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1

Relaxation dynamics of a quantum Brownian particle in an ideal gas  

E-print Network

We show how the quantum analog of the Fokker-Planck equation for describing Brownian motion can be obtained as the diffusive limit of the quantum linear Boltzmann equation. The latter describes the quantum dynamics of a tracer particle in a dilute, ideal gas by means of a translation-covariant master equation. We discuss the type of approximations required to obtain the generalized form of the Caldeira-Leggett master equation, along with their physical justification. Microscopic expressions for the diffusion and relaxation coefficients are obtained by analyzing the limiting form of the equation in both the Schroedinger and the Heisenberg picture.

Bassano Vacchini; Klaus Hornberger

2007-06-29

2

Numerical solutions of ideal quantum gas dynamical flows governed by semiclassical ellipsoidal-statistical distribution.  

PubMed

The ideal quantum gas dynamics as manifested by the semiclassical ellipsoidal-statistical (ES) equilibrium distribution derived in Wu et al. (Wu et al. 2012 Proc. R. Soc. A 468, 1799-1823 (doi:10.1098/rspa.2011.0673)) is numerically studied for particles of three statistics. This anisotropic ES equilibrium distribution was derived using the maximum entropy principle and conserves the mass, momentum and energy, but differs from the standard Fermi-Dirac or Bose-Einstein distribution. The present numerical method combines the discrete velocity (or momentum) ordinate method in momentum space and the high-resolution shock-capturing method in physical space. A decoding procedure to obtain the necessary parameters for determining the ES distribution is also devised. Computations of two-dimensional Riemann problems are presented, and various contours of the quantities unique to this ES model are illustrated. The main flow features, such as shock waves, expansion waves and slip lines and their complex nonlinear interactions, are depicted and found to be consistent with existing calculations for a classical gas. PMID:24399919

Yang, Jaw-Yen; Yan, Chih-Yuan; Diaz, Manuel; Huang, Juan-Chen; Li, Zhihui; Zhang, Hanxin

2014-01-01

3

Numerical solutions of ideal quantum gas dynamical flows governed by semiclassical ellipsoidal-statistical distribution  

PubMed Central

The ideal quantum gas dynamics as manifested by the semiclassical ellipsoidal-statistical (ES) equilibrium distribution derived in Wu et al. (Wu et al. 2012 Proc. R. Soc. A 468, 1799–1823 (doi:10.1098/rspa.2011.0673)) is numerically studied for particles of three statistics. This anisotropic ES equilibrium distribution was derived using the maximum entropy principle and conserves the mass, momentum and energy, but differs from the standard Fermi–Dirac or Bose–Einstein distribution. The present numerical method combines the discrete velocity (or momentum) ordinate method in momentum space and the high-resolution shock-capturing method in physical space. A decoding procedure to obtain the necessary parameters for determining the ES distribution is also devised. Computations of two-dimensional Riemann problems are presented, and various contours of the quantities unique to this ES model are illustrated. The main flow features, such as shock waves, expansion waves and slip lines and their complex nonlinear interactions, are depicted and found to be consistent with existing calculations for a classical gas. PMID:24399919

Yang, Jaw-Yen; Yan, Chih-Yuan; Diaz, Manuel; Huang, Juan-Chen; Li, Zhihui; Zhang, Hanxin

2014-01-01

4

Increase of temperature of an ideal nondegenerate quantum gas in a suddenly expanding box due to energy quantization  

NASA Astrophysics Data System (ADS)

We show that due to energy quantization the temperature of an ideal nondegenerate quantum gas in a rectangular box always increases after a sudden expansion of the box and a subsequent thermalization. The maximal increment of temperature is proportional to the square root of the product of the initial absolute temperature by the energy of the first discrete quantum level, i.e., it is proportional to the first power of the Planck constant.

Dodonov, V. V.; Vieira Lopes, D. O.

2008-12-01

5

Einstein’s quantum theory of the monatomic ideal gas: non-statistical arguments for a new statistics  

Microsoft Academic Search

In this article, we analyze the third of three papers, in which Einstein presented his quantum theory of the ideal gas of\\u000a 1924–1925. Although it failed to attract the attention of Einstein’s contemporaries and although also today very few commentators\\u000a refer to it, we argue for its significance in the context of Einstein’s quantum researches. It contains an attempt to

Enric Pérez; Tilman Sauer

2010-01-01

6

Ideal Gas Law and the Gas Constant  

NSDL National Science Digital Library

This site offers an interactive tutorial in which students test the validity of the ideal gas law by measuring the pressure of a gas at various molar concentrations. The value of the gas constant is determined graphically. This tutorial is coupled to others to further guide the student to a better understanding of the principles which govern the behavior of gases.

David N. Blauch

7

On the ideal gas law Jacques Arnaud  

E-print Network

meaning of the ideal gas law. The mathematics is elementary. Mas Liron, F30440 Saint Martial, FranceOn the ideal gas law Jacques Arnaud , Laurent Chusseau , Fabrice Philippe May 13, 2011 Abstract. This law, called the "ideal gas law", is valid at any temperature (except at very low temperatures when

8

Chemical Potential for the Interacting Classical Gas and the Ideal Quantum Gas Obeying a Generalized Exclusion Principle  

ERIC Educational Resources Information Center

In this work, we address the concept of the chemical potential [mu] in classical and quantum gases towards the calculation of the equation of state [mu] = [mu](n, T) where n is the particle density and "T" the absolute temperature using the methods of equilibrium statistical mechanics. Two cases seldom discussed in elementary textbooks are…

Sevilla, F. J.; Olivares-Quiroz, L.

2012-01-01

9

ChemTeacher: Ideal Gas Law  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Ideal Gas Law page includes resources for teaching students about the definition and applications of the Ideal Gas Law.

2011-01-01

10

On the ideal gas law Jacques Arnaud  

E-print Network

of the barometric and ideal-gas laws. Mas Liron, F30440 Saint Martial, France Institut d'´Electronique du Sud, UMR nOn the ideal gas law Jacques Arnaud , Laurent Chusseau , Fabrice Philippe July 16, 2011 Abstract The air density on earth decays as a function of altitude z approximately according to an exp(-w z/)-law

Paris-Sud XI, Université de

11

Derivation of the Ideal Gas Law  

ERIC Educational Resources Information Center

Undergraduate and graduate physics and chemistry books usually state that combining the gas laws results in the ideal gas law. Leaving the derivation to the students implies that this should be a simple task, most likely a substitution. Boyle's law, Charles's law, and the Avogadro's principle are given under certain conditions; therefore, direct…

Laugier, Alexander; Garai, Jozsef

2007-01-01

12

Thermostatistics of the Polymeric Ideal Gas  

E-print Network

In this paper, we formulate statistical mechanics of the polymerized systems in the semiclassical regime. On the corresponding polymeric symplectic manifold, we set up a noncanonical coordinate system in which all of the polymeric effects are summarized in the density of states. Since we show that the polymeric effects only change the number of microstates of a statistical system, working in this coordinate is quite reasonable from the statistical point of view. The results show that the number of microstates decreases due to existence of an upper bound for the momentum of the test particles in the polymer framework. We obtain a corresponding canonical partition function by means of the deformed density of states. By using the partition function, we study thermodynamics of the ideal gas in the polymer framework and show that our results are in good agreement with those that arise from the full quantum consideration at high temperature, and they coincide with their usual counterpart in the limit of low temperature.

M. A. Gorji; K. Nozari; B. Vakili

2014-08-20

13

Ideal gas matching for thermal Galilean holography  

E-print Network

We exhibit a nonrelativistic ideal gas with a Kaluza-Klein tower of species, featuring a singular behavior of thermodynamic functions at zero chemical potential. In this way, we provide a qualitative match to the thermodynamics of recently found black holes in backgrounds with asymptotic nonrelativistic conformal symmetry.

Jose L. F. Barbon; Carlos A. Fuertes

2009-03-26

14

Generalized Ideal Gas Equations for Structureful Universe  

E-print Network

We have derived generalized ideal gas equations for a structureful universe consisting of all forms of matters. We have assumed a universe that contains superclusters. Superclusters are then made of clusters. Each cluster can be further divided into smaller ones and so on. We have derived an expression for the entropy of such a universe. Our model is rather independent of the geometry of the intermediate clusters. Our calculations are valid for a non-interacting universe within non-relativistic limits. We suggest that structure formation can reduce the expansion rate of the universe.

Shahid N. Afridi; Khalid Khan

2006-09-04

15

Statistical theory of ideal quantum measurement processes  

E-print Network

A minimalist theory of ideal quantum measurements is presented. The tested system S and the apparatus A are treated as a compound, isolated system, and the process is identified with the establishment of a generalised thermodynamic equilibrium. The results can be found on the level of thermodynamics, with a qualitative account of the relaxation mechanisms, but they can also be derived through detailed dynamic calculations based on standard quantum statistical mechanics. A quantum formalism without interpretation is used, where density operators encode knowledge about properties of a statistical ensemble, and also of its subensembles. The analysis of the measurement involves three steps. The first one deals with the dynamics of the density matrix of S+A associated with a large set of runs; it involves both the disappearance of the off-diagonal blocks (by decoherence or dephasing)and the establishment of correlations between S and the pointer of A in the diagonal blocks. The desired form for this density matrix at the end of the process is thus obtained, under some specified conditions to be fulfilled by the Hamiltonian. However, due to a quantum ambiguity, this is not sufficient to account for the occurrence of a well defined outcome for each individual run of the ensemble. Therefore, in a second step, a stronger result is established, concerning all possible subensembles of runs. Their associated density operators are shown to relax towards the required structure owing to a specific mechanism that acts near the end of the process. In the third step, the equations thus formally obtained are interpreted by means of postulates which relate macrophysics to microphysics and pertain more to A than to S. The properties currently attributed to ideal measurements are thereby recovered most economically, and the status of Born's rule is re-evaluated.

Armen E. Allahverdyan; Roger Balian; Theo M. Nieuwenhuizen

2015-02-24

16

Ideal Gas Carnot Engines and Efficiency Chemistry 223  

E-print Network

Ideal Gas Carnot Engines and Efficiency Chemistry 223 Fig. 1. The Carnot Cycle The Carnot engine of the thermal properties of gases, Joule considered the isothermal expansion of dilute gases using the apparatus depicted below: Fall Term, 2014 #12;Ideal Gas Carnot Engines and Efficiency -2- Chemistry 223 P=0

Ronis, David M.

17

Thermodynamical properties of a rotating ideal Bose gas Sebastian Kling*  

E-print Network

Thermodynamical properties of a rotating ideal Bose gas Sebastian Kling* Institut für Angewandte. The condensate was set into such a fast rotation that the centrifugal force in the corotating frame potential becomes sombrero shaped. We present an analysis for an ideal Bose gas that is confined

Pelster, Axel

18

Thermodynamic functions of lactams in the ideal gas state  

NASA Astrophysics Data System (ADS)

Thermodynamic functions (enthalpy, entropy, free energy, and heat capacity) of azacycloalkan-2-ones with ring sizes n = 4-8 in the ideal gas state are calculated by means of quantum chemistry and statistical physics, using an anharmonic approximation in the range of 298-1500 K with allowance for all known conformers and optical isomers. Equilibrium structures and total energies of lactams are calculated using the B3LYP/6-311++G(3 df, 3 pd), B3LYP/aug-cc-pVQZ, and MP2/6-311++G(3 df, 3 pd) methods, and the anharmonic frequencies of the fundamental vibrations of all the investigated structures were found via B3LYP/6-311++G(3 df, 3 pd).

Emel'yanenko, V. N.; Turovtsev, V. V.; Orlov, Yu. D.

2014-09-01

19

Local thermal equilibrium and ideal gas Stephani universes  

E-print Network

The Stephani universes that can be interpreted as an ideal gas evolving in local thermal equilibrium are determined. Five classes of thermodynamic schemes are admissible, which give rise to five classes of regular models and three classes of singular models. No Stephani universes exist representing an exact solution to a classical ideal gas (one for which the internal energy is proportional to the temperature). But some Stephani universes may approximate a classical ideal gas at first order in the temperature: all of them are obtained. Finally, some features about the physical behavior of the models are pointed out.

Bartolomé Coll; Joan Josep Ferrando

2004-06-30

20

Do the Particles of an Ideal Gas Collide?  

ERIC Educational Resources Information Center

Describes the collisional properties as a logically essential component of the ideal gas model since an actual intraparticle process cannot support observable anisotropic velocity distributions without collisions taken into account. (CC)

Lesk, Arthur M.

1974-01-01

21

Computer program for calculation of ideal gas thermodynamic data  

NASA Technical Reports Server (NTRS)

Computer program calculates ideal gas thermodynamic properties for any species for which molecular constant data is available. Partial functions and derivatives from formulas based on statistical mechanics are provided by the program which is written in FORTRAN 4 and MAP.

Gordon, S.; Mc Bride, B. J.

1968-01-01

22

The modified ASEP as a model of ideal gas  

NASA Astrophysics Data System (ADS)

A modified version of the ASEP model is interpreted as a two-dimensional model of ideal gas. Its properties are studied by simulating its behavior in different situations, using an animation program designed for that purpose.

Mironov, D.; Sossinsky, A.

2015-01-01

23

Statistical mechanics of ideal gas in the presence of minimal length and maximal momentum  

E-print Network

Various approaches to quantum gravity suggest that the fundamental volume of the phase space of the given space for representative points, means !0, should be modified. In this paper, we study the effects of this modification on the thermodynamics of an ideal gas within the micro canonical ensemble. For this end, we use a Generalized Uncertainty Principle (GUP) that admits both a minimal measurable length and a maximal momentum. Using this GUP causes decreasing the total number of the microstates of the system. In the first step, we calculate these reductions for classical ideal gas, and in the second step, we calculate these effects for ultra relativistic gas.

Homa Shababi

2013-10-11

24

Irreversibility and decoherence in an ideal gas  

E-print Network

Different models are described where non-interacting particles generate dissipative effective forces by the mixing of infinitely many soft normal modes. The effective action is calculated for these models within the Closed Time Path formalism. This is a well known scheme for quantum systems but its application in classical mechanics presents a new, more unified derivation and treatment of dissipative forces within classical and quantum physics.

Janos Polonyi

2015-02-13

25

Irreversibility and decoherence in an ideal gas  

E-print Network

Different models are described where non-interacting particles generate dissipative effective forces by the mixing of infinitely many soft normal modes. The effective action is calculated for these models within the Closed Time Path formalism. This is a well known scheme for quantum systems but its application in classical mechanics presents a new, more unified derivation and treatment of dissipative forces within classical and quantum physics.

Polonyi, Janos

2015-01-01

26

Lorentz covariant statistical mechanics and thermodynamics of the relativistic ideal gas and preferred frame  

SciTech Connect

The Lorentz covariant classical and quantum statistical mechanics and thermodynamics of an ideal relativistic gas of bradyons (particles slower than light), luxons (particles moving with the speed of light), and tachyons (hypothetical particles faster than light) is discussed. The Lorentz covariant formulation is based on the preferred frame approach which among others enables a consistent, free of paradoxes description of tachyons. The thermodynamic functions within the covariant approach are obtained both in the classical and quantum case.

Kowalski, K.; Rembielinski, J.; Smolinski, K. A. [Department of Theoretical Physics, University of Lodz, ul. Pomorska 149/153, 90-236 Lodz (Poland)

2007-08-15

27

Lorentz covariant statistical mechanics and thermodynamics of the relativistic ideal gas and preferred frame  

E-print Network

The Lorentz covariant classical and quantum statistical mechanics and thermodynamics of an ideal relativistic gas of bradyons (particles slower than light), luxons (particles moving with the speed of light) and tachyons (hypothetical particles faster than light) is discussed. The Lorentz covariant formulation is based on the preferred frame approach which among others enables consistent, free of paradoxes description of tachyons. The thermodynamic functions within the covariant approach are obtained both in classical and quantum case.

K. Kowalski; J. Rembielinski; K. A. Smolinski

2007-12-18

28

Direct simulation methods for compressible inviscid ideal-gas flow  

Microsoft Academic Search

Two novel schemes are proposed for the calculation of compressible flow of an ideal fluid. One method is the equilibrium analog of the well-known discrete-particle direct simulation Monte Carlo method for the treatment of nonequilibrium ideal-gas flows. The second follows from an analytical treatment of the model inertial-transport mechanisms inherent in the first scheme. Accounts of the methods are presented

D. I. Pullin

1980-01-01

29

Influence of the Heisenberg Principle on the Ideal Bose Gas  

E-print Network

The ideal Bose gas has two major shortcomings: at zero temperature, all the particles 'condense' at zero energy or momentum, thus violating the Heisenberg principle; the second is that the pressure below the critical point is independent of density resulting in zero incompressibility (or infinite isothermal compressibility) which is unphysical. We propose a modification of the ideal Bose gas to take into account the Heisenberg principle. This modification results in a finite (in)compressibility at all temperatures and densities. The main properties of the ideal Bose gas are preserved, i.e. the relation between the critical temperature and density, but the specific heat has a maximum at the critical temperature instead of a discontinuity. Of course interactions are crucial for both cases in order to describe actual physical systems.

Hua Zheng; Gianluca Giuliani; Aldo Bonasera

2013-03-26

30

Viscosity of an ideal relativistic quantum fluid: A perturbative study  

E-print Network

We show that a quantized ideal fluid will generally exhibit a small but non-zero viscosity due to the backreaction of quantum soundwaves on the background. We use an effective field theory expansion to estimate this viscosity to first order in perturbation theory. We discuss our results, and whether this estimate can be used to obtain a more model-independent estimate of the "quantum bound" on the viscosity of physical systems

Giorgio Torrieri

2012-02-14

31

Implications of Minimal Length Scale on the Statistical Mechanics of Ideal Gas  

E-print Network

Several alternative approaches to quantum gravity problem suggest the modification of the {\\it fundamental volume $\\omega_{0}$} of the accessible phase space for representative points. This modified fundamental volume has a novel momentum dependence. In this paper, we study the effects of this modification on the thermodynamics of an ideal gas within the microcanonical ensemble and using the generalized uncertainty principle(GUP). Although the induced modifications are important only in quantum gravity era, possible experimental manifestation of these effects may provides strong support for underlying quantum gravity proposal.

Kourosh Nozari; S. H. Mehdipour

2006-10-21

32

A Demonstration of Ideal Gas Principles Using a Football  

NASA Astrophysics Data System (ADS)

A class demonstration and cooperative learning activity in which the ideal gas law is applied to determine the volume of a football is described. The mass of an air-filled football is recorded at two or more pressures, and students are asked to use these data to solve problems involving the volume, pressure, and mass of the football and the molecular weight of the gas in the ball. Several sample questions are included.

Bare, William D.; Andrews, Lester

1999-05-01

33

Experimental Verification of Boyle's Law and the Ideal Gas Law  

ERIC Educational Resources Information Center

Two new experiments are offered concerning the experimental verification of Boyle's law and the ideal gas law. To carry out the experiments, glass tubes, water, a syringe and a metal manometer are used. The pressure of the saturated water vapour is taken into consideration. For educational purposes, the experiments are characterized by their…

Ivanov, Dragia Trifonov

2007-01-01

34

From Free Expansion to Abrupt Compression of an Ideal Gas  

ERIC Educational Resources Information Center

Using macroscopic thermodynamics, the general law for adiabatic processes carried out by an ideal gas was studied. It was shown that the process reversibility is characterized by the adiabatic reversibility coefficient r, in the range 0 [less than or equal] r [less than or equal] 1 for expansions and r [greater than or equal] 1 for compressions.…

Anacleto, Joaquim; Pereira, Mario G.

2009-01-01

35

Thermodynamics of Ideal Gas in Doubly Special Relativity  

E-print Network

We study thermodynamics of an ideal gas in Doubly Special Relativity. New type of special functions (which we call Incomplete Modified Bessel functions) emerge. We obtain a series solution for the partition function and derive thermodynamic quantities. We observe that DSR thermodynamics is non-perturbative in the SR and massless limits. A stiffer equation of state is found.

Nitin Chandra; Sandeep Chatterjee

2012-02-22

36

40 CFR 1065.645 - Amount of water in an ideal gas.  

Code of Federal Regulations, 2012 CFR

...false Amount of water in an ideal gas... AIR POLLUTION CONTROLS ENGINE-TESTING...645 Amount of water in an ideal gas...the New Kelvin Temperature Scale... = saturation temperature of water at measured...

2012-07-01

37

40 CFR 1065.645 - Amount of water in an ideal gas.  

Code of Federal Regulations, 2013 CFR

...false Amount of water in an ideal gas... AIR POLLUTION CONTROLS ENGINE-TESTING...645 Amount of water in an ideal gas...the New Kelvin Temperature Scale... = saturation temperature of water at measured...

2013-07-01

38

40 CFR 1065.645 - Amount of water in an ideal gas.  

Code of Federal Regulations, 2014 CFR

...false Amount of water in an ideal gas... AIR POLLUTION CONTROLS ENGINE-TESTING...645 Amount of water in an ideal gas...humidity and dry bulb temperature measurements...super-cooled water at ambient temperatures from (?50...

2014-07-01

39

40 CFR 1065.645 - Amount of water in an ideal gas.  

Code of Federal Regulations, 2011 CFR

...false Amount of water in an ideal gas... AIR POLLUTION CONTROLS ENGINE-TESTING...645 Amount of water in an ideal gas...given saturation temperature condition, T... = saturation temperature of water at measured...

2011-07-01

40

Effect of the Minimal Length on Bose—Einstein Condensation in the Relativistic Ideal Bose Gas  

NASA Astrophysics Data System (ADS)

Based on the generalized uncertainty principle (GUP), the critical temperature and the Helmholtz free energy of Bose—Einstein condensation (BEC) in the relativistic ideal Bose gas are investigated. At the non-relativistic limit and the ultra-relativistic limit, we calculate the analytical form of the shifts of the critical temperature and the Helmholtz free energy caused by weak quantum gravitational effects. The exact numerical results of these shifts are obtained. Quantum gravity effects lift the critical temperature of BEC. By measuring the shift of the critical temperature, we can constrain the deformation parameter ?0. Furthermore, at lower densities, omitting quantum gravitational effects may lead to a metastable state while at sufficiently high densities, quantum gravitational effects tend to make BEC unstable. Using the numerical methods, the stable-unstable transition temperature is found.

Zhang, Xiu-Ming; Tian, Chi

2015-01-01

41

Microeconomics of the ideal gas like market models  

NASA Astrophysics Data System (ADS)

We develop a framework based on microeconomic theory from which the ideal gas like market models can be addressed. A kinetic exchange model based on that framework is proposed and its distributional features have been studied by considering its moments. Next, we derive the moments of the CC model (Eur. Phys. J. B 17 (2000) 167) as well. Some precise solutions are obtained which conform with the solutions obtained earlier. Finally, an output market is introduced with global price determination in the model with some necessary modifications.

Chakrabarti, Anindya S.; Chakrabarti, Bikas K.

2009-10-01

42

An ideal gas approach to classify countries using financial indices  

NASA Astrophysics Data System (ADS)

Traditionally, countries’ development is classified based on several features that can be related to economic and social factors. However, this classification task is costly due to the difficulty of obtaining those features. We propose a method to classify countries based on financial indices using an ideal gas model. The probability density function (pdf) of the return series of the financial indices is used to characterize the fluctuation of a market. Based on the pdf, the volatility and the B coefficient, which describe the behavior of world markets, are estimated. The evaluation procedure uses 34 indices from developed and developing countries. The results show that the proposed method is an accurate, fast and low-cost computational alternative to the classifications provided by traditional organizations.

de Mattos Neto, Paulo S. G.; Cavalcanti, George D. C.; Madeiro, Francisco; Ferreira, Tiago A. E.

2013-01-01

43

Spectral Stability of Ideal-Gas Shock Layers  

NASA Astrophysics Data System (ADS)

Extending recent results in the isentropic case, we use a combination of asymptotic ODE estimates and numerical Evans-function computations to examine the spectral stability of shock-wave solutions of the compressible Navier-Stokes equations with ideal gas equation of state. Our main results are that, in appropriately rescaled coordinates, the Evans function associated with the linearized operator about the wave (i) converges in the large-amplitude limit to the Evans function for a limiting shock profile of the same equations, for which internal energy vanishes at one end state; and (ii) has no unstable (positive real part) zeros outside a uniform ball |?| ? ?. Thus, the rescaled eigenvalue ODE for the set of all shock waves, augmented with the (nonphysical) limiting case, form a compact family of boundary-value problems that can be conveniently investigated numerically. An extensive numerical Evans-function study yields one-dimensional spectral stability, independent of amplitude, for gas constant ? in [1.2, 3] and ratio ?/? of heat conduction to viscosity coefficient within [0.2, 5] ( ? ? 1.4, ?/? ? 1.47 for air). Other values may be treated similarly but were not considered. The method of analysis extends also to the multi-dimensional case, a direction that we shall pursue in a future work.

Humpherys, Jeffrey; Lyng, Gregory; Zumbrun, Kevin

2009-12-01

44

Scaling Dynamics of a Massive Piston in a Cube Filled With Ideal Gas: Exact Results  

E-print Network

Scaling Dynamics of a Massive Piston in a Cube Filled With Ideal Gas: Exact Results N. Chernov 1 of a piston in a cubical container of large size L filled with an ideal gas. The piston has mass M # L 2 heuristically that the motion of the piston and the one particle distribution of the gas satisfy autonomous

45

Suppression of Density Fluctuations in a Quantum Degenerate Fermi Gas  

NASA Astrophysics Data System (ADS)

We study density profiles of an ideal Fermi gas and observe Pauli suppression of density fluctuations (atom shot noise) for cold clouds deep in the quantum degenerate regime. Strong suppression is observed for probe volumes containing more than 10 000 atoms. Measuring the level of suppression provides sensitive thermometry at low temperatures. After this method of sensitive noise measurements has been validated with an ideal Fermi gas, it can now be applied to characterize phase transitions in strongly correlated many-body systems.

Sanner, Christian; Su, Edward J.; Keshet, Aviv; Gommers, Ralf; Shin, Yong-Il; Huang, Wujie; Ketterle, Wolfgang

2010-07-01

46

Quantum arrival and dwell times via idealized clocks  

SciTech Connect

A number of approaches to the problem of defining arrival- and dwell-time probabilities in quantum theory makes use of idealized models of clocks. An interesting question is the extent to which the probabilities obtained in this way are related to standard semiclassical results. In this paper, we explore this question using a reasonably general clock model, solved using path-integral methods. We find that, in the weak-coupling regime, where the energy of the clock is much less than the energy of the particle it is measuring, the probability for the clock pointer can be expressed in terms of the probability current in the case of arrival times, and the dwell-time operator in the case of dwell times, the expected semiclassical results. In the regime of strong system-clock coupling, we find that the arrival-time probability is proportional to the kinetic-energy density, consistent with an earlier model involving a complex potential. We argue that, properly normalized, this may be the generically expected result in this regime. We show that these conclusions are largely independent of the form of the clock Hamiltonian.

Yearsley, J. M.; Downs, D. A.; Halliwell, J. J.; Hashagen, A. K. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

2011-08-15

47

Scaling Dynamics of a Massive Piston in a Cube Filled With Ideal Gas: Exact Results  

E-print Network

Scaling Dynamics of a Massive Piston in a Cube Filled With Ideal Gas: Exact Results N. Chernov1 65th birthday Abstract We continue the study of the time evolution of a system consisting of a piston in a cubical container of large size L filled with an ideal gas. The piston has mass M L2 and undergoes

Chernov, Nikolai

48

Dynamics of a Massive Piston in an Ideal Gas N. Chernov1,4  

E-print Network

Dynamics of a Massive Piston in an Ideal Gas N. Chernov1,4 , J. L. Lebowitz2,4 , and Ya. Sinai3 January 1, 2003 Abstract We study a dynamical system consisting of a massive piston in a cubical con- tainer of large size L filled with an ideal gas. The piston has mass M L2 and undergoes elastic

49

Ideal gas thermodynamic properties for the phenyl, phenoxy, and o-biphenyl radicals  

NASA Technical Reports Server (NTRS)

Ideal gas thermodynamic properties of the phenyl and o-biphenyl radicals, their deuterated analogs and the phenoxy radical were calculated to 5000 K using estimated vibrational frequencies and structures. The ideal gas thermodynamic properties of benzene, biphenyl, their deuterated analogs and phenyl were also calculated.

Burcat, A.; Zeleznik, F. J.; Mcbride, B. J.

1985-01-01

50

Quantum Afterburner: Improving the Efficiency of an Ideal Heat Engine  

Microsoft Academic Search

By using a laser and maser in tandem, it is possible to obtain laser action in the hot exhaust gases of a heat engine. Such a ``quantum afterburner'' involves the internal quantum states of the working molecules as well as the techniques of cavity quantum electrodynamics and is therefore in the domain of quantum thermodynamics. It is shown that Otto

Marlan O. Scully

2002-01-01

51

Steady flow around a plane cascade by an ideal gas  

NASA Astrophysics Data System (ADS)

The steady separation-free flow around a flat cascade by an ideal gas is discussed. Most of the attention is devoted to blocking regimes with a supersonic velocity in the entire flow and its subsonic component normal to the front of the cascade. A “directing action” of the cascade (the direction of the velocity and the Mach number of the advancing flow turn out to be related) is exhibited in these regimes which is a consequence of an independence of the flow in front of the cascade of the conditions behind it [1 5]. The most widespread method of their calculation [3, 4, 6] is based on the method of characteristics with establishment of the flow outside the cascade in a timelike coordinate. Although the integrated conservation laws also permit finding the parameters at infinity, the numerical construction of as long-range fields as desired with periodic sequences of attenuating discontinuities is practically impossible. The approximation of nonlinear acoustics (ANA) [7, 8] is justified here, as it is very effective in such problems [8 12]. A combination of ANA, the integrated conservation laws, and establishment in a calculation according to [13, 14] with isolation of the discontinuities has been realized in [5] for the construction of a solution on the entrance section of a cascade and everywhere in front of it. Below the method of [5] is extended to the entire flow and simplified even more. The flow on the entrance section of the cascade is, just as in [3], found in the approximation of a simple wave, in the rest of it and in a finite strip behind it-the flow is found with the help of the “straight-through” version of the scheme of [13, 14], and in the “long-range field”-in the ANA. A simpler version is proposed. In it ANA is applied outside the cascade and the linear theory is applied inside the cascade. Examples of the calculations are given. Similarity laws are formulated for all the regimes of streamline flow.

Kraiko, A. N.; Shironosov, V. A.; Shironosova, E. Ya.

1984-11-01

52

Ideality in a Fiber-Taper-Coupled Microresonator System for Application to Cavity Quantum Electrodynamics  

Microsoft Academic Search

The ability to achieve near lossless coupling between a waveguide and a resonator is fundamental to many quantum-optical studies as well as to practical applications of such structures. The nature of loss at the junction is described by a figure of merit called ideality. It is shown here that under appropriate conditions ideality in excess of 99.97% is possible using

S. Spillane; T. Kippenberg; K. Vahala

2003-01-01

53

Reynolds and Favre-averaged rapid distortion theory for compressible, ideal-gas turbulence  

E-print Network

Compressible ideal-gas turbulence subjected to homogeneous shear is investigated at the rapid distortion limit. Specific issues addressed are (i) the interaction between kinetic and internal energies and role of pressure-dilatation; (ii...

Lavin, Tucker Alan

2007-09-17

54

The Ideal Gas and Real Gas Heat Capacity of Sodium Atoms  

NASA Astrophysics Data System (ADS)

The ideal gas heat capacity of sodium atoms in the vapor phase is calculated to high temperatures using statistical mechanics. Since there are, in principle, an infinite number of atomic energy levels, the partition function and the heat capacity will grow very large unless the summation over energy levels is constrained as temperature increases. At higher temperatures, the increasing size of the atoms, which is a consequence of the increased population of highly excited energy levels, is used as a mechanism for limiting the summation over energy levels. The "" and "Bethe" procedures for cutting off the summation over energy levels will be discussed, and the results obtained using the two methods will be compared. In addition, although experimental information is available about lower atomic energy levels and some theoretical calculations are available for excited energy levels, information is lacking for most individual atomic states associated with highly excited energy levels. A "fill" procedure for approximating the energy of the unknown states will be discussed. Sodium vapor will also be considered to be a real gas that obeys the virial equation of state. The first non-ideal term in the power series expansion of the heat capacity in terms of virial coefficients involves the second virial coefficient, . This depends on the interaction potential energy between two sodium atoms, i.e., the potential energy curves for the sodium dimer. Accurate interaction potential energies can be obtained from either experimental or theoretical information for the lowest ten electronic states of the sodium dimer. These are used to calculate for each state, and the averaged value of for all ten states is used to calculate the non-ideal contribution to the heat capacity of sodium atoms as a function of temperature.

Biolsi, Louis

2014-10-01

55

Performance of a multilevel quantum heat engine of an ideal N-particle Fermi system.  

PubMed

We generalize the quantum heat engine (QHE) model which was first proposed by Bender et al. [J. Phys. A 33, 4427 (2000)] to the case in which an ideal Fermi gas with an arbitrary number N of particles in a box trap is used as the working substance. Besides two quantum adiabatic processes, the engine model contains two isoenergetic processes, during which the particles are coupled to energy baths at a high constant energy E(h) and a low constant energy E(c), respectively. Directly employing the finite-time thermodynamics, we find that the power output is enhanced by increasing particle number N (or decreasing minimum trap size L(A)) for given L(A) (or N), without reduction in the efficiency. By use of global optimization, the efficiency at possible maximum power output (EPMP) is found to be universal and independent of any parameter contained in the engine model. For an engine model with any particle-number N, the efficiency at maximum power output (EMP) can be determined under the condition that it should be closest to the EPMP. Moreover, we extend the heat engine to a more general multilevel engine model with an arbitrary 1D power-law potential. Comparison between our engine model and the Carnot cycle shows that, under the same conditions, the efficiency ? = 1 - E(c)/E(h) of the engine cycle is bounded from above the Carnot value ?(c) =1 - T(c)/T(h). PMID:23005748

Wang, Rui; Wang, Jianhui; He, Jizhou; Ma, Yongli

2012-08-01

56

Performance of a multilevel quantum heat engine of an ideal N-particle Fermi system  

NASA Astrophysics Data System (ADS)

We generalize the quantum heat engine (QHE) model which was first proposed by Bender [J. Phys. A10.1088/0305-4470/33/24/302 33, 4427 (2000)] to the case in which an ideal Fermi gas with an arbitrary number N of particles in a box trap is used as the working substance. Besides two quantum adiabatic processes, the engine model contains two isoenergetic processes, during which the particles are coupled to energy baths at a high constant energy Eh and a low constant energy Ec, respectively. Directly employing the finite-time thermodynamics, we find that the power output is enhanced by increasing particle number N (or decreasing minimum trap size LA) for given LA (or N), without reduction in the efficiency. By use of global optimization, the efficiency at possible maximum power output (EPMP) is found to be universal and independent of any parameter contained in the engine model. For an engine model with any particle-number N, the efficiency at maximum power output (EMP) can be determined under the condition that it should be closest to the EPMP. Moreover, we extend the heat engine to a more general multilevel engine model with an arbitrary 1D power-law potential. Comparison between our engine model and the Carnot cycle shows that, under the same conditions, the efficiency ?=1-(Ec)/(Eh) of the engine cycle is bounded from above the Carnot value ?c=1-(Tc)/(Th).

Wang, Rui; Wang, Jianhui; He, Jizhou; Ma, Yongli

2012-08-01

57

OBSERVATION OF IDEAL DARK-CURRENT BEHAVIOUR IN STRAIN-BALANCED QUANTUM WELL SOLAR CELLS  

Microsoft Academic Search

A number of strain-balanced quantum well solar cells with different well number and well depths have been studied. The dark-currents have been measured and the ideality n ~ 2 region fitted with a model based on Shockley-Hall-Read recombination with only one fitting parameter. Ideality n = 1 behaviour is observed at concentrator current levels. The intercept of this dark current

K. W. J. Barnham; I. M. Ballard; D. B. Bushnell; J. P. Connolly; R. Day; N. J. Ekins-Daukes; D. C. Johnson; C. Lim; M. Lynch; M. Mazzer; T. N. D. Tibbits; C. Calder; G. Hill; J. S. Roberts

58

Influence of quantum degeneracy on the performance of a gas Stirling engine cycle  

NASA Astrophysics Data System (ADS)

Based on the state equation of an ideal quantum gas, the regenerative loss of a Stirling engine cycle working with an ideal quantum gas is calculated. Thermal efficiency of the cycle is derived. Furthermore, under the condition of quantum degeneracy, several special thermal efficiencies are discussed. Ratios of thermal efficiencies versus the temperature ratio and volume ratio of the cycle are made. It is found that the thermal efficiency of the cycle not only depends on high and low temperatures but also on maximum and minimum volumes. In a classical gas state the thermal efficiency of the cycle is equal to that of the Carnot cycle. In an ideal quantum gas state the thermal efficiency of the cycle is smaller than that of the Carnot cycle. This will be significant for deeper understanding of the gas Stirling engine cycle.

He, Ji-Zhou; Mao, Zhi-Yuan; Wang, Jian-Hui

2006-09-01

59

A Unified Theory of Non-Ideal Gas Lattice Boltzmann Models  

NASA Technical Reports Server (NTRS)

A non-ideal gas lattice Boltzmann model is directly derived, in an a priori fashion, from the Enskog equation for dense gases. The model is rigorously obtained by a systematic procedure to discretize the Enskog equation (in the presence of an external force) in both phase space and time. The lattice Boltzmann model derived here is thermodynamically consistent and is free of the defects which exist in previous lattice Boltzmann models for non-ideal gases. The existing lattice Boltzmann models for non-ideal gases are analyzed and compared with the model derived here.

Luo, Li-Shi

1998-01-01

60

Growth and decay of acceleration waves in non-ideal gas flow with radiative heat transfer  

NASA Astrophysics Data System (ADS)

The present paper is concerned with the study of the propagation of acceleration waves along the characteristic path in a non-ideal gas flow with effect of radiative heat transfer. It is shown that a linear solution in the characteristic plane can exhibit non-linear behavior in the physical plane. It is also investigated as to how the radiative heat transfer under the optically thin limit will affect the formation of shock in planer, cylindrical and spherically symmetric flows. We conclude that there exists critical amplitude such that any compressive waves with initial amplitude greater than the critical one terminate into shock waves while an initial amplitude less than the critical one results in the decay of the disturbance. The critical time for shock formation has been computed. In this paper we also compare/contrast the nature of solution in ideal and non ideal gas flows.

Singh, Lal P.; Singh, Raghwendra; Ram, Subedar

2012-09-01

61

Seeing zeros of random polynomials: quantized vortices in the ideal Bose gas  

E-print Network

We propose a physical system allowing one to experimentally observe the distribution of the complex zeros of a random polynomial. We consider a degenerate, rotating, quasi-ideal atomic Bose gas prepared in the lowest Landau level. Thermal fluctuations provide the randomness of the bosonic field and of the locations of the vortex cores. These vortices can be mapped to zeros of random polynomials, and observed in the density profile of the gas.

Yvan Castin; Zoran Hadzibabic; Sabine Stock; Jean Dalibard; Sandro Stringari

2005-11-14

62

Kinetic Models for Adiabatic Reversible Expansion of a Monatomic Ideal Gas.  

ERIC Educational Resources Information Center

A fixed amount of an ideal gas is confined in an adiabatic cylinder and piston device. The relation between temperature and volume in initial/final phases can be derived from the first law of thermodynamics. However, the relation can also be derived based on kinetic models. Several of these models are discussed. (JN)

Chang, On-Kok

1983-01-01

63

Dynamics of a Massive Piston in an Ideal Gas: Oscillatory Motion and Approach to Equilibrium  

E-print Network

Dynamics of a Massive Piston in an Ideal Gas: Oscillatory Motion and Approach to Equilibrium N confined to a cube of size L3 divided into two parts by a piston with mass ML L2 which can only move and a stationary piston, we find that (a) after an initial quiescent period the system becomes unstable

Chernov, Nikolai

64

Dynamics of a Massive Piston in an Ideal Gas: Oscillatory Motion and Approach to Equilibrium  

E-print Network

Dynamics of a Massive Piston in an Ideal Gas: Oscillatory Motion and Approach to Equilibrium N confined to a cube of size L 3 divided into two parts by a piston with mass ML # L 2 which can only move and a stationary piston, we find that (a) after an initial quiescent period the system becomes unstable

65

Cooking under Pressure: Applying the Ideal Gas Law in the Kitchen  

ERIC Educational Resources Information Center

This case study uses a daily cooking scenario to demonstrate how the boiling point of water is directly related to the external pressures in order to reinforce the concepts of boiling and boiling point, apply ideal gas law, and relate chemical reaction rates with temperatures. It also extends its teaching to autoclaves used to destroy…

Chen, Ling; Anderson, Jennifer Y.; Wang, Diane R.

2010-01-01

66

Case Study: Cooking Under Pressure--Applying the Ideal Gas Law in the Kitchen  

NSDL National Science Digital Library

This case study uses a daily cooking scenario to demonstrate how the boiling point of water is directly related to the external pressures in order to reinforce the concepts of boiling and boiling point, apply ideal gas law, and relate chemical reaction ra

Diane R. Wang

2010-11-01

67

Ballistic and diffusive dynamics in a two-dimensional ideal gas of macroscopic chaotic Faraday waves  

NASA Astrophysics Data System (ADS)

We have constructed a macroscopic driven system of chaotic Faraday waves whose statistical mechanics, we find, are surprisingly simple, mimicking those of a thermal gas. We use real-time tracking of a single floating probe, energy equipartition, and the Stokes-Einstein relation to define and measure a pseudotemperature and diffusion constant and then self-consistently determine a coefficient of viscous friction for a test particle in this pseudothermal gas. Because of its simplicity, this system can serve as a model for direct experimental investigation of nonequilibrium statistical mechanics, much as the ideal gas epitomizes equilibrium statistical mechanics.

Welch, Kyle J.; Hastings-Hauss, Isaac; Parthasarathy, Raghuveer; Corwin, Eric I.

2014-04-01

68

Ballistic and diffusive dynamics in a two-dimensional ideal gas of macroscopic chaotic Faraday waves.  

PubMed

We have constructed a macroscopic driven system of chaotic Faraday waves whose statistical mechanics, we find, are surprisingly simple, mimicking those of a thermal gas. We use real-time tracking of a single floating probe, energy equipartition, and the Stokes-Einstein relation to define and measure a pseudotemperature and diffusion constant and then self-consistently determine a coefficient of viscous friction for a test particle in this pseudothermal gas. Because of its simplicity, this system can serve as a model for direct experimental investigation of nonequilibrium statistical mechanics, much as the ideal gas epitomizes equilibrium statistical mechanics. PMID:24827228

Welch, Kyle J; Hastings-Hauss, Isaac; Parthasarathy, Raghuveer; Corwin, Eric I

2014-04-01

69

Using Rubber-Elastic Material-Ideal Gas Analogies To Teach Introductory Thermodynamics. Part II: The Laws of Thermodynamics.  

ERIC Educational Resources Information Center

Describes the laws of thermodynamics as a supplement to an introductory thermodynamics undergraduate course. Uses rubber-elastic materials (REM) which have strong analogies to the concept of ideal gas. Provides examples of the analogies between ideal gas and REM and mathematical analogies. (YDS)

Smith, Brent

2002-01-01

70

On a slow drift of a massive piston in an ideal gas that remains at mechanical equilibrium  

E-print Network

On a slow drift of a massive piston in an ideal gas that remains at mechanical equilibrium N@math.uab.edu Fax: 1-205-934-9025 February 18, 2004 Abstract We consider a heavy piston in an infinite cylinder surrounded by ideal gases on both sides. The piston moves under elastic collisions with gas atoms. We assume

Chernov, Nikolai

71

Using Rubber-Elastic Material-Ideal Gas Analogies To Teach Introductory Thermodynamics. Part I: Equations of State.  

ERIC Educational Resources Information Center

Describes equations of state as a supplement to an introductory thermodynamics undergraduate course. Uses rubber-elastic materials (REM) which have strong analogies to the concept of an ideal gas and explains the molar basis of REM. Provides examples of the analogies between ideal gas and REM and mathematical analogies. (Contains 22 references.)…

Smith, Brent

2002-01-01

72

Co-ideal quantum affine algebra and boundary scattering of the deformed Hubbard chain  

Microsoft Academic Search

We consider boundary scattering for a semi-infinite one-dimensional deformed Hubbard chain with boundary conditions of the same type as for the Y = 0 giant graviton in the AdS\\/CFT correspondence. We show that the recently constructed quantum affine algebra of the deformed Hubbard chain has a co-ideal subalgebra which is consistent with the reflection (boundary Yang–Baxter) equation. We derive the

Marius de Leeuw; Takuya Matsumoto; Vidas Regelskis

2012-01-01

73

Evolutionary behavior of weak shocks in a non-ideal gas  

NASA Astrophysics Data System (ADS)

Except some empirical methods, which have been developed in the past, no analytical method exists to describe the evolutionary behavior of a shock wave without limiting its strength. In this paper, we have derived a system of transport equations for the shock strength and the induced continuity. We generate a completely intrinsic description of plane, cylindrical, and spherical shock waves of weak strength, propagating into a non-ideal gas. It is shown that for a weak shock, the disturbance evolves like an acceleration wave at the leading order. For a weak shock, we may assume that [InlineEquation not available: see fulltext.]. We have considered a case when the effect of the first order-induced discontinuity or the disturbances that overtook the shock from behind are strong, i.e., [ p x ] = O(1). The evolutionary behavior of the weak shocks in a non-ideal gas is described using the truncation approximation.

Arora, Rajan; Siddiqui, Mohd Junaid

2013-03-01

74

Lorentz-violating effects in the Bose-Einstein condensation of an ideal bosonic gas  

NASA Astrophysics Data System (ADS)

We have studied the effects of Lorentz-violation in the Bose-Einstein condensation (BEC) of an ideal boson gas, by assessing both the nonrelativistic and ultrarelativistic limits. Our model describes a massive complex scalar field coupled to a CPT-even and Lorentz-violating background. We first analyze the nonrelativistic case, at this level by using experimental data, we obtain upper-bounds for some LIV parameters. In the sequel, we have constructed the partition function for the relativistic ideal boson gas which to be able of a consistent description requires the imposition of severe restrictions on some LIV coefficients. In both cases, we have demonstrated that the LIV contributions are contained in an overall factor, which multiplies almost all thermodynamical properties. An exception is the fraction of the condensed particles.

Casana, Rodolfo; da Silva, Kleber A. T.

2015-02-01

75

Critical behavior of the ideal-gas Bose-Einstein condensation in the Apollonian network.  

PubMed

We show that the ideal Boson gas displays a finite-temperature Bose-Einstein condensation transition in the complex Apollonian network exhibiting scale-free, small-world, and hierarchical properties. The single-particle tight-binding Hamiltonian with properly rescaled hopping amplitudes has a fractal-like energy spectrum. The energy spectrum is analytically demonstrated to be generated by a nonlinear mapping transformation. A finite-size scaling analysis over several orders of magnitudes of network sizes is shown to provide precise estimates for the exponents characterizing the condensed fraction, correlation size, and specific heat. The critical exponents, as well as the power-law behavior of the density of states at the bottom of the band, are similar to those of the ideal Boson gas in lattices with spectral dimension d(s)=2ln(3)/ln(9/5)~/=3.74. PMID:24032807

de Oliveira, I N; dos Santos, T B; de Moura, F A B F; Lyra, M L; Serva, M

2013-08-01

76

Evolution of weak discontinuities in a non-ideal radiating gas  

NASA Astrophysics Data System (ADS)

A method of wavefront analysis is used to study the formation of shock waves in a two-dimensional steady supersonic flow of a non-ideal radiating gas past plane and axisymmetric bodies. The gas is taken to be sufficiently hot for the effect of thermal radiation to be significant, which is, of course, treated by the optically thin approximation to the radiative transfer equation. Transport equations, which lead to the determination of the shock formation distance and also to conditions which insure that no shock will ever evolve on the wavefront, is derived. The influence of the parameter of the non-idealness, upstream flow Mach number in the presence of thermal radiation on the behavior of the wavefront are examined.

Singh, L. P.; Husain, Akmal; Singh, M.

2011-02-01

77

Thermodynamic instability and first-order phase transition in an ideal Bose gas  

SciTech Connect

We conduct a rigorous investigation into the thermodynamic instability of an ideal Bose gas confined in a cubic box, without assuming a thermodynamic limit or a continuous approximation. Based on the exact expression of the canonical partition function, we perform numerical computations up to 10{sup 6} particles. We report that if the number of particles is equal to or greater than a certain critical value, which turns out to be 7616, the ideal Bose gas subject to the Dirichlet boundary condition reveals a thermodynamic instability. Accordingly, we demonstrate that a system consisting of a finite number of particles can exhibit a discontinuous phase transition that features a genuine mathematical singularity, provided we keep not volume but pressure constant. The specific number, 7616, can be regarded as a characteristic number of a ''cube,'' which is the geometric shape of the box.

Park, Jeong-Hyuck [Department of Physics and Center for Quantum Spacetime Sogang University, Mapo-gu, Seoul 121-742 (Korea, Republic of); Kim, Sang-Woo [High Energy Accelerator Research Organization (KEK) Tsukuba, Ibaraki 305-0801 (Japan)

2010-06-15

78

Characteristic decomposition of compressible Euler equations for a non-ideal gas in two-dimensions  

NASA Astrophysics Data System (ADS)

We consider a two-dimensional compressible Euler system for a non-ideal gas, and use the characteristic decomposition to establish that any pseudo-steady isentropic irrotational flow, adjacent to a constant state, must be a simple wave. Further, the constancy of the entropy and vorticity along the pseudo-flow characteristics extends the foregoing conclusion to full Euler system. An attention is drawn to the fact that the result is also applicable to the shallow water system as it bears a close structural resemblance with the system under study. These results are generalization of the well-known theorem on reducible equations by Courant and Friedrichs [Supersonic Flow and Shock Waves (Springer-Verlag, New York, 1999)] and a recent result on compressible Euler system for an ideal gas by Li et al. ["Simple waves and a characteristic decomposition of the two-dimensional compressible Euler equations," Commun. Math. Phys. 267, 1-12 (2006)

Zafar, M.; Sharma, V. D.

2014-09-01

79

Modeling shock waves in an ideal gas: Combining the Burnett approximation and Holian's conjecture  

NASA Astrophysics Data System (ADS)

We model a shock wave in an ideal gas by combining the Burnett approximation and Holian’s conjecture. We use the temperature in the direction of shock propagation rather than the average temperature in the Burnett transport coefficients. The shock wave profiles and shock thickness are compared with other theories. The results are found to agree better with the nonequilibrium molecular dynamics (NEMD) and direct simulation Monte Carlo (DSMC) data than the Burnett equations and the modified Navier-Stokes theory.

He, Yi-Guang; Tang, Xiu-Zhang; Pu, Yi-Kang

2008-07-01

80

Cooking Under Pressure Applying the Ideal Gas Law in the Kitchen  

NSDL National Science Digital Library

The Clarksons are making dinner for friends and decide to try out their new pressure cooker. As students read the dialogue that ensues, they learn about how the boiling point of water is directly related to external pressure, apply the ideal gas law, and relate chemical reaction rates with temperatures in addition to learning about the conservation of energy. Designed for a non-majors’ general chemistry course, the case could be extended to other disciplines, including physics, nutrition, and microbiology.

Ling Chen

2009-01-01

81

M. Bahrami ENSC 461 (S 11) Tutorial 1 1 ENSC 461 Tutorial, Week#2 Ideal Gas  

E-print Network

M. Bahrami ENSC 461 (S 11) Tutorial 1 1 ENSC 461 Tutorial, Week#2 ­ Ideal Gas Consider a rigid 343 50 5 A2 T2 P2 25 B2 T2 P2 5 #12;M. Bahrami ENSC 461 (S 11) Tutorial 1 2 Step 4: State your specific internal energies (Recall U = mu), Eq6 is obtained. #12;M. Bahrami ENSC 461 (S 11) Tutorial 1 3

Bahrami, Majid

82

Charged two-dimensional quantum gas in a uniform magnetic field at finite temperature  

Microsoft Academic Search

We present closed-form, analytical expressions for the thermodynamic properties of an ideal, two-dimensional (2D) charged Fermi or Bose gas in the presence of a uniform magnetic field of arbitrary strength. We consider both the homogeneous quantum gas (in which case our expressions are exact) and the inhomogeneous gas within the local-density approximation. Our results for the Fermi gas are relevant

Brandon P. van Zyl; David A. Hutchinson

2004-01-01

83

Ideal Negative Measurements in Quantum Walks Disprove Theories Based on Classical Trajectories  

NASA Astrophysics Data System (ADS)

We report on a stringent test of the nonclassicality of the motion of a massive quantum particle, which propagates on a discrete lattice. Measuring temporal correlations of the position of single atoms performing a quantum walk, we observe a 6 ? violation of the Leggett-Garg inequality. Our results rigorously excludes (i.e., falsifies) any explanation of quantum transport based on classical, well-defined trajectories. We use so-called ideal negative measurements—an essential requisite for any genuine Leggett-Garg test—to acquire information about the atom's position, yet avoiding any direct interaction with it. The interaction-free measurement is based on a novel atom transport system, which allows us to directly probe the absence rather than the presence of atoms at a chosen lattice site. Beyond the fundamental aspect of this test, we demonstrate the application of the Leggett-Garg correlation function as a witness of quantum superposition. Here, we employ the witness to discriminate different types of walks spanning from merely classical to wholly quantum dynamics.

Robens, Carsten; Alt, Wolfgang; Meschede, Dieter; Emary, Clive; Alberti, Andrea

2015-01-01

84

A complete theory for the magnetism of an ideal gas of electrons  

SciTech Connect

We have explored Pauli paramagnetism, Landau diamagnetism, and de Haas-van Alphen effect in a single framework, and unified these three effects for all temperatures as well as for all strengths of magnetic field. Our result goes beyond Pauli-Landau result on the magnetism of the 3-D ideal gas of electrons, and is able to describe crossover of the de Haas-van Alphen oscillation to the saturation of magnetization. We also have obtained a novel asymptotic series expansion for the low temperature properties of the system.

Biswas, Shyamal; Jana, Debnarayan [Department of Physics, University of Calcutta, 92 APC Road, Kolkata 700009 (India)] [Department of Physics, University of Calcutta, 92 APC Road, Kolkata 700009 (India); Sen, Swati [Department of Physical Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur 741252 (India)] [Department of Physical Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur 741252 (India)

2013-05-15

85

Gas-Kinetic Theory Based Flux Splitting Method for Ideal Magnetohydrodynamics  

NASA Technical Reports Server (NTRS)

A gas-kinetic solver is developed for the ideal magnetohydrodynamics (MHD) equations. The new scheme is based on the direct splitting of the flux function of the MHD equations with the inclusion of "particle" collisions in the transport process. Consequently, the artificial dissipation in the new scheme is much reduced in comparison with the MHD Flux Vector Splitting Scheme. At the same time, the new scheme is compared with the well-developed Roe-type MHD solver. It is concluded that the kinetic MHD scheme is more robust and efficient than the Roe- type method, and the accuracy is competitive. In this paper the general principle of splitting the macroscopic flux function based on the gas-kinetic theory is presented. The flux construction strategy may shed some light on the possible modification of AUSM- and CUSP-type schemes for the compressible Euler equations, as well as to the development of new schemes for a non-strictly hyperbolic system.

Xu, Kun

1998-01-01

86

Time-Dependent Compression of Cylindrical or Spherical Ideal Gas Volumes  

NASA Astrophysics Data System (ADS)

Two problems of time-dependent compression of ideal (inviscid and not heat-conducting) gas, related with the idea of controlled inertial thermonuclear fusion (CITF) are considered. In first of them for time, close to time of an acoustic wave run by an initial cylindrical or spherical volume, the gas is isentropically compressed from rest to rest. Such energy optimal compressing does not ensure, however, the required level of temperature. In opposite to it when faster compressing with "a head shock" (HS) the necessary density is not reached. In the second problem the centered compressing wave of characteristics coming to an axis or to center of symmetry (further — CS) simultaneously with HS is introduced. As a result it is possible to create the conditions required for CITF.

Kraiko, A. N.

2006-08-01

87

Supersonic beams at high particle densities: model description beyond the ideal gas approximation.  

PubMed

Supersonic molecular beams constitute a very powerful technique in modern chemical physics. They offer several unique features such as a directed, collision-free flow of particles, very high luminosity, and an unsurpassed strong adiabatic cooling during the jet expansion. While it is generally recognized that their maximum flow velocity depends on the molecular weight and the temperature of the working fluid in the stagnation reservoir, not a lot is known on the effects of elevated particle densities. Frequently, the characteristics of supersonic beams are treated in diverse approximations of an ideal gas expansion. In these simplified model descriptions, the real gas character of fluid systems is ignored, although particle associations are responsible for fundamental processes such as the formation of clusters, both in the reservoir at increased densities and during the jet expansion. In this contribution, the various assumptions of ideal gas treatments of supersonic beams and their shortcomings are reviewed. It is shown in detail that a straightforward thermodynamic approach considering the initial and final enthalpy is capable of characterizing the terminal mean beam velocity, even at the liquid-vapor phase boundary and the critical point. Fluid properties are obtained using the most accurate equations of state available at present. This procedure provides the opportunity to naturally include the dramatic effects of nonideal gas behavior for a large variety of fluid systems. Besides the prediction of the terminal flow velocity, thermodynamic models of isentropic jet expansions permit an estimate of the upper limit of the beam temperature and the amount of condensation in the beam. These descriptions can even be extended to include spinodal decomposition processes, thus providing a generally applicable tool for investigating the two-phase region of high supersaturations not easily accessible otherwise. PMID:20961156

Christen, Wolfgang; Rademann, Klaus; Even, Uzi

2010-10-28

88

Vibrational spectra of indene. Part 4. Calibration, assignment, and ideal-gas thermodynamics  

NASA Astrophysics Data System (ADS)

The vibrational spectra of indene have been examined in the vapor and the liquid state using infrared and Raman spectroscopy. Wavenumbers of the liquid spectra are measured to 0.1 cm -1 to re-examine the potential of indene as a calibration molecule. An assignment for its normal modes of vibration is made considering vapor band shapes, polarization ratios and calculated frequencies from a scaling procedure of the indene AM1 force field. An AM1 analysis of the cyclopentadiene vibrations is performed to obtain the scale factors for the constituent five-membered ring. The root-mean standard deviation of the calculated relative to the observed frequencies is 11 cm -1 for the planar modes and 16 cm -1 for the nonplanar modes. The potential energy distribution for the nonplanar modes from a refinement calculation is discussed. Ideal-gas thermodynamic functions are evaluated using the vapor phase vibrational wavenumbers and the previously reported moments-of-inertia. The spectroscopic ideal-gas entropy exceeds that determined from calorimetry by ? 0.95 R (R = 8.31451 J K -1 mol -1) from 300 to 500 K, indicating that the crystal most probably contains some residual disorder at 0 K.

Klots, T. D.

1995-11-01

89

Generic features of the wealth distribution in ideal-gas-like markets  

E-print Network

We provide an exact solution to the ideal-gas-like models studied in econophysics to understand the microscopic origin of Pareto-law. In these class of models the key ingredient necessary for having a self-organized scale-free steady-state distribution is the trading or collision rule where agents or particles save a definite fraction of their wealth or energy and invests the rest for trading. Using a Gibbs ensemble approach we could obtain the exact distribution of wealth in this model. Moreover we show that in this model (a) good savers are always rich and (b) every agent poor or rich invests the same amount for trading. Nonlinear trading rules could alter the generic scenario observed here.

P. K. Mohanty

2006-07-10

90

Slippage and Boundary Layer Probed in an Almost Ideal Gas by a Nanomechanical Oscillator  

NASA Astrophysics Data System (ADS)

We measure the interaction between He4 gas at 4.2 K and a high-quality nanoelectromechanical string device for its first three symmetric modes (resonating at 2.2, 6.7, and 11 MHz with quality factor Q >0.1×106) over almost 6 orders of magnitude in pressure. This fluid can be viewed as the best experimental implementation of an almost ideal monoatomic and inert gas of which properties are tabulated. The experiment ranges from high pressure where the flow is of laminar Stokes-type presenting slippage down to very low pressures where the flow is molecular. In the molecular regime, when the mean-free path is of the order of the distance between the suspended nanomechanical probe and the bottom of the trench, we resolve for the first time the signature of the boundary (Knudsen) layer onto the measured dissipation. Our results are discussed in the framework of the most recent theories investigating boundary effects in fluids (both analytic approaches and direct simulation Monte Carlo methods).

Defoort, M.; Lulla, K. J.; Crozes, T.; Maillet, O.; Bourgeois, O.; Collin, E.

2014-09-01

91

Quantum noise properties of non-ideal optical amplifiers and attenuators This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Quantum noise properties of non-ideal optical amplifiers and attenuators This article has been properties of non-ideal optical amplifiers and attenuators Zhimin Shi1 , Ksenia Dolgaleva1,2 and Robert W 26 1817) of the noise properties of ideal linear amplifiers to include the possibility of non

Boyd, Robert W.

92

University Students Explaining Adiabatic Compression of an Ideal Gas--A New Phenomenon in Introductory Thermal Physics  

ERIC Educational Resources Information Center

This study focuses on second-year university students' explanations and reasoning related to adiabatic compression of an ideal gas. The phenomenon was new to the students, but it was one which they should have been capable of explaining using their previous upper secondary school knowledge. The students' explanations and reasoning were…

Leinonen, Risto; Asikainen, Mervi A.; Hirvonen, Pekka E.

2012-01-01

93

Wigner distribution function for a harmonically trapped gas of ideal fermions and bosons at arbitrary temperature and dimensionality  

Microsoft Academic Search

We present a new, simple closed form expression for the exact Wigner function of an ideal gas of harmonically trapped fermions or bosons at arbitrary temperature and dimensionality. One of the primary advantages of our expression is that it provides a clean separation of the spatial and momentum variables, which can significantly simplify analytical calculations involving the Wigner function. Our

Brandon P van Zyl

2012-01-01

94

Quantum Information from Graviton-Matter Gas  

E-print Network

We present basics of conceptually new-type way for explaining of the origin, evolution and current physical properties of our Universe from the graviton-matter gas viewpoint. Quantization method for the Friedmann-Lemaitre Universe based on the canonical Hamilton equations of motion is proposed and quantum information theory way to physics of the Universe is showed. The current contribution from the graviton-matter gas temperature in quintessence approximation is discussed.

Lukasz-Andrzej Glinka

2007-09-04

95

Determination of ideal-gas enthalpies of formation for key compounds:  

SciTech Connect

The results of a study aimed at improvement of group-contribution methodology for estimation of thermodynamic properties of organic and organosilicon substances are reported. Specific weaknesses where particular group-contribution terms were unknown, or estimated because of lack of experimental data, are addressed by experimental studies of enthalpies of combustion in the condensed phase, vapor-pressure measurements, and differential scanning calorimetric (d.s.c.) heat-capacity measurements. Ideal-gas enthalpies of formation of ({plus minus})-butan-2-ol, tetradecan-1-ol, hexan-1,6-diol, methacrylamide, benzoyl formic acid, naphthalene-2,6-dicarboxylic acid dimethyl ester, and tetraethylsilane are reported. A crystalline-phase enthalpy of formation at 298.15 K was determined for naphthalene-2,6-dicarboxylic acid, which decomposed at 695 K before melting. The combustion calorimetry of tetraethylsilane used the proven fluorine-additivity methodology. Critical temperature and critical density were determined for tetraethylsilane with differential scanning calorimeter and the critical pressure was derived. Group-additivity parameters useful in the application of group- contribution correlations are derived. 112 refs., 13 figs., 19 tabs.

Steele, W.V.; Chirico, R.D.; Nguyen, A.; Hossenlopp, I.A.; Smith, N.K.

1991-10-01

96

The ideal relativistic rotating gas as a perfect fluid with spin  

SciTech Connect

We show that the ideal relativistic spinning gas at complete thermodynamical equilibrium is a fluid with a non-vanishing spin density tensor {sigma}{sub {mu}{nu}}. After having obtained the expression of the local spin-dependent phase-space density f(x, p){sub {sigma}{tau}} in the Boltzmann approximation, we derive the spin density tensor and show that it is proportional to the acceleration tensor {Omega}{sub {mu}{nu}} constructed with the Frenet-Serret tetrad. We recover the proper generalization of the fundamental thermodynamical relation, involving an additional term -(1/2){Omega}{sub {mu}{nu}{sigma}}{sup {mu}{nu}}. We also show that the spin density tensor has a non-vanishing projection onto the four-velocity field, i.e. t{sup {mu}} = {sigma}{sub {mu}}{nu}u{sup {nu}} {ne} 0, in contrast to the common assumption t{sup {mu}} = 0, known as Frenkel condition, in the thus-far proposed theories of relativistic fluids with spin. We briefly address the viewpoint of the accelerated observer and inertial spin effects.

Becattini, F., E-mail: becattini@fi.infn.i [Universita di Firenze, Florence (Italy); INFN Sezione di Firenze, Florence (Italy); Tinti, L. [Universita di Firenze, Florence (Italy)

2010-08-15

97

Quantum Algorithms for many-to-one Functions to Solve the Regulator and the Principal Ideal Problem  

E-print Network

We propose new quantum algorithms to solve the regulator and the principal ideal problem in a real-quadratic number field. We improve the algorithms proposed by Hallgren by using two different techniques. The first improvement is the usage of a period function which is not one-to-one on its period. We show that even in this case Shor's algorithm computes the period with constant probability. The second improvement is the usage of reduced forms (a, b, c) of discriminant D with a>0 instead of reduced ideals of the same discriminant. These improvements reduce the number of required qubits by at least 2 log D.

Arthur Schmidt

2009-12-24

98

History dependent quantum random walks as quantum lattice gas automata  

NASA Astrophysics Data System (ADS)

Quantum Random Walks (QRW) were first defined as one-particle sectors of Quantum Lattice Gas Automata (QLGA). Recently, they have been generalized to include history dependence, either on previous coin (internal, i.e., spin or velocity) states or on previous position states. These models have the goal of studying the transition to classicality, or more generally, changes in the performance of quantum walks in algorithmic applications. We show that several history dependent QRW can be identified as one-particle sectors of QLGA. This provides a unifying conceptual framework for these models in which the extra degrees of freedom required to store the history information arise naturally as geometrical degrees of freedom on the lattice.

Shakeel, Asif; Meyer, David A.; Love, Peter J.

2014-12-01

99

History Dependent Quantum Random Walks as Quantum Lattice Gas Automata  

E-print Network

Quantum Random Walks (QRW) were first defined as one-particle sectors of Quantum Lattice Gas Automata (QLGA). Recently, they have been generalized to include history dependence, either on previous coin (internal, i.e., spin or velocity) states or on previous position states. These models have the goal of studying the transition to classicality, or more generally, changes in the performance of quantum walks in algorithmic applications. We show that several history dependent QRW can be identified as one-particle sectors of QLGA. This provides a unifying conceptual framework for these models in which the extra degrees of freedom required to store the history information arise naturally as geometrical degrees of freedom on the lattice.

Asif Shakeel; David A. Meyer; Peter J. Love

2014-05-05

100

Validation of the Jarzynski relation for a system with strong thermal coupling: an isothermal ideal gas model.  

PubMed

We revisit the paradigm of an ideal gas under isothermal conditions. A moving piston performs work on an ideal gas in a container that is strongly coupled to a heat reservoir. The thermal coupling is modeled by stochastic scattering at the boundaries. In contrast to recent studies of an adiabatic ideal gas with a piston [R.C. Lua and A.Y. Grosberg, J. Phys. Chem. B 109, 6805 (2005); I. Bena, Europhys. Lett. 71, 879 (2005)], the container and piston stay in contact with the heat bath during the work process. Under this condition the heat reservoir as well as the system depend on the work parameter lambda and microscopic reversibility is broken for a moving piston. Our model is thus not included in the class of systems for which the nonequilibrium work theorem has been derived rigorously either by Hamiltonian [C. Jarzynski, J. Stat. Mech. (2004) P09005] or stochastic methods [G.E. Crooks, J. Stat. Phys. 90, 1481 (1998)]. Nevertheless the validity of the nonequilibrium work theorem is confirmed both numerically for a wide range of parameter values and analytically in the limit of a very fast moving piston, i.e., in the far nonequilibrium regime. PMID:17280048

Baule, A; Evans, R M L; Olmsted, P D

2006-12-01

101

A new method for the measurement of meteorite bulk volume via ideal gas pycnometry  

NASA Astrophysics Data System (ADS)

To date, of the many techniques used to measure the bulk volume of meteorites, only three methods (Archimedean bead method, 3-D laser imaging and X-ray microtomography) can be considered as nondestructive or noncontaminating. The bead method can show large, random errors for sample sizes of smaller than 5 cm3. In contrast, 3-D laser imaging is a high-accuracy method even when measuring the bulk volumes of small meteorites. This method is both costly and time consuming, however, and meteorites of a certain shape may lead to some uncertainties in the analysis. The method of X-ray microtomography suffers from the same problems as 3-D laser imaging. This study outlines a new method of high-accuracy, nondestructive and noncontaminating measurement of the bulk volume of meteorite samples. In order to measure the bulk volume of a meteorite, one must measure the total volume of the balloon vacuum packaged meteorite and the volume of balloon that had been used to enclose the meteorite using ideal gas pycnometry. The difference between the two determined volumes is the bulk volume of the meteorite. Through the measurement of zero porosity metal spheres and tempered glass fragments, our results indicate that for a sample which has a volume of between 0.5 and 2 cm3, the relative error of the measurement is less than ±0.6%. Furthermore, this error will be even smaller (less than ±0.1%) if the determined sample size is larger than 2 cm3. The precision of this method shows some volume dependence. For samples smaller than 1 cm3, the standard deviations are less than ±0.328%, and these values will fall to less than ±0.052% for samples larger than 2 cm3. The porosities of nine fragments of Jilin, GaoGuenie, Zaoyang and Zhaodong meteorites have been measured using our vacuum packaging-pycnometry method, with determined average porosities of Jilin, GaoGuenie, Zaoyang and Zhaodong of 9.0307%, 2.9277%, 17.5437% and 5.9748%, respectively. These values agree well with the porosities of fragments of which have been measured using the Archimedean bead method and 3-D laser imaging. This method also may be applied to the study of rare samples in other fields (e.g., archeology and geology).

Li, Shijie; Wang, Shijie; Li, Xiongyao; Li, Yang; Liu, Shen; Coulson, Ian M.

2012-10-01

102

Dynamics of the electric current in an ideal electron gas: a sound mode inside the quasi-particles  

E-print Network

We study the equation of motion for the Noether current in an electron gas within the framework of the Schwinger-Keldysh Closed-Time-Path formalism. The equation is shown to be highly non-linear and irreversible even for a non-interacting, ideal gas of electrons at non-zero density. We truncate the linearised equation of motion, written as the Laurent series in Fourier space, so that the resulting expressions are local in time, both at zero and at small finite temperatures. Furthermore, we show that the one-loop Coulomb interactions only alter the physical picture quantitatively, while preserving the characteristics of the dynamics that the electric current exhibits in the absence of interactions. As a result of the composite nature of the Noether current, composite sound waves are found to be the dominant IR collective excitations at length scales between the inverse Fermi momentum and the mean free path that would exist in an interacting electron gas. We also discuss the difference and the transition between the hydrodynamical regime of an ideal gas, defined in this work, and the hydrodynamical regime in phenomenological hydrodynamics, which is normally used for the description of interacting gases.

Sašo Grozdanov; Janos Polonyi

2015-01-26

103

The Role of Multiple Representations in the Understanding of Ideal Gas Problems  

ERIC Educational Resources Information Center

This study examined the representational competence of students as they solved problems dealing with the temperature-pressure relationship for ideal gases. Seven students enrolled in a first-semester general chemistry course and two advanced undergraduate science majors participated in the study. The written work and transcripts from videotaped…

Madden, Sean P.; Jones, Loretta L.; Rahm, Jrene

2011-01-01

104

The Heat Capacity of Ideal Gases  

ERIC Educational Resources Information Center

The heat capacity of an ideal gas has been shown to be calculable directly by statistical mechanics if the energies of the quantum states are known. However, unless one makes careful calculations, it is not easy for a student to understand the qualitative results. Why there are maxima (and occasionally minima) in heat capacity-temperature curves…

Scott, Robert L.

2006-01-01

105

Ideal-gas specific heat and second virial coefficient of HFC-125 based on sound-velocity measurements  

NASA Astrophysics Data System (ADS)

The sound velocity in gaseous pentafluoroethane (HFC-125, CF3CHF2) has been measured by means of a spherical acoustic resonator, Seventy-two sound-velocity values were measured with an uncertainty of ±0.01% at temperatures from 273 to 343 K and pressures from 101 to 250 kPa. The ideal-gas specific heats and the second acoustic-virial coefficients have been determined on the basis of the Sound-velocity measurements. The second virial coefficients calculated from the present sound-velocity measurements agree with literature values which were determined from PVT measurements by means of a Burnett method.

Hozumi, T.; Sato, H.; Watanabe, K.

1996-05-01

106

Interferograms, Schlieren, and Shadowgraphs Constructed from Real- and Ideal-Gas, Two- and Three-Dimensional Computed Flowfields  

NASA Technical Reports Server (NTRS)

The construction of interferograms, schlieren, and shadowgraphs from computed flowfield solutions permits one-to-one comparisons of computed and experimental results. A method for constructing these images from both ideal- and real-gas, two- and three-dimensional computed flowfields is described. The computational grids can be structured or unstructured, and multiple grids are an option. Constructed images are shown for several types of computed flows including nozzle, wake, and reacting flows; comparisons to experimental images are also shown. In addition, the sensitivity of these images to errors in the flowfield solution is demonstrated, and the constructed images can be used to identify problem areas in the computations.

Yates, Leslie A.

1992-01-01

107

Interferograms, schlieren, and shadowgraphs constructed from real- and ideal-gas, two- and three-dimensional computed flowfields  

NASA Technical Reports Server (NTRS)

The construction of interferograms, schlieren, and shadowgraphs from computed flowfield solutions permits one-to-one comparisons of computed and experimental results. A method of constructing these images from both ideal- and real-gas, two and three-dimensional computed flowfields is described. The computational grids can be structured or unstructured, and multiple grids are an option. Constructed images are shown for several types of computed flows including nozzle, wake, and reacting flows; comparisons to experimental images are also shown. In addition, th sensitivity of these images to errors in the flowfield solution is demonstrated, and the constructed images can be used to identify problem areas in the computations.

Yates, Leslie A.

1993-01-01

108

CHAPTER 5 -SYSTEMS UNDER PRESSURE 5.1 Ideal gas law  

E-print Network

is a moveable piston: Low pressure High pressure Fig. 5.1. Sample of gas in a sealed cylinder with a moveable piston. Chapter 5 - Systems under pressure 62 ©1997 by David Boal, Simon Fraser University. All rights. 5.2. Sample of gas under constant pressure expands when heated. More than a century later

Boal, David

109

Idealized gas turbine combustor for performance research and validation of large eddy simulations  

Microsoft Academic Search

This paper details the design of a premixed, swirl-stabilized combustor that was designed and built for the express purpose of obtaining validation-quality data for the development of large eddy simulations (LES) of gas turbine combustors. The combustor features nonambiguous boundary conditions, a geometrically simple design that retains the essential fluid dynamics and thermochemical processes that occur in actual gas turbine

Timothy C. Williams; Robert W. Schefer; Joseph C. Oefelein; Christopher R. Shaddix

2007-01-01

110

Heterostructure quantum wires as an ideal source of entangled photon pairs  

Microsoft Academic Search

We show [1] that based on symmetry arguments, idealised quantum nanostructures grown along the [111] direction, such as self-assembled quantum dots or heterostructure wires must have a vanishing FSS. We confirm this prediction by million-atom empirical pseudopotential many-body calculations of realistic structures. We use experimentally realised shapes, compositions and sizes and find that the vanishing FSS must be present in

Ranber Singh; Gabriel Bester

2010-01-01

111

Distribution functions for a two-dimensional non-interacting quantum electron gas in an external magnetic field  

NASA Astrophysics Data System (ADS)

The exact n-body distribution functions are calculated for a two-dimensional, non-interacting quantum electron gas in an external magnetic field for any temperature and density. At low tempertures and filled lowest Landau level (LLL), these functions are identical to the exact distribution functions obtained by Jancovici [1981, Phys. Rev. Lett., 46, 386] for the classical two-dimensional one-component plasma (2DOCP) at the special plasma parameter ? = 2, thus establishing that the 2DOCP provides an exact classical Boltzmann factor which describes the ideal LLL quantum state associated with the integral quantum Hall effect.

Lado, F.

2003-01-01

112

First Law of Thermodynamics Two closed thermodynamic cycles for an ideal gas  

E-print Network

positive because W is negative and U = W + Q = 0 Demo:steam engine #12;2 A cylinder with initial volume V convertible has an eight-cylinder engine. At the beginning of its compression stroke, one of the cylinders.72 x 106 Pa. What is the final temperature of the gas in an engine cylinder after the compression

Winokur, Michael

113

Minimax estimation of the Wigner function in quantum homodyne tomography with ideal detectors  

E-print Network

of quantum homodyne measurements per- formed on identically prepared pulses. The state is represented through between the microscopic and the macroscopic worlds have an intrinsic probabilistic nature. When measuring an atom or a laser pulse we obtain a random result whose probability distribution is determined

Guta, Madalin

114

Condensation of ideal Bose gas confined in a box within a canonical ensemble  

SciTech Connect

We set up recursion relations for the partition function and the ground-state occupancy for a fixed number of noninteracting bosons confined in a square box potential and determine the temperature dependence of the specific heat and the particle number in the ground state. A proper semiclassical treatment is set up which yields the correct small-T behavior in contrast to an earlier theory in Feynman's textbook on statistical mechanics, in which the special role of the ground state was ignored. The results are compared with an exact quantum-mechanical treatment. Furthermore, we derive the finite-size effect of the system.

Glaum, Konstantin; Kleinert, Hagen; Pelster, Axel [Institut fuer Theoretische Physik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Fachbereich Physik, Universitaet Duisburg-Essen, Campus Duisburg, Lotharstrasse 1, 47048 Duisburg (Germany)

2007-12-15

115

Idealized gas turbine combustor for performance research and validation of large eddy simulations.  

PubMed

This paper details the design of a premixed, swirl-stabilized combustor that was designed and built for the express purpose of obtaining validation-quality data for the development of large eddy simulations (LES) of gas turbine combustors. The combustor features nonambiguous boundary conditions, a geometrically simple design that retains the essential fluid dynamics and thermochemical processes that occur in actual gas turbine combustors, and unrestrictive access for laser and optical diagnostic measurements. After discussing the design detail, a preliminary investigation of the performance and operating envelope of the combustor is presented. With the combustor operating on premixed methane/air, both the equivalence ratio and the inlet velocity were systematically varied and the flame structure was recorded via digital photography. Interesting lean flame blowout and resonance characteristics were observed. In addition, the combustor exhibited a large region of stable, acoustically clean combustion that is suitable for preliminary validation of LES models. PMID:17411224

Williams, Timothy C; Schefer, Robert W; Oefelein, Joseph C; Shaddix, Christopher R

2007-03-01

116

Ideal gas in a strong gravitational field: Area dependence of entropy  

SciTech Connect

We study the thermodynamic parameters like entropy, energy etc. of a box of gas made up of indistinguishable particles when the box is kept in various static background spacetimes having a horizon. We compute the thermodynamic variables using both statistical mechanics as well as by solving the hydrodynamical equations for the system. When the box is far away from the horizon, the entropy of the gas depends on the volume of the box except for small corrections due to background geometry. As the box is moved closer to the horizon with one (leading) edge of the box at about Planck length (L{sub p}) away from the horizon, the entropy shows an area dependence rather than a volume dependence. More precisely, it depends on a small volume A{sub perpendicular}L{sub p}/2 of the box, up to an order O(L{sub p}/K){sup 2} where A{sub perpendicular} is the transverse area of the box and K is the (proper) longitudinal size of the box related to the distance between leading and trailing edge in the vertical direction (i.e. in the direction of the gravitational field). Thus the contribution to the entropy comes from only a fraction O(L{sub p}/K) of the matter degrees of freedom and the rest are suppressed when the box approaches the horizon. Near the horizon all the thermodynamical quantities behave as though the box of gas has a volume A{sub perpendicular}L{sub p}/2 and is kept in a Minkowski spacetime. These effects are: (i) purely kinematic in their origin and are independent of the spacetime curvature (in the sense that the Rindler approximation of the metric near the horizon can reproduce the results) and (ii) observer dependent. When the equilibrium temperature of the gas is taken to be equal to the horizon temperature, we get the familiar A{sub perpendicular}/L{sub p}{sup 2} dependence in the expression for entropy. All these results hold in a D+1 dimensional spherically symmetric spacetime. The analysis based on methods of statistical mechanics and the one based on thermodynamics applied to the gas treated as a fluid in static geometry, lead to the same results showing the consistency. The implications are discussed.

Kolekar, Sanved; Padmanabhan, T. [IUCAA, Pune University Campus, Ganeshkhind, Pune 411007 (India)

2011-03-15

117

Jack Polynomials as Fractional Quantum Hall States and the Betti Numbers of the ( k + 1)-Equals Ideal  

NASA Astrophysics Data System (ADS)

We show that for Jack parameter ? = -( k + 1)/( r - 1), certain Jack polynomials studied by Feigin-Jimbo-Miwa-Mukhin vanish to order r when k + 1 of the coordinates coincide. This result was conjectured by Bernevig and Haldane, who proposed that these Jack polynomials are model wavefunctions for fractional quantum Hall states. Special cases of these Jack polynomials include the wavefunctions of Laughlin and Read-Rezayi. In fact, along these lines we prove several vanishing theorems known as clustering properties for Jack polynomials in the mathematical physics literature, special cases of which had previously been conjectured by Bernevig and Haldane. Motivated by the method of proof, which in the case r = 2 identifies the span of the relevant Jack polynomials with the S n -invariant part of a unitary representation of the rational Cherednik algebra, we conjecture that unitary representations of the type A Cherednik algebra have graded minimal free resolutions of Bernstein-Gelfand-Gelfand type; we prove this for the ideal of the ( k + 1)-equals arrangement in the case when the number of coordinates n is at most 2 k + 1. In general, our conjecture predicts the graded S n -equivariant Betti numbers of the ideal of the ( k + 1)-equals arrangement with no restriction on the number of ambient dimensions.

Zamaere, Christine Berkesch; Griffeth, Stephen; Sam, Steven V.

2014-08-01

118

Dynamics of the electric current in an ideal electron gas: a sound mode inside the quasi-particles  

E-print Network

We study the equation of motion for the Noether current in an electron gas within the framework of the Schwinger-Keldysh Closed-Time-Path formalism. The equation is shown to be highly non-linear and irreversible even for a non-interacting, ideal gas of electrons at non-zero density. We truncate the linearised equation of motion, written as the Laurent series in Fourier space, so that the resulting expressions are local in time, both at zero and at small finite temperatures. Furthermore, we show that the one-loop Coulomb interactions only alter the physical picture quantitatively, while preserving the characteristics of the dynamics that the electric current exhibits in the absence of interactions. As a result of the composite nature of the Noether current, composite sound waves are found to be the dominant IR collective excitations at length scales between the inverse Fermi momentum and the mean free path that would exist in an interacting electron gas. We also discuss the difference and the transition betwee...

Grozdanov, Sašo

2015-01-01

119

Steady Secondary Flows Generated by Periodic Compression and Expansion of an Ideal Gas in a Pulse Tube  

NASA Technical Reports Server (NTRS)

This study establishes a consistent set of differential equations for use in describing the steady secondary flows generated by periodic compression and expansion of an ideal gas in pulse tubes. Also considered is heat transfer between the gas and the tube wall of finite thickness. A small-amplitude series expansion solution in the inverse Strouhal number is proposed for the two-dimensional axisymmetric mass, momentum and energy equations. The anelastic approach applies when shock and acoustic energies are small compared with the energy needed to compress and expand the gas. An analytic solution to the ordered series is obtained in the strong temperature limit where the zeroth-order temperature is constant. The solution shows steady velocities increase linearly for small Valensi number and can be of order I for large Valensi number. A conversion of steady work flow to heat flow occurs whenever temperature, velocity or phase angle gradients are present. Steady enthalpy flow is reduced by heat transfer and is scaled by the Prandtl times Valensi numbers. Particle velocities from a smoke-wire experiment were compared with predictions for the basic and orifice pulse tube configurations. The theory accurately predicted the observed steady streaming.

Lee, Jeffrey M.

1999-01-01

120

Development Of Excel Add-in Modules For Use In Thermodynamics Curriculum: Steam And Ideal Gas Properties  

NSDL National Science Digital Library

For engineering graduates entering the job market, experience with appropriate computational tools and techniques is increasingly necessary. Therefore, the University of Alabama's Mechanical Engineering Department is introducing students to computational problem solving earlier in their college careers by developing Microsoft Excel-based modules to be used as teaching tools in the sophomore and junior-level thermodynamics and heat transfer courses. The MS Excel package was chosen as a software platform for this purpose because of its ubiquitous nature and its ability to utilize Visual Basic for Applications (VBA) macros in a spreadsheet format. In the sophomore-level thermodynamics course, much of the class material focuses on the properties of steam and ideal gases. Therefore, a suite of Microsoft Excel functions to compute steam and ideal gas properties and assist in analyzing properties of states and processes has been developed. A number of Excel packages that pertained to the computation of steam properties were already available in the public domain. In a companion paper1, these packages were compared and Magnus Holmgrens Xsteam functions were chosen as a starting point for the current project.

Huguet, Jesse

121

An Approximate Analytical Solution of Imploding Strong Shocks in a Non-Ideal Gas through Lie Group Analysis  

NASA Astrophysics Data System (ADS)

The method of Lie group transformation is used to obtain an approximate analytical solution to the system of first-order quasilinear partial differential equations that govern a one-dimensional unsteady planer, cylindrically symmetric and spherically symmetric motion in a non-ideal gas, involving strong shock waves. Invariance groups admitted by the governing system of partial differential equations, which are indeed continuous group of transformations under which the system of partial differential equations remains invariant, are determined, and the complete Lie algebra of infinitesimal symmetries is established. The infinitesimal generators are used to construct the similarity variables. These similarity variables are used to reduce the governing system of partial differential equations into a system of ordinary differential equations.

Singh P., L.; Akmal, Husain; Singh, M.

2010-01-01

122

Unified first principles description from warm dense matter to ideal ionized gas plasma: electron-ion collisions induced friction.  

PubMed

Electron-ion interactions are central to numerous phenomena in the warm dense matter (WDM) regime and at higher temperature. The electron-ion collisions induced friction at high temperature is introduced in the procedure of ab initio molecular dynamics using the Langevin equation based on density functional theory. In this framework, as a test for Fe and H up to 1000 eV, the equation of state and the transition of electronic structures of the materials with very wide density and temperature can be described, which covers a full range of WDM up to high energy density physics. A unified first principles description from condensed matter to ideal ionized gas plasma is constructed. PMID:20867307

Dai, Jiayu; Hou, Yong; Yuan, Jianmin

2010-06-18

123

Ideal-gas specific heat and second virial coefficient of HFC-125 based on sound-velocity measurements  

SciTech Connect

The sound velocity in gaseous pentafluoroethane (HFC-125, CF{sub 3}CHF{sub 2}) has been measured by means of a spherical acoustic resonator. Seventy-two sound-velocity values were measured with an uncertainty of {plus_minus}0.01% at temperatures form 273 to 343 K and pressures form 10 to 250 kPa. The ideal-gas specific heats and the second acoustic-virial coefficients have been determined on the basis of the sound-velocity measurements. The second virial coefficients calculated from the present sound-velocity measurements agree with literature values which were determined from PVT measurements by means of a Burnett method.

Hozumi, T.; Sato, H.; Watanabe, K. [Keio Univ., Yokohama (Japan)

1996-05-01

124

Charged two-dimensional quantum gas in a uniform magnetic field at finite temperature  

NASA Astrophysics Data System (ADS)

We present closed-form, analytical expressions for the thermodynamic properties of an ideal, two-dimensional (2D) charged Fermi or Bose gas in the presence of a uniform magnetic field of arbitrary strength. We consider both the homogeneous quantum gas (in which case our expressions are exact) and the inhomogeneous gas within the local-density approximation. Our results for the Fermi gas are relevant to the current-density-functional theory of low-dimensional electronic systems in magnetic fields. For a 2D charged Bose gas (CBG) in a homogeneous magnetic field, we show that the uniform system undergoes a sharp transition at a critical temperature T?c, below which there is a macroscopic occupation of the lowest Landau level. An examination of the one-body density matrix, however, reveals the absence of long-range order, thereby indicating that the transition cannot be interpreted to a Bose-Einstein condensate. Nevertheless, for Tideal CBG to exhibit a superconducting state, it may not be a necessary condition.

van Zyl, Brandon P.; Hutchinson, David A.

2004-01-01

125

Gas-particle partitioning of atmospheric aerosols: interplay of physical state, non-ideal mixing and morphology.  

PubMed

Atmospheric aerosols, comprising organic compounds and inorganic salts, play a key role in air quality and climate. Mounting evidence exists that these particles frequently exhibit phase separation into predominantly organic and aqueous electrolyte-rich phases. As well, the presence of amorphous semi-solid or glassy particle phases has been established. Using the canonical system of ammonium sulfate mixed with organics from the ozone oxidation of ?-pinene, we illustrate theoretically the interplay of physical state, non-ideality, and particle morphology affecting aerosol mass concentration and the characteristic timescale of gas-particle mass transfer. Phase separation can significantly affect overall particle mass and chemical composition. Semi-solid or glassy phases can kinetically inhibit the partitioning of semivolatile components and hygroscopic growth, in contrast to the traditional assumption that organic compounds exist in quasi-instantaneous gas-particle equilibrium. These effects have significant implications for the interpretation of laboratory data and the development of improved atmospheric air quality and climate models. PMID:23748935

Shiraiwa, Manabu; Zuend, Andreas; Bertram, Allan K; Seinfeld, John H

2013-07-21

126

Quantum Joule-Thomson Effect in a Saturated Homogeneous Bose Gas  

NASA Astrophysics Data System (ADS)

We study the thermodynamics of Bose-Einstein condensation in a weakly interacting quasihomogeneous atomic gas, prepared in an optical-box trap. We characterize the critical point for condensation and observe saturation of the thermal component in a partially condensed cloud, in agreement with Einstein's textbook picture of a purely statistical phase transition. Finally, we observe the quantum Joule-Thomson effect, namely isoenthalpic cooling of an (essentially) ideal gas. In our experiments this cooling occurs spontaneously, due to energy-independent collisions with the background gas in the vacuum chamber. We extract a Joule-Thomson coefficient ?JT>109 K /bar, about 10 orders of magnitude larger than observed in classical gases.

Schmidutz, Tobias F.; Gotlibovych, Igor; Gaunt, Alexander L.; Smith, Robert P.; Navon, Nir; Hadzibabic, Zoran

2014-01-01

127

Quantum Joule-Thomson effect in a saturated homogeneous Bose gas.  

PubMed

We study the thermodynamics of Bose-Einstein condensation in a weakly interacting quasihomogeneous atomic gas, prepared in an optical-box trap. We characterize the critical point for condensation and observe saturation of the thermal component in a partially condensed cloud, in agreement with Einstein's textbook picture of a purely statistical phase transition. Finally, we observe the quantum Joule-Thomson effect, namely isoenthalpic cooling of an (essentially) ideal gas. In our experiments this cooling occurs spontaneously, due to energy-independent collisions with the background gas in the vacuum chamber. We extract a Joule-Thomson coefficient ?JT>10(9)??K/bar, about 10 orders of magnitude larger than observed in classical gases. PMID:24580421

Schmidutz, Tobias F; Gotlibovych, Igor; Gaunt, Alexander L; Smith, Robert P; Navon, Nir; Hadzibabic, Zoran

2014-01-31

128

Rigorous investigation of the reduced density matrix for the ideal Bose gas in harmonic traps by a loop-gas-like approach  

SciTech Connect

In this paper, we rigorously investigate the reduced density matrix (RDM) associated to the ideal Bose gas in harmonic traps. We present a method based on a sum-decomposition of the RDM allowing to treat not only the isotropic trap, but also general anisotropic traps. When focusing on the isotropic trap, the method is analogous to the loop-gas approach developed by Mullin [“The loop-gas approach to Bose-Einstein condensation for trapped particles,” Am. J. Phys. 68(2), 120 (2000)]. Turning to the case of anisotropic traps, we examine the RDM for some anisotropic trap models corresponding to some quasi-1D and quasi-2D regimes. For such models, we bring out an additional contribution in the local density of particles which arises from the mesoscopic loops. The close connection with the occurrence of generalized-Bose-Einstein condensation is discussed. Our loop-gas-like approach provides relevant information which can help guide numerical investigations on highly anisotropic systems based on the Path Integral Monte Carlo method.

Beau, Mathieu, E-mail: mbeau@stp.dias.ie [Dublin Institute for Advanced Studies School of Theoretical Physics, 10 Burlington Road, Dublin 4 (Ireland)] [Dublin Institute for Advanced Studies School of Theoretical Physics, 10 Burlington Road, Dublin 4 (Ireland); Savoie, Baptiste, E-mail: baptiste.savoie@gmail.com [Department of Mathematical Sciences, University of Aarhus, Ny Munkegade, Building 1530, DK-8000 Aarhus C (Denmark)] [Department of Mathematical Sciences, University of Aarhus, Ny Munkegade, Building 1530, DK-8000 Aarhus C (Denmark)

2014-05-15

129

Exploring the Ideal Gas Law through a Quantitative Gasometric Analysis of Nitrogen Produced by the Reaction of Sodium Nitrite with Sulfamic Acid  

ERIC Educational Resources Information Center

The gasometric analysis of nitrogen produced in a reaction between sodium nitrite, NaNO[superscript 2], and sulfamic acid, H(NH[superscript 2])SO[superscript 3], provides an alternative to more common general chemistry experiments used to study the ideal gas law, such as the experiment in which magnesium is reacted with hydrochloric acid. This…

Yu, Anne

2010-01-01

130

Steady secondary flows generated by periodic compression and expansion of an ideal gas in a pulse tube  

NASA Astrophysics Data System (ADS)

This study establishes a consistent set of differential equations for use in describing the steady secondary flows generated by periodic compression and expansion of an ideal gas in pulse tubes. A small amplitude series expansion solution in the inverse Strouhal number at the anelastic limit is proposed for the two-dimensional axisymmetric mass, momentum and energy equations. The anelastic approach applies when shock and acoustic energies are small compared to the energy needed to compress and expand the gas, such as for pulse tubes. Seven independent dimensionless numbers are used to scale the system. The reciprocal Strouhal number and Valensi number are used to linearize the mass and momentum equations. The Fourier number is used to characterize heat transfer within the tube wall. The Mach number, the Prandtl number, the velocity amplitude and the velocity phase angle at the tube ends complete the dimensionless scales. The ordered equations show that the zeroth-, first- and second-order equations, are coupled through the zeroth- order temperature. An analytic solution is obtained in the strong temperature limit where the zeroth-order temperature is constant. The solution shows that periodic heat transfer between the gas and tube, characterized by the complex Nusselt number, is independent of axial velocity boundary conditions and Fourier number. Steady velocities increase linearly for small Valensi number and can be of order 1 for large Valensi number. Decreasing heat transfer between the gas and the tube decreases steady velocities for orifice pulse tubes. The opposite is true for basic pulse tubes. A conversion of steady work flow to heat flow occurs whenever temperature, velocity or phase angle gradients are present. Steady enthalpy flow is reduced by heat transfer and is scaled by the Prandtl times Valensi numbers. Particle velocities from a smoke-wire experiment were compared to predictions for basic and orifice pulse tube configurations. The theory predicted the observed mass streaming and flow reversals between the centerline and diffusion layers. The results indicate that the theory is valid for pulse tubes and can be used to solve for the zeroth-order temperature, to compute enthalpy flows, and to determine losses associated with steady secondary streaming.

Lee, Jeffrey Marshall

1997-11-01

131

Self-energy of an impurity in an ideal Fermi gas to second order in the interaction strength  

NASA Astrophysics Data System (ADS)

We study in three dimensions the problem of a spatially homogeneous zero-temperature ideal Fermi gas of spin-polarized particles of mass m perturbed by the presence of a single distinguishable impurity of mass M. The interaction between the impurity and the fermions involves only the partial s wave through the scattering length a and has negligible range b compared to the inverse Fermi wave number 1/kF of the gas. Through the interactions with the Fermi gas the impurity gives birth to a quasiparticle, which will be here a Fermi polaron (or more precisely a monomeron). We consider the general case of an impurity moving with wave vector K ?0: Then the quasiparticle acquires a finite lifetime in its initial momentum channel because it can radiate particle-hole pairs in the Fermi sea. A description of the system using a variational approach, based on a finite number of particle-hole excitations of the Fermi sea, then becomes inappropriate around K =0. We rely thus upon perturbation theory, where the small and negative parameter kFa?0- excludes any branches other than the monomeronic one in the ground state (as, e.g., the dimeronic one), and allows us a systematic study of the system. We calculate the impurity self-energy ?(2)(K,?) up to second order included in a. Remarkably, we obtain an analytical explicit expression for ?(2)(K,?), allowing us to study its derivatives in the plane (K,?). These present interesting singularities, which in general appear in the third-order derivatives ?3?(2)(K,?). In the special case of equal masses, M =m, singularities appear already in the physically more accessible second-order derivatives ?2?(2)(K,?); using a self-consistent heuristic approach based on ?(2) we then regularize the divergence of the second-order derivative ?K2?E(K) of the complex energy of the quasiparticle found in Trefzger and Castin [Europhys. Lett. 104, 50005 (2013), 10.1209/0295-5075/104/50005] at K =kF, and we predict an interesting scaling law in the neighborhood of K =kF. As a by product of our theory we have access to all moments of the momentum of the particle-hole pair emitted by the impurity while damping its motion in the Fermi sea at the level of Fermi's golden rule.

Trefzger, Christian; Castin, Yvan

2014-09-01

132

Similarity solution for the flow behind a shock wave in a non-ideal gas with heat conduction and radiation heat-flux in magnetogasdynamics  

NASA Astrophysics Data System (ADS)

The propagation of a spherical (or cylindrical) shock wave in a non-ideal gas with heat conduction and radiation heat-flux, in the presence of a spacially decreasing azimuthal magnetic field, driven out by a moving piston is investigated. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient ?R are assumed to vary with temperature and density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. The shock wave moves with variable velocity and the total energy of the wave is non-constant. Similarity solutions are obtained for the flow-field behind the shock and the effects of variation of the heat transfer parameters, the parameter of the non-idealness of the gas, both, decreases the compressibility of the gas and hence there is a decrease in the shock strength. Further, it is investigated that with an increase in the parameters of radiative and conductive heat transfer the tendency of formation of maxima in the distributions of heat flux, density and isothermal speed of sound decreases. The pressure and density vanish at the inner surface (piston) and hence a vacuum is form at the center of symmetry. The shock waves in conducting non-ideal gas with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of central part of star burst galaxies, nuclear explosion, chemical detonation, rupture of a pressurized vessels, in the analysis of data from exploding wire experiments, and cylindrically symmetric hypersonic flow problems associated with meteors or reentry vehicles, etc. The findings of the present works provided a clear picture of whether and how the non-idealness parameter, conductive and radiative heat transfer parameters and the magnetic field affect the flow behind the shock front.

Nath, G.; Vishwakarma, J. P.

2014-05-01

133

Thermodynamic properties of H 4SiO 4 in the ideal gas state as evaluated from experimental data  

NASA Astrophysics Data System (ADS)

Solid phases of silicon dioxide react with water vapor with the formation of hydroxides and oxyhydroxides of silica. Recent transpiration and mass-spectrometric studies convincingly demonstrate that H 4SiO 4 is the predominant form of silica in vapor phase at water pressure in excess of 10 -2 MPa. Available literature transpiration and solubility data for the reactions of solid SiO 2 phases and low-density water, extending from 424 to 1661 K, are employed for the determination of ?fG0, ?fH0 and S0 of H 4SiO 4 in the ideal gas state at 298.15 K, 0.1 MPa. In total, there are 102 data points from seven literature sources. The resulting values of the thermodynamic functions of H 4SiO 4(g) are: ?fG0 = -1238.51 ± 3.0 kJ mol -1, ?fH0 = -1340.68 ± 3.5 kJ mol -1 and S0 = 347.78 ± 6.2 J K -1 mol -1. These values agree quantitatively with one set of ab initio calculations. The relatively large uncertainties are mainly due to conflicting Cp0 data for H 4SiO 4(g) from various sources, and new determinations of Cp0 would be helpful. The thermodynamic properties of this species, H 4SiO 4(g), are necessary for realistic modeling of silica transport in a low-density water phase. Applications of this analysis may include the processes of silicates condensation in the primordial solar nebula, the precipitation of silica in steam-rich geothermal systems and the corrosion of SiO 2-containing alloys and ceramics in moist environments.

Plyasunov, Andrey V.

2011-07-01

134

Quantum Control of Molecular Gas Hydrodynamics  

NASA Astrophysics Data System (ADS)

We demonstrate that strong impulsive gas heating or heating suppression at standard temperature and pressure can occur from coherent rotational excitation or deexcitation of molecular gases using a sequence of nonionizing laser pulses. For the case of excitation, subsequent collisional decoherence of the ensemble leads to gas heating significantly exceeding that from plasma absorption under the same laser focusing conditions. In both cases, the macroscopic hydrodynamics of the gas can be finely controlled with ˜40 fs temporal sensitivity.

Zahedpour, S.; Wahlstrand, J. K.; Milchberg, H. M.

2014-04-01

135

Quantum lattice gas algorithm for the telegraph equation.  

PubMed

The telegraph equation combines features of both the diffusion and wave equations and has many applications to heat propagation, transport in disordered media, and elsewhere. We describe a quantum lattice gas algorithm (QLGA) for this partial differential equation with one spatial dimension. This algorithm generalizes one previously known for the diffusion equation. We present an analysis of the algorithm and accompanying simulation results. The QLGA is suitable for simulation on combined classical-quantum computers. PMID:19658625

Coffey, Mark W; Colburn, Gabriel G

2009-06-01

136

Bernoulli's formula and Poisson's equations for a confined quantum gas: Effects due to a moving piston  

E-print Network

We study a nonequilibrium equation of states of an ideal quantum gas confined in the cavity under a moving piston with a small but finite velocity in the case that the cavity wall suddenly begins to move at time origin. Confining to the thermally-isolated process, quantum non-adiabatic (QNA) contribution to Poisson's adiabatic equations and to Bernoulli's formula which bridges the pressure and internal energy is elucidated. We carry out a statistical mean of the non-adiabatic (time-reversal-symmetric) force operator found in our preceding paper (K. Nakamura et al, Phys. Rev. E Vol.83, 041133, (2011)) in both the low-temperature quantum-mechanical and high temperature quasi-classical regimes. The QNA contribution, which is proportional to square of the piston's velocity and to inverse of the longitudinal size of the cavity, has a coefficient dependent on temperature, gas density and dimensionality of the cavity. The investigation is done for a unidirectionally-expanding 3-d rectangular parallelepiped cavity as well as its 1-d version. Its relevance in a realistic nano-scale heat engine is discussed.

Katsuhiro Nakamura; Zarifboy A. Sobirov; Davron U. Matrasulov; Sanat K. Avazbaev

2012-12-25

137

Bernoulli's formula and Poisson's equations for a confined quantum gas: Effects due to a moving piston  

NASA Astrophysics Data System (ADS)

We study a nonequilibrium equation of states of an ideal quantum gas confined in the cavity under a moving piston with a small but finite velocity in the case in which the cavity wall suddenly begins to move at the time origin. Confining ourselves to the thermally isolated process, the quantum nonadiabatic (QNA) contribution to Poisson's adiabatic equations and to Bernoulli's formula which bridges the pressure and internal energy is elucidated. We carry out a statistical mean of the nonadiabatic (time-reversal-symmetric) force operator found in our preceding paper [Nakamura , Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.83.041133 83, 041133 (2011)] in both the low-temperature quantum-mechanical and high-temperature quasiclassical regimes. The QNA contribution, which is proportional to the square of the piston's velocity and to the inverse of the longitudinal size of the cavity, has a coefficient that is dependent on the temperature, gas density, and dimensionality of the cavity. The investigation is done for a unidirectionally expanding three-dimensional (3D) rectangular parallelepiped cavity as well as its 1D version. Its relevance in a realistic nanoscale heat engine is discussed.

Nakamura, Katsuhiro; Sobirov, Zarifboy A.; Matrasulov, Davron U.; Avazbaev, Sanat K.

2012-12-01

138

Quantum memory in warm rubidium vapor with buffer gas  

E-print Network

The realization of quantum memory using warm atomic vapor cells is appealing because of their commercial availability and the perceived reduction in experimental complexity. In spite of the ambiguous results reported in the literature, we demonstrate that quantum memory can be implemented in a single cell with buffer gas using the geometry where the write and read beams are nearly co-propagating. The emitted Stokes and anti-Stokes photons display cross-correlation values greater than 2, characteristic of quantum states, for delay times up to 4 microseconds.

Mark Bashkansky; Fredrik K. Fatemi; Igor Vurgaftman

2011-12-02

139

Quantum chemical studies of trace gas adsorption on ice nanoparticles  

NASA Astrophysics Data System (ADS)

We have investigated the interaction of atmospheric trace gases with crystalline water ice particles of nanoscale size by modern quantum chemical methods. Small ice particles which can be formed in different altitudes play an important role in chemistry and physics of the Earth atmosphere. Knowledge about the uptake and incorporation of atmospheric trace gases in ice particles as well as their interactions with water molecules is very important for the understanding of processes at the air/ice interface. The interaction of the atmospheric trace gases with atmospheric ice nanoparticles is also an important issue for the development of modern physicochemical models. Usually, the interactions between trace gases and small particles considered theoretically apply small-size model complexes or the surface models representing only fragments of the ideal surface. Ice particles consisting of 48, 72, 216 and 270 water molecules with a distorted structure of hexagonal water ice Ih were studied using the new SCC-DFTBA method combining well the advantages of the DFT theory and semiempirical methods of quantum chemistry. The largest clusters correspond to the minimal nanoparticle size which are considered to be crystalline as determined experimentally. The clusters up to (H2O)72 were studied at the B3LYP/6-31++G(d,p) and B3LYP/6-311++G(2d,2p) levels. The larger clusters were studied using DFTBA and DFTB+ methods. Several adsorption complexes for the (H2O)270 water ice cluster were optimized at the RI-BLYP/6-31+G(d) theory level to verify the DFTB+ results. Trace gas molecules were coordinated on different sites of the nanoparticles corresponding to different ice Ih crystal planes: (0001), (10-10), (11-20). As atmospheric trace gases we have chosen CO, CO2, HCO*, HCOH*, HCHO, HCOOH and (HCO)2. which are the possible products and intermediates of the UV photolysis of organic molecules such as HCHCHO adsorbed on the ice surface. The structures of the corresponding coordination complexes, their vibrational frequencies, their adsorption energies and thermodynamic parameters (the enthalpy and the Gibbs free energy of adsorption) were evaluated using the full optimization followed by the frequency calculations. Additionally, the different modes of incorporation of trace gas molecules into the ice particles were considered and the corresponding structural and energetic parameters were evaluated. The transition states for the possible hydration were located and the influence of the water cluster surrounding on the barrier heights was studied as well. Acknowledgements: Financial support by the Russian Foundation for basic Research, project No. 11-03-00085 and German Academic Exchange Service (DAAD) within the Eastpartnership program is greatly acknowledged. O.B.G. and A.E.M. are grateful to DOE NERSC, I2lab, and Institute for Simulation and Training (IST) for making computer time available.

Schrems, Otto; Ignatov, Stanislav K.; Gadzhiev, Oleg B.; Masunov, Artem E.

2013-04-01

140

An accurate, residue-level, pair potential of mean force for folding and binding based on the distance-scaled, ideal-gas reference state  

Microsoft Academic Search

Structure prediction on a genomic scale requires a simplified energy function that can efficiently sample the conformational space of polypeptide chains. A good energy function at minimum should discriminate native structures against decoys. Here, we show that a recently developed, residue-specific, all-atom knowledge- based potential (167 atomic types) based on distance-scaled, finite ideal-gas reference state (DFIRE-all- atom) can be substantially

CHI ZHANG; SONG LIU; HONGYI ZHOU; YAOQI ZHOU

2004-01-01

141

Dipolar quantum electrodynamics of the two-dimensional electron gas  

NASA Astrophysics Data System (ADS)

Similarly to a previous work on the homogeneous electron gas [Y. Todorov, Phys. Rev. B 89, 075115 (2014), 10.1103/PhysRevB.89.075115], we apply the Power-Zienau-Wooley (PZW) formulation of the quantum electrodynamics to the case of an electron gas quantum confined by one-dimensional potential. We provide a microscopic description of all collective plasmon modes of the gas, oscillating both along and perpendicular to the direction of quantum confinement. Furthermore, we study the interaction of the collective modes with a photonic structure, planar metallic waveguide, by using the full expansion of the electromagnetic field into normal modes. We show how the boundary conditions for the electromagnetic field influence both the transverse light-matter coupling and the longitudinal particle-particle interactions. The PZW descriptions appear thus as a convenient tool to study semiconductor quantum optics in geometries where quantum-confined particles interact with strongly confined electromagnetic fields in microresonators, such as the ones used to achieve the ultrastrong light-matter coupling regime.

Todorov, Yanko

2015-03-01

142

Equation of state and ideal-gas heat capacity of a gaseous mixture of 1,1,1,2-tetrafluoroethane, pentafluoroethane, and difluoromethane  

SciTech Connect

The authors present the gas-phase equation of state and ideal-gas heat capacity of a ternary mixture of 1,1,1,2-tetrafluoroethane (35%), pentafluoroethane (30%), and difluoromethane (35%) for temperatures between 260 and 453 K and pressures between 0.05 and 7.7 MPa. These results were based on two very different measurement techniques. The first technique measured the gas density of the mixture in a Burnett apparatus from 313 to 453 K and from 0.2 to 7.7 MPa. The second technique deduced the gas density and ideal-gas heat capacity from high-accuracy speed-of-sound measurements in the mixture at temperatures between 260 and 400 K and at pressures between 0.05 and 1.0 MPa. The data from the two techniques were analyzed together to obtain an equation of state that reproduced the densities from the Burnett technique with a fractional RMS deviation of 0.038%, and it also reproduced the sound speeds with a fractional RMS deviation of 0.003%. Finally, the results are compared to a predictive model based on the properties of the pure fluids.

Hurly, J.J.; Schmidt, J.W.; Gillis, K.A. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

1997-05-01

143

Quantum Magnetoconductance of a Nondegenerate Two-Dimensional Electron Gas  

Microsoft Academic Search

Magnetoconductance measurements are reported for the low-density, two-dimensional classical electron gas formed on the surface of liquid helium. At strong magnetic fields, large deviations from the classical parabolic behaviour are observed. These deviations are described with a quantum-transport theory of scattering within broadened Landau levels.

R. W. van der Heijden; J. H. G. Surewaard; H. M. Gijsman; F. M. Peeters

1988-01-01

144

WHEN IS A QUANTUM GAS A QUANTUM LIQUID?  

Microsoft Academic Search

We report on measurements of the excitation spectrum of a strongly interact- ing Bose-Einstein condensate (BEC). A magnetic-fleld Feshbach resonance is used to tune atom-atom interactions in the condensate and to reach a regime where quantum depletion and beyond mean-fleld corrections to the condensate chemical potential are signiflcant. We use two-photon Bragg spectroscopy to probe the condensate excitation spectrum; our

J. M. PINO; R. J. WILD; S. B. PAPP; S. RONEN; D. S. JIN; E. A. CORNELL

2008-01-01

145

When is a Quantum Gas a Quantum Liquid?  

Microsoft Academic Search

We report on measurements of the excitation spectrum of a strongly interacting Bose-Einstein condensate (BEC). A magnetic-field Feshbach resonance is used to tune atom-atom interactions in the condensate and to reach a regime where quantum depletion and beyond mean-field corrections to the condensate chemical potential are significant. We use two-photon Bragg spectroscopy to probe the condensate excitation spectrum; our results

J. M. Pino; R. J. Wild; S. B. Papp; S. Ronen; D. S. Jin; E. A. Cornell

2009-01-01

146

Stability of a trapped dipolar quantum gas  

NASA Astrophysics Data System (ADS)

We calculate the stability diagram for a trapped normal Fermi or Bose gas with dipole-dipole interactions. Our study characterizes the roles of trap geometry and temperature on the stability using Hartree-Fock theory. We find that exchange appreciably reduces stability and that, for bosons, the double instability feature in oblate trapping geometries predicted previously is still predicted by the Hartree-Fock theory. Our results are relevant to current experiments with polar molecules and will be useful in developing strategies to obtain a polar molecule Bose-Einstein condensate or degenerate Fermi gas.

Baillie, D.; Bisset, R. N.; Blakie, P. B.

2015-01-01

147

Using Rubber-Elastic Material Ideal Gas Analogies to Teach Introductory Thermodynamics. Part II: The Laws of Thermodynamics  

Microsoft Academic Search

Polymeric rubber-elastic material (REM) is in many ways analogous to ideal gases. This may be used to good advantage as a supplementary system for teaching elementary thermodynamic concepts, equations of state, and the laws of thermodynamics. Part II includes thermometry and the zeroth law, heat, work, energy and the first law, Joule's law, heat capacity, adiabats and isotherms, enthalpy, heat

Brent Smith

2002-01-01

148

Photoacoustic Spectroscopy with Quantum Cascade Lasers for Trace Gas Detection  

PubMed Central

Various applications, such as pollution monitoring, toxic-gas detection, non invasive medical diagnostics and industrial process control, require sensitive and selective detection of gas traces with concentrations in the parts in 109 (ppb) and sub-ppb range. The recent development of quantum-cascade lasers (QCLs) has given a new aspect to infrared laser-based trace gas sensors. In particular, single mode distributed feedback QCLs are attractive spectroscopic sources because of their excellent properties in terms of narrow linewidth, average power and room temperature operation. In combination with these laser sources, photoacoustic spectroscopy offers the advantage of high sensitivity and selectivity, compact sensor platform, fast time-response and user friendly operation. This paper reports recent developments on quantum cascade laser-based photoacoustic spectroscopy for trace gas detection. In particular, different applications of a photoacoustic trace gas sensor employing a longitudinal resonant cell with a detection limit on the order of hundred ppb of ozone and ammonia are discussed. We also report two QC laser-based photoacoustic sensors for the detection of nitric oxide, for environmental pollution monitoring and medical diagnostics, and hexamethyldisilazane, for applications in semiconductor manufacturing process.

Elia, Angela; Di Franco, Cinzia; Lugarà, Pietro Mario; Scamarcio, Gaetano

2006-01-01

149

Generalized susceptibilities for a perfect quantum gas  

E-print Network

The system we consider here is a charged fermions gas in the effective mass approximation, and in grand-canonical conditions. We assume that the particles are confined in a three dimensional cubic box $\\Lambda$ with side $L\\geq 1$, and subjected to a constant magnetic field of intensity $ B \\geq 0 $. Define the grand canonical generalized susceptibilities $\\chi_L^N$, $N\\geq 1$, as successive partial derivatives with respect to $B$ of the grand canonical pressure $P_L$. Denote by $P_{\\infty}$ the thermodynamic limit of $P_L$. Our main result is that $\\chi_L^N$ admit as thermodynamic limit the corresponding partial derivatives with respect to $B$ of $P_{\\infty}$. In this paper we only give the main steps of the proofs, technical details will be given elsewhere.

Philippe Briet; Horia D. Cornean; Delphine Louis

2006-05-05

150

Finite-Difference Solution for Laminar or Turbulent Boundary Layer Flow over Axisymmetric Bodies with Ideal Gas, CF4, or Equilibrium Air Chemistry  

NASA Technical Reports Server (NTRS)

A computer code was developed that uses an implicit finite-difference technique to solve nonsimilar, axisymmetric boundary layer equations for both laminar and turbulent flow. The code can treat ideal gases, air in chemical equilibrium, and carbon tetrafluoride (CF4), which is a useful gas for hypersonic blunt-body simulations. This is the only known boundary layer code that can treat CF4. Comparisons with experimental data have demonstrated that accurate solutions are obtained. The method should prove useful as an analysis tool for comparing calculations with wind tunnel experiments and for making calculations about flight vehicles where equilibrium air chemistry assumptions are valid.

Hamilton, H. Harris, II; Millman, Daniel R.; Greendyke, Robert B.

1992-01-01

151

The spin Hall effect in a quantum gas.  

PubMed

Electronic properties such as current flow are generally independent of the electron's spin angular momentum, an internal degree of freedom possessed by quantum particles. The spin Hall effect, first proposed 40 years ago, is an unusual class of phenomena in which flowing particles experience orthogonally directed, spin-dependent forces--analogous to the conventional Lorentz force that gives the Hall effect, but opposite in sign for two spin states. Spin Hall effects have been observed for electrons flowing in spin-orbit-coupled materials such as GaAs and InGaAs (refs 2, 3) and for laser light traversing dielectric junctions. Here we observe the spin Hall effect in a quantum-degenerate Bose gas, and use the resulting spin-dependent Lorentz forces to realize a cold-atom spin transistor. By engineering a spatially inhomogeneous spin-orbit coupling field for our quantum gas, we explicitly introduce and measure the requisite spin-dependent Lorentz forces, finding them to be in excellent agreement with our calculations. This 'atomtronic' transistor behaves as a type of velocity-insensitive adiabatic spin selector, with potential application in devices such as magnetic or inertial sensors. In addition, such techniques for creating and measuring the spin Hall effect are clear prerequisites for engineering topological insulators and detecting their associated quantized spin Hall effects in quantum gases. As implemented, our system realizes a laser-actuated analogue to the archetypal semiconductor spintronic device, the Datta-Das spin transistor. PMID:23739329

Beeler, M C; Williams, R A; Jiménez-García, K; LeBlanc, L J; Perry, A R; Spielman, I B

2013-06-13

152

Condensation of N bosons. II. Nonequilibrium analysis of an ideal Bose gas and the laser phase-transition analogy  

E-print Network

study the so-called canonical ensemble problem. It describes, in some sense, an intermediate situation as com- pared with the microcanonical ensemble and the grand- canonical ensemble. In the microcanonical ensemble, the gas is completely isolated, E...

Kocharovsky, VV; Scully, Marlan O.; Zhu, S. Y.; Zubairy, M. Suhail

2000-01-01

153

Control of hot-carrier relaxation for realizing ideal quantum-dot intermediate-band solar cells.  

PubMed

For intermediate-band solar cells, the broad absorption spectrum of quantum dots (QDs) offers a favorable conversion efficiency, and photocurrent generation via efficient two-step two-photon-absorption (TS-TPA) in QDs is essential for realizing high-performance solar cells. In the last decade, many works were dedicated to improve the TS-TPA efficiency by modifying the QD itself, however, the obtained results are far from the requirements for practical applications. To reveal the mechanisms behind the low TS-TPA efficiency in QDs, we report here on two- and three-beam photocurrent measurements of InAs quantum structures embedded in AlGaAs. Comparison of two- and three-beam photocurrent spectra obtained by subbandgap excitation reveals that the QD TS-TPA efficiency is improved significantly by suppressing the relaxation of hot TS-TPA carriers to unoccupied shallow InAs quantum structure states. PMID:24535195

Tex, David M; Kamiya, Itaru; Kanemitsu, Yoshihiko

2014-01-01

154

Ultrastable, Zerodur-based optical benches for quantum gas experiments.  

PubMed

Operating ultracold quantum gas experiments outside of a laboratory environment has so far been a challenging goal, largely due to the lack of sufficiently stable optical systems. In order to increase the thermal stability of free-space laser systems, the application of nonstandard materials such as glass ceramics is required. Here, we report on Zerodur-based optical systems which include single-mode fiber couplers consisting of multiple components jointed by light-curing adhesives. The thermal stability is thoroughly investigated, revealing excellent fiber-coupling efficiencies between 0.85 and 0.92 in the temperature range from 17°C to 36°C. In conjunction with successfully performed vibration tests, these findings qualify our highly compact systems for atom interferometry experiments aboard a sounding rocket as well as various other quantum information and sensing applications. PMID:25090066

Duncker, Hannes; Hellmig, Ortwin; Wenzlawski, André; Grote, Alexander; Rafipoor, Amir Jones; Rafipoor, Mona; Sengstock, Klaus; Windpassinger, Patrick

2014-07-10

155

External cavity tunable quantum cascade lasers and their applications to trace gas monitoring.  

PubMed

Since the first quantum cascade laser (QCL) was demonstrated approximately 16 years ago, we have witnessed an explosion of interesting developments in QCL technology and QCL-based trace gas sensors. QCLs operate in the mid-IR region (3-24??m) and can directly access the rotational vibrational bands of most molecular species and, therefore, are ideally suited for trace gas detection with high specificity and sensitivity. These sensors have applications in a wide range of fields, including environmental monitoring, atmospheric chemistry, medical diagnostics, homeland security, detection of explosive compounds, and industrial process control, to name a few. Tunable external cavity (EC)-QCLs in particular offer narrow linewidths, wide ranges of tunability, and stable power outputs, which open up new possibilities for sensor development. These features allow for the simultaneous detection of multiple species and the study of large molecules, free radicals, ions, and reaction kinetics. In this article, we review the current status of EC-QCLs and sensor developments based on them and speculate on possible future developments. PMID:21283214

Rao, Gottipaty N; Karpf, Andreas

2011-02-01

156

Cooling an electron gas using quantum dot based electronic refrigeration  

E-print Network

Cooling an electron gas using quantum dot based electronic refrigeration Jonathan Robert Prance August 28, 2009 Downing College, University of Cambridge A thesis submitted for the degree of Doctor of Philosophy Preface The work presented... dots. Conventionally, low temperature measurements of 2DEGs are made by cooling the sample to 1.5 K with liquid Helium-4, to 300 mK with liquid Helium-3, or even down to a few mK using a dilution refrigerator. However, at lower temperatures the electron...

Prance, Jonathan Robert

2009-10-13

157

Quintessence and (anti-)Chaplygin gas in loop quantum cosmology  

SciTech Connect

The concordance model of cosmology contains several unknown components such as dark matter and dark energy. Many proposals have been made to describe them by choosing an appropriate potential for a scalar field. We study four models in the realm of loop quantum cosmology: the Chaplygin gas, an inflationary and radiationlike potential, quintessence and an anti-Chaplygin gas. For the latter we show that all trajectories start and end with a type II singularity and, depending on the initial value, may go through a bounce. On the other hand the evolution under the influence of the first three scalar fields behaves classically at times far away from the big bang singularity and bounces as the energy density approaches the critical density.

Lamon, Raphael; Woehr, Andreas J. [Institut fuer Theoretische Physik, Universitaet Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany)

2010-01-15

158

Ideal square quantum wells achieved in AlGaN/GaN superlattices using ultrathin blocking-compensation pair  

NASA Astrophysics Data System (ADS)

A technique for achieving square-shape quantum wells (QWs) against the intrinsic polar discontinuity and interfacial diffusion through self-compensated pair interlayers is reported. Ultrathin low-and-high % pair interlayers that have diffusion-blocking and self-compensation capacities is proposed to resist the elemental diffusion at nanointerfaces and to grow the theoretically described abrupt rectangular AlGaN/GaN superlattices by metal-organic chemical vapor deposition. Light emission efficiency in such nanostructures is effectively enhanced and the quantum-confined Stark effect could be partially suppressed. This concept could effectively improve the quality of ultrathin QWs in functional nanostructures with other semiconductors or through other growth methods.

Chen, Xiaohong; Xu, Hongmei; Lin, Na; Xu, Fuchun; Chen, Hangyang; Cai, Duanjun; Kang, Junyong

2015-03-01

159

Sex Education and Ideals  

ERIC Educational Resources Information Center

This article argues that sex education should include sexual ideals. Sexual ideals are divided into sexual ideals in the strict sense and sexual ideals in the broad sense. It is argued that ideals that refer to the context that is deemed to be most ideal for the gratification of sexual ideals in the strict sense are rightfully called sexual…

de Ruyter, Doret J.; Spiecker, Ben

2008-01-01

160

Cyclotron resonance photoconductivity of a two-dimensional electron gas in HgTe quantum wells  

E-print Network

Cyclotron resonance photoconductivity of a two-dimensional electron gas in HgTe quantum wells Ze-infrared cyclotron resonance photoconductivity (CRP) is investigated in HgTe quantum wells (QWs) of various widths that the transport time substantially exceeds the cyclotron resonance lifetime as well as the quantum lifetime which

Ganichev, Sergey

161

Indium phthalocyanine-CdSe/ZnS quantum dots nanocomposites showing size dependent and near ideal optical limiting behaviour  

NASA Astrophysics Data System (ADS)

Indium phthalocyanine-CdSe/ZnS quantum dots (QDs) nanocomposites (InPc-CdSe/ZnS) of three sizes (5.57, 8.12 and 8.75 nm) were synthesized according to known procedures. The particle size of the CdSe/ZnS QDs alone are 3.95, 6.02, and 6.66 nm, and are denoted as QD1, QD2 and QD3 respectively. The nonlinear absorption (NLA) properties of the nanoconjugates (InPc-CdSe/ZnS) were investigated with nanosecond laser radiation at 532 nm wavelength. Enhanced NLA properties compared to the InPc alone were observed in the conjugates. The NLA was found to increase with the size of the CdSe/ZnS particles attached to the phthalocyanine. The observed increase was due to the availability of more free-carrier ions in the larger QDs, thus giving rise to the enhanced free-carrier absorption. The measured free-carrier absorption cross-sections (?FCA) are 1.10, 1.65 and 1.95 (×10-19 cm2) for InPc-QD1, InPc-QD2 and InPc-QD3 respectively. The nanoconjugates (InPc-CdSe/ZnS) showed a much lower threshold for optical limiting together with a much lower transmission at high fluences, than the previously reported nanocomposite limiters.

Sanusi, Kayode; Nyokong, Tebello

2014-12-01

162

SnO2 quantum dots and quantum wires: controllable synthesis, self-assembled 2D architectures, and gas-sensing properties.  

PubMed

SnO2 quantum dots (QDs) and ultrathin nanowires (NWs) with diameters of approximately 0.5-2.5 and approximately 1.5-4.5 nm, respectively, were controllably synthesized in a simple solution system. They are supposed to be ideal models for studying the continuous evolution of the quantum-confinement effect in SnO2 1D --> 0D systems. The observed transition from strong to weak quantum confinement in SnO2 QDs and ultrathin NWs is interpreted through the use of the Brus effective-mass approximation and the Nosaka finite-depth well model. Photoluminescence properties that were coinfluenced by size effects, defects (oxygen vacancies), and surface capping are discussed in detail. With the SnO2 QDs as building blocks, various 2D porous structures with ordered hexagonal, distorted hexagonal, and square patterns were prepared on silicon-wafer surfaces and exhibited optical features of 2D photonic crystals and enhanced gas sensitivity. PMID:18715007

Xu, Xiangxing; Zhuang, Jing; Wang, Xun

2008-09-17

163

Quantum holographic encoding in a two-dimensional electron gas  

SciTech Connect

The advent of bottom-up atomic manipulation heralded a new horizon for attainable information density, as it allowed a bit of information to be represented by a single atom. The discrete spacing between atoms in condensed matter has thus set a rigid limit on the maximum possible information density. While modern technologies are still far from this scale, all theoretical downscaling of devices terminates at this spatial limit. Here, however, we break this barrier with electronic quantum encoding scaled to subatomic densities. We use atomic manipulation to first construct open nanostructures - 'molecular holograms' - which in turn concentrate information into a medium free of lattice constraints: the quantum states of a two-dimensional degenerate Fermi gas of electrons. The information embedded in the holograms is transcoded at even smaller length scales into an atomically uniform area of a copper surface, where it is densely projected into both two spatial degrees of freedom and a third holographic dimension mapped to energy. In analogy to optical volume holography, this requires precise amplitude and phase engineering of electron wavefunctions to assemble pages of information volumetrically. This data is read out by mapping the energy-resolved electron density of states with a scanning tunnelling microscope. As the projection and readout are both extremely near-field, and because we use native quantum states rather than an external beam, we are not limited by lensing or collimation and can create electronically projected objects with features as small as {approx}0.3 nm. These techniques reach unprecedented densities exceeding 20 bits/nm{sup 2} and place tens of bits into a single fermionic state.

Moon, Christopher

2010-05-26

164

Quantum fluctuations in the image of a Bose gas  

E-print Network

We analyze the information content of density profiles for an ultracold Bose gas of atoms and extract resolution limits for observables contained in these images. Our starting point is density correlations that we compute within the Bogoliubov approximation, taking into account quantum and thermal fluctuations beyond mean-field theory. This provides an approximate way to construct the joint counting statistics of atoms in an array of pixels covering the gas. We derive the Fisher information of an image and the associated Cramer-Rao sensitivity bound for measuring observables contained in the image. We elaborate on our recent study on position measurements of a dark soliton [Negretti et al., Phys. Rev. A 77, 043606 (2008)] where a sensitivity scaling with the atomic density as n^{-3/4} was found. We discuss here a wider class of soliton solutions and present a detailed analysis of the Bogoliubov excitations and the gapless (Goldstone) excitation modes. These fluctuations around the mean field contribute to the noise in the image, and we show how they can actually improve the ability to locate the position of the soliton.

Antonio Negretti; Carsten Henkel; Klaus Molmer

2008-08-27

165

Thermodynamics of Quantum Ultra-cold Neutron Gas under Gravity of The Earth  

E-print Network

The stored ultra-cold neutrons have been developed. A high density ultra-cold neutron gas has been recently produced by using the nuclear spallation method. We investigate the thermodynamic properties of the quantum ultra-cold neutron gas in the Earth's gravitational field. We find that the quantum effects increase temperature dependence of the chemical potential and the internal energy in the low temperature region. The density distribution of quantum ultra-cold neutron gas is modified by the Earth's gravitational field.

Hiromi Kaneko; Akihiro Tohsaki; Atsushi Hosaka

2012-06-29

166

Suppression of the quantum-mechanical collapse by repulsive interactions in a quantum gas  

SciTech Connect

The quantum-mechanical collapse (alias fall onto the center of particles attracted by potential -r{sup -2}) is a well-known issue in quantum theory. It is closely related to the quantum anomaly, i.e., breaking of the scaling invariance of the respective Hamiltonian by quantization. We demonstrate that the mean-field repulsive nonlinearity prevents the collapse and thus puts forward a solution to the quantum-anomaly problem that differs from that previously developed in the framework of the linear quantum-field theory. This solution may be realized in the 3D or 2D gas of dipolar bosons attracted by a central charge and in the 2D gas of magnetic dipoles attracted by a current filament. In the 3D setting, the dipole-dipole interactions are also taken into regard, in the mean-field approximation, resulting in a redefinition of the scattering length which accounts for the contact repulsion between the bosons. In lieu of the collapse, the cubic nonlinearity creates a 3D ground state (GS), which does not exist in the respective linear Schroedinger equation. The addition of the harmonic trap gives rise to a tristability, in the case when the Schroedinger equation still does not lead to the collapse. In the 2D setting, the cubic nonlinearity is not strong enough to prevent the collapse; however, the quintic term does it, creating the GS, as well as its counterparts carrying the angular momentum (vorticity). Counterintuitively, such self-trapped 2D modes exist even in the case of a weakly repulsive potential r{sup -2}. The 2D vortical modes avoid the phase singularity at the pivot (r=0) by having the amplitude diverging at r{yields}0 instead of the usual situation with the amplitude of the vortical mode vanishing at r{yields}0 (the norm of the mode converges despite of the singularity of the amplitude at r{yields}0). In the presence of the harmonic trap, the 2D quintic model with a weakly repulsive central potential r{sup -2} gives rise to three confined modes, the middle one being unstable, spontaneously developing into a breather. In both the 3D and 2D cases, the GS wave functions are found in a numerical form and in the form of an analytical approximation, which is asymptotically exact in the limit of the large norm.

Sakaguchi, Hidetsugu [Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Malomed, Boris A. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)

2011-01-15

167

Assembling gas-phase reaction mechanisms for high temperature inorganic systems based on quantum chemistry calculations  

E-print Network

Assembling gas-phase reaction mechanisms for high temperature inorganic systems based on quantum chemistry calculations and reaction rate theories Mark T. Swihart* Department of Chemical Engineering quantum chemistry and reaction rate theories. In addition, for both of these cases there is a database

Swihart, Mark T.

168

Prime ideals in quantum algebras   

E-print Network

The central objects of study in this thesis are quantized coordinate algebras. These algebras originated in the 1980s in the work of Drinfeld and Jumbo and are noncommutative analogues of coordinate rings of algebraic ...

Russell, Ewan

169

Buoyancy-Driven Heat Transfer During Application of a Thermal Gradient for the Study of Vapor Deposition at Low Pressure Using and Ideal Gas  

NASA Technical Reports Server (NTRS)

A mathematical model has been developed to determine heat transfer during vapor deposition of source materials under a variety of orientations relative to gravitational accelerations. The model demonstrates that convection can occur at total pressures as low as 10-2 mm Hg. Through numerical computation, using physical material parameters of air, a series of time steps demonstrates the development of flow and temperature profiles during the course of vapor deposition. These computations show that in unit gravity vapor deposition occurs by transport through a fairly complicated circulating flow pattern when applying heat to the bottom of the vessel with parallel orientation with respect to the gravity vector. The model material parameters for air predict the effect of kinematic viscosity to be of the same order as thermal diffusivity, which is the case for Prandtl number approx. 1 fluids. Qualitative agreement between experiment and the model indicates that 6-(2-methyl-4-nitroanilino)-2,4-hexadiyn-l-ol (DAMNA) at these pressures indeed approximates an ideal gas at the experiment temperatures, and may validate the use of air physical constants. It is apparent that complicated nonuniform temperature distribution in the vapor could dramatically affect the homogeneity, orientation, and quality of deposited films. The experimental test i's a qualitative comparison of film thickness using ultraviolet-visible spectroscopy on films generated in appropriately oriented vapor deposition cells. In the case where heating of the reaction vessel occurs from the top, deposition of vapor does not normally occur by convection due to a stable stratified medium. When vapor deposition occurs in vessels heated at the bottom, but oriented relative to the gravity vector between these two extremes, horizontal thermal gradients induce a complex flow pattern. In the plane parallel to the tilt axis, the flow pattern is symmetrical and opposite in direction from that where the vessel is positioned vertically. The ground-based experiments are sufficient preliminary tests of theory and should be of significant interest regarding vapor deposited films in microgravity.

Frazier, D. O.; Hung, R. J.; Paley, M. S.; Penn, B. G.; Long, Y. T.

1996-01-01

170

Quantum-cascade laser photoacoustic detection of methane emitted from natural gas powered engines  

NASA Astrophysics Data System (ADS)

In this work we present a laser photoacoustic arrangement for the detection of the important greenhouse gas methane. A quantum-cascade laser and a differential photoacoustic cell were employed. A detection limit of 45 ppbv in nitrogen was achieved as well as a great selectivity. The same methodology was also tested in the detection of methane issued from natural gas powered vehicles (VNG) in Brazil, which demonstrates the excellent potential of this arrangement for greenhouse gas detection emitted from real sources.

Rocha, M. V.; Sthel, M. S.; Silva, M. G.; Paiva, L. B.; Pinheiro, F. W.; Miklòs, A.; Vargas, H.

2012-03-01

171

Construction of a quantum gas microscope for fermionic atoms  

E-print Network

This thesis reports the construction of a novel apparatus for experiments with ultracold atoms in optical lattices: the Fermi gas microscope. Improving upon similar designs for bosonic atoms, our Fermi gas microscope has ...

Ramasesh, Vinay (Vinay V.)

2013-01-01

172

White noise approach to the low density limit of a quantum particle in a gas  

E-print Network

The white noise approach to the investigation of the dynamics of a quantum particle interacting with a dilute and in general non-equilibrium gaseous environment in the low density limit is outlined. The low density limit is the kinetic Markovian regime when only pair collisions (i.e., collisions of the test particle with one particle of the gas at one time moment) contribute to the dynamics. In the white noise approach one first proves that the appropriate operators describing the gas converge in the sense of appropriate matrix elements to certain operators of quantum white noise. Then these white noise operators are used to derive quantum white noise and quantum stochastic equations describing the approximate dynamics of the total system consisting of the particle and the gas. The derivation is given ab initio, starting from the exact microscopic quantum dynamics. The limiting dynamics is described by a quantum stochastic equation driven by a quantum Poisson process. This equation then applied to the derivation of quantum Langevin equation and linear Boltzmann equation for the reduced density matrix of the test particle. The first part of the paper describes the approach which was developed by L. Accardi, I.V. Volovich and the author and uses the Fock-antiFock (or GNS) representation for the CCR algebra of the gas. The second part presents the approach to the derivation of the limiting equations directly in terms of the correlation functions, without use of the Fock-antiFock representation. This approach simplifies the derivation and allows to express the strength of the quantum number process directly in terms of the one-particle $S$-matrix.

Alexander Pechen

2006-07-19

173

Soft Ideals and Arithmetic Mean Ideals  

Microsoft Academic Search

.  This article investigates the soft-interior (se) and the soft-cover (sc) of operator ideals. These operations, and especially\\u000a the first one, have been widely used before, but making their role explicit and analyzing their interplay with the arithmetic\\u000a mean operations is essential for the study in [10] of the multiplicity of traces. Many classical ideals are ‘soft’, i.e.,\\u000a coincide with their

Victor Kaftal; Gary Weiss

2007-01-01

174

Computing Toric Ideals  

Microsoft Academic Search

Toric ideals are binomial ideals which represent the algebraic relations of sets of power products. They appear in many problems arising from different branches of mathematics. In this paper, we develop new theories which allow us to devise a parallel algorithm and an efficient elimination algorithm. In many respects they improve existing algorithms for the computation of toric ideals.

Anna Maria Bigatti; Roberto La Scala; Lorenzo Robbiano

1999-01-01

175

Quantum Control by Imaging : The Zeno effect in an ultracold lattice gas  

E-print Network

We demonstrate the control of quantum tunneling in an ultracold lattice gas by the measurement backaction imposed by an imaging process. A {\\em in situ} imaging technique is used to acquire repeated images of an ultracold gas confined in a shallow optical lattice. The backaction induced by these position measurements modifies the coherent quantum tunneling of atoms within the lattice. By smoothly varying the rate at which spatial information is extracted from the atomic ensemble, we observe the continuous crossover from the 'weak measurement regime' where position measurements have little influence on the tunneling dynamics, to the 'strong measurement regime' where measurement-induced localization causes a large suppression of tunneling. This suppression of coherent tunneling is a manifestation of the Quantum Zeno effect. Our study realizes an experimental demonstration of the paradigmatic Heisenberg microscope in a lattice gas and sheds light on the implications of quantum measurement on the coherent evolution of a mesoscopic quantum system. In addition, this demonstrates a powerful technique for the control of an interacting many-body quantum system via spatially resolved measurement backaction.

Y. S. Patil; S. Chakram; M. Vengalattore

2014-11-11

176

Exchange instability of the two-dimensional electron gas in semiconductor quantum wells A. R. Gon~i,1  

E-print Network

Exchange instability of the two-dimensional electron gas in semiconductor quantum wells A. R. Gon-dimensional 2D electron gas formed in a modulation-doped GaAs/AlxGa1 xAs single quantum well undergoes a first- functional theory, which treat the 2D exchange potential exactly, show that this thermodynamical instability

Nabben, Reinhard

177

Impurity transport through a strongly interacting bosonic quantum gas  

SciTech Connect

Using near-exact numerical simulations, we study the propagation of an impurity through a one-dimensional Bose lattice gas for varying bosonic interaction strengths and filling factors at zero temperature. The impurity is coupled to the Bose gas and confined to a separate tilted lattice. The precise nature of the transport of the impurity is specific to the excitation spectrum of the Bose gas, which allows one to measure properties of the Bose gas nondestructively, in principle, by observing the impurity; here we focus on the spatial and momentum distributions of the impurity as well as its reduced density matrix. For instance, we show it is possible to determine whether the Bose gas is commensurately filled as well as the bandwidth and gap in its excitation spectrum. Moreover, we show that the impurity acts as a witness to the crossover of its environment from the weakly to the strongly interacting regime, i.e., from a superfluid to a Mott insulator or Tonks-Girardeau lattice gas, and the effects on the impurity in both of these strongly interacting regimes are clearly distinguishable. Finally, we find that the spatial coherence of the impurity is related to its propagation through the Bose gas.

Johnson, T. H. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Clark, S. R. [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore); Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Keble College, University of Oxford, Parks Road, Oxford OX1 3PG (United Kingdom); Bruderer, M. [Fachbereich Physik, Universitaet Konstanz, D-78457 Konstanz (Germany); Jaksch, D. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore); Keble College, University of Oxford, Parks Road, Oxford OX1 3PG (United Kingdom)

2011-08-15

178

Engineering Light: Quantum Cascade Lasers  

SciTech Connect

Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.

Claire Gmachl

2010-03-17

179

Engineering Light: Quantum Cascade Lasers  

ScienceCinema

Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.

Claire Gmachl

2010-09-01

180

PET 424304 2013 Exercises 1+2 of 4 12 Feb + 14 Feb 2013 1. ideal gas: s = s2-s1 = cpln(T2/T1) -R ln(p2/p1) (T << Tcrit; p << pcrit)  

E-print Network

PET 424304 2013 Exercises 1+2 of 4 12 Feb + 14 Feb 2013 1. ideal gas: s = s2- s1 = cp·ln(T2/T1,1 kWh/kg Al) This is also the minimum exergy input need for Al production from pure Al2O3. PET 424304 be neglected for this purity !) molkJ n bn b i i i o ichemi o /7020 , #12;PET 424304 2013 Exercises 1+2 of 4

Zevenhoven, Ron

181

High-resolution scanning electron microscopy of an ultracold quantum gas  

E-print Network

detection provides single-atom sensitivity. The total ionization cross-section for rubidium at 6 ke with no detectable signal. As the cross-section is eight orders of magnitude smaller than the absorption cross-sectionARTICLES High-resolution scanning electron microscopy of an ultracold quantum gas TATJANA GERICKE

Loss, Daniel

182

A Gas Chromatography Experiment for Proving the Application of Quantum Symmetry Restrictions in Homonuclear Diatomic Molecules.  

ERIC Educational Resources Information Center

Background information, procedures used, and typical results obtained are provided for an experiment in which gas chromatography is used to prove the application of quantum symmetry restrictions in homonuclear diatomic molecules. Comparisons between experimental results and theoretical computed values show good agreement, within one to two…

Dosiere, M.

1985-01-01

183

Exact results for a charged harmonically trapped quantum gas at arbitrary temperature and magnetic field strength  

Microsoft Academic Search

An analytical expression for the first-order density matrix of a charged, two-dimensional, harmonically confined quantum gas, in the presence of a constant magnetic field is derived. Our approach is nonpertabative, and is therefore exact for any temperature and magnetic field strength. We also present a useful factorization of the Bloch density matrix in the form of a simple product with

Patrick Shea; Brandon P. van Zyl

2006-01-01

184

Satyendranath Bose: Co-Founder of Quantum Statistics  

ERIC Educational Resources Information Center

Satyendranath Bose was first to prove Planck's Law by using ideal quantum gas. Einstein credited Bose for this first step in the development of quantum statistical mechanics. Bose did not realize the importance of his work, perhaps because of peculiar academic settings in India under British rule. (PS)

Blanpied, William A.

1972-01-01

185

Quantum FRW cosmological solutions in the presence of Chaplygin gas and perfect fluid  

E-print Network

We present a Friedmann-Robertson-Walker quantum cosmological model in the presence of Chaplygin gas and perfect fluid for early and late time epoches. In this work, we consider perfect fluid as an effective potential and apply Schutz's variational formalism to the Chaplygin gas which recovers the notion of time. These give rise to Schr\\"odinger-Wheeler-DeWitt equation for the scale factor. We use the eigenfunctions in order to construct wave packets and study the time dependent behavior of the expectation value of the scale factor using the many-worlds interpretation of quantum mechanics. We show that contrary to the classical case, the expectation value of the scale factor avoids singularity at quantum level. Moreover, this model predicts that the expansion of Universe is accelerating for the late times.

P. Pedram; S. Jalalzadeh

2007-11-13

186

Vortex-antivortex wavefunction of a degenerate quantum gas  

NASA Astrophysics Data System (ADS)

A mechanism of a pinning of the quantized matter wave vortices by optical vortices in a specially arranged optical dipole traps is discussed. The vortex-antivortex optical arrays of rectangular symmetry are shown to transfer angular orbital momentum and form the “antiferromagnet”-like matter waves. The separable Hamiltonian for matter waves in pancake trapping geometry is proposed and 3D-wavefunction is factorized in a product of wavefunctions of the 1D harmonic oscillator and 2D vortex-antivortex quantum state. The 2D wavefunction’s phase gradient field associated via Madelung transform with the field of classical velocities forms labyrinth-like structure. The macroscopic quantum state composed of periodically spaced counter-rotating BEC superfluid vortices has zero angular momentum and nonzero rotational energy.

Okulov, A. Yu.

2009-08-01

187

Observation of Fermi surface deformation in a dipolar quantum gas  

NASA Astrophysics Data System (ADS)

In the presence of isotropic interactions, the Fermi surface of an ultracold Fermi gas is spherical. Introducing anisotropic interactions can deform the Fermi surface, but the effect is subtle and challenging to observe experimentally. Here, we report on the observation of a Fermi surface deformation in a degenerate dipolar Fermi gas of erbium atoms. The deformation is caused by the interplay between strong magnetic dipole-dipole interaction and the Pauli exclusion principle. We demonstrate the many-body nature of the effect and its tunability with the Fermi energy. Our observation provides a basis for future studies on anisotropic many-body phenomena in normal and superfluid phases.

Aikawa, K.; Baier, S.; Frisch, A.; Mark, M.; Ravensbergen, C.; Ferlaino, F.

2014-09-01

188

Quantum criticality of one-dimensional multicomponent Fermi gas with strongly attractive interaction  

NASA Astrophysics Data System (ADS)

Quantum criticality of strongly attractive Fermi gas with SU(3) symmetry in one dimension is studied via the thermodynamic Bethe ansatz (TBA) equations. The phase transitions driven by the chemical potential ? , effective magnetic field H1, H2 (chemical potential biases) are analyzed at the quantum criticality. The phase diagram and critical fields are analytically determined by the TBA equations in the zero temperature limit. High accurate equations of state, scaling functions are also obtained analytically for the strong interacting gases. The dynamic exponent z=2 and correlation length exponent ? =1/2 read off the universal scaling form. It turns out that the quantum criticality of the three-component gases involves a sudden change of density of states of one cluster state, two or three cluster states. In general, this method can be adapted to deal with the quantum criticality of multicomponent Fermi gases with SU(N) symmetry.

He, Peng; Jiang, Yuzhu; Guan, Xiwen; He, Jinyu

2015-01-01

189

Ideals and Category Typicality  

ERIC Educational Resources Information Center

Barsalou (1985) argued that exemplars that serve category goals become more typical category members. Although this claim has received support, we investigated (a) whether categories have a single ideal, as negatively valenced categories (e.g., cigarette) often have conflicting goals, and (b) whether ideal items are in fact typical, as they often…

Kim, ShinWoo; Murphy, Gregory L.

2011-01-01

190

Test of the quantumness of atom-atom correlations in a bosonic gas  

E-print Network

It is shown how the quantumness of atom-atom correlations in a trapped bosonic gas can be made observable. Application of continuous feedback control of the center of mass of the atomic cloud is shown to generate oscillations of the spatial extension of the cloud, whose amplitude can be directly used as a characterization of atom-atom correlations. Feedback parameters can be chosen such that the violation of a Schwarz inequality for atom-atom correlations can be tested at noise levels much higher than the standard quantum limit.

D. Ivanov; S. Wallentowitz

2006-03-16

191

Hydrodynamic theory for quantum plasmonics: Linear-response dynamics of the inhomogeneous electron gas  

NASA Astrophysics Data System (ADS)

We investigate the hydrodynamic theory of metals, offering systematic studies of the linear-response dynamics for an inhomogeneous electron gas. We include the quantum functional terms of the Thomas-Fermi kinetic energy, the von Weizsäcker kinetic energy, and the exchange-correlation Coulomb energies under the local density approximation. The advantages, limitations, and possible improvements of the hydrodynamic theory are transparently demonstrated. The roles of various parameters in the theory are identified. We anticipate that the hydrodynamic theory can be applied to investigate the linear response of complex metallic nanostructures, including quantum effects, by adjusting theory parameters appropriately.

Yan, Wei

2015-03-01

192

Quantum State-Resolved Reactive and Inelastic Scattering at Gas-Liquid and Gas-Solid Interfaces  

NASA Astrophysics Data System (ADS)

Quantum state-resolved reactive and inelastic scattering at gas-liquid and gas-solid interfaces has become a research field of considerable interest in recent years. The collision and reaction dynamics of internally cold gas beams from liquid or solid surfaces is governed by two main processes, impulsive scattering (IS), where the incident particles scatter in a few-collisions environment from the surface, and trapping-desorption (TD), where full equilibration to the surface temperature (T{TD}? T{s}) occurs prior to the particles' return to the gas phase. Impulsive scattering events, on the other hand, result in significant rotational, and to a lesser extent vibrational, excitation of the scattered molecules, which can be well-described by a Boltzmann-distribution at a temperature (T{IS}>>T{s}). The quantum-state resolved detection used here allows the disentanglement of the rotational, vibrational, and translational degrees of freedom of the scattered molecules. The two examples discussed are (i) reactive scattering of monoatomic fluorine from room-temperature ionic liquids (RTILs) and (ii) inelastic scattering of benzene from a heated (˜500 K) gold surface. In the former experiment, rovibrational states of the nascent HF beam are detected using direct infrared absorption spectroscopy, and in the latter, a resonace-enhanced multi-photon-ionization (REMPI) scheme is employed in combination with a velocity-map imaging (VMI) device, which allows the detection of different vibrational states of benzene excited during the scattering process. M. E. Saecker, S. T. Govoni, D. V. Kowalski, M. E. King and G. M. Nathanson Science 252, 1421, 1991. A. M. Zolot, W. W. Harper, B. G. Perkins, P. J. Dagdigian and D. J. Nesbitt J. Chem. Phys 125, 021101, 2006. J. R. Roscioli and D. J. Nesbitt Faraday Disc. 150, 471, 2011.

Grütter, Monika; Nelson, Daniel J.; Nesbitt, David J.

2012-06-01

193

Spontaneous Pattern Formation in an Antiferromagnetic Quantum Gas  

SciTech Connect

In this Letter we report on the spontaneous formation of surprisingly regular periodic magnetic patterns in an antiferromagnetic Bose-Einstein condensate (BEC). The structures evolve within a quasi-one-dimensional BEC of {sup 87}Rb atoms on length scales of a millimeter with typical periodicities of 20...30 {mu}m, given by the spin healing length. We observe two sets of characteristic patterns which can be controlled by an external magnetic field. We identify these patterns as linearly unstable modes within a mean-field approach and calculate their mode structure as well as time and energy scales, which we find to be in good agreement with observations. These investigations open new prospects for controlled studies of symmetry breaking and complex quantum magnetism in bulk BEC.

Kronjaeger, Jochen; Bongs, Kai [MUARC, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Institut fuer Laser-Physik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Becker, Christoph; Soltan-Panahi, Parvis; Sengstock, Klaus [Institut fuer Laser-Physik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

2010-08-27

194

Hollow waveguide quantum cascade laser spectrometer as an online microliter sensor for gas chromatography.  

PubMed

An optical absorption sensor for gas chromatography (GC) is presented. It consists of a quantum cascade laser along with a long piece of Hollow Waveguide for Infrared (HWIR) transmission inserted into the GC line. It measures the infrared absorption in each individual gas peak after separation by the GC column, and maintains the shapes of gas peaks after the HWIR sensor, making the gas samples further available for other sensors. By adding an inline combustion module before the HWIR sensor, the concentrations of many carbon containing compounds can be acquired by measuring CO2 absorption in their peaks. The HWIR sensor detects isotopologues of CO2 separately, and therefore can be used to measure carbon isotope ratios of heavy compounds. Application of the HWIR sensor to the detection of 13CO2 and CDH3 is described. PMID:18343387

Wu, Sheng; Deev, Andrei; Haught, Mark; Tang, Yongchun

2008-04-25

195

OBTAINING LAWS OF THERMODYNAMICS FOR IDEAL GASES USING ELASTIC COLLISIONS  

E-print Network

of gas B in the right half of the container. The molecules obey Newton's laws of motion, with elastic's laws of motion are all that are needed to predict the ideal gas laws, and that the collisionsOBTAINING LAWS OF THERMODYNAMICS FOR IDEAL GASES USING ELASTIC COLLISIONS STEPHEN MONTGOMERY

Montgomery-Smith, Stephen

196

Carbon Dioxide Gas Sensing Application of GRAPHENE/Y2O3 Quantum Dots Composite  

NASA Astrophysics Data System (ADS)

Graphene/Y2O3 quantum dots (QDs) composite was investigated towards the carbon dioxide (CO2) gas at room temperature. Graphene synthesized by electrochemical exfoliation of graphite. The composite prepared by mixing 20-wt% graphene into the 1 g Y2O3 in organic medium (acetone). The chemiresistor of composite prepared by screen-printing on glass substrate. The optimum value of sensing response (1.08) was showed by 20-wt% graphene/Y2O3 QDs composite. The excellent stability with optimum sensing response evidenced for the composite. The gas sensing mechanism discussed on the basis of electron transfer reaction.

Nemade, K. R.; Waghuley, S. A.

197

Probing the Quantum State of a 1D Bose Gas Using Off-Resonant Light Scattering  

SciTech Connect

We present a theoretical treatment of coherent light scattering from an interacting 1D Bose gas at finite temperatures. We show how this can provide a nondestructive measurement of the atomic system states. The equilibrium states are determined by the temperature and interaction strength, and are characterized by the spatial density-density correlation function. We show how this correlation function is encoded in the angular distribution of the fluctuations of the scattered light intensity, thus providing a sensitive, quantitative probe of the density-density correlation function and therefore the quantum state of the gas.

Sykes, A. G. [Jack Dodd Centre for Quantum Technology, Department of Physics, University of Otago, PO Box 56, Dunedin (New Zealand); Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Ballagh, R. J. [Jack Dodd Centre for Quantum Technology, Department of Physics, University of Otago, PO Box 56, Dunedin (New Zealand)

2011-12-30

198

Quantum-mechanical third virial coefficient of a hard-sphere gas at high temperature  

Microsoft Academic Search

The third virial coefficient B3 of a gas of hard spheres, of diameter a and mass m, has been expanded in powers of lambdaa, where lambda is the thermal wavelength (2pik T)12 (ℏ=m=1). B3 can be expressed in terms of integrals on all configurations of the quantum-statistical-mechanical probability density of the configurations of a three-sphere system. This probability density is

B. Jancovici; S. P. Merkuriev

1975-01-01

199

Quantum-Mechanical Equation of State of a Hard-Sphere Gas at High Temperature. II  

Microsoft Academic Search

As the continuation of a preceding paper, an expansion for the quantum-mechanical free energy F of a hard-sphere gas at high temperature is extended up to the second order in the thermal wavelength lambda=(2piℏ2mkT)12. To reach this order, one must study the three-body problem in a lowest-order approximation, in which adjacent sphere surfaces can be regarded as parallel planes. Coefficients

B. Jancovici

1969-01-01

200

Thermodynamic properties of a harmonically trapped, two-dimensional charged quantum gas in a magnetic field  

Microsoft Academic Search

We present exact analytical results for the thermodyanmic properties of a two-dimensional (2D), harmonically trapped charged quantum gas in a magnetic field. While our results are applicable to both Fermi and Bose gases, we focus our attention on trapped fermions owing to their relevant application in the density-functional theory of inhomogeneous Fermi systems. In particular, we test the Thomas-Fermi (or

Patrick Shea; Brandon P. van Zyl

2008-01-01

201

Single-site resolved studies of a bilayer quantum degenerate gas  

NASA Astrophysics Data System (ADS)

Ultracold atoms in optical lattices are a versatile platform for quantum many-body simulation with the promise of insights into quantum magnetism, superconductivity, and superfluidity. In recent years, quantum gas microscopes with single-site resolution have opened the door to local observation and manipulation of strongly correlated two-dimensional quantum gases. Here we present techniques for extending study to two tunnel-coupled planes. Using an axial superlattice we prepare a bilayer system, with full control of the inter-plane tunnel coupling and detuning. We observe coherent inter-plane population transfer with single-site resolution in both planes. A collisional energy blockade in the bilayer system allows us to go beyond parity imaging and unambiguously identify site occupations from zero to three atoms. We have obtained site-resolved images of the ``wedding-cake'' Mott insulator structure and antiferromagnetic ordering in a quantum Ising model. Further applications include spin-dependent readout and in situ phase imaging.

Ma, Ruichao; Preiss, Philipp; Tai, Ming; Bakr, Waseem; Simon, Jonathan; Greiner, Markus

2012-06-01

202

Tunnel-field-effect-transistor based gas-sensor: Introducing gas detection with a quantum-mechanical transducer  

NASA Astrophysics Data System (ADS)

A gas-sensor based on tunnel-field-effect-transistor (TFET) is proposed that leverages the unique current injection mechanism in the form of quantum-mechanical band-to-band tunneling to achieve substantially improved performance compared to conventional metal-oxide-semiconductor field-effect-transistors (MOSFETs) for detection of gas species under ambient conditions. While nonlocal phonon-assisted tunneling model is used for detailed device simulations, in order to provide better physical insights, analytical formula for sensitivity is derived for both metal as well as organic conducting polymer based sensing elements. Analytical derivations are also presented for capturing the effects of temperature on sensor performance. Combining the developed analytical and numerical models, intricate properties of the sensor such as gate bias dependence of sensitivity, relationship between the required work-function modulation and subthreshold swing, counter-intuitive increase in threshold voltage for MOSFETs and reduction in tunneling probability for TFETs with temperature are explained. It is shown that TFET gas-sensors can not only lead to more than 10 000× increase in sensitivity but also provide design flexibility and immunity against screening of work-function modulation through non-specific gases as well as ensure stable operation under temperature variations.

Sarkar, Deblina; Gossner, Harald; Hansch, Walter; Banerjee, Kaustav

2013-01-01

203

Suppression of quantum collapse in an anisotropic gas of dipolar bosons  

SciTech Connect

In recent work [Sakaguchi and Malomed, Phys. Rev. A 83, 013607 (2011)], a solution to the problem of the quantum collapse (fall onto the center) in the three-dimensional space with the attractive potential -(U{sub 0}/2)r{sup -2} was proposed, based on the replacement of the linear Schroedinger equation by the Gross-Pitaevskii (GP) equation with the repulsive cubic term. The model applies to a quantum gas of molecules carrying permanent electric dipole moments, with the attraction center representing a fixed electric charge. It was demonstrated that the repulsive nonlinearity suppresses the quantum collapse and creates the corresponding spherically symmetric ground state (GS), which was missing in the case of the linear Schroedinger equation. Here, we aim to extend the analysis to the cylindrical geometry and to eigenstates carrying angular momentum. The cylindrical anisotropy is imposed by a uniform dc field, which fixes the orientation of the dipole moments, thus altering the potential of the attraction to the center. First, we analyze the modification of the condition for the onset of the quantum collapse in the framework of the linear Schroedinger equation with the cylindrically symmetric potential for the states with azimuthal quantum numbers m=0 (the GS) and m=1, 2. The corresponding critical values of the strength of the attractive potential (U{sub 0}){sub cr}(m) are found. Next, a numerical solution of the nonlinear GP equation is developed, which demonstrates the replacement of the quantum collapse by the originally missing eigenstates with m=0,1,2. Their dynamical stability is verified by means of numerical simulations of the perturbed evolution. For m=0, the Thomas-Fermi approximation is presented too, in an analytical form. Crucially important for the solution is the proper choice of the boundary conditions at r{yields}0.

Sakaguchi, Hidetsugu [Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Malomed, Boris A. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv IL-69978 (Israel); ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, ES-08860 Castelldefels (Barcelona) (Spain)

2011-09-15

204

Trace-gas sensing using the compliance voltage of an external cavity quantum cascade laser  

SciTech Connect

Quantum cascade lasers (QCLs) are increasingly being used to detect, identify, and measure levels of trace gases in the air. External cavity QCLs (ECQCLs) provide a broadly-tunable infrared source to measure absorption spectra of chemicals and provide high detection sensitivity and identification confidence. Applications include detecting chemical warfare agents and toxic industrial chemicals, monitoring building air quality, measuring greenhouse gases for atmospheric research, monitoring and controlling industrial processes, analyzing chemicals in exhaled breath for medical diagnostics, and many more. Compact, portable trace gas sensors enable in-field operation in a wide range of platforms, including handheld units for use by first responders, fixed installations for monitoring air quality, and lightweight sensors for deployment in unmanned aerial vehicles (UAVs). We present experimental demonstration of a new chemical sensing technique based on intracavity absorption in an external cavity quantum cascade laser (ECQCL). This new technique eliminates the need for an infrared photodetector and gas cell by detecting the intracavity absorption spectrum in the compliance voltage of the laser device itself. To demonstrate and characterize the technique, we measure infrared absorption spectra of chemicals including water vapor and Freon-134a. Sub-ppm detection limits in one second are achieved, with the potential for increased sensitivity after further optimization. The technique enables development of handheld, high-sensitivity, and high-accuracy trace gas sensors for in-field use.

Phillips, Mark C.; Taubman, Matthew S.

2013-06-04

205

The ideal conductor limit  

Microsoft Academic Search

This paper compares two methods of statistical mechanics used to study a classical Coulomb system S near an ideal conductor C. The first method consists in neglecting the thermal fluctuations in the conductor C and constrains the electric potential to be constant on it. In the second method the conductor C is considered as a conducting Coulomb system the charge

B. Jancovici; G. Téllez

1996-01-01

206

Idealism and Yogacara Buddhism  

Microsoft Academic Search

Over the last several years, there has been a growing controversy about whether Yogacara Buddhism can be said to be idealist in some sense, as used to be commonly thought by earlier scholars. In this paper, I first clarify the different senses of idealism that might be pertinent to the debate. I then focus on some of the works of

Saam Trivedi

2005-01-01

207

NMR dynamics of quantum discord for spin-carrying gas molecules in a closed nanopore  

E-print Network

A local orthogonal transformation that transforms any centrosymmetric (CS) matrix of fourth order to the X form is found. A picewise-analytic-numerical formula Q=min{Q_\\pi/2,Q_\\theta,Q_0}, where Q_\\pi/2 and Q_0 are analytical expressions and the branch Q_{\\theta} is found by numerical searching the optimal measurement angle \\theta\\in(0,\\pi/2), is proposed to calculate the quantum discord Q of general X state. The developed approaches are applied to a quantitative description of recently predicted flickerings (periodic birth and death) of the quantum-information pair correlation between nuclear 1/2 spin of atoms or molecules of a gas (for examples Xe^129) in a finite asymmetric volume in the presence of a strong magnetic field.

M. A. Yurischev

2015-03-11

208

Quantum mechanical limitations to spin diffusion in the unitary Fermi gas.  

PubMed

We compute spin transport in the unitary Fermi gas using the strong-coupling Luttinger-Ward theory. In the quantum degenerate regime the spin diffusivity attains a minimum value of D(s) Symbol: see text] 1.3 ?/m approaching the quantum limit of diffusion for a particle of mass m. Conversely, the spin drag rate reaches a maximum value of ?(sd) [Symbol: see text] 1.2k(B)T(F)/? in terms of the Fermi temperature T(F). The frequency-dependent spin conductivity ?(s)(?) exhibits a broad Drude peak, with spectral weight transferred to a universal high-frequency tail ?(s) (? ? ?) = ?(1/2)C/3?(m?)(3/2) proportional to the Tan contact density C. For the spin susceptibility ?(s)(T) we find no downturn in the normal phase. PMID:23215396

Enss, Tilman; Haussmann, Rudolf

2012-11-01

209

Cavity quantum electrodynamics with many-body states of a two-dimensional electron gas.  

PubMed

Light-matter interaction has played a central role in understanding as well as engineering new states of matter. Reversible coupling of excitons and photons enabled groundbreaking results in condensation and superfluidity of nonequilibrium quasiparticles with a photonic component. We investigated such cavity-polaritons in the presence of a high-mobility two-dimensional electron gas, exhibiting strongly correlated phases. When the cavity was on resonance with the Fermi level, we observed previously unknown many-body physics associated with a dynamical hole-scattering potential. In finite magnetic fields, polaritons show distinct signatures of integer and fractional quantum Hall ground states. Our results lay the groundwork for probing nonequilibrium dynamics of quantum Hall states and exploiting the electron density dependence of polariton splitting so as to obtain ultrastrong optical nonlinearities. PMID:25278508

Smolka, Stephan; Wuester, Wolf; Haupt, Florian; Faelt, Stefan; Wegscheider, Werner; Imamoglu, Ataç

2014-10-17

210

NMR dynamics of quantum discord for spin-carrying gas molecules in a closed nanopore  

NASA Astrophysics Data System (ADS)

A local orthogonal transformation that transforms any centrosymmetric density matrix of a two-qubit system to the X form has been found. A piecewise-analytic-numerical formula Q = min{ Q ?/2, Q ?, Q 0}, where Q ?/2 and Q 0 are analytical expressions and the branch Q 0 ? can be obtained only by numerically searching for the optimal measurement angle ? ? (0, ?/2), is proposed to calculate the quantum discord Q of a general X state. The developed approaches have been applied for a quantitative description of the recently predicted flickering (periodic disappearance and reappearance) of the quantum-information pair correlation between nuclear 1/2 spins of atoms or molecules of a gas (for example, 129Xe) in a bounded volume in the presence of a strong magnetic field.

Yurishchev, M. A.

2014-11-01

211

NMR dynamics of quantum discord for spin-carrying gas molecules in a closed nanopore  

SciTech Connect

A local orthogonal transformation that transforms any centrosymmetric density matrix of a two-qubit system to the X form has been found. A piecewise-analytic-numerical formula Q = min(Q{sub ?/2}, Q{sub ?}, Q{sub 0}), where Q{sub ?/2} and Q{sub 0} are analytical expressions and the branch Q{sub 0?} can be obtained only by numerically searching for the optimal measurement angle ? ? (0, ?/2), is proposed to calculate the quantum discord Q of a general X state. The developed approaches have been applied for a quantitative description of the recently predicted flickering (periodic disappearance and reappearance) of the quantum-information pair correlation between nuclear 1/2 spins of atoms or molecules of a gas (for example, {sup 129}Xe) in a bounded volume in the presence of a strong magnetic field.

Yurishchev, M. A., E-mail: yur@itp.ac.ru [Russian Academy of Sciences, Institute of Problems of Chemical Physics (Russian Federation)

2014-11-15

212

Generic and Cogeneric Monomial Ideals  

Microsoft Academic Search

Monomial ideals which are generic with respect to either their genera- tors or irreducible components have minimal free resolutions derived from simplicial complexes. For a generic monomial ideal, the associated primes satisfy a saturated chain condition, and the Cohen-Macaulay property implies shellability for both the Scarf complex and the Stanley-Reisner complex. Reverse lexicographic initial ideals of generic lattice ideals are

Ezra Miller; Bernd Sturmfels; Kohji Yanagawa

2000-01-01

213

Generic and Cogeneric Monomial Ideals  

Microsoft Academic Search

Monomial ideals which are generic with respect to either their generators or irreducible components have minimal free resolutions derived from simplicial complexes. For a generic monomial ideal, the associated primes satisfy a saturated chain condition, and the Cohen-Macaulay property implies shellability for both the Scarf complex and the Stanley-Reisner complex. Reverse lexicographic initial ideals of generic lattice ideals are generic.

Ezra Miller; Bernd Sturmfels; Kohji Yanagawa

1998-01-01

214

Weakly Relativistic Quantum Effects in a Two-Dimensional Electron Gas: Dispersion of Langmuir Waves  

NASA Astrophysics Data System (ADS)

A weakly-relativistic quantum-hydrodynamic model for charged spinless particles applied to low-dimensional systems is described in detail. The equations are constructed in the self-consistent field approximation. The Darwin term, the current-current interaction, and the weakly relativistic correction to the kinetic energy, all described by the Breit Hamiltonian, are considered together with the Coulomb interaction. The contributions of the described effects and also of relativistic-temperature effects to the dispersion of the Langmuir waves in a two-dimensional electron gas are calculated. A comparison with the corresponding formula for a three-dimensional system of particles is presented.

Andreev, P. A.; Ivanov, A. Yu.

2015-01-01

215

Quantum-Mechanical Equation of State of a Hard-Sphere Gas at High Temperature  

Microsoft Academic Search

The quantum-mechanical free energy F of a hard-sphere gas at high temperature is a series in powers of the thermal wavelength lambda=(2piℏ2mkT)12 the coefficients of this series can be expressed in terms of the classical correlation functions. The result to first order is FNk T=F(0)Nk T+pi2 g2(a)a2rholambda, where F( 0) is the classical free energy, N the total number of

B. Jancovici

1969-01-01

216

Quantum and Thermal Effects of Dark Solitons in a One-Dimensional Bose Gas  

SciTech Connect

We numerically study the imprinting and dynamics of dark solitons in a bosonic atomic gas in a tightly confined one-dimensional harmonic trap both with and without an optical lattice. Quantum and thermal fluctuations are synthesized within the truncated Wigner approximation in the quasicondensate description. We track the soliton coordinates and calculate position and velocity uncertainties. We find that the phase fluctuations lower the classically predicted soliton speed and seed instabilities. Individual runs show interactions of solitons with sound waves, splitting, and disappearing solitons.

Martin, A. D.; Ruostekoski, J. [School of Mathematics, University of Southampton, Southampton SO17 1BJ (United Kingdom)

2010-05-14

217

Quantum Anomaly, Universal Relations, and Breathing Mode of a Two-Dimensional Fermi Gas  

NASA Astrophysics Data System (ADS)

In this Letter, we show that the classical SO(2,1) symmetry of a harmonically trapped Fermi gas in two dimensions is broken by quantum effects. The anomalous correction to the symmetry algebra is given by a two-body operator that is well known as the contact. Taking into account this modification, we are able to derive the virial theorem for the system and a universal relation for the pressure of a homogeneous gas. The existence of an undamped breathing mode is associated with the classical symmetry. We provide an estimate for the anomalous frequency shift of this oscillation at zero temperature and compare the result with a recent experiment by [E. Vogt , Phys. Rev. Lett.PRLTAO0031-9007 108, 070404 (2012)10.1103/PhysRevLett.108.070404]. Discrepancies are attributed to finite temperature effects.

Hofmann, Johannes

2012-05-01

218

Quantum anomaly, universal relations, and breathing mode of a two-dimensional Fermi gas.  

PubMed

In this Letter, we show that the classical SO(2,1) symmetry of a harmonically trapped Fermi gas in two dimensions is broken by quantum effects. The anomalous correction to the symmetry algebra is given by a two-body operator that is well known as the contact. Taking into account this modification, we are able to derive the virial theorem for the system and a universal relation for the pressure of a homogeneous gas. The existence of an undamped breathing mode is associated with the classical symmetry. We provide an estimate for the anomalous frequency shift of this oscillation at zero temperature and compare the result with a recent experiment by [E. Vogt et al., Phys. Rev. Lett. 108, 070404 (2012)]. Discrepancies are attributed to finite temperature effects. PMID:22681087

Hofmann, Johannes

2012-05-01

219

Ideal Integrating Bolometer  

NASA Technical Reports Server (NTRS)

We describe a new "ideal integrator" bolometer as a prototype for a new generation of sensitive, flexible far-IR detectors suitable for use in large arrays. The combination of a non-dissipative sensor coupled with a fast heat switch provides breakthrough capabilities in both sensitivity and operation. The bolometer temperature varies linearly with the integrated infrared power incident on the detector, and may be sampled intermittently without loss of information between samples. The sample speed and consequent dynamic range depend only on the heat switch reset cycle and can be selected in software. Between samples, the device acts as an ideal integrator with noise significantly lower than resistive bolometers. Since there is no loss of information between samples, the device is well-suited for large arrays. A single SQUID readout could process an entire column of detectors, greatly reducing the complexity, power requirements, and cost of readout electronics for large pixel arrays.

Kogut, A.; DiPirro, M.; Moseley, S. H.

2004-01-01

220

Delivering ideal employee experiences.  

PubMed

Employee-centric strategies have moved from employee satisfaction and brand awareness to employee "affinity" or "attachment." In today's marketplace, occupational health nurses understand that differentiation (i.e., the perception of uniqueness) is the direct result of superior employee interactions, which lead to better employee care, enduring employee relationships, loyal employees, and satisfied employers. What drives employees to occupational health nurse attachment? The answer is a passion for rising above the competition to create ideal employee experiences. PMID:19492760

Weiss, Marjorie D; Tyink, Steve; Kubiak, Curt

2009-05-01

221

FK-DLR properties of a quantum multi-type Bose-gas with a repulsive interaction  

NASA Astrophysics Data System (ADS)

The paper extends earlier results from Suhov and Kelbert ["FK-DLR states of a quantum Bose-gas with a hardcore interaction," arXiv:1304.0782] and Suhov et al. ["Shift-invariance for FK-DLR states of a 2D quantum Bose-gas," arXiv:1304.4177] about infinite-volume quantum bosonic states (FK-DLR states) to the case of multi-type particles with non-negative interactions. (An example is a quantum Widom-Rowlinson model.) Following the strategy from Suhov and Kelbert and Suhov et al., we establish that, for the values of fugacity z ? (0, 1) and inverse temperature ? > 0, finite-volume Gibbs states form a compact family in the thermodynamic limit. Next, in dimension two we show that any limit-point state (an FK-DLR state in the terminology adopted in Suhov and Kelbert and Suhov et al.) is translation-invariant.

Suhov, Y.; Stuhl, I.

2014-08-01

222

Life cycle of superfluid vortices and quantum turbulence in the unitary Fermi gas  

NASA Astrophysics Data System (ADS)

The unitary Fermi gas (UFG) offers a unique opportunity to study quantum turbulence both experimentally and theoretically in a strongly interacting fermionic superfluid with the highest vortex line density of any known superfluid. It yields to accurate and controlled experiments and admits the only dynamical microscopic description via time-dependent density-functional theory, apart from dilute bosonic gases, of the crossing and reconnection of superfluid vortex lines conjectured by Feynman [R. P. Feynman, Prog. Low Temp. Phys. 1, 17 (1955), 10.1016/S0079-6417(08)60077-3] to be at the origin of quantum turbulence in superfluids at zero temperature. We demonstrate how various vortex configurations can be generated by using well-established experimental techniques: laser stirring and phase imprinting. New imaging techniques demonstrated by Ku et al. [M. J. H. Ku et al., Phys. Rev. Lett. 113, 065301 (2014), 10.1103/PhysRevLett.113.065301] should be able to directly visualize these crossings and reconnections in greater detail than performed so far in liquid helium. We demonstrate the critical role played by the geometry of the trap in the formation and dynamics of a vortex in the UFG and how laser stirring and phase imprint can be used to create vortex tangles with clear signatures of the onset of quantum turbulence.

Wlaz?owski, Gabriel; Bulgac, Aurel; Forbes, Michael McNeil; Roche, Kenneth J.

2015-03-01

223

ChemTeacher Resource: Ideal Gases with Movable Partition  

NSDL National Science Digital Library

An applet shows two containers of an ideal gas separated by a movable partition. By adjusting temperature and/or number of particles, the user causes the partition to move and can watch the resulting changes.

Wolfgang Christian

2011-01-01

224

Captulo 14 Gas ideal de bosones.  

E-print Network

una integral: # # F (# # ) = # # 0 d#g (1) (#)F (#) con la densidad de estados monoparticular ya densidad de estados hace que el peso del estado fundamental en la integral sea 0 1/2 = 0. Por tanto, lo que

Colet, Pere

225

Theta Bodies for Polynomial Ideals  

E-print Network

Inspired by a question of Lovász, we introduce a hierarchy of nested semidefinite relaxations of the convex hull of real solutions to an arbitrary polynomial ideal called theta bodies of the ideal. These relaxations ...

Parrilo, Pablo A.

226

Traces, ideals, and arithmetic means  

Microsoft Academic Search

This article grew out of recent work of Dykema, Figiel, Weiss, and Wodzicki (Commutator structure of operator ideals) which inter alia characterizes commutator ideals in terms of arithmetic means. In this paper we study ideals that are arithmetically mean (am) stable, am-closed, am-open, soft-edged and soft-complemented. We show that many of the ideals in the literature possess such properties. We

Victor Kaftal; Gary Weiss

2002-01-01

227

Common physical mechanism for integer and fractional quantum Hall effects  

E-print Network

Integer and fractional quantum Hall effects were studied with different physics models and explained by different physical mechanisms. In this paper, the common physical mechanism for integer and fractional quantum Hall effects is studied, where a new unified formulation of integer and fractional quantum Hall effect is presented. Firstly, we introduce a 2-dimensional ideal electron gas model in the presence of strong magnetic field with symmetry gauge, and the transverse electric filed $\\varepsilon_2$ is also introduced to balance Lorentz force. Secondly, the Pauli equation is solved where the wave function and energy levels is given explicitly. Thirdly, after the calculation of the degeneracy density for 2-dimensional ideal electron gas system, the Hall resistance of the system is obtained, where the quantum Hall number $\

Jianhua wang; Kang Li; Shuming Long; Yi Yuan

2012-01-24

228

Eulerian and Newtonian dynamics of quantum particles  

NASA Astrophysics Data System (ADS)

We derive the classical equations of hydrodynamics (the Euler and continuity equations), from which the Schrödinger equation follows as a limit case. It is shown that the statistical ensemble corresponding to a quantum system and described by the Schrödinger equation can be considered an inviscid gas that obeys the ideal gas law with a quickly oscillating sign-alternating temperature. This statistical ensemble performs the complex movements consisting of smooth average movement and fast oscillations. It is shown that the average movements of the statistical ensemble are described by the Schrödinger equation. A model of quantum motion within the limits of classical mechanics that corresponds to the hydrodynamic system considered is suggested.

Rashkovskiy, S. A.

2013-06-01

229

Dual quantum cascade laser trace gas instrument with astigmatic Herriott cell at high pass number.  

PubMed

We have developed and demonstrated a high-sensitivity trace gas instrument employing two mid-infrared quantum cascade lasers and an astigmatic Herriott sample cell with up to a 240?m path length. Several aspects of astigmatic Herriott cell optics have been addressed to enable operation at a high pass number (up to 554), including aberrations and pattern selection to minimize interference fringes. The new instrument design, based on the 200?m cell, can measure various atmospheric trace gases, depending on the installed lasers, with multiple trace gases measured simultaneously. Demonstrated concentration noise levels (1?s average) are 40?parts per trillion [(ppt) 10(-12)] for formaldehyde, 10?ppt for carbonyl sulfide, 110?ppt for hydrogen peroxide (H2O2), and 180?ppt for nitrous acid (HONO). High-precision measurements of nitrous oxide and methane have been recorded at the same time as high-sensitivity measurements of HONO and H2O2. PMID:21283223

McManus, J Barry; Zahniser, Mark S; Nelson, David D

2011-02-01

230

Finite-Temperature Pairing Gap of a Unitary Fermi Gas by Quantum Monte Carlo Calculations  

SciTech Connect

We calculate the one-body temperature Green's (Matsubara) function of the unitary Fermi gas via quantum Monte Carlo, and extract the spectral weight function A(p,omega) using the methods of maximum entropy and singular value decomposition. From A(p,omega) we determine the quasiparticle spectrum, which can be accurately parametrized by three functions of temperature: an effective mass m*, a mean-field potential U, and a gap DELTA. Below the critical temperature T{sub c}=0.15epsilon{sub F} the results for m*, U, and DELTA can be accurately reproduced using an independent quasiparticle model. We find evidence of a pseudogap in the fermionic excitation spectrum for temperatures up to T*{approx_equal}0.20{epsilon}{sub F}>T{sub c}.

Magierski, Piotr; Wlazlowski, Gabriel [Faculty of Physics, Warsaw University of Technology, ulica Koszykowa 75, 00-662 Warsaw (Poland); Bulgac, Aurel; Drut, Joaquin E. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)

2009-11-20

231

The influence of molecular complexity on expanding flows of ideal and dense gases  

Microsoft Academic Search

This paper presents an investigation about the effect of the complexity of a fluid molecule on the fluid dynamic quantities sound speed, velocity, and Mach number in isentropic expansions. Ideal-gas and dense-gas expansions are analyzed, using the polytropic ideal gas and Van der Waals thermodynamic models to compute the properties of the fluid. In these equations, the number of active

J. Harinck; A. Guardone; P. Colonna

2009-01-01

232

Fermi-edge superfluorescence from a quantum-degenerate electron-hole gas  

PubMed Central

Nonequilibrium can be a source of order. This rather counterintuitive statement has been proven to be true through a variety of fluctuation-driven, self-organization behaviors exhibited by out-of-equilibrium, many-body systems in nature (physical, chemical, and biological), resulting in the spontaneous appearance of macroscopic coherence. Here, we report on the observation of spontaneous bursts of coherent radiation from a quantum-degenerate gas of nonequilibrium electron-hole pairs in semiconductor quantum wells. Unlike typical spontaneous emission from semiconductors, which occurs at the band edge, the observed emission occurs at the quasi-Fermi edge of the carrier distribution. As the carriers are consumed by recombination, the quasi-Fermi energy goes down toward the band edge, and we observe a continuously red-shifting streak. We interpret this emission as cooperative spontaneous recombination of electron-hole pairs, or superfluorescence (SF), which is enhanced by Coulomb interactions near the Fermi edge. This novel many-body enhancement allows the magnitude of the spontaneously developed macroscopic polarization to exceed the maximum value for ordinary SF, making electron-hole SF even more “super” than atomic SF. PMID:24257510

Kim, Ji-Hee; II, G. Timothy Noe; McGill, Stephen A.; Wang, Yongrui; Wójcik, Aleksander K.; Belyanin, Alexey A.; Kono, Junichiro

2013-01-01

233

Three-Level Maser Action in Gas I. Theory of Multiple Quantum Transition and Doppler Effect in Three-Level Gas Maser  

Microsoft Academic Search

The multiple quantum process in the off-resonant condition of the three-level gas maser is discussed. The intensity of the emission produced by this process is calculated by a perturbation theory and also by a more general treatment which is the application of Javan's theory to the off-resonant case. Some graphical representations of the signal line under off-resonant pumping are given

Tatsuo Yajima

1961-01-01

234

Ideal thermodynamic processes of oscillatory-flow regenerative engines will go to ideal stirling cycle?  

NASA Astrophysics Data System (ADS)

This paper analyzes the thermodynamic cycle of oscillating-flow regenerative machines. Unlike the classical analysis of thermodynamic textbooks, the assumptions for pistons' movement limitations are not needed and only ideal flowing and heat transfer should be maintained in our present analysis. Under such simple assumptions, the meso-scale thermodynamic cycles of each gas parcel in typical locations of a regenerator are analyzed. It is observed that the gas parcels in the regenerator undergo Lorentz cycle in different temperature levels, whereas the locus of all gas parcels inside the regenerator is the Ericson-like thermodynamic cycle. Based on this new finding, the author argued that ideal oscillating-flow machines without heat transfer and flowing losses is not the Stirling cycle. However, this new thermodynamic cycle can still achieve the same efficiency of the Carnot heat engine and can be considered a new reversible thermodynamic cycle under two constant-temperature heat sinks.

Luo, Ercang

2012-06-01

235

Quantum state-resolved gas/surface reaction dynamics probed by reflection absorption infrared spectroscopy  

SciTech Connect

We report the design and characterization of a new molecular-beam/surface-science apparatus for quantum state-resolved studies of gas/surface reaction dynamics combining optical state-specific reactant preparation in a molecular beam by rapid adiabatic passage with detection of surface-bound reaction products by reflection absorption infrared spectroscopy (RAIRS). RAIRS is a non-invasive infrared spectroscopic detection technique that enables online monitoring of the buildup of reaction products on the target surface during reactant deposition by a molecular beam. The product uptake rate obtained by calibrated RAIRS detection yields the coverage dependent state-resolved reaction probability S({theta}). Furthermore, the infrared absorption spectra of the adsorbed products obtained by the RAIRS technique provide structural information, which help to identify nascent reaction products, investigate reaction pathways, and determine branching ratios for different pathways of a chemisorption reaction. Measurements of the dissociative chemisorption of methane on Pt(111) with this new apparatus are presented to illustrate the utility of RAIRS detection for highly detailed studies of chemical reactions at the gas/surface interface.

Chen Li [Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Goettingen (Germany); Ueta, Hirokazu; Beck, Rainer D. [Laboratoire de Chimie Physique Moleculaire, Ecole Polytechnique Federale de Lausanne (Switzerland); Bisson, Regis [Aix-Marseille Universite, PIIM, CNRS, UMR 7345, 13397 Marseille (France)

2013-05-15

236

Uncountably Generated Ideals of Functions  

ERIC Educational Resources Information Center

Maximal ideals in the ring of continuous functions on the closed interval [0, 1] are not finitely generated. This is well-known. What is not as well-known, but perhaps should be, is the fact that these ideals are not countably generated although the proof is not harder! We prove this here and use the result to produce some non-prime ideals in the…

Sury, B.

2011-01-01

237

OBTAINING LAWS OF THERMODYNAMICS FOR IDEAL GASES USING ELASTIC COLLISIONS  

E-print Network

N molecules of gas B in the right half of the container. The molecules obey Newton's laws of motion that Newton's laws of motion are all that are needed to predict the ideal gas laws, and that the collisions Newtonian. For example, the motion is reversible, thus demonstrating that the second law of thermodynamics

Montgomery-Smith, Stephen

238

Continuum damping of ideal toroidal Alfven eigenmodes  

SciTech Connect

A perturbation theory based on the two dimensional (2D) ballooning transform is systematically developed for ideal toroidal Alfven eigenmodes (TAEs). A formula, similar to the Fermi golden rule for decaying systems in quantum mechanics, is derived for the continuum damping rate of the TAE; the decay (damping) rate is expressed explicitly in terms of the coupling of the TAE to the continuum spectrum. Numerical results are compared with previous calculations. It is found that in some narrow intervals of the parameter m{cflx {epsilon}} the damping rate varies very rapidly. These regions correspond precisely to the root missing intervals of the numerical solution by Rosenbluth et al.

Zhang, X.D.; Zhang, Y.Z.; Mahajan, S.M.

1993-08-01

239

Thermodynamic properties and ideal-gas enthalpies of formation for 2-aminoisobutyric acid (2-methylalanine), acetic acid, (Z)-5-ethylidene-2-norbornene, mesityl oxide (4-methyl-3-penten-2-one), 4-methylpent-1-ene, 2,2â²-bis(phenylthio)propane, and glycidyl phenyl ether (1,2-epoxy-3-phenoxypropane)  

Microsoft Academic Search

The results of a study aimed at improvement of group-contribution methodology for estimation of thermodynamic properties of organic substances are reported. Specific weaknesses where particular group-contribution terms were unknown, or estimated because of lack of experimental data, are addressed by experimental studies of enthalpies of combustion in the condensed phase, vapor-pressure measurements, and differential scanning calorimetric (DSC) heat-capacity measurements. Ideal-gas

W. V. Steele; R. D. Chirico; A. B. Cowell; S. E. Knipmeyer; A. Nguyen

1997-01-01

240

Space Sciences and Idealism  

NASA Astrophysics Data System (ADS)

Erwin Schrodinger suggested that " Scientific knowledge forms part of the idealistic background of human life", which exalted man from a nude and savage state to true humanity [Science and Humanism, Cambridge, 1961, p9]. Modern space sciences an space exploration are a brilliant demonstration of the validity of Schrodinger's thesis on Idealism. Moreover, Schrodingers thesis could be considered also as a basic principle for the New Educational Space Philosophical Project "TIMAEUS"."TIMAEUS" is not only an attempt to to start a new dialogue between Science, the Humanities and Religion; but also it is an origin of the cultural innovations of our so strange of globilisation. TIMAEUS, thus, can reveal Idealism as something more fundamental , more refined, more developed than is now accepted by the scientific community and the piblic. TIMAEUS has a significant cultural agenda, connected with the high orbital performance of the synthetic arts, combining a knowledge of the truly spiritual as well as the universal. In particular, classical ballet as a synthetic art can be a new and powerful perfector and re-creator of the real human, real idealistic, real complex culture in orbit. As is well known, Carlo Blasis, the most important dance theorist of the 19t h .century, made probably the first attempts to use the scientific ideas of Leonardo da Vinci and Isaac Newton for the understanding of the gravitational nature of balance and allegro in ballet. In particular Blasis's idea of the limited use of the legs in classical dance realised by the gifted pupils of Enrico Cecchetti - M.Fokine, A.Pavlova and V.Nijinsky, with thinkable purity and elegance of style. V.Nijinsky in his remarkable animation of the dance of two dimensional creatures of a Euclidean flat world (L'Apres Midi d'un Faune,1912) discovered that true classical dance has some gravitational limits. For example, Nijinsky's Faunes and Nymphs mut use running on the heels (In accordance with "Partitura" 1916); they cannot use a turn-out or epaulement for their pas-de-bra. In other words Nijinsky's dancers must live in weightlessness in order to perform what his "Partitura" (L'Apres Midi d'un Faune, version of 1916) describes. Diaghilev and Benois, platonised theorists of the Ballet Russe, suggested that the true idealised classical dance must be performed in Tiepolo's weightlessnessful manner of later Baroque. Anna Pavlova by her idiosyncrasy of parallel motion opened the New World of Aesthetics and brought it to its utmost perfection. Hence, it is natural to think that some findings of choreographers could be developed and tested in space environment. Moreover, we believe that classical ballet itself could be brought to perfection in space fter Diaghilev's reform. Correspondingly, we may await that such innovations can initiate a development of the New Grand Style in Arts, Music and Choreography free from contemporary religious and national prejudices.

Popov, M.

241

Quantum dots as mediators in gas sensing: A case study of CdS sensitized WO3 sensing composites  

NASA Astrophysics Data System (ADS)

In this study the proof of principle of the use of naked semiconductor directly generated on metal oxide surface as mediators in gas sensing is provided. Successive ionic layer absorption and reaction (SILAR) technique has been applied to sensitize a WO3 thin film with CdS quantum dots. Response to gases of bare WO3 is deeply modified: quantum dots dramatically increase the metal oxide conductance, otherwise rather poor, and modify the capability of detecting environmental pollutants, such as CO and NO2. A modified sensing mechanism is proposed to rationalize the mediation exerted by the semiconducting active layer on the interaction between gaseous species and WO3 surface.

Concina, Isabella; Comini, Elisabetta; Kaciulis, Saulius; Sberveglieri, Giorgio

2014-01-01

242

Steric, Quantum, and Electrostatic Effects on SN2 Reaction Barriers in Gas Phase  

SciTech Connect

Biomolecular nucleophilic substitution reactions, S{sub N}2, are fundamental and commonplace in chemistry. It is the well-documented experimental finding in the literature that vicinal substitution with bulkier groups near the reaction center significantly slows the reaction due to steric hindrance, but theoretical understanding in the quantitative manner about factors dictating the S{sub N}2 reaction barrier height is still controversial. In this work, employing the new quantification approach that we recently proposed for the steric effect from the density functional theory framework, we investigate the relative contribution of three independent effects—steric, electrostatic, and quantum—to the S{sub N}2 barrier heights in gas phase for substituted methyl halide systems, R{sub 1}R{sub 2}R{sub 3}CX, reacting with the fluorine anion, where R{sub 1}, R{sub 2}, and R{sub 3} denote substituting groups and X = F or Cl. We found that in accordance with the experimental finding, for these systems, the steric effect dominates the transition state barrier, contributing positively to barrier heights, but this contribution is largely compensated by the negative, stabilizing contribution from the quantum effect due to the exchange-correlation interactions. Moreover, we find that it is the component from the electrostatic effect that is linearly correlated with the S{sub N}2 barrier height for the systems investigated in the present study. In addition, we compared our approach with the conventional method of energy decomposition in density functional theory as well as examined the steric effect from the wave function theory for these systems via natural bond orbital analysis.

Liu, Shubin; Hu, Hao; Pedersen, Lee G.

2010-01-01

243

Ideal near-field thermophotovoltaic cells  

E-print Network

We ask the question, what are the ideal characteristics of a near-field thermophotovoltaic cell? Our search leads us to a reexamination of near-field photonic heat transfer in terms of the joint density of electronic states. This form reveals that the presence of matched van Hove singularities resulting from quantum-confinement in the emitter and converter of a thermophotovoltaic cell boosts both the magnitude and spectral selectivity of photonic heat transfer; dramatically improving energy conversion efficiency. We provide a model near-field thermophotovoltaic design making use of this idea by employing the van Hove singularities present in carbon nanotubes. Shockely Queisser analysis shows that the predicted heat transfer characteristics of this model device are fundamentally better than existing thermophotovoltaic designs. Our work paves the way for the use of quantum dots, carbon nanotubes and two-dimensional materials as future materials for thermophotovoltaic near-field energy conversion devices.

Molesky, Sean

2015-01-01

244

Primary Components of Binomial Ideals  

E-print Network

their primary components explicitly. An ideal I ? k[x_(1),….x_(n) ] is cellular if every variable is either a nonzerodivisor modulo I or is nilpotent modulo I. We characterize the minimal primary components of cellular binomial ideals explicitly. Another...

Eser, Zekiye

2014-07-11

245

Be Ye Perfect? Religious Ideals in Education  

ERIC Educational Resources Information Center

This article explores the meaning of "religious ideals" and their possible role in education. "Religious ideals" are defined as ideals that acquire meaning due to a belief in transcendence or a divine being. Two kinds of religious ideals are being distinguished, namely ideals that are constituted by a belief in a transcendent being and ideals that…

de Ruyter, Doret J.

2006-01-01

246

Be ye perfect? Religious ideals in education  

Microsoft Academic Search

This article explores the meaning of ‘religious ideals’ and their possible role in education. ‘Religious ideals’ are defined as ideals that acquire meaning due to a belief in transcendence or a divine being. Two kinds of religious ideals are being distinguished, namely ideals that are constituted by a belief in a transcendent being and ideals that are being determined by

Doret J. de Ruyter

2006-01-01

247

Quantum chaos in ultracold collisions of gas-phase erbium atoms.  

PubMed

Atomic and molecular samples reduced to temperatures below one microkelvin, yet still in the gas phase, afford unprecedented energy resolution in probing and manipulating the interactions between their constituent particles. As a result of this resolution, atoms can be made to scatter resonantly on demand, through the precise control of a magnetic field. For simple atoms, such as alkalis, scattering resonances are extremely well characterized. However, ultracold physics is now poised to enter a new regime, where much more complex species can be cooled and studied, including magnetic lanthanide atoms and even molecules. For molecules, it has been speculated that a dense set of resonances in ultracold collision cross-sections will probably exhibit essentially random fluctuations, much as the observed energy spectra of nuclear scattering do. According to the Bohigas-Giannoni-Schmit conjecture, such fluctuations would imply chaotic dynamics of the underlying classical motion driving the collision. This would necessitate new ways of looking at the fundamental interactions in ultracold atomic and molecular systems, as well as perhaps new chaos-driven states of ultracold matter. Here we describe the experimental demonstration that random spectra are indeed found at ultralow temperatures. In the experiment, an ultracold gas of erbium atoms is shown to exhibit many Fano-Feshbach resonances, of the order of three per gauss for bosons. Analysis of their statistics verifies that their distribution of nearest-neighbour spacings is what one would expect from random matrix theory. The density and statistics of these resonances are explained by fully quantum mechanical scattering calculations that locate their origin in the anisotropy of the atoms' potential energy surface. Our results therefore reveal chaotic behaviour in the native interaction between ultracold atoms. PMID:24670766

Frisch, Albert; Mark, Michael; Aikawa, Kiyotaka; Ferlaino, Francesca; Bohn, John L; Makrides, Constantinos; Petrov, Alexander; Kotochigova, Svetlana

2014-03-27

248

Long-term Operation of an External Cavity Quantum Cascade Laser-based Trace-gas Sensor for Building Air Monitoring  

SciTech Connect

We analyze the long-term performance and stability of a trace-gas sensor based on an external cavity quantum cascade laser using data collected over a one-year period in a building air monitoring application.

Phillips, Mark C.; Craig, Ian M.

2013-11-03

249

Spherical Top-Hat Collapse of Viscous Modified Chaplygin Gas in Einstein's Gravity and Loop Quantum Cosmology  

E-print Network

In this work, we focus on the collapse of a spherically symmetric perturbation, with a classical top-hat profile, to study the nonlinear evolution of only viscous modified Chaplygin gas (VMCG) perturbations in Einstein's gravity as well as in loop quantum Cosmology (LQC). In the perturbed region, we have investigated the natures of equation of state parameter, square speed of sound and another perturbed quantities. The results have been analyzed by numerical and graphical investigations.

Debnath, Ujjal

2015-01-01

250

Spherical Top-Hat Collapse of Viscous Modified Chaplygin Gas in Einstein's Gravity and Loop Quantum Cosmology  

E-print Network

In this work, we focus on the collapse of a spherically symmetric perturbation, with a classical top-hat profile, to study the nonlinear evolution of only viscous modified Chaplygin gas (VMCG) perturbations in Einstein's gravity as well as in loop quantum Cosmology (LQC). In the perturbed region, we have investigated the natures of equation of state parameter, square speed of sound and another perturbed quantities. The results have been analyzed by numerical and graphical investigations.

Ujjal Debnath; Mubasher Jamil

2015-01-03

251

FK-DLR properties of a quantum multi-type Bose-gas with a repulsive interaction  

SciTech Connect

The paper extends earlier results from Suhov and Kelbert [“FK-DLR states of a quantum Bose-gas with a hardcore interaction,” http://arxiv.org/abs/arXiv:1304.0782 ] and Suhov et al. [“Shift-invariance for FK-DLR states of a 2D quantum Bose-gas,” http://arxiv.org/abs/arXiv:1304.4177 ] about infinite-volume quantum bosonic states (FK-DLR states) to the case of multi-type particles with non-negative interactions. (An example is a quantum Widom–Rowlinson model.) Following the strategy from Suhov and Kelbert and Suhov et al., we establish that, for the values of fugacity z ? (0, 1) and inverse temperature ? > 0, finite-volume Gibbs states form a compact family in the thermodynamic limit. Next, in dimension two we show that any limit-point state (an FK-DLR state in the terminology adopted in Suhov and Kelbert and Suhov et al.) is translation-invariant.

Suhov, Y., E-mail: yms@statslab.cam.ac.uk [Statistical Laboratory, DPMMS, University of Cambridge (United Kingdom); Department of Statistics/IME, University of São Paulo (Brazil); IITP, RAS, Moscow (Russian Federation); Stuhl, I., E-mail: izabella@ime.usp.br [University of Debrecen (Hungary); IME, University of São Paulo (Brazil)

2014-08-15

252

In situ observation of sub-Poissonian atom-number fluctuations in a repulsive 1D Bose gas: quantum quasi-condensate and strongly interacting regimes  

E-print Network

In situ observation of sub-Poissonian atom-number fluctuations in a repulsive 1D Bose gas: quantum for Quantum-Atom Optics, School of Mathematics and Physics, University of Queensland, Brisbane, Queensland 4072, Australia (Dated: March 21, 2011) We report on local measurements of atom number fluctuations

253

Quantum Chaos & Quantum Computers  

E-print Network

The standard generic quantum computer model is studied analytically and numerically and the border for emergence of quantum chaos, induced by imperfections and residual inter-qubit couplings, is determined. This phenomenon appears in an isolated quantum computer without any external decoherence. The onset of quantum chaos leads to quantum computer hardware melting, strong quantum entropy growth and destruction of computer operability. The time scales for development of quantum chaos and ergodicity are determined. In spite the fact that this phenomenon is rather dangerous for quantum computing it is shown that the quantum chaos border for inter-qubit coupling is exponentially larger than the energy level spacing between quantum computer eigenstates and drops only linearly with the number of qubits n. As a result the ideal multi-qubit structure of the computer remains rather robust against imperfections. This opens a broad parameter region for a possible realization of quantum computer. The obtained results are related to the recent studies of quantum chaos in such many-body systems as nuclei, complex atoms and molecules, finite Fermi systems and quantum spin glass shards which are also reviewed in the paper.

D. L. Shepelyansky

2000-06-15

254

Quantum theory Bohrification: topos theory and quantum theory  

E-print Network

Quantum theory Bohrification: topos theory and quantum theory Bas Spitters Domains XI, 9/9/2014 Bas Spitters Bohrification: topos theory and quantum theory #12;Quantum theory Point-free Topology The axiom and quantum theory #12;Quantum theory Point-free Topology The axiom of choice is used to construct ideal

Spitters, Bas

255

Modules over principal ideal rings  

E-print Network

NODULES OVER PRINCIPAL IDEAL RINGS A Thesis by Jules Bellin Vieaux Submitted to the Graduate School of the Agricultural and Nechanical College of Texas in partial fulfillment of the requirements i'or the degree of NASTER OF SCIENCE August l...957 Na)or Sub]sot: Nathematics MODULES OVER PRINCIPAL IDEAL RINGS A Thesis Jules Bellin Vieaux Approved as to style and content by: (Chairman of Committee) (Head of Department r Student Advisor) August 1957 ACKNOWLEDGMENT I would like...

Vieaux, Jules Bellin

1957-01-01

256

Majorization and arithmetic mean ideals  

E-print Network

Following "An infinite dimensional Schur-Horn theorem and majorization theory", Journal of Functional Analysis 259 (2010) 3115-3162, this paper further studies majorization for infinite sequences. It extends to the infinite case classical results on "intermediate sequences" for finite sequence majorization. These and other infinite majorization properties are then linked to notions of infinite convexity and invariance properties under various classes of substochastic matrices to characterize arithmetic mean closed operator ideals and arithmetic mean at infinity closed operator ideals.

Kaftal, V

2012-01-01

257

Quantum state-resolved energy redistribution in gas ensembles containing highly excited N2  

NASA Astrophysics Data System (ADS)

A computational model is used to quantify the evolution of quantum state populations as highly vibrationally excited 14N2 (14N2*) equilibrates in various bath gases. Multicollision energy disposal follows general principles established in related single collision processes. Thus when state-to-state routes permit, maximum amounts of energy are deposited into partner species by direct vibration-to-vibration (V-V) exchange. When these pathways are absent, e.g., when Ar is the bath species, relaxation is very slow and multistaged. Conversely, in a bath of v = 0 14N2 molecules, 16 vibrational quanta (?v = ± 8) are resonantly exchanged from (v;j) = (8;10) with vibrational equilibration so rapid that rotation and translation still lag far behind after 1000 collisions. Near-resonant V-V exchange dominates the initial phase when 15N2 forms the bath gas and although some rotational warming occurs, vibrational modes remain decoupled from, and significantly hotter than, the low heat capacity modes. These forms of behavior seem likely to characterize excited and bath species that have closely similar vibration and rotation constants. More generic in nature is 14N2 in O2 or in a mixture that closely resembles air. Here, asymmetric V-V exchange is a dominant early feature in ensemble evolution but energy differences in the key vibration and rotation quanta lead to V-V energy defects that are compensated for by the low energy modes. This results in much more rapid ensemble equilibration, generally within 400-500 collisions, when O2 is present even as a minor constituent. Our results are in good general agreement with those obtained from experimental studies of N2 plasmas both in terms of modal temperatures and initial (first collision cycle) cross-sections.

McCaffery, Anthony J.; Pritchard, Marisian; Turner, John F. C.; Marsh, Richard J.

2011-01-01

258

BCS-BEC crossover and quantum phase transition in an ultracold Fermi gas under spin-orbit coupling  

NASA Astrophysics Data System (ADS)

In this work, we study the BCS-BEC crossover and quantum phase transition in a Fermi gas under Rashba spin-orbit coupling close to a Feshbach resonance. By adopting a two-channel model, we take into account the closed-channel molecules, and show that combined with spin-orbit coupling, a finite background scattering in the open channel can lead to two branches of solution for both the two-body and the many-body ground states. The branching of the two-body bound-state solution originates from the avoided crossing between bound states in the open and the closed channels, respectively. For the many-body states, we identify a quantum phase transition in the upper branch regardless of the sign of the background scattering length, which is in clear contrast to the case without spin-orbit coupling. For systems with negative background scattering length in particular, we show that the bound state in the open channel, and hence the quantum phase transition in the upper branch, are induced by spin-orbit coupling. We then characterize the critical detuning of the quantum phase transition for both positive and negative background scattering lengths, and demonstrate the optimal parameters for the critical point to be probed experimentally.

Wu, Fan; Zhang, Ren; Deng, Tian-Shu; Zhang, Wei; Yi, Wei; Guo, Guang-Can

2014-06-01

259

Torque on an ideal plasma.  

PubMed

Ripples in the confining field may exert a torque on a rotating plasma. Time reversal symmetry implies that this torque should vanish for an ideal plasma. However, even in an apparently ideal plasma, singularities can give rise to a nonzero torque. This torque is evaluated for a simple configuration. Although the primary force is magnetic, an essential contribution arises from other nonlinear terms in the equations of motion. The net force is confined to the singular layer, in the direction of the ripple wave vector and related to the energy absorbed in the layer. PMID:14525433

Taylor, J B

2003-09-12

260

Ultra-high mobility two-dimensional electron gas in a SiGe/Si/SiGe quantum well  

NASA Astrophysics Data System (ADS)

We report the observation of an electron gas in a SiGe/Si/SiGe quantum well with maximum mobility up to 240 m2/Vs, which is noticeably higher than previously reported results in silicon-based structures. Using SiO, rather than Al2O3, as an insulator, we obtain strongly reduced threshold voltages close to zero. In addition to the predominantly small-angle scattering well known in the high-mobility heterostructures, the observed linear temperature dependence of the conductivity reveals the presence of a short-range random potential.

Melnikov, M. Yu.; Shashkin, A. A.; Dolgopolov, V. T.; Huang, S.-H.; Liu, C. W.; Kravchenko, S. V.

2015-03-01

261

Giant Andreev Backscattering through a Quantum Point Contact Coupled via a Disordered Two-Dimensional Electron Gas to Superconductors  

SciTech Connect

We have investigated the superconducting-phase-modulated reduction in the resistance of a ballistic quantum point contact (QPC) connected via a disordered two-dimensional electron gas (2DEG) to superconductors. We show that this reduction is caused by coherent Andreev backscattering of holes through the QPC, which increases monotonically by reducing the bias voltage to zero. In contrast, the magnitude of the phase-dependent resistance of the disordered 2DEG displays a nonmonotonic reentrant behavior versus bias voltage. {copyright} {ital 1997} {ital The American Physical Society}

den Hartog, S.G.; van Wees, B.J.; Klapwijk, T.M. [Department of Applied Physics and Materials Science Center, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands)] [Department of Applied Physics and Materials Science Center, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands); Nazarov, Y.V. [Faculty of Applied Physics and Delft Institute for Microelectronics and Submicron Technology, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (The Netherlands)] [Faculty of Applied Physics and Delft Institute for Microelectronics and Submicron Technology, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (The Netherlands); Borghs, G. [Interuniversity Micro Electronics Center, Kapeldreef 75, B-3030 Leuven (Belgium)] [Interuniversity Micro Electronics Center, Kapeldreef 75, B-3030 Leuven (Belgium)

1997-10-01

262

Lorentz ratio of quantum plasmas  

SciTech Connect

A quantum collective approach is developed to investigate linear transport properties of a system of highly degenerate weakly coupled electrons and strongly coupled semiclassical ions. The basic formalism rests upon suitable extention of the Boltzmann--Bloch quantum transport equation. The model considers electron--ion (e--i) and electron--electron (e--e) collisions in a unified scheme of both long- and short-range Coulomb interactions. The e--e collisions contribute to the thermal conductivity calculation in the low coupling regime. Even though they can be insignificant for strongly coupled systems, the extensively used Lorentz gas approximation cannot be justified for plasmas of astrophysical interests. It is shown that the Lorentz ratio of high-density plasma may exhibit substantial negative deviation from the ideal Sommerfeld value, due to some nonidealities, such as e--e interaction and quantum effects. Results are presented under analytical and compact forms allowing numerical applications, as well as comparisons with existing theories.

Khalfaoui, A.; Bennaceur, D. (Centre de Developpement des Technologies Avancees, Laboratoire Interaction Laser-Matiere, 2 Bd Franz Fanon, BP 1017 Alger-gare 16000 (Algeria))

1994-06-01

263

Use of external cavity quantum cascade laser compliance voltage in real-time trace gas sensing of multiple chemicals  

NASA Astrophysics Data System (ADS)

We describe a prototype trace gas sensor designed for real-time detection of multiple chemicals. The sensor uses an external cavity quantum cascade laser (ECQCL) swept over its tuning range of 940-1075 cm-1 (9.30-10.7 ?m) at a 10 Hz repetition rate. The sensor was designed for operation in multiple modes, including gas sensing within a multi-pass Heriott cell and intracavity absorption sensing using the ECQCL compliance voltage. In addition, the ECQCL compliance voltage was used to reduce effects of long-term drifts in the ECQCL output power. The sensor was characterized for noise, drift, and detection of chemicals including ammonia, methanol, ethanol, isopropanol, Freon- 134a, Freon-152a, and diisopropyl methylphosphonate (DIMP). We also present use of the sensor for mobile detection of ammonia downwind of cattle facilities, in which concentrations were recorded at 1-s intervals.

Phillips, Mark C.; Taubman, Matthew S.; Kriesel, Jason

2015-01-01

264

Chemical Laws, Idealization and Approximation  

ERIC Educational Resources Information Center

This paper examines the notion of laws in chemistry. Vihalemm ("Found Chem" 5(1):7-22, 2003) argues that the laws of chemistry are fundamentally the same as the laws of physics they are all "ceteris paribus" laws which are true "in ideal conditions". In contrast, Scerri (2000) contends that the laws of chemistry are…

Tobin, Emma

2013-01-01

265

Ideal Multipartite Secret Sharing Schemes  

NASA Astrophysics Data System (ADS)

Multipartite secret sharing schemes are those having a multipartite access structure, in which the set of participants is divided into several parts and all participants in the same part play an equivalent role. Several particular families of multipartite schemes, such as the weighted threshold schemes, the hierarchical and the compartmented schemes, and the ones with bipartite or tripartite access structure have been considered in the literature. The characterization of the access structures of ideal secret sharing schemes is one of the main open problems in secret sharing. In this work, the characterization of ideal multipartite access structures is studied with all generality. Our results are based on the well-known connections between ideal secret sharing schemes and matroids. One of the main contributions of this paper is the application of discrete polymatroids to secret sharing. They are proved to be a powerful tool to study the properties of multipartite matroids. In this way, we obtain some necessary conditions and some sufficient conditions for a multipartite access structure to be ideal.

Farràs, Oriol; Martí-Farré, Jaume; Padró, Carles

266

Ideal pharmacotherapy for allergic rhinitis  

Microsoft Academic Search

The characteristics of the “ideal” pharmacotherapeutic agent for managing the symptoms of seasonal allergic rhinitis and the advantages and disadvantages of the pharmacotherapeutic agents that are currently available are reviewed. Decongestants, mast cell stabilizers, anticholinergics, intranasal steroids, and oral antihistamines and their place in the therapeutic armamentarium of the clinician are discussed. (J Allergy Clin Immunol 1999;103:S386-7)

Sheldon Spector

1999-01-01

267

Lecture notes Ideal fluid mechanics  

E-print Network

Lecture notes Ideal fluid mechanics Simon J.A. Malham Simon J.A. Malham (6th Feb 2010) Maxwell and in the process learn about the subtleties of fluid mechanics and along the way see lots of interesting are generally incompressible--a feature essential to all modern car braking mechanisms. Fluids can be further

Malham, Simon J.A.

268

Mapping trapped atomic gas with spin-orbit coupling to quantum Rabi-like model  

E-print Network

We construct a connection of the ultracold atomic system in a harmonic trap with Raman-induced spin-orbit coupling to the quantum Rabi-like model. By mapping the trapped atomic system to a Rabi-like model, we can get the exact solution of the Rabi-like model following the methods to solve the quantum Rabi model. The existence of such a mapping implies that we can study the basic model in quantum optics by using trapped atomic gases with spin-orbit coupling.

Haiping Hu; Shu Chen

2013-02-24

269

Thermodynamic properties and ideal-gas enthalpies of formation for 2-aminoisobutyric acid (2-methylalanine), acetic acid, (Z)-5-ethylidene-2-norbornene, mesityl oxide (4-methyl-3-penten-2-one), 4-methylpent-1-ene, 2,2{prime}-bis(phenylthio)propane, and glycidyl phenyl ether (1,2-epoxy-3-phenoxypropane)  

SciTech Connect

The results of a study aimed at improvement of group-contribution methodology for estimation of thermodynamic properties of organic substances are reported. Specific weaknesses where particular group-contribution terms were unknown, or estimated because of lack of experimental data, are addressed by experimental studies of enthalpies of combustion in the condensed phase, vapor-pressure measurements, and differential scanning calorimetric (DSC) heat-capacity measurements. Ideal-gas enthalpies of formation of acetic acid, (Z)-5-ethylidene-2-norbornene, mesityl oxide (4-methyl-3-penten-2-one), 4-methylpent-1-ene, glycidyl phenyl ether (1,2-epoxy-3-phenoxypropane), and 2,2{prime}-bis(phenylthio)propane are reported. An enthalpy of formation of 2-aminoisobutyric acid (2-methylalanine) in the crystalline phase was determined. Using a literature value for the enthalpy of sublimation of 2-aminoisobutyric acid, a value for the ideal-gas enthalpy of formation was derived. An enthalpy of fusion was determined for 2,2{prime}-bis(phenylthio)propane. Two-phase (solid + vapor) or (liquid + vapor) heat capacities were determined from 300 K to the critical region or earlier decomposition temperature for all the compounds except acetic acid. For mesityl oxide and 4-methylpent-1-ene, critical temperatures and critical densities were determined from the DSC results and corresponding critical pressures derived from the fitting procedures. Group-additivity parameters and ring strain energies useful in the application of group-contribution correlations were derived.

Steele, W.V.; Chirico, R.D.; Cowell, A.B.; Knipmeyer, S.E.; Nguyen, A. [National Inst. for Petroleum and Energy Research, Bartlesville, OK (United States)] [National Inst. for Petroleum and Energy Research, Bartlesville, OK (United States)

1997-11-01

270

Quantum coherence in the dynamical excitation, ionization, and decaying of neon gas induced by X-ray laser  

E-print Network

We develop a large scale quantum master equation approach to describe dynamical processes of practical open quantum systems driven by both coherent and stochastic interactions by including more than one thousand true states of the systems, motivated by the development of highly bright and fully coherent lasers in the X-ray wavelength regime. The method combines the processes of coherent dynamics induced by the X-ray laser and incoherent relaxations due to spontaneous emissions, Auger decays, and electronic collisions. As examples, theoretical investigation of {\\it real} coherent dynamics of inner-shell electrons of a neon gas, irradiated by a high-intensity X-ray laser with a full temporal coherence, is carried out with the approach. In contrast to the rate equation treatment, we find that coherence can suppress the multiphoton absorptions of a neon gas in the ultra-intense X-ray pulse, due to coherence-induced Rabi oscillations and power broadening effects. We study the influence of coherence on ionization p...

Li, Yongqiang; Dong, Wenpu; Zeng, Jiaolong; Yuan, Jianmin

2015-01-01

271

Photoacoustic spectroscopy for trace gas detection with cryogenic and room-temperature continuous-wave quantum cascade lasers  

NASA Astrophysics Data System (ADS)

The main characteristics that a sensor must possess for trace gas detection and pollution monitoring are high sensitivity, high selectivity and the capability to perform in situ measurements. The photacoustic Helmholtz sensor developed in Reims, used in conjunction with powerful Quantum Cascade Lasers (QCLs), fulfils all these requirements. The best cell response is # 1200 V W-1 cm and the corresponding ultimate sensitivity is j 3.3 × 10-10 W cm-11 Hz-11/2. This efficient sensor is used with mid-infrared QCLs from Alpes Lasers to reach the strong fundamental absorption bands of some atmospheric gases. A first cryogenic QCL emitting at 7.9 ?m demonstrates the detection of methane in air with a detection limit of 3 ppb. A detection limit of 20 ppb of NO in air is demonstrated using another cryogenic QCL emitting in the 5.4 ?m region. Real in-situ measurements can be achieved only with room-temperature QCLs. A room-temperature QCL emitting in the 7.9 ?m region demonstrates the simultaneous detection of methane and nitrous oxide in air (17 and 7 ppb detection limit, respectively). All these reliable measurements allow the estimated detection limit for various atmospheric gases using quantum cascade lasers to be obtained. Each gas absorbing in the infrared may be detected at a detection limit in the ppb or low-ppb range.

Zeninari, Virginie; Grossel, Agnès; Joly, Lilian; Decarpenterie, Thomas; Grouiez, Bruno; Bonno, Bernard; Parvitte, Bertrand

2010-04-01

272

Tunable Interactions in Quantum Degenerate Lithium  

NASA Astrophysics Data System (ADS)

Quantum degenerate gases provide an ideal environment for studying fundamental physics. In these systems, a Feshbach resonance can be utilized to tune the interactions between certain colliding pairs of atoms, yielding control over both the magnitude and sign of the interactions. This has opened the doorway to a new area in which the underlying physics of non-linear optical phenomena and many solid-state effects can be explored in the ideal environment of a quantum degenerate gas. We will first discuss the experimental realization of a quantum degenerate Bose-Fermi mixture via sympathetic cooling [truscott01]. By confining this quantum degenerate gas in an all optical potential, the atom-atom interactions of the bosons can be manipulated to produce bright matter-wave solitons [strecker02] which are individual Bose-Einstein condensates (BEC) that we have observed to propagate for over 3 seconds without dispersion. Further, a highly interacting Fermi gas can be produced near a Feshbach resonance, and through manipulation of the external magnetic field, long lived ultra-cold bosonic molecules can be formed from the Fermi gas [strecker03]. The unexpected long lifetime of these vibrationally excited (v' = 38) molecules enables them to be evaporatively cooled to a molecular BEC. We use a pure molecular condensate as a probe of the BEC/BCS crossover region within the broad Feshbach resonance. Using an interrogation laser tuned to a bound-bound molecular resonance, the deeply bound molecular component of the gas is measured as a function of magnetic field, probing the fundamental many-body physics of a strongly interacting Fermi gas. [truscott01] A. G. Truscott, K. E. Strecker, W. I. McAlexander, G. B. Patridge, and R. G. Hulet, Science 291, 2570 (2001). [strecker02] K. E. Strecker, G. B. Partridge, A. G. Truscott, and R.G Hulet, Nature 417, 150 (2002). [strecker03] K. E. Strecker, G. B. Partridge and R. G. Hulet, Phys Rev. Lett. 91, 080406 (2003).

Strecker, Kevin

2005-05-01

273

Experimentally efficient methods for estimating the performance of quantum measurements  

E-print Network

Efficient methods for characterizing the performance of quantum measurements are important in the experimental quantum sciences. Ideally, one requires both a physically relevant distinguishability measure between measurement ...

Magesan, Easwar

274

Representation of Ideal Magnetohydrodynamic Modes  

SciTech Connect

One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through ? ? = ? X (xi X B) ensures that ? B • ? ? = 0 at a resonance, with ? labelling an equilibrium flux surface. Also useful for the analysis of guiding center orbits in a perturbed field is the representation ? ? = ? X ?B. These two representations are equivalent, but the vanishing of ? B • ?? at a resonance is necessary but not sufficient for the preservation of field line topology, and a indiscriminate use of either perturbation in fact destroys the original equilibrium flux topology. It is necessary to find the perturbed field to all orders in xi to conserve the original topology. The effect of using linearized perturbations on stability and growth rate calculations is discussed

Roscoe B. White

2013-01-15

275

Chemical dynamics in the gas phase: Time-dependent quantum mechanics of chemical reactions  

SciTech Connect

A major goal of this research is to obtain an understanding of the molecular reaction dynamics of three and four atom chemical reactions using numerically accurate quantum dynamics. This work involves: (i) the development and/or improvement of accurate quantum mechanical methods for the calculation and analysis of the properties of chemical reactions (e.g., rate constants and product distributions), and (ii) the determination of accurate dynamical results for selected chemical systems, which allow one to compare directly with experiment, determine the reliability of the underlying potential energy surfaces, and test the validity of approximate theories. This research emphasizes the use of recently developed time-dependent quantum mechanical methods, i.e. wave packet methods.

Gray, S.K. [Argonne National Laboratory, IL (United States)

1993-12-01

276

M. Bahrami ENSC 461 (S 11) Jet Propulsion Cycle 1 Ideal JetPropulsion Cycle  

E-print Network

M. Bahrami ENSC 461 (S 11) Jet Propulsion Cycle 1 Ideal JetPropulsion Cycle Gas-turbine engines. Aircraft gas turbines operate on an open cycle called jet-propulsion cycle. Some of the major differences between the gas-turbine and jet-propulsion cycles are: gases are expanded in the turbine to a pressure

Bahrami, Majid

277

Quantum-relativistic hydrodynamic model for a spin-polarized electron gas interacting with light.  

PubMed

We develop a semirelativistic quantum fluid theory based on the expansion of the Dirac Hamiltonian to second order in 1/c. By making use of the Madelung representation of the wave function, we derive a set of hydrodynamic equations that comprises a continuity equation, an Euler equation for the mean velocity, and an evolution equation for the electron spin density. This hydrodynamic model is then applied to study the dynamics of a dense and weakly relativistic electron plasma. In particular, we investigate the impact of the quantum-relativistic spin effects on the Faraday rotation in a one-dimensional plasma slab irradiated by an x-ray laser source. PMID:25122397

Morandi, Omar; Zamanian, Jens; Manfredi, Giovanni; Hervieux, Paul-Antoine

2014-07-01

278

Vortex quantum creation and winding number scaling in a quenched spinor Bose gas.  

PubMed

Motivated by a recent experiment, we study nonequilibrium quantum phenomena taking place in the quench of a spinor Bose-Einstein condensate through the zero-temperature phase transition separating the polar paramagnetic and planar ferromagnetic phases. We derive the typical spin domain structure (correlations of the effective magnetization) created by the quench arising due to spin-mode quantum fluctuations, and we establish a sample-size scaling law for the creation of spin vortices, which are topological defects in the transverse magnetization. PMID:17930483

Uhlmann, Michael; Schützhold, Ralf; Fischer, Uwe R

2007-09-21

279

Vortex Quantum Creation and Winding Number Scaling in a Quenched Spinor Bose Gas  

SciTech Connect

Motivated by a recent experiment, we study nonequilibrium quantum phenomena taking place in the quench of a spinor Bose-Einstein condensate through the zero-temperature phase transition separating the polar paramagnetic and planar ferromagnetic phases. We derive the typical spin domain structure (correlations of the effective magnetization) created by the quench arising due to spin-mode quantum fluctuations, and we establish a sample-size scaling law for the creation of spin vortices, which are topological defects in the transverse magnetization.

Uhlmann, Michael; Schuetzhold, Ralf [Institut fuer Theoretische Physik, Technische Universitaet Dresden, D-01062 Dresden (Germany); Fischer, Uwe R. [Eberhard-Karls-Universitaet Tuebingen, Institut fuer Theoretische Physik, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2007-09-21

280

Detonation Failure in Ideal and Non-Ideal Explosives  

NASA Astrophysics Data System (ADS)

In this paper we revisit and extend the classic treatment of detonation failure developed by Eyring et. al. [1]. We recently published a development of this theory [2] in which a pressure dependant rate law was substituted for the Arrhenius temperature dependant law originally considered. Here we show that by assuming a 2-component rate law based upon a temperature dependant ignition phase and a pressure dependant growth phase we are able to rationalise the very different failure characteristics (critical diameter and velocity decrement at failure) of ideal and non-ideal explosives. [1] Eyring, H., Powell, R.E., Duffy, G.H., and Parlin, R.B., ``The stability of detonation,'' Chem. Rev. 45, 69-181 (1949). [2] Haskins, P.J., Cook, M.D., and Wood, A.D., ``On the dependence of critical diameter and velocity decrement at failure on the burn law,'' in proceedings of the 33rd International Pyrotechnics Seminar, Fort Collins, Co, USA, 385-391 (2006).

Haskins, P. J.; Cook, M. D.

2007-06-01

281

Beyond the Quantum  

NASA Astrophysics Data System (ADS)

pt. A. Introductions. The mathematical basis for deterministic quantum mechanics / G.'t Hooft. What did we learn from quantum gravity? / A. Ashtekar. Bose-Einstein condensates and EPR quantum non-locality / F. Laloe. The quantum measurement process: lessons from an exactly solvable model / A.E. Allahverdyan, R. Balian and Th. M. Nieuwenhuizen -- pt. B. Quantum mechanics and quantum information. POVMs: a small but important step beyond standard quantum mechanics / W. M. de Muynck. State reduction by measurements with a null result / G. Nienhuis. Solving open questions in the Bose-Einstein condensation of an ideal gas via a hybrid mixture of laser and statistical physics / M. Kim, A. Svidzinsky and M.O. Scully. Twin-Photon light scattering and causality / G. Puentes, A. Aiello and J. P. Woerdman. Simultaneous measurement of non-commuting observables / G. Aquino and B. Mehmani. Quantum decoherence and gravitational waves / M.T. Jaekel ... [et al.]. Role of various entropies in the black hole information loss problem / Th. M. Nieuwenhuizen and I.V. Volovich. Quantum and super-quantum correlations / G.S. Jaeger -- pt. C. Long distance correlations and bell inequalities. Understanding long-distance quantum correlations / L. Marchildon. Connection of probability models to EPR experiments: probability spaces and Bell's theorem / K. Hess and W. Philipp. Fair sampling vs no-signalling principle in EPR experiments / G. Adenier and A. Yu. Khrennikov -- pt. D. Mathematical foundations. Where the mathematical structure of quantum mechanics comes from / G.M. D'Ariano. Phase space description of quantum mechanics and non-commutative geometry: Wigner-Moyal and Bohm in a wider context / B.J. Hiley. Quantum mechanics as simple algorithm for approximation of classical integrals / A. Yu. Khrennikov. Noncommutative quantum mechanics viewed from Feynman Formalism / J. Lages ... [et al.]. Beyond the quantum in Snyder space / J.F.S. van Huele and M. K. Transtrum -- pt. E. Stochastic electrodynamics. Some quantum experiments from the point of view of Stochastic electrodynamics / V. Spicka ... [et al.]. On the ergodic behaviour of atomic systems under the action of the zero-point radiation field / L. De La Peña and A. M. Cetto. Inertia and the vacuum-view on the emergence of the inertia reaction force / A. Rueda and H. Sunahata -- pt. F. Models for the electron. Rotating Hopf-Kinks: oscillators in the sense of de Broglie / U. Enz. Kerr-Newman particles: symmetries and other properties / H.I. Arcos and J.G. Pereira. Kerr geometry beyond the quantum theory / Th. M. Nieuwenhuizen -- pt. G. Philosophical considerations. Probability in non-collapse interpretations of a quantum mechanics / D. Dieks. The Schrödinger-Park paradox about the concept of "State" in quantum statistical mechanics and quantum information theory is still open: one more reason to go beyond? / G.P. Beretta. The conjecture that local realism is possible / E. Santos -- pt. H. The round table. Round table discussion / A.M. Cetto ... [et al.].

Nieuwenhuizen, Theo M.; Mehmani, Bahar; Špi?ka, Václav; Aghdami, Maryam J.; Khrennikov, Andrei Yu

2007-09-01

282

Quantum chemical analysis of the energy of proton transfer from phenol and chlorophenols to H2O in the gas phase and in aqueous solution  

Microsoft Academic Search

Proton transfer energies of phenol and 14 chlorophenols with H2O as a base are analyzed in the gas phase and in solution using quantum chemical methods at the semiempirical and ab initio level of computation. The effect of aqueous solution was accounted for by applying the density functional theory (DFT) implementation of the conductor-like screening model (COSMO) as well as

Gerrit Schüürmann

1998-01-01

283

Nearly ideal lens optimization procedure  

SciTech Connect

The Brixner lens optimization procedure, in which a lens design moves steadily toward diffraction-limited performance, samples lens performance with bundles of precisely traced skew rays, analyzes performance by calculating the image-spot sizes and positions, and optimizes performance in a least squares system that minimizes the lateral ray deviations from their ideal image points. Minimizing the rms image-spot size minimizes the rms optical path differences (OPDs). Minimizing the rms OPDs also optimizes the diffraction modulation transfer function (DMTF). Minimizing the image-spot size and position errors also minimizes and balances the Seidel and higher-order aberrations. 23 refs., 2 figs.

Brixner, B.

1985-01-01

284

[Mid-infrared distributed-feedback quantum cascade laser-based photoacoustic detection of trace methane gas].  

PubMed

There have been considerable interests in methane detection based on infrared absorption spectroscopy for industrial and environment monitoring. The authors report on the realization of photoacoustic detection of methane (CH4) using mid-infrared distributed-feedback quantum cascade laser (DFB-QCL). The absorption line at 1316.83 cm(-1) was selected for CH4 detection, which can be reached by the self-manufactured DFB-QCL source operating in pulsed mode near 7.6 microm at room-temperature. The CH4 gas is filled to a Helmholtz resonant photoacoustic cell, which was equipped with a commercial electret microphone. The DFB-QCL was operated at 234 Hz with an 80 mW optical peak power. A detection limit of 189 parts per billion in volume was derived when the signal-to-noise ratio equaled 1. PMID:22827065

Tan, Song; Liu, Wan-feng; Wang, Li-jun; Zhang, Jin-chuan; Li, Lu; Liu, Jun-qi; Liu, Feng-qi; Wang, Zhan-guo

2012-05-01

285

Quantum-tunneling dynamics of a spin-polarized Fermi gas in a double-well potential  

SciTech Connect

We study the exact dynamics of a one-dimensional spin-polarized gas of fermions in a double-well potential at zero and finite temperature. Despite the system being made of noninteracting fermions, its dynamics can be quite complex, showing strongly aperiodic spatio-temporal patterns during the tunneling. The extension of these results to the case of mixtures of spin-polarized fermions interacting with self-trapped Bose-Einstein condensates (BECs) at zero temperature is considered as well. In this case we show that the fermionic dynamics remains qualitatively similar to that observed in the absence of BEC but with the Rabi frequencies of fermionic excited states explicitly depending on the number of bosons and on the boson-fermion interaction strength. From this, the possibility of controlling quantum fermionic dynamics by means of Feshbach resonances is suggested.

Salasnich, L.; Mazzarella, G.; Toigo, F. [Dipartimento di Fisica 'Galileo Galilei' and CNISM, Universita di Padova, Via Marzolo 8, I-35122 Padua (Italy); Salerno, M. [Dipartimento di Fisica 'E.R. Caianiello', CNISM and INFN-Gruppo Collegato di Salerno, Universita di Salerno, Via Ponte don Melillo, I-84084 Fisciano(Italy)

2010-02-15

286

Non-equilibrium dynamics of an ultracold Bose gas under a multi-pulsed quantum quench in interaction  

E-print Network

We investigate the nonequilibrium dynamical properties of a weakly-interacting Bose gas at zero temperature under the multi-pulsed quantum quench in interaction by calculating one-body, two-body correlation functions and Tan's contact of the model system. The multi-pulsed quench is represented as follows: first suddenly quenching the interatomic interaction from $g_{i}$ to $g_{f}$ at time $t=0$, holding time $t$, and then suddenly quenching interaction from $g_{f}$ back to $g_{i}$, holding the time $t$ sequence $n$ times. In particular, two typical kinds of quenching parameters are chosen, corresponding to $(g_{i}/g_{f}>1)$ and $(g_{i}/g_{f}ultra-short-range properties of the two-body correlation function after the $n$th quenching, which can be used to probe the `Tan'scontact' in experiments. All our calculations can be tested in current cold atom experiments.

Lei Chen; Zhidong Zhang; Zhaoxin Liang

2015-01-28

287

The Ideal of the Educated Person.  

ERIC Educational Resources Information Center

R. S. Peters' conception of the ideal educated person is based on a male cognitive perspective and ignores women's needs. A gender-sensitive ideal is needed which acknowledges the values and traits women bring to society. (PP)

Martin, Jane Roland

1981-01-01

288

Homological Invariants of Monomial and Binomial Ideals  

E-print Network

In this dissertation, we study numerical invariants of minimal graded free resolutions of homogeneous ideals in a polynomial ring R. Chapters 2, 3 and 4 deal with homological invariants of edge ideals of bipartite graphs. First, in Chapter 2, we...

Kummini, Neelakandhan Manoj

2008-08-19

289

Development of a Polarizable Force Field For Proteins via Ab Initio Quantum Chemistry: First Generation Model and Gas Phase Tests  

PubMed Central

We present results of developing a methodology suitable for producing molecular mechanics force fields with explicit treatment of electrostatic polarization for proteins and other molecular system of biological interest. The technique allows simulation of realistic-size systems. Employing high-level ab initio data as a target for fitting allows us to avoid the problem of the lack of detailed experimental data. Using the fast and reliable quantum mechanical methods supplies robust fitting data for the resulting parameter sets. As a result, gas-phase many-body effects for dipeptides are captured within the average RMSD of 0.22 kcal/mol from their ab initio values, and conformational energies for the di- and tetrapeptides are reproduced within the average RMSD of 0.43 kcal/mol from their quantum mechanical counterparts. The latter is achieved in part because of application of a novel torsional fitting technique recently developed in our group, which has already been used to greatly improve accuracy of the peptide conformational equilibrium prediction with the OPLS-AA force field.1 Finally, we have employed the newly developed first-generation model in computing gas-phase conformations of real proteins, as well as in molecular dynamics studies of the systems. The results show that, although the overall accuracy is no better than what can be achieved with a fixed-charges model, the methodology produces robust results, permits reasonably low computational cost, and avoids other computational problems typical for polarizable force fields. It can be considered as a solid basis for building a more accurate and complete second-generation model. PMID:12395421

KAMINSKI, GEORGE A.; STERN, HARRY A.; BERNE, B. J.; FRIESNER, RICHARD A.; CAO, YIXIANG X.; MURPHY, ROBERT B.; ZHOU, RUHONG; HALGREN, THOMAS A.

2014-01-01

290

Life's Solutions are Not Ideal  

E-print Network

Life occurs in ionic solutions, not pure water. The ionic mixtures of these solutions are very different from water and have dramatic effects on the cells and molecules of biological systems, yet theories and simulations cannot calculate their properties. I suggest the reason is that existing theories stem from the classical theory of ideal or simple gases in which (to a first approximation) atoms do not interact. Even the law of mass action describes reactants as if they were ideal. I propose that theories of ionic solutions should start with the theory of complex fluids because that theory is designed to deal with interactions from the beginning. The variational theory of complex fluids is particularly well suited to describe mixtures like the solutions in and outside biological cells. When a component or force is added to a solution, the theory derives - by mathematics alone - a set of partial differential equations that captures the resulting interactions self-consistently. Such a theory has been implemented and shown to be computable in biologically relevant systems but it has not yet been thoroughly tested in equilibrium or flow.

Bob Eisenberg

2011-05-01

291

Representation of ideal magnetohydrodynamic modes  

SciTech Connect

One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through {delta}B(vector sign)={nabla} Multiplication-Sign ({xi}(vector sign) Multiplication-Sign B(vector sign)) ensures that {delta}B(vector sign){center_dot}{nabla}{psi}=0 at a resonance, with {psi} labelling an equilibrium flux surface. Also useful for the analysis of guiding center orbits in a perturbed field is the representation {delta}B(vector sign)={nabla} Multiplication-Sign {alpha}B(vector sign). These two representations are equivalent, but the vanishing of {delta}B(vector sign){center_dot}{nabla}{psi} at a resonance is necessary but not sufficient for the preservation of field line topology, and a indiscriminate use of either perturbation in fact destroys the original equilibrium flux topology. It is necessary to find the perturbed field to all orders in {xi}(vector sign) to conserve the original topology. The effect of using linearized perturbations on stability and growth rate calculations is discussed.

White, R. B. [Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States)

2013-02-15

292

Growth initiation for buried-heterostructure quantum-cascade laser regrowth by gas-source molecular-beam epitaxy  

NASA Astrophysics Data System (ADS)

We describe an optimized growth sequence for the overgrowth of quantum cascade laser ridge sidewalls with semi-insulating InP:Fe. A thin In0.52Al0.48As spacer layer grown on the laser ridge sidewalls before InP:Fe prevents the formation of void defects at this interface, which appear otherwise. Elimination of these voids at the sidewalls has led to more than a two-fold improvement of the thermal conductivity in a 7 ?m wide buried-heterostructure quantum-cascade laser overgrown with InP:Fe by gas-source molecular-beam epitaxy, and has allowed the continuous-wave operation of the laser up to 210 K. The measured thermal conductance is Gth=500 W/K cm2 at 210 K and Gth=1020 W/K cm2 at 127 K, comparable to the state of the art literature values obtained with regrowth by metal-organic vapor-phase epitaxy.

Flores, Y. V.; Elagin, M.; Kurlov, S. S.; Aleksandrova, A.; Monastyrskyi, G.; Kischkat, J.; Semtsiv, M. P.; Masselink, W. T.

2014-07-01

293

Critical points in a relativistic bosonic gas induced by the quantum structure of spacetime  

E-print Network

It is well known that phase transitions arise if the interaction among particles embodies an attractive as well as a repulsive contribution. In this work it will be shown that the breakdown of Lorentz symmetry, characterized through a deformation in the relation dispersion, plus the bosonic statistics predict the emergence of critical points. In other words, in some quantum gravity models the structure of spacetime implies the emergence of critical points even when no interaction among the particle has been considered.

Elias Castellanos; Abel Camacho

2008-10-02

294

Dynamics of a cold quantum gas in a ?-split one-dimensional potential well  

Microsoft Academic Search

Dynamics of a wave function in a non-symmetrically split (spatially asymmetric) doublewell potential is considered. We study\\u000a the dependence of the probability of well-to-well transitions on the degree of spatial asymmetry of well sizes and show that\\u000a the quantum tunneling between the wells is significantly suppressed by this asymmetry. Practically complete suppression occurs\\u000a at five-ten percent asymmetry. This is close

G. A. Muradyan; A. Zh. Muradyan

2009-01-01

295

Discrimination and bias in the vegan ideal  

Microsoft Academic Search

The vegan ideal is entailed by arguments for ethical veganism based on traditional moral theory (rights and\\/or utilitarianism) extended to animals. The most ideal lifestyle would abjure the use of animals or their products for food since animals suffer and have rights not to be killed. The ideal is discriminatory because the arguments presuppose a male physiological norm that gives

Kathryn Paxton George

1994-01-01

296

On the Splitting of a Quantum Degenerate Gas of Identical Bosons  

NASA Astrophysics Data System (ADS)

The observation of Bose-Einstein condensation in dilute clouds of trapped atoms has stimulated a great deal of research in the last 15 years. Since the basic description of a single Bose-Einstein condensate (BEC) is that of a single macroscopic condensate wavefunction, or condensate order parameter, which displays all of the interference and non-local phenomena associated with the typical quantum mechanical wavefunction, yet describes up to millions of particles, these systems have the potential to bridge the quantum mechanical and visible classical worlds. Many basic scientific questions can be addressed by examining what happens when a single such system is split into multiple entities, independently manipulated and then recombined as has been done experimentally in the case of two potential welts [1] and many potential wells [2], [3]. This thesis shows that these experiments can operate in both a classical and quantum mechanical splitting regime and demarcates the boundary in between the two. By analyzing two specific BEC splitting experiments, it is shown that splitting experiments operating in the limit of a large number of particles per well can exhibit a phenomenon analogous to supercooling in classical phase transitions. In order to perform these simulations, a novel method, extending earlier theoretical work on the splitting problem is presented, computationally implemented, and supported by analytic calculations when possible.

Faust, Douglas Karl

2011-12-01

297

Statistical mechanics based on fractional classical and quantum mechanics  

SciTech Connect

The purpose of this work is to study some problems in statistical mechanics based on the fractional classical and quantum mechanics. At first stage we have presented the thermodynamical properties of the classical ideal gas and the system of N classical oscillators. In both cases, the Hamiltonian contains fractional exponents of the phase space (position and momentum). At the second stage, in the context of the fractional quantum mechanics, we have calculated the thermodynamical properties for the black body radiation, studied the Bose-Einstein statistics with the related problem of the condensation and the Fermi-Dirac statistics.

Korichi, Z.; Meftah, M. T., E-mail: mewalid@yahoo.com [Physics Department, LRPPS Laboratory, Ouargla University, Ouargla 30000 (Algeria)

2014-03-15

298

Quantum Behavior of an Atomic Fermi Gas Brian DeMarco  

E-print Network

. Dorothy Bahrenburg encouraged my development into a leadership position and boosted my self-esteem and developing a technique for simultaneous evaporative cooling. The ability to cool an interacting, two to the classical expectation. Furthermore, the effect of the Fermi-Dirac statistics of the gas on individual

Jin, Deborah

299

Computational Methods for Ideal Magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

Numerical schemes for the ideal magnetohydrodynamics (MHD) are widely used for modeling space weather and astrophysical flows. They are designed to resolve the different waves that propagate through a magnetohydro fluid, namely, the fast, Alfven, slow, and entropy waves. Numerical schemes for ideal magnetohydrodynamics that are based on the standard finite volume (FV) discretization exhibit pseudo-convergence in which non-regular waves no longer exist only after heavy grid refinement. A method is described for obtaining solutions for coplanar and near coplanar cases that consist of only regular waves, independent of grid refinement. The method, referred to as Compound Wave Modification (CWM), involves removing the flux associated with non-regular structures and can be used for simulations in two- and three-dimensions because it does not require explicitly tracking an Alfven wave. For a near coplanar case, and for grids with 213 points or less, we find root-mean-square-errors (RMSEs) that are as much as 6 times smaller. For the coplanar case, in which non-regular structures will exist at all levels of grid refinement for standard FV schemes, the RMSE is as much as 25 times smaller. A multidimensional ideal MHD code has been implemented for simulations on graphics processing units (GPUs). Performance measurements were conducted for both the NVIDIA GeForce GTX Titan and Intel Xeon E5645 processor. The GPU is shown to perform one to two orders of magnitude greater than the CPU when using a single core, and two to three times greater than when run in parallel with OpenMP. Performance comparisons are made for two methods of storing data on the GPU. The first approach stores data as an Array of Structures (AoS), e.g., a point coordinate array of size 3 x n is iterated over. The second approach stores data as a Structure of Arrays (SoA), e.g. three separate arrays of size n are iterated over simultaneously. For an AoS, coalescing does not occur, reducing memory efficiency. All results are given for Cartesian grids, but the algorithms are implemented for a general geometry on a unstructured grids.

Kercher, Andrew D.

300

Irreversibility in an ideal fluid  

NASA Astrophysics Data System (ADS)

When a real fluid is expelled quickly from a tube, it forms a jet separated from the surrounding fluid by a thin, turbulent layer. On the other hand, when the same fluid is sucked into the tube, it enters from all directions, forming a sink-like flow. We show that, even for the ideal flow described by the time-reversible Euler equation, an experimenter who only controls the pressure in a pump attached to the tube would see jets form in one direction exclusively. The asymmetry between outflow and inflow therefore does not depend on viscous dissipation, but rather on the experimenter's limited control of initial and boundary conditions. This illustrates, in a rather different context from the usual one of thermal physics, how irreversibility may arise in systems whose microscopic dynamics are fully reversible.

Jenkins, Alejandro

2014-11-01

301

Quantum-chemical modeling of boron and noble gas dopants in silicon  

NASA Technical Reports Server (NTRS)

The electron effects of the presence of boron and noble gas dopants in a model silicon lattice were investigated using a self-consistent charge extended Hueckel program. The extent of electronic interaction of the noble gas with the lattice is given by: Kr greater than Ar greater than Ne. Theoretically, boron diffusion in the presence of neon, argon or krypton was examined using a self-consistent charge extended Hueckel program. The net energy of interaction between boron and neon is strongly repulsive while argon-boron exhibits a region of relative stability; krypton exhibits behavior similar to argon though no region of stability was found for the range of separations used in the calculations. Finally, it is noted, from the relative energy of the topmost filled molecular orbital associated with boron (in an interstitial position), that activation of the boron does not require boron movement but can be accomplished by indirect transitions.

Aronowitz, S.

1983-01-01

302

The quantum mechanics of ion-enhanced field emission and how it influences microscale gas breakdown  

NASA Astrophysics Data System (ADS)

The presence of a positive gas ion can enhance cold electron field emission by deforming the potential barrier and increasing the tunneling probability of electrons—a process known as ion-enhanced field emission. In microscale gas discharges, ion-enhanced field emission produces additional emission from the cathode and effectively reduces the voltage required to breakdown a gaseous medium at the microscale (<10 ?m). In this work, we enhance classic field emission theory by determining the impact of a gaseous ion on electron tunneling and compute the effect of ion-enhanced field emission on the breakdown voltage. We reveal that the current density for ion-enhanced field emission retains the same scaling as vacuum cold field emission and that this leads to deviations from traditional breakdown theory at microscale dimensions.

Li, Yingjie; Go, David B.

2014-09-01

303

The quantum mechanics of ion-enhanced field emission and how it influences microscale gas breakdown  

SciTech Connect

The presence of a positive gas ion can enhance cold electron field emission by deforming the potential barrier and increasing the tunneling probability of electrons—a process known as ion-enhanced field emission. In microscale gas discharges, ion-enhanced field emission produces additional emission from the cathode and effectively reduces the voltage required to breakdown a gaseous medium at the microscale (<10??m). In this work, we enhance classic field emission theory by determining the impact of a gaseous ion on electron tunneling and compute the effect of ion-enhanced field emission on the breakdown voltage. We reveal that the current density for ion-enhanced field emission retains the same scaling as vacuum cold field emission and that this leads to deviations from traditional breakdown theory at microscale dimensions.

Li, Yingjie [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Go, David B., E-mail: dgo@nd.edu [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

2014-09-14

304

Ultracold atomic gas in non-Abelian gauge potentials: the quantum Hall effect supremacy  

Microsoft Academic Search

Nowadays it is experimentally feasible to create artificial, and in particular, non-Abelian gauge potentials for ultracold atoms trapped in optical lattices. Motivated by this fact, we investigate the fundamental properties of an ultracold Fermi gas in a non-Abelian U(2) gauge potential characterized by a constant Wilson loop. Under this specific condition, the energy spectrum exhibits a robust band structure with

N. Goldman; A. Kubasiak; P. Gaspard; M. Lewenstein

305

Modified Coulomb gas construction of quantum Hall states from nonunitary conformal field theories  

SciTech Connect

Some fractional quantum Hall states observed in experiments may be described by first-quantized wavefunctions with special clustering properties such as the Moore-Read Pfaffian for filling factor {nu}=5/2. This wavefunction has been constructed by constructing correlation functions of a two-dimensional conformal field theory (CFT) involving a free boson and a Majorana fermion. By considering other CFTs many other clustered states have been proposed as candidate fractional quantum Hall states under appropriate circumstances. It is believed that the underlying CFT should be unitary if one wants to describe an incompressible, i.e., gapped liquid state. We show that by changing the way one derives the wavefunction from its parent CFT it is possible to obtain an incompressible candidate state when starting from a nonunitary parent. The construction mimics a global change in parameters in the phase space of the electron system. We explicit our construction in the case of the so-called Gaffnian state (a state for filling factor 2/5) and also for the Haldane-Rezayi state (a spin-singlet state at filling 1/2). We note that there are obstructions along this path in the case of the permanent spin-singlet state of Read and Rezayi which can be characterized as a robust gapless state.

Milovanovic, M. V.; Vidanovic, I. [Institute of Physics, P.O. Box 68, 11080 Belgrade (Serbia); Jolicoeur, Th. [Laboratoire de Physique Theorique et Modeles Statistiques, Universite Paris-Sud, 91405 Orsay (France)

2009-10-15

306

Ionic conductivity in a quantum lattice gas model with three-particle interactions  

NASA Astrophysics Data System (ADS)

A system of mesoscopic ions with dominant three-particle interactions is modeled by a quantum lattice liquid on the planar kagomé lattice. The two-parameter Hamiltonian contains localized attractive triplet interactions as potential energy and nearest neighbor hopping-type terms as kinetic energy. The dynamic ionic conductivity ?(?) is theoretically investigated for ‘weak hopping’ via a quantum many-body perturbation expansion of the thermal (Matsubara) Green function (current-current correlation). A simple analytic continuation and mapping of the thermal Green function provide the temporal Fourier transform of the physical retarded Green function in the Kubo formula. Substituting pertinent exact solutions for static multi-particle correlations known from previous work, Arrhenius relations are revealed in zeroth-order approximation for the dc ionic conductivity ?dc along special trajectories in density-temperature space. The Arrhenius plots directly yield static activation energies along the latter loci. Experimental possibilities relating to ?dc are discussed in the presence of equilibrium aggregation. This article is part of ‘Lattice models and integrability’, a special issue of Journal of Physics A: Mathematical and Theoretical in honour of F Y Wu's 80th birthday.

Barry, J. H.; Muttalib, K. A.; Tanaka, T.

2012-12-01

307

High-In-content InGaAs quantum point contacts fabricated using focused ion beam system equipped with N2 gas field ion source  

NASA Astrophysics Data System (ADS)

Quantum point contacts (QPCs) in high-In-content InGaAs modulation-doped heterostructures fabricated using a focused ion beam (FIB) system equipped with a N2 gas field ion source (GFIS) are demonstrated. The minimum physical size of the fabricated QPCs in this study is ˜30 nm, which is smaller than the typical physical size of QPCs (>50 nm) obtained by electron beam lithography and etching techniques. In addition, the fabricated QPCs are characterized electrically at low temperatures with magnetic fields. Since some of them show conductance quantization behaviors, the results indicate that the GFIS-FIB process is promising for quantum device fabrication.

Akabori, Masashi; Hidaka, Shiro; Yamada, Syoji; Kozakai, Tomokazu; Matsuda, Osamu; Yasaka, Anto

2014-11-01

308

Ideal perturbed equilibria in tokamaks  

NASA Astrophysics Data System (ADS)

Tokamaks are almost axisymmetric, but highly sensitive to a small non-axisymmetric magnetic field in the level of 10-4 compared to the axisymmetric magnetic field. The small non-axisymmetries can significantly degrade or improve the tokamak plasma performance. Only recently has the importance of understanding the plasma response to the small non-axisymmetries been appreciated. Since the non-axisymmetric field is almost static on the time scales of the equilibrium relaxation, the basic and fundamental understanding can be achieved by studying perturbed equilibria. The previous approach for these perturbed plasma states was to superpose the external vacuum field onto the axisymmetric equilibrium field. This is not self-consistent since it ignores the perturbed plasma currents arising as the plasma response. Ideal Perturbed Equilibrium Code (IPEC), which has been developed to include the plasma response effects, is based on the DCON and the VACUUM stability codes. IPEC solves free-boundary ideal equilibria when axisymmetric equilibria are perturbed by small non-axisymmetric perturbations. The complications related to the external boundary conditions are efficiently handled using equivalent surface currents on a control surface instead of directly using the current sources in the external coils. As the internal boundary conditions, the ideal constraints are used at the resonant surfaces, which prevent the destruction of flux surfaces by magnetic islands. IPEC solutions include the perturbed field and the displacement throughout the entire region, but in particular, there are the two important pieces of information: (1) the singular currents that shield out the resonant field driving the islands, and (2) the variation in the field strength on the deformed magnetic surfaces, or equivalently along the perturbed magnetic field lines. IPEC can determine both the strength of the resonant field that is trying to open magnetic islands and the variation in the field strength, which is essential for the evaluation of non-ambipolar transport. These IPEC solutions have been tested in cylindrical force-free limit, and also benchmarked against a perturbed equilibrium code for stellarators and a non-linear MHD code. Applications of IPEC are: (1) The opening of a magnetic island can stop the plasma rotation in a tokamak. This is called locking, which must be avoided for successful tokamak operations. The resonant field that tends to drive islands, when calculated by IPEC, gave a successful explanation for recent NSTX and DIII-D tokamak locking experiments, which were inconsistent when the plasma response was ignored. (2) IPEC results were also applied to study the parametric dependency of locking, based on data of three US major tokamaks, NSTX, DIII-D and C-MOD. This yielded different expectations and extrapolations to ITER, which will test the first burning plasma in a worldwide collaboration. (3) A non-axisymmetric variation in the field strength can strongly enhance rotational damping through non-ambipolar transport, or equivalently the Neoclassical Toroidal Viscosity (NTV). However, the previous approach using only the external field coupled with an asymptotic NTV calculations showed inconsistency between theory and experiment. In order to resolve the inconsistency, a new analytic treatment of NTV was developed to include important physics effects such as the particle precession and bounce-harmonic resonances. When the generalized NTV theory is coupled with the variation in the field strength calculated by IPEC, far better consistency is found between theory and experiment. Non-axisymmetric magnetic perturbations can be used for plasma control. To do the control, both the resonant field and the NTV must be determined to avoid degrading the plasma performance. A new control scheme is presented based on the coupling between the resonant field driving islands and the external field. The proposed scheme can determine dominant external field to which various locations in the plasma are most sensitive. The similarity of the dominant external

Park, Jong-Kyu

309

C-C stretching Raman spectra and stabilities of hydrocarbon molecules in natural gas hydrates: a quantum chemical study.  

PubMed

The presence of specific hydrocarbon gas molecules in various types of water cavities in natural gas hydrates (NGHs) are governed by the relative stabilities of these encapsulated guest molecule-water cavity combinations. Using molecular quantum chemical dispersion-corrected hybrid density functional computations, the interaction (?E(host--guest)) and cohesive energies (?E(coh)), enthalpies, and Gibbs free energies for the complexes of host water cages and hydrocarbon guest molecules are calculated at the ?B97X-D/6-311++G(2d,2p) level of theory. The zero-point energy effect of ?E(host-guest) and ?E(coh) is found to be quite substantial. The energetically optimal host-guest combinations for seven hydrocarbon gas molecules (CH4, C2H6, C3H6, C3H8, C4H8, i-C4H10, and n-C4H10) and various water cavities (D, ID, T, P, H, and I) in NGHs are found to be CH4@D, C2H6@T, C3H6@T, C3H8@T, C4H8@T/P/H, i-C4H10@H, and n-C4H10@H, as the largest cohesive energy magnitudes will be obtained with these host-guest combinations. The stabilities of various water cavities enclosing hydrocarbon molecules are evaluated from the computed cohesive Gibbs free energies: CH4 prefers to be trapped in a ID cage; C2H6 prefer T cages; C3H6 and C3H8 prefer T and H cages; C4H8 and i-C4H10 prefer H cages; and n-C4H10 prefer I cages. The vibrational frequencies and Raman intensities of the C-C stretching vibrational modes for these seven hydrocarbon molecules enclosed in each water cavity are computed. A blue shift results after the guest molecule is trapped from gas phase into various water cages due to the host-guest interactions between the water cage and hydrocarbon molecule. The frequency shifts to the red as the radius of water cages increases. The model calculations support the view that C-C stretching vibrations of hydrocarbon molecules in the water cavities can be used as a tool to identify the types of crystal phases and guest molecules in NGHs. PMID:25406092

Liu, Yuan; Ojamäe, Lars

2014-12-11

310

Half-quantum vortex molecules in a binary dipolar Bose gas.  

PubMed

We study the ground state phases of a rotating two-component, or binary, Bose-Einstein condensate, wherein one component possesses a large permanent magnetic dipole moment. A variety of nontrivial phases emerge in this system, including a half-quantum vortex (HQV) chain phase and a HQV molecule phase, where HQVs bind at short distances. We attribute these phases to the development of a minimum in the HQV interaction potential, which emerges without coherent coupling or attractive interactions between the components. Thus, we show that the presence of dipolar interactions in this system provides a unique mechanism for the formation of HQV molecules and results in a rich ground state phase diagram. PMID:25361261

Shirley, Wilbur E; Anderson, Brandon M; Clark, Charles W; Wilson, Ryan M

2014-10-17

311

Half-Quantum Vortex Molecules in a Binary Dipolar Bose Gas  

NASA Astrophysics Data System (ADS)

We study the ground state phases of a rotating two-component, or binary, Bose-Einstein condensate, wherein one component possesses a large permanent magnetic dipole moment. A variety of nontrivial phases emerge in this system, including a half-quantum vortex (HQV) chain phase and a HQV molecule phase, where HQVs bind at short distances. We attribute these phases to the development of a minimum in the HQV interaction potential, which emerges without coherent coupling or attractive interactions between the components. Thus, we show that the presence of dipolar interactions in this system provides a unique mechanism for the formation of HQV molecules and results in a rich ground state phase diagram.

Shirley, Wilbur E.; Anderson, Brandon M.; Clark, Charles W.; Wilson, Ryan M.

2014-10-01

312

Variational mixed quantum/semiclassical simulation of dihalogen guest and rare-gas solid host dynamics.  

PubMed

A variational mixed quantum-semiclassical theory for the internal nuclear dynamics of a small molecule and the induced small-amplitude coherent motion of a low-temperature host medium is developed, tested, and used to simulate the temporal evolution of nonstationary states of the internal molecular and surrounding medium degrees of freedom. In this theory, termed the Fixed Vibrational Basis/Gaussian Bath (FVB/GB) method, the system is treated fully quantum mechanically while Gaussian wave packets are used for the bath degrees of freedom. An approximate time-dependent wave function of the entire model is obtained instead of just a reduced system density matrix, so the theory enables the analysis of the entangled system and bath dynamics that ensues following initial displacement of the internal-molecular (system) coordinate from its equilibrium position. The norm- and energy-conserving properties of the propagation of our trial wave function are natural consequences of the Dirac-Frenkel-McLachlan variational principle. The variational approach also stabilizes the time evolution in comparison to the same ansatz propagated under a previously employed locally quadratic approximation to the bath potential and system-bath interaction terms in the bath-parameter equations of motion. Dynamics calculations are carried out for molecular iodine in a 2D krypton lattice that reveal both the time-course of vibrational decoherence and the details of host-atom motion accompanying energy dissipation and dephasing. This work sets the stage for the comprehensive simulation of ultrafast time-resolved optical experiments on small molecules in low-temperature solids. PMID:25053307

Cheng, Xiaolu; Cina, Jeffrey A

2014-07-21

313

Variational mixed quantum/semiclassical simulation of dihalogen guest and rare-gas solid host dynamics  

NASA Astrophysics Data System (ADS)

A variational mixed quantum-semiclassical theory for the internal nuclear dynamics of a small molecule and the induced small-amplitude coherent motion of a low-temperature host medium is developed, tested, and used to simulate the temporal evolution of nonstationary states of the internal molecular and surrounding medium degrees of freedom. In this theory, termed the Fixed Vibrational Basis/Gaussian Bath (FVB/GB) method, the system is treated fully quantum mechanically while Gaussian wave packets are used for the bath degrees of freedom. An approximate time-dependent wave function of the entire model is obtained instead of just a reduced system density matrix, so the theory enables the analysis of the entangled system and bath dynamics that ensues following initial displacement of the internal-molecular (system) coordinate from its equilibrium position. The norm- and energy-conserving properties of the propagation of our trial wave function are natural consequences of the Dirac-Frenkel-McLachlan variational principle. The variational approach also stabilizes the time evolution in comparison to the same ansatz propagated under a previously employed locally quadratic approximation to the bath potential and system-bath interaction terms in the bath-parameter equations of motion. Dynamics calculations are carried out for molecular iodine in a 2D krypton lattice that reveal both the time-course of vibrational decoherence and the details of host-atom motion accompanying energy dissipation and dephasing. This work sets the stage for the comprehensive simulation of ultrafast time-resolved optical experiments on small molecules in low-temperature solids.

Cheng, Xiaolu; Cina, Jeffrey A.

2014-07-01

314

Quantum corrections to the semiclassical Hartree-Fock theory of a harmonically trapped Bose gas  

NASA Astrophysics Data System (ADS)

Using the phase-space expansion of the thermodynamical distribution functions we provide a general and systematic method for including effects beyond the local-density approximation to the semiclassical Hartree-Fock theories. We illustrate the method by applying it to the case of a strictly two-dimensional, harmonically trapped Bose gas. Thereby, we address the ambiguous prediction of the Hartree-Fock approximation, namely, whether a fixed number of trapped atoms undergoes Bose-Einstein condensation or not. We also investigate the dependence of the critical temperature on the interaction strength.

Schumayer, D.; Cormack, S.; van Zyl, B. P.; Farry, J.; Collin, A.; Zaremba, E.; Hutchinson, D. A. W.

2012-08-01

315

Quantum friction  

E-print Network

The Brownian motion of a light quantum particle in a heavy classical gas is theoretically described and a new expression for the friction coefficient is obtained for arbitrary temperature. At zero temperature it equals to the de Broglie momentum of the mean free path divided by the mean free path. Alternatively, the corresponding mobility of the quantum particle in the classical gas is equal to the square of the mean free path divided by the Planck constant. The Brownian motion of a quantum particle in a quantum environment is also discussed.

R. Tsekov

2012-12-05

316

Thermodynamic model of ideal magnetostriction  

NASA Astrophysics Data System (ADS)

A self-consistent model of ideal magnetostriction is presented on a thermodynamic basis for the coupling between magnetostriction of ferromagnets and the behaviour of magnetization or induction curves (an anhysteretic approach is developed). The model is based on a rigorous adherence to the energy conservation law which is written in a characteristic differential form. The author employed an additional assumption concerning the presence of saturation effects to obtain a magnetic equation of state for some ferromagnetic materials. The coefficient ? is introduced for the coupling between magnetic and mechanical processes. A mechanical equation of state (the expression for magnetostriction) is derived using the thermodynamic Maxwell reciprocity relations. The separation of strains into magnetic and purely mechanical parts comes about as a logical consequence of the self-consistent approach. The conclusion is made that the well-known Villari and Joule effects can be treated as a coupling between magnetic and mechanical processes within the framework of an invariant coupling coefficient. The behaviour of the magnetostrictional modulus of elasticity for ferromagnetic materials is discussed and, as is shown, it takes on negative values within a certain range of the magnetic field and mechanical stress. The last Section of the paper concentrates briefly on the strength problems. Modeling results are in a good agreement with experiments.

Agayan, Vakhtang

1996-11-01

317

Meet irreducible ideals in direct limit algebras  

Microsoft Academic Search

We study the meet irreducible ideals in certain direct limit algebras, namely\\u000athe strongly maximal triangular subalgebras of AF C*-algebras. These ideals\\u000ahave a description in terms of the coordinates, or spectrum, that is a natural\\u000aextension of one description of meet irreducible ideals in the upper triangular\\u000amatrices. Additional information is available if the limit algebra is an\\u000aanalytic

Allan P. Donsig; Alan Hopenwasser; Timothy D. Hudson; Michael P. Lamoureux; Baruch Solel

1997-01-01

318

Excitonic Energy Shifts in CdMnTe/CdMgTe Quantum Wells under Resonant Excitation in Presence of 2D Carrier Gas  

NASA Astrophysics Data System (ADS)

Systematic studies of amplitude and energy changes of excitonic lines in a strong excitation regime were carried out by a pump-probe method. The series of samples containing quantum wells with well width from 80 Å to 140 Å was investigated. One 80 Å sample was n-doped with iodine, the rest of the quantum wells were intentionally undoped but contained a 2D gas of free holes. Its density could be varied by changing an intensity of additional illumination. The resonant creation of high population of e1hh1 excitons causes the energetic blue shift of the same due to interactions between excitons. The blue shift did not depend on the concentration of 2D gas of carriers whereas it did depend on the power of excitation beam. Model calculations of absorption show qualitative agreement with the experimental data.

Trajnerowicz, A.; Golnik, A.; Kossacki, P.; Bardyszewski, W.; Wiater, M.; Karczewski, G.; Wojtowicz, T.

2008-11-01

319

Initialization and readout of spin chains for quantum information transport  

E-print Network

Linear chains of spins acting as quantum wires are a promising approach for achieving scalable quantum information processors. Nuclear spins in apatite crystals provide an ideal test bed for the experimental study of quantum ...

Kaur, Gurneet

320

Suspended graphene films and their Casimir interaction with ideal conductor  

E-print Network

We adopt the Dirac model for graphene and calculate the Casimir interaction energy between a plane suspended graphene sample and a parallel plane ideal conductor. We employ both the Quantum Field Theory (QFT) approach, and the Lifshitz formula generalizations. The first approach turns out to be the leading order in the coupling constant of the second one. The Casimir interaction for this system appears to be rather weak but experimentally measurable. It exhibits a strong dependence on the mass of the quasi-particles in graphene.

I. V. Fialkovsky

2009-10-10

321

Gas Phase Photoacoustic Spectroscopy in the long-wave IR using Quartz Tuning Forks and Amplitude Modulated Quantum Cascade Lasers  

SciTech Connect

A paper to accompany a 20 minute talk about the progress of a DARPA funded project called LPAS. ABSTRACT: We demonstrate the performance of a novel long-wave infrared photoacoustic laser absorbance spectrometer for gas-phase species using an amplitude modulated (AM) quantum cascade (QC) laser and a quartz tuning fork microphone. Photoacoustic signal was generated by focusing the output of a Fabry-Perot QC laser operating at 8.41 micron between the legs of a quartz tuning fork which served as a transducer for the transient acoustic pressure wave. The QC laser was modulated at the resonant frequency of the tuning fork (32.8 kHz). This sensor was calibrated using the infrared absorber Freon-134a by performing a simultanious absorption measurement using a 35 cm absorption cell. The NEAS of this instrument was determined to be 2 x 10^-8 W cm^-1 /Hz^1/2 and the fundamental sensitivity of this technique is limited by the noise floor of the tuning fork itself.

Wojcik, Michael D.; Phillips, Mark C.; Cannon, Bret D.

2006-12-31

322

[A trace methane gas sensor using mid-infrared quantum cascaded laser at 7.5 microm].  

PubMed

Presented is a compact instrument developed for in situ high-stable and sensitive continuous measurement of trace gases in air, with results shown for ambient methane (CH4) concentration accurate, real-time and in-situ. This instrument takes advantage of recent technology in thermoelectrically cooling (TEC) pulsed Fabry-Perot (FP) quantum cascaded laser (QCL) driving in a pulse mode operating at 7.5 microm ambient temperature to cover a fundamental spectral absorption band near v4 of CH4. A high quality Liquid Nitrogen (LN) cooled Mercury Cadmium Telluride (HgCdTe) mid-infrared (MIR) detector is used along with a total reflection coated gold ellipsoid mirror offering 20 cm single pass optical absorption in an open-path cell to achieve stability of 5.2 x 10(-3) under experimental condition of 200 micromol x mol(-1) measured ambient CH4. The instrument integrated software via time discriminating electronics technology to control QCL provides continuous quantitative trace gas measurements without calibration. The results show that the instrument can be applied to field measurements of gases of environmental concern. Additional, operator could substitute a QCL operating at a different wavelength to measure other gases. PMID:23387197

Chen, Chen; Dang, Jing-Min; Huang, Jian-Qiang; Yang, Yue; Wang, Yi-Ding

2012-11-01

323

[A trace gas sensor using mid-infrared quantum cascaded laser at 4.8 microm to detect carbon monoxide].  

PubMed

Presented in the present paper is a compact instrument developed for rapid, sensitive and continuous monitoring of trace gases in air, with results shown for carbon monoxide concentration. This instrument takes advantage of recent technology in mid-infrared quantum cascaded laser (QCL) operating at 4.8 microm and mercury cadmium telluride (HgCdTe) mid-infrared (MIR) detector, combing MIR multipass herriott cell with 76 m absorption path length to obtain low detection sensitivity down to 50 nmol x mol(-1) level in 4 s acquisition time. Meanwhile, in order to eliminate the instability induced by electrically modulated light source and effectively improve detection limit of the instrument, an optical structure with dual channel path was designed which is based on differential optical absorption spectroscopy method. The experimental results show that the instrument integrated with gas concentration inversion algorithm can be applied to in-situ measurements of trace gases without calibration. Additionally, operator could substitute a QCL operating at a different wavelength to measure other gases. PMID:25208424

Chen, Chen; Wang, Biao; Li, Chun-Guang; Li, Jian; Wang, Yi-Ding

2014-03-01

324

Demonstrating the Gas Laws.  

ERIC Educational Resources Information Center

Presents a complete computer program demonstrating the relationship between volume/pressure for Boyle's Law, volume/temperature for Charles' Law, and volume/moles of gas for Avagadro's Law. The programing reinforces students' application of gas laws and equates a simulated moving piston to theoretical values derived using the ideal gas law.…

Holko, David A.

1982-01-01

325

Towards enhancing two-dimensional electron gas quantum confinement effects in perovskite oxide heterostructures  

NASA Astrophysics Data System (ADS)

We explore the possibility of achieving highly confined two-dimensional electron gas (2DEG) within one single atomic layer through a comprehensive comparison study on three prototypical perovskite heterostructures, LaAlO3/ATiO3 (A = Ca, Sr, and Ba), using first-principles electronic structure calculations. We predict that the heterostructure LaAlO3/BaTiO3 has a highly confined 2DEG within a single atomic layer of the substrate BaTiO3, and exhibits relatively higher interfacial charge carrier density and larger magnetic moments than the well-known LaAlO3/SrTiO3 system. The long Ti-O bond length in the ab-plane of the LaAlO3/BaTiO3 heterostructure is responsible for the superior charge confinement. We propose BaTiO3 as an exceptional substrate material for 2DEG systems with potentially superior properties.

Nazir, Safdar; Behtash, Maziar; Yang, Kesong

2015-03-01

326

Maintaining ideal body weight counseling sessions  

SciTech Connect

The purpose of this program is to provide employees with the motivation, knowledge and skills necessary to maintain ideal body weight throughout life. The target audience for this program, which is conducted in an industrial setting, is the employee 40 years of age or younger who is at or near his/her ideal body weight.

Brammer, S.H.

1980-10-09

327

New ideal concentrators for distant radiation sources  

Microsoft Academic Search

A new method for determining the shape of both ideal and nearly ideal concentrators for distant point sources of radiation is developed. The procedure is applied to the design of an extreme asymmetrical concentrator which has applications in solar thermal collection. (SPH)

D. R. Mills; J. E. Giutronich

1979-01-01

328

Generalized Reduction to Compute Toric Ideals  

Microsoft Academic Search

Toric ideals have many applications including solving integer programs. Several algorithms for computing the toric ideal of\\u000a an integer matrix are available in the literature. Since it is an NP hard problem the present approaches can only solve relatively\\u000a small problems. We propose a new approach which improves upon a well known saturation technique.

Deepanjan Kesh; Shashank K. Mehta

2009-01-01

329

Gröbner bases of ideals invariant under endomorphisms  

Microsoft Academic Search

We introduce the notion of Grobner S-basis of an ideal of the free associative algebra Kh Xi over a field K invariant under the action of a semigroup S of endomorphisms of the algebra. We calculate the Grobner S-bases of the ideal corresponding to the universal enveloping algebra of the free nilpotent of class 2 Lie algebra and of the

Vesselin Drensky; Roberto La Scala

2006-01-01

330

The mass and energy of a vapor bubble in a turbulent ideal fluid  

E-print Network

The mass of a bubble in a fluid can be taken as the mass of the vapor in it. The self-energy of the bubble is defined as the work performed against the pressure of the fluid in order to create the bubble. Taking the vapor to be an ideal gas the relationship between the self-energy, the mass of the bubble and the speed of the perturbation wave in a turbulent ideal fluid can be obtained.

Valery P. Dmitriyev

2006-02-22

331

Converging cylindrical shocks in ideal magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=sqrt{? _0/p_0} I/(2 ? ) where I is the current, ?0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ? R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then slows the shock Mach number growth producing a maximum followed by monotonic reduction towards magnetosonic conditions, even as the shock accelerates toward the axis. A parameter space of initial shock Mach number at a given radius is explored and the implications of the present results for inertial confinement fusion are discussed.

Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

2014-09-01

332

Converging cylindrical shocks in ideal magnetohydrodynamics  

SciTech Connect

We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=?(?{sub 0}/p{sub 0}) I/(2 ?) where I is the current, ?{sub 0} is the permeability, and p{sub 0} is the pressure ahead of the shock. For shocks initiated at r ? R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then slows the shock Mach number growth producing a maximum followed by monotonic reduction towards magnetosonic conditions, even as the shock accelerates toward the axis. A parameter space of initial shock Mach number at a given radius is explored and the implications of the present results for inertial confinement fusion are discussed.

Pullin, D. I. [Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States); Mostert, W.; Wheatley, V. [School of Mechanical and Mining Engineering, University of Queensland, Queensland 4072 (Australia); Samtaney, R. [Mechanical Engineering, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

2014-09-15

333

Quantum memory Quantum memory  

NASA Astrophysics Data System (ADS)

Interaction of quantum radiation with multi-particle ensembles has sparked off intense research efforts during the past decade. Emblematic of this field is the quantum memory scheme, where a quantum state of light is mapped onto an ensemble of atoms and then recovered in its original shape. While opening new access to the basics of light-atom interaction, quantum memory also appears as a key element for information processing applications, such as linear optics quantum computation and long-distance quantum communication via quantum repeaters. Not surprisingly, it is far from trivial to practically recover a stored quantum state of light and, although impressive progress has already been accomplished, researchers are still struggling to reach this ambitious objective. This special issue provides an account of the state-of-the-art in a fast-moving research area that makes physicists, engineers and chemists work together at the forefront of their discipline, involving quantum fields and atoms in different media, magnetic resonance techniques and material science. Various strategies have been considered to store and retrieve quantum light. The explored designs belong to three main—while still overlapping—classes. In architectures derived from photon echo, information is mapped over the spectral components of inhomogeneously broadened absorption bands, such as those encountered in rare earth ion doped crystals and atomic gases in external gradient magnetic field. Protocols based on electromagnetic induced transparency also rely on resonant excitation and are ideally suited to the homogeneous absorption lines offered by laser cooled atomic clouds or ion Coulomb crystals. Finally off-resonance approaches are illustrated by Faraday and Raman processes. Coupling with an optical cavity may enhance the storage process, even for negligibly small atom number. Multiple scattering is also proposed as a way to enlarge the quantum interaction distance of light with matter. The quest for higher efficiency, better fidelity, broader bandwidth, multimode capacity and longer storage lifetime is pursued in all those approaches, as shown in this special issue. The improvement of quantum memory operation specifically requires in-depth study and control of numerous physical processes leading to atomic decoherence. The present issue reflects the development of rare earth ion doped matrices offering long lifetime superposition states, either as bulk crystals or as optical waveguides. The need for quantum sources and high efficiency detectors at the single photon level is also illustrated. Several papers address the networking of quantum memories either in long-haul cryptography or in the prospect of quantum processing. In this context, much attention has been paid recently to interfacing quantum light with superconducting qubits and with nitrogen-vacancy centers in diamond. Finally, the quantum interfacing of light with matter raises questions on entanglement. The last two papers are devoted to the generation of entanglement by dissipative processes. It is shown that long lifetime entanglement may be built in this way. We hope this special issue will help readers to become familiar with the exciting field of ensemble-based quantum memories and will stimulate them to bring deeper insights and new ideas to this area.

Le Gouët, Jean-Louis; Moiseev, Sergey

2012-06-01

334

The structure and conformations of piracetam (2-oxo-1-pyrrolidineacetamide): Gas-phase electron diffraction and quantum chemical calculations  

NASA Astrophysics Data System (ADS)

The geometric structure of piracetam was studied by quantum chemical calculations (DFT and ab initio), gas electron diffraction (GED), and FTIR spectroscopy. Two stable mirror symmetric isomers of piracetam were found. The conformation of pyrrolidine ring is an envelope in which the C4 atom deviates from the ring plane, the angle between the planes (C3 sbnd C4 sbnd C5) and (C2 sbnd C3 sbnd C5) is 154.1°. The direction of the deviation is the same as that of the side acetamide group. The piracetam molecule is stabilized in the gas phase by an intramolecular hydrogen bond between the N9H 2 group and the oxygen O6, bonded to C2. The principal structural parameters ( re, Å and ?e, degrees; uncertainties are 3 ?LS values) were found to be: r(?3 sbnd ?4) = 1.533(1), r(C4 sbnd C5) = 1.540(1), r(N1 sbnd C5) = 1.456(1), r(C2 sbnd C3) = 1.520(1), r(N1 sbnd C7) = 1.452(1), r(C7 sbnd C8) = 1.537(1), r(N1 sbnd C2) = 1.365(2), r(C8 sbnd N9) = 1.360(2), r(C2 dbnd O6) = 1.229(1), r(C8 dbnd O10) = 1.221(1), ?C2 sbnd N1 sbnd C5 = 113.4(6), ?N1 sbnd C2 sbnd C3 = 106.9(6), ?N1 sbnd C7 sbnd C8 = 111.9(6), ?C7 sbnd C8 sbnd N9 = 112.5(6), ?N1 sbnd C2 sbnd O6 = 123.0(4), ?C3 sbnd N1 sbnd C7 = 120.4(4), ?C7 sbnd C8 sbnd O10 = 120.2(4), ?C5 sbnd N1 sbnd C2 sbnd O6 = 170(6), ?C3 sbnd C2 sbnd N1 sbnd C7 = 178(6), ?C2 sbnd N1 sbnd C7 sbnd C8 = 84.2, ?N1 sbnd C7 sbnd C8 sbnd O10 = 111.9.

Ksenafontov, Denis N.; Moiseeva, Natalia F.; Khristenko, Lyudmila V.; Karasev, Nikolai M.; Shishkov, Igor F.; Vilkov, Lev V.

2010-12-01

335

Mitosis, diffusible crosslinkers, and the ideal gas law.  

PubMed

During mitosis, molecular motors hydrolyze ATP to generate sliding forces between adjacent microtubules and form the bipolar mitotic spindle. Lansky et al. now show that the diffusible microtubule crosslinker Ase1p can generate sliding forces between adjacent microtubules, and it does so without ATP hydrolysis. PMID:25768899

Odde, David J

2015-03-12

336

Primary Ideals with Good Fiber Cone  

Microsoft Academic Search

Let (R, 𝔪) be a Cohen–Macaulay local ring of dimension d > 0. I an 𝔪-primary ideal and K an ideal containing I. Let a1,…, ad?1 ? I, ad ? K be a Rees-superficial sequence for I and K, we set J = (a1,…, ad?1). In this article, we consider the classes of these 𝔪-primary ideals I such that KI ? (J, ad) = JK + adI and , or, for some

Guangjun Zhu

2011-01-01

337

Monomization of power Ideals and parking functions  

E-print Network

A zonotopal algebra is the quotient of a polynomial ring by an ideal generated by powers of linear forms which are derived from a zonotope, or dually it's hyperplane arrangement. In the case that the hyperplane arrangement ...

Desjardins, Craig J. (Craig Jeffrey)

2010-01-01

338

Ideal fluid and acceleration of the universe  

E-print Network

The solution of the dark energy problem in models without scalars is presented. It is shown that a late-time accelerating cosmology may be generated by an ideal fluid with some implicit equation of state.

O. Gorbunova

2006-08-07

339

Stepwise Development from Ideal Specifications Graeme Smith  

E-print Network

Stepwise Development from Ideal Specifications Graeme Smith Software Verification Research Centre University of Queensland, Australia smith@svrc.uq.edu.au Abstract The stepwise development of a program using

Smith, Graeme

340

A Saturation Algorithm for Homogeneous Binomial Ideals  

E-print Network

A Saturation Algorithm for Homogeneous Binomial Ideals Deepanjan Kesh and Shashank K Mehta Indian at computation in smaller rings is by Kesh and Mehta [7] which also requires the computation of one Gr

Mehta, Shashank K

341

Quantum benchmarking with realistic states of light  

E-print Network

The goal of quantum benchmarking is to certify that imperfect quantum communication devices (e.g., quantum channels, quantum memories, quantum key distribution systems) can still be used for meaningful quantum communication. However, the test states used in quantum benchmarking experiments may be imperfect as well. Many quantum benchmarks are only valid for states which match some ideal form, such as pure states or Gaussian states. We outline how to perform quantum benchmarking using arbitrary states of light. We demonstrate these results using real data taken from a continuous-variable quantum memory.

Nathan Killoran; Mahdi Hosseini; Ben C. Buchler; Ping Koy Lam; Norbert Lütkenhaus

2012-08-27

342

Ideal shrinking and expansion of discrete sequences  

NASA Technical Reports Server (NTRS)

Ideal methods are described for shrinking or expanding a discrete sequence, image, or image sequence. The methods are ideal in the sense that they preserve the frequency spectrum of the input up to the Nyquist limit of the input or output, whichever is smaller. Fast implementations that make use of the discrete Fourier transform or the discrete Hartley transform are described. The techniques lead to a new multiresolution image pyramid.

Watson, Andrew B.

1986-01-01

343

The Statistical Mechanics of Ideal MHD Turbulence  

NASA Technical Reports Server (NTRS)

Turbulence is a universal, nonlinear phenomenon found in all energetic fluid and plasma motion. In particular. understanding magneto hydrodynamic (MHD) turbulence and incorporating its effects in the computation and prediction of the flow of ionized gases in space, for example, are great challenges that must be met if such computations and predictions are to be meaningful. Although a general solution to the "problem of turbulence" does not exist in closed form, numerical integrations allow us to explore the phase space of solutions for both ideal and dissipative flows. For homogeneous, incompressible turbulence, Fourier methods are appropriate, and phase space is defined by the Fourier coefficients of the physical fields. In the case of ideal MHD flows, a fairly robust statistical mechanics has been developed, in which the symmetry and ergodic properties of phase space is understood. A discussion of these properties will illuminate our principal discovery: Coherent structure and randomness co-exist in ideal MHD turbulence. For dissipative flows, as opposed to ideal flows, progress beyond the dimensional analysis of Kolmogorov has been difficult. Here, some possible future directions that draw on the ideal results will also be discussed. Our conclusion will be that while ideal turbulence is now well understood, real turbulence still presents great challenges.

Shebalin, John V.

2003-01-01

344

Guiding center equations for ideal magnetohydrodynamic modes  

SciTech Connect

Guiding center simulations are routinely used for the discovery of mode-particle resonances in tokamaks, for both resistive and ideal instabilities and to find modifications of particle distributions caused by a given spectrum of modes, including large scale avalanches during events with a number of large amplitude modes. One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through {delta}B-vector={nabla} Multiplication-Sign ({xi}-vector Multiplication-Sign B-vector), however, perturbs the magnetic topology, introducing extraneous magnetic islands in the field. A proper treatment of an ideal perturbation involves a full Lagrangian displacement of the field due to the perturbation and conserves magnetic topology as it should. In order to examine the effect of ideal magnetohydrodynamic modes on particle trajectories, the guiding center equations should include a correct Lagrangian treatment. Guiding center equations for an ideal displacement {xi}-vector are derived which preserve the magnetic topology and are used to examine mode particle resonances in toroidal confinement devices. These simulations are compared to others which are identical in all respects except that they use the linear representation for the field. Unlike the case for the magnetic field, the use of the linear field perturbation in the guiding center equations does not result in extraneous mode particle resonances.

White, R. B. [Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States)

2013-04-15

345

Guiding Center Equations for Ideal Magnetohydrodynamic Modes  

SciTech Connect

Guiding center simulations are routinely used for the discovery of mode-particle resonances in tokamaks, for both resistive and ideal instabilities and to find modifications of particle distributions caused by a given spectrum of modes, including large scale avalanches during events with a number of large amplitude modes. One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through ?~B = ? X (? X B) however perturbs the magnetic topology, introducing extraneous magnetic islands in the field. A proper treatment of an ideal perturbation involves a full Lagrangian displacement of the field due to the perturbation and conserves magnetic topology as it should. In order to examine the effect of ideal magnetohydrodynamic modes on particle trajectories the guiding center equations should include a correct Lagrangian treatment. Guiding center equations for an ideal displacement ? are derived which perserve the magnetic topology and are used to examine mode particle resonances in toroidal confinement devices. These simulations are compared to others which are identical in all respects except that they use the linear representation for the field. Unlike the case for the magnetic field, the use of the linear field perturbation in the guiding center equations does not result in extraneous mode particle resonances.

Roscoe B. White

2013-02-21

346

Computational Methods for Simulating Quantum Computers  

E-print Network

This review gives a survey of numerical algorithms and software to simulate quantum computers.It covers the basic concepts of quantum computation and quantum algorithms and includes a few examples that illustrate the use of simulation software for ideal and physical models of quantum computers.

H. De Raedt; K. Michielsen

2004-08-02

347

Transport properties of the two-dimensional electron gas in wide AlP quantum wells including temperature and correlation effects  

NASA Astrophysics Data System (ADS)

We investigate the mobility, magnetoresistance and scattering time of a quasi-two-dimensional electron gas in a GaP/AlP/GaP quantum well of width L>Lc=45.7 Å at zero and finite temperatures. We consider the interface-roughness and impurity scattering, and study the dependence of the mobility, the resistance and scattering time ratio on the carrier density and quantum well width for different values of the impurity position and temperature using different approximations for the local-field correction. In the case of zero temperature and Hubbard local-field correction our results reduce to those of Gold and Marty (Phys. Rev. B. 76 (2007) 165309) [3]. We also study the correlation and multiple scattering effects on the total mobility and the critical density for a metal-insulator transition.

Tai, Vo Van; Khanh, Nguyen Quoc

2015-03-01

348

Quantum simulation of energy transport with embedded Rydberg aggregates  

E-print Network

We show that an array of ultracold Rydberg atoms embedded in a laser driven background gas can serve as an aggregate for simulating exciton dynamics and energy transport with a controlled environment. Spatial disorder and decoherence introduced by the interaction with the background gas atoms can be controlled by the laser parameters. This allows for an almost ideal realization of a Haken-Reineker-Strobl type model for energy transport. Physics can be monitored using the same mechanism that provides control over the environment. The degree of decoherence is traced back to information gained on the excitation location through the monitoring, turning the setup into an experimentally accessible model system for studying the effects of quantum measurements on the dynamics of a many-body quantum system.

Schönleber, D W; Genkin, M; Whitlock, S; Wüster, S

2015-01-01

349

Quantum Hairs and Entropy of Quantum Isolated Horizon from Chern-Simons Theory  

E-print Network

We articulate the fact that the loop quantum gravity description of the quantum macrostates of black hole horizons, modeled as Quantum Isolated Horizons (QIHs), is completely characterized in terms of two independent integer-valued `quantum hairs', viz,. the coupling constant $(k)$ of the quantum $SU(2)$ Chern-Simons theory describing QIH dynamics, and the number of punctures $(N)$ produced by the bulk spin network edges piercing the isolated horizon (which act as pointlike sources for the Chern- Simons fields). We demonstrate that the microcanonical entropy of macroscopic (both parameters assuming very large values) QIHs can be obtained directly from the microstates of this Chern-Simons theory, using standard statistical mechanical methods, without having to additionally postulate the horizon as an ideal gas of punctures, or incorporate any additional classical or semi-classical input from general relativity vis-a-vis the functional dependence of the IH mass on its area, or indeed, without having to restrict to any special class of spins. Requiring the validity of the Bekenstein-Hawking area law relates these two parameters (as an equilibrium `equation of state') and consequently allows the Barbero-Immirzi parameter to take any real and positive value depending on the value of $k/N$. The logarithmic correction to the area law obtained a decade ago by R. Kaul and one of us (P.M.), ensues straightforwardly, with precisely the coefficient -3/2, making it a signature of the loop quantum gravity approach to black hole entropy.

Abhishek Majhi; Parthasarathi Majumdar

2014-08-15

350

High power, widely tunable, mode-hop free, continuous wave external cavity quantum cascade laser for multi-species trace gas detection  

NASA Astrophysics Data System (ADS)

We present a high power, widely tunable, continuous wave external cavity quantum cascade laser designed for infrared vibrational spectroscopy of molecules exhibiting broadband and single line absorption features. The laser source exhibits single mode operation with a tunability up to 303 cm-1 (˜24% of the center wavelength) at 8 ?m, with a maximum optical output power of 200 mW. In combination with off-axis integrated output spectroscopy, trace-gas detection of broadband absorption gases such as acetone was performed and a noise equivalent absorption sensitivity of 3.7 × 10-8 cm-1 Hz-1/2 was obtained.

Centeno, R.; Marchenko, D.; Mandon, J.; Cristescu, S. M.; Wulterkens, G.; Harren, F. J. M.

2014-12-01

351

Genetic Algorithms and Quantum Computation  

Microsoft Academic Search

Recently, researchers have applied genetic algorithms (GAs) to address some problems in quantum computation. Also, there has been some works in the designing of genetic algorithms based on quantum theoretical concepts and techniques. The so called Quantum Evolutionary Programming has two major sub-areas: Quantum Inspired Genetic Algorithms (QIGAs) and Quantum Genetic Algorithms (QGAs). The former adopts qubit chromosomes as representations

Gilson A. Giraldi; Renato Portugal; Ricardo N. Thess

2004-01-01

352

Resonant Fluorescence from Quantum Dot Molecular Excitonic Transitions  

Microsoft Academic Search

Quantum dot molecules formed by two vertically stacked quantum dots are a rich testing ground for basic concepts regarding the measurement and control of quantum states. The well defined geometry is ideal for studying interaction mechanisms, such as the interaction of two dipoles each located in one of the quantum dots of the quantum dot molecule. A prerequisite for doing

Mark Kerfoot; Allan Bracker; Daniel Gammon; Michael Scheibner

2011-01-01

353

Reality television and the muscular male ideal.  

PubMed

Although researchers have examined the negative effects of viewing reality television (RTV) on women's body image, this research has not been extended to men. Exploring the extent to which RTV depicts men who embody the muscular ideal may enhance our understanding of the potential influence of this media genre. We explored the extent to which RTV depicted men who embodied the muscular ideal using a quantitative content analysis. Based on binomial tests, the primary male cast members of programs airing on networks popular among young adult men during the Fall 2009 broadcast season were more muscular, with lower levels of body fat, than average U.S. men. The chest-to-waist and shoulder-to-waist ratios of these cast members did not differ as a function of program type (i.e., reality drama, endurance, and romance). Young men who view RTV programs included in the present study would be exposed to an unrepresentative muscular ideal. PMID:23523084

Dallesasse, Starla L; Kluck, Annette S

2013-06-01

354

Frequency locking of single-mode 3.5-THz quantum cascade lasers using a gas cell  

E-print Network

We report frequency locking of two 3.5-THz third-order distributed feedback (DFB)quantum cascade lasers(QCLs) by using methanol molecular absorption lines, a proportional-integral-derivative controller, and a NbN bolometer. ...

Ren, Y.

355

Symmetries and currents of the ideal and unitary Fermi gases  

E-print Network

The maximal algebra of symmetries of the free single-particle Schroedinger equation is determined and its relevance for the holographic duality in non-relativistic Fermi systems is investigated. This algebra of symmetries is an infinite dimensional extension of the Schroedinger algebra, it is isomorphic to the Weyl algebra of quantum observables, and it may be interpreted as a non-relativistic higher-spin algebra. The associated infinite collection of Noether currents bilinear in the fermions are derived from their relativistic counterparts via a light-like dimensional reduction. The minimal coupling of these currents to background sources is rewritten in a compact way by making use of Weyl quantisation. Pushing forward the similarities with the holographic correspondence between the minimal higher-spin gravity and the critical O(N) model, a putative bulk dual of the unitary and the ideal Fermi gases is discussed.

Xavier Bekaert; Elisa Meunier; Sergej Moroz

2012-02-06

356

Casimir force between two ideal-conductor walls revisited  

E-print Network

The high-temperature aspects of the Casimir force between two neutral conducting walls are studied. The mathematical model of "inert" ideal-conductor walls, considered in the original formulations of the Casimir effect, is based on the universal properties of the electromagnetic radiation in the vacuum between the conductors, with zero boundary conditions for the tangential components of the electric field on the walls. This formulation seems to be in agreement with experiments on metallic conductors at room temperature. At high temperatures or large distances, at least, fluctuations of the electric field are present in the bulk and at the surface of a particle system forming the walls, even in the high-density limit: "living" ideal conductors. This makes the enforcement of the inert boundary conditions inadequate. Within a hierarchy of length scales, the high-temperature Casimir force is shown to be entirely determined by the thermal fluctuations in the conducting walls, modelled microscopically by classical Coulomb fluids in the Debye-H\\"{u}ckel regime. The semi-classical regime, in the framework of quantum electrodynamics, is studied in the companion letter by P.R.Buenzli and Ph.A.Martin, cond-mat/0506363, Europhys.Lett.72, 42 (2005).

Bernard Jancovici; Ladislav Samaj

2005-09-28

357

Multimode solutions of an ideal plastic flow  

E-print Network

This paper contains an analysis of multimode solutions expressible in terms of Riemann invariants obtained from complex characteristic elements. A variant of the conditional symmetry method for constructing this type of solution is proposed. Examples of applications of the proposed approach to a nonstationary irrotational ideal plastic flow in (2+1) dimensions are discussed in detail. Several new classes of solutions, some of them bounded, have been obtained in closed form. For a particular case of a stationary ideal plastic flow, extrusion dies have been drawn.

Grundland, A M

2012-01-01

358

Analysis of an idealized Stirling thermocompressor  

SciTech Connect

A thermocompressor uses thermal energy to increase the pressure of a fluid without the intermediate production of mechanical work. The thermocompressor described here is essentially a cold-connected Gamma Stirling engine with the power cylinder replaced by inlet and discharge check valves. It is analyzed based on assumptions similar to those made in the analysis of an ideal Stirling engine. The analysis gives closed form predictions for thermocompressor thermal efficiency, volumetric efficiency, and non-dimensional heat input as functions of pressure and temperature ratio. It is also used to compare thermocompressor performance to that of an ideal Otto engine-driven mechanical compressor.

Kornhauser, A.A. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Mechanical Engineering

1996-12-31

359

A Saturation Algorithm for Homogeneous Binomial Ideals  

Microsoft Academic Search

\\u000a Let k[x\\u000a 1, …, x\\u000a \\u000a n\\u000a ] be a polynomial ring in n variables, and let I???k[x\\u000a 1, …, x\\u000a \\u000a n\\u000a ] be a homogeneous binomial ideal. We describe a fast algorithm to compute the saturation, I:(x\\u000a 1???x\\u000a \\u000a n\\u000a )???. In the special case when I is a toric ideal, we present some preliminary results comparing our algorithm with Project

Deepanjan Kesh; Shashank K. Mehta

360

Ideal magnetohydrodynamic stability of axisymmetric mirrors  

NASA Astrophysics Data System (ADS)

The governing partial differential equation for general mode-number pressure-driven ballooning modes in a long-thin, axisymmetric plasma is derived within the context of ideal magnetohydrodynamics. It is shown that the equation reduces in special limits to the Hain-Lüst equation, the high-m diffuse p(?) ballooning equation, and the low-m sharp-boundary equation. A low-? analytic solution of the full partial differential equation is presented for quasiflute modes in an idealized tandem mirror model to elucidate the relationship of the various limiting cases.

D'Ippolito, D. A.; Hafizi, B.; Myra, J. R.

1982-12-01

361

Ideal magnetohydrodynamic stability of axisymmetric mirrors  

NASA Astrophysics Data System (ADS)

The governing partial differential equation for general mode number pressure-driven ballooning modes in a long-thin, axisymmetric plasma is derived within the context of ideal magnetohydrodynamics. It is shown that the equation reduces in special limits to the Hain-Luest equation, the high-m diffuse p(psi) ballooning equation, and the low-m sharp-boundary equation. A low-(ALPHA) analytic solution of the full partial differential equation is presented for quasiflute modes in an idealized tandem mirror model to elucidate the relationship of the various limiting cases.

Dippolito, D. A.; Hafizi, B.; Myra, J. R.

1981-12-01

362

Lecture by John F. Nash Jr. Ideal Money and Asymptotically Ideal Money  

E-print Network

Lecture by John F. Nash Jr. Ideal Money and Asymptotically Ideal Money The special commodity or medium that we call money has a long and interesting history. And since we are so dependent on our use teaches, in effect, that "less is more" or that (in other words) "bad money is better than good money

Babu, G. Jogesh

363

The behaviour of non-ideal explosives in the Ballistic Mortar  

Microsoft Academic Search

An analysis has been developed for the Ballistic Mortar test based on classical mechanics and a two stage chemical reaction rate model. Non-ideal behaviour of the composition was modelled by partial energy release during the detonation phase and secondary exothermic processes during the expansion phase. Erosive grain burning and time delayed reactions were both considered. Gas loss from the mortar

Graeme A. Leiper

1989-01-01

364

Analysis of operational filtration data part I. Ideal candle filter behavior  

Microsoft Academic Search

Operating data for the hot-gas filtration system of the Integrated Gasification and Cleanup Facility (IGCF) at the Federal Energy Technology Center are carefully analyzed. A model for candle filters is developed and used to describe the ideal filtration process. The parameters of the model are evaluated with a least-square error fit procedure. It is shown that the model predicts the

Duane H. Smith; Victor Powell; Goodarz Ahmadi; Essam Ibrahim

1997-01-01

365

Effect of quantum tunneling on single strand breaks in a modeled gas phase cytidine nucleotide induced by low energy electron: A theoretical approach  

NASA Astrophysics Data System (ADS)

Effect of quantum mechanical tunneling on single strand breaks induced by low energy electron (LEE) has been investigated in a modeled gas phase system, 2'-deoxycytidine-3'-monophosphate (3'-dCMPH). The potential energy curves for the sugar-phosphate C-O (3' C-O) bond cleavage have been generated using second order Møller-Plesset perturbation theory at the 6-31+G(d) accuracy level. Results from the electronic structure theory calculations in conjunction with our time dependent calculations for the 3' C-O bond rupture in 3'-dCMPH using local complex potential based time dependent wave packet approach show significant quantum tunneling of the 3' C-O bond from the bound vibrational states above 1 eV of the anionic potential energy curve. A comparison of the fragmentation profile with that of our earlier gas phase investigations based on Hartree-Fock and density functional theory - Becke, 3-parameter, Lee-Yang-Parr methods with 6-31+G(d) basis set is also provided. Further, inspection of the singly occupied molecular orbitals generated at different 3' C-O bond lengths clearly indicates the electron transfer from the low lying base-?* shape resonance state to the phosphate P = O ?* orbital of the DNA backbone during the strand breaks. The decisive step during LEE induced strand breaks follows via "charge induced dissociation" (CID) for the metastable anion formed below 1 eV, whereas quantum mechanical tunnel-ing is out-weighted the CID mechanism for the LEE above 1 eV.

Bhaskaran, Renjith; Sarma, Manabendra

2013-07-01

366

Developing Ideal Student and Residency Programs.  

ERIC Educational Resources Information Center

The Veterans Administration (VA) is a primary educator of optometry students, with each college of optometry being affiliated with at least one VA hospital. Ideally, fourth-year optometry students rotate through a specific VA facility for about 12 weeks. Guidelines are designed to provide optimum care in a rich learning environment. (MSE)

Selvin, Gerald J.

1993-01-01

367

Defining an Ideal Teacher Education Program1  

Microsoft Academic Search

Program standards can take many different forms, as the history of the NCATE attests. One reason they take so many forms is that members of a field often disagree among themselves about what constitutes either essential minimums or ideal maximums. Because many standards are intended to guarantee minimum safeguards, they tend to focus on minimum requirements. When they aim higher,

Mary M. Kennedy

1997-01-01

368

Real vs. Ideal Self Discrepancy in Bulimics.  

ERIC Educational Resources Information Center

Bulimia is an eating disorder prevalent among young women, characterized by binge eating episodes followed by purging with subsequent depressive moods and self-deprecating thoughts. To determine whether bulimic women exhibit a greater discrepancy between their perceived and ideal selves than do nonbulimics, three samples of women were assessed.…

Kosak, Karen

369

Commutative ideal theory without finiteness conditions  

E-print Network

Jul 26, 2004 ... LASZLO FUCHS, WILLIAM HEINZER, AND BRUCE OLBERDING. Abstract. .... then we can only claim that R/C is a uniform R-module, that is, the intersection ... field for each P ? Spec R and every primal ideal of R is maximal.

1910-40-72

370

Random drift of an idealized oil patch  

Microsoft Academic Search

A model for the random drift of an idealized oil patch on water due to influences of wind and currents is developed. Probabilistic descriptions for the displacement of the center of mass are derived. The model provides for random shifts in wind direction and its influence on reorienting the oil patch.

M. H. Fallah; R. M. Stark

1976-01-01

371

Introduction Ideally, fishery biologists dream of a  

E-print Network

88 Introduction Ideally, fishery biologists dream of a sensor that, when placed in a water body. Availability of acoustic sensors such as side scan sonar (SSS) and multibeam bottom sounders incorporating very fast pro- cessor capabilities are beginning to actualize the fishery biologist's dream (Fish and Carr

372

The ideal Kolmogorov inertial range and constant  

NASA Technical Reports Server (NTRS)

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.

Zhou, YE

1993-01-01

373

The Ideal Train Timetabling Problem Toms Robenek  

E-print Network

the passenger demand in the planning and its aim is to minimize the passenger cost(s). The outcome of the ITTP methodology. Keywords Railway Optimization, Timetabling, Demand, Ideal Timetable, Passenger Utility ii #12;The (passengers). On the other hand, the goal of the private sector is to generate revenue. In transportation

Bierlaire, Michel

374

Ideal Spatial Adaptation by Wavelet Shrinkage  

Microsoft Academic Search

With ideal spatial adaptation, an oracle furnishes information about how best toadapt a spatially variable estimator, whether piecewise constant, piecewise polynomial,variable knot spline, or variable bandwidth kernel, to the unknown function. Estimationwith the aid of an oracle offers dramatic advantages over traditional linear estimationby nonadaptive kernels; however, it is a priori unclear whether such performance canbe obtained by a procedure

1994-01-01

375

Ideal spatial adaptation by wavelet shrinkage  

Microsoft Academic Search

SUMMARY With ideal spatial adaptation, an oracle furnishes information about how best to adapt a spatially variable estimator, whether piecewise constant, piecewise polynomial, variable knot spline, or variable bandwidth kernel, to the unknown function. Estimation with the aid of an oracle offers dramatic advantages over traditional linear estimation by nonadapt- ive kernels; however, it is a priori unclear whether such

DAVID L. DON; IAIN M. JOHNSTONE

1993-01-01

376

Ideal thermal efficiency for geothermal binary plants  

Microsoft Academic Search

The Carnot cycle is reviewed as to its appropriateness to serve as the ideal model for geothermal binary power plants. It is shown that the Carnot cycle sets an unrealistically high upper limit on the thermal efficiency of these plants. A more useful model is the triangular (or trilateral) cycle because binary plants operating on geothermal hot water use a

Ronald DiPippo

2007-01-01

377

Dielectric receivers for asymmetrical ideal concentrators  

Microsoft Academic Search

Cylindrical asymmetrical nonimaging concentrators with receivers based on fin absorbers immersed in dielectric rhombuses are introduced and shown to be ideal. They have the same concentration factor as dielectric filled devices but require only a small amount of dielectric around the absorber. The asymmetric shape and nontracking property of the collectors allow their arrangement in flat panels that, integrated with

Francesco Bloisi; Paolo Cavaliere; Sergio Martellucci; Joseph Quartieri; Luciano Vicari

1988-01-01

378

Street Children Draw the Ideal Person.  

ERIC Educational Resources Information Center

Forty-three adolescents (11-16 years of age) attending a health care program, Project Alternatives, for "street children" in Tegucigalpa, Honduras, drew randomly assigned pictures of either the ideal man or woman, engaged in some activity. These drawings were compared to samples from adolescents in various parts of the world to assess the global…

DiCarlo, Margaret A.; And Others

379

Migration Dynamics for the Ideal Free Distribution  

Microsoft Academic Search

This article verifies that the ideal free distribution (IFD) is evolutionarily stable, provided the payoff in each patch decreases with an increasing number of individuals. General frequency-dependent models of migratory dynamics that differ in the degree of animal omniscience are then developed. These models do not exclude migration at the IFD where balanced dispersal emerges. It is shown that the

Ross Cressman; Vlastimil K?ivan

2006-01-01

380

ABJM theory as a Fermi gas  

E-print Network

The partition function on the three-sphere of many supersymmetric Chern-Simons-matter theories reduces, by localization, to a matrix model. We develop a new method to study these models in the M-theory limit, but at all orders in the 1/N expansion. The method is based on reformulating the matrix model as the partition function of an ideal Fermi gas with a non-trivial, one-particle quantum Hamiltonian. This new approach leads to a completely elementary derivation of the N^{3/2} behavior for ABJM theory and N=3 quiver Chern-Simons-matter theories. In addition, the full series of 1/N corrections to the original matrix integral can be simply determined by a next-to-leading calculation in the WKB or semiclassical expansion of the quantum gas, and we show that, for several quiver Chern-Simons-matter theories, it is given by an Airy function. This generalizes a recent result of Fuji, Hirano and Moriyama for ABJM theory. It turns out that the semiclassical expansion of the Fermi gas corresponds to a strong coupling expansion in type IIA theory, and it is dual to the genus expansion. This allows us to calculate explicitly non-perturbative effects due to D2-brane instantons in the AdS background.

Marcos Marino; Pavel Putrov

2012-03-14

381

The Ideal Man and Woman According to University Students  

ERIC Educational Resources Information Center

The present study determined if the ideal man has changed over the years and who and what the ideal woman is. We asked students at Cameron University to rate the importance of character traits that define the ideal man and woman. Subjects also provided examples of famous people exemplifying the ideal, good, average, and inferior man and woman. We…

Weinstein, Lawrence; Laverghetta, Antonio V.; Peterson, Scott A.

2009-01-01

382

Int-Soft (Generalized) Bi-Ideals of Semigroups  

PubMed Central

The notions of int-soft semigroups and int-soft left (resp., right) ideals in semigroups are studied in the paper by Song et al. (2014). In this paper, further properties and characterizations of int-soft left (right) ideals are studied, and the notion of int-soft (generalized) bi-ideals is introduced. Relations between int-soft generalized bi-ideals and int-soft semigroups are discussed, and characterizations of (int-soft) generalized bi-ideals and int-soft bi-ideals are considered. Given a soft set (?;S) over U, int-soft (generalized) bi-ideals generated by (?;S) are established. PMID:25710051

Jun, Young Bae; Song, Seok-Zun

2015-01-01

383

New insights into the ideal adsorbed solution theory.  

PubMed

The GCMC technique is used for simulation of adsorption of CO2-CH4, CO2-N2 and CH4-N2 mixtures (at 298 K) on six porous carbon models. Next we formulate a new condition of the IAS concept application, showing that our simulated data obey this condition. Calculated deviations between IAS predictions and simulation results increase with the rise in pressure as in the real experiment. For the weakly adsorbed mixture component the deviation from IAS predictions is higher, especially when its content in the gas mixture is low, and this is in agreement with the experimental data. Calculated activity coefficients have similar plots to deviations between IAS and simulations, moreover obtained from simulated data activity coefficients are similar qualitatively as well as quantitatively to experimental data. Since the physical interpretation of activity coefficients is completely lacking we show for the first time that they can be described by the formulas derived from the expression for G(ex) for the ternary mixture. Finally we also for the first time show the linear relationship between the chemical potentials of nonideal and ideal solutions and the reduced temperature of interacting mixture components, and it is proved that the deviation from ideality is larger if adsorption occurs in a more microporous system. PMID:25689966

Furmaniak, Sylwester; Koter, Stanis?aw; Terzyk, Artur P; Gauden, Piotr A; Kowalczyk, Piotr; Rychlicki, Gerhard

2015-03-01

384

Letterplace ideals and non-commutative Gröbner bases  

Microsoft Academic Search

In this paper we propose a 1-to-1 correspondence between graded two-sided ideals of the free associative algebra and some class of ideals of the algebra of polynomials, whose variables are double-indexed commuting ones. We call these ideals the “letterplace analogues” of graded two-sided ideals. We study the behaviour of the generating sets of the ideals under this correspondence, and in

Roberto La Scala; Viktor Levandovskyy

2009-01-01

385

Searching Out the Ideal: Awareness of Ideal Body Standards Predicts Lower Global Self-esteem in Women  

Microsoft Academic Search

Does awareness of female body ideals affect women's global self-esteem? We measured awareness of ideal standards for beauty via two approaches. As one approach, participants (55 undergraduate women) self-reported their general propensity to be aware of society's thin ideal standard. As a second approach, we measured visual attention orienting to ideal standards; we covertly measured participants' eye movements to peers'

Emily Balcetis; Shana Cole; Marie B. Chelberg; Mark Alicke

2012-01-01

386

Far-infrared collision-induced absorption in rare gas mixtures: Quantum and semi-classical calculations  

SciTech Connect

We compare calculations of the translational collision-induced spectra and their integrated intensities of both He–Ar and Ne–Ar collisional complexes, using the quantum mechanical and a semiclassical formalism. Advanced potential energy and induced dipole functions are used for the calculations. The quantum method used is as described previously [L. Frommhold, Collision-induced Absorption in Gases (Cambridge University Press, 1993 and 2006)]. The semiclassical method is based on repeated classical atom-atom scattering calculations to simulate an ensemble average; subsequent Fourier transform then renders the binary absorption coefficient as a function of frequency. The problem of classical calculations is the violation of the principle of detailed balance, which may be introduced only artificially in classical calculations. Nevertheless, it is shown that the use of classical trajectories permits a fairly accurate reproduction of the experimental spectra, comparable to the quantum mechanical results at not too low temperatures and for collisional pairs of not too small reduced mass. Inexpensive classical calculations may thus be promising to compute spectra also of molecular pairs, or even of polyatomic collisional pairs with anisotropic intermolecular interactions, for which the quantum approach is still inefficient or impractical.

Buryak, Ilya [Chemistry Department, Lomonosov Moscow State University, GSP-1, Vorobievy Gory, Moscow 119991 (Russian Federation) [Chemistry Department, Lomonosov Moscow State University, GSP-1, Vorobievy Gory, Moscow 119991 (Russian Federation); Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, 3 Pyzhevsky per., 119017 Moscow (Russian Federation); Frommhold, Lothar [Physics Department, University of Texas at Austin, Austin, Texas 78712-1081 (United States)] [Physics Department, University of Texas at Austin, Austin, Texas 78712-1081 (United States); Vigasin, Andrey A., E-mail: vigasin@ifaran.ru [Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, 3 Pyzhevsky per., 119017 Moscow (Russian Federation)

2014-04-21

387

Ideal photon number amplifier and duplicator  

NASA Technical Reports Server (NTRS)

The photon number-amplification and number-duplication mechanism are analyzed in the ideal case. The search for unitary evolutions leads to consider also a number-deamplification mechanism, the symmetry between amplification and deamplification being broken by the integer-value nature of the number operator. Both transformations, amplification and duplication, need an auxiliary field which, in the case of amplification, turns out to be amplified in the inverse way. Input-output energy conservation is accounted for using a classical pump or through frequency-conversion of the fields. Ignoring one of the fields is equivalent to considering the amplifier as an open system involving entropy production. The Hamiltonians of the ideal devices are given and compared with those of realistic systems.

Dariano, G. M.

1992-01-01

388

Non-ideal Solution Thermodynamics of Cytoplasm  

PubMed Central

Quantitative description of the non-ideal solution thermodynamics of the cytoplasm of a living mammalian cell is critically necessary in mathematical modeling of cryobiology and desiccation and other fields where the passive osmotic response of a cell plays a role. In the solution thermodynamics osmotic virial equation, the quadratic correction to the linear ideal, dilute solution theory is described by the second osmotic virial coefficient. Herein we report, for the first time, intracellular solution second osmotic virial coefficients for four cell types [TF-1 hematopoietic stem cells, human umbilical vein endothelial cells (HUVEC), porcine hepatocytes, and porcine chondrocytes] and further report second osmotic virial coefficients indistinguishable from zero (for the concentration range studied) for human hepatocytes and mouse oocytes. PMID:23840923

Ross-Rodriguez, Lisa U.; McGann, Locksley E.

2012-01-01

389

Joule-Thomson coefficient of ideal anyons within fractional exclusion statistics  

SciTech Connect

The analytical expressions of the Joule-Thomson coefficient for homogeneous and harmonically trapped three-dimensional ideal anyons which obey Haldane fractional exclusion statistics are derived. For an ideal Fermi gas, the Joule-Thomson coefficient is negative, which means that there is no maximum Joule-Thomson inversion temperature. With careful study, it is found that there exists a Joule-Thomson inversion temperature in the fractional exclusion statistics model. Furthermore, the relations between the Joule-Thomson inversion temperature and the statistical parameter g are investigated.

Qin Fang; Chen Jisheng [Physics Department and Institute of Nanoscience and Nanotechnology, Central China Normal University, Wuhan 430079 (China)

2011-02-15

390

Extended thermodynamics of molecular ideal gases  

NASA Astrophysics Data System (ADS)

The theory of extended thermodynamics developed by Liu and Miller (1983) and Kremer (1986) is applied to the molecular ideal gases. Consideration is given to the formulations for thermodynamic processes, the constitutive theory, the definition of equilibrium, the entropy principle, the principle of material-frame indifference, the identification of absolute temperature and transport coefficients, and the consequences of the entropy inequality. The relationships between this extended theory and both conventional thermodynamics and the kinetic theory of molecular gases are explored.

Kremer, G. M.

1989-02-01

391

Maximum concentration for ideal asymmetrical radiation concentrators  

Microsoft Academic Search

A new relation between the maximum geometric concentration factor C and the angular acceptance interval for asymmetrical ideal non-imaging concentrators is proposed. A generalization of the well-known relation for the two-dimensional case, sin?c=1\\/C where ?c is the acceptance half-angle, results in the proposed relation sin?2?sin?1=2\\/C, where ?1 and ?2 are the angles of the acceptance interval limits relative to the

S. Nordlander

2005-01-01

392

Base of nonlinear dynamics or Real Dynamics, Ideal Dynamics, Unpredictable Dynamics and "Schrodinger cat"  

E-print Network

In the paper paradoxes underlying thermodynamics and a quantum mechanics are discussed. Their solution is given from the point of view of influence of the exterior observer (surrounding medium) destroying correlations of system, or boundedness of self-knowledge of system in a case when both the observer, and a surrounding medium are included in system. Concepts Real Dynamics, Ideal Dynamics and Unpredictable Dynamics are entered. Consideration an appearance of a life is given from the point of view of these three Dynamics.

Oleg Kupervasser

2013-08-01

393

Informational derivation of quantum theory  

SciTech Connect

We derive quantum theory from purely informational principles. Five elementary axioms - causality, perfect distinguishability, ideal compression, local distinguishability, and pure conditioning - define a broad class of theories of information processing that can be regarded as standard. One postulate - purification - singles out quantum theory within this class.

Chiribella, Giulio; D'Ariano, Giacomo Mauro; Perinotti, Paolo [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Ontario, N2L 2Y5 (Canada); QUIT Group, Dipartimento di Fisica ''A. Volta'' and INFN Sezione di Pavia, via Bassi 6, I-27100 Pavia (Italy)

2011-07-15

394

Multiplicity scaling in ideal and viscous hydrodynamics  

NASA Astrophysics Data System (ADS)

Using numerical results from ideal and viscous relativistic hydrodynamic simulations with three different equations of state, for Au+Au and Cu+Cu collisions at different centralities and initial energy densities, we explore the dependence of the eccentricity-scaled elliptic flow, v2/?, and the produced entropy fraction, ?S/S0, on the final charged hadron multiplicity density dNch/dy per unit transverse overlap area S,(1/S)dNch/dy. The viscous hydrodynamic simulations are performed with two different versions of the Israel-Stewart kinetic evolution equations, and in each case we investigate the dependence of the physical observables on the kinetic relaxation time. We find approximate scaling of v2/? and ?S/S0 with (1/S)dNch/dy, with scaling functions that depend on the EOS and, in particular, on the value of the specific shear viscosity ?/s. Small scaling violations are seen even in ideal hydrodynamics, caused by a breaking of the scale invariance of ideal fluid dynamics by the freeze-out condition. Viscous hydrodynamics shows somewhat larger scale-breaking effects that increase with increasing ?/s and decreasing system size and initial energy density. We propose to use precision studies of these scaling violations to help constrain the shear viscosity ?/s of the quark-gluon plasma created in relativistic heavy ion collisions.

Song, Huichao; Heinz, Ulrich

2008-08-01

395

Word recognition using ideal word patterns  

NASA Astrophysics Data System (ADS)

The word shape analysis approach to text recognition is motivated by discoveries in psychological studies of the human reading process. It attempts to describe and compare the shape of the word as a whole object without trying to segment and recognize the individual characters, so it bypasses the errors committed in character segmentation and classification. However, the large number of classes and large variation and distortion expected in all patterns belonging to the same class make it difficult for conventional, accurate, pattern recognition approaches. A word shape analysis approach using ideal word patterns to overcome the difficulty and improve recognition performance is described in this paper. A special word pattern which characterizes a word class is extracted from different sample patterns of the word class and stored in memory. Recognition of a new word pattern is achieved by comparing it with the special pattern of each word class called ideal word pattern. The process of generating the ideal word pattern of each word class is proposed. The algorithm was tested on a set of machine printed gray scale word images which included a wide range of print types and qualities.

Zhao, Sheila X.; Srihari, Sargur N.

1994-03-01

396

Elastin: a representative ideal protein elastomer.  

PubMed Central

During the last half century, identification of an ideal (predominantly entropic) protein elastomer was generally thought to require that the ideal protein elastomer be a random chain network. Here, we report two new sets of data and review previous data. The first set of new data utilizes atomic force microscopy to report single-chain force-extension curves for (GVGVP)(251) and (GVGIP)(260), and provides evidence for single-chain ideal elasticity. The second class of new data provides a direct contrast between low-frequency sound absorption (0.1-10 kHz) exhibited by random-chain network elastomers and by elastin protein-based polymers. Earlier composition, dielectric relaxation (1-1000 MHz), thermoelasticity, molecular mechanics and dynamics calculations and thermodynamic and statistical mechanical analyses are presented, that combine with the new data to contrast with random-chain network rubbers and to detail the presence of regular non-random structural elements of the elastin-based systems that lose entropic elastomeric force upon thermal denaturation. The data and analyses affirm an earlier contrary argument that components of elastin, the elastic protein of the mammalian elastic fibre, and purified elastin fibre itself contain dynamic, non-random, regularly repeating structures that exhibit dominantly entropic elasticity by means of a damping of internal chain dynamics on extension. PMID:11911774

Urry, D W; Hugel, T; Seitz, M; Gaub, H E; Sheiba, L; Dea, J; Xu, J; Parker, T

2002-01-01

397

Non-Ideal Behavior in Solvent Extraction  

SciTech Connect

This report presents a summary of the work performed to meet FCR&D level 3 milestone M31SW050801, 'Complete the year-end report summarizing FY11 experimental and modeling activities.' This work was carried out under the auspices of the Non-Ideality in Solvent Extraction Systems FCR&D work package. The report summarizes our initial considerations of potential influences that non-ideal chemistry may impose on computational prediction of outcomes in solvent extraction systems. The report is packaged into three separate test cases where a robustness of the prediction by SXFIT program is under scrutiny. The computational exercises presented here emphasize the importance of accurate representation of both an aqueous and organic mixtures when modeling liquid-liquid distribution systems. Case No.1 demonstrates that non-ideal behavior of HDEHP in aliphatic diluents, such as n-dodecane, interferes with the computation. Cases No.2 and No.3 focus on the chemical complexity of aqueous electrolyte mixtures. Both exercises stress the need for an improved thermodynamic model of an aqueous environment present in the europium distribution experiments. Our efforts for year 2 of this project will focus on the improvements of aqueous and non-aqueous solution models using fundamental physical properties of mixtures acquired experimentally in our laboratories.

Peter Zalupski

2011-09-01

398

Dimensional Analysis Using Toric Ideals: Primitive Invariants  

PubMed Central

Classical dimensional analysis in its original form starts by expressing the units for derived quantities, such as force, in terms of power products of basic units etc. This suggests the use of toric ideal theory from algebraic geometry. Within this the Graver basis provides a unique primitive basis in a well-defined sense, which typically has more terms than the standard Buckingham approach. Some textbook examples are revisited and the full set of primitive invariants found. First, a worked example based on convection is introduced to recall the Buckingham method, but using computer algebra to obtain an integer matrix from the initial integer matrix holding the exponents for the derived quantities. The matrix defines the dimensionless variables. But, rather than this integer linear algebra approach it is shown how, by staying with the power product representation, the full set of invariants (dimensionless groups) is obtained directly from the toric ideal defined by . One candidate for the set of invariants is a simple basis of the toric ideal. This, although larger than the rank of , is typically not unique. However, the alternative Graver basis is unique and defines a maximal set of invariants, which are primitive in a simple sense. In addition to the running example four examples are taken from: a windmill, convection, electrodynamics and the hydrogen atom. The method reveals some named invariants. A selection of computer algebra packages is used to show the considerable ease with which both a simple basis and a Graver basis can be found. PMID:25436774

Atherton, Mark A.; Bates, Ronald A.; Wynn, Henry P.

2014-01-01

399

Effective mass and quantum lifetime in a Si/Si0.87Ge0.13/Si two-dimensional hole gas  

NASA Astrophysics Data System (ADS)

Measurements of Shubnikov de Haas oscillations in the temperature range 0.3-2 K have been used to determine an effective mass of 0.23 m0 in a Si/Si0.87Ge0.13/Si two-dimensional hole gas. This value is in agreement with theoretical predictions and with that obtained from cyclotron resonance measurements. The ratio of the transport time to the quantum lifetime is found to be 0.8. It is concluded that the 4 K hole mobility of 11 000 cm2 V-1 s-1 at a carrier sheet density of 2.2×1011 cm-2 is limited by interface roughness and short-range interface charge scattering.

Whall, T. E.; Mattey, N. L.; Plews, A. D.; Phillips, P. J.; Mironov, O. A.; Nicholas, R. J.; Kearney, M. J.

1994-01-01

400

Ideal Fluids, the Quark Gluon Plasma, and Hadronic Gases  

NASA Astrophysics Data System (ADS)

A detailed comparison between two methods to calculate the shear viscosity coefficient of a hot hadronic gas is presented. We choose two systems in this comparison which are massless particles with current algebra cross section and a mixture comprised of pions with rho resonances. The two methods involved are the Green-Kubo method, applied using the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model to simulate the hadronic medium, and the Chapman-Enskog method. In addition, the effect of the resonance lifetime on the shear viscosity coefficient is investigated.

Demir, Nasser

2015-01-01

401

Interaction effects in a two-dimensional electron gas in a random magnetic field: Implications for composite fermions and the quantum critical point  

NASA Astrophysics Data System (ADS)

We consider a clean two-dimensional interacting electron gas subject to a random perpendicular magnetic field h(r) . The field is nonquantizing in the sense that Nh , a typical flux into the area ?F2 in the units of the flux quantum ( ?F is the de Broglie wavelength), is small, Nh?1 . If the spatial scale ? of change of h(r) is much larger than ?F , the electrons move along semiclassical trajectories. We demonstrate that a weak-field-induced curving of the trajectories affects the interaction-induced electron lifetime in a singular fashion: it gives rise to the correction to the lifetime with a very sharp energy dependence. The correction persists within the interval ?˜?0=EFNh2/3 much smaller than the Fermi energy EF . It emerges in the third order in the interaction strength; the underlying physics is that a small phase volume ˜(?/EF)1/2 for scattering processes involving two electron-hole pairs is suppressed by curving. An even more surprising effect that we find is that disorder-averaged interaction correction to the density of states ??(?) exhibits oscillatory behavior periodic in (?/?0)3/2 . In our calculations of interaction corrections, a random field is incorporated via the phases of the Green functions in the coordinate space. We discuss the relevance of the new low-energy scale for realizations of a smooth random field in composite fermions and in disordered phase of spin-fermion model of ferromagnetic quantum criticality.

Sedrakyan, T. A.; Raikh, M. E.

2008-03-01

402

Towards quantum simulating QCD  

NASA Astrophysics Data System (ADS)

Quantum link models provide an alternative non-perturbative formulation of Abelian and non-Abelian lattice gauge theories. They are ideally suited for quantum simulation, for example, using ultracold atoms in an optical lattice. This holds the promise to address currently unsolvable problems, such as the real-time and high-density dynamics of strongly interacting matter, first in toy-model gauge theories, and ultimately in QCD.

Wiese, Uwe-Jens

2014-11-01

403

Photoacoustic gas sensing with a commercial external cavity-quantum cascade laser at 10.5 ?m  

NASA Astrophysics Data System (ADS)

We report the implementation of a commercial external cavity-quantum cascade laser emitting at 10.5 ?m in a photoacoustic spectrometer. This spectrometer enables measurements on broad spectral range up to 60 cm-1 which means that spectra of complex molecules can be recorded as well as a whole absorption band of a small molecule. The wide tuning range of the source of this photoacoustic spectrometer demonstrates the possibility to detect small and complex molecules such as carbon dioxide and butane.

Mammez, D.; Stoeffler, C.; Cousin, J.; Vallon, R.; Mammez, M. H.; Joly, L.; Parvitte, B.; Zéninari, V.

2013-11-01

404

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Remote laser detection of natural gas leakages from pipelines  

NASA Astrophysics Data System (ADS)

A differential absorption lidar based on a tunable TEA CO2 laser emitting at 42 lines of the 'hot' 0111 — 1110 band in the range from 10.9 to 11.4 ?m is developed for detecting natural gas leakages from oil pipelines by measuring the ethane content in the atmosphere. The ethane detection sensitivity is 0.9 ppm km. The presence of methane does not distort the measurement results. The developed lidar can detect the natural gas leakage from kilometre heights at the flying velocities up to 200 km h-1 and a probe pulse repetition rate of 5 Hz.

Petukhov, V. O.; Gorobets, V. A.; Andreev, Yu M.; Lanskii, G. V.

2010-02-01

405

Quantum particle-number fluctuations in a two-component Bose gas in a double-well potential  

SciTech Connect

A two-component Bose gas in a double-well potential with repulsive interactions may undergo a phase separation transition if the interspecies interactions outweigh the intraspecies ones. We analyze the transition in the strong interaction limit within the two-mode approximation. Numbers of particles in each potential well are equal and constant. However, at the transition point, the ground state of the system reveals huge fluctuations of numbers of particles belonging to the different gas components; that is, the probability for observation of any mixture of particles in each potential well becomes uniform.

Zin, Pawel [Soltan Institute for Nuclear Studies, Hoza 69, PL-00-681 Warsaw (Poland); Oles, Bartlomiej; Sacha, Krzysztof [Instytut Fizyki imienia Mariana Smoluchowskiego and Mark Kac Complex Systems Research Center, Uniwersytet Jagiellonski, ulica Reymonta 4, PL-30-059 Krakow (Poland)

2011-09-15

406

Population transfer and rapid passage effects in a low pressure gas using a continuous wave quantum cascade laser.  

PubMed

A continuous wave quantum cascade laser (cw-QCL) operating at 10 ?m has been used to record absorption spectra of low pressure samples of OCS in an astigmatic Herriott cell. As a result of the frequency chirp of the laser, the spectra show clearly the effects of rapid passage on the absorption line shape. At the low chirp rates that can be obtained with the cw-QCL, population transfer between rovibrational quantum states is predicted to be much more efficient than in typical pulsed QCL experiments. This optical pumping is investigated by solving the Maxwell Bloch equations to simulate the propagation of the laser radiation through an inhomogeneously broadened two-level system. The calculated absorption profiles show good quantitative agreement with those measured experimentally over a range of chirp rates and optical thicknesses. It is predicted that at a low chirp rate of 0.13 MHz ns(-1), the population transfer between rovibrational quantum states is 12%, considerably more than that obtained at the higher chirp rates utilised in pulsed QCL experiments. PMID:22830701

McCormack, E A; Lowth, H S; Bell, M T; Weidmann, D; Ritchie, G A D

2012-07-21

407

Dust Transport in Mri Turbulent Disks: Ideal and Non-Ideal Mhd With Ambipolar Diffusion  

NASA Astrophysics Data System (ADS)

We study dust transport in turbulent protoplanetary disks using three-dimensional global unstratified MHD simulations including Lagrangian dust particles. The turbulence is driven by the magnetorotational instability (MRI) with either ideal or non-ideal MHD that includes ambipolar diffusion (AD). In ideal MHD simulations, the surface density evolution (except for dust that drifts fastest), turbulent diffusion, and vertical scale height of dust can all be reproduced by simple one-dimensoinal and/or analytical models. However, in AD dominated simulations which simulate protoplanetary disks beyond 10s of AU, the vertical scale height of dust is larger than previously predicted. To understand this anomaly in more detail, we carry out both unstratified and stratified local shearing box simulations with Lagrangian particles, and find that turbulence in AD dominated disks has very different properties (e.g., temporal autocorrelation functions and power spectra) than turbulence in ideal MHD disks, which leads to quite different particle diffusion efficiency. For example, MRI turbulence with AD has a longer correlation time for the vertical velocity, which causes significant vertical particle diffusion and large dust scale height. In ideal MHD the Schmidt numbers (Sc) for radial and vertical turbulent diffusion are S{{c}r}? 1 and S{{c}z}? 3, but in the AD dominated regime both Scr and Scz are ? 1. Particle concentration in pressure bumps induced by MRI turbulence has also been studied. Since non-ideal MHD effects dominate most regions in protoplanetary disks, our study suggests that modeling dust transport in turbulence driven by MRI with non-ideal MHD effects is important for understanding dust transport in realistic protoplanetary disks.

Zhu, Zhaohuan; Stone, James M.; Bai, Xue-Ning

2015-03-01

408

Molecular structure and conformational preferences of methylthiodichlorophosphite, Cl 2PSCH 3, as studied by gas electron diffraction and quantum-chemical calculations  

NASA Astrophysics Data System (ADS)

Free Cl 2PSCH 3 molecule has been studied by gas electron diffraction (ED), B3PW91/6-311+G ? (DFT) and MP2/AUG-cc-PVTZ quantum-chemical calculations. Structure optimizations of Cl 2PSMe molecule by both theoretical methods (DFT/MP2) indicate that the most stable conformer is an anti conformer of Cs symmetry, while the energy of a gauche conformer is about 1.3/1.6 kcal mol -1 higher. Each conformer is characterized by dihedral angle ?(CSP lp) where lp denotes the direction of the electron lone pair on the P atom; assumed to lay in the plane passing through P-S bond and bisector of the ClPCl bond angle. The calculated standard free energies at 298.15 K indicate that the mole fractions in the gas phase at this temperature are: ?( anti) = 65/79%, ?( gauche) = 35/21%. Experimental ED data agree well with joint presence of both conformers in the ratio ?( anti) = 68(12)% and ?( gauche) = 32(12)%. Natural Bond Orbital (NBO) analysis suggests that the relative stabilities of the two conformers as well as the differences between bond distances, valence angles and different NBO descriptors may be determined by anomeric effects. The most important of which is ? lpS ? ?PCl?, that is delocalizations of ? lone pair of the S atom into antibonding orbital of P-Cl bond.

Belyakov, A. V.; Khramov, A. N.; Naumov, V. A.

2010-08-01

409

Classical representation of a quantum system at equilibrium: Theory  

NASA Astrophysics Data System (ADS)

A quantum system at equilibrium is represented by a corresponding classical system, chosen to reproduce thermodynamic and structural properties. The motivation is to allow application of classical strong-coupling theories and molecular dynamics simulation to quantum systems at strong coupling. The correspondence is made at the level of the grand-canonical ensembles for the two systems. An effective temperature, local chemical potential, and pair potential are introduced to define the corresponding classical system. These are determined formally by requiring the equivalence of the grand potentials and their functional derivatives. Practical inversions of these formal definitions are indicated via the integral equations for densities and pair correlation functions of classical liquid theory. Application to the ideal Fermi gas is demonstrated, and the weak-coupling form for the pair potential is given. In a companion paper two applications are described: the thermodynamics and structure of uniform jellium over a range of temperatures and densities and the shell structure of harmonically bound charges.

Dufty, James; Dutta, Sandipan

2013-03-01

410

Dimensional analysis using toric ideals: primitive invariants.  

PubMed

Classical dimensional analysis in its original form starts by expressing the units for derived quantities, such as force, in terms of power products of basic units [Formula: see text] etc. This suggests the use of toric ideal theory from algebraic geometry. Within this the Graver basis provides a unique primitive basis in a well-defined sense, which typically has more terms than the standard Buckingham approach. Some textbook examples are revisited and the full set of primitive invariants found. First, a worked example based on convection is introduced to recall the Buckingham method, but using computer algebra to obtain an integer [Formula: see text] matrix from the initial integer [Formula: see text] matrix holding the exponents for the derived quantities. The [Formula: see text] matrix defines the dimensionless variables. But, rather than this integer linear algebra approach it is shown how, by staying with the power product representation, the full set of invariants (dimensionless groups) is obtained directly from the toric ideal defined by [Formula: see text]. One candidate for the set of invariants is a simple basis of the toric ideal. This, although larger than the rank of [Formula: see text], is typically not unique. However, the alternative Graver basis is unique and defines a maximal set of invariants, which are primitive in a simple sense. In addition to the running example four examples are taken from: a windmill, convection, electrodynamics and the hydrogen atom. The method reveals some named invariants. A selection of computer algebra packages is used to show the considerable ease with which both a simple basis and a Graver basis can be found. PMID:25436774

Atherton, Mark A; Bates, Ronald A; Wynn, Henry P

2014-01-01

411

Gravitational collapse of magnetized clouds. I. Ideal MHD accretion flow  

E-print Network

We study the self-similar collapse of an isothermal magnetized rotating cloud in the ideal magnetohydrodynamic (MHD) regime. In the limit of small distance from the accreting protostar we find an analytic solution that corresponds to free-fall onto a central mass point. The density distribution is not spherically symmetric but depends on the mass loading of magnetic field lines, which can be obtained by matching our inner solution to an outer collapse solution previously computed by Allen, Shu & Li. The concentration of magnetic field trapped by the central mass point under field-freezing, independent on the details of the starting state, creates a split monopole configuration where the magnetic field strength increases as the inverse square of the distance from the center. Under such conditions, the inflow eventually becomes subalfvenic and the outward transfer of angular momentum by magnetic braking very efficient, thus preventing the formation of a centrifugally supported disk. Instead, the azimuthal velocity of the infalling gas decreases to zero at the center, and the gas spirals into the star. Therefore, the dissipation of dynamically important levels of magnetic field is a fundamental requisite for the formation of protoplanetary disks around young stars.

D. Galli; S. Lizano; F. H. Shu; A. Allen

2006-04-27

412

The equations of the ideal latches  

E-print Network

The latches are simple circuits with feedback from the digital electrical engineering. We have included in our work the C element of Muller, the RS latch, the clocked RS latch, the D latch and also circuits containing two interconnected latches: the edge triggered RS flip-flop, the D flip-flop, the JK flip-flop, the T flip-flop. The purpose of this study is to model with equations the previous circuits, considered to be ideal, i.e. non-inertial. The technique of analysis is the pseudoboolean differential calculus.

Serban E. Vlad

2008-04-05

413

"The Scientific Method" as Myth and Ideal  

NASA Astrophysics Data System (ADS)

"The Scientific Method" as it has been portrayed in popular and introductory contexts has been declared a myth. The variation that one finds in introductory presentations of "The Scientific Method" is explained by the fact that there is no canonical account among historians and philosophers of science. What, in particular, is wrong with "The Scientific Method"? This essay provides a fairly comprehensive survey of shortcomings of "The Scientific Method". Included are corrections to several misconceptions that often accompany such presentations. Rather than treating "The Scientific Method" as a useful approximation or an ideal, the myth should be discarded. Lessons can be learned for introductory pedagogical contexts from considering the shortcomings of the myth.

Woodcock, Brian A.

2014-10-01

414

Idealized simulations of aerosol influences on tornadogenesis  

NASA Astrophysics Data System (ADS)

Numerical simulations of an idealized supercell thunderstorm were performed to assess effects of increased aerosol concentrations acting as cloud condensation nuclei (CCN) and giant CCN (GCCN) on tornadogenesis. Initial background profiles of CCN and GCCN concentrations were set to represent ``clean'' continental and aerosol-polluted environments, respectively. With a reduction in warm- and cold-rain processes, the polluted environment produced a longer-lived supercell with a well-defined rear flank downdraft (RFD) and relatively weak forward flank downdraft (FFD) that produced weak evaporative cooling, a weak cold pool, and an EF-1 tornado. The clean environment produced no tornado and was less favorable for tornadogenesis.

Lerach, David G.; Gaudet, Brian J.; Cotton, William R.

2008-12-01

415

Hamiltonian description of the ideal fluid  

SciTech Connect

Fluid mechanics is examined from a Hamiltonian perspective. The Hamiltonian point of view provides a unifying framework; by understanding the Hamiltonian perspective, one knows in advance (within bounds) what answers to expect and what kinds of procedures can be performed. The material is organized into five lectures, on the following topics: rudiments of few-degree-of-freedom Hamiltonian systems illustrated by passive advection in two-dimensional fluids; functional differentiation, two action principles of mechanics, and the action principle and canonical Hamiltonian description of the ideal fluid; noncanonical Hamiltonian dynamics with examples; tutorial on Lie groups and algebras, reduction-realization, and Clebsch variables; and stability and Hamiltonian systems.

Morrison, P.J.

1994-01-01

416

Real-Time Trace Gas Sensing of Fluorocarbons using a Swept-wavelength External Cavity Quantum Cascade Laser  

SciTech Connect

We present results demonstrating real-time sensing of four different fluorocarbons at low-ppb concentrations using an external cavity quantum cascade laser (ECQCL) operating in a swept-wavelength configuration. The ECQCL was repeatedly swept over its full tuning range at a 20 Hz rate with a scan rate of 3535 cm-1/s, and a detailed characterization of the ECQCL scan stability and repeatability is presented. The sensor was deployed on a mobile automotive platform to provide spatially resolved detection of fluorocarbons in outdoor experiments. Noise-equivalent detection limits of 800-1000 parts-per-trillion (ppt) are demonstrated for 1 s integration times.

Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.; Cannon, Bret D.; Stahl, Robert D.; Schiffern, John T.; Myers, Tanya L.

2014-05-04

417

Simple Waves in Ideal Radiation Hydrodynamics  

SciTech Connect

In the dynamic diffusion limit of radiation hydrodynamics, advection dominates diffusion; the latter primarily affects small scales and has negligible impact on the large scale flow. The radiation can thus be accurately regarded as an ideal fluid, i.e., radiative diffusion can be neglected along with other forms of dissipation. This viewpoint is applied here to an analysis of simple waves in an ideal radiating fluid. It is shown that much of the hydrodynamic analysis carries over by simply replacing the material sound speed, pressure and index with the values appropriate for a radiating fluid. A complete analysis is performed for a centered rarefaction wave, and expressions are provided for the Riemann invariants and characteristic curves of the one-dimensional system of equations. The analytical solution is checked for consistency against a finite difference numerical integration, and the validity of neglecting the diffusion operator is demonstrated. An interesting physical result is that for a material component with a large number of internal degrees of freedom and an internal energy greater than that of the radiation, the sound speed increases as the fluid is rarefied. These solutions are an excellent test for radiation hydrodynamic codes operating in the dynamic diffusion regime. The general approach may be useful in the development of Godunov numerical schemes for radiation hydrodynamics.

Johnson, B M

2008-09-03

418

Nonlinear stability of ideal fluid equilibria  

SciTech Connect

The Lyapunov method for establishing stability is related to well- known energy principles for nondissipative dynamical systems. A development of the Lyapunov method for Hamiltonian systems due to Arnold establishes sufficient conditions for Lyapunov stability by using the energy plus other conserved quantities, together with second variations and convexity estimates. When treating the stability of ideal fluid dynamics within the Hamiltonian framework, a useful class of these conserved quantities consists of the Casimir functionals, which Poisson-commute with all functionals of the dynamical fluid variables. Such conserved quantities, when added to the energy, help to provide convexity estimates that bound the growth of perturbations. These convexity estimates, in turn, provide norms necessary for establishing Lyapunov stability under the nonlinear evolution. In contrast, the commonly used second variation or spectral stability arguments only prove linearized stability. As ideal fluid examples, in these lectures we discuss planar barotropic compressible fluid dynamics, the three-dimensional hydrostatic Boussinesq model, and a new set of shallow water equations with nonlinear dispersion due to Basdenkov, Morosov, and Pogutse(1985). Remarkably, all three of these samples have the same Hamiltonian structure and, thus, possess the same Casimir functionals upon which their stability analyses are based. We also treat stability of modified quasigeostrophic flow, a problem whose Hamiltonian structure and Casimirs closely resemble Arnold's original example. Finally, we discuss some aspects of conditional stability and the applicability of Arnold's development of the Lyapunov technique. 100 refs.

Holm, D.D.

1988-01-01

419

The Statistical Mechanics of Ideal Homogeneous Turbulence  

NASA Technical Reports Server (NTRS)

Plasmas, such as those found in the space environment or in plasma confinement devices, are often modeled as electrically conducting fluids. When fluids and plasmas are energetically stirred, regions of highly nonlinear, chaotic behavior known as turbulence arise. Understanding the fundamental nature of turbulence is a long-standing theoretical challenge. The present work describes a statistical theory concerning a certain class of nonlinear, finite dimensional, dynamical models of turbulence. These models arise when the partial differential equations describing incompressible, ideal (i.e., nondissipative) homogeneous fluid and magnetofluid (i.e., plasma) turbulence are Fourier transformed into a very large set of ordinary differential equations. These equations define a divergenceless flow in a high-dimensional phase space, which allows for the existence of a Liouville theorem, guaranteeing a distribution function based on constants of the motion (integral invariants). The novelty of these particular dynamical systems is that there are integral invariants other than the energy, and that some of these invariants behave like pseudoscalars under two of the discrete symmetry transformations of physics, parity, and charge conjugation. In this work the 'rugged invariants' of ideal homogeneous turbulence are shown to be the only significant scalar and pseudoscalar invariants. The discovery that pseudoscalar invariants cause symmetries of the original equations to be dynamically broken and induce a nonergodic structure on the associated phase space is the primary result presented here. Applicability of this result to dissipative turbulence is also discussed.

Shebalin, John V.

2002-01-01

420

Global invariants in ideal magnetohydrodynamic turbulence  

SciTech Connect

Magnetohydrodynamic (MHD) turbulence is an important though incompletely understood factor affecting the dynamics of many astrophysical, geophysical, and technological plasmas. As an approximation, viscosity and resistivity may be ignored, and ideal MHD turbulence may be investigated by statistical methods. Incompressibility is also assumed and finite Fourier series are used to represent the turbulent velocity and magnetic field. The resulting model dynamical system consists of a set of independent Fourier coefficients that form a canonical ensemble described by a Gaussian probability density function (PDF). This PDF is similar in form to that of Boltzmann, except that its argument may contain not just the energy multiplied by an inverse temperature, but also two other invariant integrals, the cross helicity and magnetic helicity, each multiplied by its own inverse temperature. However, the cross and magnetic helicities, as usually defined, are not invariant in the presence of overall rotation or a mean magnetic field, respectively. Although the generalized form of the magnetic helicity is known, a generalized cross helicity may also be found, by adding terms that are linear in the mean magnetic field and angular rotation vectors, respectively. These general forms are invariant even in the presence of overall rotation and a mean magnetic field. We derive these general forms, explore their properties, examine how they extend the statistical theory of ideal MHD turbulence, and discuss how our results may be affected by dissipation and forcing.

Shebalin, John V. [Astromaterials Research Office, NASA Johnson Space Center, Houston, Texas 77058-3696 (United States)] [Astromaterials Research Office, NASA Johnson Space Center, Houston, Texas 77058-3696 (United States)

2013-10-15

421

What constitutes an ideal dental restorative material?  

PubMed

Intense environmental concerns recently have prompted dentistry to evaluate the performance and environmental impact of existing restoration materials. Doing so entices us to explore the 'what if?' innovation in materials science to create more ideal restorative materials. Articulating a specification for our design and evaluation methods is proving to be more complicated than originally anticipated. Challenges exist not only in specifying how the material should be manipulated and perform clinically but also in understanding and incorporating implications of the skill of the operator placing the restoration, economic considerations, expectations patients have for their investment, cost-effectiveness, influences of the health care system on how and for whom restorations are to be placed, and global challenges that limit the types of materials available in different areas of the world. The quandary is to find ways to actively engage multiple stakeholders to agree on priorities and future actions to focus future directions on the creation of more ideal restorative materials that can be available throughout the world. PMID:24129813

Rekow, E D; Bayne, S C; Carvalho, R M; Steele, J G

2013-11-01

422

Quantum particle-number fluctuations in a two-component Bose gas in a double-well potential  

Microsoft Academic Search

A two-component Bose gas in a double-well potential with repulsive interactions may undergo a phase separation transition if the interspecies interactions outweigh the intraspecies ones. We analyze the transition in the strong interaction limit within the two-mode approximation. Numbers of particles in each potential well are equal and constant. However, at the transition point, the ground state of the system

Pawel Zin; Bartlomiej Oles; Krzysztof Sacha

2011-01-01

423

An ideal sealed source life-cycle  

SciTech Connect

In the last 40 years, barriers to compliant and timely disposition of radioactive sealed sources have become apparent. The story starts with the explosive growth of nuclear gauging technologies in the 1960s. Dozens of companies in the US manufactured sources and many more created nuclear solutions to industrial gauging problems. Today they do not yet know how many Cat 1, 2, or 3 sources there are in the US. There are, at minimum, tens of thousands of sources, perhaps hundreds of thousands of sources. Affordable transportation solutions to consolidate all of these sources and disposition pathways for these sources do not exist. The root problem seems to be a lack of necessary regulatory framework that has allowed all of these problems to accumulate with no national plan for solving the problem. In the 1960s, Pu-238 displaced Pu-239 for most neutron and alpha source applications. In the 1970s, the availability of inexpensive Am-241 resulted in a proliferation of low energy gamma sources used in nuclear gauging, well logging, pacemakers, and X-ray fluorescence applications for example. In the 1980s, rapid expansion of worldwide petroleum exploration resulted in the expansion of Am-241 sources into international locations. Improvements of technology and regulation resulted in a change in isotopic distribution as Am-241 made Pu-239 and Pu-238 obsolete. Many early nuclear gauge technologies have been made obsolete as they were replaced by non-nuclear technoogies. With uncertainties in source end of life disposition and increased requirements for sealed source security, nuclear gauging technology is the last choice for modern process engineering gauging solutions. Over the same period, much was learned about licensing LLW disposition facilities as evident by the closure of early disposition facilities like Maxey Flats. The current difficulties in sealed source disposition start with adoption of the NLLW policy act of 1985, which created the state LLW compact system they we have today. This regulation created a new regulatory framework seen as promising at the time. However, now they recognize that, despite the good intentions, the NIJWP/85 has not solved any source disposition problems. The answer to these sealed source disposition problems is to adopt a philosophy to correct these regulatory issues, determine an interim solution, execute that solution until there is a minimal backlog of sources to deal with, and then let the mechanisms they have created solve this problem into the foreseeable future. The primary philosophical tenet of the ideal sealed source life cycle follows. You do not allow the creation (or importation) of any source whose use cannot be justified, which cannot be affordably shipped, or that does not have a well-delinated and affordable disposition pathway. The path forward dictates that we fix the problem by embracing the Ideal Source Life cycle. In figure 1, we can see some of the elements of the ideal source life cycle. The life cycle is broken down into four portions, manufacture, use, consolidation, and disposition. These four arbitrary elements allow them to focus on the ideal life cycle phases that every source should go through between manufacture and final disposition. As we examine the various phases of the sealed source life cycle, they pick specific examples and explore the adoption of the ideal life cycle model.

Tompkins, Joseph Andrew [Los Alamos National Laboratory

2009-01-01

424

The ideal energy of classical lattice dynamics  

E-print Network

We define, as local quantities, the least energy and momentum allowed by quantum mechanics and special relativity for physical realizations of some classical lattice dynamics. These definitions depend on local rates of finite-state change. In two example dynamics, we see that these rates evolve like classical mechanical energy and momentum.

Margolus, Norman

2015-01-01

425

OBNER BASIS FOR KAZHDANLUSZTIG IDEALS ALEXANDER WOO AND ALEXANDER YONG  

E-print Network

a single geometric setting to transparently explain the naturality of pipe dreams on the Rothe diagram Ë? obner basis theo­ rem for Schubert determinantal ideals and their geometric interpretation--Lusztig ideals 7 3. Pipe dreams on Rothe diagrams and the initial ideal of I v,w 9 3.1. The prime decomposition

Yong, Alexander

426

The Transfer of Scientific Principles Using Concrete and Idealized  

E-print Network

The Transfer of Scientific Principles Using Concrete and Idealized Simulations Robert L. Goldstone the first simulation was manipulated. The elements either remained concrete throughout the simulation, remained idealized, or switched midway into the simulation from concrete to idealized or vice versa

Goldstone, Robert

427

Promoting Spiritual Ideals through Design Thinking in Public Schools  

ERIC Educational Resources Information Center

Against a backdrop of the debates on religious education in public or state schools, we argue for the introduction of "spiritual ideals" into the public school curriculum. We distinguish our notion of spiritual ideals from "religious ideals" as conceptualised by De Ruyter and Merry. While we agree with De Ruyter and Merry that ideas drawn from…

Tan, Charlene; Wong, Yew-Leong

2012-01-01

428

Moral Identity as Moral Ideal Self: Links to Adolescent Outcomes  

ERIC Educational Resources Information Center

The purposes of this study were to conceptualize moral identity as moral ideal self, to develop a measure of this construct, to test for age and gender differences, to examine links between moral ideal self and adolescent outcomes, and to assess purpose and social responsibility as mediators of the relations between moral ideal self and outcomes.…

Hardy, Sam A.; Walker, Lawrence J.; Olsen, Joseph A.; Woodbury, Ryan D.; Hickman, Jacob R.

2014-01-01

429

PBMR as an Ideal Heat Source for High-Temperature Process Heat Applications  

Microsoft Academic Search

The Pebble Bed Modular Reactor (PBMR) is an advanced helium-cooled, graphite-moderated High Temperature Gas-cooled Reactor (HTGR). A 400 MWt PBMR Demonstration Power Plant (DPP) for the production of electricity is being developed in South Africa. This PBMR technology is also an ideal heat source for process heat applications, including Steam Methane Reforming, steam for Oil Sands bitumen recovery, Hydrogen Production

Michael Correia; Renee Greyvenstein; Fred Silady; Scott Penfield

2006-01-01

430

Coulomb Systems with Ideal Dielectric Boundaries: Free Fermion Point and Universality  

Microsoft Academic Search

A two-component Coulomb gas confined by walls made of ideal dielectric material is considered. In two dimensions at the special inverse temperature ß=2, by using the Pfaffian method, the system is mapped onto a four-component Fermi field theory with specific boundary conditions. The exact solution is presented for a semi-infinite geometry of the dielectric wall (the density profiles, the correlation

B. Jancovici; L. Šamaj

2001-01-01

431

Coulomb Systems with Ideal Dielectric Boundaries: Free Fermion Point and Universality  

Microsoft Academic Search

A two-component Coulomb gas confined by walls made of ideal dielectric material is considered. In two dimensions at the special inverse temperature $\\\\beta = 2$, by using the Pfaffian method, the system is mapped onto a four-component Fermi field theory with specific boundary conditions. The exact solution is presented for a semi-infinite geometry of the dielectric wall (the density profiles,

B. Jancovici; L. Samaj

2001-01-01

432

On controlling nonlinear dissipation in high order filter methods for ideal and non-ideal MHD  

NASA Technical Reports Server (NTRS)

The newly developed adaptive numerical dissipation control in spatially high order filter schemes for the compressible Euler and Navier-Stokes equations has been recently extended to the ideal and non-ideal magnetohydrodynamics (MHD) equations. These filter schemes are applicable to complex unsteady MHD high-speed shock/shear/turbulence problems. They also provide a natural and efficient way for the minimization of Div(B) numerical error. The adaptive numerical dissipation mechanism consists of automatic detection of different flow features as distinct sensors to signal the appropriate type and amount of numerical dissipation/filter where needed and leave the rest of the region free from numerical dissipation contamination. The numerical dissipation considered consists of high order linear dissipation for the suppression of high frequency oscillation and the nonlinear dissipative portion of high-resolution shock-capturing methods for discontinuity capturing. The applicable nonlinear dissipative portion of high-resolution shock-capturing methods is very general. The objective of this paper is to investigate the performance of three commonly used types of nonlinear numerical dissipation for both the ideal and non-ideal MHD.

Yee, H. C.; Sjogreen, B.

2004-01-01

433

Real-time trace gas sensing of fluorocarbons using a swept-wavelength external cavity quantum cascade laser.  

PubMed

We present results demonstrating real-time sensing of four different fluorocarbons at low part-per billion (ppb) concentrations using an external cavity quantum cascade laser (ECQCL) designed for infrared vibrational spectroscopy of molecules with broad absorption features. The ECQCL was repeatedly swept at 20 Hz over its full tuning range of 1145-1265 cm(-1) providing a scan rate of 3535 cm(-1) s(-1), and a detailed characterization of the ECQCL scan stability and repeatability is presented. The ECQCL was combined with a 100 meter path length multi-pass cell for direct absorption spectroscopy. A portable sensor system is described, which was deployed on a mobile automotive platform to provide spatially-resolved detection of fluorocarbons in outdoor experiments. Noise-equivalent detection limits of 800-1000 parts-per-trillion (ppt) are demonstrated for 1 s integration times. PMID:24384671

Phillips, Mark C; Taubman, Matthew S; Bernacki, Bruce E; Cannon, Bret D; Stahl, Robert D; Schiffern, John T; Myers, Tanya L

2014-05-01

434

Christiana Honsberg Derivation of the ideal diode equation for solar cells Derivation of the Ideal Diode Equation for Photovoltaics  

E-print Network

Christiana Honsberg Derivation of the ideal diode equation for solar cells Derivation of the Ideal Diode Equation for Photovoltaics Christiana Honsberg Basic Equations: 1. Poisson's equation of the ideal diode equation for solar cells General Procedure using the depletion approximation: Divide

Honsberg, Christiana

435

Extracting the Chern Number from the Dynamics of a Fermi Gas: Implementing a Quantum Hall Bar for Cold Atoms  

NASA Astrophysics Data System (ADS)

We propose a scheme to measure the quantized Hall conductivity of an ultracold Fermi gas initially prepared in a topological Chern insulating phase and driven by a constant force. We show that the time evolution of the center of mass, after releasing the cloud, provides a direct and clear signature of the topologically invariant Chern number. We discuss the validity of this scheme, highlighting the importance of driving the system with a sufficiently strong force to displace the cloud over measurable distances while avoiding band-mixing effects. The unusual shapes of the driven atomic cloud are qualitatively discussed in terms of a semiclassical approach.

Dauphin, Alexandre; Goldman, Nathan

2013-09-01

436

Quantum master equation for collisional dynamics of massive particles with internal degrees of freedom  

SciTech Connect

We address the microscopic derivation of a quantum master equation in Lindblad form for the dynamics of a massive test particle with internal degrees of freedom, interacting through collisions with a background ideal gas. When either internal or center-of-mass degrees of freedom can be treated classically, previously established equations are obtained as special cases. If in an interferometric setup the internal degrees of freedom are not detected at the output, the equation can be recast in the form of a generalized Lindblad structure, which describes non-Markovian effects. The effect of internal degrees of freedom on center-of-mass decoherence is considered in this framework.

Smirne, Andrea; Vacchini, Bassano [Universita degli Studi di Milano, Dipartimento di Fisica, Via Celoria 16, I-20133 Milano (Italy) and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy)

2010-10-15

437

Faked states attack and quantum cryptography protocols  

E-print Network

Leveraging quantum mechanics, cryptographers have devised provably secure key sharing protocols. Despite proving the security in theory, real-world application falls short of the ideal. Last year, cryptanalysts completed an experiment demonstrating a successful eavesdropping attack on commercial quantum key distribution (QKD) systems. This attack exploits a weakness in the typical real-world implementation of quantum cryptosystems. Cryptanalysts have successfully attacked several protocols. In this paper, we examine the Kak quantum cryptography protocol and how it may perform under such attacks.

Denny, Travis

2011-01-01

438

Thermal stability of idealized folded carbyne loops  

PubMed Central

Self-unfolding items provide a practical convenience, wherein ring-like frames are contorted into a state of equilibrium and subsequently ?pop up’ or deploy when perturbed from a folded structure. Can the same process be exploited at the molecular scale? At the limiting scale is a closed chain of single atoms, used here to investigate the limits of stability of such folded ring structures via full atomistic molecular dynamics. Carbyne is a one-dimensional carbon allotrope composed of sp-hybridized carbon atoms. Here, we explore the stability of idealized carbyne loops as a function of chain length, curvature, and temperature, and delineate an effective phase diagram between folded and unfolded states. We find that while overall curvature is reduced, in addition to torsional and self-adhesive energy barriers, a local increase in curvature results in the largest impedance to unfolding. PMID:24252156

2013-01-01

439

Broken Ergodicity in Ideal, Homogeneous, Incompressible Turbulence  

NASA Technical Reports Server (NTRS)

We discuss the statistical mechanics of numerical models of ideal homogeneous, incompressible turbulence and their relevance for dissipative fluids and magnetofluids. These numerical models are based on Fourier series and the relevant statistical theory predicts that Fourier coefficients of fluid velocity and magnetic fields (if present) are zero-mean random variables. However, numerical simulations clearly show that certain coefficients have a non-zero mean value that can be very large compared to the associated standard deviation. We explain this phenomena in terms of broken ergodicity', which is defined to occur when dynamical behavior does not match ensemble predictions on very long time-scales. We review the theoretical basis of broken ergodicity, apply it to 2-D and 3-D fluid and magnetohydrodynamic simulations of homogeneous turbulence, and show new results from simulations using GPU (graphical processing unit) computers.

Morin, Lee; Shebalin, John; Fu, Terry; Nguyen, Phu; Shum, Victor

2010-01-01

440

Stability of ideal fcc twin boundaries  

NASA Astrophysics Data System (ADS)

Ideas from continuum mechanics are used to derive an elastic stability inequality for a boundary between two different materials under quasi-static, homogeneous conditions. The terms in this inequality are interpreted for the case of an ideal twinning plane between two variants of a face-centered cubic material. High quality potentials for Ni and Cu are used in molecular dynamics calculations to calibrate relevant energies and displacements near the twinning plane. It is found that in comparison with direct molecular dynamics calculations the inequality predicts the critical stress that initiates movement of the twinning plane in Ni within 1.9% and within 1.3% for Cu. Although the predicted and calculated critical stresses are only upper bounds for the more realistic case of an imperfect boundary, the calculations give considerable insight into the interplay of energies that lead to boundary motion.

Wright, T. W.; Daphalapurkar, N. P.; Ramesh, K. T.

2014-12-01

441

Ideal ballooning modes in axisymmetric mirror machines  

SciTech Connect

A simple code is described that finds marginally stable (..omega../sup 2/ = 0) ballooning-type MHD modes, localized about a field line in an axisymmetric, open-ended, plasma confinement device. The equations are based on a lower bound for the perturbed energy delta W, derived by W. Newcomb from the ideal MHD energy principle, and are cast in the form of a Ricatti equation for the first derivative of the eigenfunction, with the open boundary conditions that this derivative vanish at the plasma boundary down each field line. The input to the code is the two-dimensional shape of a field line, the field strength B(s), and parameters to define pressure profiles throughout the system. The objective is to find the highest plasma pressures for which the given line is MHD-stable.

Baldwin, D.E.; McNamara, B.; Willmann, P.

1980-12-15

442

Error analysis of idealized nanopore sequencing  

PubMed Central

This numerical study provides an error analysis of an idealized nanopore sequencing method in which ionic current measurements are used to sequence intact single-stranded DNA in the pore, while an enzyme controls DNA motion. Examples of systematic channel errors when more than one nucleotide affects the current amplitude are detailed, which if present will persist regardless of coverage. Absent such errors, random errors associated with tracking through homopolymer regions are shown to necessitate reading known sequences (E. coli K-12) at least 140 times to achieve 99.99% accuracy (Q40). By exploiting the ability to reread each strand at each pore in an array, arbitrary positioning on an error rate vs. throughput tradeoff curve is possible if systematic errors are absent, with throughput governed by the number of pores in the array and the enzyme turnover rate. PMID:23744714

O'Donnell, Christopher R.; Wang, Hongyun; Dunbar, William B.

2013-01-01

443

Ideal magnetohydrodynamic stability of tokamak plasmas  

NASA Astrophysics Data System (ADS)

Variational theory is used to derive a generalized Euler equation and a new energy functional which are convenient for analytical studies of ideal magnetohydrodynamic stability in tokamaks. This generalized Euler equation, which is an explicit function of the magnetic surface coordinate psi only, represents an infinite set of equations coupled together by poloidal m mode coupling. In the infinite aspect ratio limit, the toroidal curvature and mode coupling terms disappear and an infinite set of uncoupled Euler equations for the diffuse linear pinch (Hain-Luest equation) for each m value results. The continuous spectra are discussed for the circular toroidal case. In this case, the equations are further specialized to three modes (m, m - 1, m + 1) and in the marginal stability limit reduce to known results. Analytically eliminating the m - 1 and m + 1 modes for arbitrary current profiles provides results on limiting beta poloidal for tokamaks.

Copenhaver, C.

1980-03-01

444

Review of Idealized Aircraft Wake Vortex Models  

NASA Technical Reports Server (NTRS)

Properties of three aircraft wake vortex models, Lamb-Oseen, Burnham-Hallock, and Proctor are reviewed. These idealized models are often used to initialize the aircraft wake vortex pair in large eddy simulations and in wake encounter hazard models, as well as to define matched filters for processing lidar observations of aircraft wake vortices. Basic parameters for each vortex model, such as peak tangential velocity and circulation strength as a function of vortex core radius size, are examined. The models are also compared using different vortex characterizations, such as the vorticity magnitude. Results of Euler and large eddy simulations are presented. The application of vortex models in the postprocessing of lidar observations is discussed.

Ahmad, Nashat N.; Proctor, Fred H.; Duparcmeur, Fanny M. Limon; Jacob, Don

2014-01-01

445

Idealized simulations of sting jet cyclones  

NASA Astrophysics Data System (ADS)

An idealized modeling study of sting-jet cyclones is presented. Sting jets are descending mesoscale jets that occur in some extratropical cyclones and produce localized regions of strong low-level winds in the frontal fracture region. Moist baroclinic lifecycle (LC1) simulations are performed with modifications to produce cyclones resembling observed sting-jet cyclones. Two jets exist in the control idealized cyclone that descend into the frontal fracture region and result in strong winds near to the top of the boundary layer; one of these satisfies the criteria for a sting jet, the other is associated with the warm front. Sensitivity experiments show that both these jets are robust features. The sting jet strength (measured by maximum low-level wind speed or descent rate) increases with the cyclone growth rate; growth rate increases with increasing basic-state zonal jet maximum or decreasing basic-state tropospheric static stability. The two cyclones with the weakest basic-state static stability have by far the strongest sting jets, with descent rates comparable to those observed. Evaporative cooling contributes up to 20% of the descent rate in these sting jets compared with up to 4% in the other sting jets. Conditional symmetric instability (CSI) release in the cloud head also contributes to the sting jet, although there is less extensive CSI than in observed cases. The robustness of the sting jets suggests that they could occur frequently in cyclones with frontal fracture; however, they are unlikely to be identified unless momentum transport through the boundary layer leads to strong surface wind gusts.

Baker, L. H.; Gray, S. L.; Clark, P. A.

2012-04-01

446

Quantum computation: algorithms and implementation in quantum dot devices  

NASA Astrophysics Data System (ADS)

In this thesis, we explore several aspects of both the software and hardware of quantum computation. First, we examine the computational power of multi-particle quantum random walks in terms of distinguishing mathematical graphs. We study both interacting and non-interacting multi-particle walks on strongly regular graphs, proving some limitations on distinguishing powers and presenting extensive numerical evidence indicative of interactions providing more distinguishing power. We then study the recently proposed adiabatic quantum algorithm for Google PageRank, and show that it exhibits power-law scaling for realistic WWW-like graphs. Turning to hardware, we next analyze the thermal physics of two nearby 2D electron gas (2DEG), and show that an analogue of the Coulomb drag effect exists for heat transfer. In some distance and temperature, this heat transfer is more significant than phonon dissipation channels. After that, we study the dephasing of two-electron states in a single silicon quantum dot. Specifically, we consider dephasing due to the electron-phonon coupling and charge noise, separately treating orbital and valley excitations. In an ideal system, dephasing due to charge noise is strongly suppressed due to a vanishing dipole moment. However, introduction of disorder or anharmonicity leads to large effective dipole moments, and hence possibly strong dephasing. Building on this work, we next consider more realistic systems, including structural disorder systems. We present experiment and theory, which demonstrate energy levels that vary with quantum dot translation, implying a structurally disordered system. Finally, we turn to the issues of valley mixing and valley-orbit hybridization, which occurs due to atomic-scale disorder at quantum well interfaces. We develop a new theoretical approach to study these effects, which we name the disorder-expansion technique. We demonstrate that this method successfully reproduces atomistic tight-binding techniques, while using a fraction of the computational resources and providing considerably more physical insight. Using this technique, we demonstrate that large dipole moments can exist between valley states in disordered systems, and calculate corrections to intervalley tunnel rates..

Gamble, John King

447

Genetic Algorithms and Quantum Computation  

Microsoft Academic Search

Recently, researchers have applied genetic algorithms (GAs) to address some\\u000aproblems in quantum computation. Also, there has been some works in the\\u000adesigning of genetic algorithms based on quantum theoretical concepts and\\u000atechniques. The so called Quantum Evolutionary Programming has two major\\u000asub-areas: Quantum Inspired Genetic Algorithms (QIGAs) and Quantum Genetic\\u000aAlgorithms (QGAs). The former adopts qubit chromosomes as representations

Gilson A. Giraldi; Renato Portugal; Ricardo N. Thess

2004-01-01

448

Quantum Computation Quantum Information  

E-print Network

Quantum Computation and Quantum Information Samuel J. Lomonaco, Jr. and Howard E. Brandt editors Searches with a Quantum Robot .............................................. 12 pages Benioff, Paul Perturbation Theory and Numerical Modeling Quantum Logic Operations with a Large of Qubits

Lomonaco Jr., Samuel J.

449

Quantum field theory for the three-body constrained lattice Bose gas. II. Application to the many-body problem  

NASA Astrophysics Data System (ADS)

We analyze the ground-state phase diagram of attractive lattice bosons, which are stabilized by a three-body onsite hardcore constraint. A salient feature of this model is an Ising-type transition from a conventional atomic superfluid to a dimer superfluid with vanishing atomic condensate. The study builds on an exact mapping of the constrained model to a theory of coupled bosons with polynomial interactions, proposed in a related paper [S. Diehl, M. Baranov, A. Daley, and P. Zoller, Phys. Rev. B 82, 064509 (2010).10.1103/PhysRevB.82.064509]. In this framework, we focus by analytical means on aspects of the phase diagram which are intimately connected to interactions, and are thus not accessible in a mean-field plus spin-wave approach. First, we determine shifts in the mean-field phase border, which are most pronounced in the low-density regime. Second, the investigation of the strong coupling limit reveals the existence of a “continuous supersolid,” which emerges as a consequence of enhanced symmetries in this regime. We discuss its experimental signatures. Third, we show that the Ising-type phase transition, driven first order via the competition of long-wavelength modes at generic fillings, terminates into a true Ising quantum critical point in the vicinity of half filling.

Diehl, S.; Baranov, M.; Daley, A. J.; Zoller, P.

2010-08-01

450

Photoluminescence of charged CdSe/ZnS quantum dots in the gas phase: effects of charge and heating on absorption and emission probabilities.  

PubMed

Gas phase spectral measurements for CdSe/ZnS core/shell nanocrystal quantum dots (QDs) before and after heating with both infrared (CO2) and visible lasers are reported. As-trapped QDs are spectrally similar to the same QDs in solution; however their photoluminescence (PL) intensities are very low, at least partly due to low absorption cross sections. After heating, the PL intensities brighten by factors ranging from ?4 to 1800 depending on the QD size and pump laser wavelength. The emission spectra no longer resemble solution spectra and are similar, regardless of the QD diameter. Emission extends from the pump laser wavelength into the near-IR, with strong emission features above the band gap energy, between 645 and 775 nm, and in the near-infrared. Emission spectra from brightened QD ensembles, single QD aggregates, and single QD monomers are similar, showing that even single QDs support PL from a wide variety of states. The heating and cooling processes for QDs in this environment are analyzed, providing limits on the magnitudes of the absorption cross sections before and after thermal brightening. A model, based on absorption bleaching by extra electrons in the conduction band, appears to account for the changes in absorption and emission behavior induced by charging and heating. PMID:25427008

Howder, Collin R; Long, Bryan A; Bell, David M; Furakawa, Kevin H; Johnson, Ryan C; Fang, Zhiyuan; Anderson, Scott L

2014-12-23

451

Low-energy positron scattering from gas-phase pyrimidine: A quantum treatment of the dynamics and a comparison with experiments  

NASA Astrophysics Data System (ADS)

In the present work we are reporting detailed quantum scattering calculations that describe the diffusion of a beam of low-energy positrons interacting with the pyrimidine target as a gas-phase partner. The calculations have employed an essentially ab initio model for the short-range correlation interaction and for the electrostatic interaction of an impinging positron and the electron+nuclear structure of the target molecule at its equilibrium geometry. The available experiments were also performed in the low-energy region below about 30 eV and have been reported by two different experimental groups cited in the main text. Those data include integral elastic plus rotationally and vibrationally summed cross sections, together with angular distributions over the same range of energies. The effects on the scattering observables which stem from the permanent dipole moment of the title molecule are carefully analyzed and computational corrections which ensure numerical convergence are introduced and discussed. The additional uncertainties introduced by the angular discrimination error present in the experiments are also discussed and analyzed, thereby providing a numerical procedure for correcting all available data. The final comparison between experimental angular distributions and the computed counterparts produced in the present work turns out to be very good. The same applies to the comparison in size and energy dependence of the integral cross sections, where we show that our calculated quantities and the corrected experiments are in very good agreement over the whole range of available energies.

Franz, J.; Gianturco, F. A.

2013-10-01

452

Landau levels and spin splitting in the two-dimensional electron gas of a HgTe quantum well near the critical width for the topological phase transition  

NASA Astrophysics Data System (ADS)

We report a detailed low-temperature study of the two-dimensional (2D) electron gas in a 6.1-nm-wide HgTe quantum well with H g0.3C d0.7Te barriers by terahertz magnetophotoconductivity and magnetotransmission combined with magnetotransport measurements (Rx x and Rx y) in magnetic fields up to 10 T. This well width, close to that at the topological phase transition, corresponds to conventional band ordering, and we probe the "bulk" quasi-2D Landau-level (LL) spectrum of the conduction band at high energies (?135 -160 meV ) above the Dirac point. The calculated separations between adjacent LLs of the same spin based on published parameters for this structure are in fair agreement with the measured cyclotron resonance energies. However, the very large spin splittings observed (Espin>Ecyclotron) require a significantly larger g -parameter ge for electrons. Tilted field coincidence experiments are consistent with the large spin splitting showing coincidences at 3/2 and twice the cyclotron energy. This large value of ge also leads to interesting crossings of the calculated LLs, and we find direct evidence of these crossings in the Rx x measurements at lower electron densities (Fermi energies) produced by negative gate bias.

Pakmehr, M.; Bruene, C.; Buhmann, H.; Molenkamp, L. W.; Stier, A. V.; McCombe, B. D.

2014-12-01

453

On probing ions at the gas-liquid interface by quantum state-resolved molecular beam scattering: the curious incident of the cation in the night time.  

PubMed

There has been a long standing controversy over the preferential presence or absence of cations vs. anions at the gas-liquid interface, dating back to early theoretical efforts by Onsager and co-workers [J. Chem. Phys., 1934, 2, 528]. In the present work, we describe our first efforts to selectively probe ions at the interface via a completely novel approach, based on scattering high energy, jet cooled molecular projectiles from the surface of hydrogen bonded liquids with dissolved alkali halide salts as the source of solvated charges. In particular, this work focuses on preliminary results from quantum state- resolved scattering studies as a function of anion (Cl-, I-), and cation identity (Li+, Na+, K+) in alkali halide/glycerol solutions. By way of physical picture, a quadrupolar projectile such as CO2 preferentially aligns parallel (anions) or perpendicular (cations) to the interface, which could therefore make rotational energy transfer sensitive to the sign of the ion charge. Experimentally, we find that the impulsive scattered (IS) CO2 rotational distributions reveal a clear dependence on anion identity (e.g., hotter for [I-] than [Cl-]), but with essentially no corresponding sensitivity to cation species (e.g., [Li+] indistinguishable from [K+]). Detailed trajectory calculations are used to provide additional insight into the anticipated and observed experimental trends. PMID:23230774

Gisler, Andrew W; Nesbitt, David J

2012-01-01

454

Semi-insulating InP:Fe for buried-heterostructure strain-compensated quantum-cascade lasers grown by gas-source molecular-beam epitaxy  

NASA Astrophysics Data System (ADS)

We describe the realization of buried-heterostructure strain-compensated quantum-cascade lasers that incorporate a very high degree of internal strain and are grown on InP substrates using gas-source molecular-beam epitaxy (GSMBE). The active region of the lasers contains AlAs layers up to 1.6 nm thick with 3.7% tensile strain; restricting any post-growth processing to temperatures below 600 °C to avoid relaxation. We demonstrate that buried-heterostructure devices can be realized by using GSMBE to over-grow the etched laser ridge with insulating InP:Fe at temperatures low enough to preserve the crystal quality of the strain-compensated active region. Two distinct growth techniques are described, both leading to successful device realization: selective regrowth at 550 °C and non-selective regrowth at 470 °C. The resulting buried-heterostructure lasers are compared to a reference laser from the same wafer, but with SiO2 insulation; all three have very similar threshold current densities, operational thermal stability, and waveguide losses.

Semtsiv, M. P.; Aleksandrova, A.; Elagin, M.; Monastyrskyi, G.; Kischkat, J.-F.; Flores, Y. V.; Masselink, W. T.

2013-09-01

455

Einstein's idealism and a new kind of space research  

NASA Astrophysics Data System (ADS)

In 1935, Albert Einstein, Boris Podolsky and Nathan Rosen made an attempt to imagine quantum experimental nonsense or some impossible experiment (EPR-experiment) in order to justify their local realism in physics. However, in the mid-1960s, John Bell showed that it is possible to realize this kind of nonsense in laboratory. Today, when EPR-refutation of local realism is routine in modern experimental physics (Clauser and Freedman [1972]; Aspect, Dalibard and Roger [1982]; Zeilinger et al. [1998]), we must; nevertheless, remark that Albert Einstein was not always a realist. As is known, in his Special Relativitz A. Einstein introduced some pure idealistic principle which K. Godel developed in famous "Remark about the relationship between Relativity theorz and Idealistic Philosophy" (1949). Kurt Godel for the first time showed an existence of special-relativistic solipsism, assuming that objective simultaneity in experimental science "loses its objective meaning". Correspondingly, there is only subjective simultaneity, that is provable by calculations with the finite velocity of light and astronomical observations. In particular, this space solipsism means that when we observe the sun, we can see only what happend on Sun 8.33 minutes ago; in other words, we percieve only certain sensations or a certain collections of ideas of the past, but not the present. Similarly, when astronomers observe galaxies estimated to be two billion light years from the Earth, they see these galaxies as they were two billion light years ago not as they are Now. Thus, in accordance with this, we may await that in this context for some pairs of astronomical objects we cannot prove they exist NOW. Moreover, this new kind of space research could be connected with introduction of the Cognitive Dark Matter, or, what is associated with manifold of the large-scale events of the Universe as a whole which are realizing Now, beyond consciousness of the observers-humans. Because we cannot know present time in Cosmology, the Cognitive Dark Matter is Kant-like superphenomental, or transcendental "noumental process" (Noumena). To describe Transcendental Dark Matter by methods of experimental idealism is, probably, the most sursprising and profound task for new space discipline ("Space Idealism"). We may await also that some fundamental characteristics of physical Dark Matter, discovered by Ostiker, Steinhardt, Krauss and Turner (1955), can be explained by our hypothethis, because it is not impossible that the Dark Matter is a part of the Cognitive Dark Matter, contained an observer's impact, which cannot be neglected after Special Relativity.

Popov, M. A.

456

On properties of Velikhov-Chandrasekhar MRI in ideal and non-ideal plasma  

NASA Astrophysics Data System (ADS)

Conditions of Velikhov-Chandrasekhar magnetorotational instability (MRI) in ideal and non-ideal plasmas are examined. Linear WKB analysis of hydromagnetic axially symmetric flows shows that in the Rayleigh-unstable hydrodynamic case where the angular momentum decreases with radius, the MRI branch becomes stable, and the magnetic field suppresses the Rayleigh instability at small wavelengths. We investigate the limiting transition from hydromagnetic flows to hydrodynamic flows. The Rayleigh mode smoothly transits to the hydrodynamic case, while the Velikhov-Chandrasekhar MRI mode completely disappears without the magnetic field. The effects of viscosity and magnetic diffusivity in plasma on the MRI conditions in thin accretion discs are studied. We find the limits on the mean-free path of ions allowing MRI to operate in such discs.

Shakura, N.; Postnov, K.

2015-04-01

457

A Full Ranking for Decision Making Units Using Ideal and Anti-Ideal Points in DEA  

PubMed Central

We propose a procedure for ranking decision making units in data envelopment analysis, based on ideal and anti-ideal points in the production possibility set. Moreover, a model has been introduced to compute the performance of a decision making unit for these two points through using common set of weights. One of the best privileges of this method is that we can make ranking for all decision making units by solving only three programs, and also solving these programs is not related to numbers of decision making units. One of the other advantages of this procedure is to rank all the extreme and nonextreme efficient decision making units. In other words, the suggested ranking method tends to seek a set of common weights for all units to make them fully ranked. Finally, it was applied for different sets holding real data, and then it can be compared with other procedures. PMID:25147844

Barzegarinegad, A.; Jahanshahloo, G.; Rostamy-Malkhalifeh, M.

2014-01-01

458

Ideal Fermi gases in harmonic oscillator potential traps  

SciTech Connect

We study the thermodynamic properties of an ideal gas of fermions in a harmonic oscillator confining potential. The analogy between this problem and the de Haas-van Alphen effect is discussed and used to obtain analytical results for the chemical potential and specific heat in the case of both isotropic and anisotropic potentials. Step-like behaviour in the chemical potential, first noted in numerical studies, is obtained analytically and shown to result in an oscillatory behaviour of the specific heat when the particle number is varied. The origin of these oscillations is that part of the thermodynamic potential is responsible for the de Haas-van Alphen-type effect. At low temperatures we show analytically that there are significant deviations in the specific heat from the expected linear temperature dependence, again as a consequence of the de Haas-van Alphen part of the thermodynamic potential. Results are given for one, two, and three spatial dimensions. In the anisotropic case we show how the specific heat jumps as the ratio of oscillator frequencies varies.

Toms, David J. [School of Mathematics and Statistics, University of Newcastle Upon Tyne, Newcastle Upon Tyne NE1 7RU (United Kingdom)]. E-mail: d.j.toms@newcastle.ac.uk

2005-12-15

459

Vacuum Technology: Kinetic Theory of Gas  

NSDL National Science Digital Library

This is a PDF version of lecture slides that discuss the kinetic theory of gases. Slide topics include vacuum basics, kinetic pressure of an ideal gas, pressure and molecular velocity, basic equations from kinetic theory, gas laws, and gas transport phenomena. Numerous charts and mathematical formulas are presented. Keywords: Boltzman's constant, collision frequency, molecular velocity, Boyle's law, Charles' law, Dalton's law

Rack, Philip D.

460

Field topologies in ideal and near-ideal magnetohydrodynamics and vortex dynamics  

NASA Astrophysics Data System (ADS)

Magnetic field topology frozen in ideal magnetohydrodynamics (MHD) and its breakage in near-ideal MHD are reviewed in two parts, clarifying and expanding basic concepts. The first part gives a physically complete description of the frozen field topology derived from magnetic flux conservation as the fundamental property, treating four conceptually related topics: Eulerian and Lagrangian descriptions of three dimensional (3D) MHD, Chandrasekhar-Kendall and Euler-potential field representations, magnetic helicity, and inviscid vortex dynamics as a fluid system in physical contrast to ideal MHD. A corollary of these developments clarifies the challenge of achieving a high degree of the frozen-in condition in numerical MHD. The second part treats field-topology breakage centered around the Parker Magnetostatic Theorem on a general incompatibility of a continuous magnetic field with the dual demand of force-free equilibrium and an arbitrarily prescribed, 3D field topology. Preserving field topology as a global constraint readily results in formation of tangential magnetic discontinuities, or, equivalently, electric current-sheets of zero thickness. A similar incompatibility is present in the steady force-thermal balance of a heated radiating fluid subject to an anisotropic thermal flux conducted strictly along its frozen-in magnetic field in the low- ? limit. In a weakly resistive fluid the thinning of current sheets by these general incompatibilities inevitably results in sheet dissipation, resistive heating and topological changes in the field notwithstanding the small resistivity. Strong Faraday induction drives but also macroscopically limits this mode of energy dissipation, trapping or storing free energy in self-organized ideal-MHD structures. This property of MHD turbulence captured by the Taylor hypothesis is reviewed in relation to the Sun's corona, calling for a basic quantitative description of the breakdown of flux conservation in the low-resistivity limit. A cylindrical initial-boundary value problem provides specificity in the general MHD ideas presented.

Low, B. C.

2015-01-01

461

Nonlinear filtering and limiting in high order methods for ideal and non-ideal MHD  

NASA Technical Reports Server (NTRS)

The various filtering mechanisms and base scheme options of the newly developed adaptive numerical dissipation control in spatially high order filter schemes for the ideal and non-ideal magnetohydrodynamics (MHD) equations are investigated. These filter schemes are applicable to complex unsteady MHD high-speed shock/shear/turbulence problems. They also provide a natural and efficient way for the minimization of Div(B) numerical error. The type of spatial base scheme to be used in conjunction with our filter idea is very general. For example, spectral, compact and non-compact spatially central finite difference schemes are possible candidates. The adaptive numerical dissipation mechanism consists of automatic detection of different flow features as distinct sensors to signal the appropriate type and amount of numerical dissipation/filter where needed and to leave the rest of the region free from numerical dissipation contamination. The numerical dissipation considered consists of high order linear dissipation for the suppression of high frequency oscillation and the nonlinear dissipative portion of high-resolution shock-capturing methods for discontinuity capturing. The applicable nonlinear dissipative portion of high-resolution shock-capturing methods is also very general. The objective of this paper is to investigate the performance of using compact and non-compact central base schemes in conjunction with three commonly used types of nonlinear numerical dissipation for both the ideal and non-ideal MHD. This extended abstract shows the performance of three nonlinear filters in conjunction with a sixth-order non-compact spatial central base scheme. In the final paper, the high order compact spatial central base scheme will be illustrated and compared with the non-compact base scheme. The reason for the investigation of the high order compact spatial central base scheme over the non-compact base scheme is to evaluate if additional accuracy can be gained in regions of fine scale turbulence that are away from shocks/shears.

Yee,H. C.; Sjogreen, B.

2004-01-01

462

The Quantum World of Ultra-Cold Atoms and Light - Book 1: Foundations of Quantum Optics  

NASA Astrophysics Data System (ADS)

Abstract The Table of Contents is as follows: * I - THE PHYSICAL BACKGROUND * 1. Controlling the Quantum World * 1.1 Quantum Optics * 1.2 Quantum Information * 2. Describing the Quantum World * 2.1 Classical Stochastic Processes * 2.2. Theoretical Quantum Optics * 2.3. Quantum Stochastic Methods * 2.4. Ultra-Cold Atoms * II - CLASSICAL STOCHASTIC METHODS * 3. Physics in a Noisy World * 3.1. Brownian Motion and the Thermal Origin of Noise * 3.2. Brownian Motion, Friction, Noise and Temperature * 3.3. Measurement in a Fluctuating System * 4. Stochastic Differential Equations * 4.1. Ito Stochastic Differential Equation * 4.2. The Fokker-Planck Equation * 4.3. The Stratonovich Stochastic Differential Equation * 4.4. Systems with Many Variables * 4.5. Numerical Simulation of Stochastic Differential Equations * 5. The Fokker-Planck Equation * 5.1. Fokker-Planck Equation in One Dimension * 5.2. Eigenfunctions of the Fokker-Planck Equation * 5.3. Many-Variable Fokker-Planck Equations * 6. Master Equations and Jump Processes * 6.1. The Master Equation * 7. Applications of Random Processes * 7.1. The Ornstein-Uhlenbeck Process * 7.2. Johnson Noise * 7.3. Complex Variable Oscillator Processes * 8. The Markov Limit * 8.1. The White Noise Limit * 8.2. Interpretation and Generalizations of the White Noise Limit * 8.3. Linear Non-Markovian Stochastic Differential Equations * 9. Adiabatic Elimination of Fast Variables * 9.1 Slow and Fast Variables * 9.2. Other Applications of the Adiabatic Elimination Method * III - FIELDS, QUANTA AND ATOMS * 10. Ideal Bose and Fermi Systems * 10.1. The Quantum Gas * 10.2. Thermal States * 10.3. Fluctuations in the Ideal Bose Gas * 10.4. Bosonic Quantum Gaussian Systems * 10.5. Coherent States * 10.6. Fluctuations in Systems of Fermions * 10.7. Two-Level Systems and Pauli Matrices * 11. Quantum Fields * 11.1 Kinds of Quantum Field * 11.2 Coherence and Correlation Functions * 12. Atoms, Light and their Interaction * 12.1. Interaction with the Quantized Radiation Field * 12.2. Decay of an Excited Atom * 12.3. The Two-Level Atom in a Strong Classical Driving Field * 12.4. Interaction of a Two-Level Atom with a Single Mode * IV - QUANTUM STOCHASTIC PROCESSES * 13. Quantum Markov Processes * 13.1. Two-Level Atom in a Finite-Temperature Electromagnetic Field * 13.2. Derivation of theMaster Equation * 13.3. More General Heat Baths * 13.4. Quantum Correlation Functions and Spectra * 14. Applications of the Master Equation * 14.1. A Two-Level Atom Interacting with a Thermal Heat Bath * 14.2. The Two-Level Atom Driven by a Coherent Light Field * 14.3. Master Equations for Harmonic Oscillator Systems * 14.4. A Simple Model of Laser Cooling * V - PHASE SPACE METHODS * 15. Phase Space Representations for Bosons * 15.1. The Quantum Characteristic Function * 15.2. Phase Space Representations of the Density Operator * 16. Wigner Function Methods * 16.1. Operator Correspondences and Equations of Motion * 16.2. Damped and Driven Systems * 16.3. The Wigner Distribution Function f (x, p) * 16.4. Quantum Fluctuations in Equations of Motion * 17. P-Function Methods * 17.1. Introduction * 17.2. Artificial Neural Networks * 17.3. Clinical Example * VI - QUANTUM MEASUREMENT THEORY * 18. Foundations and Formalism of Quantum Measurement * 18.1. Formulations of Quantum Mechanics * 18.2. Modelling a Measurement-Tracks in a Cloud Chamber * 18.3. Formal Quantum Measurement Theory * 18.4. Multitime Measurements * 19. Continuous Measurements * 19.1. Photon Counting * 19.2. Wavefunction Interpretation of Continuous Measurement * 19.3. Application to Matter Wave Interference * 19.4. Damping of Quantum Coherence * 19.5. The Emergence of the oscopic World * 20. The Quantum Zeno Effect * 20.1. Theoretical Basis for the Quantum Zeno Effect * 20.2. A Quantum Model of Trapped Atoms * 20.3. Quantum Zeno Effect for a Bose-Einstein Condensate * References * Author Index * Subject Index

Gardiner, Crispin; Zoller, Peter

2014-03-01

463

Designing ideal conduits for peripheral nerve repair  

PubMed Central

Nerve tubes, guides, or conduits are a promising alternative for autologous nerve graft repair. The first biodegradable empty single lumen or hollow nerve tubes are currently available for clinical use and are being used mostly in the repair of small-diameter nerves with nerve defects of < 3 cm. These nerve tubes are made of different biomaterials using various fabrication techniques. As a result these tubes also differ in physical properties. In addition, several modifications to the common hollow nerve tube (for example, the addition of Schwann cells, growth factors, and internal frameworks) are being investigated that may increase the gap that can be bridged. This combination of chemical, physical, and biological factors has made the design of a nerve conduit into a complex process that demands close collaboration of bioengineers, neuroscientists, and peripheral nerve surgeons. In this article the authors discuss the different steps that are involved in the process of the design of an ideal nerve conduit for peripheral nerve repair. PMID:19435445

de Ruiter, Godard C. W.; Malessy, Martijn J. A.; Yaszemski, Michael J.; Windebank, Anthony J.; Spinner, Robert J.

2010-01-01

464

Dust Resuspension due to Idealized Foot Motion  

NASA Astrophysics Data System (ADS)

The air quality is affected by amount and types of particulate contaminants that are suspended in the air. The resuspension phenomena occur through two mechanisms: mechanical, where kinetic energy is transferred through direct contact from an impacting body or a vibrating surface, and aerodynamic, where dust particles are resuspended by the flow disturbance generated by the body. In this presentation we focus on aerodynamic resuspension of particles caused by walking. The foot movement is idealized and is either towards or away from a floor without touching it. As a first approach, a 15 cm diameter disk having the equivalent area to that of a human foot is used. The ``foot'' movement is driven vertically by a linear servo motor that controls the velocity, acceleration, stroke and deceleration (a typical vertical velocity is 0.5-1.0 m/s). A thin layer of dust is spread on a table relative to which the disk is allowed to move up and down. Flow visualizations show that both the upward and downward movements of the disk play an important role in the dust resuspension. A clear effect of radial jet and vortex dynamics on the particle resuspension is observed during the downward motion. In the wake of the rising disk, the particles were entrained upwards as a starting ring vortex formed. Quantitative PIV measurements will be performed to help further analyze the flow structure of this flow configuration.

Sheth, Ritesh

2005-11-01

465

Ideal bandpasses for type Ia supernova cosmology  

SciTech Connect

To use type Ia supernovae as standard candles for cosmologywe need accurate broadband magnitudes. In practice the observed magnitudemay differ from the ideal magnitude-redshift relationship either throughintrinsic inhomogeneities in the type Ia supernova population or throughobservational error. Here we investigate how we can choose filterbandpasses to reduce the error caused by both these effects. We find thatbandpasses with large integral fluxes and sloping wings are best able tominimise several sources of observational error, and are also leastsensitive to intrinsic differences in type Ia supernovae. The mostimportant feature of a complete filter set for type Ia supernovacosmology is that each bandpass be a redshifted copy of the first. Wedesign practical sets of redshifted bandpasses that are matched totypical high resistivity CCD and HgCdTe infra-red detector sensitivities.These are designed to minimise systematic error in well observedsupernovae, final designs for specific missions should also considersignal-to-noise requirements and observing strategy. In addition wecalculate how accurately filters need to be calibrated in order toachieve the required photometric accuracy of future supernova cosmologyexperiments such as the SuperNova-Acceleration-Probe (SNAP), which is onepossible realisation of the Joint Dark-Energy mission (JDEM). We considerthe effect of possible periodic miscalibrations that may arise from theconstruction of an interference filter.

Davis, Tamara M.; Schmidt, Brian P.; Kim, Alex G.

2005-10-24

466

Ideal Structure in Free Semigroupoid Algebras from Directed Graphs  

Microsoft Academic Search

A free semigroupoid algebra is the weak operator topology closed algebra\\u000agenerated by the left regular representation of a directed graph. We establish\\u000alattice isomorphisms between ideals and invariant subspaces, and this leads to\\u000aa complete description of the weak operator topology closed ideal structure for\\u000athese algebras. We prove a distance formula to ideals, and this gives an\\u000aappropriate

Michael T. Jury; David W. Kribs

2003-01-01

467

The significance of the Hansen Ideal space frame  

NASA Astrophysics Data System (ADS)

Known and unknown properties of Hansen Ideal coordinates are summarized. It is shown that the ideal space frame is a general and necessary component of basic celestial mechanics and astrodynamics, as well as of any theory of motion. A typical consequence is the intimate correlation of the Hansen frame with the Lagrange constraint within the method of the variation of the parameters. The use of observations in the ideal frame may allow conclusions on the intergalactic fundamental coordinate system.

Jochim, E. F. M.

2012-10-01

468

Why Education in Public Schools Should Include Religious Ideals  

Microsoft Academic Search

This article aims to open a new line of debate about religion in public schools by focusing on religious ideals. The article\\u000a begins with an elucidation of the concept ‘religious ideals’ and an explanation of the notion of reasonable pluralism, in\\u000a order to be able to explore the dangers and positive contributions of religious ideals and their pursuit on a

Doret J. de Ruyter; Michael S. Merry

2009-01-01

469

Unconditional Room Temperature Quantum Memory  

E-print Network

Just as classical information systems require buffers and memory, the same is true for quantum information systems. The potential that optical quantum information processing holds for revolutionising computation and communication is therefore driving significant research into developing optical quantum memory. A practical optical quantum memory must be able to store and recall quantum states on demand with high efficiency and low noise. Ideally, the platform for the memory would also be simple and inexpensive. Here, we present a complete tomographic reconstruction of quantum states that have been stored in the ground states of rubidium in a vapour cell operating at around 80$^o$C. Without conditional measurements, we show recall fidelity up to 98% for coherent pulses containing around one photon. In order to unambiguously verify that our memory beats the quantum no-cloning limit we employ state independent verification using conditional variance and signal transfer coefficients.

M. Hosseini; G. Campbell; B. M. Sparkes; P. K. Lam; B. C. Buchler

2015-02-10

470

Idealized Computational Models for Auditory Receptive Fields  

PubMed Central

We present a theory by which idealized models of auditory receptive fields can be derived in a principled axiomatic manner, from a set of structural properties to (i) enable invariance of receptive field responses under natural sound transformations and (ii) ensure internal consistency between spectro-temporal receptive fields at different temporal and spectral scales. For defining a time-frequency transformation of a purely temporal sound signal, it is shown that the framework allows for a new way of deriving the Gabor and Gammatone filters as well as a novel family of generalized Gammatone filters, with additional degrees of freedom to obtain different trade-offs between the spectral selectivity and the temporal delay of time-causal temporal window functions. When applied to the definition of a second-layer of receptive fields from a spectrogram, it is shown that the framework leads to two canonical families of spectro-temporal receptive fields, in terms of spectro-temporal derivatives of either spectro-temporal Gaussian kernels for non-causal time or a cascade of time-causal first-order integrators over the temporal domain and a Gaussian filter over the logspectral domain. For each filter family, the spectro-temporal receptive fields can be either separable over the time-frequency domain or be adapted to local glissando transformations that represent variations in logarithmic frequencies over time. Within each domain of either non-causal or time-causal time, these receptive field families are derived by uniqueness from the assumptions. It is demonstrated how the presented framework allows for computation of basic auditory features for audio processing and that it leads to predictions about auditory receptive fields with good qualitative similarity to biological receptive fields measured in the inferior colliculus (ICC) and primary auditory cortex (A1) of mammals. PMID:25822973

Lindeberg, Tony; Friberg, Anders

2015-01-01

471

Quantum Gibbs ensemble Monte Carlo  

E-print Network

We present a path integral Monte Carlo method which is the full quantum analogue of the Gibbs ensemble Monte Carlo method of Panagiotopoulos to study the gas-liquid coexistence line of a classical fluid. Unlike previous extensions of Gibbs ensemble Monte Carlo to include quantum effects, our scheme is viable even for systems with strong quantum delocalization in the degenerate regime of temperature. This is demonstrated by an illustrative application to the gas-superfluid transition of $^4$He in two dimensions.

Riccardo Fantoni; Saverio Moroni

2014-08-24

472

Initialization and readout of spin chains for quantum information transport  

Microsoft Academic Search

Linear chains of spins acting as quantum wires are a promising approach for achieving scalable quantum information processors. Nuclear spins in apatite crystals provide an ideal test bed for the experimental study of quantum information transport, as they closely emulate a one-dimensional spin chain, while magnetic resonance techniques can be used to drive the spin chain dynamics and probe the

Gurneet Kaur; Paola Cappellaro

2012-01-01

473

Quantum logic with an indium-magnesium ion chain  

Microsoft Academic Search

Summary form only given. A chain of ions in a linear trap is ideally suited to process quantum information. Two long-lived internal states in each ion store the quantum bits, which may be coupled by means of the collective vibrational excitation of the chain. A prerequisite for realizing even the simplest two-bit quantum gate is cooling the vibrational degrees of

S. Kohler; W. Lange; V. Ludsteck; G. Morigi; E. Peik; H. Walther

2000-01-01

474

Tonks-Girardeau gas of ultracold atoms in an optical lattice.  

PubMed

Strongly correlated quantum systems are among the most intriguing and fundamental systems in physics. One such example is the Tonks-Girardeau gas, proposed about 40 years ago, but until now lacking experimental realization; in such a gas, the repulsive interactions between bosonic particles confined to one dimension dominate the physics of the system. In order to minimize their mutual repulsion, the bosons are prevented from occupying the same position in space. This mimics the Pauli exclusion principle for fermions, causing the bosonic particles to exhibit fermionic properties. However, such bosons do not exhibit completely ideal fermionic (or bosonic) quantum behaviour; for example, this is reflected in their characteristic momentum distribution. Here we report the preparation of a Tonks-Girardeau gas of ultracold rubidium atoms held in a two-dimensional optical lattice formed by two orthogonal standing waves. The addition of a third, shallower lattice potential along the long axis of the quantum gases allows us to enter the Tonks-Girardeau regime by increasing the atoms' effective mass and thereby enhancing the role of interactions. We make a theoretical prediction of the momentum distribution based on an approach in which trapped bosons acquire fermionic properties, finding that it agrees closely with the measured distribution. PMID:15152247

Paredes, Belén; Widera, Artur; Murg, Valentin; Mandel, Olaf; Fölling, Simon; Cirac, Ignacio; Shlyapnikov, Gora V; Hänsch, Theodor W; Bloch, Immanuel

2004-05-20

475

Molecular structure and conformation of 1,3,5-tris(trifluoromethyl)-benzene as studied by gas-phase electron diffraction and quantum chemical calculations  

NASA Astrophysics Data System (ADS)

The molecular structure of 1,3,5-tris(trifluoromethyl)benzene (1,3,5-TTFB) was studied by gas-phase electron diffraction (GED) and quantum chemical calculations (B3LYP method with 6-31G(d,p) basis set and MP2 method with cc-pVTZ basis set). The best fit of the experimental scattering intensities (RG = 4.0%) was obtained for the structure of CS symmetry. The differences between some geometric parameters were constrained at the values calculated at the MP2/cc-pVTZ level. The principal structural parameters rh1(?h1) determined by GED are (bond lengths in Angstroms and bond angles in degrees with 3? in parentheses): r(Cdbnd C) = 1.392(4), r(Csbnd C)=1.512(4), r(Csbnd F)av = 1.346(2), ?Csbnd C(CF3)sbnd C = 120.9(2), ?Csbnd C(H)sbnd C = 119.1(2), ?(Csbnd Csbnd F)av = 111.6(2). The structure of the carbon ring deviates from a regular hexagon due to the ?-electronegative effect of the CF3 groups. The geometric parameters of the trifluoromethyl groups deviate considerably from regular tetrahedron arrangement. The experimental structural parameters agree well with the results of B3LYP/6-31G(d,p) and MP2/cc-pVTZ calculations. The electron diffraction data are in agreement with nearly free rotation of the CF3 groups around Cmethylsbnd Cphenyl axis.

Kolesnikova, Inna N.; Dorofeeva, Olga V.; Karasev, Nikolay M.; Oberhammer, Heinz; Shishkov, Igor F.

2014-09-01

476

A Graph Theoretic Method for Determining Generating Sets of Prime Ideals in O_q(M_{m,n}(C))  

E-print Network

We take a graph theoretic approach to the problem of finding generators for those prime ideals of O_q(M_{m,n}(C)) which are invariant under the torus action (C*)^{m+n-1}. Launois has shown that the generators consist of certain quantum minors of the matrix of canonical generators of O_q(M_{m,n}(C)) and has given an algorithm to find them. In this paper we modify a classic result of Lindstr\\"om and Gessel-Viennot to show that a quantum minor is in the generating set for a particular ideal if and only if we can find a particular set of vertex-disjoint directed paths in an associated directed graph.

Casteels, Karel

2009-01-01