models and the predictions that are relevant for the investigations on properties of nuclei and of neutron stars.

Improvement of thermoelectric properties and their correlations with electron effective mass in Cu1.98SxSe1−x

PubMed Central

Zhao, Lanling; Fei, Frank Yun; Wang, Jun; Wang, Funing; Wang, Chunlei; Li, Jichao; Wang, Jiyang; Cheng, Zhenxiang; Dou, Shixue; Wang, Xiaolin

2017-01-01

Sulphur doping effects on the crystal structures, thermoelectric properties, density-of-states, and effective mass in Cu1.98SxSe1−x were studied based on the electrical and thermal transport property measurements, and first-principles calculations. The X-ray diffraction patterns and Rietveld refinements indicate that room temperature Cu1.98SxSe1−x (x = 0, 0.02, 0.08, 0.16) and Cu1.98SxSe1−x (x = 0.8, 0.9, 1.0) have the same crystal structure as monoclinic-Cu2Se and orthorhombic-Cu2S, respectively. Sulphur doping can greatly enhance zT values when x is in the range of 0.8≤ × ≤1.0. Furthermore, all doped samples show stable thermoelectric compatibility factors over a broad temperature range from 700 to 1000 K, which could greatly benefit their practical applications. First-principles calculations indicate that both the electron density-of-sates and the effective mass for all the compounds exhibit non-monotonic sulphur doping dependence. It is concluded that the overall thermoelectric performance of the Cu1.98SxSe1−x system is mainly correlated with the electron effective mass and the density-of-states. PMID:28091545

Improvement of thermoelectric properties and their correlations with electron effective mass in Cu1.98SxSe1-x.

PubMed

Zhao, Lanling; Fei, Frank Yun; Wang, Jun; Wang, Funing; Wang, Chunlei; Li, Jichao; Wang, Jiyang; Cheng, Zhenxiang; Dou, Shixue; Wang, Xiaolin

2017-01-16

Sulphur doping effects on the crystal structures, thermoelectric properties, density-of-states, and effective mass in Cu 1.98 S x Se 1-x were studied based on the electrical and thermal transport property measurements, and first-principles calculations. The X-ray diffraction patterns and Rietveld refinements indicate that room temperature Cu 1.98 S x Se 1-x (x = 0, 0.02, 0.08, 0.16) and Cu 1.98 S x Se 1-x (x = 0.8, 0.9, 1.0) have the same crystal structure as monoclinic-Cu 2 Se and orthorhombic-Cu 2 S, respectively. Sulphur doping can greatly enhance zT values when x is in the range of 0.8≤ × ≤1.0. Furthermore, all doped samples show stable thermoelectric compatibility factors over a broad temperature range from 700 to 1000 K, which could greatly benefit their practical applications. First-principles calculations indicate that both the electron density-of-sates and the effective mass for all the compounds exhibit non-monotonic sulphur doping dependence. It is concluded that the overall thermoelectric performance of the Cu 1.98 S x Se 1-x system is mainly correlated with the electron effective mass and the density-of-states.

Multiple exciton generation in cluster-free alloy Cd(x)Hg(1-x)Te colloidal quantum dots synthesized in water.

PubMed

Kershaw, Stephen V; Kalytchuk, Sergii; Zhovtiuk, Olga; Shen, Qing; Oshima, Takuya; Yindeesuk, Witoon; Toyoda, Taro; Rogach, Andrey L

2014-12-21

A number of different composition CdxHg1-xTe alloy quantum dots have been synthesized using a modified aqueous synthesis and ion exchange method. The benefits of good stoichiometric control and high emission quantum yield were retained whilst also ensuring that the tendency to form gel-like clusters and adsorb excess cations in the stabilizing ligand shells was mitigated using a sequestering method to remove excess ionic material during and after the synthesis. This was highly desirable for ultrafast carrier dynamics measurements, avoiding strong photocharging effects which may mask fundamental carrier signals. Transient grating measurements revealed a composition dependent carrier multiplication process which competes with phonon mediated carrier cooling to deplete the initial hot carrier population. The interplay between these two mechanisms is strongly dependent on the electron effective mass which in these alloys has a marked composition dependence and may be considerably lower than the hole effective mass. For a composition x = 0.52 we measured a maximum carrier multiplication quantum yield of 199 ± 19% with pump photon energy 3 times the bandgap energy, Eg, whilst the threshold energy is calculated to be just 2.15Eg. There is some evidence to suggest an impact ionization process analogous to the inverse Auger S mechanism seen in bulk CdxHg1-xTe.

Parental thermal environment alters offspring sex ratio and fitness in an oviparous lizard.

PubMed

Schwanz, Lisa E

2016-08-01

The environment experienced by parents can impact the phenotype of their offspring (parental effects), a critical component of organismal ecology and evolution in variable or changing environments. Although temperature is a central feature of the environment for ectotherms, its role in parental effects has been little explored until recently. Here, parental basking opportunity was manipulated in an oviparous lizard with temperature-dependent sex determination, the jacky dragon (Amphibolurus muricatus). Eggs were incubated at a temperature that typically produces a 50:50 sex ratio, and hatchlings were reared in a standard thermal environment. Offspring of parents in short bask conditions appeared to have better fitness outcomes in captive conditions than those of parents in long bask conditions - they had greater growth and survival as a function of their mass. In addition, the sex of offspring (male or female) depended on the interaction between parental treatment and egg mass, and treatment impacted whether sons or daughters grew larger in their first season. The interactive effects of treatment on offspring sex and growth are consistent with adaptive explanations for the existence of temperature-dependent sex determination in this species. Moreover, the greater performance recorded in short bask offspring may represent an anticipatory parental effect to aid offspring in predicted conditions of restricted thermal opportunity. Together, these responses constitute a crucial component of the population response to spatial or temporal variation in temperature. © 2016. Published by The Company of Biologists Ltd.

The difficulty with correlations: Energy expenditure and brain mass in bats.

PubMed

McNab, Brian K; Köhler, Meike

2017-10-01

Brain mass has been suggested to determine a mammal's energy expenditure. This potential dependence is examined in 48 species of bats. A correlation between characters may be direct or derived from shared correlations with intervening factors without a direct interaction. Basal rate of metabolism in these bats increases with brain mass: large brains are more expensive than small brains, and both brain mass and basal rate increase with body mass. Basal rate and brain mass also correlate with food habits in bats. Mass-independent basal rate weakly correlates with mass-independent brain mass, the correlation only accounting for 12% of the variation in basal rate, which disappears when the combined effects of body mass and food habits are deleted. The correlation between basal rate and brain mass seen in this and other studies usually accounts for <10% of the variation in basal rate and often <4%, even when statistically significant, a minimalist explanation for the level the basal rate. This correlation probably reflects the intermediacy of secondary factors, as occurred with food habits in bats. Most biological correlations are complicated and must be examined in detail before assurance can be given as to their bases. Copyright © 2017 Elsevier Inc. All rights reserved.

EFFECTS OF BIASES IN VIRIAL MASS ESTIMATION ON COSMIC SYNCHRONIZATION OF QUASAR ACCRETION

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

Steinhardt, Charles L.

2011-09-01

Recent work using virial mass estimates and the quasar mass-luminosity plane has yielded several new puzzles regarding quasar accretion, including a sub-Eddington boundary (SEB) on most quasar accretion, near-independence of the accretion rate from properties of the host galaxy, and a cosmic synchronization of accretion among black holes of a common mass. We consider how these puzzles might change if virial mass estimation turns out to have a systematic bias. As examples, we consider two recent claims of mass-dependent biases in Mg II masses. Under any such correction, the surprising cosmic synchronization of quasar accretion rates and independence from themore » host galaxy remain. The slope and location of the SEB are very sensitive to biases in virial mass estimation, and various mass calibrations appear to favor different possible physical explanations for feedback between the central black hole and its environment. The alternative mass estimators considered do not simply remove puzzling quasar behavior, but rather replace it with new puzzles that may be more difficult to solve than those using current virial mass estimators and the Shen et al. catalog.« less

Equation of State for Isospin Asymmetric Nuclear Matter Using Lane Potential

NASA Astrophysics Data System (ADS)

Basu, D. N.; Chowdhury, P. Roy; Samanta, C.

2006-10-01

A mean field calculation for obtaining the equation of state (EOS) for symmetric nuclear matter from a density dependent M3Y interaction supplemented by a zero-range potential is described. The energy per nucleon is minimized to obtain the ground state of symmetric nuclear matter. The saturation energy per nucleon used for nuclear matter calculations is determined from the co-efficient of the volume term of Bethe--Weizsäcker mass formula which is evaluated by fitting the recent experimental and estimated atomic mass excesses from Audi--Wapstra--Thibault atomic mass table by minimizing the mean square deviation. The constants of density dependence of the effective interaction are obtained by reproducing the saturation energy per nucleon and the saturation density of spin and isospin symmetric cold infinite nuclear matter. The EOS of symmetric nuclear matter, thus obtained, provide reasonably good estimate of nuclear incompressibility. Once the constants of density dependence are determined, EOS for asymmetric nuclear matter is calculated by adding to the isoscalar part, the isovector component of the M3Y interaction that do not contribute to the EOS of symmetric nuclear matter. These EOS are then used to calculate the pressure, the energy density and the velocity of sound in symmetric as well as isospin asymmetric nuclear matter.

Target productions in forward and backward hemispheres in the interactions of 28Si-EM at 14.6A GeV

NASA Astrophysics Data System (ADS)

Abdelsalam, A.; El-Nagdy, M. S.; Abdalla, A. M.; Saber, A.

2015-11-01

This paper search for the results and properties of slow particle productions, appear as a gray and black tracks in nuclear emulsions, producing secondary charged particles which are emitted from 28Si interactions with emulsion nuclei at 14.6A GeV. The forward particles emission of interactions, (θlab<90∘) as well as the backward ones (θlab≥90∘), have been investigated. It includes the effect of both projectile mass number and energy on the production and multiplicities of these particles. The results compared with other experiments for the same target but with different projectiles and energies. The experimental data show that there are two different mechanisms responsible for the production of gray particles for the chosen channels of emission angles and each are energy dependence. This dependence is weakly on the projectile mass number. The same investigations are applied for black tracks producing particles. The experimental results show the production of these particles is purely target fragments independent on both projectile mass number and its energy. The anisotropy ratio of angular distribution (F/B) is applied for both kinds of particles which are found the value for gray particle production depends on the direction of emissions while it is unchanged for black particles.

A first constraint on the average mass of ultra-diffuse galaxies from weak gravitational lensing

NASA Astrophysics Data System (ADS)

Sifón, Cristóbal; van der Burg, Remco F. J.; Hoekstra, Henk; Muzzin, Adam; Herbonnet, Ricardo

2018-01-01

The recent discovery of thousands of ultra-diffuse galaxies (UDGs) in nearby galaxy clusters has opened a new window into the process of galaxy formation and evolution. Several scenarios have been proposed to explain the formation history of UDGs, and their ability to survive in the harsh cluster environments. A key requirement to distinguish between these scenarios is a measurement of their halo masses which, due to their low surface brightnesses, has proven difficult if one relies on stellar tracers of the potential. We exploit weak gravitational lensing, a technique that does not depend on these baryonic tracers, to measure the average subhalo mass of 784 UDGs selected in 18 clusters at z ≤ 0.09. Our sample of UDGs has a median stellar mass 〈m⋆〉 = 2 × 108 M⊙ and a median effective radius 〈reff〉 = 2.8 kpc. We constrain the average mass of subhaloes within 30 kpc to log mUDG(r < 30 kpc)/M⊙ ≤ 10.99 at 95 per cent credibility, implying an effective virial mass log m200/M⊙ ≤ 11.80, and a lower limit on the stellar mass fraction within 10 kpc of 1.0 per cent. Such mass is consistent with a simple extrapolation of the subhalo-to-stellar mass relation of typical satellite galaxies in massive clusters. However, our analysis is not sensitive to scatter about this mean mass; the possibility remains that extreme UDGs reside in haloes as massive as the Milky Way.

The Importance of Three Physical Processes in a Minimal Three-Dimensional Tropical Cyclone Model.

NASA Astrophysics Data System (ADS)

Zhu, Hongyan; Smith, Roger K.

2002-06-01

The minimal three-dimensional tropical cyclone model developed by Zhu et al. is used to explore the role of shallow convection, precipitation-cooled downdrafts, and the vertical transport of momentum by deep convection on the dynamics of tropical cyclone intensification. The model is formulated in coordinates and has three vertical levels, one characterizing a shallow boundary layer, and the other two representing the upper and lower troposphere, respectively. It has three options for treating cumulus convection on the subgrid scale and a simple scheme for the explicit release of latent heat on the grid scale.In the model, as in reality, shallow convection transports air with low moist static energy from the lower troposphere to the boundary layer, stabilizing the atmosphere not only to itself, but also to deep convection. Also it moistens and cools the lower troposphere. For realistic parameter values, the stabilization in the vortex core region is the primary effect: it reduces the deep convective mass flux and therefore the rate of heating and drying in the troposphere. This reduced heating, together with the direct cooling of the lower troposphere by shallow convection, diminishes the buoyancy in the vortex core and thereby the vortex intensification rate.The effects of precipitation-cooled downdrafts depend on the closure scheme chosen for deep convection. In the two closures in which the deep cloud mass flux depends on the degree of convective instability, the downdrafts do not change the total mass flux of air that subsides into the boundary layer, but they carry air with a lower moist static energy into this layer than does subsidence outside downdrafts. As a result they decrease the rate of intensification during the early development stage. Nevertheless, by reducing the deep convective mass flux and the drying effect of compensating subsidence, they enable grid scale saturation, and therefore rapid intensification, to occur earlier than in calculations where they are excluded. In the closure in which the deep cloud mass flux depends on the mass convergence in the boundary layer, downdrafts reduce the gestation period and increase the intensification rate.Convective momentum transport as represented in the model weakens both the primary and secondary circulations of the vortex. However, it does not significantly reduce the maximum intensity attained after the period of rapid development. The weakening of the secondary circulation impedes vortex development and significantly prolongs the gestation period.Where possible the results are compared with those found in other studies.

Body composition in paediatric intestinal failure patients receiving long-term parenteral nutrition.

PubMed

Pichler, Judith; Chomtho, Sirinuch; Fewtrell, Mary; Macdonald, Sarah; Hill, Susan

2014-02-01

Outcome of children with intestinal failure (IF) has improved on treatment with parenteral nutrition (PN). The effects of PN and IF on body composition (BC) are unknown. The aim was to review BC in PN-treated children and those weaned off and to compare with reference data. Children on long-term/home PN underwent measurement of regional fat mass (FM) and lean mass (LM) using dual energy X-ray absorptiometry. Underlying diseases were intestinal enteropathy, n=15, short bowel syndrome (SBS), n=8 and intestinal dysmotility, n=11. PN duration was median 10 years. Fat Mass Index (FMI) and Lean Mass Index (LMI) were compared in children with and without intestinal inflammation, steroid treatment and according to PN dependency. 34 children aged 5-20 years were studied. They were short, mean height SD score (SDS) -1.8 (p<0.001) and light (mean weight SDS -0.86, p<0.001) with high body mass index (BMI) SDS: mean 0.4 (p=0.04) and low Limb LMI SDS -0.9 (p<0.001). Children with SBS had low FMI SDS -0.8 (p=0.01). BC did not significantly differ between diagnostic groups or with steroid treatment. Patients with intestinal inflammation (n=20) had higher BMI SDS than those without, p=0.007. Totally, PN-dependent children, n=11 had higher BMI SDS, p=0.004, total body FMI SDS, p=0.008 and trunk FMI SDS, p=0.001 compared with patients partially dependent and off PN. Significantly low limb LM was seen in all patient groups with high FM in children on total PN. Children with IF requiring PN treatment >27 days may benefit from BC monitoring and PN adjustment according to results in order to maximise linear growth and health in later life.

Stress-sensitive tissue regeneration in viscoelastic biomaterials subjected to modulated tensile strain.

PubMed

Belfiore, Laurence A; Floren, Michael L; Paulino, Alexandre T; Belfiore, Carol J

2011-09-01

This research contribution addresses the mechanochemistry of intra-tissue mass transfer for nutrients, oxygen, growth factors, and other essential ingredients that anchorage-dependent cells require for successful proliferation on biocompatible surfaces. The unsteady state reaction-diffusion equation (i.e., modified diffusion equation) is solved according to the von Kármán-Pohlhausen integral method of boundary layer analysis when nutrient consumption and tissue regeneration are stimulated by harmonically imposed stress. The mass balance with diffusion and stress-sensitive kinetics represents a rare example where the Damköhler and Deborah numbers appear together in an effort to simulate the development of mass transfer boundary layers in porous viscoelastic biomaterials. The Boltzmann superposition integral is employed to calculate time-dependent strain in terms of the real and imaginary components of dynamic compliance for viscoelastic solids that transmit harmonic excitation to anchorage-dependent cells. Rates of nutrient consumption under stress-free conditions are described by third-order kinetics which include local mass densities of nutrients, oxygen, and attached cells that maintain dynamic equilibrium with active protein sites in the porous matrix. Thinner nutrient mass transfer boundary layers are stabilized at shorter dimensionless diffusion times when the stress-free intra-tissue Damköhler number increases above its initial-condition-sensitive critical value. The critical stress-sensitive intra-tissue Damköhler number, above which it is necessary to consider the effect of harmonic strain on nutrient consumption and tissue regeneration, is proportional to the Deborah number and corresponds to a larger fraction of the stress-free intra-tissue Damköhler number in rigid biomaterials. Copyright © 2011 Elsevier B.V. All rights reserved.

(U) Physics Validation of the RMI-Based Ejecta Source Model Implementation in FLAG: L2 Milestone #6035 Report

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

Tregillis, I. L.

The Los Alamos Physics and Engineering Models (PEM) program has developed a model for Richtmyer-Meshkov instability (RMI) based ejecta production from shock-melted surfaces, along with a prescription for a self-similar velocity distribution (SSVD) of the resulting ejecta particles. We have undertaken an effort to validate this source model using data from explosively driven tin coupon experiments. The model’s current formulation lacks a crucial piece of physics: a method for determining the duration of the ejecta production interval. Without a mechanism for terminating ejecta production, the model is not predictive. Furthermore, when the production interval is hand-tuned to match time-integrated massmore » data, the predicted time-dependent mass accumulation on a downstream sensor rises too sharply at early times and too slowly at late times because the SSVD overestimates the amount of mass stored in the fastest particles and underestimates the mass stored in the slowest particles. The functional form of the resulting m(t) is inconsistent with the available time-dependent data; numerical simulations and analytic studies agree on this point. Simulated mass tallies are highly sensitive to radial expansion of the ejecta cloud. It is not clear if the same effect is present in the experimental data but if so, depending on the degree, this may challenge the model’s compatibility with tin coupon data. The current implementation of the model in FLAG is sensitive to the detailed interaction between kinematics (hydrodynamic methods) and thermodynamics (material models); this sensitivity prohibits certain physics modeling choices. The appendices contain an extensive analytic study of piezoelectric ejecta mass measurements, along with test problems, excerpted from a longer work (LA-UR-17-21218).« less

Evolution of the fraction of clumpy galaxies at 0.2 < z < 1.0 in the cosmos field

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

Murata, K. L.; Kajisawa, M.; Taniguchi, Y.

2014-05-01

Using the Hubble Space Telescope/Advanced Camera for Surveys data in the COSMOS field, we systematically searched clumpy galaxies at 0.2 < z < 1.0 and investigated the fraction of clumpy galaxies and its evolution as a function of stellar mass, star formation rate (SFR), and specific SFR (SSFR). The fraction of clumpy galaxies in star-forming galaxies with M {sub star} > 10{sup 9.5} M {sub ☉} decreases with time from ∼0.35 at 0.8 < z < 1.0 to ∼0.05 at 0.2 < z < 0.4, irrespective of the stellar mass, although the fraction tends to be slightly lower for massivemore » galaxies with M {sub star} > 10{sup 10.5} M {sub ☉} at each redshift. On the other hand, the fraction of clumpy galaxies increases with increasing both SFR and SSFR in all the redshift ranges we investigated. In particular, we found that the SSFR dependences of the fractions are similar among galaxies with different stellar masses, and the fraction at a given SSFR does not depend on the stellar mass in each redshift bin. The evolution of the fraction of clumpy galaxies from z ∼ 0.9 to z ∼ 0.3 seems to be explained by such SSFR dependence of the fraction and the evolution of SSFRs of star-forming galaxies. The fraction at a given SSFR also appears to decrease with time, but this can be due to the effect of the morphological k correction. We suggest that these results are understood by the gravitational fragmentation model for the formation of giant clumps in disk galaxies, where the gas mass fraction is a crucial parameter.« less

How Spherical Is a Cube (Gravitationally)?

NASA Astrophysics Data System (ADS)

Sanny, Jeff; Smith, David

2015-02-01

An important concept that is presented in the discussion of Newton's law of universal gravitation is that the gravitational effect external to a spherically symmetric mass distribution is the same as if all of the mass of the distribution were concentrated at the center.1,2 By integrating over ring elements of a spherical shell, we show that the gravitational force on a point mass outside the shell is the same as that of a particle with the same mass as the shell at its center. This derivation works for objects with spherical symmetry while depending on the fact that the gravitational force between two point masses varies inversely as the square of their separation.3 If these conditions are not met, then the problem becomes more difficult. In this paper, we remove the condition of spherical symmetry and examine the gravitational force between two uniform cubes.

Bose polaron problem: Effect of mass imbalance on binding energy

NASA Astrophysics Data System (ADS)

Ardila, L. A. Peña; Giorgini, S.

2016-12-01

By means of quantum Monte Carlo methods we calculate the binding energy of an impurity immersed in a Bose-Einstein condensate at T =0 . The focus is on the attractive branch of the Bose polaron and on the role played by the mass imbalance between the impurity and the surrounding particles. For an impurity resonantly coupled to the bath, we investigate the dependence of the binding energy on the mass ratio and on the interaction strength within the medium. In particular, we determine the equation of state in the case of a static (infinite mass) impurity, where three-body correlations are irrelevant and the result is expected to be a universal function of the gas parameter. For the mass ratio corresponding to 40K impurities in a gas of 87Rb atoms, we provide an explicit comparison with the experimental findings of a recent study carried out at JILA.

Effect of food restriction on energy budget in warm-acclimated striped hamsters.

PubMed

Zhao, Zhi-Jun; Chi, Qing-Sheng; Zhao, Liang; Zhu, Qiao-Xia; Cao, Jing; Wang, De-Hua

2015-08-01

The capacity of small mammals to sustain periods of food shortage largely depends on the adaptive regulation of energy budget in response to the decrease in food supply. In addition to food availability, ambient temperature (Ta) is an important factor affecting the rates of both energy intake and expenditure. To examine the effect of Ta on energy strategy and the capacity to sustain food shortage, striped hamsters were exposed to a warm condition (30°C) and were then restricted to 70% of ad libitum food intake. Body mass, energy intake and expenditure and physiological markers indicative of thermogenesis were measured. Warm exposure had no effect on body mass and digestibility, but decreased energy intake, basal metabolic rate and maximum nonshivering thermogenesis. The mitochondria protein content, cytochrome c oxidase activity and uncoupling protein 1 level of brown adipose tissue were significantly lower in hamsters at 30°C than at 21°C. Food restriction induced a significant decrease in body mass, but the decreased body mass was attenuated at 30°C relative to 21°C. This suggests that striped hamsters could not compensate for the limited food supply by decreasing daily energy expenditure at 21°C, whereas they could at 30°C. The significant reductions in the rates of metabolism and thermogenesis in warm-acclimated hamsters increase the capacity to cope with food shortage. Although, it remains uncertain whether this response represents some generalized evolutionary adaptation, the Ta-dependent adjustment in the capacity to survive food restriction may reflect that warm acclimation plays an important role in adaptive regulation of both physiology and behavior in response to the variations of food availability. Copyright © 2015 Elsevier Inc. All rights reserved.

Equation of state for nucleonic matter and its quark mass dependence from the nuclear force in lattice QCD.

PubMed

Inoue, Takashi; Aoki, Sinya; Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Ishii, Noriyoshi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji

2013-09-13

Quark mass dependence of the equation of state (EOS) for nucleonic matter is investigated, on the basis of the Brueckner-Hartree-Fock method with the nucleon-nucleon interaction extracted from lattice QCD simulations. We observe saturation of nuclear matter at the lightest available quark mass corresponding to the pseudoscalar meson mass ≃469  MeV. Mass-radius relation of the neutron stars is also studied with the EOS for neutron-star matter from the same nuclear force in lattice QCD. We observe that the EOS becomes stiffer and thus the maximum mass of neutron star increases as the quark mass decreases toward the physical point.

Prompt merger collapse and the maximum mass of neutron stars.

PubMed

Bauswein, A; Baumgarte, T W; Janka, H-T

2013-09-27

We perform hydrodynamical simulations of neutron-star mergers for a large sample of temperature-dependent nuclear equations of state and determine the threshold mass above which the merger remnant promptly collapses to form a black hole. We find that, depending on the equation of state, the threshold mass is larger than the maximum mass of a nonrotating star in isolation by between 30 and 70 percent. Our simulations also show that the ratio between the threshold mass and maximum mass is tightly correlated with the compactness of the nonrotating maximum-mass configuration. We speculate on how this relation can be used to derive constraints on neutron-star properties from future observations.

Investigation of mass dependence effects for the accurate determination of molybdenum isotope amount ratios by MC-ICP-MS using synthetic isotope mixtures.

PubMed

Malinovsky, Dmitry; Dunn, Philip J H; Petrov, Panayot; Goenaga-Infante, Heidi

2015-01-01

Methodology for absolute Mo isotope amount ratio measurements by multicollector inductively coupled plasma-mass spectrometry (MC-ICP-MS) using calibration with synthetic isotope mixtures (SIMs) is presented. For the first time, synthetic isotope mixtures prepared from seven commercially available isotopically enriched molybdenum metal powders ((92)Mo, (94)Mo, (95)Mo, (96)Mo, (97)Mo, (98)Mo, and (100)Mo) are used to investigate whether instrumental mass discrimination of Mo isotopes in MC-ICP-MS is consistent with mass-dependent isotope distribution. The parent materials were dissolved and mixed as solutions to obtain mixtures with accurately known isotope amount ratios. The level of elemental impurities in the isotopically enriched molybdenum metal powders was quantified by ICP-MS by using both high-resolution and reaction cell instruments to completely resolve spectral interferences. The Mo isotope amount ratio values with expanded uncertainty (k = 2), determined by MC-ICP-MS for a high-purity Mo rod from Johnson Matthey, were as follows: (92)Mo/(95)Mo = 0.9235(9), (94)Mo/(95)Mo = 0.5785(8), (96)Mo/(95)Mo = 1.0503(9), (97)Mo/(95)Mo = 0.6033(6), (98)Mo/(95)Mo = 1.5291(20), and (100)Mo/(95)Mo = 0.6130(7). A full uncertainty budget for the measurements is presented which shows that the largest contribution to the uncertainty budget comes from correction for elemental impurities (∼51%), followed by the contribution from weighing operations (∼26 %). The atomic weight of molybdenum was calculated to be 95.947(2); the uncertainty in parentheses is expanded uncertainty with the coverage factor of 2. A particular advantage of the developed method is that calibration factors for all six Mo isotope amount ratios, involving the (95)Mo isotope, were experimentally determined. This allows avoiding any assumption on mass-dependent isotope fractions in MC-ICP-MS, inherent to the method of double spike previously used for Mo isotope amount ratio measurements. However, data obtained in this study show that instrumental mass discrimination in MC-ICP-MS is consistent with mass-dependent Mo isotope fractionation. This was demonstrated by a good agreement between experimentally obtained and theoretically expected values of the exponent of isotope fractionation, β, for each triad of Mo isotopes.

Just entertainment: effects of TV series about intrigue on young adults

PubMed Central

Wang, Fei; Lin, Shengdong; Ke, Xue

2015-01-01

The potential harmful effects of media violence have been studied systematically and extensively. However, very little attention has been devoted to the intrigue and struggles between people depicted in the mass media. A longitudinal randomized experimental group-control group, pretest–posttest design study was conducted to examine the potential effects of this type of TV series on young adults. A typical and popular TV series was select as a stimulus. By scrutinizing the outline of this TV series and inspired by studies of the effects of media violence, one behavioral observation and five scales were adopted as dependent measures. The study did not find any effect of the intrigue TV series on any of the six dependent variables. Finally, possible interference variables or moderators were discussed. PMID:26029127

Time dispersion of energetic solar particles, unexpected velocity and species dependence

NASA Technical Reports Server (NTRS)

Gallagher, J. J.; Hovestadt, D.; Klecker, B.; Gloeckler, G.; Fan, C. Y.

1976-01-01

The intensity-time behavior for protons and helium, as well as for carbon, oxygen and iron ions was measured following the 1974 September 19 solar flare for energies between 0.5 and approximately 5 MeV per nucleon. The profiles displayed a time dispersion which is inversely proportional to velocity for each individual species. In addition, at a given velocity the time dispersion also depended on the charge to mass ratio of the ion. Based on this latter dependence, it was concluded that while carbon and oxygen are essentially fully stripped, iron nuclei are not, having an effective charge Q = 10 + or - 5. The observed dispersion cannot be explained by purely rigidity dependent diffusive propagation.

SURFACE DENSITY EFFECTS IN QUENCHING: CAUSE OR EFFECT?

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

Lilly, Simon J.; Carollo, C. Marcella

2016-12-10

There are very strong observed correlations between the specific star formation rates (sSFRs) of galaxies and their mean surface mass densities, Σ, as well as other aspects of their internal structure. These strong correlations have often been taken to argue that the internal structure of a galaxy must play a major physical role, directly or indirectly, in the control of star formation. In this paper we show by means of a very simple toy model that these correlations can arise naturally without any such physical role once the observed evolution of the size–mass relation for star-forming galaxies is taken intomore » account. In particular, the model reproduces the sharp threshold in Σ between galaxies that are star-forming and those that are quenched and the evolution of this threshold with redshift. Similarly, it produces iso-quenched-fraction contours in the f {sub Q}( m , R {sub e}) plane that are almost exactly parallel to lines of constant Σ for centrals and shallower for satellites. It does so without any dependence on quenching on size or Σ and without invoking any differences between centrals and satellites, beyond the different mass dependences of their quenching laws. The toy model also reproduces several other observations, including the sSFR gradients within galaxies and the appearance of inside-out build-up of passive galaxies. Finally, it is shown that curvature in the main-sequence sSFR–mass relation can produce curvature in the apparent B / T ratios with mass. Our analysis therefore suggests that many of the strong correlations that are observed between galaxy structure and sSFR may well be a consequence of things unrelated to quenching and should not be taken as evidence of the physical processes that drive quenching.« less

Constraints on the Evolution of the Galaxy Stellar Mass Function I: Role of Star Formation, Mergers, and Stellar Stripping

NASA Astrophysics Data System (ADS)

Contini, E.; Kang, Xi; Romeo, A. D.; Xia, Q.

2017-03-01

We study the connection between the observed star formation rate-stellar mass (SFR-M *) relation and the evolution of the stellar mass function (SMF) by means of a subhalo abundance matching technique coupled to merger trees extracted from an N-body simulation. Our approach, which considers both galaxy mergers and stellar stripping, is to force the model to match the observed SMF at redshift z> 2, and let it evolve down to the present time according to the observed SFR-M * relation. In this study, we use two different sets of SMFs and two SFR-M * relations: a simple power law and a relation with a mass-dependent slope. Our analysis shows that the evolution of the SMF is more consistent with an SFR-M * relation with a mass-dependent slope, in agreement with predictions from other models of galaxy evolution and recent observations. In order to fully and realistically describe the evolution of the SMF, both mergers and stellar stripping must be considered, and we find that both have almost equal effects on the evolution of SMF at the massive end. Taking into account the systematic uncertainties in the observed data, the high-mass end of the SMF obtained by considering stellar stripping results in good agreement with recent observational data from the Sloan Digital Sky Survey. At {log} {M}* < 11.2, our prediction at z = 0.1 is close to Li & White data, but the high-mass end ({log} {M}* > 11.2) is in better agreement with D’Souza et al. data which account for more massive galaxies.

Sex- and concentration-dependent effects of predator feces on seasonal regulation of body mass in the bank vole Clethrionomys glareolus.

PubMed

Tidhar, Wendy L; Bonier, Frances; Speakman, John R

2007-11-01

Increased perception of predation risk can cause changes in activity, feeding and reproductive behavior in a wide range of taxa. Many small mammals in the temperate zone exhibit fluctuations in body mass in response to changing photoperiod. Bank voles lose body mass in winter which they regain when photoperiod increases in the spring. To determine if predation risk affects seasonal changes in body mass (BM), bank voles were exposed to two concentrations (low: LC and high: HC) of weasel feces. Food intake (FI) and daily energy expenditure (DEE) were measured to establish if differences in body mass were due to adjustment in energy intake or expenditure. Fecal corticosterone (CORT) was measured to assess whether the voles had detected and responded to predator feces as a physiological stressor. Voles of both sexes had higher levels of fecal CORT in the groups exposed to weasel feces compared to controls. Voles responded to the predator feces in a sex- and concentration-dependent manner. Males responded to LC feces by gaining less mass following the change in photoperiod. This was mediated by reduced FI and higher DEE. Female voles also gained less BM in response to HC feces, but increased both FI and DEE. We hypothesize that males may gain a short-term advantage by lowering BM in response to predation risk, which may be regained without affecting reproductive success. The consequences of mass loss in females may be more significant as this may delay the onset of breeding or reduce the size or number of young, thereby negatively affecting breeding success.

Quenching of Star-formation Activity of High-redshift Galaxies in Cluster and Field

NASA Astrophysics Data System (ADS)

Lee, Seong-Kook; Im, Myungshin; Kim, Jae-Woo; Lotz, Jennifer; McPartland, Conor; Peth, Michael; Koekemoer, Anton M.

2015-08-01

How the galaxy evolution differs at different environment is one of intriguing questions in the study of structure formation. At local, galaxy properties are well known to be clearly different in different environments. However, it is still an open question how this environment-dependent trend has been shaped.In this presentation, we will present the results of our investigation about the evolution of star-formation properties of galaxies over a wide redshift range, from z~ 2 to z~0.5, focusing its dependence on their stellar mass and environment. In the UKIDSS/UDS region, covering ~2800 arcmin2, we estimated photometric redshifts and stellar population properties, such as stellar masses and star-formation rates, using the deep optical and near-infrared data available in this field. Then, we identified galaxy cluster candidates within the given redshift range.Through the analysis and comparison of star-formation (SF) properties of galaxies in clusters and in field, we found interesting results regarding the evolution of SF properties of galaxies: (1) regardless of redshifts, stellar mass is a key parameter controlling quenching of star formation in galaxies; (2) At z<1, environmental effects become important at quenching star formation regardless of stellar mass of galaxies; and (3) However, the result of the environmental quenching is prominent only for low mass galaxies (M* < 1010 M⊙) since the star formation in most of high mass galaxies are already quenched at z > 1.

Determination of O₂ Mass Transport at the Pt | PFSA Ionomer Interface under Reduced Relative Humidity.

PubMed

Novitski, David; Holdcroft, Steven

2015-12-16

Oxygen mass transport resistance through the ionomer component in the cathode catalyst layer is considered to contribute overpotential losses in polymer electrolyte membrane fuel cells. Whereas it is known that water uptake, water transport, and proton conductivity are reduced upon reducing relative humidity, the effect on oxygen mass transport remains unknown. We report a two-electrode approach to determine mass transport coefficients for the oxygen reduction reaction in air at the Pt/perfluorosulfonic acid ionomer membrane interface between 90 and 30% RH at 70 °C using a Pt microdisk in a solid state electrochemical cell. Potential-step chronoamperometry was performed at specific mass-transport limiting potentials to allow for the elucidation of the oxygen diffusion coefficient (D(bO2)) and oxygen concentration (c(bO2)). In our efforts, novel approaches in data acquisition, as well as analysis, were examined because of the dynamic nature of the membrane under lowered hydration conditions. Linear regression analysis reveals a decrease in oxygen permeability (D(bO2c(bO2)) by a factor of 1.7 and 3.4 from 90 to 30% RH for Nafion 211 membrane and membranes cast from Nafion DE2020 ionomer solutions, respectively. Additionally, nonlinear curve fitting by way of the Shoup-Szabo equation is employed to analyze the entire current transient during potential step controlled ORR. We also report on the presence of an RH dependence of our previously reported time-dependency measurements for O2 mass transport coefficients.

The massive end of the luminosity and stellar mass functions and clustering from CMASS to SDSS: evidence for and against passive evolution

NASA Astrophysics Data System (ADS)

Bernardi, M.; Meert, A.; Sheth, R. K.; Huertas-Company, M.; Maraston, C.; Shankar, F.; Vikram, V.

2016-02-01

We describe the luminosity function, based on Sérsic fits to the light profiles, of CMASS galaxies at z ˜ 0.55. Compared to previous estimates, our Sérsic-based reductions imply more luminous, massive galaxies, consistent with the effects of Sérsic- rather than Petrosian or de Vaucouleur-based photometry on the Sloan Digital Sky Survey (SDSS) main galaxy sample at z ˜ 0.1. This implies a significant revision of the high-mass end of the correlation between stellar and halo mass. Inferences about the evolution of the luminosity and stellar mass functions depend strongly on the assumed, and uncertain, k + e corrections. In turn, these depend on the assumed age of the population. Applying k + e corrections taken from fitting the models of Maraston et al. to the colours of both SDSS and CMASS galaxies, the evolution of the luminosity and stellar mass functions appears impressively passive, provided that the fits are required to return old ages. However, when matched in comoving number- or luminosity-density, the SDSS galaxies are less strongly clustered compared to their counterparts in CMASS. This rules out the passive evolution scenario, and, indeed, any minor merger scenarios which preserve the rank ordering in stellar mass of the population. Potential incompletenesses in the CMASS sample would further enhance this mismatch. Our analysis highlights the virtue of combining clustering measurements with number counts.

ON THE RELIABILITY OF STELLAR AGES AND AGE SPREADS INFERRED FROM PRE-MAIN-SEQUENCE EVOLUTIONARY MODELS

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

Hosokawa, Takashi; Offner, Stella S. R.; Krumholz, Mark R., E-mail: Takashi.Hosokawa@jpl.nasa.gov, E-mail: hosokwtk@gmail.com

2011-09-10

We revisit the problem of low-mass pre-main-sequence stellar evolution and its observational consequences for where stars fall on the Hertzsprung-Russell diagram (HRD). In contrast to most previous work, our models follow stars as they grow from small masses via accretion, and we perform a systematic study of how the stars' HRD evolution is influenced by their initial radius, by the radiative properties of the accretion flow, and by the accretion history, using both simple idealized accretion histories and histories taken from numerical simulations of star cluster formation. We compare our numerical results to both non-accreting isochrones and to the positionsmore » of observed stars in the HRD, with a goal of determining whether both the absolute ages and the age dispersions inferred from non-accreting isochrones are reliable. We show that non-accreting isochrones can sometimes overestimate stellar ages for more massive stars (those with effective temperatures above {approx}3500 K), thereby explaining why non-accreting isochrones often suggest a systematic age difference between more and less massive stars in the same cluster. However, we also find the only way to produce a similar overestimate for the ages of cooler stars is if these stars grow from {approx}0.01 M{sub sun} seed protostars that are an order of magnitude smaller than predicted by current theoretical models, and if the size of the seed protostar correlates systematically with the final stellar mass at the end of accretion. We therefore conclude that, unless both of these conditions are met, inferred ages and age spreads for cool stars are reliable, at least to the extent that the observed bolometric luminosities and temperatures are accurate. Finally, we note that the time dependence of the mass accretion rate has remarkably little effect on low-mass stars' evolution on the HRD, and that such time dependence may be neglected for all stars except those with effective temperatures above {approx}4000 K.« less

The Safety, Pharmacokinetics, and Effects of LGD-4033, a Novel Nonsteroidal Oral, Selective Androgen Receptor Modulator, in Healthy Young Men

PubMed Central

Basaria, Shehzad; Collins, Lauren; Dillon, E. Lichar; Orwoll, Katie; Storer, Thomas W.; Miciek, Renee; Ulloor, Jagadish; Zhang, Anqi; Eder, Richard; Zientek, Heather; Gordon, Gilad; Kazmi, Syed; Sheffield-Moore, Melinda

2013-01-01

Background. Concerns about potential adverse effects of testosterone on prostate have motivated the development of selective androgen receptor modulators that display tissue-selective activation of androgenic signaling. LGD-4033, a novel nonsteroidal, oral selective androgen receptor modulator, binds androgen receptor with high affinity and selectivity. Objectives. To evaluate the safety, tolerability, pharmacokinetics, and effects of ascending doses of LGD-4033 administered daily for 21 days on lean body mass, muscle strength, stair-climbing power, and sex hormones. Methods. In this placebo-controlled study, 76 healthy men (21–50 years) were randomized to placebo or 0.1, 0.3, or 1.0 mg LGD-4033 daily for 21 days. Blood counts, chemistries, lipids, prostate-specific antigen, electrocardiogram, hormones, lean and fat mass, and muscle strength were measured during and for 5 weeks after intervention. Results. LGD-4033 was well tolerated. There were no drug-related serious adverse events. Frequency of adverse events was similar between active and placebo groups. Hemoglobin, prostate-specific antigen, aspartate aminotransferase, alanine aminotransferase, or QT intervals did not change significantly at any dose. LGD-4033 had a long elimination half-life and dose-proportional accumulation upon multiple dosing. LGD-4033 administration was associated with dose-dependent suppression of total testosterone, sex hormone–binding globulin, high density lipoprotein cholesterol, and triglyceride levels. follicle-stimulating hormone and free testosterone showed significant suppression at 1.0-mg dose only. Lean body mass increased dose dependently, but fat mass did not change significantly. Hormone levels and lipids returned to baseline after treatment discontinuation. Conclusions. LGD-4033 was safe, had favorable pharmacokinetic profile, and increased lean body mass even during this short period without change in prostate-specific antigen. Longer randomized trials should evaluate its efficacy in improving physical function and health outcomes in select populations. PMID:22459616

Frequency graded 1D metamaterials: A study on the attenuation bands

NASA Astrophysics Data System (ADS)

Banerjee, Arnab; Das, Raj; Calius, Emilio P.

2017-08-01

Depending on the frequency, waves can either propagate (transmission band) or be attenuated (attenuation band) while travelling through a one-dimensional spring-mass chain with internal resonators. The literature on wave propagation through a 1D mass-in-mass chain is vast and continues to proliferate because of its versatile applicability in condensed matter physics, optics, chemistry, acoustics, and mechanics. However, in all these areas, a uniformly periodic arrangement of identical linear resonating units is normally used which limits the attenuation band to a narrow frequency range. To counter this limitation of linear uniformly periodic metamaterials, the attenuation bandwidth in a one-dimensional finite chain with frequency graded linear internal resonators are investigated in this paper. The result shows that a properly tuned frequency graded arrangement of resonating units can extend the upper part of the attenuation band of 1D metamaterial theoretically up to infinity and also increases the lower part of the attenuation bandwidth by around 40% of an equivalent uniformly periodic metamaterial without increasing the mass. Therefore, the frequency graded metamaterials can be a potential solution towards low frequency and wideband acoustic or vibration insulation. In addition, this paper provides analytical expressions for the attenuation and transmission frequency limits for a periodic mass-in-mass metamaterial and demonstrates the attenuation band is generated by the high absolute value of the effective mass not only due to the negative effective mass.

The effect of arsenic chemical form and mixing regime on arsenic mass transfer from soil to magnetite.

PubMed

Yang, Kyung; Kim, Byung-Chul; Nam, Kyoungphile; Choi, Yongju

2017-03-01

This study investigated the effect of chemical forms of arsenic (As) and soil-magnetite mixing regimes on As mass transfer in magnetite-amended soil. Two soil samples with different component ratios of As chemical forms were prepared. In the absence of magnetite, the amount of desorbable As was strongly dependent on the fraction of easily extractable As in soil. Contact of the soils with magnetite in a slurry phase significantly reduced soil As concentration for both soils. Changes in As concentrations in soil, magnetite, and water by the slurry phase contact were simulated using an As mass transfer model. The model parameters were determined independently for each process of As soil desorption and magnetite sorption. The experimentally measured As mass transfer from soil to magnetite was significantly greater than the simulation result. By sequential extraction, it was observed that the soil As concentration was significantly reduced not only for easily extractable As, but also for relatively strongly bound forms of As. Enclosing the magnetite in a dialysis bag substantially limited the As mass transfer from soil to magnetite. These results suggest that improving the mixture between Fe oxides and soils can facilitate the effectiveness of As stabilization using Fe oxides.

Gauge invariance and kaon production in deep inelastic scattering at low scales

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

Guerrero, Juan V.; Accardi, Alberto

This work focuses on hadron mass effects in calculations of semi-inclusive kaon production in lepton-Deuteron deeply inelastic scattering at HERMES and COMPASS kinematics. In the collinear factorization framework, the corresponding cross section is shown to factorize, at leading order and leading twist, into products of parton distributions and fragmentation functions evaluated in terms of kaon- and nucleon-mass-dependent scaling variables, and to respect gauge invariance. It is found that hadron mass corrections for integrated kaon multiplicities sizeably reduce the apparent large discrepancy between measurements of K + + K - multiplicities performed by the two collaborations, and fully reconcile their Kmore » +/K - ratios.« less

Higgs production via gluon fusion in k{sub T} factorisation

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

Hautmann, F.; Jung, H.; Pandis, V.

2011-07-15

Theoretical studies of Higgs production via gluon fusion are frequently carried out in the limit where the top quark mass is much larger than the Higgs mass, an approximation which reduces the top quark loop to an effective vertex. We present a numerical analysis of the error thus introduced by performing a Monte Carlo calculation for gg{yields}h in k{sub T}-factorisation, using the parton shower generator CASCADE. By examining both inclusive and exclusive quantities, we find that retaining the top-mass dependence results in only a small enhancement of the cross-section. We then proceed to compare CASCADE to the collinear Monte Carlosmore » PYTHIA, MC-NLO and POWHEG.« less

Kinetic Study of Mass Transfer by Sodium Hydroxide in Nickel Under Free-convection Conditions /by Don R. Mosher and Robert A. Lad

NASA Technical Reports Server (NTRS)

Mosher, Don R; Lad, Robert A

1954-01-01

An investigation was conducted using static capsules fabricated from "L" nickel tubing to determine the effect of temperature level, temperature gradient, and test duration on corrosion and mass transfer by molten sodium hydroxide under free-convection conditions. A base temperature range from 1000 degrees to 1600 degrees F with temperature differences to 500 degrees was studied. The rate of mass transfer was found to be strongly dependent on both temperature level and gradient. The rate shows little tendency to decrease for test durations up to 200 hours, although the concentration of nickel in the melt approaches a limited value after 100 hours.

Dynamic Modeling Accuracy Dependence on Errors in Sensor Measurements, Mass Properties, and Aircraft Geometry

NASA Technical Reports Server (NTRS)

Grauer, Jared A.; Morelli, Eugene A.

2013-01-01

A nonlinear simulation of the NASA Generic Transport Model was used to investigate the effects of errors in sensor measurements, mass properties, and aircraft geometry on the accuracy of dynamic models identified from flight data. Measurements from a typical system identification maneuver were systematically and progressively deteriorated and then used to estimate stability and control derivatives within a Monte Carlo analysis. Based on the results, recommendations were provided for maximum allowable errors in sensor measurements, mass properties, and aircraft geometry to achieve desired levels of dynamic modeling accuracy. Results using other flight conditions, parameter estimation methods, and a full-scale F-16 nonlinear aircraft simulation were compared with these recommendations.

Gauge invariance and kaon production in deep inelastic scattering at low scales

DOE PAGES

Guerrero, Juan V.; Accardi, Alberto

2018-06-08

This work focuses on hadron mass effects in calculations of semi-inclusive kaon production in lepton-Deuteron deeply inelastic scattering at HERMES and COMPASS kinematics. In the collinear factorization framework, the corresponding cross section is shown to factorize, at leading order and leading twist, into products of parton distributions and fragmentation functions evaluated in terms of kaon- and nucleon-mass-dependent scaling variables, and to respect gauge invariance. It is found that hadron mass corrections for integrated kaon multiplicities sizeably reduce the apparent large discrepancy between measurements of K + + K - multiplicities performed by the two collaborations, and fully reconcile their Kmore » +/K - ratios.« less

Mass dependence of calcium isotope fractionations in crown-ether resin chromatography.

PubMed

Fujii, Yasuhiko; Nomura, Masao; Kaneshiki, Tositaka; Sakuma, Yoichi; Suzuki, Tatsuya; Umehara, Saori; Kishimoto, Tadahumi

2010-06-01

Benzo 18-crown-6-ether resin was synthesised by the phenol condensation polymerisation process in porous silica beads, of which particle diameter was ca 60micro Calcium adsorption chromatography was performed with the synthesised resin packed in a glass column. The effluent was sampled in fractions, and the isotopic abundance ratios of (42)Ca, (43)Ca, (44)Ca, and (48)Ca against (40)Ca were measured by a thermo-ionisation mass spectrometer. The enrichment of heavier calcium isotopes was observed at the front boundary of calcium adsorption chromatogram. The mass dependence of mutual separation of calcium isotopes was analysed by using the three-isotope-plots method. The slopes of three-isotope-plots indicate the relative values of mutual separation coefficients for concerned isotopic pairs. The results have shown the normal mass dependence; isotope fractionation is proportional to the reduced mass difference, (M - M')/MM', where M and M' are masses of heavy and light isotope, respectively. The mass dependence clarifies that the isotope fractionations are originated from molecular vibration. The observed separation coefficient epsilon is 3.1x10(-3) for the pair of (40)Ca and (48)Ca. Productivity of enriched (48)Ca by crown-ether-resin was discussed as the function of the separation coefficient and the height equivalent to the theoretical plate.

An equivalent viscoelastic model for rock mass with parallel joints

NASA Astrophysics Data System (ADS)

Li, Jianchun; Ma, Guowei; Zhao, Jian

2010-03-01

An equivalent viscoelastic medium model is proposed for rock mass with parallel joints. A concept of "virtual wave source (VWS)" is proposed to take into account the wave reflections between the joints. The equivalent model can be effectively applied to analyze longitudinal wave propagation through discontinuous media with parallel joints. Parameters in the equivalent viscoelastic model are derived analytically based on longitudinal wave propagation across a single rock joint. The proposed model is then verified by applying identical incident waves to the discontinuous and equivalent viscoelastic media at one end to compare the output waves at the other end. When the wavelength of the incident wave is sufficiently long compared to the joint spacing, the effect of the VWS on wave propagation in rock mass is prominent. The results from the equivalent viscoelastic medium model are very similar to those determined from the displacement discontinuity method. Frequency dependence and joint spacing effect on the equivalent viscoelastic model and the VWS method are discussed.

Strange stars in f( R) theories of gravity in the Palatini formalism

NASA Astrophysics Data System (ADS)

Panotopoulos, Grigoris

2017-05-01

In the present work we study strange stars in f( R) theories of gravity in the Palatini formalism. We consider two concrete well-known cases, namely the R+R^2/(6 M^2) model as well as the R-μ ^4/R model for two different values of the mass parameter M or μ . We integrate the modified Tolman-Oppenheimer-Volkoff equations numerically, and we show the mass-radius diagram for each model separately. The standard case corresponding to the General Relativity is also shown in the same figure for comparison. Our numerical results show that the interior solution can be vastly different depending on the model and/or the value of the parameter of each model. In addition, our findings imply that (i) for the cosmologically interesting values of the mass scales M,μ the effect of modified gravity on strange stars is negligible, while (ii) for the values predicting an observable effect, the modified gravity models discussed here would be ruled out by their cosmological effects.

Effects of mass media action on the Axelrod model with social influence

NASA Astrophysics Data System (ADS)

Rodríguez, Arezky H.; Moreno, Y.

2010-07-01

The use of dyadic interaction between agents, in combination with homophily (the principle that “likes attract”) in the Axelrod model for the study of cultural dissemination, has two important problems: the prediction of monoculture in large societies and an extremely narrow window of noise levels in which diversity with local convergence is obtained. Recently, the inclusion of social influence has proven to overcome them [A. Flache and M. W. Macy, e-print arXiv:0808.2710]. Here, we extend the Axelrod model with social influence interaction for the study of mass media effects through the inclusion of a superagent which acts over the whole system and has non-null overlap with each agent of the society. The dependence with different parameters as the initial social diversity, size effects, mass media strength, and noise is outlined. Our results might be relevant in several socioeconomic contexts and for the study of the emergence of collective behavior in complex social systems.

Effects of mass media action on the Axelrod model with social influence.

PubMed

Rodríguez, Arezky H; Moreno, Y

2010-07-01

The use of dyadic interaction between agents, in combination with homophily (the principle that "likes attract") in the Axelrod model for the study of cultural dissemination, has two important problems: the prediction of monoculture in large societies and an extremely narrow window of noise levels in which diversity with local convergence is obtained. Recently, the inclusion of social influence has proven to overcome them [A. Flache and M. W. Macy, e-print arXiv:0808.2710]. Here, we extend the Axelrod model with social influence interaction for the study of mass media effects through the inclusion of a superagent which acts over the whole system and has non-null overlap with each agent of the society. The dependence with different parameters as the initial social diversity, size effects, mass media strength, and noise is outlined. Our results might be relevant in several socioeconomic contexts and for the study of the emergence of collective behavior in complex social systems.

Accretion disks around black holes

NASA Technical Reports Server (NTRS)

Abramowicz, M. A.

1994-01-01

The physics of accretion flow very close to a black hole is dominated by several general relativistic effects. It cannot be described by the standard Shakura Sunyaev model or by its relativistic version developed by Novikov and Thome. The most important of these effects is a dynamical mass loss from the inner edge of the disk (Roche lobe overflow). The relativistic Roche lobe overflow induces a strong advective cooling, which is sufficient to stabilize local, axially symmetric thermal and viscous modes. It also stabilizes the non-axially-symmetric global modes discovered by Papaloizou and Pringle. The Roche lobe overflow, however, destabilizes sufficiently self-gravitating accretion disks with respect to a catastrophic runaway of mass due to minute changes of the gravitational field induced by the changes in the mass and angular momentum of the central black hole. One of the two acoustic modes may become trapped near the inner edge of the disk. All these effects, absent in the standard model, have dramatic implications for time-dependent behavior of the accretion disks around black holes.

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 1.3, and thus more than one mass-independent isotope effect is inferred. MIF of mercury can be caused by the nuclear volume effect. Schauble, 2007 has calculated nuclear volume fractionation scaling factors for a number of common mercury chemical species in equilibrium with Hg° vapor. From his calculations the nuclear field shift effect is larger in Δ199Hg than in Δ201Hg by approximately a factor of two. The predominant mercury chemical species in fish is methylmercury cysteine. From the experimental studies of Buchachenko and others (2004) on the reaction of methylmercury chloride with creatine kinase it seems reasonable to predicted that the thiol functional groups of cysteine gets enriched in 199Hg and 201Hg. Here the magnetic isotope effect (MIE) produces a kinetic partial separation of isotopes with non-zero nuclear spin quantum numbers from the even-N isotopes. The ratio of enrichment of Δ201Hg /Δ199Hg is predicted from theory to be 1.11, which is the ratio of the magnetic moments of 199Hg and 201Hg. Because mercury possesses two odd-N isotopes, it is possible to detect and evaluate the effects of two distinct, mass-independent isotope fractionating processes. From the data obtained on fish samples, we can deconvolute the contributions of the isotope effects of nuclear mass, spin and volume. For these samples the role of spin or the magnetic isotope effect is the most dominant.

Seismological properties of intermediate-mass stars

NASA Astrophysics Data System (ADS)

Audard, N.; Provost, J.

1994-02-01

Stars more massive than about 1.2 solar mass are characterized by a convective core, which induces at its frontier a rapid variation of the density, sound speed and Brunt-Vaisala frequency, close to a discontinuity. For three stars of 1, 1.5 and 2 solar mass we have studied the properties of p-mode frequencies of high radial order and low degree, and we present results on the effects on p-mode oscillations of some rapid variations of the internal structure. We first point out the difficulties of the classical asymptotic theory to represent with accuracy the p-mode spectrum of the stars considered. We compare the numerical frequencies with asymptotic and polynomial approximations obtained from fits. The variation of the derived global coefficients characterizing the p-mode spectrum along the evolutionary tracks has been estimated; it would help to separate the effects of age and mass of intermediate-mass stars. The sensitivity of these coefficients to stellar parameters substantially depends on the stellar mass and must be considered for asteroseismic calibration. The effects of rapid variations in the stellar internal structure are finally considered. An asymptotic formula taking into account the rapid variation of the sound speed at the convective core boundary of the 1.5 and 2 solar mass stars predicts an oscillatory behavior of the frequencies with a very large period. We also show that the second frequency difference delta2nu = nun, l - 2nun-1, l + nun-2, l exhibits a substantial oscillation which corresponds to the region of the He II ionization of the 1, 1.5 and 2 solar mass stars.

Density-dependent recruitment rates in great tits: the importance of being heavier

PubMed Central

Both, C.; Visser, M. E.; Verboven, N.

1999-01-01

In birds, individuals with a higher mass at fledging have a higher probability of recruiting into the breeding population. This can be because mass is an indicator of general condition and thereby of the ability to survive adverse circumstances and/or because fledging mass is positively related to competitive strength in interactions with other fledglings. This latter explanation leads to two testable predictions: (i) there is stronger selection for fledging mass when there is more severe competition (i.e. at higher densities); and (ii) that besides absolute fledging mass, relative mass of fledglings within a cohort is important. We test these two predictions in two great tit (Parus major) populations. The first prediction was met for one of the populations, showing that competition affects the importance of mass-dependent recruitment. The second prediction, that fledglings recruit relatively well if they are heavy compared to the other fledglings, is met for both populations. The consequence of the importance of relative rather than absolute fledging mass is that the fitness consequences of reproductive decisions affecting fledging mass, such as clutch size, depend on the decisions of the other individuals in the population.

Pesticide-contaminated feeds in integrated grass carp aquaculture: toxicology and bioaccumulation.

PubMed

Pucher, J; Gut, T; Mayrhofer, R; El-Matbouli, M; Viet, P H; Ngoc, N T; Lamers, M; Streck, T; Focken, U

2014-02-19

Effects of dissolved pesticides on fish are widely described, but little is known about effects of pesticide-contaminated feeds taken up orally by fish. In integrated farms, pesticides used on crops may affect grass carp that feed on plants from these fields. In northern Vietnam, grass carp suffer seasonal mass mortalities which may be caused by pesticide-contaminated plants. To test effects of pesticide-contaminated feeds on health and bioaccumulation in grass carp, a net-cage trial was conducted with 5 differently contaminated grasses. Grass was spiked with 2 levels of trichlorfon/fenitrothion and fenobucarb. Unspiked grass was used as a control. Fish were fed at a daily rate of 20% of body mass for 10 d. The concentrations of fenitrothion and fenobucarb in pond water increased over time. Effects on fish mortality were not found. Fenobucarb in feed showed the strongest effects on fish by lowering feed uptake, deforming the liver, increasing blood glucose and reducing cholinesterase activity in blood serum, depending on feed uptake. Fenobucarb showed increased levels in flesh in all treatments, suggesting bio-concentration. Trichlorfon and fenitrothion did not significantly affect feed uptake but showed concentration-dependent reduction of cholinesterase activity and liver changes. Fenitrothion showed bioaccumulation in flesh which was dependant on feed uptake, whereas trichlorfon was only detected in very low concentrations in all treatments. Pesticide levels were all detected below the maximum residue levels in food. The pesticide-contaminated feeds tested did not cause mortality in grass carp but were associated with negative physiological responses and may increase susceptibility to diseases.

A Green's function formulation of the k→ ·p→ theory in the presence of spin-orbit interaction and magnetic field: Application to the electronic structure and related properties of w-GaN

NASA Astrophysics Data System (ADS)

Shadangi, Subrat K.; Mishra, Sambit R.; Tripathi, Gouri S.

2018-01-01

We use a Green's function perturbation formalism in the presence of an applied magnetic field and spin-orbit effects in the effective mass representation (EMR). The lack of lattice translational symmetry of the vector potential in the presence of the magnetic field is considered by redefining the Green's function in terms of the Peierls' phase factor. The equation of motion of the Green's function as a function of a magnetic wave vector was solved using perturbation theory, leading to expressions for the effective mass and the g-factor. We study the electronic structure of wurtzite GaN theoretically using the resulting k→ ·π→ method, where k→ is the electronic wave vector and π→ is the relativistic momentum operator by considering the conduction band edge and three valence bands. The k→ ·π→ Hamiltonians for the conduction band edge and the valence bands are diagonalized, considering the conduction band and one valence band at a time. We obtain electron and hole dispersions. Effects of other bands are considered by using perturbation theory. Resulting dispersions agree with the results of other calculations. In order to study the effective mass and the g-factor, we use the eigenvalues and eigenfunctions obtained after the diagonalization. Our results for the effective masses and the g-factors agree fairly well with available theoretical and experimental results, Temperature dependence of both the electronic effective mass and g-factor is studied and trends obtained agree with the existing experimental data.

Self-consistent mean-field approach to the statistical level density in spherical nuclei

NASA Astrophysics Data System (ADS)

Kolomietz, V. M.; Sanzhur, A. I.; Shlomo, S.

2018-06-01

A self-consistent mean-field approach within the extended Thomas-Fermi approximation with Skyrme forces is applied to the calculations of the statistical level density in spherical nuclei. Landau's concept of quasiparticles with the nucleon effective mass and the correct description of the continuum states for the finite-depth potentials are taken into consideration. The A dependence and the temperature dependence of the statistical inverse level-density parameter K is obtained in a good agreement with experimental data.

[Multiple myeloma: current therapeutic approaches].

PubMed

Troussard, X; Bauduer, F; Leporrier, M

1992-01-01

The therapeutic strategy in multiple myeloma depends on age and tumor mass. Stage I must not be treated. The Melphalan Prednisone regimen is the reference for induction therapy because polychemotherapies are generally not superior. At this phase, the addition of Interferon alpha seems to be interesting. This drug has an important role during the steady-state phase. VAD represents the most efficient chemotherapy. Body hemi-irradiation is also useful. The analgesic effect and the decrease in the tumoral mass are the striking effects of this treatment. In young patients, high dose chemotherapy with bone marrow transplantation is proposed. Verapamil and anti-IL6 antibodies are currently being evaluated. Symptomatic treatment is essential in this non curable disease.

Effects of commercial aircraft operating environment on composite materials

NASA Technical Reports Server (NTRS)

Chapman, A. J.; Hoffman, D. J.; Hodges, W. T.

1980-01-01

Long term effects of commercial aircraft operating environment on the properties and durability of composite materials are being systematically explored. Composite specimens configured for various mechanical property tests are exposed to environmental conditions on aircraft in scheduled airline service, on racks at major airports, and to controlled environmental conditions in the laboratory. Results of tests following these exposures will identify critical parameters affecting composite durability, and correlation of the data will aid in developing methods for predicting durability. Interim results of these studies show that mass change of composite specimens on commercial aircraft depends upon the regional climate and season, and that mass loss from composite surfaces due to ultraviolet radiation can be largely prevented by aircraft paint.

A study of the convective flow as a function of external parameters in a high-pressure metal halide discharge lamp (HgDyI{sub 3})

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

Hajji, S.; HadjSalah, S.; Benhalima, A.

2016-06-15

This paper deals with the modelling of the convection processes in metal–halide lamp discharges (HgDyI{sub 3}). For this, we realized a 3D model, a steady, direct current powered and time-depending model for the solution of conservation equations relative to mass, momentum, and energy. After validation, this model was applied to the study of the effect of some parameters that have appeared on major transport phenomena of mass and energy in studying the lamp. Indeed, the electric current, the atomic ratio (Hg/Dy), and the effect of the convective transport have been studied.

A study of the convective flow as a function of external parameters in a high-pressure metal halide discharge lamp (HgDyI3)

NASA Astrophysics Data System (ADS)

Hajji, S.; HadjSalah, S.; Benhalima, A.; Charrada, K.; Zissis, G.

2016-06-01

This paper deals with the modelling of the convection processes in metal-halide lamp discharges (HgDyI3). For this, we realized a 3D model, a steady, direct current powered and time-depending model for the solution of conservation equations relative to mass, momentum, and energy. After validation, this model was applied to the study of the effect of some parameters that have appeared on major transport phenomena of mass and energy in studying the lamp. Indeed, the electric current, the atomic ratio (Hg/Dy), and the effect of the convective transport have been studied.

Size exclusion chromatography-gradients, an alternative approach to polymer gradient chromatography: 2. Separation of poly(meth)acrylates using a size exclusion chromatography-solvent/non-solvent gradient.

PubMed

Schollenberger, Martin; Radke, Wolfgang

2011-10-28

A gradient ranging from methanol to tetrahydrofuran (THF) was applied to a series of poly(methyl methacrylate) (PMMA) standards, using the recently developed concept of SEC-gradients. Contrasting to conventional gradients the samples eluted before the solvent, i.e. within the elution range typical for separations by SEC, however, the high molar mass PMMAs were retarded as compared to experiments on the same column using pure THF as the eluent. The molar mass dependence on retention volume showed a complex behaviour with a nearly molar mass independent elution for high molar masses. This molar mass dependence was explained in terms of solubility and size exclusion effects. The solubility based SEC-gradient was proven to be useful to separate PMMA and poly(n-butyl crylate) (PnBuA) from a poly(t-butyl crylate) (PtBuA) sample. These samples could be separated neither by SEC in THF, due to their very similar hydrodynamic volumes, nor by an SEC-gradient at adsorbing conditions, due to a too low selectivity. The example shows that SEC-gradients can be applied not only in adsorption/desorption mode, but also in precipitation/dissolution mode without risking blocking capillaries or breakthrough peaks. Thus, the new approach is a valuable alternative to conventional gradient chromatography. Copyright © 2011 Elsevier B.V. All rights reserved.

Mephedrone: use, subjective effects and health risks.

PubMed

Winstock, Adam; Mitcheson, Luke; Ramsey, John; Davies, Susannah; Puchnarewicz, Malgorzata; Marsden, John

2011-11-01

To assess the patterns of use, subjective effect profile and dependence liability of mephedrone, supported by corroborative urine toxicology. Cross-sectional structured telephone interview. UK-based drug users associated with the dance music scene. A total of 100 mephedrone users, recruited through their involvement with the dance music scene. Assessment of pattern of use, acute and after effects, DSM dependence criteria and gas chromatography-mass spectrometry urinalysis. Mephedrone consumption results in typical stimulant-related subjective effects: euphoria, increased concentration, talkativeness, urge to move, empathy, jaw clenching, reduced appetite and insomnia. Thirty per cent of the sample potentially met criteria for DSM-IV dependence and there was evidence of a strong compulsion to use the drug (47% had used the drug for 2 or more consecutive days). Self-reported recent consumption of mephedrone was confirmed by toxicological analysis in all of the 14 participants who submitted a urine sample. Mephedrone has a high abuse and health risk liability, with increased tolerance, impaired control and a compulsion to use, the predominant reported dependence symptoms. © 2011 The Authors, Addiction © 2011 Society for the Study of Addiction.

Theory of nitrogen doping of carbon nanoribbons: Edge effects

DOE PAGES

Jiang, Jie; Turnbull, Joseph; Lu, Wenchang; ...

2012-01-01

Nitrogen doping of a carbon nanoribbon is profoundly affected by its one-dimensional character, symmetry, and interaction with edge states. Using state-of-the-art ab initio calculations, including hybrid exact-exchange density functional theory, we find that, for N-doped zigzag ribbons, the electronic properties are strongly dependent upon sublattice effects due to the non-equivalence of the two sublattices. For armchair ribbons, N-doping effects are different depending upon the ribbon family: for families 2 and 0, the N-induced levels are in the conduction band, while for family 1 the N levels are in the gap. In zigzag nanoribbons, nitrogen close to the edge is amore » deep center, while in armchair nanoribbons its behavior is close to an effective-mass-like donor with the ionization energy dependent on the value of the band gap. In chiral nanoribbons, we find strong dependence of the impurity level and formation energy upon the edge position of the dopant, while such site-specificity is not manifested in the magnitude of the magnetization.« less

A novel selective androgen receptor modulator (SARM) MK-4541 exerts anti-androgenic activity in the prostate cancer xenograft R-3327G and anabolic activity on skeletal muscle mass & function in castrated mice.

PubMed

Chisamore, Michael J; Gentile, Michael A; Dillon, Gregory Michael; Baran, Matthew; Gambone, Carlo; Riley, Sean; Schmidt, Azriel; Flores, Osvaldo; Wilkinson, Hilary; Alves, Stephen E

2016-10-01

The androgen receptor (AR) is a member of the nuclear hormone receptor super family of transcription factors. Androgens play an essential role in the development, growth, and maintenance of male sex organs, as well as the musculoskeletal and central nervous systems. Yet with advancing age, androgens can drive the onset of prostate cancer, the second leading cause of cancer death in males within the United States. Androgen deprivation therapy (ADT) by pharmacologic and/or surgical castration induces apoptosis of prostate cells and subsequent shrinkage of the prostate and prostate tumors. However, ADT is associated with significant musculoskeletal and behavioral adverse effects. The unique pharmacological activity of selective androgen receptor modulator (SARM) MK-4541 recently has been reported as an AR antagonist with 5α-reductase inhibitor function. The molecule inhibits proliferation and induces apoptosis in AR positive, androgen dependent prostate cancer cells. Importantly, MK-4541 inhibited androgen-dependent prostate growth in male rats yet maintained lean body mass and bone formation following ovariectomy in female rats. In the present study, we evaluated the effects of SARM MK-4541 in the androgen-dependent Dunning R3327-G prostate carcinoma xenograft mouse model as well as on skeletal muscle mass and function, and AR-regulated behavior in mice. MK-4541 significantly inhibited the growth of R3327-G prostate tumors, exhibited anti-androgen effects on the seminal vesicles, reduced plasma testosterone concentrations in intact males, and inhibited Ki67 expression. MK-4541 treated xenografts appeared similar to xenografts in castrated mice. Importantly, we demonstrate that MK-4541 exhibited anabolic activity in androgen deficient conditions, increasing lean body mass and muscle function in adult castrated mice. Moreover, MK-4541 treatment restored general activity levels in castrated mice. Thus, MK-4541 exhibits an optimum profile as an adjuvant therapy to ADT which may provide potent anti-androgenic activity at the prostate yet protective activity on skeletal muscle and behavior in patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

Higgs Boson Pair Production in Gluon Fusion at Next-to-Leading Order with Full Top-Quark Mass Dependence.

PubMed

Borowka, S; Greiner, N; Heinrich, G; Jones, S P; Kerner, M; Schlenk, J; Schubert, U; Zirke, T

2016-07-01

We present the calculation of the cross section and invariant mass distribution for Higgs boson pair production in gluon fusion at next-to-leading order (NLO) in QCD. Top-quark masses are fully taken into account throughout the calculation. The virtual two-loop amplitude has been generated using an extension of the program GoSam supplemented with an interface to Reduze for the integral reduction. The occurring integrals have been calculated numerically using the program SecDec. Our results, including the full top-quark mass dependence for the first time, allow us to assess the validity of various approximations proposed in the literature, which we also recalculate. We find substantial deviations between the NLO result and the different approximations, which emphasizes the importance of including the full top-quark mass dependence at NLO.

Large effective mass and interaction-enhanced Zeeman splitting of K -valley electrons in MoSe2

NASA Astrophysics Data System (ADS)

Larentis, Stefano; Movva, Hema C. P.; Fallahazad, Babak; Kim, Kyounghwan; Behroozi, Armand; Taniguchi, Takashi; Watanabe, Kenji; Banerjee, Sanjay K.; Tutuc, Emanuel

2018-05-01

We study the magnetotransport of high-mobility electrons in monolayer and bilayer MoSe2, which show Shubnikov-de Haas (SdH) oscillations and quantum Hall states in high magnetic fields. An electron effective mass of 0.8 me is extracted from the SdH oscillations' temperature dependence; me is the bare electron mass. At a fixed electron density the longitudinal resistance shows minima at filling factors (FFs) that are either predominantly odd, or predominantly even, with a parity that changes as the density is tuned. The SdH oscillations are insensitive to an in-plane magnetic field, consistent with an out-of-plane spin orientation of electrons at the K point. We attribute the FF parity transitions to an interaction enhancement of the Zeeman energy as the density is reduced, resulting in an increased Zeeman-to-cyclotron energy ratio.

The investigation of substituent effects on the fragmentation pathways of pentacoordinated phenoxyspirophosphoranes by ESI-MSn.

PubMed

Cui, Xiaoyan; Sun, Can; Zhao, Pei; Wang, Yanyan; Guo, Yanchun; Zhao, Yufen; Cao, Shuxia

2018-04-01

The fragmentation pathways of pentacoordinated phenoxyspirophosphoranes were investigated in the positive mode by electrospray ionization multistage mass spectrometry. The results demonstrate that the sodium adducts of the title compounds undergo two competitive fragmentation pathways, and the fragmentation patterns are heavily dependent on the various substituent patterns at the phenolic group. An electron-withdrawing substituent at the ortho-position always results in the removal of a corresponding phenol analogue, while cleavage by spiroring opening becomes the predominant fragmentation pathway if an electron-donating substituent is at the phenolic group. The substituent effects on the competitive fragmentation pathways were further elucidated by theoretical calculations, single crystal structure analysis, and high-resolution mass spectrometry. The results contribute to the understanding of the gas-phase fragmentation reactions and the structure identification of spirophosphorane analogues by electrospray ionization multistage mass spectrometry. Copyright © 2018 John Wiley & Sons, Ltd.

Effect of mass and density of ambient gas on the interaction of laser-blow-off plasma plumes propagating in close proximity

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

Kumar, Bhupesh; Singh, R. K.; Kumar, Ajai, E-mail: ajai@ipr.res.in

2016-04-15

The effects of mass and pressure of ambient gas on the propagation dynamics of two laser-blow-off plasma plumes created in close proximity are investigated. A time gated fast imaging technique is used for recording the images of the laterally colliding plumes under different experimental conditions. Pressure is varied from 0.1 to 3 mbar in three ambient, i.e., helium, neon, and argon. Emphasis is given on the nature of shock-shock interaction under different ambient conditions. It has been observed that the shock-velocity, shape, strength, and their interactions are strongly dependent on the mass and density of the ambient gases. The rolemore » of the interacting shocks and their subsequent reflections on the formation and geometrical shape of the interaction region in different ambient conditions is briefly described.« less

Nature and mechanisms of elastic deformations for a rock mass with several workings. [Deviations from superposition of individual effects

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

Yagunov, A.S.; Seryakov, V.M.

1985-07-01

This paper presents results of a study which indicates that as a result of the solution for a nonuniform rock mass by the FEM it is established that, first, from the direction of the hanging wall of workings and at the surface, the nature of elastic deformation of the rock is equivalent to that observed under natural conditions, and from the direction of the lying wall of workings and close to their ends there is short-lived rotational creation of elastic displacements, extinguished as plastic deformation develops. Second, the superposition principle, taken as the basis for algebraic summation of displacements andmore » deformations due to individual workings, is not entirely observed in their joint effect on the rock mass in the elastic stage, and with plastic and shear deformation of rocks (partial or complete), depending on their bedding conditions.« less

Influence of multiple ion species on low-frequency electromagnetic wave instabilities. [in solar wind

NASA Technical Reports Server (NTRS)

Brinca, Armando L.; Tsurutani, Bruce T.

1989-01-01

The effect of multiple (singly ionized) coexisting newborn ion species on the stability of low-frequency electromagnetic waves was investigated using a plasma model in which solar wind magnetoplasma is made up of isotropic Maxwellian electron and proton populations with a common number density of 4.95/cu cm and temperatures equal to 17.2 eV and 6.9 eV, respectively. It is shown that the effect of multiple ions on wave growth, for given background magnetoplasma conditions and relative densities, depends not only on their mass but also on the physical nature of the wave modes. If the ion masses are disparate, each one of the coexisting ion beams tends to stimulate instabilities without undue influence from the other species. If the masses of newborn ions are similar, they can strongly catalyze wave growth of fluidlike nonresonant modes, but bring about weak growth enhancements in cyclotron resonant instabilities.

The galaxy-dark matter halo connection: which galaxy properties are correlated with the host halo mass?

NASA Astrophysics Data System (ADS)

Contreras, S.; Baugh, C. M.; Norberg, P.; Padilla, N.

2015-09-01

We demonstrate how the properties of a galaxy depend on the mass of its host dark matter subhalo, using two independent models of galaxy formation. For the cases of stellar mass and black hole mass, the median property value displays a monotonic dependence on subhalo mass. The slope of the relation changes for subhalo masses for which heating by active galactic nuclei becomes important. The median property values are predicted to be remarkably similar for central and satellite galaxies. The two models predict considerable scatter around the median property value, though the size of the scatter is model dependent. There is only modest evolution with redshift in the median galaxy property at a fixed subhalo mass. Properties such as cold gas mass and star formation rate, however, are predicted to have a complex dependence on subhalo mass. In these cases, subhalo mass is not a good indicator of the value of the galaxy property. We illustrate how the predictions in the galaxy property-subhalo mass plane differ from the assumptions made in some empirical models of galaxy clustering by reconstructing the model output using a basic subhalo abundance matching scheme. In its simplest form, abundance matching generally does not reproduce the clustering predicted by the models, typically resulting in an overprediction of the clustering signal. Using the predictions of the galaxy formation model for the correlations between pairs of galaxy properties, the basic abundance matching scheme can be extended to reproduce the model predictions more faithfully for a wider range of galaxy properties. Our results have implications for the analysis of galaxy clustering, particularly for low abundance samples.

2D nanosheet molybdenum disulphide (MoS2) modified electrodes explored towards the hydrogen evolution reaction

NASA Astrophysics Data System (ADS)

Rowley-Neale, Samuel J.; Brownson, Dale A. C.; Smith, Graham C.; Sawtell, David A. G.; Kelly, Peter J.; Banks, Craig E.

2015-10-01

We explore the use of two-dimensional (2D) MoS2 nanosheets as an electrocatalyst for the Hydrogen Evolution Reaction (HER). Using four commonly employed commercially available carbon based electrode support materials, namely edge plane pyrolytic graphite (EPPG), glassy carbon (GC), boron-doped diamond (BDD) and screen-printed graphite electrodes (SPE), we critically evaluate the reported electrocatalytic performance of unmodified and MoS2 modified electrodes towards the HER. Surprisingly, current literature focuses almost exclusively on the use of GC as an underlying support electrode upon which HER materials are immobilised. 2D MoS2 nanosheet modified electrodes are found to exhibit a coverage dependant electrocatalytic effect towards the HER. Modification of the supporting electrode surface with an optimal mass of 2D MoS2 nanosheets results in a lowering of the HER onset potential by ca. 0.33, 0.57, 0.29 and 0.31 V at EPPG, GC, SPE and BDD electrodes compared to their unmodified counterparts respectively. The lowering of the HER onset potential is associated with each supporting electrode's individual electron transfer kinetics/properties and is thus distinct. The effect of MoS2 coverage is also explored. We reveal that its ability to catalyse the HER is dependent on the mass deposited until a critical mass of 2D MoS2 nanosheets is achieved, after which its electrocatalytic benefits and/or surface stability curtail. The active surface site density and turn over frequency for the 2D MoS2 nanosheets is determined, characterised and found to be dependent on both the coverage of 2D MoS2 nanosheets and the underlying/supporting substrate. This work is essential for those designing, fabricating and consequently electrochemically testing 2D nanosheet materials for the HER.We explore the use of two-dimensional (2D) MoS2 nanosheets as an electrocatalyst for the Hydrogen Evolution Reaction (HER). Using four commonly employed commercially available carbon based electrode support materials, namely edge plane pyrolytic graphite (EPPG), glassy carbon (GC), boron-doped diamond (BDD) and screen-printed graphite electrodes (SPE), we critically evaluate the reported electrocatalytic performance of unmodified and MoS2 modified electrodes towards the HER. Surprisingly, current literature focuses almost exclusively on the use of GC as an underlying support electrode upon which HER materials are immobilised. 2D MoS2 nanosheet modified electrodes are found to exhibit a coverage dependant electrocatalytic effect towards the HER. Modification of the supporting electrode surface with an optimal mass of 2D MoS2 nanosheets results in a lowering of the HER onset potential by ca. 0.33, 0.57, 0.29 and 0.31 V at EPPG, GC, SPE and BDD electrodes compared to their unmodified counterparts respectively. The lowering of the HER onset potential is associated with each supporting electrode's individual electron transfer kinetics/properties and is thus distinct. The effect of MoS2 coverage is also explored. We reveal that its ability to catalyse the HER is dependent on the mass deposited until a critical mass of 2D MoS2 nanosheets is achieved, after which its electrocatalytic benefits and/or surface stability curtail. The active surface site density and turn over frequency for the 2D MoS2 nanosheets is determined, characterised and found to be dependent on both the coverage of 2D MoS2 nanosheets and the underlying/supporting substrate. This work is essential for those designing, fabricating and consequently electrochemically testing 2D nanosheet materials for the HER. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05164a|ART

Systematic and statistical uncertainties in simulated r-process abundances due to uncertain nuclear masses

DOE PAGES

Surman, Rebecca; Mumpower, Matthew; McLaughlin, Gail

2017-02-27

Unknown nuclear masses are a major source of nuclear physics uncertainty for r-process nucleosynthesis calculations. Here we examine the systematic and statistical uncertainties that arise in r-process abundance predictions due to uncertainties in the masses of nuclear species on the neutron-rich side of stability. There is a long history of examining systematic uncertainties by the application of a variety of different mass models to r-process calculations. Here we expand upon such efforts by examining six DFT mass models, where we capture the full impact of each mass model by updating the other nuclear properties — including neutron capture rates, β-decaymore » lifetimes, and β-delayed neutron emission probabilities — that depend on the masses. Unlike systematic effects, statistical uncertainties in the r-process pattern have just begun to be explored. Here we apply a global Monte Carlo approach, starting from the latest FRDM masses and considering random mass variations within the FRDM rms error. Here, we find in each approach that uncertain nuclear masses produce dramatic uncertainties in calculated r-process yields, which can be reduced in upcoming experimental campaigns.« less

Systematic and statistical uncertainties in simulated r-process abundances due to uncertain nuclear masses

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

Surman, Rebecca; Mumpower, Matthew; McLaughlin, Gail

Unknown nuclear masses are a major source of nuclear physics uncertainty for r-process nucleosynthesis calculations. Here we examine the systematic and statistical uncertainties that arise in r-process abundance predictions due to uncertainties in the masses of nuclear species on the neutron-rich side of stability. There is a long history of examining systematic uncertainties by the application of a variety of different mass models to r-process calculations. Here we expand upon such efforts by examining six DFT mass models, where we capture the full impact of each mass model by updating the other nuclear properties — including neutron capture rates, β-decaymore » lifetimes, and β-delayed neutron emission probabilities — that depend on the masses. Unlike systematic effects, statistical uncertainties in the r-process pattern have just begun to be explored. Here we apply a global Monte Carlo approach, starting from the latest FRDM masses and considering random mass variations within the FRDM rms error. Here, we find in each approach that uncertain nuclear masses produce dramatic uncertainties in calculated r-process yields, which can be reduced in upcoming experimental campaigns.« less

Calibration of marginal oscillator sensitivity for use in ICR spectrometry

NASA Technical Reports Server (NTRS)

Anicich, V. G.; Huntress, W. T., Jr.

1977-01-01

A constant-reference load is utilized as Q-spoiler in calibrations of relative sensitivity variations of a marginal oscillator with frequency. Frequency-dependent effects troublesome in earlier Q-spoilers are compensated by employing a pure resistive calibration load with compensation for the small distributed capacitance of large resistors. The validity of the approach is demonstrated for a 2:1 mass ratio range, and validity for a mass ratio range greater than 10:1 is claimed. The circuit and technique were developed for use in ion cyclotron resonance (ICR) spectrometric practice.

Female political representation and child health: Evidence from a multilevel analysis.

PubMed

Quamruzzaman, Amm; Lange, Matthew

2016-10-24

This article explores the impact of female political representation in national parliaments on child health through a multilevel analysis. Using available Demographic and Health Surveys, we employ both cross-sectional data for 51 low- and middle-income countries and longitudinal data for 20 countries with multiple surveys. For both the cross-sectional and longitudinal analyses, female representation is negatively related to infant mortality and positively related to measles vaccination status. To explore potential mechanisms, we control for state spending on health and analyze whether the impact of female representation depends on a critical mass of female representatives. The analysis offers evidence that state spending accounts for some of the mediation effect and that the impact of female representation on infant death depends on a critical mass. Copyright © 2016 Elsevier Ltd. All rights reserved.

Atmospheric mercury inputs in montane soils increase with elevation: evidence from mercury isotope signatures.

PubMed

Zhang, Hua; Yin, Run-sheng; Feng, Xin-bin; Sommar, Jonas; Anderson, Christopher W N; Sapkota, Atindra; Fu, Xue-wu; Larssen, Thorjørn

2013-11-25

The influence of topography on the biogeochemical cycle of mercury (Hg) has received relatively little attention. Here, we report the measurement of Hg species and their corresponding isotope composition in soil sampled along an elevational gradient transect on Mt. Leigong in subtropical southwestern China. The data are used to explain orography-related effects on the fate and behaviour of Hg species in montane environments. The total- and methyl-Hg concentrations in topsoil samples show a positive correlation with elevation. However, a negative elevation dependence was observed in the mass-dependent fractionation (MDF) and mass-independent fractionation (MIF) signatures of Hg isotopes. Both a MIF (Δ(199)Hg) binary mixing approach and the traditional inert element method indicate that the content of Hg derived from the atmosphere distinctly increases with altitude.

Temperature dependence of the isotope chemistry of the heavy elements.

PubMed Central

Bigeleisen, J

1996-01-01

The temperature coefficient of equilibrium isotope fractionation in the heavy elements is shown to be larger at high temperatures than that expected from the well-studied vibrational isotope effects. The difference in the isotopic behavior of the heavy elements as compared with the light elements is due to the large nuclear isotope field shifts in the heavy elements. The field shifts introduce new mechanisms for maxima, minima, crossovers, and large mass-independent isotope effects in the isotope chemistry of the heavy elements. The generalizations are illustrated by the temperature dependence of the isotopic fractionation in the redox reaction between U(VI) and U(IV) ions. PMID:8790340

Mass enhances speed but diminishes turn capacity in terrestrial pursuit predators

PubMed Central

Wilson, Rory P; Griffiths, Iwan W; Mills, Michael GL; Carbone, Chris; Wilson, John W; Scantlebury, David M

2015-01-01

The dynamics of predator-prey pursuit appears complex, making the development of a framework explaining predator and prey strategies problematic. We develop a model for terrestrial, cursorial predators to examine how animal mass modulates predator and prey trajectories and affects best strategies for both parties. We incorporated the maximum speed-mass relationship with an explanation of why larger animals should have greater turn radii; the forces needed to turn scale linearly with mass whereas the maximum forces an animal can exert scale to a 2/3 power law. This clarifies why in a meta-analysis, we found a preponderance of predator/prey mass ratios that minimized the turn radii of predators compared to their prey. It also explained why acceleration data from wild cheetahs pursuing different prey showed different cornering behaviour with prey type. The outcome of predator prey pursuits thus depends critically on mass effects and the ability of animals to time turns precisely. DOI: http://dx.doi.org/10.7554/eLife.06487.001 PMID:26252515

Preconceptions of Japanese Students Surveyed Using the Force and Motion Conceptual Evaluation

NASA Astrophysics Data System (ADS)

Ishimoto, Michi

2010-07-01

We assess the preconceptions of Japanese students about force and motion. The Force and Motion Conceptual Evaluation is a research-based, multiple-choice assessment of students' conceptual understanding of Newton's laws of motion and energy conservation. It is administered to determine the effectiveness of introductory mechanics curricula. In this study, the test was given to engineering students at the beginning of the first lecture of an introductory mechanics course for several years. Some students had minimal high school physics education, whereas the others had completed high school physics programs. To probe the students' preconceptions, we studied their test answers for each of the following categories: velocity, acceleration, Newton's first and second laws, Newton's third law, and energy conservation. We find that preconceptions, such as F ∝ mv, are prevalent among the students, regardless of their level of high school physics education. In the case of a collision between two objects, two preconceptions—a mass-dependent model and an action-dependent model—are prevalent. Typically, students combine the two models, with action dependency outweighing mass dependency. In the case of a sled sliding down a hill without friction at two heights and inclinations, a quarter of students used the height-dependent model to answer questions regarding speed and kinetic energy.

Physical Activity and Health Perception in Aging: Do Body Mass and Satisfaction Matter? A Three-Path Mediated Link

PubMed Central

Capranica, Laura; Stager, Joel; Forte, Roberta; Falbo, Simone; Di Baldassarre, Angela; Segura-Garcia, Cristina; Pesce, Caterina

2016-01-01

Although ageing people could benefit from healthy diet and physical activity to maintain health and quality of life, further understandings of the diet- and physical activity-related mechanisms that may cause changes in health and quality of life perception are necessary. The purpose of the study was to investigate the effect of eating attitudes, body mass and image satisfaction, and exercise dependence in the relationship between physical activity and health and quality of life perception in older individuals. Hundred and seventy-nine late middle-aged, (55–64 yrs), young-old (65–74 yrs), and old (75–84 yrs) senior athletes (n = 56), physically active (n = 58) or sedentary adults (n = 65) were submitted to anthropometric evaluations (body mass, height) and self-reported questionnaires: Body Image Dimensional Assessment, Exercise Dependence Scale, Eating Attitude Test, and Short Form Health Survey (Physical Component Summary [PCS] and Mental Component Summary [MCS] of and health and quality of life perception). Senior athletes, physically active, and sedentary participants subgroups differed (P<0.05) from each other in body mass index (BMI) and several components of body image and exercise dependence. Senior athletes showed, compared to their sedentary counterparts, further differences (P<0.05) in eating attitudes and in both PCS and MCS. Mediation analysis showed that the relationship between physical activity habit and MCS, but not PCS, was indirectly explained by a serial mediation chain composed of objective BMI and subjective body image (dis)satisfaction. Findings confirm the relevant role of physically active life habits for older individuals to perceive good physical and mental health. The novelty of the three-path mediated link between physical activity level and mental health perception suggests that the beneficial effect of a physically active lifestyle on weight control can positively impinge on the cognitive-emotional dimension of mental health by ensuring the maintenance, also at older age, of a satisfactory body image. PMID:27611689

Reactive solute transport in an asymmetric aquifer-aquitard system with scale-dependent dispersion

NASA Astrophysics Data System (ADS)

Zhou, R.; Zhan, H.

2017-12-01

Abstract: The understanding of reactive solute transport in an aquifer-aquitard system is important to study transport behavior in the more complex porous media. When transport properties are asymmetric in the upper and lower aquitards, reactive solute transport in such an aquifer-aquitard system becomes a coupled three domain problem that is more complex than the symmetric case in which the upper and lower aquitards have identical transport properties. Meanwhile, the dispersivity of transport in the aquifer is considered as a linear or exponential function of travel distance due to the heterogeneity of aquifer. This study proposed new transport models to describe reactive solute transport in such an asymmetric aquifer-aquitard system with scale-dependent dispersion. Mathematical models were developed for such problems under the first-type and third-type boundary conditions to analyze the spatial-temporal concentration and mass distribution in the aquifer and aquitards with the help of Laplace transform technique and the de Hoog numerical Laplace inversion method. Breakthrough curves (BTCs) and residence time distribution curves (RTDs) obtained from the models with scale-dependent dispersion, constant dispersion and constant effective dispersivity were compared to reflect the lumped scale-dispersion effect in the aquifer-aquitard system. The newly acquired solutions were then tested extensively against previous analytical and numerical solutions and were proven to be robust and accurate. Furthermore, to study the back diffusion of contaminant mass in aquitards, a zero-contaminant mass concentration boundary condition was imposed on the inlet boundary of the system after a certain time, which is also called the process of water flushing. The diffusion loss alone the aquifer/aquitard interfaces and mass stored ratio change in each of three domains (upper aquitard, aquifer, and lower aquitard) after water flushing provided an insightful and comprehensive analysis of transport behavior with asymmetric distribution of transport properties.

Evolution of wavelength-dependent mass absorption cross sections of carbonaceous aerosols during the 2010 DOE CARES campaign

NASA Astrophysics Data System (ADS)

Flowers, B. A.; Dubey, M. K.; Subramanian, R.; Sedlacek, A. J.; Kelley, P.; Luke, W. T.; Jobson, B. T.; Zaveri, R. A.

2011-12-01

Predictions of aerosol radiative forcing require process level optical property models that are built on precise and accurate field observations. Evolution of aerosol optical properties for urban influenced carbonaceous aerosol undergoing transport and mixing with rural air masses was a focal point of the DOE Carbonaceous Aerosol and Radiative Effects (CARES) campaign near Sacramento, CA in summer 2010. Urban aerosol was transported from Sacramento, CA (T0) to the foothills of the Sierra Nevada Mountains to a rural site located near Cool, CA (T1). Aerosol absorption and scattering coefficients were measured at the T0 and T1 sites using integrated photoacoustic acoustic/nephelometer instruments (PASS-3 and PASS-UV) at 781, 532, 405, and 375 nm. Single particle soot photometry (SP2) instrumentation was used to monitor black carbon (BC) mass at both sites. Combining data from these sensors allows estimate of the wavelength-dependent mass absorption coefficient (MAC(λ)) and partitioning of MAC(λ) into contributions from the BC core and from enhancements from coating of BC cores. MAC(λ) measured in this way is free of artifacts associated with filter-based aerosol absorption measurements and takes advantage of the single particle sensitivity of the SP2 instrument, allowing observation of MAC(λ) on 10 minute and faster time scales. Coating was observed to enhance MAC(λ) by 20 - 30 % and different wavelength dependence for MAC(λ) was observed for urban and biomass burning aerosol. Further, T0 - T1 evolution of MAC(λ) was correlated with separately measured NO/NOy ratios and CO/CO2 ratios to understand the effects of aging & transport on MAC(λ) and the implications of aerosol processing that links air quality to radiative forcing on a regional scale. Aircraft observations made from the Gulfstream-1 during CARES are also analyzed to enhance process level understanding of the optical properties of fresh and aged carbonaceous aerosol in the urban-rural interface.

The connection between mass, environment, and slow rotation in simulated galaxies

NASA Astrophysics Data System (ADS)

Lagos, Claudia del P.; Schaye, Joop; Bahé, Yannick; Van de Sande, Jesse; Kay, Scott T.; Barnes, David; Davis, Timothy A.; Dalla Vecchia, Claudio

2018-06-01

Recent observations from integral field spectroscopy (IFS) indicate that the fraction of galaxies that are slow rotators (SRs), FSR, depends primarily on stellar mass, with no significant dependence on environment. We investigate these trends and the formation paths of SRs using the EAGLE and HYDRANGEA hydrodynamical simulations. EAGLE consists of several cosmological boxes of volumes up to (100 Mpc)^3, while HYDRANGEA consists of 24 cosmological simulations of galaxy clusters and their environment. Together they provide a statistically significant sample in the stellar mass range 10^{9.5}-10^{12.3} M_{⊙}, of 16 358 galaxies. We construct IFS-like cubes and measure stellar spin parameters, λR, and ellipticities, allowing us to classify galaxies into slow/fast rotators as in observations. The simulations display a primary dependence of FSR on stellar mass, with a weak dependence on environment. At fixed stellar mass, satellite galaxies are more likely to be SRs than centrals. FSR shows a dependence on halo mass at fixed stellar mass for central galaxies, while no such trend is seen for satellites. We find that ≈70 per cent of SRs at z = 0 have experienced at least one merger with mass ratio ≥0.1, with dry mergers being at least twice more common than wet mergers. Individual dry mergers tend to decrease λR, while wet mergers mostly increase it. However, 30 per cent of SRs at z = 0 have not experienced mergers, and those inhabit haloes with median spins twice smaller than the haloes hosting the rest of the SRs. Thus, although the formation paths of SRs can be varied, dry mergers and/or haloes with small spins dominate.

Effects of winglet on transonic flutter characteristics of a cantilevered twin-engine-transport wing model

NASA Technical Reports Server (NTRS)

Ruhlin, C. L.; Bhatia, K. G.; Nagaraja, K. S.

1986-01-01

A transonic model and a low-speed model were flutter tested in the Langley Transonic Dynamics Tunnel at Mach numbers up to 0.90. Transonic flutter boundaries were measured for 10 different model configurations, which included variations in wing fuel, nacelle pylon stiffness, and wingtip configuration. The winglet effects were evaluated by testing the transonic model, having a specific wing fuel and nacelle pylon stiffness, with each of three wingtips, a nonimal tip, a winglet, and a nominal tip ballasted to simulate the winglet mass. The addition of the winglet substantially reduced the flutter speed of the wing at transonic Mach numbers. The winglet effect was configuration-dependent and was primarily due to winglet aerodynamics rather than mass. Flutter analyses using modified strip-theory aerodynamics (experimentally weighted) correlated reasonably well with test results. The four transonic flutter mechanisms predicted by analysis were obtained experimentally. The analysis satisfactorily predicted the mass-density-ratio effects on subsonic flutter obtained using the low-speed model. Additional analyses were made to determine the flutter sensitivity to several parameters at transonic speeds.

Dynamical friction in the primordial neutrino sea

NASA Astrophysics Data System (ADS)

Okoli, Chiamaka; Scrimgeour, Morag I.; Afshordi, Niayesh; Hudson, Michael J.

2017-06-01

Standard big bang cosmology predicts a cosmic neutrino background at Tν ≃ 1.95 K. Given the current neutrino oscillation measurements, we know most neutrinos move at large, but non-relativistic, velocities. Therefore, dark matter haloes moving in the sea of primordial neutrinos form a neutrino wake behind them, which would slow them down, due to the effect of dynamical friction. In this paper, we quantify this effect for realistic haloes, in the context of the halo model of structure formation, and show that it scales as m_ν ^4× relative velocity and monotonically grows with the halo mass. Galaxy redshift surveys can be sensitive to this effect (at >3σ confidence level, depending on survey properties, neutrino mass and hierarchy) through redshift space distortions of distinct galaxy populations.

Infrared broadband metasurface absorber for reducing the thermal mass of a microbolometer.

PubMed

Jung, Joo-Yun; Song, Kyungjun; Choi, Jun-Hyuk; Lee, Jihye; Choi, Dae-Geun; Jeong, Jun-Ho; Neikirk, Dean P

2017-03-27

We demonstrate an infrared broadband metasurface absorber that is suitable for increasing the response speed of a microbolometer by reducing its thermal mass. A large fraction of holes are made in a periodic pattern on a thin lossy metal layer characterised with a non-dispersive effective surface impedance. This can be used as a non-resonant metasurface that can be integrated with a Salisbury screen absorber to construct an absorbing membrane for a microbolometer that can significantly reduce the thermal mass while maintaining high infrared broadband absorption in the long wavelength infrared (LWIR) band. The non-dispersive effective surface impedance can be matched to the free space by optimising the surface resistance of the thin lossy metal layer depending on the size of the patterned holes by using a dc approximation method. In experiments a high broadband absorption was maintained even when the fill factor of the absorbing area was reduced to 28% (hole area: 72%), and it was theoretically maintained even when the fill factor of the absorbing area was reduced to 19% (hole area: 81%). Therefore, a metasurface with a non-dispersive effective surface impedance is a promising solution for reducing the thermal mass of infrared microbolometer pixels.

Meson properties at finite temperature in a three flavor nonlocal chiral quark model with Polyakov loop

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

Contrera, G. A.; CONICET, Rivadavia 1917, 1033 Buenos Aires; Dumm, D. Gomez

2010-03-01

We study the finite temperature behavior of light scalar and pseudoscalar meson properties in the context of a three-flavor nonlocal chiral quark model. The model includes mixing with active strangeness degrees of freedom, and takes care of the effect of gauge interactions by coupling the quarks with the Polyakov loop. We analyze the chiral restoration and deconfinement transitions, as well as the temperature dependence of meson masses, mixing angles and decay constants. The critical temperature is found to be T{sub c{approx_equal}}202 MeV, in better agreement with lattice results than the value recently obtained in the local SU(3) PNJL model. Itmore » is seen that above T{sub c} pseudoscalar meson masses get increased, becoming degenerate with the masses of their chiral partners. The temperatures at which this matching occurs depend on the strange quark composition of the corresponding mesons. The topological susceptibility shows a sharp decrease after the chiral transition, signalling the vanishing of the U(1){sub A} anomaly for large temperatures.« less

Optimal Concentrations in Transport Networks

NASA Astrophysics Data System (ADS)

Jensen, Kaare; Savage, Jessica; Kim, Wonjung; Bush, John; Holbrook, N. Michele

2013-03-01

Biological and man-made systems rely on effective transport networks for distribution of material and energy. Mass flow in these networks is determined by the flow rate and the concentration of material. While the most concentrated solution offers the greatest potential for mass flow, impedance grows with concentration and thus makes it the most difficult to transport. The concentration at which mass flow is optimal depends on specific physical and physiological properties of the system. We derive a simple model which is able to predict optimal concentrations observed in blood flows, sugar transport in plants, and nectar feeding animals. Our model predicts that the viscosity at the optimal concentration μopt =2nμ0 is an integer power of two times the viscosity of the pure carrier medium μ0. We show how the observed powers 1 <= n <= 6 agree well with theory and discuss how n depends on biological constraints imposed on the transport process. The model provides a universal framework for studying flows impeded by concentration and provides hints of how to optimize engineered flow systems, such as congestion in traffic flows.

Matrix effects in pesticide multi-residue analysis by liquid chromatography-mass spectrometry.

PubMed

Kruve, Anneli; Künnapas, Allan; Herodes, Koit; Leito, Ivo

2008-04-11

Three sample preparation methods: Luke method (AOAC 985.22), QuEChERS (quick, easy, cheap, effective, rugged and safe) and matrix solid-phase dispersion (MSPD) were applied to different fruits and vegetables for analysis of 14 pesticide residues by high-performance liquid chromatography with electrospray ionization-mass spectrometry (HPLC/ESI/MS). Matrix effect, recovery and process efficiency of the sample preparation methods applied to different fruits and vegetables were compared. The Luke method was found to produce least matrix effect. On an average the best recoveries were obtained with the QuEChERS method. MSPD gave unsatisfactory recoveries for some basic pesticide residues. Comparison of matrix effects for different apple varieties showed high variability for some residues. It was demonstrated that the amount of co-extracting compounds that cause ionization suppression of aldicarb depends on the apple variety as well as on the sample preparation method employed.

Effects of long term supplementation of anabolic androgen steroids on human skeletal muscle.

PubMed

Yu, Ji-Guo; Bonnerud, Patrik; Eriksson, Anders; Stål, Per S; Tegner, Yelverton; Malm, Christer

2014-01-01

The effects of long-term (over several years) anabolic androgen steroids (AAS) administration on human skeletal muscle are still unclear. In this study, seventeen strength training athletes were recruited and individually interviewed regarding self-administration of banned substances. Ten subjects admitted having taken AAS or AAS derivatives for the past 5 to 15 years (Doped) and the dosage and type of banned substances were recorded. The remaining seven subjects testified to having never used any banned substances (Clean). For all subjects, maximal muscle strength and body composition were tested, and biopsies from the vastus lateralis muscle were obtained. Using histochemistry and immunohistochemistry (IHC), muscle biopsies were evaluated for morphology including fiber type composition, fiber size, capillary variables and myonuclei. Compared with the Clean athletes, the Doped athletes had significantly higher lean leg mass, capillary per fibre and myonuclei per fiber. In contrast, the Doped athletes had significantly lower absolute value in maximal squat force and relative values in maximal squat force (relative to lean body mass, to lean leg mass and to muscle fiber area). Using multivariate statistics, an orthogonal projection of latent structure discriminant analysis (OPLS-DA) model was established, in which the maximal squat force relative to muscle mass and the maximal squat force relative to fiber area, together with capillary density and nuclei density were the most important variables for separating Doped from the Clean athletes (regression  =  0.93 and prediction  =  0.92, p<0.0001). In Doped athletes, AAS dose-dependent increases were observed in lean body mass, muscle fiber area, capillary density and myonuclei density. In conclusion, long term AAS supplementation led to increases in lean leg mass, muscle fiber size and a parallel improvement in muscle strength, and all were dose-dependent. Administration of AAS may induce sustained morphological changes in human skeletal muscle, leading to physical performance enhancement.

Effects of Long Term Supplementation of Anabolic Androgen Steroids on Human Skeletal Muscle

PubMed Central

Yu, Ji-Guo; Bonnerud, Patrik; Eriksson, Anders; Stål, Per S.; Tegner, Yelverton; Malm, Christer

2014-01-01

The effects of long-term (over several years) anabolic androgen steroids (AAS) administration on human skeletal muscle are still unclear. In this study, seventeen strength training athletes were recruited and individually interviewed regarding self-administration of banned substances. Ten subjects admitted having taken AAS or AAS derivatives for the past 5 to 15 years (Doped) and the dosage and type of banned substances were recorded. The remaining seven subjects testified to having never used any banned substances (Clean). For all subjects, maximal muscle strength and body composition were tested, and biopsies from the vastus lateralis muscle were obtained. Using histochemistry and immunohistochemistry (IHC), muscle biopsies were evaluated for morphology including fiber type composition, fiber size, capillary variables and myonuclei. Compared with the Clean athletes, the Doped athletes had significantly higher lean leg mass, capillary per fibre and myonuclei per fiber. In contrast, the Doped athletes had significantly lower absolute value in maximal squat force and relative values in maximal squat force (relative to lean body mass, to lean leg mass and to muscle fiber area). Using multivariate statistics, an orthogonal projection of latent structure discriminant analysis (OPLS-DA) model was established, in which the maximal squat force relative to muscle mass and the maximal squat force relative to fiber area, together with capillary density and nuclei density were the most important variables for separating Doped from the Clean athletes (regression  =  0.93 and prediction  =  0.92, p<0.0001). In Doped athletes, AAS dose-dependent increases were observed in lean body mass, muscle fiber area, capillary density and myonuclei density. In conclusion, long term AAS supplementation led to increases in lean leg mass, muscle fiber size and a parallel improvement in muscle strength, and all were dose-dependent. Administration of AAS may induce sustained morphological changes in human skeletal muscle, leading to physical performance enhancement. PMID:25207812

Non-linear mixing effects on mass-47 CO2 clumped isotope thermometry: Patterns and implications.

PubMed

Defliese, William F; Lohmann, Kyger C

2015-05-15

Mass-47 CO(2) clumped isotope thermometry requires relatively large (~20 mg) samples of carbonate minerals due to detection limits and shot noise in gas source isotope ratio mass spectrometry (IRMS). However, it is unreasonable to assume that natural geologic materials are homogenous on the scale required for sampling. We show that sample heterogeneities can cause offsets from equilibrium Δ(47) values that are controlled solely by end member mixing and are independent of equilibrium temperatures. A numerical model was built to simulate and quantify the effects of end member mixing on Δ(47). The model was run in multiple possible configurations to produce a dataset of mixing effects. We verified that the model accurately simulated real phenomena by comparing two artificial laboratory mixtures measured using IRMS to model output. Mixing effects were found to be dependent on end member isotopic composition in δ(13)C and δ(18)O values, and independent of end member Δ(47) values. Both positive and negative offsets from equilibrium Δ(47) can occur, and the sign is dependent on the interaction between end member isotopic compositions. The overall magnitude of mixing offsets is controlled by the amount of variability within a sample; the larger the disparity between end member compositions, the larger the mixing offset. Samples varying by less than 2 ‰ in both δ(13)C and δ(18)O values have mixing offsets below current IRMS detection limits. We recommend the use of isotopic subsampling for δ(13)C and δ(18)O values to determine sample heterogeneity, and to evaluate any potential mixing effects in samples suspected of being heterogonous. Copyright © 2015 John Wiley & Sons, Ltd.

Context-dependent effects of background colour in free recall with spatially grouped words.

PubMed

Sakai, Tetsuya; Isarida, Toshiko K; Isarida, Takeo

2010-10-01

Three experiments investigated context-dependent effects of background colour in free recall with groups of items. Undergraduates (N=113) intentionally studied 24 words presented in blocks of 6 on a computer screen with two different background colours. The two background colours were changed screen-by-screen randomly (random condition) or alternately (alternation condition) during the study period. A 30-second filled retention interval was imposed before an oral free-recall test. A signal for free recall was presented throughout the test on one of the colour background screens presented at study. Recalled words were classified as same- or different-context words according to whether the background colours at study and test were the same or different. The random condition produced significant context-dependent effects, whereas the alternation condition showed no context-dependent effects, regardless of whether the words were presented once or twice. Furthermore, the words presented on the same screen were clustered in recall, whereas the words presented against the same background colour but on different screens were not clustered. The present results imply: (1) background colours can cue spatially massed words; (2) background colours act as temporally local context; and (3) predictability of the next background colour modulates the context-dependent effect.

Novel approach identifies SNPs in SLC2A10 and KCNK9 with evidence for parent-of-origin effect on body mass index.

PubMed

Hoggart, Clive J; Venturini, Giulia; Mangino, Massimo; Gomez, Felicia; Ascari, Giulia; Zhao, Jing Hua; Teumer, Alexander; Winkler, Thomas W; Tšernikova, Natalia; Luan, Jian'an; Mihailov, Evelin; Ehret, Georg B; Zhang, Weihua; Lamparter, David; Esko, Tõnu; Macé, Aurelien; Rüeger, Sina; Bochud, Pierre-Yves; Barcella, Matteo; Dauvilliers, Yves; Benyamin, Beben; Evans, David M; Hayward, Caroline; Lopez, Mary F; Franke, Lude; Russo, Alessia; Heid, Iris M; Salvi, Erika; Vendantam, Sailaja; Arking, Dan E; Boerwinkle, Eric; Chambers, John C; Fiorito, Giovanni; Grallert, Harald; Guarrera, Simonetta; Homuth, Georg; Huffman, Jennifer E; Porteous, David; Moradpour, Darius; Iranzo, Alex; Hebebrand, Johannes; Kemp, John P; Lammers, Gert J; Aubert, Vincent; Heim, Markus H; Martin, Nicholas G; Montgomery, Grant W; Peraita-Adrados, Rosa; Santamaria, Joan; Negro, Francesco; Schmidt, Carsten O; Scott, Robert A; Spector, Tim D; Strauch, Konstantin; Völzke, Henry; Wareham, Nicholas J; Yuan, Wei; Bell, Jordana T; Chakravarti, Aravinda; Kooner, Jaspal S; Peters, Annette; Matullo, Giuseppe; Wallaschofski, Henri; Whitfield, John B; Paccaud, Fred; Vollenweider, Peter; Bergmann, Sven; Beckmann, Jacques S; Tafti, Mehdi; Hastie, Nicholas D; Cusi, Daniele; Bochud, Murielle; Frayling, Timothy M; Metspalu, Andres; Jarvelin, Marjo-Riitta; Scherag, André; Smith, George Davey; Borecki, Ingrid B; Rousson, Valentin; Hirschhorn, Joel N; Rivolta, Carlo; Loos, Ruth J F; Kutalik, Zoltán

2014-07-01

The phenotypic effect of some single nucleotide polymorphisms (SNPs) depends on their parental origin. We present a novel approach to detect parent-of-origin effects (POEs) in genome-wide genotype data of unrelated individuals. The method exploits increased phenotypic variance in the heterozygous genotype group relative to the homozygous groups. We applied the method to >56,000 unrelated individuals to search for POEs influencing body mass index (BMI). Six lead SNPs were carried forward for replication in five family-based studies (of ∼4,000 trios). Two SNPs replicated: the paternal rs2471083-C allele (located near the imprinted KCNK9 gene) and the paternal rs3091869-T allele (located near the SLC2A10 gene) increased BMI equally (beta = 0.11 (SD), P<0.0027) compared to the respective maternal alleles. Real-time PCR experiments of lymphoblastoid cell lines from the CEPH families showed that expression of both genes was dependent on parental origin of the SNPs alleles (P<0.01). Our scheme opens new opportunities to exploit GWAS data of unrelated individuals to identify POEs and demonstrates that they play an important role in adult obesity.

Novel Approach Identifies SNPs in SLC2A10 and KCNK9 with Evidence for Parent-of-Origin Effect on Body Mass Index

PubMed Central

Hoggart, Clive J.; Venturini, Giulia; Mangino, Massimo; Gomez, Felicia; Ascari, Giulia; Zhao, Jing Hua; Teumer, Alexander; Winkler, Thomas W.; Tšernikova, Natalia; Luan, Jian'an; Mihailov, Evelin; Ehret, Georg B.; Zhang, Weihua; Lamparter, David; Esko, Tõnu; Macé, Aurelien; Rüeger, Sina; Bochud, Pierre-Yves; Barcella, Matteo; Dauvilliers, Yves; Benyamin, Beben; Evans, David M.; Hayward, Caroline; Lopez, Mary F.; Franke, Lude; Russo, Alessia; Heid, Iris M.; Salvi, Erika; Vendantam, Sailaja; Arking, Dan E.; Boerwinkle, Eric; Chambers, John C.; Fiorito, Giovanni; Grallert, Harald; Guarrera, Simonetta; Homuth, Georg; Huffman, Jennifer E.; Porteous, David; Moradpour, Darius; Iranzo, Alex; Hebebrand, Johannes; Kemp, John P.; Lammers, Gert J.; Aubert, Vincent; Heim, Markus H.; Martin, Nicholas G.; Montgomery, Grant W.; Peraita-Adrados, Rosa; Santamaria, Joan; Negro, Francesco; Schmidt, Carsten O.; Scott, Robert A.; Spector, Tim D.; Strauch, Konstantin; Völzke, Henry; Wareham, Nicholas J.; Yuan, Wei; Bell, Jordana T.; Chakravarti, Aravinda; Kooner, Jaspal S.; Peters, Annette; Matullo, Giuseppe; Wallaschofski, Henri; Whitfield, John B.; Paccaud, Fred; Vollenweider, Peter; Bergmann, Sven; Beckmann, Jacques S.; Tafti, Mehdi; Hastie, Nicholas D.; Cusi, Daniele; Bochud, Murielle; Frayling, Timothy M.; Metspalu, Andres; Jarvelin, Marjo-Riitta; Scherag, André; Smith, George Davey; Borecki, Ingrid B.; Rousson, Valentin; Hirschhorn, Joel N.; Rivolta, Carlo; Loos, Ruth J. F.; Kutalik, Zoltán

2014-01-01

The phenotypic effect of some single nucleotide polymorphisms (SNPs) depends on their parental origin. We present a novel approach to detect parent-of-origin effects (POEs) in genome-wide genotype data of unrelated individuals. The method exploits increased phenotypic variance in the heterozygous genotype group relative to the homozygous groups. We applied the method to >56,000 unrelated individuals to search for POEs influencing body mass index (BMI). Six lead SNPs were carried forward for replication in five family-based studies (of ∼4,000 trios). Two SNPs replicated: the paternal rs2471083-C allele (located near the imprinted KCNK9 gene) and the paternal rs3091869-T allele (located near the SLC2A10 gene) increased BMI equally (beta = 0.11 (SD), P<0.0027) compared to the respective maternal alleles. Real-time PCR experiments of lymphoblastoid cell lines from the CEPH families showed that expression of both genes was dependent on parental origin of the SNPs alleles (P<0.01). Our scheme opens new opportunities to exploit GWAS data of unrelated individuals to identify POEs and demonstrates that they play an important role in adult obesity. PMID:25078964

Dentin biomodification potential depends on polyphenol source.

PubMed

Aguiar, T R; Vidal, C M P; Phansalkar, R S; Todorova, I; Napolitano, J G; McAlpine, J B; Chen, S N; Pauli, G F; Bedran-Russo, A K

2014-04-01

Although proanthocyanidins (PACs) modify dentin, the effectiveness of different PAC sources and the correlation with their specific chemical composition are still unknown. This study describes the chemical profiling of natural PAC-rich extracts from 7 plants using ultra high pressure/performance liquid chromatography (UHPLC) to determine the overall composition of these extracts and, in parallel, comprehensively evaluate their effect on dentin properties. The total polyphenol content of the extracts was determined (as gallic acid equivalents) using Folin-Ciocalteau assays. Dentin biomodification was assessed by the modulus of elasticity, mass change, and resistance to enzymatic biodegradation. Extracts with a high polyphenol and PAC content from Vitis vinifera, Theobroma cacao, Camellia sinensis, and Pinus massoniana induced a significant increase in modulus of elasticity and mass. The UHPLC analysis showed the presence of multiple types of polyphenols, ranging from simple phenolic acids to oligomeric PACs and highly condensed tannins. Protective effect against enzymatic degradation was observed for all experimental groups; however, statistically significant differences were observed between plant extracts. The findings provide clear evidence that the dentin bioactivities of PACs are source dependent, resulting from a combination of concentration and specific chemical constitution of the complex PAC mixtures.

A bias in the "mass-normalized" DTT response - An effect of non-linear concentration-response curves for copper and manganese

NASA Astrophysics Data System (ADS)

Charrier, Jessica G.; McFall, Alexander S.; Vu, Kennedy K.-T.; Baroi, James; Olea, Catalina; Hasson, Alam; Anastasio, Cort

2016-11-01

The dithiothreitol (DTT) assay is widely used to measure the oxidative potential of particulate matter. Results are typically presented in mass-normalized units (e.g., pmols DTT lost per minute per microgram PM) to allow for comparison among samples. Use of this unit assumes that the mass-normalized DTT response is constant and independent of the mass concentration of PM added to the DTT assay. However, based on previous work that identified non-linear DTT responses for copper and manganese, this basic assumption (that the mass-normalized DTT response is independent of the concentration of PM added to the assay) should not be true for samples where Cu and Mn contribute significantly to the DTT signal. To test this we measured the DTT response at multiple PM concentrations for eight ambient particulate samples collected at two locations in California. The results confirm that for samples with significant contributions from Cu and Mn, the mass-normalized DTT response can strongly depend on the concentration of PM added to the assay, varying by up to an order of magnitude for PM concentrations between 2 and 34 μg mL-1. This mass dependence confounds useful interpretation of DTT assay data in samples with significant contributions from Cu and Mn, requiring additional quality control steps to check for this bias. To minimize this problem, we discuss two methods to correct the mass-normalized DTT result and we apply those methods to our samples. We find that it is possible to correct the mass-normalized DTT result, although the correction methods have some drawbacks and add uncertainty to DTT analyses. More broadly, other DTT-active species might also have non-linear concentration-responses in the assay and cause a bias. In addition, the same problem of Cu- and Mn-mediated bias in mass-normalized DTT results might affect other measures of acellular redox activity in PM and needs to be addressed.

Host Star Dependence of Small Planet Mass–Radius Distributions

NASA Astrophysics Data System (ADS)

Neil, Andrew R.; Rogers, Leslie A.

2018-05-01

The planet formation environment around M dwarf stars is different than around G dwarf stars. The longer hot protostellar phase, activity levels and lower protoplanetary disk mass of M dwarfs all may leave imprints on the composition distribution of planets. We use hierarchical Bayesian modeling conditioned on the sample of transiting planets with radial velocity mass measurements to explore small planet mass–radius distributions that depend on host star mass. We find that the current mass–radius data set is consistent with no host star mass dependence. These models are then applied to the Kepler planet radius distribution to calculate the mass distribution of close-orbiting planets and how it varies with host star mass. We find that the average heavy element mass per star at short orbits is higher for M dwarfs compared to FGK dwarfs, in agreement with previous studies. This work will facilitate comparisons between microlensing planet surveys and Kepler, and will provide an analysis framework that can readily be updated as more M dwarf planets are discovered by ongoing and future surveys such as K2 and the Transiting Exoplanet Survey Satellite.

Galaxy and Mass Assembly (GAMA): the star formation rate dependence of the stellar initial mass function

NASA Astrophysics Data System (ADS)

Gunawardhana, M. L. P.; Hopkins, A. M.; Sharp, R. G.; Brough, S.; Taylor, E.; Bland-Hawthorn, J.; Maraston, C.; Tuffs, R. J.; Popescu, C. C.; Wijesinghe, D.; Jones, D. H.; Croom, S.; Sadler, E.; Wilkins, S.; Driver, S. P.; Liske, J.; Norberg, P.; Baldry, I. K.; Bamford, S. P.; Loveday, J.; Peacock, J. A.; Robotham, A. S. G.; Zucker, D. B.; Parker, Q. A.; Conselice, C. J.; Cameron, E.; Frenk, C. S.; Hill, D. T.; Kelvin, L. S.; Kuijken, K.; Madore, B. F.; Nichol, B.; Parkinson, H. R.; Pimbblet, K. A.; Prescott, M.; Sutherland, W. J.; Thomas, D.; van Kampen, E.

2011-08-01

The stellar initial mass function (IMF) describes the distribution in stellar masses produced from a burst of star formation. For more than 50 yr, the implicit assumption underpinning most areas of research involving the IMF has been that it is universal, regardless of time and environment. We measure the high-mass IMF slope for a sample of low-to-moderate redshift galaxies from the Galaxy and Mass Assembly survey. The large range in luminosities and galaxy masses of the sample permits the exploration of underlying IMF dependencies. A strong IMF-star formation rate dependency is discovered, which shows that highly star-forming galaxies form proportionally more massive stars (they have IMFs with flatter power-law slopes) than galaxies with low star formation rates. This has a significant impact on a wide variety of galaxy evolution studies, all of which rely on assumptions about the slope of the IMF. Our result is supported by, and provides an explanation for, the results of numerous recent explorations suggesting a variation of or evolution in the IMF.

Using FLUKA to Calculate Spacecraft: Single Event Environments: A Practical Approach

NASA Technical Reports Server (NTRS)

Koontz, Steve; Boeder, Paul; Reddell, Brandon

2009-01-01

The FLUKA nuclear transport and reaction code can be developed into a practical tool for calculation of spacecraft and planetary surface asset SEE and TID environments. Nuclear reactions and secondary particle shower effects can be estimated with acceptable accuracy both in-flight and in test. More detailed electronic device and/or spacecraft geometries than are reported here are possible using standard FLUKA geometry utilities. Spacecraft structure and shielding mass. Effects of high Z elements in microelectronic structure as reported previously. Median shielding mass in a generic slab or concentric sphere target geometry are at least approximately applicable to more complex spacecraft shapes. Need the spacecraft shielding mass distribution function applicable to the microelectronic system of interest. SEE environment effects can be calculated for a wide range of spacecraft and microelectronic materials with complete nuclear physics. Evaluate benefits of low Z shielding mass can be evaluated relative to aluminum. Evaluate effects of high Z elements as constituents of microelectronic devices. The principal limitation on the accuracy of the FLUKA based method reported here are found in the limited accuracy and incomplete character of affordable heavy ion test data. To support accurate rate estimates with any calculation method, the aspect ratio of the sensitive volume(s) and the dependence must be better characterized.

C P -odd sector and θ dynamics in holographic QCD

NASA Astrophysics Data System (ADS)

Areán, Daniel; Iatrakis, Ioannis; Järvinen, Matti; Kiritsis, Elias

2017-07-01

The holographic model of V-QCD is used to analyze the physics of QCD in the Veneziano large-N limit. An unprecedented analysis of the C P -odd physics is performed going beyond the level of effective field theories. The structure of holographic saddle points at finite θ is determined, as well as its interplay with chiral symmetry breaking. Many observables (vacuum energy and higher-order susceptibilities, singlet and nonsinglet masses and mixings) are computed as functions of θ and the quark mass m . Wherever applicable the results are compared to those of chiral Lagrangians, finding agreement. In particular, we recover the Witten-Veneziano formula in the small x →0 limit, we compute the θ dependence of the pion mass, and we derive the hyperscaling relation for the topological susceptibility in the conformal window in terms of the quark mass.

Investigation of Ion Transmission Effects on Intact Protein Quantification in a Triple Quadrupole Mass Spectrometer

NASA Astrophysics Data System (ADS)

Wang, Evelyn H.; Appulage, Dananjaya Kalu; McAllister, Erin A.; Schug, Kevin A.

2017-09-01

Recently, direct intact protein quantitation using triple quadrupole mass spectrometry (QqQ-MS) and multiple reaction monitoring (MRM) was demonstrated (J. Am. Soc. Mass Spectrom. 27, 886-896 (2016)). Even though QqQ-MS is known to provide extraordinary detection sensitivity for quantitative analysis, we found that intact proteins exhibited a less than 5% ion transmission from the first quadrupole to the third quadrupole mass analyzer in the presence of zero collision energy (ZCE). With the goal to enhance intact protein quantitation sensitivity, ion scattering effects, proton transfer effects, and mass filter resolution widths were examined for their contributions to the lost signal. Protein standards myoglobin and ubiquitin along with small molecules reserpine and vancomycin were analyzed together with various collision induced dissociation (CID) gases (N2, He, and Ar) at different gas pressures. Mass resolution settings played a significant role in reducing ion transmission signal. By narrowing the mass resolution window by 0.35 m/z on each side, roughly 75%-90% of the ion signal was lost. The multiply charged proteins experienced additional proton transfer effects, corresponding to 10-fold signal reduction. A study of increased sensitivity of the method was also conducted with various MRM summation techniques. Although the degree of enhancement was analyte-dependent, an up to 17-fold increase in sensitivity was observed for ubiquitin using a summation of multiple MRM transitions. Biological matrix, human urine, and equine plasma were spiked with proteins to demonstrate the specificity of the method. This study provides additional insight into optimizing the use and sensitivity of QqQ-MS for intact protein quantification. [Figure not available: see fulltext.

Population dynamics of brown trout (Salmo trutta) in Spruce Creek Pennsylvania: A quarter-century perspective

USGS Publications Warehouse

Grossman, Gary D.; Carline, Robert F.; Wagner, Tyler

2017-01-01

We examined the relationship between density-independent and density-dependent factors on the demography of a dense, relatively unexploited population of brown trout in Spruce Creek Pennsylvania between 1985 and 2011.Individual PCAs of flow and temperature data elucidated groups of years with multiple high flow versus multiple low flow characteristics and high versus low temperature years, although subtler patterns of variation also were observed.Density and biomass displayed similar temporal patterns, ranging from 710 to 1,803 trout/ha and 76–263 kg/ha. We detected a significantly negative linear stock-recruitment relationship (R2 = .39) and there was no evidence that flow or water temperature affected recruitment.Both annual survival and the per-capita rate of increase (r) for the population varied over the study, and density-dependent mechanisms possessed the greatest explanatory power for annual survival data. Temporal trends in population r suggested it displayed a bounded equilibrium with increases observed in 12 years and decreases detected in 13 years.Model selection analysis of per-capita rate of increase data for age 1, and adults (N = eight interpretable models) indicated that both density-dependent (five of eight) and negative density-independent processes (five of eight, i.e. high flows or temperatures), affected r. Recruitment limitation also was identified in three of eight models. Variation in the per-capita rate of increase for the population was most strongly affected by positive density independence in the form of increasing spring–summer temperatures and recruitment limitation.Model selection analyses describing annual variation in both mean length and mass data yielded similar results, although maximum wi values were low ranging from 0.09 to 0.23 (length) and 0.13 to 0.22 (mass). Density-dependence was included in 15 of 15 interpretable models for length and all ten interpretable models for mass. Similarly, positive density-independent effects in the form of increasing autumn–winter flow were present in seven of 15 interpretable models for length and five of ten interpretable models for mass. Negative density independent effects also were observed in the form of high spring–summer flows or temperatures (N = 4), or high autumn–winter temperatures (N = 1).Our analyses of the factors affecting population regulation in an introduced population of brown trout demonstrate that density-dependent forces affected every important demographic characteristic (recruitment, survivorship, the rate of increase, and size) within this population. However, density-independent forces in the form of seasonal variations in flow and temperature also helped explain annual variation in the per-capita rate of increase, and mean length and mass data. Consequently, population regulation within this population is driven by a complex of biotic and environmental factors, although it seems clear that density-dependent factors play a dominant role.

Incubation temperature influences trade-off between structural size and energy reserves in mallard hatchlings.

PubMed

Koláčková, Martina; Prokůpková, Ludmila; Albrecht, Tomáš; Hořák, David

2015-01-01

The reproductive success of precocial birds depends on investments in clutch formation and incubation. Egg quality strongly affects the phenotypic traits correlated with survival of the hatchling, but parental ability to maintain incubation temperature can also influence hatchling outcomes. The effect of incubation temperature on hatchling phenotype has been widely studied in reptiles but not in birds. The aim of this study was to explore the effects of egg mass and incubation temperature on the incubation period, hatchability, and hatchling phenotype of the mallard (Anas platyrhynchos). Mallard eggs were incubated under six constant incubation temperatures (ranging from 35.0° to 39.0°C). Hatchlings were weighed, and their structural size was measured. Some hatchlings were used for an examination of residual yolk sac mass and basic chemical composition of the yolk-free body. All investigated phenotypic traits except for chemical composition were positively correlated with egg mass. Incubation temperature did not affect hatchling body mass, but increased temperatures led to a decreased yolk-free body mass and structural size of hatchlings and to increased yolk sac mass. Our results suggest that there is a trade-off between the yolk-free body size and energetic reserves in the form of the yolk sac and that this trade-off is modulated by incubation temperature.

Limits to the radiative decay of the axion

NASA Technical Reports Server (NTRS)

Ressell, M. Ted

1991-01-01

An axion with a mass greater than 1 eV should be detectable through its decay into two photons. The astrophysical and cosmological limits which define a small window of allowed axion mass above 3 eV are discussed. A firm upper bound to the axion's mass of M(sub a) less than or equal to 8 eV is derived by considering the effect of decaying axions upon the diffuse extragalactic background radiation and the brightness of the night sky due to axions in the halo of the Milky Way galaxy. The intergalactic light of clusters of galaxies is shown to be an ideal place to search for an emission line arising from the radiative decay of axions. An unsuccessful search for this emission line in three clusters of galaxies is then detailed. Limits to the presence of any intracluster line emission are derived with the result that axions with masses between 3 and 8 eV are excluded by the data, effectively closing this window of axion mass, unless a severe cancellation of axionic decay amplitudes occurs. The intracluster flux limits are then used to constrain the amplitude of any such model dependence.

Orbital order and effective mass enhancement in t2 g two-dimensional electron gases

NASA Astrophysics Data System (ADS)

Tolsma, John; Principi, Alessandro; Polini, Marco; MacDonald, Allan

2015-03-01

It is now possible to prepare d-electron two-dimensional electron gas systems that are confined near oxide heterojunctions and contain t2 g electrons with a density much smaller than one electron per metal atom. I will discuss a generic model that captures all qualitative features of electron-electron interaction physics in t2 g two-dimensional electron gas systems, and the use of a GW approximation to explore t2 g quasiparticle properties in this new context. t2 g electron gases contain a high density isotropic light mass xy component and low-density xz and yz anisotropic components with light and heavy masses in orthogonal directions. The high density light mass band screens interactions within the heavy bands. As a result the wave vector dependence of the self-energy is reduced and the effective mass is increased. When the density in the heavy bands is low, the difference in anisotropy between the two heavy bands favors orbital order. When orbital order does not occur, interactions still reshape the heavy-band Fermi surfaces. I will discuss these results in the context of recently reported magnetotransport experiments.

Control of interlayer physics in 2H transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Wang, Kuang-Chung; Stanev, Teodor K.; Valencia, Daniel; Charles, James; Henning, Alex; Sangwan, Vinod K.; Lahiri, Aritra; Mejia, Daniel; Sarangapani, Prasad; Povolotskyi, Michael; Afzalian, Aryan; Maassen, Jesse; Klimeck, Gerhard; Hersam, Mark C.; Lauhon, Lincoln J.; Stern, Nathaniel P.; Kubis, Tillmann

2017-12-01

It is assessed in detail both experimentally and theoretically how the interlayer coupling of transition metal dichalcogenides controls the electronic properties of the respective devices. Gated transition metal dichalcogenide structures show electrons and holes to either localize in individual monolayers, or delocalize beyond multiple layers—depending on the balance between spin-orbit interaction and interlayer hopping. This balance depends on the layer thickness, momentum space symmetry points, and applied gate fields. The design range of this balance, the effective Fermi levels, and all relevant effective masses is analyzed in great detail. A good quantitative agreement of predictions and measurements of the quantum confined Stark effect in gated MoS2 systems unveils intralayer excitons as the major source for the observed photoluminescence.

Energy dependence of the response of lithium fluoride TLD rods in high energy electron fields.

PubMed

Holt, J G; Edelstein, G R; Clark, T E

1975-07-01

The energy dependence of lithium fluoride dosemeters is a complicated function of energy as well as of cavity size. In the application of TLD to charged particle dosimetry, a cavity perturbation effect may exist even though the ratios of the mass stopping powers are constant over the energies encountered. This effect was investigated for lithium fluoride rods in electron fields ranging in energy from 2-5 to 20 MeV. A 13% change of TL response per unit of absorbed dose was measured over that energy range. A semi-empirical theory was developed to account for the cavity effect, using Burlin cavity theory as a starting point. The agreement between theory and measurement is satisfactory.

STELLAR, GAS, AND DARK MATTER CONTENT OF BARRED GALAXIES

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

Cervantes Sodi, Bernardo, E-mail: b.cervantes@crya.unam.mx

We select a sample of galaxies from the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7) where galaxies are classified, through visual inspection, as hosting strong bars, weak bars, or as unbarred galaxies, and make use of H i mass and kinematic information from the Arecibo Legacy Fast ALFA survey catalog, to study the stellar, atomic gas, and dark matter content of barred disk galaxies. We find, in agreement with previous studies, that the bar fraction increases with increasing stellar mass. A similar trend is found with total baryonic mass, although the dependence is not as strong as with stellarmore » mass, due to the contribution of gas. The bar fraction shows a decrease with increasing gas mass fraction. This anticorrelation between the likelihood of a galaxy hosting a bar with the gas richness of the galaxy results from the inhibiting effect the gas has in the formation of bars. We also find that for massive galaxies with stellar masses larger than 10{sup 10} M {sub ⊙}, at fixed stellar mass, the bar fraction decreases with increasing global halo mass (i.e., halo mass measured up to a radius of the order of the H i disk extent).« less

Electrospray Ionization with High-Resolution Mass Spectrometry as a Tool for Lignomics: Lignin Mass Spectrum Deconvolution

NASA Astrophysics Data System (ADS)

Andrianova, Anastasia A.; DiProspero, Thomas; Geib, Clayton; Smoliakova, Irina P.; Kozliak, Evguenii I.; Kubátová, Alena

2018-05-01

The capability to characterize lignin, lignocellulose, and their degradation products is essential for the development of new renewable feedstocks. Electrospray ionization high-resolution time-of-flight mass spectrometry (ESI-HR TOF-MS) method was developed expanding the lignomics toolkit while targeting the simultaneous detection of low and high molecular weight (MW) lignin species. The effect of a broad range of electrolytes and various ionization conditions on ion formation and ionization effectiveness was studied using a suite of mono-, di-, and triarene lignin model compounds as well as kraft alkali lignin. Contrary to the previous studies, the positive ionization mode was found to be more effective for methoxy-substituted arenes and polyphenols, i.e., species of a broadly varied MW structurally similar to the native lignin. For the first time, we report an effective formation of multiply charged species of lignin with the subsequent mass spectrum deconvolution in the presence of 100 mmol L-1 formic acid in the positive ESI mode. The developed method enabled the detection of lignin species with an MW between 150 and 9000 Da or higher, depending on the mass analyzer. The obtained M n and M w values of 1500 and 2500 Da, respectively, were in good agreement with those determined by gel permeation chromatography. Furthermore, the deconvoluted ESI mass spectrum was similar to that obtained with matrix-assisted laser desorption/ionization (MALDI)-HR TOF-MS, yet featuring a higher signal-to-noise ratio. The formation of multiply charged species was confirmed with ion mobility ESI-HR Q-TOF-MS. [Figure not available: see fulltext.

Electrospray Ionization with High-Resolution Mass Spectrometry as a Tool for Lignomics: Lignin Mass Spectrum Deconvolution

NASA Astrophysics Data System (ADS)

Andrianova, Anastasia A.; DiProspero, Thomas; Geib, Clayton; Smoliakova, Irina P.; Kozliak, Evguenii I.; Kubátová, Alena

2018-03-01

The capability to characterize lignin, lignocellulose, and their degradation products is essential for the development of new renewable feedstocks. Electrospray ionization high-resolution time-of-flight mass spectrometry (ESI-HR TOF-MS) method was developed expanding the lignomics toolkit while targeting the simultaneous detection of low and high molecular weight (MW) lignin species. The effect of a broad range of electrolytes and various ionization conditions on ion formation and ionization effectiveness was studied using a suite of mono-, di-, and triarene lignin model compounds as well as kraft alkali lignin. Contrary to the previous studies, the positive ionization mode was found to be more effective for methoxy-substituted arenes and polyphenols, i.e., species of a broadly varied MW structurally similar to the native lignin. For the first time, we report an effective formation of multiply charged species of lignin with the subsequent mass spectrum deconvolution in the presence of 100 mmol L-1 formic acid in the positive ESI mode. The developed method enabled the detection of lignin species with an MW between 150 and 9000 Da or higher, depending on the mass analyzer. The obtained M n and M w values of 1500 and 2500 Da, respectively, were in good agreement with those determined by gel permeation chromatography. Furthermore, the deconvoluted ESI mass spectrum was similar to that obtained with matrix-assisted laser desorption/ionization (MALDI)-HR TOF-MS, yet featuring a higher signal-to-noise ratio. The formation of multiply charged species was confirmed with ion mobility ESI-HR Q-TOF-MS. [Figure not available: see fulltext.

Density dependent interactions between VA mycorrhizal fungi and even-aged seedlings of two perennial Fabaceae species.

PubMed

Allsopp, N; Stock, W D

1992-08-01

The interaction of density and mycorrhizal effects on the growth, mineral nutrition and size distribution of seedlings of two perennial members of the Fabaceae was investigated in pot culture. Seedlings of Otholobium hirtum and Aspalathus linearis were grown at densities of 1, 4, 8 and 16 plants per 13-cm pot with or without vesicular-arbuscular (VA) mycorrhizal inoculum for 120 days. Plant mass, relative growth rates, height and leaf number all decreased with increasing plant density. This was ascribed to the decreasing availability of phosphorus per plant as density increased. O. hirtum was highly dependent on mycorrhizas for P uptake but both mycorrhizal and non-mycorrhizal A. linearis seedlings were able to extract soil P with equal ease. Plant size distribution as measured by the coefficient of variation (CV) of shoot mass was greater at higher densities. CVs of mycorrhizal O. hirtum plants were higher than those of non-mycorrhizal plants. CVs of the facultatively mycorrhizal A. linearis were similar for both mycorrhizal and non-mycorrhizal plants. Higher CVs are attributed to resource preemption by larger individuals. Individuals in populations with high CVs will probably survive stress which would result in the extinction of populations with low CVs. Mass of mycorrhizal plants of both species decreased more rapidly with increasing density than did non-mycorrhizal plant mass. It is concluded that the cost of being mycorrhizal increases as plant density increases, while the benefit decreases. The results suggest that mycorrhizas will influence density-dependent population processes of faculative and obligate mycorrhizal species.

Critical insight into the influence of the potential energy surface on fission dynamics

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

Mazurek, K.; Grand Accelerateur National d'Ions Lourds; Schmitt, C.

The present work is dedicated to a careful investigation of the influence of the potential energy surface on the fission process. The time evolution of nuclei at high excitation energy and angular momentum is studied by means of three-dimensional Langevin calculations performed for two different parametrizations of the macroscopic potential: the Finite Range Liquid Drop Model (FRLDM) and the Lublin-Strasbourg Drop (LSD) prescription. Depending on the mass of the system, the topology of the potential throughout the deformation space of interest in fission is observed to noticeably differ within these two approaches, due to the treatment of curvature effects. Whenmore » utilized in the dynamical calculation as the driving potential, the FRLDM and LSD models yield similar results in the heavy-mass region, whereas the predictions can be strongly dependent on the Potential Energy Surface (PES) for medium-mass nuclei. In particular, the mass, charge, and total kinetic energy distributions of the fission fragments are found to be narrower with the LSD prescription. The influence of critical model parameters on our findings is carefully investigated. The present study sheds light on the experimental conditions and signatures well suited for constraining the parametrization of the macroscopic potential. Its implication regarding the interpretation of available experimental data is briefly discussed.« less

Unifying principles in terrestrial locomotion: do hopping Australian marsupials fit in?

PubMed

Bennett, M B

2000-01-01

Mammalian terrestrial locomotion has many unifying principles. However, the Macropodoidea are a particularly interesting group that exhibit a number of significant deviations from the principles that seem to apply to other mammals. While the properties of materials that comprise the musculoskeletal system of mammals are similar, evidence suggests that tendon properties in macropodoid marsupials may be size or function dependent, in contrast to the situation in placental mammals. Postural differences related to hopping versus running have a dramatic effect on the scaling of the pelvic limb musculoskeletal system. Ratios of muscle fibre to tendon cross-sectional areas for ankle extensors and digital flexors scale with positive allometry in all mammals, but exponents are significantly higher in macropods. Tendon safety factors decline with increasing body mass in mammals, with eutherians at risk of ankle extensor tendon rupture at a body mass of about 150 kg, whereas kangaroos encounter similar problems at a body mass of approximately 35 kg. Tendon strength appears to limit locomotor performance in these animals. Elastic strain energy storage in tendons is mass dependent in all mammals, but exponents are significantly larger in macropodid. Tibial stresses may scale with positive allometry in kangaroos, which result in lower bone safety factors in macropods compared to eutherian mammals.

The correlation between the sizes of globular cluster systems and their host dark matter haloes

NASA Astrophysics Data System (ADS)

Hudson, Michael J.; Robison, Bailey

2018-07-01

The sizes of entire systems of globular clusters (GCs) depend not only on the formation and destruction histories of the GCs themselves but also on the assembly, merger, and accretion history of the dark matter (DM) haloes that they inhabit. Recent work has shown a linear relation between total mass of GCs in the GC system and the mass of its host DM halo, calibrated from weak lensing. Here, we extend this to GC system sizes, by studying the radial density profiles of GCs around galaxies in nearby galaxy groups. We find that radial density profiles of the GC systems are well fit with a de Vaucouleurs profile. Combining our results with those from the literature, we find tight relationship (˜0.2 dex scatter) between the effective radius of the GC system and the virial radius (or mass) of its host DM halo, for haloes with masses greater than ˜1012 M⊙. The steep non-linear dependence of this relationship (R_{ {e, GCS}} ∝ R_{200}^{2.5 - 3} ∝ M_{200}^{0.8 - 1}) is currently not well understood, but is an important clue regarding the assembly history of DM haloes and of the GC systems that they host.

Lattice dynamics approach to determine the dependence of the time-of-flight of transversal polarized acoustic waves on external stress

NASA Astrophysics Data System (ADS)

Tarar, K. S.; Pluta, M.; Amjad, U.; Grill, W.

2011-04-01

Based on the lattice dynamics approach the dependence of the time-of-flight (TOF) on stress has been modeled for transversal polarized acoustic waves. The relevant dispersion relation is derived from the appropriate mass-spring model together with the dependencies on the restoring forces including the effect of externally applied stress. The lattice dynamics approach can also be interpreted as a discrete and strictly periodic lumped circuit. In that case the modeling represents a finite element approach. In both cases the properties relevant for wavelengths large with respect to the periodic structure can be derived from the respective limit relating also to low frequencies. The model representing a linear chain with stiffness to shear and additional stiffness introduced by extensional stress is presented and compared to existing models, which so far represent each only one of the effects treated here in combination. For a string this effect is well known from musical instruments. The counteracting effects are discussed and compared to experimental results.