Hua, J S; Hua, T; Hu, S L
2002-01-01
Recently, we have found, by means of a shock wave experiment, that an empirical relation Y/G approx 1.9x10 sup - sup 2 (Y is the yield strength and G is the shear modulus) is applicable for describing the strength effect for shocked 93W (93% W with 7% Fe-Ni-Co as binder) in the pressure range up to 150 GPa. This represents an extension of existing knowledge of the empirical approximation Y/G approx constant for potassium obtained at liquid-N sub 2 temperature and in the pressure range below 0.55 GPa. This approximation is advantageous in allowing one to simply and conveniently construct the constitutive equation for shocked metals.
Energy Technology Data Exchange (ETDEWEB)
Pecharroman, C.; Esteban-Betegon, F.; Bartolome, J.F.; Lopez-Esteban, S.; Moya, J.S. [Consejo Superior de Investigaciones Cientificas, Madrid (Spain). Inst. de Ciencia de Materiales
2001-10-16
A novel capacitor device with a high, frequency-independent dielectric constant has been fabricated by a simple powder processing route. A mixture of microparticles of ferroelectric BaTiO{sub 3} and de-passivated metallic nickel was sintered to yield percolative composites in which the system of conducting particles separated by insulator layers exhibits a dielectric constant higher than that of either component. (orig.)
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
Institute of Scientific and Technical Information of China (English)
Chen,Guochu; Zhang,Lin; Hao,Ninmei; Liu,Xianguang; Wang,Junhong
2003-01-01
Guided by the principle of neural network, an intelligent PID controller based on neural network is devised and applied to control of constant temperature and constant liquidlevel system. The experiment results show that this controller has high accuracy and strong robustness and good characters.
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.
Institute of Scientific and Technical Information of China (English)
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.
High dielectric constant materials and their application to IC gate stack systems
Institute of Scientific and Technical Information of China (English)
TU; Hailing
2005-01-01
High dielectric constant (high-k) materials are vital tothe nanoelectronic devices.The paper reviews research development of high-k materials, describes a variety of manufacture technologies and discusses the application of the gate stack systems to non-classical device structures.
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.
A constant air flow rate control of blower for residential applications
Energy Technology Data Exchange (ETDEWEB)
Yang, S.M. [Tamkang Univ., Taipei (Taiwan, Province of China). Dept. of Mechanical Engineering
1998-03-01
This paper presents a technique to control a blower for residential applications at constant air flow rate using an induction motor drive. The control scheme combines a variable volt/hertz ratio inverter drive and an average motor current regulation loop to achieve control of the motor torque-speed characteristics, consequently controlling the air flow rate of the blower which the motor is driving. The controller is simple to implement and practical for commercialization. It is also reliable, since no external pressure or air flow sensor is required. Both a theoretical derivation and an experimental verification for the control scheme are presented in this paper.
Minkowski problem, new constant curvature surfaces in R^3, and some applications
Alarcon, Antonio
2012-01-01
Let $m\\in\\mathbb{N},$ $m\\geq 2,$ and let $\\{p_j\\}_{j=1}^m$ be a finite subset of $\\mathbb{S}^2$ such that $0\\in\\mathbb{R}^3$ lies in its positive convex hull. In this paper we make use of the classical Minkowski problem, to show the complete family of smooth convex bodies $K$ in $\\mathbb{R}^3$ whose boundary surface consists of an open surface $S$ with constant Gauss curvature (respectively, constant mean curvature) and $m$ planar compact discs $\\bar{D_1},...,\\bar{D_m},$ such that the Gauss map of $S$ is a homeomorphism onto $\\mathbb{S}^2-\\{p_j\\}_{j=1}^m$ and $D_j\\bot p_j,$ for all $j.$ We derive applications to the generalized Minkowski problem, existence of harmonic diffeomorphisms between domains of $\\mathbb{S}^2,$ existence of capillary surfaces in $\\mathbb{R}^3,$ and a Hessian equation of Monge-Ampere type.
Fong, Yeong Yin; Bhatia, Subhash
The semiconductor industry needs low dielectric constant (low k-value) materials for more advance microprocessor and chips by reducing the size of the device features. In fabricating these contents, a new material with lower k-value than conventional silica (k = 3.9-4.2) is needed in order to improve the circuit performance. The choice of the inorganic zeolite membrane is an attractive option for low k material and suitable for microprocessor applications. A pure silica zeolite beta membrane was synthesized and coated on non-porous stainless steel support using insitu crystallization in the presence of tetraethylammonium hydroxide, TEA (OH), as structure directing agent, fumed silica, HF and deionized water at pH value of 9. The crystallization was carried out for the duration of 14 days under hydrothermal conditions at 130°C. The membrane was characterized by thermogravimetric analysis (TGA), nitrogen adsorption and Scanning Electron Microscope (SEM). SEM results show a highly crystalline; with a truncated square bipyramidal morphology of pure silica zeolite beta membrane strongly adhered on the non-porous stainless steel support. In the present work, the k-value of the membrane was measured as 2.64 which make it suitable for the microprocessor applications.
Energy Technology Data Exchange (ETDEWEB)
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
Allison, Thomas C
2016-03-03
Rate constants for reactions of chemical compounds with hydroxyl radical are a key quantity used in evaluating the global warming potential of a substance. Experimental determination of these rate constants is essential, but it can also be difficult and time-consuming to produce. High-level quantum chemistry predictions of the rate constant can suffer from the same issues. Therefore, it is valuable to devise estimation schemes that can give reasonable results on a variety of chemical compounds. In this article, the construction and training of an artificial neural network (ANN) for the prediction of rate constants at 298 K for reactions of hydroxyl radical with a diverse set of molecules is described. Input to the ANN consists of counts of the chemical bonds and bends present in the target molecule. The ANN is trained using 792 (•)OH reaction rate constants taken from the NIST Chemical Kinetics Database. The mean unsigned percent error (MUPE) for the training set is 12%, and the MUPE of the testing set is 51%. It is shown that the present methodology yields rate constants of reasonable accuracy for a diverse set of inputs. The results are compared to high-quality literature values and to another estimation scheme. This ANN methodology is expected to be of use in a wide range of applications for which (•)OH reaction rate constants are required. The model uses only information that can be gathered from a 2D representation of the molecule, making the present approach particularly appealing, especially for screening applications.
Tadano, T; Gohda, Y; Tsuneyuki, S
2014-06-04
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.
Model of constant probability event and its application in information fusion
Institute of Scientific and Technical Information of China (English)
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.
Kinetic Equations of Potassium Desorption and the Application of Equation Constants
Institute of Scientific and Technical Information of China (English)
LUEXIAO－NAN; LUYUN－FU
1995-01-01
Elovich,parabolic diffusion,power function and exponential equations were used to describe K desorption kinetics of 12 soils in a constant electric field of electro-ultrafiltration(EUF),Results showed that the Elovich,parabolic diffusion and power function equations could describe K desorption kinetics well owing to their high correlation coefficients and low standard errors;but the exponential equation was not suitable to be used in this study due to its relatively low correlation coefficients and relatively high standard errors.This work established successfully the relationships between the constants(slope or intercept)of kinetic equations and the barley responses to K fertilizer in the multiple-site field experiments and K-supplying status of soilsk,the constants of Elovich,parabolic diffusion and power function equations were very significantly or significantly correlated to the soil available K,relative yield of barley and K uptake of barley in NP plot.It was suggested that the kinetic equation constants could be used to estimate K-supplying power of soils.
Low dielectric constant Parylene-F-like films for intermetal dielectric applications
Hanyaloglu, Bengi; Aydinli, Atilla; Oye, Michael; Aydi, Eray S.
1999-01-01
We report on the dielectric properties and thermal stability of thin polymer films that are suitable candidates for replacing silicon dioxide as the intermetal dielectric material in integrated circuits. Parylene-F-like films, (-CF2-C6H4-CF2-)n, were produced by plasma deposition from a mixture of Ar and 1,4-bis(trifluoromethyl)benzene (CF3-C6H4-CF3) discharges and characterized using infrared absorption spectroscopy, spectroscopic ellipsometry, and capacitance measurements. The dielectric constant and the magnitude of the electronic and ionic contributions to the dielectric constant were determined through capacitance measurements and Kramers-Kronig analysis of the infrared absorption data. The film's dielectric constant ranges between 2 and 2.6 depending on the deposition conditions and the largest contribution to the dielectric constant is electronic. The films deposited at 300 °C are stable above 400 °C and further optimization could push this limit to as high as 500 °C.
Ivanov, Mikhail V; Babikov, Dmitri
2012-05-14
Efficient method is proposed for computing thermal rate constant of recombination reaction that proceeds according to the energy transfer mechanism, when an energized molecule is formed from reactants first, and is stabilized later by collision with quencher. The mixed quantum-classical theory for the collisional energy transfer and the ro-vibrational energy flow [M. Ivanov and D. Babikov, J. Chem. Phys. 134, 144107 (2011)] is employed to treat the dynamics of molecule + quencher collision. Efficiency is achieved by sampling simultaneously (i) the thermal collision energy, (ii) the impact parameter, and (iii) the incident direction of quencher, as well as (iv) the rotational state of energized molecule. This approach is applied to calculate third-order rate constant of the recombination reaction that forms the (16)O(18)O(16)O isotopomer of ozone. Comparison of the predicted rate vs. experimental result is presented.
Remarks on the sharp constant for the Schrodinger Strichartz estimate and applications
Directory of Open Access Journals (Sweden)
Alessandro Selvitella
2015-10-01
Full Text Available In this article, we compute the sharp constant for the homogeneous Schrodinger Strichartz inequality, and for the Fourier restriction inequality on the paraboloid in any dimension under the condition conjectured (and proved for dimensions 1 and 2 that the maximizers are Gaussians. We observe also how this would imply a far from optimal, but "cheap" and sufficient, criterion of the global wellposedness in the $L^2$-critical case $p=1+4/n$.
Measurement of third-order elastic constants and applications to loaded structural materials.
Takahashi, Sennosuke; Motegi, Ryohei
2015-01-01
The objective of this study is to obtain the propagation velocity of an elastic wave in a loaded isotropic solid and to show the usefulness of the third-order elastic constant in determining properties of practical materials. As is well known, the infinitesimal elastic theory is unable to express the influence of stress on elastic wave propagating in loaded materials. To solve this problem, the authors derive an equation of motion for elastic wave in a finitely deformed state and use the Lagrangian description where the state before deformation is used as a reference, and Murnaghans finite deformation theory for the unidirectional deformed isotropic solid. Ordinary derivatives were used for the mathematical treatment and although the formulas are long the content is simple. The theory is applied to the measurement of the third-order elastic constants of common steels containing carbon of 0.22 and 0.32 wt%. Care is taken in preparing specimens to precise dimensions, in properly adhering of transducer to the surface of the specimen, and in having good temperature control during the measurements to obtain precise data. As a result, the stress at various sites in the structural materials could be estimated by measuring the elastic wave propagation times. The results obtained are graphed for illustration.
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.
Yu, Yang-Yen; Jiang, Ai-Hua; Lee, Wen-Ya
2016-11-01
The organic material soluble polyimide (PI) and organic-inorganic hybrid PI-barium titanate (BaTiO3) nanoparticle dielectric materials (IBX, where X is the concentration of BaTiO3 nanoparticles in a PI matrix) were successfully synthesized through a sol-gel process. The effects of various BaTiO3 contents on the hybrid film performance and performance optimization were investigated. Furthermore, pentacene-based organic thin film transistors (OTFTs) with PI-BaTiO3/polymethylmethacrylate or cyclic olefin copolymer (COC)-modified gate dielectrics were fabricated and examined. The hybrid materials showed effective dispersion of BaTiO3 nanoparticles in the PI matrix and favorable thermal properties. X-ray diffraction patterns revealed that the BaTiO3 nanoparticles had a perovskite structure. The hybrid films exhibited high formability and planarity. The IBX hybrid dielectric films exhibited tunable insulating properties such as the dielectric constant value and capacitance in ranges of 4.0-8.6 and 9.2-17.5 nF cm-2, respectively. Adding the modified layer caused the decrease of dielectric constant values and capacitances. The modified dielectric layer without cross-linking displayed a hydrophobic surface. The electrical characteristics of the pentacene-based OTFTs were enhanced after the surface modification. The optimal condition for the dielectric layer was 10 wt% hybrid film with the COC-modified layer; moreover, the device exhibited a threshold voltage of 0.12 V, field-effect mobility of 4.32 × 10-1 cm2 V-1 s-1, and on/off current of 8.4 × 107.
Nuclear deformations in the A approx. = 80-100 region
Energy Technology Data Exchange (ETDEWEB)
Galeriu, D.; Bucurescu, D.; Ivascu, M.
1986-04-01
The occurrence of highly deformed nuclei in the A approx.80 and A approx.= 100 mass regions has been investigated in the framework of the Strutinsky approach with a Nilsson-type potential and the Yukawa-plus-exponential macroscopy mass formula, including elongation, necking and ..gamma.. deformation. Special emphasis was given to the spin-orbit potential parameters, which have large variations at the magic numbers and also depend on the shell filling. Good reproduction of the masses, deformations and shape transition was achieved in both mass regions. The phenomena of shape coexistence are also supported by the calculated potential energy surfaces. The odd-particle influence in driving the nucleus to deformed shapes is demonstrated. The results obtained are rather similar to those of the more elaborated Yukawa shell-model calculations, and show for the first time that a Nilsson-type model can also account for the large deformations of the light Kr, Sr and Zr nuclei.
Directory of Open Access Journals (Sweden)
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.
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.
HERSCHEL-ATLAS: TOWARD A SAMPLE OF {approx}1000 STRONGLY LENSED GALAXIES
Energy Technology Data Exchange (ETDEWEB)
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.
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 ...
Nicolay, Pascal; Aubert, Thierry
2014-08-01
Langasite (LGS) is a promising material for SAW applications at high temperature. However, the temperature coefficients of LGS material constants are not accurate enough to perform reliable simulations, and therefore to make good use of available design tools, above 300°C. In the first part of the paper, we describe a new possible way to derive these coefficients in a wider temperature range. The method is based on Simulated Annealing, a well-known optimization algorithm. The algorithm converges toward a set of optimized temperature coefficients of the stiffness constants which are used to perform accurate simulations up to at least 800°C. In the second part, a deeper analysis of the algorithm outputs demonstrates some of its strengths but also some of its main limitations. Possible solutions are described to predict and then improve the accuracy of the optimized coefficient values. In particular, one solution making use of additional BAW target curves is tested. A promising solution to extend the optimization to the temperature coefficients of piezoelectric constants is also discussed.
Flämmich, Michael; Danz, Norbert; Michaelis, Dirk; Bräuer, Andreas; Gather, Malte C; Kremer, Jonas H-W M; Meerholz, Klaus
2009-03-10
We describe a method to determine the refractive index and extinction coefficient of thin film materials without prior knowledge of the film thickness and without the assumption of a dispersion model. A straightforward back calculation to the optical parameters can be performed starting from simple measurements of reflection and transmission spectra of a 100-250 nm thick supported film. The exact film thickness is found simultaneously by fulfilling the intrinsic demand of continuity of the refractive index as a function of wavelength. If both the layer and the substrate are homogeneous and isotropic media with plane and parallel interfaces, effects like surface roughness, scattering, or thickness inhomogeneities can be neglected. Then, the accuracy of the measurement is approximately 10(-2) and 10(-3) for the refractive index and the extinction coefficient, respectively. The error of the thin film thickness determination is well below 1 nm. Thus this technique is well suited to determine the input parameters for optical simulations of organic thin film devices, such as organic light-emitting diodes (OLEDs) or organic photovoltaic (OPV) cells. We apply the method to the electroluminescent polymer poly(2,5-dioctyl-p-phenylene vinylene) (PDO-PPV) and show its applicability by comparing the measured and calculated reflection and transmission spectra of OLED stacks with up to five layers.
Damour, Thibault Marie Alban Guillaume
2003-01-01
We review some string-inspired theoretical models which incorporate a correlated spacetime variation of coupling constants while remaining naturally compatible both with phenomenological constraints coming from geochemical data (Oklo; Rhenium decay) and with present equivalence principle tests. Barring unnatural fine-tunings of parameters, a variation of the fine-structure constant as large as that recently ``observed'' by Webb et al. in quasar absorption spectra appears to be incompatible with these phenomenological constraints. Independently of any model, it is emphasized that the best experimental probe of varying constants are high-precision tests of the universality of free fall, such as MICROSCOPE and STEP. Recent claims by Bekenstein that fine-structure-constant variability does not imply detectable violations of the equivalence principle are shown to be untenable.
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.
Energy Technology Data Exchange (ETDEWEB)
El Naschie, M.S. [Department of Physics, Alexandria University (Egypt)], E-mail: Chaossf@aol.com
2008-01-15
Noether's theorem relating conservation laws with symmetry is applied in conjunction with the exceptional Lie group hierarchy, the holographic principles and E-infinity theory to calculate the electromagnetic fine structure constant. Various schemes are suggested utilizing the fundamentals of heterotic strings as well as P-Brane theory leading to essentially the same value of 1/{alpha} {approx_equal} 137 in complete agreement with the well-established experimental evidences.
Guo, Y C; Wang, H; Zhang, B L
2015-10-02
This study proposes use of the DNA genetic artificial fish swarm constant modulus blind equalization algorithm (DNA-G-AFS-CMBEA) to overcome the local convergence of the CMBEA. In this proposed algorithm, after the fusion of the fast convergence of the AFS algorithm and the global search capability of the DNA-G algorithm to drastically optimize the position vector of the artificial fish, the global optimal position vector is obtained and used as the initial optimal weight vector of the CMBEA. The result of application of this improved method in medical image processing demonstrates that the proposed algorithm outperforms the CMBEA and the AFS-CMBEA in removing the noise in a medical image and improving the peak signal to noise ratio.
Optical constants of materials in the EUV/soft x-ray region for multilayer mirror applications
Energy Technology Data Exchange (ETDEWEB)
Soufli, Regina [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 - δ + iβ. 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 δ, β 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 δ and β in the prediction and modeling of the performance of multilayer optics.
Optical constants of materials in the EUV/soft x-ray region for multilayer mirror applications
Energy Technology Data Exchange (ETDEWEB)
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.
Directory of Open Access Journals (Sweden)
Snezhana Georgieva Gocheva-Ilieva
2013-01-01
Full Text Available There are obtained integral form and recurrence representations for some Fourier series and connected with them Favard constants. The method is based on preliminary integration of Fourier series which permits to establish general recursion formulas for Favard constants. This gives the opportunity for effective summation of infinite series and calculation of some classes of multiple singular integrals by the Favard constants.
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.
Energy Technology Data Exchange (ETDEWEB)
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.
THE EPOCH OF DISK SETTLING: z {approx} 1 TO NOW
Energy Technology Data Exchange (ETDEWEB)
Kassin, Susan A.; Gardner, Jonathan P. [Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States); Weiner, Benjamin J.; Willmer, C. N. A. [Steward Observatory, University of Arizona, Tucson, AZ (United States); Faber, S. M.; Guhathakurta, Puragra; Koo, David C. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Coil, Alison L. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Cooper, Michael C. [Center for Galaxy Evolution, Department of Physics and Astronomy, University of California, Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Devriendt, Julien [Department of Physics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Dutton, Aaron A. [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Metevier, A. J. [Department of Physics and Astronomy, Sonoma State University, 1801 East Cotati Avenue, Rohnert Park, CA 94928 (United States); Noeske, Kai G. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Primack, Joel R., E-mail: susan.kassin@nasa.gov [Department of Physics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)
2012-10-20
We present evidence from a sample of 544 galaxies from the DEEP2 Survey for evolution of the internal kinematics of blue galaxies with stellar masses ranging 8.0 < log M {sub *}(M {sub Sun }) < 10.7 over 0.2 < z < 1.2. DEEP2 provides galaxy spectra and Hubble imaging from which we measure emission-line kinematics and galaxy inclinations, respectively. Our large sample allows us to overcome scatter intrinsic to galaxy properties in order to examine trends in kinematics. We find that at a fixed stellar mass, galaxies systematically decrease in disordered motions and increase in rotation velocity and potential well depth with time. Massive galaxies are the most well ordered at all times examined, with higher rotation velocities and less disordered motions than less massive galaxies. We quantify disordered motions with an integrated gas velocity dispersion corrected for beam smearing ({sigma} {sub g}). It is unlike the typical pressure-supported velocity dispersion measured for early type galaxies and galaxy bulges. Because both seeing and the width of our spectral slits comprise a significant fraction of the galaxy sizes, {sigma} {sub g} integrates over velocity gradients on large scales which can correspond to non-ordered gas kinematics. We compile measurements of galaxy kinematics from the literature over 1.2 < z < 3.8 and do not find any trends with redshift, likely for the most part, because these data sets are biased toward the most highly star-forming systems. In summary, over the last {approx}8 billion years since z = 1.2, blue galaxies evolve from disordered to ordered systems as they settle to become the rotation-dominated disk galaxies observed in the universe today, with the most massive galaxies being the most evolved at any time.
Uspenskii, Yu A; Seely, John E; Popov, N L; Vinogradov, A V; Pershin, Yu P; Kondratenko, V V
2004-02-01
The chemical reaction of a sample with atmospheric gases causes a significant error in the determinantion of the complex refractive index n = 1 - delta + ibeta in the extreme-ultraviolet region. The protection of samples removes this effect but hampers the interpretation of measurements. To overcome this difficulty, we derive the exact dependences on film thickness of the reflectivity and transmissivity of a protected film. These dependences greatly simplify the determination of delta and beta when the spectra of several films with different thickness and identical protection are measured. They also allow the verification of the delta(omega) obtained from the Kramers-Kronig relation and even make the Kramers-Kronig method unnecessary in many cases. As a practical application, the optical constants of Sc and Ti are determined at h omega = 18-70 eV and 18-99 eV, respectively. The essential feature of our experimental technique is deposition of a film sample directly on a silicon photodiode that allows easy operation with both thin (approximately 10-nm) and thick (approximately 100-nm) films. The comparison of calculated reflectivities of Si-Sc multilayers with the measured values shows the high accuracy of the determined delta(omega) and beta(omega).
Asquith, William H.; Roussel, Meghan C.
2007-01-01
Estimation of representative hydrographs from design storms, which are known as design hydrographs, provides for cost-effective, riskmitigated design of drainage structures such as bridges, culverts, roadways, and other infrastructure. During 2001?07, the U.S. Geological Survey (USGS), in cooperation with the Texas Department of Transportation, investigated runoff hydrographs, design storms, unit hydrographs,and watershed-loss models to enhance design hydrograph estimation in Texas. Design hydrographs ideally should mimic the general volume, peak, and shape of observed runoff hydrographs. Design hydrographs commonly are estimated in part by unit hydrographs. A unit hydrograph is defined as the runoff hydrograph that results from a unit pulse of excess rainfall uniformly distributed over the watershed at a constant rate for a specific duration. A time-distributed, watershed-loss model is required for modeling by unit hydrographs. This report develops a specific time-distributed, watershed-loss model known as an initial-abstraction, constant-loss model. For this watershed-loss model, a watershed is conceptualized to have the capacity to store or abstract an absolute depth of rainfall at and near the beginning of a storm. Depths of total rainfall less than this initial abstraction do not produce runoff. The watershed also is conceptualized to have the capacity to remove rainfall at a constant rate (loss) after the initial abstraction is satisfied. Additional rainfall inputs after the initial abstraction is satisfied contribute to runoff if the rainfall rate (intensity) is larger than the constant loss. The initial abstraction, constant-loss model thus is a two-parameter model. The initial-abstraction, constant-loss model is investigated through detailed computational and statistical analysis of observed rainfall and runoff data for 92 USGS streamflow-gaging stations (watersheds) in Texas with contributing drainage areas from 0.26 to 166 square miles. The analysis is
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...
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.
Stadnik, Y. V.; Flambaum, V. V.
2016-06-01
We outline laser interferometer measurements to search for variation of the electromagnetic fine-structure constant α and particle masses (including a nonzero photon mass). We propose a strontium optical lattice clock—silicon single-crystal cavity interferometer as a small-scale platform for these measurements. Our proposed laser interferometer measurements, which may also be performed with large-scale gravitational-wave detectors, such as LIGO, Virgo, GEO600, or TAMA300, 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.
Croton, Darren
2013-01-01
The Hubble constant, H_0, or its dimensionless equivalent, "little h", is a fundamental cosmological property that is now known to an accuracy better than a few percent. Despite its cosmological nature, little h commonly appears in the measured properties of individual galaxies. This can pose unique challenges for users of such data, particularly with survey data. In this paper we show how little h arises in the measurement of galaxies, how to compare like-properties from different datasets that have assumed different little h cosmologies, and how to fairly compare theoretical data with observed data, where little h can manifest in vastly different ways. This last point is particularly important when observations are used to calibrate galaxy formation models, as calibrating with the wrong (or no) little h can lead to disastrous results when the model is later converted to the correct h cosmology. We argue that in this modern age little h is an anachronism, being one of least uncertain parameters in astrophysi...
Odabasi, Mustafa; Adali, Mutlu
2016-12-01
The Henry's law constant (H) is a crucial variable to investigate the air-water exchange of persistent organic pollutants. H values for 32 polychlorinated naphthalene (PCN) congeners were measured using an inert gas-stripping technique at five temperatures ranging between 5 and 35 °C. H values in deionized water (at 25 °C) varied between 0.28 ± 0.08 Pa m3 mol-1 (PCN-73) and 18.01 ± 0.69 Pa m3 mol-1 (PCN-42). The agreement between the measured and estimated H values from the octanol-water and octanol-air partition coefficients was good (measured/estimated ratio = 1.00 ± 0.41, average ± SD). The calculated phase change enthalpies (ΔHH) were within the interval previously determined for other several semivolatile organic compounds (42.0-106.4 kJ mol-1). Measured H values, paired atmospheric and aqueous concentrations and meteorological variables were also used to reveal the level and direction of air-sea exchange fluxes of PCNs at the coast of Izmir Bay, Turkey. The net PCN air-sea exchange flux varied from -0.55 (volatilization, PCN-24/14) to 2.05 (deposition, PCN-23) ng m-2 day-1. PCN-19, PCN-24/14, PCN-42, and PCN-33/34/37 were mainly volatilized from seawater while the remaining congeners were mainly deposited. The overall number of the cases showing deposition was higher (67.9%) compared to volatilization (21.4%) and near equilibrium (10.7%).
Bhattacharjee, Suraka; Chaudhury, Ranjan
2016-11-01
The generalized spin stiffness constant for a doped quantum antiferromagnet has been investigated both analytically and numerically as a function of doping concentration at zero temperature, based on the strongly correlated t-J model on two-dimensional square lattice. The nature of the theoretical dependence of the stiffness constant on doping shows a striking similarity with that of the effective exchange constant, obtained from the combination of other theoretical and experimental techniques in the low doping region. This correspondence once again establishes that spin stiffness can very well play the role of an effective exchange constant even in the strongly correlated semi-itinerant systems. Our theoretical plot of the stiffness constant against doping concentration in the whole doping region exhibits the various characteristic features like a possible crossover in the higher doping regions and persistence of short range ordering even for very high doping with the complete vanishing of spin stiffness occurring only close to 100% doping. Our results receive very good support from various other theoretical approaches and also brings out a few limitations of some of them. Our detailed analysis highlights the crucial importance of the study of spin stiffness for the proper understanding of magnetic correlations in a semi-itinerant magnetic system described by the strongly correlated t-J model. Moreover, our basic formalism can also be utilized for determination of the effective exchange constant and magnetic correlations for itinerant magnetic systems, in general in a novel way.
Yongquan, Han
2016-10-01
The ideal gas state equation is not applicable to ordinary gas, it should be applied to the Electromagnetic ``gas'' that is applied to the radiation, the radiation should be the ultimate state of matter changes or initial state, the universe is filled with radiation. That is, the ideal gas equation of state is suitable for the Singular point and the universe. Maybe someone consider that, there is no vessel can accommodate radiation, it is because the Ordinary container is too small to accommodate, if the radius of your container is the distance that Light through an hour, would you still think it can't accommodates radiation? Modern scientific determinate that the radius of the universe now is about 1027 m, assuming that the universe is a sphere whose volume is approximately: V = 4.19 × 1081 cubic meters, the temperature radiation of the universe (cosmic microwave background radiation temperature of the universe, should be the closest the average temperature of the universe) T = 3.15k, radiation pressure P = 5 × 10-6 N / m 2, according to the law of ideal gas state equation, PV / T = constant = 6 × 1075, the value of this constant is the universe, The singular point should also equal to the constant Author: hanyongquan
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.
Energy Technology Data Exchange (ETDEWEB)
Urano, Miho; Tomimatsu, Akira [Department of Physics, Graduate School of Science, Nagoya University, Nagoya 464-8602 (Japan); Saida, Hiromi, E-mail: urano@gravity.phys.nagoya-u.ac.j, E-mail: atomi@gravity.phys.nagoya-u.ac.j, E-mail: saida@daido-it.ac.j [Department of Physics, Daido Institute of Technology , Nagoya 457-8530 (Japan)
2009-05-21
The mechanical first law (MFL) of black hole spacetimes is a geometrical relation which relates variations of the mass parameter and horizon area. While it is well known that the MFL of an asymptotic flat black hole is equivalent to its thermodynamical first law, however we do not know the detail of the MFL of black hole spacetimes with a cosmological constant which possess a black hole and cosmological event horizons. 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 the conserved Noether current and its associated Noether charge, and gives an abstract form of the MFL of black hole spacetimes with a cosmological constant. Then, as a representative application of this formalism, we derive the MFL of the Schwarzschild-de Sitter (SdS) spacetime. Our MFL of the SdS spacetime relates the variations of three quantities: the mass parameter, the total area of the two horizons and the volume enclosed by the two horizons. If our MFL is regarded as a thermodynamical first law of the SdS spacetime, it offers a thermodynamically consistent description of the SdS black hole evaporation process: the mass decreases while the volume and the entropy increase. In our suggestion, a generalized second law is not needed to ensure the second law of SdS thermodynamics for its evaporation process.
THE BIMODAL METALLICITY DISTRIBUTION OF THE COOL CIRCUMGALACTIC MEDIUM AT z {approx}< 1
Energy Technology Data Exchange (ETDEWEB)
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.
EARLY-TYPE GALAXIES AT z {approx} 1.3. IV. SCALING RELATIONS IN DIFFERENT ENVIRONMENTS
Energy Technology Data Exchange (ETDEWEB)
Raichoor, A.; Mei, S.; Huertas-Company, M. [GEPI, Observatoire de Paris, Section de Meudon, 92190 Meudon Cedex (France); Stanford, S. A.; Rettura, A.; Jee, M. J. [Department of Physics, University of California, Davis, CA 95616 (United States); Holden, B. P.; Illingworth, G. [UCO/Lick Observatories, University of California, Santa Cruz, CA 95065 (United States); Nakata, F.; Kodama, T. [Subaru Telescope, National Astronomical Observatory of Japan, Hilo, HI 96720 (United States); Rosati, P. [European South Observatory, D-85748 Garching (Germany); Shankar, F. [Max-Planck-Instituet fuer Astrophysik, D-85748 Garching (Germany); Tanaka, M. [Institute for the Physics and Mathematics of the Universe, The University of Tokyo, Chiba 277-8583 (Japan); Ford, H. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Postman, M.; White, R. L. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Blakeslee, J. P. [Herzberg Institute of Astrophysics, National Research Council of Canada, Victoria, BC V9E 2E7 (Canada); Demarco, R., E-mail: anand.raichoor@brera.inaf.it [Department of Astronomy, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile)
2012-02-01
We present the Kormendy and mass-size relations (MSR) for early-type galaxies (ETGs) as a function of environment at z {approx} 1.3. Our sample includes 76 visually classified ETGs with masses 10{sup 10} < M/M{sub Sun} < 10{sup 11.5}, selected in the Lynx supercluster and in the Great Observatories Origins Deep Survey/Chandra Deep Field South field; 31 ETGs in clusters, 18 in groups, and 27 in the field, all with multi-wavelength photometry and Hubble Space Telescope/Advanced Camera for Surveys observations. The Kormendy relation, in place at z {approx} 1.3, does not depend on the environment. The MSR reveals that ETGs overall appear to be more compact in denser environments: cluster ETGs have sizes on average around 30%-50% smaller than those of the local universe and a distribution with a smaller scatter, whereas field ETGs show an MSR with a similar distribution to the local one. Our results imply that (1) the MSR in the field did not evolve overall from z {approx} 1.3 to present; this is interesting and in contrast to the trend found at higher masses from previous works; (2) in denser environments, either ETGs have increased in size by 30%-50% on average and spread their distributions, or more ETGs have been formed within the dense environment from non-ETG progenitors, or larger galaxies have been accreted to a pristine compact population to reproduce the MSR observed in the local universe. Our results are driven by galaxies with masses M {approx}< 2 Multiplication-Sign 10{sup 11} M{sub Sun} and those with masses M {approx} 10{sup 11} M{sub Sun} follow the same trends as that of the entire sample. Following the Valentinuzzi et al. definition of superdense ETGs, {approx}35%-45% of our cluster sample is made up of superdense ETGs.
THE STRUCTURE OF THE MERGING RCS 231953+00 SUPERCLUSTER AT z {approx} 0.9
Energy Technology Data Exchange (ETDEWEB)
Faloon, A. J.; Webb, T. M. A.; Geach, J. E.; Noble, A. G. [Department of Physics, McGill University, 3600 Rue University, Montreal, QC, H3A 2T8 (Canada); Ellingson, E. [Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Science, UCB-389, University of Colorado, Boulder, CO 80309 (United States); Yan, R. [Department of Physics and Astronomy, University of Kentucky, 505 Rose St., Lexington, KY 40506-0055 (United States); Gilbank, David G. [South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 (South Africa); Barrientos, L. F. [Departamento de Astronomia y Astrofisica Pontifica Universidad Catholica de Chile, Vicuna MacKenna 4860, 7820436 Macul, Santiago (Chile); Yee, H. K. C. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, ON, M5S 3H4 (Canada); Gladders, M. [Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Ave, Chicago, IL 60637 (United States); Richard, J. [Observatoire de Lyon, Centre de Recherche Astrophysique de Lyon, Universite Lyon, 19 Avenue Charles Andre, F-69561 Saint-Genis-Laval (France)
2013-05-10
The RCS 2319+00 supercluster is a massive supercluster at z = 0.9 comprising three optically selected, spectroscopically confirmed clusters separated by <3 Mpc on the plane of the sky. This supercluster is one of a few known examples of the progenitors of present-day massive clusters (10{sup 15} M{sub Sun} by z {approx} 0.5). We present an extensive spectroscopic campaign carried out on the supercluster field resulting, in conjunction with previously published data, in 1961 high-confidence galaxy redshifts. We find 302 structure members spanning three distinct redshift walls separated from one another by {approx}65 Mpc ({Delta} z = 0.03). The component clusters have spectroscopic redshifts of 0.901, 0.905, and 0.905. The velocity dispersions are consistent with those predicted from X-ray data, giving estimated cluster masses of {approx}10{sup 14.5}-10{sup 14.9} M{sub Sun }. The Dressler-Shectman test finds evidence of substructure in the supercluster field and a friends-of-friends analysis identified five groups in the supercluster, including a filamentary structure stretching between two cluster cores previously identified in the infrared by Coppin et al. The galaxy colors further show this filamentary structure to be a unique region of activity within the supercluster, comprised mainly of blue galaxies compared to the {approx}43%-77% red-sequence galaxies present in the other groups and cluster cores. Richness estimates from stacked luminosity function fits result in average group mass estimates consistent with {approx}10{sup 13} M{sub Sun} halos. Currently, 22% of our confirmed members reside in {approx}> 10{sup 13} M{sub Sun} groups/clusters destined to merge onto the most massive cluster, in agreement with the massive halo galaxy fractions important in cluster galaxy pre-processing in N-body simulation merger tree studies.
LOW-FREQUENCY RADIO-FIR CORRELATION IN NORMAL GALAXIES AT {approx}1 kpc SCALES
Energy Technology Data Exchange (ETDEWEB)
Basu, Aritra; Roy, Subhashis; Mitra, Dipanjan, E-mail: aritra@ncra.tifr.res.in, E-mail: roy@ncra.tifr.res.in, E-mail: dmitra@ncra.tifr.res.in [National Center for Radio Astrophysics, TIFR, Pune University Campus, Ganeshkhind Road, Pune-411007 (India)
2012-09-10
We study the radio-FIR correlation between the nonthermal (synchrotron) radio continuum emission at {lambda}90 cm (333 MHz) and the far-infrared emission due to cool ({approx}20 K) dust at {lambda}70 {mu}m in spatially resolved normal galaxies at scales of {approx}1 kpc. The slope of the radio-FIR correlation significantly differs between the arm and interarm regions. However, this change is not evident at a lower wavelength of {lambda}20 cm (1.4 GHz). We find the slope of the correlation in the arm to be 0.8 {+-} 0.12 and we use this to determine the coupling between equipartition magnetic field (B{sub eq}) and gas density ({rho}{sub gas}) as B{sub eq}{proportional_to}{rho}{sup 0.51{+-}0.12}{sub gas}. This is close to what is predicted by magnetohydrodynamic simulations of turbulent interstellar medium, provided the same region produces both the radio and far-infrared emission. We argue that at 1 kpc scales this condition is satisfied for radio emission at 1.4 GHz and may not be satisfied at 333 MHz. The change of slope observed in the interarm region could be caused by propagation of low energy ({approx}1.5 GeV) and long-lived ({approx}10{sup 8} yr) cosmic-ray electrons at 333 MHz.
INTERMEDIATE-MASS HOT CORES AT {approx}500 AU: DISKS OR OUTFLOWS?
Energy Technology Data Exchange (ETDEWEB)
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.
CANDELS: THE PROGENITORS OF COMPACT QUIESCENT GALAXIES AT z {approx} 2
Energy Technology Data Exchange (ETDEWEB)
Barro, Guillermo; Faber, S. M.; Koo, David C.; Kocevski, Dale D.; Trump, Jonathan R.; Mozena, Mark; McGrath, Elizabeth; Cheung, Edmond; Fang, Jerome [UCO/Lick Observatory and Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Perez-Gonzalez, Pablo G. [Departamento de Astrof isica, Facultad de CC F isicas, Universidad Complutense de Madrid, F. CC. Fisicas, E-28040 Madrid (Spain); Williams, Christina C. [Astronomy Department, University of Massachusetts, 710 N. Pleasant Street, Amherst, MA 01003 (United States); Van der Wel, Arjen [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Wuyts, Stijn [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, Giessenbachstr., D-85741 Garching (Germany); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI 48109 (United States); Croton, Darren J. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122 (Australia); Ceverino, Daniel; Dekel, Avishai [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Ashby, M. L. N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Ferguson, Henry C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Fontana, Adriano [INAF Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monteporzio, Rome (Italy); and others
2013-03-10
We combine high-resolution Hubble Space Telescope/WFC3 images with multi-wavelength photometry to track the evolution of structure and activity of massive (M{sub *} > 10{sup 10} M{sub Sun }) galaxies at redshifts z = 1.4-3 in two fields of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. We detect compact, star-forming galaxies (cSFGs) whose number densities, masses, sizes, and star formation rates (SFRs) qualify them as likely progenitors of compact, quiescent, massive galaxies (cQGs) at z = 1.5-3. At z {approx}> 2, cSFGs present SFR = 100-200 M{sub Sun} yr{sup -1}, yet their specific star formation rates (sSFR {approx} 10{sup -9} yr{sup -1}) are typically half that of other massive SFGs at the same epoch, and host X-ray luminous active galactic nuclei (AGNs) 30 times ({approx}30%) more frequently. These properties suggest that cSFGs are formed by gas-rich processes (mergers or disk-instabilities) that induce a compact starburst and feed an AGN, which, in turn, quench the star formation on dynamical timescales (few 10{sup 8} yr). The cSFGs are continuously being formed at z = 2-3 and fade to cQGs down to z {approx} 1.5. After this epoch, cSFGs are rare, thereby truncating the formation of new cQGs. Meanwhile, down to z = 1, existing cQGs continue to enlarge to match local QGs in size, while less-gas-rich mergers and other secular mechanisms shepherd (larger) SFGs as later arrivals to the red sequence. In summary, we propose two evolutionary tracks of QG formation: an early (z {approx}> 2), formation path of rapidly quenched cSFGs fading into cQGs that later enlarge within the quiescent phase, and a late-arrival (z {approx}< 2) path in which larger SFGs form extended QGs without passing through a compact state.
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
Nuclear level densities below 40 MeV excitation energy in the mass region A approx equal 50
Energy Technology Data Exchange (ETDEWEB)
Avrigeanu, M.; Ivascu, M.; Avrigeanu, V. (Institutul de Fizica si Inginerie Nucleara, Bucharest (Romania))
1990-03-01
Consistent pre-equilibrium emission and statistical model calculations of fast neutron induced reaction cross sections are used to validate nuclear level densities for excitation energies up to 40 MeV in the mass region A{approx equal}50. A 'composed' level density approach has been employed by using the back-shifted Fermi gas model for excitation energies lower than 12 MeV and a realistic analytical formula for higher excitations. In the transition region from the BSFG model range to that of full applicability of the realistic formula, an interpolation between the predictions of the two models is adopted. The interpolation rule, suggested by microscopic level density calculations, has been validated through the comparison of the calculated and experimental cross sections. (orig.).
EARLY STAGES OF CLUSTER FORMATION: FRAGMENTATION OF MASSIVE DENSE CORES DOWN TO {approx}< 1000 AU
Energy Technology Data Exchange (ETDEWEB)
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
Energy Technology Data Exchange (ETDEWEB)
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.
Structure of high-spin states in A {approx} 60 region
Energy Technology Data Exchange (ETDEWEB)
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.)
Wang, Yiwei; Binaud, Nicolas; Gogu, Christian; Bes, Christian; Fu, Jian
2016-12-01
Prediction of fatigue crack length in aircraft fuselage panels is one of the key issues for aircraft structural safety since it helps prevent catastrophic failures. Accurate estimation of crack length propagation is also meaningful for helping develop aircraft maintenance strategies. Paris' law is often used to capture the dynamics of fatigue crack propagation in metallic material. However, uncertainties are often present in the crack growth model, measured crack size and pressure differential in each flight and need to be accounted for accurate prediction. The aim of this paper is to estimate the two unknown Paris' law constants m and C as well as the crack length evolution by taking into account these uncertainties. Due to the nonlinear nature of the Paris' law, we propose here an on-line estimation algorithm based on two widespread nonlinear filtering techniques, Extended Kalman filter (EKF) and Unscented Kalman filter (UKF). The numerical experiments indicate that both EKF and UKF estimated the crack length well and accurately identified the unknown parameters. Although UKF is theoretical superior to EKF, in this Paris' law application EKF is comparable in accuracy to UKF and requires less computational expense.
Energy Technology Data Exchange (ETDEWEB)
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.
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...
CANDELS: CONSTRAINING THE AGN-MERGER CONNECTION WITH HOST MORPHOLOGIES AT z {approx} 2
Energy Technology Data Exchange (ETDEWEB)
Kocevski, Dale D.; Faber, S. M.; Mozena, Mark; Trump, Jonathan R.; Koo, David C. [University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Koekemoer, Anton M.; Somerville, Rachel S.; Lotz, Jennifer M.; Dahlen, Tomas; Donley, Jennifer L. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Nandra, Kirpal; Brusa, Marcella; Wuyts, Stijn [Max-Planck-Institut fuer extraterrestrische Physik, D-85748 Garching (Germany); Rangel, Cyprian; Laird, Elise S. [Astrophysics Group, Imperial College London, London, SW7 2AZ (United Kingdom); Bell, Eric F. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Alexander, David M. [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Bournaud, Frederic [CEA, IRFU, SAp and Laboratoire AIM Paris-Saclay, F-91191 Gif-sur-Yvette (France); Conselice, Christopher J. [Centre for Astronomy and Particle Theory, University of Nottingham, Nottingham, NG7 2RD (United Kingdom); Dekel, Avishai, E-mail: kocevski@ucolick.org [Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel); and others
2012-01-10
Using Hubble Space Telescope/WFC3 imaging taken as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, we examine the role that major galaxy mergers play in triggering active galactic nucleus (AGN) activity at z {approx} 2. Our sample consists of 72 moderate-luminosity (L{sub X} {approx} 10{sup 42-44} erg s{sup -1}) AGNs at 1.5 < z < 2.5 that are selected using the 4 Ms Chandra observations in the Chandra Deep Field South, the deepest X-ray observations to date. Employing visual classifications, we have analyzed the rest-frame optical morphologies of the AGN host galaxies and compared them to a mass-matched control sample of 216 non-active galaxies at the same redshift. We find that most of the AGNs reside in disk galaxies (51.4{sup +5.8}{sub -5.9}%), while a smaller percentage are found in spheroids (27.8{sup +5.8}{sub -4.6}%). Roughly 16.7{sup +5.3}{sub -3.5}% of the AGN hosts have highly disturbed morphologies and appear to be involved in a major merger or interaction, while most of the hosts (55.6{sup +5.6}{sub -5.9}%) appear relatively relaxed and undisturbed. These fractions are statistically consistent with the fraction of control galaxies that show similar morphological disturbances. These results suggest that the hosts of moderate-luminosity AGNs are no more likely to be involved in an ongoing merger or interaction relative to non-active galaxies of similar mass at z {approx} 2. The high disk fraction observed among the AGN hosts also appears to be at odds with predictions that merger-driven accretion should be the dominant AGN fueling mode at z {approx} 2, even at moderate X-ray luminosities. Although we cannot rule out that minor mergers are responsible for triggering these systems, the presence of a large population of relatively undisturbed disk-like hosts suggests that the stochastic accretion of gas plays a greater role in fueling AGN activity at z {approx} 2 than previously thought.
THE ROAD TO THE RED SEQUENCE: A DETAILED VIEW OF THE FORMATION OF A MASSIVE GALAXY AT z {approx} 2
Energy Technology Data Exchange (ETDEWEB)
Ferreras, Ignacio [Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom); Pasquali, Anna [Astronomisches Rechen Institut, Zentrum fuer Astronomie der Universitaet Heidelberg, Moenchhofstrasse 12-14, 69120 Heidelberg (Germany); Khochfar, Sadegh [Theoretical Modelling of Cosmic Structures Group, Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstr., D-85748 Garching (Germany); Kuntschner, Harald; Kuemmel, Martin [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany); Pirzkal, Nor [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Windhorst, Rogier; Malhotra, Sangeeta; Rhoads, James; Cohen, Seth [Department of Physics and Astronomy, Arizona State University, P.O. Box 871504, Tempe, AZ 85287-1504 (United States); O' Connell, Robert W. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Hathi, Nimish P. [Observatories of the Carnegie Institute of Washington, Pasadena, CA 91101 (United States); Ryan, Russell E. [Physics Department, University of California, Davis, CA 95616 (United States); Yan Haojing, E-mail: ferreras@star.ucl.ac.uk [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States)
2012-08-15
Over half of the census of massive galaxies at z {approx} 2 are dominated by quiescent stellar populations. The formation mechanism for these galaxies is still under debate, with models relying either on massive and early mergers or cold accretion. It is therefore imperative to understand in detail the properties of these galaxies. We present here a detailed analysis of the star formation history (SFH) of FW4871, a massive galaxy at z = 1.893 {+-} 0.002. We compare rest-frame optical and NUV slitless grism spectra from the Hubble Space Telescope with a large set of composite stellar populations to constrain the underlying SFH. Even though the morphology features prominent tidal tails, indicative of a recent merger, there is no sign of ongoing star formation within an aperture encircling one effective radius, which corresponds to a physical extent of 2.6 kpc. A model assuming truncation of an otherwise constant SFH gives a formation epoch z{sub F} {approx} 10 with a truncation after 2.7 Gyr, giving a mass-weighted age of 1.5 Gyr and a stellar mass of (0.8-3) Multiplication-Sign 10{sup 11} M{sub Sun} (the intervals representing the output from different population synthesis models), implying star formation rates of 30-110 M{sub Sun} yr{sup -1}. A more complex model including a recent burst of star formation places the age of the youngest component at 145{sup +450}{sub -70} Myr, with a mass contribution lower than 20%, and a maximum amount of dust reddening of E(B - V) < 0.4 mag (95% confidence levels). This low level of dust reddening is consistent with the low emission observed at 24 {mu}m, corresponding to rest-frame 8 {mu}m, where polycyclic aromatic hydrocarbon emission should contribute significantly if a strong formation episode were present. The color profile of FW4871 does not suggest a significant radial trend in the properties of the stellar populations out to 3 R{sub e}. We suggest that the recent merger that formed FW4871 is responsible for the quenching
METALLICITY EVOLUTION OF DAMPED Ly{alpha} SYSTEMS OUT TO z {approx} 5
Energy Technology Data Exchange (ETDEWEB)
Rafelski, Marc [Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125 (United States); Wolfe, Arthur M.; Neeleman, Marcel; Mendez, Alexander J. [Department of Physics and Center for Astrophysics and Space Sciences, UCSD, La Jolla, CA 92093 (United States); Prochaska, J. Xavier [Department of Astronomy and Astrophysics, UCO/Lick Observatory, 1156 High Street, University of California, Santa Cruz, CA 95064 (United States)
2012-08-20
We present chemical abundance measurements for 47 damped Ly{alpha} (DLA) systems, 30 at z > 4, observed with the Echellette Spectrograph and Imager and the High Resolution Echelle Spectrometer on the Keck telescopes. H I column densities of the DLAs are measured with Voigt profile fits to the Ly{alpha} profiles, and we find an increased number of false DLA identifications with Sloan Digital Sky Survey at z > 4 due to the increased density of the Ly{alpha} forest. Ionic column densities are determined using the apparent optical depth method, and we combine our new metallicity measurements with 195 from previous surveys to determine the evolution of the cosmic metallicity of neutral gas. We find the metallicity of DLAs decreases with increasing redshift, improving the significance of the trend and extending it to higher redshifts, with a linear fit of -0.22 {+-} 0.03 dex per unit redshift from z = 0.09-5.06. The metallicity 'floor' of Almost-Equal-To 1/600 solar continues out to z {approx} 5, despite our sensitivity for finding DLAs with much lower metallicities. However, this floor is not statistically different from a steep tail to the distribution. We also find that the intrinsic scatter of metallicity among DLAs of {approx}0.5 dex continues out to z {approx} 5. In addition, the metallicity distribution and the {alpha}/Fe ratios of z > 2 DLAs are consistent with being drawn from the same parent population with those of halo stars. It is therefore possible that the halo stars in the Milky Way formed out of gas that commonly exhibits DLA absorption at z > 2.
DEFF Research Database (Denmark)
Svendsen, Casper Steinmann; Bratholm, L.A.; Olsen, Jógvan Magnus Haugaard
2017-01-01
Full-protein nuclear magnetic resonance (NMR) shielding constants based on ab initio calculations are desirable, because they can assist in elucidating protein structures from NMR experiments. In this work, we present NMR shielding constants computed using a new automated fragmentation (J. Phys. ...... can obtain a representative subset of snapshots that gives the smallest predicted error, compared to experiment. Finally, we use this subset of snapshots to calculate the NMR shielding constants at the PE-KT3/pcSseg-2 level of theory for all atoms in the protein GB3....
Microscopic description of systematic doublet bands in the A {approx} 130 region
Energy Technology Data Exchange (ETDEWEB)
Yoshinaga, Naotaka [Department of Physics, Saitama University, Saitama City 338-8570 (Japan); Higashiyama, Koji [Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033 (Japan)
2005-10-01
The properties of the yrast and yrare states with the {nu}h{sub 11/2} x {pi}h{sub 11/2} configuration in the mass A {approx} 130 region are studied by a full microscopic theoretical framework of the pair-truncated shell model. This approach for energy levels and electromagnetic transition rates in {sup 134}La gives good agreement with experiment. The analysis of the wavefunctions reveals new band structure, which results from chopsticks configurations of two angular momenta of the unpaired neutron and the unpaired proton, weakly coupled with the quadrupole collective excitations of the even-even core.
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...
Generalized Pickands constants
Debicki, K.G.
2001-01-01
Pickands constants play an important role in the exact asymptotic of extreme values for Gaussian stochastic processes. By the {it generalized Pickands constant ${cal H_{eta$ we mean the limit begin{eqnarray* {cal H_{eta= lim_{T to inftyfrac{ {cal H_{eta(T){T, end{eqnarray* where ${cal H_{eta(T)= Exp
Directory of Open Access Journals (Sweden)
Hadjeb R.
2013-07-01
Full Text Available Ten compounds hydroxybases Schiff were synthesized from salicylaldehyde and the substituted aniline in the ortho, meta and para methyl groups, chloro and nitro. To study the effect of substituents on their acidities, the acid dissociation constants( Ka of salicylideneaniline and some of their derivatives were determined by pH-metric titration. All Schiff bases were titrated with NaOH in mixtures of 60% dioxane-water and 60% ethanol-water at a constant ionic strength and a temperature of 25 °C. The calculated acidity constants, pKa values were evaluated in protonation –deprotanation mechanisms. The Hammett relationship linear type was applied to quantify the effects of substituents on the acidity of hydroxybases Schiff, and therefore a reaction constant, ρ is calculated.
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.
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 ...
MEASUREMENT OF 21 cm BRIGHTNESS FLUCTUATIONS AT z {approx} 0.8 IN CROSS-CORRELATION
Energy Technology Data Exchange (ETDEWEB)
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.
New Star Forming Galaxies at $z\\approx 7$ from WFC3 Imaging
Wilkins, Stephen M; Lorenzoni, Silvio; Caruana, Joseph; Astrophysics, - Oxford
2010-01-01
The addition of Wide Field Camera 3 (WFC3) on the {\\em Hubble Space Telescope} ({\\em HST}) has led to a dramatic increase in our ability to study the $z>6$ Universe. The increase in the near-infrared (NIR) sensitivity of WFC3 over previous instruments has enabled us to reach apparent magnitudes approaching 29 (AB). This allows us to probe the rest-frame ultraviolet (UV) continuum, redshifted into the NIR at $z>6$. Taking advantage of the large optical depths at this redshift, resulting in the Lyman-$\\alpha$ break, we use a combination of WFC3 imaging and pre-existing Advanced Camera for Surveys (ACS) imaging to search for $z\\approx 7$ over 4 fields. Our analysis reveals 29 new $z\\approx 7$ star forming galaxy candidates in addition to 16 pre-existing candidates already discovered in these fields. The improved statistics from our doubling of the robust sample of $z$-drop candidates confirms the previously observed evolution of the bright end of the luminosity function.
Windberger, A; Crespo López-Urrutia, J R; Bekker, H; Oreshkina, N S; Berengut, J C; Bock, V; Borschevsky, A; Dzuba, V A; Eliav, E; Harman, Z; Kaldor, U; Kaul, S; Safronova, U I; Flambaum, V V; Keitel, C H; Schmidt, P O; Ullrich, J; Versolato, O O
2015-04-17
We measure optical spectra of Nd-like W, Re, Os, Ir, and Pt ions of particular interest for studies of a possibly varying fine-structure constant. Exploiting characteristic energy scalings we identify the strongest lines, confirm the predicted 5s-4f level crossing, and benchmark advanced calculations. We infer two possible values for optical M2/E3 and E1 transitions in Ir^{17+} that have the highest predicted sensitivity to a variation of the fine-structure constant among stable atomic systems. Furthermore, we determine the energies of proposed frequency standards in Hf^{12+} and W^{14+}.
Hadjeb R.; Bara A.; Barkat D.
2013-01-01
Ten compounds hydroxybases Schiff were synthesized from salicylaldehyde and the substituted aniline in the ortho, meta and para methyl groups, chloro and nitro. To study the effect of substituents on their acidities, the acid dissociation constants( Ka) of salicylideneaniline and some of their derivatives were determined by pH-metric titration. All Schiff bases were titrated with NaOH in mixtures of 60% dioxane-water and 60% ethanol-water at a constant ionic strength and a temperature of 25 °...
Mao, Jun; Hou, Jian; Shen, Dong
2013-03-01
This article describes the control system of PID parameter self-tuning fuzzy controller. For cutting the coal of different hardness, adopt fuzzy techniques, automatically adjust the feed speed of operating mechanism, and maintain the control of operating mechanism of heading machine with constant power.
Fukuda, Ryoichi; Nakatsuji, Hiroshi
2005-07-22
The quasirelativistic (QR) generalized unrestricted Hartree-Fock method for the magnetic shielding constant [R. Fukuda, M. Hada, and H. Nakatsuji, J. Chem. Phys. 118, 1015 (2003); R. Fukuda, M. Hada, and H. Nakatsuji, J. Chem. Phys.118, 1027 (2003)] has been extended to include the electron correlation effect in the level of the second-order Møller-Plesset perturbation theory (MP2). We have implemented the energy gradient and finite-perturbation methods to calculate the magnetic shielding constant at the QR MP2 level and applied to the magnetic shielding constants and the NMR chemical shifts of 125Te nucleus in various tellurium compounds. The calculated magnetic shielding constants and NMR chemical shifts well reproduced the experimental values. The relations of the chemical shifts with the natures of ligands, and the tellurium oxidation states were investigated. The chemical shifts in different valence states were explained by the paramagnetic shielding and spin-orbit terms. The tellurium 5p electrons are the dominant origin of the chemical shifts in the Te I and Te II compounds and the chemical shifts were explained by the p-hole mechanism. The tellurium d electrons also play an important role in the chemical shifts of the hypervalent compounds.
Variation of Fundamental Constants
Flambaum, V. V.
2006-11-01
Theories unifying gravity with other interactions suggest temporal and spatial variation of the fundamental ``constants'' in expanding Universe. The spatial variation can explain a fine tuning of the fundamental constants which allows humans (and any life) to appear. We appeared in the area of the Universe where the values of the fundamental constants are consistent with our existence. We present a review of recent works devoted to the variation of the fine structure constant α, 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 Feshbach resonance.
Peselnick, L.; Robie, R.A.
1962-01-01
The recent measurements of the elastic constants of calcite by Reddy and Subrahmanyam (1960) disagree with the values obtained independently by Voigt (1910) and Bhimasenachar (1945). The present authors, using an ultrasonic pulse technique at 3 Mc and 25??C, determined the elastic constants of calcite using the exact equations governing the wave velocities in the single crystal. The results are C11=13.7, C33=8.11, C44=3.50, C12=4.82, C13=5.68, and C14=-2.00, in units of 1011 dyncm2. Independent checks of several of the elastic constants were made employing other directions and polarizations of the wave velocities. With the exception of C13, these values substantially agree with the data of Voigt and Bhimasenachar. ?? 1962 The American Institute of Physics.
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.
Radiographic constant exposure technique
DEFF Research Database (Denmark)
Domanus, Joseph Czeslaw
1985-01-01
The constant exposure technique has been applied to assess various industrial radiographic systems. Different X-ray films and radiographic papers of two producers were compared. Special attention was given to fast film and paper used with fluorometallic screens. Radiographic image quality...... was tested by the use of ISO wire IQI's and ASTM penetrameters used on Al and Fe test plates. Relative speed and reduction of kilovoltage obtained with the constant exposure technique were calculated. The advantages of fast radiographic systems are pointed out...
Bosma, Wieb
2009-01-01
The average value of log s(n)/n taken over the first N even integers is shown to converge to a constant lambda when N tends to infinity; moreover, the value of this constant is approximated and proven to be less than 0. Here s(n) sums the divisors of n less than n. Thus the geometric mean of s(n)/n, the growth factor of the function s, in the long run tends to be less than 1. This could be interpreted as probabilistic evidence that aliquot sequences tend to remain bounded.
Bou Malham, I; Letellier, P; Turmine, M
2007-04-15
The autoprotolysis constants (K(s)) of water - 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)) mixtures were determined at 298K over the composition range of 0 to 77.43vol.% bmimBF(4) using potentiometric method with a glass electrode. A slight increase in the autoprotolysis constant was observed when the salt was added to the water. The value of the ionic product of the medium then decreases as the bmimBF(4) content increases from about 20vol.%. The acid-base properties of these media were perfectly described by Bahe's approaches that were completed by Varela et al. concerning structured electrolyte solutions with large short-range interactions.
Lobaton, E J; Salamon, T R
2007-10-01
The interface shape separating a gas layer within a superhydrophobic surface consisting of a square lattice of posts from a pressurized liquid above the surface is computed numerically. The interface shape is described by a constant mean curvature surface that satisfies the Young-Laplace equation with the three-phase gas-liquid-solid contact line assumed pinned at the post outer edge. The numerical method predicts the existence of constant mean curvature solutions from the planar, zero curvature solution up to a maximum curvature that is dependent on the post shape, size and pitch. An overall force balance between surface tension and pressure forces acting on the interface yields predictions for the maximum curvature that agree with the numerical simulations to within one percent for convex shapes such as circular and square posts, but significantly over predicts the maximum curvature for non-convex shapes such as a circular post with a sinusoidal surface perturbation. Changing the post shape to increase the contact line length, while maintaining constant post area, results in increases of 2 to 12% in the maximum computable curvature for contact line length increases of 11 to 77%. Comparisons are made to several experimental studies for interface shape and pressure stability.
Scott, Tricia
2015-11-01
Compassion is a powerful word that describes an intense feeling of commiseration and a desire to help those struck by misfortune. Most people know intuitively how and when to offer compassion to relieve another person's suffering. In health care, compassion is a constant; it cannot be rationed because emergency nurses have limited time or resources to manage increasing demands.
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...
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...
Measurement of the dipole response of neutron-rich nuclei in the A approx 20 region
Datta-Pramanik, U; Leistenschneider, A; Boretzky, K; Cortina-Gil, D; Elze, T W; Emling, H; Geissel, H; Grünschloss, A; Hellström, M; Holzmann, R; Ilievski, S; Iwasa, N; Kratz, J V; Kulessa, R; Leifels, Y; Lubkiewicz, E; Münzenberg, G; Reiter, P; Rejmund, M; Scheidenberger, C; Schlegel, C; Simon, H; Stroth, J; Sümmerer, K; Wajda, E; Walús, W
2002-01-01
Coulomb break up of the neutron-rich sup 1 sup 5 sup , sup 1 sup 7 C and sup 1 sup 7 sup - sup 2 sup 2 O isotopes has been studied experimentally using secondary beams at energies of 500-600 MeV/u. A comparison between differential cross sections, d sigma/dE sup * , with that obtained from a binary model shows that the main ground-state configuration of sup 1 sup 5 C is sup 1 sup 4 C(0 sup +)centre dot nu sub S sub sub 1 sub sub / sub sub 2 as expected. For sup 1 sup 7 C, our preliminary data analysis reveals that the predominant (approx 64%) configuration of the ground state is sup 1 sup 6 C(2 sup +)centre dot nu sub s sub , sub d. For sup 1 sup 7 sup - sup 2 sup 2 O, the low-lying E1 strength amounts up to about 12% of the energy weighted sum rule strength depending on neutron number. The energy weighted E1 strength (integrated up to 15 MeV excitation energy) increases up to sup 2 sup 0 O then decreases for sup 2 sup 1 sup , sup 2 sup 2 O. These data are compared to a shell model calculation.
THE DIRECT DETECTION OF COOL, METAL-ENRICHED GAS ACCRETION ONTO GALAXIES AT z {approx} 0.5
Energy Technology Data Exchange (ETDEWEB)
Rubin, Kate H. R.; Xavier Prochaska, J. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany); Koo, David C. [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High St, Santa Cruz, CA 95064 (United States); Phillips, Andrew C., E-mail: rubin@mpia.de [UCO/Lick Observatory, University of California, 1156 High St, Santa Cruz, CA 95064 (United States)
2012-03-10
We report on the discovery of cool gas inflow toward six star-forming galaxies with redshifts z {approx} 0.35-1. Analysis of Mg II and Fe II resonance-line absorption in Keck/LRIS spectroscopy of the galaxies reveals positive velocity shifts for cool gas of 80-200 km s{sup -1} with respect to the host galaxy velocity centroids, and equivalent widths for this inflow of {approx}> 0.6 A in five of the six objects. The host galaxies exhibit a wide range of star formation rates (SFRs {approx}1-40 M{sub Sun} yr{sup -1}) and have stellar masses similar to that of the Milky Way (log M{sub *}/M{sub Sun} {approx} 9.6-10.5). Imaging from the Hubble Space Telescope Advanced Camera for Surveys indicates that five of the six galaxies have highly inclined (i > 55 Degree-Sign ), disk-like morphologies. These data represent the first unambiguous detection of inflow into isolated, star-forming galaxies in the distant universe. We suggest that the inflow is due to the infall of enriched material from dwarf satellites and/or a galactic fountain within the galaxies. Assuming that the material has been enriched to 0.1 Z{sub Sun} and has a physical extent approximately equal to that of the galaxies (implied by the high observed gas covering fractions), we infer mass inflow rates of dM{sub in}/dt {approx}> 0.2-3 M{sub Sun} yr{sup -1} for four of these systems. Finally, from comparison of these absorption lines to the profiles of Mg II and Fe II absorption in a larger spectroscopic sample of {approx}100 objects, we measure a covering fraction of cool inflow of at least 6%, but cannot rule out the presence of enriched infall onto as many as {approx}40 of these galaxies.
Institute of Scientific and Technical Information of China (English)
张寅平; 胡先旭; 郝磬; 王馨
2003-01-01
This paper analyzes the convective heat transfer enhancement mechanism of latent heat functionally thermal fluid. By using the proposed internal heat source model, the influence of each factor affecting the heat transfer enhancement of laminar flow in a circular tube with constant heat flux is analyzed. The main influencing factors and the mechanisms of heat transfer enhancement are clarified, and the influences of the main factors on the heat transfer enhancement are quantitatively analyzed. A modified Nusselt number for internal flow is introduced to describe more effectively the degree of heat transfer enhancement for latent functionally thermal fluid.
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.
Sorensen, E
1940-01-01
The conventional axial blowers operate on the high-pressure principle. One drawback of this type of blower is the relatively low pressure head, which one attempts to overcome with axial blowers producing very high pressure at a given circumferential speed. The Schicht constant-pressure blower affords pressure ratios considerably higher than those of axial blowers of conventional design with approximately the same efficiency.
String Scale Cosmological Constant
Chalmers, Gordon
2006-01-01
The cosmological constant is an unexplained until now phenomena of nature that requires an explanation through string effects. The apparent discrepancy between theory and experiment is enourmous and has already been explained several times by the author including mechanisms. In this work the string theory theory of abolished string modes is documented and given perturbatively to all loop orders. The holographic underpinning is also exposed. The matching with the data of the LIGO and D0 experi...
Jackson, Neal
2015-01-01
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 H0 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.
Energy Technology Data Exchange (ETDEWEB)
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.
Energy Technology Data Exchange (ETDEWEB)
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.
EVIDENCE FOR COLD ACCRETION: PRIMITIVE GAS FLOWING ONTO A GALAXY AT z {approx} 0.274
Energy Technology Data Exchange (ETDEWEB)
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.
Energy Technology Data Exchange (ETDEWEB)
Olsen, Karen P.; Rasmussen, Jesper; Toft, Sune; Zirm, Andrew W., E-mail: karen@dark-cosmology.dk [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)
2013-02-10
We quantify the presence of active galactic nuclei (AGNs) in a mass-complete (M {sub *} > 5 Multiplication-Sign 10{sup 10} M {sub Sun }) sample of 123 star-forming and quiescent galaxies at 1.5 {<=} z {<=} 2.5, using X-ray data from the 4 Ms Chandra Deep Field-South (CDF-S) survey. 41% {+-} 7% of the galaxies are detected directly in X-rays, 22% {+-} 5% with rest-frame 0.5-8 keV luminosities consistent with hosting luminous AGNs (L {sub 0.5-8keV} > 3 Multiplication-Sign 10{sup 42} erg s{sup -1}). The latter fraction is similar for star-forming and quiescent galaxies, and does not depend on galaxy stellar mass, suggesting that perhaps luminous AGNs are triggered by external effects such as mergers. We detect significant mean X-ray signals in stacked images for both the individually non-detected star-forming and quiescent galaxies, with spectra consistent with star formation only and/or a low-luminosity AGN in both cases. Comparing star formation rates inferred from the 2-10 keV luminosities to those from rest-frame IR+UV emission, we find evidence for an X-ray excess indicative of low-luminosity AGNs. Among the quiescent galaxies, the excess suggests that as many as 70%-100% of these contain low- or high-luminosity AGNs, while the corresponding fraction is lower among star-forming galaxies (43%-65%). Our discovery of the ubiquity of AGNs in massive, quiescent z {approx} 2 galaxies provides observational support for the importance of AGNs in impeding star formation during galaxy evolution.
History and progress in the accurate determination of the Avogadro constant
Energy Technology Data Exchange (ETDEWEB)
Becker, Peter [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)
2001-12-01
The Avogadro constant, N{sub A}, is a fundamental physical constant that relates any quantity at the atomic scale to its corresponding macroscopic scale. Inspired by the kinetic gas theory Avogadro proposed his hypothesis in 1811, in order to describe chemical reactions as an atomic process between atoms or molecules. Starting from his pioneering findings, the determination of this large number has fascinated generations of scientists up to this day. The review of methods aimed at finding a value for N{sub A} starts with the calculations made by Loschmidt (1865; N{sub A}{approx}72x10{sup 23} mol{sup -1}) who evaluated the number of molecules in a given gas volume, derived from estimates of molecular diameters and the mean free path length. Consideration of Brownian motion led to some more accurate determinations of N{sub A} around the beginning of the 20th century (Perrin (1908); N{sub A}{approx}6.7x10{sup 23} mol{sup -1}). Other methods developed in the following years are based on Millikan's oil drop experiment (1917, N{sub A}{approx}6.064(6)x10{sup 23} mol{sup -1}), on the counting of alpha particles emitted from radium or uranium (Rutherford (1909); N{sub A}{approx}6.16x10{sup 23} mol{sup -1}) and on investigations of molecular monolayers on liquids (Nuoy (1924); N{sub A}{approx}6.004x10{sup 23} mol{sup -1}). A modern method to derive N{sub A} from the density, the relative atomic mass, and the unit cell length was introduced by Bragg in 1913. It makes use of the diffraction of x-rays by the interatomic spacings of a crystal lattice and its periodic arrangement. The accuracy of this method is extremely affected by the fact that the lattice scale of the structurally imperfect lattice can be calibrated only approximately in SI units. Data of NA were, therefore, found to be in disagreement with other fundamental constants (Bearden (1931); N{sub A}{approx}6.019(3)x10{sup 23} mol{sup -1}). A break though was achieved with perfect crystals of silicon and x
Zhang, Haifeng; Kosinski, J A; Karim, Md Afzalul
2013-05-01
We describe an apparatus for the measurement of acoustic wave propagation under uniaxial loading featuring a special mechanism designed to assure a uniform mechanical load on a cube-shaped sample of piezoelectric material. We demonstrate the utility of the apparatus by determining the effects of stresses on acoustic wave speed, which forms a foundation for the final determination of the third-order elastic constants of langasite and langatate single crystals. The transit time method is used to determine changes in acoustic wave velocity as the loading is varied. In order to minimize error and improve the accuracy of the wave speed measurements, the cross correlation method is used to determine the small changes in the time of flight. Typical experimental results are presented and discussed.
Energy Technology Data Exchange (ETDEWEB)
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.
Directory of Open Access Journals (Sweden)
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.
Energy Technology Data Exchange (ETDEWEB)
Pentericci, L.; Fontana, A.; Castellano, M.; Grazian, A.; Boutsia, K.; Giallongo, E.; Maiolino, R.; Paris, D.; Santini, P. [INAF Osservatorio Astronomico di Roma, Via Frascati 33,00040 Monteporzio (Italy); Vanzella, E.; Cristiani, S. [INAF Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34131 Trieste (Italy); Dijkstra, M. [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany); Dickinson, M. [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726 (United States); Giavalisco, M. [Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States); Moorwood, A., E-mail: laura.pentericci@oa-roma.inaf.it [European Southern Observatory, Karl-Schwarzschild Strasse, 85748 Garching (Germany)
2011-12-20
We present the final results from our ultra-deep spectroscopic campaign with FORS2 at the ESO Very Large Telescope (VLT) for the confirmation of z {approx_equal} 7 'z-band dropout' candidates selected from our VLT/Hawk-I imaging survey over three independent fields. In particular, we report on two newly discovered galaxies at redshift {approx}6.7 in the New Technology Telescope Deep Field. Both galaxies show an Ly{alpha} emission line with rest-frame equivalent widths (EWs) of the order of 15-20 A and luminosities of (2-4) Multiplication-Sign 10{sup 42} erg s{sup -1}. We also present the results of ultra-deep observations of a sample of i-dropout galaxies, from which we set a solid upper limit on the fraction of interlopers. Out of the 20 z-dropouts observed we confirm 5 galaxies at 6.6 < z < 7.1. This is systematically below the expectations drawn on the basis of lower redshift observations: in particular, there is a significant lack of objects with intermediate Ly{alpha} EWs (between 20 and 55 A). We conclude that the observed trend for the rising fraction of Ly{alpha} emission in Lyman break galaxies from z {approx} 3 to z {approx} 6 is most probably reversed from z {approx} 6 to z {approx} 7. Explaining the observed rapid change in the Ly{alpha} emitter fraction among the dropout population with reionization requires a fast evolution of the neutral fraction of hydrogen in the universe. Assuming that the universe is completely ionized at z = 6 and adopting a set of semi-analytical models, we find that our data require a change of the neutral hydrogen fraction of the order of {Delta}{chi}{sub H{sub i}}{approx}0.6 in a time {Delta}z {approx} 1, provided that the escape fraction does not increase dramatically over the same redshift interval.
Hadron spectrum, quark masses and decay constants from light overlap fermions on large lattices
Energy Technology Data Exchange (ETDEWEB)
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.)
Design and Application of Uninstall Guider Based on Constant Overload%基于恒定重载的卸荷导轨副设计与应用
Institute of Scientific and Technical Information of China (English)
文怀栋; 史军; 姜美娜
2011-01-01
Against the problem of movement and crawl when we use digital machine at the present stage, designed a kind of uninstall guider which is based on constant overload. Introduced the structure principle, structure design and using of the uninstall guider. From the point of simple and practical elaborated the excellence of the uninstall guider when it is used to solved the problem of movement and crawl. Adopting two methods calculated the load of uninstall guider. The two methods are measurement of disc spring and rotating the adjustment bush. Also check the rated load of it. Determine the selection of bearings. Obviously, the uninstall guider, we related, could meet the requirement of constant overload.%针对现阶段国产大型数字化机床在使用过程中存在的运动及爬行问题,提出了一种基于恒定重载的卸荷导轨副的设计方法.介绍了该导轨副的结构原理、结构设计及其在重型加工中心上的应用,从简约、实用的角度阐述其在解决大型设备运动中产生振动、爬行问题的优越性.采用测量碟簧变形量和旋动调整套两种方法对卸荷导轨副所承受的载荷进行了计算,并对额定静载荷进行了校核,确定了轴承的选型.文中所设计的卸荷导轨副能够满足在恒定重载条件下使用.效果:运行平稳、安装方便、节约成本,且有效保持机床运动精度.
The rotational gamma-continuum in the mass region A approx 110
Bracco, A; Leoni, S; Camera, F; Million, B; Blasi, N; Falconi, G; Lo Bianco, G; Pignanelli, M; Vigezzi, E; Herskind, B; Bergström, M H; Varmette, P; Toermaenen, S; Maj, A; Kmiecik, M; Napoli, D R; Matsuo, M
2000-01-01
Unresolved gamma transitions of sup 1 sup 1 sup 4 Te and of sup 1 sup 1 sup 2 Sn sorted into one-dimensional and two-dimensional spectra have been studied. The reaction sup 6 sup 4 Ni + sup 5 sup 4 Cr at bombarding energies 230, 240, 250, 260, 270 MeV was used and the gamma-rays were detected with the EUROBALL array. In the case of the nucleus sup 1 sup 1 sup 4 Te the values of the multiplicity as a function of bombarding energy and of the moment of inertia were obtained. The effective moment of inertia was found to be almost constant in the interval I=20-40 Planck constant, in contrast to the decreasing behaviour of the dynamic moment of inertia for the terminating yrast band. The ridge valley structures in E subgamma sub sub 1 xE subgamma sub sub 2 spectra of sup 1 sup 1 sup 4 Te and of sup 1 sup 1 sup 2 Sn were analysed with the fluctuation analysis technique. The analysis of the two nuclei are compared to simulations based on microscopic cranking calculations with residual interactions included. A rather ...
Application of SCR Technology of Constant Water Level in Sewage Treatment Plant%恒水位SBR工艺在污水处理厂的应用
Institute of Scientific and Technical Information of China (English)
周志强; 张玉山; 叶晓娟
2016-01-01
安溪湖头镇污水处理厂采用连续进水、出水的恒水位SBR工艺，工程结构简单，占地面积小。经过三个月调试及一个月试运行，系统稳定，脱氮除磷效果良好，出水水质达到《城镇污水处理厂污染物排放标准》（GB 18918-2002）一级A标准。%The sewage treatment plant in Hutou town of An Xi adopts SCR technology of the constant water level in inlet and outlet water. The plant accounts for a smal area of the land and its engineering structure is simple. Through debugging for 3 months and trial operation for one month, the system is stable. The denitrogenation and dephosphorization show a good result, the water quality meets A standard of the ifrst grade (GB 18918-2002).
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.
Directory of Open Access Journals (Sweden)
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.
Decay constants in geochronology
Institute of Scientific and Technical Information of China (English)
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.
Energy Technology Data Exchange (ETDEWEB)
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.
Constant Proportion Portfolio Insurance
DEFF Research Database (Denmark)
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....... Frequent rebalancing limits how badly the position can go off track, but costs more than infrequent rebalancing. Gap risk resulting from a down jump that penetrates the floor adds another hard-to-manage risk. In this article, Jessen comparescommon hedging strategies for CPPI and explores how well each does...
Roy, Partha Pratim; Kovarich, Simona; Gramatica, Paola
2011-08-01
The crucial importance of the three central OECD principles for quantitative structure-activity relationship (QSAR) model validation is highlighted in a case study of tropospheric degradation of volatile organic compounds (VOCs) by OH, applied to two CADASTER chemical classes (PBDEs and (benzo-)triazoles). The application of any QSAR model to chemicals without experimental data largely depends on model reproducibility by the user. The reproducibility of an unambiguous algorithm (OECD Principle 2) is guaranteed by redeveloping MLR models based on both updated version of DRAGON software for molecular descriptors calculation and some freely available online descriptors. The Genetic Algorithm has confirmed its ability to always select the most informative descriptors independently on the input pool of variables. The ability of the GA-selected descriptors to model chemicals not used in model development is verified by three different splittings (random by response, K-ANN and K-means clustering), thus ensuring the external predictivity of the new models, independently of the training/prediction set composition (OECD Principle 5). The relevance of checking the structural applicability domain becomes very evident on comparing the predictions for CADASTER chemicals, using the new models proposed herein, with those obtained by EPI Suite.
The Interacting and Non-constant Cosmological Constant
Verma, Murli Manohar
2009-01-01
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, that 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 form of the dark energy driving the acceleration.
Quantum Theory without Planck's Constant
Ralston, John P
2012-01-01
Planck's constant was introduced as a fundamental scale in the early history of quantum mechanics. We find a modern approach where Planck's constant is absent: it is unobservable except as a constant of human convention. Despite long reference to experiment, review shows that Planck's constant cannot be obtained from the data of Ryberg, Davisson and Germer, Compton, or that used by Planck himself. In the new approach Planck's constant is tied to macroscopic conventions of Newtonian origin, which are dispensable. The precision of other fundamental constants is substantially improved by eliminating Planck's constant. The electron mass is determined about 67 times more precisely, and the unit of electric charge determined 139 times more precisely. Improvement in the experimental value of the fine structure constant allows new types of experiment to be compared towards finding "new physics." The long-standing goal of eliminating reliance on the artifact known as the International Prototype Kilogram can be accompl...
Energy Technology Data Exchange (ETDEWEB)
Yahia, I.S. [Nano-Science & Semiconductor Labs, Metallurgical Lab., Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Ganesh, V. [Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Shkir, M., E-mail: shkirphysics@gmail.com [Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); AlFaify, S. [Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Zahran, H.Y. [Nano-Science & Semiconductor Labs, Metallurgical Lab., Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Algarni, H. [Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Abutalib, M.M.; Al-Ghamdi, Attieh A. [Centre of Nanotechnology, Physics Department-Faculty of Science-AL Faisaliah Campus, King Abdulaziz University, Jeddah (Saudi Arabia); El-Naggar, A.M.; AlBassam, A.M. [Research Chair of Exploitation of Renewable Energy Applications in Saudi Arabia, Physics & Astronomy Dept., College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)
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{sup −12}. The higher value of linear and nonlinear parameters makes it suitable for optoelectronic applications.
Calculation of Thermochemical Constants of Propellants
Directory of Open Access Journals (Sweden)
K. P. Rao
1979-01-01
Full Text Available A method for calculation of thermo chemical constants and products of explosion of propellants from the knowledge of molecular formulae and heats of formation of the ingredients is given. A computer programme in AUTOMATH-400 has been established for the method. The results of application of the method for a number of propellants are given.
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...
Institute of Scientific and Technical Information of China (English)
GAO LiNa; ZHAI JiWei; YAO Xi
2009-01-01
Ba0.60Sr0.40Mg0.15Ti0.85O3-xmol%Mg2TiO4 (x = 0-40 mol%) (BSTM-MT) composite thin films were fabricated by sol-gel method.The precursor solution of these composite thin films was prepared through mixing the Ba0.60Sr0.40Mg0.15Ti0.85O3 and Mg2Ti04 solution.The microstructures and dielectric tunability of composite thin films were investigated.The dielectric constant of composite thin films can be tailored from 155 to 55 by changing the concentration of Mg2TiO4.The dielectric loss of these composite thin films were still kept below 0.01 and the tunability was above 20% at a dc-applied electric field of 500 kV/cm.Suitable dielectric constant,low dielectric loss,and high tunability of this kind of composite thin films can be useful for potential microwave tunable applications.
Energy Technology Data Exchange (ETDEWEB)
Vardaci, E.; Di Nitto, A.; Brondi, A.; La Rana, G.; Moro, R. [Universita di Napoli ' ' Federico II' ' , Istituto Nazionale di Fisica Nucleare and Dipartimento di Scienze Fisiche, Napoli (Italy); Nadotchy, P.N.; Trotta, M.; Ordine, A.; Boiano, A. [Istituto Nazionale di Fisica Nucleare, Napoli (Italy); Cinausero, M.; Fioretto, E.; Prete, G.; Rizzi, V.; Shetty, D. [Laboratori Nazionali di Legnaro dell' Istituto Nazionale di Fisica Nucleare, Legnaro (Padova) (Italy); Barbui, M.; Fabris, D.; Lunardon, M.; Montagnoli, G.; Moretto, S.; Viesti, G. [Istituto Nazionale di Fisica Nucleare and Dipartimento di Fisica, Padova (Italy); Gelli, N.; Lucarelli, F. [Istituto Nazionale di Fisica Nucleare e Dipartimento di Fisica, Firenze (Italy); Knyazheva, G.N.; Kozulin, E.M. [Joint Institute for Nuclear Research, Flerov Laboratory of Nuclear Reactions, Dubna, Moscow Region (Russian Federation)
2010-02-15
Light charged-particle multiplicities in the evaporation residue (ER) and fission (FF) channels from the reaction 200MeV {sup 32}S+{sup 100}Mo as well as ER and FF channel cross-sections have been measured and compared to the predictions of the statistical model (SM) to estimate the fission time scale. The statistical model fails in reproducing the whole set of data and no convincing estimate is possible. In particular, while pre-scission multiplicities can be reproduced, the model strongly overestimates proton and alpha particle multiplicities in the ER channel, irrespective of the SM input parameters and prescriptions used for the level density and the transmission coefficients. Same calculations performed on data from literature in the A {approx} 150 and excitation energy E{sub x}{approx} 100-200 MeV region, for the ER channel, provide similar conclusions. These findings repropose the problem of the reliability of the SM in describing the compound-nucleus decay and have a relevant impact on the extraction of the fission delay time through the use of the SM. (orig.)
Spectrophotometric determination of association constant
DEFF Research Database (Denmark)
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 Charge...
Constant-Pressure Hydraulic Pump
Galloway, C. W.
1982-01-01
Constant output pressure in gas-driven hydraulic pump would be assured in new design for gas-to-hydraulic power converter. With a force-multiplying ring attached to gas piston, expanding gas would apply constant force on hydraulic piston even though gas pressure drops. As a result, pressure of hydraulic fluid remains steady, and power output of the pump does not vary.
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 < 6.6. We find no significant evidence for Ly(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.
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.
Institute of Scientific and Technical Information of China (English)
彭志平
2015-01-01
针对高炉不同的出铁工况，设计出一种高炉出铁场除尘恒风压变频调速模型，以满足高炉出铁过程中的正常风量需要，保持恒定的除尘总管风压；通过出铁场除尘阀门控制技术，将除尘控制设置在炉前泥炮操作室，完成对除尘阀门和风机的操作。梅钢5#高炉（4070 m3，风机装机量2×2240 kW）应用表明，出铁场除尘风机吨铁总电耗为5.78 kW·h，节能减排效果明显。%According to different conditions of blast furnace casthouse, the article designs a frequency control model of speed regulation which can keep dedust pressure constant for blast furnace casthouse dust, can meet the needs of normal flue gas volume in the process of blast furnace production, can keep the pressure constant of gas piping stress. By means of the field dedusting valve control technology, due to it is set in the dust control mud gun in front of the furnace operation room, it can finish the operation of the dedusting valve and fan. The application in Meigang’s No.5 blast furnace fan installed with 2×2 (4 070 m3, 240 kW) shows that the field of iron dust removal fan ton iron total power consumption is 5.78 kW·h, energy conservation and emissions reduction effect is obviously.
Energy Technology Data Exchange (ETDEWEB)
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)
Reliability concerns with logical constants in Xilinx FPGA designs
Energy Technology Data Exchange (ETDEWEB)
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.
Energy Technology Data Exchange (ETDEWEB)
Savajols, H.
1996-05-13
This work concerns the study of the nuclear superdeformation phenomenon in the rare earth region (A {approx} 150). The superdeformed (SD) states in Gadolinium and Dysprosium isotopes were produced via heavy-ion induced reactions and studied with the (EUROGAM EUROpean GAmma-ray Microscope) gamma multidetector array. Precise level attenuation method (DSAM). From the derived quadrupole moments, we find large differences in deformation between the yrast bands in neighbour nuclei explained in terms of the case of nuclei corresponding to an axis ratio of 2:1, the shell gaps are not fixed at a specific particle number and deformation. Furthermore the present results indicate that the deformations associated with identical bands are different supporting the picture that mass and deformation changes tend to compensate in SB bands with the same moments of inertia. (author). 114 refs.
Ruzsa's Constant on Additive Functions
Institute of Scientific and Technical Information of China (English)
Jin Hui FANG; Yong Gao CHEN
2013-01-01
A function f:N → R is called additive if f(mn) =f(m)+f(n) for all m,n with (m,n) =1.Let μ(x) =maxn≤x(f(n)-f(n + 1)) and v(x) =maxn≤x(f(n + 1)-f(n)).In 1979,Ruzsa proved that there exists a constant c such that for any additive function f,μ(x) ≤ cv(x2) + cf,where cf is a constant depending only on f.Denote by Raf the least such constant c.We call Raf Ruzsa's constant on additive functions.In this paper,we prove that Raf ≤ 20.
Naturally Time Dependent Cosmological Constant
Gregori, A
2004-01-01
In the light of the proposal of hep-th/0207195, we discuss in detail the issue of the cosmological constant, explaining how can string theory naturally predict the value which is experimentally observed, without low-energy supersymmetry.
Varying constants, Gravitation and Cosmology
Uzan, Jean-Philippe
2010-01-01
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. It is thus of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We thus 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, meteorites 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 describ...
Inflation and the cosmological constant
Directory of Open Access Journals (Sweden)
FENG Chaojun
2014-08-01
Full Text Available By assuming the cosmological “constant” is no longer a constant during the inflation epoch,it is found that the cosmological constant fine-tuning problem is solved.In the meanwhile,inflation models could predict a large tensor-to-scalar ratio,correct power spectral index and a larger running of it.Furthermore,the e-folding number is large enough to overcome the horizon,flatness problems in the Big Bang cosmology.
Varying Constants, Gravitation and Cosmology
Directory of Open Access Journals (Sweden)
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.
Varying Constants, Gravitation and Cosmology
Uzan, Jean-Philippe
2011-12-01
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.
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.
Energy Technology Data Exchange (ETDEWEB)
Jones, Tucker; Ellis, Richard S. [Astronomy Department, California Institute of Technology, MC249-17, Pasadena, CA 91125 (United States); Richard, Johan [CRAL, Observatoire de Lyon, Universite Lyon 1, 9 Avenue Ch. Andre, F-69561 Saint Genis Laval Cedex (France); Jullo, Eric [Laboratoire d' Astrophysique de Marseille, Universite d' Aix-Marseille and CNRS, UMR7326, 38 rue F. Joliot-Curie, F-13388 Marseille Cedex 13 (France)
2013-03-01
We present and discuss measurements of the gas-phase metallicity gradient in four gravitationally lensed galaxies at z = 2.0-2.4 based on adaptive optics-assisted imaging spectroscopy with the Keck II telescope. Three galaxies with well-ordered rotation reveal metallicity gradients with lower gas-phase metallicities at larger galactocentric radii. Two of these display gradients much steeper than found locally, while a third has one similar to that seen in local disk galaxies. The fourth galaxy exhibits complex kinematics indicative of an ongoing merger and reveals an 'inverted' gradient with lower metallicity in the central regions. By comparing our sample to similar data in the literature for lower redshift galaxies, we determine that, on average, metallicity gradients must flatten by a factor of 2.6 {+-} 0.9 between z = 2.2 and the present epoch. This factor is in rough agreement with the size growth of massive galaxies, suggesting that inside-out growth can account for the evolution of metallicity gradients. Since the addition of our new data provides the first indication of a coherent picture of this evolution, we develop a simple model of chemical evolution to explain the collective data. We find that metallicity gradients and their evolution can be explained by the inward radial migration of gas together with a radial variation in the mass loading factor governing the ratio of outflowing gas to the local star formation rate. Average mass loading factors of {approx}< 2 are inferred from our model in good agreement with direct measurements of outflowing gas in z {approx_equal} 2 galaxies.
Energy Technology Data Exchange (ETDEWEB)
Carman, R J; Mildren, R P [Department of Physics, Macquarie University, North Ryde, Sydney NSW (Australia)
2003-01-07
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 -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 4,5} states that feed the VUV emitting Xe{sub 2}* excimer states. Calculations suggest that the overall conversion efficiency from electrical energy to VUV output in the plasma is greater than 60%, with >99% of the light output emitted in the VUV. Parasitic processes that act to reduce the key Xe* 1s{sub 4,5} and Xe{sub 2}* populations are found to be essentially negligible. For pulsed excitation, the longer-term spatio-temporal behaviour of the electron/ions during the afterglow or inter-pulse period is important, resulting in a remnant 'pre-pulse' ion density of {approx} 10{sup 15} m{sup -3} close to the cathode dielectric. These ions bombard the cathode during the subsequent excitation period to release the secondary (seed) electrons required to achieve electrical breakdown.
Energy Technology Data Exchange (ETDEWEB)
Anselmetti, F. S. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Duebendorf (Switzerland); Drescher-Schneider, R. [Institut fuer Pflanzenwissenschaften, Karl-Fanzen-Universitaet Graz, Graz (Austria); Furrer, H. [Palaeontologisches Institut und Museum, Universitaet Zuerich, Zuerich (Switzerland); Graf, H. R. [Matousek, Baumann und Niggli AG, Baden (Switzerland); Lowick, S. E.; Preusser, F. [Institut fuer Geologie, Universitaet Bern, Bern (Switzerland); Riedi, M. A. [Marc A. Riedi, Susenbuehlstrasse 41, Chur (Switzerland)
2010-11-15
A 30 m-deep drill core from a glacially overdeepened trough in Northern Switzerland recovered a {approx} 180 ka old sedimentary succession that provides new insights into the timing and nature of erosion-sedimentation processes in the Swiss lowlands. The luminescence-dated stratigraphic succession starts at the bottom of the core with laminated carbonate-rich lake sediments reflecting deposition in a proglacial lake between {approx} 180 and 130 ka ago (Marine Isotope Stage MIS 6). Anomalies in geotechnical properties and the occurrence of deformation structures suggest temporary ice contact around 140 ka. Up-core, organic content increases in the lake deposits indicating a warming of climate. These sediments are overlain by a peat deposit characterised by pollen assemblages typical of the late Eemian (MIS 5e). An abrupt transition following this interglacial encompasses a likely hiatus and probably marks a sudden lowering of the water level. The peat unit is overlain by deposits of a cold unproductive lake dated to late MIS 5 and MIS 4, which do not show any direct influence from glaciers. An upper peat unit, the so-called {sup M}ammoth peat{sup ,} previously encountered in construction pits, interrupts this cold lacustrine phase and marks more temperate climatic conditions between 60 and 45 ka (MIS 3). In the upper part of the core, a succession of fluvial and alluvial deposits documents the Late Glacial and Holocene sedimentation in the basin. The sedimentary succession at Wehntal confirms that the glaciation during MIS 6 did not apparently cause the overdeepening of the valley, as the lacustrine basin fill covering most of MIS 6 is still preserved. Consequently, erosion of the basin is most likely linked to an older glaciation. This study shows that new dating techniques combined with paleoenvironmental interpretations of sediments from such overdeepened troughs provide valuable insights into the past glacial history. (authors)
Alam, Md Mehebub; Ghosh, Sujoy Kumar; Sarkar, Debabrata; Sen, Shrabanee; Mandal, Dipankar
2017-01-06
Titanium dioxide (TiO2) nanoparticles (NPs) embedded Î³-phase containing polyvinylidene fluoride (PVDF) nanocomposite (PNC) film turns to an excellent material for energy storage application due to an increased dielectric constant (32 at 1 kHz), enhanced electric breakdown strength (400 MV m(-1)). It also exhibits a high energy density of 4 J cm(-3) which is 25 times higher than that of virgin PVDF. 98% of the electroactive γ-phase has been acheived by the incorporation of TiO2 NPs and the resulting PNC behaves like a super-toughened material due to a dramatic improvement (more than 80%) in the tensile strength. Owing to their electroactive nature and extraordinary mechanical properties, PNC films have a strong ability to fabricate the piezoelectric nanogenerators (PNGs) that have recently been an area of focus regarding mechanical energy harvesting. The feasibility of piezoelectric voltage generation from PNGs is demostrated under the rotating fan that also promises further utility such as rotational speed (RPM) determination.
Application of Constant-tension Spring Tensioner in Metro OCS Anchoring%恒张力弹簧补偿器在地铁接触网中的应用
Institute of Scientific and Technical Information of China (English)
汪理
2011-01-01
为适应新环境对接触网下锚补偿装置提出的要求,南京地铁在接触网下锚时使用恒张力弹簧补偿装置.阐述恒张力弹簧补偿装置的结构及工作原理,并将其与传统棘轮补偿装置进行对比；逐一分析恒张力弹簧补偿装置在不同条件下的应用,论证其在地铁应用的优越性.%In order to adapt the requirements of the OCS (Overhead Catenary System) anchoring, constant-tension spring tensioners were used in Nanjing metro. This article introduces the structure and working principles of this equipment and makes a contrast of it with the traditional wheel tensknung device. Moreover, it analyses the application of the spring tensioners in various working conditions in Nanjing metro and demonstrates their significant advantages.
Mehebub Alam, Md; Ghosh, Sujoy Kumar; Sarkar, Debabrata; Sen, Shrabanee; Mandal, Dipankar
2017-01-01
Titanium dioxide (TiO2) nanoparticles (NPs) embedded Î³-phase containing polyvinylidene fluoride (PVDF) nanocomposite (PNC) film turns to an excellent material for energy storage application due to an increased dielectric constant (32 at 1 kHz), enhanced electric breakdown strength (400 MV m-1). It also exhibits a high energy density of 4 J cm-3 which is 25 times higher than that of virgin PVDF. 98% of the electroactive γ-phase has been acheived by the incorporation of TiO2 NPs and the resulting PNC behaves like a super-toughened material due to a dramatic improvement (more than 80%) in the tensile strength. Owing to their electroactive nature and extraordinary mechanical properties, PNC films have a strong ability to fabricate the piezoelectric nanogenerators (PNGs) that have recently been an area of focus regarding mechanical energy harvesting. The feasibility of piezoelectric voltage generation from PNGs is demostrated under the rotating fan that also promises further utility such as rotational speed (RPM) determination.
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.
Learning Read-constant Polynomials of Constant Degree modulo Composites
DEFF Research Database (Denmark)
Chattopadhyay, Arkadev; Gavaldá, Richard; Hansen, Kristoffer Arnsfelt;
2011-01-01
Boolean functions that have constant degree polynomial representation over a fixed finite ring form a natural and strict subclass of the complexity class \\textACC0ACC0. They are also precisely the functions computable efficiently by programs over fixed and finite nilpotent groups. This class...... is not 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...
Energy Technology Data Exchange (ETDEWEB)
Ideue, Y. [Graduate School of Science and Engineering, Ehime University, Bunkyo-cho, Matsuyama 790-8577 (Japan); Taniguchi, Y.; Shioya, Y.; Kajisawa, M. [Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho, Matsuyama 790-8577 (Japan); Nagao, T. [The Hakubi Project, Kyoto University, Yoshida-Ushinomiya-cho, Sakyo-ku, Kyoto 606-8302 (Japan); Trump, J. R. [UCO/Lick, UC Santa Cruz, Santa Cruz, CA 95064 (United States); Vergani, D. [INAF-Osservatorio Astronomico di Bolona, Via Ranzani 1, I-40127 Bologna (Italy); Iovino, A. [INSF-Osservatorio Astronomico di Brera, Via Brera 28, I-20159 Milano (Italy); Koekemoer, A. M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Le Fevre, O. [Laboratoire d' Astrophysique de Marseile, CNRS-Universite d' Aix-Marseille, 38 rue Frederic Joliot Curie, F-13388 Marseille (France); Ilbert, O. [Observatoriore de Marseille-Provence, Pole de I' Etoile Site de Chiateau-Gombert, 38 rue Frederic Joliot-Curie, 13388 Marseille Cedex 13 (France); Scoville, N. Z., E-mail: ideue@cosmos.phys.sci.ehime-u.ac.jp [Department of Astronomy, MS 105-24, California Institute of Technology, Pasadena, CA 91125 (United States)
2012-03-01
In order to understand environmental effects on star formation in high-redshift galaxies, we investigate the physical relationships between the star formation activity, stellar mass, and environment for z {approx_equal} 1.2 galaxies in the 2 deg{sup 2} COSMOS field. We estimate star formation using the [O II]{lambda}3727 emission line and environment from the local galaxy density. Our analysis shows that for massive galaxies (M{sub *} {approx}> 10{sup 10} M{sub Sun }), the fraction of [O II] emitters in high-density environments ({Sigma}{sub 10th} {approx}> 3.9 Mpc{sup -2}) is 1.7 {+-} 0.4 times higher than in low-density environments ({Sigma}{sub 10th} {approx}< 1.5 Mpc{sup -2}), while the [O II] emitter fraction does not depend on environment for low-mass M{sub *} {approx}< 10{sup 10} M{sub Sun} galaxies. In order to understand what drives these trends, we investigate the role of companion galaxies in our sample. We find that the fraction of [O II] emitters in galaxies with companions is 2.4 {+-} 0.5 times as high as that in galaxies without companions at M{sub *} {approx}> 10{sup 10} M{sub Sun }. In addition, massive galaxies are more likely to have companions in high-density environments. However, although the number of star-forming galaxies increases for massive galaxies with close companions and in dense environments, the average star formation rate of star-forming galaxies at a given mass is independent of environment and the presence/absence of a close companion. These results suggest that interactions and/or mergers in a high-density environment could induce star formation in massive galaxies at z {approx} 1.2, increasing the fraction of star-forming galaxies with M{sub *} {approx}> 10{sup 10} M{sub Sun }.
Hathi, N. P.; Cohen, S. H.; Ryan, R. E., Jr.; Finkelstein, S. L.; McCarthy, P. J.; Windhorst, R. A.; Yan, H.; Koekemoer, A. M.; Rutkowski, M. J.; OConnell, R. W.; Straughn, A. N.; Balick, B.; Bond, H. E.; Calzetti, D.; Disney, M. J.; Dopita, M. A.; Frogel, Jay A.; Hall, D. N. B.; Holtzman, J. A.; Kimble, R. A.; Paresce, F.; Saha, A.; Silk, J. I.; Tauger, J. T.; Young, E. T.
2012-01-01
We analyze the spectral energy distributions (SEDs) of Lyman break galaxies . (LBGs) at z approx = 1-3 selected using the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) UVIS channel filters. These HST /WFC3 obse,rvations cover about 50 arcmin2 in the GOODS-South field as a part of the WFC3 Early Release Science program. These LBGs at z approx = 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 f3 is redder than at high redshift (z > 3), where LBGs are less dusty; (3) on average, LBGs at .z approx = 1-3 are massive, dustier and more highly star-forming, compared to LBGs at higher redshifts with similar luminosities, though their median values are similar within 1a uncertainties. This could imply that identical dropout selection technique, at all. redshifts, find 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 = 1.5 to 5. The star-forming galaxies selected using other color-based techniques show similar correlations at z approx = 2, but to avoid any selection biases, and for direct comparison with LBGs at z > 3, a true Lyman break selection at z approx = 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.
Energy Technology Data Exchange (ETDEWEB)
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.)
The fermion propagator in cosmological spaces with constant deceleration
Energy Technology Data Exchange (ETDEWEB)
Koksma, Jurjen F; Prokopec, Tomislav, E-mail: J.F.Koksma@uu.n, E-mail: T.Prokopec@uu.n [Institute for Theoretical Physics (ITP) and Spinoza Institute, Utrecht University, Postbus 80195, 3508 TD Utrecht (Netherlands)
2009-06-21
We calculate the fermion propagator in Friedmann-LemaItre-Robertson-Walker (FLRW) spacetimes with constant deceleration q=epsilon-1, epsilon=-H-dot/H{sup 2} for excited states. For fermions whose mass is generated by a scalar field through a Yukawa coupling m = g{sub Y}phi, we assume phi approx H. We first solve the mode functions by splitting the spinor into a direct product of helicity and chirality spinors. We also allow for non-vacuum states. We normalize the spinors using a consistent canonical quantization and by requiring orthogonality of particle and anti-particle spinors. We apply our propagator to calculate the one-loop effective action and renormalize using dimensional regularization. Since the Hubble parameter is now treated dynamically, this paves the way to study the dynamical backreaction of fermions on the background spacetime.
Bouncing universes with varying constants
Energy Technology Data Exchange (ETDEWEB)
Barrow, John D [DAMTP, Centre for Mathematical Sciences, Cambridge University, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Kimberly, Dagny [Theoretical Physics, Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2BZ (United Kingdom); Magueijo, Joao [Theoretical Physics, Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2BZ (United Kingdom)
2004-09-21
We investigate the behaviour of exact closed bouncing Friedmann universes in theories with varying constants. We show that the simplest BSBM varying alpha theory leads to a bouncing universe. The value of alpha increases monotonically, remaining approximately constant during most of each cycle, but increasing significantly around each bounce. When dissipation is introduced we show that in each new cycle the universe expands for longer and to a larger size. We find a similar effect for closed bouncing universes in Brans-Dicke theory, where G also varies monotonically in time from cycle to cycle. Similar behaviour occurs also in varying speed of light theories.
Bouncing Universes with Varying Constants
Barrow, J D; Magueijo, J; Barrow, John D.; Kimberly, Dagny; Magueijo, Joao
2004-01-01
We investigate the behaviour of exact closed bouncing Friedmann universes in theories with varying constants. We show that the simplest BSBM varying-alpha theory leads to a bouncing universe. The value of alpha increases monotonically, remaining approximately constant during most of each cycle, but increasing significantly around each bounce. When dissipation is introduced we show that in each new cycle the universe expands for longer and to a larger size. We find a similar effect for closed bouncing universes in Brans-Dicke theory, where $G$ also varies monotonically in time from cycle to cycle. Similar behaviour occurs also in varying speed of light theories.
Spatial Variations of Fundamental Constants
Barrow, John D; Barrow, John D.; Toole, Chris O'
1999-01-01
We show that observational limits on the possible time variation of constants of Nature are significantly affected by allowing for both space and time variation. Bekenstein's generalisation of Maxwell's equations to allow for cosmological variation of $alpha$ is investigated in a universe containing spherically symmetric inhomogeneities. The time variation of $alpha$ is determined by the local matter density and hence limits obtained in high-density geophysical enviroments are far more constraining than those obtained at high redshift. This new feature is expected to be a property of a wide class of theories for the variation of constants.
Mirror QCD and Cosmological Constant
Pasechnik, Roman; Teryaev, Oleg
2016-01-01
An analog of Quantum Chromo Dynamics (QCD) sector known as mirror QCD (mQCD) can affect the cosmological evolution and help in resolving the Cosmological Constant problem. In this work, we explore an intriguing possibility for a compensation of the negative QCD vacuum contribution to the ground state energy density of the universe by means of a positive contribution from the chromomagnetic gluon condensate in mQCD. The trace anomaly compensation condition and the form of the mQCD coupling constant in the infrared limit have been proposed by analysing a partial non-perturbative solution of the Einstein--Yang-Mills equations of motion.
Álvarez-Asencio, R; Thormann, E; Rutland, M W
2013-09-01
A technique has been developed for the calculation of torsional spring constants for AFM cantilevers based on the combination of the normal spring constant and plate/beam theory. It is easy to apply and allow the determination of torsional constants for stiff cantilevers where the thermal power spectrum is difficult to obtain due to the high resonance frequency and low signal/noise ratio. The applicability is shown to be general and this simple approach can thus be used to obtain torsional constants for any beam shaped cantilever.
Energy Technology Data Exchange (ETDEWEB)
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
Decay Constants of Vector Mesons
Institute of Scientific and Technical Information of China (English)
LI Heng-Mei; WAN Shao-Long
2008-01-01
@@ The light vector mesons are studied within the framework of the Bethe-Salpeter equation with the vector-vectortype flat-bottom potential The Bethe-Salpeter wavefunctions and the decay constants of the vector mesons are obtained. All the obtained results, fρ, fφ, and fΚ* , are in agreement with the experimental values, respectively.
Energy Technology Data Exchange (ETDEWEB)
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.
Variation of fundamental constants: theory
Flambaum, Victor
2008-05-01
Theories unifying gravity with other interactions suggest temporal and spatial variation of the fundamental ``constants'' in expanding Universe. There are some hints for the variation of different fundamental constants in quasar absorption spectra and Big Bang nucleosynthesis data. A large number of publications (including atomic clocks) report limits on the variations. We want to study the variation of the main dimensionless parameters of the Standard Model: 1. Fine structure constant alpha (combination of speed of light, electron charge and Plank constant). 2. Ratio of the strong interaction scale (LambdaQCD) to a fundamental mass like electron mass or quark mass which are proportional to Higgs vacuum expectation value. The proton mass is propotional to LambdaQCD, therefore, the proton-to-electron mass ratio comes into this second category. We performed necessary atomic, nuclear and QCD calculations needed to study variation of the fundamental constants using the Big Bang Nucleosynthsis, quasar spectra, Oklo natural nuclear reactor and atomic clock data. The relative effects of the variation may be enhanced in transitions between narrow close levels in atoms, molecules and nuclei. If one will study an enhanced effect, the relative value of systematic effects (which are not enhanced) may be much smaller. Note also that the absolute magnitude of the variation effects in nuclei (e.g. in very narrow 7 eV transition in 229Th) may be 5 orders of magnitude larger than in atoms. A different possibility of enhancement comes from the inversion transitions in molecules where splitting between the levels is due to the quantum tunneling amplitude which has strong, exponential dependence on the electron to proton mass ratio. Our study of NH3 quasar spectra has already given the best limit on the variation of electron to proton mass ratio.
Varying Fine-Structure Constant and the Cosmological Constant Problem
Fujii, Y
2003-01-01
We start with a brief account of the latest analysis of the Oklo phenomenon providing the still most stringent constraint on time-variability of the fine- structure constant $\\alpha$. Comparing this with the recent result from the measurement of distant QSO's appears to indicate a non-uniform time-dependence, which we argue to be related to another recent finding of the accelerating universe. This view is implemented in terms of the scalar-tensor theory, applied specifically to the small but nonzero cosmological constant. Our detailed calculation shows that these two phenomena can be understood in terms of a common origin, a particular behavior of the scalar field, dilaton. We also sketch how this theoretical approach makes it appropriate to revisit non- Newtonian gravity featuring small violation of Weak Equivalence Principle at medium distances.
Varying Fine-Structure Constant and the Cosmological Constant Problem
Fujii, Yasunori
We start with a brief account of the latest analysis of the Oklo phenomenon providing the still most stringent constraint on time variability of the fine-structure constant α. Comparing this with the recent result from the measurement of distant QSO's appears to indicate a non-uniform time-dependence, which we argue to be related to another recent finding of the accelerating universe. This view is implemented in terms of the scalar-tensor theory, applied specifically to the small but nonzero cosmological constant. Our detailed calculation shows that these two phenomena can be understood in terms of a common origin, a particular behavior of the scalar field, dilaton. We also sketch how this theoretical approach makes it appropriate to revisit non-Newtonian gravity featuring small violation of Weak Equivalence Principle at medium distances.
New Quasar Studies Keep Fundamental Physical Constant Constant
2004-03-01
Very Large Telescope sets stringent limit on possible variation of the fine-structure constant over cosmological time Summary Detecting or constraining the possible time variations of fundamental physical constants is an important step toward a complete understanding of basic physics and hence the world in which we live. A step in which astrophysics proves most useful. Previous astronomical measurements of the fine structure constant - the dimensionless number that determines the strength of interactions between charged particles and electromagnetic fields - suggested that this particular constant is increasing very slightly with time. If confirmed, this would have very profound implications for our understanding of fundamental physics. New studies, conducted using the UVES spectrograph on Kueyen, one of the 8.2-m telescopes of ESO's Very Large Telescope array at Paranal (Chile), secured new data with unprecedented quality. These data, combined with a very careful analysis, have provided the strongest astronomical constraints to date on the possible variation of the fine structure constant. They show that, contrary to previous claims, no evidence exist for assuming a time variation of this fundamental constant. PR Photo 07/04: Relative Changes with Redshift of the Fine Structure Constant (VLT/UVES) A fine constant To explain the Universe and to represent it mathematically, scientists rely on so-called fundamental constants or fixed numbers. The fundamental laws of physics, as we presently understand them, depend on about 25 such constants. Well-known examples are the gravitational constant, which defines the strength of the force acting between two bodies, such as the Earth and the Moon, and the speed of light. One of these constants is the so-called "fine structure constant", alpha = 1/137.03599958, a combination of electrical charge of the electron, the Planck constant and the speed of light. The fine structure constant describes how electromagnetic forces hold
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...
Energy Technology Data Exchange (ETDEWEB)
Parrish, Randall R. [Department of Geology, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Notts, NG12 5GG (United Kingdom)], E-mail: rrp@nigl.nerc.ac.uk; Horstwood, Matthew [NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Notts, NG12 5GG (United Kingdom); Arnason, John G. [Department of Earth and Atmospheric Sciences, University at Albany, 1400 Washington Avenue, Albany NY 12222 (United States); Chenery, Simon [British Geological Survey, Keyworth, Notts, NG12 5GG (United Kingdom); Brewer, Tim [Department of Geology, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Lloyd, Nicholas S. [Department of Geology, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); British Geological Survey, Keyworth, Notts, NG12 5GG (United Kingdom); Carpenter, David O. [Institute for Health and the Environment, University at Albany, Five University Place, Room A217, Rensselaer, NY 12144-3456 (United States)
2008-02-01
Inhaled depleted uranium (DU) aerosols are recognised as a distinct human health hazard and DU has been suggested to be responsible in part for illness in both military and civilian populations that may have been exposed. This study aimed to develop and use a testing procedure capable of detecting an individual's historic milligram-quantity aerosol exposure to DU up to 20 years after the event. This method was applied to individuals associated with or living proximal to a DU munitions plant in Colonie New York that were likely to have had a significant DU aerosol inhalation exposure, in order to improve DU-exposure screening reliability and gain insight into the residence time of DU in humans. We show using sensitive mass spectrometric techniques that when exposure to aerosol has been unambiguous and in sufficient quantity, urinary excretion of DU can be detected more than 20 years after primary DU inhalation contamination ceased, even when DU constitutes only {approx} 1% of the total excreted uranium. It seems reasonable to conclude that a chronically DU-exposed population exists within the contamination 'footprint' of the munitions plant in Colonie, New York. The method allows even a modest DU exposure to be identified where other less sensitive methods would have failed entirely. This should allow better assessment of historical exposure incidence than currently exists.
Energy Technology Data Exchange (ETDEWEB)
Lobach, V.A.; Sobolev, A.B.; Shul' gin, B.V.
1987-05-01
Calculations have been performed on the clusters (A/sub x/B/sub y/) (x = 1, 13; y = 6, 14), corresponding to perfect crystals of the alkaline-earth oxides (AEO) MgO, CaO, and SrO by means of methods involving molecular clusters (MC) and crystalline clusters (CC) in the SCF-X/sub approx./-RW method. It is found that MC is unsuitable for describing perfect AEO, because they have a long-range Coulomb interaction and a potential cluster effect. Even in the CC method, the nonstoichiometric composition of (A/sub x/B/sub y/) for x < 13 and y < 14 does not allow one to obtain satisfactory agreement with the observed optical and x-ray spectra. The (A/sub 13/B/sub 14/) and (B/sub 13/A/sub 14/) clusters reproduce satisfactorily the partial composition of the valence band (VB) and the conduction band (CB), as well as the widths of those bands, the fine structure of the K emission spectrum for oxygen in MgO, and the observed electron-density distribution. A study is made of the effects of varying the radii of the spheres on the error from the region between the spheres with muffin-tin averaging.
Constant-bandwidth constant-temperature hot-wire anemometer.
Ligeza, P
2007-07-01
A constant-temperature anemometer (CTA) enables the measurement of fast-changing velocity fluctuations. In the classical solution of CTA, the transmission band is a function of flow velocity. This is a minor drawback when the mean flow velocity does not significantly change, though it might lead to dynamic errors when flow velocity varies over a considerable range. A modification is outlined, whereby an adaptive controller is incorporated in the CTA system such that the anemometer's transmission band remains constant in the function of flow velocity. For that purpose, a second feedback loop is provided, and the output signal from the anemometer will regulate the controller's parameters such that the transmission bandwidth remains constant. The mathematical model of a CTA that has been developed and model testing data allow a through evaluation of the proposed solution. A modified anemometer can be used in measurements of high-frequency variable flows in a wide range of velocities. The proposed modification allows the minimization of dynamic measurement errors.
Infrared propagator corrections for constant deceleration
Energy Technology Data Exchange (ETDEWEB)
Janssen, T M; Miao, S P; Prokopec, T [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, Leuvenlaan 4, Postbus 80.195, 3508 TD Utrecht (Netherlands); Woodard, R P [Department of Physics, University of Florida Gainesville, FL 32611 (United States)], E-mail: T.M.Janssen@uu.nl, E-mail: S.Miao@uu.nl, E-mail: T.Prokopec@uu.nl, E-mail: woodard@phys.ufl.edu
2008-12-21
We derive the propagator for a massless, minimally coupled scalar on a D-dimensional, spatially flat, homogeneous and isotropic background with arbitrary constant deceleration parameter. Our construction uses the operator formalism by integrating the Fourier mode sum. We give special attention to infrared corrections from the nonzero lower limit associated with working on finite spatial sections. These corrections eliminate infrared divergences that would otherwise be incorrectly treated by dimensional regularization, resulting in off-coincidence divergences for those special values of the deceleration parameter at which the infrared divergence is logarithmic. As an application we compute the expectation value of the scalar stress-energy tensor.
Institute of Scientific and Technical Information of China (English)
黄建刚; 吴杰; 谢海武; 周泽坤; 明鑫; 张波
2012-01-01
A kind of on timer circuit applicable to constant on-time mode control was put forward in this paper.ln the circuit the current that proportional to the input voltage charge the capacitance,so as to realize the timing of time is inversely proportional to the input voltage,which can solve the working frequency change with input voltage in the traditional constant on-time mode control.In order to get high precision timer,the comparator in timer is used the adaptive biasing technology which can dynamic set the bias current of comparator according to the input vohage. on_timer circuit is simulated and verified on the 0.6urn 16V CD process.The results show that the on_timer in this paper can always guarantee the high precision timing.Because input voltage,so a feedforward path is introduced into the system speed. of the timing of time is inversely proportional to the which can greatly improve the system linear response%本文提出一种适用于恒定导通时间控制的开启时间定时器电路。电路中采用与输入电源电压成正比的电流对电容充电，从而实现定时器的定时时间与输入电源电压成反比，解决了传统恒定导通时间控制中系统工作频率随输入电源电压变化的问题。为了获得高的定时精度，开启时间定时器中的比较器采用了自适应偏置技术，根据输入电源电压的情况动态地设置定时器中比较器的偏置电流。基于0．6μmCD工艺，对所设计开启时间定时器电路进行仿真验证。结果表明，本文所设计的开启时间定时器电路，能够始终保证高的定时精度。同时由于定时时间与输入电源电压成反比，在系统中引入了前馈，极大地提高了系统的线性响应速度。
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.
Time-Varying Fundamental Constants
Olive, Keith
2003-04-01
Recent data from quasar absorption systems can be interpreted as arising from a time variation in the fine-structure constant. However, there are numerous cosmological, astro-physical, and terrestrial bounds on any such variation. These includes bounds from Big Bang Nucleosynthesis (from the ^4He abundance), the Oklo reactor (from the resonant neutron capture cross-section of Sm), and from meteoretic lifetimes of heavy radioactive isotopes. The bounds on the variation of the fine-structure constant are significantly strengthened in models where all gauge and Yukawa couplings vary in a dependent manner, as would be expected in unified theories. Models which are consistent with all data are severly challenged when Equivalence Principle constraints are imposed.
Why isn't the solar constant a constant?
Li, K J; Xu, J C; Gao, P X; Yang, L H; Liang, H F; Zhan, L S
2012-01-01
In order to probe the mechanism of variations of the Solar Constant on the inter-solar-cycle scale, total solar irradiance (TSI, the so-called Solar Constant) in the time interval of 7 November 1978 to 20 September 2010 is decomposed into three components through the 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 are inferred to be caused by the network magnetic elements in quiet regions, whose magnetic flux ranges from $(4.27-38.01)\\times10^{19}$ Mx.
Fine-structure constant: Is it really a constant?
Bekenstein, Jacob D.
1982-03-01
It is often claimed that the fine-structure "constant" α is shown to be strictly constant in time by a variety of astronomical and geophysical results. These constrain its fractional rate of change α˙α to at least some orders of magnitude below the Hubble rate H0. We argue that the conclusion is not as straightforward as claimed since there are good physical reasons to expect α˙α<
On the Universality of the Kolmogorov Constant in Numerical Simulations of Turbulence
Yeung, P. K.; Zhou, Ye
1997-01-01
Motivated by a recent survey of experimental data, we examine data on the Kolmogorov spectrum constant in numerical simulations of isotropic turbulence, using results both from previous studies and from new direct numerical simulations over a range of Reynolds numbers (up to 240 on the Taylor scale) at grid resolutions up to 512(exp 3). It is noted that in addition to k(exp -5/3) scaling, identification of a true inertial range requires spectral isotropy in the same wavenumber range. We found that a plateau in the compensated three-dimensional energy spectrum at k(eta) approx. = 0.1 - -0.2, commonly used to infer the Kolmogorov constant from the compensated three-dimensional energy spectrum, actually does not represent proper inertial range behavior. Rather, a proper, if still approximate, inertial range emerges at k(eta) approx. = 0.02 - 0.05 when R(sub lambda) increases beyond 140. The new simulations indicate proportionality constants C(sub 1) and C in the one- and three-dimensional energy spectra respectively about 0.60 and 1.62. If the turbulence were perfectly isotropic then use of isotropy relations in wavenumber space (C(sub 1) = 18/55 C) would imply that C(sub 1) approx. = 0.53 for C = 1.62, in excellent agreement with experiments. However the one- and three-dimensional estimates are not fully consistent, because of departures (due to numerical and statistical limitations) from isotropy of the computed spectra at low wavenumbers. The inertial scaling of structure functions in physical space is briefly addressed. Since DNS is still restricted to moderate Reynolds numbers, an accurate evaluation of the Kolmogorov constant is very difficult. We focus on providing new insights on the interpretation of Kolmogorov 1941 similarity in the DNS literature and do not consider issues pertaining to the refined similarity hypotheses of Kolmogorov (K62).
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.
Chandra Independently Determines Hubble Constant
2006-08-01
A critically important number that specifies the expansion rate of the Universe, the so-called Hubble constant, has been independently determined using NASA's Chandra X-ray Observatory. This new value matches recent measurements using other methods and extends their validity to greater distances, thus allowing astronomers to probe earlier epochs in the evolution of the Universe. "The reason this result is so significant is that we need the Hubble constant to tell us the size of the Universe, its age, and how much matter it contains," said Max Bonamente from the University of Alabama in Huntsville and NASA's Marshall Space Flight Center (MSFC) in Huntsville, Ala., lead author on the paper describing the results. "Astronomers absolutely need to trust this number because we use it for countless calculations." Illustration of Sunyaev-Zeldovich Effect Illustration of Sunyaev-Zeldovich Effect The Hubble constant is calculated by measuring the speed at which objects are moving away from us and dividing by their distance. Most of the previous attempts to determine the Hubble constant have involved using a multi-step, or distance ladder, approach in which the distance to nearby galaxies is used as the basis for determining greater distances. The most common approach has been to use a well-studied type of pulsating star known as a Cepheid variable, in conjunction with more distant supernovae to trace distances across the Universe. Scientists using this method and observations from the Hubble Space Telescope were able to measure the Hubble constant to within 10%. However, only independent checks would give them the confidence they desired, considering that much of our understanding of the Universe hangs in the balance. Chandra X-ray Image of MACS J1149.5+223 Chandra X-ray Image of MACS J1149.5+223 By combining X-ray data from Chandra with radio observations of galaxy clusters, the team determined the distances to 38 galaxy clusters ranging from 1.4 billion to 9.3 billion
Cryptography in constant parallel time
Applebaum, Benny
2013-01-01
Locally computable (NC0) functions are 'simple' functions for which every bit of the output can be computed by reading a small number of bits of their input. The study of locally computable cryptography attempts to construct cryptographic functions that achieve this strong notion of simplicity and simultaneously provide a high level of security. Such constructions are highly parallelizable and they can be realized by Boolean circuits of constant depth.This book establishes, for the first time, the possibility of local implementations for many basic cryptographic primitives such as one-way func
Henry's law constants of polyols
Directory of Open Access Journals (Sweden)
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.
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
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.
Determination of Constitutive Model Constants from Cylinder Impact Tests
1987-12-01
HONEYWELL, INC./ARMAMENT SYSTEMS DIVISION) FOR NAVAL SURFACE WARFARE CENTER RESEARCH AND TECHNOLOGY DEPARTMENT DECEMBER 1988 Approved for public release...primary application is for higher strain rates, and the strain rate constant was therefore selected to give better correlation with the higher strain...to that of the test data. The new constants (C and C2) were obtained in conjunction with the previous values of C. and C4, as talen from Reference 2
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.
Cosmological constant and curved 5D geometry
Ito, M
2002-01-01
We study the value of cosmological constant in de Sitter brane embedded in five dimensions with positive, vanishing and negative bulk cosmological constant. In the case of negative bulk cosmological constant, we show that not zero but tiny four-dimensional cosmological constant can be realized by tiny deviation from bulk curvature of the Randall-Sundrum model.
The fundamental constants a mystery of physics
Fritzsch, Harald
2009-01-01
The speed of light, the fine structure constant, and Newton's constant of gravity — these are just three among the many physical constants that define our picture of the world. Where do they come from? Are they constant in time and across space? In this book, physicist and author Harald Fritzsch invites the reader to explore the mystery of the fundamental constants of physics in the company of Isaac Newton, Albert Einstein, and a modern-day physicist
Coupling constant in dispersive model
Indian Academy of Sciences (India)
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.
Constant Proportion Debt Obligations (CPDOs)
DEFF Research Database (Denmark)
Cont, Rama; Jessen, Cathrine
2012-01-01
be made arbitrarily small—and thus the credit rating arbitrarily high—by increasing leverage, but the ratings obtained strongly depend on assumptions on the credit environment (high spread or low spread). More importantly, CPDO loss distributions are found to exhibit a wide range of tail risk measures......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 major rating agencies, based on complex models for the joint transition of ratings and spreads for all names in the underlying portfolio. We propose a parsimonious model for analysing the performance of CPDO strategies using a top-down approach that captures the essential risk factors of the CPDO. Our...
Henry's law constants of polyols
Directory of Open Access Journals (Sweden)
S. Compernolle
2014-12-01
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. 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.
Omnidirectional antenna having constant phase
Energy Technology Data Exchange (ETDEWEB)
Sena, Matthew
2017-04-04
Various technologies presented herein relate to constructing and/or operating an antenna having an omnidirectional electrical field of constant phase. The antenna comprises an upper plate made up of multiple conductive rings, a lower ground-plane plate, a plurality of grounding posts, a conical feed, and a radio frequency (RF) feed connector. The upper plate has a multi-ring configuration comprising a large outer ring and several smaller rings of equal size located within the outer ring. The large outer ring and the four smaller rings have the same cross-section. The grounding posts ground the upper plate to the lower plate while maintaining a required spacing/parallelism therebetween.
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.
Institute of Scientific and Technical Information of China (English)
杨洪升
2015-01-01
Using frequency control method to enable water pump motor keep the pressure constant in water supply system of high-rise building’s construction, can reach the target that high-rise building's water supply capacity changes with the water flow. By the use of Siemens frequency converter to control the water pump motor, the article introduces the composi⁃tion of variable frequency constant pressure water supply system, the PID regulatory function of Siemens inverter, the set⁃ting method of PID parameters and briefly introduces the control scheme of frequency converter in constant pressure water supply system of high-rise building’s construction . Results show that the constant pressure water supply system con⁃trolled by Siemens inverter in high-rise building’s construction can ensure the of constant pressure water supply, at the same time has achieved remarkable energy saving effect. At present, constant pressure water supply system controlled by the Siemens inverter has been widely used.%采用对水泵电机变频调速的方法，使高层建筑施工供水系统压力恒定，可达到高层建筑供水能力随用水流量而变化的目标。本文通过使用西门子变频器控制水泵电机，介绍了变频恒压供水系统的构成、西门子变频器的PID调节功能、PID参数的设置方法并简要介绍了变频器在高层建筑施工恒压供水系统中的控制方案。结果表明西门子变频器控制的恒压供水系统在实现高层建筑施工恒压供水的同时，达到了显著的节能效果。目前西门子变频器控制的恒压供水系统已经得到了广泛的应用。
Energy Technology Data Exchange (ETDEWEB)
Sajina, Anna [Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Yan Lin [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Fadda, Dario [NASAHerschel Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Dasyra, Kalliopi [Observatoire de Paris, LERMA (CNRS: UMR8112), 61 Av. de l' Observatoire, F-75014, Paris (France); Huynh, Minh [International Center for Radio Astronomy Research, M468, University of Western Australia, Crawley, WA 6009 (Australia)
2012-09-20
In this paper, we characterize the infrared spectral energy distributions (SEDs) of mid-IR-selected z {approx} 0.3-3.0 and L{sub IR} {approx} 10{sup 11}-10{sup 13} L{sub Sun} galaxies, and study how their SEDs differ from those of local and high-z analogs. Infrared SEDs depend both on the power source (AGN or star formation) and the dust distribution. Therefore, differences in the SEDs of high-z and local galaxies provide clues as to differences in their physical conditions. Our mid-IR flux-limited sample of 191 sources is unique in size, and spectral coverage, including Spitzer mid-IR spectroscopy. Here, we add Herschel photometry at 250 {mu}m, 350 {mu}m, and 500 {mu}m, which allows us, through fitting an empirical SED model, to obtain accurate total IR luminosities, as well as constrain the relative contributions of AGNs and starbursts to those luminosities. Our sample includes three broad categories of SEDs: {approx}23% of the sources are AGNs (i.e., where the AGN contributes >50% of L{sub IR}), {approx}30% are starbursts where an AGN contributes <20% of L{sub IR}, and the mid-IR spectra are starburst-like (i.e., strong polycyclic aromatic hydrocarbon features); and the largest group ({approx}47%) are composites which show both significant AGN and starburst activity. The AGN-dominated sources divide into ones that show a strong silicate 9.7 {mu}m absorption feature, implying highly obscured systems, and ones that do not. The high-{tau}{sub 9.7} sources are half of our z > 1.2 AGNs, but show SEDs that are extremely rare among local AGNs. The 30% of the sample that are starbursts, even the z {approx} 2, L{sub IR} {approx} 10{sup 13} L{sub Sun} ones, have lower far-IR to mid-IR continuum ratios than local Ultra Luminous Infrared Galaxies (ULIRGs) or the z {approx} 2 sub-mm galaxies-effectively the SEDs of our z {approx} 2 starburst-dominated ULIRGs are much closer to those of local Luminous Infrared Galaxies than ULIRGs. This is consistent with our earlier finding
Energy Technology Data Exchange (ETDEWEB)
Trump, Jonathan R.; Kocevski, Dale D.; McGrath, Elizabeth J.; Koo, David C.; Faber, S. M.; Mozena, Mark; Yesuf, Hassen [University of California Observatories/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Weiner, Benjamin J. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Scarlata, Claudia [Astronomy Department, University of Minnesota, Minneapolis, MN 55455 (United States); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI 48109 (United States); Laird, Elise S.; Rangel, Cyprian [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Yan Renbin [Department of Physics, Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States); Atek, Hakim [Spitzer Science Center, Caltech, Pasadena, CA 91125 (United States); Dickinson, Mark [National Optical Astronomical Observatories, Tucson, AZ 85719 (United States); Donley, Jennifer L.; Ferguson, Henry C.; Grogin, Norman A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Dunlop, James S. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, EH9 3HJ (United Kingdom); Finkelstein, Steven L. [Department of Physics and Astronomy, Texas A and M University, 4242 TAMU, College Station, TX 77843 (United States); and others
2011-12-20
We present Hubble Space Telescope Wide Field Camera 3 (WFC3) slitless grism spectroscopy of 28 emission-line galaxies at z {approx} 2, in the GOODS-S region of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. The high sensitivity of these grism observations, with >1{sigma} detections of emission lines to f > 2.5 Multiplication-Sign 10{sup -18} erg s{sup -1} cm{sup -2}, means that the galaxies in the sample are typically {approx}7 times less massive (median M{sub *} = 10{sup 9.5} M{sub Sun }) than previously studied z {approx} 2 emission-line galaxies. Despite their lower mass, the galaxies have [O III]/H{beta} ratios which are very similar to previously studied z {approx} 2 galaxies and much higher than the typical emission-line ratios of local galaxies. The WFC3 grism allows for unique studies of spatial gradients in emission lines, and we stack the two-dimensional spectra of the galaxies for this purpose. In the stacked data the [O III] emission line is more spatially concentrated than the H{beta} emission line with 98.1% confidence. We additionally stack the X-ray data (all sources are individually undetected), and find that the average L{sub [OIII]}/L{sub 0.5-10keV} ratio is intermediate between typical z {approx} 0 obscured active galaxies and star-forming galaxies. Together the compactness of the stacked [O III] spatial profile and the stacked X-ray data suggest that at least some of these low-mass, low-metallicity galaxies harbor weak active galactic nuclei.
Bedregal, A. G.; Scarlata, C.; Henry, A. L.; Atek, H.; Rafelski, M.; Teplitz, H. I.; Dominguez, A.; Siana, B.; Colbert, J. W.; Malkan, M.; Ross, N. R.; Martin, C. L.; Dressler, A.; Bridge, C.; Hathi, N. P.; Masters, D.; McCarthy, P. J.; Rutkowski, M. J.
2013-01-01
We combine Hubble Space Telescope (HST) G102 and G141 near-IR (NIR) grism spectroscopy with HST/WFC3- UVIS, HST/WFC3-IR, and Spitzer/IRAC [3.6 microns] photometry to assemble a sample of massive (log(Mstar/M solar mass) at approx 11.0) and quenched (specific star formation rate population properties. We find that their spectral energy distributions (SEDs) are well fitted with exponentially decreasing star formation histories and short star formation timescales (tau less than or equal to 100 M/yr). Quenched galaxies also show a wide distribution in ages, between 1 and 4 G/yr. In the (u - r)0-versus-mass space quenched galaxies have a large spread in rest-frame color at a given mass. Most quenched galaxies populate the zeta appro. 1.5 red sequence (RS), but an important fraction of them (32%) have substantially bluer colors. Although with a large spread, we find that the quenched galaxies on the RS have older median ages (3.1 G/yr) than the quenched galaxies off the RS (1.5 G/yr). We also show that a rejuvenated SED cannot reproduce the observed stacked spectra of (the bluer) quenched galaxies off the RS. We derive the upper limit on the fraction of massive galaxies on the RS at zeta approx 1.5 to be 2 and the zeta approx 1.5 RS. According to their estimated ages, the time required for quenched galaxies off the RS to join their counterparts on the z approx. 1.5 RS is of the order of approx. 1G/yr.
Energy Technology Data Exchange (ETDEWEB)
Cicero, Daniel O.; Barbato, Gaetano; Koch, Uwe; Ingallinella, Paolo; Bianchi, Elisabetta; Sambucini, Sonia; Neddermann, Petra; De Francesco, Raffaele; Pessi, Antonello; Bazzo, Renzo
2001-05-15
A new isotope-filtered experiment has been designed to measure homonuclear three-bond J(H{sup N}H{sup {alpha}}) coupling constants of unlabeled peptides complexed with labeled proteins. The new experiment is based on the 3D HNHA pulse scheme, and belongs to the 'quantitative J-correlation' type. It has been applied to a decapeptide inhibitor bound to the proteinase domain of the NS3 protein of human hepatitis C virus (HCV)
Development of low dielectric constant alumina-based ceramics for microelectronic substrates
Energy Technology Data Exchange (ETDEWEB)
Wu, S. J. [Lawrence Berkeley Lab., CA (United States). Materials Science Div.; California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering
1993-05-01
The performance of high speed computers depends not only on IC chips, but also on the signal propagation speed between these chips. The signal propagation delay in a computer is determined by the dielectric constant of the substrate material to which the IC chips are attached. In this study, a ceramic substrate with a low dielectric constant (k {approx} 5.0) has been developed. When compared with the traditional alumina substrate (k {approx} 10.0), the new material corresponds to a 37% decrease in the signal propagation delay. Glass hollow spheres are used to introduce porosity (k = 1.0) to the alumina matrix in a controlled manner. A surface coating technique via heterogeneous nucleation in aqueous solution has been used to improve the high temperature stability of these spheres. After sintering at 1,400 C, isolated spherical pores are uniformly distributed in the almost fully dense alumina matrix; negligible amounts of matrix defects can be seen. All pores are isolated from each other. Detailed analyses of the chemical composition find that the sintered sample consists of {alpha}-alumina, mullite and residual glass. Mullite is the chemical reaction product of alumina and the glass spheres. Residual glass exists because current firing conditions do not complete the mullitization reaction. The dielectric constant of the sintered sample is measured and then compared with the predicted value using Maxwell`s model. Mechanical strength is evaluated by a four-point bending test. Although the flexural strength decreases exponentially with porosity, samples with 34% porosity (k {approx} 5.0) still maintain adequate mechanical strength for the proper operation of a microelectronic substrate.
A Variant of Davenport's Constant
Indian Academy of Sciences (India)
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.
Institute of Scientific and Technical Information of China (English)
刘善顺
2012-01-01
随着人们对供暖质量和要求的不断提高，利用先进的自动化技术、控制技术以及通讯技术，设计出高性能、高节能、适应供暖复杂环境的恒压补水系统已成为必然趋势。朔里矿业对原工人村区域供热补水系统进行了改造，实现变频恒压自动补水系统，其节能效果显著，稳定性大大提高。本文阐述了供暖热网补水系统改造的背景、工作原理、控制方案、变频恒压补水系统的运行性能，并进行了经济效益分析。%With the increasing demanding on the heating quality, using advanced automation technology, control technology and communication technology, constant pressure water supply system with high performance, high energy-saving and adapting to the complex heating environment was designed, and it become an inevitable trend. Heating water supply system of the former district of workers was transformed by Shuoli Mining, realized variable frequency and constant pressure automatic water supply system, and saved energy observably, stability was greatly improved. The modification background, work theories and control programs of water supply system in heating network, and the operational performance of variable frequency and constant pressure water supply system were advanced in this paper, and economic benefits were analyzed.
Temporal variation of coupling constants and nucleosynthesis
Oberhummer, Heinz; Fairbairn, M; Schlattl, H; Sharma, M M
2003-01-01
We investigate the triple-alpha process and the Oklo phenomenon to obtain constraints on possible cosmological time variations of fundamental constants. Specifically we study cosmological temporal constraints for the fine structure constant and nucleon and meson masses.
Temporal variation of coupling constants and nucleosynthesis
Oberhummer, H.; Csótó, A.; Fairbairn, M.; Schlattl, H.; Sharma, M. M.
2003-05-01
We investigate the triple-alpha process and the Oklo phenomenon to obtain constraints on possible cosmological time variations of fundamental constants. Specifically we study cosmological temporal constraints for the fine structure constant and nucleon and meson masses.
Institute of Scientific and Technical Information of China (English)
郑淑娟
2014-01-01
结合高速铁路电气化施工技术要求，介绍了恒张力放线车结构组成、放线流程、安全保证措施，满足高速铁路电气化施工要求。%Connecting with the technical requirements for high-speed railway’s electrification construction, this paper introduces the structural composition, stringing process and safety-ensuring measures of constant tension wire-barrow for meeting the requirements for high-speed railway’s electrification construction.
Directory of Open Access Journals (Sweden)
Jagannadham Vandanapu
2012-01-01
Full Text Available The emergence of putative Hammett equation in mid 1930s was a boon to physical-organic chemists to elucidate the reaction mechanisms of several organic reactions. Based on the concept of this equation several hundreds of papers have emerged in chemical literature in the last century on the effect of structure, on reactivity, and very few on thermodynamic stability and kinetic reactivity of intermediates. In this article an attempt is made to explain the effect of hetero atom on Hammett’s reaction constant (ρ taking the dissociation equilibriums of benzoic acids, dithiobenzoic acids, phenols, and thiophenols.
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
Untangling Fixed Effects and Constant Regressors
Klaassen, F.; Teulings, R.
2015-01-01
Fixed effects (FE) in panel data models overlap each other and prohibit the identification of the impact of "constant" regressors. Think of regressors that are constant across countries in a country-time panel with time FE. The traditional approach is to drop some FE and constant regressors by norma
Searching for Kaprekar's constants: algorithms and results
Directory of Open Access Journals (Sweden)
Byron L. Walden
2005-01-01
Full Text Available We examine some new results on Kaprekar's constants, specifically establishing the unique 7-digit (in base 4 and 9-digit (in base 5 Kaprekar's constants and showing that there are no 15-, 21-, 27-, or 33-digit Kaprekar's constants.
Energy Technology Data Exchange (ETDEWEB)
Lacy, M. [North American ALMA Science Center, National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Petric, A. O. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Martinez-Sansigre, A. [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth, PO1 3FX (United Kingdom); Ridgway, S. E. [NOAO, Colina El Pino s/n, Casilla 603, La Serena (Chile); Sajina, A. [Tuffs University, Medford, MA 02155 (United States); Urrutia, T. [Spitzer Science Center, Caltech, Mail Code 220-6, Pasadena, CA 91125 (United States); Farrah, D. [Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9RH (United Kingdom)
2011-12-15
We present optical through radio observations of the host galaxies of two dust-obscured, luminous quasars selected in the mid-infrared, at z = 2.62 and z = 2.99, including a search for CO emission. Our limits on the CO luminosities are consistent with these objects having masses of molecular gas {approx}< 10{sup 10} M{sub Sun }, several times less than those of luminous submillimeter-detected galaxies at comparable redshifts. Their near-infrared spectral energy distributions, however, imply that these galaxies have high stellar masses ({approx}10{sup 11}-10{sup 12} M{sub Sun }). The relatively small reservoirs of molecular gas and low dust masses are consistent with them being relatively mature systems at high-z.
Institute of Scientific and Technical Information of China (English)
卢祥江; 武宇龙
2014-01-01
In view of the problems of instability, excessive energy consumption and long time lag of current variable frequency constant pressure water supply, the model free control method was applied to the constant pressure water supply system, and on the basis of research of water supply characteristics, the specific water supply equipment was analyzed and improved. The practice showed that the improved water supply system realized stable pressure water supply, obvious effect of energy-saving, fast response speed and long-term stable and reliable operation.%针对当前变频恒压供水压力不稳定、能耗过大、滞后时间过长等问题，将无模型控制方式运用到恒压变频供水系统中，同时在分析供水特性的基础上，对具体的供水设备进行分析和改进。实践表明，改进之后的供水系统实现了供水压力稳定，节能效果明显，反应执行速度快捷，长期运行稳定可靠。
Stefańska, Patrycja
2011-01-01
The Sturmian expansion of the generalized Dirac-Coulomb Green function [R. Szmytkowski, J. Phys. B 30 (1997) 825; erratum 30 (1997) 2747] is exploited to derive closed-form expressions for electric ($\\sigma_{\\mathrm{E}}$) and magnetic ($\\sigma_{\\mathrm{M}}$) dipole shielding constants for the ground state of the relativistic hydrogen-like atom with a point-like and spinless nucleus of charge $Ze$. It is found that $\\sigma_{\\mathrm{E}}=Z^{-1}$ (as it should be) and $$\\sigma_{\\mathrm{M}}=-(2Z\\alpha^{2}/27)(4\\gamma_{1}^{3}+6\\gamma_{1}^{2}-7\\gamma_{1}-12) /[\\gamma_{1}(\\gamma_{1}+1)(2\\gamma_{1}-1)],$$ where $\\gamma_{1}=\\sqrt{1-(Z\\alpha)^{2}}$ ($\\alpha$ is the fine-structure constant). This expression for $\\sigma_{\\mathrm{M}}$ agrees with earlier findings of several other authors, obtained with the use of other analytical techniques, and is elementary compared to an alternative one presented recently by Cheng \\emph{et al.} [J. Chem. Phys. 130 (2009) 144102], which involves an infinite series of ratios of the Euler'...
Institute of Scientific and Technical Information of China (English)
连黎明; 唐军
2014-01-01
通过对数控转台SKZT3500用恒流静压轴承进行特性分析，借助软件MATLAB7．1中神经网络工具箱，将RBF神经网络的理论和算法应用到恒流静压轴承静刚度预测中。经过对物理样机进行相关试验，把测量获得的样本数据用于对RBF神经网络进行训练和测试。结果表明，RBF神经网络能够较准确地预测恒流静压轴承的静刚度。%Through analysis of the characteristics of constant -current hydrostatic bearings for NC rotary table SKZT3500,the theory and arithmetic for the RBF neural network are applied to predict the static stiffness for the bear-ings by using neural network toolbox in MATLAB 7.1.The measured sample data is used to train and test the RBF neural network through experiment of physical prototype.The results show that the RBF neural network can accurately forecast the static stiffness of constant-current hydrostatic bearings.
Helgason, K.; Cappelluti, N.; Hasinger, G.; Kashlinsky, A.; Ricotti, M.
2014-01-01
A spatial clustering signal has been established in Spitzer/IRAC measurements of the unresolved cosmic near-infrared background (CIB) out to large angular scales, approx. 1deg. This CIB signal, while significantly exceeding the contribution from the remaining known galaxies, was further found to be coherent at a highly statistically significant level with the unresolved soft cosmic X-ray background (CXB). This measurement probes the unresolved CXB to very faint source levels using deep near-IR source subtraction.We study contributions from extragalactic populations at low to intermediate redshifts to the measured positive cross-power signal of the CIB fluctuations with the CXB. We model the X-ray emission from active galactic nuclei (AGNs), normal galaxies, and hot gas residing in virialized structures, calculating their CXB contribution including their spatial coherence with all infrared emitting counterparts. We use a halo model framework to calculate the auto and cross-power spectra of the unresolved fluctuations based on the latest constraints of the halo occupation distribution and the biasing of AGNs, galaxies, and diffuse emission. At small angular scales (1), the 4.5microns versus 0.5-2 keV coherence can be explained by shot noise from galaxies and AGNs. However, at large angular scales (approx.10), we find that the net contribution from the modeled populations is only able to account for approx. 3% of the measured CIB×CXB cross-power. The discrepancy suggests that the CIB×CXB signal originates from the same unknown source population producing the CIB clustering signal out to approx. 1deg.
Stopping of {approx}0.2-3.4 MeV/amu {sup 1}H{sup +} and {sup 4}He{sup +} ions in polyvinyl formal
Energy Technology Data Exchange (ETDEWEB)
Damache, S., E-mail: sdamache@gmail.co [Division de Physique, CRNA, 02 Bd. Frantz Fanon, B.P. 399 Alger-gare, Algiers (Algeria); Moussa, D. [USTHB, Faculte de Physique, B.P. 32, 16111 Bab-Ezzouar, Algiers (Algeria); Ouichaoui, S., E-mail: souichaoui@gmail.co [USTHB, Faculte de Physique, B.P. 32, 16111 Bab-Ezzouar, Algiers (Algeria)
2010-06-15
The stopping powers of polyvinyl formal resin for protons and alpha particles have been measured over the energy range {approx}(0.2-3.4) MeV/amu with an overall relative uncertainty of less than 2.5% using the ion beam transmission method. The obtained results are discussed in comparison to scarce experimental data from the literature and to values calculated by the SRIM-2008 computer code assuming Bragg-Kleeman's additivity rule of stopping powers. Departures from additivity attaining {approx}5.5% and {approx}3.0% for the proton and alpha particle data, respectively, are observed at moderate projectile velocities, increasingly as one evolves towards the stopping power maximum dominated by charge exchange effects. They are presumed to be mainly due to valence structure effects involving the C-H bonds of the studied polymer compound. The less pronounced deviation for alpha particles is probably due to the projectile screening effect that occurs in distant collisions tending to reduce the contribution of valence electrons in the low projectile velocity regime.
Institute of Scientific and Technical Information of China (English)
李徐; 刘睿杰; 金青哲; 王兴国
2014-01-01
There is a high correlation between dielectric constant and deterioration of frying oils and thus the dielectric constant can be used to measure the quality changes of frying oils, which has the advantages such as fast detection, easy operation and food grade safety. The review described test principle of dielectric property on liquid and dielectric property of frying oils including correlation fitting model between TPC and dielectric constant. Three rapid test kits:FOS, FOM 310 and Testo 270 were evaluated with their structure, operation and data reliability. Then the main factors affecting the accuracy of detection were analyzed to be oil variety, cali-bration, suspended solids and operation. Finally, two future trends in this technology including specific optimi-zation for signal parameters and combination with data processing technique or infrared testing technique were prospected.%介电常数与煎炸油中极性组分含量有较好相关性，用于评价煎炸油品质，具有快速、便捷、安全等优点。本文分析了液体介电特性的测试原理和煎炸油介电特性机制，列出极性组分和介电常数的相关性拟合模型。以商业化应用广泛的FOS、FOM 310、Testo 270三类快速检测仪器为对象，对其内部构造、仪器操作和数据可靠性进行评价，结合餐饮业实践经验总结了影响其检测准确度的主要因素，包括煎炸油品种、校准体系、悬浮物、操作规范性。最后，提出此快速检测技术未来的两大发展方向：对信号处理参数的特异性优化和对数据处理技术或红外在线检测技术的引入结合。
Smart magnetodielectric nano-materials for the very high frequency applications
Energy Technology Data Exchange (ETDEWEB)
Thakur, Atul [Department of Physics, National Taiwan University, 1 Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China); Thakur, Preeti [Physics Department, Himachal Pradesh University, Shimla 171005 (India); Hsu, Jen-Hwa, E-mail: jhhsu@phys.ntu.edu.tw [Department of Physics, National Taiwan University, 1 Roosevelt Road, Sec. 4, Taipei 106, Taiwan (China)
2011-04-28
Research highlights: > Ni{sub 0.4}Zn{sub 0.4}Co{sub 0.2}Cu{sub 0.02}Fe{sub 1.98}O{sub 4} nano-ferrite is prepared by a co-precipitation method. > The average crystalline size of the nano-ferrite is 38 nm. > The material shows almost constant {mu} and {epsilon} in the frequency range from 10 to 200 MHz. > Relaxation phenomenon takes place above 200 MHz. > Useful as a substrate for loading the patch antenna than pure dielectric substrates. - Abstract: Cobalt and copper doped Ni-Zn nano-ferrite with a composition of Ni{sub 0.4}Zn{sub 0.4}Co{sub 0.2}Cu{sub 0.02}Fe{sub 1.98}O{sub 4} are prepared by a coprecipitation method. The structural, electromagnetic and magnetic properties are investigated by means of X-ray diffraction, impedance analyzer and vibrating sample magnetometer, respectively. Samples are calcinated at 600 deg. C and then subjected to different sintering temperatures. After sintering at 900 deg. C for 5 h, the average crystalline size is found to be 38 nm. The material shows almost constant permeability and permittivity, in the frequency range from 10 to 200 MHz, equal to {approx}10.8 (loss tangent {approx} 0.04) and {approx}6.5 (loss tangent {approx} 0.006), respectively. Relaxation phenomenon takes place beyond 200 MHz. The refractive index n is close to 8.3, and the reduced impedance Z/Z{sub 0} is close to 1.3. The persistent and higher value of permeability than that of permittivity along with low losses enables this material useful for the very high frequency applications.
Dielectric constant of /sup 3/He near the liquid-vapor critical point
Energy Technology Data Exchange (ETDEWEB)
Doiron, T.; Meyer, H.
1978-03-01
High-resolution measurements of the static dielectic constant epsilon along the critical isochore are reported for /sup 3/He in the region of the critical point. The experiments were conducted at a frequency of 1000 Hz and the purpose was to observe a divergence of (partialepsilon/partialT)/sub rhoc/ as T/sub c/ is approached from above. No evidence for a critical anomaly was found, the estimated upper bound for its integrated value being deltaepsilon approx. 4 x 10/sup -8/ which is consistent with the theoretical estimations. Hence the recently reported is not observed in /sup 3/He. In the Appendix, some experimental questions arising in such constant-density experiments are discussed.
Institute of Scientific and Technical Information of China (English)
何武全; 张华; 何欣烨; 张宇峰
2016-01-01
为解决机电泵利用工频电源（50 Hz）作恒速运转条件下，灌溉面积或地形高差变化较大的管道式喷微灌系统灌水均匀度不能满足灌溉要求的问题，提出了一种变频调速分级恒压灌溉自动控制系统，该系统将变频技术和自动化技术相结合，具有变频调速和全自动闭环控制功能的机电一体化智能设备，可同时对1台或多台三相380 V，50 Hz 水泵电动机进行自动控制．该系统设计了多段压力设置转换电路，可根据预先设定的压力控制值自动进行压力等级切换，并对管网的电磁阀开启、关闭进行控制，实现分级恒压自动供水灌溉．通过工程实例分析表明，采用水泵工频控制时喷灌系统水头最大差值为12.89 m，采用变频分级恒压控制时喷灌系统水头最大差值为3.38 m，满足设计压力变幅不大于4.00 m 的要求．同时该系统具有节水、节能、自动化程度高、运行管理方便以及保证管网和水泵安全运行等功能，能够根据灌溉分区进行分级恒压自动供水灌溉，满足灌水均匀度要求．%In a sprinkler irrigation system with long pipe,there is a constant frequency (50 Hz)motor to derive the pump for delivering water.If the irrigating area or elevation change greatly in an irrigation field,the sprinkler irrigation uniformity will become unsatisfactory.In order to solve this problem,a variable frequency and adjustable constant pressure automatic control irrigation system is proposed.In the system,frequency conversion and automation technique are combined,and it is a kind of mecha-tronic-intelligent device with variable frequency motor and closed-loop fully automatic control function, and it can control for one or more AC 380 V,50 Hz pump motors automatically at the same time.An electrical circuit is designed for setting different constant pressure levels.As a result,the system can vary the pressure in a pipe network automatically
Statistical Modelling of the Soil Dielectric Constant
Usowicz, Boguslaw; Marczewski, Wojciech; Bogdan Usowicz, Jerzy; Lipiec, Jerzy
2010-05-01
the soil type, and that way it enables clear comparing to results from other soil type dependent models. The paper is focused on proper representing possible range of porosity in commonly existing soils. This work is done with aim of implementing the statistical-physical model of the dielectric constant to a use in the model CMEM (Community Microwave Emission Model), applicable to SMOS (Soil Moisture and Ocean Salinity ESA Mission) data. The input data to the model clearly accepts definition of soil fractions in common physical measures, and in opposition to other empirical models, does not need calibrating. It is not dependent on recognition of the soil by type, but instead it offers the control of accuracy by proper determination of the soil compound fractions. SMOS employs CMEM being funded only by the sand-clay-silt composition. Common use of the soil data, is split on tens or even hundreds soil types depending on the region. We hope that only by determining three element compounds of sand-clay-silt, in few fractions may help resolving the question of relevance of soil data to the input of CMEM, for SMOS. Now, traditionally employed soil types are converted on sand-clay-silt compounds, but hardly cover effects of other specific properties like the porosity. It should bring advantageous effects in validating SMOS observation data, and is taken for the aim in the Cal/Val project 3275, in the campaigns for SVRT (SMOS Validation and Retrieval Team). Acknowledgements. This work was funded in part by the PECS - Programme for European Cooperating States, No. 98084 "SWEX/R - Soil Water and Energy Exchange/Research".
Third order elastic constants of bcc Cu-Al-Ni
Gonzàlez Comas, Alfons; Mañosa, Lluís
1996-01-01
We have measured the changes in the ultrasonic wave velocity, induced by the application of uniaxial stresses in a Cu-Al-Ni single crystal. From these measurements, the complete set of third-order elastic constants has been obtained. The comparison of results for Cu-Al-Ni with available data for other Cu-based alloys has shown that all these alloys exhibit similar anharmonic behavior. By using the measured elastic constants in a Landau expansion for elastic phase transitions, we have been abl...
A first-principles approach to finite temperature elastic constants
Energy Technology Data Exchange (ETDEWEB)
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.
AB INITIO CALCULATIONS OF ELASTIC CONSTANTS OF BCC V-NB SYSTEM AT HIGH PRESSURES
Energy Technology Data Exchange (ETDEWEB)
Landa, A; Klepeis, J; Soderlind, P; Naumov, I; Velikokhatnyi, O; Vitos, L; Ruban, A
2005-05-02
First-principles total energy calculation based on the exact muffin-tin orbital and full potential linear muffin-tin orbital methods were used to calculate the equation of state and shear elastic constants of bcc V, Nb, and the V{sub 95}Nb{sub 05} disordered alloy as a function of pressure up to 6 Mbar. We found a mechanical instability in C{sub 44} and a corresponding softening in C at pressures {approx} 2 Mbar for V. Both shear elastic constants show softening at pressures {approx} 0.5 Mbar for Nb. Substitution of 5 at. % of V with Nb removes the instability of V with respect to trigonal distortions in the vicinity of 2 Mbar pressure, but still leaves the softening of C{sub 44} in this pressure region. We argue that the pressure induced shear instability (softening) of V (Nb) originates from the electronic system and can be explained by a combination of the Fermi surface nesting, electronic topological transition, and band Jahn-Teller effect.
The cosmological constant: Plus CA change, plus C`est La Meme Chose
Energy Technology Data Exchange (ETDEWEB)
Frieman, J.A.
1998-02-01
Recent measurements of the cosmological parameters have renewed interest in the cosmological constant {Lambda}. I briefly review the current status of these measurements and the corresponding arguments for and against cosmological models with non-zero {Lambda}. I outline a scenario which attempts to incorporate non-zero vacuum energy into the framework of particle physics, based on an ultra-light pseudo-Nambu-Goldstone boson. With global spontaneous symmetry breaking scale f {approx_equal} 10{sup 18} GeV and explicit breaking scale comparable to MSW neutrino masses, M {approximately} 10{sup -3} eV, such a field, which acquires a mass M{sub {phi}} {approximately} M{sup 2}/f {approximately} H{sub 0}, would have become dynamical at recent epochs and currently dominate the energy density of the universe. The field acts as an effective cosmological constant for several expansion times and then relaxes into a condensate of coherent non-relativistic bosons. Such a model can reconcile dynamical estimates of the density parameter, {Omega}{sub m} {approximately} 0.2, with a spatially flat universe, and can yield an expansion age H{sub 0}t{sub 0} {approx_equal} 1 while remaining consistent with limits from gravitational lens statistics.
On a time varying fine structure constant
Berman, M S; Berman, Marcelo S.; Trevisan, Luis A.
2001-01-01
By employing Dirac LNH, and a further generalization by Berman (GLNH), we estimate how should vary the total number of nucleons, the energy density, Newton Gravitational constant, the cosmological constant, the magnetic permeability and electric permitivity, of the Universe,in order to account for the experimentally observed time variation of the fine structure constant. As a bonus,we find an acceptable value for the deceleration parameter of the present Universe, compatible with the Supernovae observations.
Singularities in universes with negative cosmological constant
Energy Technology Data Exchange (ETDEWEB)
Tipler, F.J.
1976-10-01
It is well known that many universes with negative cosmological constant contain singularities. We shall generalize this result by proving that all closed universes with negative cosmological constant are both future and past timelike geodesically incomplete if the strong energy condition holds. No global causality conditions or restrictions on the initial data are used in the proof. Furthermore, we shall show that all open universes with a Cauchy surface and a negative cosmological constant are singular if the strong energy condition holds. (AIP)
Coasting cosmologies with time dependent cosmological constant
Pimentel, L O; Pimentel, Luis O.
1999-01-01
The effect of a time dependent cosmological constant is considered in a family of scalar tensor theories. Friedmann-Robertson-Walker cosmological models for vacumm and perfect fluid matter are found. They have a linear expansion factor, the so called coasting cosmology, the gravitational "constant" decreace inversely with time; this model satisfy the Dirac hipotesis. The cosmological "constant" decreace inversely with the square of time, therefore we can have a very small value for it at present time.
Institute of Scientific and Technical Information of China (English)
尹业宏; 高黎明
2012-01-01
随着高性能CCD传感器的发展，其在空间成像探测系统得到广泛应用。为解决传感器的成像质量和恒温控制问题，采用基于帕尔贴效应的热电制冷（Thermo—ElectricCooling，TEC）技术，以FPGA为控制芯片，运用PID控制算法，实现了小型温度控制系统。实验结果表明，该系统能快速准确地实现恒温控制，可扩展性强，具有一定的应用价值。%With the development of high performance cooling CCD imaging system in aerospace imaging detection, in order to improve sensor＇s imaging performance and keep sensor＇s temperature constant, a precision temperature control system is designed by using FPGA as digital control processor and a method of PID control and Thermo-Electric Cooling（TEC） technolo- gy, based on Peltier effect. The experiment results show that the system can work fast and accurately and can be well expanded. It has the good practicability.
Tenti, Lorenzo; Maynau, Daniel; Angeli, Celestino; Calzado, Carmen J
2016-07-21
A new strategy based on orthogonal valence-bond analysis of the wave function combined with intermediate Hamiltonian theory has been applied to the evaluation of the magnetic coupling constants in two AF systems. This approach provides both a quantitative estimate of the J value and a detailed analysis of the main physical mechanisms controlling the coupling, using a combined perturbative + variational scheme. The procedure requires a selection of the dominant excitations to be treated variationally. Two methods have been employed: a brute-force selection, using a logic similar to that of the CIPSI approach, or entanglement measures, which identify the most interacting orbitals in the system. Once a reduced set of excitations (about 300 determinants) is established, the interaction matrix is dressed at the second-order of perturbation by the remaining excitations of the CI space. The diagonalization of the dressed matrix provides J values in good agreement with experimental ones, at a very low-cost. This approach demonstrates the key role of d → d* excitations in the quantitative description of the magnetic coupling, as well as the importance of using an extended active space, including the bridging ligand orbitals, for the binuclear model of the intermediates of multicopper oxidases. The method is a promising tool for dealing with complex systems containing several active centers, as an alternative to both pure variational and DFT approaches.
Institute of Scientific and Technical Information of China (English)
张晓毅
2011-01-01
Mechanical calculation combined with finite element analysis is used in amended calculation for the constant current closed hydrostatic guideway. Through this calculation, the deformation in the oil reservoir of hydrostatic guideway was gotten. Based on the equilibrium equation of correction system, technics parameters were modified so as to minimize the impact of rigid deformation that caused by the guideway's basic element in reduced load condition on the hydrostatic parameters. Practice proves that the accuracy of design can be improved by amended calculation.%恒流闭式静压导轨修正计算法是采用力学计算和有限元分析相结合的方式,得到静压导轨油腔处的变形,在修正系统平衡方程的基础上,修改工艺参数,减小导轨基础件在负载条件下的刚性变形对静压导轨参数的影响.实践证明,修正计算法能提高设计的精度.
Accurate lineshape spectroscopy and the Boltzmann constant.
Truong, G-W; Anstie, J D; May, E F; Stace, T M; Luiten, A N
2015-10-14
Spectroscopy has an illustrious history delivering serendipitous discoveries and providing a stringent testbed for new physical predictions, including applications from trace materials detection, to understanding the atmospheres of stars and planets, and even constraining cosmological models. Reaching fundamental-noise limits permits optimal extraction of spectroscopic information from an absorption measurement. Here, we demonstrate a quantum-limited spectrometer that delivers high-precision measurements of the absorption lineshape. These measurements yield a very accurate measurement of the excited-state (6P1/2) hyperfine splitting in Cs, and reveals a breakdown in the well-known Voigt spectral profile. We develop a theoretical model that accounts for this breakdown, explaining the observations to within the shot-noise limit. Our model enables us to infer the thermal velocity dispersion of the Cs vapour with an uncertainty of 35 p.p.m. within an hour. This allows us to determine a value for Boltzmann's constant with a precision of 6 p.p.m., and an uncertainty of 71 p.p.m.
Optical Constants of Cadmium Telluride Thin Film
Nithyakalyani, P.; Pandiaraman, M.; Pannir, P.; Sanjeeviraja, C.; Soundararajan, N.
2008-04-01
Cadmium Telluride (CdTe) is II-VI direct band gap semiconductor compound with potential application in Solar Energy conversion process. CdTe thin film of thickness 220 mn was prepared by thermal evaporation technique at a high vacuum better than 10-5 m.bar on well cleaned glass substrates of dimensions (l cm×3 cm). The transmittance spectrum and the reflectance spectrum of the prepared CdTc thin film was recorded using UV-Vis Spectrophotometer in the wavelength range between 300 nm and 900 nm. These spectral data were analyzed and the optical band and optical constants of CdTe Thin film have been determined by adopting suitable relations. The optical band gap of CdTe thin film is found to be 1.56 eV and this value is also agreeing with the published works of CdTe thin film prepared by various techniques. The absorption coefficient (α) has been higher than 106 cm-1. The Refractive index (n) and the Extinction Coefficient (k) are found to be varying from 3.0 to 4.0 and 0.1 Cm-1 to 0.5 Cm-1 respectively by varying the energy from l.0 eV to 4.0 eV. These results are also compared with the literature.
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.
A natural cosmological constant from chameleons
Energy Technology Data Exchange (ETDEWEB)
Nastase, Horatiu, E-mail: nastase@ift.unesp.br [Instituto de Física Teórica, UNESP-Universidade Estadual Paulista, R. Dr. Bento T. Ferraz 271, Bl. II, Sao Paulo 01140-070, SP (Brazil); Weltman, Amanda, E-mail: amanda.weltman@uct.ac.za [Astrophysics, Cosmology & Gravity Center, Department of Mathematics and Applied Mathematics, University of Cape Town, Private Bag, Rondebosch 7700 (South Africa)
2015-07-30
We present a simple model where the effective cosmological constant appears from chameleon scalar fields. For a Kachru–Kallosh–Linde–Trivedi (KKLT)-inspired form of the potential and a particular chameleon coupling to the local density, patches of approximately constant scalar field potential cluster around regions of matter with density above a certain value, generating the effect of a cosmological constant on large scales. This construction addresses both the cosmological constant problem (why Λ is so small, yet nonzero) and the coincidence problem (why Λ is comparable to the matter density now)
A natural cosmological constant from chameleons
Directory of Open Access Journals (Sweden)
Horatiu Nastase
2015-07-01
Full Text Available We present a simple model where the effective cosmological constant appears from chameleon scalar fields. For a Kachru–Kallosh–Linde–Trivedi (KKLT-inspired form of the potential and a particular chameleon coupling to the local density, patches of approximately constant scalar field potential cluster around regions of matter with density above a certain value, generating the effect of a cosmological constant on large scales. This construction addresses both the cosmological constant problem (why Λ is so small, yet nonzero and the coincidence problem (why Λ is comparable to the matter density now.
TARGET DETECTION USING MULTI-RESOLUTION ANALYSIS AND HOLDER CONSTANT
Institute of Scientific and Technical Information of China (English)
Liu Wenyu; Li Hua; Zhu Guangxi
2001-01-01
Through analyzing the different height parameter of 3D surface between the artificial target and complex background based on the description of average Holder constant of fractional Brownian motion, a novel method of target detection based on wavelet transformation and Holder constant is proposed. The wavelet Holder constants are calculated and linearly interpolated in a series of images, the target is detected by testing the linearity errof The more accurate localization can be achieved using two images of the same region but with difIerent scaling parameters.The application results of this algorithm for target detection are also given, and show that this method has good performance of noise immunity. This method is also suitable for identifying specific targets in complex background.
Regular Black Hole Metric with Three Constants of Motion
Johannsen, Tim
2015-01-01
According to the no-hair theorem, astrophysical black holes are uniquely characterized by their masses and spins and are described by the Kerr metric. Several parametric spacetimes which deviate from the Kerr metric have been proposed in order to test this theorem with observations of black holes in both the electromagnetic and gravitational-wave spectra. Such metrics often contain naked singularities or closed timelike curves in the vicinity of the compact objects that can limit the applicability of the metrics to compact objects that do not spin rapidly, and generally admit only two constants of motion. The existence of a third constant, however, can facilitate the calculation of observables, because the equations of motion can be written in first-order form. In this paper, I design a Kerr-like black hole metric which is regular everywhere outside of the event horizon, possesses three independent constants of motion, and depends nonlinearly on four free functions that parameterize potential deviations from ...
Energy Technology Data Exchange (ETDEWEB)
Lin Lihwai; Wang Weihao; Yan, Chi-Hung [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 106, Taiwan (China); Dickinson, Mark [National Optical Astronomy Observatory, 950 N. Cherry Ave., Tucson, AZ 85719 (United States); Jian, Hung-Yu [Department of Physics, National Taiwan University, Taipei, Taiwan (China); Merson, A. I.; Baugh, C. M.; Helly, John; Lagos, Claudia del P [Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Scott, Douglas; Meger, Nicole [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Foucaud, Sebastien [Department of Earth Sciences, National Taiwan Normal University, N Degree-Sign 88, Tingzhou Road, Sec. 4, Taipei 11677, Taiwan (China); Yan Haojing [Center for Cosmology and AstroParticle Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210 (United States); Cheng, Yi-Wen [Institute of Astronomy, National Central Universe, Jhongli, Taiwan (China); Guo Yicheng; Pope, Alexandra [Astronomy Department, University of Massachusetts, 710 N. Pleasant St., Amherst, MA 01003 (United States); Kirsten, Franz [Argelander-Institut fuer Astronomie, University of Bonn (Germany); Koo, David C. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Messias, Hugo [Centro de Astronomia e Astrofisica da Universidade de Lisboa, Observatorio Astronomico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa (Portugal); Simard, Luc, E-mail: lihwailin@asiaa.sinica.edu.tw [National Research Council of Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia (Canada); and others
2012-09-01
Using a sample of BzK-selected galaxies at z {approx} 2 identified from the CFHT/WIRCAM near-infrared survey of GOODS-North, we discuss the relation between star formation rate (SFR), specific star formation rate (SSFR), and stellar mass (M{sub *}), and the clustering of galaxies as a function of these parameters. For star-forming galaxies (sBzKs), the UV-based SFR, corrected for extinction, scales with the stellar mass as SFR{proportional_to}M{sup {alpha}}{sub *} with {alpha} = 0.74 {+-} 0.20 down to M{sub *} {approx} 10{sup 9} M{sub Sun }, indicating a weak dependence on the stellar mass of the SFR efficiency, namely, SSFR. We also measure the angular correlation function and hence infer the correlation length for sBzK galaxies as a function of M{sub *}, SFR, and SSFR, as well as K-band apparent magnitude. We show that passive galaxies (pBzKs) are more strongly clustered than sBzK galaxies at a given stellar mass, mirroring the color-density relation seen at lower redshifts. We also find that the correlation length of sBzK galaxies ranges from 4 to 20 h {sup -1} Mpc, being a strong function of M{sub K} , M{sub *}, and SFR. On the other hand, the clustering dependence on SSFR changes abruptly at 2 Multiplication-Sign 10{sup -9} yr{sup -1}, which is the typical value for 'main-sequence' star-forming galaxies at z {approx} 2. We show that the correlation length reaches a minimum at this characteristic value, and is larger for galaxies with both smaller and larger SSFRs; a dichotomy that is only marginally implied from the predictions of the semi-analytical models. Our results suggest that there are two types of environmental effects at work at z {approx} 2. Stronger clustering for relatively quiescent galaxies implies that the environment has started to play a role in quenching star formation. At the same time, stronger clustering for galaxies with elevated SSFRs ({sup s}tarbursts{sup )} might be attributed to an increased efficiency for galaxy
Energy Technology Data Exchange (ETDEWEB)
Sand, David J.; Graham, Melissa L. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Bildfell, Chris; Pritchet, Chris [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, STN CSC, Victoria BC V8W 3P6 (Canada); Zaritsky, Dennis; Just, Dennis W.; Herbert-Fort, Stephane [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Hoekstra, Henk [Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333 CA Leiden (Netherlands); Sivanandam, Suresh [Dunlap Institute for Astronomy and Astrophysics, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Mahdavi, Andisheh, E-mail: dsand@lcogt.net [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States)
2012-02-20
We describe the Multi-Epoch Nearby Cluster Survey, designed to measure the cluster Type Ia supernova (SN Ia) rate in a sample of 57 X-ray selected galaxy clusters, with redshifts of 0.05 < z < 0.15. Utilizing our real-time analysis pipeline, we spectroscopically confirmed twenty-three cluster SNe Ia, four of which were intracluster events. Using our deep Canada-France-Hawaii Telescope/MegaCam imaging, we measured total stellar luminosities in each of our galaxy clusters, and we performed detailed supernova (SN) detection efficiency simulations. Bringing these ingredients together, we measure an overall cluster SN Ia rate within R{sub 200} (1 Mpc) of 0.042{sup +0.012}{sub -0.010}{sup +0.010}{sub -0.008} SNuM (0.049{sup +0.016}{sub -0.014}{sup +0.005}{sub -0.004} SNuM) and an SN Ia rate within red-sequence galaxies of 0.041{sup +0.015}{sub -0.015}{sup +0.005}{sub -0.010} SNuM (0.041{sup +0.019}{sub -0.015}{sup +0.005}{sub -0.004} SNuM). The red-sequence SN Ia rate is consistent with published rates in early-type/elliptical galaxies in the 'field'. Using our red-sequence SN Ia rate, and other cluster SN measurements in early-type galaxies up to z {approx} 1, we derive the late-time (>2 Gyr) delay time distribution (DTD) of SN Ia assuming a cluster early-type galaxy star formation epoch of z{sub f} = 3. Assuming a power-law form for the DTD, {Psi}(t){proportional_to}t{sup s} , we find s = -1.62 {+-} 0.54. This result is consistent with predictions for the double degenerate SN Ia progenitor scenario (s {approx} -1) and is also in line with recent calculations for the double detonation explosion mechanism (s {approx} -2). The most recent calculations of the single degenerate scenario DTD predicts an order-of-magnitude drop-off in SN Ia rate {approx}6-7 Gyr after stellar formation, and the observed cluster rates cannot rule this out.
Constant Angle Surfaces in the Heisenberg Group
Institute of Scientific and Technical Information of China (English)
Johan FASTENAKELS; Marian Ioan MUNTEANU; Joeri VAN DER VEKEN
2011-01-01
In this article we extend the notion of constant angle surfaces in S2 × R and H2 × R to general Bianchi-Cartan-Vranceanu spaces. We show that these surfaces have constant Gaussian curvature and we give a complete local classification in the Heisenberg group.
Physical Properties of Triglycerides IV. Dielectric Constant
Gouw, T.H.; Vlugter, J.C.
1967-01-01
Dielectric constants at 20° and at 40° C of a number of triglycerides in the liquid state have been measured. A molar additive function of the dielectric constant, based on a relation derived by J. van Elk, was used in combination with a previously derived equation for triglycerides to give an equat
The time constant of the somatogravic illusion.
Correia Grácio, B J; de Winkel, K N; Groen, E L; Wentink, M; Bos, J E
2013-02-01
Without visual feedback, humans perceive tilt when experiencing a sustained linear acceleration. This tilt illusion is commonly referred to as the somatogravic illusion. Although the physiological basis of the illusion seems to be well understood, the dynamic behavior is still subject to discussion. In this study, the dynamic behavior of the illusion was measured experimentally for three motion profiles with different frequency content. Subjects were exposed to pure centripetal accelerations in the lateral direction and were asked to indicate their tilt percept by means of a joystick. Variable-radius centrifugation during constant angular rotation was used to generate these motion profiles. Two self-motion perception models were fitted to the experimental data and were used to obtain the time constant of the somatogravic illusion. Results showed that the time constant of the somatogravic illusion was on the order of two seconds, in contrast to the higher time constant found in fixed-radius centrifugation studies. Furthermore, the time constant was significantly affected by the frequency content of the motion profiles. Motion profiles with higher frequency content revealed shorter time constants which cannot be explained by self-motion perception models that assume a fixed time constant. Therefore, these models need to be improved with a mechanism that deals with this variable time constant. Apart from the fundamental importance, these results also have practical consequences for the simulation of sustained accelerations in motion simulators.
Chiral Corrections to Vector Meson Decay Constants
Bijnens, J; Talavera, P; Bijnens, Johan; Gosdzinsky, Peter; Talavera, Pere
1998-01-01
We calculate the leading quark mass corrections of order $m_q\\log(m_q)$, $m_q$ and $m_q^{3/2}$ to the vector meson decay constants within Heavy Vector Meson Chiral Perturbation Theory. We discuss the issue of electromagnetic gauge invariance and the heavy mass expansion. Reasonably good fits to the observed decay constants are obtained.
DEFF Research Database (Denmark)
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...
String theory, cosmology and varying constants
Damour, Thibault
In string theory the coupling `constants' appearing in the low-energy effective Lagrangian are determined by the vacuum expectation values of some (a priori) massless scalar fields (dilaton, moduli). This naturally leads one to expect a correlated variation of all the coupling constants, and an associated violation of the equivalence principle. We review some string-inspired theoretical models which incorporate such a spacetime variation of coupling constants while remaining naturally compatible both with phenomenological constraints coming from geochemical data (Oklo; Rhenium decay) and with present equivalence principle tests. Barring a very unnatural fine-tuning of parameters, a variation of the fine-structure constant as large as that recently `observed' by Webb et al. in quasar absorption spectra appears to be incompatible with these phenomenological constraints. Independently of any model, it is emphasized that the best experimental probe of varying constants are high-precision tests of the universality of free fall, such as MICROSCOPE and STEP.
String theory, cosmology and varying constants
Damour, Thibault Marie Alban Guillaume
2002-01-01
In string theory the coupling ``constants'' appearing in the low-energy effective Lagrangian are determined by the vacuum expectation values of some (a priori) massless scalar fields (dilaton, moduli). This naturally leads one to expect a correlated variation of all the coupling constants, and an associated violation of the equivalence principle. We review some string-inspired theoretical models which incorporate such a spacetime variation of coupling constants while remaining naturally compatible both with phenomenological constraints coming from geochemical data (Oklo; Rhenium decay) and with present equivalence principle tests. Barring a very unnatural fine-tuning of parameters, a variation of the fine-structure constant as large as that recently ``observed'' by Webb et al. in quasar absorption spectra appears to be incompatible with these phenomenological constraints. Independently of any model, it is emphasized that the best experimental probe of varying constants are high-precision tests of the universa...
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...
General Relativity, Cosmological Constant and Modular Forms
Kraniotis, G V
2001-01-01
Strong field (exact) solutions of the gravitational field equations of General Relativity in the presence of a Cosmological Constant are investigated. In particular, a full exact solution is derived within the inhomogeneous Szekeres-Szafron family of space-time line element with a nonzero Cosmological Constant. The resulting solution connects, in an intrinsic way, General Relativity with the theory of modular forms and elliptic curves and thus to the theory of Taniyama-Shimura.The homogeneous FLRW limit of the above space-time elements is recovered and we solve exactly the resulting Friedmann Robertson field equation with the appropriate matter density for generic values of the Cosmological Constant $ \\Lambda $ and curvature constant $K$. A formal expression for the Hubble constant is derived. The cosmological implications of the resulting non-linear solutions are systematically investigated. Two particularly interesting solutions i) the case of a flat universe $K=0,\\Lambda \
Tojeiro, Rita; Wake, David A; Maraston, Claudia; Skibba, Ramin A; Zehavi, Idit; Ross, Ashley J; Conroy, Charlie; Guo, Hong; Manera, Marc; Masters, Karen L; Pforr, Janine; Samushia, Lado; Schneider, Donald P; Thomas, Daniel; Bizyaev, Dmitry; Brewington, Howard; Malanushenko, Elena; Malanushenko, Viktor; Oravetz, Daniel; Pan, Kaike; Shelden, Alaina; Simmons, Audrey; Snedden, Stephanie
2012-01-01
We present a comprehensive study of 250,000 galaxies targeted by the Baryon Oscillation Spectroscopic Survey (BOSS) up to z {\\approx} 0.7 with the specific goal of identifying and characterising a population of galaxies that has followed passive evolution (no mergers) as closely as possible. We compute a likelihood that each BOSS galaxy is a progenitor of the Luminous Red Galaxies (LRGs) sample, targeted by SDSS-I/II up z {\\approx} 0.5, by using the fossil record of LRGs and their inferred star-formation histories, metallicity histories and dust content. We determine merger rates, luminosity growth rates and the evolution of the large-scale clustering between the two surveys, and we investigate the effect of using different stellar population synthesis models in our conclusions. We demonstrate that our sample is slowly evolving (of the order of 2 {\\pm} 1.5% Gyr-1 by merging) by computing the change in weighted luminosity-per-galaxy between the two samples, and that this result is robust to our choice of stell...
Tease, Katherine Whitaker; vanDokkum, Pieter G.; Brammer, Gabriel; Momcheva, Ivelina; Skelton, Rosalind; Franx, Marijin; Kriek, Mariska; Labbe, Ivo; Fumagalli, Mattia; Lundgren, Britt F.; Nelson, Erica J.; Patel, Shannon G.; Rix, Hans-Walter
2013-01-01
Quiescent galaxies at z approx. 2 have been identified in large numbers based on rest-frame colors, but only a small number of these galaxies have been spectroscopically confirmed to show that their rest-frame optical spectra show either strong Balmer or metal absorption lines. Here, we median stack the rest-frame optical spectra for 171 photometrically quiescent galaxies at 1.4 populations already existed when the universe was approx. 3 Gyr old, and that rest-frame color selection techniques can efficiently select them. We find an average age of 1.3+0.10.3 Gyr when fitting a simple stellar population to the entire stack. We confirm our previous result from medium-band photometry that the stellar age varies with the colors of quiescent galaxies: the reddest 80 of galaxies are dominated by metal lines and have a relatively old mean age of 1.6+0.50.4 Gyr, whereas the bluest (and brightest) galaxies have strong Balmer lines and a spectroscopic age of 0.9+0.20.1 Gyr. Although the spectrum is dominated by an evolved stellar population, we also find [O iii] and H emission. Interestingly, this emission is more centrally concentrated than the continuum with LOiii = 1.7+/- 0.3 x 10(exp 40) erg/s, indicating residual central star formation or nuclear activity.
$\\bar{\\psi} \\psi$-condensate in constant magnetic fields
Anguiano-Galicia, M de J; Raya, A
2007-01-01
We solve Dirac equation in the presence of a constant magnetic field in (3+1)- and (2+1)-dimensions. Quantizing the fermion field, we calculate $\\bar{\\psi} \\psi$-condensate from first principles for parity conserving and violating Lagrangians for arbitrary field strength. We make comparison with the results already known in the literature for some particular cases and point out the relevance of our work for possible physical applications.
EFFECTS OF CONSTANT EXCITATION ON LOCAL BIFURCATION
Institute of Scientific and Technical Information of China (English)
WU Zhi-qiang; CHEN Yu-shu
2006-01-01
The effects of the constant excitation on the local bifurcation of the periodic solutions in the 1:2 internal resonant systems were analyzed based on the singularity theory. It is shown that the constant excitation make influence only when there exist some nonlinear terms, in the oscillator with lower frequency. Besides acting as main bifurcation parameter, the constant excitation, together with coefficients of some nonlinear terms,may change the values of unfolding parameters and the type of the bifurcation. Under the non-degenerate cases, the effect of the third order terms can be neglected.
The Determination of the Strong Coupling Constant
Dissertori, Günther
2016-10-01
The strong coupling constant is one of the fundamental parameters of the Standard Theory of particle physics. In this review I will briefly summarise the theoretical framework, within which the strong coupling constant is defined and how it is connected to measurable observables. Then I will give an historical overview of its experimental determinations and discuss the current status and world average value. Among the many different techniques used to determine this coupling constant in the context of quantum chromodynamics, I will focus in particular on a number of measurements carried out at the Large Electron-Positron Collider (LEP) and the Large Hadron Collider (LHC) at CERN.
Some Zero-Sum Constants with Weights
Indian Academy of Sciences (India)
S D Adhikari; R Balasubramanian; F Pappalardi; P Rath
2008-05-01
For an abelian group , the Davenport constant () is defined to be the smallest natural number such that any sequence of elements in has a non-empty subsequence whose sum is zero (the identity element). Motivated by some recent developments around the notion of Davenport constant with weights, we study them in some basic cases. We also define a new combinatorial invariant related to $(\\mathbb{Z}/n\\mathbb{Z})^d$, more in the spirit of some constants considered by Harborth and others and obtain its exact value in the case of $(\\mathbb{Z}/n\\mathbb{Z})^2$ where is an odd integer.
Colossal dielectric constant in high entropy oxides
Energy Technology Data Exchange (ETDEWEB)
Berardan, David; Franger, Sylvain; Dragoe, Diana; Meena, Arun Kumar; Dragoe, Nita [ICMMO (UMR 8182 CNRS), Universite Paris-Sud, Universite Paris-Saclay, 91405, Orsay (France)
2016-04-15
materials by widening their (already complex) phase space. As a first example, we report here that at least one HEOx composition exhibits colossal dielectric constants, which could make it very promising for applications as large-k dielectric materials. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Marshak waves: Constant flux vs constant T-a (slight) paradigm shift
Energy Technology Data Exchange (ETDEWEB)
Rosen, M.D.
1994-12-22
We review the basic scaling laws for Marshak waves and point out the differences in results for wall loss, albedo, and Marshak depth when a constant absorbed flux is considered as opposed to a constant absorbed temperature. Comparisons with LASNEX simulations and with data are presented that imply that a constant absorbed flux is a more appropriate boundary condition.
Determination of the gravitational constant G
Institute of Scientific and Technical Information of China (English)
HU Zhong-kun; LIU Qi; LUO Jun
2006-01-01
A precise knowledge of the Newtonian gravitational constant G has an important role in physics and is of considerable meteorological interest.Although G was the first physical constant to be introduced and measured in the history of science,it is still the least precisely determined of all the fundamental constants of nature.The 2002 CODATA recommended value for G,G=(6.6742±0.0010)×10-11m3·kg-1·s-2,has an uncertainty of 150 parts per million (ppm),much larger than that of all other fundamental constants.Reviewed here is the status of our knowledge of the absolute value of G,methods for determining G,and recent high precision experiments for determining G.
Black holes with constant topological Euler density
Bargueño, Pedro
2016-01-01
A class of four dimensional spherically symmetric and static geometries with constant topological Euler density is studied. These geometries are shown to solve the coupled Einstein-Maxwell system when non-linear Born-Infeld-like electrodynamics is employed.
Interacting universes and the cosmological constant
Energy Technology Data Exchange (ETDEWEB)
Alonso-Serrano, A. [Centro de Física “Miguel Catalán”, Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid (Spain); Estación Ecológica de Biocosmología, Pedro de Alvarado 14, 06411 Medellín (Spain); Bastos, C. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Bertolami, O. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Robles-Pérez, S., E-mail: salvarp@imaff.cfmac.csic.es [Centro de Física “Miguel Catalán”, Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid (Spain); Estación Ecológica de Biocosmología, Pedro de Alvarado 14, 06411 Medellín (Spain); Física Teórica, Universidad del País Vasco, Apartado 644, 48080 Bilbao (Spain)
2013-02-12
In this Letter it is studied the effects that an interaction scheme among universes can have in the values of their cosmological constants. In the case of two interacting universes, the value of the cosmological constant of one of the universes becomes very close to zero at the expense of an increasing value of the cosmological constant of the partner universe. In the more general case of a chain of N interacting universes with periodic boundary conditions, the spectrum of the Hamiltonian splits into a large number of levels, each of them associated with a particular value of the cosmological constant, that can be occupied by single universes revealing a collective behavior that plainly shows that the multiverse is much more than the mere sum of its parts.
The time constant of the somatogravic illusion
Correia Grácio, B.J.; Winkel, K.N. de; Groen, E.L.; Wentink, M.; Bos, J.E.
2013-01-01
Met desdemona hebben we gevonden dat de tijd constante van de somatografische illusie rond twee seconden is. Dit resultaat verschilt van wat was gevonden in ander onderzoek dat gebruikt maakt van een gewone centrifuge
Prime rings with PI rings of constants
Kharchenko, V K; Rodríguez-Romo, S
1996-01-01
It is shown that if the ring of constants of a restricted differential Lie algebra with a quasi-Frobenius inner part satisfies a polynomial identity (PI) then the original prime ring has a generalized polynomial identitiy (GPI). If additionally the ring of constants is semiprime then the original ring is PI. The case of a non-quasi-Frobenius inner part is also considered.
Trialogue on the number of fundamental constants
Duff, Michael J; Veneziano, Gabriele
2002-01-01
This paper consists of three separate articles on the number of fundamental dimensionful constants in physics. We started our debate in summer 1992 on the terrace of the famous CERN cafeteria. In the summer of 2001 we returned to the subject to find that our views still diverged and decided to explain our current positions. LBO develops the traditional approach with three constants, GV argues in favor of just two, while MJD advocates zero.
Inflationary Phase with Time Varying Fundamental Constants
Berman, M S; Berman, Marcelo S.; Trevisan, Luis A.
2002-01-01
Following Barrow, and Barrow and collaborators, we find a cosmological JBD model, with varying speed of light and varying fine structure constant, where the deceleration parameter is -1,causing acceleration of the Universe.Indeed, we have an exponential inflationary phase. Plancks time, energy, length,etc.,might have had different numerical values in the past, than those available in the litterature, due to the varying values for speed of light, and gravitational constant.
The Origin of the Constant Carbohydrate Diet
Directory of Open Access Journals (Sweden)
Charles Herbert Read
2009-01-01
Full Text Available The Constant Carbohydrate diet, based entirely on carbohydrate exchanges, is now widely used in the dietary treatment of diabetes mellitus. Being based on sound scientific principles and simple in design, the Constant Carabohydrate diet is appropriate for all those having diabetes mellitus, young or old, no matter their ethncity. This report describes why and how it was developed in 1951. Its simplicity makes it adaptable to all ethnic diets.
The Origin of the Constant Carbohydrate Diet
Directory of Open Access Journals (Sweden)
Read CharlesHerbert
2008-01-01
Full Text Available The Constant Carbohydrate diet, based entirely on carbohydrate exchanges, is now widely used in the dietary treatment of diabetes mellitus. Being based on sound scientific principles and simple in design, the Constant Carabohydrate diet is appropriate for all those having diabetes mellitus, young or old, no matter their ethncity. This report describes why and how it was developed in 1951. Its simplicity makes it adaptable to all ethnic diets.
Beyond lensing by the cosmological constant
Faraoni, Valerio
2016-01-01
The long-standing problem of whether the cosmological constant affects directly the deflection of light caused by a gravitational lens is reconsidered. We use a new approach based on the Hawking quasilocal mass of a sphere grazed by light rays and on its splitting into local and cosmological parts. Previous literature restricted to the cosmological constant is extended to any form of dark energy accelerating the universe in which the gravitational lens is embedded.
Beyond lensing by the cosmological constant
Faraoni, Valerio; Lapierre-Léonard, Marianne
2017-01-01
The long-standing problem of whether the cosmological constant affects directly the deflection of light caused by a gravitational lens is reconsidered. We use a new approach based on the Hawking quasilocal mass of a sphere grazed by light rays and on its splitting into local and cosmological parts. Previous literature restricted to the cosmological constant is extended to any form of dark energy accelerating the universe in which the gravitational lens is embedded.
A constant elasticity of profit production function
Beard, Rodney
2007-01-01
Impact analysis of changes in production inputs may be simplified if one can apply a constant adjustment factor to profit. In particular, if a production function can be found for which the elasticity of profit is constant and this function has desirable properties, then one can use the input elasticity of profit to study the impact of input changes on profit. In this paper such a production function is derived from first principles.
RNA structure and scalar coupling constants
Energy Technology Data Exchange (ETDEWEB)
Tinoco, I. Jr.; Cai, Z.; Hines, J.V.; Landry, S.M.; SantaLucia, J. Jr.; Shen, L.X.; Varani, G. [Univ. of California, Berkeley, CA (United States)
1994-12-01
Signs and magnitudes of scalar coupling constants-spin-spin splittings-comprise a very large amount of data that can be used to establish the conformations of RNA molecules. Proton-proton and proton-phosphorus splittings have been used the most, but the availability of {sup 13}C-and {sup 15}N-labeled molecules allow many more coupling constants to be used for determining conformation. We will systematically consider the torsion angles that characterize a nucleotide unit and the coupling constants that depend on the values of these torsion angles. Karplus-type equations have been established relating many three-bond coupling constants to torsion angles. However, one- and two-bond coupling constants can also depend on conformation. Serianni and coworkers measured carbon-proton coupling constants in ribonucleosides and have calculated their values as a function of conformation. The signs of two-bond coupling can be very useful because it is easier to measure a sign than an accurate magnitude.
Irradiation creep and void swelling of two LMR heat of HT9 at {approx}400{degrees}C and 165 dpa
Energy Technology Data Exchange (ETDEWEB)
Toloczko, M.B. [Univ. of California, Santa Barbara, CA (United States); Garner, F.A. [Pacific Northwest National Laboratory, Richland, WA (United States)
1996-04-01
Two nominally identical heats of HT9 ferritic-martensitic steel were produced, fabricated into pressurized tubes, and then irradiated in FFTF, using identical procedures. After reaching 165 dpa at {approx}400C, small differences in strains associated with both phase-related change in lattice parameter and void swelling were observed in comparing the two heats. The creep strains, while different, exhibited the same functional relationship to the swelling behavior. The derived creep coefficients, the one associated with creep in the absence of swelling and the one directly responsive to swelling, were essentially identical for the two heats. Even more significantly, the creep coefficients for this bcc ferritic-martensitic steel appear to be very similar and possibly identical to those routinely derived from creep experiments on fcc austenitic steels.
Simon, V V; Chowdhury, U; Eberhardt, B; Ettenauer, S; Gallant, A T; Mané, E; Simon, M C; Delheij, P; Pearson, M R; Audi, G; Gwinner, G; Lunney, D; Schatz, H; Dilling, J
2012-01-01
The neutron-rich mass region around $A\\approx100$ presents challenges for modeling the astrophysical $r$-process because of rapid shape transitions. We report on mass measurements using the TITAN Penning trap at TRIUMF-ISAC to attain more reliable theoretical predictions of $r$-process nucleosynthesis paths in this region. A new approach using highly charged ($q=15+$) ions has been applied which considerably saves measurement time and preserves accuracy. New mass measurements of neutron-rich $^{94,97,98}$Rb and $^{94,97-99}$Sr have uncertainties of less than 4 keV and show deviations of up to 11$\\sigma$ to previous measurements. An analysis using a parameterized $r$-process model is performed and shows that mass uncertainties for the A=90 abundance region are eliminated.
Energy Technology Data Exchange (ETDEWEB)
Kalirai, Jason S.; Anderson, Jay; Dotter, Aaron; Reid, I. Neill [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Richer, Harvey B. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC (Canada); Fahlman, Gregory G. [National Research Council, Herzberg Institute of Astrophysics, Victoria, BC (Canada); Hansen, Brad M. S.; Rich, R. Michael [Division of Astronomy and Astrophysics, University of California at Los Angeles, Los Angeles, CA 90095 (United States); Hurley, Jarrod [Center for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn VIC 3122 (Australia); Shara, Michael M., E-mail: jkalirai@stsci.edu, E-mail: jayander@stsci.edu, E-mail: dotter@stsci.edu, E-mail: richer@astro.ubc.ca, E-mail: greg.fahlman@nrc-cnrc.gc.ca, E-mail: hansen@astro.ucla.edu, E-mail: rmr@astro.ucla.edu, E-mail: jhurley@swin.edu.au, E-mail: mshara@amnh.org [Department of Astrophysics, American Museum of Natural History, Central Park West and 79th Street, New York, NY 10024 (United States)
2013-02-15
We present a new measurement of the stellar initial mass function (IMF) based on ultra-deep, high-resolution photometry of >5000 stars in the outskirts of the Small Magellanic Cloud (SMC) galaxy. The Hubble Space Telescope (HST) Advanced Camera for Surveys observations reveal this rich, cospatial population behind the foreground globular cluster 47 Tuc, which we targeted for 121 HST orbits. The stellar main sequence of the SMC is measured in the F606W, F814W color-magnitude diagram down to {approx}30th magnitude, and is cleanly separated from the foreground star cluster population using proper motions. We simulate the SMC population by extracting stellar masses (single and unresolved binaries) from specific IMFs and converting those masses to luminosities in our bandpasses. The corresponding photometry for these simulated stars is drawn directly from a rich cloud of 4 million artificial stars, thereby accounting for the real photometric scatter and completeness of the data. Over a continuous and well-populated mass range of M = 0.37-0.93 M {sub Sun} (e.g., down to a {approx}75% completeness limit at F606W = 28.7), we demonstrate that the IMF is well represented by a single power-law form with slope {alpha} = -1.90 ({sup +0.15} {sub -0.10}) (3{sigma} error) (e.g., dN/dM{proportional_to} M {sup {alpha}}). This is shallower than the Salpeter slope of {alpha} = -2.35, which agrees with the observed stellar luminosity function at higher masses. Our results indicate that the IMF does not turn over to a more shallow power-law form within this mass range. We discuss implications of this result for the theory of star formation, the inferred masses of galaxies, and the (lack of a) variation of the IMF with metallicity.
DEFF Research Database (Denmark)
Jongberg, Sisse; Lund, Marianne Nissen; Pattison, David I.
2016-01-01
. This approach allows determination of apparent rate constants for the oxidation of proteins by haem proteins of relevance to food oxidation and should be applicable to other systems. A similar approach has provided approximate apparent rate constants for the reduction of MbFe(IV)=O by catechin and green tea...
A new combinatorial approach to the construction of constant composition codes
Institute of Scientific and Technical Information of China (English)
2008-01-01
Constant composition codes(CCCs)are a new generalization of binary constant weight codes and have attracted recent interest due to their numerous applications. In this paper, a new combinatorial approach to the construction of CCCs is proposed, and used to establish new optimal CCCs.
Preliminary results of solar constant observations with the SOLCON experiment on ATLAS-1
Crommelynck, D.; Domingo, V.; Barkstrom, B.; Lee, R. B., II; Donaldson, J.; Telljohann, U; Warren, L.; Fichot, A.
1994-01-01
A brief description is given of the Solar Constant (SOLCAN) experiment on Atmospheric Laboratory for Applications and Science (ATLAS) 1, its scientific and technical objectives, as well as its measurement principle and its on board chronology of operations. A preliminary value of the solar constant during the third solar operation of the mission is also provided.
The modified Black-Scholes model via constant elasticity of variance for stock options valuation
Edeki, S. O.; Owoloko, E. A.; Ugbebor, O. O.
2016-02-01
In this paper, the classical Black-Scholes option pricing model is visited. We present a modified version of the Black-Scholes model via the application of the constant elasticity of variance model (CEVM); in this case, the volatility of the stock price is shown to be a non-constant function unlike the assumption of the classical Black-Scholes model.
A Constant Factor Approximation Algorithm for Reordering Buffer Management
Avigdor-Elgrabli, Noa
2012-01-01
In the reordering buffer management problem (RBM) a sequence of $n$ colored items enters a buffer with limited capacity $k$. When the buffer is full, one item is removed to the output sequence, making room for the next input item. This step is repeated until the input sequence is exhausted and the buffer is empty. The objective is to find a sequence of removals that minimizes the total number of color changes in the output sequence. The problem formalizes numerous applications in computer and production systems, and is known to be NP-hard. We give the first constant factor approximation guarantee for RBM. Our algorithm is based on an intricate "rounding" of the solution to an LP relaxation for RBM, so it also establishes a constant upper bound on the integrality gap of this relaxation. Our results improve upon the best previous bound of $O(\\sqrt{\\log k})$ of Adamaszek et al. (STOC 2011) that used different methods and gave an online algorithm. Our constant factor approximation beats the super-constant lower b...
Athermal nonlinear elastic constants of amorphous solids.
Karmakar, Smarajit; Lerner, Edan; Procaccia, Itamar
2010-08-01
We derive expressions for the lowest nonlinear elastic constants of amorphous solids in athermal conditions (up to third order), in terms of the interaction potential between the constituent particles. The effect of these constants cannot be disregarded when amorphous solids undergo instabilities such as plastic flow or fracture in the athermal limit; in such situations the elastic response increases enormously, bringing the system much beyond the linear regime. We demonstrate that the existing theory of thermal nonlinear elastic constants converges to our expressions in the limit of zero temperature. We motivate the calculation by discussing two examples in which these nonlinear elastic constants play a crucial role in the context of elastoplasticity of amorphous solids. The first example is the plasticity-induced memory that is typical to amorphous solids (giving rise to the Bauschinger effect). The second example is how to predict the next plastic event from knowledge of the nonlinear elastic constants. Using the results of our calculations we derive a simple differential equation for the lowest eigenvalue of the Hessian matrix in the external strain near mechanical instabilities; this equation predicts how the eigenvalue vanishes at the mechanical instability and the value of the strain where the mechanical instability takes place.
Environment-Dependent Fundamental Physical Constants
Terazawa, Hidezumi
2012-01-01
A theory of special inconstancy, in which some fundamental physical constants such as the fine-structure and gravitational constants may vary, is proposed in pregeometry. In the special theory of inconstancy, the \\alpha-G relation of \\alpha=3\\pi/[16ln(4\\pi/5GM_W^2)] between the varying fine-structure and gravitaional constants (where M_W is the charged weak boson mass) is derived from the hypothesis that both of these constants are related to the same fundamental length scale in nature. Furthermore, it leads to the prediction of dot{{\\alpha}}/\\alpha=(-0.8\\pm2.5)\\times10^{-14}yr^{-1} from the most precise limit of dot{G}/G=(-0.6\\pm2.0)\\times10^{-12}yr^{-1} by Thorsett, which is not only consistent with the recent observation of dot{{\\alpha}}/\\alpha=(0.5\\pm0.5)\\times10^{-14}yr^{-1} by Webb et al. but also feasible for future experimental tests. Also a theory of general inconstancy, in which any fundamental physical constants may vary, is proposed in "more general relativity", by assuming that the space-time is ...
An Improved Dielectric Constant Cell for Use in Student and Research Laboratories.
Thompson, H. Bradford.; Walmsley, Judith A.
1979-01-01
Describes the latest stage in the design of an economical dielectric constant cell, tested in both instructional and research applications, that is suitable for student laboratories and for precision research measurements. (BT)
The case for the cosmological constant
Indian Academy of Sciences (India)
Varun Sahni
2000-07-01
I present a short overview of current observational results and theoretical models for a cosmological constant. The main motivation for invoking a small cosmological constant (or -term) at the present epoch has to do with observations of high redshift Type Ia supernovae which suggest an accelerating universe. A ﬂat accelerating universe is strongly favoured by combining supernovae observations with observations of CMB anisotropies on degree scales which give the `best-ﬁt’ values ≃ 0.7 and m ≃ 0.3. A time dependent cosmological -term can be generated by scalar ﬁeld models with exponential and power law potentials. Some of these models can alleviate the `ﬁne tuning’ problem which faces the cosmological constant.
Bounds on Gromov Hyperbolicity Constant in Graphs
Indian Academy of Sciences (India)
José M Rodríguez; José M Sigarreta
2012-02-01
If is a geodesic metric space and 1,2,3 $\\in$ , a geodesic triangle ={1,2,3} is the union of the three geodesics [1,2], [2,3] and [31] in . The space is -hyperbolic (in the Gromov sense) if any side of is contained in a -neighborhood of the union of two other sides, for every geodesic triangle in . If is hyperbolic, we denote by () the sharp hyperbolicity constant of , i.e. ()=$inf{$≥ 0$ : is -hyperbolic}. In this paper we relate the hyperbolicity constant of a graph with some known parameters of the graph, as its independence number, its maximum and minimum degree and its domination number. Furthermore, we compute explicitly the hyperbolicity constant of some class of product graphs.
Construction and experimental testing of the constant-bandwidth constant-temperature anemometer.
Ligeza, P
2008-09-01
A classical constant-temperature hot-wire anemometer enables the measurement of fast-changing flow velocity fluctuations, although its transmission bandwidth is a function of measured velocity. This may be a source of significant dynamic errors. Incorporation of an adaptive controller into the constant-temperature system results in hot-wire anemometer operating with a constant transmission bandwidth. The construction together with the results of experimental testing of a constant-bandwidth hot-wire anemometer prototype are presented in this article. During the testing, an approximately constant transmission bandwidth of the anemometer was achieved. The constant-bandwidth hot-wire anemometer can be used in measurements of high-frequency variable flows characterized by a wide range of velocity changes.
Construction of constant-Q viscoelastic model with three parameters
Institute of Scientific and Technical Information of China (English)
SUN Cheng-yu; YIN Xing-yao
2007-01-01
The popularly used viscoelastic models have some shortcomings in describing relationship between quality factor (Q) and frequency, which is not consistent with the observation data. Based on the theory of viscoelasticity, a new approach to construct constant-Q viscoelastic model in given frequency band with three parameters is developed. The designed model describes the frequency-independence feature of quality factor very well, and the effect of viscoelasticity on seismic wave field can be studied relatively accurate in theory with this model. Furthermore, the number of required parameters in this model has been reduced fewer than that of other constant-Q models, this can simplify the solution of the viscoelastic problems to some extent. At last, the accuracy and application range have been analyzed through numerical tests. The effect of viscoelasticity on wave propagation has been briefly illustrated through the change of frequency spectra and waveform in several different viscoelastic models.
A Parallel Priority Queue with Constant Time Operations
DEFF Research Database (Denmark)
Brodal, Gerth Stølting; Träff, Jesper Larsson; Zaroliagis, Christos D.
1998-01-01
We present a parallel priority queue that supports the following operations in constant time:parallel insertionof a sequence of elements ordered according to key,parallel decrease keyfor a sequence of elements ordered according to key,deletion of the minimum key element, anddeletion of an arbitrary...... element. Our data structure is the first to support multi-insertion and multi-decrease key in constant time. The priority queue can be implemented on the EREW PRAM and can perform any sequence ofnoperations inO(n) time andO(mlogn) work,mbeing the total number of keyes inserted and/or updated. A main...... application is a parallel implementation of Dijkstra's algorithm for the single-source shortest path problem, which runs inO(n) time andO(mlogn) work on a CREW PRAM on graphs withnvertices andmedges. This is a logarithmic factor improvement in the running time compared with previous approaches....
Optical constants of infrared (IR) materials in the IR region
Nagendra, C. L.; Thutupalli, G. K. M.
1992-01-01
Optical constants, i.e., refractive index 'n' and absorption index 'k' of the IR materials, Ge, ThF4, CdTe and CdSe have been determined, through spectrophotometric method, in the IR region from 2.5 to 15 microns. It is seen that all these films are transparent in the IR region, and the optical constants of the films deposited at elevated temperatures (T = 200 C) are unaffected, even after subjecting to severe environs such as humidity and thermal shock/cycling. Making use of Ge/ThF4 and CdTe/CdSe coating combinations, IR antireflection coatings (ARCs) which can find applications in space-borne electrooptical systems have been successfully designed and developed. The resulting ARCs have not only efficient optical properties, low reflection loss and high transmission, but are also durable against adverse environments.
Degravitation of the Cosmological Constant in Bigravity
Platscher, Moritz
2016-01-01
In this article the phenomenon of degravitation of the cosmological constant is studied in the framework of bigravity. It is demonstrated that despite a sizable value of the cosmological constant its gravitational effect can be only mild. The bigravity framework is chosen for this demonstration as it leads to a consistent, ghost-free theory of massive gravity. We show that degravitation takes place in the limit where the physical graviton is dominantly a gauge invariant metric combination. We present and discuss several phenomenological consequences expected in this regime.
Cosmological constant, supersymmetry, nonassociativity, and big numbers
Energy Technology Data Exchange (ETDEWEB)
Dzhunushaliev, Vladimir [KazNU, Department of Theoretical and Nuclear Physics, Almaty (Kazakhstan); IETP, Al-Farabi KazNU, Almaty (Kazakhstan)
2015-02-01
The nonassociative generalization of supersymmetry is considered. It is shown that the associator of four supersymmetry generators has the coefficient ∝ ℎ/l{sub 0}{sup 2} where l0 is some characteristic length. Two cases are considered: (a) l{sub 0}{sup -2} coincides with the cosmological constant; (b) l{sub 0} is the classical radius of the electron. It is also shown that the scaled constant is of the order of 10{sup -120} for the first case and 10{sup -30} for the second case. The possible manifestation and smallness of nonassociativity is discussed. (orig.)
Black Ring with a Positive Cosmological Constant
Chu, C S; Chu, Chong-Sun; Dai, Shou-Huang
2007-01-01
We construct a black ring with a cosmological constant in the five dimensional N=4 de Sitter supergravity theory. The black ring preserves half of the de Sitter supersymmetries. Unlike the flat case, this black ring is not rotating and the stability against gravitational self-attraction is balanced by the cosmological repulsion due to the cosmological constant. The black ring carries a dipole charge and this charge contributes to the first law of thermodynamics. The black ring has an entropy and mass which conform to the entropic N-bound proposal and the maximal mass conjecture.
Atomic weights: no longer constants of nature
Coplen, Tyler B.; Holden, Norman E.
2011-01-01
Many of us were taught that the standard atomic weights we found in the back of our chemistry textbooks or on the Periodic Table of the Chemical Elements hanging on the wall of our chemistry classroom are constants of nature. This was common knowledge for more than a century and a half, but not anymore. The following text explains how advances in chemical instrumentation and isotopic analysis have changed the way we view atomic weights and why they are no longer constants of nature
Flexible alternatives to constant frequency systems
Stewart-Wilson, John
The use of hybrid systems in which variable frequency is used as generated, with a proportion being converted to constant frequency by electronic conversion, is examined as a flexible alternative to constant frequency systems. Here, some practical solutions to the technical issues raised by adopting the more flexible approach to electrical system generation are presented. In particular, attention is given to the frequency ranges used, impact on aircraft equipment, motor-driven equipment, transformer rectifier units, lighting, and avionics. The discussion also covers fan-assisted galley ovens, system architecture, special airworthiness requirements, and power quality.
The Cosmological Constant Problem (2/2)
CERN. Geneva
2015-01-01
I will review the cosmological constant problem as a serious challenge to our notion of naturalness in Physics. Weinberg’s no go theorem is worked through in detail. I review a number of proposals possibly including Linde's universe multiplication, Coleman's wormholes, the fat graviton, and SLED, to name a few. Large distance modifications of gravity are also discussed, with causality considerations pointing towards a global modification as being the most sensible option. The global nature of the cosmological constant problem is also emphasized, and as a result, the sequestering scenario is reviewed in some detail, demonstrating the cancellation of the Standard Model vacuum energy through a global modification of General Relativity.
The Cosmological Constant Problem (1/2)
CERN. Geneva
2015-01-01
I will review the cosmological constant problem as a serious challenge to our notion of naturalness in Physics. Weinberg’s no go theorem is worked through in detail. I review a number of proposals possibly including Linde's universe multiplication, Coleman's wormholes, the fat graviton, and SLED, to name a few. Large distance modifications of gravity are also discussed, with causality considerations pointing towards a global modification as being the most sensible option. The global nature of the cosmological constant problem is also emphasized, and as a result, the sequestering scenario is reviewed in some detail, demonstrating the cancellation of the Standard Model vacuum energy through a global modification of General Relativity.
Do the fundamental constants change with time ?
Kanekar, Nissim
2008-01-01
Comparisons between the redshifts of spectral lines from cosmologically-distant galaxies can be used to probe temporal changes in low-energy fundamental constants like the fine structure constant and the proton-electron mass ratio. In this article, I review the results from, and the advantages and disadvantages of, the best techniques using this approach, before focussing on a new method, based on conjugate satellite OH lines, that appears to be less affected by systematic effects and hence holds much promise for the future.
Variations of fundamental constants and multidimensional gravity
Bronnikova, K. A.; Skvortsova, M. V.
We try to explain the recently reported large-scale spatial variations of the fine structure constant α, in agreement with other cosmological observations, in the framework of curvature-nonlinear multidimensional gravity. The original theory is reduced to a scalar-tensor theory in four dimensions, and the corresponding isotropic cosmologies are considered in both Einstein and Jordan conformal frames. In the Jordan frame one obtains simultaneous variations of α and the gravitational constant G, equal in magnitude. Long-wave small inhomogeneous perturbations of isotropic models allow for explaining spatial variations of α.
Porous low dielectric constant materials for microelectronics.
Baklanov, Mikhail R; Maex, Karen
2006-01-15
Materials with a low dielectric constant are required as interlayer dielectrics for the on-chip interconnection of ultra-large-scale integration devices to provide high speed, low dynamic power dissipation and low cross-talk noise. The selection of chemical compounds with low polarizability and the introduction of porosity result in a reduced dielectric constant. Integration of such materials into microelectronic circuits, however, poses a number of challenges, as the materials must meet strict requirements in terms of properties and reliability. These issues are the subject of the present paper.
Coulomb field in a constant electromagnetic background
Adorno, T C; Shabad, A E
2016-01-01
Nonlinear Maxwell equations are written up to the third-power deviations from a constant-field background, valid within any local nonlinear electrodynamics including QED with Euler-Heisenberg effective Lagrangian. Linear electric response to imposed static finite-sized charge is found in the vacuum filled by an arbitrary combination of constant and homogeneous electric and magnetic fields. The modified Coulomb field, corrections to the total charge and to the charge density are given in terms of derivatives of the effective Lagrangian with respect to the field invariants.
Conformational dependence of {sup 13}C shielding and coupling constants for methionine methyl groups
Energy Technology Data Exchange (ETDEWEB)
Butterfoss, Glenn L. [New York University, Courant Institute of Mathematical Sciences and the Center for Genomics and Systems Biology (United States); DeRose, Eugene F.; Gabel, Scott A.; Perera, Lalith; Krahn, Joseph M.; Mueller, Geoffrey A.; Zheng Xunhai; London, Robert E., E-mail: London@niehs.nih.go [National Institute of Environmental Health Sciences (NIEHS), NIH, Laboratory of Structural Biology (United States)
2010-09-15
Methionine residues fulfill a broad range of roles in protein function related to conformational plasticity, ligand binding, and sensing/mediating the effects of oxidative stress. A high degree of internal mobility, intrinsic detection sensitivity of the methyl group, and low copy number have made methionine labeling a popular approach for NMR investigation of selectively labeled protein macromolecules. However, selective labeling approaches are subject to more limited information content. In order to optimize the information available from such studies, we have performed DFT calculations on model systems to evaluate the conformational dependence of {sup 3}J{sub CSCC}, {sup 3}J{sub CSCH}, and the isotropic shielding, {sigma}{sub iso}. Results have been compared with experimental data reported in the literature, as well as data obtained on [methyl-{sup 13}C]methionine and on model compounds. These studies indicate that relative to oxygen, the presence of the sulfur atom in the coupling pathway results in a significantly smaller coupling constant, {sup 3}J{sub CSCC}/{sup 3}J{sub COCC} {approx} 0.7. It is further demonstrated that the {sup 3}J{sub CSCH} coupling constant depends primarily on the subtended CSCH dihedral angle, and secondarily on the CSCC dihedral angle. Comparison of theoretical shielding calculations with the experimental shift range of the methyl group for methionine residues in proteins supports the conclusion that the intra-residue conformationally-dependent shift perturbation is the dominant determinant of {delta}{sup 13}C{epsilon}. Analysis of calmodulin data based on these calculations indicates that several residues adopt non-standard rotamers characterized by very large {approx}100{sup o} {chi}{sup 3} values. The utility of the {delta}{sup 13}C{epsilon} as a basis for estimating the gauche/trans ratio for {chi}{sup 3} is evaluated, and physical and technical factors that limit the accuracy of both the NMR and crystallographic analyses are
Energy Technology Data Exchange (ETDEWEB)
Muzzin, Adam; Van Dokkum, Pieter [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States); Wilson, Gillian; Rettura, Alessandro [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Yee, H. K. C. [Department of Astronomy and Astrophysics, University of Toronto, Toronto, Ontario M5S 3H4 (Canada); Gilbank, David [South African Astronomical Observatory, Observatory 7935 (South Africa); Hoekstra, Henk; Franx, Marijn [Leiden Observatory, Leiden University, 2300 RA Leiden (Netherlands); Demarco, Ricardo; Nantais, Julie [Department of Astronomy, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Balogh, Michael [Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Ellingson, Erica [Center for Astrophysics and Space Astronomy, 389UCB, University of Colorado, Boulder, CO 80309 (United States); Hicks, Amalia [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-2320 (United States); Noble, Allison; Webb, Tracy [Department of Physics, McGill University, Montreal, QC (Canada); Lacy, Mark [North American ALMA Science Center, NRAO Headquarters, Charlottesville, VA 22903 (United States); Lidman, Chris [Australian Astronomical Observatory, Epping, NSW 1710 (Australia); Surace, Jason, E-mail: adam.muzzin@yale.edu [Spitzer Science Center, California Institute of Technology, 220-6 Pasadena, CA 91125 (United States)
2012-02-20
We evaluate the effects of environment and stellar mass on galaxy properties at 0.85
High Dielectric Constant Oxides for Advanced Micro-Electronic Applications
2006-11-29
Anatase phase Crystalline 117 Rutile phase TixSiyO2 PECVD Amorphous 3.9-30 All...Seo, "Dielectric and infrared properties of TiO2 films containing anatase and rutile ", Sem. Sci. and Technol. 20 870 (2005) A. H. Edwards, T
Quenched heavy-light decay constants
Energy Technology Data Exchange (ETDEWEB)
Baxter, R.M.; Booth, S.P.; Bowler, K.C.; Collins, S.; Henty, D.S.; Kenway, R.D.; Richards, D.G.; Shanahan, H.P.; Simone, J.N.; Simpson, A.D.; Wilkes, B.E. (Department of Physics, The University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom)); Ewing, A.K.; Lellouch, L.; Sachrajda, C.T.; Wittig, H. (Physics Department, The University, Southampton SO9 5NH (United Kingdom)); (UKQCD Collaboration)
1994-02-01
We present results for heavy-light decay constants, using both propagating quarks and the static approximation, in [ital O]([ital a])-improved, quenched lattice QCD. At [beta]=6.2 on a 24[sup 3][times]48 lattice we find [ital f][sub [ital D
Teaching Nanochemistry: Madelung Constants of Nanocrystals
Baker, Mark D.; Baker, A. David
2010-01-01
The Madelung constants for binary ionic nanoparticles are determined. The computational method described here sums the Coulombic interactions of each ion in the particle without the use of partial charges commonly used for bulk materials. The results show size-dependent lattice energies. This is a useful concept in teaching how properties such as…
Can compactifications solve the cosmological constant problem?
Energy Technology Data Exchange (ETDEWEB)
Hertzberg, Mark P. [Institute of Cosmology, Department of Physics and Astronomy, Tufts University,574 Boston Ave, Medford, MA 02155 (United States); Center for Theoretical Physics, Department of Physics,Massachusetts Institute of Technology,77 Massachusetts Ave, Cambridge, MA 02139 (United States); Masoumi, Ali [Institute of Cosmology, Department of Physics and Astronomy, Tufts University,574 Boston Ave, Medford, MA 02155 (United States)
2016-06-30
Recently, there have been claims in the literature that the cosmological constant problem can be dynamically solved by specific compactifications of gravity from higher-dimensional toy models. These models have the novel feature that in the four-dimensional theory, the cosmological constant Λ is much smaller than the Planck density and in fact accumulates at Λ=0. Here we show that while these are very interesting models, they do not properly address the real cosmological constant problem. As we explain, the real problem is not simply to obtain Λ that is small in Planck units in a toy model, but to explain why Λ is much smaller than other mass scales (and combinations of scales) in the theory. Instead, in these toy models, all other particle mass scales have been either removed or sent to zero, thus ignoring the real problem. To this end, we provide a general argument that the included moduli masses are generically of order Hubble, so sending them to zero trivially sends the cosmological constant to zero. We also show that the fundamental Planck mass is being sent to zero, and so the central problem is trivially avoided by removing high energy physics altogether. On the other hand, by including various large mass scales from particle physics with a high fundamental Planck mass, one is faced with a real problem, whose only known solution involves accidental cancellations in a landscape.
Quantum electrodynamics and the fundamental constants
Directory of Open Access Journals (Sweden)
Peter J. Mohr
2000-07-01
Full Text Available the results of critical experiments and the theoretical expressions for these results written in terms of the constants. Many of the theoretical expressions are based on quantum electrodynamics (QED, so the consistency of the comparison provides a critical test of the validity of the theory.
Cosmological models with constant deceleration parameter
Energy Technology Data Exchange (ETDEWEB)
Berman, M.S.; de Mello Gomide, F.
1988-02-01
Berman presented elsewhere a law of variation for Hubble's parameter that yields constant deceleration parameter models of the universe. By analyzing Einstein, Pryce-Hoyle and Brans-Dicke cosmologies, we derive here the necessary relations in each model, considering a perfect fluid.
Discrete Higgs and the Cosmological Constant
Amore, Paolo; Diaz-Cruz, J Lorenzo
2008-01-01
It is proposed that the Higgs vacuum possesses a small-scale structure that can explain the large discrepancy between the predicted electroweak vacuum energy density and the observed cosmological constant. An effective Lagrangian description is employed to obtain modifications to the Standard Model predictions that can be tested at collider experiments.
LIOUVILLE'S THEOREM FOR LPDO WITH CONSTANT COEFFICIENTS
Institute of Scientific and Technical Information of China (English)
Han Yazhou; Luo Xuebo
2005-01-01
In this note, the authors consider a class of linear partial differential operators P(θ) with constant coefficients and prove that the operator P(θ) has Liouville property if and only if the polynomial P(iξ) doesn't have roots in Rn\\{O}.
Hamiltonian constants for several new entire solutions
Institute of Scientific and Technical Information of China (English)
2008-01-01
Using the Hamiltonian identities and the corresponding Hamilto- nian constants for entire solutions of elliptic partial differential equations, we investigate several new entire solutions whose existence were shown recently, and show interesting properties of the solutions such as formulas for contact angles at infinity of concentration curves.
Early publications about nonzero cosmological constant
Horvath, I
2012-01-01
In 2011 the Nobel Prize in Physics was awarded for the 1998 discovery of the nonzero cosmological constant. This discovery is very important and surely worth to receive the Nobel Prize. However, years earlier several papers had been published (Paal, Horvath, & Lukacs 1992; Holba et al. 1992, Holba et al. 1994) about a very similar discovery from observational data.
Timelike Constant Mean Curvature Surfaces with Singularities
DEFF Research Database (Denmark)
Brander, David; Svensson, Martin
2014-01-01
We use integrable systems techniques to study the singularities of timelike non-minimal constant mean curvature (CMC) surfaces in the Lorentz–Minkowski 3-space. The singularities arise at the boundary of the Birkhoff big cell of the loop group involved. We examine the behavior of the surfaces at ...
Stability constants for silicate adsorbed to ferrihydrite
DEFF Research Database (Denmark)
Hansen, Hans Christian Bruun; Wetche, T.P.; Raulund-Rasmussen, Karsten;
1994-01-01
Intrinsic surface acidity constants (K(a1)intr, K(a2)intr) and surface complexation constant for adsorption of orthosilicate onto synthetic ferrihydrite (K(Si) for the complex = FeOSi(OH)3) have been determined from acid/base titrations in 0.001-0.1 m NaClO4 electrolytes and silicate adsorption...... experiments in 0.01 m NaNO3 electrolyte (pH 3-6). The surface equilibrium constants were calculated according to the two-layer model by Dzombak & Morel (1990). Near equilibrium between protons/hydroxyls in solution and the ferrihydrite surface was obtained within minutes while equilibration with silicate...... required days-weeks, both reactions probably being diffusion controlled. Applying the values for specific surface area and site densities for ferrihydrite used by Dzombak & Morel (1990) (600 m2 g-1, 3.4 mumole m-2) the constants pK(al)intr 6.93 +/- 0.12, pK(a2)intr = 8.72 +/- 0.17 and log K(Si) = 3.62 were...
Pion decay constants in dense skyrmion matter
Directory of Open Access Journals (Sweden)
Lee H.-J.
2010-10-01
Full Text Available According to the QCD, the hadronic matter can have various phases with matter density and temperature. In general, when there is phase transition in a matter, it is known that a symmetry in the matter changes. In case of the hadronic matter, the chiral symmetry in the matter is expected to be restored when the matter density (or temperature increases. The actual order parameter with respect to the chiral symmetry in the hadronic matter is known as the quark condensate from the QCD, but the pion decay constant, corresponding to the radius of the chiral circle, plays the role of the order parameter in an eﬀective ﬁeld theoretical approach to the QCD. In this paper, by using the skyrmion model which is an eﬀective theory to the QCD, we construct the skyrmion matter as a model of the hadronic matter (nuclear matter and calculate the pion decay constant in the matter. Because of presence of the matter, the pion decay constant is split into the two components, the temporal component and the spatial component. We discuss the phase transition in the skyrmion matter and behavior of the two components of the decay constant for massless pion with density of the skyrmion matter.
Variation of the fine structure constant
Lipovka, Anton A
2016-01-01
In present paper we evaluate the fine structure constant variation which should take place as the Universe is expanded and its curvature is changed adiabatically. This changing of the fine structure constant is attributed to the energy lost by physical system (consist of baryonic component and electromagnetic field) due to expansion of our Universe. Obtained ratio (d alpha)/alpha = 1. 10{-18} (per second) is only five times smaller than actually reported experimental limit on this value. For this reason this variation can probably be measured within a couple of years. To argue the correctness of our approach we calculate the Planck constant as adiabatic invariant of electromagnetic field, from geometry of our Universe in the framework of the pseudo- Riemannian geometry. Finally we discuss the double clock experiment based on Al+ and Hg+ clocks carried out by T. Rosenband et al. (Science 2008). We show that in this particular case there is an error in method and this way the fine structure constant variation c...
Limitations of constant-force-feedback experiments.
Elms, Phillip J; Chodera, John D; Bustamante, Carlos J; Marqusee, Susan
2012-10-03
Single-molecule force spectroscopy has provided important insights into the properties and mechanisms of biological molecules and systems. A common experiment is to measure the force dependence of conformational changes at equilibrium. Here, we demonstrate that the commonly used technique of force feedback has severe limitations when used to evaluate rapid macromolecular conformational transitions. By comparing the force-dependent dynamics of three major classes of macromolecules (DNA, RNA, and protein) using both a constant-force-feedback and a constant-trap-position technique, we demonstrate a problem in force-feedback experiments. The finite response time of the instrument's force feedback can modify the behavior of the molecule, leading to errors in the reported parameters, such as the rate constants and the distance to the transition state, for the conformational transitions. We elucidate the causes of this problem and provide a simple test to identify and evaluate the magnitude of the effect. We recommend avoiding the use of constant force feedback as a method to study rapid conformational changes in macromolecules.
The ideal Kolmogorov inertial range and constant
Zhou, YE
1993-01-01
The energy transfer statistics measured in numerically simulated flows are found to be nearly self-similar for wavenumbers in the inertial range. Using the measured self-similar form, an 'ideal' energy transfer function and the corresponding energy flux rate were deduced. From this flux rate, the Kolmogorov constant was calculated to be 1.5, in excellent agreement with experiments.
Monopoly price discrimination with constant elasticity demand
Aguirre Pérez, Iñaki; Cowan, Simon George
2013-01-01
This paper presents new results on the welfare e¤ects of third-degree price discrimination under constant elasticity demand. We show that when both the share of the strong market under uniform pricing and the elasticity di¤erence between markets are high enough,then price discrimination not only can increase social welfare but also consumer surplus.
The Elastic Constants for Wrought Aluminum Alloys
Templin, R L; Hartmann, E C
1945-01-01
There are several constants which have been devised as numerical representations of the behavior of metals under the action of loadings which stress the metal within the range of elastic action. Some of these constants, such as Young's modulus of elasticity in tension and compression, shearing modulus of elasticity, and Poisson's ratio, are regularly used in engineering calculations. Precise tests and experience indicate that these elastic constants are practically unaffected by many of the factors which influence the other mechanical properties of materials and that a few careful determinations under properly controlled conditions are more useful and reliable than many determinations made under less favorable conditions. It is the purpose of this paper to outline the methods employed by the Aluminum Research Laboratories for the determination of some of these elastic constants, to list the values that have been determined for some of the wrought aluminum alloys, and to indicate the variations in the values that may be expected for some of the commercial products of these alloys.
Supersymmetry Breaking and the Cosmological Constant
Banks, T
2014-01-01
I review three attempts to explain the small value of the cosmological constant, and their connection to SUSY breaking. They are The String Landscape, Supersymmetric Large Extra Dimensions (SLED), and the Holographic Space-time Formalism invented by Fischler and myself.
When is the growth index constant?
Polarski, David; Starobinsky, Alexei A.; Giacomini, Hector
2016-12-01
The growth index γ is an interesting tool to assess the phenomenology of dark energy (DE) models, in particular of those beyond general relativity (GR). We investigate the possibility for DE models to allow for a constant γ during the entire matter and DE dominated stages. It is shown that if DE is described by quintessence (a scalar field minimally coupled to gravity), this behaviour of γ is excluded either because it would require a transition to a phantom behaviour at some finite moment of time, or, in the case of tracking DE at the matter dominated stage, because the relative matter density Ωm appears to be too small. An infinite number of solutions, with Ωm and γ both constant, are found with wDE = 0 corresponding to Einstein-de Sitter universes. For all modified gravity DE models satisfying Geff >= G, among them the f(R) DE models suggested in the literature, the condition to have a constant wDE is strongly violated at the present epoch. In contrast, DE tracking dust-like matter deep in the matter era, but with Ωm G and an example is given using scalar-tensor gravity for a range of admissible values of γ. For constant wDE inside GR, departure from a quasi-constant value is limited until today. Even a large variation of wDE may not result in a clear signature in the change of γ. The change however is substantial in the future and the asymptotic value of γ is found while its slope with respect to Ωm (and with respect to z) diverges and tends to ‑∞.
Turner, Monica L; Steidel, Charles C; Rudie, Gwen C; Strom, Allison L
2014-01-01
We use quasar absorption lines to study the physical conditions in the circumgalactic medium of redshift $z\\approx 2.3$ star-forming galaxies taken from the Keck Baryonic Structure Survey (KBSS). In Turner et al. 2014 we used the pixel optical depth technique to show that absorption by HI and the metal ions OVI, NV, CIV, CIII and SiIV is strongly enhanced within $|\\Delta v|\\lesssim170$ km/s and projected distances $|d|\\lesssim180$ proper kpc from sightlines to the background quasars. Here we demonstrate that the OVI absorption is also strongly enhanced at fixed HI, CIV, and SiIV optical depths, and that this enhancement extends out to $\\sim350$ km/s. At fixed HI the increase in the median OVI optical depth near galaxies is 0.3-0.7 dex and is detected at 2--3-$\\sigma$ confidence for all seven HI bins that have $\\log_{10}\\tau_{\\rm HI}\\ge-1.5$. We use ionisation models to show that the observed strength of OVI as a function of HI is consistent with enriched, photoionised gas for pixels with $\\tau_{\\rm HI}\\gtrsim...
Nomura, K; Robledo, L M
2016-01-01
The structure of even-even neutron-rich Ru, Mo, Zr and Sr nuclei in the $A\\approx 100$ mass region is studied within the interacting boson model (IBM) with microscopic input from the self-consistent mean-field approximation based on the Gogny-D1M energy density functional. The deformation energy surface in the quadrupole deformation space $(\\beta,\\gamma)$, computed within the constrained Hartree-Fock-Bogoliubov framework, is mapped onto the expectation value of the appropriately chosen IBM Hamiltonian with configuration mixing in the boson condensate state. The mapped IBM Hamiltonian is used to study the spectroscopic properties of $^{98-114}$Ru, $^{96-112}$Mo, $^{94-110}$Zr and $^{92-108}$Sr. Several cases of $\\gamma$-soft behavior are predicted in Ru and Mo nuclei while a pronounced coexistence between strongly-prolate and weakly-oblate deformed shapes is found for Zr and Sr nuclei. The method describes well the evolution of experimental yrast and non-yrast states as well as selected $B$(E2) transition prob...
Constraints on the Nucleon Strange Form Factors at Q{sup 2} {approx} 0.1 GeV{sup 2}
Energy Technology Data Exchange (ETDEWEB)
K.A. Aniol; D.S. Armstrong; T. Averett; H. Benaoum; P.Y. Bertin; E. Burtin; J. Cahoon; G.D. Cates; C.C. Chang; Y.-C. Chao; J.-P. Chen; Seonho Choi; E. Chudakov; B. Craver; F. Cusanno; Piotr Decowski; D. Deepa; C. FERDI; R.J. Feuerbach; J.M. Finn; S. Frullani; K. Fuoti; F. Garibaldi; R. Gilman; A. Glamazdin; V. Gorbenko; J.M. Grames; J. Hansknecht; D.W. Higinbotham; R. Holmes; T. Holmstrom; T.B. Humensky; H. Ibrahim; C.W. de Jager; X. Jiang; L.J. Kaufman; A. Kelleher; A. Kolarkar; S. Kowalski; K.S. Kumar; D. Lambert; P. LaViolette; J. LeRose; D. Lhuillier; N. Liyanage; M. Mazouz; K. McCormick; D.G. Meekins; Z.-E. Meziani; R. Michaels; B. Moffit; P. Monaghan; C. Munoz-Camacho; S. Nanda; V. Nelyubin; D. Neyret; K.D. Paschke; M. Poelker; R. Pomatsalyuk; Y. Qiang; B. Reitz; J. Roche; A. Saha; J. Singh; R. Snyder; P.A. Souder; R. Subedi; R. Suleiman; V. Sulkosky; W.A. Tobias; G.M. Urciuoli; A. Vacheret; E. Voutier; K. Wang; R. Wilson; B. Wojtsekhowski; X. Zheng
2005-06-01
We report the most precise measurement to date of a parity-violating asymmetry in elastic electron-proton scattering. The measurement was carried out with a beam energy of 3.03 GeV and a scattering angle <{theta}{sub lab}> = 6.0 degrees, with the result A{sub PV} = -1.14 {+-} 0.24 (stat) {+-} 0.06 (syst) parts per million. From this we extract, at Q{sup 2} = 0.099 GeV{sup 2}, the strange form factor combination G{sub E}{sup s} + 0.080 G{sub M}{sup s} = 0.030 {+-} 0.025 (stat) {+-} 0.006 (syst) {+-} 0.012 (FF) where the first two errors are experimental and the last error is due to the uncertainty in the neutron electromagnetic form factor. The measurement significantly improves existing constraints on G{sub E}{sup s} and G{sub M}{sup s} at Q{sup 2} {approx}0.1 GeV{sup 2}. A consistent picture emerges from all measurements at this Q{sup 2}. A combined fit shows that G{sub E}{sup s} is consistent with zero while G{sub M}{sup s} prefers positive values though G{sub E}{sup s} = G{sub M}{sup s} = 0 is compatible with the data at 95% C.L.
Energy Technology Data Exchange (ETDEWEB)
Urbano, R.R. [Instituto de Fisica ' Gleb Wataghin' , Universidade Estadual de Campinas, Cidade Universitaria ' Zaferino Vaz' , UNICAMP, CP 6165, Campinas 13083-970 (Brazil)]. E-mail: urbano@ifi.unicamp.br; Pagliuso, P.G. [Instituto de Fisica ' Gleb Wataghin' , Universidade Estadual de Campinas, Cidade Universitaria ' Zaferino Vaz' , UNICAMP, CP 6165, Campinas 13083-970 (Brazil); Rettori, C. [Instituto de Fisica ' Gleb Wataghin' , Universidade Estadual de Campinas, Cidade Universitaria ' Zaferino Vaz' , UNICAMP, CP 6165, Campinas 13083-970 (Brazil); Oseroff, S.B. [San Diego State University, San Diego, CA 92182 (United States); Sarrao, J.L. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Schlottmann, P. [National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 2310 (United States); Fisk, Z. [National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 2310 (United States)
2004-12-31
The spin-flip scattering (SFS) between conduction and Eu2+4f7 (S7/28) electrons in the paramagnetic phase of EuB6 (T>=TC{approx}15K) is studied by electron spin resonance (ESR) and magneto-resistance (MR) experiments. The observed Dysonian resonance suggests a metallic environment for the Eu2+ ions. ESR at high field, H-bar 12.05kG ({nu}-bar 33.9GHz), shows an anisotropic line width with cubic symmetry. ESR at low-field, 1.46kG (4.1GHz) and 3.35kG (9.5GHz), shows broader line width and smaller anisotropy than at higher field. The narrowing and anisotropy of the line width at high fields are indicative of a homogeneous resonance where the line width is mainly governed by the SFS mechanism due to the exchange interaction between Eu2+ 4f7 and conduction electrons. Besides the negative MR, we found an anisotropic MR with cubic symmetry. These results are interpreted in terms of magnetic polaron and Fermi surface effects.
Moura, Clarissa de Almeida; Lima, Jéssica Polyana da Silva; Silveira, Vanessa Augusta Magalhães; Miguel, Mário André Leocadio; Luchiari, Ana Carolina
2017-02-20
The ability to learn about the signs of variability in space and time is known as time place learning (TPL). To adjust their circadian rhythms, animals use stimuli that change regularly, such as the light-dark cycle, temperature, food availability or even social stimuli. Because light-dark cycle is the most important environmental temporal cue, we asked how a diurnal animal would perform TPL if this cue was removed. Zebrafish has been extensively studied in the chronobiology area due to it diurnal chronotype, thus, we studied the effects of constant light and constant dark on the time-place learning and activity profile in zebrafish. Our data show that while under constant light and dark condition zebrafish was not able of TPL, after 30days under the constant conditions, constant light led to higher activity level and less significant (robust) 24h rhythm.
Drag flow analysis of Oldroyd eight constant fluid
Directory of Open Access Journals (Sweden)
A.M. Siddiqui
2016-09-01
Full Text Available This article presents the steady drag flow problems. The incompressible Oldroyd eight constant fluid flow is considered between two infinite parallel plates. Three flow problems including the Couette flow, Poiseuille flow and Couette–Poiseuille flow are modeled. The source term appearing in the nonlinear differential equation for each case is simplified with the application of modified homotopy perturbation method, and thus the general solution is obtained. The validity of second order approximate analytic solutions is tested with the aid of a numerical technique. The order of accuracy has been obtained in tabular form and the graphs are presented to demonstrate the difference between the three flow regimes.
Reaction rate constant for radiative association of CF{sup +}
Energy Technology Data Exchange (ETDEWEB)
Öström, Jonatan, E-mail: jonatan.ostrom@gmail.com; Gustafsson, Magnus, E-mail: magnus.gustafsson@ltu.se [Applied Physics, Division of Materials Science, Department of Engineering Science and Mathematics, Luleå University of Technology, 97187 Luleå (Sweden); Bezrukov, Dmitry S. [Department of Chemistry, M. V. Lomonosov Moscow State University, Moscow, 119991 (Russian Federation); Nyman, Gunnar [Department of Chemistry and Molecular Biology, University of Gothenburg, 41296 Gothenburg (Sweden)
2016-01-28
Reaction rate constants and cross sections are computed for the radiative association of carbon cations (C{sup +}) and fluorine atoms (F) in their ground states. We consider reactions through the electronic transition 1{sup 1}Π → X{sup 1}Σ{sup +} and rovibrational transitions on the X{sup 1}Σ{sup +} and a{sup 3}Π potentials. Semiclassical and classical methods are used for the direct contribution and Breit–Wigner theory for the resonance contribution. Quantum mechanical perturbation theory is used for comparison. A modified formulation of the classical method applicable to permanent dipoles of unequally charged reactants is implemented. The total rate constant is fitted to the Arrhenius–Kooij formula in five temperature intervals with a relative difference of <3%. The fit parameters will be added to the online database KIDA. For a temperature of 10–250 K, the rate constant is about 10{sup −21} cm{sup 3} s{sup −1}, rising toward 10{sup −16} cm{sup 3} s{sup −1} for a temperature of 30 000 K.
Diffusion Monte Carlo methods applied to Hamaker Constant evaluations
Hongo, Kenta
2016-01-01
We applied diffusion Monte Carlo (DMC) methods to evaluate Hamaker constants of liquids for wettabilities, with practical size of a liquid molecule, Si$_6$H$_{12}$ (cyclohexasilane). The evaluated constant would be justified in the sense that it lies within the expected dependence on molecular weights among similar kinds of molecules, though there is no reference experimental values available for this molecule. Comparing the DMC with vdW-DFT evaluations, we clarified that some of the vdW-DFT evaluations could not describe correct asymptotic decays and hence Hamaker constants even though they gave reasonable binding lengths and energies, and vice versa for the rest of vdW-DFTs. We also found the advantage of DMC for this practical purpose over CCSD(T) because of the large amount of BSSE/CBS corrections required for the latter under the limitation of basis set size applicable to the practical size of a liquid molecule, while the former is free from such limitations to the extent that only the nodal structure of...
Reaction Rate Constant for Radiative Association of CF$^+$
Öström, Jonatan; Nyman, Gunnar; Gustafsson, Magnus
2015-01-01
Reaction rate constants and cross sections are computed for the radiative association of carbon cations ($\\text{C}^+$) and fluorine atoms ($\\text{F}$) in their ground states. We consider reactions through the electronic transition $1^1\\Pi \\rightarrow X^1\\Sigma^+$ and rovibrational transitions on the $X^1\\Sigma^+$ and $a^3\\Pi$ potentials. Semiclassical and classical methods are used for the direct contribution and Breit--Wigner theory for the resonance contribution. Quantum mechanical perturbation theory is used for comparison. A modified formulation of the classical method applicable to permanent dipoles of unequally charged reactants is implemented. The total rate constant is fitted to the Arrhenius--Kooij formula in five temperature intervals with a relative difference of $<3\\:\\%$. The fit parameters will be added to the online database KIDA. For a temperature of $10$ to $250\\:\\text{K}$, the rate constant is about $10^{-21}\\:\\text{cm}^3\\text{s}^{-1}$, rising toward $10^{-16}\\:\\text{cm}^3\\text{s}^{-1}$ fo...
Frequency Dependence of Attenuation Constant of Dielectric Materials
Directory of Open Access Journals (Sweden)
A. S. Zadgaonkar
1975-01-01
Full Text Available Different dielectric materials have been studied for frequency dependence of attenuation constant. The sensitive cathode ray oscillograph method has been used to evaluate to the dielectric constant and loss factor, and from these attenuation constants have been calculated. The temperature remaining constant, a regular increase has been observed in attenuation constant, at higher frequencies of electro-magnetic propagating wave.
Quantum Exclusion of Positive Cosmological Constant?
Dvali, Gia
2014-01-01
We show that a positive cosmological constant is incompatible with the quantum-corpuscular resolution of de Sitter metric in form of a coherent state. The reason is very general and is due to the quantum self-destruction of the coherent state because of the scattering of constituent graviton quanta. This process creates an irreversible quantum clock, which precludes eternal de Sitter. It also eliminates the possibility of Boltzmann brains and Poincare recurrences. This effect is expected to be part of any microscopic theory that takes into account the quantum corpuscular structure of the cosmological background. This observation puts the cosmological constant problem in a very different light, promoting it, from a naturalness problem, into a question of quantum consistency. We are learning that quantum gravity cannot tolerate exceedingly-classical sources.
Some Dynamical Effects of the Cosmological Constant
Axenides, M.; Floratos, E. G.; Perivolaropoulos, L.
Newton's law gets modified in the presence of a cosmological constant by a small repulsive term (antigravity) that is proportional to the distance. Assuming a value of the cosmological constant consistent with the recent SnIa data (Λ~=10-52 m-2), we investigate the significance of this term on various astrophysical scales. We find that on galactic scales or smaller (less than a few tens of kpc), the dynamical effects of the vacuum energy are negligible by several orders of magnitude. On scales of 1 Mpc or larger however we find that the vacuum energy can significantly affect the dynamics. For example we show that the velocity data in the local group of galaxies correspond to galactic masses increased by 35% in the presence of vacuum energy. The effect is even more important on larger low density systems like clusters of galaxies or superclusters.
The Cosmological Constant in the Quantum Multiverse
Larsen, Grant; Roberts, H L L
2011-01-01
Recently, a new framework for describing the multiverse has been proposed which is based on the principles of quantum mechanics. The framework allows for well-defined predictions, both regarding global properties of the universe and outcomes of particular experiments, according to a single probability formula. This provides complete unification of the eternally inflating multiverse and many worlds in quantum mechanics. In this paper we elucidate how cosmological parameters can be calculated in this framework, and study the probability distribution for the value of the cosmological constant. We consider both positive and negative values, and find that the observed value is consistent with the calculated distribution at an order of magnitude level. In particular, in contrast to the case of earlier measure proposals, our framework prefers a positive cosmological constant over a negative one. These results depend only moderately on how we model galaxy formation and life evolution therein.
Lectures on the Cosmological Constant Problem
Padilla, Antonio
2015-01-01
These lectures on the cosmological constant problem were prepared for the X Mexican School on Gravitation and Mathematical Physics. The problem itself is explained in detail, emphasising the importance of radiative instability and the need to repeatedly fine tune as we change our effective description. Weinberg's no go theorem is worked through in detail. I review a number of proposals including Linde's universe multiplication, Coleman's wormholes, the fat graviton, and SLED, to name a few. Large distance modifications of gravity are also discussed, with causality considerations pointing towards a global modification as being the most sensible option. The global nature of the cosmological constant problem is also emphasized, and as a result, the sequestering scenario is reviewed in some detail, demonstrating the cancellation of the Standard Model vacuum energy through a global modification of General Relativity.
Incompressible flows with piecewise constant density
Danchin, Raphaël
2012-01-01
We investigate the incompressible Navier-Stokes equations with variable density. The aim is to prove existence and uniqueness results in the case of discontinuous ini- tial density. In dimension n = 2, 3, assuming only that the initial density is bounded and bounded away from zero, and that the initial velocity is smooth enough, we get the local-in-time existence of unique solutions. Uniqueness holds in any dimension and for a wider class of velocity fields. Let us emphasize that all those results are true for piecewise constant densities with arbitrarily large jumps. Global results are established in dimension two if the density is close enough to a positive constant, and in n-dimension if, in addition, the initial velocity is small. The Lagrangian formula- tion for describing the flow plays a key role in the analysis that is proposed in the present paper.
Mechanism for a Decaying Cosmological Constant
Bisabr, Y
2002-01-01
A mechanism is introduced to reduce a large cosmological constant to a sufficiently small value consistent with observational upper limit. The basic ingradient in this mechanism is a distinction which has been made between the two unit systems used on cosmology and particle physics. We have used a conformal invariant gravitational model to define a particular conformal frame in terms of the large scale properties of the universe. It is then argued that the contributions of mass scales in particle physics to the vacuum energy density should be considered in a different conformal frame. In this manner a cancellation mechanism is presented in which the conformal factor plays a key role to relax the large effective cosmological constant.
Fat Euclidean Gravity with Small Cosmological Constant
Sundrum, Raman
2003-01-01
The cosmological constant problem is usually considered an inevitable feature of any effective theory capturing well-tested gravitational and matter physics, without regard to the details of short-distance gravitational couplings. In this paper, a subtle effective description avoiding the problem is presented in a first quantized language, consistent with experiments and the Equivalence Principle. First quantization allows a minimal domain of validity to be carved out by cutting on the proper length of particle worldlines. This is facilitated by working in (locally) Euclidean spacetime, although considerations of unitarity are still addressed by analytic continuation from Lorentzian spacetime. The new effective description demonstrates that the cosmological constant problem {\\it is} sensitive to short-distance details of gravity, which can be probed experimentally. ``Fat Gravity'' toy models are presented, illustrating how gravity might shut off at short but testable distances, in a generally covariant manner...
Negative Energy Cosmology and the Cosmological Constant
Prokopec, Tomislav
2011-01-01
It is well known that string theories naturally compactify on anti-de Sitter spaces, and yet cosmological observations show no evidence of a negative cosmological constant in the early Universe's evolution. In this letter we present two simple nonlocal modifications of the standard Friedmann cosmology that can lead to observationally viable cosmologies with an initial (negative) cosmological constant. The nonlocal operators we include are toy models for the quantum cosmological backreaction. In Model I an initial quasiperiodic oscillatory epoch is followed by inflation and a late time matter era, representing a dark matter candidate. The backreaction in Model II quickly compensates the negative cosmological term such that the Ricci curvature scalar rapidly approaches zero, and the Universe ends up in a late time radiation era.
Regular Black Holes with Cosmological Constant
Institute of Scientific and Technical Information of China (English)
MO Wen-Juan; CAI Rong-Gen; SU Ru-Keng
2006-01-01
We present a class of regular black holes with cosmological constant Λ in nonlinear electrodynamics. Instead of usual singularity behind black hole horizon, all fields and curvature invariants are regular everywhere for the regular black holes. Through gauge invariant approach, the linearly dynamical stability of the regular black hole is studied. In odd-parity sector, we find that the Λ term does not appear in the master equations of perturbations, which shows that the regular black hole is stable under odd-parity perturbations. On the other hand, for the even-parity sector, the master equations are more complicated than the case without the cosmological constant. We obtain the sufficient conditions for stability of the regular black hole. We also investigate the thermodynamic properties of the regular black hole, and find that those thermodynamic quantities do not satisfy the differential form of first law of black hole thermodynamics. The reason for violating the first law is revealed.
Cosmological Constant or Variable Dark Energy?
Institute of Scientific and Technical Information of China (English)
XU Li-Xin; ZHANG Cheng-Wu; LIU Hong-Ya
2007-01-01
@@ Selection statics of the Akaike information criterion (AIC) model and the Bayesian information criterion (BIC)model are applied to the Λ-cold dark matter (ΛCDM) cosmological model, the constant equation of state of dark energy, w =constant, and the parametrized equation of state of dark energy, w(z) = w0 + w1z/(1 + z),to determine which one is the better cosmological model to describe the evolution of the universe by combining the recent cosmic observational data including Sne Ia, the size of baryonic acoustic oscillation (BAO) peak from SDSS, the three-year WMAP CMB shift parameter. The results show that AIC, BIC and current datasets are not powerful enough to discriminate one model from the others, though odds suggest differences between them.
Hyperscaling violation and the shear diffusion constant
Kolekar, Kedar S.; Mukherjee, Debangshu; Narayan, K.
2016-09-01
We consider holographic theories in bulk (d + 1)-dimensions with Lifshitz and hyperscaling violating exponents z , θ at finite temperature. By studying shear gravitational modes in the near-horizon region given certain self-consistent approximations, we obtain the corresponding shear diffusion constant on an appropriately defined stretched horizon, adapting the analysis of Kovtun, Son and Starinets. For generic exponents with d - z - θ > - 1, we find that the diffusion constant has power law scaling with the temperature, motivating us to guess a universal relation for the viscosity bound. When the exponents satisfy d - z - θ = - 1, we find logarithmic behaviour. This relation is equivalent to z = 2 +deff where deff =di - θ is the effective boundary spatial dimension (and di = d - 1 the actual spatial dimension). It is satisfied by the exponents in hyperscaling violating theories arising from null reductions of highly boosted black branes, and we comment on the corresponding analysis in that context.
Pole placement with constant gain output feedback
Sridhar, B.; Lindorff, D. P.
1972-01-01
Given a linear time invariant multivariable system with m inputs and p outputs, it was shown that p closed loop poles of the system can be preassigned arbitrarily using constant gain output feedback provided (A circumflex, B circumflex) is controllable. These data show that if (A circumflex, B circumflex, C circumflex) is controllable and observable, and Rank B circumflex = m, Rank C circumflex = p, then max (m,p) poles of the system can be assigned arbitarily using constant gain output feedback. Further, it is shown that in some cases more than max (m,p) poles can be arbitrarily assigned. A least square design technique is outlined to approximate the desired pole locations when it is not possible to place all the poles.
Constant envelope chirped OFDM power efficiency
Dida, Mussa A.; Hao, Huan; Anjum, M. R.; Ran, Tao
2016-10-01
Fractional Fourier OFDM or simply chirped OFDM performs better in time-frequency selective channel than its convectional OFDM. Although chirped OFDM outperforms OFDM it still inherits Peak to Average Power Ratio (PAPR) drawback as a convectional OFDM. To eliminate PAPR drawback Constant Envelope OFDM was developed and for better performance in time frequency selective channel Constant Envelope Fractional Fourier OFDM (CE-COFDM) is used. Its BER performance is analyzed and compared to chirped OFDM and OFDM in AWGN and Rayleigh channel. The simulations show the BER performance of CE-COFDM is the same as chirped OFDM and OFDM. The power efficiency of CE-COFDM is also studied and different simulations performed shows CE-COFDM is more power efficient than chirped OFDM and convectional OFDM for class A and class B Linear Power Amplifier (LPA).
Daylight calculations using constant luminance curves
Energy Technology Data Exchange (ETDEWEB)
Betman, E. [CRICYT, Mendoza (Argentina). Laboratorio de Ambiente Humano y Vivienda
2005-02-01
This paper presents a simple method to manually estimate daylight availability and to make daylight calculations using constant luminance curves calculated with local illuminance and irradiance data and the all-weather model for sky luminance distribution developed in the Atmospheric Science Research Center of the University of New York (ARSC) by Richard Perez et al. Work with constant luminance curves has the advantage that daylight calculations include the problem's directionality and preserve the information of the luminous climate of the place. This permits accurate knowledge of the resource and a strong basis to establish conclusions concerning topics related to the energy efficiency and comfort in buildings. The characteristics of the proposed method are compared with the method that uses the daylight factor. (author)
Axionic Band Structure of the Cosmological Constant
Bachlechner, Thomas C.
2015-01-01
We argue that theories with multiple axions generically contain a large number of vacua that can account for the smallness of the cosmological constant. In a theory with N axions, the dominant instantons with charges Q determine the discrete symmetry of vacua. Subleading instantons break the leading periodicity and lift the vacuum degeneracy. For generic integer charges the number of distinct vacua is given by |det(Q)|~exp(N). Our construction motivates the existence of a landscape with a vas...
Noteworthy dimensionless constant in gravitation theory
Energy Technology Data Exchange (ETDEWEB)
Fayos, F.; Lobo, J.A.; Llanta, E.
1986-01-01
A simple problem of gravitation is studied classically and in the Schwarzchild framework. A relationship is found between the parameters that define the trajectories of two particles (the first in radial motion and the second in a circular orbit) which are initially together and meet again after one revolution of particle 2. Dimensional analysis is the clue to explain the appearance of a dimensionless constant in the Newtonian case.
Chiral Heterotic Strings with Positive Cosmological Constant
Florakis, Ioannis
2016-01-01
We present explicit examples of semi-realistic heterotic models with spontaneously broken supersymmetry, which dynamically lead to breaking scales much smaller than $M_{\\rm Planck}$ and exponentially small positive values for the cosmological constant. Contrary to field theoretic intuition, we find that the global structure of the effective potential is significantly affected by contributions of massive and non-level matched string states and we investigate the conditions that dynamically ensure a number of desired properties.
String coupling constant seems to be 1
Yoon, Youngsub
2016-01-01
We present a reasoning that the string coupling constant should be 1 from the assumption that the area spectrum derived from loop quantum gravity must be equal to the area spectrum calculated from "stringy differential geometry." To this end, we will use the loop quantum gravity area spectrum constructions proposed by Brian Kong and us, and stringy differential geometry based on double field theory recently proposed by Imtak Jeon, Kanghoon Lee and Jeong-Hyuck Park.
Physical Basis for a Constant Lag Time
Socrates, Aristotle
2012-01-01
We show that the constant time lag prescription for tidal dissipation follows directly from the equations of motion of a tidally-forced fluid body, given some basic assumptions. They are (i) the equilibrium structure of the forced body is spherically-symmetric (ii) the tidal forcing is weak and non-resonant (iii) dissipation is weak. The lag time is an intrinsic property of the tidally-forced body and is independent of the orbital configuration.
Chiral heterotic strings with positive cosmological constant
Florakis, Ioannis; Rizos, John
2016-12-01
We present explicit examples of semi-realistic heterotic models with spontaneously broken supersymmetry, which dynamically lead to breaking scales much smaller than MPlanck and exponentially small positive values for the cosmological constant. Contrary to field theoretic intuition, we find that the global structure of the effective potential is significantly affected by contributions of massive and non-level matched string states and we investigate the conditions that dynamically ensure a number of desired properties.
Determination of Optical Constants of Polyarylenevinylene
高田, 徳幸; 村田, 英幸; 江良, 正直; 筒井, 哲夫; 斎藤, 省吾
1991-01-01
The optical constants of an extremely thin film which are indispensable for precise evaluation of its nonlinear susceptibilities have been determined by using the Kramers-Kronig (KK) analysis of the transmittance spectrum. High quality thin films of poly (arylenevinylene) family were prepared from the soluble precursor polymers. The transmittance measurements were performed in the wavelength region from 340 to 1000 nm. KK analysis of the transmittance spectrum gave much accurate results than ...
Why all these prejudices against a constant?
Bianchi, Eugenio
2010-01-01
The expansion of the observed universe appears to be accelerating. A simple explanation of this phenomenon is provided by the non-vanishing of the cosmological constant in the Einstein equations. Arguments are commonly presented to the effect that this simple explanation is not viable or not sufficient, and therefore we are facing the "great mystery" of the "nature of a dark energy". We argue that these arguments are unconvincing, or ill-founded.
Fractional constant elasticity of variance model
Ngai Hang Chan; Chi Tim Ng
2007-01-01
This paper develops a European option pricing formula for fractional market models. Although there exist option pricing results for a fractional Black-Scholes model, they are established without accounting for stochastic volatility. In this paper, a fractional version of the Constant Elasticity of Variance (CEV) model is developed. European option pricing formula similar to that of the classical CEV model is obtained and a volatility skew pattern is revealed.
High-temperature rate constant measurements for OH+xylenes
Elwardani, Ahmed Elsaid
2015-06-01
The overall rate constants for the reactions of hydroxyl (OH) radicals with o-xylene (k 1), m-xylene (k 2), and p-xylene (k 3) were measured behind reflected shock waves over 890-1406K at pressures of 1.3-1.8atm using OH laser absorption near 306.7nm. Measurements were performed under pseudo-first-order conditions. The measured rate constants, inferred using a mechanism-fitting approach, can be expressed in Arrhenius form as:k1=2.93×1013exp(-1350.3/T)cm3mol-1s-1(890-1406K)k2=3.49×1013exp(-1449.3/T)cm3mol-1s-1(906-1391K)k3=3.5×1013exp(-1407.5/T)cm3mol-1s-1(908-1383K)This paper presents, to our knowledge, first high-temperature measurements of the rate constants of the reactions of xylene isomers with OH radicals. Low-temperature rate-constant measurements by Nicovich et al. (1981) were combined with the measurements in this study to obtain the following Arrhenius expressions, which are applicable over a wider temperature range:k1=2.64×1013exp(-1181.5/T)cm3mol-1s-1(508-1406K)k2=3.05×109exp(-400/T)cm3mol-1s-1(508-1391K)k3=3.0×109exp(-440/T)cm3mol-1s-1(526-1383K) © 2015 The Combustion Institute.
Emergent gravity in spaces of constant curvature
Alvarez, Orlando; Haddad, Matthew
2017-03-01
In physical theories where the energy (action) is localized near a submanifold of a constant curvature space, there is a universal expression for the energy (or the action). We derive a multipole expansion for the energy that has a finite number of terms, and depends on intrinsic geometric invariants of the submanifold and extrinsic invariants of the embedding of the submanifold. This is the second of a pair of articles in which we try to develop a theory of emergent gravity arising from the embedding of a submanifold into an ambient space equipped with a quantum field theory. Our theoretical method requires a generalization of a formula due to by Hermann Weyl. While the first paper discussed the framework in Euclidean (Minkowski) space, here we discuss how this framework generalizes to spaces of constant sectional curvature. We focus primarily on anti de Sitter space. We then discuss how such a theory can give rise to a cosmological constant and Planck mass that are within reasonable bounds of the experimental values.
Nonminimal coupling and the cosmological constant problem
Glavan, Dražen
2015-01-01
We consider a universe with a positive effective cosmological constant and a nonminimally coupled scalar field. When the coupling constant is negative, the scalar field exhibits linear growth at asymptotically late times, resulting in a decaying effective cosmological constant. The Hubble rate in the Jordan frame reaches a self-similar solution, $H=1/(\\epsilon t)$, where the principal slow roll parameter $\\epsilon$ depends on $\\xi$, reaching maximally $\\epsilon=2$ (radiation era scaling) in the limit when $\\xi\\rightarrow -\\infty$. Similar results are found in the Einstein frame (E), with $H_E=1/(\\epsilon_E t)$, but now $\\epsilon_E \\rightarrow 4/3$ as $\\xi\\rightarrow -\\infty$. Therefore in the presence of a nonminimally coupled scalar de Sitter is not any more an attractor, but instead (when $\\xi4/3$ at a rate $\\Gamma\\gg H$, the scaling changes to that of matter, $\\epsilon\\rightarrow \\epsilon_m$, and the energy density in the effective cosmological becomes a fixed fraction of the matter energy density, $M_{\\rm...
When is the growth index constant?
Polarski, David; Giacomini, Hector
2016-01-01
The growth index $\\gamma$ is an interesting tool to assess the phenomenology of dark energy (DE) models, in particular of those beyond general relativity (GR). We investigate the possibility for DE models to allow for a constant $\\gamma$ during the entire matter and DE dominated stages. It is shown that if DE is described by quintessence (a scalar field minimally coupled to gravity), this behaviour of $\\gamma$ is excluded either because it would require a transition to a phantom behaviour at some finite moment of time, or, in the case of tracking DE at the matter dominated stage, because the relative matter density $\\Omega_m$ appears to be too small. An infinite number of solutions, with $\\Omega_m$ and $\\gamma$ both constant, are found with $w_{DE}=0$ corresponding to Einstein-de Sitter universes. For all modified gravity DE models satisfying $G_{\\rm eff}\\ge G$, among them the $f(R)$ DE models suggested in the literature, the condition to have a constant $w_{DE}$ is strongly violated at the present epoch. In ...
Twelve Elastic Constants of Betula platyphylla Suk.
Institute of Scientific and Technical Information of China (English)
Wang Liyu; Lu Zhenyou
2004-01-01
Wood elastic constants are needed to describe the elastic behaviors of wood and be taken as an important design parameter for wood-based composite materials and structural materials. This paper clarified the relationships between compliance coefficients and engineering elastic constants combined with orthotropic properties of wood, and twelve elastic constants of Betula platyphylla Suk. were measured by electrical strain gauges. Spreading the adhesive quantity cannot be excessive or too little when the strain flakes were glued. If excessive, the glue layer was too thick which would influence the strain flakes' performance, and if too little, glues plastered were not firm, which could not accurately transmit the strain. Wood as an orthotropic material, its modulus of elasticity and poisson's ratios are related by two formulas:μij /Ei =μji /Ej and μij 0.95) between the reciprocal of elastic modulus MOE-1 and the square of the ratio of depth to length (h/l)2, which indicate that shear modulus values measured were reliable by three point bending experiment.
Time-dependent polymer rheology under constant stress and under constant shear conditions.
Lee, K. H.; Brodkey, R. S.
1971-01-01
A kinetic rate theory previously presented for describing non-Newtonian phenomena has been further modified to predict the flow behavior of viscoelastic materials under constant stress conditions. The thixotropic shear stress or shear rate is predicted by the kinetic theory, and the experimental stress or shear rate is obtained by modifying the thixotropic value by a stress or shear rate retardation term. The retardation term stems from a Maxwellian approach for stress retardation. In order to test the validity of this approach, transient and steady-state data were obtained for two solutions of polymethylmethacrylate in diethylphthalate. Both constant stress measurements and constant shear rate data were taken over a broad range.
Energy Technology Data Exchange (ETDEWEB)
Agarwal, Pankaj B., E-mail: pankaj@ceeri.ernet.i [Central Electronics Engineering Research Institute, Pilani - 333 031, (Council of Scientific and Industrial Research, Delhi) (India); Kumar, A. [Central Electronics Engineering Research Institute, Pilani - 333 031, (Council of Scientific and Industrial Research, Delhi) (India); Saravanan, R. [Vellore Institute of Technology University, Vellore - 632 014 (India); Sharma, A.K.; Shekhar, Chandra [Central Electronics Engineering Research Institute, Pilani - 333 031, (Council of Scientific and Industrial Research, Delhi) (India)
2010-11-30
Nano-arrays of bio-molecules have potential applications in many areas namely, bio-sensors, bio/molecular electronics and virus detection. Spot array, micro-contact printing and photolithography are used for micron size array fabrications while Dip-Pen Nanowriting (DPN) is employed for submicron/nano size arrays. We have fabricated nano-dots of 16-MHA (16-mercaptohexadecanoic acid) self-assembled monolayer (SAM) on gold substrate by DPN technique with different dwell time under varying relative humidity. These patterns were imaged in the same system in LFM (Lateral Force Microscopy) mode with fast scanning speed (5 Hz). The effect of humidity on size variation of nano-dots has been studied. During experiments, relative humidity (RH) was varied from 20% to 60%, while the temperature was kept constant {approx} 25 {sup o}C. The minimum measured diameter of the dot is {approx} 294 nm at RH = 20% for a dwell time of 2 s. The thickness of the 16-MHA dots, estimated in NanoRule image analysis software is {approx} 2 nm, which agrees well with the length of single MHA molecule (2.2 nm). The line profile has been used to estimate the size and thickness of dots. The obtained results will be useful in further development of nano-array based bio-sensors and bio-electronic devices.
Computing the dielectric constant of liquid water at constant dielectric displacement
Zhang, Chao
2015-01-01
The static dielectric constant of liquid water is computed using classical force field based molecular dynamics simulation at fixed electric displacement D. The method to constrain the electric displacement is the finite temperature classical variant of the constant-D method developed by Stengel, Spaldin and Vanderbilt (Nat. Phys. 2009, 5: 304). There is also a modification of this scheme imposing fixed values of the macroscopic field E. The method is applied to the popular SPC/E model of liquid water. We compare four different estimates of the dielectric constant, two obtained from fluctuations of the polarization at D = 0 and E = 0 and two from the variation of polarization with finite D and E. It is found that all four estimates agree when properly converged. The computational effort to achieve convergence varies however, with constant D calculations being substantially more efficient. We attribute this difference to the much shorter relaxation time of longitudinal polarization compared to transverse polar...
Directory of Open Access Journals (Sweden)
E. M. Karchevskii
2014-01-01
Full Text Available We present new numerical methods for the solution of inverse spectral problem to determine the dielectric constants of core and cladding in optical fibers. These methods use measurements of propagation constants. Our algorithms are based on approximate solution of a nonlinear nonselfadjoint eigenvalue problem for a system of weakly singular integral equations. We study three inverse problems and prove that they are well posed. Our numerical results indicate good accuracy of new algorithms.
Dereli, Tekin; Yetişmişoǧlu, Cem
2016-09-01
We derive the field equations for topologically massive gravity coupled with the most general quadratic curvature terms using the language of exterior differential forms and a first order constrained variational principle. We find variational field equations both in the presence and absence of torsion. We then show that spaces of constant negative curvature (i.e. the anti-de Sitter space AdS3) and constant torsion provide exact solutions.
Dereli, T
2016-01-01
We derive the field equations for topologically massive gravity coupled with the most general quadratic curvature terms using the language of exterior differential forms and a first order constrained variational principle. We find variational field equations both in the presence and absence of torsion. We then show that spaces of constant negative curvature (i.e. the anti de-Sitter space $AdS_3$) and constant torsion provide exact solutions.
CONSTANT LEVERAGE AND CONSTANT COST OF CAPITAL: A COMMON KNOWLEDGE HALF-TRUTH
Directory of Open Access Journals (Sweden)
IGNACIO VÉLEZ-PAREJA
2008-01-01
Full Text Available Un enfoque típico para valorar flujos de caja finitos es suponer que el endeudamiento es constante (generalmente como un endeudamiento objetivo o deseado y que por tanto, el costo del patrimonio, Ke y el costo promedio ponderado de capital CPPC, también son constantes. Para los flujos de caja perpetuos, y con el costo de la deuda, Kd como la tasa de descuento para el ahorro en impuestos o escudo fiscal, Ke y el CPPC aplicado al flujo de caja libre FCL son constantes si el endeudamiento es constante. Sin embargo esto no es verdad para los flujos de caja finitos. En este documento mostramos que para flujos de caja finitos, Ke y por lo tanto el CPPC dependen de la tasa de descuento que se utiliza para valorar el ahorro en impuestos, AI y según lo esperado, Ke y el CPPC no son constantes con Kd como la tasa de descuento para el ahorro en impuestos, aunque el endeudamiento sea constante. Ilustramos esta situación con un ejemplo simple. Analizamos cinco métodos: el flujo de caja descontado, FCD, usando APV, el FCD y la formulación tradicional y general del CPPC, el valor presente del flujo de caja del accionista, FCA más deuda y el flujo de caja de capital, FCC.
Localized (super)gravity and cosmological constant
Kakushadze, Zurab
2000-11-01
We consider localization of gravity in domain wall solutions of Einstein's gravity coupled to a scalar field with a generic potential. We discuss conditions on the scalar potential such that domain wall solutions are non-singular. Such solutions even exist for appropriate potentials which have no minima at all and are unbounded below. Domain walls of this type have infinite tension, while usual kink type of solutions interpolating between two AdS minima have finite tension. In the latter case the cosmological constant on the domain wall is necessarily vanishing, while in the former case it can be zero or negative. Positive cosmological constant is allowed for singular domain walls. We discuss non-trivial conditions for physically allowed singularities arising from the requirement that truncating the space at the singularities be consistent. Non-singular domain walls with infinite tension might a priori avoid recent "no-go" theorems indicating impossibility of supersymmetric embedding of kink type of domain walls in gauged supergravity. We argue that (non-singular) domain walls are stable even if they have infinite tension. This is essentially due to the fact that localization of gravity in smooth domain walls is a Higgs mechanism corresponding to a spontaneous breakdown of translational invariance. As to discontinuous domain walls arising in the presence of δ-function "brane" sources, they explicitly break translational invariance. Such solutions cannot therefore be thought of as limits of smooth domain walls. We point out that if the scalar potential has no minima and approaches finite negative values at infinity, then higher derivative terms are under control, and do not affect the cosmological constant which is vanishing for such backgrounds. Nonetheless, we also point out that higher curvature terms generically delocalize gravity, so that the desired lower-dimensional Newton's law is no longer reproduced.
Standard-model coupling constants from compositeness
Besprosvany, J
2003-01-01
A coupling-constant definition is given based on the compositeness property of some particle states with respect to the elementary states of other particles. It is applied in the context of the vector-spin-1/2-particle interaction vertices of a field theory, and the standard model. The definition reproduces Weinberg's angle in a grand-unified theory. One obtains coupling values close to the experimental ones for appropriate configurations of the standard-model vector particles, at the unification scale within grand-unified models, and at the electroweak breaking scale.
Solution strategies for constant acceleration problems
Wheaton, S. M.; Binder, P.-M.
2017-03-01
We discuss strategies for the general solution of single-step 1D constant acceleration problems. In a slightly restricted form, these problems have five variables (Δx, v 0, v, a and t) and two independent equations, so three variables must be given to solve for the other two, giving 10 cases. Instead of the haphazard solution of individual problems, we advocate teaching a strategy for tackling the entire class of problems. We enumerate the possible strategies, and present in detail one which reveals a number of interesting special cases and also allows the possibility of developing an automatic problem generator and solver.
Axionic Band Structure of the Cosmological Constant
Bachlechner, Thomas C
2015-01-01
We argue that theories with multiple axions generically contain a large number of vacua that can account for the smallness of the cosmological constant. In a theory with N axions, the dominant instantons with charges Q determine the discrete symmetry of vacua. Subleading instantons break the leading periodicity and lift the vacuum degeneracy. For generic integer charges the number of distinct vacua is given by |det(Q)|~exp(N). Our construction motivates the existence of a landscape with a vast number of vacua in a large class of four-dimensional effective theories.
Axionic band structure of the cosmological constant
Bachlechner, Thomas C.
2016-01-01
We argue that theories with multiple axions generically contain a large number of vacua that can account for the smallness of the cosmological constant. In a theory with N axions, the dominant instantons with charges 풬 determine the discrete symmetry of vacua. Subleading instantons break the leading periodicity and lift the vacuum degeneracy. For generic integer charges the number of distinct vacua is given by √{det (풬⊤풬 ) }∝eN. Our construction motivates the existence of a landscape with a vast number of vacua in a large class of four-dimensional effective theories.
Rugged constant-temperature thermal anemometer.
Palma, J; Labbé, R
2016-12-01
Here we report a robust thermal anemometer which can be easily built. It was conceived to measure outdoor wind speeds and for airspeed monitoring in wind tunnels and other indoor uses. It works at a constant, low temperature of approximately 90 °C, so that an independent measurement of the air temperature is required to give a correct speed reading. Despite the size and high thermal inertia of the probe, the test results show that this anemometer is capable of measuring turbulent fluctuations up to ∼100 Hz in winds of ∼14 m/s, which corresponds to a scale similar to the length of the probe.
Rugged constant-temperature thermal anemometer
Palma, J
2016-01-01
Here we report a robust thermal anemometer which can be easily built. It was conceived to measure outdoor wind speeds, and for airspeed monitoring in wind tunnels and other indoor uses. It works at a constant, low temperature of approximately 90$^\\circ$C, so that an independent measurement of the air temperature is required to give a correct speed reading. Despite the size and high thermal inertia of the probe, the test results show that this anemometer is capable of measuring turbulent fluctuations up to ~100 Hz in winds of ~14 m/s, which corresponds to a scale similar to the length of the probe.
The fine structure constant and habitable planets
DEFF Research Database (Denmark)
Sandora, McCullen
2016-01-01
© 2016 IOP Publishing Ltd and Sissa Medialab srl .We use the existence of habitable planets to impose anthropic requirements on the fine structure constant, α. To this effect, we present two considerations that restrict its value to be very near the one observed. The first, that the end product...... of stellar fusion is iron and not one of its neighboring elements, restricts α-1 to be 145± 50. The second, that radiogenic heat in the Earth's interior remains adequately productive for billions of years, restricts it to be 145±9. A connection with the grand unified theory window is discussed, effectively...
Transmission eigenvalues for operators with constant coefficients
Hitrik, Michael; Ola, Petri; Päivärinta, Lassi
2010-01-01
In this paper we study the interior transmission problem and transmission eigenvalues for multiplicative perturbations of linear partial differential operator of order $\\ge 2$ with constant real coefficients. Under suitable growth conditions on the symbol of the operator and the perturbation, we show the discreteness of the set of transmission eigenvalues and derive sufficient conditions on the existence of transmission eigenvalues. We apply these techniques to the case of the biharmonic operator and the Dirac system. In the hypoelliptic case we present a connection to scattering theory.
The Fine Structure Constant and Habitable Planets
Sandora, McCullen
2016-01-01
We use the existence of habitable planets to impose anthropic requirements on the fine structure constant, $\\alpha$. To this effect, we present two considerations that restrict its value to be very near the one observed. The first, that the end product of stellar fusion is iron and not one of its neighboring elements, restricts $\\alpha^{-1}$ to be $145\\pm 50$. The second, that radiogenic heat in the Earth's interior remains adequately productive for billions of years, restricts it to be $145\\pm9$. A connection with the grand unified theory window is discussed, effectively providing a route to probe ultra-high energy physics with upcoming advances in planetary science.
The fine structure constant and habitable planets
Sandora, McCullen
2016-08-01
We use the existence of habitable planets to impose anthropic requirements on the fine structure constant, α. To this effect, we present two considerations that restrict its value to be very near the one observed. The first, that the end product of stellar fusion is iron and not one of its neighboring elements, restricts α-1 to be 145± 50. The second, that radiogenic heat in the Earth's interior remains adequately productive for billions of years, restricts it to be 145±9. A connection with the grand unified theory window is discussed, effectively providing a route to probe ultra-high energy physics with upcoming advances in planetary science.
Scalar field collapse with negative cosmological constant
Baier, R; Stricker, S A
2014-01-01
The formation of black holes or naked singularities is studied in a model in which a homogeneous time-dependent scalar field with an exponential potential couples to four dimensional gravity with negative cosmological constant. An analytic solution is derived and its consequences are discussed. The model depends only on one free parameter which determines the equation of state and decides the fate of the spacetime. Depending on the value of this parameter the collapse ends in a black hole or a naked singularity. The latter case violates the cosmic censorship conjecture.
Information carrying capacity of a cosmological constant
Simidzija, Petar; Martín-Martínez, Eduardo
2017-01-01
We analyze the exchange of information in different cosmological backgrounds when sender and receiver are timelike separated and communicate through massless fields (without the exchange of light signals). Remarkably, we show that the dominance of a cosmological constant makes the amount of recoverable information imprinted in the field by the sender extremely resilient: it does not decay in time or with the spatial separation of the sender and receiver, and it actually increases with the rate of expansion of the Universe. This is in stark contrast with the information carried by conventional light signals and with previous results on timelike communication through massless fields in matter-dominated cosmologies.
On inflation, cosmological constant, and SUSY breaking
Linde, Andrei
2016-01-01
We consider a broad class of inflationary models of two unconstrained chiral superfields, the stabilizer $S$ and the inflaton $\\Phi$, which can describe inflationary models with nearly arbitrary potentials. These models include, in particular, the recently introduced theories of cosmological attractors, which provide an excellent fit to the latest Planck data. We show that by adding to the superpotential of the fields $S$ and $\\Phi$ a small term depending on a nilpotent chiral superfield $P$ one can break SUSY and introduce a small cosmological constant without affecting main predictions of the original inflationary scenario.
Parametrised Constants and Replication for Spatial Mobility
DEFF Research Database (Denmark)
Hüttel, Hans; Haagensen, Bjørn
2009-01-01
of reachable sites is static an encoding exists, but we also show that parametrised constants can not be encoded in the full calculus. The locality requirement supplements widely accepted encoding criteria. It appears to be a natural property in spatial calculi where links and locations can fail. The versions...... and the calculus of mobile ambients. Here, processes are located at sites and can migrate between them. In this paper we say that an encoding is local if it does not introduce extra migration. We first study this property for the distributed π-calculus where locations can be dynamically created. If the set...
TASI Lectures on the cosmological constant
Energy Technology Data Exchange (ETDEWEB)
Bousso, Raphael; Bousso, Raphael
2007-08-30
The energy density of the vacuum, Lambda, is at least 60 orders of magnitude smaller than several known contributions to it. Approaches to this problem are tightly constrained by data ranging from elementary observations to precision experiments. Absent overwhelming evidence to the contrary, dark energy can only be interpreted as vacuum energy, so the venerable assumption that Lambda=0 conflicts with observation. The possibility remains that Lambda is fundamentally variable, though constant over large spacetime regions. This can explain the observed value, but only in a theory satisfying a number of restrictive kinematic and dynamical conditions. String theory offers a concrete realization through its landscape of metastable vacua.
Timelike Constant Mean Curvature Surfaces with Singularities
DEFF Research Database (Denmark)
Brander, David; Svensson, Martin
2014-01-01
We use integrable systems techniques to study the singularities of timelike non-minimal constant mean curvature (CMC) surfaces in the Lorentz–Minkowski 3-space. The singularities arise at the boundary of the Birkhoff big cell of the loop group involved. We examine the behavior of the surfaces...... at the big cell boundary, generalize the definition of CMC surfaces to include those with finite, generic singularities, and show how to construct surfaces with prescribed singularities by solving a singular geometric Cauchy problem. The solution shows that the generic singularities of the generalized...
Finite state verifiers with constant randomness
Say, A C Cem
2011-01-01
We give a new certificate-based characterization of $\\mathsf{NL}$, as the class of languages whose members have certificates that can be verified with small error in polynomial time by probabilistic finite automata (2pfa's) which have access to only a constant number of random bits. We obtain this result by demonstrating that verifiers which are restricted to have this property are equivalent in language recognition power to multihead finite automata. The cases where the verifier is restricted in different manners in its input and certificate head movements are also examined.
Index to Constant Weight Codeword Converter
2011-03-01
1 log2i− 2 ∑n/2 i=1 log2ic+ 1. The Verilog compiler used to implement the circuits lacks the word size to compute n! for moderate n. Also, it is not...in the Verilog code. Similarly, to realize the circuits represented in Table 2, it 8 High-Speed Constant Weight Codeword Generator Table 2. Frequency...these values and printed them to a header file that was included in the Verilog code. 3 Trellis Generator 3.1 Introduction An alternative approach for
Constant force extensional rheometry of polymer solutions
DEFF Research Database (Denmark)
Szabo, Peter; McKinley, Gareth H.; Clasen, Christian
2012-01-01
We revisit the rapid stretching of a liquid filament under the action of a constant imposed tensile force, a problem which was first considered by Matta and Tytus [J. Non-Newton. Fluid Mech. 35 (1990) 215–229]. A liquid bridge formed from a viscous Newtonian fluid or from a dilute polymer solution...... is first established between two cylindrical disks. The upper disk is held fixed and may be connected to a force transducer while the lower cylinder falls due to gravity. By varying the mass of the falling cylinder and measuring its resulting acceleration, the viscoelastic nature of the elongating fluid...
Characterization of a constant current charge detector.
Mori, Masanobu; Chen, Yongjing; Ohira, Shin-Ichi; Dasgupta, Purnendu K
2012-12-15
Ion exchangers are ionic equivalents of doped semiconductors, where cations and anions are equivalents of holes and electrons as charge carriers in solid state semiconductors. We have previously demonstrated an ion exchange membrane (IEM) based electrolyte generator which behaves similar to a light-emitting diode and a charge detector (ChD) which behaves analogous to a p-i-n photodiode. The previous work on the charge detector, operated at a constant voltage, established its unique ability to respond to the charge represented by the analyte ions regardless of their redox properties, rather than to their conductivities. It also suggested that electric field induced dissociation (EFID) of water occurs at one or both ion exchange membranes. A logical extension is to study the behavior of the same device, operated in a constant current mode (ChD(i)). The evidence indicates that in the present operational mode the device also responds to the charge represented by the analytes and not their conductivity. Injection of a base into a charge detector operated in the constant voltage mode was not previously examined; in the constant current mode, base injection appears to inhibit EFID. The effects of applied current, analyte residence time and outer channel fluid composition were individually examined; analyte ions of different mobilities as well as affinities for the respective IEMs were used. While the exact behavior is somewhat dependent on the applied current, strong electrolytes, both acids and salts, respond the highest and in a near-uniform fashion, weak acids and their salts respond in an intermediate fashion and bases produce the lowest responses. A fundamentally asymmetric behavior is observed. Injected bases but not injected acids produce a poor response; the effects of incorporating a strong base as the electrolyte in the anion exchange membrane (AEM) compartment is far greater than incorporating an acid in the cation exchange membrane (CEM) compartment. These
Can the cosmological constant undergo abrupt changes?
Cabo-Montes de Oca, Alejandro; Rosabal, A; Cabo, Alejandro; Garcia-Chung, Alejandro; Rosabal, Alejandro
2005-01-01
The existence of a simple spherically symmetric and static solution of the Einstein equations in the presence of a cosmological constant vanishing outside a definite value of the radial distance is investigated. A particular succession of field configurations, which are solutions of the Einstein equations in the presence of the considered cosmological term and auxiliary external sources, is constructed. Then, it is shown that the associated succession of external sources tend to zero in the sense of the generalized functions. The type of weak solution that is found becomes the deSitter homogeneous space-time for the interior region, and the Schwartzschild space in the outside zone.
Constant-Elasticity-of-Substitution Simulation
Reiter, G.
1986-01-01
Program simulates constant elasticity-of-substitution (CES) production function. CES function used by economic analysts to examine production costs as well as uncertainties in production. User provides such input parameters as price of labor, price of capital, and dispersion levels. CES minimizes expected cost to produce capital-uncertainty pair. By varying capital-value input, one obtains series of capital-uncertainty pairs. Capital-uncertainty pairs then used to generate several cost curves. CES program menu driven and features specific print menu for examining selected output curves. Program written in BASIC for interactive execution and implemented on IBM PC-series computer.
Radiation balances and the solar constant
Crommelynck, D.
1981-01-01
The radiometric concepts are defined in order to consider various types of radiation balances and relate them to the diabetic form of the energy balance. Variability in space and time of the components of the radiation field are presented. A specific concept for sweeping which is tailored to the requirements is proposed. Finally, after establishing the truncated character of the present knowledge of the radiation balance. The results of the last observations of the solar constant are given. Ground and satellite measurement techniques are discussed.
Infrared Spectra and Optical Constants of Nitrile Ices Relevant to Titan's Atmosphere
Anderson, Carrie; Ferrante, Robert F.; Moore, W. James; Hudson, Reggie; Moore, Marla H.
2011-01-01
Spectra and optical constants of nitrile ices known or suspected to be in Titan?s atmosphere have been determined from 2.0 to 333.3 microns (approx.5000 to 30/cm). These results are relevant to the ongoing modeling of Cassini CIRS observations of Titan?s winter pole. Ices studied were: HCN, hydrogen cyanide; C2N2, cyanogen; CH3CN, acetonitrile; C2H5CN, propionitrile; and HC3N, cyanoacetylene. Optical constants were calculated, using Kramers-Kronig analysis, for each nitrile ice?s spectrum measured at a variety of temperatures, in both the amorphous- and crystalline phases. Spectra were also measured for many of the nitriles after quenching at the annealing temperature and compared with those of annealed ices. For each of these molecules we also measured the real component, n, of the refractive index for amorphous and crystalline phases at 670 nm. Several examples of the information contained in these new data sets and their usefulness in modeling Titan?s observed features will be presented (e.g., the broad emission feature at 160/cm; Anderson and Samuelson, 2011).
Energy Technology Data Exchange (ETDEWEB)
Albrand, J.P. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires
1969-07-01
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 {sup 2}J{sub P-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 {sup 2}J{sub P-C-H} values are negative. The {sup 3}J{sub H-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) [French] La non-equivalence de protons methyleniques observee dans quelques composes phosphores tricoordines et tetracoordines a apporte les resultats suivants, concernant la stereochimie et les constantes de couplage dans ces composes: dans les phosphines secondaires, la structure pyramidale des liaisons issues du phosphore est fixe a l'echelle de temps de mesure de la R.M.N.; la constante de couplage {sup 2}J{sub H-C-H}, pour un methylene en libre rotation en {alpha} d'un atome de phosphore, est negative; dans les phosphines etudiees, la non-equivalence. observee pour les protons methyleniques s'accompagne d'une difference importante (5 Hz) entre les deux constantes de couplage {sup 2}J{sub P-C-H} determinees par l'analyse; ce resultat est en accord avec la stereospecificite deja observee pour ce couplage dans les phosphines cycliques. Les valeurs observees pour {sup 2}J{sub P-C-H} dans les oxydes de phosphines sont negatives. Les valeurs de la constante de couplage {sup 3}J{sub H-P-C-H}, dans les phosphines
Analytic Continuation in the Coupling Constant Method for the Dirac Equation
Institute of Scientific and Technical Information of China (English)
张时声; 郭建友; 张双全; 孟杰
2004-01-01
On the basis of the Dirac equation, the analytic continuation in the coupling constant method is employed to investigate the energies and widths of single-particle resonant in square-well, harmonic-oscillator, and Woodsconvergent energies and widths of single-particle resonant states can be obtained, which makes the application of the analytic continuation in the coupling constant for the relativistic mean field theory possible.
Construction of Large Constant Dimension Codes With a Prescribed Minimum Distance
Kohnert, Axel
2008-01-01
In this paper we construct constant dimension space codes with prescribed minimum distance. There is an increased interest in space codes since a paper by Koetter and Kschischang were they gave an application in network coding. There is also a connection to the theory of designs over finite fields. We will modify a method of Braun, Kerber and Laue which they used for the construction of designs over finite fields to do the construction of space codes. Using this approach we found many new constant dimension spaces codes with a larger number of codewords than previously known codes. We will finally give a table of the best found constant dimension space codes.
Positive Cosmological Constant and Quantum Theory
Directory of Open Access Journals (Sweden)
Felix M. Lev
2010-11-01
Full Text Available We argue that quantum theory should proceed not from a spacetime background but from a Lie algebra, which is treated as a symmetry algebra. Then the fact that the cosmological constant is positive means not that the spacetime background is curved but that the de Sitter (dS algebra as the symmetry algebra is more relevant than the Poincare or anti de Sitter ones. The physical interpretation of irreducible representations (IRs of the dS algebra is considerably different from that for the other two algebras. One IR of the dS algebra splits into independent IRs for a particle and its antiparticle only when Poincare approximation works with a high accuracy. Only in this case additive quantum numbers such as electric, baryon and lepton charges are conserved, while at early stages of the Universe they could not be conserved. Another property of IRs of the dS algebra is that only fermions can be elementary and there can be no neutral elementary particles. The cosmological repulsion is a simple kinematical consequence of dS symmetry on quantum level when quasiclassical approximation is valid. Therefore the cosmological constant problem does not exist and there is no need to involve dark energy or other fields for explaining this phenomenon (in agreement with a similar conclusion by Bianchi and Rovelli.
Local constants of motion imply information propagation
Friesdorf, M.; Werner, A. H.; Goihl, M.; Eisert, J.; Brown, W.
2015-11-01
Interacting quantum many-body systems are expected to thermalize, in the sense that the evolution of local expectation values approaches a stationary value resembling a thermal ensemble. This intuition is notably contradicted in systems exhibiting many-body localisation (MBL). In stark contrast to the non-interacting case of Anderson localisation, the entanglement of states grows without limit over time, albeit slowly. In this work, we establish a novel link between quantum information theory and notions of condensed matter physics, capturing this phenomenon in the Heisenberg picture. We show that the mere existence of local constants of motion, often taken as the defining property of MBL, together with a generic spectrum of the Hamiltonian, is already sufficient to rigorously prove information propagation: these systems can be used to send a classical bit over arbitrary distances, in that the impact of a local perturbation can be detected arbitrarily far away. This counterintuitive result is compatible with and further corroborates the intuition of a slow entanglement growth following global quenches in MBL systems. We perform a detailed perturbation analysis of quasi-local constants of motion and also show that they indeed can be used to construct efficient spectral tensor networks, as recently suggested. Our results provide a detailed and at the same time model-independent picture of information propagation in MBL systems.
Constant domain-regulated antibody catalysis.
Sapparapu, Gopal; Planque, Stephanie; Mitsuda, Yukie; McLean, Gary; Nishiyama, Yasuhiro; Paul, Sudhir
2012-10-19
Some antibodies contain variable (V) domain catalytic sites. We report the superior amide and peptide bond-hydrolyzing activity of the same heavy and light chain V domains expressed in the IgM constant domain scaffold compared with the IgG scaffold. The superior catalytic activity of recombinant IgM was evident using two substrates, a small model peptide that is hydrolyzed without involvement of high affinity epitope binding, and HIV gp120, which is recognized specifically by noncovalent means prior to the hydrolytic reaction. The catalytic activity was inhibited by an electrophilic phosphonate diester, consistent with a nucleophilic catalytic mechanism. All 13 monoclonal IgMs tested displayed robust hydrolytic activities varying over a 91-fold range, consistent with expression of the catalytic functions at distinct levels by different V domains. The catalytic activity of polyclonal IgM was superior to polyclonal IgG from the same sera, indicating that on average IgMs express the catalytic function at levels greater than IgGs. The findings indicate a favorable effect of the remote IgM constant domain scaffold on the integrity of the V-domain catalytic site and provide a structural basis for conceiving antibody catalysis as a first line immune function expressed at high levels prior to development of mature IgG class antibodies.
Ventricular fibrillation time constant for swine.
Wu, Jiun-Yan; Nimunkar, Amit J; Sun, Hongyu; O'Rourke, Ann; Huebner, Shane; Will, James A; Webster, John G
2008-10-01
The strength-duration curve for cardiac excitation can be modeled by a parallel resistor-capacitor circuit that has a time constant. Experiments on six pigs were performed by delivering current from the X26 Taser dart at a distance from the heart to cause ventricular fibrillation (VF). The X26 Taser is an electromuscular incapacitation device (EMD), which generates about 50 kV and delivers a pulse train of about 15-19 pulses s(-1) with a pulse duration of about 150 micros and peak current about 2 A. Similarly a continuous 60 Hz alternating current of the amplitude required to cause VF was delivered from the same distance. The average current and duration of the current pulse were estimated in both sets of experiments. The strength-duration equation was solved to yield an average time constant of 2.87 ms +/- 1.90 (SD). Results obtained may help in the development of safety standards for future electromuscular incapacitation devices (EMDs) without requiring additional animal tests.
Hyperscaling violation and the shear diffusion constant
Directory of Open Access Journals (Sweden)
Kedar S. Kolekar
2016-09-01
Full Text Available We consider holographic theories in bulk (d+1-dimensions with Lifshitz and hyperscaling violating exponents z,θ at finite temperature. By studying shear gravitational modes in the near-horizon region given certain self-consistent approximations, we obtain the corresponding shear diffusion constant on an appropriately defined stretched horizon, adapting the analysis of Kovtun, Son and Starinets. For generic exponents with d−z−θ>−1, we find that the diffusion constant has power law scaling with the temperature, motivating us to guess a universal relation for the viscosity bound. When the exponents satisfy d−z−θ=−1, we find logarithmic behaviour. This relation is equivalent to z=2+deff where deff=di−θ is the effective boundary spatial dimension (and di=d−1 the actual spatial dimension. It is satisfied by the exponents in hyperscaling violating theories arising from null reductions of highly boosted black branes, and we comment on the corresponding analysis in that context.
Variation of fundamental constants: theory and observations
Flambaum, V V
2007-01-01
Review of recent works devoted to the variation of the fundamental constants is presented including atomic clocks, quasar absorption spectra, and Oklo natural nuclear reactor data. Assuming linear variation with time we can compare different results. From the quasar absorption spectra: $\\dot{\\mu}/\\mu=(1 \\pm 3) \\times 10^{-16}$ yr$^{-1}$. A combination of this result and the atomic clock results gives the best limt on variation of $\\alpha$: $\\dot{\\alpha}/\\alpha=(-0.8 \\pm 0.8) \\times 10^{-16}$ yr$^{-1}$. The Oklo natural reactor gives the best limit on the variation of $m_s/\\Lambda_{QCD}$ where $m_s$ is the strange quark mass. Huge enhancement of the relative variation effects happens in transitions between close atomic, molecular and nuclear energy levels. We suggest several new cases where the levels are very narrow. Large enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feshbach resonance. Massive bodies (stars or galaxies) can also affect physical constants....
Local Pain Dynamics during Constant Exhaustive Exercise.
Directory of Open Access Journals (Sweden)
Agne Slapsinskaite
Full Text Available The purpose of this study was to delineate the topological dynamics of pain and discomfort during constant exercise performed until volitional exhaustion. Eleven physical education students were tested while cycling and running at a "hard" intensity level (e.g., corresponding to Borg's RPE (6-20 = 15. During the tests, participants reported their discomfort and pain on a body map every 15s. "Time on task" for each participant was divided into five equal non-overlapping temporal windows within which their ratings were considered for analysis. The analyses revealed that the number of body locations with perceived pain and discomfort increased throughout the five temporal windows until reaching the mean (± SE values of 4.2 ± 0.7 and 4.1 ± 0.6 in cycling and running, respectively. The dominant locations included the quadriceps and hamstrings during cycling and quadriceps and chest during running. In conclusion, pain seemed to spread throughout the body during constant cycling and running performed up to volitional exhaustion with differences between cycling and running in the upper body but not in the lower body dynamics.
Local Pain Dynamics during Constant Exhaustive Exercise.
Slapsinskaite, Agne; Razon, Selen; Balagué Serre, Natàlia; Hristovski, Robert; Tenenbaum, Gershon
2015-01-01
The purpose of this study was to delineate the topological dynamics of pain and discomfort during constant exercise performed until volitional exhaustion. Eleven physical education students were tested while cycling and running at a "hard" intensity level (e.g., corresponding to Borg's RPE (6-20) = 15). During the tests, participants reported their discomfort and pain on a body map every 15s. "Time on task" for each participant was divided into five equal non-overlapping temporal windows within which their ratings were considered for analysis. The analyses revealed that the number of body locations with perceived pain and discomfort increased throughout the five temporal windows until reaching the mean (± SE) values of 4.2 ± 0.7 and 4.1 ± 0.6 in cycling and running, respectively. The dominant locations included the quadriceps and hamstrings during cycling and quadriceps and chest during running. In conclusion, pain seemed to spread throughout the body during constant cycling and running performed up to volitional exhaustion with differences between cycling and running in the upper body but not in the lower body dynamics.
Hyperscaling violation and the shear diffusion constant
Kolekar, Kedar S; Narayan, K
2016-01-01
We consider holographic theories in bulk $(d+1)$-dimensions with Lifshitz and hyperscaling violating exponents $z,\\theta$ at finite temperature. By studying shear gravitational modes in the near-horizon region given certain self-consistent approximations, we obtain the corresponding shear diffusion constant on an appropriately defined stretched horizon, adapting the analysis of Kovtun, Son and Starinets. For generic exponents with $d-z-\\theta>-1$, we find that the diffusion constant has power law scaling with the temperature, motivating us to guess a universal relation for the viscosity bound. When the exponents satisfy $d-z-\\theta=-1$, we find logarithmic behaviour. This relation is equivalent to $z=2+d_{eff}$ where $d_{eff}=d_i-\\theta$ is the effective boundary spatial dimension (and $d_i=d-1$ the actual spatial dimension). It is satisfied by the exponents in hyperscaling violating theories arising from null reductions of highly boosted black branes, and we comment on the corresponding analysis in that cont...
Holographic dark energy with cosmological constant
Hu, Yazhou; Li, Miao; Li, Nan; Zhang, Zhenhui
2015-08-01
Inspired by the multiverse scenario, we study a heterotic dark energy model in which there are two parts, the first being the cosmological constant and the second being the holographic dark energy, thus this model is named the ΛHDE model. By studying the ΛHDE model theoretically, we find that the parameters d and Ωhde are divided into a few domains in which the fate of the universe is quite different. We investigate dynamical behaviors of this model, and especially the future evolution of the universe. We perform fitting analysis on the cosmological parameters in the ΛHDE model by using the recent observational data. We find the model yields χ2min=426.27 when constrained by Planck+SNLS3+BAO+HST, comparable to the results of the HDE model (428.20) and the concordant ΛCDM model (431.35). At 68.3% CL, we obtain -0.07<ΩΛ0<0.68 and correspondingly 0.04<Ωhde0<0.79, implying at present there is considerable degeneracy between the holographic dark energy and cosmological constant components in the ΛHDE model.
Is cosmological constant needed in Higgs inflation?
Directory of Open Access Journals (Sweden)
Chao-Jun Feng
2014-11-01
Full Text Available The detection of B-mode shows a very powerful constraint to theoretical inflation models through the measurement of the tensor-to-scalar ratio r. Higgs boson is the most likely candidate of the inflaton field. But usually, Higgs inflation models predict a small value of r, which is not quite consistent with the recent results from BICEP2. In this paper, we explored whether a cosmological constant energy component is needed to improve the situation. And we found the answer is yes. For the so-called Higgs chaotic inflation model with a quadratic potential, it predicts r≈0.2, ns≈0.96 with e-folds number N≈56, which is large enough to overcome the problems such as the horizon problem in the Big Bang cosmology. The required energy scale of the cosmological constant is roughly Λ∼(1014 GeV2, which means a mechanism is still needed to solve the fine-tuning problem in the later time evolution of the universe, e.g. by introducing some dark energy component.
Distance constant of the Risoe cup anemometer
Energy Technology Data Exchange (ETDEWEB)
Kristensen, L.; Frost Hansen, O.
2002-04-01
The theory for cup-anemometer dynamics is presented in some detail and two methods of obtaining the distance constant . are discussed. The first method is based on wind tunnel measurements: with a constant wind speed the cup anemometer is released from a locked position of the rotor and the increasing rotation rate recorded. It is concluded that the rapid increase in rotation rate makes the method very inaccurate. The second method consists of an analysis of turbulent, atmospheric of wind speed as measured by the cup anemometer and a fast-responding sonic anemometer with a spatial eddy resolution which is significantly better than that which can be obtained by a cup anemometer. The ratio between the measured power spectra of the horizontal wind speed by the two instruments contains the necessary information for determining the response characteristics of the cup anemometer and thereby .. The conditions for this last method to be accurate are discussed. Field measurements are used to demonstrate how . is determined the Riso cup anemometer, model P2546.
Exact Values of Some Geometric Constants of Orlicz Spaces
Institute of Scientific and Technical Information of China (English)
Ya Qiang YAN
2007-01-01
We present the exact values of nonsquare constants, yon Neumann-Jordan constants, Jung constants, packing constants, weakly convergent sequence coefficients and normal structure coefficients in a class of reflexive Orlicz function spaces and sequence spaces equipped with Luxemburg norm and Orlicz norm.
Curved dilatonic brane-worlds and the cosmological constant problem
Alonso-Alberca, N; Silva, P J; Alonso-Alberca, Natxo; Janssen, Bert; Silva, Pedro J.
2000-01-01
We construct a model for dilatonic brane worlds with constant curvature on the brane, i.e. a non-zero four-dimensional cosmological constant, given in function of the dilaton coupling and the cosmological constant of the bulk. It is shown that the brane cosmological constant does not change under quantum fluctuations in the brane tension.
Search for a Variation of Fundamental Constants
Ubachs, W.
2013-06-01
Since the days of Dirac scientists have speculated about the possibility that the laws of nature, and the fundamental constants appearing in those laws, are not rock-solid and eternal but may be subject to change in time or space. Such a scenario of evolving constants might provide an answer to the deepest puzzle of contemporary science, namely why the conditions in our local Universe allow for extreme complexity: the fine-tuning problem. In the past decade it has been established that spectral lines of atoms and molecules, which can currently be measured at ever-higher accuracies, form an ideal test ground for probing drifting constants. This has brought this subject from the realm of metaphysics to that of experimental science. In particular the spectra of molecules are sensitive for probing a variation of the proton-electron mass ratio μ, either on a cosmological time scale, or on a laboratory time scale. A comparison can be made between spectra of molecular hydrogen observed in the laboratory and at a high redshift (z=2-3), using the Very Large Telescope (Paranal, Chile) and the Keck telescope (Hawaii). This puts a constraint on a varying mass ratio Δμ/μ at the 10^{-5} level. The optical work can also be extended to include CO molecules. Further a novel direction will be discussed: it was discovered that molecules exhibiting hindered internal rotation have spectral lines in the radio-spectrum that are extremely sensitive to a varying proton-electron mass ratio. Such lines in the spectrum of methanol were recently observed with the radio-telescope in Effelsberg (Germany). F. van Weerdenburg, M.T. Murphy, A.L. Malec, L. Kaper, W. Ubachs, Phys. Rev. Lett. 106, 180802 (2011). A. Malec, R. Buning, M.T. Murphy, N. Milutinovic, S.L. Ellison, J.X. Prochaska, L. Kaper, J. Tumlinson, R.F. Carswell, W. Ubachs, Mon. Not. Roy. Astron. Soc. 403, 1541 (2010). E.J. Salumbides, M.L. Niu, J. Bagdonaite, N. de Oliveira, D. Joyeux, L. Nahon, W. Ubachs, Phys. Rev. A 86, 022510
Running cosmological constant with observational tests
Geng, Chao-Qiang; Lee, Chung-Chi; Zhang, Kaituo
2016-09-01
We investigate the running cosmological constant model with dark energy linearly proportional to the Hubble parameter, Λ = σH +Λ0, in which the ΛCDM limit is recovered by taking σ = 0. We derive the linear perturbation equations of gravity under the Friedmann-Lemaïtre-Robertson-Walker cosmology, and show the power spectra of the CMB temperature and matter density distribution. By using the Markov chain Monte Carlo method, we fit the model to the current observational data and find that σH0 /Λ0 ≲ 2.63 ×10-2 and 6.74 ×10-2 for Λ (t) coupled to matter and radiation-matter, respectively, along with constraints on other cosmological parameters.
Dimensionless constants, cosmology and other dark matters
Tegmark, M; Rees, M; Wilczek, F; Tegmark, Max; Aguirre, Anthony; Rees, Martin; Wilczek, Frank
2006-01-01
We identify 31 dimensionless physical constants required by particle physics and cosmology, and emphasize that both microphysical constraints and selection effects might help elucidate their origin. Axion cosmology provides an instructive example, in which these two kinds of arguments must both be taken into account, and work well together. If a Peccei-Quinn phase transition occurred before or during inflation, then the axion dark matter density will vary from place to place with a probability distribution. By calculating the net dark matter halo formation rate as a function of all four relevant cosmological parameters and assessing other constraints, we find that this probability distribution, computed at stable solar systems, is arguably peaked near the observed dark matter density. If cosmologically relevant WIMP dark matter is discovered, then one naturally expects comparable densities of WIMPs and axions, making it important to follow up with precision measurements to determine whether WIMPs account for ...
The cosmological constant and the relaxed universe
Bauer, Florian
2010-01-01
We study the role of the cosmological constant (CC) as a component of dark energy (DE). It is argued that the cosmological term is in general unavoidable and it should not be ignored even when dynamical DE sources are considered. From the theoretical point of view quantum zero-point energy and phase transitions suggest a CC of large magnitude in contrast to its tiny observed value. Simply relieving this disaccord with a counterterm requires extreme fine-tuning which is referred to as the old CC problem. To avoid it, we discuss some recent approaches for neutralising a large CC dynamically without adding a fine-tuned counterterm. This can be realised by an effective DE component which relaxes the cosmic expansion by counteracting the effect of the large CC. Alternatively, a CC filter is constructed by modifying gravity to make it insensitive to vacuum energy.
Simple Pendulum Determination of the Gravitational Constant
Parks, Harold V.; Faller, James E.
2010-09-01
We determined the Newtonian constant of gravitation G by interferometrically measuring the change in spacing between two free-hanging pendulum masses caused by the gravitational field from large tungsten source masses. We find a value for G of (6.67234±0.00014)×10-11m3kg-1s-2. This value is in good agreement with the 1986 Committee on Data for Science and Technology (CODATA) value of (6.67259±0.00085)×10-11m3kg-1s-2 [Rev. Mod. Phys. 59, 1121 (1987)RMPHAT0034-686110.1103/RevModPhys.59.1121] but differs from some more recent determinations as well as the latest CODATA recommendation of (6.67428±0.00067)×10-11m3kg-1s-2 [Rev. Mod. Phys. 80, 633 (2008)RMPHAT0034-686110.1103/RevModPhys.80.633].
Measuring the RC time constant with Arduino
Pereira, N. S. A.
2016-11-01
In this work we use the Arduino UNO R3 open source hardware platform to assemble an experimental apparatus for the measurement of the time constant of an RC circuit. With adequate programming, the Arduino is used as a signal generator, a data acquisition system and a basic signal visualisation tool. Theoretical calculations are compared with direct observations from an analogue oscilloscope. Data processing and curve fitting is performed on a spreadsheet. The results obtained for the six RC test circuits are within the expected interval of values defined by the tolerance of the components. The hardware and software prove to be adequate to the proposed measurements and therefore adaptable to a laboratorial teaching and learning context.
Running cosmological constant with observational tests
Geng, Chao-Qiang; Zhang, Kaituo
2016-01-01
We investigate the running cosmological constant model with dark energy linearly proportional to the Hubble parameter, $\\Lambda = \\sigma H + \\Lambda_0$, in which the $\\Lambda$CDM limit is recovered by taking $\\sigma=0$. We derive the linear perturbation equations of gravity under the Friedmann-Lema\\"itre-Robertson-Walker cosmology, and show the power spectra of the CMB temperature and matter density distribution. By using the Markov chain Monte Carlo method, we fit the model to the current observational data and find that $\\sigma H_0/ \\Lambda_0 \\lesssim 2.63 \\times 10^{-2}$ and $6.74 \\times 10^{-2}$ for $\\Lambda(t)$ coupled to matter and radiation-matter, respectively, along with constraints on other cosmological parameters.
Automatic gesture analysis using constant affine velocity.
Cifuentes, Jenny; Boulanger, Pierre; Pham, Minh Tu; Moreau, Richard; Prieto, Flavio
2014-01-01
Hand human gesture recognition has been an important research topic widely studied around the world, as this field offers the ability to identify, recognize, and analyze human gestures in order to control devices or to interact with computer interfaces. In particular, in medical training, this approach is an important tool that can be used to obtain an objective evaluation of a procedure performance. In this paper, some obstetrical gestures, acquired by a forceps, were studied with the hypothesis that, as the scribbling and drawing movements, they obey the one-sixth power law, an empirical relationship which connects path curvature, torsion, and euclidean velocity. Our results show that obstetrical gestures have a constant affine velocity, which is different for each type of gesture and based on this idea this quantity is proposed as an appropriate classification feature in the hand human gesture recognition field.
Running cosmological constant with observational tests
Directory of Open Access Journals (Sweden)
Chao-Qiang Geng
2016-09-01
Full Text Available We investigate the running cosmological constant model with dark energy linearly proportional to the Hubble parameter, Λ=σH+Λ0, in which the ΛCDM limit is recovered by taking σ=0. We derive the linear perturbation equations of gravity under the Friedmann–Lemaïtre–Robertson–Walker cosmology, and show the power spectra of the CMB temperature and matter density distribution. By using the Markov chain Monte Carlo method, we fit the model to the current observational data and find that σH0/Λ0≲2.63×10−2 and 6.74×10−2 for Λ(t coupled to matter and radiation-matter, respectively, along with constraints on other cosmological parameters.
Tunelling with a negative cosmological constant
Gibbons, G W
1996-01-01
The point of this paper is see what light new results in hyperbolic geometry may throw on gravitational entropy and whether gravitational entropy is relevant for the quantum origin of the univeres. We introduce some new gravitational instantons which mediate the birth from nothing of closed universes containing wormholes and suggest that they may contribute to the density matrix of the universe. We also discuss the connection between their gravitational action and the topological and volumetric entropies introduced in hyperbolic geometry. These coincide for hyperbolic 4-manifolds, and increase with increasing topological complexity of the four manifold. We raise the questions of whether the action also increases with the topological complexity of the initial 3-geometry, measured either by its three volume or its Matveev complexity. We point out, in distinction to the non-supergravity case, that universes with domains of negative cosmological constant separated by supergravity domain walls cannot be born from ...
String Phenomenology and the Cosmological Constant
de Alwis, S P
2007-01-01
It is argued that classical string solutions should not be fine tuned to have a positive cosmological constant (CC) at the observed size, since even the quantum corrections from standard model effects will completely negate any classical string theory solution with such a CC. In fact it is even possible that there is no need at all for any ad hoc uplifting term in the potential since these quantum effects may well take care of this. Correspondingly any calculation of the parameters of the MSSM has to be rethought to take into account the evolution of the CC. This considerably complicates the issue since the initial conditions for RG evolution of these parameters are determined by the final condition on the CC! The Anthropic Principle is of no help in addressing these issues.
Higgs inflation and the cosmological constant
Energy Technology Data Exchange (ETDEWEB)
Jegerlehner, Fred [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2014-02-15
The Higgs not only induces the masses of all SM particles, the Higgs, given its special mass value, is the natural candidate for the inflaton and in fact is ruling the evolution of the early universe, by providing the necessary dark energy which remains the dominant energy density. SM running couplings not only allow us to extrapolate SM physics up to the Planck scale, but equally important they are triggering the Higgs mechanism. This is possible by the fact that the bare mass term in the Higgs potential changes sign at about μ{sub 0}≅1.40 x 10{sup 16} GeV and in the symmetric phase is enhanced by quadratic terms in the Planck mass. Such a huge Higgs mass term is able to play a key role in triggering inflation in the early universe. In this article we extend our previous investigation by working out the details of a Higgs inflation scenario. We show how different terms contributing to the Higgs Lagrangian are affecting inflation. Given the SM and its extrapolation to scales μ>μ{sub 0} we find a calculable cosmological constant V(0) which is weakly scale dependent and actually remains large during inflation. This is different to the Higgs fluctuation field dependent ΔV(φ), which decays exponentially during inflation, and actually would not provide a sufficient amount of inflation. The fluctuation field has a different effective mass which shifts the bare Higgs transition point to a lower value μ'{sub 0} ≅7.7 x 10{sup 14} GeV. The vacuum energy V(0) being proportional to M{sub Pl}{sup 4} has a coefficient which vanishes near the Higgs transition point, such that the bare and the renormalized cosmological constant match at this point. The role of the Higgs in reheating and baryogenesis is emphasized.
Bianchi Type-Ⅲ Cosmological Models with Gravitational Constant G and the Cosmological Constant Λ
Institute of Scientific and Technical Information of China (English)
J.P.Singh; R.K.Tiwari; Pratibha Shukla
2007-01-01
Einstein field equations with variable gravitational and cosmological constants are considered in the presence of perfect fluid for the Bianchi type-Ⅲ universe by assuming conservation law for the energy-momentum tensor.Exact solutions of the field equations are obtained by using the scalar of expansion proportional to the shear scalar θχσ,which leads to a relation between metric potential B=Cn,where n is a constant.The corresponding physical interpretation of the cosmological solutions are also discussed.
Infrared Spectra and Optical Constants of Elusive Amorphous Methane
Gerakines, Perry A.; Hudson, Reggie L.
2015-01-01
New and accurate laboratory results are reported for amorphous methane (CH4) ice near 10 K for the study of the interstellar medium (ISM) and the outer Solar System. Near- and mid-infrared (IR) data, including spectra, band strengths, absorption coefficients, and optical constants, are presented for the first time for this seldom-studied amorphous solid. The apparent IR band strength near 1300 cm(exp -1) (7.69 micrometer) for amorphous CH4 is found to be about 33% higher than the value long used by IR astronomers to convert spectral observations of interstellar CH4 into CH4 abundances. Although CH4 is most likely to be found in an amorphous phase in the ISM, a comparison of results from various laboratory groups shows that the earlier CH4 band strength at 1300 cm(exp -1) (7.69 micrometer) was derived from IR spectra of ices that were either partially or entirely crystalline CH4 Applications of the new amorphous-CH4 results are discussed, and all optical constants are made available in electronic form.
Proton radiation effects on optical constants of Al film reflector
Institute of Scientific and Technical Information of China (English)
Liu Hai; Wei Qiang; He Shi-Yu; Zhao Dan
2006-01-01
The Al film reflectors can yield a high-reflectance over a broad wavelength region, and have been widely used in the spacecraft optical instruments for high quality optical applications. Under the irradiation of charged particles in the Earth radiation belt, the reflectors could be deteriorated. In order to reveal the deterioration mechanism, the change in optical constants of Al film reflector induced by proton radiation with 60 keV was studied in an environment of vacuum with heat sink. Experimental results showed that when the radiation damage primarily occurs in the Al reflecting film,the extinction coefficient k will gradually decrease with increasing radiation fluence, which results in the decrease of the energies of reflective light. Therefore, the proton radiation induced an obvious degradation of spectral reflectance in the wavelength region from 200 to 800 nm on the Al film reflector.
Molecular Dynamics Simulations of Solutions at Constant Chemical Potential
Perego, Claudio; Parrinello, Michele
2015-01-01
Molecular Dynamics studies of chemical processes in solution are of great value in a wide spectrum of applications, that range from nano-technology to pharmaceutical chemistry. However, these calculations are affected by severe finite-size effects, such as the solution being depleted as the chemical process proceeds, that influence the outcome of the simulations. To overcome these limitations, one must allow the system to exchange molecules with a macroscopic reservoir, thus sampling a Grand-Canonical ensemble. Despite the fact that different remedies have been proposed, this still represents a key challenge in molecular simulations. In the present work we propose the C$\\mu$MD method, which introduces an external force that controls the environment of the chemical process of interest. This external force, drawing molecules from a finite reservoir, maintains the chemical potential constant in the region where the process takes place. We have applied the C$\\mu$MD method to the paradigmatic case of urea crystall...
Effects of constant voltage and constant current stress in PCBM:P3HT solar cells
DEFF Research Database (Denmark)
Cester, Andrea; Rizzo, Aldo; Bazzega, A.
2015-01-01
The aimof this work is the investigation of forward and reverse bias stress effects, cell self-heating and annealing in roll coated organic solar cells with PCBM:P3HT active layer. In reverse bias stress cells show a constant degradation over time. In forward current stress cells alternate degrad...
Symmetry breakdown and coupling constants of leptons
Directory of Open Access Journals (Sweden)
Gil C. Marques
2007-06-01
Full Text Available Based on a new approach to symmetries of the fundamental interactions we deal, in this paper, with the electroweak interactions of leptons. We show that the coupling constants, arising in the way leptons are coupled to intermediate bosons, can be understood as parameters associated to the breakdown of SU(2 and parity symmetries. The breakdown of both symmetries is characterized by a new parameter (the asymetry parameter of the electroweak interactions. This parameter gives a measure of the strength of breakdown of symmetries. We analyse the behaviour of the theory for three values of this parameter. The most relevant value is the one for which only the electromagnetic interactions do not break parity (the maximally allowed left-right asymetric theory. Maximamally allowed parity asymmetry is a requirement that is met for a value of Weinberg's theta-angle that is quite close to the experimental value of this parameter.Com base em uma formulação nova para simetrias das interações fundamentais nós lidamos, neste trabalho, com interações eletrofracas de leptons. Mostramos que as constantes do acoplamento, associadas aos acoplamentos de bósons intermediários, podem ser entendidas como parâmetros associados à quebra de simetrias SU(2 e paridade. A quebra de ambas as simetrias é caracterizada por um parâmetro novo (o parâmetro de assimetria das interações eletrofracas. Este parâmetro dá uma medida da intensidade com que a simetria é quebrada. Analisamos o comportamento da teoria para três valores deste parâmetro. O valor mais relevante é aquele para o qual apenas as interações eletromagnéticas não quebram a paridade (a teoria assimétrica esquerda-direita permitida da maneira máxima. A assimetria máxima permitida é uma exigência que leva a um ângulo de Weinberg cujo valor é próximo daquele observado experimentalmente.
Gu, Qing; Bravo-Díaz, Carlos; Romsted, Laurence S
2013-06-15
Kinetic results obtained in cationic and anionic emulsions show for the first time that pseudophase kinetic models give reasonable estimates of the partition constants of reactants, here t-butylhydroquinone (TBHQ) between the oil and interfacial region, P(O)(I), and the water and interfacial region, P(W)(I), and of the interfacial rate constant, k(I), for the reaction with an arenediazonium ion in emulsions containing a 1:1 volume ratio of a medium chain length triglyceride, MCT, and aqueous acid or buffer. The results provide: (a) an explanation for the large difference in pH, >4 pH units, required to run the reaction in CTAB (pH 1.54, added HBr) and SDS (pH 5.71, acetate buffer) emulsions; (b) reasonable estimates of PO(I) and k(I) in the CTAB emulsions; (c) a sensible interpretation of added counterion effects based on ion exchange in SDS emulsions (Na(+)/H3O(+) ion exchange in the interfacial region) and Donnan equilibrium in CTAB emulsions (Br(-) increasing the interfacial H3O(+)); and (d) the significance of the effect of the much greater solubility of TBHQ in MCT versus octane, 1000/1, as the oil. These results should aid in interpreting the effects of ionic surfactants on chemical reactivity in emulsions in general and in selecting the most efficient antioxidant for particular food applications.
Quenched Heavy-Light Decay Constants
Baxter, R M; Bowler, K C; Collins, S; Henty, D S; Kenway, R D; Richards, D G; Shanahan, H P; Simone, J N; Simpson, A D; Wilkes, B E; Ewing, A K; Lellouch, L P; Sachrajda, Christopher T C; Wittig, H
1994-01-01
We present results for heavy-light decay constants, using both propagating quarks and the static approximation, in O(a)-improved, quenched lattice QCD. At beta=6.2 on a 24^3x48 lattice we find f_D=185 +4-3(stat)+42-7(syst) MeV, f_B=160 +6-6 +53-19 MeV, f_{D_s}/f_D=1.18 +2-2 and f_{B_s}/f_B=1.22 +4-3, in good agreement with earlier studies. From the static theory we obtain f_B^stat=253 +16-15 +105-14 MeV. We also present results from a simulation at beta=6.0 on a 16^3x48 lattice, which are consistent with those at beta=6.2. In order to study the effects of improvement, we present a direct comparison of the results using both the Wilson and the improved action at beta=6.0.
Can Dust Segregation Mimic a Cosmological Constant?
Simonsen, J T; Simonsen, Jakob T.; Hannestad, Steen
1999-01-01
Recent measurements of type Ia supernovae indicate that distant supernovae are substantially fainter than expected from the standard flat cold dark matter model. One possible explanation is that the energy density in our universe is in fact dominated by a cosmological constant. Another possible solution is that there are large amounts of grey dust in the intergalactic medium. Dust grains can be grey either because they are non-spherical or very large. We have numerically investigated whether grey dust can be emitted from high redshift galaxies without also emitting standard, reddening dust, which would have been visible in the spectra of high redshift objects. Our finding is that grain velocities are almost independent of ellipticity so that if greyness are due to the grains being elongated, it will not be possible to separate grey dust from ordinary dust. We also find that velocities are fairly independent of grain size, but we cannot rule out possible sputtering of small grains, so that large, grey dust gra...
Tunnelling with a negative cosmological constant
Gibbons, G. W.
1996-02-01
The point of this paper is to see what light new results in hyperbolic geometry may throw on gravitational entropy and whether gravitational entropy is relevant for the quantum origin of the universe. We introduce some new gravitational instantons which mediate the birth from nothing of closed universes containing wormholes and suggest that they may contribute to the density matrix of the universe. We also discuss the connection between their gravitational action and the topological and volumetric entropies introduced in hyperbolic geometry. These coincide for hyperbolic 4-manifolds, and increase with increasing topological complexity of the 4-manifold. We raise the question of whether the action also increases with the topological complexity of the initial 3-geometry, measured either by its 3-volume or its Matveev complexity. We point out, in distinction to the non-supergravity case, that universes with domains of negative cosmological constant separated by supergravity domain walls cannot be born from nothing. Finally we point out that our wormholes provide examples of the type of Perpetual Motion machines envisaged by Frolov and Novikov.
The Constant Comparative Method of Qualitative Analysis
Directory of Open Access Journals (Sweden)
Barney G. Glaser, Ph.D.
2008-11-01
Full Text Available Currently, the general approaches to the analysis of qualitative data are these:1. If the analyst wishes to convert qualitative data into crudely quantifiable form so that he can provisionally test a hypothesis, he codes the data first and then analyzes it. He makes an effort to code “all relevant data [that] can be brought to bear on a point,” and then systematically assembles, assesses and analyzes these data in a fashion that will “constitute proof for a given proposition.”i2. If the analyst wishes only to generate theoretical ideasnew categories and their properties, hypotheses and interrelated hypotheses- he cannot be confined to the practice of coding first and then analyzing the data since, in generating theory, he is constantly redesigning and reintegrating his theoretical notions as he reviews his material.ii Analysis with his purpose, but the explicit coding itself often seems an unnecessary, burdensome task. As a result, the analyst merely inspects his data for new properties of his theoretical categories, and writes memos on these properties.We wish to suggest a third approach
Time constant of the cerebral arterial bed.
Kasprowicz, Magdalena; Diedler, Jennifer; Reinhard, Matthias; Carrera, Emmanuel; Smielewski, Peter; Budohoski, Karol P; Sorrentino, Enrico; Haubrich, Christina; Kirkpatrick, Peter J; Pickard, John D; Czosnyka, Marek
2012-01-01
We have defined a novel cerebral hemodynamic index, a time constant of the cerebral arterial bed (τ), the product of arterial compliance (C(a)) and cerebrovascular resistance (CVR). C(a) and CVR were calculated based on the relationship between pulsatile arterial blood pressure (ABP) and transcranial Doppler cerebral blood flow velocity. This new parameter theoretically estimates how fast the cerebral arterial bed is filled by blood volume after a sudden change in ABP during one cardiac cycle. We have explored this concept in 11 volunteers and in 25 patients with severe stenosis of the internal carotid artery (ICA). An additional group of 15 subjects with non-vascular dementia was studied to assess potential age dependency of τ. The τ was shorter (p = 0.011) in ICA stenosis, both unilateral (τ = 0.18 ± 0.04 s) and bilateral (τ = 0.16 ± 0.03 s), than in controls (τ = 0.22 ± 0.0 s). The τ correlated with the degree of stenosis (R = -0.62, p = 0.001). In controls, τ was independent of age. Further study during cerebrovascular reactivity tests is needed to establish the usefulness of τ for quantitative estimation of haemodynamics in cerebrovascular disease.
Type Ia Supernovae and the Hubble Constant
Branch, D
1998-01-01
The focus of this review is the work that has been done during the 1990s on using Type Ia supernovae (SNe Ia) to measure the Hubble constant ($H_0$). SNe Ia are well suited for measuring $H_0$. A straightforward maximum-light color criterion can weed out the minority of observed events that are either intrinsically subluminous or substantially extinguished by dust, leaving a majority subsample that has observational absolute-magnitude dispersions of less than $\\sigma_{obs}(M_B) \\simeq \\sigma_{obs}(M_V) \\simeq 0.3$ mag. Correlations between absolute magnitude and one or more distance-independent SN Ia or parent-galaxy observables can be used to further standardize the absolute magnitudes to better than 0.2 mag. The absolute magnitudes can be calibrated in two independent ways --- empirically, using Cepheid-based distances to parent galaxies of SNe Ia, and physically, by light curve and spectrum fitting. At present the empirical and physical calibrations are in agreement at $M_B \\simeq M_V \\simeq -19.4$ or -19....
Holographic Dark Energy with Cosmological Constant
Hu, Yazhou; Li, Nan; Zhang, Zhenhui
2015-01-01
Inspired by the multiverse scenario, we study a heterotic dark energy model in which there are two parts, the first being the cosmological constant and the second being the holographic dark energy, thus this model is named the $\\Lambda$HDE model. By studying the $\\Lambda$HDE model theoretically, we find that the parameters $c$ and $\\Omega_{hde}$ are divided into a few domains in which the fate of the universe is quite different. We investigate dynamical behaviors of this model, and especially the future evolution of the universe. We perform fitting analysis on the cosmological parameters in the $\\Lambda$HDE model by using the recent observational data. We find the model yields $\\chi^2_{\\rm min}=426.27$ when constrained by Planck+SNLS3+BAO+HST, comparable to the results of the HDE model (428.20) and the concordant $\\Lambda$CDM model (431.35). At 68.3\\% CL, we obtain $-0.07<\\Omega_{\\Lambda0}<0.68$ and correspondingly $0.04<\\Omega_{hde0}<0.79$, implying at present there is considerable degeneracy bet...
Determination of the Hubble Constant Using Cepheids
Abdel-Sabour, Mohamed; Issa, Issa Ali; El-Nawawy, Mohamed Saleh; Kordi, Ayman; Almostafa, Zaki; El-Said, Ahmad Essam; Ali, Gamal Bakr
2014-01-01
This paper introduces a statistical treatment to use Cepheid variable stars as distance indicators. The expansion rate of the Universe is also studied here through deriving the value of the Hubble constant H0. A Gaussian function approximation is proposed to fit the absolute magnitude and period of Cepheid variables in our galaxy. The calculations are carried out on samples of Cepheids observed in 23 galaxies to derive the distance modulus (DM) of these galaxies based on the frequency distributions of their periods and intrinsic apparent magnitudes. The DM is the difference between the apparent magnitude for extragalactic Cepheids and the absolute magnitude of the galactic Cepheids at maximum number. It is calculated by using the comparison of the period distribution of Cepheids in our galaxy and in other galaxies. This method is preferred due to its simplicity to use and its efficiency in providing reliable DM. A linear fit with correlation coefficient of 99.68% has been found between the published distance ...
Expanding Taylor bubble under constant heat flux
Voirand, Antoine; Benselama, Adel M.; Ayel, Vincent; Bertin, Yves
2016-09-01
Modelization of non-isothermal bubbles expanding in a capillary, as a contribution to the understanding of the physical phenomena taking place in Pulsating Heat Pipes (PHPs), is the scope of this paper. The liquid film problem is simplified and solved, while the thermal problem takes into account a constant heat flux density applied at the capillary tube wall, exchanging with the liquid film surrounding the bubble and also with the capillary tube outside medium. The liquid slug dynamics is solved using the Lucas-Washburn equation. Mass and energy balance on the vapor phase allow governing equations of bubble expansion to be written. The liquid and vapor phases are coupled only through the saturation temperature associated with the vapor pressure, assumed to be uniform throughout the bubble. Results show an over-heating of the vapor phase, although the particular thermal boundary condition used here always ensures an evaporative mass flux at the liquid-vapor interface. Global heat exchange is also investigated, showing a strong decreasing of the PHP performance to convey heat by phase change means for large meniscus velocities.
Determination of magneto-optical constant of Fe films with weak measurements
Energy Technology Data Exchange (ETDEWEB)
Qiu, Xiaodong; Hu, Dejiao; Du, Jinglei; Gao, Fuhua; Zhang, Zhiyou, E-mail: zhangzhiyou@scu.edu.cn [Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Zhou, Xinxing; Luo, Hailu, E-mail: hailuluo@hnu.edu.cn [Laboratory for Spin Photonics, College of Physics and Electronic Science, Hunan University, Changsha 410082 (China)
2014-09-29
In this letter, a detecting method for the magneto-optical constant is presented by using weak measurements. The photonic spin Hall effect (PSHE), which manifests itself as spin-dependent splitting, is introduced to characterize the magneto-optical constant, and a propagation model to describe the quantitative relation between the magneto-optical constant and the PSHE is established. According to the amplified shift of the PSHE detected by weak measurements, we determinate the magneto-optical constant of the Fe film sample. The Kerr rotation is measured via the standard polarimetry method to verify the rationality and feasibility of our method. These findings may provide possible applications in magnetic physics research.
Determination of magneto-optical constant of Fe films with weak measurements
Qiu, Xiaodong; Zhou, Xinxing; Hu, Dejiao; Du, Jinglei; Gao, Fuhua; Zhang, Zhiyou; Luo, Hailu
2014-09-01
In this letter, a detecting method for the magneto-optical constant is presented by using weak measurements. The photonic spin Hall effect (PSHE), which manifests itself as spin-dependent splitting, is introduced to characterize the magneto-optical constant, and a propagation model to describe the quantitative relation between the magneto-optical constant and the PSHE is established. According to the amplified shift of the PSHE detected by weak measurements, we determinate the magneto-optical constant of the Fe film sample. The Kerr rotation is measured via the standard polarimetry method to verify the rationality and feasibility of our method. These findings may provide possible applications in magnetic physics research.
Realistic Silver Optical Constants for Plasmonics
Yajie Jiang; Supriya Pillai; GREEN Martin A.
2016-01-01
Silver remains the preferred conductor for optical and near-infrared plasmonics. Many high-profile studies focus exclusively on performance simulation in such applications. Almost invariably, these use silver optical data either from Palik’s 1985 handbook or, more frequently, an earlier Johnson and Christy (J&C) tabulation. These data are inconsistent, making it difficult to ascertain the reliability of the simulations. The inconsistency stems from challenges in measuring representative prope...
New multitarget constant modulus array for CDMA systems
Institute of Scientific and Technical Information of China (English)
Zhang Jidong; Zheng Baoyu
2006-01-01
A new multitarget constant modulus array is proposed for CDMA systems based on least squares constant modulus algorithm. The new algorithm is called pre-despreading decision directed least squares constant modulus algorithm (DDDLSCMA). In the new algorithm, the pre-despreading is first applied for multitarget arrays to remove some multiple access signals, then the despreaded signal is processed by the algorithm which united the constant modulus algorithm and decision directed method. Simulation results illustrate the good performance for the proposed algorithm.
Study on cipher propertys of constant weight codes
Institute of Scientific and Technical Information of China (English)
Lin Bogang
2006-01-01
Constant weight code is an important error-correcting control code in communications. Basic structure of constant weight codes for some arriving at Johnson bound, A(n, 2u, w), is presented. Some correlative propertys of the codes, the solution of arriving at Johnson bound, and the results on the couple constant code and some constant weight codes are discussed. The conclusion is verified through four examples.
Deformed extra space and the smallness of the cosmological constant
Rubin, Sergey G
2016-01-01
The mechanism of different universes formation is elaborated. Each universe is characterized by a unique cosmological constant. It is shown that the set of cosmological constants has the cardinality of the continuum and contains zero cosmological constant. Those universes with cosmological constants near zero could be filled by complex structures. There is no necessity in a special mechanism of the fine tuning. The role of quantum fluctuations is studied.
The type Ia supernovae and the Hubble's constant
2004-01-01
The Hubble's constant is usually surmised to be a constant; but the experiments show a large spread and conflicting estimates. According to the plasma-redshift theory, the Hubble's constant varies with the plasma densities along the line of sight. It varies then slightly with the direction and the distance to a supernova and a galaxy. The relation between the magnitudes of type Ia supernovae and their observed redshifts results in an Hubble's constant with an average value in intergalactic sp...
A relation between diffusion,temperature and the cosmological constant
Haba, Z
2016-01-01
We show that the temperature of a diffusing fluid with the diffusion constant \\kappa^{2} in an expanding universe approaches a constant limit T=\\kappa^{2}/H in its final de Sitter stage characterized by the horizon 1/H determined by the Hubble constant. If de Sitter surface temperature in the final equilibrium state coincides with the fluid temperature then the cosmological constant \\Lambda=3H^{2}=6\\pi\\kappa^{2}.
A novel constant degree and constant congestion DHT scheme for peer-to-peer networks
Institute of Scientific and Technical Information of China (English)
LI Dongsheng; LU Xicheng
2005-01-01
Degree, diameter and congestion are important measures of distributed hash table (DHT) schemes for peer-to-peer networks. Many proposed DHT schemes are based on some traditional interconnection topologies and the Kautz graph is a topology with good properties such as optimal network diameter. In this paper, FissionE, a novel DHT scheme based on the Kautz graph, is proposed. FissionE is the first constant degree and O(logN) diameter DHT scheme with (1+o(1))-congestion. FissionE shows that the DHT scheme with constant degree and constant congestion can achieve O(logN) diameter, which is better than the lower bound Ω(N1/d) conjectured before. The average degree of FissionE is 4 and the diameter is 2*log2N, and the average routing path length is about Iog2N. The average path length of FissionE is shorter than CAN or Koorde with the same degree when the P2P network is large scale.
A study on the dielectric constant of microcapsules during ageing.
Labhasetwar, V D; Joshi, S V; Dorle, A K
1988-01-01
Gelatin and methylcellulose microcapsules with and without sulphadiazine were compressed into compacts. The dielectric constant of these compacts was measured at regular intervals during ageing at 45 degrees C. An initial sharp fall in dielectric constant is followed by a progressive increase. Dielectric constant could be a parameter to study the changes occurring in microcapsules during ageing.
On the radius constants for classes of analytic functions
Ali, Rosihan M.; Jain, Naveen; Ravichandran, V.
2012-01-01
Radius constants for several classes of analytic functions on the unit disk are obtained. These include the radius of starlikeness of a positive order, radius of parabolic starlikeness, radius of Bernoulli lemniscate starlikeness, and radius of uniform convexity. In the main, the radius constants obtained are sharp. Conjectures on the non-sharp constants are given.
Some comments on the universal constant in DSR
Girelli, F; Girelli, Florian; Livine, Etera R.
2006-01-01
Deformed Special Relativity is usually presented as a deformation of Special Relativity accommodating a new universal constant, the Planck mass, while respecting the relativity principle. In order to avoid some fundamental problems (e.g. soccer ball problem), we argue that we should switch point of view and consider instead the Newton constant $G$ as the universal constant.
Nuclear magnetic resonance J coupling constant polarizabilities of hydrogen peroxide
DEFF Research Database (Denmark)
Kjær, Hanna; Nielsen, Monia R.; Pagola, Gabriel I.
2012-01-01
In this paper we present the so far most extended investigation of the calculation of the coupling constant polarizability of a molecule. The components of the coupling constant polarizability are derivatives of the NMR indirect nuclear spin-spin coupling constant with respect to an external elec...
Systematic harmonic power laws inter-relating multiple fundamental constants
Chakeres, Donald; Buckhanan, Wayne; Andrianarijaona, Vola
2017-01-01
Power laws and harmonic systems are ubiquitous in physics. We hypothesize that 2, π, the electron, Bohr radius, Rydberg constant, neutron, fine structure constant, Higgs boson, top quark, kaons, pions, muon, Tau, W, and Z when scaled in a common single unit are all inter-related by systematic harmonic powers laws. This implies that if the power law is known it is possible to derive a fundamental constant's scale in the absence of any direct experimental data of that constant. This is true for the case of the hydrogen constants. We created a power law search engine computer program that randomly generated possible positive or negative powers searching when the product of logical groups of constants equals 1, confirming they are physically valid. For 2, π, and the hydrogen constants the search engine found Planck's constant, Coulomb's energy law, and the kinetic energy law. The product of ratios defined by two constants each was the standard general format. The search engine found systematic resonant power laws based on partial harmonic fraction powers of the neutron for all of the constants with products near 1, within their known experimental precision, when utilized with appropriate hydrogen constants. We conclude that multiple fundamental constants are inter-related within a harmonic power law system.
Beauty vector meson decay constants from QCD sum rules
Energy Technology Data Exchange (ETDEWEB)
Lucha, Wolfgang [Institute for High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, A-1050 Vienna (Austria); Melikhov, Dmitri [Institute for High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, A-1050 Vienna (Austria); D. V. Skobeltsyn Institute of Nuclear Physics, M. V. Lomonosov Moscow State University, 119991, Moscow (Russian Federation); Simula, Silvano [Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146, Roma (Italy)
2016-01-22
We present the outcomes of a very recent investigation of the decay constants of nonstrange and strange heavy-light beauty vector mesons, with special emphasis on the ratio of any such decay constant to the decay constant of the corresponding pseudoscalar meson, by means of Borel-transformed QCD sum rules. Our results suggest that both these ratios are below unity.
Search for Possible Variation of the Fine Structure Constant
2003-01-01
Determination of the fine structure constant alpha and search for its possible variation are considered. We focus on a role of the fine structure constant in modern physics and discuss precision tests of quantum electrodynamics. Different methods of a search for possible variations of fundamental constants are compared and those related to optical measurements are considered in detail.
Beauty Vector Meson Decay Constants from QCD Sum Rules
Lucha, Wolfgang; Simula, Silvano
2016-01-01
We present the outcomes of a very recent investigation of the decay constants of nonstrange and strange heavy-light beauty vector mesons, with special emphasis on the ratio of any such decay constant to the decay constant of the corresponding pseudoscalar meson, by means of Borel-transformed QCD sum rules. Our results suggest that both these ratios are below unity.
Beauty vector meson decay constants from QCD sum rules
Lucha, Wolfgang; Melikhov, Dmitri; Simula, Silvano
2016-01-01
We present the outcomes of a very recent investigation of the decay constants of nonstrange and strange heavy-light beauty vector mesons, with special emphasis on the ratio of any such decay constant to the decay constant of the corresponding pseudoscalar meson, by means of Borel-transformed QCD sum rules. Our results suggest that both these ratios are below unity.
Energy Technology Data Exchange (ETDEWEB)
Guo Fukui [Institute of Mathematics, Information School, Shandong University of Science and Technology, Qingdao Huangdao 266510 (China); Zhang Yufeng [Institute of Mathematics, Information School, Shandong University of Science and Technology, Qingdao Huangdao 266510 (China)], E-mail: zhang_yfshandong@163.com
2008-10-15
V{sub 3} is a 3-dimensional Lie algebra whose commuting operation involves in nine parameters. Appropriately choosing these parameters makes V{sub 3} become an arbitrary 3-dimensional Lie algebra. Denote the loop algebra V{sup {approx}}{sub 3} generated by V{sub 3}, from which linear isospectral problems are set up to produce a good many integrable hierarchies of equations. Some of them can be turned into Hamiltonian forms by means of the trace identity, others can be cast into Hamiltonian expressions with the help of the quadratic-form identity. A unified computational formula on the constant {gamma} appeared in the trace identity and the quadratic-form identity is obtained, from which the left problem remarkably proposed in Tu [Tu Guizhang. The trace identity, a powerful tool for constructing the Hamiltonian structure of integrable systems. J Math Phys 1989;30(2):330-8] is completely overcome in the paper.
Bambi, Cosimo
2013-01-01
Extensions of general relativity and theories aiming at unifying gravity with the forces of the Standard Model are usually characterized by new degrees of freedom and violations of the Einstein Equivalence Principle. The search for time and/or space variations of fundamental parameters like the fine structure constant $\\alpha$ tests the assumption of Local Position Invariance. In this letter, I show that the analysis of the K$\\alpha$ iron line observed in the X-ray spectrum of black holes can probe $\\alpha$ in gravitational potentials relative to Earth of $\\Delta \\phi \\approx 0.1$. From the measurements of the black hole in Cygnus X-1 reported in the literature, one obtains $|\\Delta \\alpha / \\alpha| \\lesssim 0.01$.
Energy Technology Data Exchange (ETDEWEB)
Poirier, E
2002-12-01
Nuclei with A {approx} 70 along the N=Z line are known to be the scene of phenomena closely related to the nuclear deformation and are of particular interest since theoretical mean field calculations predict that a large part of the Gamow-Teller resonance might be located below the ground state of the mother nucleus and then be accessible through {beta}-decay studies. These results have shown the effect of the shape of the ground state on the intensity of the Gamow-Teller strength. Thus, the experimental determination, through {delta}-decay, of the Gamow-Teller strength distribution and the comparison to the theoretical predictions allow to pin down the quadrupolar deformation parameter of the ground state of the parent nucleus. In order to study the neutron deficient isotopes of krypton (A=72,73,74,75) and strontium (A=76,77,78) and to establish the {beta}-strength on the full energy range, a new total absorption spectrometer (TAgS) has been built in the frame of an international collaboration and installed at the (SOLDE/CERN mass separator. For the data analysis, the response function R of the spectrometer has been calculated by means of Monte-Carlo simulations, based on the GEANT4 code, and of a statistical description of the level scheme in the daughter nucleus. The {beta}-feeding distribution has been obtained from experimental spectra through a method based on Bayes theorem and then converted into Gamow-Teller strength. The results coming from the {sup 74}Kr decay analysis allow to describe the ground state of such a nucleus as the coexistence of an oblate shape and of a prolate shape. In the case of {sup 76}Sr, the experimental Gamow-Teller strength distribution strongly indicates a prolate deformation. (author)
A new extension of Hilbert's inequality for multifunctions with best constant factors
Directory of Open Access Journals (Sweden)
H. A. Agwo
2009-08-01
Full Text Available The aim of this paper is to establish a new extension of Hilbert's inequality and Hardy-Hilbert's inequality for multifunctions with best constants factors. Also, we present some applications for Hilbert's inequality which give new integral inequalities.
Lee, Kuo-Wei
2016-01-01
We prove the existence and uniqueness of the Dirichlet problem for spacelike, spherically symmetric, constant mean curvature equation with symmetric boundary data in the extended Schwarzschild spacetime. As an application, we completely solve the CMC foliation conjecture which is posted by Malec and O Murchadha in 2003.
Lee, Kuo-Wei
2016-09-01
We prove the existence and uniqueness of the Dirichlet problem for the spacelike, spherically symmetric, constant mean curvature equation with symmetric boundary data in the extended Schwarzschild spacetime. As an application, we completely solve the CMC foliation conjecture which is proposed by Malec and Murchadha (2003 Phys. Rev. D 68 124019).
Constant-Differential-Pressure Two-Fluid Accumulator
Piecuch, Benjamin; Dalton, Luke T.
2010-01-01
A two-fluid accumulator has been designed, built, and demonstrated to provide an acceptably close approximation to constant differential static pressure between two fluids over the full ranges of (1) accumulator stroke, (2) rates of flow of the fluids, and (3) common static pressure applied to the fluids. Prior differential- pressure two-fluid accumulators are generally not capable of maintaining acceptably close approximations to constant differential pressures. The inadequacies of a typical prior differential-pressure two-fluid accumulator can be summarized as follows: The static differential pressure is governed by the intrinsic spring rate (essentially, the stiffness) of an accumulator tank. The spring rate can be tailored through selection of the tank-wall thickness, selection of the number and/or shape of accumulator convolutions, and/or selection of accumulator material(s). Reliance on the intrinsic spring rate of the tank results in three severe limitations: (1) The spring rate and the expulsion efficiency tend to be inversely proportional to each other: that is to say, as the stiffness (and thus the differential pressure) is increased, the range of motion of the accumulator is reduced. (2) As the applied common static pressure increases, the differential pressure tends to decrease. An additional disadvantage, which may or may not be considered limiting, depending on the specific application, is that an increase in stiffness entails an increase in weight. (3) The additional weight required by a low expulsion efficiency accumulator eliminates the advantage given to such gas storage systems. The high expulsion efficiency provided by this two-fluid accumulator allows for a lightweight, tightly packaged system, which can be used in conjunction with a fuel cell-based system.
Implications of a Time-Varying Fine Structure Constant
Alfonso-Faus, A
2002-01-01
Much work has been done after the possibility of a fine structure constant being time-varying. It has been taken as an indication of a time-varying speed of light. Here we prove that this is not the case. We prove that the speed of light may or may not vary with time, independently of the fine structure constant being constant or not. Time variations of the speed of light, if present, have to be derived by some other means and not from the fine structure constant. No implications based on the possible variations of the fine structure constant can be imposed on the speed of light.
Influence of coupling constants on nuclear symmetry energy
Institute of Scientific and Technical Information of China (English)
LIU Bei-Bei; OUYANG Fei; CHEN Wei
2013-01-01
By studying the energy of neutron star matter,we discuss the nuclear symmetry energy at different baryon densities and different coupling constants in the relativistic mean field approximation.The results show that the symmetry energy increases with baryon density at various coupling constants and incompressibilities.Furthermore,the symmetry energy at saturation density increases with increasing incompressibility at fixed d,and decreases at fixed c.Specifically,when coupling constants gv and gs are fixed,respectively,the symmetry energy has a little change with increasing incompressibility.It is demonstrated that the NN coupling constants have greater influences on the symmetry energy than the self-coupling constants.
Rotating-bed reactor as a power source for EM gun applications
Energy Technology Data Exchange (ETDEWEB)
Powell, J.; Botts, T.; Stickley, C.M.; Meth, S.
1980-01-01
Electromagnetic gun applications of the Rotating Bed Reactor (RBR) are examined. The RBR is a compact (approx. 1 m/sup 3/), (up to several thousand MW(th)), high-power reactor concept, capable of producing a high-temperature (up to approx. 300/sup 0/K) gas stream with a MHD generator coupled to it, the RBR can generate electric power (up to approx. 1000 MW(e)) in the pulsed or cw modes. Three EM gun applications are investigated: a rail gun thruster for orbit transfer, a rapid-fire EM gun for point defense, and a direct ground-to-space launch. The RBR appears suitable for all applications.
DEFF Research Database (Denmark)
Álvarez-Asencio, R.; Thormann, Esben; Rutland, M.W.
2013-01-01
A technique has been developed for the calculation of torsional spring constants for AFM cantilevers based on the combination of the normal spring constant and plate/beam theory. It is easy to apply and allow the determination of torsional constants for stiff cantilevers where the thermal power...
Multiple constant multiplication optimizations for field programmable gate arrays
Kumm, Martin
2016-01-01
This work covers field programmable gate array (FPGA)-specific optimizations of circuits computing the multiplication of a variable by several constants, commonly denoted as multiple constant multiplication (MCM). These optimizations focus on low resource usage but high performance. They comprise the use of fast carry-chains in adder-based constant multiplications including ternary (3-input) adders as well as the integration of look-up table-based constant multipliers and embedded multipliers to get the optimal mapping to modern FPGAs. The proposed methods can be used for the efficient implementation of digital filters, discrete transforms and many other circuits in the domain of digital signal processing, communication and image processing. Contents Heuristic and ILP-Based Optimal Solutions for the Pipelined Multiple Constant Multiplication Problem Methods to Integrate Embedded Multipliers, LUT-Based Constant Multipliers and Ternary (3-Input) Adders An Optimized Multiple Constant Multiplication Architecture ...
Investigation of the fundamental constants stability based on the reactor Oklo burn-up analysis
Onegin, M S
2014-01-01
New severe constraints on the variation of the fine structure constant have been obtained from reactor Oklo analysis in our previous work. We investigate here how these constraints confine the parameter of BSBM model of varying $\\alpha$. Integrating the coupled system of equations from the Big Bang up to the present time and taking into account the Oklo limits we have obtained the following margin on the combination of the parameters of BSBM model: $$ |\\zeta_m (\\frac{l}{l_{pl}})^2|<6\\cdot 10^{-7}, $$ where $l_{pl}=(\\frac{G\\hbar}{c^3})^{\\frac{1}{2}} \\approx 1.6 \\cdot 10^{-33}$ cm is a Plank length and $l$ is the characteristic length of the BSBM model. The natural value of the parameter $\\zeta_m$ - the fraction of electromagnetic energy in matter - is about $10^{-4}$. As a result it is followed from our analysis that the characteristic length $l$ of BSBM theory should be considerably smaller than the Plank length to fulfill the Oklo constraints on $\\alpha$ variation.
Realistic Silver Optical Constants for Plasmonics
Jiang, Yajie; Pillai, Supriya; Green, Martin A.
2016-07-01
Silver remains the preferred conductor for optical and near-infrared plasmonics. Many high-profile studies focus exclusively on performance simulation in such applications. Almost invariably, these use silver optical data either from Palik’s 1985 handbook or, more frequently, an earlier Johnson and Christy (J&C) tabulation. These data are inconsistent, making it difficult to ascertain the reliability of the simulations. The inconsistency stems from challenges in measuring representative properties of pristine silver, due to tarnishing on air exposure. We demonstrate techniques, including use of silicon-nitride membranes, to access the full capabilities of multiple-angle, spectrometric-ellipsometry to generate an improved data set, representative of overlayer-protected, freshly-deposited silver films on silicon-nitride and glass.
Massa, Enrico; Nicolaus, Arnold
2011-04-01
This issue of Metrologia collects papers about the results of an international research project aimed at the determination of the Avogadro constant, NA, by counting the atoms in a silicon crystal highly enriched with the isotope 28Si. Fifty years ago, Egidi [1] thought about realizing an atomic mass standard. In 1965, Bonse and Hart [2] operated the first x-ray interferometer, thus paving the way to the achievement of Egidi's dream, and soon Deslattes et al [3] completed the first counting of the atoms in a natural silicon crystal. The present project, outlined by Zosi [4] in 1983, began in 2004 by combining the experiences and capabilities of the BIPM, INRIM, IRMM, NIST, NPL, NMIA, NMIJ and PTB. The start signal, ratified by a memorandum of understanding, was a contract for the production of a silicon crystal highly enriched with 28Si. The enrichment process was undertaken by the Central Design Bureau of Machine Building in St Petersburg. Subsequently, a polycrystal was grown in the Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences in Nizhny Novgorod and a 28Si boule was grown and purified by the Leibniz-Institut für Kristallzüchtung in Berlin. Isotope enrichment made it possible to apply isotope dilution mass spectroscopy, to determine the Avogadro constant with unprecedented accuracy, and to fulfil Egidi's dream. To convey Egidi's 'fantasy' into practice, two 28Si kilogram prototypes shaped as quasi-perfect spheres were manufactured by the Australian Centre for Precision Optics; their isotopic composition, molar mass, mass, volume, density and lattice parameter were accurately determined and their surfaces were chemically and physically characterized at the atomic scale. The paper by Andreas et al reviews the work carried out; it collates all the findings and illustrates how Avogadro's constant was obtained. Impurity concentration and gradients in the enriched crystal were measured by infrared spectroscopy and taken into
Momose, Takamasa; Yamaguchi, Makoto; Shida, Tadamasa
1990-11-01
Following the previous work on the isotropic hyperfine coupling constants (HFCCs) of polyatomic radicals the symmetry adapted cluster expansion-configuration interaction (SAC-CI) theory is applied to calculate anisotropic HFCCs also. The results are compared with available experimental data from diatomic to polyatomic radicals such as the vinoxy. For radicals consisting of only the first row atoms Dunning's double zeta (DZ) basis set is shown to be adequate, but for those containing the second row atoms inclusion of polarization functions is required. Compared with the isotropic HFCC the calculation of the anisotropic HFCC is less formidable. However, ignorance of electron correlation causes serious disagreements with experimental data.
Systematic Angle Random Walk Estimation of the Constant Rate Biased Ring Laser Gyro
Directory of Open Access Journals (Sweden)
Guohu Feng
2013-02-01
Full Text Available An actual account of the angle random walk (ARW coefficients of gyros in the constant rate biased rate ring laser gyro (RLG inertial navigation system (INS is very important in practical engineering applications. However, no reported experimental work has dealt with the issue of characterizing the ARW of the constant rate biased RLG in the INS. To avoid the need for high cost precise calibration tables and complex measuring set-ups, the objective of this study is to present a cost-effective experimental approach to characterize the ARW of the gyros in the constant rate biased RLG INS. In the system, turntable dynamics and other external noises would inevitably contaminate the measured RLG data, leading to the question of isolation of such disturbances. A practical observation model of the gyros in the constant rate biased RLG INS was discussed, and an experimental method based on the fast orthogonal search (FOS for the practical observation model to separate ARW error from the RLG measured data was proposed. Validity of the FOS-based method was checked by estimating the ARW coefficients of the mechanically dithered RLG under stationary and turntable rotation conditions. By utilizing the FOS-based method, the average ARW coefficient of the constant rate biased RLG in the postulate system is estimated. The experimental results show that the FOS-based method can achieve high denoising ability. This method estimate the ARW coefficients of the constant rate biased RLG in the postulate system accurately. The FOS-based method does not need precise calibration table with high cost and complex measuring set-up, and Statistical results of the tests will provide us references in engineering application of the constant rate biased RLG INS.
Directory of Open Access Journals (Sweden)
S. D. Deosarkar
2012-01-01
Full Text Available The proton-ligand stability constants of some biologically important new pyrazoles and formation constants of their complexes with Ni(II were determined at 0.1 mol dm-3 ionic strength and at 303.15 K in different dielectric constant of dioxane-water mixture by potentiometric method. The Calvin-Bjerrum's pH-titration technique as used by Irving and Rossotti was used for determination of stability constants. The results enabled to study the electrostatic forces of attraction between metal ion and ligand with changes in dielectric constant of the medium.
Legal reality of Russia: constants and variables
Directory of Open Access Journals (Sweden)
Andrey Valeryevich Skorobogatov
2015-06-01
Full Text Available Objective to develop the sciencebased knowledge about essential and substantial aspects of the current legal reality of Russia in the context of postclassical paradigm. Methods the methodological basis of this research is the synthesis of classical and postclassical paradigms that determine the choice of specific methods of research formallegal comparative legal modeling method hermeneutic discursive methods. Results basing on the postclassical methodology it is proved that the legal reality of Russia consists of three levels legislation law enforcement and legal behavior. The determinant level of legal reality is legal behavior that is aimed at observing the unwritten rules. The legal reality of Russia is characterized by a transgressive state of the modern Russian society expressed in broad application of nonlegislative nonlegal practices low level of legal culture legal nihilism and legal infantilism. Scientific novelty the article for the first time analyzes the ontological and phenomenological essence of the legal reality in Russia and determines its transgressive nature at the present stage of development. Practical value the main provisions and conclusions of the article can be used in scientific and pedagogical activity when considering questions about the nature and content of legal development. nbsp
Novel high dielectric constant hybrid elastomers based on glycerol-insilicone emulsions
DEFF Research Database (Denmark)
Mazurek, Piotr Stanislaw; Skov, Anne Ladegaard
2016-01-01
Novel hybrid elastomers were prepared by speedmixing of two virtually immiscible liquids – glycerol and polydimethylsiloxane (PDMS) prepolymer. Upon crosslinking ofthe PDMS phase of the resulting glycerol-in-silicone emulsion freestanding films were obtained. In this way glycerol became uniformly...... distributed within PDMS in shape of discrete droplets thus acting as a high dielectric constant filler efficiently enhancing the dielectric constant of the composites. Low- and high-voltage dielectric spectroscopy measurements were conducted in order to verify applicability of the composites as dielectric...... elastomeractuators. Conductivities of samples based on various PDMS compositions with different loadings of embedded glycerol were thoroughly investigated providing useful information about the dielectric behavior....
Deflation of the cosmological constant associated with inflation and dark energy
Geng, Chao-Qiang
2016-01-01
In order to solve the fine-tuning problem of the cosmological constant, we propose a simple model with the vacuum energy non-minimally coupled to the inflaton field. In this model, the vacuum energy decays to the inflaton during pre-inflation and inflation eras, so that the cosmological constant effectively deflates from the Planck mass scale to a much smaller one after inflation and plays the role of dark energy in the late-time of the universe. We show that our deflationary scenario is applicable to arbitrary slow-roll inflation models. We also take two specific inflation potentials to illustrate our results.
Directory of Open Access Journals (Sweden)
A.R. Jivani
2011-01-01
Full Text Available The elastic constants, pressure derivative of bulk modulus and pressure derivative of elastic constants are investigated using the higher-order perturbation theory based on pseudopotential formalism and the application of our proposed model potential for Boron Phosphide. The parameter of the potential is derived using zero-pressure equilibrium condition. In the present study, Hartree and Sarkar et al screening functions are used to consider exchange and correlation effect. The good agreement of presently investigated numerical data is found with the available experiment data and other such theoretical values.
Demiralay, Ebru Çubuk; Koç, Duygu; Daldal, Y Doğan; Cakır, Cansel
2012-12-01
In this work, dissociation constants values of seven beta lactam antibiotics in water and acetonitrile-water mixtures using spectrophotometric and reversed phase liquid chromatography methods were determined. The dissociation constant values of these compounds were calculated by NLREG and STAR programs. Aqueous pK(a) values of beta lactam antibiotics were calculated with extrapolation by means of the Yasuda-Shedlovsky and mole fraction equations. Finally, application of the different techniques was compared to the determination of aqueous pK(a) values of investigated compounds.
ASYMPTOTIC EXPANSION AND ESTIMATE OF THE LANDAU CONSTANT
Institute of Scientific and Technical Information of China (English)
A.Eisinberg; G.Franzè; N.Salerno
2001-01-01
Properties of Landau constant are investigated in this note.A new representation in terms of a hypergeometric function 3F2 is given and a property defining the family of asymptotic sequences of Landau constant is formalized.Moreover,we give an other asymptotic expansion of Landau constant by using asymptotic expansion of the ratio of gamma functions in the sense of Poincaré due to Tricomi and Erdélyi.
A Constant Envelope OFDM Implementation on GNU Radio
2015-02-02
Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/5524--15-9575 A Constant Envelope OFDM Implementation on GNU Radio February 2, 2015...NUMBER OF PAGES 17. LIMITATION OF ABSTRACT A Constant Envelope OFDM Implementation on GNU Radio Andrew Robertson, Amos Ajo, Sastry Kompella, Joe...time for non-linear amplification. These requirements are uniquely served by constant envelope OFDM . We describe the use-cases, theory, and
Camera Constant in the Case of Two Media Photogrammetry
Agrafiotis, P.; Georgopoulos, A.
2015-04-01
Refraction is the main cause of geometric distortions in the case of two media photogrammetry. However, this effect cannot be compensated and corrected by a suitable camera calibration procedure (Georgopoulos and Agrafiotis, 2012). In addition, according to the literature (Lavest et al. 2000), when the camera is underwater, the effective focal length is approximately equal to that in the air multiplied by the refractive index of water. This ratio depends on the composition of the water (salinity, temperature, etc.) and usually ranges from 1.10 to 1.34. It seems, that in two media photogrammetry, the 1.33 factor used for clean water in underwater cases does not apply and the most probable relation of the effective camera constant to the one in air is depending of the percentages of air and water within the total camera-to-object distance. This paper examines this relation in detail, verifies it and develops it through the application of calibration methods using different test fields. In addition the current methodologies for underwater and two-media calibration are mentioned and the problem of two-media calibration is described and analysed.
Evaluation of elastic constants of materials using the frequency spectrum
Energy Technology Data Exchange (ETDEWEB)
Silva Neto, Ramiro J. da; Baroni, Douglas B.; Bittencourt, Marcelo de S.Q., E-mail: ramirobd@gmail.com [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Departamento de Materiais Nucleares. Laboratorio de Ultrassom
2015-07-01
The characterization of materials made with the support of non-destructive techniques has great importance in industrial applications. The ultrasonic techniques are distinguished by good resolution to measure small variations of wave velocities as a result of changes in the character suffered by a particular material. In general these ultrasonic techniques are studied in the time domain, which represents an experimental difficulties when thin materials are analyzed, as well as to attenuate the ultrasonic signal drastically. An ultrasonic technique that uses the frequency domain is used in this study aiming to provide good time measurements to calculate the elastic constants of the first order in an aluminum alloy 6351. With the aid of a statistical approach was possible to have good results of tests performed when compared by a time domain technique already well explored in Ultrasound works produced in the Nuclear Engineering Institute Laboratory (LABUS / IEN) and also presented in most of the package, in good agreement with the theoretical model established in literature and used to validate the experiment, which was found in the results with good approximation. The relevance of this work in the nuclear area is associated with the interest to know the mechanical properties of structural components of the nuclear industry, which is currently studied as a rule, resorting to the computer simulations or previously during the operation of the system. (author)
CAMERA CONSTANT IN THE CASE OF TWO MEDIA PHOTOGRAMMETRY
Directory of Open Access Journals (Sweden)
P. Agrafiotis
2015-04-01
Full Text Available Refraction is the main cause of geometric distortions in the case of two media photogrammetry. However, this effect cannot be compensated and corrected by a suitable camera calibration procedure (Georgopoulos and Agrafiotis, 2012. In addition, according to the literature (Lavest et al. 2000, when the camera is underwater, the effective focal length is approximately equal to that in the air multiplied by the refractive index of water. This ratio depends on the composition of the water (salinity, temperature, etc. and usually ranges from 1.10 to 1.34. It seems, that in two media photogrammetry, the 1.33 factor used for clean water in underwater cases does not apply and the most probable relation of the effective camera constant to the one in air is depending of the percentages of air and water within the total camera-to-object distance. This paper examines this relation in detail, verifies it and develops it through the application of calibration methods using different test fields. In addition the current methodologies for underwater and two-media calibration are mentioned and the problem of two-media calibration is described and analysed.
Evidence against solar influence on nuclear decay constants
Directory of Open Access Journals (Sweden)
S. Pommé
2016-10-01
Full Text Available The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements of mono-radionuclide sources were performed over periods from 200 days up to four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ from one data set to another and are attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of alpha, beta-minus, electron capture, and beta-plus decaying sources set an upper limit of 0.0006% to 0.008% to the amplitude of annual oscillations in the decay rate. Oscillations in phase with Earth's orbital distance to the Sun could not be observed within a 10−6 to 10−5 range of precision. There are also no apparent modulations over periods of weeks or months. Consequently, there is no indication of a natural impediment against sub-permille accuracy in half-life determinations, renormalisation of activity to a distant reference date, application of nuclear dating for archaeology, geo- and cosmochronology, nor in establishing the SI unit becquerel and seeking international equivalence of activity standards.
Evidence against solar influence on nuclear decay constants
Pommé, S.; Stroh, H.; Paepen, J.; Van Ammel, R.; Marouli, M.; Altzitzoglou, T.; Hult, M.; Kossert, K.; Nähle, O.; Schrader, H.; Juget, F.; Bailat, C.; Nedjadi, Y.; Bochud, F.; Buchillier, T.; Michotte, C.; Courte, S.; van Rooy, M. W.; van Staden, M. J.; Lubbe, J.; Simpson, B. R. S.; Fazio, A.; De Felice, P.; Jackson, T. W.; Van Wyngaardt, W. M.; Reinhard, M. I.; Golya, J.; Bourke, S.; Roy, T.; Galea, R.; Keightley, J. D.; Ferreira, K. M.; Collins, S. M.; Ceccatelli, A.; Unterweger, M.; Fitzgerald, R.; Bergeron, D. E.; Pibida, L.; Verheyen, L.; Bruggeman, M.; Vodenik, B.; Korun, M.; Chisté, V.; Amiot, M.-N.
2016-10-01
The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements of mono-radionuclide sources were performed over periods from 200 days up to four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ from one data set to another and are attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of alpha, beta-minus, electron capture, and beta-plus decaying sources set an upper limit of 0.0006% to 0.008% to the amplitude of annual oscillations in the decay rate. Oscillations in phase with Earth's orbital distance to the Sun could not be observed within a 10-6 to 10-5 range of precision. There are also no apparent modulations over periods of weeks or months. Consequently, there is no indication of a natural impediment against sub-permille accuracy in half-life determinations, renormalisation of activity to a distant reference date, application of nuclear dating for archaeology, geo- and cosmochronology, nor in establishing the SI unit becquerel and seeking international equivalence of activity standards.
Constant-Pressure Combustion Charts Including Effects of Diluent Addition
Turner, L Richard; Bogart, Donald
1949-01-01
Charts are presented for the calculation of (a) the final temperatures and the temperature changes involved in constant-pressure combustion processes of air and in products of combustion of air and hydrocarbon fuels, and (b) the quantity of hydrocarbon fuels required in order to attain a specified combustion temperature when water, alcohol, water-alcohol mixtures, liquid ammonia, liquid carbon dioxide, liquid nitrogen, liquid oxygen, or their mixtures are added to air as diluents or refrigerants. The ideal combustion process and combustion with incomplete heat release from the primary fuel and from combustible diluents are considered. The effect of preheating the mixture of air and diluents and the effect of an initial water-vapor content in the combustion air on the required fuel quantity are also included. The charts are applicable only to processes in which the final mixture is leaner than stoichiometric and at temperatures where dissociation is unimportant. A chart is also included to permit the calculation of the stoichiometric ratio of hydrocarbon fuel to air with diluent addition. The use of the charts is illustrated by numerical examples.
Planck intermediate results XXIV. Constraints on variations in fundamental constants
DEFF Research Database (Denmark)
Ade, P. A. R.; Aghanim, N.; Arnaud, M.;
2015-01-01
Any variation in the fundamental physical constants, more particularly in the fine structure constant, a, or in the mass of the electron, me, affects the recombination history of the Universe and cause an imprint on the cosmic microwave background angular power spectra. We show that the Planck data...... of the electron, me, and in the simultaneous variation of the two constants. We examine in detail the degeneracies between fundamental constants and the cosmological parameters, in order to compare the limits obtained from Planck and WMAP and to determine the constraining power gained by including other...
The 400-Hertz constant-speed electrical generation systems
Mcclung, R.
1982-01-01
Materials illustrating a presentation on 400 Hz constant speed generation systems are presented. The system features are outlined, components and functioning described, and display graphics illustrated.
An automated approach for finding variable-constant pairing bugs
DEFF Research Database (Denmark)
Lawall, Julia; Lo, David
2010-01-01
Named constants are used heavily in operating systems code, both as internal flags and in interactions with devices. Decision making within an operating system thus critically depends on the correct usage of these values. Nevertheless, compilers for the languages typically used in implementing...... operating systems provide little support for checking the usage of named constants. This affects correctness, when a constant is used in a context where its value is meaningless, and software maintenance, when a constant has the right value for its usage context but the wrong name. We propose a hybrid...
Large Capacity Constant Spring Support Hanger Design Optimization
Institute of Scientific and Technical Information of China (English)
HU Xian-wei
2012-01-01
This article discussed how to improve constant force performance of the large capacity constant spring support hangers. Large deviations have been found between product testing results and theoretical calculations after years of research and testing. The deviations mainly are caused by internal frictions inside the constant spring support hangers. By reducing or properly using internal frictions, consistent results between testing and theoretical calculation have been achieved. Based on product performance testing results recently, constant force performance of hangers has been improved greatly by adopting new methodology.
Negative Dielectric Constant Material Based on Ion Conducting Materials
Gordon, Keith L. (Inventor); Kang, Jin Ho (Inventor); Park, Cheol (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)
2014-01-01
Metamaterials or artificial negative index materials (NIMs) have generated great attention due to their unique and exotic electromagnetic properties. One exemplary negative dielectric constant material, which is an essential key for creating the NIMs, was developed by doping ions into a polymer, a protonated poly(benzimidazole) (PBI). The doped PBI showed a negative dielectric constant at megahertz (MHz) frequencies due to its reduced plasma frequency and an induction effect. The magnitude of the negative dielectric constant and the resonance frequency were tunable by doping concentration. The highly doped PBI showed larger absolute magnitude of negative dielectric constant at just above its resonance frequency than the less doped PBI.
An Einstein-Cartan Fine Structure Constant Definition
Directory of Open Access Journals (Sweden)
Stone R. A. Jr.
2010-01-01
Full Text Available The fine structure constant definition given in Stone R.A. Jr. Progress in Physics, 2010, v.1, 11-13 is compared to an Einstein-Cartan fine structure constant definition. It is shown that the Einstein-Cartan definition produces the correct pure theory value, just not the measure value. To produce the measured value, the pure theory Einstein-Cartan fine structure constant requires only the new variables and spin coupling of the fine structure constant definition in [1].
Institute of Scientific and Technical Information of China (English)
李飞
2015-01-01
In the underneath construction of a mine, the accurate collection of the wind speed is the key point to ensure the construction safety. Owing to such unique advantages as small size, light weight, fast response speed, tiny resistance loss and etc., Homework Hot-Wire wind speed sensor has been widely applied in construction operations inside the mine. Currently, what many transducers adopting is a kind of bridge affiliated by compensating components, which makes the probe structure further complicated and the consistency requirement for sensitive elements higher, meanwhile as the im⁃pact by the length of connecting wire is more obvious, it’s not suitable for the demands of the underground construction. Of the underground construction, when Homework Hot-Wire wind speed sensor is used for wind speed measurement un⁃der high temperature, in order to realize its constant temperature difference control, the article proposes to use platinum wire's thermoelectric effect to replace the bridge's temperature compensation, by doing so the structure of the probe can be simplified, and the response speed of the measurement will be promoted as well. Experiment proves the validity of this method in the process of construction, thereby, it can be promoted in practical applications.%矿下施工中对风速的准确采集是保证施工安全的关键。作业热线式风速传感器具有体积小、重量轻、响应速度快、阻力损失小等独特的优点，在矿下施工作业中得到广泛应用。目前许多传感器采用的是带有补偿元件的电桥方式，这使探头的结构进一步复杂化，对于敏感元件的一致性要求较高，受连接导线长度变化的影响较大，不适应井下施工的要求。矿下施工作业热线式风速传感器用于高温风速测量时，为了实现其定温差控制，本文利用铂丝的热电效应取代了电桥的温度补偿，简化了探头的结构，提高了测量的响应速度。实验证
Directory of Open Access Journals (Sweden)
Eryi Hu
2016-01-01
Full Text Available The ultrasonic nondestructive method is introduced into the elastic constants measurement of metal material. The extraction principle of Poisson’s ratio, elastic modulus, and shear modulus is deduced from the ultrasonic propagating equations with two kinds of vibration model of the elastic medium named ultrasonic longitudinal wave and transverse wave, respectively. The ultrasonic propagating velocity is measured by using the digital correlation technique between the ultrasonic original signal and the echo signal from the bottom surface, and then the elastic constants of the metal material are calculated. The feasibility of the correlation algorithm is verified by a simulation procedure. Finally, in order to obtain the stability of the elastic properties of different metal materials in a variable engineering application environment, the elastic constants of two kinds of metal materials in different temperature environment are measured by the proposed ultrasonic method.
Influx of CO2 from Soil Incubated Organic Residues at Constant Temperature
Directory of Open Access Journals (Sweden)
Shoukat Ali Abro
2016-06-01
Full Text Available Temperature induced CO2 from genotypic residue substances is still less understood. Two types of organic residues (wheat- maize were incubated at a constant temperature (25°C to determine the rate and cumulative influx of CO2 in laboratory experiment for 40 days. Further, the effect of surface and incorporated crop residues with and without phosphorus addition was also studied. Results revealed that mixing of crop residues increased CO2-C evolution significantly & emission rare was 37% higher than that of control. At constant temperature, soil mixed residues, had higher emission rates CO2-C than the residues superimposed. There was linear correlation of CO2-C influxed for phosphorus levels and residue application ways with entire incubation at constant temperature. The mixing of organic residues to soil enhanced SOC levels and biomass of microbially bound N; however to little degree ammonium (NH4-N and nitrate NO3-N nitrogen were decreased.
Elastic constants characterization on graphite at 500°C by the virtual fields method
Directory of Open Access Journals (Sweden)
Baoqiao Guo
2014-01-01
Full Text Available In this paper the elastic constants of graphite at elevated temperature were experimentally investigated by using the virtual fields method (VFM. A new method was presented for the characterization of mechanical properties at elevated temperature. The three-point bending tests were performed on graphite materials by an universal testing machine equipped with heating furnace. Based on the heterogeneous deformation fields measured by the digital image correlation (DIC technique, the elastic constants were then extracted by using VFM. The measurement results of the elastic constants at 500°C were obtained. The effect on the experimental results was also analyzed. The successful results verify the feasibility of using the proposed method to measure the properties of graphite at high temperature, and the proposed method is believed to have a good potential for further applications.
Energy Technology Data Exchange (ETDEWEB)
Caballero, Magdalena; Rubio, Rafael M [Departamento de Matematicas, Campus de Rabanales, Universidad de Cordoba, 14071 Cordoba (Spain); Romero, Alfonso, E-mail: magdalena.caballero@uco.es, E-mail: aromero@ugr.es, E-mail: rmrubio@uco.es [Departamento de Geometria y Topologia, Universidad de Granada, 18071 Granada (Spain)
2011-07-21
A new technique to study spacelike hypersurfaces of constant mean curvature in a spacetime which admits a timelike gradient conformal vector field is introduced. As an application, the leaves of the natural spacelike foliation of such spacetimes are characterized in some relevant cases. The global structure of this class of spacetimes is analyzed and the relation with its well-known subfamily of generalized Robertson-Walker spacetimes is exposed in detail. Moreover, some known uniqueness results for compact spacelike hypersurfaces of constant mean curvature in generalized Robertson-Walker spacetimes are widely extended. Finally, and as a consequence, several Calabi-Bernstein problems are solved obtaining all the entire solutions on a compact Riemannian manifold to the constant mean curvature spacelike hypersurface equation, under natural geometric assumptions.
Theory of space-charge polarization for determining ionic constants of electrolytic solutions.
Sawada, Atsushi
2007-06-14
A theoretical expression of the complex dielectric constant attributed to space-charge polarization has been derived under an electric field calculated using Poisson's equation considering the effects of bound charges on ions. The frequency dependence of the complex dielectric constant of chlorobenzene solutions doped with tetrabutylammonium tetraphenylborate (TBATPB) has been analyzed using the theoretical expression, and the impact of the bound charges on the complex dielectric constant has been clarified quantitatively in comparison with a theory that does not consider the effect of the bound charges. The Stokes radius of TBA+(=TPB-) determined by the present theory shows a good agreement with that determined by conductometry in the past; hence, the present theory should be applicable to the direct determination of the mobility of ion species in an electrolytic solution without the need to measure ionic limiting equivalent conductance and transport number.
Dynamical friction in constant density cores: a failure of the Chandrasekhar formula
Read, J I; Moore, B; Pontzen, A P; Lake, J S G; Goerdt, Tobias; Moore, Ben; Lake, Joachim Stadel & George
2006-01-01
Using analytic calculations and N-body simulations we show that in constant density (harmonic) cores, sinking satellites undergo an initial phase of very rapid (super-Chandrasekhar) dynamical friction, after which they experience no dynamical friction at all. For density profiles with a central power law profile of log-slope, $-\\alpha$, the infalling satellite heats the background and causes $\\alpha$ to decrease. For $\\alpha < 0.5$ initially, the satellite generates a small central constant density core and stalls as in the $\\alpha = 0$ case. We discuss some astrophysical applications of our results to decaying satellite orbits, galactic bars and mergers of supermassive black hole binaries. In a companion paper we show that a central constant density core can provide a natural solution to the timing problem for Fornax's globular clusters.
High dielectric constant, low loss and high photocatalytic activity in Gd doped ZnO systems
Divya, N. K.; Pradyumnan, P. P.
2017-01-01
Enhanced photocatalytic activity and high dielectric constant values are achieved by gadolinium (Gd) doping in ZnO. The changes that happened to the wurtzite structure of ZnO on doping are depicted in detail by using x-ray diffraction spectroscopy. The chemical composition is confirmed using energy dispersive x-ray spectroscopy (EDAX). The influence of Gd incorporation in the emission spectra of ZnO is analysed from photoluminescence studies. The photocatalytic activity enhancement occurred in ZnO system on Gd doping was explored by kinetic rate analysis. The optimum incorporation of Gd has enhanced the dielectric constant value and decreased the loss of pristine. The high dielectric constant value and low loss make the system suitable for large scale of applications in microelectronics. The work also proposes large scale synthesis of highly efficient fluorescent Gd doped ZnO photocatalysts.
Hoeck, Casper; Gotfredsen, Charlotte H.; Sørensen, Ole W.
2017-02-01
A novel method, Spin-State-Selective (S3) HMBC hetero, for accurate measurement of heteronuclear coupling constants is introduced. The method extends the S3 HMBC technique for measurement of homonuclear coupling constants by appending a pulse sequence element that interchanges the polarization in 13C-1H methine pairs. This amounts to converting the spin-state selectivity from 1H spin states to 13C spin states in the spectra of long-range coupled 1H spins, allowing convenient measurement of heteronuclear coupling constants similar to other S3 or E.COSY-type methods. As usual in this type of techniques, the accuracy of coupling constant measurement is independent of the size of the coupling constant of interest. The merits of the new method are demonstrated by application to vinyl acetate, the alkaloid strychnine, and the carbohydrate methyl β-maltoside.
Coakley, Kevin J.; Qu, Jifeng
2017-04-01
In the electronic measurement of the Boltzmann constant based on Johnson noise thermometry, the ratio of the power spectral densities of thermal noise across a resistor at the triple point of water, and pseudo-random noise synthetically generated by a quantum-accurate voltage-noise source is constant to within 1 part in a billion for frequencies up to 1 GHz. Given knowledge of this ratio, and the values of other parameters that are known or measured, one can determine the Boltzmann constant. Due, in part, to mismatch between transmission lines, the experimental ratio spectrum varies with frequency. We model this spectrum as an even polynomial function of frequency where the constant term in the polynomial determines the Boltzmann constant. When determining this constant (offset) from experimental data, the assumed complexity of the ratio spectrum model and the maximum frequency analyzed (fitting bandwidth) dramatically affects results. Here, we select the complexity of the model by cross-validation—a data-driven statistical learning method. For each of many fitting bandwidths, we determine the component of uncertainty of the offset term that accounts for random and systematic effects associated with imperfect knowledge of model complexity. We select the fitting bandwidth that minimizes this uncertainty. In the most recent measurement of the Boltzmann constant, results were determined, in part, by application of an earlier version of the method described here. Here, we extend the earlier analysis by considering a broader range of fitting bandwidths and quantify an additional component of uncertainty that accounts for imperfect performance of our fitting bandwidth selection method. For idealized simulated data with additive noise similar to experimental data, our method correctly selects the true complexity of the ratio spectrum model for all cases considered. A new analysis of data from the recent experiment yields evidence for a temporal trend in the offset
Energy Technology Data Exchange (ETDEWEB)
Costa, Ederson D' Martin; Lemes, Nelson Henrique Teixeira, E-mail: nelson.lemes@unifal-mg.edu.br [Instituto de Ciencias Exatas, Universidade Federal de Alfenas, Alfenas, MG (Brazil); Santos, Marcelo Henrique dos [Instituto de Ciencias Farmaceuticas, Universidade Federal de Alfenas, Alfenas, MG (Brazil); Braga, Joao Pedro [Departamento de Quimica, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)
2012-07-01
This work propose a recursive neural network to solve inverse equilibrium problem. The acidity constants of 7-epiclusianone in ethanol-water binary mixtures were determined from multiwavelength spectrophotometric data. A linear relationship between acidity constants and the % w/v of ethanol in the solvent mixture was observed. The proposed method efficiency is compared with the Simplex method, commonly used in nonlinear optimization techniques. The neural network method is simple, numerically stable and has a broad range of applicability. (author)
Impact of non-constant concentration exposure on lethality of inhaled hydrogen cyanide.
Sweeney, Lisa M; Sommerville, Douglas R; Channel, Stephen R
2014-03-01
The ten Berge model, also known as the toxic load model, is an empirical approach in hazard assessment modeling for estimating the relationship between the inhalation toxicity of a chemical and the exposure duration. The toxic load (TL) is normally expressed as a function of vapor concentration (C) and duration (t), with TL equaling C(n) × t being a typical form. Hypothetically, any combination of concentration and time that yields the same "toxic load" will give a constant biological response. These formulas have been developed and tested using controlled, constant concentration animal studies, but the validity of applying these assumptions to time-varying concentration profiles has not been tested. Experiments were designed to test the validity of the model under conditions of non-constant acute exposure. Male Sprague-Dawley rats inhaled constant or pulsed concentrations of hydrogen cyanide (HCN) generated in a nose-only exposure system for 5, 15, or 30 min. The observed lethality of HCN for the 11 different C versus t profiles was used to evaluate the ability of the model to adequately describe the lethality of HCN under the conditions of non-constant inhalation exposure. The model was found to be applicable under the tested conditions, with the exception of the median lethality of very brief, high concentration, discontinuous exposures.
Measuring Boltzmann's Constant with Carbon Dioxide
Ivanov, Dragia; Nikolov, Stefan
2013-01-01
In this paper we present two experiments to measure Boltzmann's constant--one of the fundamental constants of modern-day physics, which lies at the base of statistical mechanics and thermodynamics. The experiments use very basic theory, simple equipment and cheap and safe materials yet provide very precise results. They are very easy and…
Constant-Operating-Resistance Hot-Wire Probe
Stainback, P. C.
1985-01-01
Effects of lead-wire-resistance changes with temperature nullified. Constant-operating-resistance hot-wire probe uses two sets of leads. Exposed to identical conditions, comparison of resistance gives change in sensing element itself. Data taken in more convenient manner, with advantage of not having to constantly check for possible changes in lead resistance and consequently readjust potentiometer.
Nuclear Magnetic Resonance Coupling Constants and Electronic Structure in Molecules.
Venanzi, Thomas J.
1982-01-01
Theory of nuclear magnetic resonance spin-spin coupling constants and nature of the three types of coupling mechanisms contributing to the overall spin-spin coupling constant are reviewed, including carbon-carbon coupling (neither containing a lone pair of electrons) and carbon-nitrogen coupling (one containing a lone pair of electrons).…
Decay constants of p and d wave heavy light mesons
Energy Technology Data Exchange (ETDEWEB)
Veseli, Sinisa; Dunietz, Isard
1996-07-01
We investigate decay constants of P- and D-wave heavy-light mesons within the mock-meson approach. Numerical estimates are obtained using the relativistic quark model. We also comment on recent calculations of heavy-light pseudo-scalar and vector decay constants.