Nonlinear Schroedinger-Poisson definition of fine-structure-constant's value {approx}1/137
Reinisch, G, E-mail: Gilbert.Reinisch@oca.e [Universite de Nice - Sophia Antipolis CNRS, Observatoire de la Cote d' Azur BP 4229 06304 - Nice Cedex 4 (France)
2010-06-01
By numerically investigating the nonlinear Schroedinger-Poisson eigenstates of a condensed Bose gas of charged particles that is confined in a two-dimensional axisymmetric parabolic potential 1/2 m{sub e{omega}}{sup 2}r{sup 2} (e.g. quantum-dot helium), it is shown that the probability amplitude between two nonlinear-and hence non-orthogonal-eigenstates displays an interference pattern scaled (within 0.03 %) by graphic equation Since {alpha} = e{sup 2}/ h-bar c {approx} 1/137 is the fine structure constant, this stunning result-indeed velocity of light c does not enter the present non-relativistic model-is tentatively explained by the existence of a 'nonlinear' bound state of the trapped particle-particle interaction Coulomb field whose energy cal E = half pi hbar omega defines the induced emission or absorption equilibrium processes between two appropriate chemical potentials. Besides, a non-decoherence quantum-classical transition with increasing nonlinearity is pointed out. As a possible experimental test for the present theory, the 0s{sup 2} {yields}1s{sup 2} nonlinear transition in an {h_bar} {omega} = 1.66meV GaAs quantum-dot helium is emphasized.
Rate Constant Calculation for Thermal Reactions Methods and Applications
DaCosta, Herbert
2011-01-01
Providing an overview of the latest computational approaches to estimate rate constants for thermal reactions, this book addresses the theories behind various first-principle and approximation methods that have emerged in the last twenty years with validation examples. It presents in-depth applications of those theories to a wide range of basic and applied research areas. When doing modeling and simulation of chemical reactions (as in many other cases), one often has to compromise between higher-accuracy/higher-precision approaches (which are usually time-consuming) and approximate/lower-preci
High temperature elastic constant measurements: application to plutonium
We present an apparatus with which we have measured the Young's modulus and the Poisson's ratio of several compounds from the resonance frequency of cylinders in the temperature range 0 deg. C-700 deg. C. We especially studied the elastic constants of plutonium and measured for the first time to our knowledge the Young's modulus of Puδ and Puε. Eδ 360 deg. C = 1.6 1011 dy/cm2; Eε 490 deg. C = 1.1 1011 dy/cm2, σε = 0.25 ± 0.03 Using our results, we have calculated the compressibility, the Debye temperature, the Grueneisen constant and the electronic specific heat of Puε. (author)
TAO Wen-liang; WEI Tao
2006-01-01
This research is carried out on the basis of Constant Strain Rate(CSR) to measure creep internal stress. Measurements of creep internal stress are conducted on the material test machine by using the CSR method. A mathematical model of creep internal stress is also proposed and its application is presented in this paper.
Keisuke Fujisaki
2013-11-01
Full Text Available To connect different scale models in the multi-scale problem of microwave use, equivalent material constants were researched numerically by a three-dimensional electromagnetic field, taking into account eddy current and displacement current. A volume averaged method and a standing wave method were used to introduce the equivalent material constants; water particles and aluminum particles are used as composite materials. Consumed electrical power is used for the evaluation. Water particles have the same equivalent material constants for both methods; the same electrical power is obtained for both the precise model (micro-model and the homogeneous model (macro-model. However, aluminum particles have dissimilar equivalent material constants for both methods; different electric power is obtained for both models. The varying electromagnetic phenomena are derived from the expression of eddy current. For small electrical conductivity such as water, the macro-current which flows in the macro-model and the micro-current which flows in the micro-model express the same electromagnetic phenomena. However, for large electrical conductivity such as aluminum, the macro-current and micro-current express different electromagnetic phenomena. The eddy current which is observed in the micro-model is not expressed by the macro-model. Therefore, the equivalent material constant derived from the volume averaged method and the standing wave method is applicable to water with a small electrical conductivity, although not applicable to aluminum with a large electrical conductivity.
Quantum theory of the dielectric constant of a magnetized plasma and astrophysical applications. I.
Canuto, V.; Ventura, J.
1972-01-01
A quantum mechanical treatment of an electron plasma in a constant and homogeneous magnetic field is considered, with the aim of (1) defining the range of validity of the magnetoionic theory (2) studying the deviations from this theory, in applications involving high densities, and intense magnetic field. While treating the magnetic field exactly, a perturbation approach in the photon field is used to derive general expressions for the dielectric tensor. Numerical estimates on the range of applicability of the magnetoionic theory are given for the case of the 'one-dimensional' electron gas, where only the lowest Landau level is occupied.
Applications of the constant-current variable-voltage dc accelerator
Variable beam energy at constant current is useful for industrial applications such as surface hardening and passivation or semiconductor processing. We discuss a dc accelerator, under development for the DOE magnetic fusion energy program, which uses electrostatic quadrupole (ESQ) focusing to maintain constant current while the voltage is variable over a wide range. The use of ESQs also allows a conservative design that alleviates known causes of dc voltage breakdown. The beam is accelerated by a series of 100 kV ESQ modules, stackable to a megavolt or more. The energy is tunable to as low as 20 keV without reduction in current. Single-beam and multiple-beam systems have been designed, capable of accelerating typically 50 mA of N+ or O+ per beam. (orig.)
Isospin Mixing In N $\\approx$ Z Nuclei
Srnka, D; Versyck, S; Zakoucky, D
2002-01-01
Isospin mixing in N $\\approx$ Z nuclei region of the nuclear chart is an important phenomenon in nuclear physics which has recently gained theoretical and experimental interest. It also forms an important nuclear physics correction in the precise determination of the $ft$-values of superallowed 0$^+ \\rightarrow 0^+ \\beta$- transitions. The latter are used in precision tests of the weak interaction from nuclear $\\beta$- decay. We propose to experimentally measure isospin mixing into nuclear ground states in the N $\\approx$ Z region by determining the isospin forbidden Fermi-component in the Gamow-Teller dominated $J^{\\pi} \\rightarrow J^{\\pi} \\beta$- transitions through the observation of anisotropic positron emission from oriented nuclei. First measurements were carried out with $^{71}$As and are being analyzed now.
Resonant converter topologies for constant-current power supplies and their applications
Power electronics, in general, and power supplies, in particular, is an important field of accelerator technology due to its widespread use, for instance in dc, ramp or pulse magnet power supplies, high voltage power supplies for electrostatic accelerators and RF amplifies, power supplies for vacuum pumps, vacuum gauges, beam diagnostic devices etc. It has been possible to meet stringent performance requirements with the continuing advancement in the field of power electronics. Resonant converters have been an active area of research in power electronics field due to variety of topologies, diverse, peculiar and useful characteristics. While the majority of the previous work on resonant converters has been directed towards developing methods of analysis and control techniques for the mentioned applications, very little has been done to explore their suitability for application as a constant-current power supply, which is either inherently required or can be advantageously applied in power supplies for various accelerator subsystems and other industrial applications such as electric arc welding, laser diode drivers, magnet illumination systems, battery charging, electrochemical processes etc.
Application of equivalence methods on Monte Carlo method based homogenization multi-group constants
The multi-group constants generated via continuous energy Monte Carlo method do not satisfy the equivalence between reference calculation and diffusion calculation applied in reactor core analysis. To the satisfaction of the equivalence theory, general equivalence theory (GET) and super homogenization method (SPH) were applied to the Monte Carlo method based group constants, and a simplified reactor core and C5G7 benchmark were examined with the Monte Carlo constants. The results show that the calculating precision of group constants is improved, and GET and SPH are good candidates for the equivalence treatment of Monte Carlo homogenization. (authors)
Evaluation and Application of the Constant Flow Technique in Testing Low-Permeability Geo-Materials
Safety assessment of facilities involved in geological disposal of hazardous waste, including radioactive nuclear waste, is generally performed through mass transport simulations combined with uncertainty and sensitivity analyses. Transport of contaminants, such as radionuclides, through an engineered and/or natural barrier system is mainly controlled by advection, dispersion, sorption, and chain decay. Ideally, waste disposal facilities should be constructed in the geological environments where groundwater is not existent, or groundwater is static, or its flow is extremely slow. Potential fluid flow, however, may be induced by thermal convection and/or gas generation, and thus accurate evaluation of hydraulic properties, specifically the permeability and specific storage, along with diffusive transport properties of engineered and natural barrier materials, is of fundamental importance for safety assessment. The engineered and natural barrier materials for isolating hazardous wastes are hydraulically tight, and special techniques are generally required to obtain both rapid and accurate determination of their hydraulic properties. In this paper, the constant flow technique is introduced and evaluated. The capability of this technique in testing low-permeability geo-materials are illustrated through practical applications to a bentonite-sand mixture and rock samples having low permeabilities. (authors)
Calibration of the k- ɛ model constants for use in CFD applications
Glover, Nina; Guillias, Serge; Malki-Epshtein, Liora
2011-11-01
The k- ɛ turbulence model is a popular choice in CFD modelling due to its robust nature and the fact that it has been well validated. However it has been noted in previous research that the k- ɛ model has problems predicting flow separation as well as unconfined and transient flows. The model contains five empirical model constants whose values were found through data fitting for a wide range of flows (Launder 1972) but ad-hoc adjustments are often made to these values depending on the situation being modeled. Here we use the example of flow within a regular street canyon to perform a Bayesian calibration of the model constants against wind tunnel data. This allows us to assess the sensitivity of the CFD model to changes in these constants, find the most suitable values for the constants as well as quantifying the uncertainty related to the constants and the CFD model as a whole.
Ziyatdinova, Guzel, E-mail: Ziyatdinovag@mail.ru [Analytical Chemistry Department, A.M. Butlerov Institute of Chemistry, Kazan (Volga Region) Federal University, Kremlyevskaya, 18, Kazan 420008 (Russian Federation); Ziganshina, Endzhe; Budnikov, Herman [Analytical Chemistry Department, A.M. Butlerov Institute of Chemistry, Kazan (Volga Region) Federal University, Kremlyevskaya, 18, Kazan 420008 (Russian Federation)
2012-09-26
Highlights: Black-Right-Pointing-Pointer Applicability of surfactants in constant-current coulometry is shown for the first time. Black-Right-Pointing-Pointer Reactions of antioxidants with electrogenerated titrants in surfactant media are investigated. Black-Right-Pointing-Pointer Water insoluble antioxidants can be determined in water media with addition of surfactants. Black-Right-Pointing-Pointer Coulometric determination of antioxidants in pharmaceutical dosage forms using surfactants media is developed. - Abstract: Effect of surfactant presence on electrochemical generation of titrants has been evaluated and discussed for the first time. Cationic (1-dodecylpyridinium and cetylpyridinium bromide), anionic (sodium dodecyl sulfate) and nonionic (Triton X100 and Brij{sup Registered-Sign} 35) surfactants as well as nonionic high molecular weight polymer (PEG 4000) do not react with the electrogenerated bromine, iodine and hexacyanoferrate(III) ions. The electrogenerated chlorine chemically interact with Triton X100 and Brij{sup Registered-Sign} 35. The allowable range of surfactants concentrations providing 100% current yield has been found. Chain-breaking low molecular weight antioxidants (ascorbic acid, rutin, {alpha}-tocopherol and retinol) were determined by reaction with the electrogenerated titrants in surfactant media. Nonionic and cationic surfactants can be used for the determination of antioxidants by reaction with the electrogenerated halogens. On contrary, cationic surfactants gives significantly overstated results of antioxidants determination with electrogenerated hexacyanoferrate(III) ions. The use of surfactants in coulometry of {alpha}-tocopherol and retinol provides their solubilization and allows to perform titration in water media. Simple, express and reliable coulometric approach for determination of {alpha}-tocopherol, rutin and ascorbic acid in pharmaceuticals using surfactant media has been developed. The relative standard deviation of the
Li, Changsheng
2013-12-01
Verdet constants of beta-barium borate (BBO) and lead molybdate (PMO) crystals are measured experimentally by the method of comparison with a block of terbium-doped glass with a known Verdet constant. Experimental setups mainly include two prism polarizers, a solenoid and ac current supply, and signal processing circuits. The influences of light intensity fluctuation, applied magnetic field and signal processing circuits on measurement result of Verdet constant can be removed by using the method of comparison. For light wavelength of 635nm, the measured Verdet constants respectively are 5.80+/-0.06 rad/(T.m) for the BBO crystal and 54.6+/-1.1 rad/(T.m) for the PMO crystal. A novel optical current sensor based on electrooptic compensation is designed in principle using the BBO crystal.
A systematic method to calculate anharmonic force constants of crystals is presented. The method employs the direct-method approach, where anharmonic force constants are extracted from the trajectory of first-principles molecular dynamics simulations at high temperature. The method is applied to Si where accurate cubic and quartic force constants are obtained. We observe that higher-order correction is crucial to obtain accurate force constants from the trajectory with large atomic displacements. The calculated harmonic and anharmonic force constants are, then, combined with the Boltzmann transport equation (BTE) and non-equilibrium molecular dynamics (NEMD) methods in calculating the thermal conductivity. The BTE approach successfully predicts the lattice thermal conductivity of bulk Si, whereas NEMD shows considerable underestimates. To evaluate the linear extrapolation method employed in NEMD to estimate bulk values, we analyze the size dependence in NEMD based on BTE calculations. We observe strong nonlinearity in the size dependence of NEMD in Si, which can be ascribed to acoustic phonons having long mean-free-paths and carrying considerable heat. Subsequently, we also apply the whole method to a thermoelectric material Mg2Si and demonstrate the reliability of the NEMD method for systems with low thermal conductivities. (paper)
Model of constant probability event and its application in information fusion
邓勇; 施文康
2004-01-01
A model of constant probability event is constructed rigorously in event space of PSCEA. It is showed that the numerical-based fusion and the algebraic-based fusion have a consistent result when the weight is regarded as a constant probability event. From the point of view of algebra, we present a novel similarity measure in product space. Based on the similarity degree, we use a similarity aggregation method to fusion experts' evaluation. We also give a numerical example to illustrate the method.
Hodzic, A.; Aumont, B.; Knote, C.; Lee-Taylor, J.; Madronich, S.; Tyndall, G.
2014-07-01
The water solubility of oxidation intermediates of volatile organic compounds that can condense to form secondary organic aerosol (SOA) is largely unconstrained in current chemistry-climate models. We apply the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere to calculate Henry's law constants for these intermediate species. Results show a strong negative correlation between Henry's law constants and saturation vapor pressures. Details depend on precursor species, extent of photochemical processing, and NOx levels. Henry's law constants as a function of volatility are made available over a wide range of vapor pressures for use in 3-D models. In an application using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) over the U.S. in summer, we find that dry (and wet) deposition of condensable organic vapors leads to major reductions in SOA, decreasing surface concentrations by ~50% (10%) for biogenic and ~40% (6%) for short chain anthropogenic precursors under the considered volatility conditions.
Zhang, Chao; Hutter, Jürg; Sprik, Michiel
2016-07-21
In his classic 1939 paper, Kirkwood linked the macroscopic dielectric constant of polar liquids to the local orientational order as measured by the g-factor (later named after him) and suggested that the corresponding dielectric constant at short-range is effectively equal to the macroscopic value just after "a distance of molecular magnitude" [ Kirkwood, J. Chem. Phys., 1939, 7, 911 ]. Here, we show a simple approach to extract the short-ranged Kirkwood g-factor from molecular dynamics (MD) simulation by superposing the outcomes of constant electric field E and constant electric displacement D simulations [ Zhang and Sprik, Phys. Rev. B: Condens. Matter Mater. Phys., 2016, 93, 144201 ]. Rather than from the notoriously slow fluctuations of the dipole moment of the full MD cell, the dielectric constant can now be estimated from dipole fluctuations at short-range, accelerating the convergence. Exploiting this feature, we computed the bulk dielectric constant of liquid water modeled in the generalized gradient approximation (PBE) to density functional theory and found it to be at least 40% larger than the experimental value. PMID:27352038
Temperature and Pressure Derivatives of Elastic Constants With Application to the Mantle
Anderson, Don L.
1988-01-01
The temperature and pressure derivatives of the elastic moduli M of solids can be cast into the form of dimensionless logarithmic anharmonic {DLA} parameters, ∂ ln M/∂ In p = {M} at constant temperature, pressure, or entropy (T, P, S), where p is the density. These parameters show little variation from material to material and are expected to show little variation with temperature at high temperature. Most of the available derivative data for ionic solids has been renormalized and analyzed fo...
Omur, Pinar
2004-01-01
Although utilities attempt to avoid offensive smelling compounds in consumer's drinking water, their efforts are often hampered by a lack of data or knowledge of the physical, chemical, and sensory properties of odorants. Many factors affect the ability of a consumer to detect odors, including: concentration, presence of chlorine/other odorants, temperature, and the individual's sensitivity. This research developed a simplified static-headspace technique to determine Henry's Law constants...
Reese, Erik D; Kitayama, Tetsu; Ota, Naomi; Sasaki, Shin; Suto, Yasushi
2010-01-01
We perform a uniform, systematic analysis of a sample of 38 X-ray galaxy clusters with three different Chandra calibrations. The temperatures change systematically between calibrations. Cluster temperatures change on average by roughly ~6% for the smallest changes and roughly ~13% for the more extreme changes between calibrations. We explore the effects of the changing cluster spectral properties on Sunyaev-Zel'dovich effect (SZE) and X-ray determinations of the Hubble constant. The Hubble parameter changes by +10% and -13% between the current calibration and two previous Chandra calibrations, indicating that changes in the cluster temperature basically explain the entire change in H_0. Although this work focuses on the difference in spectral properties and resultant Hubble parameters between the calibrations, it is intriguing to note that the newer calibrations favor a lower value of the Hubble constant, H_0 ~ 60 km s-1 Mpc-1, typical of results from SZE/X-ray distances. Both galaxy clusters themselves and t...
Bhardwaj, R. C.
Conventional power sources are able to deliver high energy, but high-power demands can be met only with advanced electrochemical or heavy battery devices. BOLDER Technologies has developed a high-power cell (86 g, 1.0 A h, 2 V) based on patented Thin Metal Film (TMF®) Technology which is capable of delivering very high constant or pulse power for several applications. Six cells in a 0.5-1 kg pack are capable of delivering 1 to 1000 A with a stiff voltage plateau of 12 V for periods ranging from 1 h to a few milliseconds, respectively, and constant power not provided by any other battery chemistry. The BOLDER TMF® cells are made of thin lead foil and PbO active material, which gives enormous cost advantages compared with existing lead-acid batteries or with competing battery systems. This paper presents the high constant-power and pulse-power delivery characteristics of batteries made with TMF technology. The new concept of developing hybrid power sources with proton exchange membrane fuel cells (PEMFCs) or other battery types for electronic communication and turbine-starting applications is also discussed.
Magallanes, Francisco Cabaleiro; Viarouge, Philippe; Cros, Jérôme
2015-01-01
This paper proposes a novel topological solution for pulsed power converters based on capacitor-discharge topologies, integrating a Fast Voltage Compensator which allows an operation at constant power consumption from the utility grid. This solution has been retained as a possible candidate for the CLIC project under study at CERN, which requires more than a thousand synchronously-operated klystron modulators producing a total pulsed power of almost 40 GW. The proposed Fast Voltage Compensator is integrated in the modulator such that it only has to treat the capacitor charger current and a fraction of the charging voltage, meaning that its dimensioning power and cost are minimized. This topology can be used to improve the AC power quality of any pulsed converters based on capacitor-discharge concept. A prototype has been built and exploited to validate the operating principle and demonstrate the benefits of the proposed solution.
Liesbeth van Oeffelen
Full Text Available Current software applications for densitometric analysis, such as ImageJ, QuantityOne (BioRad and the Intelligent or Advanced Quantifier (Bio Image do not allow to take the non-linearity of autoradiographic films into account during calibration. As a consequence, quantification of autoradiographs is often regarded as problematic, and phosphorimaging is the preferred alternative. However, the non-linear behaviour of autoradiographs can be described mathematically, so it can be accounted for. Therefore, the 'Densitometric Image Analysis Software' has been developed, which allows to quantify electrophoretic bands in autoradiographs, as well as in gels and phosphorimages, while providing optimized band selection support to the user. Moreover, the program can determine protein-DNA binding constants from Electrophoretic Mobility Shift Assays (EMSAs. For this purpose, the software calculates a chosen stepwise equilibrium constant for each migration lane within the EMSA, and estimates the errors due to non-uniformity of the background noise, smear caused by complex dissociation or denaturation of double-stranded DNA, and technical errors such as pipetting inaccuracies. Thereby, the program helps the user to optimize experimental parameters and to choose the best lanes for estimating an average equilibrium constant. This process can reduce the inaccuracy of equilibrium constants from the usual factor of 2 to about 20%, which is particularly useful when determining position weight matrices and cooperative binding constants to predict genomic binding sites. The MATLAB source code, platform-dependent software and installation instructions are available via the website http://micr.vub.ac.be.
Urano, Miho; Saida, Hiromi
2009-01-01
The mechanical first law (MFL) of black hole spacetimes is a geometrical relation which relates variations of mass parameter and horizon area. While it is well known that the MFL of asymptotic flat black hole is equivalent to its thermodynamical first law, however we do not know the detail of MFL of black hole spacetimes with cosmological constant which possess black hole and cosmological event horizons. Then this paper aims to formulate an MFL of the two-horizon spacetimes. For this purpose, we try to include the effects of two horizons in the MFL. To do so, we make use of the Iyer-Wald formalism and extend it to regard the mass parameter and the cosmological constant as two independent variables which make it possible to treat the two horizons on the same footing. Our extended Iyer-Wald formalism preserves the existence of conserved Noether current and its associated Noether charge, and gives the abstract form of MFL of black hole spacetimes with cosmological constant. Then, as a representative application ...
The formation constant of molybdophosphate complex and it's application in the product of xenotime sand, tooth and bone have been studied by spectrophotometric method. The molybdophosphate complex were formed from reaction between phosphate and molybdate on several of pH in the strong acid condition (pH = 0.45 - 0.71) and several of phosphate mole fraction (0.01 - 0.08). The several of complex formation reactions were determined by matrix disintegration technique. Molybdophosphate complex were founded three forms i.e. (P2Mo18O62)6- or 9 MPA, (PMo11O39)7- or 11 MPA and (PMo12O40)3- or 12 MPA. The formation constant of (PMo12O40)3- complex was found β = 1046.95 ± 103.7, while for (P2Mo18O62)6- and (PMo11O39)7- were not detected. The application in samples were found the concentration of P in product of xenotime sand : 5.37±0.08 μg/ml, in canine-tooth: 10.40 - 19.49 % in cutting-tooth : 11.08 - 18.05 % and in bone 10.94 - 14.29 %. (author)
Snyder, Jeff; Hanstock, Chris C.; Wilman, Alan H.
2009-10-01
A general in vivo magnetic resonance spectroscopy editing technique is presented to detect weakly coupled spin systems through subtraction, while preserving singlets through addition, and is applied to the specific brain metabolite γ-aminobutyric acid (GABA) at 4.7 T. The new method uses double spin echo localization (PRESS) and is based on a constant echo time difference spectroscopy approach employing subtraction of two asymmetric echo timings, which is normally only applicable to strongly coupled spin systems. By utilizing flip angle reduction of one of the two refocusing pulses in the PRESS sequence, we demonstrate that this difference method may be extended to weakly coupled systems, thereby providing a very simple yet effective editing process. The difference method is first illustrated analytically using a simple two spin weakly coupled spin system. The technique was then demonstrated for the 3.01 ppm resonance of GABA, which is obscured by the strong singlet peak of creatine in vivo. Full numerical simulations, as well as phantom and in vivo experiments were performed. The difference method used two asymmetric PRESS timings with a constant total echo time of 131 ms and a reduced 120° final pulse, providing 25% GABA yield upon subtraction compared to two short echo standard PRESS experiments. Phantom and in vivo results from human brain demonstrate efficacy of this method in agreement with numerical simulations.
Conventional collapsing for group cross sections used in multigroup nuclear reactor calculations is usually performed using normal (real; direct) flux weighting. The application of more advanced collapsing procedures using in an appropriate manner real, adjoint and bilinear weighting was in the past restricted in general to fundamental mode problems. Although the principles have been published for more than ten years, there seems to exist little recent experience on the merits and possible difficulties of these improved procedures for multidimensional diffusion problems for practical purposes, e.g. in the nuclear design and analysis of large Liquid Metal Fast Breeder Reactors (LMFBRs). The present work indicates the nature of the problems which could possibly be encountered in applying these procedures by tracing them back to the known close correspondence between group collapsing and synthesis methods. It tries to explain certain somewhat unusual features of the collapsed group constants obtained by adjoint and bilinear weighting and describes the experience gained in representative 1-dim. and 2-dim. test cases. It could be shown for criticality and perturbation calculations that in general it is advantageous to apply these improved collapsing methods if the necessary precautions are taken. Compared to the conventional collapsing procedures these improved procedures are especially useful for multidimensional problems because their application is well suited for that purpose. In the present study it could be proven that they are favorable with respect to computer time and storage needed due to the fact that the necessary number of coarse groups can be kept fairly small without deteriorating too much the accuracy and reliability of the coarse group results compared to reference results of corresponding fine group calculations with uncollapsed group constants. (orig.)
Optical constants of materials in the EUV/soft x-ray region for multilayer mirror applications
Soufli, R [Univ. of California, Berkeley, CA (United States)
1997-12-01
The response of a given material to an incident electromagnetic wave is described by the energy dependent complex index of refraction n = 1 {minus} {delta} + i{beta}. In the extreme ultraviolet (EUV)/soft x-ray spectral region, the need for accurate determination of n is driven by activity in areas such as synchrotron based research, EUV/x-ray lithography, x-ray astronomy and plasma applications. Knowledge of the refractive index is essential for the design of the optical components of instruments used in experiments and applications. Moreover, measured values of n may be used to evaluate solid state models for the optical behavior of materials. The refractive index n of Si, Mo and Be is investigated in the EUV/soft x-ray region. In the case of Si, angle dependent reflectance measurements are performed in the energy range 50--180 eV. The optical constants {delta}, {beta} are both determined by fitting to the Fresnel equations. The results of this method are compared to the values in the 1993 atomic tables. Photoabsorption measurements for the optical constants of Mo are performed on C/Mo/C foils, in the energy range 60--930 eV. Photoabsorption measurements on Be thin films supported on silicon nitride membranes are performed, and the results are applied in the determination of the absorption coefficient of Be in the energy region 111.5--250 eV. The new results for Si and Mo are applied to the calculation of normal incidence reflectivities of Mo/Si and Mo/Be multilayer mirrors. These calculations show the importance of accurate knowledge of {delta} and {beta} in the prediction and modeling of the performance of multilayer optics.
Barrow, J D
2005-01-01
We review properties of theories for the variation of the gravitation and fine structure 'constants'. We highlight some general features of the cosmological models that exist in these theories with reference to recent quasar data that are consistent with time-variation in the fine structure 'constant' since a redshift of 3.5. The behaviour of a simple class of varying-alpha cosmologies is outlined in the light of all the observational constraints.
Xiongwu Wu
2015-10-01
Full Text Available Chemical and thermodynamic equilibrium of multiple states is a fundamental phenomenon in biology systems and has been the focus of many experimental and computational studies. This work presents a simulation method to directly study the equilibrium of multiple states. This method constructs a virtual mixture of multiple states (VMMS to sample the conformational space of all chemical states simultaneously. The VMMS system consists of multiple subsystems, one for each state. The subsystem contains a solute and a solvent environment. The solute molecules in all subsystems share the same conformation but have their own solvent environments. Transition between states is implicated by the change of their molar fractions. Simulation of a VMMS system allows efficient calculation of relative free energies of all states, which in turn determine their equilibrium molar fractions. For systems with a large number of state transition sites, an implicit site approximation is introduced to minimize the cost of simulation. A direct application of the VMMS method is for constant pH simulation to study protonation equilibrium. Applying the VMMS method to a heptapeptide of 3 ionizable residues, we calculated the pKas of those residues both with all explicit states and with implicit sites and obtained consistent results. For mouse epidermal growth factor of 9 ionizable groups, our VMMS simulations with implicit sites produced pKas of all 9 ionizable groups and the results agree qualitatively with NMR measurement. This example demonstrates the VMMS method can be applied to systems of a large number of ionizable groups and the computational cost scales linearly with the number of ionizable groups. For one of the most challenging systems in constant pH calculation, SNase Δ+PHS/V66K, our VMMS simulation shows that it is the state-dependent water penetration that causes the large deviation in lysine66's pKa.
With different irradiation methods including high dose rate irradiation, low dose rate irradiation, alteration temperature and constant dose rate irradiation, and US military standard constant high temperature and constant dose rate irradiation, the ionizing radiation responses of bipolar linear regulator LM317 from three different companies were investigated under the operating and zero biases. The results show that compared with constant high temperature and constant dose rate irradiation method, the alteration temperature and constant dose rate irradiation method can not only very rapidly and accurately evaluate the dose rate effect of three bipolar linear regulators, but also well simulate the damage of low dose rate irradiation. Experiment results make the alteration temperature and constant dose rate irradiation method successfully apply to bipolar linear regulator. (authors)
Astrophysics to z approx. 10 with Gravitational Waves
Stebbins, Robin; Hughes, Scott; Lang, Ryan
2007-01-01
The most useful characterization of a gravitational wave detector's performance is the accuracy with which astrophysical parameters of potential gravitational wave sources can be estimated. One of the most important source types for the Laser Interferometer Space Antenna (LISA) is inspiraling binaries of black holes. LISA can measure mass and spin to better than 1% for a wide range of masses, even out to high redshifts. The most difficult parameter to estimate accurately is almost always luminosity distance. Nonetheless, LISA can measure luminosity distance of intermediate-mass black hole binary systems (total mass approx.10(exp 4) solar mass) out to z approx.10 with distance accuracies approaching 25% in many cases. With this performance, LISA will be able to follow the merger history of black holes from the earliest mergers of proto-galaxies to the present. LISA's performance as a function of mass from 1 to 10(exp 7) solar mass and of redshift out to z approx. 30 will be described. The re-formulation of LISA's science requirements based on an instrument sensitivity model and parameter estimation will be described.
Sparavigna, Amelia Carolina
2012-01-01
As proposed in a previous paper, the decorations of ancient objects can provide some information on the approximate evaluations of constant {\\pi}, the ratio of circumference to diameter. Here we discuss some disks found in the tomb of Hemaka, the chancellor of a king of the First Dynasty of Egypt, about 3000 BC. The discussion is based on measurements of the dimensionless ratio of lengths.
Robinson, H.P.; Potter, Elinor
1971-03-01
This collection of mathematical data consists of two tables of decimal constants arranged according to size rather than function, a third table of integers from 1 to 1000, giving some of their properties, and a fourth table listing some infinite series arranged according to increasing size of the coefficients of the terms. The decimal values of Tables I and II are given to 20 D.
HERSCHEL-ATLAS: TOWARD A SAMPLE OF {approx}1000 STRONGLY LENSED GALAXIES
Gonzalez-Nuevo, J.; Lapi, A.; Bressan, S.; Danese, L.; De Zotti, G.; Cai, Z.-Y.; Fan, L. [SISSA, Via Bonomea 265, I-34136 Trieste (Italy); Fleuren, S.; Sutherland, W. [School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Negrello, M. [Department of Physical Sciences, Open University, Milton Keynes MK7 6AA (United Kingdom); Baes, M. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Baker, A. J. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019 (United States); Clements, D. L. [Astrophysics Group, Imperial College, Blackett Lab, Prince Consort Road, London SW7 2AZ (United Kingdom); Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Dannerbauer, H. [Institut fuer Astronomie, Universitaet Wien, Tuerkenschanzstrasse 17, 1180 Wien, Oesterreich (Austria); Dunne, L.; Dye, S. [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Eales, S. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA (United Kingdom); Frayer, D. T. [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944 (United States); Harris, A. I., E-mail: gnuevo@sissa.it [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); and others
2012-04-10
While the selection of strongly lensed galaxies (SLGs) with 500 {mu}m flux density S{sub 500} > 100 mJy has proven to be rather straightforward, for many applications it is important to analyze samples larger than the ones obtained when confining ourselves to such a bright limit. Moreover, only by probing to fainter flux densities is it possible to exploit strong lensing to investigate the bulk of the high-z star-forming galaxy population. We describe HALOS (the Herschel-ATLAS Lensed Objects Selection), a method for efficiently selecting fainter candidate SLGs, reaching a surface density of {approx_equal} 1.5-2 deg{sup -2}, i.e., a factor of about 4-6 higher than that at the 100 mJy flux limit. HALOS will allow the selection of up to {approx}1000 candidate SLGs (with amplifications {mu} {approx}> 2) over the full H-ATLAS survey area. Applying HALOS to the H-ATLAS Science Demonstration Phase field ({approx_equal} 14.4 deg{sup 2}) we find 31 candidate SLGs, whose candidate lenses are identified in the VIKING near-infrared catalog. Using the available information on candidate sources and candidate lenses we tentatively estimate a {approx_equal} 72% purity of the sample. As expected, the purity decreases with decreasing flux density of the sources and with increasing angular separation between candidate sources and lenses. The redshift distribution of the candidate lensed sources is close to that reported for most previous surveys for lensed galaxies, while that of candidate lenses extends to redshifts substantially higher than found in the other surveys. The counts of candidate SLGs are also in good agreement with model predictions. Even though a key ingredient of the method is the deep near-infrared VIKING photometry, we show that H-ATLAS data alone allow the selection of a similarly deep sample of candidate SLGs with an efficiency close to 50%; a slightly lower surface density ({approx_equal} 1.45 deg{sup -2}) can be reached with a {approx}70% efficiency.
Application of the pM'-pCH diagrams in the determination of hydrolysis constants of the lanthanides
The pM'-pCH diagrams allowed to determine the saturation and non-saturation zones of Lu(OH)3 in solid phase and those were applied for determining the hydrolysis and lutetium solubility constants, using the radioactive isotope Lu-177. The first constant of hydrolysis was also determined by the potentiometric method in absence of solid phase. (Author)
Plasmonic effects associated with metal nanostructures are expected to hold the key to tailoring light emission/propagation and harvesting solar energy in materials including single crystal silicon which remains the backbone in the microelectronics and photovoltaics industries but unfortunately, lacks many functionalities needed for construction of advanced photonic and optoelectronics devices. Currently, silicon plasmonic structures are practically possible only in the configuration with metal nanoparticles or thin film arrays on a silicon surface. This does not enable one to exploit the full potential of plasmonics for optical engineering in silicon, because the plasmonic effects are dominant over a length of ∼50 nm, and the active device region typically lies below the surface much beyond this range. Here, we report on a novel method for the formation of silver nanoparticles embedded within a silicon crystal through metal gettering from a silver thin film deposited at the surface to nanocavities within the Si created by hydrogen ion implantation. The refractive index of the Ag-nanostructured layer is found to be 3–10% lower or higher than that of silicon for wavelengths below or beyond ∼815–900 nm, respectively. Around this wavelength range, the optical extinction values increase by a factor of 10–100 as opposed to the pure silicon case. Increasing the amount of gettered silver leads to an increased extinction as well as a redshift in wavelength position for the resonance. This resonance is attributed to the surface plasmon excitation of the resultant silver nanoparticles in silicon. Additionally, we show that the profiles for optical constants in silicon can be tailored by varying the position and number of nanocavity layers. Such silicon crystals with embedded metal nanostructures would offer novel functional base structures for applications in silicon photonics, optoelectronics, photovoltaics, and plasmonics
Akhter, Perveen [Department of Physics, State University of New York at Albany, Albany, New York 12222 (United States); Huang, Mengbing, E-mail: mhuang@albany.edu; Spratt, William; Kadakia, Nirag [College of Nanoscale Science and Engineering, State University of New York Polytechnic Institute, Albany, New York 12203 (United States); Amir, Faisal [Department of Physics, University of North Dakota, Grand Forks, North Dakota 58203 (United States)
2015-03-28
Plasmonic effects associated with metal nanostructures are expected to hold the key to tailoring light emission/propagation and harvesting solar energy in materials including single crystal silicon which remains the backbone in the microelectronics and photovoltaics industries but unfortunately, lacks many functionalities needed for construction of advanced photonic and optoelectronics devices. Currently, silicon plasmonic structures are practically possible only in the configuration with metal nanoparticles or thin film arrays on a silicon surface. This does not enable one to exploit the full potential of plasmonics for optical engineering in silicon, because the plasmonic effects are dominant over a length of ∼50 nm, and the active device region typically lies below the surface much beyond this range. Here, we report on a novel method for the formation of silver nanoparticles embedded within a silicon crystal through metal gettering from a silver thin film deposited at the surface to nanocavities within the Si created by hydrogen ion implantation. The refractive index of the Ag-nanostructured layer is found to be 3–10% lower or higher than that of silicon for wavelengths below or beyond ∼815–900 nm, respectively. Around this wavelength range, the optical extinction values increase by a factor of 10–100 as opposed to the pure silicon case. Increasing the amount of gettered silver leads to an increased extinction as well as a redshift in wavelength position for the resonance. This resonance is attributed to the surface plasmon excitation of the resultant silver nanoparticles in silicon. Additionally, we show that the profiles for optical constants in silicon can be tailored by varying the position and number of nanocavity layers. Such silicon crystals with embedded metal nanostructures would offer novel functional base structures for applications in silicon photonics, optoelectronics, photovoltaics, and plasmonics.
DISCOVERY OF A PROTOCLUSTER AT z {approx} 6
Toshikawa, Jun; Kashikawa, Nobunari; Shibuya, Takatoshi; Ishizaki, Yoshifumi [Department of Astronomy, School of Science, Graduate University for Advanced Studies, Mitaka, Tokyo 181-8588 (Japan); Ota, Kazuaki; Nagao, Tohru [Department of Astronomy, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Morokuma, Tomoki; Motohara, Kentaro [Institute of Astronomy, University of Tokyo, Mitaka, Tokyo 181-0015 (Japan); Hayashi, Masao [Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Jiang, Linhua; Egami, Eiichi [Steward Observatory, University of Arizona, 933 North Chery Avenue, Tucson, AZ 85721 (United States); Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Shimasaku, Kazuhiro, E-mail: jun.toshikawa@nao.ac.jp [Department of Astronomy, University of Tokyo, Hongo, Tokyo 113-0033 (Japan)
2012-05-10
We report the discovery of a protocluster at z {approx} 6 containing at least eight cluster member galaxies with spectroscopic confirmations in the wide-field image of the Subaru Deep Field (SDF). The overdensity of the protocluster is significant at the 6{sigma} level, based on the surface number density of i'-dropout galaxies. The overdense region covers {approx}6' Multiplication-Sign 6' (14 Mpc Multiplication-Sign 14 Mpc in comoving units at z = 6) and includes 30 i'-dropout galaxies. Follow-up spectroscopy revealed that 15 of these are real z {approx} 6 galaxies (5.7 < z < 6.3). Of these 15, 8 are clustering in a narrow redshift range ({Delta}z < 0.05 centered at z = 6.01), corresponding to a seven-fold increase in number density over the average in redshift space. We found no significant difference in the observed properties, such as Ly{alpha} luminosities and UV continuum magnitudes, between the eight protocluster members and the seven non-members. The velocity dispersion of the eight protocluster members is 647 {+-} 124 km s{sup -1}, which is about three times higher than that predicted by the standard cold dark matter model. This discrepancy could be attributed to the distinguishing three-dimensional distribution of the eight protocluster members. We discuss two possible explanations for this discrepancy: either the protocluster is already mature, with old galaxies at the center, or it is still immature and composed of three subgroups merging to become a larger cluster. In either case, this concentration of z = 6.01 galaxies in the SDF may be one of the first sites of formation of a galaxy cluster in the universe.
Calibrating UV Emissivity And Dust Absorption At z \\approx 3
Meurer, Gerhardt R.; Heckman, Timothy M.; Calzetti, Daniela
1998-01-01
We detail a technique for estimating the UV extinction and luminosity of UV selected galaxies using UV quantities alone. The technique is based on a tight correlation between the ratios of far infrared (FIR) to UV flux ratios and UV color for a sample of local starbursts. A simple empirical fit to this correlation can be used to estimate UV extinction as a function of color. This method is applied to a sample of Lyman-break systems selected from the HDF and having $z \\approx 3$. The resultant...
Wen Yingying [Department of Applied Chemistry, Yantai University, Yantai 264005 (China); Liu Huitao, E-mail: liuht-ytu@163.co [Department of Applied Chemistry, Yantai University, Yantai 264005 (China); Luan Feng; Gao Yuan [Department of Applied Chemistry, Yantai University, Yantai 264005 (China)
2011-01-15
Quantitative structure-activity relationship (QSAR) model was used to predict and explain binding constant (log K) determined by fluorescence quenching. This method allowed us to predict binding constants of a variety of compounds with human serum albumin (HSA) based on their structures alone. Stepwise multiple linear regression (MLR) and nonlinear radial basis function neural network (RBFNN) were performed to build the models. The statistical parameters provided by the MLR model (R{sup 2}=0.8521, RMS=0.2678) indicated satisfactory stability and predictive ability while the RBFNN predictive ability is somewhat superior (R{sup 2}=0.9245, RMS=0.1736). The proposed models were used to predict the binding constants of two bioactive components in traditional Chinese medicines (isoimperatorin and chrysophanol) whose experimental results were obtained in our laboratory and the predicted results were in good agreement with the experimental results. This QSAR approach can contribute to a better understanding of structural factors of the compounds responsible for drug-protein interactions, and can be useful in predicting the binding constants of other compounds. - Research Highlights: QSAR models for binding constants of some compounds to HSA were developed. The models provide a simple and straightforward way to predict binding constant. QSAR can give some insight into structural features related to binding behavior.
The method of homogeneous deformation has been applied to obtain theoretical expressions for the second order elastic (SOE) and third order elastic (TOE) constants of an ideal dhcp lattice. Two body interactions alone have been considered between the origin atom and six other kinds of atoms. The expressions obtained for the TOE constants have been employed to calculate the TOE constants for the metals Pr and Nd whose c to a ratio is very nearly equal to the ideal value. The Anderson-Grueneisen parameter for the two metals is calculated using their respective TOE constants. Anderson's theory is used to calculate the temperature dependence of the bulk modulus Bsub(S) for these two metals and is compared with the experimental values. The agreement is good. The low temperature limit of the volume Grueneisen function has been obtained using the respective theoretical TOE constants of these two metals. The variation of a/a0 and v/v0 with hydrostatic pressure up to 100 kbar has been calculated using the theoretical TOE constants and Thurston's extrapolation formula for both Pr and Nd. (Auth.)
Quantitative structure-activity relationship (QSAR) model was used to predict and explain binding constant (log K) determined by fluorescence quenching. This method allowed us to predict binding constants of a variety of compounds with human serum albumin (HSA) based on their structures alone. Stepwise multiple linear regression (MLR) and nonlinear radial basis function neural network (RBFNN) were performed to build the models. The statistical parameters provided by the MLR model (R2=0.8521, RMS=0.2678) indicated satisfactory stability and predictive ability while the RBFNN predictive ability is somewhat superior (R2=0.9245, RMS=0.1736). The proposed models were used to predict the binding constants of two bioactive components in traditional Chinese medicines (isoimperatorin and chrysophanol) whose experimental results were obtained in our laboratory and the predicted results were in good agreement with the experimental results. This QSAR approach can contribute to a better understanding of structural factors of the compounds responsible for drug-protein interactions, and can be useful in predicting the binding constants of other compounds. - Research Highlights: → QSAR models for binding constants of some compounds to HSA were developed. → The models provide a simple and straightforward way to predict binding constant. → QSAR can give some insight into structural features related to binding behavior.
Dyes with high dielectric constants
Langhals, Heinz
1988-01-01
The dielectric constants of perylene dyes, perylene-3,4: 9,10-tetracarboxylic bisimides, are reported. With aromatic substituents, dielectric constants up to 110 are obtained. With polymeric dyes, the dielectric constants rise to 260. Mechanisms and applications are discussed.
Two devices based on the study of the response of a disc excited by current pulses are described. The piezoelectric constant, the permittivity and the coupling factor are measured with the first one; the receiving transducer sensitivity as a function of the ultrasonic wave frequency is obtained with the other one
Šebestová, I.; Vejchodský, Tomáš
2014-01-01
Roč. 52, č. 1 (2014), s. 308-329. ISSN 0036-1429 Institutional support: RVO:67985840 Keywords : bounds on spectrum * a posteriori error estimate * optimal constant Subject RIV: BA - General Mathematics Impact factor: 1.788, year: 2014 http://epubs.siam.org/doi/abs/10.1137/13091467X
Stadnik, Y V
2015-01-01
We outline new laser interferometer measurements to search for variation of the electromagnetic fine-structure constant $\\alpha$ and particle masses (including a non-zero photon mass). We propose a strontium optical lattice clock -- silicon single-crystal cavity interferometer as a novel small-scale platform for these new measurements. Multiple passages of a light beam inside an interferometer enhance the effects due to variation of the fundamental constants by the mean number of passages ($N_{\\textrm{eff}} \\sim 10^2$ for a large-scale gravitational-wave detector, such as LIGO, Virgo, GEO600 or TAMA300, while $N_{\\textrm{eff}} \\sim 10^5$ for a strontium clock -- silicon cavity interferometer). Our proposed laser interferometer measurements may be implemented as an extremely precise tool in the direct detection of scalar dark matter that forms an oscillating classical field or topological defects.
This thesis looks into some qualitative properties, of dynamical systems occurring as ordinary differential equations. Essential information about the structure of the solution can be obtained without explicitly solving a linear system of differential equations with constant coefficients. This can be achieved by decomposing the operator of such a system into a semisimple and a nilpotent part. Fundamental theorems, concerning the existence of the solutions are discussed as well as the problem of stability of equilibrium points in dynamical systems (Liapunov's theorem). Gradient systems, special forms of dynamical systems, have particular properties that simplify the analysis of their flow. Finally, by applying the theory of dynamical systems to the Boltzmann equation with constant collision frequencies an investigation of equilibrium points is carried out. A mixture of three gases consisting of particles that interact through different collision mechanisms serves as the physical model. (Suda)
Vasseur, Guy; Rousseau-Gueutin, Pauline; de Marsily, Ghislain
2015-08-01
Analytical formulae are proposed to describe the first-order temporal evolution of the head in large groundwater systems (such as those found in North Africa or eastern Australia) that are subjected to drastic modifications of their recharge conditions (such as those in Pleistocene and Holocene times). The mathematical model is based on the hydrodynamics of a mixed-aquifer system composed of a confined aquifer connected to an unconfined one with a large storage capacity. The transient behaviour of the head following a sudden change of recharge conditions is computed with Laplace transforms for linear one-dimensional and cylindrical geometries. This transient evolution closely follows an exponential trend exp(- t/ τ). The time constant τ is expressed analytically as a function of the various parameters characterizing the system. In many commonly occurring situations, τ depends on only four parameters: the width a c of the main confined aquifer, its transmissivity T c, the integrated storage situated upstream in the unconfined aquifer M = S u a u, and a curvature parameter accounting for convergence/divergence effects. This model is applied to the natural decay of large aquifer basins of the Sahara and Australia following the end of the mid-Holocene humid period. The observed persistence of the resource is discussed on the basis of the time constant estimated with the system parameters. This comparison confirms the role of the upstream water reserve, which is modelled as an unconfined aquifer, and highlights the significant increase of the time constant in case of converging flow.
Wei Xu
2015-03-01
Full Text Available Based on entropy relations, we derive the thermodynamic bound for entropy and the area of horizons for a Schwarzschild–dS black hole, including the event horizon, Cauchy horizon, and negative horizon (i.e., the horizon with negative value, which are all geometrically bound and comprised by the cosmological radius. We consider the first derivative of the entropy relations to obtain the first law of thermodynamics for all horizons. We also obtain the Smarr relation for the horizons using the scaling discussion. For the thermodynamics of all horizons, the cosmological constant is treated as a thermodynamic variable. In particular, the thermodynamics of the negative horizon are defined well in the r<0 side of space–time. This formula appears to be valid for three-horizon black holes. We also generalize the discussion to thermodynamics for the event horizon and Cauchy horizon of Gauss–Bonnet charged flat black holes because the Gauss–Bonnet coupling constant is also considered to be thermodynamic variable. These results provide further insights into the crucial role played by the entropy relations of multi-horizons in black hole thermodynamics as well as improving our understanding of entropy at the microscopic level.
ZVONIMIR J. SUTUROVIC
2002-03-01
Full Text Available The trace amounts of lead in extraction glassware products were determined by potentiometric stripping analysis with constant inverse current in the analytic step (PSA-iR, an electrochemical technique of high sensitivity and selectivity. This paper deals with an investigation which was directed to the effect of a great number of factors on the results of PSA-iR, of lead in glassware, such as the mercury time electrodeposition, the electrolysis potential, the solution stirring rate and the constant inverse current. Linearity of the lead analytical signal was achieved within the range of mass concentrations from 2.5 mg/dm3 to 4.5 mg/dm3. A detection limit of 0.64 mg/dm3 was obtained, with a reproducibility of 4.14 % expressed as the coefficient of variation. The analyses were carried out using a computerized stripping analyzer of domestic design and manufacture (Faculty of Technology, Novi Sad and Elektrouniverzal, Leskovac. The accuracy of the method was confirmed by parallel analyses using flameless atomic absorption spectrophotometry as the reference method.
Mays, Ebony Lynn
Integrated circuit (IC) manufacturers increasingly need new high dielectric constant (epsilon) materials for gate stacks to maintain the pace of developing faster, higher capacity CMOS and DRAM devices. Identification of new high-epsilon materials that can be integrated into current manufacturing processes is critical to the continued development of IC devices. Using magnetron sputtering and a compositional spread approach, a key composition of amorphous zirconium tin titanate (a-ZTT) films was found to exhibit a dielectric constant from 50 to 70 and leakage currents from 10-9 to 10 -7 A/cm2 at 1 MV/cm. Chemical Vapor Deposition (CVD) is an attractive technique for deposition of ZTT films because it offers several advantages over sputter deposition. Many processing parameters can be controlled and varied in the optimization of the film microstructure and composition. In addition, high-epsilon phases of the compounds might be achieved at low temperatures by using plasma enhancement of the CVD process. Alternatively, use of ozone or other oxidants may allow complete oxidation of metal precursors at lower processing temperatures. The following discussion details the construction and modification of a CVD reactor for the deposition of ZTT thin films. In addition, characterization of a precursor "cocktail"---a solution containing all the metal components of the film---for the deposition of ZTT thin films is discussed. Discussion includes experiments characterizing the dielectric and device properties (dielectric constant, dielectric loss, capacitance, and leakage current) of CVD-grown, a-ZTT thin films using the precursor "cocktail". The importance of the relationship of the cation ratio in the precursor that is translated to the film and its relationship to the dielectric properties are shown. The device properties of ZTT films were measured using Capacitance-Voltage (CV) and Current-Voltage (IV) analysis, while dielectric properties were explored using Impedance
Sedmák, P.; Seiner, Hanuš; Sedlák, Petr; Landa, Michal; Mušálek, Radek; Matějíček, Jiří
2013-01-01
Roč. 232, October (2013), s. 747-757. ISSN 0257-8972 R&D Projects: GA ČR(CZ) GA101/09/0702; GA ČR GA13-13616S; GA ČR(CZ) GPP108/12/P552; GA ČR(CZ) GAP108/12/1872 Grant ostatní: Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100761203 Institutional support: RVO:61388998 ; RVO:61389021 Keywords : plasma-sprayed coatings * elastic constants * resonant ultrasound spectroscopy * internal friction * anisotropy Subject RIV: BI - Acoustics; BI - Acoustics (UFP-V) Impact factor: 2.199, year: 2013 http://www.sciencedirect.com/science/article/pii/S0257897213006063
Kompany-Zareh, Mohsen; Khoshkam, Maryam
2008-05-01
To determine the rate constants for the second order consecutive reactions of the form U + V -(k1)--> W -(k2)--> P, a number of chemometrics and hard modeling-based methods are described. The absorption spectroscopic data from the reaction were utilized for performing the analysis. Concentrations and extinctions of components were comparable, and all of them were absorbing species. The number of steps in the reaction was less than the number of absorbing species, which resulted in a rank-deficient response matrix. This can cause difficulties for some of the methods described in the literature. The standard MATLAB functions were used for determining the solutions of the differential equations as well as for finding the optimal rate constants to describe the kinetic profiles. The available knowledge about the system determines the approaches described in this paper. The knowledge includes the spectra of reactants and products, the initial concentrations, and the exact kinetics. Some of this information is sometimes not available or is hard to estimate. Multiple linear regression for fitting the kinetic parameters to the obtained concentration profiles, rank augmentation using multiple batch runs, a mixed spectral approach which treats the reaction using a pseudo species concept, and principal components regression are the four groups of methods discussed in this study. In one of the simulated datasets the spectra are quite different, and in the other one the spectra of one reactant and of the product share a high degree of overlap. Instrumental noise, sampling error are the sources of error considered. Our aim was the investigation of the relative merits of each method. PMID:18469471
Application of PC-ANN to Acidity Constant Prediction of Various Phenols and Benzoic Acids in Water
HABIBI-YANGJEH Aziz; ESMAILIAN Mahdi
2008-01-01
Principal component regression(PCR)and principal component-artificial neural network(PC-ANN)models were applied to prediction of the acidity constant for various benzoic acids and phenols(242 compounds)in water at 25℃.A large number of theoretical descriptors were calculated for each molecule.The first fifty principal components(PC)were found to explain more than 95% of variances in the original data matrix.From the pool of these PC's.the eigenvalue ranking method was employed to select the best set of PC for PCR and PC-ANN models.The PC-ANN model with architecture 47-20-1 was generated using 47 principal components as inputs and its output is pKa.For evaluation of the predictive power of the PeR and PC-ANN models,pKa values of 37 compounds in the prediction set were calculated.Mean percentage deviation (MPD)for PCR and PC-ANN models are 18.45 and 0.6448,respectively.These improvements are due to the fact that the PKa of the compounds demonstrate non-linear correlations with the principal components.Comparison of the results obtained by the models reveals superiority of the PC-ANN model relative to the PCR model.
Liesbeth van Oeffelen; Eveline Peeters; Phu Nguyen Le Minh; Daniël Charlier
2014-01-01
Current software applications for densitometric analysis, such as ImageJ, QuantityOne (BioRad) and the Intelligent or Advanced Quantifier (Bio Image) do not allow to take the non-linearity of autoradiographic films into account during calibration. As a consequence, quantification of autoradiographs is often regarded as problematic, and phosphorimaging is the preferred alternative. However, the non-linear behaviour of autoradiographs can be described mathematically, so it can be accounted for....
A geochronological study of the Guanabara Bay (Rio de Janeiro, Brazil) based on 210Pb dating technique to determine sedimentation rates and using the Constant Rate of Supply model (CRS) is presented in this work. Sediment samples were collected from river-head of Estrela, Sao Joao de Meriti, Guapimirim, Guaxindiba e Imbuacu. A low energy gamma spectrometry (210Pb, samples taken from the Estrela and Sao Joao de Meriti rivers. Radiochemical method was applied to determine the amount of 210Pb in samples collected near Guapimirim, Guaxindiba and Imbuacu Rivers. Atomic absorption spectrometry with air-acetylene flame technique was used to determine the amount of copper in all these samples. Experimental data shown the following variation in the concentration levels of copper and 210Pb: (i) copper; from 2.5 μg/g to 37.1 μg/g (Imbuacu River); from 3.6 to 228.1 μg/g (Estrela River); from 11.6 to 73.4 μg/g (Guapimirim River); from 12.0 to 52.9 μg/g (Guaxindiba River) and from 90.8 to to 237.7 μg/g (Sao Joao de Meriti River), (ti) 210Pb; from 2.0 Bq/kg to 27.0 Bq/kg (Imbuacu River); from 25.2 to 136.6 Bq/kg (Estrela River); from 40.0 to 90.0 Bq/kg (Sao Joao de Meriti River); from 7.0 to 70.0 Bq/kg (Guapimirim River); from 10.0 to 48.0 Bq/kg (Guaxindiba River). The sedimentation rates ranged from 0.30 cm/y in the Imbuacu River for a depth below of 35 cm to 1.3 cm/y for 0-30 cm depth in Guaxindiba River. It was concluded that the experimental data found in this work are consistent with those published in the scientific literature and that they can be predicted by the CRS model. (author)
Cosmological Constant, Fine Structure Constant and Beyond
Wei, Hao; Zou, Xiao-Bo; Li, Hong-Yu; Xue, Dong-Ze
2016-01-01
In this work, we consider the cosmological constant model $\\Lambda\\propto\\alpha^{-6}$, which is well motivated from three independent approaches. As is well known, the evidence of varying fine structure constant $\\alpha$ was found in 1998. If $\\Lambda\\propto\\alpha^{-6}$ is right, it means that the cosmological constant $\\Lambda$ should be also varying. In this work, we try to develop a suitable framework to model this varying cosmological constant $\\Lambda\\propto\\alpha^{-6}$, in which we view...
Allen, Ronald J; Engelke, Philip D
2015-01-01
We report the first results from a survey for 1665, 1667, and 1720 MHz OH emission over a small region of the Outer Galaxy centered at $l \\approx 105.0\\deg , b \\approx +1.0\\deg$ . This sparse, high-sensitivity survey ($\\Delta Ta \\approx \\Delta Tmb \\approx 3.0 - 3.5$ mK rms in 0.55 km/s channels), was carried out as a pilot project with the Green Bank Telescope (GBT, FWHM $\\approx 7.6'$) on a 3 X 9 grid at $0.5\\deg$ spacing. The pointings chosen correspond with those of the existing $^{12}$CO(1-0) CfA survey of the Galaxy (FWHM $\\approx 8.4'$). With 2-hr integrations, 1667 MHz OH emission was detected with the GBT at $\\gtrsim 21$ of the 27 survey positions ($\\geq 78\\%$ ), confirming the ubiquity of molecular gas in the ISM as traced by this spectral line. With few exceptions, the main OH lines at 1665 and 1667 MHz appear in the ratio of 5:9 characteristic of LTE at our sensitivity levels. No OH absorption features are recorded in the area of the present survey, in agreement with the low levels of continuum bac...
Jincai Wang
2007-01-01
We introduce the \\(J\\)-convexity constants on Banach spaces and give some properties of the constants. We give the relations between the \\(J\\)-convexity constants and the \\(n\\)-th von Neumann-Jordan constants. Using the quantitative indices we estimate the value of \\(J\\)-convexity constants in Orlicz spaces.
Nicas, Mark
2016-07-01
The near field/far field (NF/FF) model is a contaminant dispersion construct that permits making airborne contaminant exposure estimates for an individual located close to an emission source. In the present analysis, chemical emission involves a constant mass rate of chemical application to surfaces, denoted I (mg/min), and an exponentially decreasing rate of emission of the chemical from the surfaces with rate constant α (min(-1)). The time-dependent emission rate function is: G(t), mg/min = I - I exp(- αt), where time t is in minutes. The exact time-dependent equations for the contaminant concentration in the NF and the FF are presented. These equations are used to revise a previous analysis of a study in which a penetrant liquid containing benzene was applied to parts on a work table in a test room. The previous analysis assumed that the benzene was applied as a bolus at the start of a 15-min use period, whereas the present analysis assumes the same total benzene mass was applied at a uniform rate over the 15-min use period, but with the same evaporation rate constant α. The new G(t) function leads to a lower 15-min time weighted average NF benzene concentration that better matches the experimental data. It is also shown that the exact equation for the NF concentration is well approximated by combining two well-mixed single-zone equations. The approximation method is mathematically simpler and obviates the need to derive the exact NF equation. PMID:26861562
Capacitive Cells for Dielectric Constant Measurement
Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco
2015-01-01
A simple capacitive cell for dielectric constant measurement in liquids is presented. As an illustrative application, the cell is used for measuring the degradation of overheated edible oil through the evaluation of their dielectric constant.
THROUGH THE LOOKING GLASS: BRIGHT, HIGHLY MAGNIFIED GALAXY CANDIDATES AT z {approx} 7 BEHIND A1703
Bradley, L. D.; Coe, D. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bouwens, R. J.; Smit, R. [Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden (Netherlands); Zitrin, A. [School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); Ford, H. C.; Zheng, W. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Illingworth, G. D. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California Santa Cruz, Santa Cruz, CA 95064 (United States); Benitez, N. [Instituto de Astrofisica de Andalucia (CSIC), C/Camino Bajo de Huetor 24, Granada 18008 (Spain); Broadhurst, T. J. [Department of Theoretical Physics, University of Basque Country UPV/EHU, Leioa (Spain)
2012-03-01
We report the discovery of seven strongly lensed Lyman-break galaxy (LBG) candidates at z {approx} 7 detected in Hubble Space Telescope Wide Field Camera 3 (WFC3) imaging of A1703. The brightest candidate, called A1703-zD1, has an observed (lensed) magnitude of 24.0 AB (26{sigma}) in the WFC3/IR F160W band, making it 0.2 mag brighter than the z{sub 850}-dropout candidate recently reported behind the Bullet Cluster and 0.7 mag brighter than the previously brightest known z {approx} 7.6 galaxy, A1689-zD1. With a cluster magnification of {approx}9, this source has an intrinsic magnitude of H{sub 160} = 26.4 AB, a strong z{sub 850} - J{sub 125} break of 1.7 mag, and a photometric redshift of z {approx} 6.7. Additionally, we find six other bright LBG candidates with H{sub 160}-band magnitudes of 24.9-26.4, photometric redshifts z {approx} 6.4 - 8.8, and magnifications {mu} {approx} 3-40. Stellar population fits to the Advanced Camera for Surveys, WFC3/IR, and Spitzer/Infrared Array Camera data for A1703-zD1 and A1703-zD4 yield stellar masses (0.7 - 3.0) Multiplication-Sign 10{sup 9} M{sub Sun }, stellar ages 5-180 Myr, and star formation rates {approx}7.8 M{sub Sun} yr{sup -1}, and low reddening with A{sub V} {<=} 0.7. The source-plane reconstruction of the exceptionally bright candidate A1703-zD1 exhibits an extended structure, spanning {approx}4 kpc in the z {approx} 6.7 source plane, and shows three resolved star-forming knots of radius r {approx} 0.4 kpc.
Cosmological Hubble constant and nuclear Hubble constant
The evolution of the Universe after the Big Bang and the evolution of the dense and highly excited nuclear matter formed by relativistic nuclear collisions are investigated and compared. Values of the Hubble constants for cosmological and nuclear processes are obtained. For nucleus-nucleus collisions at high energies the nuclear Hubble constant is obtained in the frame of different models involving the hydrodynamic flow of the nuclear matter. Significant difference in the values of the two Hubble constant - cosmological and nuclear - is observed
Constant Communities in Complex Networks
Chakraborty, Tanmoy; Ganguly, Niloy; Bhowmick, Sanjukta; Mukherjee, Animesh
2013-01-01
Identifying community structure is a fundamental problem in network analysis. Most community detection algorithms are based on optimizing a combinatorial parameter, for example modularity. This optimization is generally NP-hard, thus merely changing the vertex order can alter their assignments to the community. However, there has been very less study on how vertex ordering influences the results of the community detection algorithms. Here we identify and study the properties of invariant groups of vertices (constant communities) whose assignment to communities are, quite remarkably, not affected by vertex ordering. The percentage of constant communities can vary across different applications and based on empirical results we propose metrics to evaluate these communities. Using constant communities as a pre-processing step, one can significantly reduce the variation of the results. Finally, we present a case study on phoneme network and illustrate that constant communities, quite strikingly, form the core func...
Ion exchange equilibrium constants
Marcus, Y
2013-01-01
Ion Exchange Equilibrium Constants focuses on the test-compilation of equilibrium constants for ion exchange reactions. The book first underscores the scope of the compilation, equilibrium constants, symbols used, and arrangement of the table. The manuscript then presents the table of equilibrium constants, including polystyrene sulfonate cation exchanger, polyacrylate cation exchanger, polymethacrylate cation exchanger, polysterene phosphate cation exchanger, and zirconium phosphate cation exchanger. The text highlights zirconium oxide anion exchanger, zeolite type 13Y cation exchanger, and
Siddiqua, Poppy; Hadi, Walid A.; Salhotra, Amith K.; O' Leary, Stephen K., E-mail: stephen.oleary@ubc.ca [School of Engineering, The University of British Columbia, 3333 University Way, Kelowna, British Columbia V1V 1V7 (Canada); Shur, Michael S. [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3590 (United States)
2015-03-28
Within the framework of an ensemble semi-classical three-valley Monte Carlo electron transport simulation approach, we critically contrast the nature of the electron transport that occurs within the wurtzite and zinc-blende phases of indium nitride in response to the application of a constant and uniform electric field. We use the electron energy distribution and its relationship with the electron transport characteristics in order to pursue this analysis. For the case of zinc-blende indium nitride, only a peak corresponding to the electrons within the lowest energy conduction band valley is observed, this peak being seen to broaden and shift to higher energies in response to increases in the applied electric field strength, negligible amounts of upper energy conduction band valley occupancy being observed. In contrast, for the case of wurtzite indium nitride, in addition to the aforementioned lowest energy conduction band valley peak in the electron energy distribution, and its broadening and shifting to higher energies in response to increases in the applied electric field strength, beyond a certain critical electric field strength, 30 kV/cm for the case of this particular material, upper energy conduction band valley occupancy is observed, this occupancy being further enhanced in response to further increases in the applied electric field strength. Reasons for these results are provided. The potential for device consequences is then commented upon.
Within the framework of an ensemble semi-classical three-valley Monte Carlo electron transport simulation approach, we critically contrast the nature of the electron transport that occurs within the wurtzite and zinc-blende phases of indium nitride in response to the application of a constant and uniform electric field. We use the electron energy distribution and its relationship with the electron transport characteristics in order to pursue this analysis. For the case of zinc-blende indium nitride, only a peak corresponding to the electrons within the lowest energy conduction band valley is observed, this peak being seen to broaden and shift to higher energies in response to increases in the applied electric field strength, negligible amounts of upper energy conduction band valley occupancy being observed. In contrast, for the case of wurtzite indium nitride, in addition to the aforementioned lowest energy conduction band valley peak in the electron energy distribution, and its broadening and shifting to higher energies in response to increases in the applied electric field strength, beyond a certain critical electric field strength, 30 kV/cm for the case of this particular material, upper energy conduction band valley occupancy is observed, this occupancy being further enhanced in response to further increases in the applied electric field strength. Reasons for these results are provided. The potential for device consequences is then commented upon
Cosmological Constant, Fine Structure Constant and Beyond
Wei, Hao; Li, Hong-Yu; Xue, Dong-Ze
2016-01-01
In this work, we consider the cosmological constant model $\\Lambda\\propto\\alpha^{-6}$, which is well motivated from three independent approaches. As is well known, the evidence of varying fine structure constant $\\alpha$ was found in 1998. If $\\Lambda\\propto\\alpha^{-6}$ is right, it means that the cosmological constant $\\Lambda$ should be also varying. In this work, we try to develop a suitable framework to model this varying cosmological constant $\\Lambda\\propto\\alpha^{-6}$, in which we view it from an interacting vacuum energy perspective. We propose two types of models to describe the evolutions of $\\Lambda$ and $\\alpha$. Then, we consider the observational constraints on these models, by using the 293 $\\Delta\\alpha/\\alpha$ data from the absorption systems in the spectra of distant quasars, and the data of type Ia supernovae (SNIa), cosmic microwave background (CMB), baryon acoustic oscillation (BAO). We find that the model parameters can be tightly constrained to the narrow ranges of ${\\cal O}(10^{-5})$ t...
Physics without physical constants
Following the general principles of both Newton's mechanics and Maxwell's electrodynamics, a new approach to basic equations of physics is presented. The new basic equations express fundamental laws of physics and are free from any physical constants. The necessary constants appear only through some kind of constitutive relations and by considering special solutions of the basic equations. The presented approach admits a new interpretation of fundamental physical constants, such as the Planck gravitational ones. 4 refs. (author)
Papp, P.; Matejčík, Š.; Mach, P.; Urban, J.; Paidarová, I.; Horáček, J.
2013-06-01
The method of analytic continuation in the coupling constant (ACCC) in combination with use of the statistical Padé approximation is applied to the determination of resonance energy and width of some amino acids and formic acid dimer. Standard quantum chemistry codes provide accurate data which can be used for analytic continuation in the coupling constant to obtain the resonance energy and width of organic molecules with a good accuracy. The obtained results are compared with the existing experimental ones.
Varying fine-structure and gravitational constants
A simple relation between the time-dependent fine-structure and gravitational constants of alpha/alpha2 approx G/G is derived from the hypothesis that both of these fundamental constants are related to the more fundamental length scale of nature as in he unified pregauge and pregeometric theory of all fundamental forces. From the latest observation of alpha/alpha = (-1.91 ± 0.54) centre dot 10-15yr-1 by Webb et al., it leads to the prediction of G/G = (-0.154 ± 0.044) centre dot 10-12yr-1, which is not only consistent with the most precise limit of G/G = (-0.6 ± 2.0) centre dot 10-12yr-1 by Thorsett but also feasible for future experimental tests
Carroll Sean M.
2001-01-01
Full Text Available This is a review of the physics and cosmology of the cosmological constant. Focusing on recent developments, I present a pedagogical overview of cosmology in the presence of a cosmological constant, observational constraints on its magnitude, and the physics of a small (and potentially nonzero vacuum energy.
Helgason, Kari; Kashlinsky, Alexander
2012-01-01
Reconstructing the Gamma-Ray Photon Optical Depth of the Universe To Z Approx. 4fFrom Multiwavelength Galaxy Survey Data We reconstruct the gamma-ray opacity of the universe out to z approx. photons already at z approx. < 0.2 and reaching tau approx 10 at z = 1. Comparing with the currently available Fermi/LAT gamma-ray burst and blazar data shows that there is room for significant emissions originating in the first stars era.
THE BIMODAL METALLICITY DISTRIBUTION OF THE COOL CIRCUMGALACTIC MEDIUM AT z {approx}< 1
Lehner, N.; Howk, J. C. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Tripp, T. M. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Tumlinson, J.; Thom, C.; Fox, A. J. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Prochaska, J. X.; Werk, J. K. [UCO/Lick Observatory, University of California, Santa Cruz, CA (United States); O' Meara, J. M. [Department of Physics, Saint Michael' s College, Vermont, One Winooski Park, Colchester, VT 05439 (United States); Ribaudo, J. [Department of Physics, Utica College, 1600 Burrstone Road, Utica, New York 13502 (United States)
2013-06-20
We assess the metal content of the cool ({approx}10{sup 4} K) circumgalactic medium (CGM) about galaxies at z {approx}< 1 using an H I-selected sample of 28 Lyman limit systems (LLS; defined here as absorbers with 16.2 {approx}< log N{sub H{sub I}} {approx}< 18.5) observed in absorption against background QSOs by the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The N{sub H{sub I}} selection avoids metallicity biases inherent in many previous studies of the low-redshift CGM. We compare the column densities of weakly ionized metal species (e.g., O II, Si II, Mg II) to N{sub H{sub I}} in the strongest H I component of each absorber. We find that the metallicity distribution of the LLS (and hence the cool CGM) is bimodal with metal-poor and metal-rich branches peaking at [X/H] {approx_equal} -1.6 and -0.3 (or about 2.5% and 50% solar metallicities). The cool CGM probed by these LLS is predominantly ionized. The metal-rich branch of the population likely traces winds, recycled outflows, and tidally stripped gas; the metal-poor branch has properties consistent with cold accretion streams thought to be a major source of fresh gas for star forming galaxies. Both branches have a nearly equal number of absorbers. Our results thus demonstrate there is a significant mass of previously undiscovered cold metal-poor gas and confirm the presence of metal enriched gas in the CGM of z {approx}< 1 galaxies.
Decay Constants of Beauty Mesons from QCD Sum Rules
Lucha, Wolfgang; Simula, Silvano
2014-01-01
Our recently completed analysis of the decay constants of both pseudoscalar and vector beauty mesons reveals that in the bottom-quark sector two specific features of the sum-rule predictions show up: (i) For the input value of the bottom-quark mass in the $\\overline{\\rm MS}$ scheme $\\overline{m}_b(\\overline{m}_b)\\approx4.18\\;\\mbox{GeV},$ the sum-rule result $f_B\\approx210$-$220\\;\\mbox{MeV}$ for the $B$ meson decay constant is substantially larger than the recent lattice-QCD finding $f_B\\approx190\\;\\mbox{MeV}.$ Requiring QCD sum rules to reproduce the lattice-QCD value of $f_B$ yields a significantly larger $b$-quark mass: $\\overline{m}_b(\\overline{m}_b)=4.247\\;\\mbox{GeV}.$ (ii) Whereas QCD sum-rule predictions for the charmed-meson decay constants $f_D,$ $f_{D_s},$ $f_{D^*}$ and $f_{D_s^*}$ are practically independent of the choice of renormalization scale, in the beauty sector the results for the decay constants - and especially for the ratio $f_{B^*}/f_B$ - prove to be very sensitive to the specific scale s...
We have carried out investigations aimed at understanding the mechanism responsible for a water contact angle increase of up to ten degrees and a decrease in dielectric constant in silicon modified hydrogenated amorphous carbon films compared to unmodified hydrogenated amorphous carbon films. Our investigations based on surface chemical constituent analysis using Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), SIMS, FTIR, contact angle / surface energy measurements and spectroscopic ellipsometry suggests the presence of hydrophobic chemical entities on the surface of the films. This observation is consistent with earlier theoretical plasma chemistry predictions and observed Raman peak shifts in the films. These surface hydrophobic entities also have a lower polarizability than the bonds in the un-modified films thereby reducing the dielectric constant of the silicon modified films measured by spectroscopic ellipsometry. Ellipsometric dielectric constant measurement is directly related to the surface energy through Hamaker's constant. Our current finding is expected to be of benefit to understanding stiction, friction and lubrication in areas that range from nano-tribology to microfluidics.
Chaiken, J; Goodisman, J; Kornilov, O
2015-07-01
The Smoluchowski equations provide a rigorous and efficient means for including multiple kinetic pathways when modeling coalescence growth systems. Originally written for a constant temperature and volume system, the equations must be modified if temperature and pressure vary during the coalescence time. In this paper, the equations are generalized, and adaptations appropriate to the situation presented by supersonic nozzle beam expansions are described. Given rate constants for all the cluster-cluster reactions, solution of the Smoluchowski equations would yield the abundances of clusters of all sizes at all times. This is unlikely, but we show that if these rate constants scale with the sizes of the reacting partners, the asymptotic (large size and large time) form of the cluster size distribution can be predicted. Experimentally determined distributions for He fit the predicted asymptotic distribution very well. Deviations between predicted and observed distributions allow identification of special cluster sizes that is, magic numbers. Furthermore, fitting an observed distribution to the theoretical form yields the base agglomeration cross section, from which all cluster-cluster rate constants may be obtained by scaling. Comparing the base cross section to measures of size and reactivity gives information about the coalescence process. PMID:26067086
INTERMEDIATE-MASS HOT CORES AT {approx}500 AU: DISKS OR OUTFLOWS?
Palau, Aina; Girart, Josep M. [Institut de Ciencies de l' Espai (CSIC-IEEC), Campus UAB-Facultat de Ciencies, Torre C5-parell 2, 08193 Bellaterra, Catalunya (Spain); Fuente, Asuncion; Alonso-Albi, Tomas [Observatorio Astronomico Nacional, P.O. Box 112, 28803 Alcala de Henares, Madrid (Spain); Fontani, Francesco; Sanchez-Monge, Alvaro [Osservatorio Astrofisico di Arcetri, INAF, Largo E. Fermi 5, 50125 Firenze (Italy); Boissier, Jeremie [Istituto di Radioastronomia, INAF, Via Gobetti 101, Bologna (Italy); Pietu, Vincent; Neri, Roberto [IRAM, 300 Rue de la piscine, 38406 Saint Martin d' Heres (France); Busquet, Gemma [Istituto di Fisica dello Spazio Interplanetario, INAF, Area di Recerca di Tor Vergata, Via Fosso Cavaliere 100, 00133 Roma (Italy); Estalella, Robert [Departament d' Astronomia i Meteorologia (IEEC-UB), Institut Ciencies Cosmos, Universitat Barcelona, Marti Franques 1, 08028 Barcelona (Spain); Zapata, Luis A. [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, P.O. Box 3-72, 58090 Morelia, Michoacan (Mexico); Zhang, Qizhou; Ho, Paul T. P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Audard, Marc, E-mail: palau@ieec.uab.es [Geneva Observatory, University of Geneva, Ch. des Maillettes 51, 1290 Versoix (Switzerland)
2011-12-20
Observations with the Plateau de Bure Interferometer in the most extended configuration toward two intermediate-mass star-forming regions, IRAS 22198+6336 and AFGL 5142, reveal the presence of several complex organic molecules at {approx}500 AU scales, confirming the presence of hot cores in both regions. The hot cores are not rich in CN-bearing molecules, as often seen in massive hot cores, and are mainly traced by CH{sub 3}CH{sub 2}OH, (CH{sub 2}OH){sub 2}, CH{sub 3}COCH{sub 3}, and CH{sub 3}OH, with, additionally, CH{sub 3}CHO, CH{sub 3}OD, and HCOOD for IRAS 22198+6336, and C{sub 6}H and O{sup 13}CS for AFGL 5142. The emission of complex molecules is resolved down to sizes of {approx}300 and {approx}600 AU, for IRAS 22198+6336 and AFGL 5142, respectively, and most likely is tracing protostellar disks rather than flattened envelopes or toroids as is usually found. This is especially clear for the case of IRAS 22198+6336, where we detect a velocity gradient for all the mapped molecules perpendicular to the most chemically rich outflow of the region, yielding a dynamic mass {approx}> 4 M{sub Sun }. As for AFGL 5142, the hot core emission is resolved into two elongated cores separated {approx}1800 AU. A detailed comparison of the complex molecule peaks to the new CO (2-1) data and H{sub 2}O maser data from the literature suggests also that for AFGL 5142 the complex molecules are mainly associated with disks, except for a faint and extended molecular emission found to the west, which is possibly produced in the interface between one of the outflows and the dense surrounding gas.
Bassenne, Maxime; Urzay, Javier; Park, George I.; Moin, Parviz
2016-03-01
This study investigates control-based forcing methods for incompressible homogeneous-isotropic turbulence forced linearly in physical space which result in constant turbulent kinetic energy, constant turbulent dissipation (also constant enstrophy), or a combination of the two based on a least-squares error minimization. The methods consist of proportional controllers embedded in the forcing coefficients. During the transient, the controllers adjust the forcing coefficients such that the controlled quantity achieves very early a minimal relative error with respect to its target stationary value. Comparisons of these forcing methods are made with the non-controlled approaches of Rosales and Meneveau ["Linear forcing in numerical simulations of isotropic turbulence: Physical space implementations and convergence properties," Phys. Fluids 17, 095106 (2005)] and Carroll and Blanquart ["A proposed modification to Lundgren's physical space velocity forcing method for isotropic turbulence," Phys. Fluids 25, 105114 (2013)], using direct numerical simulations (DNS) and large-eddy simulations (LES). The results indicate that the proposed constant-energetics forcing methods shorten the transient period from a user-defined artificial flow field to Navier-Stokes turbulence while maintaining steadier statistics. Additionally, the proposed method of constant kinetic-energy forcing behaves more robustly in coarse LES when initial conditions are employed that favor the occurrence of subgrid-scale backscatter, whereas the other approaches fail to provide physical turbulent flow fields. For illustration, the proposed forcing methods are applied to dilute particle-laden homogeneous-isotropic turbulent flows; the results serve to highlight the influences of the forcing strategies on the disperse-phase statistics.
Leff, P.; Martin, G R; Morse, J. M.
1985-01-01
The operational model of agonism (Black & Leff, 1983) has been used to analyse comparatively functional antagonism and irreversible antagonism as methods for estimating agonist dissociation constants (KAs). A general condition is established in terms of the model parameters which defines the type of experimental interventions at the receptor and the post-receptor level that allow valid KA estimation. It is shown that functional antagonism and other post-receptor interventions may produce chan...
The value of transfer function of unorganic-crystal, CeF3, is measured by the method of pluse of laser radiation. It is applied that the mathematics convolution of neutron-decay exponential constant on zero power assembly is processed. At the same time, the effect is assumed that the dual-exponential type transfer function deals with the value of neutron-decay on zero power assembly in the convolution of input function. (authors)
Reyes, E.; Krokhin, A. A.; Roberts, J.
2005-01-01
We calculate the static dielectric tensor of a periodic system of aligned anisotropic dielectric cylinders. Exact analytical formulas for the effective dielectric constants for the E- and H- eigenmodes are obtained for arbitrary 2D Bravais lattice and arbitrary cross-section of anisotropic cylinders. It is shown that depending on the symmetry of the unit cell photonic crystal of anisotropic cylinders behaves in the low-frequency limit like uniaxial or biaxial natural crystal. The developed th...
Kjær, Hanna; Sauer, Stephan P. A.; Kongsted, Jacob
2011-01-01
We present a benchmark study of a combined multipole shielding polarizability/reaction field (MSP/RF) approach to the calculation of both specific and bulk solvation effects on nuclear magnetic shielding constants of solvated molecules. The MSP/RF scheme is defined by an expansion of the shielding constants of the solvated molecule in terms of electric field and field gradient property derivatives derived from single molecule ab initio calculations. The solvent electric field and electric field gradient are calculated based on data derived from molecular dynamics simulations, thereby accounting for solute-solvent dynamical effects. The MSP/RF method is benchmarked against polarizable quantum mechanics/molecular mechanics (QM/MM) calculations. The best agreement between the MSP/RF and QM/MM approaches is found by truncating the electric field expansion in the MSP/RF approach at the linear electric field level which is due to the cancelation of errors. In addition, we investigate the sensitivity of the results due to the choice of one-electron basis set in the ab initio calculations of the property derivatives and find that these derivatives are affected by the basis set in a way similar to the shielding constants themselves.
Dielectric Constant of Suspensions
Mendelson, Kenneth S.; Ackmann, James J.
1997-03-01
We have used a finite element method to calculate the dielectric constant of a cubic array of spheres. Extensive calculations support preliminary conclusions reported previously (K. Mendelson and J. Ackmann, Bull. Am. Phys. Soc. 41), 657 (1996).. At frequencies below 100 kHz the real part of the dielectric constant (ɛ') shows oscillations as a function of the volume fraction of suspension. These oscillations disappear at low conductivities of the suspending fluid. Measurements of the dielectric constant (J. Ackmann, et al., Ann. Biomed. Eng. 24), 58 (1996). (H. Fricke and H. Curtis, J. Phys. Chem. 41), 729 (1937). are not sufficiently sensitive to show oscillations but appear to be consistent with the theoretical results.
Optimization for Hue Constant RGB Sensors
Finlayson, Graham D.; Süsstrunk, Sabine
2002-01-01
We present an optimization technique to find hue constant RGB sensors. The hue representation is based on a log RGB opponent color space that is invariant to brightness and gamma. While modeling the visual response did not derive the opponent space, the hue definition is similar to the ones found in CIE Lab and IPT. Finding hue constant RGB sensors through this optimization might be applicable in color engineering applications such as finding RGB sensors for color image encodings.
Quaternions as astrometric plate constants
Jefferys, William H.
1987-01-01
A new method for solving problems in relative astrometry is proposed. In it, the relationship between the measured quantities and the components of the position vector of a star is modeled using quaternions, in effect replacing the plate constants of a standard four-plate-constant solution with the four components of a quaternion. The method allows a direct solution for the position vectors of the stars, and hence for the equatorial coordinates. Distortions, magnitude, and color effects are readily incorporated into the formalism, and the method is directly applicable to overlapping-plate problems. The advantages of the method include the simplicity of the resulting equations, their freedom from singularities, and the fact that trigonometric functions and tangential point transformations are not needed to model the plate material. A global solution over the entire sky is possible.
Algorithm for structure constants
Paiva, F M
2011-01-01
In a $n$-dimensional Lie algebra, random numerical values are assigned by computer to $n(n-1)$ especially selected structure constants. An algorithm is then created, which calculates without ambiguity the remaining constants, obeying the Jacobi conditions. Differently from others, this algorithm is suitable even for poor personal computer. ------------- En $n$-dimensia algebro de Lie, hazardaj numeraj valoroj estas asignitaj per komputilo al $n(n-1)$ speciale elektitaj konstantoj de strukturo. Tiam algoritmo estas kreita, kalkulante senambigue la ceterajn konstantojn, obeante kondicxojn de Jacobi. Malsimile al aliaj algoritmoj, tiu cxi tauxgas ecx por malpotenca komputilo.
Structure of high-spin states in A {approx} 60 region
Nakada, Hitoshi [Chiba Univ. (Japan); Furutaka, K.; Hatsukawa, Y. [and others
1998-03-01
High-spin states in the proton-rich Cu-Zn nuclei are investigated by the experiments at JAERI. New levels and {gamma}-rays are identified by the particle-{gamma}-{gamma} coincidence, and J{sup P} assignments are made via the DCO ratio analysis. Yrast sequences are observed up to J {approx} 18 for {sup 62}Zn, and {sup 64}Zn, J {approx} 27/2 for {sup 61}Cu and J {approx} 23/2 for {sup 63}Cu. Though we cannot settle new J{sup P} values for {sup 61,63}Zn, their yrast sequence is also extended. In {sup 64}Zn, a doublet of {gamma}-rays is discovered at 1315 keV, clarifying the similarity in the level scheme between {sup 62}Zn and {sup 64}Zn. We reproduce the yrast levels by a shell-model calculation, by which structure of the high-spin states is further studied. A parity change in the yrast sequence is established, in which the unique-parity orbit 0g{sub 9/2} plays an essential role; one nucleon excitation to g{sub 9/2} gains high angular momentum with low seniority, at the cost of the single-parity energy. Second parity-change is also suggested by the calculation. Such parity change seems characteristic to spherical or nearly spherical nuclei. In {sup 61}Cu, concentration of the {gamma}-ray intensity is observed. This happens because a stretched 3-quasiparticle configuration including 0g{sub 9/2} is relatively stable, similarly to some isomers. Thus, by studying the structure of the high-spin states of the A {approx} 60 nuclei, we have clarified the role of unique-parity orbit in high-spin states, which may be generic to spherical and nearly spherical nuclei. (J.P.N.)
THE SINS/zC-SINF SURVEY of z {approx} 2 GALAXY KINEMATICS: OUTFLOW PROPERTIES
Newman, Sarah F.; Genzel, Reinhard [Department of Astronomy, Campbell Hall, University of California, Berkeley, CA 94720 (United States); Foerster-Schreiber, Natascha M.; Buschkamp, Peter; Davies, Ric; Eisenhauer, Frank; Kurk, Jaron; Lutz, Dieter [Max-Planck-Institut fuer extraterrestrische Physik (MPE), Giessenbachstr.1, D-85748 Garching (Germany); Griffin, Kristen Shapiro [Space Sciences Research Group, Northrop Grumman Aerospace Systems, Redondo Beach, CA 90278 (United States); Mancini, Chiara; Renzini, Alvio [Osservatorio Astronomico di Padova, Vicolo dellOsservatorio 5, Padova, I-35122 (Italy); Lilly, Simon J.; Carollo, C. Marcella; Peng, Yingjie [Institute of Astronomy, Department of Physics, Eidgenoessische Technische Hochschule, ETH Zuerich, CH-8093 (Switzerland); Bouche, Nicolas [Institut de Recherche en Astrophysique et Planetologie (IRAP), Universite de Toulouse, UPS-OMP, IRAP, 14, avenue Edouard Berlin, F-31400 Toulouse (France); Burkert, Andreas [Department fuer Physik, Universitaets-Sternwarte Ludwig-Maximilians-Universitaet (USM), Scheinerstr. 1, Muenchen, D-81679 (Germany); Cresci, Giovanni [Istituto Nazionale di AstrofisicaOsservatorio Astronomico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze (Italy); Genel, Shy [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hicks, Erin K. S. [Department of Astronomy, University of Washington, Box 351580, U.W., Seattle, WA 98195-1580 (United States); Naab, Thorsten, E-mail: sfnewman@berkeley.edu [Max-Planck Institute for Astrophysics, Karl Schwarzschildstrasse 1, D-85748 Garching (Germany); and others
2012-12-10
Using SINFONI H{alpha}, [N II], and [S II] AO data of 27 z {approx} 2 star-forming galaxies (SFGs) from the SINS and zC-SINF surveys, we explore the dependence of outflow strength (via the broad flux fraction) on various galaxy parameters. For galaxies that have evidence for strong outflows, we find that the broad emission is spatially extended to at least the half-light radius ({approx}a few kpc). Decomposition of the [S II] doublet into broad and narrow components suggests that this outflowing gas probably has a density of {approx}10-100 cm{sup -3}, less than that of the star-forming gas (600 cm{sup -3}). There is a strong correlation of the H{alpha} broad flux fraction with the star formation surface density of the galaxy, with an apparent threshold for strong outflows occurring at 1 M{sub Sun} yr{sup -1} kpc{sup -2}. Above this threshold, we find that SFGs with log m{sub *} > 10 have similar or perhaps greater wind mass-loading factors ({eta} = M-dot{sub out}/SFR) and faster outflow velocities than lower mass SFGs, suggesting that the majority of outflowing gas at z {approx} 2 may derive from high-mass SFGs. The mass-loading factor is also correlated with the star formation rate (SFR), galaxy size, and inclination, such that smaller, more star-forming, and face-on galaxies launch more powerful outflows. We propose that the observed threshold for strong outflows and the observed mass loading of these winds can be explained by a simple model wherein break-out of winds is governed by pressure balance in the disk.
EARLY STAGES OF CLUSTER FORMATION: FRAGMENTATION OF MASSIVE DENSE CORES DOWN TO {approx}< 1000 AU
Palau, Aina; Girart, Josep M. [Institut de Ciencies de l' Espai (CSIC-IEEC), Campus UAB-Facultat de Ciencies, Torre C5-parell 2, E-08193 Bellaterra, Catalunya (Spain); Fuente, Asuncion [Observatorio Astronomico Nacional, P.O. Box 112, E-28803 Alcala de Henares, Madrid (Spain); Estalella, Robert [Departament d' Astronomia i Meteorologia (IEEC-UB), Institut de Ciencies del Cosmos, Universitat de Barcelona, Marti Franques, 1, E-08028 Barcelona (Spain); Ho, Paul T. P.; Zhang, Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Sanchez-Monge, Alvaro; Fontani, Francesco; Cesaroni, Riccardo [Osservatorio Astrofisico di Arcetri, INAF, Lago E. Fermi 5, I-50125 Firenze (Italy); Busquet, Gemma [INAF-Istituto di Astrofisica e Planetologia Spaziali, Area di Recerca di Tor Vergata, Via Fosso Cavaliere 100, I-00133 Roma (Italy); Commercon, Benoit; Hennebelle, Patrick [Laboratoire de Radioastronomie, UMR CNRS 8112, Ecole Normale Superieure et Observatoire de Paris, 24 rue Lhomond, F-75231 Paris Cedex 05 (France); Boissier, Jeremie [Istituto di Radioastronomia, INAF, Via Gobetti 101, I-40129 Bologna (Italy); Zapata, Luis A., E-mail: palau@ieec.uab.es [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, P.O. Box 3-72, 58090 Morelia, Michoacan (Mexico)
2013-01-10
In order to study the fragmentation of massive dense cores, which constitute the cluster cradles, we observed the continuum at 1.3 mm and the CO (2-1) emission of four massive cores with the Plateau de Bure Interferometer in the most extended configuration. We detected dust condensations down to {approx}0.3 M {sub Sun} and separate millimeter sources down to 0.''4 or {approx}< 1000 AU, comparable to the sensitivities and separations reached in optical/infrared studies of clusters. The CO (2-1) high angular resolution images reveal high-velocity knots usually aligned with previously known outflow directions. This, in combination with additional cores from the literature observed at similar mass sensitivity and spatial resolution, allowed us to build a sample of 18 protoclusters with luminosities spanning three orders of magnitude. Among the 18 regions, {approx}30% show no signs of fragmentation, while 50% split up into {approx}> 4 millimeter sources. We compiled a list of properties for the 18 massive dense cores, such as bolometric luminosity, total mass, and mean density, and found no correlation of any of these parameters with the fragmentation level. In order to investigate the combined effects of the magnetic field, radiative feedback, and turbulence in the fragmentation process, we compared our observations to radiation magnetohydrodynamic simulations and found that the low-fragmented regions are reproduced well in the magnetized core case, while the highly fragmented regions are consistent with cores where turbulence dominates over the magnetic field. Overall, our study suggests that the fragmentation in massive dense cores could be determined by the initial magnetic field/turbulence balance in each particular core.
QUIET-TIME INTERPLANETARY {approx}2-20 keV SUPERHALO ELECTRONS AT SOLAR MINIMUM
Wang, Linghua [Department of Geophysics, Peking University, 100871 Beijing (China); Lin, Robert P.; Salem, Chadi; Pulupa, Marc; Larson, Davin E.; Luhmann, Janet G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States); Yoon, Peter H., E-mail: wanglhwang@gmail.com [School of Space Research, Kyung Hee University, Yongin, Gyeonggi (Korea, Republic of)
2012-07-01
We present a statistical survey of {approx}2-20 keV superhalo electrons in the solar wind measured by the SupraThermal Electron instrument on board the two STEREO spacecraft during quiet-time periods from 2007 March through 2009 March at solar minimum. The observed superhalo electrons have a nearly isotropic angular distribution and a power-law spectrum, f{proportional_to}v{sup -{gamma}}, with {gamma} ranging from 5 to 8.7, with nearly half between 6.5 and 7.5, and an average index of 6.69 {+-} 0.90. The observed power-law spectrum varies significantly on a spatial scale of {approx}>0.1 AU and a temporal scale of {approx}>several days. The integrated density of quiet-time superhalo electrons at 2-20 keV ranges from {approx}10{sup -8} cm{sup -3} to 10{sup -6} cm{sup -3}, about 10{sup -9}-10{sup -6} of the solar wind density, and, as well as the power-law spectrum, shows no correlation with solar wind proton density, velocity, or temperature. The density of superhalo electrons appears to show a solar-cycle variation at solar minimum, while the power-law spectral index {gamma} has no solar-cycle variation. These quiet-time superhalo electrons are present even in the absence of any solar activity-e.g., active regions, flares or microflares, type III radio bursts, etc.-suggesting that they may be accelerated by processes such as resonant wave-particle interactions in the interplanetary medium, or possibly by nonthermal processes related to the acceleration of the solar wind such as nanoflares, or by acceleration at the CIR forward shocks.
GALEX-SELECTED LYMAN BREAK GALAXIES AT z {approx} 2: COMPARISON WITH OTHER POPULATIONS
Haberzettl, L.; Williger, G. [Department of Physics and Astronomy, University of Louisville, Louisville KY 20492 (United States); Lehnert, M. D. [GEPI, Observatoire de Paris, UMR 8111 du CNRS, 5 Place Jules Janssen, 92195 Meudon (France); Nesvadba, N. [Institut d' Astrophysique Spatiale, CNRS, Universite Paris-Sud, Bat. 120-121, 91405 Orsay (France); Davies, L. [Department of Physics, H H Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom)
2012-01-20
We present results of a search for bright Lyman break galaxies (LBGs) at 1.5 {<=} z {<=} 2.5 in the GOODS-S field using an NUV-dropout technique in combination with color selection. We derived a sample of 73 LBG candidates. We compare our selection efficiencies to BM/BX and BzK methods (techniques solely based on ground-based data sets), and find the NUV data to provide greater efficiency for selecting star-forming galaxies. We estimate LBG candidate ages, masses, star formation rates, and extinction from fitting PEGASE synthesis evolution models. We find that about 20% of our LBG candidates are comparable to infrared-luminous LBGs or submillimeter galaxies which are thought to be precursors of massive elliptical galaxies today. Overall, we can show that although BM/BX and BzK methods do identify star-forming galaxies at z {approx} 2, the sample they provide biases against those star-forming galaxies which are more massive and contain sizeable red stellar populations. A true Lyman break criterion at z {approx} 2 is therefore more directly comparable to the populations found at z {approx} 3, which does contain a red fraction.
Microscopic group constants determination
The method of microscopic group constants determination for nuclear reactor calculations is described in this paper. The principle of this method is group averaging of microscopic cross sections with respect to the standard spectrum. The group cross sections obtained are used for the calculation of fast critical assembly Jezebel. (author)
Serpent is a continuous-energy Monte Carlo (MC) reactor physics code recently developed at VTT Technical Research Centre of Finland. Serpent can be used for 2D fuel lattice calculations as well as for 3D full core simulations. Due to its built-in decay and burnup routine Serpent can perform depletion and decay analysis to provide time-dependent isotopic compositions and spent fuel characteristics including radioactivity and decay heat. Serpent uses matrix exponential method to solve the Bateman decay and depletion equations while the solution of the matrix exponential relies on the Chebyshev Rational Approximation Method (CRAM) Serpent runs significantly faster than other MC codes due to the two main reasons: 1) the use of the Woodcock delta-tracking in a combination with a typical surface-to-surface ray-tracing in a geometry routine, and 2) the use of the unionized energy grid for all point-wise reaction cross sections. The later, however, considerably increases the memory requirements and can be a bottleneck in simulations with a large number of involved nuclides. Serpent is especially designed to generate homogenized constants for deterministic 3D core analysis. For any region of interest the code automatically calculates homogenized few-group cross sections, group-to-group scattering matrices, diffusion coefficients, assembly discontinuity factors, kinetics parameters, etc. More details can be found in Serpent User's Manual. Recently some new calculation methods related to the production of homogenized few-group constants were implemented in the Serpent code including homogenization in leakage-corrected criticality spectrum, group constant generation in reflectors and other non-fissile regions, and improved treatment of neutron-multiplying scattering reactions. The capability to generate homogenized few-group constants can be considered as one of the most attractive features of Serpent. Being a MC code, Serpent is capable of handling complex geometries without
It is possible to determine the h/mRb ratio between the Planck constant and the mass of the atoms, and then to deduce a value of the fine structure constant alpha, from the accurate measurement of the recoil velocity of an atom absorbing a photon. To perform this measurement we combine the high efficiency of Bloch oscillations with the high sensitivity of a Ramsey-Borde interferometer. The Bloch oscillations technic allows us to transfer a large number of recoils to the atoms (up to 1600 recoil momenta). An interferometric Ramsey-Borde velocity sensor, based on velocity selective Raman transitions, allows us to measure the momentum transferred to the atoms. A measurement with a statistical uncertainty of 3 ppb (3*10-9), in conjunction with a careful study of systematic effects (3.4 ppb), lead us to a determination of alpha with a relative uncertainty of 4.8 ppb. The value of α-1 is 137.03599887(65). It is the best determination of alpha, independent from quantum electrodynamics
Papp, P., E-mail: papp@fmph.uniba.sk [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina, 84248 Bratislava (Slovakia); Matejčík, Š. [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina, 84248 Bratislava (Slovakia); Mach, P.; Urban, J. [Department of Nuclear Physics and Biophysics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina, 84248 Bratislava (Slovakia); Paidarová, I. [J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, CZ-182 23 Praha 8 (Czech Republic); Horáček, J., E-mail: horacek@mbox.troja.mff.cuni.cz [Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, CZ-180 00 Praha 8 (Czech Republic)
2013-06-03
Highlights: • The anions are stabilized by additional charges on the nuclei. • The energy dependence of anions and neutrals on nuclear charges are calculated by ab initio methods. • Resonance energies and widths are obtained from the energy data by analytical continuation with Padé approximation. • The resonance energies and widths of amino acids are compared with Nestmann–Peyerimhoff’s method and with experiment. • The resonance energies and (widths) of formic acid monomer and dimer are 2.09 (0.33) eV and 1.7 (0.13) eV, respectively. - Abstract: The method of analytic continuation in the coupling constant (ACCC) in combination with use of the statistical Padé approximation is applied to the determination of resonance energy and width of some amino acids and formic acid dimer. Standard quantum chemistry codes provide accurate data which can be used for analytic continuation in the coupling constant to obtain the resonance energy and width of organic molecules with a good accuracy. The obtained results are compared with the existing experimental ones.
Perdomo, Oscar M
2013-01-01
In this paper we show all possible ramps where an object can move with constant speed under the effect of gravity and friction. The planar ramp are very easy to describe, just rotate a curve with velocity vector (tanh(as),sech(as)). Recall that tanh(as)^2+sech^2(as) = 1. Therefore, the solution of the planar constant speed problem is connected with easy to describe examples of curves with arc-length parameter. For ramps in the space, we show that there are as many ramps as tangent unit vector fields in the south hemisphere. A video explaining these results can be found at http://www.youtube.com/watch?v=iBrvbb0efVk
Variation of fundamental constants
Flambaum, V V
2006-01-01
We present a review of recent works devoted to the variation of the fine structure constant alpha, strong interaction and fundamental masses. There are some hints for the variation in quasar absorption spectra, Big Bang nucleosynthesis, and Oklo natural nuclear reactor data. A very promising method to search for the variation of the fundamental constants consists in comparison of different atomic clocks. Huge enhancement of the variation effects happens in transition between accidentally degenerate atomic and molecular energy levels. A new idea is to build a ``nuclear'' clock based on the ultraviolet transition between very low excited state and ground state in Thorium nucleus. This may allow to improve sensitivity to the variation up to 10 orders of magnitude! Huge enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feschbach resonance.
The cosmological constant puzzle
Bass, Steven D.
2011-01-01
Abstract The accelerating expansion of the Universe points to a small positive vacuum energy density and negative vacuum pressure. A strong candidate is the cosmological constant in Einstein's equations of General Relativity. Possible contributions are zero-point energies and the condensates associated with spontaneous symmetry breaking. The vacuum energy density extracted from astrophysics is 10 56 times smaller than the value expected from quantum fields and Standard Model particle physi...
Small fluctuations in the solar constant can occur on timescales much shorter than the Kelvin time. Changes in the ability of convection to transmit energy through the superadiabatic and transition regions of the convection zone cause structure adjustments which can occur on a time scale of days. The bulk of the convection zone reacts to maintain hydrostatic equilibrium (though not thermal equilibrium) and causes a luminosity change. While small radius variations will occur, most of the change will be seen in temperature
Calixto, M.
2000-03-01
The structure constants for Moyal brackets of an infinite basis of functions on the algebraic manifolds M of pseudo-unitary groups U (N + ,N - ) are provided. They generalize the Virasoro and icons/Journals/Common/calW" ALT="calW" ALIGN="TOP"/> icons/Journals/Common/infty" ALT="infty" ALIGN="MIDDLE"/> algebras to higher dimensions. The connection with volume-preserving diffeomorphisms on M , higher generalized-spin and tensor operator algebras of U (N + ,N - ) is discussed. These centrally extended, infinite-dimensional Lie algebras also provide the arena for nonlinear integrable field theories in higher dimensions, residual gauge symmetries of higher-extended objects in the light-cone gauge and C * -algebras for tractable non-commutative versions of symmetric curved spaces.
Confirmation of Small Dynamical and Stellar Masses for Extreme Emission Line Galaxies at z Approx. 2
Maseda, Michael V.; van Der Wel, Arjen; da Cunha, Elisabete; Rix, Hans-Walter; Pacifici, Camilla; Momcheva, Ivelina; Brammer, Gabriel B.; Franx, Marijn; van Dokkum, Pieter; Bell, Eric F.; Fumagalli, Mattia; Grogin, Norman A.; Kocevski, Dale D.; Koekemoer, Anton M.; Lundgren, Britt F.; Marchesini, Danilo; Nelson, Eric J.; Patel, Shannon G.; Skelton, Rosalind E.; Straughn, Amber N.; Trump. Jonathan R.; Weiner, Benjamin J.; Whitaker, Katherine E.; Wuyts, Stijn
2013-01-01
Spectroscopic observations from the Large Binocular Telescope and the Very Large Telescope reveal kinematically narrow lines (approx. 50 km/s) for a sample of 14 extreme emission line galaxies at redshifts 1.4 1. The stellar mass formed in this vigorous starburst phase represents a large fraction of the total (dynamical) mass, without a significantly massive underlying population of older stars. The occurrence of such intense events in shallow potentials strongly suggests that supernova-driven winds must be of critical importance in the subsequent evolution of these systems.
Neal Jackson
2015-09-01
Full Text Available I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual astrophysical objects which have some property that allows their intrinsic luminosity or size to be determined, or allows the determination of their distance by geometric means. The second category comprises the use of all-sky cosmic microwave background, or correlations between large samples of galaxies, to determine information about the geometry of the Universe and hence the Hubble constant, typically in a combination with other cosmological parameters. Many, but not all, object-based measurements give H_0 values of around 72–74 km s^–1 Mpc^–1, with typical errors of 2–3 km s^–1 Mpc^–1. This is in mild discrepancy with CMB-based measurements, in particular those from the Planck satellite, which give values of 67–68 km s^–1 Mpc^–1 and typical errors of 1–2 km s^–1 Mpc^–1. The size of the remaining systematics indicate that accuracy rather than precision is the remaining problem in a good determination of the Hubble constant. Whether a discrepancy exists, and whether new physics is needed to resolve it, depends on details of the systematics of the object-based methods, and also on the assumptions about other cosmological parameters and which datasets are combined in the case of the all-sky methods.
Approximations to Euler's constant
We study a problem of finding good approximations to Euler's constant γ=lim→∞ Sn, where Sn = Σk=Ln (1)/k-log(n+1), by linear forms in logarithms and harmonic numbers. In 1995, C. Elsner showed that slow convergence of the sequence Sn can be significantly improved if Sn is replaced by linear combinations of Sn with integer coefficients. In this paper, considering more general linear transformations of the sequence Sn we establish new accelerating convergence formulae for γ. Our estimates sharpen and generalize recent Elsner's, Rivoal's and author's results. (author)
Kim, Sang-Kyu; Ito, Kazuma; Yoshihara, Daisuke; Wakisaka, Tomoyuki
For numerically predicting the combustion processes in homogeneous charge compression ignition (HCCI) engines, practical chemical kinetic models have been explored. A genetic algorithm (GA) has been applied to the optimization of the rate constants in detailed chemical kinetic models, and a detailed kinetic model (592 reactions) for gasoline reference fuels with arbitrary octane number between 60 and 100 has been obtained from the detailed reaction schemes for iso-octane and n-heptane proposed by Golovitchev. The ignition timing in a gasoline HCCI engine has been predicted reasonably well by zero-dimensional simulation using the CHEMKIN code with this detailed kinetic model. An original reduced reaction scheme (45 reactions) for dimethyl ether (DME) has been derived from Curran’s detailed scheme, and the combustion process in a DME HCCI engine has been predicted reasonably well in a practical computation time by three-dimensional simulation using the authors’ GTT code, which has been linked to the CHEMKIN subroutines with the proposed reaction scheme and also has adopted a modified eddy dissipation combustion model.
We have designed and realized a Front-End chip for MPPC in standard CMOS 0.35μm technology. The channel presents a low input impedance in order to reduce as much as possible the recovery time of the sensor. This is achieved using the current domain for processing signals through the current conveyors (CCII) as building blocks of the channel. A current feed-back with low-pass filter has also been used to realize a sensitive improvement of the correction of the pile-up problem, in case of high repetition rate events. An independent arming threshold is available for each channel, providing the selection of the event through the peak level (proportional to the number of simultaneously hit pixels) reached by the signal. A constant-fraction functionality is present in order to reduce the well know time-walk problem. The delay in the correspondent branch is obtained by using an additional CCII block. The digital output of the discriminator channel has adjustable time width. The pilot chip is made up of five channels. All the values of the independent thresholds are stored in 10−bit registers as well as the values of the trigger output width and the main polarization current of the CCII blocks. All the registers are writable from a standard three-wire SPI. These features make the chip fully self-consistent. In this work we present and discuss the simulation results together with the preliminary test performed
Neutron-proton pairing correlations in medium mass N approx =Z nuclei
Petrovici, A; Faessler, A
1999-01-01
The pair structure and the average pairing gaps of realistic wave functions obtained within the complex Excited Vampir variational approach are investigated in order to evaluate the neutron-proton pairing correlations at low and high spins in medium mass N approx =Z nuclei. The number of isovector J suppi=0 sup + pairs is calculated for the lowest few 0 sup + states in two chains of nuclei in the A approx =70 mass region. The results indicate the dominant role played by the isovector neutron-proton pairing correlations in the structure of odd-odd N=Z nuclei and the reduction of their importance with increasing neutron excess in even-even nuclei. The evolution of particular isovector and isoscalar pairs with increasing angular momentum is analyzed for the odd-odd N=Z nucleus sup 7 sup 4 Rb and the even-even N=Z nucleus sup 7 sup 2 Kr. It turns out that in the nucleus sup 7 sup 4 Rb the neutron-proton correlations play an essential role for the alignment of the yrast positive-parity even-spin band.
MEASUREMENT OF 21 cm BRIGHTNESS FLUCTUATIONS AT z {approx} 0.8 IN CROSS-CORRELATION
Masui, K. W.; Switzer, E. R.; Calin, L.-M.; Pen, U.-L.; Shaw, J. R. [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George St., Toronto, Ontario, M5S 3H8 (Canada); Banavar, N. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, Ontario, M5S 3H4 (Canada); Bandura, K. [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec, H3A 2T8 (Canada); Blake, C. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122 (Australia); Chang, T.-C.; Liao, Y.-W. [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei, 10617, Taiwan (China); Chen, X.; Li, Y.-C. [National Astronomical Observatories, Chinese Academy of Science, 20A Datun Road, Beijing 100012 (China); Natarajan, A.; Peterson, J. B.; Voytek, T. C. [McWilliams Center for Cosmology, Carnegie Mellon University, Department of Physics, 5000 Forbes Ave., Pittsburgh, PA 15213 (United States)
2013-01-20
In this Letter, 21 cm intensity maps acquired at the Green Bank Telescope are cross-correlated with large-scale structure traced by galaxies in the WiggleZ Dark Energy Survey. The data span the redshift range 0.6 < z < 1 over two fields totaling {approx}41 deg. sq. and 190 hr of radio integration time. The cross-correlation constrains {Omega}{sub HI} b{sub HI} r = [0.43 {+-} 0.07(stat.) {+-} 0.04(sys.)] Multiplication-Sign 10{sup -3}, where {Omega}{sub HI} is the neutral hydrogen (H I) fraction, r is the galaxy-hydrogen correlation coefficient, and b{sub HI} is the H I bias parameter. This is the most precise constraint on neutral hydrogen density fluctuations in a challenging redshift range. Our measurement improves the previous 21 cm cross-correlation at z {approx} 0.8 both in its precision and in the range of scales probed.
The gas mass of star-forming galaxies at $z \\approx 1.3$
Kanekar, Nissim; Dwarakanath, K S
2016-01-01
We report a Giant Metrewave Radio Telescope (GMRT) search for HI 21cm emission from a large sample of star-forming galaxies at $z \\approx 1.18 - 1.34$, lying in sub-fields of the DEEP2 Redshift Survey. The search was carried out by co-adding ("stacking") the HI 21cm emission spectra of 857 galaxies, after shifting each galaxy's HI 21cm spectrum to its rest frame. We obtain the $3\\sigma$ upper limit S$_{\\rm{HI}} 1$. The implied limit on the average atomic gas mass fraction (relative to stars) is ${\\rm M}_{\\rm GAS}/{\\rm M}_* < 0.5$, comparable to the cold molecular gas mass fraction in similar star-forming galaxies at these redshifts. We find that the cosmological mass density of neutral atomic gas in star-forming galaxies at $z \\approx 1.3$ is $\\Omega_{\\rm GAS} < 3.7 \\times 10^{-4}$, significantly lower than $\\Omega_{\\rm GAS}$ estimates in both galaxies in the local Universe and damped Lyman-$\\alpha$ absorbers at $z \\geq 2.2$. Blue star-forming galaxies thus do not appear to dominate the neutral atomic ...
THE ASSEMBLY OF MILKY-WAY-LIKE GALAXIES SINCE z {approx} 2.5
Van Dokkum, Pieter G.; Leja, Joel; Nelson, Erica June; Skelton, Rosalind E.; Momcheva, Ivelina [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Patel, Shannon; Fumagalli, Mattia; Franx, Marijn; Labbe, Ivo [Leiden Observatory, Leiden University, Leiden (Netherlands); Brammer, Gabriel [European Southern Observatory, Alonson de Cordova 3107, Casilla 19001, Vitacura, Santiago (Chile); Whitaker, Katherine E. [Astrophysics Science Division, Goddard Space Center, Greenbelt, MD 20771 (United States); Lundgren, Britt [Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706 (United States); Conroy, Charlie [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA (United States); Foerster Schreiber, Natascha; Wuyts, Stijn [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Kriek, Mariska [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Marchesini, Danilo [Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Rix, Hans-Walter; Van der Wel, Arjen [Max Planck Institute for Astronomy (MPIA), Koenigstuhl 17, D-69117 Heidelberg (Germany)
2013-07-10
Galaxies with the mass of the Milky Way dominate the stellar mass density of the universe but it is uncertain how and when they were assembled. Here we study progenitors of these galaxies out to z = 2.5, using data from the 3D-HST and CANDELS Treasury surveys. We find that galaxies with present-day stellar masses of log (M) Almost-Equal-To 10.7 built {approx}90% of their stellar mass since z = 2.5, with most of the star formation occurring before z = 1. In marked contrast to the assembly history of massive elliptical galaxies, mass growth is not limited to large radii: the mass in the central 2 kpc of the galaxies increased by a factor of 3.2{sup +0.8}{sub -0.7} between z = 2.5 and z = 1. We therefore rule out simple models in which bulges were fully assembled at high redshift and disks gradually formed around them. Instead, bulges (and black holes) likely formed in lockstep with disks, through bar instabilities, migration, or other processes. We find that after z = 1 the growth in the central regions gradually stopped and the disk continued to be built up, consistent with recent studies of the gas distributions in z {approx} 1 galaxies and the properties of many spiral galaxies today.
Reactor group constants and benchmark test
The evaluated nuclear data files such as JENDL, ENDF/B-VI and JEF-2 are validated by analyzing critical mock-up experiments for various type reactors and assessing applicability for nuclear characteristics such as criticality, reaction rates, reactivities, etc. This is called Benchmark Testing. In the nuclear calculations, the diffusion and transport codes use the group constant library which is generated by processing the nuclear data files. In this paper, the calculation methods of the reactor group constants and benchmark test are described. Finally, a new group constants scheme is proposed. (author)
MUTLU, Reşat
2015-01-01
The memristor is a new-found circuit element and its applications in programmable circuits are also under study. Analysis of most of its combinations with other circuit elements such as resistors, capacitors, and inductors does not exist. In this work, a TiO$_{2}$ memristor model with linear dopant drift speed is used and the solution of a TiO$_{2}$ memristor and capacitor series circuit driven by a constant voltage source is given. It is then used to analyze a novel M-C oscillator circuit. I...
Constant Proportion Portfolio Insurance
Jessen, Cathrine
2014-01-01
Portfolio insurance, as practiced in 1987, consisted of trading between an underlying stock portfolio and cash, using option theory to place a floor on the value of the position, as if it included a protective put. Constant Proportion Portfolio Insurance (CPPI) is an option-free variation on the...... theme, originally proposed by Fischer Black. In CPPI, a financial institution guarantees a floor value for the “insured” portfolio and adjusts the stock/bond mix to produce a leveraged exposure to the risky assets, which depends on how far the portfolio value is above the floor. Plain-vanilla portfolio...... insurance largely died with the crash of 1987, but CPPI is still going strong. In the frictionless markets of finance theory, the issuer’s strategy to hedge its liability under the contract is clear, but in the real world with transactions costs and stochastic jump risk, the optimal strategy is less obvious...
Beiu, V.
1997-04-01
In this paper the authors discuss several complexity aspects pertaining to neural networks, commonly known as the curse of dimensionality. The focus will be on: (1) size complexity and depth-size tradeoffs; (2) complexity of learning; and (3) precision and limited interconnectivity. Results have been obtained for each of these problems when dealt with separately, but few things are known as to the links among them. They start by presenting known results and try to establish connections between them. These show that they are facing very difficult problems--exponential growth in either space (i.e. precision and size) and/or time (i.e., learning and depth)--when resorting to neural networks for solving general problems. The paper will present a solution for lowering some constants, by playing on the depth-size tradeoff.
Decay constants in geochronology
IgorM.Villa; PaulR.Renne
2005-01-01
Geologic time is fundamental to the Earth Sciences, and progress in many disciplines depends critically on our ability to measure time with increasing accuracy and precision. Isotopic geochronology makes use of the decay of radioactive nuclides as a help to quantify the histories of rock, minerals, and other materials. Both accuracy and precision of radioisotopic ages are, at present, limited by those of radioactive decay constants. Modem mass spectrometers can measure isotope ratios with a precision of 10-4 or better. On the other hand, the uncertainties associated with direct half-life determinations are, in most cases, still at the percent level. The present short note briefly summarizes progress and problems that have been encountered during the Working Group's activity.
Jackson Neal
2007-09-01
Full Text Available I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. In the last 20 years, much progress has been made and estimates now range between 60 and 75 km s^-1 Mpc^-1, with most now between 70 and 75 km s^-1 Mpc^-1, a huge improvement over the factor-of-2 uncertainty which used to prevail. Further improvements which gave a generally agreed margin of error of a few percent rather than the current 10% would be vital input to much other interesting cosmology. There are several programmes which are likely to lead us to this point in the next 10 years.
Hadron spectrum, quark masses and decay constants from light overlap fermions on large lattices
Galletly, D.; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics; Guertler, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Perlt, H.; Schiller, A. [Leipzig Univ. (Germany). Inst. fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division, Dept. of Mathematical Sciences; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Streuer, T. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC]|[Freie Univ. Berlin (Germany). Inst. fuer Theoretische Physik
2006-07-15
We present results from a simulation of quenched overlap fermions with Luescher-Weisz gauge field action on lattices up to 24{sup 3} 48 and for pion masses down to {approx}250 MeV. Among the quantities we study are the pion, rho and nucleon masses, the light and strange quark masses, and the pion decay constant. The renormalization of the scalar and axial vector currents is done nonperturbatively in the RI-MOM scheme. The simulations are performed at two different lattice spacings, a {approx}0.1 fm and {approx}0.15 fm, and on two different physical volumes, to test the scaling properties of our action and to study finite volume effects. We compare our results with the predictions of chiral perturbation theory and compute several of its low-energy constants. The pion mass is computed in sectors of fixed topology as well. (orig.)
Yahia, I. S.; Ganesh, V.; Shkir, M.; AlFaify, S.; Zahran, H. Y.; Algarni, H.; Abutalib, M. M.; Al-Ghamdi, Attieh A.; El-Naggar, A. M.; AlBassam, A. M.
2016-09-01
In the current work, the authors present the systematic study on linear and nonlinear optical properties of Copper-phathalocyanine thin film deposited by thermal evaporation system for the first time. The thickness of the prepared thin film was measured and found to be ~300 nm. X-ray diffraction and AFM study confirms that the prepared thin film possess good quality. The orientation of the grown thin film is found to be along (100). UV-vis-NIR study shows that the deposited thin film is highly transparent (>80%) in the wavelength range of 700-2500 nm. Further, the recorded optical data was used to determine the various linear and nonlinear optical parameters. The calculated value of refractive index is found to be in the range of 0.4-1.0. The direct and indirect band gap value is found to be 2.9 and 3.25 eV, respectively. The value of linear and nonlinear susceptibilities is found to be in order of 10-12. The higher value of linear and nonlinear parameters makes it suitable for optoelectronic applications.
Analysis of the chemical equilibrium of combustion at constant volume
Marius BREBENEL
2014-04-01
Full Text Available Determining the composition of a mixture of combustion gases at a given temperature is based on chemical equilibrium, when the equilibrium constants are calculated on the assumption of constant pressure and temperature. In this paper, an analysis of changes occurring when combustion takes place at constant volume is presented, deriving a specific formula of the equilibrium constant. The simple reaction of carbon combustion in pure oxygen in both cases (constant pressure and constant volume is next considered as example of application, observing the changes occurring in the composition of the combustion gases depending on temperature.
There are various charge constant current technologies for liquid scintillation circuit. The constant current technology, charge technology and their application to liquid scintillation counter are emphasized
The interacting and non-constant cosmological constant
We propose a time-varying cosmological constant with a fixed equation of state, which evolves mainly through its interaction with the background during most of the long history of the universe. However, such interaction does not exist in the very early and the late-time universe and produces the acceleration during these eras when it becomes very nearly a constant. It is found that after the initial inflationary phase, the cosmological constant, which we call as lambda parameter, rolls down from a large constant value to another but very small constant value and further dominates the present epoch showing up in the form of the dark energy driving the acceleration. (author)
Adelic Universe and Cosmological Constant
Makhaldiani, Nugzar
2003-01-01
In the quantum adelic field (string) theory models, vacuum energy -- cosmological constant vanish. The other (alternative ?) mechanism is given by supersymmetric theories. Some observations on prime numbers, zeta -- function and fine structure constant are also considered.
1995-08-01
about the distances to galaxies and thereby about the expansion rate of the Universe. A simple way to determine the distance to a remote galaxy is by measuring its redshift, calculate its velocity from the redshift and divide this by the Hubble constant, H0. For instance, the measured redshift of the parent galaxy of SN 1995K (0.478) yields a velocity of 116,000 km/sec, somewhat more than one-third of the speed of light (300,000 km/sec). From the universal expansion rate, described by the Hubble constant (H0 = 20 km/sec per million lightyears as found by some studies), this velocity would indicate a distance to the supernova and its parent galaxy of about 5,800 million lightyears. The explosion of the supernova would thus have taken place 5,800 million years ago, i.e. about 1,000 million years before the solar system was formed. However, such a simple calculation works only for relatively ``nearby'' objects, perhaps out to some hundred million lightyears. When we look much further into space, we also look far back in time and it is not excluded that the universal expansion rate, i.e. the Hubble constant, may have been different at earlier epochs. This means that unless we know the change of the Hubble constant with time, we cannot determine reliable distances of distant galaxies from their measured redshifts and velocities. At the same time, knowledge about such change or lack of the same will provide unique information about the time elapsed since the Universe began to expand (the ``Big Bang''), that is, the age of the Universe and also its ultimate fate. The Deceleration Parameter q0 Cosmologists are therefore eager to determine not only the current expansion rate (i.e., the Hubble constant, H0) but also its possible change with time (known as the deceleration parameter, q0). Although a highly accurate value of H0 has still not become available, increasing attention is now given to the observational determination of the second parameter, cf. also the Appendix at the
THE FORMATION OF THE FIRST COSMIC STRUCTURES AND THE PHYSICS OF THE z {approx} 20 UNIVERSE
O' Leary, Ryan M.; McQuinn, Matthew [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
2012-11-20
We perform a suite of cosmological simulations in the {Lambda}CDM paradigm of the formation of the first structures in the universe prior to astrophysical reheating and reionization (15 {approx}< z < 200). These are the first simulations initialized in a manner that self-consistently accounts for the impact of pressure on the rate of growth of modes, temperature fluctuations in the gas, and the dark matter-baryon supersonic velocity difference. Even with these improvements, these are still difficult times to simulate accurately as the Jeans length of the cold intergalactic gas must be resolved while also capturing a representative sample of the universe. We explore the box size and resolution requirements to meet these competing objectives. Our simulations support the finding of recent studies that the dark matter-baryon velocity difference has a surprisingly large impact on the accretion of gas onto the first star-forming minihalos (which have masses of {approx}10{sup 6} M {sub Sun }). In fact, the halo gas is often significantly downwind of such halos and with lower densities in the simulations in which the baryons have a bulk flow with respect to the dark matter, modulating the formation of the first stars by the local value of this velocity difference. We also show that dynamical friction plays an important role in the nonlinear evolution of the dark matter-baryon differential velocity, acting to erase this velocity difference quickly in overdense gas, as well as sourcing visually apparent bow shocks and Mach cones throughout the universe. We use simulations with both the GADGET and Enzo cosmological codes to test the robustness of these conclusions. The comparison of these codes' simulations also provides a relatively controlled test of these codes themselves, allowing us to quantify some of the tradeoffs between the algorithms. For example, we find that particle coupling in GADGET between the gas and dark matter particles results in spurious growth that
Witzel, Oliver
2013-01-01
We report on our progress to obtain the decay constants f_B and f_Bs from lattice-QCD simulations on the RBC-UKQCD Collaborations 2+1 flavor domain-wall Iwasaki lattices. Using domain-wall light quarks and relativistic b-quarks we analyze data with several partially quenched light-quark masses at two lattice spacings of a approx 0.11 fm and a approx 0.08 fm.
Hemisphere differences in the morphology of the high latitude ionosphere measured at approx. 500 km
Ambient electron density measurements made by the radio frequency capacitance probe on Ariel 4 have been analyzed in order to study the structures present at approx. 500 km altitude at latitudes poleward of + - 500A during the 1971 Northern Hemisphere winter (December solstice) and the 1972 Southern Hemisphere winter (June solstice); data obtained on 94 days centered on each solstice have been used. The general morphology of and the extreme densities within the mid-latitude electron density trough, the polar cap depletions and the electron density enhancements associated with the cusp-auroral zone were determined statistically. Analyses of data acquired during quiet magnetic conditions (Ksub(p) < = 2 +) show that the Northern and Southern Hemisphere winter ionospheres were significantly different; in particular, the Southern Hemisphere densities were lower than those in the Northern Hemisphere. The maximum electron densities observed in the Northern Hemisphere occurred in a magnetic-local-time range symmetrical about the 02 14 M.L.T. meridian, whereas in the Southern Hemisphere the maxima were symmetrical with respect to the midnight noon magnetic meridian. (author)
Substructure within the SSA22 protocluster at $z\\approx3.09$
Topping, Michael W; Steidel, Charles C
2016-01-01
We present the results of a densely sampled spectroscopic survey of the SSA22 protocluster at $z\\approx 3.09$. Our sample with Keck/LRIS spectroscopy includes 106 Ly$\\alpha$ Emitters (LAEs) and 40 Lyman Break Galaxies (LBGs) at $z=3.05-3.12$. These galaxies are contained within the $9'\\times9'$ region in which the protocluster was discovered, which also hosts the maximum galaxy overdensity in the SSA22 region. The redshift histogram of our spectroscopic sample reveals two distinct peaks, at $z=3.069$ (blue, 43 galaxies) and $z=3.095$ (red, 103 galaxies). Furthermore, objects in the blue and red peaks are segregated on the sky, with galaxies in the blue peak concentrating towards the western half of the field. These results suggest that the blue and red redshift peaks represent two distinct structures in physical space. Although the double-peaked redshift histogram is traced in the same manner by LBGs and LAEs, and brighter and fainter galaxies, we find that nine out of 10 X-ray AGNs in SSA22, and all seven sp...
Coulomb Excitation of Neutron-Rich $A\\approx$140 Nuclei
Van duppen, P L E
2002-01-01
Investigating the isospin dependence of the product between the B( E2; 0$_{1}^{+} \\rightarrow 2_{1}^{+}$)-value and the 2$_{1}^{+}$-excitation energy E$_{2^{+}}$ in even-even nuclei around $A\\!\\approx$140 one observes a rather smooth trend close to the valley of stability but clear indication for a reduction from the extrapolated B(E2)-values by one order of magnitude for some very neutron-rich nuclei. While close to the valley of stability the strong neutron-proton interaction results in an equilibration of the neutron and proton deformations with a predominate isoscalar character of the collective 2$^{+}$ excitation, it is conceivable that more loosely bound neutrons cannot polarize a close-to-magic proton core that well any more. This might result in a decoupling of the shape of the outer neutrons from the core and in a strong isovector admixture to the lowest lying 2$^{+}$ level. In this way the 2$^{+}$ -energies could be further lowered in neutron-rich nuclei, while the quadrupole moments of the proton c...
Isomers in neutron-rich A{approx}190 nuclides from {sup 208}Pb fragmentation
Caamano, M.; Podolyak, Z.; Garces Narro, J. [University of Surrey, Department of Physics, Guildford (United Kingdom); Walker, M. [University of Surrey, Department of Physics, Guildford (United Kingdom)]|[TRIUMF, Vancouver (Canada); Regan, P.H. [University of Surrey, Department of Physics, Guildford (United Kingdom)]|[Yale University, Wright Nuclear Structure Laboratory, New Haven (United States); Pfuetzner, M. [Warsaw University, Institute of Experimental Physics, Warsaw (Poland); Gerl, J.; Cortina Gil, D.; Doering, J.; Geissel, H. [GSI, Darmstadt (Germany); Hellstroem, M. [GSI, Darmstadt (Germany)]|[Lund University, Div. of Nuclear Physics (Sweden); Mayet, P. [GSI, Darmstadt (Germany)]|[KU Leuven, IKS, Leuven (Belgium); Mineva, M.N. [Lund University, Division of Nuclear Physics (Sweden); Aprahamian, A. [University of Notre Dame, Department of Physics, South Bend (United States); Benlliure, J. [University of Santiago de Compostela, Departamento de Fisica de Particulas, Santiago de Compostela (Spain); Bruce, A.M. [University of Brighton, School of Engineering, Brighton (United Kingdom); Butler, P.A. [University of Liverpool, Oliver Lodge Laboratory, Liverpool (United Kingdom); Cullen, D.M. [University of Liverpool, Oliver Lodge Laboratory, Liverpool (United Kingdom)]|[University of Manchester, Schuster Lab., Manchester (United Kingdom); Enqvist, T. [GSI, Darmstadt (Germany)]|[Univ. of Jyvaeskylae, Dept. of Physics, Jyvaeskylae (Finland); Fox, C. [Univ. of Liverpool, Oliver Lodge Lab., Liverpool (United Kingdom)]|[Duke Univ., TUNL, Durham (United States); Gelletly, M.; Giovinazzo, J.; Gorska, M.; Grawe, H.; Grzywacz, R.; Kleinboehl, A.H.; Korten, A.; Lewitowicz, M.; Lucas, R.; Mach, H.; O' Leary, C.D.; De Oliveira, F.; Pearson, C.J.; Rejmund, F.; Rejmund, M.; Sawicka, M.; Schaffner, H.; Schlegel, C.; Schmidt, K.; Schmidt, K.H.; Stevenson, P.D.; Theisen, C.; Vives, F.; Warner, D.D.; Wheldon, C.; Wollersheim, S.; Wooding, S.; Xu, F.; Yordanov, O.
2005-02-01
Relativistic projectile fragmentation of {sup 208}Pb has been used to produce isomers in neutron-rich, A{approx}190 nuclides. A forward-focusing spectrometer provided ion-by-ion mass and charge identification. The detection of {gamma}-rays emitted by stopped ions has led to the assignment of isomers in {sup 188}Ta, {sup 190}W, {sup 192}Re, {sup 193}Re, {sup 195}Os, {sup 197}Ir, {sup 198}Ir, {sup 200}Pt, {sup 201}Pt, {sup 202}Pt and {sup 203}Au, with half-lives ranging from approximately 10 ns to 1 ms. Tentative isomer information has been found also for {sup 174}Er, {sup 175}Er, {sup 185}Hf, {sup 191}Re, {sup 194}Re and {sup 199}Ir. In most cases, time-correlated, singles {gamma}-ray events provided the first spectroscopic data on excited states for each nuclide. In {sup 200}Pt and {sup 201}Pt, the assignments are supported by {gamma}-{gamma} coincidences. Isomeric ratios provide additional information, such as half-life and transition energy constraints in particular cases. The level structures of the platinum isotopes are discussed, and comparisons are made with isomer systematics. (orig.)
A constraint on the distance dependence of the gravitational constant
Extended supergravity theories predict the existence of vector and scalar bosons, besides the gravitation, which in the static limit couple to the mass. An example is the gravitation, leading to antigravity. If these bosons have a small mass (approx. -4 eV), an observable Yukawa term would be present in the gravitational potential in the newtonian limit. This can be parametrized by a distance dependent effective gravitational constant G(γ). Defining G0 = G (10 cm) and Gsub(e) = G (103 km), the comparison between theory and observations of the white dwarf Sirius B results in Gsub(c)/G0 = 0.98 +- 0.08. (orig.)
A construction method for discrete constant negative Gaussian curvature surfaces
Kobayashi, Shimpei
2016-01-01
This article is an application of the author's paper about a construction method for discrete constant negative Gaussian curvature surfaces, the nonlinear d'Alembert formula. The heart of this formula is the Birkhoff decomposition, and we give a simple algorithm for the Birkhoff decomposition. As an application, we draw figures of discrete constant negative Gaussian curvature surfaces given by this method.
Elia, D.; Molinari, S.; Schisano, E.; Pestalozzi, M.; Benedettini, M.; Di Giorgio, A. M.; Pezzuto, S.; Rygl, K. L. J. [Istituto di Astrofisica e Planetologia Spaziali-INAF, Via Fosso del Cavaliere 100, I-00133 Roma (Italy); Fukui, Y.; Hayakawa, T.; Yamamoto, H. [Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan); Olmi, L. [Osservatorio Astrofisico di Arcetri-INAF, Largo E. Fermi 5, I-50125 Firenze (Italy); Veneziani, M. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Schneider, N.; Piazzo, L. [IRFU/SAp CEA/DSM, Laboratoire AIM CNRS, Universit Paris Diderot, F-91191 Gif-sur-Yvette (France); Ikhenaode, D. [DIET-Dipartimento di Ingegneria dell' Informazione, Elettronica e Telecomunicazioni, Universita di Roma La Sapienza, via Eudossina 18, I-00184 Roma (Italy); Mizuno, A. [Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Onishi, T. [Department of Physical Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Polychroni, D. [Department of Astrophysics, Astronomy and Mechanics, Faculty of Physics, University of Athens, Panepistimiopolis, 15784 Zografos, Athens (Greece); Maruccia, Y., E-mail: davide.elia@iaps.inaf.it [Dipartimento di Matematica e Fisica, Universita del Salento, CP 193, I-73100 Lecce (Italy)
2013-07-20
We present the first Herschel PACS and SPIRE photometric observations in a portion of the outer Galaxy (216. Degree-Sign 5 {approx}< l {approx}< 225. Degree-Sign 5 and -2 Degree-Sign {approx}< b {approx}< 0 Degree-Sign ) as a part of the Hi-GAL survey. The maps between 70 and 500 {mu}m, the derived column density and temperature maps, and the compact source catalog are presented. NANTEN CO(1-0) line observations are used to derive cloud kinematics and distances so that we can estimate distance-dependent physical parameters of the compact sources (cores and clumps) having a reliable spectral energy distribution that we separate into 255 proto-stellar and 688 starless sources. Both typologies are found in association with all the distance components observed in the field, up to {approx}5.8 kpc, testifying to the presence of star formation beyond the Perseus arm at these longitudes. Selecting the starless gravitationally bound sources, we identify 590 pre-stellar candidates. Several sources of both proto- and pre-stellar nature are found to exceed the minimum requirement for being compatible with massive star formation based on the mass-radius relation. For the pre-stellar sources belonging to the Local arm (d {approx}< 1.5 kpc) we study the mass function whose high-mass end shows a power law N(log M){proportional_to}M {sup -1.0{+-}0.2}. Finally, we use a luminosity versus mass diagram to infer the evolutionary status of the sources, finding that most of the proto-stellar sources are in the early accretion phase (with some cases compatible with a Class I stage), while for pre-stellar sources, in general, accretion has not yet started.
Incomplete vs. Complete Fusion at E/A {approx} 4-7 MeV
Singh, Pushpendra P [INFN - Laboratori Nazionali di Legnaro, 1-35020 Legnaro (Italy); Yadav, Abhishek; Sharma, Vijay R; Singh, Devendra P; Gupta, Unnati; Singh, B P; Prasad, R [Accelerator Laboratory, Department of Physics, A. M. University, Aligarh-202 002 (India); Sharma, Manoj K [Physics Department, S. V. College, Aligarh-202 001 (India); Kumar, R; Golda, K S; Singh, R P; Muralithar, S; Bhowmik, R K, E-mail: pushpendrapsingh@gmail.com [NP-Group, Inter-University Accelerator Center, New Delhi-110 067 (India)
2011-02-01
With a view to study onset and strength of incomplete fusion at low projectile energies (i.e., {approx} 4-7 MeV/nucleon) three sets of experiments have been performed in {sup 12}C,{sup 16}O+{sup 169}Tm systems. In first set of experiments, spin-distributions and feeding intensity profiles for xn,{alpha}xn/2{alpha}xn-channels have been measured to figure out associated l-values. The spin-distributions for direct-{alpha}-emitting channels (associated with incomplete fusion) have been found to be distinctly different than that observed for fusion-evaporation (complete fusion) channels. The mean value of driving input angular momenta associated with direct-{alpha}-emitting-channels have been found to be higher than that observed for fusion-evaporation xn/{alpha}-emitting-channels, and increases with direct-{alpha}-multiplicity in forward cone. The second set of experiments has been performed to understand influence of incomplete fusion on complete fusion at these energies. Incomplete fusion strength function has been deduced from the analysis of experimental excitation functions. The third set of experiments deals with the validation of data reduction procedure used to deduce incomplete fusion fraction, and to confirm the fusion incompleteness at slightly above barrier energies. Forward-recoil-ranges of heavy reaction products have been measured and analysed on the basis of break-up fusion model. More than one linear-momentum-transfer components associated with full- and/or partial-fusion of projectile with target nucleus have been observed. Experimental ranges of forward-recoils are found to be in good agreement with that estimated using range-energy formulation. The relative strengths of complete and incomplete fusion components deduced from the analysis of forward-recoil-ranges and excitation functions complement each other. Result presented in this paper conclusively demonstrate substantial incomplete fusion contribution at energy as low as 7% above the barrier.
EVIDENCE FOR COLD ACCRETION: PRIMITIVE GAS FLOWING ONTO A GALAXY AT z {approx} 0.274
Ribaudo, Joseph; Lehner, Nicolas; Christopher Howk, J. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Werk, Jessica K.; Xavier Prochaska, J. [UCO/Lick Observatory, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Tripp, Todd M.; Meiring, Joseph D. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Tumlinson, Jason [Space Telescope Science Institute, Baltimore, MD 21218 (United States)
2011-12-20
We present UV and optical observations from the Cosmic Origins Spectrograph on the Hubble Space Telescope and Keck of a z = 0.27395 Lyman limit system (LLS) seen in absorption against the QSO PG1630+377. We detect H I absorption with log N(H I) = 17.06 {+-} 0.05 as well as Mg II, C III, Si III, and O VI in this system. The column densities are readily explained if this is a multi-phase system, with the intermediate and low ions arising in a very low metallicity ([Mg/H] = -1.71 {+-} 0.06) photoionized gas. We identify via Keck spectroscopy and Large Binocular Telescope imaging a 0.3 L{sub *} star-forming galaxy projected 37 kpc from the QSO at nearly identical redshift (z = 0.27406 and {Delta}v = -26 km s{sup -1}) with near solar metallicity ([O/H] = -0.20 {+-} 0.15). The presence of very low metallicity gas in the proximity of a near-solar metallicity, sub-L{sub *} galaxy strongly suggests that the LLS probes gas infalling onto the galaxy. A search of the literature reveals that such low-metallicity LLSs are not uncommon. We found that 50% (4/8) of the well-studied z {approx}< 1 LLSs have metallicities similar to the present system and show sub-L{sub *} galaxies with {rho} < 100 kpc in those fields where redshifts have been surveyed. We argue that the properties of these primitive LLSs and their host galaxies are consistent with those of cold mode accretion streams seen in galaxy simulations.
Forward recursions and normalizing constant
Guyon, Xavier; Hardouin, Cécile
2009-01-01
Maximum likelihood parameter estimation is frequently replaced by various techniques because of its intractable normalizing constant. In the same way, the literature displays various alternatives for distributions involving such unreachable constants. In this paper, we consider a Gibbs distribution $\\pi $ and present a recurrence formula allowing a recursive calculus of the marginals of $\\pi $ and in the same time its normalizing constant$.$ The numerical performance of this algorithm is eval...
Basic constant of matter world
It was analysed how to gain constant 46 hidden among elementary units of matter world, which is divided into, 1, 2, 4, 8, 16, 8, 4, 2, 1. Here it shows the unity of opposites on philosophy and simple symmetric beauty of mathphysics. The constant specifically shows that scope constant 44 in nuclides layer of matter world and chromosome number of mankind is 23 pairs, which is the highest form of matter motion, the basic cause of existing constant 46 is that matter exists in space-time with 4-dimensions, and it obeys the principle of the most lower energy
Inelastic neutron scattering study on Na{sub x}CoO{sub 2}(x{approx}0.3)
Ohira-Kawamura, Seiko, E-mail: seiko.kawamura@j-parc.j [Academic and Information Board, Ochanomizu University, 2-1-1 Bunkyo-ku, Tokyo 112-8610 (Japan); Nagata, Takashi [Department of Physics, Ochanomizu University, 2-1-1 Bunkyo-ku, Tokyo 112-8610 (Japan); Takeda, Keiko [Graduate School of Humanities and Sciences, Ochanomizu University, 2-1-1 Bunkyo-ku, Tokyo 112-8610 (Japan); Yoshizawa, Hideki [Neutron Science Laboratory, I.S.S.P., University of Tokyo, Tokai, Ibaraki 319-1106 (Japan); Kawano-Furukawa, Hazuki [Graduate School of Humanities and Sciences, Ochanomizu University, 2-1-1 Bunkyo-ku, Tokyo 112-8610 (Japan)
2010-12-15
Inelastic neutron scattering experiments were performed on single crystals of Na{sub x}CoO{sub 2}(x{approx}0.3). The results reveal that an inelastic scattering signal appears at {Delta}E{approx}5.5meV and q {approx} (0 1 0) in the orthorhombic notation. Intensity of the signal decreases with increasing temperature, and disappears above 100 K. The origin of this signal is of magnetic. However, we also found the signal is absent in samples from a different batch at the same T and Q conditions. This indicates that the signal is very sensitive to condition in sample preparation. It might be attributed to Na ion ordering (disordering).
Lisse, C. M. [JHU-APL, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Wyatt, M. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Chen, C. H. [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Morlok, A. [Department of Earth and Planetary Sciences, The Open University, Milton-Keynes (United Kingdom); Watson, D. M.; Manoj, P.; Sheehan, P. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Currie, T. M. [NASA-GSFC, Code 667, Greenbelt, MD 20771 (United States); Thebault, P. [Observatoire de Paris, F-92195 Meudon Principal Cedex (France); Sitko, M. L., E-mail: carey.lisse@jhuapl.edu, E-mail: wyatt@ast.cam.ac.uk, E-mail: cchen@stsci.edu, E-mail: a.morlok@open.ac.uk, E-mail: dmw@pas.rochester.edu, E-mail: manoj@pas.rochester.edu, E-mail: psheeha2@mail.rochester.edu, E-mail: thayne.m.currie@nasa.gov, E-mail: philippe.thebault@obspm.fr, E-mail: sitko@spacescience.org [Space Science Institute, 475 Walnut Street, Suite 205, Boulder, CO 80301 (United States)
2012-03-10
We have analyzed Spitzer and NASA/IRTF 2-35 {mu}m spectra of the warm, {approx}350 K circumstellar dust around the nearby MS star {eta} Corvi (F2V, 1.4 {+-} 0.3 Gyr). The spectra show clear evidence for warm, water- and carbon-rich dust at {approx}3 AU from the central star, in the system's terrestrial habitability zone. Spectral features due to ultra-primitive cometary material were found, in addition to features due to impact produced silica and high-temperature carbonaceous phases. At least 9 Multiplication-Sign 10{sup 18} kg of 0.1-100 {mu}m warm dust is present in a collisional equilibrium distribution with dn/da {approx} a{sup -3.5}, the equivalent of a 130 km radius Kuiper Belt object (KBO) of 1.0 g cm{sup 3} density and similar to recent estimates of the mass delivered to the Earth at 0.6-0.8 Gyr during the late-heavy bombardment. We conclude that the parent body was a Kuiper Belt body or bodies which captured a large amount of early primitive material in the first megayears of the system's lifetime and preserved it in deep freeze at {approx}150 AU. At {approx}1.4 Gyr they were prompted by dynamical stirring of their parent Kuiper Belt into spiraling into the inner system, eventually colliding at 5-10 km s{sup -1} with a rocky planetary body of mass {<=}M{sub Earth} at {approx}3 AU, delivering large amounts of water (>0.1% of M{sub Earth'sOceans}) and carbon-rich material. The Spitzer spectrum also closely matches spectra reported for the Ureilite meteorites of the Sudan Almahata Sitta fall in 2008, suggesting that one of the Ureilite parent bodies was a KBO.
谢海; 郑小珍; 彭小勇
2012-01-01
新型恒压集束管式风力送丝装置是一种采用集束管代替通用树状型分支式、风量自动补偿的风力送丝装置.经过某大型卷烟厂实际应用表明:该装置结构原理简单、风速控制 稳定、运行可靠、节能效果明显.%The new constant pressure cluster device type of tobacco pneumatic conveying equipment, it is a kind of the pipe bundle together instead of the universal tree branch type, air volume to be automatic compensation of tobacco pneumatic conveying equipment. After the practical application of a large cigarette factories ,it showed that has a significant advantage; simple structure, work principle, reliable wind speed control flexible, remarkable energy saving. In order to improve the energy efficiency of important energy production technology level, it is worth in the modern cigarette factories of tobacco pneumatic conveying system of popularization and application.
Europium (III) and americium (III) stability constants with humic acid
The stability constants for tracer concentrations of Eu(III) and Am(III) complexes with a humic acid extracted from a lake-bottom sediment were measured using a solvent extraction system. The organic extractant was di(2-ethylhexyl)-phosphoric acid in toluene while the humate aqueous phase had a constant ionic strength of 0.1 M (NaClO4). Aqueous humic acid concentrations were monitored by measuring uv-visible absorbances at approx.= 380 nm. The total carboxylate capacity of the humic acid was determined by direct potentiometric titration to be 3.86 +- 0.03 meq/g. The humic acid displayed typical characteristics of a polyelectrolyte - the apparent pKsub(a), as well as the calculated metal ion stability constants increased as the degree of ionization (α) increased. The binding data required a fit of two stability constants, β1 and β2, such that for Eu, log β1 = 8.86 α + 4.39, log β2 = 3.55 α + 11.06 while for Am, log β1 = 10.58 α + 3.84, log β2 = 5.32 α + 10.42. With hydroxide, carbonate, and humate as competing ligands, the humate complex associated with the β1 constant is calculated to be the dominant species for the trivalent actinides and lanthanides under conditions present in natural waters. (orig.)
JF151型定速摩擦试验机的研制与应用%Application and design for the JF151 friction tester with constant speed
王振玉; 王铁山; 宋黎
2012-01-01
Based on the JF150 friction tester with constant speed,a JF151 friction tester with constant speed was designed and developed.The accurate calibration value could be obtained using the weights way,and the draught fan could be mounted underneath for improving service life.By adding water tank and relieving lever, the labor intensity of the operator could be reduced.By using the computer to control and test,the tester was in high accuracy even and the test data was accurate.The new tester was Compact in structure and operated easily.The working principle, composing parts,structure parameter,control system and means of the machine are expounded. With the application of the friction material,the structure design of the machine is reasonable with the performance satisfying the testing standard.%在JF150型定速摩擦试验机的基础上,设计并研制JF151型定速摩擦试验机.采用重力砝码式标定,使标定值更准确.风机下置,提高风机的使用寿命.增加水箱和卸载手柄,减轻了操作者的劳动强度.采用计算机进行控制和检测,控制精度更高,试验数据更准确,整体结构紧凑,操作方便.详细阐述了JF151型定速摩擦试验机的工作原理、结构组成及其技术参数,简述了其控制系统组成及其控制方式.该机结构设计合理的,性能优良,完全符合测试标准要求.
Leptonic B- and D-meson decay constants with 2+1 flavors of asqtad fermions
Kronfeld, Andreas S; Simone, James N; Van de Water, Ruth S
2015-01-01
We present the status of our updated D- and B-meson decay-constant analysis, based on the MILC $N_f = 2+1$ asqtad gauge ensembles. Heavy quarks are incorporated using the Wilson clover action with the Fermilab interpretation. This analysis includes ensembles at five lattice spacings from a $\\approx$ 0.045 to 0.15 fm, and light sea-quark masses down to 1/20th of the strange-quark mass. Projected error budgets for ratios of decay constants, in particular between bottom- and charm-meson decay constants, are presented.
Spectrophotometric determination of association constant
Spanget-Larsen, Jens
2016-01-01
Least-squares 'Systematic Trial-and-Error Procedure' (STEP) for spectrophotometric evaluation of association constant (equilibrium constant) K and molar absorption coefficient E for a 1:1 molecular complex, A + B = C, with error analysis according to Conrow et al. (1964). An analysis of the Charg...
Formulas for determining rotational constants
Guelachvili, G.
This document is part of Subvolume B `Linear Triatomic Molecules', Part 9, of Volume 20 `Molecular Constants mostly from Infrared Spectroscopy' of Landolt-Börnstein Group II `Molecules and Radicals'. Part of the introduction, it states formulas for determining rotational constants, band center, band origin, and quadrupole coupling. Specific comments relate to BHO (HBO) and COS (OCS).
The stability of fundamental constants
The tests of the constancy of fundamental constants are tests of the local position invariance and thus of the equivalence principle, at the heart of general relativity. After summarising the links between fundamental constants, gravity, cosmology and metrology, a brief overview of the observational and experimental constraints on their variation is proposed. (authors)
Lopez G, H.; Jimenez R, M.; Solache R, M. [Instituto Nacional de Investigaciones Nucleares, Departamento de Quimica, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Rojas H, A. [Universidad Autonoma Metropolitana, Departamento de Quimica, Area de Quimica Analitica (Mexico)
2001-07-01
The pM{sup '}-pC{sub H} diagrams allowed to determine the saturation and non-saturation zones of Lu(OH){sub 3} in solid phase and those were applied for determining the hydrolysis and lutetium solubility constants, using the radioactive isotope Lu-177. The first constant of hydrolysis was also determined by the potentiometric method in absence of solid phase. (Author)
THE RADIAL DISTRIBUTION OF STAR FORMATION IN GALAXIES AT z {approx} 1 FROM THE 3D-HST SURVEY
Nelson, Erica June; Van Dokkum, Pieter G.; Momcheva, Ivelina; Skelton, Rosalind E.; Leja, Joel [Astronomy Department, Yale University, New Haven, CT 06511 (United States); Brammer, Gabriel [European Southern Observatory, Alonson de Cordova 3107, Casilla 19001, Vitacura, Santiago (Chile); Lundgren, Britt [Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706 (United States); Whitaker, Katherine E. [Astrophysics Science Division, Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Da Cunha, Elisabete; Rix, Hans-Walter; Van der Wel, Arjen [Max Planck Institute for Astronomy (MPIA), Koenigstuhl 17, D-69117, Heidelberg (Germany); Foerster Schreiber, Natascha; Wuyts, Stijn [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Franx, Marijn; Fumagalli, Mattia; Labbe, Ivo; Patel, Shannon [Leiden Observatory, Leiden University, Leiden (Netherlands); Kriek, Mariska [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Schmidt, Kasper B. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
2013-01-20
The assembly of galaxies can be described by the distribution of their star formation as a function of cosmic time. Thanks to the WFC3 grism on the Hubble Space Telescope (HST) it is now possible to measure this beyond the local Universe. Here we present the spatial distribution of H{alpha} emission for a sample of 54 strongly star-forming galaxies at z {approx} 1 in the 3D-HST Treasury survey. By stacking the H{alpha} emission, we find that star formation occurred in approximately exponential distributions at z {approx} 1, with a median Sersic index of n = 1.0 {+-} 0.2. The stacks are elongated with median axis ratios of b/a = 0.58 {+-} 0.09 in H{alpha} consistent with (possibly thick) disks at random orientation angles. Keck spectra obtained for a subset of eight of the galaxies show clear evidence for rotation, with inclination corrected velocities of 90-330 km s{sup -1}. The most straightforward interpretation of our results is that star formation in strongly star-forming galaxies at z {approx} 1 generally occurred in disks. The disks appear to be 'scaled-up' versions of nearby spiral galaxies: they have EW(H{alpha}) {approx} 100 A out to the solar orbit and they have star formation surface densities above the threshold for driving galactic scale winds.
Accurate measurement of electrical power above approx.1 MHz is accomplished by reconstruction of the voltage and current waveforms at a lower frequency using a sampling oscilloscope. The low-frequency waveforms are then multiplied in a 4-quadrant tranconductance-type multiplier module
Reliability concerns with logical constants in Xilinx FPGA designs
Quinn, Heather M [Los Alamos National Laboratory; Graham, Paul [Los Alamos National Laboratory; Morgan, Keith [Los Alamos National Laboratory; Ostler, Patrick [Los Alamos National Laboratory; Allen, Greg [JPL; Swift, Gary [XILINX; Tseng, Chen W [XILINX
2009-01-01
In Xilinx Field Programmable Gate Arrays logical constants, which ground unused inputs and provide constants for designs, are implemented in SEU-susceptible logic. In the past, these logical constants have been shown to cause the user circuit to output bad data and were not resetable through off-line rcconfiguration. In the more recent devices, logical constants are less problematic, though mitigation should still be considered for high reliability applications. In conclusion, we have presented a number of reliability concerns with logical constants in the Xilinx Virtex family. There are two main categories of logical constants: implicit and explicit logical constants. In all of the Virtex devices, the implicit logical constants are implemented using half latches, which in the most recent devices are several orders of magnitudes smaller than configuration bit cells. Explicit logical constants are implemented exclusively using constant LUTs in the Virtex-I and Virtex-II, and use a combination of constant LUTs and architectural posts to the ground plane in the Virtex-4. We have also presented mitigation methods and options for these devices. While SEUs in implicit and some types of explicit logical constants can cause data corrupt, the chance of failure from these components is now much smaller than it was in the Virtex-I device. Therefore, for many cases, mitigation might not be necessary, except under extremely high reliability situations.
Fundamental Constants and Conservation Laws
Roh, Heui-Seol
2001-01-01
This work describes underlying features of the universe such as fundamental constants and cosmological parameters, conservation laws, baryon and lepton asymmetries, etc. in the context of local gauge theories for fundamental forces under the constraint of the flat universe. Conservation laws for fundamental forces are related to gauge theories for fundamental forces, their resulting fundamental constants are quantitatively analyzed, and their possible violations at different energy scales are...
Varying Constants, Gravitation and Cosmology
Jean-Philippe Uzan
2011-03-01
Full Text Available Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. Thus, it is of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, solar system observations, meteorite dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.
Sarma, Garimella,; Comte-Bellot, Geneviève; Faure, Thierry M.
1998-01-01
International audience Software compensation correction for thermal lag of a hot wire in the application of a constant voltage anemometer (CVA) for turbulence measurements in the boundary layer of a supersonic wind tunnel has been demonstrated. The CVA was used with a fixed compensation setting while measuring the in situ thermal lag (time constant) of the hot wire. Using the measured time constant, corrections are applied to the fixed compensation output of the CVA in postprocessing of th...
Bubble growth constants for liquid hydrogen and liquid helium
Bubble growth constants are calculated for liquid H2 and liquid He at various pressures and liquid superheats for spherically symmetric growth using Scrivens' solution (Chem. Eng. Sci.; 10 (1959)). The constants are shown to be applicable to bubble growth at a heated wall during boiling of cryogenic liquids. (author)
Damping constant estimation in magnetoresistive readers
Stankiewicz, Andrzej, E-mail: Andrzej.Stankiewicz@seagate.com; Hernandez, Stephanie [Recording Heads Group, Seagate Technology, Bloomington, Minnesota 55435 (United States)
2015-05-07
The damping constant is a key design parameter in magnetic reader design. Its value can be derived from bulk or sheet film ferromagnetic resonance (FMR) line width. However, dynamics of nanodevices is usually defined by presence of non-uniform modes. It triggers new damping mechanisms and produces stronger damping than expected from traditional FMR. This work proposes a device-level technique for damping evaluation, based on time-domain analysis of thermally excited stochastic oscillations. The signal is collected using a high bandwidth oscilloscope, by direct probing of a biased reader. Recorded waveforms may contain different noise signals, but free layer FMR is usually a dominating one. The autocorrelation function is a reflection of the damped oscillation curve, averaging out stochastic contributions. The damped oscillator formula is fitted to autocorrelation data, producing resonance frequency and damping constant values. Restricting lag range allows for mitigation of the impact of other phenomena (e.g., reader instability) on the damping constant. For a micromagnetically modeled reader, the technique proves to be much more accurate than the stochastic FMR line width approach. Application to actual reader waveforms yields a damping constant of ∼0.03.
From the Rydberg constant to the fundamental constants metrology
This document reviews the theoretical and experimental achievements of the author since the beginning of his scientific career. This document is dedicated to the spectroscopy of hydrogen, deuterium and helium atoms. The first part is divided into 6 sub-sections: 1) the principles of hydrogen spectroscopy, 2) the measurement of the 2S-nS/nD transitions, 3) other optical frequency measurements, 4) our contribution to the determination of the Rydberg constant, 5) our current experiment on the 1S-3S transition, 6) the spectroscopy of the muonic hydrogen. Our experiments have improved the accuracy of the Rydberg Constant by a factor 25 in 15 years and we have achieved the first absolute optical frequency measurement of a transition in hydrogen. The second part is dedicated to the measurement of the fine structure constant and the last part deals with helium spectroscopy and the search for optical references in the near infrared range. (A.C.)
Effective cosmological constant induced by stochastic fluctuations of Newton's constant
de Cesare, Marco; Sakellariadou, Mairi
2016-01-01
We consider implications of the microscopic dynamics of spacetime for the evolution of cosmological models. We argue that quantum geometry effects may lead to stochastic fluctuations of the gravitational constant, which is thus considered as a macroscopic effective dynamical quantity. Consistency with Riemannian geometry entails the presence of a time-dependent dark energy term in the modified field equations, which can be expressed in terms of the dynamical gravitational constant. We suggest that the late-time accelerated expansion of the Universe may be ascribed to quantum fluctuations in the geometry of spacetime rather than the vacuum energy from the matter sector.
Effective cosmological constant induced by stochastic fluctuations of Newton's constant
de Cesare, Marco; Lizzi, Fedele; Sakellariadou, Mairi
2016-09-01
We consider implications of the microscopic dynamics of spacetime for the evolution of cosmological models. We argue that quantum geometry effects may lead to stochastic fluctuations of the gravitational constant, which is thus considered as a macroscopic effective dynamical quantity. Consistency with Riemannian geometry entails the presence of a time-dependent dark energy term in the modified field equations, which can be expressed in terms of the dynamical gravitational constant. We suggest that the late-time accelerated expansion of the Universe may be ascribed to quantum fluctuations in the geometry of spacetime rather than the vacuum energy from the matter sector.
How fundamental are fundamental constants?
Duff, M. J.
2015-01-01
I argue that the laws of physics should be independent of one's choice of units or measuring apparatus. This is the case if they are framed in terms of dimensionless numbers such as the fine structure constant, ?. For example, the standard model of particle physics has 19 such dimensionless parameters whose values all observers can agree on, irrespective of what clock, rulers or scales? they use to measure them. Dimensional constants, on the other hand, such as ?, c, G, e and k ?, are merely human constructs whose number and values differ from one choice of units to the next. In this sense, only dimensionless constants are 'fundamental'. Similarly, the possible time variation of dimensionless fundamental 'constants' of nature is operationally well defined and a legitimate subject of physical enquiry. By contrast, the time variation of dimensional constants such as ? or ? on which a good many (in my opinion, confusing) papers have been written, is a unit-dependent phenomenon on which different observers might disagree depending on their apparatus. All these confusions disappear if one asks only unit-independent questions. We provide a selection of opposing opinions in the literature and respond accordingly.
How fundamental are fundamental constants?
Duff, M J
2014-01-01
I argue that the laws of physics should be independent of one's choice of units or measuring apparatus. This is the case if they are framed in terms of dimensionless numbers such as the fine structure constant, alpha. For example, the Standard Model of particle physics has 19 such dimensionless parameters whose values all observers can agree on, irrespective of what clock, rulers, scales... they use to measure them. Dimensional constants, on the other hand, such as h, c, G, e, k..., are merely human constructs whose number and values differ from one choice of units to the next. In this sense only dimensionless constants are "fundamental". Similarly, the possible time variation of dimensionless fundamental "constants" of nature is operationally well-defined and a legitimate subject of physical enquiry. By contrast, the time variation of dimensional constants such as c or G on which a good many (in my opinion, confusing) papers have been written, is a unit-dependent phenomenon on which different observers might...
The 1% concordance Hubble constant
The determination of the Hubble constant has been a central goal in observational astrophysics for nearly a hundred years. Extraordinary progress has occurred in recent years on two fronts: the cosmic distance ladder measurements at low redshift and cosmic microwave background (CMB) measurements at high redshift. The CMB is used to predict the current expansion rate through a best-fit cosmological model. Complementary progress has been made with baryon acoustic oscillation (BAO) measurements at relatively low redshifts. While BAO data do not independently determine a Hubble constant, they are important for constraints on possible solutions and checks on cosmic consistency. A precise determination of the Hubble constant is of great value, but it is more important to compare the high and low redshift measurements to test our cosmological model. Significant tension would suggest either uncertainties not accounted for in the experimental estimates or the discovery of new physics beyond the standard model of cosmology. In this paper we examine in detail the tension between the CMB, BAO, and cosmic distance ladder data sets. We find that these measurements are consistent within reasonable statistical expectations and we combine them to determine a best-fit Hubble constant of 69.6 ± 0.7 km s–1 Mpc–1. This value is based upon WMAP9+SPT+ACT+6dFGS+BOSS/DR11+H 0/Riess; we explore alternate data combinations in the text. The combined data constrain the Hubble constant to 1%, with no compelling evidence for new physics.
Turner, Monica L; Crain, Robert A; Theuns, Tom; Wendt, Martin
2016-01-01
We study the $z\\approx3.5$ intergalactic medium (IGM) by comparing new, very high-quality absorption spectra of eight QSOs with $\\langle z_{\\rm QSO} \\rangle=3.75$, to virtual observations of the EAGLE cosmological hydrodynamical simulations. We employ the pixel optical depth method to study how the absorption of one ion varies as a function of another, and uncover strong correlations between various combinations of HI, CIII, CIV, SiIII, SiIV, and OVI. We find good agreement between the simulated and observed median optical depth relations of OVI(HI), CIII(CIV) and SiIII(SiIV). However, the observed median optical depths for the CIV(HI) and SiIV(HI) relations are higher than those measured from the mock spectra. The discrepancy increases from up to $\\approx0.1$ dex at $\\tau_{\\rm HI}=1$ to $\\approx1$ dex at $\\tau_{\\rm HI}=10^2$, where we are likely probing dense regions at small galactocentric distances. To try to uncover the origin of this discrepancy, we invoke (a) different models for the ionizing background...
Learning Read-constant Polynomials of Constant Degree modulo Composites
Chattopadhyay, Arkadev; Gavaldá, Richard; Hansen, Kristoffer Arnsfelt;
2011-01-01
known to be learnable in any reasonable learning model. In this paper, we provide a deterministic polynomial time algorithm for learning Boolean functions represented by polynomials of constant degree over arbitrary finite rings from membership queries, with the additional constraint that each variable...
Nez, F
2005-06-15
This document reviews the theoretical and experimental achievements of the author since the beginning of his scientific career. This document is dedicated to the spectroscopy of hydrogen, deuterium and helium atoms. The first part is divided into 6 sub-sections: 1) the principles of hydrogen spectroscopy, 2) the measurement of the 2S-nS/nD transitions, 3) other optical frequency measurements, 4) our contribution to the determination of the Rydberg constant, 5) our current experiment on the 1S-3S transition, 6) the spectroscopy of the muonic hydrogen. Our experiments have improved the accuracy of the Rydberg Constant by a factor 25 in 15 years and we have achieved the first absolute optical frequency measurement of a transition in hydrogen. The second part is dedicated to the measurement of the fine structure constant and the last part deals with helium spectroscopy and the search for optical references in the near infrared range. (A.C.)
Foot, R.; Volkas, R. R.
2003-01-01
The cosmological dust has begun to settle. A likely picture is a universe comprised (predominantly) of three components: ordinary baryons ($\\Omega_B \\approx 0.05$), non-baryonic dark matter ($\\Omega_{Dark} \\approx 0.22$) and dark energy ($\\Omega_{\\Lambda} \\approx 0.7$). We suggest that the observed similarity of the abundances of ordinary baryons and non-baryonic dark matter ($\\Omega_{B}/\\Omega_{Dark} \\approx 0.20$) hints at an underlying similarity between the fundamental properties of ordin...
Non-equivalent methylenic protons, with respect to an asymmetric center, have been observed in the n.m.r. spectra of some three- and tetra-coordinated phosphorus compounds. The analysis of these spectra yield the following results: in the studied secondary phosphines, the inversion rate at the phosphorus atom is slow on the n.m.r. time scale; the geminal coupling constant, for a free-rotating methylene group attached to a phosphorus atom, is negative; in phosphines the non equivalence of methylenic protons reveals two 2JP-C-H coupling constants which differ by about 5 Hz. This result is in agreement with previous studies on cyclic phosphines. In phosphine oxides, the 2JP-C-H values are negative. The 3JH-P-C-H coupling constant is positive in both phosphines and phosphine oxides. In phosphines, the non-equivalent methylenic protons exhibit two nearly equal values for this coupling constant. (author)
On constant elasticities of demand
Andrés Vázquez
1998-01-01
While the Slutsky matrix and duality theory have been used to establish that constant elasticity demand functions imply unitary income elasticities, zero cross price elasticities and own price elasticities equal to minus one, this note shows that these results can also be straightforwardly derived from the simple assumption that demand functions satisfy the budget constraint with strict equality.
Constant Proportion Debt Obligations (CPDOs)
Cont, Rama; Jessen, Cathrine
2012-01-01
Constant Proportion Debt Obligations (CPDOs) are structured credit derivatives that generate high coupon payments by dynamically leveraging a position in an underlying portfolio of investment-grade index default swaps. CPDO coupons and principal notes received high initial credit ratings from the...
Kerma constant of gamma radiation
The values are tabulated of the gamma kerma constant for 106 radionuclides and an energy threshold of δ=0, 10, 20 and 30 keV. The calculated values will be useful in gamma radiation protection for ease of calculation of the kerma rate from a point radiation source. The study was required in view of the consistent introduction of SI units. (author)
Exponential Decay of Expansive Constants
Sun, Peng
2011-01-01
A map $f$ on a compact metric space is expansive if and only if $f^n$ is expansive. We study the exponential rate of decay of the expansive constant of $f^n$. A major result is that this rate times box dimension bounds topological entropy.
The 1% concordance Hubble constant
Bennett, C. L.; Larson, D.; Weiland, J. L. [Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Hinshaw, G., E-mail: cbennett@jhu.edu [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada)
2014-10-20
The determination of the Hubble constant has been a central goal in observational astrophysics for nearly a hundred years. Extraordinary progress has occurred in recent years on two fronts: the cosmic distance ladder measurements at low redshift and cosmic microwave background (CMB) measurements at high redshift. The CMB is used to predict the current expansion rate through a best-fit cosmological model. Complementary progress has been made with baryon acoustic oscillation (BAO) measurements at relatively low redshifts. While BAO data do not independently determine a Hubble constant, they are important for constraints on possible solutions and checks on cosmic consistency. A precise determination of the Hubble constant is of great value, but it is more important to compare the high and low redshift measurements to test our cosmological model. Significant tension would suggest either uncertainties not accounted for in the experimental estimates or the discovery of new physics beyond the standard model of cosmology. In this paper we examine in detail the tension between the CMB, BAO, and cosmic distance ladder data sets. We find that these measurements are consistent within reasonable statistical expectations and we combine them to determine a best-fit Hubble constant of 69.6 ± 0.7 km s{sup –1} Mpc{sup –1}. This value is based upon WMAP9+SPT+ACT+6dFGS+BOSS/DR11+H {sub 0}/Riess; we explore alternate data combinations in the text. The combined data constrain the Hubble constant to 1%, with no compelling evidence for new physics.
WHY IS THE SOLAR CONSTANT NOT A CONSTANT?
In order to probe the mechanism of variations of the solar constant on the inter-solar-cycle scale, the total solar irradiance (TSI; the so-called solar constant) in the time interval of 1978 November 7 to 2010 September 20 is decomposed into three components through empirical mode decomposition and time-frequency analyses. The first component is the rotation signal, counting up to 42.31% of the total variation of TSI, which is understood to be mainly caused by large magnetic structures, including sunspot groups. The second is an annual-variation signal, counting up to 15.17% of the total variation, the origin of which is not known at this point in time. Finally, the third is the inter-solar-cycle signal, counting up to 42.52%, which is inferred to be caused by the network magnetic elements in quiet regions, whose magnetic flux ranges from (4.27-38.01) × 1019 Mx.
Production in constant evolution; Produccion en constante evolucion
Lozano, T.
2009-07-01
The Cofrentes Nuclear Power Plant now has 25 years of operation behind it: a quarter century adding value and demonstrating the reasons why it is one of the most important energy producing facilities in the Spanish power market. Particularly noteworthy is the enterprising spirit of the plant, which has strived to continuously improve with the large number of modernization projects that it has undertaken over the past 25 years. The plant has constantly evolved thanks to the amount of investments made to improve safety and reliability and the perseverance to stay technologically up to date. Efficiency, training and teamwork have been key to the success of the plant over these 25 years of constant change and progress. (Author)
Scales Set by the Cosmological Constant
Balaguera-Antolinez, A; Nowakowski, M; Balaguera-Antolinez, Andres; Boehmer, Christian G.; Nowakowski, Marek
2006-01-01
The cosmological constant sets certain scales important in cosmology. We show that \\Lambda in conjunction with other parameters like the Schwarzschild radius leads to scales relevant not only for cosmological but also for astrophysical applications. Of special interest is the extension of orbits and velocity of test particles traveling over Mpc distances. We will show that there exists a lower and an upper cut-off on the possible velocities of test particles. For a test body moving in a central gravitational field \\Lambda enforces a maximal value of the angular momentum if we insist on bound orbits of the test body which move at a distance larger than the Schwarzschild radius.
Computing upper bounds on Friedrichs' constant
Vejchodský, Tomáš
Prague : Institute of Math ematics AS CR, 2012 - (Brandts, J.; Chleboun, J.; Korotov, S.; Segeth, K.; Šístek, J.; Vejchodský, T.), s. 278-289 ISBN 978-80-85823-60-8. [Applications of Math ematics 2012. Prague (CZ), 02.05.2012-05.05.2012] R&D Projects: GA AV ČR IAA100760702 Institutional support: RVO:67985840 Keywords : Friedrichs' constant Subject RIV: BA - General Math ematics http://www. math .cas.cz/~am2012/proceedings/contributions/vejchodsky.pdf
Maris, P; Tandy, P C
1998-01-01
Independent of assumptions about the form of the quark-antiquark scattering kernel we derive the explicit relation between the pion Bethe-Salpeter amplitude, Gamma_pi, and the quark propagator in the chiral limit; Gamma_pi necessarily involves a non-negligible gamma_5 gamma.P term (P is the pion four-momentum). We also obtain exact expressions for the pion decay constant, f_pi, and mass, both of which depend on Gamma_pi; and demonstrate the equivalence between f_pi and the pion Bethe-Salpeter normalisation constant in the chiral limit. We stress the importance of preserving the axial-vector Ward-Takahashi identity in any study of the pion itself, and in any study whose goal is a unified understanding of the properties of the pion and other hadronic bound states.
Wormholes and the cosmological constant
We review Coleman's wormhole mechanism for the vanishing of the cosmological constant. We show that in a minisuperspace model wormhole-connected universes dominate the path integral. We also provide evidence that the euclidean path integral over geometries with spherical topology is unstable with respect to formation of infinitely many wormhole-connected 4-spheres. Consistency is restored by summing over all topologies, which leads to Coleman's result. Coleman's argument for determination of other parameters is reviewed and applied to the mass of the pion. A discouraging result is found that the pion mass is driven to zero. We also consider qualitatively the implications of the wormhole theory for cosmology. We argue that a small number of universes containing matter and energy may exist in contact with infinitely many cold and empty universes. Contact with the cold universes insures that the cosmological constant in the warm ones is zero. (orig.)
Three pion nucleon coupling constants
Arriola, E Ruiz; Perez, R Navarro
2016-01-01
There exist four pion nucleon coupling constants, $f_{\\pi^0, pp}$, $-f_{\\pi^0, nn}$, $f_{\\pi^+, pn} /\\sqrt{2}$ and $ f_{\\pi^-, np} /\\sqrt{2}$ which coincide when up and down quark masses are identical and the electron charge is zero. While there is no reason why the pion-nucleon-nucleon coupling constants should be identical in the real world, one expects that the small differences might be pinned down from a sufficiently large number of independent and mutually consistent data. Our discussion provides a rationale for our recent determination $$f_p^2 = 0.0759(4) \\, , \\quad f_{0}^2 = 0.079(1) \\,, \\quad f_{c}^2 = 0.0763(6) \\, , $$ based on a partial wave analysis of the $3\\sigma$ self-consistent nucleon-nucleon Granada-2013 database comprising 6713 published data in the period 1950-2013.
McQuinn, Matthew; O' Leary, Ryan M. [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
2012-11-20
Recently, Tseliakhovich and Hirata showed that during the cosmic Dark Ages the baryons were typically moving supersonically with respect to the dark matter with a spatially variable Mach number. Such supersonic motion may source shocks that inhomogeneously heat the universe. This motion may also suppress star formation in the first halos. Even a small amount of coupling of the 21 cm signal to this motion has the potential to vastly enhance the 21 cm brightness temperature fluctuations at 15 {approx}< z {approx}< 40, as well as to imprint distinctive acoustic oscillations in this signal. We present estimates for the size of this coupling, which we calibrate with a suite of cosmological simulations of the high-redshift universe using the GADGET and Enzo codes. Our simulations, discussed in detail in a companion paper, are initialized to self-consistently account for gas pressure and the dark matter-baryon relative velocity, v {sub bc} (in contrast to prior simulations). We find that the supersonic velocity difference dramatically suppresses structure formation on 10-100 comoving kpc scales, it sources shocks throughout the universe, and it impacts the accretion of gas onto the first star-forming minihalos (even for halo masses as large as 10{sup 7} M {sub Sun }). However, prior to reheating by astrophysical sources, we find that the v {sub bc}-sourced temperature fluctuations can contribute only as much as Almost-Equal-To 10% of the fluctuations in the 21 cm signal. We do find that v {sub bc} in certain scenarios could source an O(1) component in the power spectrum of the 21 cm background on observable scales via the X-ray (but not ultraviolet) backgrounds produced once the first stars formed. In a scenario in which {approx}10{sup 6} M {sub Sun} minihalos reheated the universe via their X-ray backgrounds, we find that the pre-reionization 21 cm signal would be larger than previously anticipated and exhibit more significant acoustic features. Such features would be a
Henry's law constants of polyols
Compernolle, S.; J.-F. Müller
2014-01-01
Henry's law constants (HLC) are derived for several polyols bearing between 2 and 6 hydroxyl groups, based on literature data for water activity, vapour pressure and/or solubility. While deriving HLC and depending on the case, also infinite dilution activity coefficients (IDACs), solid state vapour pressures or activity coefficient ratios are obtained as intermediate results. An error analysis on the intermediate quantities and the obtained HLC is included....
Henry's law constants of polyols
Compernolle, S.; J.-F. Müller
2014-01-01
Henry's law constants (HLC) are derived for several polyols bearing between 2 and 6 hydroxyl groups, based on literature data for water activity, vapour pressure and/or solubility. Depending on the case, infinite dilution activity coefficients (IDACs), solid state pressures or activity coefficient ratios are obtained as intermediary results. For most compounds, these are the first values reported, while others compare favourably with literature data in most ...
Planck's constant measurement for dummies
Damyanov, Desislav S; Ilieva, Simona I; Gourev, Vassil N; Yordanov, Vasil G; Mishonov, Todor M
2015-01-01
A simple experimental setup for measuring the Planck's constant, using Landauer quantization of the conductance of touching gold wires, is described. It consists of two gold wires with thickness of 500 micron and 1.5cm length, and a fast operational amplifier. The setup costs less than \\$30 and can be realized in every teaching laboratory in 10 days. The usage of oscilloscope is required.
Neutron Scattering and Elastic Constants
Elastic constants of crystals obtained from neutron scattering techniques at frequencies, ω, of the order of 1012 cps, are frequently compared with those obtained with ultrasonic techniques for which ω 10 cps. If the normal modes of vibration of the crystal did not interact with each other or with other excitations in the crystal, these elastic constants would be identical. In a real crystal, however, interactions exist, and these lead to different behaviour, depending on whether the elastic wave propagates in a collision-free, ωτ >> 1, mode or a collision-dominated ωτ 3 have demonstrated this difference. In piezoelectric crystals τ is related to the time required for the electric polarization to follow the elastic wave. At frequencies so high that the electric polarization cannot follow the elastic wave, experiments on DKDP have shown that the elastic constants do not exhibit the anormaly present at low frequencies. Similar behaviour is expected to occur near many phase transitions which show anomalous elastic behaviour. Analogous, but probably smaller, effects occur through the interactions of elastic waves with conduction electrons in metals and with the spins in magnetic materials. (author)
Cosmology with New Astrophysical Constants
Alfonso-Faus, Antonio
2008-01-01
It is shown that Einstein field equations give two solutions for cosmology. The first one is the standard well known representative of the present status of cosmology. We identify it with the local point of view of a flat Universe with the values for the cosmological omega parameters (k = 0, lambda = 2/3, m = 1/3). The second one is a new one that we identify with a cosmic point of view, as given by free photons, neutrinos, tachyons and gravity quanta. We apply a wave to particle technique to find the matter propagation equation. Then we prove that all gravitational radii are constant, regardless of the possible time variations of the physical properties like the speed of light c, the gravitational constant G or the mass m of fundamental particles. We find two cosmological constants, c^3 /G and mc, with the condition that the field equations be derived from the action principle. With this result, and the integration of the Bianchi identity, we prove the existence of the two solutions for cosmology. We then va...
Alternative set of defining constants for redefinition of four SI units
Khruschov, V. V.
2016-01-01
We discuss different sets of defining constants, fixed values of which are considered in connection with the transition to new definitions of four SI units (the kilogram, the mole, the ampere, and the kelvin). The notion of constant's order in a given system of units is suggested. We propose an alternative set of fixed constants applicable for new definitions of the four SI units. We analyse and discuss in detail the set, which consists of the Planck constant, the Avogadro constant, the Boltz...
A Luminosity Function of Ly(alpha)-Emitting Galaxies at Z [Approx. Equal to] 4.5(Sup 1),(Sup 2)
Dawson, Steve; Rhoads, James E.; Malhotra, Sangeeta; Stern, Daniel; Wang, JunXian; Dey, Arjun; Spinrad, Hyron; Jannuzi, Buell T.
2007-01-01
We present a catalog of 59 z [approx. equal to] 4:5 Ly(alpha)-emitting galaxies spectroscopically confirmed in a campaign of Keck DEIMOS follow-up observations to candidates selected in the Large Are (LALA) narrowband imaging survey.We targeted 97 candidates for spectroscopic follow-up; by accounting for the variety of conditions under which we performed spectroscopy, we estimate a selection reliability of approx.76%. Together with our previous sample of Keck LRIS confirmations, the 59 sources confirmed herein bring the total catalog to 73 spectroscopically confirmed z [approx. equal to] 4:5 Ly(alpha)- emitting galaxies in the [approx. equal to] 0.7 deg(exp 2) covered by the LALA imaging. As with the Keck LRIS sample, we find that a nonnegligible fraction of the co rest-frame equivalent widths (W(sub lambda)(sup rest)) that exceed the maximum predicted for normal stellar populations: 17%-31%(93%confidence) of the detected galaxies show (W(sub lambda)(sup rest)) 12%-27% (90% confidence) show (W(sub lambda)(sup rest)) > 240 A. We construct a luminosity function of z [approx. equal to] 4.5 Ly(alpha) emission lines for comparison to Ly(alpha) luminosity function alpha) luminosity function evolution from z [approx. equal to] 3 to z [approx. equal to] 6. This result supports the conclusion that the intergalactic me largely reionized from the local universe out to z [approx. equal to] 6.5. It is somewhat at odds with the pronounced drop in the cosmic star formation rate density recently measured between z approx. 3 an z approx. 6 in continuum-selected Lyman-break galaxies, and therefore potentially sheds light on the relationship between the two populations.
Mohr, Peter
2015-01-01
A simple reduction scheme using so-called reduced energies $E_{\\rm{red}}$ and reduced cross sections $\\sigma_{\\rm{red}}$ allows the comparison of heavy-ion induced reaction cross sections for a broad range of masses of projectile and target and over a wide energy range. A global behavior has been found for strongly bound projectiles whereas much larger reduced cross sections have been observed for weakly bound and halo projectiles. It has been shown that this simple reduction scheme works also well for $\\alpha$-particle induced reactions on heavy target nuclei, but very recently significant deviations have been seen for $\\alpha$+$^{33}$S and $\\alpha$+$^{23}$Na. Motivated by these unexpected discrepancies, the present study analyses $\\alpha$-induced reaction cross sections for targets with masses $A \\approx 20-50$. The study shows that the experimental data for $\\alpha$-induced reactions on nuclei with $A \\approx 20-50$ deviate slightly from the global behavior of reduced cross sections. However, in general th...
A $\\mathcal{M}\\approx3$ shock in `El Gordo' cluster and the origin of the radio relic
Botteon, A; Brunetti, G; Kale, R
2016-01-01
We present an X-ray and radio study of the famous `El Gordo', a massive and distant ($z=0.87$) galaxy cluster. In the deep (340 ks) Chandra observation, the cluster appears with an elongated and cometary morphology, a sign of its current merging state. The GMRT radio observations at 610 MHz reveal the presence of a radio halo which remarkably overlaps the X-ray cluster emission and connects a couple of radio relics. We detect a strong shock ($\\mathcal{M}\\approx3$) in the NW periphery of the cluster, co-spatially located with the radio relic. This is the most distant ($z=0.87$) and one of the strongest shock detected in a galaxy cluster. This work supports the relic-shock connection and allows to investigate the origin of these radio sources in a uncommon regime of $\\mathcal{M}\\approx3$. For this particular case we found that shock acceleration from the thermal pool is a viable possibility.
Newman, Sarah F.; Genzel, Reinhard [Department of Astronomy, Campbell Hall, University of California, Berkeley, CA 94720 (United States); Foerster Schreiber, Natascha M.; Buschkamp, Peter; Davies, Ric; Eisenhauer, Frank; Kurk, Jaron; Lutz, Dieter [Max-Planck-Institut fuer extraterrestrische Physik (MPE), Giessenbachstr. 1, D-85748 Garching (Germany); Shapiro Griffin, Kristen [Space Sciences Research Group, Northrop Grumman Aerospace Systems, Redondo Beach, CA 90278 (United States); Mancini, Chiara; Renzini, Alvio [Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, Padova I-35122 (Italy); Lilly, Simon J.; Carollo, C. Marcella; Peng, Yingjie [Institute of Astronomy, Department of Physics, Eidgenoessische Technische Hochschule, ETH Zuerich CH-8093 (Switzerland); Bouche, Nicolas [Universite de Toulouse, UPS-OMP, IRAP, Toulouse (France); Burkert, Andreas [Universitaets-Sternwarte Ludwig-Maximilians-Universitaet (USM), Scheinerstr. 1, Muenchen D-81679 (Germany); Cresci, Giovanni [Istituto Nazionale di Astrofisica Osservatorio Astronomico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze (Italy); Genel, Shy [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hicks, Erin K. S. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Naab, Thorsten, E-mail: sfnewman@berkeley.edu [Max-Planck Institute for Astrophysics, Karl Schwarzschildstrasse 1, D-85748 Garching (Germany); and others
2013-04-20
We analyze the spectra, spatial distributions, and kinematics of H{alpha}, [N II], and [S II] emission in a sample of 38, z {approx} 2.2 UV/optically selected star-forming galaxies (SFGs) from the SINS and zC-SINF surveys, 34 of which were observed in the adaptive optics mode of SINFONI and 30 of those contain data presented for the first time here. This is supplemented by kinematic data from 43 z {approx} 1-2.5 galaxies from the literature. None of these 81 galaxies is an obvious major merger. We find that the kinematic classification of high-z SFGs as ''dispersion dominated'' or ''rotation dominated'' correlates most strongly with their intrinsic sizes. Smaller galaxies are more likely ''dispersion-dominated'' for two main reasons: (1) the rotation velocity scales linearly with galaxy size but intrinsic velocity dispersion does not depend on size or may even increase in smaller galaxies, and as such, their ratio is systematically lower for smaller galaxies, and (2) beam smearing strongly decreases large-scale velocity gradients and increases observed dispersion much more for galaxies with sizes at or below the resolution. Dispersion-dominated SFGs may thus have intrinsic properties similar to ''rotation-dominated'' SFGs, but are primarily more compact, lower mass, less metal enriched, and may have higher gas fractions, plausibly because they represent an earlier evolutionary state.
Proceedings of the specialists' meeting on reactor group constants
This report is the Proceedings of the Specialists' Meeting on Reactor Group Constants. The meeting was held on February 22-23, 2001 at Tokai Research Establishment of Japan Atomic Energy Research Institute with the participation of 59 specialists. The evaluation work for JENDL-3.3 is going on for the publication in a short time. The processing JENDL-3.3 file to make reactor group constants is needed when it is used in application fields. In the meeting, the present status of the reactor group constants was reviewed and the issues relating to them were discussed in such fields as thermal reactor, criticality safety, fast reactor, high energy region, burn-up calculation and radiation shielding. At the final session in the meeting, standardization of reactor group constants was discussed and the need of the reference group constants was confirmed by the participants. The 11 of the presented papers are indexed individually. (J.P.N.)
Alternative set of defining constants for redefinition of four SI units
Khruschov, V V
2016-01-01
We discuss different sets of defining constants, fixed values of which are considered in connection with the transition to new definitions of four SI units (the kilogram, the mole, the ampere, and the kelvin). The notion of constant's order in a given system of units is suggested. We propose an alternative set of fixed constants applicable for new definitions of the four SI units. We analyse and discuss in detail the set, which consists of the Planck constant, the Avogadro constant, the Boltzmann constant and the magnetic constant.
Maris, P.; Roberts, C. D.; Tandy, P. C.
1997-01-01
Independent of assumptions about the form of the quark-antiquark scattering kernel we derive the explicit relation between the pion Bethe-Salpeter amplitude, Gamma_pi, and the quark propagator in the chiral limit; Gamma_pi necessarily involves a non-negligible gamma_5 gamma.P term (P is the pion four-momentum). We also obtain exact expressions for the pion decay constant, f_pi, and mass, both of which depend on Gamma_pi; and demonstrate the equivalence between f_pi and the pion Bethe-Salpeter...
Hydrodynamic constants from cosmic censorship
We study a gravity dual of Bjorken flow of N=4 SYM-theory plasma. We point out that the cosmic censorship hypothesis may explain why the regularity of the dual geometry constrains the hydrodynamic constants. We also investigate the apparent horizon of the dual geometry. We find that the dual geometry constructed on Fefferman-Graham (FG) coordinates is not appropriate for examination of the apparent horizon since the coordinates do not cover the trapped region. However, the preliminary analysis on FG coordinates suggests that the location of the apparent horizon is very sensitive to the hydrodynamic parameters. (author)
Exact constants in approximation theory
Korneichuk, N
1991-01-01
This book is intended as a self-contained introduction for non-specialists, or as a reference work for experts, to the particular area of approximation theory that is concerned with exact constants. The results apply mainly to extremal problems in approximation theory, which in turn are closely related to numerical analysis and optimization. The book encompasses a wide range of questions and problems: best approximation by polynomials and splines; linear approximation methods, such as spline-approximation; optimal reconstruction of functions and linear functionals. Many of the results are base
Markov constant and quantum instabilities
Pelantová, Edita; Starosta, Štěpán; Znojil, Miloslav
2016-04-01
For a qualitative analysis of spectra of certain two-dimensional rectangular-well quantum systems several rigorous methods of number theory are shown productive and useful. These methods (and, in particular, a generalization of the concept of Markov constant known in Diophantine approximation theory) are shown to provide a new mathematical insight in the phenomenologically relevant occurrence of anomalies in the spectra. Our results may inspire methodical innovations ranging from the description of the stability properties of metamaterials and of certain hiddenly unitary quantum evolution models up to the clarification of the mechanisms of occurrence of ghosts in quantum cosmology.
Henry's law constants of polyols
S. Compernolle
2014-05-01
Full Text Available Henry's law constants (HLC are derived for several polyols bearing between 2 and 6 hydroxyl groups, based on literature data for water activity, vapour pressure and/or solubility. Depending on the case, infinite dilution activity coefficients (IDACs, solid state pressures or activity coefficient ratios are obtained as intermediary results. For most compounds, these are the first values reported, while others compare favourably with literature data in most cases. Using these values and those from a previous work (Compernolle and Müller, 2014, an assessment is made on the partitioning of polyols, diacids and hydroxy acids to droplet and aqueous aerosol.
The big constant out, the small constant in
Some time ago, Tseytlin has made an original and unusual proposal for an action that eliminates an arbitrary cosmological constant. The form of the proposed action, however, is strongly modified by gravity loop effects, ruining its benefit. Here I discuss an embedding of Tseytlin's action into a broader context, that enables to control the loop effects. The broader context is another universe, with its own metric and dynamics, but only globally connected to ours. One possible Lagrangian for the other universe is that of unbroken AdS supergravity. A vacuum energy in our universe does not produce any curvature for us, but instead increases or decreases the AdS curvature in the other universe. I comment on how to introduce the accelerated expansion in this framework in a technically natural way, and consider the case where this is done by the self-accelerated solutions of massive gravity and its extensions
Computing the Gromov hyperbolicity constant of a discrete metric space
Ismail, Anas
2012-07-01
Although it was invented by Mikhail Gromov, in 1987, to describe some family of groups[1], the notion of Gromov hyperbolicity has many applications and interpretations in different fields. It has applications in Biology, Networking, Graph Theory, and many other areas of research. The Gromov hyperbolicity constant of several families of graphs and geometric spaces has been determined. However, so far, the only known algorithm for calculating the Gromov hyperbolicity constant of a discrete metric space is the brute force algorithm with running time O (n4) using the four- point condition. In this thesis, we first introduce an approximation algorithm which calculates a O (log n)-approximation of the hyperbolicity constant , based on a layering approach, in time O (n2), where n is the number of points in the metric space. We also calculate the fixed base point hyperbolicity constant r for a fixed point r using a (max; min)matrix multiplication algorithm by Duan in time O (n2:688) [2]. We use this result to present a 2-approximation algorithm for calculating the hyperbolicity constant in time O (n2:688). We also provide an exact algorithm to compute the hyperbolicity constant in time O (n3:688) for a discrete metric space. We then present some partial results we obtained for designing some approximation algorithms to compute the hyperbolicity constant.
Kepler's Constant and WDS Orbit
Siregar, S
2012-01-01
The aim of this work are to find a Kepler's constant by using polynomial regression of the angular separation \\rho = \\rho(t) and the position angle \\theta = \\theta(t). The Kepler's constant obtained is used to derive the element of orbit. As a case study the angular separation and the position angle of the WDS 00063 +5826 and the WDS 04403-5857 were investigated. For calculating the element of orbit the Thiele-Innes van den Bos method is used. The rough data of the angular separation \\rho(t) and the position angle \\theta(t) are taken from the US Naval Observatory, Washington. This work also presents the masses and absolute bolometric magnitudes of each star.These stars include into the main-sequence stars with the spectral class G5V for WDS04403-5857and the type of spectrum G3V for WDS 00063+5826. The life time of the primary star and the secondary star of WDS 04403-5857 nearly equal to 20 Gyr. The life time of the primary star and the secondary star of WDS 00063+5826 are 20 Gyr and 19 Gyr, respectively.
Mohr, Peter
2016-01-01
In a recent review it was shown that the cross sections of $\\alpha$-induced reactions in the $A \\approx 20 - 50$ mass range follow a general and smooth trend in most cases. For comparison of cross sections of different targets at various energies the method of reduced cross sections $\\sigma_{\\rm{red}}$ and reduced energies $E_{\\rm{red}}$ was used. Four outliers were identified: $^{36}$Ar and $^{40}$Ar with unusally small cross sections and $^{23}$Na and $^{33}$S with unusually large cross sections. New data for $^{23}$Na were presented at this NPA-7 conference; contrary to the previous data, these new data fit into the general systematics. In addition, a relation between the most effective energy $E_0$ for astrophysical reaction rates (the so-called Gamow window) and the reduced energy $E_{\\rm{red}}$ is presented.
Cleaning up the cosmological constant
Kimpton, Ian
2012-01-01
We present a novel idea for screening the vacuum energy contribution to the overall value of the cosmological constant, thereby enabling us to choose the bare value of the vacuum curvature empirically, without any need to worry about the zero-point energy contributions of each particle. The trick is to couple matter to a metric that is really a composite of other fields, with the property that the square-root of its determinant is the integrand of a topological invariant, and/or a total derivative. This ensures that the vacuum energy contribution to the Lagrangian is non-dynamical. We then give an explicit example of a theory with this property that is free from Ostrogradski ghosts, and is consistent with solar system physics and cosmological tests.
Coupling constant in dispersive model
R Saleh-Moghaddam; M E Zomorrodian
2013-11-01
The average of the moments for event shapes in + - → hadrons within the context of next-to-leading order (NLO) perturbative QCD prediction in dispersive model is studied. Moments used in this article are $\\langle 1 - T \\rangle, \\langle ρ \\rangle, \\langle B_{T} \\rangle$ and $\\langle B_{W} \\rangle$. We extract , the coupling constant in perturbative theory and α0 in the non-perturbative theory using the dispersive model. By fitting the experimental data, the values of $(M_{Z^{°}})$ = 0.1171 ± 0.00229 and 0 ($_{I} = 2{\\text{GeV}}$) = 0.5068 ± 0.0440 are found. Our results are consistent with the above model. Our results are also consistent with those obtained from other experiments at different energies. All these features are explained in this paper.
Henry's law constants of polyols
Compernolle, S.; Müller, J.-F.
2014-12-01
Henry's law constants (HLC) are derived for several polyols bearing between 2 and 6 hydroxyl groups, based on literature data for water activity, vapour pressure and/or solubility. While deriving HLC and depending on the case, also infinite dilution activity coefficients (IDACs), solid state vapour pressures or activity coefficient ratios are obtained as intermediate results. An error analysis on the intermediate quantities and the obtained HLC is included. For most compounds, these are the first values reported, while others compare favourably with literature data in most cases. Using these values and those from a previous work (Compernolle and Müller, 2014), an assessment is made on the partitioning of polyols, diacids and hydroxy acids to droplet and aqueous aerosol.
Yang, Hengzhao; Zhang, Ying
2016-04-01
Understanding the power and energy performance of supercapacitors connected to constant power elements is important for many applications. This paper proposes a characterization method for two supercapacitor models that are used to analyze the power and energy behavior of supercapacitors connected to constant power elements: linear capacitance model and constant capacitance model. The linear or constant capacitance is determined by conducting a constant power experiment. A set of constant power experiments is designed. The proposed method can reduce the error in estimating the constant power experiment time for a variety of supercapacitor samples with different rated capacitance and voltage. The accuracy of using the linear capacitance model and the constant capacitance model is approximately equal. Moreover, the performance evaluation results suggest that using the linear or constant capacitance fitted through a low power discharge experiment can minimize the error, which can serve as a guideline to design the constant power experiment.
Scales set by the cosmological constant
The cosmological constant, Λ, sets certain scales important in cosmology. We show that Λ in conjunction with other parameters such as the Schwarzschild radius leads to scales relevant not only for cosmological but also for astrophysical applications. Of special interest is the extension of orbits and velocity of test particles travelling over Mpc distances. We will show that there exist a lower and an upper cut-off on the possible velocities of test particles. For a test body moving in a central gravitational field, Λ enforces a maximal value of the angular momentum if we insist on bound orbits of the test body which move at a distance larger than the Schwarzschild radius
Scales set by the cosmological constant
Balaguera-AntolInez, Andres [Departamento de Fisica, Universidad de los Andes, AA 4976, Bogota, DC (Colombia); Boehmer, Christian G [ASGBG/CIU, Department of Mathematics, Apartado Postal C-600, University of Zacatecas (UAZ), Zacatecas, Zac 98060 (Mexico); Nowakowski, Marek [Departamento de Fisica, Universidad de los Andes, AA 4976, Bogota, DC (Colombia)
2006-01-21
The cosmological constant, {lambda}, sets certain scales important in cosmology. We show that {lambda} in conjunction with other parameters such as the Schwarzschild radius leads to scales relevant not only for cosmological but also for astrophysical applications. Of special interest is the extension of orbits and velocity of test particles travelling over Mpc distances. We will show that there exist a lower and an upper cut-off on the possible velocities of test particles. For a test body moving in a central gravitational field, {lambda} enforces a maximal value of the angular momentum if we insist on bound orbits of the test body which move at a distance larger than the Schwarzschild radius.
A Variant of Davenport's Constant
R Thangadurai
2007-05-01
Let be a prime number. Let be a finite abelian -group of exponent (written additively) and be a non-empty subset of $]n[:=\\{1,2,\\ldots,n\\}$ such that elements of are incongruent modulo and non-zero modulo . Let $k ≥ D(G)/|A|$ be any integer where () denotes the well-known Davenport’s constant. In this article, we prove that for any sequence $g_1,g_2,\\ldots,g_k$ (not necessarily distinct) in , one can always extract a subsequence $g_{i_1},g_{i_2},\\ldots,g_{i_l}$ with $1 ≤ l ≤ k$ such that $$\\sum\\limits_{j=1}^l a_j g_{i_j}=0 \\text{in} G,$$ where $a_j\\in A$ for all . We provide examples where this bound cannot be improved. Furthermore, for the cyclic groups, we prove some sharp results in this direction. In the last section, we explore the relation between this problem and a similar problem with prescribed length. The proof of Theorem 1 uses group-algebra techniques, while for the other theorems, we use elementary number theory techniques.
Markov constant and quantum instabilities
Pelantová, E.; Starosta, Š.; Znojil, Miloslav
2016-01-01
Roč. 49, č. 15 (2016), s. 155201. ISSN 1751-8113 R&D Projects: GA ČR GA16-22945S Institutional support: RVO:61389005 Keywords : renormalizable quantum theories with ghosts * Pais-Uhlenbeck model * singular spectra * square-well model * number theory analysis * physical applications Subject RIV: BE - Theoretical Physics Impact factor: 1.583, year: 2014
Shen Sijing; Madau, Piero; Prochaska, J. Xavier [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Guedes, Javiera [Institute for Astronomy, ETH Zurich, Wolgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Mayer, Lucio [Institute of Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-9057 Zurich (Switzerland); Wadsley, James [Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1 (Canada)
2013-03-10
We present new results on the kinematics, thermal and ionization state, and spatial distribution of metal-enriched gas in the circumgalactic medium (CGM) of massive galaxies at redshift {approx}3, using the Eris suite of cosmological hydrodynamic ''zoom-in'' simulations. The reference run adopts a blastwave scheme for supernova feedback that produces large-scale galactic outflows, a star formation recipe based on a high gas density threshold, metal-dependent radiative cooling, and a model for the diffusion of metals and thermal energy. The effect of the local UV radiation field is added in post-processing. The CGM (defined as all gas at R > 0.2 R{sub vir} = 10 kpc, where R{sub vir} is the virial radius) contains multiple phases having a wide range of physical conditions, with more than half of its heavy elements locked in a warm-hot component at T > 10{sup 5} K. Synthetic spectra, generated by drawing sightlines through the CGM, produce interstellar absorption-line strengths of Ly{alpha}, C II, C IV, Si II, and Si IV as a function of the galactocentric impact parameter (scaled to the virial radius) that are in broad agreement with those observed at high redshift by Steidel et al. The covering factor of absorbing material declines less rapidly with impact parameter for Ly{alpha} and C IV compared to C II, Si IV, and Si II, with Ly{alpha} remaining strong (W{sub Ly{alpha}} > 300 mA) to {approx}> 5 R{sub vir} = 250 kpc. Only about one third of all the gas within R{sub vir} is outflowing. The fraction of sightlines within one virial radius that intercept optically thick, N{sub H{sub I}}>10{sup 17.2} cm{sup -2} material is 27%, in agreement with recent observations by Rudie et al. Such optically thick absorption is shown to trace inflowing ''cold'' streams that penetrate deep inside the virial radius. The streams, enriched to metallicities above 0.01 solar by previous episodes of star formation in the main host and in nearby
戚康标; 王金发; 王宏斌; 何炎明; 冯冬茹; 刘兵
2012-01-01
A highly efficient constant temperature water-bath ultraviolet radiation instrument is developed for distinguishing color aberration and exchange of sister chromatids according to the nature of the material handling and special requirements with the staining of sister chromatids. By a wide range of continuous use and examining, it is proved that the constant temperature water-bath ultraviolet radiation instrument has the advantages of convenient operation, safe use and stable performance. The samples treated with the instrument are processed uniformly and have obvious color aberration and fine resolution.%根据姊妹染色单体色差染色材料处理的性质和特殊要求,研制一种能够高效分辨姊妹染色单体色差和互换的仪器——恒温水浴紫外光照射仪.经过大范围连续使用与测试结果表明,该仪器操作简便,安全稳定,样品玻片处理均匀,姊妹染色单体染色清晰,色差明显,分辨率高.
Surfaces of a Constant Negative Curvature
G. M. Gharib
2012-01-01
Full Text Available I study the geometric notion of a differential system describing surfaces of a constant negative curvature and describe a family of pseudospherical surfaces for the nonlinear partial differential equations with constant Gaussian curvature .
Vacuum energy and the cosmological constant
Bass, Steven D
2015-01-01
The accelerating expansion of the Universe points to a small positive value for the cosmological constant or vacuum energy density. We discuss recent ideas that the cosmological constant plus LHC results might hint at critical phenomena near the Planck scale.
Anderegg, G
2013-01-01
Critical Survey of Stability Constants of EDTA Complexes focuses on the computations, values, and characteristics of stability constants. The book emphasizes that for a critical discussion of experimentally determined stability constants, it is important to consider the precision of the values that manifests the self-consistency of the constant, taking into consideration the random errors. The publication reviews the stability constants of metal complexes. The numerical calculations affirm the reactions and transformations of metal ions when exposed to varying conditions. The text also present
Hathi, N. P.; McCarthy, P. J. [Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States); Cohen, S. H.; Windhorst, R. A.; Rutkowski, M. J. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States); Ryan, R. E. Jr.; Koekemoer, A. M.; Bond, H. E. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Finkelstein, S. L. [Department of Astronomy, University of Texas, Austin, TX 78712 (United States); Yan, H. [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); O' Connell, R. W. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Straughn, A. N.; Kimble, R. A. [NASA-Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Balick, B. [Department of Astronomy, University of Washington, Seattle, WA 98195-1580 (United States); Calzetti, D. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Disney, M. J. [School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA (United Kingdom); Dopita, M. A. [Research School of Astronomy and Astrophysics, Australian National University, Weston Creek, ACT 2611 (Australia); Frogel, Jay A. [Astronomy Department, King Abdulaziz University, P.O. Box 80203, Jeddah (Saudi Arabia); Hall, D. N. B. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Holtzman, J. A., E-mail: nhathi@obs.carnegiescience.edu [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States); and others
2013-03-10
We analyze the spectral energy distributions (SEDs) of Lyman break galaxies (LBGs) at z {approx_equal} 1-3 selected using the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) UVIS channel filters. These HST/WFC3 observations cover about 50 arcmin{sup 2} in the GOODS-South field as a part of the WFC3 Early Release Science program. These LBGs at z {approx_equal} 1-3 are selected using dropout selection criteria similar to high-redshift LBGs. The deep multi-band photometry in this field is used to identify best-fit SED models, from which we infer the following results: (1) the photometric redshift estimate of these dropout-selected LBGs is accurate to within few percent; (2) the UV spectral slope {beta} is redder than at high redshift (z > 3), where LBGs are less dusty; (3) on average, LBGs at z {approx_equal} 1-3 are massive, dustier, and more highly star forming, compared to LBGs at higher redshifts with similar luminosities (0.1L* {approx}< L {approx}< 2.5L*), though their median values are similar within 1{sigma} uncertainties. This could imply that identical dropout selection technique, at all redshifts, finds physically similar galaxies; and (4) the stellar masses of these LBGs are directly proportional to their UV luminosities with a logarithmic slope of {approx}0.46, and star formation rates are proportional to their stellar masses with a logarithmic slope of {approx}0.90. These relations hold true-within luminosities probed in this study-for LBGs from z {approx_equal} 1.5 to 5. The star-forming galaxies selected using other color-based techniques show similar correlations at z {approx_equal} 2, but to avoid any selection biases, and for direct comparison with LBGs at z > 3, a true Lyman break selection at z {approx_equal} 2 is essential. The future HST UV surveys, both wider and deeper, covering a large luminosity range are important to better understand LBG properties and their evolution.
Constant global population with demographic heterogeneity
Cohen, Joel E.
2008-01-01
To understand better a possible future constant global population that is demographically heterogeneous, this paper analyzes several models. Classical theory of stationary populations generally fails to apply. However, if constant global population size P(global) is the sum of all country population sizes, and if constant global annual number of births B(global) is the sum of the annual number of births of all countries, and if constant global life expectancy at birth e(global) is the populat...
Origin of cosmological constant from Bulk manifold
The problem about cosmological constant is a difficult and important problem, people even don't know what it is really originated from. In this letter, the authors show up a kind of origin of the cosmological constant from the viewpoint of some extra dimensional spaces, obtain different values of the cosmological constant under different circumstances, acquire the evolution function with time t. And we achieve a cosmological constant that may be fitted with modern astronomic observation. (authors)
The $D_s$, $D^+$, $B_s$ and $B$ decay constants from $2+1$ flavor lattice QCD
Bazavov, A; Bouchard, C; DeTar, C; Du, D; El-Khadra, A X; Foley, J; Freeland, E D; Gámiz, E; Gottlieb, Steven; Heller, U M; Kim, J; Komijani, J; Kronfeld, A S; Laiho, J; Levkova, L; Mackenzie, P B; Mohler, D; Neil, E T; Oktay, M B; Qiu, S; Simone, J N; Sugar, R L; Toussaint, D; Van de Water, R S; Zhou, R
2014-01-01
We present a study of the $D$ and $B$ leptonic decay constants on the MILC $N_f=2+1$ asqtad gauge ensembles using asqtad-improved staggered light quarks and clover heavy quarks in the Fermilab interpretation. Our previous analysis \\cite{Bazavov:2011aa} computed the decay constants at lattice spacings $a \\approx 0.14, 0.11$ and $0.083$ fm. We have extended the simulations to finer $a \\approx 0.058$ and $0.043$ fm lattice spacings, and have also increased statistics; this allows us to address many important sources of uncertainty. Technical advances include a two-step two-point fit procedure, better tuning of the heavy quark masses and a better determination of the axial-vector current matching. The present analysis remains blinded, so here we focus on the improvements and their predicted impact on the error budget compared to the prior analysis.
Covariant description of shape evolution and shape coexistence in neutron-rich nuclei at N\\approx60
Xiang, J; Li, Z X; Yao, J M; Meng, J
2011-01-01
The shape evolution and shape coexistence phenomena in neutron-rich nuclei at $N\\approx60$, including Kr, Sr, Zr, and Mo isotopes, are studied in the covariant density functional theory (DFT) with the new parameter set PC-PK1. Pairing correlations are treated using the BCS approximation with a separable pairing force. Sharp rising in the charge radii of Sr and Zr isotopes at N=60 is observed and shown to be related to the rapid changing in nuclear shapes. The shape evolution is moderate in neighboring Kr and Mo isotopes. Similar as the results of previous Hartree-Fock-Bogogliubov (HFB) calculations with the Gogny force, triaxiality is observed in Mo isotopes and shown to be essential to reproduce quantitatively the corresponding charge radii. In addition, the coexistence of prolate and oblate shapes is found in both $^{98}$Sr and $^{100}$Zr. The observed oblate and prolate minima are related to the low single-particle energy level density around the Fermi surfaces of neutron and proton respectively. Furthermo...
Carman, R J
2003-01-01
A detailed rate-equation analysis has been used to simulate the plasma kinetics in a pulsed-excited dielectric barrier discharge in xenon, under operating conditions where the discharge structure is spatially homogeneous. The one-dimensional model, incorporating 14 species and 70 reaction processes, predicts results that are in good agreement with experimental measurements of the electrical characteristics, and optical (vacuum-ultraviolet (VUV) and visible) pulse shapes. The model reveals that electrical breakdown of the discharge gap occurs via a fast-moving ionization/excitation wavefront that starts close to the anode dielectric and propagates towards the cathode at approx 3x10 sup 5 m s sup - sup 1. The wavefront appears as a result of successive avalanches of electrons that propagate across the discharge gap after release from the cathode dielectric. During breakdown, the mean electron energy in the bulk plasma is close to optimum for preferential excitation of the Xe* 1s sub 4 sub , sub 5 states that fe...
The Not so Constant Gravitational "Constant" G as a Function of Quantum Vacuum
Maxmilian Caligiuri, Luigi
Gravitation is still the less understood among the fundamental forces of Nature. The ultimate physical origin of its ruling constant G could give key insights in this understanding. According to the Einstein's Theory of General Relativity, a massive body determines a gravitational potential that alters the speed of light, the clock's rate and the particle size as a function of the distance from its own center. On the other hand, it has been shown that the presence of mass determines a modification of Zero-Point Field (ZPF) energy density within its volume and in the space surrounding it. All these considerations strongly suggest that also the constant G could be expressed as a function of quantum vacuum energy density somehow depending on the distance from the mass whose presence modifies the ZPF energy structure. In this paper, starting from a constitutive medium-based picture of space, it has been formulated a model of gravitational constant G as a function of Planck's time and Quantum Vacuum energy density in turn depending on the radial distance from center of the mass originating the gravitational field, supposed as spherically symmetric. According to this model, in which gravity arises from the unbalanced physical vacuum pressure, gravitational "constant" G is not truly unchanging but slightly varying as a function of the distance from the mass source of gravitational potential itself. An approximate analytical form of such dependence has been discussed. The proposed model, apart from potentially having deep theoretical consequences on the commonly accepted picture of physical reality (from cosmology to matter stability), could also give the theoretical basis for unthinkable applications related, for example, to the field of gravity control and space propulsion.
Stefańska, Patrycja
2016-01-01
We present analytical derivation of the closed-form expression for the dipole magnetic shielding constant of a Dirac one-electron atom being in an arbitrary discrete energy eigenstate. The external magnetic field, by which the atomic state is perturbed, is assumed to be weak, uniform and time independent. With respect to the atomic nucleus we assume that it is pointlike, spinless, motionless and of charge Ze. Calculations are based on the Sturmian expansion of the generalized Dirac- Coulomb Green function [R. Szmytkowski, J. Phys. B 30, 825 (1997); erratum 30, 2747 (1997)], combined with the theory of hypergeometric functions. The final result is of an elementary form and agrees with corresponding formulas obtained earlier by other authors for some particular states of the atom.
Stefańska, Patrycja
2016-07-01
We present analytical derivation of the closed-form expression for the dipole magnetic shielding constant of a Dirac one-electron atom being in an arbitrary discrete energy eigenstate. The external magnetic field, by which the atomic state is perturbed, is assumed to be weak, uniform, and time independent. With respect to the atomic nucleus we assume that it is pointlike, spinless, motionless, and of charge Z e . Calculations are based on the Sturmian expansion of the generalized Dirac-Coulomb Green function [R. Szmytkowski, J. Phys. B 30, 825 (1997), 10.1088/0953-4075/30/4/007; erratum R. Szmytkowski, J. Phys. B 30, 2747(E) (1997), 10.1088/0953-4075/30/11/023], combined with the theory of hypergeometric functions. The final result is of an elementary form and agrees with corresponding formulas obtained earlier by other authors for some particular states of the atom.
Ono, Yoshiaki; Shimasaku, Kazuhiro; Nakajima, Kimihiko, E-mail: ono@astron.s.u-tokyo.ac.jp [Department of Astronomy, Graduate School of Science, University of Tokyo, Tokyo 113-0033 (Japan); Ouchi, Masami [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan); Mobasher, Bahram; Nayyeri, Hooshang [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Dickinson, Mark; Kartaltepe, Jeyhan S. [National Optical Astronomical Observatories, Tucson, AZ 85719 (United States); Penner, Kyle [Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States); Weiner, Benjamin J. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Kashikawa, Nobunari [Optical and Infrared Astronomy Division, National Astronomical Observatory of Japan, Tokyo 181-8588 (Japan); Spinrad, Hyron [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
2012-01-10
We present the results of our ultra-deep Keck/DEIMOS spectroscopy of z-dropout galaxies in the Subaru Deep Field and Great Observatories Origins Deep Survey's northern field. For 3 out of 11 objects, we detect an emission line at {approx}1 {mu}m with a signal-to-noise ratio of {approx}10. The lines show asymmetric profiles with high weighted skewness values, consistent with being Ly{alpha}, yielding redshifts of z = 7.213, 6.965, and 6.844. Specifically, we confirm the z = 7.213 object in two independent DEIMOS runs with different spectroscopic configurations. The z = 6.965 object is a known Ly{alpha} emitter, IOK-1, for which our improved spectrum at a higher resolution yields a robust skewness measurement. The three z-dropouts have Ly{alpha} fluxes of 3 Multiplication-Sign 10{sup -17} erg s{sup -1} cm{sup -2} and rest-frame equivalent widths EW{sup Ly{alpha}}{sub 0} = 33-43 A. Based on the largest spectroscopic sample of 43 z-dropouts, which is the combination of our and previous data, we find that the fraction of Ly{alpha}-emitting galaxies (EW{sup Ly{alpha}}{sub 0} > 25 A) is low at z {approx} 7; 17% {+-} 10% and 24% {+-} 12% for bright (M{sub UV} {approx_equal} -21) and faint (M{sub UV} {approx_equal} -19.5) galaxies, respectively. The fractions of Ly{alpha}-emitting galaxies drop from z {approx} 6 to 7 and the amplitude of the drop is larger for faint galaxies than for bright galaxies. These two pieces of evidence would indicate that the neutral hydrogen fraction of the intergalactic medium increases from z {approx} 6 to 7 and that the reionization proceeds from high- to low-density environments, as suggested by an inside-out reionization model.
Kim, Yong-Hyun; Kim, Ki-Hyun
2014-05-16
Accurate values for the Henry's law constants are essential to describe the environmental dynamics of a solute, but substantial errors are recognized in many reported data due to practical difficulties in measuring solubility and/or vapor pressure. Despite such awareness, validation of experimental approaches has scarcely been made. An experimental approach based on thermal desorption-gas chromatography-mass spectrometery (TD-GC-MS) method was developed to concurrently allow the accurate determination of target compounds from the headspace and aqueous samples in closed equilibrated system. The analysis of six aromatics and eight non-aromatic oxygenates was then carried out in a static headspace mode. An estimation of the potential bias and mass balance (i.e., sum of mass measured individually from gas and liquid phases vs. the mass initially added to the system) demonstrates compound-specific phase dependency so that the best results are obtained by aqueous (less soluble aromatics) and headspace analysis (more soluble non-aromatics). Accordingly, we were able to point to the possible sources of biases in previous studies and provide the best estimates for the Henry's constants (Matm(-1)): benzene (0.17), toluene (0.15), p-xylene (0.13), m-xylene (0.13), o-xylene (0.19), styrene (0.27); propionaldehyde (9.26), butyraldehyde (6.19), isovaleraldehyde (2.14), n-valeraldehyde (3.98), methyl ethyl ketone (10.5), methyl isobutyl ketone (3.93), n-butyl acetate (2.41), and isobutyl alcohol (22.2). PMID:24704185
USING THE STATIC HEADSPACE METHOD TO DETERMINE HENRY'S LAW CONSTANTS
A new, accurate, and experimentally simple method has been developed to determine dimensionless Henry's law constants using the static headspace method. he method appears applicable to a wide range of volatile and semivolatile organic compounds. he method work well even for methy...
Local Experiments See Cosmologically Varying Constants
Shaw, D J; Barrow, John D.; Shaw, Douglas J.
2006-01-01
We describe a rigorous construction, using matched asymptotic expansions, which establishes under very general conditions that local terrestrial and solar-system experiments will measure the effects of varying `constants' of Nature occurring on cosmological scales to computable precision. In particular, `constants' driven by scalar fields will still be found to evolve in time when observed within virialised structures like clusters, galaxies, and planetary systems. This provides a justification for combining cosmological and terrestrial constraints on the possible time variation of many assumed `constants' of Nature, including the fine structure constant and Newton's gravitation constant.
CLASH: DISCOVERY OF A BRIGHT z {approx_equal} 6.2 DWARF GALAXY QUADRUPLY LENSED BY MACS J0329.6-0211
Zitrin, A. [Institut fuer Theoretische Astrophysik, Universitaet Heidelberg, Heidelberg (Germany); Moustakas, J. [Center for Astrophysics and Space Sciences, University of California, San Diego, CA (United States); Bradley, L.; Coe, D.; Postman, M.; Koekemoer, A. [Space Telescope Science Institute, Baltimore, MD (United States); Moustakas, L. A. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA (United States); Shu, X. [Department of Astronomy, University of Science and Technology of China, Hefei, Anhui (China); Zheng, W.; Ford, H. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD (United States); Benitez, N. [Instituto de Astrofisica de Andalucia (CSIC), Granada (Spain); Bouwens, R. [Leiden Observatory, University of Leiden, Leiden (Netherlands); Broadhurst, T. [Department of Theoretical Physics, University of Basque Country, Bilbao (Spain); Host, O.; Jouvel, S. [Department of Physics and Astronomy, University College London, London (United Kingdom); Meneghetti, M. [INAF, Osservatorio Astronomico di Bologna, Bologna (Italy); Rosati, P. [European Southern Observatory, Garching bei Muenchen (Germany); Donahue, M. [Physics and Astronomy Department, Michigan State University, East Lansing, MI (United States); Grillo, C. [Excellence Cluster Universe, Technische Universitaet Muenchen, Muenchen (Germany); Kelson, D., E-mail: adizitrin@gmail.com [Observatories of the Carnegie Institution of Washington, Pasadena, CA (United States); and others
2012-03-15
We report the discovery of a z{sub phot} = 6.18{sup +0.05}{sub -0.07} (95% confidence level) dwarf galaxy, lensed into four images by the galaxy cluster MACS J0329.6-0211 (z{sub l} = 0.45). The galaxy is observed as a high-redshift dropout in HST/ACS/WFC3 CLASH and Spitzer/IRAC imaging. Its redshift is securely determined due to a clear detection of the Lyman break in the 18-band photometry, making this galaxy one of the highest-redshift multiply lensed objects known to date with an observed magnitude of F125W =24.00 {+-} 0.04 AB mag for its most magnified image. We also present the first strong-lensing analysis of this cluster uncovering 15 additional multiply imaged candidates of five lower-redshift sources spanning the range z{sub s} {approx_equal} 2-4. The mass model independently supports the high photometric redshift and reveals magnifications of 11.6{sup +8.9}{sub -4.1}, 17.6{sup +6.2}{sub -3.9}, 3.9{sup +3.0}{sub -1.7}, and 3.7{sup +1.3}{sub -0.2}, respectively, for the four images of the high-redshift galaxy. By delensing the most magnified image we construct an image of the source with a physical resolution of {approx}200 pc when the universe was {approx}0.9 Gyr old, where the z {approx_equal} 6.2 galaxy occupies a source-plane area of approximately 2.2 kpc{sup 2}. Modeling the observed spectral energy distribution using population synthesis models, we find a demagnified stellar mass of {approx}10{sup 9} M{sub Sun }, subsolar metallicity (Z/Z{sub Sun} {approx} 0.5), low dust content (A{sub V} {approx} 0.1 mag), a demagnified star formation rate (SFR) of {approx}3.2 M{sub Sun} yr{sup -1}, and a specific SFR of {approx}3.4 Gyr{sup -1}, all consistent with the properties of local dwarf galaxies.
[O III] EMISSION AND GAS KINEMATICS IN A LYMAN-ALPHA BLOB AT z {approx} 3.1
McLinden, Emily M. [McDonald Observatory, University of Texas at Austin, Austin, TX 78712 (United States); Malhotra, Sangeeta; Rhoads, James E. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Hibon, Pascale [Gemini Observatory, La Serena (Chile); Weijmans, Anne-Marie [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Tilvi, Vithal [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States)
2013-04-10
We present spectroscopic measurements of the [O III] emission line from two subregions of strong Ly{alpha} emission in a radio-quiet Lyman-alpha blob (LAB). The blob under study is LAB1 at z {approx} 3.1, and the [O III] detections are from the two Lyman break galaxies (LBGs) embedded in the blob halo. The [O III] measurements were made with LUCIFER on the 8.4 m Large Binocular Telescope and NIRSPEC on 10 m Keck Telescope. Comparing the redshift of the [O III] measurements to Ly{alpha} redshifts from SAURON allows us to take a step toward understanding the kinematics of the gas in the blob. Using both LUCIFER and NIRSPEC we find velocity offsets between the [O III] and Ly{alpha} redshifts that are modestly negative or consistent with 0 km s{sup -1} in both subregions studied (ranging from -72 {+-} 42- + 6 {+-} 33 km s{sup -1}). A negative offset means Ly{alpha} is blueshifted with respect to [O III] a positive offset then implies Ly{alpha} is redshifted with respect to [O III]. These results may imply that outflows are not primarily responsible for Lyman alpha escape in this LAB, since outflows are generally expected to produce a positive velocity offset. In addition, we present an [O III] line flux upper limit on a third region of LAB1, a region that is unassociated with any underlying galaxy. We find that the [O III] upper limit from the galaxy-unassociated region of the blob is at least 1.4-2.5 times fainter than the [O III] flux from one of the LBG-associated regions and has an [O III] to Ly{alpha} ratio measured at least 1.9-3.4 times smaller than the same ratio measured from one of the LBGs.
The importance of being (a) constant
The author intends to show how the epistemological status of the physical constants bears witness to the development of physical science in general. He classifies the various physical constants into three types, properties of particular physical objects, characteristics of classes of physical phenomena and universal constants. He discusses the phenomena of fundamental constants experiencing a change in their type, at length on the example of two important constants, c and G. He considers Planck's constant and discusses the conceptual role of universal constants in general, as well as some aspects of quantum mechanics which appear in a new light from the proposed point of view. The existence is shown of hidden universal constants, forgotten ones in the realm of classical physics, as well as overlooked ones in modern physics. The velocity of light is studied as an example of general considerations on universal constants, and as a way to approach some epistemological problems of special relativity. Newton's gravitational constant is studied in connection with the interpretation of general relativity. (Auth./C.F.)
Non-perturbative renormalization constants using Ward identities
We extend the application of vector and axial Ward identities to calculate bA, bP and bT, coefficients that give the mass dependence of the renormalization constants of the corresponding bilinear operators in the quenched theory. The extension relies on using operators with non-degenerate quark masses. It allows a complete determination of the O(a) improvement coefficients for bilinears in the quenched approximation using Ward Identities alone. Only the scale dependent normalization constants Z0P (or Z0S) and ZT are undetermined. We present results of a pilot numerical study using hadronic correlators
A first-principles approach to finite temperature elastic constants
Wang, Y; Wang, J J; Zhang, H; Manga, V R; Shang, S L; Chen, L-Q; Liu, Z-K [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)
2010-06-09
A first-principles approach to calculating the elastic stiffness coefficients at finite temperatures was proposed. It is based on the assumption that the temperature dependence of elastic stiffness coefficients mainly results from volume change as a function of temperature; it combines the first-principles calculations of elastic constants at 0 K and the first-principles phonon theory of thermal expansion. Its applications to elastic constants of Al, Cu, Ni, Mo, Ta, NiAl, and Ni{sub 3}Al from 0 K up to their respective melting points show excellent agreement between the predicted values and existing experimental measurements.
Dust-filled axially symmetric universes with a cosmological constant
Aguiar, P; Aguiar, Paulo; Crawford, Paulo
2000-01-01
Following the recent recognition of a positive value for the vacuum energy density and the realization that a simple Kantowski-Sachs model might fit the classical tests of cosmology, we study the qualitative behavior of three anisotropic and homogeneous models: Kantowski-Sachs, Bianchi type-I and Bianchi type-III universes, with dust and a cosmological constant, in order to find out which are physically permitted. We find that these models undergo isotropization up to the point that the observations will not be able to distinguish between them and the standard model, except for the Kantowski-Sachs model $(\\Omega_{k_{0}}0)$ with $\\Omega_{\\Lambda_{0}}$ smaller than some critical value $\\Omega_{\\Lambda_{M}}$. Even if one imposes that the Universe should be nearly isotropic since the last scattering epoch ($z\\approx 1000$), meaning that the Universe should have approximately the same Hubble parameter in all directions (considering the COBE 4-Year data), there is still a large range for the matter density paramete...
Constant Current Models of Brushless DC Motor
Krykowski, Krzysztof; Hetmańczyk, Janusz
2013-01-01
Two constant current models of Permanent Magnet Brushless Direct Current Motor (PM BLDC) are presented in the paper. In the first part of the paper principle of operation, basic properties and mathematical equations describing PM BLDC models are given. Then, two different constant current models of PM BLDC motor are considered: In the first model, PM BLDC motor is approximated with dc motor; in the second model, modified constant current model is applied with additional block, which is used t...
Cosmological Constant and Soft Terms in Supergravity
Choi, Kiwoon; Kim, Jihn E.; Nilles, Hans Peter, Ramos-S\\xe1nchez, Sa\\xfal
1994-01-01
Some of the soft SUSY breaking parameters in hidden sector supergravity model depend on the expectation value of the hidden sector scalar potential, $$, whose tree level value is equal to the tree level cosmological constant. The current practice of calculating soft parameters assumes that $=0$. Quantum correction to the cosmological constant can differ from the correction to $$ by an amount of order $m^2_{3/2}M_{Pl}^2/8\\pi$. This implies that, for the vanishing cosmological constant, the $$-...
Cosmological Constant and Axions in String Theory
Svrcek, Peter; /Stanford U., Phys. Dept. /SLAC
2006-08-18
String theory axions appear to be promising candidates for explaining cosmological constant via quintessence. In this paper, we study conditions on the string compactifications under which axion quintessence can happen. For sufficiently large number of axions, cosmological constant can be accounted for as the potential energy of axions that have not yet relaxed to their minima. In compactifications that incorporate unified models of particle physics, the height of the axion potential can naturally fall close to the observed value of cosmological constant.
Bubble Universes With Different Gravitational Constants
Takamizu, Yu-ichi; Maeda, Kei-ichi
2015-01-01
We argue a scenario motivated by the context of string landscape, where our universe is produced by a new vacuum bubble embedded in an old bubble and these bubble universes have not only different cosmological constants, but also their own different gravitational constants. We study these effects on the primordial curvature perturbations. In order to construct a model of varying gravitational constants, we use the Jordan-Brans-Dicke (JBD) theory where different expectation values of scalar fi...
ZEMO system for generating group constants
The code system ZEMO for generating 26 group and 140-group constant sets for fast breeder reactors neutronics is considered. Group constant libraries, calculational techniques, formats of generated group constant sets and code control parameters are described. Results of one-dimensional model calculations for some critical assemblies and results of investigation of sodium void reactivity effect calculational error caused by 26-group approximation for two-dimensional model of BN-800 are presented. 14 refs.; 1 fig.; 3 tabs
Surprises in numerical expressions of physical constants
Amir, Ariel; Tokieda, Tadashi
2016-01-01
In science, as in life, `surprises' can be adequately appreciated only in the presence of a null model, what we expect a priori. In physics, theories sometimes express the values of dimensionless physical constants as combinations of mathematical constants like pi or e. The inverse problem also arises, whereby the measured value of a physical constant admits a `surprisingly' simple approximation in terms of well-known mathematical constants. Can we estimate the probability for this to be a mere coincidence, rather than an inkling of some theory? We answer the question in the most naive form.
Tuning the Spring Constant of Cantilever-free Probe Arrays
Eichelsdoerfer, Daniel J.; Brown, Keith A.; Boya, Radha; Shim, Wooyoung; Mirkin, Chad A.
2013-03-01
The versatility of atomic force microscope (AFM) based techniques such as scanning probe lithography is due in part to the utilization of a cantilever that can be fabricated to match a desired application. In contrast, cantilever-free scanning probe lithography utilizes a low cost array of probes on a compliant backing layer that allows for high throughput nanofabrication but lacks the tailorability afforded by the cantilever in traditional AFM. Here, we present a method to measure and tune the spring constant of probes in a cantilever-free array by adjusting the mechanical properties of the underlying elastomeric layer. Using this technique, we are able to fabricate large-area silicon probe arrays with spring constants that can be tuned in the range from 7 to 150 N/m. This technique offers an advantage in that the spring constant depends linearly on the geometry of the probe, which is in contrast to traditional cantilever-based lithography where the spring constant varies as the cube of the beam width and thickness. To illustrate the benefit of utilizing a probe array with a lower spring constant, we pattern a block copolymer on a delicate 50 nm thick silicon nitride window.
Pattan, J.N.; Masuzawa, T.; Borole, D.V.; Parthiban, G.; Jauhari, P.; Yamamoto, M.
and few trace elements (Al, Ti, Fe, K, Mg, Zr, Sc, V, Mn, Cu, Ni, Zn, Co, and Ba) to understand the productivity and intensity of terrigenous supply. The age model of the sediment core is based on U-Th dating, occurrence of Youngest Toba Tuff of approx. 74...
Electromechanical systems generating constant frequency alternating current
Т.А. Мазур
2008-01-01
Full Text Available In the article we consider the usage of electromechanical drivers of constant speed rotation, which is based on many stepped electrodynamic reduction unit, in onboard main systems of electric supply of alternative current with constant frequency.
Habitable sphere and fine structure constant
Kozlovskii, Miroslaw P; Kozlowski, Miroslaw; Marciak-Kozlowska, Janina
2005-01-01
Future space missions, TPF and Darwin will focus on searches of signatures of life on extrasolar planets. In this paper we look for model independ definition of the habitable zone. It will be shown that the radius of the habitable sphere depends only on the constants of the Nature. Key words: Habitable sphere, fine structure constant.
Fullerene derivatives with increased dielectric constants
Jahani, Fatemeh; Torabi, Solmaz; Chiechi, Ryan C; Koster, L Jan Anton; Hummelen, Jan C
2014-01-01
The invention of new organic materials with high dielectric constants is of extreme importance for the development of organic-based devices such as organic solar cells. We report on a synthetic way to increase the dielectric constant of fullerene derivatives. It is demonstrated that introducing trie
Supplementary kinetic constants of charged particles
Ribaric, Marijan; Sustersic, Luka
2006-01-01
We put forward: (A) An improved description of classical, kinetic properties of a charged pointlike physical particle that consists, in addition to its mass and charge, also of the Eliezer and Bhabha kinetic constants; and (B) a proposal to evaluate these kinetic constants by considering the trajectories of charged particles in an acccelerator.
FLOTATION RATE CONSTANT MODEL FOR FINE COAL
LuMaixi; CaiZhang; TaoYoujun; KuangYali
1996-01-01
The density of fine coal has a major effect on the value of its floxation rate constant. The collector dose can increase the flotation rate of fine coal, especially for low ash coal, but the effect for gangue is not notable. The flotation rate of gangue is mainly governed by the water entrainment. A coal flotation rate constant model has been developed.
Constant-axial-intensity nondiffracting beam.
Cox, A J; D'Anna, J
1992-02-15
Numerical solutions of the Fresnel diffraction integral with various apodizing filter functions are used to indicate that a so-called nondiffracting beam can be produced that maintains a constant spot size and constant axial intensity over a considerable range, approximately 30 m in our example. PMID:19784285
Atomic hydrogen and fundamental physical constants
Techniques are described which allow the study, in undergraduate laboratories, of the spectrum of atomic hydrogen. The Rydberg constant, the electron-proton mass ratio, and the fine-structure constant are evaluated from the measurements. The key to the series of experiments is a discharge tube in which atomic lines dominate over the molecular lines. (author)
Matchkov, Vladimir; Tarasova, Olga S; Timin, Eugeny N;
1997-01-01
pressure. Two series of experiments were performed. In the first series, vessels were perfused/superfused with Krebs-Henseleit solution. In the second one a modified salt solution was used, in which NaCl was totally replaced by an equimolar amount of KCI. Under constant flow conditions noradrenaline evoked......, vasoconstriction at constant pressure in SHR became more pronounced than that in WKY. We suggest that there is greater wall thickness:lumen diameter ratio in SHR vessels and thus different contribution of distension-activated myogenic response is of primary importance for the data obtained....... a more prominent resistance increase in SHR compared with WKY independently of the composition of solution (normal or high-K+) used. At constant pressure perfusion with normal solution, the vasoconstrictor response to noradrenaline was more prominent in WKY. Under application of high-K+ solution...
Cosmic Time Variation of the Gravitational Constant
Tomaschitz, R
2000-01-01
A pre-relativistic cosmological approach to electromagnetism and gravitation is explored that leads to a cosmic time variation of the fundamental constants. Space itself is supposed to have physical substance, which manifests by its permeability. The scale factors of the permeability tensor induce a time variation of the fundamental constants. Atomic radii, periods, and energy levels scale in cosmic time, which results in dispersionless redshifts without invoking a space expansion. Hubble constant and deceleration parameter are reviewed in this context. The time variation of the gravitational constant at the present epoch can be expressed in terms of these quantities. This provides a completely new way to restrain the deceleration parameter from laboratory bounds on the time variation of the gravitational constant. This variation also affects the redshift dependence of angular diameters and the surface brightness, and we study in some detail the redshift scaling of the linear sizes of radio sources. The effec...