Candidate Elastic Quantum Critical Point in LaCu_{6-x}Au_{x}.
Poudel, L; May, A F; Koehler, M R; McGuire, M A; Mukhopadhyay, S; Calder, S; Baumbach, R E; Mukherjee, R; Sapkota, D; de la Cruz, C; Singh, D J; Mandrus, D; Christianson, A D
2016-12-02
The structural properties of LaCu_{6-x}Au_{x} are studied using neutron diffraction, x-ray diffraction, and heat capacity measurements. The continuous orthorhombic-monoclinic structural phase transition in LaCu_{6} is suppressed linearly with Au substitution until a complete suppression of the structural phase transition occurs at the critical composition x_{c}=0.3. Heat capacity measurements at low temperatures indicate residual structural instability at x_{c}. The instability is ferroelastic in nature, with density functional theory calculations showing negligible coupling to electronic states near the Fermi level. The data and calculations presented here are consistent with the zero temperature termination of a continuous structural phase transition suggesting that the LaCu_{6-x}Au_{x} series hosts an elastic quantum critical point.
UNCOVERING THE NUCLEUS CANDIDATE FOR NGC 253
Energy Technology Data Exchange (ETDEWEB)
Günthardt, G. I.; Camperi, J. A. [Observatorio Astronómico, Universidad Nacional de Córdoba (Argentina); Agüero, M. P. [Observatorio Astronómico, Universidad Nacional de Córdoba, and CONICET (Argentina); Díaz, R. J.; Gomez, P. L.; Schirmer, M. [Gemini Observatory, AURA (United States); Bosch, G., E-mail: gunth@oac.uncor.edu, E-mail: camperi@oac.uncor.edu, E-mail: mpaguero@oac.uncor.edu, E-mail: rdiaz@gemini.edu, E-mail: pgomez@gemini.edu, E-mail: mschirmer@gemini.edu, E-mail: guille@fcaglp.unlp.edu.ar [Instituto de Astrofísica de La Plata (CONICET-UNLP) (Argentina)
2015-11-15
NGC 253 is the nearest spiral galaxy with a nuclear starburst that becomes the best candidate for studying the relationship between starburst and active galactic nucleus activity. However, this central region is veiled by large amounts of dust, and it has been so far unclear which is the true dynamical nucleus to the point that there is no strong evidence that the galaxy harbors a supermassive black hole co-evolving with the starburst as was supposed earlier. Near-infrared (NIR) spectroscopy, especially NIR emission line analysis, could be advantageous in shedding light on the true nucleus identity. Using Flamingos-2 at Gemini South we have taken deep K-band spectra along the major axis of the central structure and through the brightest infrared source. In this work, we present evidence showing that the brightest NIR and mid-infrared source in the central region, already known as radio source TH7 and so far considered just a large stellar supercluster, in fact presents various symptoms of a genuine galactic nucleus. Therefore, it should be considered a valid nucleus candidate. Mentioning some distinctive aspects, it is the most massive compact infrared object in the central region, located at 2.″0 of the symmetry center of the galactic bar, as measured in the K-band emission. Moreover, our data indicate that this object is surrounded by a large circumnuclear stellar disk and it is also located at the rotation center of the large molecular gas disk of NGC 253. Furthermore, a kinematic residual appears in the H{sub 2} rotation curve with a sinusoidal shape consistent with an outflow centered in the candidate nucleus position. The maximum outflow velocity is located about 14 pc from TH7, which is consistent with the radius of a shell detected around the nucleus candidate, observed at 18.3 μm (Qa) and 12.8 μm ([Ne ii]) with T-ReCS. Also, the Brγ emission line profile shows a pronounced blueshift and this emission line also has the highest equivalent width at this
Uncovering the nucleus candidate for NGC 253
Günthardt, G I; Camperi, J A; Díaz, R J; Gomez, P L; Bosch, G; Schirmer, M
2015-01-01
NGC253 is the nearest spiral galaxy with a nuclear starburst which becomes the best candidate to study the relationship between starburst and AGN activity. However, this central region is veiled by large amounts of dust, and it has been so far unclear which is the true dynamical nucleus. The near infrared spectroscopy could be advantageous in order to shed light on the true nucleus identity. Using Flamingos-2 at Gemini South we have taken deep K-band spectra along the major axis and through the brightest infrared source. We present evidence showing that the brightest near infrared and mid infrared source in the central region, already known as radio source TH7 and so far considered just a stellar supercluster, in fact, presents various symptoms of a genuine galactic nucleus. Therefore, it should be considered a valid nucleus candidate. It is the most massive compact infrared object in the central region, located at 2.0" of the symmetry center of the galactic bar. Moreover, our data indicate that this object i...
DEFF Research Database (Denmark)
Jensen, Ole B.; Morelli, Nicola
2011-01-01
where the networks meet and establish contact. Thus we argue for the usefulness of the notion of Critical Point of Contact (CPC) to deepen our understanding of the actual life within networks. En route to this notion we draw upon theories within as diverse realms such as interaction design, service...
DEFF Research Database (Denmark)
2012-01-01
In this brief article, we shall illustrate the application of the analytical and interventionist concept of ‘Critical Points of Contact’ (CPC) through a number of urban design studios. The notion of CPC has been developed over a span of the last three to four years and is reported in more detail...
Finding critical points whose polarization is also a critical point
Squassina, Marco; Van Schaftingen, Jean
2011-01-01
We show that near any given minimizing sequence of paths for the mountain pass lemma, there exists a critical point whose polarization is also a critical point. This is motivated by the fact that if any polarization of a critical point is also a critical point and the Euler-Lagrange equation is a second-order semi-linear elliptic problem, T. Bartsch, T. Weth and M. Willem (J. Anal. Math., 2005) have proved that the critical point is axially symmetric.
DEFF Research Database (Denmark)
Jensen, Ole B.; Morelli, Nicola
2011-01-01
where the networks meet and establish contact. Thus we argue for the usefulness of the notion of Critical Point of Contact (CPC) to deepen our understanding of the actual life within networks. En route to this notion we draw upon theories within as diverse realms such as interaction design, service...... design, geography, and mobility studies. After the introduction in section we develop and define the notion of CPC based upon a broad set of disciplines and theories. We illustrate the usefulness of the notion within the field of mobility in the network city and within the field of service design...
Directory of Open Access Journals (Sweden)
Debra Lewis
2013-05-01
Full Text Available Relative equilibria of Lagrangian and Hamiltonian systems with symmetry are critical points of appropriate scalar functions parametrized by the Lie algebra (or its dual of the symmetry group. Setting aside the structures – symplectic, Poisson, or variational – generating dynamical systems from such functions highlights the common features of their construction and analysis, and supports the construction of analogous functions in non-Hamiltonian settings. If the symmetry group is nonabelian, the functions are invariant only with respect to the isotropy subgroup of the given parameter value. Replacing the parametrized family of functions with a single function on the product manifold and extending the action using the (coadjoint action on the algebra or its dual yields a fully invariant function. An invariant map can be used to reverse the usual perspective: rather than selecting a parametrized family of functions and finding their critical points, conditions under which functions will be critical on specific orbits, typically distinguished by isotropy class, can be derived. This strategy is illustrated using several well-known mechanical systems – the Lagrange top, the double spherical pendulum, the free rigid body, and the Riemann ellipsoids – and generalizations of these systems.
Lewis, Debra
2013-05-01
Relative equilibria of Lagrangian and Hamiltonian systems with symmetry are critical points of appropriate scalar functions parametrized by the Lie algebra (or its dual) of the symmetry group. Setting aside the structures - symplectic, Poisson, or variational - generating dynamical systems from such functions highlights the common features of their construction and analysis, and supports the construction of analogous functions in non-Hamiltonian settings. If the symmetry group is nonabelian, the functions are invariant only with respect to the isotropy subgroup of the given parameter value. Replacing the parametrized family of functions with a single function on the product manifold and extending the action using the (co)adjoint action on the algebra or its dual yields a fully invariant function. An invariant map can be used to reverse the usual perspective: rather than selecting a parametrized family of functions and finding their critical points, conditions under which functions will be critical on specific orbits, typically distinguished by isotropy class, can be derived. This strategy is illustrated using several well-known mechanical systems - the Lagrange top, the double spherical pendulum, the free rigid body, and the Riemann ellipsoids - and generalizations of these systems.
Uranium Critical Point Location Problem
Iosilevskiy, Igor
2013-01-01
Significant uncertainty of our present knowledge for uranium critical point parameters is under consideration. Present paper is devoted to comparative analysis of possible resolutions for the problem of uranium critical point location, as well as to discussion of plausible scheme of decisive experiment, which could resolve existing uncertainty. New calculations of gas-liquid coexistence in uranium by modern thermodynamic code are included in the analysis.
Critical points of metal vapors
Energy Technology Data Exchange (ETDEWEB)
Khomkin, A. L., E-mail: alhomkin@mail.ru; Shumikhin, A. S. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)
2015-09-15
A new method is proposed for calculating the parameters of critical points and binodals for the vapor–liquid (insulator–metal) phase transition in vapors of metals with multielectron valence shells. The method is based on a model developed earlier for the vapors of alkali metals, atomic hydrogen, and exciton gas, proceeding from the assumption that the cohesion determining the basic characteristics of metals under normal conditions is also responsible for their properties in the vicinity of the critical point. It is proposed to calculate the cohesion of multielectron atoms using well-known scaling relations for the binding energy, which are constructed for most metals in the periodic table by processing the results of many numerical calculations. The adopted model allows the parameters of critical points and binodals for the vapor–liquid phase transition in metal vapors to be calculated using published data on the properties of metals under normal conditions. The parameters of critical points have been calculated for a large number of metals and show satisfactory agreement with experimental data for alkali metals and with available estimates for all other metals. Binodals of metals have been calculated for the first time.
The Critical Point Facility (CPF)
1992-01-01
The Critical Point Facility (CPF) is an ESA multiuser facility designed for microgravity research onboard Spacelab. It has been conceived and built to offer investigators opportunities to conduct research on critical point phenomena in microgravity. This facility provides the high precision and stability temperature standards required in this field of research. It has been primarily designed for the purpose of optical investigations of transparent fluids. During a Spacelab mission, the CPF automatically processes several thermostats sequentially, each thermostat corresponding to an experiment. The CPF is now integrated in Spacelab at Kennedy Space Center, in preparation for the International Microgravity Lab. mission. The CPF was designed to submit transparent fluids to an adequate, user defined thermal scenario, and to monitor their behavior by using thermal and optical means. Because they are strongly affected by gravity, a good understanding of critical phenomena in fluids can only be gained in low gravity conditions. Fluids at the critical point become compressed under their own weight. The role played by gravity in the formation of interfaces between distinct phases is not clearly understood.
Interval Mathematics Applied to Critical Point Transitions
Stradi, Benito A.
2012-01-01
The determination of critical points of mixtures is important for both practical and theoretical reasons in the modeling of phase behavior, especially at high pressure. The equations that describe the behavior of complex mixtures near critical points are highly nonlinear and with multiplicity of solutions to the critical point equations. Interval arithmetic can be used to reliably locate all the critical points of a given mixture. The method also verifies the nonexistence of a critical point ...
Enhanced protein crystallization around the metastable critical point
Wolde, P.R. ten; Frenkel, D.
1999-01-01
We report on a computer-simulation study of homogeneous crystal nucleation in a model for globular proteins. We find that the presence of a metastable vapour-liquid critical point drastically changes the pathway for the formation of a critical nucleus. But what is more important, the large density f
Critical Point Symmetries in Nuclei
Bonatsos, D; Petrellis, D; Terziev, P A; Yigitoglu, I; Bonatsos, Dennis
2006-01-01
Critical Point Symmetries (CPS) appear in regions of the nuclear chart where a rapid change from one symmetry to another is observed. The first CPSs, introduced by F. Iachello, were E(5), which corresponds to the transition from vibrational [U(5)] to gamma-unstable [O(6)] behaviour, and X(5), which represents the change from vibrational [U(5)] to prolate axially deformed [SU(3)] shapes. These CPSs have been obtained as special solutions of the Bohr collective Hamiltonian. More recent special solutions of the same Hamiltonian, to be described here, include Z(5) and Z(4), which correspond to maximally triaxial shapes (the latter with ``frozen'' gamma=30 degrees), as well as X(3), which corresponds to prolate shapes with ``frozen'' gamma=0. CPSs have the advantage of providing predictions which are parameter free (up to overall scale factors) and compare well to experiment. However, their mathematical structure [with the exception of E(5)] needs to be clarified.
Correlations in avalanche critical points
Cerruti, Benedetta; Vives, Eduard
2009-07-01
Avalanche dynamics and related power-law statistics are ubiquitous in nature, arising in phenomena such as earthquakes, forest fires, and solar flares. Very interestingly, an analogous behavior is associated with many condensed-matter systems, such as ferromagnets and martensites. Bearing it in mind, we study the prototypical random-field Ising model at T=0 . We find a finite correlation between waiting intervals and the previous avalanche size. This correlation is not found in other models for avalanches but it is experimentally found in earthquakes and in forest fires. Our study suggests that this effect occurs in critical points that are at the end of a first-order discontinuity separating two regimes: one with high activity from another with low activity.
New candidate for deformed halo nucleus in Mg isotopes through analysis of reaction cross sections
Directory of Open Access Journals (Sweden)
Watanabe S.
2014-03-01
Full Text Available The total reaction cross sections of Mg isotopes on a 12C target at 240 MeV/nucleon have been analyzed with a fully microscopic framework, i.e., the double folding model with the density calculated by antisymmetrized molecular dynamics. Our results well reproduce the latest experimental data except 37Mg as a new candidate for a deformed halo nucleus.
Odd-Parity Superconductivity and the Ferromagnetic Quantum Critical Point
Huxley, A. D.; Yates, S. J. C.; Lévy, F.; Sheikin, I.
2007-05-01
The study of the emergence of superconductivity close to quantum critical points affords a powerful means to identify the mechanism that drives the formation of unconventional superconductivity in heavy fermion materials. The recent discovery of superconducting states close to quantum critical points in ferromagnets UGe2 and URhGe is reviewed in this light. For URhGe we examine whether the predominant type of magnetic excitations involved are longitudinal excitations, hitherto considered theoretically to be the most promising candidate to mediate equal-spin-paired superconductivity.
Critical point fluctuations in supported lipid membranes.
Connell, Simon D; Heath, George; Olmsted, Peter D; Kisil, Anastasia
2013-01-01
In this paper, we demonstrate that it is possible to observe many aspects of critical phenomena in supported lipid bilayers using atomic force microscopy (AFM) with the aid of stable and precise temperature control. The regions of criticality were determined by accurately measuring and calculating phase diagrams for the 2 phase L(d)-L(o) region, and tracking how it moves with temperature, then increasing the sampling density around the estimated critical regions. Compositional fluctuations were observed above the critical temperature (T(c)) and characterised using a spatial correlation function. From this analysis, the phase transition was found to be most closely described by the 2D Ising model, showing it is a critical transition. Below T(c) roughening of the domain boundaries occurred due to the reduction in line tension close to the critical point. Smaller scale density fluctuations were also detected just below T(c). At T(c), we believe we have observed fluctuations on length scales greater than 10 microm. The region of critically fluctuating 10-100 nm nanodomains has been found to extend a considerable distance above T(c) to temperatures within the biological range, and seem to be an ideal candidate for the actual structure of lipid rafts in cell membranes. Although evidence for this idea has recently emerged, this is the first direct evidence for nanoscale domains in the critical region.
Critical-Point Structure in Finite Nuclei
Leviatan, A
2006-01-01
Properties of quantum shape-phase transitions in finite nuclei are considered in the framework of the interacting boson model. Special emphasis is paid to the dynamics at the critical-point of a general first-order phase transition.
Critical point wetting drop tower experiment
Kaukler, W. F.; Tcherneshoff, L. M.; Straits, S. R.
1984-01-01
Preliminary results for the Critical Point Wetting CPW Drop Tower Experiment are produced with immiscible systems. Much of the observed phenomena conformed to the anticipated behavior. More drops will be needed to test the CPW theory with these immiscible systems.
124Te and the E(5) Critical Point Symmetry
Ghiţă, D. G.; Căta-Danil, G.; Bucurescu, D.; Căta-Danil, I.; Ivascu, M.; Mihai, C.; Suliman, G.; Stroe, L.; Sava, T.; Zamfir, N. V.
We present a new study of the low-lying states in 124Te nucleus by γ-ray spectroscopy following 124I β+/ɛ decay. The β radioactive sources were produced in the 124Te(p, n)124I reaction induced by 11 MeV protons, delivered by the Bucharest FN Tandem Accelerator. The γ-rays were measured in a low background area with three large volume HPGe detectors. A total number of 276 milion double coincidence events were recorded in a six-day run. Most of the gamma line intensities previously measured were confirmed with improved accuracy and several gamma lines were obtained for the first time. Our results, combined with those from a recent (n, γ) study are compared with the predictions of the E(5) critical point symmetry model and numerical IBA-1 model calculations at the critical point of the U(5)-O(6) phase transition.
Fermion-induced quantum critical points.
Li, Zi-Xiang; Jiang, Yi-Fan; Jian, Shao-Kai; Yao, Hong
2017-08-22
A unified theory of quantum critical points beyond the conventional Landau-Ginzburg-Wilson paradigm remains unknown. According to Landau cubic criterion, phase transitions should be first-order when cubic terms of order parameters are allowed by symmetry in the Landau-Ginzburg free energy. Here, from renormalization group analysis, we show that second-order quantum phase transitions can occur at such putatively first-order transitions in interacting two-dimensional Dirac semimetals. As such type of Landau-forbidden quantum critical points are induced by gapless fermions, we call them fermion-induced quantum critical points. We further introduce a microscopic model of SU(N) fermions on the honeycomb lattice featuring a transition between Dirac semimetals and Kekule valence bond solids. Remarkably, our large-scale sign-problem-free Majorana quantum Monte Carlo simulations show convincing evidences of a fermion-induced quantum critical points for N = 2, 3, 4, 5 and 6, consistent with the renormalization group analysis. We finally discuss possible experimental realizations of the fermion-induced quantum critical points in graphene and graphene-like materials.Quantum phase transitions are governed by Landau-Ginzburg theory and the exceptions are rare. Here, Li et al. propose a type of Landau-forbidden quantum critical points induced by gapless fermions in two-dimensional Dirac semimetals.
Critical Points in Distance Learning System
Directory of Open Access Journals (Sweden)
Airina Savickaitė
2013-08-01
Full Text Available Purpose – This article presents the results of distance learning system analysis, i.e. the critical elements of the distance learning system. The critical points of distance learning are a part of distance education online environment interactivity/community process model. The most important is the fact that the critical point is associated with distance learning participants. Design/methodology/approach – Comparative review of articles and analysis of distance learning module. Findings – A modern man is a lifelong learner and distance learning is a way to be a modern person. The focus on a learner and feedback is the most important thing of learning distance system. Also, attention should be paid to the lecture-appropriate knowledge and ability to convey information. Distance system adaptation is the way to improve the learner’s learning outcomes. Research limitations/implications – Different learning disciplines and learning methods may have different critical points. Practical implications – The information of analysis could be important for both lecturers and students, who studies distance education systems. There are familiar critical points which may deteriorate the quality of learning. Originality/value – The study sought to develop remote systems for applications in order to improve the quality of knowledge. Keywords: distance learning, process model, critical points. Research type: review of literature and general overview.
Controlling superconductivity by tunable quantum critical points.
Seo, S; Park, E; Bauer, E D; Ronning, F; Kim, J N; Shim, J-H; Thompson, J D; Park, Tuson
2015-03-04
The heavy fermion compound CeRhIn5 is a rare example where a quantum critical point, hidden by a dome of superconductivity, has been explicitly revealed and found to have a local nature. The lack of additional examples of local types of quantum critical points associated with superconductivity, however, has made it difficult to unravel the role of quantum fluctuations in forming Cooper pairs. Here, we show the precise control of superconductivity by tunable quantum critical points in CeRhIn5. Slight tin-substitution for indium in CeRhIn5 shifts its antiferromagnetic quantum critical point from 2.3 GPa to 1.3 GPa and induces a residual impurity scattering 300 times larger than that of pure CeRhIn5, which should be sufficient to preclude superconductivity. Nevertheless, superconductivity occurs at the quantum critical point of the tin-doped metal. These results underline that fluctuations from the antiferromagnetic quantum criticality promote unconventional superconductivity in CeRhIn5.
Pions near the chiral critical point
Hippert, M.; Fraga, E. S.; Santos, E. M.
2016-04-01
It is an exciting possibility that the QCD critical point can be found in ultrarelativistic heavy-ion collision experiments (HICs). While quantities such as some event-by-event moments of specific observables should display strong non-monotonic behavior near the critical point and could, hence, be used as signatures of criticality, it is not clear that this behavior could effectively be observed in the highly non-ideal scenario of HICs. We here employ Monte Carlo simulations to test second-order moments of pion observables as possible signatures of the critical point while taking into account some realistic ingredients, similar to the ones found in HICs. We make use of simplified models to introduce spurious contributions and dynamical effects.
Critical Point Theory for Lagrangian Systems
Mazzucchelli, Marco
2012-01-01
Lagrangian systems constitute a very important and old class in dynamics. Their origin dates back to the end of the eighteenth century, with Joseph-Louis Lagrange's reformulation of classical mechanics. The main feature of Lagrangian dynamics is its variational flavor: orbits are extremal points of an action functional. The development of critical point theory in the twentieth century provided a powerful machinery to investigate existence and multiplicity questions for orbits of Lagrangian systems. This monograph gives a modern account of the application of critical point theory, and more spec
QCD critical point: The race is on
Indian Academy of Sciences (India)
Rajiv V Gavai
2015-05-01
A critical point in the phase diagram of quantum chromodynamics (QCD), if established either theoretically or experimentally, would be as profound a discovery as the good-old gas–liquid critical point. Unlike the latter, however, first-principles-based approaches are being employed to locate it theoretically. Due to the short-lived nature of the concerned phases, novel experimental techniques are needed to search for it. The Relativistic Heavy Ion Collider (RHIC) in USA has an experimental programme to do so. This short review is an attempt to provide a glimpse of the race between the theorists and the experimentalists as well as the synergy between them.
Critical point of view: a Wikipedia reader
Lovink, G.; Tkacz, N.
2011-01-01
For millions of internet users around the globe, the search for new knowledge begins with Wikipedia. The encyclopedia’s rapid rise, novel organization, and freely offered content have been marveled at and denounced by a host of commentators. Critical Point of View moves beyond unflagging praise, wel
Critical points in Lovelock Black Holes
Frassino, Antonia M; Simovic, Fil
2016-01-01
We review some of the results obtained by introducing a thermodynamic pressure via the cosmological constant in a class of higher curvature theories known as Lovelock gravity. In particular, we focus on a specific relation between the higher-order Lovelock couplings that introduces a peculiar isolated critical point for hyperbolic black holes characterized by non-standard critical exponents.
Nonionic reverse micelles near the critical point.
Shrestha, Lok Kumar; Shrestha, Rekha Goswami
2013-01-01
We report shape, size, and internal cross-sectional structure of diglycerol monomyristate (C₁₄G₂) reverse micelles in n-hexadecane near the critical point using small-angle X-ray scattering (SAXS). Pair-distance distribution function, p(r), which gives structural information in real-space, was obtained by indirect Fourier transformation (IFT) method. The p(r) showed a clear picture of rodlike micelles at higher temperatures well above the critical point (micellar solution phase separates into two immiscible liquids at ~ 48°C). At a fixed surfactant concentration (5% C₁₄G₂), decrease in temperature increases the micellar size monotonously and surprisingly shape of the p(r) curve at 50°C; close to the critical point, mimics the shape of the two dimensional disk-like micelles indicating the onset of critical fluctuations (attractive interactions among rodlike micelles forming a weak network). A similar behavior has been observed with normal micelles in aqueous system near the critical point. When the system is heated to 60°C, shape of the p(r) curve regains rodlike structure. At fixed temperature of 60°C, increase in C₁₄G₂ concentration induced one dimensional micellar growth. Maximum length of micelles increases from ca. 23.5 to 46.0 nm upon increasing concentration from 1 to 12% keeping cross section diameter apparently unchanged at ca. 4.0 nm.
Critical dynamics near QCD critical point
Minami, Yuki
2012-01-01
In this thesis, we study the critical dynamics near the QCD critical point. Near the critical point, the relevant modes for the critical dynamics are identified as the hydrodynamic modes. Thus, we first study the linear dynamics of them by the relativistic hydrodynamics. We show that the thermal diffusion mode is the most relevant mode, whereas the sound mode is suppressed around the critical point. We also find that the Landau equation, which is believed to be an acausal hydrodynamic equation, has no problem to describe slowly varying fluctuations. Moreover, we find that the Israel-Stewart equation, which is a causal one, gives the same result as the Landau equation gives in the long-wavelength region. Next, we study the nonlinear dynamics of the hydrodynamic modes by the nonlinear Langevin equation and the dynamic renormalization group (RG). In the vicinity of the critical point, the usual hydrodynamics breaks down by large fluctuations. Thus, we must consider the nonlinear Langevin equation. We construct t...
A CANDIDATE DUAL ACTIVE GALACTIC NUCLEUS AT z = 1.175
Energy Technology Data Exchange (ETDEWEB)
Scott Barrows, R. [Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, AR 72701 (United States); Stern, Daniel; Assef, Roberto J.; Cushing, Michael C. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Madsen, Kristin; Harrison, Fiona [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Comerford, Julia M. [Astronomy Department, University of Texas at Austin, Austin, TX 78712 (United States); Fassnacht, Christopher D.; Lagattuta, David J. [Department of Physics, University of California at Davis, One Shields Avenue, Davis, CA 95616 (United States); Gonzalez, Anthony H. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Griffith, Roger; Davy Kirkpatrick, J. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Hickox, Ryan, E-mail: rbarrows@uark.edu [Department of Physics, Durham University, Durham DHI 3LE (United Kingdom)
2012-01-01
The X-ray source CXOXBJ142607.6+353351 (CXOJ1426+35), which was identified in a 172 ks Chandra image in the Booetes field, shows double-peaked rest-frame optical/UV emission lines, separated by 0.''69 (5.5 kpc) in the spatial dimension and by 690 km s{sup -1} in the velocity dimension. The high excitation lines and emission line ratios indicate both systems are ionized by an active galactic nucleus (AGN) continuum, and the double-peaked profile resembles that of candidate dual AGNs. At a redshift of z = 1.175, this source is the highest redshift candidate dual AGN yet identified. However, many sources have similar emission line profiles for which other interpretations are favored. We have analyzed the substantial archival data available in this field as well as acquired near-infrared (NIR) adaptive optics (AO) imaging and NIR slit spectroscopy. The X-ray spectrum is hard, implying a column density of several 10{sup 23} cm{sup -2}. Though heavily obscured, the source is also one of the brightest in the field, with an absorption-corrected 2-10 keV luminosity of {approx}10{sup 45} erg s{sup -1}. Outflows driven by an accretion disk may produce the double-peaked lines if the central engine accretes near the Eddington limit. However, we may be seeing the narrow line regions of two AGNs following a galactic merger. While the AO image reveals only a single source, a second AGN would easily be obscured by the significant extinction inferred from the X-ray data. Understanding the physical processes producing the complex emission line profiles seen in CXOJ1426+35 and related sources is important for interpreting the growing population of dual AGN candidates.
Shape phase mixing in critical point nuclei
Budaca, R
2016-01-01
Spectral properties of nuclei near the critical point of the quantum phase transition between spherical and axially symmetric shapes are studied in a hybrid collective model which combines the $\\gamma$-stable and $\\gamma$-rigid collective conditions through a rigidity parameter. The model in the lower and upper limits of the rigidity parameter recovers the X(5) and X(3) solutions respectively, while in the equally mixed case it corresponds to the X(4) critical point symmetry. Numerical applications of the model on nuclei from regions known for critical behavior reveal a sizable shape phase mixing and its evolution with neutron or proton numbers. The model also enables a better description of energy spectra and electromagnetic transitions for these nuclei.
Correlation Probes of a QCD Critical Point
Csörgö, T
2009-01-01
Critical opalescence is a characteristic experimental signature of a second order phase transition in solid state physics. A new, experimentally accessible measure of opacity and of attenuation length in heavy ion reactions is suggested, as a combination of HBT radii and nuclear modification factors. This opacity is maximal when $\\sqrt{s_{NN}}$, the system size and centrality correspond to the critical point of QCD. To characterize the phase transition at this critical point, the critical exponent of the correlation function can be determined by measuring the L\\'evy index of stability of the Bose-Einstein or HBT correlations. The exponent of the correlation length can be determined from fits to the multiplicity distribution in various pseudorapidity intervals, also as a function of colliding energy, system size, centrality and (chemical) freeze-out temperature. These two critical exponents determine the remaining four critical exponents and the universality class of this second order phase transition. As a co...
Quantum critical points in quantum impurity systems
Energy Technology Data Exchange (ETDEWEB)
Lee, Hyun Jung [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg (Germany); Bulla, Ralf [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg (Germany)]. E-mail: bulla@cpfs.mpg.de
2005-04-30
The numerical renormalization group method is used to investigate zero-temperature phase transitions in quantum impurity systems, in particular in the soft-gap Anderson model, where an impurity couples to a non-trivial fermionic bath. In this case, zero-temperature phase transitions occur between two different phases whose fixed points can be built up of non-interacting single-particle states. However, the quantum critical point cannot be described by non-interacting fermionic or bosonic excitations.
Quantum critical points in quantum impurity systems
Lee, Hyun Jung; Bulla, Ralf
2005-04-01
The numerical renormalization group method is used to investigate zero-temperature phase transitions in quantum impurity systems, in particular in the soft-gap Anderson model, where an impurity couples to a non-trivial fermionic bath. In this case, zero-temperature phase transitions occur between two different phases whose fixed points can be built up of non-interacting single-particle states. However, the quantum critical point cannot be described by non-interacting fermionic or bosonic excitations.
Mielczarek, Jakub
2014-01-01
This essay addresses the issue of gravitational phase transitions in the early universe. We suggest that a second order phase transition observed in the Causal Dynamical Triangulations approach to quantum gravity may have a cosmological relevance. The phase transition interpolates between a non-geometric crumpled phase of gravity, and an extended phase with classical properties. Transitions of this kind have been postulated earlier in the context of geometrogenesis in Quantum Graphity. We show that critical behavior may also be associated with a signature change event in Loop Quantum Cosmology. In both cases, classical spacetime originates at the critical point associated with a second order phase transition.
Critical point anomalies include expansion shock waves
Energy Technology Data Exchange (ETDEWEB)
Nannan, N. R., E-mail: ryan.nannan@uvs.edu [Mechanical Engineering Discipline, Anton de Kom University of Suriname, Leysweg 86, PO Box 9212, Paramaribo, Suriname and Process and Energy Department, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Guardone, A., E-mail: alberto.guardone@polimi.it [Department of Aerospace Science and Technology, Politecnico di Milano, Via La Masa 34, 20156 Milano (Italy); Colonna, P., E-mail: p.colonna@tudelft.nl [Propulsion and Power, Delft University of Technology, Kluyverweg 1, 2629 HS Delft (Netherlands)
2014-02-15
From first-principle fluid dynamics, complemented by a rigorous state equation accounting for critical anomalies, we discovered that expansion shock waves may occur in the vicinity of the liquid-vapor critical point in the two-phase region. Due to universality of near-critical thermodynamics, the result is valid for any common pure fluid in which molecular interactions are only short-range, namely, for so-called 3-dimensional Ising-like systems, and under the assumption of thermodynamic equilibrium. In addition to rarefaction shock waves, diverse non-classical effects are admissible, including composite compressive shock-fan-shock waves, due to the change of sign of the fundamental derivative of gasdynamics.
Correlated fluctuations near the QCD critical point
Jiang, Lijia; Song, Huichao
2015-01-01
In this paper, we introduce a freeze-out scheme for the dynamical models near the QCD critical point through coupling the decoupled classical particles with the order parameter field. With a modified distribution function that satisfies specific static fluctuations, we calculate the correlated fluctuations of net protons on the hydrodynamic freeze-out surface. A comparison with recent STAR data shows that our model calculations could roughly reproduce energy dependent cumulant $C_4$ and $\\kappa \\sigma^2$ of net protons through tuning the related parameters. However, the calculated $C_2$ and $C_3$ with both Poisson and Binomial baselines are always above the experimental data due to the positive contributions from the static critical fluctuations. In order to qualitatively and quantitatively describe the experimental data, the dynamical critical fluctuations and more realistic non-critical fluctuation baselines should be investigated in the near future.
QCD Critical Point in a Quasiparticle Model
Srivastava, P K; Singh, C P
2010-01-01
Recent theoretical investigations have unveiled a rich structure in the quantum chromodynamics (QCD) phase diagram which consists of quark gluon plasma (QGP) and the hadronic phases but also supports the existence of a cross-over transition ending at a critical end point (CEP). We find a too large variation in determination of the coordinates of the CEP in the temperature (T), baryon chemical potential ($\\mu_{B}$) plane and, therefore, its identification in the current heavy-ion experiments becomes debatable. Here we use an equation of state (EOS) for a deconfined QGP using a thermodynamically consistent quasiparticle model involving quarks and gluons having thermal masses. We further use a thermodynamically consistent excluded volume model for the hadron gas (HG) which was recently proposed by us. Using these equations of state, a first order deconfining phase transition is constructed using Gibbs' criteria. This leads to an interesting finding that the phase transition line ends at a critical point (CEP) be...
Dynamical response near quantum critical points
Lucas, Andrew; Podolsky, Daniel; Witczak-Krempa, William
2016-01-01
We study high frequency response functions, notably the optical conductivity, in the vicinity of quantum critical points (QCPs) by allowing for both detuning from the critical coupling and finite temperature. We consider general dimensions and dynamical exponents. This leads to a unified understanding of sum rules. In systems with emergent Lorentz invariance, powerful methods from conformal field theory allow us to fix the high frequency response in terms of universal coefficients. We test our predictions analytically in the large-N O(N) model and using the gauge-gravity duality, and numerically via Quantum Monte Carlo simulations on a lattice model hosting the interacting superfluid-insulator QCP. In superfluid phases, interacting Goldstone bosons qualitatively change the high frequency optical conductivity, and the corresponding sum rule.
Holographic Butterfly Effect at Quantum Critical Points
Ling, Yi; Wu, Jian-Pin
2016-01-01
When the Lyapunov exponent $\\lambda_L$ in a quantum chaotic system saturates the bound $\\lambda_L\\leqslant 2\\pi k_BT$, it is proposed that this system has a holographic dual described by a gravity theory. In particular, the butterfly effect as a prominent phenomenon of chaos can ubiquitously exist in a black hole system characterized by a shockwave solution near the horizon. In this letter we propose that the butterfly velocity $v_B$ can be used to diagnose quantum phase transition (QPT) in holographic theories. We provide evidences for this proposal with two holographic models exhibiting metal-insulator transitions (MIT), in which the second derivative of $v_B$ with respect to system parameters characterizes quantum critical points (QCP) with local extremes. We also point out that this proposal can be tested by experiments in the light of recent progress on the measurement of out-of-time-order correlation function (OTOC).
Viscoelasticity of Xenon near the Critical Point
Berg, Robert F.; Moldover, Michael R.; Zimmerli, Gregory A.
1999-01-01
Using a novel, overdamped, oscillator flown aboard the Space Shuttle, we measured the viscosity of xenon near the liquid-vapor critical point in the frequency range 2 Hz less than or equal to f less than or equal to 12 Hz. The measured viscosity divergence is characterized by the exponent z(sub eta) = 0.0690 +/- 0.0006, in agreement with the value z(sub eta) = 0.067 +/- 0.002 calculated from a two-loop perturbation expansion. Viscoelastic behavior was evident when t = (T - T(sub c))/T(sub c) less than 10(exp -5) and dominant when t less than 10(exp -6), further from T(sub c) than predicted. Viscoelastic behavior scales as Af(tau) where tau is the fluctuation decay time. The measured value of A is 2.0 +/- 0.3 times the result of a one-loop calculation. (Uncertainties stated are one standard uncertainty.)
Directory of Open Access Journals (Sweden)
Jakub Mielczarek
2017-01-01
Full Text Available This article addresses the issue of possible gravitational phase transitions in the early universe. We suggest that a second-order phase transition observed in the Causal Dynamical Triangulations approach to quantum gravity may have a cosmological relevance. The phase transition interpolates between a nongeometric crumpled phase of gravity and an extended phase with classical properties. Transition of this kind has been postulated earlier in the context of geometrogenesis in the Quantum Graphity approach to quantum gravity. We show that critical behavior may also be associated with a signature change in Loop Quantum Cosmology, which occurs as a result of quantum deformation of the hypersurface deformation algebra. In the considered cases, classical space-time originates at the critical point associated with a second-order phase transition. Relation between the gravitational phase transitions and the corresponding change of symmetry is underlined.
Dynamical Response near Quantum Critical Points
Lucas, Andrew; Gazit, Snir; Podolsky, Daniel; Witczak-Krempa, William
2017-02-01
We study high-frequency response functions, notably the optical conductivity, in the vicinity of quantum critical points (QCPs) by allowing for both detuning from the critical coupling and finite temperature. We consider general dimensions and dynamical exponents. This leads to a unified understanding of sum rules. In systems with emergent Lorentz invariance, powerful methods from quantum field theory allow us to fix the high-frequency response in terms of universal coefficients. We test our predictions analytically in the large-N O (N ) model and using the gauge-gravity duality and numerically via quantum Monte Carlo simulations on a lattice model hosting the interacting superfluid-insulator QCP. In superfluid phases, interacting Goldstone bosons qualitatively change the high-frequency optical conductivity and the corresponding sum rule.
Correlated fluctuations near the QCD critical point
Jiang, Lijia; Li, Pengfei; Song, Huichao
2016-08-01
In this article, we introduce a freeze-out scheme for the dynamical models near the QCD critical point through coupling the decoupled classical particles with the order parameter field. With a modified distribution function that satisfies specific static fluctuations, we calculate the correlated fluctuations of net protons on the hydrodynamic freeze-out surface. A comparison with recent STAR data shows that our model calculations could roughly reproduce energy-dependent cumulant C4 and κ σ2 of net protons through tuning the related parameters. However, the calculated C2 and C3 with both Poisson and binomial baselines are always above the experimental data due to the positive contributions from the static critical fluctuations. To qualitatively and quantitatively describe all the related experimental data, the dynamical critical fluctuations and more realistic noncritical fluctuation baselines should be investigated in the near future.
Eigenvalues of a diffusion process with a critical point
Dekker, H.; Kampen, N.G. van
1979-01-01
The eigenvalues of a Fokker-Planck equation involving a critical point have been computed by means of a simple discretization technique. The results smoothly connect the monostable case above the critical point with the bistable case below it.
Imprints of a critical point on photon emission
Energy Technology Data Exchange (ETDEWEB)
Wunderlich, F.; Kaempfer, B. [Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universitaet Dresden, Institut fuer Theoretische Physik, Dresden (Germany)
2016-08-15
The linear sigma model with linearized fluctuations of all involved fields facilitates the onset of a sequence of first-order phase transitions at a critical point. This phase structure has distinctive imprints on the photon emission rates. We argue that analogously a critical point in the QCD phase diagram manifests itself by peculiarities of the photon spectra, in particular when the dynamical expansion path of matter crosses the phase transition curve in the vicinity of the critical point. (orig.)
Critical Point Dryer: Tousimis 916B Series C
Federal Laboratory Consortium — Description: CORAL Name: Critical Point Dryer This system utilizes CO 2to dry fragile suspended and floating structures Specifications / Capabilities: Wafer size up...
On the critical point of a Malthus-Verhulst process
Dekker, H.
1980-01-01
The master equation for the Malthus-Verhulst process including spontaneous generation will be re-examined in the light of an extended version of Van Kampen's method at the critical point. The Malthus-Verhulst process turns out to be a remarkable special case as the standard scaling property is left untouched at the critical point.
Dynamic universality class of the QCD critical point
Son, D. T.; Stephanov, M. A.
2004-01-01
We show that the dynamic universality class of the QCD critical point is that of model H and discuss the dynamic critical exponents. We show that the baryon diffusion rate vanishes at the critical point. The dynamic critical index $z$ is close to 3.
Pole distribution of PVI transcendents close to a critical point
Guzzetti, Davide
2012-12-01
The distribution of the poles of Painlevé VI transcendents associated to semi-simple Frobenius manifolds is determined close to a critical point. It is shown that the poles accumulate at the critical point, asymptotically along two rays. As an example, the Frobenius manifold given by the quantum cohomology of CP2 is considered. The general PVI is also considered.
X(5) Critical-Point Structure in a Finite System
Leviatan, A
2005-01-01
X(5) is a paradigm for the structure at the critical point of a particular first-order phase transition for which the intrinsic energy surface has two degenerate minima separated by a low barrier. For a finite system, we show that the dynamics at such a critical point can be described by an effective deformation determined by minimizing the energy surface after projection onto angular momentum zero, and combined with two-level mixing. Wave functions of a particular analytic form are used to derive estimates for energies and quadrupole rates at the critical point.
Critical-point symmetry in a finite system.
Leviatan, A; Ginocchio, J N
2003-05-30
At a critical point of a second-order phase transition the intrinsic energy surface is flat and there is no stable minimum value of the deformation. However, for a finite system, we show that there is an effective deformation which can describe the dynamics at the critical point. This effective deformation is determined by minimizing the energy surface after projection onto the appropriate symmetries. We derive analytic expressions for energies and quadrupole rates which provide good estimates for these observables at the critical point.
Critical-Point Symmetry in a Finite System
Leviatan, A
2003-01-01
At a critical point of a second order phase transition the intrinsic energy surface is flat and there is no stable minimum value of the deformation. However, for a finite system, we show that there is an effective deformation which can describe the dynamics at the critical point. This effective deformation is determined by minimizing the energy surface after projection onto the appropriate symmetries. We derive analytic expressions for energies and quadrupole rates which provide good estimates for these observables at the critical point.
The location of critical points of analytic and harmonic functions
Walsh, J L
1950-01-01
This book is concerned with the critical points of analytic and harmonic functions. A critical point of an analytic function means a zero of its derivative, and a critical point of a harmonic function means a point where both partial derivatives vanish. The analytic functions considered are largely polynomials, rational functions, and certain periodic, entire, and meromorphic functions. The harmonic functions considered are largely Green's functions, harmonic measures, and various linear combinations of them. The interest in these functions centers around the approximate location of their crit
Critical Point Dryer: Tousimis 916B Series C
Federal Laboratory Consortium — Description:CORAL Name: Critical Point DryerThis system utilizes CO 2to dry fragile suspended and floating structures Specifications / Capabilities:Wafer size up to...
Cubic Polynomials with Rational Roots and Critical Points
Gupta, Shiv K.; Szymanski, Waclaw
2010-01-01
If you want your students to graph a cubic polynomial, it is best to give them one with rational roots and critical points. In this paper, we describe completely all such cubics and explain how to generate them.
Critical Point Theorems and Applications to Differential Equations
Institute of Scientific and Technical Information of China (English)
A. R. EL AMROUSS
2005-01-01
This paper contains a generalization of the well-known Palais-Smale and Cerami compactness conditions. The compactness condition introduced is used to prove some general existence theorems for critical points. Some applications are given to differential equations.
Critical points and dynamic systems with planar hexagonal symmetry
Energy Technology Data Exchange (ETDEWEB)
Chen Ning [Faculty of Information and Control Engineering, Shenyang Jianzhu University, Shenyang 110168 (China)]. E-mail: n_chen@126.com; Meng Fan Yu [Faculty of Information and Control Engineering, Shenyang Jianzhu University, Shenyang 110168 (China)
2007-05-15
In this investigation, we detect and utilize critical points of functions with hexagonal symmetry in order to study their dynamics. The asymmetric unit in a parallelogram lattice is chosen as the initial searching region for a critical point set in a dynamic plane. The accelerated direct search algorithm is used within the parallelogram lattice to search for the critical points. Parameter space is separated into regions (chaotic, periodic or mixed) by the Ljapunov exponents of the critical points. Then the generalized Mandelbrot set (M-set), which is a cross-section of the parameter space, is constructed. Many chaotic attractors and filled-in Julia sets can be generated by using parameters from this kind of M-sets.
Partial dynamical symmetry at critical points of quantum phase transitions.
Leviatan, A
2007-06-15
We show that partial dynamical symmetries can occur at critical points of quantum phase transitions, in which case underlying competing symmetries are conserved exactly by a subset of states, and mix strongly in other states. Several types of partial dynamical symmetries are demonstrated with the example of critical-point Hamiltonians for first- and second-order transitions in the framework of the interacting boson model, whose dynamical symmetries correspond to different shape phases in nuclei.
Has the QCD critical point been observed at RHIC?
Antoniou, N G; Diakonos, F K
2016-01-01
The experimental search for the location of the QCD critical point in the phase diagram is of primary importance. In a recent publication it is claimed that measurements at RHIC lead not only to the location of the critical point ($\\mu_{cep}=95$ MeV, $T_{cep}=165$ MeV) but also to the verification of its universality class ($3d$ Ising system) by extracting the values of the critical exponents ($\\gamma=1.2$, $\
Inherently unstable networks collapse to a critical point.
Sheinman, M; Sharma, A; Alvarado, J; Koenderink, G H; MacKintosh, F C
2015-07-01
Nonequilibrium systems that are driven or drive themselves towards a critical point have been studied for almost three decades. Here we present a minimalist example of such a system, motivated by experiments on collapsing active elastic networks. Our model of an unstable elastic network exhibits a collapse towards a critical point from any macroscopically connected initial configuration. Taking into account steric interactions within the network, the model qualitatively and quantitatively reproduces results of the experiments on collapsing active gels.
The critical point of quantum chromodynamics through lattice and experiment
Indian Academy of Sciences (India)
Sourendu Gupta
2011-05-01
This talk discusses methods of extending lattice computations at ﬁnite temperature into regions of ﬁnite chemical potential, and the conditions under which such results from the lattice may be compared to experiments. Such comparisons away from a critical point are absolutely essential for quantitative use of lattice QCD in heavy-ion physics. An outline of various arguments which can then be used to locate the critical point is also presented.
Search for the QCD critical point at SPS energies
Anticic, T; Barna, D; Bartke, J; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Botje, M; Bracinik, J; Buncic, P; Cerny, V; Christakoglou, P; Chung, P; Chvala, O; Cramer, J G; Csato, P; Dinkelaker, P; Eckardt, V; Fodor, Z; Foka, P; Friese, V; Gal, J; Gazdzicki, M; Genchev, V; Gladysz, E; Grebieszkow, K; Hegyi, S; Hohne, C; Kadija, K; Karev, A; Kikola, D; Kolesnikov, V I; Kornas, E; Korus, R; Kowalski, M; Kreps, M; Laszlo, A; Lacey, R; van Leeuwen, M; Levai, P; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Mateev, M; Melkumov, G L; Mischke, A; Mitrovski, M; Mrowczynski, St; Nicolic, V; Palla, G; Panagiotou, A D; Petridis, A; Peryt, W; Pikna, M; Pluta, J; Prindle, D; Puhlhofer, F; Renfordt, R; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Seyboth, P; Sikler, F; Sitar, B; Skrzypczak, E; Slodkowski, M; Stefanek, G; Stock, R; Strabel, C; Strobele, H; Susa, T; Szentpetery, I; Sziklai, J; Szuba, M; Szymanski, P; Trubnikov, V; Utvic, M; Varga, D; Vassiliou, M; Veres, G I; Vesztergombi, G; Vranic, D; Wlodarczyk, Z; Wojtaszek-Szwarc, A; Yoo, I K; Abgrall, N; Aduszkiewicz, A; Andrieu, B; Anticic, T; Antoniou, N; Argyriades, J; Asryan, A G; Baatar, B; Blondel, A; Blumer, J; Boldizsar, L; Bravar, A; Brzychczyk, J; Bubak, A; Bunyatov, S A; Choi, K.-U; Christakoglou, P; Chung, P; Cleymans, J; Derkach, D A; Diakonos, F; Dominik, W; Dumarchez, J; Engel, R; Ereditato, A; Feofilov, G A; Fodor, Z; Ferrero, A; Gazdzicki, M; Golubeva, M; Grebieszkow, K; Grzeszczuk, A; Guber, F; Hasegawa, T; Haungs, A; Igolkin, S; Ivanov, A S; Ivashkin, A; Kadija, K; Katrynska, N; Kielczewska, D; Kikola, D; Kisiel, J; Kobayashi, T; Kolesnikov, V I; Kolev, D; Kolevatov, R S; Kondratiev, V P; Kowalski, S; Kurepin, A; Lacey, R; Laszlo, A; Lyubushkin, V V; Majka, Z; Malakhov, A I; Marchionni, A; Marcinek, A; Maris, I; Matveev, V; Melkumov, G L; Meregaglia, A; Messina, M; Mijakowski, P; Mitrovski, M; Montaruli, T; Mrowczynski, St; Murphy, S; Nakadaira, T; Naumenko, P A; Nikolic, V; Nishikawa, K; Palczewski, T; Palla, G; Panagiotou, A D; Peryt, W; Planeta, R; Pluta, J; Popov, B A; Posiadala, M; Przewlocki, P; Rauch, W; Ravonel, M; Renfordt, R; Rohrich, D; Rondio, E; Rossi, B; Roth, M; Rubbia, A; Rybczynski, M; Sadovsky, A; Sakashita, K; Schuster, T; Sekiguchi, T; Seyboth, P; Shibata, M; Sissakian, A N; Skrzypczak, E; Slodkowski, M; Sorin, A S; Staszel, P; Stefanek, G; Stepaniak, J; Strabel, C; Stroebele, H; Susa, T; Szentpetery, I; Szuba, M; Tada, M; Taranenko, A; Tsenov, R; Ulrich, R; Unger, M; Vassiliou, M; Vechernin, V V; Vesztergombi, G; Wlodarczyk, Z; Wojtaszek-Szwarc, A; Zipper, W
2009-01-01
Lattice QCD calculations locate the QCD critical point at energies accessible at the CERN Super Proton Synchrotron (SPS). We present average transverse momentum and multiplicity fluctuations, as well as baryon and anti-baryon transverse mass spectra which are expected to be sensitive to effects of the critical point. The future CP search strategy of the NA61/SHINE experiment at the SPS is also discussed.
DEFF Research Database (Denmark)
Annuar, A.; Gandhi, P.; Alexander, D. M.;
2015-01-01
We present two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton, and Swift-BAT, we perform a high-quality broadband s...
Potential Improvements of Supercritical CO2 Brayton Cycle by Modifying Critical Point of CO2
Energy Technology Data Exchange (ETDEWEB)
Jeong, Woo Seok; Lee, Jeong Ik; Jeong, Yong Hoon; No, Hee Cheon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)
2009-10-15
A Sodium-cooled Fast Reactor (SFR) is one of strong candidates for a next generation nuclear reactor. However, the conventional design of a SFR concept with an indirect Rankine cycle is subjected to a sodium water reaction, which can deteriorate the safety of a SFR. To prevent any hazards from sodium-water reaction, a SFR with the Brayton cycle using Helium or Supercritical Carbon dioxide (S-CO2) as working fluids can be an alternative approach to improve the current SFR design. As in a helium cycle, there has been an investigation to modify thermo-physical properties to increase the efficiency of the cycle and reduce the size of turbomachineries. Particularly, He-Xe or He-N2 binary mixture were successful to decrease the stages of turbomachines due to the increment of molecular weight of gas mixture than that of pure helium. Similar to the case of helium, CO2 has a potential to modify its thermo-physical properties by mixing with other gases. For instance, it was reported that critical point of CO2 can be shifted by mixing with different gases. Since, the efficiency of a S-CO2 cycle is limited to the critical point of CO2, the shift in critical point implies that there is a possibility of improving the cycle efficiency than the current design. This paper presents the results of a preliminary analysis to identify the effects of CO2 critical point modification on the Brayton cycle performance.
Candidate Elastic Quantum Critical Point in {\mathrm{LaCu}}_{6-x}{\mathrm{Au}}_{x}
Energy Technology Data Exchange (ETDEWEB)
Poudel, L.; May, A. F.; Koehler, M. R.; McGuire, M. A.; Mukhopadhyay, S.; Calder, S.; Baumbach, R. E.; Mukherjee, R.; Sapkota, D.; de la Cruz, C.; Singh, D. J.; Mandrus, D.; Christianson, A. D.
2016-11-01
The structural properties of LaCu _{6-x} Au _{x} are studied using neutron diffraction, x-ray diffraction, and heat capacity measurements. The continuous orthorhombic-monoclinic structural phase transition in LaCu_{ 6} is suppressed linearly with Au substitution until a complete suppression of the structural phase transition occurs at the critical composition x _{c} = 0.3 . Heat capacity measurements at low temperatures indicate residual structural instability at x_{ c} . The instability is ferroelastic in nature, with density functional theory calculations showing negligible coupling to electronic states near the Fermi level. The data and calculations presented here are consistent with the zero temperature termination of a continuous structural phase transition suggesting that the LaCu _{6-x} Au _{x} series hosts an elastic quantum critical point.
Critical points of multidimensional random Fourier series: Variance estimates
Nicolaescu, Liviu I.
2016-08-01
We investigate the number of critical points of a Gaussian random smooth function uɛ on the m-torus Tm ≔ ℝm/ℤm approximating the Gaussian white noise as ɛ → 0. Let N(uɛ) denote the number of critical points of uɛ. We prove the existence of constants C, C' such that as ɛ goes to zero, the expectation of the random variable ɛmN(uɛ) converges to C, while its variance is extremely small and behaves like C'ɛm.
Critical Points in Nuclei and Interacting Boson Model Intrinsic States
Ginocchio, J N; Ginocchio, Joseph N.
2003-01-01
We consider properties of critical points in the interacting boson model, corresponding to flat-bottomed potentials as encountered in a second-order phase transition between spherical and deformed $\\gamma$-unstable nuclei. We show that intrinsic states with an effective $\\beta$-deformation reproduce the dynamics of the underlying non-rigid shapes. The effective deformation can be determined from the the global minimum of the energy surface after projection onto the appropriate symmetry. States of fixed $N$ and good O(5) symmetry projected from these intrinsic states provide good analytic estimates to the exact eigenstates, energies and quadrupole transition rates at the critical point.
Characterizing variable for the critical point in momentum space
Institute of Scientific and Technical Information of China (English)
DU Jia-Xin; KE Hong-Wei; XU Ming-Mei; LIU Lian-Shou
2009-01-01
The possible experimentally observable signal in momentum space for the critical point, which is free from the contamination of statistical fluctuations, is discussed. It is shown that the higher order scaled moment of transverse momentum can serve as an appropriate signal for the critical point, provided the transverse momentum distribution has a sudden change when energy increases passing through this point. A 2-D percolation model with a linear temperature gradient is constructed to check this suggestion. A sudden change of third order scaled moment of transverse momentum is observed.
Universal Postquench Prethermalization at a Quantum Critical Point.
Gagel, Pia; Orth, Peter P; Schmalian, Jörg
2014-11-28
We consider an open system near a quantum critical point that is suddenly moved towards the critical point. The bath-dominated diffusive nonequilibrium dynamics after the quench is shown to follow scaling behavior, governed by a critical exponent that emerges in addition to the known equilibrium critical exponents. We determine this exponent and show that it describes universal prethermalized coarsening dynamics of the order parameter in an intermediate time regime. Implications of this quantum critical prethermalization are: (i) a power law rise of order and correlations after an initial collapse of the equilibrium state and (ii) a crossover to thermalization that occurs arbitrarily late for sufficiently shallow quenches.
Oscillatory integrals for phase functions having certain degenerate critical points
Institute of Scientific and Technical Information of China (English)
Jinmyong KIM; ZHENG Quan
2008-01-01
The paper is concerned with oscillatory integrals for phase functions having certain de-generate critical points. Under a finite type condition of phase functions we show the estimate of oscillatory integrals of the first kind. The decay of the oscillatory integral depends on indices of the finite type, the spatial dimension and the symbol.
Oscillatory integrals for phase functions having certain degenerate critical points
Institute of Scientific and Technical Information of China (English)
Jinmyong; KIM
2008-01-01
The paper is concerned with oscillatory integrals for phase functions having certain de- generate critical points. Under a finite type condition of phase functions we show the estimate of oscillatory integrals of the first kind. The decay of the oscillatory integral depends on indices of the finite type, the spatial dimension and the symbol.
Critical Points of the Electric Field from a Collection of Point Charges
Energy Technology Data Exchange (ETDEWEB)
Max, N; Weinkauf, T
2007-02-16
The electric field around a molecule is generated by the charge distribution of its constituents: positively charged atomic nuclei, which are well approximated by point charges, and negatively charged electrons, whose probability density distribution can be computed from quantum mechanics. For the purposes of molecular mechanics or dynamics, the charge distribution is often approximated by a collection of point charges, with either a single partial charge at each atomic nucleus position, representing both the nucleus and the electrons near it, or as several different point charges per atom. The critical points in the electric field are useful in visualizing its geometrical and topological structure, and can help in understanding the forces and motion it induces on a charged ion or neutral dipole. Most visualization tools for vector fields use only samples of the field on the vertices of a regular grid, and some sort of interpolation, for example, trilinear, on the grid cells. There is less risk of missing or misinterpreting topological features if they can be derived directly from the analytic formula for the field, rather than from its samples. This work presents a method which is guaranteed to find all the critical points of the electric field from a finite set of point charges. To visualize the field topology, we have modified the saddle connector method to use the analytic formula for the field.
Identification of Critical Points in the Quality Management System
Directory of Open Access Journals (Sweden)
Tünde SZABÓ
2011-10-01
Full Text Available Creating a quality management system can help organizations and other stakeholders in satisfying customer needs and expectations. Moreover, a well-implemented quality management ensures the organization a capable structure to make continuous improvement actions. Thus, after the evaluation of the quality management system elements, the identification of critical points is a very important element. There are several ways of assessing and identifying these critical points; in this case, identification will be done by questionnaire survey carried out at the Székely National Museum in Saint George. The questionnaire aimed to assess the whole system of management and staff attitudes towards some considerations established by international standard ISO 9001:2008.
Possible signal for critical point in hadronization process
Rybczynski, M; Wlodarczyk, Z.; Wilk, G.
2003-01-01
We argue that recent data on fluctuations observed in heavy ion collisions show non-monotonic behaviour as function of number of participants (or "wounded nucleons") N_W. When interpreted in thermodynamical approach this result can be associated with a possible structure occuring in the corresponding equation of state (EoS). This in turn could be further interpreted as due to the occurence of some characteristic points (like "softest point" or "critical point") of EoS discussed in the literat...
Binary Colloidal Alloy Test-3 and 4: Critical Point
Weitz, David A.; Lu, Peter J.
2007-01-01
Binary Colloidal Alloy Test - 3 and 4: Critical Point (BCAT-3-4-CP) will determine phase separation rates and add needed points to the phase diagram of a model critical fluid system. Crewmembers photograph samples of polymer and colloidal particles (tiny nanoscale spheres suspended in liquid) that model liquid/gas phase changes. Results will help scientists develop fundamental physics concepts previously cloaked by the effects of gravity.
Thermodynamic curvature from the critical point to the triple point.
Ruppeiner, George
2012-08-01
I evaluate the thermodynamic curvature R for fourteen pure fluids along their liquid-vapor coexistence curves, from the critical point to the triple point, using thermodynamic input from the NIST Chemistry WebBook. In this broad overview, R is evaluated in both the coexisting liquid and vapor phases. R is an invariant whose magnitude |R| is a measure of the size of mesoscopic organized structures in a fluid, and whose sign specifies whether intermolecular interactions are effectively attractive (R0). I discuss five principles for R in pure fluids: (1) Near the critical point, the attractive part of the interactions forms loose structures of size |R| proportional to the correlation volume ξ(3), and the sign of R is negative. (2) In the vapor phase, there are instances of compact clusters of size |R| formed by the attractive part of the interactions and prevented from collapse by the repulsive part of the interactions, and the sign of R is positive. (3) In the asymptotic critical point regime, the R's in the coexisting liquid and vapor phases are equal to each other, i.e., commensurate. (4) Outside the asymptotic critical-point regime incommensurate R's may be associated with metastability. (5) The compact liquid phase has |R| on the order of the volume of a molecule, with the sign of R being negative for a liquidlike state held together by attractive interactions and the sign of R being positive for a solidlike state held up by repulsive interactions. These considerations amplify and extend the application of thermodynamic curvature in pure fluids.
QCD Critical Point and Complex Chemical Potential Singularities
Stephanov, M A
2006-01-01
The thermodynamic singularities of QCD in the plane of complex baryo-chemical potential mu are studied. Predictions are made using scaling and universality arguments in the vicinity of the massless quark limit. The results are illustrated by a calculation of complex mu singularities in a random matrix model at finite temperature. Implications for lattice QCD simulations aimed at locating the QCD critical point are discussed.
Dynamical net-proton fluctuations near a QCD critical point
Herold, Christoph; Yan, Yupeng; Kobdaj, Chinorat
2016-01-01
We investigate the evolution of the net-proton kurtosis and the kurtosis of the chiral order parameter near the critical point in the model of nonequilibrium chiral fluid dynamics. The order parameter is propagated explicitly and coupled to an expanding fluid of quarks and gluons in order to describe the dynamical situation in a heavy-ion collision. We study the critical region near the critical point on the crossover side. There are two sources of fluctuations: non-critical initial event-by-event fluctuations and critical fluctuations. These fluctuations can be distinguished by comparing a mean-field evolution of averaged thermodynamic quantities with the inclusion of fluctuations at the phase transition. We find that while the initial state fluctuations give rise to flat deviations from statistical fluctuations, critical fluctuations reveal a clear structure of the phase transition. The signals of the critical point in the net-proton and sigma field kurtosis are affected by the nonequilibrium dynamics and t...
Metallic magnets without inversion symmetry and antiferromagnetic quantum critical points
Energy Technology Data Exchange (ETDEWEB)
Fischer, I.A.
2006-07-01
This thesis focusses on two classes of systems that exhibit non-Fermi liquid behaviour in experiments: we investigated aspects of chiral ferromagnets and of antiferromagnetic metals close to a quantum critical point. In chiral ferromagnets, the absence of inversion symmetry makes spin-orbit coupling possible, which leads to a helical modulation of the ferromagnetically ordered state. We studied the motion of electrons in the magnetically ordered state of a metal without inversion symmetry by calculating their generic band-structure. We found that spin-orbit coupling, although weak, has a profound effect on the shape of the Fermi surface: On a large portion of the Fermi surface the electron motion parallel to the helix practically stops. Signatures of this effect can be expected to show up in measurements of the anomalous Hall effect. Recent neutron scattering experiments uncovered the existence of a peculiar kind of partial order in a region of the phase diagram adjacent to the ordered state of the chiral ferromagnet MnSi. Starting from the premise that this partially ordered state is a thermodynamically distinct phase, we investigated an extended Ginzburg-Landau theory for chiral ferromagnets. In a certain parameter regime of the Ginzburg-Landau theory we identified crystalline phases that are reminiscent of the so-called blue phases in liquid crystals. Many antiferromagnetic heavy-fermion systems can be tuned into a regime where they exhibit non-Fermi liquid exponents in the temperature dependence of thermodynamic quantities such as the specific heat capacity; this behaviour could be due to a quantum critical point. If the quantum critical behaviour is field-induced, the external field does not only suppress antiferromagnetism but also induces spin precession and thereby influences the dynamics of the order parameter. We investigated the quantum critical behavior of clean antiferromagnetic metals subject to a static, spatially uniform external magnetic field. We
Direct Observation of Critical Point Wetting in Microgravity
Kaukler, W. F.
1985-01-01
The objective of this program is to observe the interface shape in single and multicomponent systems at the onset of critical wetting in microgravity using the MSFC drop tower and KC-135 aircraft. Test cells for the drop facility were built and tested up to critical point of CCl. Low temperature drops were conducted for two-component systems near the critical consolute point. Contact angle seems to approach 90 deg near the critical consolute temperature contrary to expectations. It is suspected that since the interfacial energy becomes vanishingly small at the critical consolute temperature, the interface shape has not reached equilibrium in the available low-gravity time.
Critical point drying: contamination in transitional fluid supply cylinders.
Hoagland, K D; Rosowski, J R; Cohen, A L
1980-01-01
We call attention to the occurrence of an oily residue in the CPD bomb after critical point drying, as well as the presence of rust, dirt, and an oily residue in CO2 and Freon supply cylinders. Bottled gas is often tested for purity once after manufacturing and then is pumped and stored, perhaps several times, before the consumer's cylinders are filled. The cylinders may be in use for over 40 years, and may never be chemically cleaned, although they are hydrostatically pressure tested every five years, with the date of each test stamped on the cylinder. To the bottled gas industry we recommend regular inspection of tanks for bottom contamination, and vacuum and chemical cleaning when contamination is found. To users of bottled gas for critical point drying, we recommend becoming aware of the procedures of cylinder inspection, cleaning, and circulation among users. We suggest reporting to the gas supplier any contamination produced by inadvertently backfilling the supply cylinder. Although a common awareness of the problem of supply cylinder residues should lead to failures, the best assurance of clean, oil-free, dry liquid CO2 and other transitional fluids may be in the development of in-line filters which would remove particles, oil and moisture between the supply cylinder and the CPD bomb. We also suggest the use of gas grades higher than commercial, such as welding anhydrous (CO2) or specialty gases.
Critical Point on the QCD Deconfining Phase Boundary
Srivastava, P K
2012-01-01
Ambiguities regarding the physics and the existence of the critical point (CP) on the QCD phase boundary still exist and the mist regarding the conjectured QCD phase boundary has not yet cleared. In this paper we extend our earlier study where we constructed a deconfining phase boundary using Gibbs' equilibrium conditions after using a quasiparticle equation of state (EOS) for quark gluon plasma (QGP) and an excluded volume EOS for the hadron gas (HG) and find the presence of a critical point on this phase boundary where the first order phase transition terminates. In this paper, we plot the difference in the normalized entropy density ($s/T^{3}$) between HG and QGP phases along the deconfining phase boundary and find that it vanishes at CP. Further we have shown the variation of the square of speed of sound ($c_{s}^{2}$) for the HG and QGP separately and find that the difference ($\\Delta c_{s}^{2}$) between them along the deconfining phase boundary again vanishes at the CP of the boundary. We also plot the v...
The Critical Point Entanglement and Chaos in the Dicke Model
Directory of Open Access Journals (Sweden)
Lina Bao
2015-07-01
Full Text Available Ground state properties and level statistics of the Dicke model for a finite number of atoms are investigated based on a progressive diagonalization scheme (PDS. Particle number statistics, the entanglement measure and the Shannon information entropy at the resonance point in cases with a finite number of atoms as functions of the coupling parameter are calculated. It is shown that the entanglement measure defined in terms of the normalized von Neumann entropy of the reduced density matrix of the atoms reaches its maximum value at the critical point of the quantum phase transition where the system is most chaotic. Noticeable change in the Shannon information entropy near or at the critical point of the quantum phase transition is also observed. In addition, the quantum phase transition may be observed not only in the ground state mean photon number and the ground state atomic inversion as shown previously, but also in fluctuations of these two quantities in the ground state, especially in the atomic inversion fluctuation.
Ion exchange at the critical point of solution.
Savoy, J D; Baird, J K; Lang, J R
2016-03-11
A mixture of isobutyric acid (IBA)+water has an upper critical point of solution at 26.7°C and an IBA concentration of 4.40M. We have determined the Langmuir isotherms for the hydroxide form of Amberlite IRN-78 resin in contact with mixtures of IBA+water at temperatures, 27.0, 29.0, 31.0 and 38.0°C, respectively. The Langmuir plot at 38.0°C forms a straight line. At the three lower temperatures, however, a peak in the Langmuir plot is observed for IBA concentrations in the vicinity of 4.40M. We regard this peak to be a critical effect not only because it is located close to 4.40M, but also because its height becomes more pronounced as the temperature of the isotherm approaches the critical temperature. For concentrations in the vicinity of the peak, the data indicate that the larger isobutyrate ion is rejected by the resin in favor of the smaller hydroxide ion. This reversal of the expected ion exchange reaction might be used to separate ions according to size. Using the Donnan theory of ion exchange equilibrium, we link the swelling pressure to the osmotic pressure. We show that the peak in the Langmuir plot is associated with a maximum in the "osmotic" energy. This maximum has its origin in the concentration derivative of the osmotic pressure, which goes to zero as the critical point is approached.
Peculiar thermodynamics of the second critical point in supercooled water.
Bertrand, C E; Anisimov, M A
2011-12-08
On the basis of the principle of critical-point universality, we examine the peculiar thermodynamics of the liquid-liquid critical point in supercooled water. We show that the liquid-liquid criticality in water represents a special kind of critical behavior in fluids, intermediate between two limiting cases: the lattice gas, commonly used to model liquid-vapor transitions, and the lattice liquid, a weakly compressible liquid with an entropy-driven phase separation. While the ordering field in the lattice gas is associated with the chemical potential and the order parameter with the density, in the lattice liquid the ordering field is the temperature and the order parameter is the entropy. The behavior of supercooled water is much closer to lattice-liquid behavior than to lattice-gas behavior. Using new experimental data recently obtained by Mishima [J. Chem. Phys. 2010, 133, 144503], we have revised the parametric scaled equation of state, previously suggested by Fuentevilla and Anisimov [Phys. Rev. Lett. 2006, 97, 195702], and obtain a consistent description of the thermodynamic anomalies of supercooled water by adjusting linear backgrounds, one critical amplitude, and the critical pressure. We also show how the lattice-liquid description affects the finite-size scaling description of supercooled water in confined media.
LEARNING THE CRITICAL POINTS FOR ADDITION IN MATEMATIKA GASING
Directory of Open Access Journals (Sweden)
Johannes Hamonangan Siregar
2014-07-01
Full Text Available We propose learning Matematika GASING to help students better understand the addition material. Matematika GASING is a way of learning mathematics in an easy, fun and enjoyable fashion. GASING is short for GAmpang, aSyIk, and menyenaNGkan (Bahasa Indonesia for easy, fun and enjoyable. It was originally developed by Prof. Yohanes Surya at the Surya Institute in Indonesia to improve the mathematics education in Indonesia. In Matematika GASING, there is a step called “the critical point” that needs to be mastered for each topic. The focus of our research is the critical point for addition, that is addition of two numbers between 1 − 10 with a sum less than 20. The subject is a matriculation class at STKIP Surya and the research method used is Classroom Action Research. The statistics obtained is described using Qualitative Descriptive Statistics.Keyword: Matematika GASING, Addition, Critical Points, Classroom Action Research. DOI: http://dx.doi.org/10.22342/jme.5.2.1500.160-169
Critical Opalescence: An Optical Signature for a QCD Critical Point
Csorgo, T
2009-01-01
Four possible scenarios are considered for a transition from a quark-gluon matter to hadronic matter, and their corresponding correlation signatures are discussed. Four criteria are highlighted for a definitive experimental search for a QCD critical point. An old-new experimental measure, the optical opacity (or its inverse the nuclear attenuation length) is determined, in terms of a combination of nuclear suppression factors and a measurement of the relevant fireball length scales. Length scale estimates using either the Hanbury Brown -- Twiss radii or that of the initial nuclear geometry for measurements of optical opacity with respect to the reaction plane yield, somewhat surprizingly, nearly the same nuclear attenuation lenght in 0-5 % most central 200 GeV Au+Au collisions, corresponding to 2.9 $\\pm$ 0.3 fm. The necessity and the possibility of measuring critical exponents is also discussed in the context of determination of the universality class of the QCD critical point. Critical opalescence is propose...
Symmetry relations for multifractal spectra at random critical points
Monthus, Cécile; Berche, Bertrand; Chatelain, Christophe
2009-12-01
Random critical points are generically characterized by multifractal properties. In the field of Anderson localization, Mirlin et al (2006 Phys. Rev. Lett. 97 046803) have proposed that the singularity spectrum f(α) of eigenfunctions satisfies the exact symmetry f(2d-α) = f(α)+d-α. In the present paper, we analyze the physical origin of this symmetry in relation to the Gallavotti-Cohen fluctuation relations of large deviation functions that are well known in the field of non-equilibrium dynamics: the multifractal spectrum of the disordered model corresponds to the large deviation function of the rescaling exponent γ = (α-d) along a renormalization trajectory in the effective time t = lnL. We conclude that the symmetry discovered for the specific example of Anderson transitions should actually be satisfied at many other random critical points after an appropriate translation. For many-body random phase transitions, where the critical properties are usually analyzed in terms of the multifractal spectrum H(a) and of the moment exponents X(N) of the two-point correlation function (Ludwig 1990 Nucl. Phys. B 330 639), the symmetry becomes H(2X(1)-a) = H(a)+a-X(1), or equivalently Δ(N) = Δ(1-N) for the anomalous parts \\Delta (N) \\equiv X(N)-NX(1) . We present numerical tests favoring this symmetry for the 2D random Q-state Potts model with varying Q.
Menezes, R. B.; Steiner, J. E.
2017-04-01
NGC 1313 is a bulgeless nearby galaxy, classified as SB(s)d. Its proximity allows high spatial resolution observations. We performed the first detailed analysis of the emission-line properties in the nuclear region of NGC 1313, using an optical data cube obtained with the Gemini Multi-object Spectrograph. We detected four main emitting areas, three of them (regions 1, 2 and 3) having spectra typical of H II regions. Region 1 is located very close to the stellar nucleus and shows broad spectral features characteristic of Wolf-Rayet stars. Our analysis revealed the presence of one or two WC4-5 stars in this region, which is compatible with results obtained by previous studies. Region 4 shows spectral features (as a strong Hα emission line, with a broad component) typical of a massive emission-line star, such as a luminous blue variable, a B[e] supergiant or a B hypergiant. The radial velocity map of the ionized gas shows a pattern consistent with rotation. A significant drop in the values of the gas velocity dispersion was detected very close to region 1, which suggests that the young stars there were formed from this cold gas, possibly keeping low values of velocity dispersion. Therefore, although detailed measurements of the stellar kinematics were not possible (due to the weak stellar absorption spectrum of this galaxy), we predict that NGC 1313 may also show a drop in the values of the stellar velocity dispersion in its nuclear region.
Annuar, A; Alexander, D M; Lansbury, G B; Arévalo, P; Ballantyne, D R; Baloković, M; Bauer, F E; Boggs, S E; Brandt, W N; Brightman, M; Christensen, F E; Craig, W W; Del Moro, A; Hailey, C J; Harrison, F A; Hickox, R C; Matt, G; Puccetti, S; Ricci, C; Rigby, J R; Stern, D; Walton, D J; Zappacosta, L; Zhang, W
2015-01-01
We present two NuSTAR observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton and Swift-BAT, we perform a high-quality broadband spectral analysis of the AGN over two decades in energy ($\\sim$0.5-100 keV). Previous X-ray observations suggested that the AGN is obscured by a Compton-thick (CT) column of obscuring gas along our line-of-sight. However, the lack of high-quality $\\gtrsim$ 10 keV observations, together with the presence of a nearby X-ray luminous source, NGC 5643 X-1, had left significant uncertainties in the characterization of the nuclear spectrum. NuSTAR now enables the AGN and NGC 5643 X-1 to be separately resolved above 10 keV for the first time and allows a direct measurement of the absorbing column density toward the nucleus. The new data show that the nucleus is indeed obscured by a CT column of $N_{\\rm{H}}$ $\\gtrsim$ 5 $\\times$ 10$^{24}$ cm$^{-2}$. The range of 2-10 ...
Black holes as critical point of quantum phase transition.
Dvali, Gia; Gomez, Cesar
We reformulate the quantum black hole portrait in the language of modern condensed matter physics. We show that black holes can be understood as a graviton Bose-Einstein condensate at the critical point of a quantum phase transition, identical to what has been observed in systems of cold atoms. The Bogoliubov modes that become degenerate and nearly gapless at this point are the holographic quantum degrees of freedom responsible for the black hole entropy and the information storage. They have no (semi)classical counterparts and become inaccessible in this limit. These findings indicate a deep connection between the seemingly remote systems and suggest a new quantum foundation of holography. They also open an intriguing possibility of simulating black hole information processing in table-top labs.
Possible Signal for Critical Point in Hadronization Process
Rybczynski, M.; Wlodarczyk, Z.; Wilk, G.
2004-02-01
We argue that recent data on fluctuations observed in heavy ion collisions show non-monotonic behaviour as function of number of participants (or ''wounded nucleons'') NW. When interpreted in thermodynamical approach this result can be associated with a possible structure occurring in the corresponding equation of state (EoS). This in turn could be further interpreted as due to the occurrence of some characteristic points (like softest point or critical point) of EoS discussed in the literature and therefore be regarded as a possible signal of the QGP formation in such collisions. We show, however, that the actual situation is still far from being clear and calls for more investigations of fluctuation phenomena in multiparticle production processes to be performed.
Black holes as critical point of quantum phase transition
Energy Technology Data Exchange (ETDEWEB)
Dvali, Gia [Arnold Sommerfeld Center for Theoretical Physics, Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Muenchen (Germany); Max-Planck-Institut fuer Physik, Muenchen (Germany); CERN, Theory Department, Geneva 23 (Switzerland); New York University, Department of Physics, Center for Cosmology and Particle Physics, New York, NY (United States); Gomez, Cesar [Arnold Sommerfeld Center for Theoretical Physics, Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Muenchen (Germany); Universidad Autonoma de Madrid, Instituto de Fisica Teorica UAM-CSIC, C-XVI, Madrid (Spain)
2014-02-15
We reformulate the quantum black hole portrait in the language of modern condensed matter physics. We show that black holes can be understood as a graviton Bose-Einstein condensate at the critical point of a quantum phase transition, identical to what has been observed in systems of cold atoms. The Bogoliubov modes that become degenerate and nearly gapless at this point are the holographic quantum degrees of freedom responsible for the black hole entropy and the information storage. They have no (semi)classical counterparts and become inaccessible in this limit. These findings indicate a deep connection between the seemingly remote systems and suggest a new quantum foundation of holography. They also open an intriguing possibility of simulating black hole information processing in table-top labs. (orig.)
Black Holes as Critical Point of Quantum Phase Transition
Dvali, Gia
2014-01-01
We reformulate the quantum black hole portrait in the language of modern condensed matter physics. We show that black holes can be understood as a graviton Bose-Einstein condensate at the critical point of a quantum phase transition, identical to what has been observed in systems of cold atoms. The Bogoliubov modes that become degenerate and nearly gapless at this point are the holographic quantum degrees of freedom responsible for the black hole entropy and the information storage. They have no (semi)classical counterparts and become inaccessible in this limit. These findings indicate a deep connection between the seemingly remote systems and suggest a new quantum foundation of holography. They also open an intriguing possibility of simulating black hole information processing in table-top labs.
Black holes as critical point of quantum phase transition
Dvali, Gia; Gomez, Cesar
2014-02-01
We reformulate the quantum black hole portrait in the language of modern condensed matter physics. We show that black holes can be understood as a graviton Bose-Einstein condensate at the critical point of a quantum phase transition, identical to what has been observed in systems of cold atoms. The Bogoliubov modes that become degenerate and nearly gapless at this point are the holographic quantum degrees of freedom responsible for the black hole entropy and the information storage. They have no (semi)classical counterparts and become inaccessible in this limit. These findings indicate a deep connection between the seemingly remote systems and suggest a new quantum foundation of holography. They also open an intriguing possibility of simulating black hole information processing in table-top labs.
Order parameter fluctuations at a buried quantum critical point.
Feng, Yejun; Wang, Jiyang; Jaramillo, R; van Wezel, Jasper; Haravifard, S; Srajer, G; Liu, Y; Xu, Z-A; Littlewood, P B; Rosenbaum, T F
2012-05-08
Quantum criticality is a central concept in condensed matter physics, but the direct observation of quantum critical fluctuations has remained elusive. Here we present an X-ray diffraction study of the charge density wave (CDW) in 2H-NbSe(2) at high pressure and low temperature, where we observe a broad regime of order parameter fluctuations that are controlled by proximity to a quantum critical point. X-rays can track the CDW despite the fact that the quantum critical regime is shrouded inside a superconducting phase; and in contrast to transport probes, allow direct measurement of the critical fluctuations of the charge order. Concurrent measurements of the crystal lattice point to a critical transition that is continuous in nature. Our results confirm the long-standing expectations of enhanced quantum fluctuations in low-dimensional systems, and may help to constrain theories of the quantum critical Fermi surface.
Diagnosis as the First Critical Point in the Treatment Trajectory
DEFF Research Database (Denmark)
Missel, Malene; Pedersen, Jesper H; Hendriksen, Carsten
2015-01-01
of patients with operable lung cancer in order to identify their needs for care interventions from the point of diagnosis to hospitalization. METHODS: We investigated patients' lived experiences from a longitudinal perspective at 4 critical time points during the treatment trajectory; we present here...... the patient to face a new life situation, and demands one-on-one supportive care. CONCLUSIONS: Diagnosis is the first critical point for patients with operable lung cancer and disrupts their daily life. Patients need psychosocial support during the period from diagnosis to surgical intervention and patient...... the findings from the first time point, diagnosis. Data were collected through interviews conducted 7 to 10 days following diagnosis of lung cancer. Data from 19 patients are included, and the analysis is based on Ricoeur's interpretation theory. The study framework is inspired by Schutz's phenomenological...
Impurities near an antiferromagnetic-singlet quantum critical point
Mendes-Santos, T.; Costa, N. C.; Batrouni, G.; Curro, N.; dos Santos, R. R.; Paiva, T.; Scalettar, R. T.
2017-02-01
Heavy-fermion systems and other strongly correlated electron materials often exhibit a competition between antiferromagnetic (AF) and singlet ground states. Using exact quantum Monte Carlo simulations, we examine the effect of impurities in the vicinity of such an AF-singlet quantum critical point (QCP), through an appropriately defined "impurity susceptibility" χimp. Our key finding is a connection within a single calculational framework between AF domains induced on the singlet side of the transition and the behavior of the nuclear magnetic resonance (NMR) relaxation rate 1 /T1 . We show that local NMR measurements provide a diagnostic for the location of the QCP, which agrees remarkably well with the vanishing of the AF order parameter and large values of χimp.
Thermal conductivity at a disordered quantum critical point
Hartnoll, Sean A; Santos, Jorge E
2015-01-01
Strongly disordered and strongly interacting quantum critical points are difficult to access with conventional field theoretic methods. They are, however, both experimentally important and theoretically interesting. In particular, they are expected to realize universal incoherent transport. Such disordered quantum critical theories have recently been constructed holographically by deforming a CFT by marginally relevant disorder. In this paper we find additional disordered fixed points via relevant disordered deformations of a holographic CFT. Using recently developed methods in holographic transport, we characterize the thermal conductivity in both sets of theories in 1+1 dimensions. The thermal conductivity is found to tend to a constant at low temperatures in one class of fixed points, and to scale as $T^{0.3}$ in the other. Furthermore, in all cases the thermal conductivity exhibits discrete scale invariance, with logarithmic in temperature oscillations superimposed on the low temperature scaling behavior....
Learning the Critical Points for Addition in Matematika GASING
Directory of Open Access Journals (Sweden)
Johannes Hamonangan Siregar
2014-07-01
Full Text Available We propose learning Matematika GASING to help students better understand the addition material. Matematika GASING is a way of learning mathematics in an easy, fun and enjoyable fashion. GASING is short for GAmpang, aSyIk, and menyenaNGkan (Bahasa Indonesia for easy, fun and enjoyable. It was originally developed by Prof. Yohanes Surya at the Surya Institute in Indonesia to improve the mathematics education in Indonesia. In Matematika GASING, there is a step called “the critical point” that needs to be mastered for each topic. The focus of our research is the critical point for addition, that is addition of two numbers between 1 − 10 with a sum less than 20. The subject is a matriculation class at STKIP Surya and the research method used is Classroom Action Research. The statistics obtained is described using Qualitative Descriptive Statistics.
Experimental consequences of quantum critical points at high temperatures
Freitas, D. C.; Rodière, P.; Núñez, M.; Garbarino, G.; Sulpice, A.; Marcus, J.; Gay, F.; Continentino, M. A.; Núñez-Regueiro, M.
2015-11-01
We study the C r1 -xR ex phase diagram finding that its phase transition temperature towards an antiferromagnetic order TN follows a quantum [(xc-x ) /xc ] ψ law, with ψ =1 /2 , from the quantum critical point (QCP) at xc=0.25 up to TN≈600 K . We compare this system to others in order to understand why this elemental material is affected by the QCP up to such unusually high temperatures. We determine a general criterion for the crossover, as a function of an external parameter such as concentration, from the region controlled solely by thermal fluctuations to that where quantum effects become observable. The properties of materials with low coherence lengths will thus be altered far away from the QCP.
On Prop erties of p-critical Points of Convex Bo dies
Institute of Scientific and Technical Information of China (English)
Huang Xing; Guo Qi
2015-01-01
Properties of the p-measures of asymmetry and the corresponding aﬃne equivariant p-critical points, defined recently by the second author, for convex bodies are discussed in this article. In particular, the continuity of p-critical points with respect to p on (1,+∞) is confirmed, and the connections between general p-critical points and the Minkowski-critical points (∞-critical points) are investigated. The behavior of p-critical points of convex bodies approximating a convex bodies is studied as well.
Has the QCD critical point been observed at RHIC? - A Rebuttal
Lacey, Roy A
2016-01-01
This note rebuts an old, but recurring claim by Antoniou, Davis and Diakonos [1] that the critical point and associated critical exponents reported in Ref. [2], is based on an erroneous treatment of scaling relations near the critical point.
Institute of Scientific and Technical Information of China (English)
Shuxiang YU
2006-01-01
Using the concept of an isolated invariant set, some existence criteria of orbits connecting two critical points bifurcating from a single critical point for ordinary differential equations depending on a parameter are given.
Quantum-to-classical crossover near quantum critical point.
Vasin, M; Ryzhov, V; Vinokur, V M
2015-12-21
A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transition from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d + zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T) ∈ [0, 1] decreases with the temperature such that Λ(T = 0) = 1 and Λ(T → ∞) = 0. Our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical crossover.
Universal thermodynamics at the liquid-vapor critical point.
Sanchez, Isaac C; Boening, Kevin L
2014-11-26
For 68 fluids that include hydrogen bonding and quantum fluids, the fugacity coefficient that defines the residual chemical potential adopts a near universal value of 2/3 at the critical point. More precisely, the reciprocal of the fugacity coefficient equals 1.52 ± 0.02 and includes fluids as diverse as helium (1.50), dodecafluoropentane (1.50), and water (1.53). For 65 classical fluids, a dimensionless thermal pressure coefficient and internal pressure attain critical values of 1.88 ± 0.11 and 1.61 ± 0.11, respectively. From equations of state, values of these new critical constants have been calculated and agree favorably with experimental values. Specifically, for the critical fugacity coefficient, the following results were obtained for its reciprocal: van der Waals (1.44), lattice gas (1.43), scaled particle theory (1.46), and the Redlich-Kwong eq (1.50). The semiempirical Redlich-Kwong equation is also the most accurate for the thermal pressure coefficient (1.86) and internal pressure (1.53). Physical interpretations of these results are discussed as well as their implications for other critical phenomena.
Influence of intermolecular forces at critical-point wedge filling.
Malijevský, Alexandr; Parry, Andrew O
2016-04-01
We use microscopic density functional theory to study filling transitions in systems with long-ranged wall-fluid and short-ranged fluid-fluid forces occurring in a right-angle wedge. By changing the strength of the wall-fluid interaction we can induce both wetting and filling transitions over a wide range of temperatures and study the order of these transitions. At low temperatures we find that both wetting and filling transitions are first order in keeping with predictions of simple local effective Hamiltonian models. However close to the bulk critical point the filling transition is observed to be continuous even though the wetting transition remains first order and the wetting binding potential still exhibits a small activation barrier. The critical singularities for adsorption for the continuous filling transitions depend on whether retarded or nonretarded wall-fluid forces are present and are in excellent agreement with predictions of effective Hamiltonian theory even though the change in the order of the transition was not anticipated.
Critical point of the solar wind by radio sounding data
Lotova, N. A.; Oraevsky, V. N.; Pisarenko, Ya. V.; Vladimirskii, K. V.
1995-01-01
Results of the close-to-Sun plasmas sounding at the transonic region of the solar wind, where the sub-to supersonic flow transition proceeds (at 10 to 40 solar radii from the Sun), are presented. Natural sources of two types were used, water vapour maser sources at 1.35 cm and guasars at 2.9 m wavelength. scattering observations cover the period of 1986 to 1993, Russian Academy of Sciences telescopes RT-22 and DCR-1000 were used, IPS index and scattering angle being the immediate results of observations. Extensive studies of the scintillation index and scattering angle radial profiles reveal a remarkable structural detail, 'transonic region forrunner'-narrow region of diminished scattering close to the internal border of the extended transonic region with its characteristic enhanced scattering. Comparisons of the scattering and plasma velocity profiles let it possible to determine the critical point positions by the comparatively simple scattering observations. This new possibility widely improves the process of the basic data accumulation in the fundamental problem of the solar wind acceleration mechanism.
Zooming on the quantum critical point in Nd-LSCO
Energy Technology Data Exchange (ETDEWEB)
Cyr-Choiniere, Olivier, E-mail: olivier.cyr-choiniere@usherbrooke.c [Department de Physique and RQMP, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada); Daou, R.; Chang, J.; Laliberte, Francis; Doiron-Leyraud, Nicolas; LeBoeuf, David [Department de Physique and RQMP, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada); Jo, Y.J.; Balicas, L. [National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310-3706 (United States); Yan, J.-Q. [Ames Laboratory, Ames, IA 50011 (United States); Cheng, J.-G.; Zhou, J.-S.; Goodenough, J.B. [Texas Materials Institute, University of Texas at Austin, Austin, TX 78712 (United States); Taillefer, Louis, E-mail: louis.taillefer@physique.usherbrooke.c [Department de Physique and RQMP, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada); Canadian Institute for Advanced Research, Toronto, Ontario, M5G 1Z8 (Canada)
2010-12-15
Recent studies of the high-T{sub c} superconductor La{sub 1.6-x}Nd{sub 0.4}Sr{sub x}CuO{sub 4} (Nd-LSCO) have found a linear-T in-plane resistivity {rho}{sub ab} and a logarithmic temperature dependence of the thermopower S/T at a hole doping p=0.24 and a Fermi-surface reconstruction just below p=0.24. These are typical signatures of a quantum critical point (QCP). Here we report data on the c-axis resistivity {rho}{sub c}(T) of Nd-LSCO measured as a function of temperature near this QCP, in a magnetic field large enough to entirely suppress superconductivity. Like {rho}{sub ab},{rho}{sub c} shows an upturn at low temperature, a signature of Fermi surface reconstruction caused by stripe order. Tracking the height of the upturn as it decreases with doping enables us to pin down the precise location of the QCP where stripe order ends, at p*=0.235{+-}0.005. We propose that the temperature T{sub {rho}} below which the upturn begins marks the onset of the pseudogap phase, found to be roughly twice as high as the stripe-ordering temperature in this material.
Identification of critical points of thermal environment in broiler production
Directory of Open Access Journals (Sweden)
AG Menezes
2010-03-01
Full Text Available This paper describes an exploratory study carried out to determine critical control points and possible risks in hatcheries and broiler farms. The study was based in the identification of the potential hazards existing in broiler production, from the hatchery to the broiler farm, identifying critical control points and defining critical limits. The following rooms were analyzed in the hatchery: egg cold storage, pre-heating, incubator, and hatcher rooms. Two broiler houses were studied in two different farms. The following data were collected in the hatchery and broiler houses: temperature (ºC and relative humidity (%, air velocity (m s-1, ammonia levels, and light intensity (lx. In the broiler house study, a questionnaire using information of the Broiler Production Good Practices (BPGP manual was applied, and workers were interviewed. Risk analysis matrices were build to determine Critical Control Points (CCP. After data collection, Statistical Process Control (SPC was applied through the analysis of the Process Capacity Index, using the software program Minitab15®. Environmental temperature and relative humidity were the critical points identified in the hatchery and in both farms. The classes determined as critical control points in the broiler houses were poultry litter, feeding, drinking water, workers' hygiene and health, management and biosecurity, norms and legislation, facilities, and activity planning. It was concluded that CCP analysis, associated with SPC control tools and guidelines of good production practices, may contribute to improve quality control in poultry production.
Influence of intermolecular forces at critical-point wedge filling
Malijevský, Alexandr; Parry, Andrew O.
2016-04-01
We use microscopic density functional theory to study filling transitions in systems with long-ranged wall-fluid and short-ranged fluid-fluid forces occurring in a right-angle wedge. By changing the strength of the wall-fluid interaction we can induce both wetting and filling transitions over a wide range of temperatures and study the order of these transitions. At low temperatures we find that both wetting and filling transitions are first order in keeping with predictions of simple local effective Hamiltonian models. However close to the bulk critical point the filling transition is observed to be continuous even though the wetting transition remains first order and the wetting binding potential still exhibits a small activation barrier. The critical singularities for adsorption for the continuous filling transitions depend on whether retarded or nonretarded wall-fluid forces are present and are in excellent agreement with predictions of effective Hamiltonian theory even though the change in the order of the transition was not anticipated.
Dairy production system type and critical points of contamination
Directory of Open Access Journals (Sweden)
Gilberto Henrique Simões
2015-12-01
Full Text Available Current milk production includes a large diversity between systems, which generates difficulties in defining a microbiological standard. The adapted practical and hygienic-sanitary management methods are diverse and introduce great complexity into the production systems. Based on this scenario, the objective of this study was to evaluate the types of dairy production systems of western Parana and to quantify Staphylococcus sp in three critical points in the dairy cattle production systems: the milking machines, milkers’ hands, the cooling tanks and raw milk. A total of 35 samples of refrigerated raw milk were collected, and a questionnaire referring to hygienic and sanitary management was administered. All of the data were collected during the period from September to October 2012 and involved 35 properties in the municipality of Marechal Cândido Rondon – PR. From these data, five groups were formed based on cluster analysis (CHA. The multiple correspondence analysis (MCA presented in the first two dimensions, CP1 (81.43% and CP2 (36.87%, showed the relevance of the variables used, which are sanitary and production management methods, and contamination and control of mastitis, respectively (CP1 and CP2. We found average contamination with 9.9 x 101 CFU/cm2, 2.2x104 CFU/cm2, 28 CFU/ cm2 and 3.8x103 CFU/mL; for milking machines, milkers’ hands, cooling tanks and milk, respectively. The results reveal the presence of staphylococcal agent in dairy production systems regardless of the adopted hygiene and health management protocols. The guidance, planning and adaptation of hygiene and health management systems can significantly improve the microbiological quality of the milk produced, both qualitatively and quantitatively.
Shear Thinning Near the Critical Point of Xenon
Zimmerli, Gregory A.; Berg, Robert F.; Moldover, Michael R.; Yao, Minwu
2008-01-01
We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids, near the critical point of xenon. The data span a wide range of reduced shear rate: 10(exp -3) critical fluctuations. The measurements had a temperature resolution of 0.01 mK and were conducted in microgravity aboard the Space Shuttle Columbia to avoid the density stratification caused by Earth's gravity. The viscometer measured the drag on a delicate nickel screen as it oscillated in the xenon at amplitudes 3 mu,m 430 mu, and frequencies 1 Hz critical scaling. At high frequencies, (omega tau)(exp 2) > gamma-dot tau, C(sub gamma) depends also on both x(sub 0) and omega. The data were compared with numerical calculations based on the Carreau-Yasuda relation for complex fluids: eta(gamma-dot)/eta(0)=[1+A(sub gamma)|gamma-dot tau|](exp - chi(sub eta)/3+chi(sub eta)), where chi(sub eta) =0.069 is the critical exponent for viscosity and mode-coupling theory predicts A(sub gamma) =0.121. For xenon we find A(sub gamma) =0.137 +/- 0.029, in agreement with the mode coupling value. Remarkably, the xenon data close to the critical temperature T(sub c) were independent of the cooling rate (both above and below T(sub c) and these data were symmetric about T(sub c) to within a temperature scale factor. The scale factors for the magnitude of the oscillator s response differed from those for the oscillator's phase; this suggests that the surface tension of the two-phase domains affected the drag on the screen below T(sub c).
Third-order gas-liquid phase transition and the nature of Andrews critical point
Directory of Open Access Journals (Sweden)
Tian Ma
2011-12-01
Full Text Available The main objective of this article is to study the nature of the Andrews critical point in the gas-liquid transition in a physical-vapor transport (PVT system. A dynamical model, consistent with the van der Waals equation near the Andrews critical point, is derived. With this model, we deduce two physical parameters, which interact exactly at the Andrews critical point, and which dictate the dynamic transition behavior near the Andrews critical point. In particular, it is shown that 1 the gas-liquid co-existence curve can be extended beyond the Andrews critical point, and 2 the transition is first order before the critical point, second-order at the critical point, and third order beyond the Andrews critical point. This clearly explains why it is hard to observe the gas-liquid phase transition beyond the Andrews critical point. Furthermore, the analysis leads naturally the introduction of a general asymmetry principle of fluctuations and the preferred transition mechanism for a thermodynamic system. The theoretical results derived in this article are in agreement with the experimental results obtained in (K. Nishikawa and T. Morita, Fluid behavior at supercritical states studied by small-angle X-ray scattering, Journal of Supercritical Fluid, 13 (1998, pp. 143-148. Also, the derived second-order transition at the critical point is consistent with the result obtained in (M. Fisher, Specific heat of a gas near the critical point, Physical Review, 136:6A (1964, pp. A1599-A1604.
Directory of Open Access Journals (Sweden)
Zhengchang Liu
2013-03-01
Full Text Available Intracellular communication from the mitochondria to the nucleus is achieved via the retrograde response. In budding yeast, the retrograde response, also known as the RTG pathway, is regulated positively by Rtg1, Rtg2, Rtg3 and Grr1 and negatively by Mks1, Lst8 and two 14-3-3 proteins, Bmh1/2. Activation of retrograde signaling leads to activation of Rtg1/3, two basic helix-loop-helix leucine zipper transcription factors. Rtg1/3 activation requires Rtg2, a cytoplasmic protein with an N-terminal adenosine triphosphate (ATP binding domain belonging to the actin/Hsp70/sugar kinase superfamily. The critical regulatory step of the retrograde response is the interaction between Rtg2 and Mks1. Rtg2 binds to and inactivates Mks1, allowing for activation of Rtg1/3 and the RTG pathway. When the pathway is inactive, Mks1 has dissociated from Rtg2 and bound to Bmh1/2, preventing activation of Rtg1/3. What signals association or disassociation of Mks1 and Rtg2 is unknown. Here, we show that ATP at physiological concentrations dissociates Mks1 from Rtg2 in a highly cooperative fashion. We report that ATP-mediated dissociation of Mks1 from Rtg2 is conserved in two other fungal species, K. lactis and K. waltii. Activation of Rtg1/3 upregulates expression of genes encoding enzymes catalyzing the first three reactions of the Krebs cycle, which is coupled to ATP synthesis through oxidative phosphorylation. Therefore, we propose that the retrograde response is an ATP homeostasis pathway coupling ATP production with ATP-mediated repression of the retrograde response by releasing Mks1 from Rtg2.
Energy Technology Data Exchange (ETDEWEB)
Annuar, A.; Gandhi, P.; Alexander, D. M.; Lansbury, G. B.; Moro, A. Del [Centre for Extragalactic Astronomy, Department of Physics, University of Durham, South Road, Durham, DH1 3LE (United Kingdom); Arévalo, P. [Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretana N 1111, Playa Ancha, Valparaíso (Chile); Ballantyne, D. R. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Baloković, M.; Brightman, M.; Harrison, F. A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Bauer, F. E. [EMBIGGEN Anillo, Concepción (Chile); Boggs, S. E.; Craig, W. W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Brandt, W. N. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Christensen, F. E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Hickox, R. C. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Matt, G. [Dipartimento di Matematica e Fisica, Universitá degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy); Puccetti, S. [ASI Science Data Center, via Galileo Galilei, I-00044 Frascati (Italy); Ricci, C. [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); and others
2015-12-10
We present two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton, and Swift-BAT, we perform a high-quality broadband spectral analysis of the AGN over two decades in energy (∼0.5–100 keV). Previous X-ray observations suggested that the AGN is obscured by a Compton-thick (CT) column of obscuring gas along our line of sight. However, the lack of high-quality ≳10 keV observations, together with the presence of a nearby X-ray luminous source, NGC 5643 X–1, have left significant uncertainties in the characterization of the nuclear spectrum. NuSTAR now enables the AGN and NGC 5643 X–1 to be separately resolved above 10 keV for the first time and allows a direct measurement of the absorbing column density toward the nucleus. The new data show that the nucleus is indeed obscured by a CT column of N{sub H} ≳ 5 × 10{sup 24} cm{sup −2}. The range of 2–10 keV absorption-corrected luminosity inferred from the best-fitting models is L{sub 2–10,int} = (0.8–1.7) × 10{sup 42} erg s{sup −1}, consistent with that predicted from multiwavelength intrinsic luminosity indicators. In addition, we also study the NuSTAR data for NGC 5643 X–1 and show that it exhibits evidence of a spectral cutoff at energy E ∼ 10 keV, similar to that seen in other ULXs observed by NuSTAR. Along with the evidence for significant X-ray luminosity variations in the 3–8 keV band from 2003 to 2014, our results further strengthen the ULX classification of NGC 5643 X–1.
Critical-point analysis of the liquid-vapor interfacial surface tension
Salvino, R. E.
1990-01-01
The interfacial surface tension of the liquid-vapor system is analyzed near the critical point in a manner similar to bulk thermodynamic critical-point analyses. This is accomplished by a critical-point analysis of the single-phase hard-wall surface tension. Both a Landau expansion and a scaling theory equation of state are investigated. Some general exponent relations are derived and, in addition, some thermodynamically defined correlation lengths are discussed.
Rigidity of critical points for a nonlocal Ohta-Kawasaki energy
Dipierro, Serena; Novaga, Matteo; Valdinoci, Enrico
2017-04-01
We investigate the shape of critical points for a free energy consisting of a nonlocal perimeter plus a nonlocal repulsive term. In particular, we prove that a volume-constrained critical point is necessarily a ball if its volume is sufficiently small with respect to its isodiametric ratio, thus extending a result previously known only for global minimizers. We also show that, at least in one-dimension, there exist critical points with arbitrarily small volume and large isodiametric ratio. This example shows that a constraint on the diameter is, in general, necessary to establish the radial symmetry of the critical points.
Bonatsos, D; Minkov, N; Petrellis, D; Raychev, P P; Terziev, P A; Bonatsos, Dennis
2004-01-01
Davidson potentials of the form $\\beta^2 +\\beta_0^4/\\beta^2$, when used in the E(5) framework, bridge the U(5) and O(6) symmetries, while they bridge the U(5) and SU(3) symmetries when used in the X(5) framework. Using a variational procedure, we determine for each value of angular momentum $L$ thevalue of $\\beta_0$ at which the rate of change of various physical quantities (energy ratios, intraband B(E2) ratios, quadrupole moment ratios) has a maximum, the collection of the values of the physical quantity formed in this way being a candidate for describing its behavior at the relevant critical point. Energy ratios lead to the E(5) and X(5) results (whice correspond to an infinite well potential in $\\beta$), while intraband B(E2) ratios and quadrupole moments lead to the E(5)-$\\beta^4$ and X(5)-$\\beta^4$ results, which correspond to the use of a $\\beta^4$ potential in the relevant framework. A new derivation of the Holmberg-Lipas formula for nuclear energy spectra is obtained as a by-product.
Critical Dynamics : The Expansion of the Master Equation Including a Critical Point
Dekker, H.
1980-01-01
In this thesis it is shown how to solve the master equation for a Markov process including a critical point by means of successive approximations in terms of a small parameter. A critical point occurs if, by adjusting an externally controlled quantity, the system shows a transition from normal monos
Susceptibilities from a black hole engineered EoS with a critical point
Portillo, Israel
2016-01-01
Currently at the Beam Energy Scan at RHIC experimental efforts are being made to find the QCD critical point. On the theoretical side, the behavior of higher-order susceptibilities of the net-baryon charge from Lattice QCD at $\\mu_{_B}\\!=\\!0$ may allow us to estimate the position of the critical point in the QCD phase diagram. However, even if the series expansion continues to higher-orders, there is always the possibility to miss the critical point behavior due to truncation errors. An alternative approach is to use a black hole engineered holographic model, which displays a critical point at large densities and matches lattice susceptibilities at $\\mu_{_B}\\!=\\!0$. Using the thermodynamic data from this black hole model, we obtain the freeze-out points extracted from the net-protons distribution measured at STAR and explore higher order fluctuations at the lowest energies at the beam energy scan to investigate signatures of the critical point.
Łącki, Mateusz; Damski, Bogdan; Zakrzewski, Jakub
2016-12-02
We show that the critical point of the two-dimensional Bose-Hubbard model can be easily found through studies of either on-site atom number fluctuations or the nearest-neighbor two-point correlation function (the expectation value of the tunnelling operator). Our strategy to locate the critical point is based on the observation that the derivatives of these observables with respect to the parameter that drives the superfluid-Mott insulator transition are singular at the critical point in the thermodynamic limit. Performing the quantum Monte Carlo simulations of the two-dimensional Bose-Hubbard model, we show that this technique leads to the accurate determination of the position of its critical point. Our results can be easily extended to the three-dimensional Bose-Hubbard model and different Hubbard-like models. They provide a simple experimentally-relevant way of locating critical points in various cold atomic lattice systems.
Institute of Scientific and Technical Information of China (English)
Feng LI; Yin Lai JIN
2011-01-01
In this paper,center conditions and bifurcation of limit cycles at the nilpotent critical point in a class of quintic polynomial differential system are investigated.With the help of computer algebra system MATHEMATICA,the first 8 quasi Lyapunov constants are deduced.As a result,the necessary and sufficient conditions to have a center are obtained.The fact that there exist 8 small amplitude limit cycles created from the three-order nilpotent critical point is also proved.Henceforth we give a lower bound of cyclicity of three-order nilpotent critical point for quintic Lyapunov systems.
Measurements of the Coexistence Curve near the Liquid-Gas Critical Point
Hahn, Inseob
2003-01-01
The shape of the liquid-gas coexistence curve of He-3 very near the critical point (-2x10(exp -6) critical point was strongly affected by the gravitational field. Away from the critical point, the coexistence curve obtained using this technique was also consistent with the earlier work using the local density measurements of Pittman et al. The recent crossover parametric model of the equation-of-state are used to analyze the height-dependent measured coexistence curves. Data analyses have indicated that microgravity will permit measurements within two additional decades in reduced temperatures beyond the best gravity-free data obtained in Earth-bound experiments.
Evidence for a Disordered Critical Point in a Glass-Forming Liquid.
Berthier, Ludovic; Jack, Robert L
2015-05-22
Using computer simulations of an atomistic glass-forming liquid, we investigate the fluctuations of the overlap between a fluid configuration and a quenched reference system. We find that large fluctuations of the overlap develop as temperature decreases, consistent with the existence of the random critical point that is predicted by effective field theories. We discuss the scaling of fluctuations near the presumed critical point, comparing the observed behavior with that of the random-field Ising model. We argue that this critical point directly reveals the existence of an interfacial tension between amorphous metastable states, a quantity relevant both for equilibrium relaxation and for nonequilibrium melting of stable glass configurations.
Phenomenological consequences of enhanced bulk viscosity near the QCD critical point
Monnai, Akihiko; Mukherjee, Swagato; Yin, Yi
2017-03-01
In the proximity of the QCD critical point the bulk viscosity of quark-gluon matter is expected to be proportional to nearly the third power of the critical correlation length, and become significantly enhanced. This work is the first attempt to study the phenomenological consequences of enhanced bulk viscosity near the QCD critical point. For this purpose, we implement the expected critical behavior of the bulk viscosity within a non-boost-invariant, longitudinally expanding 1 +1 dimensional causal relativistic hydrodynamical evolution at nonzero baryon density. We demonstrate that the critically enhanced bulk viscosity induces a substantial nonequilibrium pressure, effectively softening the equation of state, and leads to sizable effects in the flow velocity and single-particle distributions at the freeze-out. The observable effects that may arise due to the enhanced bulk viscosity in the vicinity of the QCD critical point can be used as complementary information to facilitate searches for the QCD critical point.
Is the critical point for aperture crossing adapted to the person-plus-object system?
Hackney, Amy L; Cinelli, Michael E; Frank, Jim S
2014-01-01
When passing through apertures, individuals scale their actions to their shoulder width and rotate their shoulders or avoid apertures that are deemed too small for straight passage. Carrying objects wider than the body produces a person-plus-object system that individuals must account for in order to pass through apertures safely. The present study aimed to determine whether individuals scale their critical point to the widest horizontal dimension (shoulder or object width). Two responses emerged: Fast adapters adapted to the person-plus-object system by maintaining a consistent critical point regardless of whether the object was carried while slow adapters initially increased their critical point (overestimated) before adapting back to their original critical point. The results suggest that individuals can account for increases in body width by scaling actions to the size of the object width but people adapt at different rates.
The thermodynamics and transport properties of transition metals in critical point
Khomkin, Alexander L
2016-01-01
A new method for calculating the critical point parameters (density, temperature, pressure and electrical conductivity) and binodal of vapor-liquid (dielectric-metal) phase transition is proposed. It is based on the assumption that cohesion, which determines the main properties of solid state, also determines the properties in the vicinity of the critical point. Comparison with experimental and theoretical data available for transition metals is made.
Partial Dynamical Symmetry at Critical-Points of Quantum Phase Transitions
Leviatan, A
2007-01-01
We show that partial dynamical symmetries (PDS) can occur at critical-points of quantum phase transitions, in which case, underlying competing symmetries are conserved exactly by a subset of states, and mix strongly in other states. Several types of PDS are demonstrated with the example of critical-point Hamiltonians for first- and second-order transitions in the framework of the interacting boson model, whose dynamical symmetries correspond to different shape-phases in nuclei.
Critical point quantities and integrability conditions for a class of quintic systems
Institute of Scientific and Technical Information of China (English)
刘一戎; 肖萍
2004-01-01
For a class of quintic systems, the first 16 critical point quantities are obtained by computer algebraic system Mathematica, and the necessary and sufficient conditions that there exists an exact integral in a neighborhood of the origin are also given. The technique employed is essentially different from usual ones. The recursive formula for computation of critical point quantities is linear and then avoids complex integral operations. Some results show an interesting contrast with the related results on quadratic systems.
Leherte, L; Meurice, N; Vercauteren, D P
2000-01-01
A procedure for the comparison of three-dimensional electron density distributions is proposed for similarity searches between pharmacological ligands at various levels of crystallographic resolution. First, a graph representation of molecular electron density distributions is generated using a critical point analysis approach. Pairwise as well as multiple comparisons between the obtained graphs of critical points are then carried out using a Monte Carlo/simulated annealing technique, and results are compared with genetic algorithm solutions.
Visualizing Robustness of Critical Points for 2D Time-Varying Vector Fields
Wang, B.
2013-06-01
Analyzing critical points and their temporal evolutions plays a crucial role in understanding the behavior of vector fields. A key challenge is to quantify the stability of critical points: more stable points may represent more important phenomena or vice versa. The topological notion of robustness is a tool which allows us to quantify rigorously the stability of each critical point. Intuitively, the robustness of a critical point is the minimum amount of perturbation necessary to cancel it within a local neighborhood, measured under an appropriate metric. In this paper, we introduce a new analysis and visualization framework which enables interactive exploration of robustness of critical points for both stationary and time-varying 2D vector fields. This framework allows the end-users, for the first time, to investigate how the stability of a critical point evolves over time. We show that this depends heavily on the global properties of the vector field and that structural changes can correspond to interesting behavior. We demonstrate the practicality of our theories and techniques on several datasets involving combustion and oceanic eddy simulations and obtain some key insights regarding their stable and unstable features. © 2013 The Author(s) Computer Graphics Forum © 2013 The Eurographics Association and Blackwell Publishing Ltd.
Liu, Fu-Hu; Lacey, Roy A
2015-01-01
Experimental results of the rapidity distributions of negatively charged pions produced in proton-proton (p-p) and beryllium-beryllium (Be-Be) collisions at different beam momentums, measured by the NA61/SHINE Collaboration at the super proton synchrotron (SPS), are described by a revised (three-source) Landau hydrodynamic model. The squared speed-of-sound parameter c^2_s is then extracted from the width of rapidity distribution. There is a knee point appearing at about 40A GeV/c (or 8.8 GeV) in the dependence of c^2_s on incident beam momentum (or center-of-mass energy). This knee point can be possibly regarded as the onset of deconfinement of the quarks and gluons in proton-proton collisions, and the critical point of phase transition from hadronic matter to quark-gluon plasma (QGP) in nucleus-nucleus collisions. It is possible that the quark deconfinement and QGP phase transition happen initially in collisions at 8.8 GeV.
Lee, Sang-Hee; Kang, Seung-Ho
2016-10-01
In previous studies, we showed that the branch length similarity (BLS) entropy profile could be used successfully for the recognition of shapes such as battle tanks, facial expressions, and butterflies. In the present study, we introduce critical points defined as a set of distinguishing points with high curvature to the BLS entropy profile in order to improve the shape recognition. In order to generate a given number of critical points from the shape, we propose a critical point detection method. Furthermore, we show the invariant properties of the BLS entropy descriptor. To evaluate the effects of critical points on the shape recognition of the BLS entropy descriptor, we performed a butterfly classification experiment against a real image data set, and we conducted performance comparisons with other point detection methods. In addition, the performance of the BLS entropy descriptor computed using the critical points was compared with those of other well-known descriptors such as the Fourier descriptor using three machine learning techniques, the Bayesian classifier, the multi-layer perceptron and the support vector machine. The results show that the BLS entropy descriptor outperforms other well-known descriptors.
Critical Point Cancellation in 3D Vector Fields: Robustness and Discussion.
Skraba, Primoz; Rosen, Paul; Wang, Bei; Chen, Guoning; Bhatia, Harsh; Pascucci, Valerio
2016-02-29
Vector field topology has been successfully applied to represent the structure of steady vector fields. Critical points, one of the essential components of vector field topology, play an important role in describing the complexity of the extracted structure. Simplifying vector fields via critical point cancellation has practical merit for interpreting the behaviors of complex vector fields such as turbulence. However, there is no effective technique that allows direct cancellation of critical points in 3D. This work fills this gap and introduces the first framework to directly cancel pairs or groups of 3D critical points in a hierarchical manner with a guaranteed minimum amount of perturbation based on their robustness, a quantitative measure of their stability. In addition, our framework does not require the extraction of the entire 3D topology, which contains non-trivial separation structures, and thus is computationally effective. Furthermore, our algorithm can remove critical points in any subregion of the domain whose degree is zero and handle complex boundary configurations, making it capable of addressing challenging scenarios that may not be resolved otherwise. We apply our method to synthetic and simulation datasets to demonstrate its effectiveness.
Can we approach the gas-liquid critical point using slab simulations of two coexisting phases?
Goujon, Florent; Ghoufi, Aziz; Malfreyt, Patrice; Tildesley, Dominic J
2016-09-28
In this paper, we demonstrate that it is possible to approach the gas-liquid critical point of the Lennard-Jones fluid by performing simulations in a slab geometry using a cut-off potential. In the slab simulation geometry, it is essential to apply an accurate tail correction to the potential energy, applied during the course of the simulation, to study the properties of states close to the critical point. Using the Janeček slab-based method developed for two-phase Monte Carlo simulations [J. Janec̆ek, J. Chem. Phys. 131, 6264 (2006)], the coexisting densities and surface tension in the critical region are reported as a function of the cutoff distance in the intermolecular potential. The results obtained using slab simulations are compared with those obtained using grand canonical Monte Carlo simulations of isotropic systems and the finite-size scaling techniques. There is a good agreement between these two approaches. The two-phase simulations can be used in approaching the critical point for temperatures up to 0.97 TC(∗) (T(∗) = 1.26). The critical-point exponents describing the dependence of the density, surface tension, and interfacial thickness on the temperature are calculated near the critical point.
Can we approach the gas-liquid critical point using slab simulations of two coexisting phases?
Goujon, Florent; Ghoufi, Aziz; Malfreyt, Patrice; Tildesley, Dominic J.
2016-09-01
In this paper, we demonstrate that it is possible to approach the gas-liquid critical point of the Lennard-Jones fluid by performing simulations in a slab geometry using a cut-off potential. In the slab simulation geometry, it is essential to apply an accurate tail correction to the potential energy, applied during the course of the simulation, to study the properties of states close to the critical point. Using the Janeček slab-based method developed for two-phase Monte Carlo simulations [J. Janec̆ek, J. Chem. Phys. 131, 6264 (2006)], the coexisting densities and surface tension in the critical region are reported as a function of the cutoff distance in the intermolecular potential. The results obtained using slab simulations are compared with those obtained using grand canonical Monte Carlo simulations of isotropic systems and the finite-size scaling techniques. There is a good agreement between these two approaches. The two-phase simulations can be used in approaching the critical point for temperatures up to 0.97 TC ∗ (T∗ = 1.26). The critical-point exponents describing the dependence of the density, surface tension, and interfacial thickness on the temperature are calculated near the critical point.
The QCD critical point: an exciting Odyssey in the Femto-world
Gavai, Rajiv V.
2016-07-01
Strongly interacting matter, which makes up the nuclei of atoms, is described by a theory called quantum chromodynamics (QCD). A critical point in the phase diagram of QCD, if established either theoretically or experimentally, would be as profound a discovery as the familiar gas-liquid critical point discovered in the nineteenth century. Due to the extremely short-lived nature of the concerned phases, novel experimental techniques are needed to search for it. The Relativistic Heavy Ion Collider (RHIC) in USA has an experimental programme which can fit the bill to do so. Theoretical techniques of Lattice QCD, which is QCD defined on a discrete space-time lattice, have provided glimpses into where the QCD critical point may be, and how to search for it in the experimental data. A brief overview of the theoretical and experimental attempts is provided.
Theory of finite-entanglement scaling at one-dimensional quantum critical points.
Pollmann, Frank; Mukerjee, Subroto; Turner, Ari M; Moore, Joel E
2009-06-26
Studies of entanglement in many-particle systems suggest that most quantum critical ground states have infinitely more entanglement than noncritical states. Standard algorithms for one-dimensional systems construct model states with limited entanglement, which are a worse approximation to quantum critical states than to others. We give a quantitative theory of previously observed scaling behavior resulting from finite entanglement at quantum criticality. Finite-entanglement scaling in one-dimensional systems is governed not by the scaling dimension of an operator but by the "central charge" of the critical point. An important ingredient is the universal distribution of density-matrix eigenvalues at a critical point [P. Calabrese and A. Lefevre, Phys. Rev. A 78, 032329 (2008)10.1103/PhysRevA.78.032329]. The parameter-free theory is checked against numerical scaling at several quantum critical points.
Phenomenological Consequences of Enhanced Bulk Viscosity Near the QCD Critical Point
Monnai, Akihiko; Yin, Yi
2016-01-01
In the proximity of the QCD critical point the bulk viscosity of quark-gluon matter is expected to be proportional to nearly the third power of the critical correlation length, and become significantly enhanced. This work is the first attempt to study the phenomenological consequences of enhanced bulk viscosity near the QCD critical point. For this purpose, we implement the expected critical behavior of the bulk viscosity within a non-boost-invariant, longitudinally expanding $1+1$ dimensional causal relativistic hydrodynamical evolution at non-zero baryon density. We demonstrate that the critically-enhanced bulk viscosity induces a substantial non-equilibrium pressure, effectively softening the equation of state, and leads to sizable effects in the flow velocity and single particle distributions at the freeze-out. The observable effects that may arise due to the enhanced bulk viscosity in the vicinity of the QCD critical point can be used as complimentary information to facilitate searches for the QCD critic...
Degenerate optomechanical parametric oscillators: cooling in the vicinity of a critical point
Degenfeld-Schonburg, Peter; Hartmann, Michael J; Navarrete-Benlloch, Carlos
2015-01-01
Degenerate optomechanical parametric oscillators are optical resonators in which a mechanical degree of freedom is coupled to a cavity mode that is nonlinearly amplified via parametric down-conversion of an external pumping laser. Below a critical pumping power the down-converted field is purely quantum-mechanical, making the theoretical description of such systems very challenging. Here we introduce a theoretical approach that is capable of describing this regime, even at the critical point itself. We find that the down-converted field can induce significant mechanical cooling and identify the process responsible of this as a "cooling by heating" mechanism. Moreover, we show that, contrary to naive expectations and semi-classical predictions, cooling is not optimal at the critical point, where the photon number is largest. Our approach opens the possibility for analyzing further hybrid dissipative quantum systems in the vicinity of critical points.
Completely mixed state is a critical point for three-qubit entanglement
Energy Technology Data Exchange (ETDEWEB)
Tamaryan, Sayatnova, E-mail: sayat@mail.yerphi.am [Department of Theoretical Physics, A. Alikhanyan National Laboratory, Yerevan (Armenia)
2011-06-06
Pure three-qubit states have five algebraically independent and one algebraically dependent polynomial invariants under local unitary transformations and an arbitrary entanglement measure is a function of these six invariants. It is shown that if the reduced density operator of a some qubit is a multiple of the unit operator, than the geometric entanglement measure of the pure three-qubit state is absolutely independent of the polynomial invariants and is a constant for such tripartite states. Hence a one-particle completely mixed state is a critical point for the geometric measure of entanglement. -- Highlights: → Geometric measure of pure three-qubits is expressed in terms of polynomial invariants. → When one Bloch vector is zero the measure is independent of the remaining invariants. → Hence a one-particle completely mixed state is a critical point for the geometric measure. → The existence of the critical points is an inherent feature of the entanglement.
Critical versus spurious fluctuations in the search for the QCD critical point
Hippert, M.; Fraga, E. S.; Santos, E. M.
2016-01-01
The neighborhood of the QCD chiral critical point is characterized by intense fluctuations of the chiral field which could, in principle, generate pronounced experimental signatures. However, experimental uncertainties which are inherent to heavy-ion collisions, as well as the modest size and duration of the formed plasma, will severely attenuate these signatures. Using Monte Carlo techniques, we study second-order event-by-event moments of pions as a prototype for signatures of the chiral critical point based on the enhancement of the correlation length and event-by-event analysis. We test their viability against some realistic ingredients, similar to the ones found in the RHIC beam energy scan program.
Critical versus spurious fluctuations in the search for the QCD critical point
Hippert, Maurício; Santos, Edivaldo M
2015-01-01
The neighborhood of the QCD chiral critical point is characterized by intense fluctuations of the chiral field which could, in principle, generate pronounced experimental signatures. However, experimental uncertainties which are inherent to heavy ion collisions, as well as the modest size and duration of the formed plasma, will severely attenuate these signatures. Using Monte Carlo techniques, we study second-order event-by-event moments of pions as a prototype for signatures of the chiral critical point based on the enhancement of the correlation length and event-by-event analysis. We test their viability against some realistic ingredients, similar to the ones found in the RHIC Beam Energy Scan program.
Indian Academy of Sciences (India)
Ghasem A Afrouzi; Mohammad B Ghaemi; Shirin Mir
2015-11-01
A variety of three-critical-point theorems have been established for nonsmooth functionals, based on a minimax inequality. In this paper, a generalized form of a recent result due to Ricceri is introduced for non-smooth functionals and by a few hypotheses, without any minimax inequality, the existence of at least three critical points with a uniform bound on the norms of solutions, is obtained. Also, as an application, our main theorem is used to obtain at least three anti-periodic solutions for a second order differential inclusion.
Z(5): critical point symmetry for the prolate to oblate nuclear shape phase transition
Energy Technology Data Exchange (ETDEWEB)
Bonatsos, Dennis; Lenis, D.; Petrellis, D.; Terziev, P.A
2004-05-27
A critical point symmetry for the prolate to oblate shape phase transition is introduced, starting from the Bohr Hamiltonian and approximately separating variables for {gamma}=30 deg. Parameter-free (up to overall scale factors) predictions for spectra and B(E2) transition rates are found to be in good agreement with experimental data for {sup 194}Pt, which is supposed to be located very close to the prolate to oblate critical point, as well as for its neighbours ({sup 192}Pt, {sup 196}Pt)
Z(5): Critical point symmetry for the prolate to oblate nuclear shape phase transition
Bonatsos, D; Petrellis, D; Terziev, P A; Bonatsos, Dennis
2004-01-01
A critical point symmetry for the prolate to oblate shape phase transition is introduced, starting from the Bohr Hamiltonian and approximately separating variables for $\\gamma=30^{\\rm o}$. Parameter-free (up to overall scale factors) predictions for spectra and B(E2) transition rates are found to be in good agreement with experimental data for 194-Pt, which is supposed to be located very close to the prolate to oblate critical point, as well as for its neighbours (192-Pt, 196-Pt).
Anomalous waves in gas-liquid mixtures near gas critical point in Gardner equation approximation
Gasenko, V. G.
2016-10-01
The waves in a bubbled incompressible liquid with Van der Waals gas in a bubbles being near critical points is considered in a frame of Gardner equation. It is shown that both coefficients on quadratic and cubic nonlinear terms in Gardner equation change the sign near gas critical point and it results the anomalous waves: negative and limited solitons, kinks, antikinks and breathers. The dynamics and interactions of these waves was studied numerically by high accuracy Fourier methods with periodically boundary conditions. In particular it is revealed that limited solitons always arise from initial distribution with a few identical soliton's pair and stand stable in their form after numerous interactions.
Volume of supercooled water under pressure and the liquid-liquid critical point.
Mishima, Osamu
2010-10-14
The volume of water (H(2)O) was obtained at about 200-275 K and 40-400 MPa by using emulsified water. The plot of volume against temperature showed slightly concave-downward curvature at pressures higher than ≈200 MPa. This is compatible with the liquid-liquid critical-point hypothesis, but hardly with the singularity-free scenario. When the critical point is assumed to exist at ≈50 MPa and ≈223 K, the experimental volume and the derived compressibility are qualitatively described by the modified Fuentevilla-Anisimov scaling equation.
Topology-induced anomalous defect production by crossing a quantum critical point.
Bermudez, A; Patanè, D; Amico, L; Martin-Delgado, M A
2009-04-03
We study the influence of topology on the quench dynamics of a system driven across a quantum critical point. We show how the appearance of certain edge states, which fully characterize the topology of the system, dramatically modifies the process of defect production during the crossing of the critical point. Interestingly enough, the density of defects is no longer described by the Kibble-Zurek scaling, but determined instead by the nonuniversal topological features of the system. Edge states are shown to be robust against defect production, which highlights their topological nature.
Variation of critical point of aging transition in a networked oscillators system.
Huang, Wenwen; Zhang, Xiyun; Hu, Xin; Zou, Yong; Liu, Zonghua; Guan, Shuguang
2014-06-01
In this work, we study the variation of critical point in aging transition in a networked system consisting of both active and inactive oscillators. By theoretical analysis and numerical simulations, we show that the critical point of aging transition actually is determined by the (normalized) cross links between active and inactive subpopulations of oscillators. This reveals how specific configuration of active and inactive oscillators in the network can lead to the variation of transition point. In particular, we investigate how different strategies of targeted inactivation influence the transition point based on the theory. Our results theoretically explain why the low-degree nodes are crucial regarding dynamical robustness in such systems.
Molecular dynamics simulation of a binary mixture near the lower critical point.
Pousaneh, Faezeh; Edholm, Olle; Maciołek, Anna
2016-07-07
2,6-lutidine molecules mix with water at high and low temperatures but in a wide intermediate temperature range a 2,6-lutidine/water mixture exhibits a miscibility gap. We constructed and validated an atomistic model for 2,6-lutidine and performed molecular dynamics simulations of 2,6-lutidine/water mixture at different temperatures. We determined the part of demixing curve with the lower critical point. The lower critical point extracted from our data is located close to the experimental one. The estimates for critical exponents obtained from our simulations are in a good agreement with the values corresponding to the 3D Ising universality class.
The phase transition and classification of critical points in the multistability chemical reactions
Institute of Scientific and Technical Information of China (English)
ChunhuaZHANG; FugenWU; ChunyanWU; FaOU
2000-01-01
In this paper, we study the phase transition and classification of critical points in multistability chemical reaction systems. Referring to the spirit of Landau's theory of phase transitions, this paper deals with the varied transitions and critical phenomena in multistable chemical systems. It is demonstrated that the higher the order of the multistability,the wider the variety of phase transitions will be. A classification scheme of critical points according to the stability criterion and the thermodynamic potential continuity is suggested.It is useful for us to study critical phenomena especially in the non-equilibrium systems including the multi-stable chemical ones.
Implementation of the critical points model in a SFM-FDTD code working in oblique incidence
Energy Technology Data Exchange (ETDEWEB)
Hamidi, M; Belkhir, A; Lamrous, O [Laboratoire de Physique et Chimie Quantique, Universite Mouloud Mammeri, Tizi-Ouzou (Algeria); Baida, F I, E-mail: omarlamrous@mail.ummto.dz [Departement d' Optique P.M. Duffieux, Institut FEMTO-ST UMR 6174 CNRS Universite de Franche-Comte, 25030 Besancon Cedex (France)
2011-06-22
We describe the implementation of the critical points model in a finite-difference-time-domain code working in oblique incidence and dealing with dispersive media through the split field method. Some tests are presented to validate our code in addition to an application devoted to plasmon resonance of a gold nanoparticles grating.
Phase structure, critical points and susceptibilities in Nambu-Jona-Lasinio type models
De Sousa, C A; Ruivo, M C
2008-01-01
We investigate the chiral phase transition at finite temperature and chemical potential within SU(2) and SU(3) Nambu-Jona-Lasinio type models. The behavior of the baryon number susceptibility and the specific heat, in the vicinity of the critical end point, is studied. The class of the critical points is analyzed by calculating critical exponents.
Fermionic quantum critical point of spinless fermions on a honeycomb lattice
Wang, L.; Corboz, P.; Troyer, M.
2014-01-01
Spinless fermions on a honeycomb lattice provide a minimal realization of lattice Dirac fermions. Repulsive interactions between nearest neighbors drive a quantum phase transition from a Dirac semimetal to a charge-density-wave state through a fermionic quantum critical point, where the coupling of
Numerical simulation of turbulent heat transfer close to the critical point
Boersma, B.J.; Pecnik, R.; Nemati, H.; Peeters, J.W.R.
2015-01-01
In this paper we discuss the effect of sharp property variations on the turbulent heat transfer in fluids close the critical point. The governing equations for this flow regime are discussed, a short description of the numerical tools that have been developed to study these flows is given. Finally,
The expansion of the Fokker-Planck equation including a critical point
Dekker, H.; Kampen, N.G. van
1980-01-01
The known expansion of the master equation for weak diffusion in an external potential applies to both the monostable and the bistable case, but fails at the critical point. This can be remedied by taking as zeroth order approximation a suitably defined set of eigenfunctions. The resulting expansion
THE UNIQUENESS OF LIMIT CYCLE AND CRITICAL POINT FOR A CLASS OF CUBIC SYSTEM
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
In this paper,we consider an accompany system concerning some class of cubic system. We then prove that the system has at most one limit cycle. Finally,we obtain the topological structure of both the critical points at infinity and the singular points lying on invariant lines.
Theoretical Analysis of Thermodynamic Measurements near a Liquid-Gas Critical Point
Barmatz, M.; Zhong, Fang; Hahn, Inseob
2003-01-01
Over the years, many ground-based studies have been performed near liquid-gas critical points to elucidate the expected divergences in thermodynamic quantities. The unambiguous interpretation of these studies very near the critical point is hindered by a gravity-induced density stratification. However, these ground-based measurements can give insight into the crossover behavior between the asymptotic critical region near the transition and the mean field region farther away. We have completed a detailed analysis of heat capacity, susceptibility and coexistence curve measurements near the He-3 liquid-gas critical point using the minimal-subtraction renormalization (MSR) scheme within the phi(exp 4) model. This MSR scheme, using only two adjustable parameters, provides a reasonable global fit to all of these experimental measurements in the gravity-free region out to a reduced temperature of |t| approx. 2x10(exp -2). Recently this approach has also been applied to the earlier microgravity measurements of Haupt and Straub in SF(sub 6) with surprising results. The conclusions drawn from the MSR analyses will be presented. Measurements in the gravity-affected region closer to the He-3 critical point have also been analyzed using the recent crossover parametric model (CPM) of the equation-of-state. The results of fitting heat capacity measurements to the CPM model along the He-3 critical isochore in the gravity-affected region will also be presented.
Dielectric Function and Critical Point of GeSbTe Pseudo-binary Compound Thin Films
Lee, Hosun; Park, Jun-Woo; Kang, Youn-Seon; Lee, Tae-Yon; Suh, Dong-Seok; Kim, Ki-Joon; Kim, Cheol Kyu; Kang, Yoon Ho; da Silva, Juarez L. F.
2009-03-01
We measure the dielectric functions of GeSbTe pseudo-binary thin films by using spectroscopic ellipsometry. We anneal the thin films at various temperatures. According to x-ray diffraction, the as-grown thin films are amorphous and the annealed films have metastable and stable crystalline phases. By using standard critical point model, we obtain the accurate values of the energy gap of the amorphous phase as well as the critical point energies of the crystalline thin films. The critical point energies are compared to the band gap energies determined by the method of linear extrapolation of the optical absorption. As the Sb to Ge atomic ratio increases, the optical (band) gap energy of amorphous (crystalline) phase decreases. Standard critical point fitting show several higher band gaps. The electronic band structures and the dielectric functions of the thin films are calculated by using density functional theory and are compared to the measured ones. The band structure calculations show in stable phase that GeTe, Ge2Sb2Te5, and Ge1Sb2Te4 have indirect gap whereas Ge1Sb4Te7 and Sb2Te3 have direct gap. The measured indirect band gap energies match well with the electronic band structure calculations.
Critical points for finite Fibonacci chains of point delta-interactions and orthogonal polynomials
Energy Technology Data Exchange (ETDEWEB)
De Prunele, E, E-mail: eprunele@univ-fcomte.fr [Institut UTINAM, UMR CNRS 6213, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France)
2011-10-21
For a one-dimensional Schroedinger operator with a finite number n of point delta-interactions with a common intensity, the parameters are the intensity, the n - 1 intercenter distances and the mass. Critical points are points in the parameters space of the Hamiltonian where one bound state appears or disappears. The study of critical points for Hamiltonians with point delta-interactions arranged along a Fibonacci chain is shown to be closely related to the study of the so-called Fibonacci operator, a discrete one-dimensional Schroedinger-type operator, which occurs in the context of tight binding Hamiltonians. These critical points are the zeros of orthogonal polynomials previously studied in the context of special diatomic linear chains with elastic nearest-neighbor interaction. Properties of the zeros (location, asymptotic behavior, gaps, ...) are investigated. The perturbation series from the solvable periodic case is determined. The measure which yields orthogonality is investigated numerically from the zeros. It is shown that the transmission coefficient at zero energy can be expressed in terms of the orthogonal polynomials and their associated polynomials. In particular, it is shown that when the number of point delta-interactions is equal to a Fibonacci number minus 1, i.e. when the intervals between point delta-interactions form a palindrome, all the Fibonacci chains at critical points are completely transparent at zero energy. (paper)
On the creations of critical points in scale space with applications to medical image analysis
Kuijper, Arjan; Florack, L.M.J.
2002-01-01
In order to investigate the deep structure of Gaussian scale space images, one needs to understand the behaviour of spatial critical points under the influence of blurring. We show how the mathematical framework of catastrophe theory can be used to describe the various different types of annihilatio
Functional renormalization group analysis of the soft mode at the QCD critical point
Yokota, Takeru; Kunihiro, Teiji; Morita, Kenji
2016-07-01
We make an intensive investigation of the soft mode at the quantum chromodynamics (QCD) critical point on the basis of the functional renormalization group (FRG) method in the local potential approximation. We calculate the spectral functions ρ_{σ, π}(ω, p) in the scalar (σ) and pseudoscalar (π) channels beyond the random phase approximation in the quark-meson model. At finite baryon chemical potential μ with a finite quark mass, the baryon-number fluctuation is coupled to the scalar channel and the spectral function in the σ channel has a support not only in the time-like (ω > p) but also in the space-like (ω position of the latter becomes vanishingly small with the height being enhanced as the system approaches the QCD critical point, which is a manifestation of the fact that the phonon mode is the soft mode associated with the second-order transition at the QCD critical point, as has been suggested by some authors. Moreover, our extensive calculation of the spectral function in the (ω, p) plane enables us to see that the mesonic and phonon modes have the respective definite dispersion relations ω_{σ.ph}(p), and it turns out that ω_{σ}(p) crosses the light-cone line into the space-like region, and then eventually merges into the phonon mode as the system approaches the critical point more closely. This implies that the sigma-mesonic mode also becomes soft at the critical point. We also provide numerical stability conditions that are necessary for obtaining the accurate effective potential from the flow equation.
Zhu, Lijun; Garst, Markus; Rosch, Achim; Si, Qimiao
2003-08-08
At a generic quantum critical point, the thermal expansion alpha is more singular than the specific heat c(p). Consequently, the "Grüneisen ratio," Gamma=alpha/c(p), diverges. When scaling applies, Gamma approximately T(-1/(nu z)) at the critical pressure p=p(c), providing a means to measure the scaling dimension of the most relevant operator that pressure couples to; in the alternative limit T-->0 and p not equal p(c), Gamma approximately 1/(p-p(c)) with a prefactor that is, up to the molar volume, a simple universal combination of critical exponents. For a magnetic-field driven transition, similar relations hold for the magnetocaloric effect (1/T) partial differential T/ partial differential H|(S). Finally, we determine the corrections to scaling in a class of metallic quantum critical points.
Viscosity of net-baryon fluid near the QCD critical point
Antoniou, N G; Kapoyannis, A S
2016-01-01
In the dynamics of the QCD critical point, the net-baryon fluid, linked to the slow component of the order parameter, relaxes to a 3d Ising system in equilibrium. The transport coefficients develop power-law singularities in the limit $T \\rightarrow T_c$, $\\mu_b=\\mu_c$, associated with the critical exponents of the 3d Ising universality class. An analytical study of shear and bulk viscosity, with constraints imposed by universality and the requirements of a class of strong coupling theories, is performed in the neighbourhood of the critical point. It is found that the shear viscosity of the net-baryon fluid is restricted in the domain $1.6\\leq 4\\pi\\frac{\\eta}{s}\\leq 3.7$ for $T_c 1.23 T_c$) but rising towards the singularity at $T=T_c$.
Baugher, Benjamin
2008-01-01
We prove the main conjecture from [M. R. Douglas, B. Shiffman and S. Zelditch, Critical points and supersymmetric vacua, II: Asymptotics and extremal metrics. J. Differential Geom. 72 (2006), no. 3, 381-427] concerning the metric dependence and asymptotic minimization of the expected number \\mathcal{N}^{crit}_{N,h} of critical points of random holomorphic sections of the Nth tensor power of a positive line bundle. The first non-topological term in the asymptotic expansion of \\mathcal{N}^{crit}_{N,h} is the the Calabi functional multiplied by the constant \\be_2(m) which depends only on the dimension of the manifold. We prove that \\be_2(m) is strictly positive in all dimensions, showing that the expansion is non-topological for all m, and that the Calabi extremal metric, when it exists, asymptotically minimizes \\mathcal{N}^{crit}_{N,h}.
Determination of liquid-liquid critical point composition using 90∘ laser light scattering
Williamson, J. Charles; Brown, Allison M.; Helvie, Elise N.; Dean, Kevin M.
2016-04-01
Despite over a century of characterization efforts, liquid-liquid critical point compositions are difficult to identify with good accuracy. Reported values vary up to 10% for even well-studied systems. Here, a technique is presented for high-precision determination of the critical composition of a partially miscible binary liquid system. Ninety-degree laser light-scattering intensities from single-phase samples are analyzed using an equation derived from nonclassical power laws and the pseudospinodal approximation. Results are reported for four liquid-liquid systems (aniline + hexane, isobutyric acid + water, methanol + cyclohexane, and methanol + carbon disulfide). Compared to other methods, the 90∘ light-scattering approach has a strong dependence on composition near the critical point, is less affected by temperature fluctuations, and is insensitive to the presence of trace impurities in the samples. Critical compositions found with 90∘ light scattering are precise to the parts-per-thousand level and show long-term reproducibility.
Kallin, Ann B; Hyatt, Katharine; Singh, Rajiv R P; Melko, Roger G
2013-03-29
We develop a method to calculate the bipartite entanglement entropy of quantum models, in the thermodynamic limit, using a numerical linked-cluster expansion (NLCE) involving only rectangular clusters. It is based on exact diagonalization of all n×m rectangular clusters at the interface between entangled subsystems A and B. We use it to obtain the Renyi entanglement entropy of the two-dimensional transverse field Ising model, for arbitrary real Renyi index α. Extrapolating these results as a function of the order of the calculation, we obtain universal pieces of the entanglement entropy associated with lines and corners at the quantum critical point. They show NLCE to be one of the few methods capable of accurately calculating universal properties of arbitrary Renyi entropies at higher dimensional critical points.
Classical dynamics of the Abelian Higgs model from the critical point and beyond
Directory of Open Access Journals (Sweden)
G.C. Katsimiga
2015-09-01
Full Text Available We present two different families of solutions of the U(1-Higgs model in a (1+1 dimensional setting leading to a localization of the gauge field. First we consider a uniform background (the usual vacuum, which corresponds to the fully higgsed-superconducting phase. Then we study the case of a non-uniform background in the form of a domain wall which could be relevantly close to the critical point of the associated spontaneous symmetry breaking. For both cases we obtain approximate analytical nodeless and nodal solutions for the gauge field resulting as bound states of an effective Pöschl–Teller potential created by the scalar field. The two scenaria differ only in the scale of the characteristic localization length. Numerical simulations confirm the validity of the obtained analytical solutions. Additionally we demonstrate how a kink may be used as a mediator driving the dynamics from the critical point and beyond.
BEHAVIOUR OF A THREE-DIMENSIONAL UNIAXIAL MAGNET NEAR THE CRITICAL POINT IN AN EXTERNAL FIELD
Directory of Open Access Journals (Sweden)
M.P.Kozlovskii
2004-01-01
Full Text Available The behaviour of a three-dimensional magnet with a one-component order parameter near the critical point in a homogeneous external field is investigated. The calculations are performed in the case when the field and temperature are dependent and related by some expression (the system tends to the critical point along some trajectory. The high- and low-temperature regions in the vicinity of Tc (Tc is the phase transition temperature in the absence of an external field are considered. It is shown that in the weak fields the system behaviour is described in general by the temperature variable, but in the case of the strong fields the role of the temperature variable is not dominant. The corresponding expressions for the free energy, susceptibility and other characteristics of the system are obtained for each of these regions.
Zhang, Zhao
2010-01-01
The combined effect of the repulsive vector interaction and the positive electric chemical potential on the chiral phase transition is investigated by considering neutral color superconductivity. Under the charge-neutrality constraint, the chiral condensate, diquark condensate and quark number densities are obtained in two-plus-one-flavor Nambu-Jona-Lasinio model with the so called Kobayashi-Maskawa-'t Hooft term. We demonstrate that multiple chiral critical-point structures always exist in the Nambu-Jona-Lasinio model within the self-consistent mean-field approximation, and that the number of chiral critical points can vary from zero to four, which is dependent on the magnitudes of vector interaction and the diquark coupling.
Critical exponents and scaling invariance in the absence of a critical point.
Saratz, N; Zanin, D A; Ramsperger, U; Cannas, S; Pescia, D; Vindigni, A
2016-12-05
The paramagnetic-to-ferromagnetic phase transition is classified as a critical phenomenon due to the power-law behaviour shown by thermodynamic observables when the Curie point is approached. Here we report the observation of such a behaviour over extraordinarily many decades of suitable scaling variables in ultrathin Fe films, for certain ranges of temperature T and applied field B. This despite the fact that the underlying critical point is practically unreachable because protected by a phase with a modulated domain structure, induced by the dipole-dipole interaction. The modulated structure has a well-defined spatial period and is realized in a portion of the (T, B) plane that extends above the putative critical temperature, where thermodynamic quantities do not display any singularity. Our results imply that scaling behaviour of macroscopic observables is compatible with an avoided critical point.
Determination of liquid-liquid critical point composition using 90^{∘} laser light scattering.
Williamson, J Charles; Brown, Allison M; Helvie, Elise N; Dean, Kevin M
2016-04-01
Despite over a century of characterization efforts, liquid-liquid critical point compositions are difficult to identify with good accuracy. Reported values vary up to 10% for even well-studied systems. Here, a technique is presented for high-precision determination of the critical composition of a partially miscible binary liquid system. Ninety-degree laser light-scattering intensities from single-phase samples are analyzed using an equation derived from nonclassical power laws and the pseudospinodal approximation. Results are reported for four liquid-liquid systems (aniline + hexane, isobutyric acid + water, methanol + cyclohexane, and methanol + carbon disulfide). Compared to other methods, the 90^{∘} light-scattering approach has a strong dependence on composition near the critical point, is less affected by temperature fluctuations, and is insensitive to the presence of trace impurities in the samples. Critical compositions found with 90^{∘} light scattering are precise to the parts-per-thousand level and show long-term reproducibility.
A Model for Hydrogen Thermal Conductivity and Viscosity Including the Critical Point
Wagner, Howard A.; Tunc, Gokturk; Bayazitoglu, Yildiz
2001-01-01
In order to conduct a thermal analysis of heat transfer to liquid hydrogen near the critical point, an accurate understanding of the thermal transport properties is required. A review of the available literature on hydrogen transport properties identified a lack of useful equations to predict the thermal conductivity and viscosity of liquid hydrogen. The tables published by the National Bureau of Standards were used to perform a series of curve fits to generate the needed correlation equations. These equations give the thermal conductivity and viscosity of hydrogen below 100 K. They agree with the published NBS tables, with less than a 1.5 percent error for temperatures below 100 K and pressures from the triple point to 1000 KPa. These equations also capture the divergence in the thermal conductivity at the critical point
Athermal domain-wall creep near a ferroelectric quantum critical point.
Kagawa, Fumitaka; Minami, Nao; Horiuchi, Sachio; Tokura, Yoshinori
2016-02-16
Ferroelectric domain walls are typically stationary because of the presence of a pinning potential. Nevertheless, thermally activated, irreversible creep motion can occur under a moderate electric field, thereby underlying rewritable and non-volatile memory applications. Conversely, as the temperature decreases, the occurrence of creep motion becomes less likely and eventually impossible under realistic electric-field magnitudes. Here we show that such frozen ferroelectric domain walls recover their mobility under the influence of quantum fluctuations. Nonlinear permittivity and polarization-retention measurements of an organic charge-transfer complex reveal that ferroelectric domain-wall creep occurs via an athermal process when the system is tuned close to a pressure-driven ferroelectric quantum critical point. Despite the heavy masses of material building blocks such as molecules, the estimated effective mass of the domain wall is comparable to the proton mass, indicating the realization of a ferroelectric domain wall with a quantum-particle nature near the quantum critical point.
Nanoporous Materials Can Tune the Critical Point of a Pure Substance.
Braun, Efrem; Chen, Joseph J; Schnell, Sondre K; Lin, Li-Chiang; Reimer, Jeffrey A; Smit, Berend
2015-11-23
Molecular simulations and NMR relaxometry experiments demonstrate that pure benzene or xylene confined in isoreticular metal-organic frameworks (IRMOFs) exhibit true vapor-liquid phase equilibria where the effective critical point may be reduced by tuning the structure of the MOF. Our results are consistent with vapor and liquid phases extending over many MOF unit cells. These results are counterintuitive since the MOF pore diameters are approximately the same length scale as the adsorbate molecules. As applications of these materials in catalysis, separations, and gas storage rely on the ability to tune the properties of adsorbed molecules, we anticipate that the ability to systematically control the critical point, thereby preparing spatially inhomogeneous local adsorbate densities, could add a new design tool for MOF applications.
Equation of state and critical point behavior of hard-core double-Yukawa fluids.
Montes, J; Robles, M; López de Haro, M
2016-02-28
A theoretical study on the equation of state and the critical point behavior of hard-core double-Yukawa fluids is presented. Thermodynamic perturbation theory, restricted to first order in the inverse temperature and having the hard-sphere fluid as the reference system, is used to derive a relatively simple analytical equation of state of hard-core multi-Yukawa fluids. Using such an equation of state, the compressibility factor and phase behavior of six representative hard-core double-Yukawa fluids are examined and compared with available simulation results. The effect of varying the parameters of the hard-core double-Yukawa intermolecular potential on the location of the critical point is also analyzed using different perspectives. The relevance of this analysis for fluids whose molecules interact with realistic potentials is also pointed out.
Equation of state and critical point behavior of hard-core double-Yukawa fluids
Montes, J.; Robles, M.; López de Haro, M.
2016-02-01
A theoretical study on the equation of state and the critical point behavior of hard-core double-Yukawa fluids is presented. Thermodynamic perturbation theory, restricted to first order in the inverse temperature and having the hard-sphere fluid as the reference system, is used to derive a relatively simple analytical equation of state of hard-core multi-Yukawa fluids. Using such an equation of state, the compressibility factor and phase behavior of six representative hard-core double-Yukawa fluids are examined and compared with available simulation results. The effect of varying the parameters of the hard-core double-Yukawa intermolecular potential on the location of the critical point is also analyzed using different perspectives. The relevance of this analysis for fluids whose molecules interact with realistic potentials is also pointed out.
Itinerant Magnetism and the Ferromagnetic Quantum Critical Point in Fe(Ga,Ge)3
Singh, David J.
2014-03-01
FeGa3 is a tetragonal semiconductor with a band gap of ~0.5 eV and interesting thermoelectric properties. It shows diamagnetic behavior but when modestly electron doped by Ge, a ferromagnetic quantum critical point emerges and the ground state becomes a ferromagnetic metal. We present first-principles calculations showing that the magnetism can be readily explained in an itinerant picture without the need for preexisting moments in the semiconducting state and without the need for correlation terms. We also present Boltzmann transport calculations of the thermopower. Itinerant magnetism implies strong coupling between the electrons at the Fermi energy that control transport and the magnetism. Thus, FeGa3 may be a particularly interesting material near a quantum critical point. We find that the ferromagnetic state is half-metallic over a substantial composition range. Work supported by the Department of Energy, BES, Materials Sciences and Engineering Division.
Classical dynamics of the Abelian Higgs model from the critical point and beyond
Katsimiga, G. C.; Diakonos, F. K.; Maintas, X. N.
2015-09-01
We present two different families of solutions of the U(1)-Higgs model in a (1 + 1) dimensional setting leading to a localization of the gauge field. First we consider a uniform background (the usual vacuum), which corresponds to the fully higgsed-superconducting phase. Then we study the case of a non-uniform background in the form of a domain wall which could be relevantly close to the critical point of the associated spontaneous symmetry breaking. For both cases we obtain approximate analytical nodeless and nodal solutions for the gauge field resulting as bound states of an effective Pöschl-Teller potential created by the scalar field. The two scenaria differ only in the scale of the characteristic localization length. Numerical simulations confirm the validity of the obtained analytical solutions. Additionally we demonstrate how a kink may be used as a mediator driving the dynamics from the critical point and beyond.
Nanoporous Materials Can Tune the Critical Point of a Pure Substance
Energy Technology Data Exchange (ETDEWEB)
Braun, Efrem; Chen, Joseph J.; Schnell, Sondre K.; Lin, Li-Chiang; Reimer, Jeffrey A.; Smit, Berend
2015-09-30
Molecular simulations and NMR relaxometry experiments demonstrate that pure benzene or xylene confined in isoreticular metal–organic frameworks (IRMOFs) exhibit true vapor–liquid phase equilibria where the effective critical point may be reduced by tuning the structure of the MOF. Our results are consistent with vapor and liquid phases extending over many MOF unit cells. These results are counterintuitive since the MOF pore diameters are approximately the same length scale as the adsorbate molecules. As applications of these materials in catalysis, separations, and gas storage rely on the ability to tune the properties of adsorbed molecules, we anticipate that the ability to systematically control the critical point, thereby preparing spatially inhomogeneous local adsorbate densities, could add a new design tool for MOF applications.
Noise levels at critical points in the municipality of Guadalajara, Jalisco, Mexico
Figueroa, Arturo; Garcia, Jesus; Macias, Jorge; Orozco, Martha; Garcia, Javier; Delgadillo, Alan
2002-11-01
Studies of acoustic conditions are planning tools on which we can diagnose the problem of noise pollution in the cities. The first study on noise pollution made in the city was made by the University of Guadalajara in 1995 and updated in 1998 covering with measuring points the city center. This paper discusses the problem of noise pollution by motor vehicles at critical points and covers a total of 105 points. The study also analyzes the problem of noise pollution base on the community annoyance from which a regulation policy should derive. Results of the study show that the most critical points are located within zone 1 (center) where Leq levels within the range of 70-85 dB were found. Such levels exceed by far the international standard of 65 dB as recommended for ambient noise by the World Health Organization.
Self-assembly in chains, rings, and branches: a single component system with two critical points.
Rovigatti, Lorenzo; Tavares, José Maria; Sciortino, Francesco
2013-10-18
We study the interplay between phase separation and self-assembly in chains, rings, and branched structures in a model of particles with dissimilar patches. We extend Wertheim's first order perturbation theory to include the effects of ring formation and to theoretically investigate the thermodynamics of the model. We find a peculiar shape for the vapor-liquid coexistence, featuring reentrant behavior in both phases and two critical points, despite the single-component nature of the system. The emergence of the lower critical point is caused by the self-assembly of rings taking place in the vapor, generating a phase with lower energy and lower entropy than the liquid. Monte Carlo simulations of the same model fully support these unconventional theoretical predictions.
Barlow, Nathaniel S; Schultz, Andrew J; Weinstein, Steven J; Kofke, David A
2015-08-21
The mathematical structure imposed by the thermodynamic critical point motivates an approximant that synthesizes two theoretically sound equations of state: the parametric and the virial. The former is constructed to describe the critical region, incorporating all scaling laws; the latter is an expansion about zero density, developed from molecular considerations. The approximant is shown to yield an equation of state capable of accurately describing properties over a large portion of the thermodynamic parameter space, far greater than that covered by each treatment alone.
Universal free-energy distribution in the critical point of a random Ising ferromagnet.
Dotsenko, Victor; Holovatch, Yurij
2014-11-01
We discuss the non-self-averaging phenomena in the critical point of weakly disordered Ising ferromagnet. In terms of the renormalized replica Ginzburg-Landau Hamiltonian in dimensions Dcritical free-energy fluctuations. In particular, using known fixed-point values for the renormalized coupling parameters, we obtain the universal curve for such PDF in the dimension D=3. It is demonstrated that this function is strongly asymmetric: its left tail is much slower than the right one.
Second-order magnetic critical points at finite magnetic fields: Revisiting Arrott plots
Bustingorry, S.; Pomiro, F.; Aurelio, G.; Curiale, J.
2016-06-01
The so-called Arrott plot, which consists in plotting H /M against M2, with H the applied magnetic field and M the magnetization, is used to extract valuable information in second-order magnetic phase transitions. Besides, it is widely accepted that a negative slope in the Arrott plot is indicative of a first-order magnetic transition. This is known as the Banerjee criterion. In consequence, the zero-field transition temperature T* is reported as the characteristic first-order transition temperature. By carefully analyzing the mean-field Landau model used for studying first-order magnetic transitions, we show in this work that T* corresponds in fact to a triple point where three first-order lines meet. More importantly, this analysis reveals the existence of two symmetrical second-order critical points at finite magnetic field (Tc,±Hc) . We then show that a modified Arrott plot can be used to obtain information about these second-order critical points. To support this idea we analyze experimental data on La2 /3Ca1 /3MnO3 and discuss an estimate for the location of the triple point and the second-order critical points.
Overlapping Modularity at the Critical Point of k-Clique Percolation
Tóth, Bálint; Vicsek, Tamás; Palla, Gergely
2013-05-01
One of the most remarkable social phenomena is the formation of communities in social networks corresponding to families, friendship circles, work teams, etc. Since people usually belong to several different communities at the same time, the induced overlaps result in an extremely complicated web of the communities themselves. Thus, uncovering the intricate community structure of social networks is a non-trivial task with great potential for practical applications, gaining a notable interest in the recent years. The Clique Percolation Method (CPM) is one of the earliest overlapping community finding methods, which was already used in the analysis of several different social networks. In this approach the communities correspond to k-clique percolation clusters, and the general heuristic for setting the parameters of the method is to tune the system just below the critical point of k-clique percolation. However, this rule is based on simple physical principles and its validity was never subject to quantitative analysis. Here we examine the quality of the partitioning in the vicinity of the critical point using recently introduced overlapping modularity measures. According to our results on real social and other networks, the overlapping modularities show a maximum close to the critical point, justifying the original criteria for the optimal parameter settings.
Study of the ST2 model of water close to the liquid-liquid critical point.
Sciortino, Francesco; Saika-Voivod, Ivan; Poole, Peter H
2011-11-28
We perform successive umbrella sampling grand canonical Monte Carlo computer simulations of the original ST2 model of water in the vicinity of the proposed liquid-liquid critical point, at temperatures above and below the critical temperature. Our results support the previous work of Y. Liu, A. Z. Panagiotopoulos and P. G. Debenedetti [J. Chem. Phys., 2009, 131, 104508], who provided evidence for the existence and location of the critical point for ST2 using the Ewald method to evaluate the long-range forces. Our results therefore demonstrate the robustness of the evidence for critical behavior with respect to the treatment of the electrostatic interactions. In addition, we verify that the liquid is equilibrated at all densities on the Monte Carlo time scale of our simulations, and also that there is no indication of crystal formation during our runs. These findings demonstrate that the processes of liquid-state relaxation and crystal nucleation are well separated in time. Therefore, the bimodal shape of the density of states, and hence the critical point itself, is a purely liquid-state phenomenon that is distinct from the crystal-liquid transition.
Behavior of the dielectric constant of Ar near the critical point.
Hidalgo, Marcelo; Coutinho, Kaline; Canuto, Sylvio
2015-03-01
The fundamental question of the behavior of the dielectric constant near the critical point is addressed using Ar as the probe system. The neighborhood of the liquid-vapor critical point of Ar is accessed by classical Monte Carlo simulation and then explicit quantum mechanics calculations are performed to study the behavior of the dielectric constant. The theoretical critical temperature is determined by calculating the position of the discontinuity of the specific heat and is found to be at T(c)Theor=148.7K, only 2 K below the experimental value. The large fluctuations and the inhomogeneity of the density that characterize the critical point rapidly disappear and are not seen at T=T(c)Theor+2K. The structure of Ar obtained by the radial distribution function is found to be in very good agreement with experiment both in the liquid phase and 2 K above the critical temperature. The behavior of the dielectric constant is then analyzed after calculating the static dipole polarizability and using a many-body Clausius-Mossotti equation. The dielectric constant shows a density-independent behavior around the critical density, 2 K above the critical temperature. At this point, the calculated value of the dielectric constant is 1.173±0.005 in excellent agreement with the experimental value of 1.179.
Fermi-surface collapse and dynamical scaling near a quantum-critical point.
Friedemann, Sven; Oeschler, Niels; Wirth, Steffen; Krellner, Cornelius; Geibel, Christoph; Steglich, Frank; Paschen, Silke; Kirchner, Stefan; Si, Qimiao
2010-08-17
Quantum criticality arises when a macroscopic phase of matter undergoes a continuous transformation at zero temperature. While the collective fluctuations at quantum-critical points are being increasingly recognized as playing an important role in a wide range of quantum materials, the nature of the underlying quantum-critical excitations remains poorly understood. Here we report in-depth measurements of the Hall effect in the heavy-fermion metal YbRh(2)Si(2), a prototypical system for quantum criticality. We isolate a rapid crossover of the isothermal Hall coefficient clearly connected to the quantum-critical point from a smooth background contribution; the latter exists away from the quantum-critical point and is detectable through our studies only over a wide range of magnetic field. Importantly, the width of the critical crossover is proportional to temperature, which violates the predictions of conventional theory and is instead consistent with an energy over temperature, E/T, scaling of the quantum-critical single-electron fluctuation spectrum. Our results provide evidence that the quantum-dynamical scaling and a critical Kondo breakdown simultaneously operate in the same material. Correspondingly, we infer that macroscopic scale-invariant fluctuations emerge from the microscopic many-body excitations associated with a collapsing Fermi-surface. This insight is expected to be relevant to the unconventional finite-temperature behavior in a broad range of strongly correlated quantum systems.
Critical points of the cosmic velocity and the uncertainties in the value of the Hubble constant
Liu, Hao; Naselsky, Pavel
2016-01-01
The existence of critical points for the peculiar velocity field is a natural feature of the correlated vector field. These points appear in contact zones of the velocity domains with different orientation of the averaged velocity vector. At the same time peculiar velocities are the cause of the scatter of the Hubble expansion rate. We propose that a more precise determination of the Hubble constant can be made by restricting analysis to subsample of observational data containing only the zones around the critical points of the peculiar velocity field, associated with voids and saddle points. On large-scales the critical points where the first derivative of the gravitational potential vanishes can be easily identified using the density field and classified by the behavior of the Hessian of the gravitational potential. We use high- resolution N-body simulations to show that these regions are stable in time and hence are excellent tracers of the initial conditions. Furthermore, we show that the variance of the ...
Measurements of the Coexistence Curve near the Liquid-Gas Critical Point
Hahn, Inseob
2003-01-01
The shape of the liquid-gas coexistence curve of He-3 very near the critical point (-2x10(exp -6) < t < -5x10(exp -3) was measured using the quasi-static thermogram method. The study was performed in Earth s gravitational field using two different height calorimetry cells, both originally designed for simultaneous measurements of the isochoric heat capacity, isothermal compressibility, and PVT. The heights of two cells were 0.5 mm and 4.8 cm. The uncertainty in measuring the phase transition temperature was typically +/-2 micro-K. The measured coexistence curve near the critical point was strongly affected by the gravitational field. Away from the critical point, the coexistence curve obtained using this technique was also consistent with the earlier work using the local density measurements of Pittman et al. The recent crossover parametric model of the equation-of-state are used to analyze the height-dependent measured coexistence curves. Data analyses have indicated that microgravity will permit measurements within two additional decades in reduced temperatures beyond the best gravity-free data obtained in Earth-bound experiments.
X(3): An Exactly Separable Gamma-Rigid Version of the X(5) Critical Point Symmetry
Bonatsos, D; Petrellis, D; Terziev, P A; Yigitoglu, I; Bonatsos, Dennis
2006-01-01
A gamma-rigid version (with gamma=0) of the X(5) critical point symmetry is constructed. The model, to be called X(3) since it is proved to contain three degrees of freedom, utilizes an infinite well potential, is based on exact separation of variables, and leads to parameter free (up to overall scale factors) predictions for spectra and B(E2) transition rates, which are in good agreement with existing experimental data for 172-Os and 186-Pt. An unexpected similarity of the first beta bands of the X(5) nuclei 150-Nd, 152-Sm, 154-Gd, and 156-Dy to the X(3) predictions is observed.
Influence of the ferroelectric quantum critical point on SrTiO3 interfaces
Atkinson, W. A.; Lafleur, P.; Raslan, A.
2017-02-01
We study a model SrTiO3 interface in which conduction t2 g electrons couple to the ferroelectric (FE) phonon mode. We treat the FE mode within a self-consistent phonon theory that captures its quantum critical behavior and show that proximity to the quantum critical point leads to universal tails in the electron density of the form n (z ) ˜(λ+z ) -2 , where λ ˜T2 -d /z , with d =3 the dimensionality and z =1 the dynamical critical exponent. Implications for the metal-insulator transition at low electron density are discussed.
Regularity and chaos at critical points of first-order quantum phase transitions
Macek, Michal
2011-01-01
We study the interplay between regular and chaotic dynamics at the critical point of a first order quantum shape-phase transition in an interacting boson model of nuclei. A classical analysis reveals a distinct behavior of the coexisting phases in a broad energy range. The dynamics is completely regular in the deformed phase while it becomes strongly chaotic in the spherical phase. A quantum analysis of the spectra separates the regular states from the irregular ones, assigns them to particular phases and discloses persisting regular rotational bands in the deformed region.
Scaled Correlations of Critical Points of Random Sections on Riemann Surfaces
Baber, John
2011-01-01
In this thesis we prove that as N goes to infinity, the scaling limit of the correlation between critical points z1 and z2 of random holomorphic sections of the N-th power of a positive line bundle over a compact Riemann surface tends to 2/(3pi^2) for small sqrt(N)|z1-z2|. The scaling limit is directly calculated using a general form of the Kac-Rice formula and formulas and theorems of Pavel Bleher, Bernard Shiffman, and Steve Zelditch.
Scaled Correlations of Critical Points of Random Sections on Riemann Surfaces
Baber, John
2012-08-01
In this paper we prove that as N goes to infinity, the scaling limit of the correlation between critical points z 1 and z 2 of random holomorphic sections of the N-th power of a positive line bundle over a compact Riemann surface tends to 2/(3 π 2) for small sqrt{N}|z1-nobreak z2|. The scaling limit is directly calculated using a general form of the Kac-Rice formula and formulas and theorems of Pavel Bleher, Bernard Shiffman, and Steve Zelditch.
4d/5d Correspondence for the Black Hole Potential and its Critical Points
Ceresole, A; Marrani, A
2007-01-01
We express the d=4, N=2 black hole effective potential for cubic holomorphic F functions and generic dyonic charges in terms of d=5 real special geometry data. The 4d critical points are computed from the 5d ones, and their relation is elucidated. For symmetric spaces, we identify the BPS and non-BPS classes of attractors and the respective entropies. These are related by simple formulae, interpolating between four and five dimensions, depending on the volume modulus and on the 4d magnetic (or electric) charges, and holding true also for generic field configurations and for non-symmetric cubic geometries.
Superconductivity and non-Fermi liquid behavior near a nematic quantum critical point
Lederer, Samuel; Schattner, Yoni; Berg, Erez; Kivelson, Steven A.
2017-05-01
Using determinantal quantum Monte Carlo, we compute the properties of a lattice model with spin mn>1mn>mn>2mn>12 itinerant electrons tuned through a quantum phase transition to an Ising nematic phase. The nematic fluctuations induce superconductivity with a broad dome in the superconducting TcTc enclosing the nematic quantum critical point. For temperatures above TcTc, we see strikingly non-Fermi liquid behavior, including a “nodal-antinodal dichotomy” reminiscent of that seen in several transition metal oxides. In addition, the critical fluctuations have a strong effect on the low-frequency optical conductivity, resulting in behavior consistent with “bad metal” phenomenology.
Existence of a line of critical points in a two-dimensional Lebwohl Lasher model
Energy Technology Data Exchange (ETDEWEB)
Shabnam, Sabana [Department of Physics, Lady Brabourne College, Kolkata 700017 (India); DasGupta, Sudeshna, E-mail: sudeshna.dasgupta10@gmail.com [Department of Physics, Lady Brabourne College, Kolkata 700017 (India); Roy, Soumen Kumar [Department of Physics, Jadavpur University, Kolkata 700032 (India)
2016-02-15
Controversy regarding transitions in systems with global symmetry group O(3) has attracted the attention of researchers and the detailed nature of this transition is still not well understood. As an example of such a system in this paper we have studied a two-dimensional Lebwohl Lasher model, using the Wolff cluster algorithm. Though we have not been able to reach any definitive conclusions regarding the order present in the system, from finite size scaling analysis, hyperscaling relations and the behavior of the correlation function we have obtained strong indications regarding the presence of quasi-long range order and the existence of a line of critical points in our system.
Existence of a line of critical points in a two-dimensional Lebwohl Lasher model
Shabnam, Sabana; DasGupta, Sudeshna; Roy, Soumen Kumar
2016-02-01
Controversy regarding transitions in systems with global symmetry group O(3) has attracted the attention of researchers and the detailed nature of this transition is still not well understood. As an example of such a system in this paper we have studied a two-dimensional Lebwohl Lasher model, using the Wolff cluster algorithm. Though we have not been able to reach any definitive conclusions regarding the order present in the system, from finite size scaling analysis, hyperscaling relations and the behavior of the correlation function we have obtained strong indications regarding the presence of quasi-long range order and the existence of a line of critical points in our system.
Lattice determination of the critical point of QCD at finite $T$ and $\\mu$
Fodor, Z
2002-01-01
Based on universal arguments it is believed that there is a critical point (E) in QCD on the temperature (T) versus chemical potential (\\mu) plane, which is of extreme importance for heavy-ion experiments. Using finite size scaling and a recently proposed lattice method to study QCD at finite \\mu we determine the location of E in QCD with n_f=2+1 dynamical staggered quarks with semi-realistic masses on L_t=4 lattices. Our result is T_E=160 \\pm 3.5 MeV and
Duality between the Deconfined Quantum-Critical Point and the Bosonic Topological Transition
Qin, Yan Qi; He, Yuan-Yao; You, Yi-Zhuang; Lu, Zhong-Yi; Sen, Arnab; Sandvik, Anders W.; Xu, Cenke; Meng, Zi Yang
2017-07-01
Recently, significant progress has been made in (2 +1 )-dimensional conformal field theories without supersymmetry. In particular, it was realized that different Lagrangians may be related by hidden dualities; i.e., seemingly different field theories may actually be identical in the infrared limit. Among all the proposed dualities, one has attracted particular interest in the field of strongly correlated quantum-matter systems: the one relating the easy-plane noncompact CP1 model (NCCP1 ) and noncompact quantum electrodynamics (QED) with two flavors (N =2 ) of massless two-component Dirac fermions. The easy-plane NCCP1 model is the field theory of the putative deconfined quantum-critical point separating a planar (X Y ) antiferromagnet and a dimerized (valence-bond solid) ground state, while N =2 noncompact QED is the theory for the transition between a bosonic symmetry-protected topological phase and a trivial Mott insulator. In this work, we present strong numerical support for the proposed duality. We realize the N =2 noncompact QED at a critical point of an interacting fermion model on the bilayer honeycomb lattice and study it using determinant quantum Monte Carlo (QMC) simulations. Using stochastic series expansion QMC simulations, we study a planar version of the S =1 /2 J -Q spin Hamiltonian (a quantum X Y model with additional multispin couplings) and show that it hosts a continuous transition between the X Y magnet and the valence-bond solid. The duality between the two systems, following from a mapping of their phase diagrams extending from their respective critical points, is supported by the good agreement between the critical exponents according to the proposed duality relationships. In the J -Q model, we find both continuous and first-order transitions, depending on the degree of planar anisotropy, with deconfined quantum criticality surviving only up to moderate strengths of the anisotropy. This explains previous claims of no deconfined quantum
Transport Properties near Quantum Critical Point in 2D Hubbard Model
Chen, Kuang-Shing; Pathak, Sandeep; Yang, Shuxiang; Su, Shi-Quan; Galanakis, Dimitris; Mikelsons, Karlis; Moreno, Juana; Jarrell, Mark
2011-03-01
We obtain high quality estimates of the self energy Σ (K , ω) by direct analytic continuation of Σ (K , iωn) obtained from Continuous-Time Quantum Monte Carlo. We use these results to investigate the transport properties near the quantum critical point found in the 2D Hubbard model at finite doping. Resistivity, thermal conductivity, Wiedemann-Franz Law, and thermopower are examined in the Fermi liquid, Marginal Fermi liquid (MFL), and pseudo-gap regions. Σ (k , ω) with k along the nodal direction displays temperature-dependent scaling similar to that seen in the experiment. A next-nearest neighbor hopping tOISE-0730290.
Energy Technology Data Exchange (ETDEWEB)
Comerford, Julia M. [Astronomy Department, University of Texas at Austin, Austin, TX 78712 (United States); Gerke, Brian F. [Kavli Institute for Particle Astrophysics and Cosmology, M/S 29, Stanford Linear Accelerator Center, 2575 Sand Hill Road, Menlo Park, CA 94725 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, MS 169-221, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Cooper, Michael C. [Center for Galaxy Evolution, Department of Physics and Astronomy, University of California, Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Weiner, Benjamin J. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Newman, Jeffrey A. [Department of Physics and Astronomy, Pittsburgh Particle Physics, Astrophysics, and Cosmology Center, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Madsen, Kristin [Space Radiation Laboratory, California Institute of Technology, MS 105-24, Pasadena, CA 91125 (United States); Barrows, R. Scott [Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, AR 72701 (United States)
2012-07-01
Merger-remnant galaxies with kiloparsec (kpc) scale separation dual active galactic nuclei (AGNs) should be widespread as a consequence of galaxy mergers and triggered gas accretion onto supermassive black holes, yet very few dual AGNs have been observed. Galaxies with double-peaked narrow AGN emission lines in the Sloan Digital Sky Survey (SDSS) are plausible dual AGN candidates, but their double-peaked profiles could also be the result of gas kinematics or AGN-driven outflows and jets on small or large scales. To help distinguish between these scenarios, we have obtained spatial profiles of the AGN emission via follow-up long-slit spectroscopy of 81 double-peaked narrow-line AGNs in SDSS at 0.03 {<=} z {<=} 0.36 using Lick, Palomar, and MMT Observatories. We find that all 81 systems exhibit double AGN emission components with {approx}kpc projected spatial separations on the sky (0.2 h{sup -1}{sub 70} kpc <{Delta}x < 5.5 h{sup -1}{sub 70} kpc; median {Delta}x = 1.1 h{sup -1}{sub 70} kpc), which suggests that they are produced by kiloparsec-scale dual AGNs or kiloparsec-scale outflows, jets, or rotating gaseous disks. Further, the objects split into two subpopulations based on the spatial extent of the double emission components and the correlation between projected spatial separations and line-of-sight velocity separations. These results suggest that the subsample (58{sup +5}{sub -6}%) of the objects with spatially compact emission components may be preferentially produced by dual AGNs, while the subsample (42{sup +6}{sub -5}%) with spatially extended emission components may be preferentially produced by AGN outflows. We also find that for 32{sup +8}{sub -6}% of the sample the two AGN emission components are preferentially aligned with the host galaxy major axis, as expected for dual AGNs orbiting in the host galaxy potential. Our results both narrow the list of possible physical mechanisms producing the double AGN components, and suggest several observational
Dielectric function and critical points of AlP determined by spectroscopic ellipsometry
Energy Technology Data Exchange (ETDEWEB)
Hwang, S.Y.; Kim, T.J.; Jung, Y.W.; Barange, N.S.; Park, H.G.; Kim, J.Y.; Kang, Y.R. [Nano-Optical Property Laboratory and Department of Physics, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Kim, Y.D., E-mail: ydkim@khu.ac.kr [Nano-Optical Property Laboratory and Department of Physics, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Shin, S.H.; Song, J.D. [Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Liang, C.-T.; Chang, Y.-C. [Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan (China)
2014-02-25
Highlights: • We report the dielectric function ε of AlP from 0.74 to 6.54 eV. • The critical points (CPs) in the E{sub 2} spectral range are important for band-structure analysis. • We extract ε of AlP, using the multilayer parametric model. • The CP energies are obtained from numerically calculated second-energy-derivatives. • We identify these CPs from the linear augmented Slater-type orbital method. -- Abstract: We report the room-temperature dielectric function ε of AlP from 0.74 to 6.54 eV obtained by in situ spectroscopic ellipsometry. Measurements were done on a 1.2 μm thick film grown on (0 0 1) GaAs by molecular beam epitaxy, with ε extracted using a multilayer parametric model. Critical point energies of features in the ε spectra were obtained from numerically calculated second-energy-derivatives, and their Brillouin-zone origins identified by band-structure calculations done using the linear augmented Slater-type orbital method.
Intrinsic low pass filtering improves signal-to-noise ratio in critical-point flexure biosensors
Energy Technology Data Exchange (ETDEWEB)
Jain, Ankit; Alam, Muhammad Ashraful, E-mail: alam@purdue.edu [School of ECE, Purdue University, West Lafayette, Indiana 47906 (United States)
2014-08-25
A flexure biosensor consists of a suspended beam and a fixed bottom electrode. The adsorption of the target biomolecules on the beam changes its stiffness and results in change of beam's deflection. It is now well established that the sensitivity of sensor is maximized close to the pull-in instability point, where effective stiffness of the beam vanishes. The question: “Do the signal-to-noise ratio (SNR) and the limit-of-detection (LOD) also improve close to the instability point?”, however remains unanswered. In this article, we systematically analyze the noise response to evaluate SNR and establish LOD of critical-point flexure sensors. We find that a flexure sensor acts like an effective low pass filter close to the instability point due to its relatively small resonance frequency, and rejects high frequency noise, leading to improved SNR and LOD. We believe that our conclusions should establish the uniqueness and the technological relevance of critical-point biosensors.
Pseudo-critical point in anomalous phase diagrams of simple plasma models
Chigvintsev, A. Yu; Iosilevskiy, I. L.; Noginova, L. Yu
2016-11-01
Anomalous phase diagrams in subclass of simplified (“non-associative”) Coulomb models is under discussion. The common feature of this subclass is absence on definition of individual correlations for charges of opposite sign. It is e.g. modified OCP of ions on uniformly compressible background of ideal Fermi-gas of electrons OCP(∼), or a superposition of two non-ideal OCP(∼) models of ions and electrons etc. In contrast to the ordinary OCP model on non-compressible (“rigid”) background OCP(#) two new phase transitions with upper critical point, boiling and sublimation, appear in OCP(∼) phase diagram in addition to the well-known Wigner crystallization. The point is that the topology of phase diagram in OCP(∼) becomes anomalous at high enough value of ionic charge number Z. Namely, the only one unified crystal- fluid phase transition without critical point exists as continuous superposition of melting and sublimation in OCP(∼) at the interval (Z 1 equation of state provided by Chabrier and Potekhin (1998 Phys. Rev. E 58 4941).
Search for a liquid-liquid critical point in models of silica
Lascaris, Erik; Hemmati, Mahin; Buldyrev, Sergey V.; Stanley, H. Eugene; Angell, C. Austen
2014-06-01
Previous research has indicated the possible existence of a liquid-liquid critical point (LLCP) in models of silica at high pressure. To clarify this interesting question we run extended molecular dynamics simulations of two different silica models (WAC and BKS) and perform a detailed analysis of the liquid at temperatures much lower than those previously simulated. We find no LLCP in either model within the accessible temperature range, although it is closely approached in the case of the WAC potential near 4000 K and 5 GPa. Comparing our results with those obtained for other tetrahedral liquids, and relating the average Si-O-Si bond angle and liquid density at the model glass temperature to those of the ice-like β-cristobalite structure, we conclude that the absence of a critical point can be attributed to insufficient "stiffness" in the bond angle. We hypothesize that a modification of the potential to mildly favor larger average bond angles will generate a LLCP in a temperature range that is accessible to simulation. The tendency to crystallize in these models is extremely weak in the pressure range studied, although this tendency will undoubtedly increase with increasing stiffness.
Functional renormalization group analysis of the soft mode at the QCD critical point
Yokota, Takeru; Morita, Kenji
2016-01-01
We make an intensive investigation of the soft mode at the QCD critical point on the basis of the the functional renormalization group (FRG) method in the local potential approximation. We calculate the the spectral functions $\\rho_{\\sigma, \\pi}(\\omega, p)$ in the scalar ($\\sigma$) and pseudoscalar ($\\pi$) channels beyond the random phase approximation in the quark-meson model. At finite baryon chemical potential $\\mu$ with a finite quark mass, the baryon-number fluctuation is coupled to the scalar channel and the spectral function in the $\\sigma$ channel has a support not only in the time-like ($\\omega > p$) and but also in the space-like ($\\omega < p$) regions, which correspond to the mesonic and the particle-hole phonon excitations, respectively. We find that the energy of the peak position of the latter becomes vanishingly small with the height being enhanced as the system approaches the QCD critical point, which is a manifestation of the fact that the phonon mode is the soft mode associated with the s...
Institute of Scientific and Technical Information of China (English)
万永革; 吴忠良; 周公威
2003-01-01
Whether or not a small stress change can trigger a big earthquake is one of the most important problems related to the critical point hypothesis for earthquakes. We investigate global earthquakes with different focal mechanisms which have different levels of ambient shear stress. This ambient stress level is the stress level required by the earthquakes for their occurrence. Earthquake pairs are studied to see whether the occurrence of the preceding event encourages the occurrence of the succeeding one in terms of the Coulomb stress triggering. It is observed that the stress triggering effect produced by the change of Coulomb failure stress in the same order of magnitudes,about 10-2 MPa, is distinctly different for different focal mechanisms, and thus for different ambient stress levels.For non-strike-slip earthquakes with a relatively low ambient stress level, the triggering effect is more evident,while for strike-slip earthquakes with a relatively high ambient stress level, there is no evident triggering effect.This water level test provides an observational support to the critical point hypothesis for earthquakes.
Scaling dimensions of higher-charge monopoles at deconfined critical points
Sreejith, G. J.; Powell, Stephen
2015-11-01
The classical cubic dimer model has a columnar ordering transition that is continuous and described by a critical Anderson-Higgs theory containing an SU (2 ) -symmetric complex field minimally coupled to a noncompact U (1 ) gauge theory. Defects in the dimer constraints correspond to monopoles of the gauge theory, with charge determined by the deviation from unity of the dimer occupancy. By introducing such defects into Monte Carlo simulations of the dimer model at its critical point, we determine the scaling dimensions y2=1.48 ±0.07 and y3=0.20 ±0.03 for the operators corresponding to defects of charge q =2 and 3, respectively. These results, which constitute the first direct determination of the scaling dimensions, shed light on the deconfined critical point of spin-1/2 quantum antiferromagnets, thought to belong to the same universality class. In particular, the positive value of y3 implies that the transition in the J Q model on the honeycomb lattice is of first order.
The phase and critical point of quantum Einstein-Cartan gravity
Xue, She-Sheng
2012-05-01
By introducing diffeomorphism and local Lorentz gauge invariant holonomy fields, we study in the recent article [S.-S. Xue, Phys. Rev. D 82 (2010) 064039] the quantum Einstein-Cartan gravity in the framework of Regge calculus. On the basis of strong coupling expansion, mean-field approximation and dynamical equations satisfied by holonomy fields, we present in this Letter calculations and discussions to show the phase structure of the quantum Einstein-Cartan gravity, (i) the order phase: long-range condensations of holonomy fields in strong gauge couplings; (ii) the disorder phase: short-range fluctuations of holonomy fields in weak gauge couplings. According to the competition of the activation energy of holonomy fields and their entropy, we give a simple estimate of the possible ultra-violet critical point and correlation length for the second-order phase transition from the order phase to disorder one. At this critical point, we discuss whether the continuum field theory of quantum Einstein-Cartan gravity can be possibly approached when the macroscopic correlation length of holonomy field condensations is much larger than the Planck length.
Heat capacity singularity of binary liquid mixtures at the liquid-liquid critical point.
Méndez-Castro, Pablo; Troncoso, Jacobo; Peleteiro, José; Romaní, Luis
2013-10-01
The critical anomaly of the isobaric molar heat capacity for the liquid-liquid phase transition in binary nonionic mixtures is explained through a theory based on the general assumption that their partition function can be exactly mapped into that of the Ising three-dimensional model. Under this approximation, it is found that the heat capacity singularity is directly linked to molar excess enthalpy. In order to check this prediction and complete the available data for such systems, isobaric molar heat capacity and molar excess enthalpy near the liquid-liquid critical point were experimentally determined for a large set of binary liquid mixtures. Agreement between theory and experimental results-both from literature and from present work-is good for most cases. This fact opens a way for explaining and predicting the heat capacity divergence at the liquid-liquid critical point through basically the same microscopic arguments as for molar excess enthalpy, widely used in the frame of solution thermodynamics.
Change of carrier density at the pseudogap critical point of a cuprate superconductor.
Badoux, S; Tabis, W; Laliberté, F; Grissonnanche, G; Vignolle, B; Vignolles, D; Béard, J; Bonn, D A; Hardy, W N; Liang, R; Doiron-Leyraud, N; Taillefer, Louis; Proust, Cyril
2016-03-10
The pseudogap is a partial gap in the electronic density of states that opens in the normal (non-superconducting) state of cuprate superconductors and whose origin is a long-standing puzzle. Its connection to the Mott insulator phase at low doping (hole concentration, p) remains ambiguous and its relation to the charge order that reconstructs the Fermi surface at intermediate doping is still unclear. Here we use measurements of the Hall coefficient in magnetic fields up to 88 tesla to show that Fermi-surface reconstruction by charge order in the cuprate YBa2Cu3Oy ends sharply at a critical doping p = 0.16 that is distinctly lower than the pseudogap critical point p* = 0.19 (ref. 11). This shows that the pseudogap and charge order are separate phenomena. We find that the change in carrier density n from n = 1 + p in the conventional metal at high doping (ref. 12) to n = p at low doping (ref. 13) starts at the pseudogap critical point. This shows that the pseudogap and the antiferromagnetic Mott insulator are linked.
Infrared conformality and bulk critical points: SU(2) with heavy adjoint quarks
Lucini, Biagio; Rago, Antonio; Rinaldi, Enrico
2013-01-01
The lattice phase structure of a gauge theory can be a serious obstruction to Monte Carlo studies of its continuum behaviour. This issue is particularly delicate when numerical studies are performed to determine whether a theory is in a (near-)conformal phase. In this work we investigate the heavy mass limit of the SU(2) gauge theory with Nf=2 adjoint fermions and its lattice phase diagram, showing the presence of a critical point ending a line of first order bulk phase transition. The relevant gauge observables and the low-lying spectrum are monitored in the vicinity of the critical point with very good control over different systematic effects. The scaling properties of masses and susceptibilities open the possibility that the effective theory at criticality is a scalar theory in the universality class of the four-dimensional Gaussian model. This behaviour is clearly different from what is observed for SU(2) gauge theory with two dynamical adjoint fermions, whose (near-)conformal numerical signature is henc...
del Campo, Adolfo; Rams, Marek M; Zurek, Wojciech H
2012-09-14
The dynamics of a quantum phase transition is inextricably woven with the formation of excitations, as a result of critical slowing down in the neighborhood of the critical point. We design a transitionless quantum driving through a quantum critical point, allowing one to access the ground state of the broken-symmetry phase by a finite-rate quench of the control parameter. The method is illustrated in the one-dimensional quantum Ising model in a transverse field. Driving through the critical point is assisted by an auxiliary Hamiltonian, for which the interplay between the range of the interaction and the modes where excitations are suppressed is elucidated.
Apfelbaum, E M
2012-12-20
The critical-point coordinates of Beryllium have been calculated by means of recently found similarity relations between the Zeno-line and the critical-point parameters. We have used the NVT MC simulations and pseudopotential theory to calculate the Zeno-line parameters together with the data of isobaric measurements to construct the liquid branch of Beryllium binodal. The critical-point coordinates, determined this way, are lower than earlier estimates. We have shown that these previous estimates are in evident contradiction with available measurements data. Present investigation can resolve this contradiction if the measurements data are supposed to be reliable.
Exotic quantum critical point on the surface of three-dimensional topological insulator
Bi, Zhen; You, Yi-Zhuang; Xu, Cenke
2016-07-01
In the last few years a lot of exotic and anomalous topological phases were constructed by proliferating the vortexlike topological defects on the surface of the 3 d topological insulator (TI) [Fidkowski et al., Phys. Rev. X 3, 041016 (2013), 10.1103/PhysRevX.3.041016; Chen et al., Phys. Rev. B 89, 165132 (2014), 10.1103/PhysRevB.89.165132; Bonderson et al., J. Stat. Mech. (2013) P09016, 10.1088/1742-5468/2013/09/P09016; Wang et al., Phys. Rev. B 88, 115137 (2013), 10.1103/PhysRevB.88.115137; Metlitski et al., Phys. Rev. B 92, 125111 (2015), 10.1103/PhysRevB.92.125111]. In this work, rather than considering topological phases at the boundary, we will study quantum critical points driven by vortexlike topological defects. In general, we will discuss a (2 +1 )d quantum phase transition described by the following field theory: L =ψ ¯γμ(∂μ-i aμ) ψ +| (∂μ-i k aμ) ϕ| 2+r|ϕ | 2+g |ϕ| 4 , with tuning parameter r , arbitrary integer k , Dirac fermion ψ , and complex scalar bosonic field ϕ , which both couple to the same (2 +1 )d dynamical noncompact U(1) gauge field aμ. The physical meaning of these quantities/fields will be explained in the text. Making use of the new duality formalism developed in [Metlitski et al., Phys. Rev. B 93, 245151 (2016), 10.1103/PhysRevB.93.245151; Wang et al., Phys. Rev. X 5, 041031 (2015), 10.1103/PhysRevX.5.041031; Wang et al., Phys. Rev. B 93, 085110 (2016), 10.1103/PhysRevB.93.085110; D. T. Son, Phys. Rev. X 5, 031027 (2015), 10.1103/PhysRevX.5.031027], we demonstrate that this quantum critical point has a quasi-self-dual nature. And at this quantum critical point, various universal quantities such as the electrical conductivity and scaling dimension of gauge-invariant operators, can be calculated systematically through a 1 /k2 expansion, based on the observation that the limit k →+∞ corresponds to an ordinary 3 d X Y transition.
Zhang, Chendong
2015-09-21
By using a comprehensive form of scanning tunneling spectroscopy, we have revealed detailed quasi-particle electronic structures in transition metal dichalcogenides, including the quasi-particle gaps, critical point energy locations, and their origins in the Brillouin zones. We show that single layer WSe surprisingly has an indirect quasi-particle gap with the conduction band minimum located at the Q-point (instead of K), albeit the two states are nearly degenerate. We have further observed rich quasi-particle electronic structures of transition metal dichalcogenides as a function of atomic structures and spin-orbit couplings. Such a local probe for detailed electronic structures in conduction and valence bands will be ideal to investigate how electronic structures of transition metal dichalcogenides are influenced by variations of local environment.
X(3): an exactly separable {gamma}-rigid version of the X(5) critical point symmetry
Energy Technology Data Exchange (ETDEWEB)
Bonatsos, Dennis [Institute of Nuclear Physics, NCSR ' Demokritos' , GR-15310 Aghia Paraskevi, Attiki (Greece)]. E-mail: bonat@inp.demokritos.gr; Lenis, D. [Institute of Nuclear Physics, NCSR ' Demokritos' , GR-15310 Aghia Paraskevi, Attiki (Greece)]. E-mail: lenis@inp.demokritos.gr; Petrellis, D. [Institute of Nuclear Physics, NCSR ' Demokritos' , GR-15310 Aghia Paraskevi, Attiki (Greece)]. E-mail: petrellis@inp.demokritos.gr; Terziev, P.A. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 72 Tzarigrad Road, BG-1784 Sofia (Bulgaria)]. E-mail: terziev@inrne.bas.bg; Yigitoglu, I. [Institute of Nuclear Physics, NCSR ' Demokritos' , GR-15310 Aghia Paraskevi, Attiki (Greece) and Hasan Ali Yucel Faculty of Education, Istanbul University, TR-34470 Beyazit, Istanbul (Turkey)]. E-mail: yigitoglu@istanbul.edu.tr
2006-01-12
A {gamma}-rigid version (with {gamma}=0) of the X(5) critical point symmetry is constructed. The model, to be called X(3) since it is proved to contain three degrees of freedom, utilizes an infinite well potential, is based on exact separation of variables, and leads to parameter free (up to overall scale factors) predictions for spectra and B(E2) transition rates, which are in good agreement with existing experimental data for {sup 172}Os and {sup 186}Pt. An unexpected similarity of the {beta}{sub 1}-bands of the X(5) nuclei {sup 150}Nd, {sup 152}Sm, {sup 154}Gd, and {sup 156}Dy to the X(3) predictions is observed.
The Subtle Balance between Lipolysis and Lipogenesis: A Critical Point in Metabolic Homeostasis
Directory of Open Access Journals (Sweden)
Chiara Saponaro
2015-11-01
Full Text Available Excessive accumulation of lipids can lead to lipotoxicity, cell dysfunction and alteration in metabolic pathways, both in adipose tissue and peripheral organs, like liver, heart, pancreas and muscle. This is now a recognized risk factor for the development of metabolic disorders, such as obesity, diabetes, fatty liver disease (NAFLD, cardiovascular diseases (CVD and hepatocellular carcinoma (HCC. The causes for lipotoxicity are not only a high fat diet but also excessive lipolysis, adipogenesis and adipose tissue insulin resistance. The aims of this review are to investigate the subtle balances that underlie lipolytic, lipogenic and oxidative pathways, to evaluate critical points and the complexities of these processes and to better understand which are the metabolic derangements resulting from their imbalance, such as type 2 diabetes and non alcoholic fatty liver disease.
Oral Mucosal Disorders: Problems and Questions What are the Critical Points?
Directory of Open Access Journals (Sweden)
A. Tülin Mansur
2012-12-01
Full Text Available Oral mucosal disorders comprise more than 200 pathological conditions or diseases, grouped in different categories including genetic, inflammatory, infectious and neoplastic. In this report the key points in diagnosis and treatment of oral mucosal disorders are briefly underlined, and indications, precautions, and contraindications are pointed out. In addition, some clues are given to the dermatologists for management of common symptoms of oral disorders, such as pain, dry mouth and halitosis, which greatly disrupt the quality of life. Moreover, the frequently encountered problems in daily practice including contact stomatitis, effects of dental prostheses, dental materials, and topical agents on oral mucosa, and the critical points in surgical interventions of oral disorders are reviewed.
Motif based hierarchical random graphs: structural properties and critical points of an Ising model
Kotorowicz, M; 10.5488/CMP.14.13801
2011-01-01
A class of random graphs is introduced and studied. The graphs are constructed in an algorithmic way from five motifs which were found in [Milo R., Shen-Orr S., Itzkovitz S., Kashtan N., Chklovskii D., Alon U., Science, 2002, 298, 824-827]. The construction scheme resembles that used in [Hinczewski M., A. Nihat Berker, Phys. Rev. E, 2006, 73, 066126], according to which the short-range bonds are non-random, whereas the long-range bonds appear independently with the same probability. A number of structural properties of the graphs have been described, among which there are degree distributions, clustering, amenability, small-world property. For one of the motifs, the critical point of the Ising model defined on the corresponding graph has been studied.
Overlapping modularity at the critical point of k-clique percolation
Toth, Balint; Palla, Gergely
2013-01-01
One of the most remarkable social phenomena is the formation of communities in social networks corresponding to families, friendship circles, work teams, etc. Since people usually belong to several different communities at the same time, the induced overlaps result in an extremely complicated web of the communities themselves. Thus, uncovering the intricate community structure of social networks is a non-trivial task with great potential for practical applications, gaining a notable interest in the recent years. The Clique Percolation Method (CPM) is one of the earliest overlapping community finding methods, which was already used in the analysis of several different social networks. In this approach the communities correspond to k-clique percolation clusters, and the general heuristic for setting the parameters of the method is to tune the system just below the critical point of k-clique percolation. However, this rule is based on simple physical principles and its validity was never subject to quantitative ...
Novel picture of the soft modes at the QCD critical point based on the FRG method
Yokota, Takeru; Morita, Kenji
2016-01-01
We investigate the soft mode at the QCD critical point (CP) on the basis of the functional renormalization group. We calculate the spectral functions in the meson channels in the two-flavor quark--meson model. Our result shows that the energy of the peak position of the particle--hole mode in the sigma channel becomes vanishingly small as the system approaches the QCD CP, which is a manifestation of the softening of the phonon mode. We also extract the dispersion curves of the mesonic and the phonon mode, a hydrodynamic mode which leads to a finding that the dispersion curve of the sigma-mesonic mode crosses the light-cone into the space-like momentum region, and then eventually merges into the phonon mode as the system approaches further close to the CP. This may suggest that the sigma-mesonic mode forms the soft mode together with the hydrodynamic mode at the CP.
Thermo-mechanic-electrical coupling in phospholipid monolayers near the critical point
Steppich, D; Frommelt, T; Appelt, W; Wixforth, A; Schneider, M F
2010-01-01
Lipid monolayers have been shown to represent a powerful tool in studying mechanical and thermodynamic properties of lipid membranes as well as their interaction with proteins. Using Einstein's theory of fluctuations we here demonstrate, that an experimentally derived linear relationship both between transition entropy S and area A as well as between transition entropy and charge q implies a linear relationships between compressibility \\kappa_T, heat capacity c_\\pi, thermal expansion coefficient \\alpha_T and electric capacity CT. We demonstrate that these couplings have strong predictive power as they allow calculating electrical and thermal properties from mechanical measurements. The precision of the prediction increases as the critical point TC is approached.
A three-stage Stirling pulse tube cryocooler operating below the critical point of helium-4
Qiu, L. M.; Cao, Q.; Zhi, X. Q.; Gan, Z. H.; Yu, Y. B.; Liu, Y.
2011-10-01
Precooled phase shifters can significantly enhance the phase shift effect and further improve the performance of pulse tube cryocoolers. A separate three-stage Stirling pulse tube cryocooler (SPTC) with a cold inertance tube was designed and fabricated. Helium-4 instead of the rare helium-3 was used as the working fluid. The cryocooler reached a bottom temperature of 4.97 K with a net cooling power of 25 mW at 6.0 K. The operating frequency was 29.9 Hz and the charging pressure was 0.91 MPa. It is the first time a refrigeration temperature below the critical point of helium-4 was obtained in a three-stage Stirling pulse tube cryocooler.
Thermodynamic and real-space structural evidence of a 2D critical point in phospholipid monolayers
DEFF Research Database (Denmark)
Nielsen, Lars K.; Bjørnholm, Thomas; Mouritsen, Ole G.
2007-01-01
The two-dimensional phase diagram of phospholipid monolayers at air-water interfaces has been constructed from Langmuir compression isotherms. The coexistence region between the solid and fluid phases of the monolayer ends at the critical temperature of the transition. The small-scale lateral...... structure of the monolayers has been imaged by atomic force microscopy in the nm to mu m range at distinct points in the phase diagram. The lateral structure is immobilized by transferring the monolayer from an air-water interface to a solid mica support using Langmuir-Blodgett techniques. A transfer...... a critical point. The critical behavior inferred from the thermodynamic as well as the structural data is found to be consistent with the 2D Ising universality class. Additional results are presented demonstrating the presence of striped phases and coexisting domains in binary mixtures....
Picture change error in quasirelativistic electron/spin density, Laplacian and bond critical points
Bučinský, Lukáš
2014-06-01
The change of picture of the quasirelativistic Hartree-Fock wave functions is considered for electron/spin densities, the negative Laplacian of electron density and the appropriate bond critical point characteristics from the Quantum Theory of Atoms In Molecules (QTAIM). [OsCl5(Hpz)]- and [RuCl5(NO)]2- transition metal complexes are considered. Both, scalar relativistic and spin-orbit effects have been accounted for using the Infinite Order Two Component (IOTC) Hamiltonian. Picture change error (PCE) correction in the electron and spin densities and the Laplacian of electron density are treated analytically. Generally, PCE is found significant only in the core region of the atoms for the electron/spin density as well as Laplacian.©2014 Elsevier B.V. All rights reserved.
Properties of high-temperature phase diagram and critical point parameters in silica
Iosilevskiy, Igor; Solov'ev, Alexander
2013-01-01
Some uncertainties are discussed on the high-temperature phase boundaries and critical point parameters for gas-liquid phase transition in silica (SiO2). The thermal and caloric phase diagrams are compared and examined as being predicted by various theoretical approaches, such as the quasi-chemical representation, the wide-range semi-empirical equation of state and the ionic model under direct molecular dynamic simulation. The theoretical predictions are confronted with handbook recommendations and scanty experimental data on the equilibrium vapor composition over SiO2 boiling. Validity of conventional semi-empirical rules is tested for the theoretically predicted SiO2-phase diagrams. The non-congruence of gas-liquid phase transition in SiO2 is considered for this matter to be used as a modeling body to study the non-congruent evaporation in uranium dioxide and other uranium-bearing fuels at both existing and perspective nuclear reactors.
Pezzini, S.; Cobaleda, C.; Piot, B. A.; Bellani, V.; Diez, E.
2014-09-01
We report on magnetotransport measurements up to 30 T performed on a bilayer graphene Hall bar, enclosed by two thin hexagonal boron nitride flakes. In the quantum Hall regime, our high-mobility sample exhibits an insulating state at the neutrality point which evolves into a metallic phase when a strong in-plane field is applied, as expected for a transition from a canted antiferromagnetic to a ferromagnetic spin-ordered phase. We individuate a temperature-independent crossing in the four-terminal resistance as a function of the total magnetic field, corresponding to the critical point of the transition. We show that the critical field scales linearly with the perpendicular component of the field, as expected from the underlying competition between the Zeeman energy and interaction-induced anisotropies. A clear scaling of the resistance is also found and a universal behavior is proposed in the vicinity of the transition.
Critical point in the superconducting phase diagram of UPt/sub 3/
Energy Technology Data Exchange (ETDEWEB)
Hasselbach, K.; Taillefer, L.; Flouquet, J.
1989-07-03
We report on detailed measurements of the specific heat of UPt/sub 3/, performed on a high-quality single crystal in a magnetic field perpendicular to the /ital c/ axis, at temperatures down to 100 mK. Two distinct phase transitions at zero field are seen to converge at a critical point, near /ital H/=5 kOe, which coincides with the sharp break in the /ital H//sub /ital c/2/ curve. Beyond that point, there is evidence for only one phase. Combining these thermodynamic results with ultrasonic attenuation and /ital H//sub /ital c/2/ data, an /ital H/-/ital T/ diagram is constructed which consists of a ''polycritical'' point and several superconducting phases.
Universal Organization of Resting Brain Activity at the Thermodynamic Critical Point
Yu, Shan; Shriki, Oren; Plenz, Dietmar
2013-01-01
Thermodynamic criticality describes emergent phenomena in a wide variety of complex systems. In the mammalian brain, the complex dynamics that spontaneously emerge from neuronal interactions have been characterized as neuronal avalanches, a form of critical branching dynamics. Here, we show that neuronal avalanches also reflect that the brain dynamics are organized close to a thermodynamic critical point. We recorded spontaneous cortical activity in monkeys and humans at rest using high-density intracranial microelectrode arrays and magnetoencephalography, respectively. By numerically changing a control parameter equivalent to thermodynamic temperature, we observed typical critical behavior in cortical activities near the actual physiological condition, including the phase transition of an order parameter, as well as the divergence of susceptibility and specific heat. Finite-size scaling of these quantities allowed us to derive robust critical exponents highly consistent across monkey and humans that uncover ...
Vapor-like liquid coexistence densities affect the extension of the critical point's influence zone
Rivera, Jose Luis; Guerra-Gonzalez, Roberto
2015-01-01
The critical point affects the coexistence behavior of the vapor-liquid equilibrium densities. The length of the critical influence zone is under debate because for some properties, like shear viscosity, the extension is only a few degrees, while for others, such as the density order parameter, the critical influence zone range covers up to hundreds of degrees below the critical temperature. Here we show that for a simple molecular potential of ethane, the critical influence zone covers a wide zone of tens of degrees (below the critical temperature) down to a transition temperature, at which the apparent critical influence zone vanishes and the transition temperature can be predicted through a pressure analysis of the coexisting bulk liquid phase. The liquid phases within the apparent critical influence zone show low densities, making them behave internally like their corresponding vapor phases. Therefore, the experimentally observed wide extension of the critical influence zone is due to a vapor-like effect ...
Second virial coefficient at the critical point in a fluid of colloidal spheres plus depletants.
Tuinier, Remco; Feenstra, Maartje S
2014-11-11
Vliegenthart-Lekkerkerker (VL) criterion B2 = -6vc for second virial coefficient B2 at the critical (colloidal) gas-liquid point is considered for a mixture of spheres with volume vc plus depletants. For the onset of fluid-phase instability, the VL criterion holds for a wide range of shapes of direct attractive forces between hard-core spheres (Vliegenthart, G. A.; Lekkerkerker, H. N. W. J. Chem. Phys. 2000, 112, 5364). In the case of long-ranged attractions imposed indirectly via depletants, it is found that the VL relation fails. Instead, B2/vc at the critical point depends strongly on the sphere/depletant size ratio. By making the hard spheres sticky, we find that B2 moves gradually toward the VL criterion upon increasing the stickiness.
Superconductivity near a Quantum-Critical Point: The Special Role of the First Matsubara Frequency.
Wang, Yuxuan; Abanov, Artem; Altshuler, Boris L; Yuzbashyan, Emil A; Chubukov, Andrey V
2016-10-07
Near a quantum-critical point in a metal strong fermion-fermion interaction mediated by a soft collective boson gives rise to incoherent, non-Fermi liquid behavior. It also often gives rise to superconductivity which masks the non-Fermi liquid behavior. We analyze the interplay between the tendency to pairing and fermionic incoherence for a set of quantum-critical models with effective dynamical interaction between low-energy fermions. We argue that superconducting T_{c} is nonzero even for strong incoherence and/or weak interaction due to the fact that the self-energy from dynamic critical fluctuations vanishes for the two lowest fermionic Matsubara frequencies ω_{m}=±πT. We obtain the analytic formula for T_{c}, which reproduces well earlier numerical results for the electron-phonon model at vanishing Debye frequency.
Measurement of Critical Adsorption of Nitrogen near Its Liquid-vapor Critical Point
Chan, Moses
2003-01-01
The density profile of a critical fluid near a solid surface is expected to show an universal shape. This is known as critical adsorption. The measurement of this effect, especially close to the critical point, is often obscured by gravity. We were able to separate the gravitational effect from critical adsorption by using two capacitors, one with a large gap and one with a small gap of approximately 2 m. Within the uncertainty in the measurement, our data, which ranges between 10(exp -3) to 2 x 10(exp -6) in reduced temperatures, is consistent with the predicted power law dependence. This work is carried out in collaboration with Rafael Garcia, Sarah Scheidemantel and Klaus Knorr. It is funded by NASA's office of Biological and Physical Researchunder.
Emergence of a Fermionic Finite-Temperature Critical Point in a Kondo Lattice.
Chou, Po-Hao; Zhai, Liang-Jun; Chung, Chung-Hou; Mou, Chung-Yu; Lee, Ting-Kuo
2016-04-29
The underlying Dirac point is central to the profound physics manifested in a wide class of materials. However, it is often difficult to drive a system with Dirac points across the massless fermionic critical point. Here by exploiting screening of local moments under spin-orbit interactions in a Kondo lattice, we show that below the Kondo temperature, the Kondo lattice undergoes a topological transition from a strong topological insulator to a weak topological insulator at a finite temperature T_{D}. At T_{D}, massless Dirac points emerge and the Kondo lattice becomes a Dirac semimetal. Our analysis indicates that the emergent relativistic symmetry dictates nontrivial thermal responses over large parameter and temperature regimes. In particular, it yields critical scaling behaviors both in magnetic and transport responses near T_{D}.
Critical Point Facility (CPE) Group in the Spacelab Payload Operations Control Center (SL POCC)
1992-01-01
The primary payload for Space Shuttle Mission STS-42, launched January 22, 1992, was the International Microgravity Laboratory-1 (IML-1), a pressurized manned Spacelab module. The goal of IML-1 was to explore in depth the complex effects of weightlessness of living organisms and materials processing. Around-the-clock research was performed on the human nervous system's adaptation to low gravity and effects of microgravity on other life forms such as shrimp eggs, lentil seedlings, fruit fly eggs, and bacteria. Materials processing experiments were also conducted, including crystal growth from a variety of substances such as enzymes, mercury iodide, and a virus. The Huntsville Operations Support Center (HOSC) Spacelab Payload Operations Control Center (SL POCC) at the Marshall Space Flight Center (MSFC) was the air/ground communication channel used between the astronauts and ground control teams during the Spacelab missions. Featured is the Critical Point Facility (CPE) group in the SL POCC during STS-42, IML-1 mission.
Zhang, Chendong; Chen, Yuxuan; Johnson, Amber; Li, Ming-Yang; Li, Lain-Jong; Mende, Patrick C; Feenstra, Randall M; Shih, Chih-Kang
2015-10-14
By using a comprehensive form of scanning tunneling spectroscopy, we have revealed detailed quasi-particle electronic structures in transition metal dichalcogenides, including the quasi-particle gaps, critical point energy locations, and their origins in the Brillouin zones. We show that single layer WSe2 surprisingly has an indirect quasi-particle gap with the conduction band minimum located at the Q-point (instead of K), albeit the two states are nearly degenerate. We have further observed rich quasi-particle electronic structures of transition metal dichalcogenides as a function of atomic structures and spin-orbit couplings. Such a local probe for detailed electronic structures in conduction and valence bands will be ideal to investigate how electronic structures of transition metal dichalcogenides are influenced by variations of local environment.
Institute of Scientific and Technical Information of China (English)
Muktish Acharyya; Ajanta Bhowal Acharyya
2011-01-01
We solve the equilibrium meanfield equation of state of Ising ferromagnet (obtained from Bragg-Williams theory) by Newton-Raphson method.The number of iterations required to get a convergent solution (within a specified accuracy) of equilibrium magnetisation, at any particular temperature, is observed to diverge in a power law fashion as the temperature approaches the critical value.This is identified as the critical slowing down.The exponent is also estimated.This value of the exponent is compared with that obtained from analytic solution.Besides this, the numerical results are also compared with some experimental results exhibiting satisfactory degree of agreement.It is observed from this study that the information of the invariance of time scale at the critical point is present in the meanfield equilibrium equation of state of Ising ferromagnet.
Critical points in the 16-moment approximation. [plasma flow in laboratory and space plasmas study
Yasseen, F.; Retterer, J. M.
1991-01-01
The singular points in steady state, field-aligned plasma transport models based on velocity moment theory are examined. In particular, two separate singular points in the equations obtained from the 16-moment approximation are identified. These equations are presented in a form that makes the singularities apparent, and they are solved in a simple illustrative case. The singular points, one occurring at the sonic point and the other at a critical value of the parallel heat flux, give rise to different outflow regimes, characterized generically by different asymptotic behavior. The existence of the different outflow regimes separated by the heat flux critical point has been only hinted at in previous discussions of numerical simulation of the polar wind.
Magnetic and superconducting quantum critical points of heavy-fermion systems
Energy Technology Data Exchange (ETDEWEB)
Demuer, A.; Sheikin, I.; Braithwaite, D. E-mail: dbraithwaite@cea.fr; Faak, B.; Huxley, A.; Raymond, S.; Flouquet, J
2001-05-01
Two examples of heavy-fermion systems are presented : CePd{sub 2}Si{sub 2}, an antiferromagnet with a quantum critical point at P{sub C}=28 kbar and UGe{sub 2} an itinerant ferromagnet which transits in a paramagnetic phase above P{sub C}=16 kbar. In CePd{sub 2}Si{sub 2} the superconductivity domain is centered on P{sub C}. Special attention was given to the superconducting and magnetic anomalies at their superconducting and Neel temperatures. In UGe{sub 2} superconductivity appears in 9 kbar at a temperature T{sub S}, more than two orders of magnitude lower than the Curie temperature; furthermore, it occurs only on the magnetic border (P
Magnetic and superconducting quantum critical points of heavy-fermion systems
Demuer, A.; Sheikin, I.; Braithwaite, D.; Fåk, B.; Huxley, A.; Raymond, S.; Flouquet, J.
2001-05-01
Two examples of heavy-fermion systems are presented : CePd 2Si 2, an antiferromagnet with a quantum critical point at PC=28 kbar and UGe 2 an itinerant ferromagnet which transits in a paramagnetic phase above PC=16 kbar. In CePd 2Si 2 the superconductivity domain is centered on PC. Special attention was given to the superconducting and magnetic anomalies at their superconducting and Néel temperatures. In UGe 2 superconductivity appears in 9 kbar at a temperature TS, more than two orders of magnitude lower than the Curie temperature; furthermore, it occurs only on the magnetic border ( P< PC). Another characteristic temperature TX is detected by resistivity; the zigzag uranium chain of the lattice may favor a supplementary nesting in the majority spin band.
Mapping the current–current correlation function near a quantum critical point
Energy Technology Data Exchange (ETDEWEB)
Prodan, Emil, E-mail: prodan@yu.edu [Department of Physics, Yeshiva University, New York, NY 10016 (United States); Bellissard, Jean [School of Mathematics and School of Physics, Georgia Institute of Technology, Atlanta, GA (United States)
2016-05-15
The current–current correlation function is a useful concept in the theory of electron transport in homogeneous solids. The finite-temperature conductivity tensor as well as Anderson’s localization length can be computed entirely from this correlation function. Based on the critical behavior of these two physical quantities near the plateau–insulator or plateau–plateau transitions in the integer quantum Hall effect, we derive an asymptotic formula for the current–current correlation function, which enables us to make several theoretical predictions about its generic behavior. For the disordered Hofstadter model, we employ numerical simulations to map the current–current correlation function, obtain its asymptotic form near a critical point and confirm the theoretical predictions.
[Economic aspects of the Italian food industry: critical points and perspectives].
Casati, D
2012-01-01
The Italian food industry represents 2% of GDP and employment. Its role grows considering the whole food supply chain to 3.7% of GDP and 5.7% of employment, reaching 12.5% of the European one. In terms of value added, it reaches 25% of private sector expenditure, at the second places after the house one, but 8 times more than health. The european food industry is the leading sector. Italian industry is at the 3rd place for its value added, at 5th for employment, but the first for productivity together with the French food industry. Critical points of Italian food industry are mainly connected with its structure, production composition, dependence on consumer evolution, crisis impact, internationalization of firms and leading groups, innovation.
Dielectric constant of /sup 3/He near the liquid-vapor critical point
Energy Technology Data Exchange (ETDEWEB)
Doiron, T.; Meyer, H.
1978-03-01
High-resolution measurements of the static dielectic constant epsilon along the critical isochore are reported for /sup 3/He in the region of the critical point. The experiments were conducted at a frequency of 1000 Hz and the purpose was to observe a divergence of (partialepsilon/partialT)/sub rhoc/ as T/sub c/ is approached from above. No evidence for a critical anomaly was found, the estimated upper bound for its integrated value being deltaepsilon approx. 4 x 10/sup -8/ which is consistent with the theoretical estimations. Hence the recently reported is not observed in /sup 3/He. In the Appendix, some experimental questions arising in such constant-density experiments are discussed.
Shear viscosity at the Ising-nematic quantum critical point in two dimensional metals
Patel, Aavishkar A; Sachdev, Subir
2016-01-01
In a strongly interacting quantum liquid without quasiparticles, general scaling arguments imply that the dimensionless ratio $(k_B /\\hbar)\\, \\eta/s$, where $\\eta$ is the shear viscosity and $s$ is the entropy density, is a universal number. We compute the shear viscosity of the Ising-nematic critical point of metals in spatial dimension $d=2$ by an expansion below $d=5/2$. The anisotropy associated with directions parallel and normal to the Fermi surface leads to a violation of the scaling expectations: $\\eta$ scales in the same manner as a chiral conductivity, and the ratio $\\eta/s$ diverges as $T^{-2/z}$, where $z$ is the dynamic critical exponent for fermionic excitations dispersing normal to the Fermi surface.
Mukherjee, Swagato; Yin, Yi
2015-01-01
We report on recent progress in the study of the evolution of non-Gaussian cumulants of critical fluctuations. We explore the implications of non-equilibrium effects on the search for the QCD critical point.
Event-by-event fluctuations in heavy ion collisions and the QCD critical point
Stephanov, M.; Rajagopal, K.; Shuryak, E.
1999-12-01
The event-by-event fluctuations of suitably chosen observables in heavy ion collisions at CERN SPS, BNL RHIC, and CERN LHC can tell us about the thermodynamic properties of the hadronic system at freeze-out. By studying these fluctuations as a function of varying control parameters, it is possible to learn much about the phase diagram of QCD. As a timely example, we stress the methods by which present experiments at the CERN SPS can locate the second-order critical end point of the first-order transition between quark-gluon plasma and hadron matter. Those event-by-event signatures which are characteristic of freeze-out in the vicinity of the critical point will exhibit nonmonotonic dependence on control parameters. We focus on observables constructed from the multiplicity and transverse momenta of charged pions. We first consider how the event-by-event fluctuations of such observables are affected by Bose-Einstein correlations, by resonances which decay after freeze-out, and by fluctuations in the transverse flow velocity. We compare our thermodynamic predictions for such noncritical event-by-event fluctuations with NA49 data, finding broad agreement. We then focus on effects due to thermal contact between the observed pions and a heat bath with a given (possibly singular) specific heat, due to the direct coupling between the critical fluctuations of the sigma field and the observed pions. We also discuss the effect of the pions produced in the decay of sigma particles just above threshold after freeze-out on the inclusive pion spectrum and on multiplicity fluctuations. We estimate the size of these nonmonotonic effects, which appear near the critical point, including restrictions imposed by finite size and finite time, and conclude that they should be easily observable.
Theory of First Order Chemical Kinetics at the Critical Point of Solution.
Baird, James Kern; Lang, Joshua R
2017-09-27
Liquid mixtures, which have a phase diagram exhibiting a miscibility gap ending in a critical point of solution, have been used as solvents for chemical reactions. The reaction rate in the forward direction has often been observed to slow down as a function of temperature in the critical region. Theories based upon the Gibbs free energy of reaction as the driving force for chemical change have been invoked to explain this behavior. With the assumption that the reaction is proceeding under relaxation conditions, these theories expand the free energy in a Taylor series about the position of equilibrium. Since the free energy is zero at equilibrium, the leading term in the Taylor series is proportional to the first derivative of the free energy with respect to the extent of reaction. To analyze the critical behavior of this derivative, the theories invoke the principle of critical point isomorphism, which is thought to govern all critical phenomena. They find that the derivative goes to zero in the critical region, which accounts for the slowing down observed in the reaction rate. As has been pointed out, however, most experimental rate investigations have been carried out under irreversible conditions as opposed to relaxation conditions [Shen et al. J. Phys. Chem. A 2015, 119, 8784 - 8791]. Below, we consider a reaction governed by first order kinetics and invoke transition state theory to take into account the irreversible conditions. We express the apparent activation energy in terms of thermodynamic derivatives evaluated under standard conditions as well as the pseudo-equilibrium conditions associated with the reactant and the activated complex. We show that these derivatives approach infinity in the critical region. The apparent activation energy follows this behavior, and its divergence accounts for the slowing down of the reaction rate.
Stationary and transient Soret separation in a binary mixture with a consolute critical point.
Ryzhkov, Ilya I; Kozlova, Sofia V
2016-12-01
The stationary and transient Soret separation in a binary mixture with a consolute critical point is studied theoretically. The mixture is placed between two parallel plates kept at different temperatures. A polymer blend is used as a model system. Analytical solutions are constructed to describe the stationary separation in a binary mixture with variable Soret coefficient. The latter strongly depends on temperature and concentration and enhances near a consolute critical point due to reduced diffusion. As a result, a large concentration gradient is observed locally, while much smaller concentration variations are found in the rest of the layer. It is shown that complete separation can be obtained by applying a small temperature difference first, waiting for the establishment of stationary state, and then increasing this difference again. In this case, the critical temperature lies between hot and cold wall temperatures, while the mixture still remains in the one-phase region. When the initial (mean) temperature or concentration are shifted away from the near-critical values, the separation decreases. The analysis of transient behavior shows that the Soret separation occurs much faster than diffusion to the homogeneous state when the initial concentration is close to the critical one. It happens due to the decrease (increase) of the local relaxation time during the Soret (Diffusion) steps. The transient times of these steps become comparable for small temperature differences or off-critical initial concentrations. An unusual (non-exponential) separation dynamics is observed when the separation starts in the off-critical domain, and then enhances greatly when the system enters into the near-critical region. It is also found that the transient time decreases with increasing the applied temperature difference.
Cholewa, Michał
2011-01-01
This paper presents a method of choosing number of states of a HMM based on number of critical points of the motion capture data. The choice of Hidden Markov Models(HMM) parameters is crucial for recognizer's performance as it is the first step of the training and cannot be corrected automatically within HMM. In this article we define predictor of number of states based on number of critical points of the sequence and test its effectiveness against sample data.
Energy Technology Data Exchange (ETDEWEB)
Schlottmann, P. [Department of Physics, Florida State University, MC 4350-309 Keene Building, Tallahassee, FL 32306 (United States)]. E-mail: schlottm@martech.fsu.edu
2004-12-31
The nesting of the Fermi surfaces of an electron pocket and a hole pocket separated by a wave vector Q and the interaction between electrons gives rise to spin- and charge-density waves. The order can gradually be suppressed by mismatching the nesting and a quantum critical point is obtained as the critical temperature tends to zero. We calculate the quasi-particle damping close to the quantum critical point and discuss its consequences on the resistivity and Hall effect.
Empirical Example of Nucleus with Transitional Dynamical Symmetry X(5)
Institute of Scientific and Technical Information of China (English)
张大立; 赵惠英
2002-01-01
By analysing the energy spectrum, E2 transition rates and branching ratios, it is shown explicitly that the nucleus 150Nd provides an empirical example with X(5) symmetry at the critical point of the transition from U(5) to SU(3) symmetry.
Uncovering the hidden quantum critical point in disordered massless Dirac and Weyl semimetals
Pixley, J. H.; Huse, David A.; Das Sarma, S.
2016-09-01
We study the properties of the avoided or hidden quantum critical point (AQCP) in three-dimensional Dirac and Weyl semimetals in the presence of short range potential disorder. By computing the averaged density of states (along with its second and fourth derivative at zero energy) with the kernel polynomial method (KPM) we systematically tune the effective length scale that eventually rounds out the transition and leads to an AQCP. We show how to determine the strength of the avoidance, establishing that it is not controlled by the long wavelength component of the disorder. Instead, the amount of avoidance can be adjusted via the tails of the probability distribution of the local random potentials. A binary distribution with no tails produces much less avoidance than a Gaussian distribution. We introduce a double Gaussian distribution to interpolate between these two limits. As a result we are able to make the length scale of the avoidance sufficiently large so that we can accurately study the properties of the underlying transition (that is eventually rounded out), unambiguously identify its location, and provide accurate estimates of the critical exponents ν =1.01 ±0.06 and z =1.50 ±0.04 . We also show that the KPM expansion order introduces an effective length scale that can also round out the transition in the scaling regime near the AQCP.
Liquid-liquid critical point in a simple analytical model of water
Urbic, Tomaz
2016-10-01
A statistical model for a simple three-dimensional Mercedes-Benz model of water was used to study phase diagrams. This model on a simple level describes the thermal and volumetric properties of waterlike molecules. A molecule is presented as a soft sphere with four directions in which hydrogen bonds can be formed. Two neighboring waters can interact through a van der Waals interaction or an orientation-dependent hydrogen-bonding interaction. For pure water, we explored properties such as molar volume, density, heat capacity, thermal expansion coefficient, and isothermal compressibility and found that the volumetric and thermal properties follow the same trends with temperature as in real water and are in good general agreement with Monte Carlo simulations. The model exhibits also two critical points for liquid-gas transition and transition between low-density and high-density fluid. Coexistence curves and a Widom line for the maximum and minimum in thermal expansion coefficient divides the phase space of the model into three parts: in one part we have gas region, in the second a high-density liquid, and the third region contains low-density liquid.
Universal Organization of Resting Brain Activity at the Thermodynamic Critical Point
Directory of Open Access Journals (Sweden)
Shan eYu
2013-08-01
Full Text Available Thermodynamic criticality describes emergent phenomena in a wide variety of complex systems. In the mammalian cortex, one type of complex dynamics that spontaneously emerges from neuronal interactions has been characterized as neuronal avalanches. Several aspects of neuronal avalanches such as their size and life time distributions are described by power laws with unique exponents, indicating an underlying critical branching process that governs avalanche formation. Here, we show that neuronal avalanches also reflect an organization of brain dynamics close to a thermodynamic critical point. We recorded spontaneous cortical activity in monkeys and humans at rest using high-density intracranial microelectrode arrays and magnetoencephalography, respectively. By numerically changing a control parameter equivalent to thermodynamic temperature, we observed typical critical behavior in cortical activities near the actual physiological condition, including the phase transition of an order parameter, as well as the divergence of susceptibility and specific heat. Finite-size scaling of these quantities allowed us to derive robust critical exponents highly consistent across monkey and humans that uncover a distinct, yet universal organization of brain dynamics. Our results demonstrate that normal brain dynamics at rest resides near or at criticality, which maximizes several aspects of information processing such as input sensitivity and dynamic range.
Nematic quantum critical point without magnetism in FeSe1-xSx superconductors
Hosoi, Suguru; Matsuura, Kohei; Ishida, Kousuke; Wang, Hao; Mizukami, Yuta; Watashige, Tatsuya; Kasahara, Shigeru; Matsuda, Yuji; Shibauchi, Takasada
2016-07-01
In most unconventional superconductors, the importance of antiferromagnetic fluctuations is widely acknowledged. In addition, cuprate and iron-pnictide high-temperature superconductors often exhibit unidirectional (nematic) electronic correlations, including stripe and orbital orders, whose fluctuations may also play a key role for electron pairing. In these materials, however, such nematic correlations are intertwined with antiferromagnetic or charge orders, preventing the identification of the essential role of nematic fluctuations. This calls for new materials having only nematicity without competing or coexisting orders. Here we report systematic elastoresistance measurements in FeSe1-xSx superconductors, which, unlike other iron-based families, exhibit an electronic nematic order without accompanying antiferromagnetic order. We find that the nematic transition temperature decreases with sulfur content x; whereas, the nematic fluctuations are strongly enhanced. Near ≈0.17, the nematic susceptibility diverges toward absolute zero, revealing a nematic quantum critical point. The obtained phase diagram for the nematic and superconducting states highlights FeSe1-xSx as a unique nonmagnetic system suitable for studying the impact of nematicity on superconductivity.
Directory of Open Access Journals (Sweden)
de B. Alves Leonardo S.
2013-01-01
Full Text Available The classical thermodynamic model for near critical heat transfer is an integral-differential equation with constant coefficients. It is similar to the heat equation, except for a source term containing the time derivative of the bulk temperature. Despite its simple form, analytical methods required the use of approximations to generate solutions for it, such as an approximate Fourier transformation or a numerical Laplace inversion. Recently, the Generalized Integral Transform Technique or GITT has been successfully applied to this problem, providing a highly accurate analytical solution for it and a new expression of its relaxation time. Nevertheless, very small temperature differences, on the order of mK, have to be imposed so that constant thermal properties can be assumed very close to the critical point. The present paper generalizes this study by relaxing its restriction and accounting for the strong dependence on temperature and pressure of supercritical fluid properties, demonstrating that a the GITT can be applied to realistic nonlinear unsteady compressible heat transfer in fluids with diverging thermal properties and b temperature and pressure have opposite effects on all properties, but their variation causes no additional thermo-acoustic effect, increasing the validity range of the constant property model.
Fluid adsorption up to the critical point. Experimental study of a wetting fluid/solid interface
Findenegg, G. H.; Löring, R.
1984-10-01
We have measured multilayer adsorption isotherms of propane on graphitized carbon black over a wide temperature range, corresponding to reduced temperatures T/Tc of the fluid from 0.7 to 1.004 and reduced densities ρ/ρc up to 1.4. Experimental isotherms of the surface excess concentration Γgs are analyzed in terms of the Frenkel-Halsey-Hill (FHH) model. The exponent n is somewhat less than 3 (2.55±0.30) and the amplitude parameter Δɛ/kT becomes nearly independent of temperature, up to T/Tc=0.98, when the simple one-step density profile of the original FHH model is replaced by a two-step profile, to account for the compression of the layer next to the solid substrate. Evidence for a compression of the liquid boundary layer comes from measurements of the surface excess concentration Γls at the liquid/substrate interface. Along the liquid-vapor coexistence curve, Γls0 diverges as T approaches Tc, in qualitative agreement with scaling law theory. The analogy of the present one-component fluid/solid-substrate interface near the critical point of the fluid, with a two-component liquid/vapor interface near the critical solution point of the liquid mixture is discussed.
Neural avalanches at the critical point between replay and non-replay of spatiotemporal patterns.
Directory of Open Access Journals (Sweden)
Silvia Scarpetta
Full Text Available We model spontaneous cortical activity with a network of coupled spiking units, in which multiple spatio-temporal patterns are stored as dynamical attractors. We introduce an order parameter, which measures the overlap (similarity between the activity of the network and the stored patterns. We find that, depending on the excitability of the network, different working regimes are possible. For high excitability, the dynamical attractors are stable, and a collective activity that replays one of the stored patterns emerges spontaneously, while for low excitability, no replay is induced. Between these two regimes, there is a critical region in which the dynamical attractors are unstable, and intermittent short replays are induced by noise. At the critical spiking threshold, the order parameter goes from zero to one, and its fluctuations are maximized, as expected for a phase transition (and as observed in recent experimental results in the brain. Notably, in this critical region, the avalanche size and duration distributions follow power laws. Critical exponents are consistent with a scaling relationship observed recently in neural avalanches measurements. In conclusion, our simple model suggests that avalanche power laws in cortical spontaneous activity may be the effect of a network at the critical point between the replay and non-replay of spatio-temporal patterns.
Kondo effect and quantum critical point in Mn(1-x)CoxSi
Teyssier, J.; Viennois, R.; Guritanu, V.; Giannini, E.; van der Marel, D.
2010-01-01
We report magnetic, transport and neutron diffraction studies of the solid solution Mn1-xCoxSi. For the Mn rich compounds, a sharp decrease of the Curie temperature is observed upon cobalt doping and neutron elastic scattering shows that the helimagnetic order of MnSi persists up to x = 0.06 with a shortening of the helix period. For higher Co concentrations (0.06 Weiss temperature changes sign and the system enters an antiferromagnetic state upon cooling (TN=9K for x = 0.50). In this doping range, the antiferromagnetic coupling leads to a Kondo effect marked by a minimum in the resistivity. This scenario is supported by the scaling of the magnetoresistance with a TK approx 6.5 K, close to the change in curvature of the resistivity and in agreement with the Weiss temperature from magnetic susceptibility. The sign change of the Weiss temperature and the transition from a helimagnetic to an antiferromagnetic ground state, with increasing the Co doping, point toward the existence of a quantum critical point at the composition Mn0.94Co0.06Si.
Universal organization of resting brain activity at the thermodynamic critical point.
Yu, Shan; Yang, Hongdian; Shriki, Oren; Plenz, Dietmar
2013-01-01
Thermodynamic criticality describes emergent phenomena in a wide variety of complex systems. In the mammalian cortex, one type of complex dynamics that spontaneously emerges from neuronal interactions has been characterized as neuronal avalanches. Several aspects of neuronal avalanches such as their size and life time distributions are described by power laws with unique exponents, indicating an underlying critical branching process that governs avalanche formation. Here, we show that neuronal avalanches also reflect an organization of brain dynamics close to a thermodynamic critical point. We recorded spontaneous cortical activity in monkeys and humans at rest using high-density intracranial microelectrode arrays and magnetoencephalography, respectively. By numerically changing a control parameter equivalent to thermodynamic temperature, we observed typical critical behavior in cortical activities near the actual physiological condition, including the phase transition of an order parameter, as well as the divergence of susceptibility and specific heat. Finite-size scaling of these quantities allowed us to derive robust critical exponents highly consistent across monkey and humans that uncover a distinct, yet universal organization of brain dynamics. Our results demonstrate that normal brain dynamics at rest resides near or at criticality, which maximizes several aspects of information processing such as input sensitivity and dynamic range.
Nematic quantum critical point without magnetism in FeSe1-xSx superconductors.
Hosoi, Suguru; Matsuura, Kohei; Ishida, Kousuke; Wang, Hao; Mizukami, Yuta; Watashige, Tatsuya; Kasahara, Shigeru; Matsuda, Yuji; Shibauchi, Takasada
2016-07-19
In most unconventional superconductors, the importance of antiferromagnetic fluctuations is widely acknowledged. In addition, cuprate and iron-pnictide high-temperature superconductors often exhibit unidirectional (nematic) electronic correlations, including stripe and orbital orders, whose fluctuations may also play a key role for electron pairing. In these materials, however, such nematic correlations are intertwined with antiferromagnetic or charge orders, preventing the identification of the essential role of nematic fluctuations. This calls for new materials having only nematicity without competing or coexisting orders. Here we report systematic elastoresistance measurements in FeSe1-xSx superconductors, which, unlike other iron-based families, exhibit an electronic nematic order without accompanying antiferromagnetic order. We find that the nematic transition temperature decreases with sulfur content x; whereas, the nematic fluctuations are strongly enhanced. Near [Formula: see text], the nematic susceptibility diverges toward absolute zero, revealing a nematic quantum critical point. The obtained phase diagram for the nematic and superconducting states highlights FeSe1-xSx as a unique nonmagnetic system suitable for studying the impact of nematicity on superconductivity.
Susceptibility Measurements Near the He-3 Liquid-Gas Critical Point
Barmatz, Martin; Zhong, Fang; Hahn, Inseob
2000-01-01
An experiment is now being developed to measure both the linear susceptibility and specific heat at constant volume near the liquid-gas critical point of He-3 in a microgravity environment. An electrostriction technique for measuring susceptibility will be described. Initial electrostriction measurements were performed on the ground along the critical isochore in a 0.5 mm high measurement cell filled to within 0.1 % of the critical density. These measurements agreed with the susceptibility determined from pressure-density measurements along isotherms. The critical temperature, T(sub c), determined separately from specific heat and susceptibility measurements was self-consistent. Susceptibility measurements in the range t = T/T(sub c) - 1 > 10(exp -4)were fit to Chi(sup *)(sub T) = Gamma(sup +)t(exp -lambda)(1 + Gamma(sup +)(sub 1)t(sup delta). Best fit parameters for the asymptotic amplitude Gamma(sup +) and the first Wegner amplitude Gamma(sup +)(sub 1) will be presented and compared to previous measurements.
Neural avalanches at the critical point between replay and non-replay of spatiotemporal patterns.
Scarpetta, Silvia; de Candia, Antonio
2013-01-01
We model spontaneous cortical activity with a network of coupled spiking units, in which multiple spatio-temporal patterns are stored as dynamical attractors. We introduce an order parameter, which measures the overlap (similarity) between the activity of the network and the stored patterns. We find that, depending on the excitability of the network, different working regimes are possible. For high excitability, the dynamical attractors are stable, and a collective activity that replays one of the stored patterns emerges spontaneously, while for low excitability, no replay is induced. Between these two regimes, there is a critical region in which the dynamical attractors are unstable, and intermittent short replays are induced by noise. At the critical spiking threshold, the order parameter goes from zero to one, and its fluctuations are maximized, as expected for a phase transition (and as observed in recent experimental results in the brain). Notably, in this critical region, the avalanche size and duration distributions follow power laws. Critical exponents are consistent with a scaling relationship observed recently in neural avalanches measurements. In conclusion, our simple model suggests that avalanche power laws in cortical spontaneous activity may be the effect of a network at the critical point between the replay and non-replay of spatio-temporal patterns.
New quantum-critical-point-related effects in Ce lattice systems
Energy Technology Data Exchange (ETDEWEB)
Sereni, J.G. [Division Bajas Temperaturas, Centro Atomico Bariloche (CNEA), 8400 S.C. de Bariloche (Argentina)]. E-mail: jsereni@cab.cnea.gov.ar
2004-12-31
Anomalous physical properties related to quantum critical points are investigated in Ce-systems whose magnetic phase boundaries, TN,C(x,p), can be traced for at least one decade of temperature. A change from the usual negative curvature to a linear concentration, x, dependence of TN,C(x) is observed at x*>=xcr/2 (xcr being the critical concentration). Within the x*xxcr region, the usual specific heat temperature dependence Cm/T{proportional_to}Ln(1/T) develops above TN,C, while a nearly constant value of Cm/T maximum is observed besides a scaling of Cm/T(T) with {delta}T=T-TN,C. Coincidentally, a significant increase of the zero-point entropy S0(x)(=RLn2-Sm(x,T)) occurs. Dimensionality and dynamics of the spin fluctuations can be analyzed computing the internal energy and entropy for T>=TN and AC-susceptibility results. Consequences for the free-energy evolution within this region and implications of the S0(x) increase are discussed.
Frame rate up-conversion using multiresolution critical point filters with occlusion refinement
Institute of Scientific and Technical Information of China (English)
Yi-xiong ZHANG; Wei-dong WANG; Peng LIU; Qing-dong YAO
2008-01-01
In this paper,multiresolution critical-point filters (CPFs) are employed to image matching for frame rate up-conversion (FRUC). By CPF matching,the dense motion field can be obtained for representing object motions accurately. However,the elastic motion model does not hold in the areas of occlusion,thus resulting in blur artifacts in the interpolated frame. To tackle this problem,we propose a new FRUC scheme using an occlusion refined CPF matching interpolation (ORCMI). In the proposed approach,the occlusion refinement is based on a bidirectional CPF mapping. And the intermediate frames are generated by the bidirectional interpolation for non-occlusion pixels combined with unidirectional projection for the occlusion pixeis. Ex-perimental results show that ORCMI improves the visual quality of the interpolated frames,especially at the occlusion regions. Compared to the block matching based FRUC algorithm,ORCMI can achieve 1～2 dB PSNR gain for standard video sequences.
Quantum critical point for stripe order: An organizing principle of cuprate superconductivity
Energy Technology Data Exchange (ETDEWEB)
Doiron-Leyraud, Nicolas [Departement de Physique and RQMP, Universite de Sherbrooke, Sherbrooke, Canada Canadian Institute for Advanced Research, Toronto (Canada); Taillefer, Louis, E-mail: Louis.Taillefer@USherbrooke.ca [Departement de Physique and RQMP, Universite de Sherbrooke, Sherbrooke, Canada Canadian Institute for Advanced Research, Toronto (Canada)
2012-11-01
A spin density-wave quantum critical point (QCP) is the central organizing principle of organic, iron-pnictide, heavy-fermion and electron-doped cuprate superconductors. It accounts for the superconducting T{sub c} dome, the non-Fermi-liquid resistivity, and the Fermi-surface reconstruction. Outside the magnetically ordered phase above the QCP, scattering and pairing decrease in parallel as the system moves away from the QCP. Here we argue that a similar scenario, based on a stripe-order QCP, is a central organizing principle of hole-doped cuprate superconductors. Key properties of La{sub 1.8-x}Eu{sub 0.2}Sr{sub x}CuO{sub 4}, La{sub 1.6-x}Nd{sub 0.4}Sr{sub x}CuO{sub 4} and YBa{sub 2}Cu{sub 3}O{sub y} are naturally unified, including stripe order itself, its QCP, Fermi-surface reconstruction, the linear-T resistivity, and the nematic character of the pseudogap phase.
Is U3Ni3Sn4 best described as near a quantum critical point?
Energy Technology Data Exchange (ETDEWEB)
Booth, C.H.; Shlyk, L.; Nenkov, K.; Huber, J.G.; De Long, L.E.
2003-04-08
Although most known non-Fermi liquid (NFL) materials are structurally or chemically disordered, the role of this disorder remains unclear. In particular, very few systems have been discovered that may be stoichiometric and well ordered. To test whether U{sub 3}Ni{sub 3}Sn{sub 4} belongs in this latter class, we present measurements of the x-ray absorption fine structure (XAFS) of polycrystalline and single-crystal U{sub 3}Ni{sub 3}Sn{sub 4} samples that are consistent with no measurable local atomic disorder. We also present temperature-dependent specific heat data in applied magnetic fields as high as 8 T that show features that are inconsistent with the antiferromagnetic Griffiths' phase model, but do support the conclusion that a Fermi liquid/NFL crossover temperature increases with applied field. These results are inconsistent with theoretical explanations that require strong disorder effects, but do support the view that U{sub 3}Ni{sub 3}Sn{sub 4} is a stoichoiometric, ordered material that exhibits NFL behavior, and is best described as being near an antiferromagnetic quantum critical point.
Critical point scaling of Ising spin glasses in a magnetic field
Yeo, Joonhyun; Moore, M. A.
2015-03-01
Critical point scaling in a field H applies for the limits t →0 (where t =T /Tc-1 ) and H →0 but with the ratio R =t /H2 /Δ finite. Δ is a critical exponent of the zero-field transition. We study the replicon correlation length ξ and from it the crossover scaling function f (R ) defined via 1 /(ξ H4 /(d +2 -η )) ˜f (R ) . We have calculated analytically f (R ) for the mean-field limit of the Sherrington-Kirkpatrick model. In dimension d =3 , we have determined the exponents and the critical scaling function f (R ) within two versions of the Migdal-Kadanoff (MK) renormalization group procedure. One of the MK versions gives results for f (R ) in d =3 in reasonable agreement with those of the Monte Carlo simulations at the values of R for which they can be compared. If there were a de Almeida-Thouless (AT) line for d ≤6 , it would appear as a zero of the function f (R ) at some negative value of R , but there is no evidence for such behavior. This is consistent with the arguments that there should be no AT line for d ≤6 , which we review.
Discrete self-similiarity and critical point behavior in fluctuations about extremal black holes
Traschen, J
1994-01-01
The issues of scaling symmetry and critical point behavior are studied for fluctuations about extremal charged black holes. We consider the scattering and capture of the spherically symmetric mode of a charged, massive test field on the background spacetime of a black hole with charge Q and mass M. The spacetime geometry near the horizon of a |Q|=M black hole has a scaling symmetry, which is absent if |Q|
Discrete self-similarity and critical point behavior in fluctuations about extremal black holes
Traschen, Jennie
1994-12-01
The issues of scaling symmetry and critical point behavior are studied for fluctuations about extremal charged black holes. We consider the scattering and capture of the spherically symmetric mode of a charged, massive test field on the background spacetime of a black hole with charge Q and mass M. The spacetime geometry near the horizon of a ||Q||=M black hole has a scaling symmetry, which is absent if ||Q||scale being introduced by the surface gravity. We show that this symmetry leads to the existence of a self-similar solution for the charged field near the horizon, and further, that there is a one parameter family of discretely self-similar solutions. The scaling symmetry, or lack thereof, also shows up in correlation length scales, defined in terms of the rate at which the influence of an external source coupled to the field dies off. It is shown by constructing the Green's functions that an external source has a long range influence on the extremal background, compared to a correlation length scale which falls off exponentially fast in the ||Q||0 in the background spacetime, infinitesimal changes in the black hole area vary like Δ1/2.
NMSSM Inflation and Domain Walls from a Tri-critical Point of View
Aval, Hadi Gholian
2016-01-01
In this paper we want to study the conditions in which we could bring a universe filled with different $Z_3$ vacua created during the Next to Minimal Supersymmetric Standard Model (NMSSM) electroweak symmetry breaking at $\\textit{O} (10)^2$ GeV and a three dimensional three states diluted Potts model together in the same universality class. Then we use Cardy-Jacobsen conjecture to prove that there might be a tri-critical point in the NMSSM electroweak epoch of early universe. We prove that due to the existence of this point there would be no cosmological domain wall problem. Moreover, at this point the heat capacity and correlation length diverge which lead to a huge amount of energy release at constant temperature and a new mechanism for cosmological structure formation. Also, the entropy decrease after the tri-critical phase transition could explain the problem of low initial entropy in early universe. Finally, we combine Cardy-Jacobsen and Yaffe-Svetitsky conjectures to show that there might be a tri-criti...
The break-up of heavy electrons at a quantum critical point.
Custers, J; Gegenwart, P; Wilhelm, H; Neumaier, K; Tokiwa, Y; Trovarelli, O; Geibel, C; Steglich, F; Pépin, C; Coleman, P
2003-07-31
The point at absolute zero where matter becomes unstable to new forms of order is called a quantum critical point (QCP). The quantum fluctuations between order and disorder that develop at this point induce profound transformations in the finite temperature electronic properties of the material. Magnetic fields are ideal for tuning a material as close as possible to a QCP, where the most intense effects of criticality can be studied. A previous study on the heavy-electron material YbRh2Si2 found that near a field-induced QCP electrons move ever more slowly and scatter off one another with ever increasing probability, as indicated by a divergence to infinity of the electron effective mass and scattering cross-section. But these studies could not shed light on whether these properties were an artefact of the applied field, or a more general feature of field-free QCPs. Here we report that, when germanium-doped YbRh2Si2 is tuned away from a chemically induced QCP by magnetic fields, there is a universal behaviour in the temperature dependence of the specific heat and resistivity: the characteristic kinetic energy of electrons is directly proportional to the strength of the applied field. We infer that all ballistic motion of electrons vanishes at a QCP, forming a new class of conductor in which individual electrons decay into collective current-carrying motions of the electron fluid.
Cai, Ang; Pixley, Jedediah; Si, Qimiao
Heavy fermion metals represent a canonical system to study superconductivity driven by quantum criticality. We are particularly motivated by the properties of CeRhIn5, which shows the characteristic features of a Kondo destruction quantum critical point (QCP) in its normal state, and has one of the highest Tc's among the heavy fermion superconductors. As a first step to study this problem within a cluster-EDMFT approach, we analyze a four-site Anderson impurity model with the antiferromagnetic spin component of the cluster coupled to a sub-Ohmic bosonic bath. We find a QCP that belongs to the same universality class as the single-site Bose-Fermi Anderson model. Together with previous work on a two-site model, our result suggests that the Kondo destruction QCP is robust as cluster size increases. More importantly, we are able to calculate the d-wave pairing susceptibility, which we find to be enhanced near the QCP. Using this model as the effective cluster model of the periodic Anderson model, we are also able to study the superconducting pairing near the Kondo-destruction QCP of the lattice model; preliminary results will be presented.
Jin, Xiao-Yong; Kuramashi, Yoshinobu; Nakamura, Yoshifumi; Takeda, Shinji; Ukawa, Akira
2017-08-01
We study the finite temperature phase structure for three-flavor QCD with a focus on locating the critical point, which separates the crossover and the first order phase transition region in the chiral regime of the Columbia plot. In this study, we employ the Iwasaki gauge action and the nonperturvatively O (a ) improved Wilson-Clover fermion action. We discuss the finite size scaling analysis, including the mixing of magnetizationlike and energylike observables. We carry out the continuum extrapolation of the critical point using newly generated data at the Nt=8 , 10 and estimate the upper bound of the critical pseudoscalar meson mass mPS ,E≲170 MeV and the critical temperature TE=134 (3 ) MeV . Our estimate of the upper bound is derived from the existence of the critical point as an edge of the first order phase transition while that of the staggered-type fermions with smearing is based on its absence.
Strečka, Jozef; Verkholyak, Taras
2016-10-01
Magnetic properties of the ferrimagnetic mixed spin-(1/2,S) Heisenberg chains are examined using quantum Monte Carlo simulations for two different quantum spin numbers S=1 and 3/2. The calculated magnetization curves at finite temperatures are confronted with zero-temperature magnetization data obtained within the density matrix renormalization group method, which imply an existence of two quantum critical points determining a breakdown of the gapped Lieb-Mattis ferrimagnetic phase and Tomonaga-Luttinger spin-liquid phase, respectively. While a square root behavior of the magnetization accompanying each quantum critical point is gradually smoothed upon rising temperature, the susceptibility and isothermal entropy change data at low temperatures provide a stronger evidence of the zero-temperature quantum critical points through marked local maxima and minima, respectively.
Asakawa, M; Bass, S A; Müller, B; Nonaka, C
2008-09-19
The presence of a critical point in the QCD phase diagram can deform the trajectories describing the evolution of the expanding fireball in the mu_B-T phase diagram. If the average emission time of hadrons is a function of transverse velocity, as microscopic simulations of the hadronic freeze-out dynamics suggest, the deformation of the hydrodynamic trajectories will change the transverse velocity (beta_T) dependence of the proton-antiproton ratio when the fireball passes in the vicinity of the critical point. An unusual beta_T dependence of the [over]p/p ratio in a narrow beam energy window would thus signal the presence of the critical point.
Study of the critical points of HPMC hydrophilic matrices for controlled drug delivery.
Miranda, Antonia; Millán, Mónica; Caraballo, Isidoro
2006-03-27
The knowledge of the percolation thresholds of a system results in a clear improvement of the design of controlled release dosage forms such as inert matrices. Despite hydrophilic matrices are one of the most used controlled delivery systems in the world, but actuality, the mechanisms of drug release from these systems continue to be a matter of debate nowadays. The objective of the present paper is to apply the percolation theory to study the release and hydration rate of hydrophilic matrices. Matrix tablets have been prepared using KCl as a drug model and HPMC K4M as matrix-forming material, employing five different excipient/drug particle size ratios (ranging from 0.42 to 2.33). The formulations studied containing a drug loading in the range of 20-90% (w/w). Dissolution studies were carried out using the paddle method and the water uptake measurements were performed using a modified Enslin apparatus. In order to estimate the percolation threshold, the behaviour of the kinetic parameters with respect to the volumetric fraction of each component at time zero, was studied. The percolation theory has been applied for the first time to the study of matrix type controlled delivery systems. The application of this theory allowed to explain changes in the release and hydration kinetics of these matrices. The critical points observed in dissolution and water uptake studies can be attributed to the excipient percolation threshold, being this threshold one of the main factors governing the gel layer formation and consequently, the drug release control from hydrophilic matrices.
Theory of the nematic quantum critical point in a nodal superconductor
Kim, Eun-Ah
2008-03-01
In the last several years, experimental evidence has accumulated in a variety of highly correlated electronic systems of new quantum phases which (for purely electronic reasons) spontaneously break the rotational (point group) symmetry of the underlying crystal. Such electron ``nematic'' phases have been seen in quantum Hall systems[1], in the metamagnetic metal Sr3Ru2O7[2], and more recently in magnetic neutron scattering studies of the high temperature superconductor, YBCO[3]. In the case of a high Tc superconductor, the quantum dynamics of nematic order parameter naturally couples strongly to quasiparticle (qp) excitations. In this talk, I will discuss our recent results on the effects of the coupling between quantum critical nematic fluctuations and the nodal qp's of a d-wave superconductor in the vicinity of a putative quantum critical point inside the superconducting phase. We solve a model system with N flavors of quasiparticles in the large N limit[4]. To leading order in 1/N, quantum fluctuations enhance the dispersion anisotropy of the nodal excitations, and cause strong scattering which critically broadens the quasiparticle peaks in the spectral function, except in the vicinity of ``the tips of the banana,'' where the qp's remain sharp. We will discuss the possible implications of our results to ARPES and STM experiments. [1] M.P. Lilly, K.B. Cooper, J.P. Eisenstein, L.N. Pfeiffer, and K.W. West, PRL 83, 824 (1999). [2] R. A. Borzi and S. A. Grigera and J. Farrell and R. S. Perry and S. J. S. Lister and S. L. Lee and D. A. Tennant and Y. Maeno and A. P. Mackenzie, Science 315, 214 (2007). [3] V. Hinkov, D. Haug, B. Fauqu'e, P. Bourges, Y. Sidis, A. Ivanov, C. Bernhard, C. T. Lin, B. Keimer, unpublished. [4] E.-A. Kim, M. Lawler, P. Oreto, E. Fradkin, S. Kivelson, cond-mat/0705.4099.
Test of phi(sup 2) model predictions near the (sup 3)He liquid-gas critical point
Barmatz, M.; Zhong, F.; Hahn, I.
2000-01-01
NASA is supporting the development of an experiment called MISTE (Microgravity Scaling Theory Experiment) for future International Space Station mission. The main objective of this flight experiment is to perform in-situ PVT, heat capacity at constant volume, C(sub v) and chi(sub tau), measurements in the asymptotic region near the (sup 3)He liquid-gas critical point.
Theory of center-focus for a class of higher-degree critical points and infinite points
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
For the real planar autonomous differential system, the questionsof detection between center and focus, successor function, formal series, central integration, integration factor, focal values, values of singular point and bifurcation of limit cycles for a class of higher-degree critical points and infinite points are expounded.
Mel, Maizirwan; Karim, Mohamed Ismail Abdul; Salleh, Mohamad Ramlan Mohamed; Abdullah, Rohane
The study was conducted to determine the critical point of pO2 level in the production of lactic acid by Lactobacillus rhamnosus. The fermentation process was successfully carried out in laboratory scale fermenter/bioreactor using different pO2 level (the main parameter that significantly affects the growth of L. rhamnosus and lactic acid production) together with two other parameters; the agitation rate and pH. From the result, it was observed that the best production of lactic acid with the concentration of 16.85 g L-1 or 1.68% production yield has been obtained at the operating parameters of 5% pO2 level, agitation speed of 100 rpm and sample pH 6. The critical point of pO2 was found to be between 5 and 10%.
Energy Technology Data Exchange (ETDEWEB)
Khelalfa, R.; Durastanti, J.F. [Centre d' Etudes et de Recherche en Thermique, Environnement et Systemes, Paris 12, 61 avenue du General de Gaulle, 94010 Creteil Cedex (France); Darrozes, J.S. [Institut Jean Le Rond d' Alembert, Paris 6, 4 place Jussieu, 75252 Paris Cedex 05 (France)
2011-07-01
The assembly of metal parts that may be encountered in industry (nuclear, space, ...), creates frequently a path of leakage which can let a fluid pass. In this following study, we aim at understanding the phenomenology of a confined flow through the vicinity of critical point and its influence on the leakage rate. This sealing problem was limited to stationary and viscous situations. The leakage geometry has been assimilated to a capillary tube whose the wall temperature is fixed at the fluid critical value. A difference of pressure was imposed between a supercritical inlet and a subcritical outlet. The phenomenological approach has led to highlight the existence of a transition zone crossing the critical point. In this region of strong expansion, has shown the existence of a thermo-mechanical coupling and be taken a into account by the thermal convection joined the conduction to transport heat. It shows that the progression in fluid outwards is slowed by that cap effect. (authors)
X-ray Raman Scattering of Water Near the Critical Point: Comparison of an Isotherm and Isochore
Ishikawa, D; Shaw, D M; Tse, J S; Hiraoka, N; Baron, A Q R
2012-01-01
X-ray Raman spectra of liquid, sub- and super- critical water at the oxygen K-edge were measured, at densities 1.02 - 0.16 gcm^-3. Measurements were made along both an isotherm and an isochore passing near the critical point. As density is reduced there is a general tendency of the spectra to increasingly resemble that of the vapor phase, with, first, a well separated low-energy peak, and, eventually, at densities below the critical density, peaks appearing at higher energies corresponding to molecular transitions. The critical point itself is distinguished by a local maximum in the contrast between some of the spectroscopic features. The results are compared to computed X-ray absorption spectra of supercritical water.
IR spectra of water droplets in no man's land and the location of the liquid-liquid critical point.
Ni, Yicun; Skinner, J L
2016-09-28
No man's land is the region in the metastable phase diagram of water where it is very difficult to do experiments on liquid water because of homogeneous nucleation to the crystal. There are a number of estimates of the location in no man's land of the liquid-liquid critical point, if it exists. We suggest that published IR absorption experiments on water droplets in no man's land can provide information about the correct location. To this end, we calculate theoretical IR spectra for liquid water over a wide range of temperatures and pressures, using our E3B3 model, and use the results to argue that the temperature dependence of the experimental spectra is inconsistent with several of the estimated critical point locations, but consistent with others.
Directory of Open Access Journals (Sweden)
Tae Jung Kim
2014-02-01
Full Text Available The complex dielectric function ɛ and the E0 excitonic and band-edge critical-point structures of hexagonal GaN are reported for temperatures from 30 to 690 K and energies from 0.74 to 6.42 eV, obtained by rotating-compensator spectroscopic ellipsometry on a 1.9 μm thick GaN film deposited on a c-plane (0001 sapphire substrate by molecular beam epitaxy. Direct inversion and B-splines in a multilayer-structure calculation were used to extract the optical properties of the film from the measured pseudodielectric function ⟨ɛ⟩. At low temperature sharp E0 excitonic and critical-point interband transitions are separately observed. Their temperature dependences were determined by fitting the data to the empirical Varshni relation and the phenomenological expression that contains the Bose-Einstein statistical factor.
IR spectra of water droplets in no man's land and the location of the liquid-liquid critical point
Ni, Yicun; Skinner, J. L.
2016-09-01
No man's land is the region in the metastable phase diagram of water where it is very difficult to do experiments on liquid water because of homogeneous nucleation to the crystal. There are a number of estimates of the location in no man's land of the liquid-liquid critical point, if it exists. We suggest that published IR absorption experiments on water droplets in no man's land can provide information about the correct location. To this end, we calculate theoretical IR spectra for liquid water over a wide range of temperatures and pressures, using our E3B3 model, and use the results to argue that the temperature dependence of the experimental spectra is inconsistent with several of the estimated critical point locations, but consistent with others.
Energy Technology Data Exchange (ETDEWEB)
Bonatsos, Dennis [Institute of Nuclear Physics, NCSR ' Demokritos' GR-15310 Aghia Paraskevi, Attiki (Greece)]. E-mail: bonat@inp.demokritos.gr; Lenis, D. [Institute of Nuclear Physics, NCSR ' Demokritos' GR-15310 Aghia Paraskevi, Attiki (Greece)]. E-mail: lenis@inp.demokritos.gr; Petrellis, D. [Institute of Nuclear Physics, NCSR ' Demokritos' GR-15310 Aghia Paraskevi, Attiki (Greece)]. E-mail: petrellis@inp.demokritos.gr; Terziev, P.A. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 72 Tzarigrad Road, BG-1784 Sofia (Bulgaria)]. E-mail: terziev@inrne.bas.bg; Yigitoglu, I. [Institute of Nuclear Physics, NCSR ' Demokritos' GR-15310 Aghia Paraskevi, Attiki (Greece) and Hasan Ali Yucel Faculty of Education, Istanbul University, TR-34470 Beyazit, Istanbul (Turkey)]. E-mail: yigitoglu@istanbul.edu.tr
2005-08-11
A {gamma}-rigid solution of the Bohr Hamiltonian for {gamma}=30 deg. is derived, its ground state band being related to the second order Casimir operator of the Euclidean algebra E(4). Parameter-free (up to overall scale factors) predictions for spectra and B(E2) transition rates are in close agreement to the E(5) critical point symmetry, as well as to experimental data in the Xe region around A=130.
Bonatsos, D; Petrellis, D; Terziev, P A; Yigitoglu, I; Bonatsos, Dennis
2005-01-01
A gamma-rigid solution of the Bohr Hamiltonian for gamma = 30 degrees is derived, its ground state band being related to the second order Casimir operator of the Euclidean algebra E(4). Parameter-free (up to overall scale factors) predictions for spectra and B(E2) transition rates are in close agreement to the E(5) critical point symmetry, as well as to experimental data in the Xe region around A=130.
Coexistence of order and chaos at critical points of first-order quantum phase transitions in nuclei
Macek, M
2011-01-01
We study the interplay between ordered and chaotic dynamics at the critical point of a generic first-order quantum phase transition in the interacting boson model of nuclei. Classical and quantum analyses reveal a distinct behavior of the coexisting phases. While the dynamics in the deformed phase is robustly regular, the spherical phase shows strongly chaotic behavior in the same energy intervals. The effect of collective rotations on the dynamics is investigated.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
We study systematically the evolutive behaviors of some energy ratios,E2 transition rate ratios and isomer shift in the nuclear shape phase transitions.We find that the quantities sensitive to the phase transition and independent of free parameter(s) are approximately particle number N scale invariant around the critical point of the first order phase transition,similar to that in the second order phase transition.
Institute of Scientific and Technical Information of China (English)
ZHANG Yu; HOU ZhanFeng; LIU YuXin
2009-01-01
We study systematically the evolutive behaviors of some energy ratios,E2 transition rate ratios and Isomer shift in the nuclear shape phase transitions.We find that the quantities sensitive to the phase transition and independent of free parameter(s) are approximately particle number N scale invariant around the critical point of the first order phase transition,similar to that in the second order phase transition.
Energy Technology Data Exchange (ETDEWEB)
Konopelchenko, B [Dipartimento di Fisica, Universita di Lecce and Sezione INFN, 73100 Lecce (Italy); Alonso, L MartInez [Departamento de Fisica Teorica II, Universidad Complutense, E28040 Madrid (Spain); Medina, E [Departamento de Matematicas, Universidad de Cadiz, E11510 Puerto Real, Cadiz (Spain)
2010-10-29
It is shown that the hodograph solutions of the dispersionless coupled KdV (dcKdV) hierarchies describe critical and degenerate critical points of a scalar function which obeys the Euler-Poisson-Darboux equation. Singular sectors of each dcKdV hierarchy are found to be described by solutions of higher genus dcKdV hierarchies. Concrete solutions exhibiting shock-type singularities are presented.
Brücker, C.
2015-01-01
© 2015 AIP Publishing LLC. The recent discovery of rare backflow events in turbulent boundary layer flows based on the analysis of simulation data has again raised the need of experimental visualizations of wall-shear stress fields in unsteady flows. The localization of critical points, which are thought to strongly correlate with large-scale events in the log-layer, is of importance. Up to now, there is no experimental proof of these rare events and their topological patterns. Their existenc...
Critical points in the Bragg glass phase of a weakly pinned crystal of Ca3Rh4Sn13
Indian Academy of Sciences (India)
S Sarkar; A D Thakur; C V Tomy; G Balakrishnan; D McK Paul; S Ramakrishnan; A K Grover
2006-01-01
New experimental data are presented on the scan rate dependence of the magnetization hysteresis width () (∝ critical current density c()) in isothermal - scans in a weakly pinned single crystal of Ca3Rh4Sn13, which displays second magnetization peak (SMP) anomaly as distinct from the peak effect (PE). We observe an interesting modulation in the field dependence of a parameter which purports to measure the dynamical annealing of the disordered bundles of vortices injected through the sample edges towards the destined equilibrium vortex state at a given . These data, in conjunction with the earlier observations made while studying the thermomagnetic history dependence in c() in the tracing of the minor hysteresis loops, imply that the partially disordered state heals towards the more ordered state between the peak field of the SMP anomaly and the onset field of the PE. The vortex phase diagram in the given crystal of Ca3Rh4Sn13 has been updated in the context of the notion of the phase coexistence of the ordered and disordered regions between the onset field of the SMP anomaly and the spinodal line located just prior to the irreversibility line. A multi-critical point and a critical point in the (, ) region of the Bragg glass phase have been marked in this phase diagram and the observed behavior is discussed in the light of recent data on multi-critical point in the vortex phase diagram in a single crystal of Nb.
Relativistic nucleus-nucleus collisions and the QCD phase diagram
Stock, Reinhard
2005-01-01
A steep maximum occurs in the Wroblewski ratio between strange and non-strange quarks created in central nucleus-nucleus collisions, of about A=200, at the lower SPS energy square root s approximately= 7 GeV. By analyzing hadronic multiplicities within the grand canonical statistical hadronization model this maximum is shown to occur at a baryochemical potential of about 450 MeV. In comparison, recent QCD lattice calculations at finite baryochemical potential suggest a steep maximum of the light quark susceptibility, to occur at similar mu /sub B/, indicative of "critical fluctuation" expected to occur at or near the QCD critical endpoint. This endpoint had not been firmly pinned down but should occur in the 300 MeV < mu /sub B//sup c/ < 700 MeV interval. It is argued that central collisions within the low SPS energy range should exhibit a turning point between compression /heating, and expansion/cooling at energy density, temperature and mu /sub B/ close to the suspected critical point. Whereas from to...
Johnson, Michael R.
2006-01-01
In most general chemistry and introductory physical chemistry classes, critical point is defined as that temperature-pressure point on a phase diagram where the liquid-gas interface disappears, a phenomenon that generally occurs at relatively high temperatures or high pressures. Two examples are: water, with a critical point at 647 K (critical…
Bañados, Máximo; Faraggi, Alberto; Reyes, Ignacio
2016-01-01
We study the thermodynamic phase diagram of three-dimensional $sl(N;\\mathbb{R})$ higher spin black holes. By analyzing the semi-classical partition function we uncover a rich structure that includes Hawking-Page transitions to the AdS$_3$ vacuum, first order phase transitions among black hole states, and a second order critical point. Our analysis is explicit for $N=4$ but we extrapolate some of our conclusions to arbitrary $N$. In particular, we argue that even $N$ is stable in the ensemble under consideration but odd $N$ is not.
Suppression of the Shastry-Sutherland phase in Ce$_{2}$Pd$_{2}$Sn at a field induced critical point
Sereni, J. G.; Berisso, M. Gomez; Schmerber, G.; Braghta, A.; Kappler, J. P.
2010-01-01
The magnetic phase diagram of Ce$_2$Pd$_2$Sn is investigated through the field dependence of thermal, transport and magnetic measurements performed at low temperature. The upper transition, $T_M=4.8$ K is practically not affected by magnetic field up to B=1 T, whereas the lower one $T_C(B)$ rapidly increases from 2.1 K joining $T_M$ in a critical point at $T_{cr}=(4.2\\pm 0.3$)K for $B_{cr}=(0.12\\pm 0.03)$ T. At that point the intermediate phase, previously described as an unstable Shastry-Sut...
Institute of Scientific and Technical Information of China (English)
高承华
2014-01-01
In this paper, we consider the existence of three nontrivial solutions for a discrete non-linear multiparameter periodic problem involving the p-Laplacian. By using the similar method for the Dirichlet boundary value problems in [G. Bonanno and P. Candito, Appl. Anal., 88(4) (2009), pp. 605-616], we construct two new strong maximum principles and obtain that the boundary value problem has three positive solutions for λ and µ in some suitable intervals. The approaches we use are the critical point theory.
Rodríguez Orozco, Alain R; Ruiz Reyes, Héctor; Farias Rodríguez, Victor Manuel; Cruz Balandran, Jorge; Manzo Rodriguez, Lidia; Ung Medina, Eduardo; Cruz Bermudez, Claudia
2007-01-01
Allergic diseases represent a serious public health problem all over the world, and they use to be associated with environmental factors as well as with each patient genetic predisposition. To characterize consult profile and critical points of allergic patients attention attended by non-allergologists specialists but referred by allergologists. Descriptive study since October 2004 until February 2005, with a questionnaire to 255 patients attended by non-allergologists specialists in an IMSS hospital. Skin hypersensibility Prick-tests with standardized commercial extracts were practiced (1:20 p/v). Gender distribution was 41.96% male and 58.04% female, most of them (88.6%) from urban places (the reminder from rural ones); 55.37% with family history of allergy. In 49.02% the disease disturbs family behavior. Annual attention cost to allergic patients was 2,896.74 mexican pesos. Only 35.7% of patients get the disease control. Both work and home control of allergy exacerbation risk factors were poor. Critical points affecting allergic patients' treatment are attention to risk factors and to those factors exacerbating the disease (environmental and drug scheme choice). Non-allergologists specialists must consider a better control of allergic patients.
Garrabos, Yves; Palencia, Fabien; Lecoutre, Carole; Erkey, Can; Le Neindre, Bernard
2006-02-01
We present the master (i.e., unique) behavior of the correlation length, as a function of the thermal field along the critical isochore, asymptotically close to the gas-liquid critical point of xenon, krypton, argon, helium-3, sulfur hexafluoride, carbon dioxide, and heavy water. It is remarkable that this unicity extends to the correction-to-scaling terms. The critical parameter set, which contains all the needed information to reveal the master behavior, is composed of four thermodynamic coordinates of the critical point and one adjustable parameter which accounts for quantum effects in the helium-3 case. We use a scale dilatation method applied to the relevant physical variables of the one-component fluid subclass, in analogy with the basic hypothesis of the renormalization theory. This master behavior for the correlation length satisfies hyperscaling. We finally estimate the thermal field extent where the critical crossover of the singular thermodynamic and correlation functions deviates from the theoretical crossover function obtained from field theory.
Nakamura, Shin
2012-09-21
We find novel phase transitions and critical phenomena that occur only outside the linear-response regime of current-driven nonequilibrium states. We consider the strongly interacting (3+1)-dimensional N = 4 large-N(c) SU(N(c)) supersymmetric Yang-Mills theory with a single flavor of fundamental N = 2 hypermultiplet as a microscopic theory. We compute its nonlinear nonballistic quark-charge conductivity by using the AdS/CFT correspondence. We find that the system exhibits a novel nonequilibrium first-order phase transition where the conductivity jumps and the sign of the differential conductivity flips at finite current density. A nonequilibrium critical point is discovered at the end point of the first-order regime. We propose a nonequilibrium steady-state analogue of thermodynamic potential in terms of the gravity-dual theory in order to define the transition point. Nonequilibrium analogues of critical exponents are proposed as well. The critical behavior of the conductivity is numerically confirmed on the basis of these proposals. The present work provides a new example of nonequilibrium phase transitions and nonequilibrium critical points.
Baird, James K; Baker, Jonathan D; Hu, Baichuan; Lang, Joshua R; Joyce, Karen E; Sides, Alison K; Richey, Randi D
2015-03-12
Binary liquid mixtures having a consolute point can be used as solvents for chemical reactions. When excess cerium(IV) oxide is brought into equilibrium with a mixture of isobutyric acid + water, and the concentration of cerium in the liquid phase is plotted in van't Hoff form, a straight line results for temperatures sufficiently in excess of the critical solution temperature. Within 1 K of the critical temperature, however, the concentration becomes substantially suppressed, and the van't Hoff slope diverges toward negative infinity. According to the phase rule, one mole fraction can be fixed. Given this restriction, the temperature behavior of the data is in exact agreement with the predictions of both the principle of critical point isomorphism and the Gibbs-Helmholtz equation. In addition, we have determined the concentration of lead in the liquid phase when crystalline lead(II) sulfate reacts with potassium iodide in isobutyric acid + water. When plotted in van't Hoff form, the data lie on a straight line for all temperatures including the critical region. The phase rule indicates that two mole fractions can be fixed. With this restriction, the data are in exact agreement with the principle of critical point isomorphism.
Directory of Open Access Journals (Sweden)
L. S. Campana
2012-01-01
Full Text Available We explore the low-temperature thermodynamic properties and crossovers of a d-dimensional classical planar Heisenberg ferromagnet in a longitudinal magnetic field close to its field-induced zero-temperature critical point by employing the two-time Green’s function formalism in classical statistical mechanics. By means of a classical Callen-like method for the magnetization and the Tyablikov-like decoupling procedure, we obtain, for any d, a low-temperature critical scenario which is quite similar to the one found for the quantum counterpart. Remarkably, for d>2 the discrimination between the two cases is found to be related to the different values of the shift exponent which governs the behavior of the critical line in the vicinity of the zero-temperature critical point. The observation of different values of the shift-exponent and of the related critical exponents along thermodynamic paths within the typical V-shaped region in the phase diagram may be interpreted as a signature of emerging quantum critical fluctuations.
Multiple critical points and liquid-liquid equilibria from the van der Waals like equations of state
Energy Technology Data Exchange (ETDEWEB)
Artemenko, Sergey; Lozovsky, Taras; Mazur, Victor [Thermodynamics Department, Academy of Refrigeration, 65082 Odessa (Ukraine)
2008-06-18
The principal aim of this work is a comprehensive analysis of the phase diagram of water via the van der Waals like equations of state (EoSs) which are considered as superpositions of repulsive and attractive forces. We test more extensively the modified van der Waals EoS (MVDW) proposed by Skibinski et al (2004 Phys. Rev. E 69 061206) and refine this model by introducing instead of the classical van der Waals repulsive term a very accurate hard sphere EoS over the entire stable and metastable regions (Liu 2006 Preprint cond-mat/0605392). It was detected that the simplest form of MVDW EoS displays a complex phase behavior, including three critical points, and identifies four fluid phases (gas, low density liquid (LDL), high density liquid (HDL), and very high density liquid (VHDL)). Moreover the experimentally observed (Mallamace et al 2007 Proc. Natl Acad. Sci. USA 104 18387) anomalous behavior of the density of water in the deeply supercooled region (a density minimum) is reproduced by the MWDW EoS. An improvement of the repulsive part does not change the topological picture of the phase behavior of water in the wide range of thermodynamic variables. The new parameters set for second and third critical points are recognized by thorough analysis of experimental data for the loci of thermodynamic response function extrema.
Melia, Fulvio
Exciting new broadband observations of the galactic nucleus have placed the heart of the Milky Way under intense scrutiny in recent years. This has been due in part to the growing interest from theorists motivated to study the physics of black hole accretion, magnetized gas dynamics, and unusual star formation. The center of our Galaxy is now known to harbor the most compelling supermassive black hole candidate, weighing in at 3-4 million solar masses. Its nearby environment is comprised of a molecular dusty ring, clusters of evolved and young stars, diffuse hot gas, ionized gas streamers, and several supernova remnants. This chapter will focus on the physical makeup of this dynamic region and the feasibility of actually imaging the black hole's shadow in the coming decade with mm interferometry.
DEFF Research Database (Denmark)
Jensen, Ole B.; Morelli, Nicola
2011-01-01
In contemporary urban societies multiple networks and systems interact, overlap, exist in parallel, converge, conflict etc. creating unforeseen complexity and less transparency. By exploring how layered networks of physical movement, service information, goods delivery, commercial communication etc...... design, geography, and mobility studies. After the introduction in section we develop and define the notion of CPC based upon a broad set of disciplines and theories. We illustrate the usefulness of the notion within the field of mobility in the network city and within the field of service design...
Institute of Scientific and Technical Information of China (English)
崔珊; 何兰坡; 洪晓晨; 朱相德; Cedomir Petrovic; 李世燕
2016-01-01
It was found that selenium doping can suppress the charge-density-wave (CDW) order and induce bulk supercon-ductivity in ZrTe3. The observed superconducting dome suggests the existence of a CDW quantum critical point (QCP) in ZrTe3−x Sex near x≈0.04. To elucidate the superconducting state near the CDW QCP, we measure the thermal conductivity of two ZrTe3−x Sex single crystals (x=0.044 and 0.051) down to 80 mK. For both samples, the residual linear termκ0/T at zero field is negligible, which is a clear evidence for nodeless superconducting gap. Furthermore, the field dependence ofκ0/T manifests a multigap behavior. These results demonstrate multiple nodeless superconducting gaps in ZrTe3−x Sex , which indicates conventional superconductivity despite of the existence of a CDW QCP.
Widom line and the liquid-liquid critical point for the TIP4P/2005 water model.
Abascal, José L F; Vega, Carlos
2010-12-21
The Widom line and the liquid-liquid critical point of water in the deeply supercooled region are investigated via computer simulation of the TIP4P/2005 model. The Widom line has been calculated as the locus of compressibility maxima. It is quite close to the experimental homogeneous nucleation line and, in the region studied, it is almost parallel to the curve of temperatures of maximum density at fixed pressure. The critical temperature is determined by examining which isotherm has a region with flat slope. An interpolation in the Widom line gives the rest of the critical parameters. The computed critical parameters are T(c)=193 K, p(c)=1350 bar, and ρ(c)=1.012 g/cm(3). Given the performance of the model for the anomalous properties of water and for the properties of ice phases, the calculated critical parameters are probably close to those of real water.
von Ferber, C; Folk, R; Holovatch, Yu; Kenna, R; Palchykov, V
2011-06-01
We analyze the entropic equation of state for a many-particle interacting system in a scale-free network. The analysis is performed in terms of scaling functions, which are of fundamental interest in the theory of critical phenomena and have previously been theoretically and experimentally explored in the context of various magnetic, fluid, and superconducting systems in two and three dimensions. Here, we obtain general scaling functions for the entropy, the constant-field heat capacity, and the isothermal magnetocaloric coefficient near the critical point in uncorrelated scale-free networks, where the node-degree distribution exponent λ appears to be a global variable and plays a crucial role, similar to the dimensionality d for systems on lattices. This extends the principle of universality to systems on scale-free networks and allows quantification of the impact of fluctuations in the network structure on critical behavior.
Aminzadeh, Faranak; Dalziel, William B; Molnar, Frank J; Garcia, Linda J
2010-06-01
The sociophysical home environment is an integral component of everyday coping, self-identity, and well-being for individuals with dementia; however, residential discontinuity is a common experience for many of these individuals. This article examined the meanings, functions, and experiences associated with living at home for individuals with dementia at the critical point of relocation to a residential care facility. Qualitative research methods were used to analyze in-depth interviews with 16 individuals with dementia at their homes within 2 months prior to relocation. At the time of relocation, living at home had become a paradoxical experience for most participants. The findings inform practice and policy interventions at both individual and societal levels to help individuals with dementia age in place for as long as possible and to maximize their efforts to "place" themselves in their new living environments after relocation. Copyright 2010, SLACK Incorporated.
3 d - 4 d hybridization anomaly in NixPd1-x alloys at quantum critical point
Swain, P.; Srivastava, Sanjeev K.; Srivastava, Suneel K.
2017-07-01
First-principles density functional theory computations of electronic structure and local magnetic properties of the non-fluctuating ground state of NixPd1-x alloy system around its quantum critical point xc=0.026 have been performed. The density of states at the Fermi energy and certain other parameters characterizing the Ni 3 d - Pd 4 d hybridization apparently follow power-laws with x similar to that obeyed by the reported ferromagnetic to paramagnetic transition temperature. The width of Pd 4 d density of states (DOS) and centroid of Ni 3 d DOS show peak-like anomalies in the neighbourhood of xc, and so indicate a possible scenario of the existence of a definite relation between the orbital hybridization and the emergence of quantum fluctuations in the system.
Optical properties of ZnTe and ZnS nanocrystals by critical-points and Tauc-Lorentz models
Energy Technology Data Exchange (ETDEWEB)
En Naciri, A., E-mail: ennacir@univ-metz.f [Universite Paul Verlaine-Metz, Laboratoire LPMD, 1 Bd Arago, 57078 Metz (France); Ahmed, F. [Universite Paul Verlaine-Metz, Laboratoire LPMD, 1 Bd Arago, 57078 Metz (France); Stchakovsky, M. [Horiba-Jobin Yvon, Z. A. de la Vigne-aux-loups, 5 Avenue Arago, 91380 Chilly-Mazarin Cedex (France)
2011-02-28
The optical properties of ZnTe and ZnS nanocrystals (ZnTe-NC and ZnS-NC) were determined by Spectroscopic Ellipsometry. The nanocrystals were embedded in a SiO{sub 2} matrix by ion implantation technique. Their sizes were characterized by transmission electron microscopy. The ZnTe-NC and ZnS-NC were modelled using Critical Points (CPs) dispersion formulas developed by Adachi. Besides the CPs model, the Tauc-Lorentz model was found to be another choice to get a good spectral fitting. Here we demonstrated that these models yield reasonable values of optical constants of II-VI nanocrystals. The best agreement was found with the experimental data over the entire range of 0.6 to 6.5 eV.
Czaban, Christopher
2016-01-01
QCD at zero baryon density in the limit of infinite quark mass undergoes a first order deconfinement phase transition at a critical temperature $T_c$ corresponding to the breaking of the global centre symmetry. In the presence of dynamical quarks this symmetry is explicitly broken. Lowering the quark mass the first order phase transition weakens and terminates in a second order Z(2) point. Beyond this line confined and deconfined regions are analytically connected by a crossover transition. As the continuum limit is approached (i.e. the lattice spacing is decreased) the region of first order transitions expands towards lower masses. We study the deconfinement critical point with standard Wilson fermions and $N_f=2$ flavours. To this end we simulate several kappa values on $N_\\tau=8$ and various aspect ratios in order to extrapolate to the thermodynamic limit, applying finite size scaling. We estimate if and when a continuuum extrapolation is possible.
Finite-temperature scaling close to Ising-nematic quantum critical points in two-dimensional metals
Punk, Matthias
2016-11-01
We study finite-temperature properties of metals close to an Ising-nematic quantum critical point in two spatial dimensions. In particular we show that at any finite temperature there is a regime where order parameter fluctuations are characterized by a dynamical critical exponent z =2 , in contrast to z =3 found at zero temperature. Our results are based on a simple Eliashberg-type approach, which gives rise to a boson self-energy proportional to Ω /γ (T ) at small momenta, where γ (T ) is the temperature dependent fermion scattering rate. These findings might shed some light on recent Monte Carlo simulations at finite temperature, where results consistent with z =2 were found.
Energy Technology Data Exchange (ETDEWEB)
Kawasaki, S; Tabuchi, T; Zheng Guoqing [Department of Physics, Okayama University, Okayama 700-8530 (Japan); Wang, X F; Chen, X H [Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)
2010-05-15
{sup 75}As-zero-field nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements are performed on CaFe{sub 2}As{sub 2} under pressure. At P = 4.7 and 10.8 kbar, the temperature dependencies of nuclear-spin-lattice relaxation rate (1/T{sub 1}) measured in the tetragonal phase show no coherence peak just below T{sub c}(P) and decrease with decreasing temperature. The superconductivity is gapless at P = 4.7 kbar but evolves to that with multiple gaps at P = 10.8 kbar. We find that the superconductivity appears near a quantum critical point under pressures in the range 4.7 kbar {<=} P {<=} 10.8 kbar. Both electron correlation and superconductivity disappear in the collapsed tetragonal phase. A systematic study under pressure indicates that electron correlations play a vital role in forming Cooper pairs in this compound.
Lévy, F.; Sheikin, I.; Huxley, A.
2007-07-01
When a pure material is tuned to the point where a continuous phase-transition line is crossed at zero temperature, known as a quantum critical point (QCP), completely new correlated quantum ordered states can form. These phases include exotic forms of superconductivity. However, as superconductivity is generally suppressed by a magnetic field, the formation of superconductivity ought not to be possible at extremely high field. Here, we report that as we tune the ferromagnet, URhGe, towards a QCP by applying a component of magnetic field in the material's easy magnetic plane, superconductivity survives in progressively higher fields applied simultaneously along the material's magnetic hard axis. Thus, although superconductivity never occurs above a temperature of 0.5K, we find that it can survive in extremely high magnetic fields, exceeding 28T.
Energy Technology Data Exchange (ETDEWEB)
Levy, F.; Huxley, A. [CEA, SPSMS, DRFMC, F-38054 Grenoble, (France); Levy, F.; Sheikin, I. [CNRS, GHMFL, F-38042 Grenoble, (France); Huxley, A. [Univ Edinburgh, Scottish Univ Phys Alliance, Sch Phys, Edinburgh EH9 3JZ, Midlothian, (United Kingdom)
2007-07-01
When a pure material is tuned to the point where a continuous phase-transition line is crossed at zero temperature, known as a quantum critical point (QCP), completely new correlated quantum ordered states can form. These phases include exotic forms of superconductivity. However, as superconductivity is generally suppressed by a magnetic field, the formation of superconductivity ought not to be possible at extremely high field. Here, we report that as we tune the ferromagnet, URhGe, towards a QCP by applying a component of magnetic field in the material's easy magnetic plane, superconductivity survives in progressively higher fields applied simultaneously along the material's magnetic hard axis. Thus, although superconductivity never occurs above a temperature of 0.5 K, we find that it can survive in extremely high magnetic fields, exceeding 28 T. (authors)
Bennati, C.; Gozzelino, L.; Olivetti, E. S.; Basso, V.
2016-12-01
The phase transformation kinetics of LaFe11.41Mn0.30Si1.29-H1.65 magnetocaloric compound is addressed by low rate calorimetry experiments. Scans at 1 mK/s show that its first order phase transitions are made by multiple heat flux avalanches. Getting very close to the critical point, when the transition becomes of the second order type, the step-like discontinuous behaviour associated with avalanches is smoothed out and the thermal hysteresis disappears. This result is confirmed by magneto-resistivity measurements and allows to obtain accurate values of the temperature hysteresis (ΔThyst = 0.37 K) at zero external magnetic field and of the critical field (Hc = 1.19 T). The number and magnitude of heat flux avalanches change as the magnetic field strength is increased, showing the interplay between the intrinsic energy barrier between phases and the microstructural disorder of the sample.
Energy Technology Data Exchange (ETDEWEB)
Butlitsky, M. A.; Zelener, B. V. [Joint Institute for High Temperature of Russian Academy of Science, 125412, Russia, Moscow, Izhorskaya str. 13/2 (Russian Federation); Zelener, B. B. [Joint Institute for High Temperature of Russian Academy of Science, 125412, Russia, Moscow, Izhorskaya str. 13/2 (Russian Federation); Moscow Engineering Physics Institute, 115409, Russia, Moscow, Kashirskoe sh. 31 (Russian Federation)
2014-07-14
A two-component plasma model, which we called a “shelf Coulomb” model has been developed in this work. A Monte Carlo study has been undertaken to calculate equations of state, pair distribution functions, internal energies, and other thermodynamics properties. A canonical NVT ensemble with periodic boundary conditions was used. The motivation behind the model is also discussed in this work. The “shelf Coulomb” model can be compared to classical two-component (electron-proton) model where charges with zero size interact via a classical Coulomb law. With important difference for interaction of opposite charges: electrons and protons interact via the Coulomb law for large distances between particles, while interaction potential is cut off on small distances. The cut off distance is defined by an arbitrary ε parameter, which depends on system temperature. All the thermodynamics properties of the model depend on dimensionless parameters ε and γ = βe{sup 2}n{sup 1/3} (where β = 1/k{sub B}T, n is the particle's density, k{sub B} is the Boltzmann constant, and T is the temperature) only. In addition, it has been shown that the virial theorem works in this model. All the calculations were carried over a wide range of dimensionless ε and γ parameters in order to find the phase transition region, critical point, spinodal, and binodal lines of a model system. The system is observed to undergo a first order gas-liquid type phase transition with the critical point being in the vicinity of ε{sub crit}≈13(T{sub crit}{sup *}≈0.076),γ{sub crit}≈1.8(v{sub crit}{sup *}≈0.17),P{sub crit}{sup *}≈0.39, where specific volume v* = 1/γ{sup 3} and reduced temperature T{sup *} = ε{sup −1}.
Butlitsky, M A; Zelener, B B; Zelener, B V
2014-07-14
A two-component plasma model, which we called a "shelf Coulomb" model has been developed in this work. A Monte Carlo study has been undertaken to calculate equations of state, pair distribution functions, internal energies, and other thermodynamics properties. A canonical NVT ensemble with periodic boundary conditions was used. The motivation behind the model is also discussed in this work. The "shelf Coulomb" model can be compared to classical two-component (electron-proton) model where charges with zero size interact via a classical Coulomb law. With important difference for interaction of opposite charges: electrons and protons interact via the Coulomb law for large distances between particles, while interaction potential is cut off on small distances. The cut off distance is defined by an arbitrary ɛ parameter, which depends on system temperature. All the thermodynamics properties of the model depend on dimensionless parameters ɛ and γ = βe(2)n(1/3) (where β = 1/kBT, n is the particle's density, kB is the Boltzmann constant, and T is the temperature) only. In addition, it has been shown that the virial theorem works in this model. All the calculations were carried over a wide range of dimensionless ɛ and γ parameters in order to find the phase transition region, critical point, spinodal, and binodal lines of a model system. The system is observed to undergo a first order gas-liquid type phase transition with the critical point being in the vicinity of ɛ(crit) ≈ 13(T(*)(crit) ≈ 0.076), γ(crit) ≈ 1.8(v(*)(crit) ≈ 0.17), P(*)(crit) ≈ 0.39, where specific volume v* = 1/γ(3) and reduced temperature T(*) = ɛ(-1).
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Lacy, M. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Ridgway, S. E. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Gates, E. L. [UCO/Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Nielsen, D. M. [Department of Astronomy, University of Wisconsin, 475 N. Charter Street, Madison, WI 53706 (United States); Petric, A. O. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Sajina, A. [Department of Physics and Astronomy, Tuffs University, 212 College Avenue, Medford, MA 02155 (United States); Urrutia, T. [Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany); Cox Drews, S. [946 Mangrove Avenue 102, Sunnyvale, CA 94086 (United States); Harrison, C. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Seymour, N. [CSIRO, P.O. Box 76, Epping, NSW 1710 (Australia); Storrie-Lombardi, L. J. [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
2013-10-01
We present the results of a program of optical and near-infrared spectroscopic follow-up of candidate active galactic nuclei (AGNs) selected in the mid-infrared. This survey selects both normal and obscured AGNs closely matched in luminosity across a wide range, from Seyfert galaxies with bolometric luminosities L {sub bol} ∼ 10{sup 10} L {sub ☉} to highly luminous quasars (L {sub bol} ∼ 10{sup 14} L {sub ☉}), all with redshifts ranging from 0 to 4.3. Samples of candidate AGNs were selected with mid-infrared color cuts at several different 24 μm flux density limits to ensure a range of luminosities at a given redshift. The survey consists of 786 candidate AGNs and quasars, of which 672 have spectroscopic redshifts and classifications. Of these, 137 (20%) are type 1 AGNs with blue continua, 294 (44%) are type 2 objects with extinctions A{sub V} ∼> 5 toward their AGNs, 96 (14%) are AGNs with lower extinctions (A{sub V} ∼ 1), and 145 (22%) have redshifts, but no clear signs of AGN activity in their spectra. Of the survey objects 50% have L {sub bol} > 10{sup 12} L {sub ☉}, in the quasar regime. We present composite spectra for type 2 quasars and objects with no signs of AGN activity in their spectra. We also discuss the mid-infrared—emission-line luminosity correlation and present the results of cross correlations with serendipitous X-ray and radio sources. The results show that: (1) obscured objects dominate the overall AGN population, (2) mid-infrared selected AGN candidates exist which lack AGN signatures in their optical spectra but have AGN-like X-ray or radio counterparts, and (3) X-ray and optical classifications of obscured and unobscured AGNs often differ.
Finite-size scaling as a tool in the search for the QCD critical point in heavy ion data
Fraga, Eduardo S; Sorensen, Paul
2011-01-01
Given the short lifetime and the reduced volume of the quark-gluon plasma (QGP) formed in high-energy heavy ion collisions, a possible critical endpoint (CEP) will be blurred in a region and the effects from criticality severely smoothened. Nevertheless, the non-monotonic behavior of correlation functions near criticality for systems of different sizes, given by different centralities in heavy ion collisions, must obey finite-size scaling. We apply the predicting power of scaling plots to the search for the CEP of strong interactions in heavy ion collisions using data from RHIC and SPS. The results of our data analysis exclude a critical point below chemical potentials $\\mu\\sim 450 $MeV. Extrapolating the analysis, we speculate that criticality could appear slightly above $\\mu\\sim 500 $MeV. Using available data we extrapolate our scaling curves to predict the behavior of new data at lower center-of-mass energy, currently being investigated in the Beam Energy Scan program at RHIC. If it turns out that the QGP ...
Cong, P. T.; Postulka, L.; Wolf, B.; van Well, N.; Ritter, F.; Assmus, W.; Krellner, C.; Lang, M.
2016-10-01
Magneto-acoustic investigations of the frustrated triangular-lattice antiferromagnet Cs2CuCl4 were performed for the longitudinal modes c11 and c33 in magnetic fields along the a-axis. The temperature dependence of the sound velocity at zero field shows a mild softening at low temperature and displays a small kink-like anomaly at TN. Isothermal measurements at T sound attenuation α reveal two closely spaced features of different characters on approaching the material's quantum-critical point (QCP) at Bs ≈ 8.5 T for B || a. The peak at slightly lower fields remains sharp down to the lowest temperature and can be attributed to the ordering temperature TN(B). The second anomaly, which is rounded and which becomes reduced in size upon cooling, is assigned to the material's spin-liquid properties preceding the long-range antiferromagnetic ordering with decreasing temperature. These two features merge upon cooling suggesting a coincidence at the QCP. The elastic constant at lowest temperatures of our experiment at 32 mK can be well described by a Landau free energy model with a very small magnetoelastic coupling constant G/kB ≈ 2.8 K. The applicability of this classical model indicates the existence of a small gap in the magnetic excitation spectrum which drives the system away from quantum criticality.
Rybczynski, Maciej; Baatar, B.; Barna, D.; Bartke, J.; Beck, H.; Betev, L.; Bialkowska, H.; Blume, C.; Bogusz, M.; Boimska, B.; Book, J.; Botje, M.; Buncic, P.; Cetner, T.; Christakoglou, P.; Chung, P.; Chvala, O.; Cramer, J.G.; Eckardt, V.; Fodor, Z.; Foka, P.; Friese, V.; Gazdzicki, M.; Grebieszkow, K.; Hohne, C.; Kadija, K.; Karev, A.; Kolesnikov, V.I.; Kowalski, M.; Kresan, D.; Laszlo, A.; Lacey, R.; van Leeuwen, M.; Mackowiak-Pawlowska, M.; Makariev, M.; Malakhov, A.I.; Mateev, M.; Melkumov, G.L.; Mitrovski, M.; Mrowczynski, St.; Nicolic, V.; Palla, G.; Panagiotou, A.D.; Peryt, W.; Pluta, J.; Prindle, D.; Puhlhofer, F.; Renfordt, R.; Roland, C.; Roland, G.; Rybczynski, M.; Rybicki, A.; Sandoval, A.; Schmitz, N.; Schuster, T.; Seyboth, P.; Sikler, F.; Skrzypczak, E.; Slodkowski, M.; Stefanek, G.; Stock, R.; Strobele, H.; Susa, T.; Szuba, M.; Utvic, M.; Varga, D.; Vassiliou, M.; Veres, G.I.; Vesztergombi, G.; Vranic, D.; Wlodarczyk, Z.; Wojtaszek-Szwarc, A.
2013-01-01
The exploration of the QCD phase diagram particularly the search for a phase transition from hadronic to partonic degrees of freedom and possibly a critical endpoint, is one of the most challenging tasks in present heavy-ion physics. As observed by the NA49 experiment, several hadronic observables in central Pb+Pb collisions at the CERN SPS show qualitative changes in their energy dependence. These features are not observed in elementary interactions and indicate the onset of a phase transition in the SPS energy range. The existence of a critical point is expected to result in the increase of event-by-event fluctuations of various hadronic observables provided that the freeze-out of the measured hadrons occurs close to its location in the phase diagram and the evolution of the final hadron phase does not erase the fluctuations signals. A selection of NA49 results on di-pion and proton intermittency from the scan of the phase diagram will be discussed.
Energy Technology Data Exchange (ETDEWEB)
Agocs, Emil, E-mail: agocsemil@gmail.com [Doctoral School of Molecular and Nanotechnologies, Faculty of Information Technology, University of Pannonia, Egyetem u.10, Veszprém, H-8200 (Hungary); Research Institute for Technical Physics and Material Science (MFA), Research Centre for Natural Sciences, H-1525 Budapest, POB 49 (Hungary); Nassiopoulou, Androula G. [IMEL/NCSR Demokritos, Aghia Paraskevi, 153 10 Athens (Greece); Milita, Silvia [CNR-IMM Sezione Bologna, Via Gobetti, 40129 Bologna (Italy); Petrik, Peter [Doctoral School of Molecular and Nanotechnologies, Faculty of Information Technology, University of Pannonia, Egyetem u.10, Veszprém, H-8200 (Hungary); Research Institute for Technical Physics and Material Science (MFA), Research Centre for Natural Sciences, H-1525 Budapest, POB 49 (Hungary)
2013-08-31
Due to quantum-confinement the band structure of silicon nanocrystals (NCs) is different from that of bulk silicon and strongly depends on the NC size. The samples we investigated have been prepared using chemical vapor deposition and annealing allowing a good control of the parameters in terms of both thickness and NC size, being suitable as model systems. The problem of the analysis is that the critical point features of the dielectric function can only be described with acceptable accuracy when using numerous parameters. The majority of the fit parameters are describing the oscillators of different line-shapes. In this work we show how the number of fit parameters can be reduced by a systematic analysis to find non-sensitive and correlating parameters to fix and couple as much parameters as possible. - Highlights: ► Silicon nanocrystal films were measured by spectroscopic ellipsometry. ► The dielectric functions were modeled with Adachi's model dielectric function. ► We developed a parameter analysis and fitting algorithm. ► The non-sensitive parameters were coupled and neglected. ► The behaviors of key material parameters were determined.
Rillo, C.; Gabal, M.; Lozano, M. P.; Sesé, J.; Spagna, S.; Diederichs, J.; Sager, R.; Chialvo, C.; Terry, J.; Rayner, G.; Warburton, R.; Reineman, R.
2015-05-01
Low-temperature research laboratories with typical liquid-helium consumption of the order of tens of liters per day have greatly benefited from the recent development of small-scale liquefiers. In general, these liquefiers are based on Gifford-McMahon or pulse-tube closed-cycle refrigerators with a nominal cooling power ranging from 1 to 1.5 W at 4.2 K. The liquefaction rate for these cryocooler-based liquefiers depends on the pressure at which the helium is liquefied, although the final user conditions of the produced liquid helium are always atmospheric pressure and boiling temperature (e.g., 4.2 K at 100 kPa). Here, we show a systematic study on this effect, in which an enhancement in excess of 70% in liquefaction rate is found experimentally for pressures near and above the critical point of helium (220 kPa). We propose that the underlying mechanism for the liquefaction enhancement is based on the increase in cryocooler cooling power with temperature and the decrease of the helium enthalpy with pressure.
Kleine, Christian; Mußhoff, Julian; Anders, Frithjof B.
2014-12-01
The energy-dependent scattering of fermions from a localized orbital at an energy-dependent rate Γ (ɛ ) ∝|ɛ| r gives rise to quantum critical points (QCPs) in the pseudogap single-impurity Anderson model separating a local moment phase with an unscreened spin moment from a strong-coupling phase which slightly deviates from the screened phase of standard Kondo problem. Using the time-dependent numerical renormalization group (TD-NRG) approach we show that local dynamic properties always equilibrate towards a steady-state value even for quenches across the QCP but with systematic deviations from the thermal equilibrium depending on the distance to the critical coupling. Local nonequilibrium properties are presented for interaction quenches and hybridization quenches. We augment our numerical data by an analytical calculation that becomes exact at short times and find excellent agreement between the numerics and the analytical theory. For interaction quenches within the screened phase we find a universal function for the time-dependent local double occupancy. We trace back the discrepancy between our results and the data obtained by a time-dependent Gutzwiller variational approach to restrictions of the wave-function ansatz in the Gutzwiller theory: while the NRG ground states properly account for the formation of an extended spin moment which decouples from the system in the unscreened phase, the Gutzwiller ansatz only allows the formation of the spin moment on the local impurity orbital.
Yokota, Takeru; Morita, Kenji
2016-01-01
We first review the method to calculate the spectral functions in the functional renormalization group (FRG) approach, which has been recently developed. We also provide the numerical stability conditions given by the present authors for a generic nonlinear evolution equation that are necessary for obtaining the accurate effective potential from the flow equation in the FRG. As an interesting example, we report the recent calculation of the spectral functions of the mesonic and particle-hole excitations using a chiral effective model of Quantum Chromodynamics (QCD); we extract the dispersion relations from them and try to reveal the nature of the soft modes at the QCD critical point (CP) where the phase transition is second order. Our result shows that a clear development and the softening of the phonon mode in the space-like region as the system approaches the CP; furthermore it turns out that the sigma mesonic mode once in the time-like region gets to merge with the phonon mode in the close vicinity of the ...
Dib, R F A; Ould-Kaddour, F; Levesque, D
2006-07-01
Numerous theoretical and numerical works have been devoted to the study of the algebraic decrease at large times of the velocity autocorrelation function of particles in a fluid. The derivation of this behavior, the so-called long-time tail, generally based on linearized hydrodynamics, makes no reference to any specific characteristic of the particle interactions. However, in the literature doubts have been expressed about the possibility that by numerical simulations the long-time tail can be observed in the whole fluid phase domain of systems in which the particles interact by soft-core and attractive pair potentials. In this work, extensive and accurate molecular-dynamics simulations establish that the predicted long-time tail of the velocity autocorrelation function exists in a low-density fluid of particles interacting by a soft-repulsive potential and near the liquid-gas critical point of a Lennard-Jones system. These results contribute to the confirmation that the algebraic decay of the velocity autocorrelation function is universal in these fluid systems.
Isobe, Hiroki; Yang, Bohm-Jung; Chubukov, Andrey; Schmalian, Jörg; Nagaosa, Naoto
2016-02-19
We study the effects of Coulomb interaction between 2D Weyl fermions with anisotropic dispersion which displays relativistic dynamics along one direction and nonrelativistic dynamics along the other. Such a dispersion can be realized in phosphorene under electric field or strain, in TiO_{2}/VO_{2} superlattices, and, more generally, at the quantum critical point between a nodal semimetal and an insulator in systems with a chiral symmetry. Using the one-loop renormalization group approach in combination with the large-N expansion, we find that the system displays interaction-driven non-Fermi liquid behavior in a wide range of intermediate frequencies and marginal Fermi liquid behavior at the smallest frequencies. In the non-Fermi liquid regime, the quasiparticle residue Z at energy E scales as Z∝E^{a} with a>0, and the parameters of the fermionic dispersion acquire anomalous dimensions. In the marginal Fermi-liquid regime, Z∝(|logE|)^{-b} with universal b=3/2.
Dalmonte, M.; Lechner, W.; Cai, Zi; Mattioli, M.; Läuchli, A. M.; Pupillo, G.
2015-07-01
We investigate the quantum phases of hard-core bosonic atoms in an extended Hubbard model where particles interact via soft-shoulder potentials in one dimension. Using a combination of field-theoretical methods and strong-coupling perturbation theory, we demonstrate that the low-energy phase can be a conformal cluster Luttinger liquid (CLL) phase with central charge c =1 , where the microscopic degrees of freedom correspond to mesoscopic ensembles of particles. Using numerical density-matrix renormalization-group methods, we demonstrate that the CLL phase [first predicted in M. Mattioli et al., Phys. Rev. Lett. 111, 165302 (2013), 10.1103/PhysRevLett.111.165302] is separated from a conventional Tomonaga-Luttinger liquid by an exotic critical point with central charge c =3/2 . The latter is expression of an emergent conformal supersymmetry, which is not present in the original Hamiltonian. We discuss the observability of the CLL phase in realistic experimental settings with weakly dressed Rydberg atoms confined to optical lattices. Using quantum Monte Carlo simulations, we show that the typical features of CLLs are stable up to comparatively high temperatures. Using exact diagonalizations and quantum trajectory methods, we provide a protocol for adiabatic state preparation as well as quantitative estimates on the effects of particle losses.
Directory of Open Access Journals (Sweden)
E. Svanidze
2015-03-01
Full Text Available A quantum critical point (QCP occurs upon chemical doping of the weak itinerant ferromagnet Sc_{3.1}In. Remarkable for a system with no local moments, the QCP is accompanied by non-Fermi liquid behavior, manifested in the logarithmic divergence of the specific heat both in the ferro-and the paramagnetic states, as well as linear temperature dependence of the low-temperature resistivity. With doping, critical scaling is observed close to the QCP, as the critical exponents δ, γ, and β have weak composition dependence, with δ nearly twice and β almost half of their respective mean-field values. The unusually large paramagnetic moment μ_{PM}∼1.3μ_{B}/F.U. is nearly composition independent. Evidence for strong spin fluctuations, accompanying the QCP at x_{c}=0.035±0.005, may be ascribed to the reduced dimensionality of Sc_{3.1}In, associated with the nearly one-dimensional Sc-In chains.
BFKL Pomeron calculus: Nucleus-nucleus scattering
Energy Technology Data Exchange (ETDEWEB)
Contreras, Carlos, E-mail: carlos.contreras@usm.cl [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, Avda. Espana 1680, and Centro Cientifico-Tecnologico de Valparaiso, Casilla 110-V, Valparaiso (Chile); Levin, Eugene, E-mail: leving@post.tau.ac.il [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, Avda. Espana 1680, and Centro Cientifico-Tecnologico de Valparaiso, Casilla 110-V, Valparaiso (Chile); Department of Particle Physics, School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); Miller, Jeremy S., E-mail: jeremy.miller@ist.utl.pt [Department of Particle Physics, School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); CENTRA, Departamento de Fisica, Instituto Superior Tecnico (IST), Av. Rovisco Pais, 1049-001 Lisboa (Portugal)
2012-04-15
In this paper the action of the BFKL Pomeron calculus is rewritten in momentum representation, and the equations of motion for nucleus-nucleus collisions are derived, in this representation. We found the semiclassical solutions to these equations, outside of the saturation domain. Inside this domain these equations reduce to the set of delay differential equations, and their asymptotic solutions are derived.
Gallo, Paola; Sciortino, Francesco
2012-10-26
We present a finite-size scaling study of the liquid-liquid critical point in the Jagla model, a prototype model for liquids that present the same thermodynamic anomalies which characterize liquid water. Performing successive umbrella sampling grand canonical Monte Carlo simulations, we evaluate an accurate density of states for different system sizes and determine the size-dependent critical parameters. Extrapolation to infinite size provides estimates of the bulk critical values for this model. The finite-size study allows us to establish that critical fluctuations are consistent with the Ising universality class and to provide definitive evidence for the existence of a liquid-liquid critical point in the Jagla potential. This finding supports the possibility of the existence of a genuine liquid-liquid critical point in anomalous one-component liquids like water.
Patel, Sonal; Wilding, W Vincent; Rowley, Richard L
2011-01-14
Molecular dynamics simulations were performed to determine two-phase configurations of model propane molecules below the critical point and in the near-critical, two-phase region. A postprocessor that uses a Monte Carlo method for determination of volumes attributable to each molecule was used to obtain density histograms of the particles from which the bulk coexisting equilibrium vapor and liquid densities were determined. This method of analyzing coexisting densities in a two-phase simulation is straightforward and can be easily implemented for complex, multisite models. Various degrees of internal flexibility in the propane models have little effect on the coexisting densities at temperatures 40 K or more below the critical point, but internal flexibility (angle bending and bond vibrations) does affect the saturated liquid densities in the near-critical region, changing the critical temperature by approximately 20 K. Shorter cutoffs were also found to affect the phase dome and the location of the critical point.
Evidence of a quantum critical point in Ce1-xYbxCoIn5 alloys at high Yb doping
Singh, Y. P.; Haney, D. J.; Huang, X. Y.; White, B. D.; Maple, M. B.; Dzero, M.; Almasan, C. C.
2015-03-01
We performed this study on single crystals of Ce1-xYbxCoIn5 alloys with the motivation to further explore some of the previously reported unusual behaviors such as robust coherence and superconductivity, non-Fermi liquid (NFL) behavior, and the possibility of quantum criticality in higher Yb doping. Our specific heat and electronic magneto-transport measurements on the alloy with x = 0.75 nominal doping down to temperatures (T) as low as 0.5 K and magnetic fields (H) as high as 14 T. Our analysis of both specific heat and resistivity data unveils the presence of a crossover from NFL behavior at high temperatures to Fermi-liquid (FL) behavior at lower temperatures. Our analysis also indicates that the origin of the NFL behavior is a result of quantum fluctuations of unknown origin. The H-T phase diagram extracted from resistivity and specific heat shows that the crossover from NFL to FL behavior at zero temperature occurs at H = 0. This implies that the alloy with x = 0.75 Yb concentration is quantum critical, i.e., xc = 0.75. This result of zero field quantum critical point at x = 0.75 is also confirmed from our analysis of magneto-resistance data. This work was supported by the National Science Foundation (Grant NSF DMR-1006606) and Ohio Board of Regents (Grant OBR-RIP-220573) at KSU, and by the U.S. Department of Energy (Grant DE-FG02- 04ER46105) at UCSD.
Riederer, Beat M
2014-03-01
Most medical curricula rely on human bodies for teaching macroscopic anatomy. Over the past 20 years, plastination has become an important means of preservation of organs, for well dissected specimens or for body slices. Here, several critical points regarding body donation with legal and ethical considerations for long-term preservation, the use of cadavers in teaching and the preparation of plastinates as an additional teaching tool will be discussed. Silicone S10 is the gold standard in the preparation of plastinates. An important point to respect is the preparation of specimens, since only very well dissected body parts or excellent tissue sections should be plastinated to show the extraordinary aspects of the human anatomy. The preparation of thin and transparent sections and preservation with P40 polyester provides an additional technique to prepare resistant body slices. A selection of samples prepared by S10 and P40 are shown and compared. In addition, Prussian or Berlin blue staining of brain slices is shown to discriminate better between gray and white matter and demonstrate neuroanatomical structures. These plastinates have been used for many years in teaching first- and second-year medical students and have not lost their appeal. Students and staff appreciate the use of such plastinates. One of the advantages is that their use is not restricted to the dissection hall; slices and body parts can be used in any lecture room or in small group teaching. Therefore, ethical and legal questions need to be addressed regarding their specific use. Plastinates do not replace the traditional dissection courses, since students learn best the anatomical features of a given region by hands-on dissection and by exploratory anatomy. Furthermore, plastinates are more rigid and do not allow demonstration of hidden structures; they also become more cumbersome for endoscopy or are too rigid for demonstrating mechanical features of joints. However, although not a replacement
Energy Technology Data Exchange (ETDEWEB)
Mendoza, Bernardo S. [Department of Photonics, Centro de Investigaciones en Optica, A. C. Leon, Guanajuato (Mexico); Wei, Junwei; Downer, Michael C. [Department of Physics, The University of Texas at Austin, Austin, Texas 78712-1081 (United States)
2012-06-15
The E{sub 2} critical point (CP) resonance in the second-harmonic spectrum of silica-embedded Si nanocrystals (NCs) of 3 and 5 nm average diameter is observed to be blue-shifted by 0.5 eV from its energy (4.4 eV) in the linear dielectric response {epsilon}({omega}) of the same samples. In contrast, the E{sub 1} CP resonance (3.4 eV) and a third resonance intermediate in energy (3.8 eV) between E{sub 1} and E{sub 2} occur at nearly the same energy in both linear and nonlinear spectra. We explain the anomalous E{sub 2} blue-shift by calculating the second-harmonic response function {delta}({omega}) of the NCs analytically from the measured {epsilon}({omega}) using a dipolium model. The analysis shows that the E{sub 2} blue-shift originates from the screening factors of the form [{epsilon}(2{omega})+2]{sup -1} and [2{epsilon}(2{omega})+3]{sup -1} that are unique to second-harmonic generation (SHG) from nanospheres. Strong interaction between E{sub 2} and E'{sub 1} (5.3 eV in bulk c-Si) resonant contributions to this factor pulls the E{sub 2} peak response toward the higher E'{sub 1} energy while negligibly influencing lower energy resonances. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Institute of Scientific and Technical Information of China (English)
周文来; 密建国; 贺刚; 于燕梅; 陈健
2003-01-01
The description using an analytic equation of state of thermodynamic properties near the critical points of fluids and their mixtures remains a challenging problem in the area of chemical engineering. Based on the statistical associating fluid theory across the critical point (SAFT-CP), an analytic equation of state is established in this work for non-polar mixtures. With two binary parameters, this equation of state can be used to calculate not only vapor-liquid equilibria but also critical properties of binary non-polar alkane mixtures with acceptable deviations.
DEFF Research Database (Denmark)
Schrøder, H D
1981-01-01
in the length of the nucleus was observed. Based on the cytoarchitecture the nucleus could be divided in three parts, a cranial, a dorsomedial and a ventrolateral. All parts of the nucleus consisted of chromatin-rich medium-sized neurons, and apparent direct appositions between different cells bodies as well......The first, second and third sacral segments of 59 human spinal cords were examined in order to localize and describe Onuf's nucleus X. The nucleus was found to be situated in the ventral horn of the segments S2 and S3; only in very few spinal cords did it extend into S1. A significant variation...... as between cell bodies and large dendrites were observed. Characteristic findings in the neuropil surrounding the nucleus were the sparsity of myelinated fibers and the presence of dendritic bundles. The present observations are compared to the descriptions of a morphologically similar nucleus...
Directory of Open Access Journals (Sweden)
Z. GERGÁCZ
2013-07-01
Full Text Available The aim of the study was to analyse the relationship between the body condition and the results of metabolic profile tests done in the milk (DIM of dairy cows in different days. Moreover, critical points in the early pre- and postpartum period were also analysed. In the experiment, blood and urine samples were taken from 1984 clinically healthy cows (from 49 large scale dairy farms in Hungary, selected randomly from various groups of cows with different physiological stage of lactation and gestation, 3-5 hours after the morning feeding. During the experiment body condition scoring (BCS was measured on 1-5 scale, as well. It was concluded, that the BCS (body condition score decreased from the 1st day of lactation (3.48 onwards till the 44th day (2.65 and slightly increased till the day 218 (2.89. The haemoglobin value and the glucose concentration in blood samples were ranging within the physiological range and followed the tendency of BCS and the relationship between them and DIM was (P<0.001. There was a close negative correlation between the NEFA (non-esterified-fatty-acid concentration in blood samples and BCS change and it was found that these values were significantly different (P<0.01 compared to the DIM. The aceto-acetic acid concentration exceeded the upper limit of the physiological range indicating hyperketonaemia at DIM 18. The AST (aspartate aminotransferase, liver-enzyme activity value exceeded the upper limit of physiological range and followed the tendency of BCS change . The urea concentration in the blood exceeded the upper limit of the physiological range in all cows. The NABE (net acid-base empty value in the urine samples indicated acid load in the first two groups of samples (pre-, and post calving. During factor analysis I could differentiate three group factors and one individual. The most important factor is the acid-based factor (with urine pH and NEBA. The results of the present study also confirm that the body
Quantum Critical Point, Scaling, and Universality in High Tc [CaxLa(1-x)][Ba(2-c-x)La(c+x)]Cu3Oy
2005-01-01
Using charge transport observations on sintered ceramic samples of CLBLCO, we failed to observe the Quantum Critical Point (QCP) where it is expected. Experimental data relating Cooper pair density, electrical conductivity, and superconductivity critical temperature suggest that Homes' relation might need a more specific definition of 'sigma'. Transport observations on YBCO single crystals will resolve this question.
Shape transitions far from stability: The nucleus {sup 58}Cr
Energy Technology Data Exchange (ETDEWEB)
Marginean, N. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Italy) and National Institute for Physics and Nuclear Engineering, Bucharest (Romania)]. E-mail: nicolae.marginean@lnl.infn.it; Lenzi, S.M. [Dipartimento di Fisica and INFN, Padova (Italy); Gadea, A. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Italy)] (and others)
2006-02-23
Excited states up to I{sup {pi}}=8{sup +} in the neutron-rich nucleus {sup 58}Cr have been identified by using a new experimental setup composed of the large acceptance magnetic spectrometer PRISMA and the highly efficient {gamma}-detector array CLARA. Interestingly, the excitation energy sequence of the ground-state band follows the one expected by the E(5) dynamical symmetry for a nucleus at the critical point of the shape phase transition from a spherical vibrator (U(5)) to a {gamma}-soft rotor (O(6)). For the first time, in the same physical system, large scale shell-model calculations in the full fp shell are compared to the E(5) analytical model results and to the Interacting Boson Model. The theoretical results are in excellent agreement with the present data.
Goh, S K; Tompsett, D A; Saines, P J; Chang, H C; Matsumoto, T; Imai, M; Yoshimura, K; Grosche, F M
2015-03-06
The quasiskutterudite superconductor Sr_{3}Rh_{4}Sn_{13} features a pronounced anomaly in electrical resistivity at T^{*}∼138 K. We show that the anomaly is caused by a second-order structural transition, which can be tuned to 0 K by applying physical pressure and chemical pressure via the substitution of Ca for Sr. A broad superconducting dome is centered around the structural quantum critical point. Detailed analysis of the tuning parameter dependence of T^{*} as well as insights from lattice dynamics calculations strongly support the existence of a structural quantum critical point at ambient pressure when the fraction of Ca is 0.9 (i.e., x_{c}=0.9). This establishes the (Ca_{x}Sr_{1-x})_{3}Rh_{4}Sn_{13} series as an important system for exploring the physics of structural quantum criticality without the need of applying high pressures.
Oprisan, Ana; Oprisan, Sorinel A; Bayley, Brittany; Hegseth, John J; Garrabos, Yves; Lecoutre-Chabot, Carole; Beysens, Daniel
2012-12-01
Large density fluctuations were observed by illuminating a cylindrical cell filled with sulfur hexafluoride (SF(6)), very near its liquid-gas critical point (|T-T(c)|critical wave number, which is related to the characteristic length of fluctuations, steadily decreases over time, supporting a sustained increase in the spatial scale of the fluctuating domains. The scaled evolution of the critical wave number obeys the universal evolution for the interconnected domains at high volume fraction with an apparent power law exponent of -0.35 ± 0.02. We also determined the correlation time of the fluctuations and inferred values for thermal diffusivity coefficient very near the critical point, above and below. The values were used to pinpoint the crossing of T(c) within 13 μK.
Energy Technology Data Exchange (ETDEWEB)
Vial, Alexandre; Laroche, Thierry [Institut Charles Delaunay, Universite de Technologie de Troyes, CNRS FRE 2848, Laboratoire de Nanotechnologie et d' Instrumentation Optique 12, rue Marie Curie, BP-2060, F-10010 Troyes Cedex (France)
2007-11-21
Using a combination of Drude and critical points models, we show that the permittivity of several metals can be more efficiently described than using the well-known Drude-Lorentz model. The numerical implementation in a finite-difference time-domain code together with a non-uniform grid enables the study of thin metallic intermediate layers often neglected in simulations but found in realistic resonant structures.
Mauguière, Frédéric A L; Kramer, Zeb C; Carpenter, Barry K; Ezra, Gregory S; Farantos, Stavros C; Wiggins, Stephen
2015-01-01
We examine the phase space structures that govern reaction dynamics in the absence of critical points on the potential energy surface. We show that in the vicinity of hyperbolic invariant tori it is possible to define phase space dividing surfaces that are analogous to the dividing surfaces governing transition from reactants to products near a critical point of the potential energy surface. We investigate the problem of capture of an atom by a diatomic molecule and show that a normally hyperbolic invariant manifold exists at large atom-diatom distances, away from any critical points on the potential. This normally hyperbolic invariant manifold is the anchor for the construction of a dividing surface in phase space, which defines the outer or loose transition state governing capture dynamics. We present an algorithm for sampling an approximate capture dividing surface, and apply our methods to the recombination of the ozone molecule. We treat both 2 and 3 degree of freedom models with zero total angular momen...
Yu, Wing Chi; Cheung, Yiu Wing; Saines, Paul J; Imai, Masaki; Matsumoto, Takuya; Michioka, Chishiro; Yoshimura, Kazuyoshi; Goh, Swee K
2015-11-13
The family of the superconducting quasiskutterudites (Ca(x)Sr(1-x))(3)Rh(4)Sn(13) features a structural quantum critical point at x(c)=0.9, around which a dome-shaped variation of the superconducting transition temperature T(c) is found. Using specific heat, we probe the normal and the superconducting states of the entire series straddling the quantum critical point. Our analysis indicates a significant lowering of the effective Debye temperature on approaching x(c), which we interpret as a result of phonon softening accompanying the structural instability. Furthermore, a remarkably large enhancement of 2Δ/k(B)T(c) and ΔC/γT(c) beyond the Bardeen-Cooper-Schrieffer values is found in the vicinity of the structural quantum critical point. The phase diagram of (Ca(x)Sr(1-x))(3)Rh(4)Sn(13) thus provides a model system to study the interplay between structural quantum criticality and strong electron-phonon coupling superconductivity.
Energy Technology Data Exchange (ETDEWEB)
Mauguière, Frédéric A. L., E-mail: frederic.mauguiere@bristol.ac.uk; Collins, Peter, E-mail: peter.collins@bristol.ac.uk; Wiggins, Stephen, E-mail: stephen.wiggins@mac.com [School of Mathematics, University of Bristol, Bristol BS8 1TW (United Kingdom); Kramer, Zeb C., E-mail: zebcolterkramer@gmail.com; Ezra, Gregory S., E-mail: gse1@cornell.edu [Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853 (United States); Carpenter, Barry K., E-mail: carpenterb1@cardiff.ac.uk [School of Chemistry, Cardiff University, Cardiff CF10 3AT (United Kingdom); Farantos, Stavros C., E-mail: farantos@iesl.forth.gr [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, and Department of Chemistry, University of Crete, Iraklion 711 10, Crete (Greece)
2016-02-07
We examine the phase space structures that govern reaction dynamics in the absence of critical points on the potential energy surface. We show that in the vicinity of hyperbolic invariant tori, it is possible to define phase space dividing surfaces that are analogous to the dividing surfaces governing transition from reactants to products near a critical point of the potential energy surface. We investigate the problem of capture of an atom by a diatomic molecule and show that a normally hyperbolic invariant manifold exists at large atom-diatom distances, away from any critical points on the potential. This normally hyperbolic invariant manifold is the anchor for the construction of a dividing surface in phase space, which defines the outer or loose transition state governing capture dynamics. We present an algorithm for sampling an approximate capture dividing surface, and apply our methods to the recombination of the ozone molecule. We treat both 2 and 3 degrees of freedom models with zero total angular momentum. We have located the normally hyperbolic invariant manifold from which the orbiting (outer) transition state is constructed. This forms the basis for our analysis of trajectories for ozone in general, but with particular emphasis on the roaming trajectories.
Rose, F.; Dupuis, N.
2017-01-01
Using a nonperturbative functional renormalization-group approach to the two-dimensional quantum O (N ) model, we compute the low-frequency limit ω →0 of the zero-temperature conductivity in the vicinity of the quantum critical point. Our results are obtained from a derivative expansion to second order of a scale-dependent effective action in the presence of an external (i.e., nondynamical) non-Abelian gauge field. While in the disordered phase the conductivity tensor σ (ω ) is diagonal, in the ordered phase it is defined, when N ≥3 , by two independent elements, σA(ω ) and σB(ω ) , respectively associated to SO (N ) rotations which do and do not change the direction of the order parameter. For N =2 , the conductivity in the ordered phase reduces to a single component σA(ω ) . We show that limω→0σ (ω ,δ ) σA(ω ,-δ ) /σq2 is a universal number, which we compute as a function of N (δ measures the distance to the quantum critical point, q is the charge, and σq=q2/h the quantum of conductance). On the other hand we argue that the ratio σB(ω →0 ) /σq is universal in the whole ordered phase, independent of N and, when N →∞ , equal to the universal conductivity σ*/σq at the quantum critical point.
Fluctuations and correlations in nucleus-nucleus collisions within transport approaches
Energy Technology Data Exchange (ETDEWEB)
Konchakovski, Volodymyr P.
2009-10-01
The current thesis is devoted to a systematic study of fluctuations and correlations in heavy-ion collisions, which might be considered as probes for the phase transition and the critical point in the phase diagram, within the Hadron-String- Dynamics (HSD) microscopic transport approach. This is a powerful tool to study nucleus-nucleus collisions and allows to completely simulate experimental collisions on an event-by-event basis. Thus, the transport model has been used to study fluctuations and correlations including the influence of experimental acceptance as well as centrality, system size and collision energy. The comparison to experimental data can separate the effects induced by a phase transition since there is no phase transition in the HSD version used here. Firstly the centrality dependence of multiplicity fluctuations has been studied. Different centrality selections have been performed in the analysis in correspondence to the experimental situation. For the fixed target experiment NA49 events with fixed numbers of the projectile participants have been studied while in the collider experiment PHENIX centrality classes of events have been defined by the multiplicity in certain phase space region. A decrease of participant number fluctuations (and thus volume fluctuations) in more central collisions for both experiments has been obtained. Another area of this work addresses to transport model calculations of multiplicity fluctuations in nucleus-nucleus collisions as a function of colliding energy and system size. This study is in full correspondence to the experimental program of the NA61 Collaboration at the SPS. Central C+C, S+S, In+In, and Pb+Pb nuclear collisions at Elab = 10, 20, 30, 40, 80, 158 AGeV have been investigated. The expected enhanced fluctuations - attributed to the critical point and phase transition - can be observed experimentally on top of a monotonic and smooth 'hadronic background'. These findings should be helpful for the
Directory of Open Access Journals (Sweden)
Böyükata M.
2014-03-01
Full Text Available Quantum phase transitions in odd-nuclei are investigated within the framework of the interacting boson-fermion model with a description based on the concept of intrinsic states. We consider the case of a single j=9/2 odd-particle coupled to an even-even boson core that performs a transition from spherical to deformed prolate and to deformed gamma-unstable shapes varying a control parameter in the boson Hamiltonian. The effect of the coupling of the odd particle to this core is discussed along the shape transition and, in particular, at the critical point.
Dhanai, Ruchika; Rana, Puneet; Kumar, Lokendra
2016-05-01
The motivation behind the present analysis is to focus on magneto-hydrodynamic flow and heat transfer characteristics of non-Newtonian fluid (Sisko fluid) past a permeable nonlinear shrinking sheet utilizing nanoparticles involving convective boundary condition. The non-homogenous nanofluid transport model considering the effect of Brownian motion, thermophoresis, suction/injection and no nanoparticle flux at the sheet with convective boundary condition has been solved numerically by the RKF45 method with shooting technique. Critical points for various pertinent parameters are evaluated in this study. The dual solutions (both first and second solutions) are captured in certain range of material constant (ncthermophoresis parameter.
Giesy, Timothy J; Chou, Alan S; McFeeters, Robert L; Baird, James K; Barlow, Douglas A
2011-06-01
The mixture of isobutyric acid and water has a consolute point at a temperature of 25.75 °C and mole fraction 0.1148 isobutyric acid. When charcoal is added to this mixture, the concentration of isobutyric acid is reduced by adsorption. We have measured the action of charcoal on solutions of isobutyric acid and water as a function of isobutyric acid mole fraction at temperatures of 25.85 and 32.50 °C. At the higher temperature, the specific adsorption density (y(2)(α)/m) satisfies the Freundlich equation (y(2)(α)/m)=KX(2)(1/n), where y(2)(α) is the mass of isobutyric acid adsorbed, m is the mass of charcoal, X(2) is the equilibrium mole fraction of isobutyric acid, n is the Freundlich index, and K=K(T) is an amplitude that depends upon the temperature T. At 25.85 °C, a critical endpoint is located at an isobutyric acid mole fraction X(2)(ce)=0.09. When compared with the Freundlich equation at this temperature, a plot of the specific adsorption density as a function of X(2) in the vicinity of the critical-endpoint composition assumes a shape which is reminiscent of the derivative of a Dirac delta function. Using critical-point scaling theory, we show that this divergent pattern is consistent with the principle of critical point universality.
Urabe, Keiichiro; Kato, Toru; Himeno, Shohei; Kato, Satoshi; Stauss, Sven; Baba, Motoyoshi; Suemoto, Tohru; Terashima, Kazuo
2013-09-01
Pulsed laser ablation (PLA) plasmas generated in high-density gases and liquids are promising for the synthesis of nanomaterials. However, the characteristics of such plasmas are still not well understood. In order to improve the understandings of PLA plasmas in high-density fluids including gases, liquids, and supercritical fluids (SCFs), we have investigated the dynamics of PLA plasmas in high-density carbon dioxide (CO2) . We report on experimental results of time-resolved shadowgraph imaging, from the generation of plasma plume to the extinction of cavitation bubbles. Shadowgraph images revealed that the PLA plasma dynamics showed two distinct behaviors. These are divided by gas-liquid coexistence curve and the so-called Widom line, which separates gas-like and liquid-like SCF domains. Furthermore, cavitation bubble observed in liquid CO2 near the critical point showed peculiar characteristics, the formation of an inner bubble and an outer shell structure, which so far has never been reported. The experiments indicate that thermophysical properties of PLA plasmas can be tuned by controlling solvent temperature and pressure around the critical point, which may be useful for materials processing. This work was supported financially in part by a Grant-in-Aid for Scientific Research on Innovative Areas (No. 21110002) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.
Doucet, J R; Ross, A T; Gillespie, M B; Ryugo, D K
1999-06-14
Certain distinct populations of neurons in the dorsal cochlear nucleus are inhibited by a neural source that is responsive to a wide range of acoustic frequencies. In this study, we examined the glycine immunoreactivity of two types of ventral cochlear nucleus neurons (planar and radiate) in the rat which project to the dorsal cochlear nucleus (DCN) and thus, might be responsible for this inhibition. Previously, we proposed that planar neurons provided a tonotopic and narrowly tuned input to the DCN, whereas radiate neurons provided a broadly tuned input and thus, were strong candidates as the source of broadband inhibition (Doucet and Ryugo [1997] J. Comp. Neurol. 385:245-264). We tested this idea by combining retrograde labeling and glycine immunohistochemical protocols. Planar and radiate neurons were first retrogradely labeled by injecting biotinylated dextran amine into a restricted region of the dorsal cochlear nucleus. The labeled cells were visualized using streptavidin conjugated to indocarbocyanine (Cy3), a fluorescent marker. Sections that contained planar or radiate neurons were then processed for glycine immunocytochemistry using diaminobenzidine as the chromogen. Immunostaining of planar neurons was light, comparable to that of excitatory neurons (pyramidal neurons in the DCN), whereas immunostaining of radiate neurons was dark, comparable to that of glycinergic neurons (cartwheel cells in the dorsal cochlear nucleus and principal cells in the medial nucleus of the trapezoid body). These results are consistent with the hypothesis that radiate neurons in the ventral cochlear nucleus subserve the wideband inhibition observed in the dorsal cochlear nucleus.
Nucleus Driven Electronic Pulsation
Ludwig, H; Xue, S -S
2014-01-01
We derive and solve by the spectral method the equations for a neutral system of ultra-relativistic electrons that are compressed to the radius of the nucleus and subject to a driving force. This driving force can be thought of as originating from a nuclear breathing mode, a possibility we discuss in detail.
Energy Technology Data Exchange (ETDEWEB)
Gibbs, Gerald V.; Cox, David F.; Rosso, Kevin M.; Ross, Nancy L.; Downs, R. T.; Spackman, M. A.
2007-03-01
Bond critical point and local energy density properties together with net atomic charges were calculated for theoretical electron density distributions, F(r), generated for a variety of Fe and Cu metal-sulfide materials with high- and low-spin Fe atoms in octahedral coordination and high-spin Fe atoms in tetrahedral coordination. The electron density, F(rc), the Laplacian, 32F(rc), the local kinetic energy, G(rc), and the oxidation state of Fe increase as the local potential energy density, V(rc), the Fe-S bond lengths, and the coordination numbers of the Fe atoms decrease. The properties of the bonded interactions for the octahedrally coordinated low-spin Fe atoms for pyrite and marcasite are distinct from those for high-spin Fe atoms for troilite, smythite, and greigite. The Fe-S bond lengths are shorter and the values of F(rc) and 32F(rc) are larger for pyrite and marcasite, indicating that the accumulation and local concentration of F(r) in the internuclear region are greater than those involving the longer, high-spin Fe-S bonded interactions. The net atomic charges and the bonded radii calculated for the Fe and S atoms in pyrite and marcasite are also smaller than those for sulfides with high-spin octahedrally coordinated Fe atoms. Collectively, the Fe-S interactions are indicated to be intermediate in character with the low-spin Fe-S interactions having greater shared character than the highspin interactions. The bond lengths observed for chalcopyrite together with the calculated bond critical point properties are consistent with the formula Cu+Fe3+S2. The bond length is shorter and the F(rc) value is larger for the FeS4 tetrahedron displayed by metastable greigite than those displayed by chalcopyrite and cubanite, consistent with a proposal that the Fe atom in greigite is tetravalent. S-S bond paths exist between each of the surface S atoms of adjacent slabs of FeS6 octahedra comprising the layer sulfide smythite, suggesting that the neutral Fe3S4 slabs are
Institute of Scientific and Technical Information of China (English)
Jiang Shixue
2012-01-01
Greece,the first European country to fall into debt trouble,is faced with a painful decision on whether to stay in the euro zone.At present,the country is suffering the heavy blow of a triple crisissovereign debt,social problems and political uncertainty.
Singh, Neeraj Kumar; Snoussi, Hichem; Hewson, David; Duchêne, Jacques
The aim of this study was to develop a method to detecting the critical point interval (CPI) when sensory feedback is used as part of a closed-loop postural control strategy. Postural balance was evaluated using centre of pressure (COP) displacements from a force plate for 17 control and 10 elderly subjects under eyes open, eyes closed, and vibration conditions. A modified local-maximum-modulus wavelet transform analysis using the power spectrum of COP signals was used to calculate CPI. Lower CPI values indicate increased closed-loop postural control with a quicker response to sensory input. Such a strategy requires greater energy expenditure due to the repeated muscular interventions to remain stable. The CPI for elderly occurred significantly quicker than for controls, indicating tighter control of posture. Similar results were observed for eyes closed and vibration conditions. The CPI parameter can be used to detect differences in postural control due to ageing.
Energy Technology Data Exchange (ETDEWEB)
Pisipati, Venkata G.K.M.; Latha, Divi Madhavi; Madhav, Boddapati T.P. [Liquid Crystal Research Centre, ECE Dept., Koneru Lakshmaiah Univ., Vaddeswaram (India); Datta Prasad, Potapragada V. [Dept. of Physics, The Hindu Coll., Machilipatnam (India)
2010-04-15
The tri critical point (TCP), where the second-order transition transforms to first order has been located in nO.m homologous series. The order parameter has been estimated from the birefringence {delta}n, from the refractive indices and from birefringence data available in literature and from those obtained at our laboratory on a number of nO.m compounds. The compounds in the nO.m series exhibit both second and first-order nematic/smectic-A (NS{sub A}) transition depending on the McMillan ratio (T{sub NA}/T{sub IN}) which in turn depends on the nematic and smectic-A thermal ranges. The data presented are compared with the body of the data available on this homologous series obtained with other techniques. (orig.)
Institute of Scientific and Technical Information of China (English)
JIANG Chang-sheng; WU Zhong-liang
2005-01-01
Long-term seismic activity prior to the December 26, 2004, off the west coast of northern Sumatra, Indonesia, MW=9.0 earthquake was investigated using the Harvard CMT catalogue. It is observed that before this great earthquake, there exists an accelerating moment release (AMR) process with the temporal scale of a quarter century and the spatial scale of 1 500 km. Within this spatial range, the MW=9.0 event falls into the piece-wise power-law-like frequency-magnitude distribution. Therefore, in the perspective of the critical-point-like model of earthquake preparation, the failure to forecast/predict the approaching and/or the size of this earthquake is not due to the physically intrinsic unpredictability of earthquakes.
Lee, Sukbae; Jeon, Joonhyeon; Kim, Wonsoo; Chair, Tong-Seek
2008-12-11
To date, it has been considered that all classical equations of state (EOS) have failed to describe the properties of fluids near the critical region, where the density fluctuations have a significant influence on fluid properties. In this paper, we suggest a newly constructed equation for fluid states, the generalized van der Waals (GvdW) EOS with the highly simplified Dieterici's form P = [RT/(V - b)] - a(b/V)c by a new model potential construction describing intermolecular interactions. On the basis of the model potential construction, it is shown that the a, b, and c parameters have physical interpretations as an internal pressure, a void volume, and a dimensionless value that represents an inharmonic intermolecular cell potential, respectively. As an illustration of our model approach, we initially apply it to near the critical point (cp) region, where all classical EOS descriptions have been incorporated with experimental thermodynamic data, and we obtain a table of three parameters for 12 pure normal fluids, which precisely describes thermodynamic critical values. On the basis of the basic relations between pressure and volume at the critical point, we express the corresponding EOS in terms of the c parameter, and by this means, we also obtain a theoretical vapor-liquid equilibrium (VLE) line, which closely coincides with the experimental data for several pure normal fluids near the critical region. As a result, we show that thermodynamic properties near the critical region can be described analytically by only three parameters. In addition, to validate our EOS for the temperature-differential derivatives, we show that the calculated isochoric heat capacity (Cv) of saturated argon closely coincides with the experimental data. Moreover, the possibility of a precise description with respect to the entire fluid region is also argued, in terms of the physical cases from the triple point to the ideal gas region.
Neutrino nucleus cross sections
Athar, M Sajjad; Singh, S K; Vacas, M J Vicente
2008-01-01
We present the results of our calculation which has been performed to study the nuclear effects in the quasielastic, inelastic and deep inelastic scattering of neutrinos(antineutrinos) from nuclear targets. These calculations are done in the local density approximation. We take into account the effect of Pauli blocking, Fermi motion, Coulomb effect, renormalization of weak transition strengths in the nuclear medium in the case of the quasielastic reaction. The inelastic reaction leading to production of pions is calculated in a $\\Delta $- dominance model taking into account the renormalization of $\\Delta$ properties in the nuclear medium and the final state interaction effects of the outgoing pions with the residual nucleus. We discuss the nuclear effects in the $F_{3}^{A}(x)$ structure function in the deep inelastic neutrino(antineutrino) reaction using a relativistic framework to describe the nucleon spectral function in the nucleus.
Heavy flavor in nucleus-nucleus and proton-nucleus: quenching, flow and correlations
Nardi, M; De Pace, A; Monteno, M; Prino, F
2015-01-01
We present recent results for heavy-flavor observables in nucleus-nucleus collisions at LHC energies, obtained with the POWLANG transport setup. The initial creation of c-cbar and b-bbar pairs is simulated with a perturbative QCD approach (POWHEG+PYTHIA); their propagation in the medium (created in the nucleus-nucleus or in proton-nucleus collision) is studied with the relativistic Langevin equation, here solved using weak-coupling transport coefficients. Successively, the heavy quarks hadronize in the medium. We compute the nuclear modification factor and the elliptic flow parameter of the final D mesons both in nucleus-nucleus and in (for the first time, in the POWLANG setup) proton-nucleus collisions and compare our results to experimental data.
Nucleus-nucleus potential with shell-correction contribution
Denisov, V Yu
2015-01-01
The full relaxed-density potential between spherical nuclei is considered as a sum of the macroscopic and shell-correction contributions. The macroscopic part of the potential is related to a nucleus-nucleus potential obtained in the framework of the extended Thomas-Fermi approach with the Skyrme and Coulomb forces and the relaxed-density ansatz for evaluation of proton and neutron densities of interacting nuclei. A simple prescription for the shell-correction part of the total potential is discussed. The parameters of the shell-correction and macroscopic parts of the relaxed-density potential are found by fitting the empirical barrier heights of the 89 nucleus-nucleus systems as well as macroscopic potentials evaluated for 1485 nucleus-nucleus systems at 12 distances around touching points.
Energy Technology Data Exchange (ETDEWEB)
Gallagher, H.; /Tufts U.; Garvey, G.; /Los Alamos; Zeller, G.P.; /Fermilab
2011-01-01
The study of neutrino oscillations has necessitated a new generation of neutrino experiments that are exploring neutrino-nuclear scattering processes. We focus in particular on charged-current quasi-elastic scattering, a particularly important channel that has been extensively investigated both in the bubble-chamber era and by current experiments. Recent results have led to theoretical reexamination of this process. We review the standard picture of quasi-elastic scattering as developed in electron scattering, review and discuss experimental results, and discuss additional nuclear effects such as exchange currents and short-range correlations that may play a significant role in neutrino-nucleus scattering.
Antineutron-nucleus annihilation
Botta, E
2001-01-01
The n-nucleus annihilation process has been studied by the OBELIX experiment at the CERN Low Energy Antiproton Ring (LEAR) in the (50-400) MeV/c projectile momentum range on C, Al, Cu, Ag, Sn, and Pb nuclear targets. A systematic survey of the annihilation cross- section, sigma /sub alpha /(A, p/sub n/), has been performed, obtaining information on its dependence on the target mass number and on the incoming n momentum. For the first time the mass number dependence of the (inclusive) final state composition of the process has been analyzed. Production of the rho vector meson has also been examined. (13 refs).
Energy Technology Data Exchange (ETDEWEB)
Nakanishi, Y; Kamiyama, T; Ito, K; Nakamura, M; Yoshizawa, M [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Saiga, Y [Graduate School of Advanced Sciences of Matter, Hiroshima University, HigashiHiroshima 739-8530 (Japan); Kosaka, M [Department of Physics, Saitama University, Saitama 338-8570 (Japan); Uwatoko, Y, E-mail: yoshiki@iwate-u.ac.j [Institute for Solid State Physics, University of Tokyo, Kashiwa 227-8581 (Japan)
2010-01-15
We performed ultrasonic measurements on high quality single crystals of the Yb-based heavy fermion compounds YbTr{sub 2}Zn{sub 20} (Tr: Co, Rh and Ir) over a temperature range from 200 K to 0.5 K, which seem to be close to a quantum critical point (QCP). A sharp contrast of the temperature dependence of elastic constants was found at low temperature among the three compounds, reflecting the 4f electronic state stemmed from Yb ion. The results indicate that a crystalline electric field (CEF) effect seems to be dominant in the systems YbRh{sub 2}Zn{sub 20} and YbIr{sub 2}Zn{sub 20} at low temperatures. On the other hand, the CEF effect is much less, but an additional effect would be dominant which is most probably ascribable to non Fermi liquid characteristics formed close to the QCP. We discuss briefly each 4f electronic state developed at the low temperatures and physical parameters relating to a renormalized band model in YbTr{sub 2}Zn{sub 20} in the framework of a deformation potential approximation.
Institute of Scientific and Technical Information of China (English)
黄惠明
2015-01-01
Immunosuppressive drugs including glucocorticoids , azathioprine and cyclophosphamide , etc are the main drugs used for the treatment of interstitial pneumonia . According to the pathophysiological conditions of patients, antioxidant and anticoagulant are used for symptomatic and supporting treatment, and anti-pulmonary fibrosis is used for complication treatment . In this paper , the critical points of pharmaceutical care to the patients with interstitial pneumonia were explored including medicine characters , usage and dosage , adverse reaction , drug interactions and notice of medication , etc . so as to provide a reasonable proposal for clinical medication and ensure the safety and effectiveness of drug use .%间质性肺炎主要治疗药物包括糖皮质激素、硫唑嘌呤、环磷酰胺等免疫抑制药，根据患者的病理生理情况，采取抗氧化、抗凝等对症支持治疗，抗肺纤维化等并发症治疗。通过实例，从药物特点、用法用量、不良反应、相互作用、用药注意事项等方面探讨间质性肺炎患者的药学监护要点，为临床提供合理用药方案，保证临床安全、有效用药。
Energy Technology Data Exchange (ETDEWEB)
Tirado-Mejia, L; Prias-Barragan, J J; Gomez, J F; Ariza-Calderon, H, E-mail: litirado@uniquindio.edu.c [Laboratorio de Optoelectronica, Universidad del Quindio (Colombia)
2009-05-01
We present the analysis of the photoreflectance (PR) spectra line-shape of GaInAsSb films over GaSb. The studied samples were grown by liquid phase epitaxy technique. The growth parameters such as initial temperature and contact time were the same for all samples, but the precursor solution varied slightly in the As concentration. The cooling rate was different for each sample. The PR spectra were obtained at low temperature, modulated by a 632.8 nm He-Ne laser. These spectra were fitted using the third derivative lorentzian function but, for one of the samples exhibiting an additional structure around the E{sub 0} critical point oscillation, it was also necessary to use a first derivative lorentzian function, associated to an excitonic transition. This interpretation of the new PR feature was analyzed according to X-ray diffractograms. Comparing the FWHM of the main peak in the diffractograms it was found that the sample which exhibits the excitonic transition has the best crystalline quality, and was the sample with the lower cooling rate. The excitonic energy value obtained (9.7 meV) is in agreement with the value reported in the related literature.
Indications of a Quantum Critical Point in Bi2Sr2CaCu2O8+δ Using a Local Kondo Effect
Calleja, Eduardo; Dai, Jixia; Arnold, Gerald; Gu, Genda; McElroy, Kyle
2014-03-01
A complete understanding of the complex phase diagrams that are present in high temperature superconductors remains elusive. While there is an overwhelming amount of experimental data on the existence and interplay of the phases present in high Tc superconductors from local probes, much of the existing data only looks at the charge degree of freedom of the material. By substituting Fe atoms for Cu atoms in the CuO plane of Bi2Sr2CaCu2O8+δ (Bi2212), we gain the ability to access the spin degree of freedom since the Fe atoms retain their magnetization below the superconducting transition temperature. This leads to a local Kondo effect which can be observed using Spectroscopic-Imaging Scanning Tunneling Microscopy (SI-STM) and the local Kondo temperature can be extracted from spectra via a theoretical model. We show that the examination of this local Kondo temperature across local and sample average doping leads to the observation of a change in the quasiparticle spin degree of freedom at a quantum critical point (QCP) with a nominal hole doping of roughly 0.22, in agreement with other probes. The observation of the QCP in Bi2212 with this new method to access the spin degree of freedom helps to unravel some of the mystery behind the complex phase diagram of Bi2212.
Hechster, Elad; Sarusi, Gabby
2017-07-01
The complex dielectric function ɛ(E )=ɛR(E )+i ɛI(E ) of a semiconductor is a key parameter that dictates the material's optical and electrical properties. Surprisingly, the ɛ(E ) of Lead Sulfide (PbS) quantum dots (QDs) has not been widely studied. In the present work, we develop a new model that aims to simulate the ɛ(E ) of QDs. Our model is based on the fact that the quantum confinement in the nano regime affects all the electronic transitions throughout the entire Brillouin zone. Hence, as a first approximation, we attribute an equal contribution of energy, equivalent to the bandgap broadening, to each critical point (CP) in the E-k diagram. This is mathematically realized by adding these energy contributions to the central energy parameters of the Lorentz oscillator model. In order to validate our model, we used the CP parameters of bulk PbS to simulate the ɛ(E ) of PbS QDs. Next, we use Maxwell Relations to calculate the refractive index and the extinction coefficient of PbS QDs from ɛ(" separators="|E ). Our results were compared with those published in the previous literature and showed good agreement. Our findings open a new avenue that may enable the calculation of the ɛ(" separators="|E ) for nanoparticle systems.
Squire, Richard H.; March, Norman H.; Booth, Michael L.
There has been considerable effort expended toward understanding high temperature superconductors (HTSC), and more specifically the cuprate phase diagram as a function of doping level. Yet, the only agreement seems to be that HTSC is an example of a strongly correlated material where Coulomb repulsion plays a major role. This manuscript proposes a model based on a Feshbach resonance pairing mechanism and competing orders. An initial BCS-type superconductivity at high doping is suppressed in the two particle channel by a localized preformed pair (PP) (Nozieres and Schmitt-Rink, J Low Temp Phys, 1985, 59, 980) (circular density wave) creating a quantum critical point. As doping continues to diminish, the PP then participates in a Feshbach resonance complex that creates a new electron (hole) pair that delocalizes and constitutes HTSC and the characteristic dome (Squire and March, Int J Quantum Chem, 2007, 107, 3013; 2008, 108, 2819). The resonant nature of the new pair contributes to its short coherence length. The model we propose also suggests an explanation (and necessity) for an experimentally observed correlated lattice that could restrict energy dissipation to enable the resonant Cooper pair to move over several correlation lengths, or essentially free. The PP density wave is responsible for the pseudogap as it appears as a "localized superconductor" since its density of states and quasiparticle spectrum are similar to those of a superconductor (Peierls-Fröhlich theory), but with no phase coherence between the PP.
Quantum critical point in SmO(1-x)F(x)FeAs and oxygen vacancy induced by high fluorine dopant.
Cheng, Jie; Chu, Shengqi; Chu, Wangsheng; Xu, Wei; Zhou, Jing; Zhang, Linjuan; Zhao, Haifeng; Liu, Ronghua; Chen, Xianhui; Marcelli, Augusto; Wu, Ziyu
2011-09-01
The local lattice and electronic structure of the high-T(c) superconductor SmO(1-x)F(x)FeAs as a function of F-doping have been investigated by Sm L(3)-edge X-ray absorption near-edge structure and multiple-scattering calculations. Experiments performed at the L(3)-edge show that the white line (WL) is very sensitive to F-doping. In the under-doped region (x ≤ 0.12) the WL intensity increases with doping and then it suddenly starts decreasing at x = 0.15. Meanwhile, the trend of the WL linewidth versus F-doping levels is just contrary to that of the intensity. The phenomenon is almost coincident with the quantum critical point occurring in SmO(1-x)F(x)FeAs at x ≃ 0.14. In the under-doped region the increase of the intensity is related to the localization of Sm-5d states, while theoretical calculations show that both the decreasing intensity and the consequent broadening of linewidth at high F-doping are associated with the content and distribution of oxygen vacancies.
Rose, Félix
2016-01-01
Using a nonperturbative functional renormalization-group approach to the two-dimensional quantum O($N$) model, we compute the low-frequency limit $\\omega\\to 0$ of the zero-temperature conductivity in the vicinity of the quantum critical point. Our results are obtained from a derivative expansion to second order of a scale-dependent effective action in the presence of an external (i.e., non-dynamical) non-Abelian gauge field. While in the disordered phase the conductivity tensor $\\sigma(\\omega)$ is diagonal, in the ordered phase it is defined, when $N\\geq 3$, by two independent elements, $\\sigma_{\\rm A}(\\omega)$ and $\\sigma_{\\rm B}(\\omega)$, respectively associated to SO($N$) rotations which do and do not change the direction of the order parameter. For $N=2$, the conductivity in the ordered phase reduces to a single component $\\sigma_{\\rm A}(\\omega)$. We show that $\\lim_{\\omega\\to 0}\\sigma(\\omega,\\delta)\\sigma_{\\rm A}(\\omega,-\\delta)/\\sigma_q^2$ is a universal number which we compute as a function of $N$ ($\\d...
Pang, Jinbo; Deng, Lingfei
2017-01-01
Although frequent fluctuations in domestic hog prices seriously affect the stability and robustness of the hog supply chain, hog futures (an effective hedging instrument) have not been listed in China. To better understand hog futures market hedging, it is important to study the steady state of intersubjective bidding. This paper uses evolutionary game theory to construct a game model between hedgers and speculators in the hog futures market, and replicator dynamic equations are then used to obtain the steady state between the two trading entities. The results show that the steady state is one in which hedgers adopt a “buy” strategy and speculators adopt a “do not speculate” strategy, but this type of extreme steady state is not easily realized. Thus, to explore the rational proportion of hedgers and speculators in the evolutionary stabilization strategy, bidding processes were simulated using weekly average hog prices from 2006 to 2015, such that the conditions under which hedgers and speculators achieve a steady state could be analyzed. This task was performed to achieve the stability critical point, and we show that only when the value of λ is satisfied and the conditions of hog futures price changes and futures price are satisfied can hedgers and speculators achieve a rational proportion and a stable hog futures market. This market can thus provide a valuable reference for the development of the Chinese hog futures market and the formulation and guidance of relevant departmental policies. PMID:28241024
Cheng, Jie; Dong, Peng; Xu, Wei; Liu, Shengli; Chu, Wangsheng; Chen, Xianhui; Wu, Ziyu
2015-07-01
Many researchers have pointed out that there is a quantum critical point (QCP) in the F-doped SmOFeAs system. In this paper, the electronic structure and local structure of the superconductive FeAs layer in SmO(1-x)FxFeAs as a function of the F-doping concentration have been investigated using Fe and As K-edge X-ray absorption spectroscopy. Experiments performed on the X-ray absorption near-edge structure showed that in the vicinity of the QCP the intensity of the pre-edge feature at the Fe-edge decreases continuously, while there is a striking rise of the shoulder-peak at the As edge, suggesting the occurrence of charge redistribution near the QCP. Further analysis on the As K-edge extended X-ray absorption fine structure demonstrated that the charge redistribution originates mostly from a shortening of the Fe-As bond at the QCP. An evident relationship between the mysterious QCP and the fundamental Fe-As bond was established, providing new insights on the interplay between QCP, charge dynamics and the local structural Fe-As bond in Fe-based superconductors.
Directory of Open Access Journals (Sweden)
J. S. Kim
2015-07-01
Full Text Available The specific feature of multi-component oxides synthesized by hydrothermal process under high temperature (633 K and highly pressurized water (18.9 MPa near critical point. Effects of hydrothermal processing duration times 24 hours and 72 hours, respectively, on the oxide formation of the Ni59Zr20Ti16Si2Sn3 metallic glass synthesized by powder metallurgy process were characterized by X-ray diffractometer, differential scanning calorimeter along with the particle size, morphology and crystalline phase of the oxides. The crystallization of the needle-shape NiTiO3, ZrTiO4 and ZrSnO4 ternary oxide phases observed on the surface of metallic glass at below glass transition temperature and the morphology of oxide phases changed to plate-shape around 2 μm in diameter by the increase processing time. This hydrothermal processing in subcritical water provides accelerated dense metal oxide crystals due to the reaction medium being at higher pressure than conventional oxidation processing.
Energy Technology Data Exchange (ETDEWEB)
Kim, J. S.; Lee, M. H., E-mail: mhlee1@kitech.re.kr [Headquarters Bearing Division, Iljin Global Co., Ltd., Seoul 135-875 (Korea, Republic of); Kim, S. Y. [Rare Metals R& D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Kim, D. H. [Center for Noncrystalline Materials, Yonsei University, Seoul 120-749 (Korea, Republic of); Ott, R. T. [Division of Materials and Engineering, Ames Laboratory (US DOE), Ames, Iowa 50011 (United States); Kim, H. G. [LWR Fuel Technology Division, Korea Atomic Energy Institute, Daejeon 305-600 (Korea, Republic of)
2015-07-15
The specific feature of multi-component oxides synthesized by hydrothermal process under high temperature (633 K) and highly pressurized water (18.9 MPa) near critical point. Effects of hydrothermal processing duration times 24 hours and 72 hours, respectively, on the oxide formation of the Ni{sub 59}Zr{sub 20}Ti{sub 16}Si{sub 2}Sn{sub 3} metallic glass synthesized by powder metallurgy process were characterized by X-ray diffractometer, differential scanning calorimeter along with the particle size, morphology and crystalline phase of the oxides. The crystallization of the needle-shape NiTiO{sub 3}, ZrTiO{sub 4} and ZrSnO{sub 4} ternary oxide phases observed on the surface of metallic glass at below glass transition temperature and the morphology of oxide phases changed to plate-shape around 2 μm in diameter by the increase processing time. This hydrothermal processing in subcritical water provides accelerated dense metal oxide crystals due to the reaction medium being at higher pressure than conventional oxidation processing.
Pang, Jinbo; Deng, Lingfei; Wang, Gangyi
2017-01-01
Although frequent fluctuations in domestic hog prices seriously affect the stability and robustness of the hog supply chain, hog futures (an effective hedging instrument) have not been listed in China. To better understand hog futures market hedging, it is important to study the steady state of intersubjective bidding. This paper uses evolutionary game theory to construct a game model between hedgers and speculators in the hog futures market, and replicator dynamic equations are then used to obtain the steady state between the two trading entities. The results show that the steady state is one in which hedgers adopt a "buy" strategy and speculators adopt a "do not speculate" strategy, but this type of extreme steady state is not easily realized. Thus, to explore the rational proportion of hedgers and speculators in the evolutionary stabilization strategy, bidding processes were simulated using weekly average hog prices from 2006 to 2015, such that the conditions under which hedgers and speculators achieve a steady state could be analyzed. This task was performed to achieve the stability critical point, and we show that only when the value of λ is satisfied and the conditions of hog futures price changes and futures price are satisfied can hedgers and speculators achieve a rational proportion and a stable hog futures market. This market can thus provide a valuable reference for the development of the Chinese hog futures market and the formulation and guidance of relevant departmental policies.
Higgs-Boson Production in Nucleus-Nucleus Collisions
Norbury, John W.
1992-01-01
Cross section calculations are presented for the production of intermediate-mass Higgs bosons produced in ultrarelativistic nucleus-nucleus collisions via two photon fusion. The calculations are performed in position space using Baur's method for folding together the Weizsacker-Williams virtual-photon spectra of the two colliding nuclei. It is found that two photon fusion in nucleus-nucleus collisions is a plausible way of finding intermediate-mass Higgs bosons at the Superconducting Super Collider or the CERN Large Hadron Collider.
Source size determination in relativistic nucleus-nucleus collisions
Energy Technology Data Exchange (ETDEWEB)
Nagle, J.L.; Kumar, B.S.; Bennett, M.J.; Diebold, G.E.; Pope, J.K. (Yale University, A. W. Wright Nuclear Structure Laboratory, New Haven, Connecticut 06520-8124 (United States)); Sorge, H.; Sullivan, J.P. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))
1994-08-29
We describe a technique whereby the freeze-out interaction volumes of nucleus-nucleus collisions are extracted from a cascade (plus coalescence) model, after comparison to measured abundances of light nuclei. We conclude that the interaction volume undergoes significant expansion before light nuclei are produced.
Energy Technology Data Exchange (ETDEWEB)
Cong, P. T., E-mail: t.pham@hzdr.de [Dresden High Magnetic Field Laboratory, Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden (Germany); Physics Institute, Goethe University Frankfurt, D-60438 Frankfurt am Main (Germany); Postulka, L.; Wolf, B.; Ritter, F.; Assmus, W.; Krellner, C.; Lang, M., E-mail: michael.lang@physik.uni-frankfurt.de [Physics Institute, Goethe University Frankfurt, D-60438 Frankfurt am Main (Germany); Well, N. van [Physics Institute, Goethe University Frankfurt, D-60438 Frankfurt am Main (Germany); Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen (Switzerland)
2016-10-14
Magneto-acoustic investigations of the frustrated triangular-lattice antiferromagnet Cs{sub 2}CuCl{sub 4} were performed for the longitudinal modes c{sub 11} and c{sub 33} in magnetic fields along the a-axis. The temperature dependence of the sound velocity at zero field shows a mild softening at low temperature and displays a small kink-like anomaly at T{sub N}. Isothermal measurements at T < T{sub N} of the sound attenuation α reveal two closely spaced features of different characters on approaching the material's quantum-critical point (QCP) at B{sub s} ≈ 8.5 T for B || a. The peak at slightly lower fields remains sharp down to the lowest temperature and can be attributed to the ordering temperature T{sub N}(B). The second anomaly, which is rounded and which becomes reduced in size upon cooling, is assigned to the material's spin-liquid properties preceding the long-range antiferromagnetic ordering with decreasing temperature. These two features merge upon cooling suggesting a coincidence at the QCP. The elastic constant at lowest temperatures of our experiment at 32 mK can be well described by a Landau free energy model with a very small magnetoelastic coupling constant G/k{sub B} ≈ 2.8 K. The applicability of this classical model indicates the existence of a small gap in the magnetic excitation spectrum which drives the system away from quantum criticality.
Silk fibroin porous scaffolds for nucleus pulposus tissue engineering
Energy Technology Data Exchange (ETDEWEB)
Zeng, Chao; Yang, Qiang [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Tianjin Medical University, Tianjin 300070 (China); Zhu, Meifeng [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Du, Lilong [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Tianjin Medical University, Tianjin 300070 (China); Zhang, Jiamin [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Ma, Xinlong [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Xu, Baoshan, E-mail: xubaoshan99@126.com [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Wang, Lianyong, E-mail: wly@nankai.edu.cn [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China)
2014-04-01
Intervertebral discs (IVDs) are structurally complex tissue that hold the vertebrae together and provide mobility to spine. The nucleus pulposus (NP) degeneration often results in degenerative IVD disease that is one of the most common causes of back and neck pain. Tissue engineered nucleus pulposus offers an alternative approach to regain the function of the degenerative IVD. The aim of this study is to determine the feasibility of porous silk fibroin (SF) scaffolds fabricated by paraffin-sphere-leaching methods with freeze-drying in the application of nucleus pulposus regeneration. The prepared scaffold possessed high porosity of 92.38 ± 5.12% and pore size of 165.00 ± 8.25 μm as well as high pore interconnectivity and appropriate mechanical properties. Rabbit NP cells were seeded and cultured on the SF scaffolds. Scanning electron microscopy, histology, biochemical assays and mechanical tests revealed that the porous scaffolds could provide an appropriate microstructure and environment to support adhesion, proliferation and infiltration of NP cells in vitro as well as the generation of extracellular matrix. The NP cell–scaffold construction could be preliminarily formed after subcutaneously implanted in a nude mice model. In conclusion, The SF porous scaffold offers a potential candidate for tissue engineered NP tissue. - Highlights: • Paraffin microsphere-leaching method is used to fabricate silk fibroin scaffold. • The scaffold has appropriate mechanical property, porosity and pore size • The scaffold supports growth and infiltration of nucleus pulposus cells. • Nucleus pulposus cells can secrete extracellular matrix in the scaffolds. • The scaffold is a potential candidate for tissue engineered nucleus pulposus.
Energy Technology Data Exchange (ETDEWEB)
Piotr A. Domanski; W. Vance Payne
2002-10-31
The main goal of this project was to investigate and compare the performance of an R410A air conditioner to that of an R22 air conditioner, with specific interest in performance at high ambient temperatures at which the condenser of the R410A system may be operating above the refrigerant's critical point. Part 1 of this project consisted of conducting comprehensive measurements of thermophysical for refrigerant R125 and refrigerant blends R410A and R507A and developing new equation of state formulations and mixture models for predicting thermophysical properties of HFC refrigerant blends. Part 2 of this project conducted performance measurements of split-system, 3-ton R22 and R410A residential air conditioners in the 80 to 135 F (27.8 to 57.2 C) outdoor temperature range and development of a system performance model. The performance data was used in preparing a beta version of EVAP-COND, a windows-based simulation package for predicting performance of finned-tube evaporators and condensers. The modeling portion of this project also included the formulation of a model for an air-conditioner equipped with a thermal expansion valve (TXV). Capacity and energy efficiency ratio (EER) were measured and compared. The R22 system's performance was measured over the outdoor ambient temperature range of 80 to 135 F (27.8 to 57.2 C). The same test range was planned for the R410A system. However, the compressor's safety system cut off the compressor at the 135.0 F (57.2 C) test temperature. The highest measurement on this system was at 130.0 F (54.4 C). Subsequently, a custom-manufactured R410A compressor with a disabled safety system and a more powerful motor was installed and performance was measured at outdoor temperatures up to 155.0 F (68.3 C). Both systems had similar capacity and EER performance at 82.0 F (27.8 C). The capacity and EER degradation of both systems were nearly linearly dependent with rising ambient outdoor ambient test temperatures. The
Lammerding, Jan
2015-01-01
The nucleus is the distinguishing feature of eukaryotic cells. Until recently, it was often considered simply as a unique compartment containing the genetic information of the cell and associated machinery, without much attention to its structure and mechanical properties. This article provides compelling examples that illustrate how specific nuclear structures are associated with important cellular functions, and how defects in nuclear mechanics can cause a multitude of human diseases. During differentiation, embryonic stem cells modify their nuclear envelope composition and chromatin structure, resulting in stiffer nuclei that reflect decreased transcriptional plasticity. In contrast, neutrophils have evolved characteristic lobulated nuclei that increase their physical plasticity, enabling passage through narrow tissue spaces in their response to inflammation. Research on diverse cell types further demonstrates how induced nuclear deformations during cellular compression or stretch can modulate cellular function. Pathological examples of disturbed nuclear mechanics include the many diseases caused by mutations in the nuclear envelope proteins lamin A/C and associated proteins, as well as cancer cells that are often characterized by abnormal nuclear morphology. In this article, we will focus on determining the functional relationship between nuclear mechanics and cellular (dys-)function, describing the molecular changes associated with physiological and pathological examples, the resulting defects in nuclear mechanics, and the effects on cellular function. New insights into the close relationship between nuclear mechanics and cellular organization and function will yield a better understanding of normal biology and will offer new clues into therapeutic approaches to the various diseases associated with defective nuclear mechanics. PMID:23737203
Neurons of human nucleus accumbens
Directory of Open Access Journals (Sweden)
Sazdanović Maja
2011-01-01
Full Text Available Background/Aim. Nucleus accumbens is a part of the ventral striatum also known as a drug active brain region, especially related with drug addiction. The aim of the study was to investigate the Golgi morphology of the nucleus accumbens neurons. Methods. The study was performed on the frontal and sagittal sections of 15 human brains by the Golgi Kopsch method. We classified neurons in the human nucleus accumbens according to their morphology and size into four types: type I - fusiform neurons; type II - fusiform neurons with lateral dendrite, arising from a part of the cell body; type III - pyramidal-like neuron; type IV - multipolar neuron. The medium spiny neurons, which are mostly noted regarding to the drug addictive conditions of the brain, correspond to the type IV - multipolar neurons. Results. Two regions of human nucleus accumbens could be clearly recognized on Nissl and Golgi preparations each containing different predominant neuronal types. Central part of nucleus accumbens, core region, has a low density of impregnated neurons with predominant type III, pyramidal-like neurons, with spines on secondary branches and rare type IV, multipolar neurons. Contrary to the core, peripheral region, shell of nucleus, has a high density of impregnated neurons predominantly contained of type I and type IV - multipolar neurons, which all are rich in spines on secondary and tertiary dendritic branches. Conclusion. Our results indicate great morphological variability of human nucleus accumbens neurons. This requires further investigations and clarifying clinical significance of this important brain region.
Independent candidates in Mexico
Campos, Gonzalo Santiago
2014-01-01
In this paper we discuss the issue of independent candidates in Mexico, because through the so-called political reform of 2012 was incorporated in the Political Constitution of the Mexican United States the right of citizens to be registered as independent candidates. Also, in September 2013 was carried out a reform of Article 116 of the Political Constitution of the Mexican United States in order to allow independent candidates in each state of the Republic. However, prior to the constitutio...
Heavy flavors in nucleus-nucleus and proton-nucleus collisions
Directory of Open Access Journals (Sweden)
Nardi Marzia
2016-01-01
Full Text Available A multi-step setup for heavy-flavor studies in high-energy nucleus-nucleus (AA and proton-nucleus (pA collisions is presented. The propagation of the heavy quarks in the medium is described in a framework provided by the relativistic Langevin equation, here solved using weak-coupling transport coefficients. Successively, the heavy quarks hadronize in the medium. We compute the nuclear modification factor and the elliptic flow parameter of the final Dmesons both in AA and in pA collisions and compare our results to experimental data.
Heavy flavors in nucleus-nucleus and proton-nucleus collisions
Nardi, Marzia
2016-11-01
A multi-step setup for heavy-flavor studies in high-energy nucleus-nucleus (AA) and proton-nucleus (pA) collisions is presented. The propagation of the heavy quarks in the medium is described in a framework provided by the relativistic Langevin equation, here solved using weak-coupling transport coefficients. Successively, the heavy quarks hadronize in the medium. We compute the nuclear modification factor and the elliptic flow parameter of the final Dmesons both in AA and in pA collisions and compare our results to experimental data.
A scaling relation between proton-nucleus and nucleus-nucleus collisions
Basar, Gokce; Teaney, Derek
2014-01-01
It is recently discovered that at high multiplicy, the proton-nucleus ($pA$) collisions give rise to two particle correlations that are strikingly similar to those of nucleus-nucleus ($AA$) collisions at the same multiplicity, although the system size is smaller in $pA$. Using an independent cluster model and a simple conformal scaling argument, where the ratio of the mean free path to the system size stays constant at fixed multiplicity, we argue that flow in $pA$ emerges as a collective res...
Charged pion anisotropy in relativistic nucleus-nucleus collisions
Energy Technology Data Exchange (ETDEWEB)
Poitou, J.; L' Hote, D.; Cavata, C.; Babinet, R.; Demoulins, M.; Fanet, H.; Gosset, J.; Lemaire, M.C.; Le Merdy, A.; Lucas, B.; Terrien, Y.; Valette, O. (CEN Saclay, 91 - Gif-sur-Yvette (France)); Alard, J.P.; Augerat, J.; Bastid, N.; Charmensat, P.; Dupieux, P.; Fraysse, L.; Marroncle, J.; Montarou, G.; Parizet, M.J.; Rahmani, A. (LPC Clermont-Ferrand, 63 - Aubiere (France)); Brochard, F.; Gorodetzky, P.; Racca, C. (CRN, 67 - Strasbourg (France))
1992-01-27
The momentum distributions with respect to the reaction plane for charged pions emitted in Ne-nucleus and Ar-nucleus collisions have been measured with the 4{pi} detector Diogene at the Saturne synchrotron. The reaction plane is estimated from the baryon momenta, using a standard technique for flow analysis. The pions exhibit a non-zero flow. For asymmetric systems, there is a preferential emission in the direction of the lighter (projectile) nucleus. Such a behaviour contradicts the predictions of INC calculations and is underestimated by QMD calculations which include mean field effects. It can be interpreted with a simple geometrical model in terms of absorption by the spectator nuclear matter. (orig.).
Vessia, Giovanna; Parise, Mario
2013-04-01
the assumed depth of the sliding surface. Thus, it is of paramount relevance to correctly understand and describe the dynamic behavior of the lithologies affected by the earthquake. Accordingly, we put here in evidence some critical points in the application of the permanent displacement formulations by considering the case study of Santa Susana Mountains (California, USA) shaken by the Northridge earthquake in 1994. During this earthquake, a high number of registrations has been collected, whilst soon after a careful inventory of the mass movements triggered by the shaking has been produced, together with analysis of the related failure mechanisms. Hence, these data allow to perform a back analysis in order to verify the reliability of some numerical expressions, such as those proposed by Ambraseys and Menu (1988), Romeo (2000), and Jibson (2007), with respect to the possible dynamic behavior of the lithologies affected by landslides. In this sector of California, the following lithologies crop out, that were involved in shallow landslides: (1) Quaternay deposits; (2) Saugus Formation; (3) Towsley Formation; (4) Pico Formation; (5) Topanga Formation; (6) Modelo Formation; (7) Simi Conglomerate; (8) Santa Susana Formation; (9) Llajas and Chatsworth Formations. The surveys carried out after the Northridge earthquake (Harp and Jibson, 1995), and the analysis of landslide distribution (Parise and Jibson 2000) pointed out that the strongest formations with slopes higher than 50° mainly suffered toppling or fall failures: thus, our hazard maps based on permanent displacements did not take into account such range of slopes. Further, areas with slopes lower than 10° were not affected by relevant mass movements. Thus, a limited range of slopes (between 10° and 45°) was considered in the analyses, with depth of the sliding surface varying between 1 and 3 m, and using the resistance parameters of involved lithologies obtained from in situ and laboratory tests performed by
Energy Technology Data Exchange (ETDEWEB)
Kono, Y. [Central Research Institute of Electric Power Industry, Tokyo (Japan); Umezawa, T.; Murakoshi, M. [Bio-Environment Research, Co. Ltd., Chiba (Japan)
1998-11-10
A solution culture is experimented for the investigation of the effect of Ca/Al on the growth of Sugi (cryptomeria), Hinoki (cypress), and Sakura (cherry tree), and of CP (critical point for the emergence of the effect of Al). The solution culture is performed in water under specified conditions, the harvest is assortedly collected after 14 weeks, and is measured for dried weight. Sugi and Hinoki wither and die at an Al concentration of 5mM, but not at an Al concentration of 1mM or less. The concentration of Ca fails to exert any significant influence. At the Al concentration of 5mM, the trees are inhibited from growing in height or trunk diameter, but not affected by Ca concentration. The dried weight shares the same trend. The dried weight begins to decrease when the mol concentration ratio of Ca/Al or (K+Ca+Mg)/Al lowers to four or less. It may be concluded that conifers are inhibited from growing when the Al concentration is 2mM or higher, Ca/Al is one or lower, or (K+Ca+Mg)/Al is five or lower. If the point where growth is inhibited by 20% or 50% is chosen as the reference point, the CP of (K+Ca+Mg)/Al will be 1 or 0.5, respectively. This means that a different reference point yields a different value. There is an experimental outcome stating that growth is not affected even when this value is 0.4 in the case of soil exposed to artificial acid rain. 22 refs., 9 figs., 1 tab.
Quasielastic K-nucleus scattering
Pace, A D; Oset, E
1997-01-01
Quasielastic K^+ - nucleus scattering data at q=290, 390 and 480 MeV/c are analyzed in a finite nucleus continuum random phase approximation framework, using a density-dependent particle-hole interaction. The reaction mechanism is consistently treated according to Glauber theory, keeping up to two-step inelastic processes. A good description of the data is achieved, also providing a useful constraint on the strength of the effective particle-hole interaction in the scalar-isoscalar channel at intermediate momentum transfers. We find no evidence for the increase in the effective number of nucleons participating in the reaction which has been reported in the literature.
Rahman, M A; Haque, S
2003-01-01
Heavy ion-nucleus scattering is an excellent laboratory to probe high spin phenomena, exotic nuclei and for the analysis of various exit channels. The Strong Absorption Model or the generalized diffraction models, which are semi-classical in nature, have been employed in the description of various heavy ion-nucleus scattering phenomena with reasonable success. But one needs to treat the deflection function (scattering angles) quantum mechanically in the Wave Mechanical picture for the appropriate description of the heavy-ion nucleus scattering phenomena. We have brought the mathematics for the cross-section of the heavy-ion nucleus scattering to an analytic expression taking account of the deflection function (scattering angles) quantum mechanically. sup 9 Be, sup 1 sup 6 O, sup 2 sup 0 Ne and sup 3 sup 2 S heavy-ion beams elastic scattering from sup 2 sup 8 Si, sup 2 sup 4 Mg and sup 4 sup 0 Ca target nuclei at various projectile energies over the range 20-151 MeV have been analysed in terms of the 2-paramet...
Dimuon enhancement in nucleus-nucleus ultrarelativistic interactions
Energy Technology Data Exchange (ETDEWEB)
Bordalo, Paula; Abreu, M.C.; Alessandro, B.; Alexa, C.; Arnaldi, R.; Astruc, J.; Atayan, M.; Baglin, C.; Baldit, A.; Bedjidian, M.; Bellaiche, F.; Beole, S.; Bohrani, A.; Boldea, V.; Bussiere, A.; Capelli, L.; Caponi, V.; Casagrande, L.; Castor, J.; Chambon, T.; Chaurand, B.; Chevrot, I.; Cheynis, B.; Chiavassa, E.; Cicalo, C.; Comets, M.P.; Constans, N.; Constantinescu, S.; Contardo, D.; Cruz, J.; De Falco, A.; De Marco, N.; Dellacasa, G.; Devaux, A.; Dita, S.; Drapier, O.; Ducroux, L.; Espagnon, B.; Fargeix, J.; Ferreira, R.; Filippov, S.N.; Fleuret, F.; Force, P.; Gallio, M.; Gavrilov, Y.K.; Gerschel, C.; Giubellino, P.; Golubeva, M.B.; Gonin, M.; Gorodetzky, P.; Grigorian, A.A.; Grossiord, J.Y.; Guber, F.F.; Guichard, A.; Gulkanyan, H.; Hakobyan, R.; Haroutunian, R.; Idzik, M.; Jouan, D.; Karavitcheva, T.L.; Kluberg, L.; Kossakowski, R.; Kurepin, A.B.; Landau, G.; Le Bornec, Y.; Lourenco, C.; Luquin, L.; Macciotta, P.; Mac Cormick, M.; Mandry, R.; Marzari-Chiesa, A.; Masera, M.; Masoni, A.; Mehrabyan, S.; Monteno, M.; Mourgues, S.; Musso, A.; Ohlsson-Malek, F.; Petiau, P.; Piccotti, A.; Pizzi, J.R.; Prado da Silva, W.L.; Puddu, G.; Quintans, C.; Racca, C.; Ramello, L.; Ramos, S.; Rato-Mendes, P.; Riccati, L.; Romana, A.; Ropotar, I.; Saturnini, P.; Scomparin, E.; Serci, S.; Shahoyan, R.; Silva, S.; Sitta, M.; Soave, C.; Sonderegger, P.; Tarrago, X.; Topilskaya, N.S.; Usai, G.L.; Varela, J.; Vercellin, E.; Villatte, L
1999-12-27
The study of muon pairs in the mass region 1.5 < M{sub {mu}}{sub {mu}} < 2.5 GeV/c{sup 2} in 450 GeV/c p-A, 200 GeV/nucleon S-U and 158 GeV/nucleon Pb-Pb collisions is presented. In p-A interactions, the dimuon signal mass spectra are well described by a superposition of Drell-Yan and charmed meson semi-leptonic decay contributions, in agreement with previous experiments when considering a linear A dependence. In nucleus-nucleus reactions, taking only into account these two physical ingredients, a dimuon enhancement both with increasing A{center_dot}B and centrality is observed.
Azimuthal correlation and collective behavior in nucleus-nucleus collisions
Energy Technology Data Exchange (ETDEWEB)
Mali, P.; Mukhopadhyay, A., E-mail: amitabha-62@rediffmail.com; Sarkar, S. [University of North Bengal, Department of Physics (India); Singh, G. [SUNY at Fredonia, Department of Computer and Information Science (United States)
2015-03-15
Various flow effects of nuclear and hadronic origin are investigated in nucleus-nucleus collisions. Nuclear emulsion data collected from {sup 84}Kr + Ag/Br interaction at an incident energy of 1.52 GeV per nucleon and from {sup 28}Si + Ag/Br interaction at an incident energy of 14.5 GeV per nucleon are used in the investigation. The transverse momentum distribution and the flow angle analysis show that collective behavior, like a bounce-off effect of the projectile spectators and a sidesplash effect of the target spectators, are present in our event samples. From an azimuthal angle analysis of the data we also see a direct flow of the projectile fragments and of the produced charged particles. On the other hand, for both data samples the target fragments exhibit a reverse flow, while the projectile fragments exhibit an elliptic flow. Relevant flow parameters are measured.
Transverse Energy in nucleus-nucleus collisions: A review
Energy Technology Data Exchange (ETDEWEB)
Tincknell, M.
1988-11-15
The status of Transverse Energy (E/sub T/) in relativistic nucleus-nucleus collisions at the Brookhaven AGS and the CERN SPS is reviewed. The definition of E/sub T/ and its physical significance are discussed. The basic techniques and limitations of the experimental measurements are presented. The acceptances of the major experiments to be discussed are shown, along with remarks about their idiosyncrasies. The data demonstrate that the nuclear geometry of colliding spheres primarily determines the shapes of the observed spectra. Careful account of the acceptances is crucial to comparing and interpreting results. It is concluded that nuclear stopping power is high, and that the amount of energy deposited into the interaction volume is increasing with beam energy even at SPS energies. The energy densities believed to be obtained at the SPS are close to the critical values predicted for the onset of a quark-gluon plasma. 25 refs., 8 figs.
Primary and Presidential Candidates
DEFF Research Database (Denmark)
Goddard, Joseph
2012-01-01
This article looks at primary and presidential candidates in 2008 and 2012. Evidence suggests that voters are less influenced by candidates’ color, gender, or religious observation than previously. Conversely, markers of difference remain salient in the imaginations of pollsters and journalists...
Kalitvianski, V
2008-01-01
It is shown that electrostatic potential of atomic nucleus seen by a fast charged projectile at short distances is quite smeared due to nucleus motion around the atomic center of inertia. For example, the size of positive charge cloud in the Hydrogen ground state is much larger than the proper proton size. It is even bigger for the target atom in an excited state. Therefore the elastic scattering at large angles is generally weaker than the Rutherford one. In other words, the resulting elastic interaction with an atom at short distances is softer than the Colombian one due to a natural cutoff. In addition, the large angle scattering leads to the target atom excitations due to hitting the nucleus (inelastic processes). It is also shown that the Rutherford cross section is in fact the inclusive rather than the elastic one. These results are analogous to the QED ones. The difference and the value of the presented below non relativistic atomic calculations is in non perturbatively (exact) dressing that immediatel...
1989-05-01
pilot selection system and to best support up-front track selection for SUPT? Assumptions The USAF Trainer Masterplan does not include a plan to...replace the T-41 with a new flight screening aircraft. In addition, the Masterplan states that candidates will be track selected prior to entry into primary...training. (3:10) While the Masterplan is not a static document and aircraft procurement plans and/or the timing of track selection are subject to
Classifiers for centrality determination in proton-nucleus and nucleus-nucleus collisions
Altsybeev, Igor
2016-01-01
Centrality, as a geometrical property of the collision, is crucial for the physical interpretation of nucleus-nucleus and proton-nucleus experimental data. However, it cannot be directly accessed in event-by-event data analysis. Common methods for centrality estimation in A-A and p-A collisions usually rely on a single detector (either on the signal in zero-degree calorimeters or on the multiplicity in some semi-central rapidity range). In the present work, we made an attempt to develop an approach for centrality determination that is based on machine-learning techniques and utilizes information from several detector subsystems simultaneously. Different event classifiers are suggested and evaluated for their selectivity power in terms of the number of nucleons-participants and the impact parameter of the collision. Finer centrality resolution may allow to reduce impact from so-called volume fluctuations on physical observables being studied in heavy-ion experiments like ALICE at the LHC and fixed target exper...
Exclusive glueball production in high energy nucleus-nucleus collisions
Machado, M V T
2010-01-01
The cross sections for the glueball candidates production in quasi-real photon-photon collisions and on central diffraction processes, i.e. double Pomeron exchange, in heavy ion interactions at RHIC and LHC are computed. The rates for these distinct production channels are compared and they may be a fruitful approach to the investigation of glueballs.
An off-centered active galactic nucleus in NGC 3115
Menezes, R B; Ricci, T V
2014-01-01
NGC 3115 is an S0 galaxy that has always been considered to have a pure absorption-line spectrum. Some recent studies have detected a compact radio-emitting nucleus in this object, coinciding with the photometric center and with a candidate for the X-ray nucleus. This is evidence of the existence of a low-luminosity active galactic nucleus (AGN) in the galaxy, although no emission line has ever been observed. We report the detection of an emission-line spectrum of a type 1 AGN in NGC 3115, with an H$\\alpha$ luminosity of $L_{H\\alpha} = (4.2 \\pm 0.4) \\times 10^{37}$ erg s$^{-1}$. Our analysis revealed that this AGN is located at a projected distance of $\\sim 0.29" \\pm 0.05"$ (corresponding to $\\sim 14.3 \\pm 2.5$ pc) from the stellar bulge center, which is coincident with the kinematic center of this object's stellar velocity map. The black hole corresponding to the observed off-centered AGN may form a binary system with a black hole located at the stellar bulge center. However, it is also possible that the dis...
Study of the structure of borromean nucleus 17Ne
Institute of Scientific and Technical Information of China (English)
LU Fei; HUA Hui; YE Yan-Lin; LI Zhi-Huan; JIANG Dong-Xing; MA Li-Ying; GE Yu-Cheng; ZHENG Tao; SONG Yu-Shou; LI Xiang-Qing; Qureshi Faisal-Jamil
2009-01-01
The 17Ne nucleus is a possible candidate with a two-proton borromean halo structure. Since the theoretical model is difficult to handle the three-body system, it is difficult to determine the two-proton halo structure in 17Ne. In the present research, we try to study the breakup reaction of 17Ne. For the Borromean nuclei, one-proton knockout results in an unstable nucleus which is decaying further by proton emission. This process will result in an angular correlation between the direction of the aligned recoiling unstable nucleus and its decay products. The angular correlations can give us information about the configuration of the valence proton in the 17Ne. Furthermore, theoretical calculations indicate that the momentum distributions of 16F c.m are sensitive to the structure of the halo in 17Ne. Thus the measurement of momentum distributions of 16F c.m may also give us conclusive information on the structure of 17Ne. The present experiment has been done at IMP in Lanzhou using the radioactive beam 17Ne at 30.8 MeV/u on a 43mg/cm2 12C target. The data analysis is under procedure and the primary results are provided.
Pion production and absorption in relativistic nucleus-nucleus collisions
Energy Technology Data Exchange (ETDEWEB)
Senger, P. [GSI Planckstr.1, Darmstadt (Germany)
1993-12-31
In a relativistic nucleus-nucleus collision the projectile kinetic energy is not only converted into thermal and compressional energy of the nucleonic system, but also into internal excitation energy of the nucleons. At bombarding energies around 1 GeV/nucleon a substantial amount of baryonic resonances is produced which decay predominantly into pions. Thus the pion multiplicity, momentum and angular distributions provide information on the space time dynamics of the nuclear reaction system. In this paper the authors report on experiments which try to measure the `primordial` delta or pion abundancy. The idea is to compare the pion yields measured in a heavy and a light system: in the first case pion final-state interactions should happen much more frequently than in the second case. Both inclusive pion cross sections and pion multiplicities per participant nucleon are measured. In addition the authors study the pion emission pattern with respect to the reaction plane to sort out pions which are less affected by absorption and rescattering even in a heavy collision system.
Resonances in -light nucleus systems
Indian Academy of Sciences (India)
K P Khemchandani; N G Kelkar; M Nowakowski; B K Jain
2006-04-01
We locate resonances in -light nucleus elastic scattering using the time delay method. We solve few-body equations within the finite rank approximation in order to calculate the -matrices and hence the time delay for the - 3He and - 4He systems. We find a resonance very close to the threshold in - 3 He elastic scattering, at about 0.5 MeV above threshold with a width of ∼ 2 MeV. The calculations also hint at the presence of sub-threshold states in both the cases.
Turbulent mixing condensation nucleus counter
Mavliev, Rashid
The construction and operating principles of the Turbulent Mixing Condensation Nucleus Counter (TM CNC) are described. Estimations based on the semiempirical theory of turbulent jets and the classical theory of nucleation and growth show the possibility of detecting particles as small as 2.5 nm without the interference of homogeneous nucleation. This conclusion was confirmed experimentally during the International Workshop on Intercomparison of Condensation Nuclei and Aerosol Particle Counters (Vienna, Austria). Number concentration, measured by the Turbulent Mixing CNC and other participating instruments, is found to be essentially equal.
Vega, C; Abascal, J L F; Nezbeda, I
2006-07-21
The vapor-liquid equilibria of three recently proposed water models have been computed using Gibbs-Duhem simulations. These models are TIP4P/Ew, TIP4P/2005, and TIP4P/ice and can be considered as modified versions of the TIP4P model. By design TIP4P reproduces the vaporization enthalpy of water at room temperature, whereas TIP4P/Ew and TIP4P/2005 match the temperature of maximum density and TIP4P/ice the melting temperature of water. Recently, the melting point for each of these models has been computed, making it possible for the first time to compute the complete vapor-liquid equilibria curve from the triple point to the critical point. From the coexistence results at high temperature, it is possible to estimate the critical properties of these models. None of them is capable of reproducing accurately the critical pressure or the vapor pressures and densities. Additionally, in the cases of TIP4P and TIP4P/ice the critical temperatures are too low and too high, respectively, compared to the experimental value. However, models accounting for the density maximum of water, such as TIP4P/Ew and TIP4P/2005 provide a better estimate of the critical temperature. In particular, TIP4P/2005 provides a critical temperature just 7 K below the experimental result as well as an extraordinarily good description of the liquid densities from the triple point to the critical point. All TIP4P-like models present a ratio of the triple point temperature to the critical point temperature of about 0.39, compared with the experimental value of 0.42. As is the case for any effective potential neglecting many body forces, TIP4P/2005 fails in describing simultaneously the vapor and the liquid phases of water. However, it can be considered as one of the best effective potentials of water for describing condensed phases, both liquid and solid. In fact, it provides a completely coherent view of the phase diagram of water including fluid-solid, solid-solid, and vapor-liquid equilibria.
Percolation systems away from the critical point
Indian Academy of Sciences (India)
Deepak Dhar
2002-02-01
This article reviews some effects of disorder in percolation systems away from the critical density c. For densities below c, the statistics of large clusters deﬁnes the animals problem. Its relation to the directed animals problem and the Lee–Yang edge singularity problem is described. Rare compact clusters give rise to Grifﬁths singularities in the free energy of diluted ferromagnets, and lead to a very slow relaxation of magnetization. In biased diffusion on percolation clusters, trapping in dead-end branches leads to asymptotic drift velocity becoming zero for strong bias, and very slow relaxation of velocity near the critical bias ﬁeld.
Echo State Condition at the Critical Point
Directory of Open Access Journals (Sweden)
Norbert Michael Mayer
2016-12-01
Full Text Available Recurrent networks with transfer functions that fulfil the Lipschitz continuity with K = 1 may be echo state networks if certain limitations on the recurrent connectivity are applied. It has been shown that it is sufficient if the largest singular value of the recurrent connectivity is smaller than 1. The main achievement of this paper is a proof under which conditions the network is an echo state network even if the largest singular value is one. It turns out that in this critical case the exact shape of the transfer function plays a decisive role in determining whether the network still fulfills the echo state condition. In addition, several examples with one-neuron networks are outlined to illustrate effects of critical connectivity. Moreover, within the manuscript a mathematical definition for a critical echo state network is suggested.
Kondo Effect at a Quantum Critical Point
Ramazashvili, Revaz; Coleman, Piers
1998-03-01
The Kondo effect in a metal on the verge of a zero-temperature magnetic instability provides a fascinating example of interference between local and long-range correlations. (A. I. Larkin and V. I. Mel'nikov, Sov. Phys. JETP 34, 656 (1972)) (P. Coleman and A. M. Tsvelik, cond-mat/9707003) (A. Sengupta, cond-mat/9707316) We discuss possible consequences of this interference, including the breakdown of the Fermi liquid state.
Determination of Coil Inductances Cylindrical Iron Nucleus
Directory of Open Access Journals (Sweden)
Azeddine Mazouz
2014-03-01
Full Text Available The paper describes the investigation and development of a structure and performance characteristics of a coil iron nucleus cylindrical (C.I.N.C. The coil iron nucleus cylindrical is a nonlinear electro radio in which the moving of the nucleus in a sense or in other causes change in inductance and can reach extreme values at the superposition of nucleus and coil centers. The variation of the inductance and the degree of freedom of movement of the nucleus can lead to a device with electromechanical conversion The aim of this paper is the determination and visualization of self inductance and mutual of the (C.I.N.C based on geometric dimensions and the displacement of the nucleus.
Directory of Open Access Journals (Sweden)
Lokman Tsui
2017-06-01
Full Text Available The study of continuous phase transitions triggered by spontaneous symmetry breaking has brought revolutionary ideas to physics. Recently, through the discovery of symmetry protected topological phases, it is realized that continuous quantum phase transition can also occur between states with the same symmetry but different topology. Here we study a specific class of such phase transitions in 1+1 dimensions – the phase transition between bosonic topological phases protected by Zn×Zn. We find in all cases the critical point possesses two gap opening relevant operators: one leads to a Landau-forbidden symmetry breaking phase transition and the other to the topological phase transition. We also obtained a constraint on the central charge for general phase transitions between symmetry protected bosonic topological phases in 1+1D.
Ni, Yicun; Skinner, J. L.
2016-06-01
Supercooled water exhibits many thermodynamic anomalies, and several scenarios have been proposed to interpret them, among which the liquid-liquid critical point (LLCP) hypothesis is the most commonly discussed. We investigated Widom lines and the LLCP of deeply supercooled water, by using molecular dynamics simulation with a newly reparameterized water model that explicitly includes three-body interactions. Seven isobars are studied from ambient pressure to 2.5 kbar, and Widom lines are identified by calculating maxima in the coefficient of thermal expansion and the isothermal compressibility (both with respect to temperature). From these data we estimate that the LLCP of the new water model is at 180 K and 2.1 kbar. The oxygen radial distribution function is calculated along the 2 kbar isobar. It shows a steep change in the height of its second peak between 180 and 185 K, which indicates a transition between the high-density liquid and low-density liquid phases and which is consistent with the ascribed location of the critical point. The good agreement of the height of the second peak of the radial distribution function between simulation and experiment at 1 bar, as a function of temperature, supports the validity of the model. The location of the LLCP within the model is close to the kink in the experimental homogeneous nucleation line. We use existing experimental data to argue that the experimental LLCP is at 168 K and 1.95 kbar and speculate how this LLCP and its Widom line might be responsible for the kink in the homogeneous nucleation line.
Ni, Yicun; Skinner, J L
2016-06-07
Supercooled water exhibits many thermodynamic anomalies, and several scenarios have been proposed to interpret them, among which the liquid-liquid critical point (LLCP) hypothesis is the most commonly discussed. We investigated Widom lines and the LLCP of deeply supercooled water, by using molecular dynamics simulation with a newly reparameterized water model that explicitly includes three-body interactions. Seven isobars are studied from ambient pressure to 2.5 kbar, and Widom lines are identified by calculating maxima in the coefficient of thermal expansion and the isothermal compressibility (both with respect to temperature). From these data we estimate that the LLCP of the new water model is at 180 K and 2.1 kbar. The oxygen radial distribution function is calculated along the 2 kbar isobar. It shows a steep change in the height of its second peak between 180 and 185 K, which indicates a transition between the high-density liquid and low-density liquid phases and which is consistent with the ascribed location of the critical point. The good agreement of the height of the second peak of the radial distribution function between simulation and experiment at 1 bar, as a function of temperature, supports the validity of the model. The location of the LLCP within the model is close to the kink in the experimental homogeneous nucleation line. We use existing experimental data to argue that the experimental LLCP is at 168 K and 1.95 kbar and speculate how this LLCP and its Widom line might be responsible for the kink in the homogeneous nucleation line.
Energy Technology Data Exchange (ETDEWEB)
Baltz, E.
2004-12-03
It is now widely accepted that most of mass-energy in the universe is unobserved except by its gravitational effects. Baryons make only about 4% of the total, with ''dark matter'' making up about 23% and the ''dark energy'' responsible for the accelerated expansion of the universe making up the remainder. We focus on the dark matter, which is the primary constituent of galaxies. We outline the observed properties of this material, enumerating some candidates covering 90 orders of magnitude in mass. Finally, we argue that the weak scale (100 GeV) is relevant to new physics, including the dark matter problem.
Projections from the central amygdaloid nucleus to the precuneiform nucleus in the mouse.
Liang, Huazheng; Watson, Charles; Paxinos, George
2015-01-01
The mouse precuneiform nucleus has been proposed as the midbrain locomotion center, a function ascribed to its caudal neighbor, cuneiform nucleus, in the rat, cat and other species. The present study investigated the projections from the central amygdaloid nucleus to the precuneiform nucleus in the mouse using retrograde tracer injections (fluoro-gold) into the precuneiform nucleus and anterograde tracer injections (biotinylated dextran amine) into the central amygdaloid nucleus. The entire central amygdaloid nucleus except the rostral pole had retrogradely labeled neurons, especially in the middle portion where labeled neurons were densely packed. Anterogradely labeled amygdaloid fibers approached the precuneiform nucleus from the area ventrolateral to it and terminated in the entire precuneiform nucleus. Labeled fibers were also found in laminae 5 and 6 in the upper cervical cord on the ipsilateral side. The present study is the first demonstration of projections from the central amygdaloid nucleus to the precuneiform nucleus. This projection may underpin the role of the precuneiform nucleus in the modulation of the cardiovascular activity.
Crossing axons in the third nerve nucleus.
Bienfang, D C
1975-12-01
The research presented in this paper studied the pathway taken by the crossed fibers of the third nerve nucleus in an animal whose nucleus has been well mapped and found to correlate well with higher mammals and man. Autoradiography using tritiated amino acid labeled the cell bodies an axons of the left side of the oculomotor nucleus of the cat. Axons so labeled could be seen emerging from the ventral portion of the left nucleus through the median longitudinal fasciculus (mlf) to join the left oculomotor nerve. Labeled axons were also seen to emerge from the medial border of the caudal left nucleus, cross the midline, and pass through the right nucleus and the right mlf to join the right oculomotor nerve. These latter axons must be the crossed axons of the superior rectus and levator palpebrae subnuclei. Since the path of these crossed axons is through the caudal portion of the nucleus of the opposite side, the destruction of one lateral half of the oculomotor nucleus would result in a bilateral palsy of the crossed subnuclei. Bilateral palsy of the superior rectus and bilateral assymetrical palsy of the levator palpebrae muscles would result.
Determining the meson-nucleus potential - on the way to mesic states
Energy Technology Data Exchange (ETDEWEB)
Metag, Volker, E-mail: volker.metag@exp2.physik.uni-giessen.de [Universität Giessen, II. Physikalisches Institut (Germany)
2015-08-15
Experimental approaches to determine the real and imaginary part of the meson-nucleus potential are described. The experiments have been performed with the Crystal Barrel/TAPS detector at the electron accelerator ELSA (Bonn) and the Crystal Ball/TAPS detector at MAMI (Mainz). Measuring the transparency ratio as well as the excitation function and momentum distribution for photo production of ω and η′ mesons, the imaginary part of the η′-nucleus potential is found to be smaller than the real part. In case of the ω meson the opposite is observed. This makes the η′ meson a good candidate for the search for meson-nucleus bound states while no resolved ω mesic states can be expected. The results are discussed and compared to theoretical predictions. An outlook on future experiments is given.
Directory of Open Access Journals (Sweden)
Marcos David Ferreira
2006-12-01
Full Text Available A produção citrícola brasileira é uma das mais importantes para a fruticultura do País, comercializando principalmente para o mercado externo. O impacto mecânico é um fator importante a ser minimizado, visando a reduzir as perdas pós-colheita, diminuindo conseqüentemente os prejuízos decorrentes do manejo inadequado. Neste trabalho, foram avaliados os pontos críticos e o nível de impacto em que os frutos são submetidos em equipamentos nacionais e importados, utilizados para beneficiamento e classificação de citros. Utilizou-se da esfera instrumentada (70 mm (Techmark, Inc., Lansing, EUA, com registrador de aceleração, para a avaliação da magnitude de impactos (G, m/s² nos pontos de transferência das linhas de classificação de laranjas e lima-ácida Tahiti. A esfera instrumentada foi colocada, juntamente com os frutos, na etapa de recebimento das linhas que funcionavam em seu volume padrão diário, e seguiu o fluxo dos frutos até a etapa de classificação. Os resultados demonstraram que os maiores impactos foram causados por quedas em pontos de transferência com superfícies rígidas, sendo os maiores valores encontrados na etapa de recebimento e na entrada dos frutos em "containers" utilizados para o armazenamento. Observou-se, também, que a magnitude de impacto foi significativamente reduzida quando se utilizaram superfícies recobertas com acolchoados nos diversos pontos de transferência.The Brazilian citrus chain is one of the leaders on the export process. Mechanical injury is one important factor that should be minimized on this chain, in order to reduce and decrease postharvest losses due to no appropriate handling. On this work, critical points of impact were evaluated in imported and national equipments used for sorting citrus. The instrumented sphere, 70mm, (Techmark Inc., Lansing, EUA was used for this evaluation, mesuring the magnitude of impact (G, m/s² on transfer points in sorting lines of oranges and
Multiple chiral doublet candidate nucleus $^{105}$Rh in a relativistic mean-field approach
Li, Jian; Meng, J; 10.1103/PhysRevC.83.037301
2011-01-01
Following the reports of two pairs of chiral doublet bands observed in $^{105}$Rh, the adiabatic and configuration-fixed constrained triaxial relativistic mean-field (RMF) calculations are performed to investigate their triaxial deformations with the corresponding configuration and the possible multiple chiral doublet (M$\\chi$D) phenomenon. The existence of M$\\chi$D phenomenon in $^{105}$Rh is highly expected.
Music and the nucleus accumbens.
Mavridis, Ioannis N
2015-03-01
Music is a universal feature of human societies over time, mainly because it allows expression and regulation of strong emotions, thus influencing moods and evoking pleasure. The nucleus accumbens (NA), the most important pleasure center of the human brain (dominates the reward system), is the 'king of neurosciences' and dopamine (DA) can be rightfully considered as its 'crown' due to the fundamental role that this neurotransmitter plays in the brain's reward system. Purpose of this article was to review the existing literature regarding the relation between music and the NA. Studies have shown that reward value for music can be coded by activity levels in the NA, whose functional connectivity with auditory and frontal areas increases as a function of increasing musical reward. Listening to music strongly modulates activity in a network of mesolimbic structures involved in reward processing including the NA. The functional connectivity between brain regions mediating reward, autonomic and cognitive processing provides insight into understanding why listening to music is one of the most rewarding and pleasurable human experiences. Musical stimuli can significantly increase extracellular DA levels in the NA. NA DA and serotonin were found significantly higher in animals exposed to music. Finally, passive listening to unfamiliar although liked music showed activations in the NA.
Saini, Anoop Kumar; Sharma, Vinay; Mathur, Pradeep; Shaikh, Mobin M.
2016-01-01
The morphology of nucleus and nucleolus is powerful indicator of physiological and pathological conditions. The specific staining of nucleolus recently gained much attention due to the limited and expensive availability of the only existing stain “SYTO RNA-Select”. Here, a new multifunctional salen type ligand (L1) and its Al3+ complex (1) are designed and synthesized. L1 acts as a chemosensor for Al3+ whereas 1 demonstrates specific staining of nucleus as well as nucleoli. The binding of 1 with nucleic acid is probed by DNase and RNase digestion in stained cells. 1 shows an excellent photostability, which is a limitation for existing nucleus stains during long term observations. 1 is assumed to be a potential candidate as an alternative to expensive commercial dyes for nucleus and nucleoli staining. PMID:27721431
Energy Technology Data Exchange (ETDEWEB)
Jiang Shuai; Xing Hui; Xuan Guofang; Wang Cao; Ren Zhi; Dai Jianhui; Xu Zhu' an; Cao Guanghan [Department of Physics, Zhejiang University, Hangzhou 310027 (China); Feng, Chunmu, E-mail: ghcao@zju.edu.c [Test and Analysis Center, Zhejiang University, Hangzhou 310027 (China)
2009-09-23
We report bulk superconductivity induced by an isovalent doping of phosphorus in BaFe{sub 2}(As{sub 1-x}P{sub x}){sub 2}. The P-for-As substitution results in shrinkage of the lattice, especially for the FeAs block layers. The resistivity anomaly associated with the spin-density-wave (SDW) transition in the undoped compound is gradually suppressed by the P doping. Superconductivity with a maximum T{sub c} of 30 K emerges at x = 0.32, coinciding with a magnetic quantum critical point (QCP) which is shown by the disappearance of SDW order and the linear temperature-dependent resistivity in the normal state. The T{sub c} values were found to decrease with further P doping and no superconductivity was observed down to 2 K for x>=0.77. The appearance of superconductivity in the vicinity of QCP hints at the superconductivity mechanism in iron-based arsenides. (fast track communication)
Hammerath, F.; Bonfà, P.; Sanna, S.; Prando, G.; De Renzi, R.; Kobayashi, Y.; Sato, M.; Carretta, P.
2014-04-01
A superconducting-to-magnetic transition is reported for LaFeAsO0.89F0.11 where a per-thousand amount of Mn impurities is dispersed. By employing local spectroscopic techniques like muon spin rotation (μSR) and nuclear quadrupole resonance (NQR) on compounds with Mn contents ranging from x =0.025% to x =0.75%, we find that the electronic properties are extremely sensitive to the Mn impurities. In fact, a small amount of Mn as low as 0.2% suppresses superconductivity completely. Static magnetism, involving the FeAs planes, is observed to arise for x >0.1% and becomes further enhanced upon increasing Mn substitution. Also a progressive increase of low-energy spin fluctuations, leading to an enhancement of the NQR spin-lattice relaxation rate T1-1, is observed upon Mn substitution. The analysis of T1-1 for the sample closest to the crossover between superconductivity and magnetism (x =0.2%) points toward the presence of an antiferromagnetic quantum critical point around that doping level.
Zséli, Györgyi; Vida, Barbara; Martinez, Anais; Lechan, Ronald M.; Khan, Arshad M.; Fekete, Csaba
2017-01-01
We hypothesized that brain regions showing neuronal activation after refeeding comprise major nodes in a satiety network, and tested this hypothesis with two sets of experiments. Detailed c-Fos mapping comparing fasted and refed rats was performed to identify candidate nodes of the satiety network. In addition to well-known feeding-related brain regions such as the arcuate, dorsomedial and paraventricular hypothalamic nuclei, lateral hypothalamic area, parabrachial nucleus (PB), nucleus of solitary tract and central amygdalar nucleus; other refeeding activated regions were also identified, such as the parastrial and parasubthalamic nuclei. To begin understanding the connectivity of the satiety network, the interconnectivity of PB with other refeeding-activated neuronal groups was studied following administration of anterograde or retrograde tracers into the PB. After allowing for tracer transport time, the animals were fasted and then refed before sacrifice. Refeeding-activated neurons that project to the PB were found in the agranular insular area; bed nuclei of terminal stria; anterior hypothalamic area; arcuate, paraventricular and dorsomedial hypothalamic nuclei; lateral hypothalamic area; parasubthalamic nucleus; central amygdalar nucleus; area postrema; and nucleus of solitary tract. Axons originating from PB were observed to closely associate with refeeding-activated neurons in the agranular insular area; bed nuclei of terminal stria; anterior hypothalamus; paraventricular, arcuate and dorsomedial hypothalamic nuclei; lateral hypothalamic area; central amygdalar nucleus; parasubthalamic nucleus; ventral posterior thalamic nucleus; area postrema; and nucleus of solitary tract. These data indicate that the PB has bidirectional connections with most refeeding-activated neuronal groups, suggesting that short loop feedback circuits exist in this satiety network. PMID:26918800
Evaluation of novel injectable hydrogels for nucleus pulposus replacement.
Vernengo, J; Fussell, G W; Smith, N G; Lowman, A M
2008-01-01
Branched copolymers composed of poly(N-isopropylacrylamide) (PNIPAAm) and poly(ethylene glycol) (PEG) are being investigated as an in situ forming replacement for the nucleus pulposus of the intervertebral disc. A family of copolymers was synthesized by varying the molecular weight of the PEG blocks and molar ratio of NIPAAm monomer units to PEG branches. Gel swelling, dissolution, and compressive mechanical properties were characterized over 90 days and stress relaxation behavior over 30 days immersion in vitro. It was found that the NIPAAm to PEG molar ratio did not affect the equilibrium swelling and compressive mechanical properties. However, gel elasticity exhibited a dependency on both the PEG block molecular weight and content. The equilibrium gel water content increased and compressive modulus decreased with increasing PEG block size. While all of the branched copolymers showed significant increases in stress relaxation time constant compared to the homopolymer (p < 0.05), the high PEG content PNIPAAm-PEG (4600 and 8000 g/mol) exhibited the maximum elasticity. Because of its high water content, requisite stiffness and high elastic response, PNIPAAm-PEG (4600 g/mol) will be further evaluated as a candidate material for nucleus pulposus replacement.
Study of Hadron Production in Hadron-Nucleus and Nucleus-Nucleus Collisions at the CERN SPS
Selyuzhenkov, I; Klochkov, V; Kowalski, S; Kaptur, E A; Kowalik, K L; Dominik, W M; Krasnoperov, A; Feofilov, G; Vinogradov, L; Kovalenko, V; Johnson, S R; Mills, G B; Planeta, R J; Rubbia, A; Marton, K; Messerly, B A; Puzovic, J; Bogomilov, M V; Bravar, A; Sgalaberna, D; Renfordt, R A E; Deveaux, M; Engel, R R; Grzeszczuk, A; Davis, N; Kuich, M; Lyubushkin, V; Kondratev, V; Kadija, K; Diakonos, F; Slodkowski, M A; Rauch, W H; Pistillo, C; Laszlo, A; Nakadaira, T; Hasegawa, T; Sadovskiy, A; Morozov, S; Petukhov, O; Szuba, M K; Mathes, H; Herve, A E; Roehrich, D; Marino, A D; Grebieszkow, K; Wlodarczyk, Z; Rybczynski, M A; Wojtaszek-szwarc, A; Nirkko, M C; Sakashita, K; Golubeva, M; Kurepin, A; Manic, D; Kolev, D I; Kisiel, J E; Rondio, E; Larsen, D T; Czopowicz, T R; Seyboth, P; Turko, L; Guber, F; Marin, V; Busygina, O; Taranenko, A; Cirkovic, M; Gazdzicki, M; Roth, M A; Pulawski, S M; Aduszkiewicz, A M; Bunyatov, S; Vechernin, V; Nagai, Y; Anticic, T; Dynowski, K M; Mackowiak-pawlowska, M K; Stefanek, G; Pavin, M; Fodor, Z P; Nishikawa, K; Tada, M; Kobayashi, T; Blondel, A P P; Damyanova, A; Stroebele, H W; Posiadala, M Z; Kolesnikov, V; Andronov, E; Zimmerman, E D; Antoniou, N; Majka, Z; Di luise, S; Veberic, D; Dumarchez, J; Naskret, M; Ivashkin, A; Tsenov, R V; Koziel, M G; Schmidt, K J; Melkumov, G; Popov, B; Panagiotou, A; Richter-was, E M; Ereditato, A; Paolone, V; Unger, M T; Wilczek, A G; Stepaniak, J M; Matulewicz, T N; Seryakov, A; Susa, T; Staszel, P P; Brzychczyk, J; Maksiak, B; Tefelski, D B; Kucewicz, W; Dorosz, P A
2007-01-01
The NA61/SHINE (SHINE = SPS Heavy Ion and Neutrino Experiment) experiment is a large acceptance hadron spectrometer at the CERN SPS for the study of the hadronic final states produced in interactions of various beam particles (pions, protons, C, S and In) with a variety of fixed targets at the SPS energies. The main components of the current detector were constructed and used by the NA49 experiment. The physics program of NA61/SHINE consists of three main subjects. In the first stage of data taking (2007-2009) measurements of hadron production in hadron-nucleus interactions needed for neutrino (T2K) and cosmic-ray (Pierre Auger and KASCADE) experiments will be performed. In the second stage (2009-2011) hadron production in proton-proton and proton-nucleus interactions needed as reference data for a better understanding of nucleus-nucleus reactions will be studied. In the third stage (2009-2013) energy dependence of hadron production properties will be measured in nucleus-nucleus collisions as well as in p+p a...
Large philipsite crystal as ferromanganese nodule nucleus
Digital Repository Service at National Institute of Oceanography (India)
Ghosh, A.K.; Mukhopadhyay, R.
We report here the occurrence of, to date, the largest (21 x 10 x 8 mm) phillipsite crystal forming the nucleus of a diagenetically formed ferromanganese nodule from the Central Indian Ocean Basin (CIOB). Assuming an average rate of ferromanganese...
Medium effect in high density region probed by nucleus-nucleus elastic scattering
Furumoto, T; Yamamoto, Y
2014-01-01
We investigate the sensitivity of the medium effect in the high density region on the nucleus-nucleus elastic scattering in the framework of the double-folding (DF) model with the complex $G$-matrix interaction. First, the evaluating position of the local density, which is an ambiguity of the DF model, is investigated. However, the effect has a minor role to the nucleus-nucleus system. Next, the medium effect including three-body-force (TBF) effect is investigated with two methods. In the both methods, the medium effect is clearly seen on the potential and the elastic cross section, but not on the total reaction cross section. Finally, we make clear the crucial role of the TBF effect up to $k_F =$ 1.6 fm$^{-1}$ in the nucleus-nucleus elastic scattering.
Transport calculations of antiproton-nucleus interactions
Larionov, A B; Pshenichnov, I A; Satarov, L M; Greiner, W
2010-01-01
The Giessen Boltzmann-Uehling-Uhlenbeck transport model is extended and applied to the antiproton-nucleus interactions in a wide beam momentum range. The model calculations are compared with the experimental data on $\\bar p$-absorption cross sections on nuclei with an emphasis on extraction of the real part of an antiproton optical potential. The possibility of the cold compression of a nucleus by an antiproton in-flight is also considered.
Commissural axons of the mouse cochlear nucleus.
Brown, M Christian; Drottar, Marie; Benson, Thane E; Darrow, Keith
2013-05-01
The axons of commissural neurons that project from one cochlear nucleus to the other were studied after labeling with anterograde tracer. Injections were made into the dorsal subdivision of the cochlear nucleus in order to restrict labeling only to the group of commissural neurons that gave off collaterals to, or were located in, this subdivision. The number of labeled commissural axons in each injection was correlated with the number of labeled radiate multipolar neurons, suggesting radiate neurons as the predominant origin of the axons. The radiate commissural axons are thick and myelinated, and they exit the dorsal acoustic stria of the injected cochlear nucleus to cross the brainstem in the dorsal half, near the crossing position of the olivocochlear bundle. They enter the opposite cochlear nucleus via the dorsal and ventral acoustic stria and at its medial border. Reconstructions of single axons demonstrate that terminations are mostly in the core and typically within a single subdivision of the cochlear nucleus. Extents of termination range from narrow to broad along both the dorsoventral (i.e., tonotopic) and the rostrocaudal dimensions. In the electron microscope, labeled swellings form synapses that are symmetric (in that there is little postsynaptic density), a characteristic of inhibitory synapses. Our labeled axons do not appear to include excitatory commissural axons that end in edge regions of the nucleus. Radiate commissural axons could mediate the broadband inhibition observed in responses to contralateral sound, and they may balance input from the two ears with a quick time course.
BFKL Pomeron calculus: solution to equations for nucleus-nucleus scattering in the saturation domain
Contreras, Carlos; Meneses, Rodrigo
2013-01-01
In this paper we solve the equation for nucleus-nucleus scattering in the BFKL Pomeron calculus, suggested by Braun. We find these solutions analytically at high energies as well as numerically in the entire region of energies inside the saturation region. The semi-classical approximation is used to select out the infinite set of the parasite solutions. The nucleus-nucleus cross sections at high energy are estimated and compared with the Glauber-Gribov approach. It turns out that the exact formula gives the estimates that are very close to the ones based on Glauber-Gribov formula which is important for the practical applications
Onset of Deconfinement in Nucleus-Nucleus Collisions - Past, Present and Future -
Gazdzicki, Marek
2007-01-01
In 2007 Mark I. Gorenstein celebrated his 60th birthday. This report is dedicated to Mark and it sketches the results obtained during the past ten years of our collaboration and friendship. They concern search for and study of the onset of deconfinement in high energy nucleus-nucleus collisions.
High density QCD and nucleus-nucleus scattering deeply in the saturation region
Kormilitzin, Andrey; Levin, Eugene; Miller, Jeremy S.
2011-06-01
In this paper we solve the equations that describe nucleus-nucleus scattering, in high density QCD, in the framework of the BFKL Pomeron Calculus. We found that (i) the contribution of short distances to the opacity for nucleus-nucleus scattering dies at high energies, (ii) the opacity tends to unity at high energy, and (iii) the main contribution that survives comes from soft (long distance) processes for large values of the impact parameter. The corrections to the opacity Ω(Y,b)=1 were calculated and it turns out that they have a completely different form, namely ( 1-Ω→exp(-Const √{Y} )) than the opacity that stems from the Balitsky-Kovchegov equation, which is ( 1-Ω→exp(-Const Y)). We reproduce the formula for the nucleus-nucleus cross section that is commonly used in the description of nucleus-nucleus scattering, and there is no reason why it should be correct in the Glauber-Gribov approach.
Control of nucleus positioning in mouse oocytes.
Almonacid, Maria; Terret, Marie-Emilie; Verlhac, Marie-Hélène
2017-08-12
The position of the nucleus in a cell can instruct morphogenesis in some cases, conveying spatial and temporal information and abnormal nuclear positioning can lead to disease. In oocytes from worm, sea urchin, frog and some fish, nucleus position regulates embryo development, it marks the animal pole and in Drosophila it defines the future dorso-ventral axis of the embryo and of the adult body plan. However, in mammals, the oocyte nucleus is centrally located and does not instruct any future embryo axis. Yet an off-center nucleus correlates with poor outcome for mouse and human oocyte development. This is surprising since oocytes further undergo two extremely asymmetric divisions in terms of the size of the daughter cells (enabling polar body extrusion), requiring an off-centering of their chromosomes. In this review we address not only the bio-physical mechanism controlling nucleus positioning via an actin-mediated pressure gradient, but we also speculate on potential biological relevance of nuclear positioning in mammalian oocytes and early embryos. Copyright © 2017. Published by Elsevier Ltd.
76 FR 4896 - Call for Candidates
2011-01-27
... From the Federal Register Online via the Government Publishing Office FEDERAL ACCOUNTING STANDARDS ADVISORY BOARD Call for Candidates AGENCY: Federal Accounting Standards Advisory Board. ACTION: Notice... Federal Accounting Standards Advisory Board (FASAB) is currently seeking candidates (candidates must...
Organisation of the human dorsomedial hypothalamic nucleus.
Koutcherov, Yuri; Mai, Juergen K; Ashwell, Ken W; Paxinos, George
2004-01-19
This study used acetylcholinesterase (AChE) histochemistry to reveal the organization of the dorsomedial hypothalamic nucleus (DM) in the human. Topographically, the human DM is similar to DM in the monkey and rat. It is wedged between the paraventricular nucleus, dorsally, and the ventromedial nucleus, ventrally. Laterally, DM borders the lateral hypothalamic area while medially it approaches the 3rd ventricle. The AChE staining distinguished two subcompartments of the human DM: the larger diffuse and the smaller compact DM. The subcompartmental organization of the human DM appears homologous to that found in the monkey and less complex than that reported in rats. Understanding of the organization of DM creates meaningful anatomical reference for physiological and pharmacological studies in the human hypothalamus.
The nucleus: a black box being opened.
van Driel, R; Humbel, B; de Jong, L
1991-12-01
Until recently our knowledge about the structural and functional organization of the cell nucleus was very limited. Recent technical developments in the field of ultrastructural analysis, combined with ongoing research on the properties of the nuclear matrix, give new insight into how the nucleus is structured. Two types of observations shape our ideas about nuclear organization. First, most nuclear functions (replication, transcription, RNA processing, and RNA transport) are highly localized within the nucleus, rather than diffusely distributed. Moreover, they are associated with the nuclear matrix. Second, chromatin is organized in discrete loops, bordered by nuclear matrix attachment sequences (MARs). Each loop may contain one or several genes. The arrangement of chromatin in loops has profound consequences for the regulation of gene expression.
Dirac Phenomenology and Hyperon-Nucleus Interactions
J., MARES; B. K., JENNINGS; E. D., COOPER; Triumf, 4004 Wesbrook Mall; Department of Physics, University College of the Fraser Valley
1995-01-01
We discuss various aspects of hyperon-nucleus interactions in the relativistic mean field theory. First, characteristics of Λ, Σ and Ξ hypernuclei, as well as multi-strange baryonic objects, are investigated. The spin-orbit splittings and magnetic moments are shown to be very sensitive to the value of the tensor coupling f_. Second, optical potentials for Λ and Σ scattering off nuclei are developed based on a global nucleon-nucleus Dirac optical potential and SU(3) symmetry. The tensor coupli...
PSN J19065165-6142163 a supernova candidate by TAROT in IC 4815
Klotz, A.
2012-06-01
From images taken on 2012 June 20.36 with the TAROT La Silla telescope A. Klotz report the discovery of a supernova candidate located at R.A. = 19h06m51.65s, Decl. = -61o42'16.3" (equinox 2000.0), which is offset of 6" E and 12" S from the nucleus of IC 4815. The image was R filtered and magnitude was R~19. The presence of the candidate is confirmed on two images taken on 2012 June 26.34 with the same telescope.
PSN J17484870-6042193 a supernova candidate by TAROT in ESO 139-28
Klotz, A.
2012-06-01
From images taken on 2012 June 21.27 with the TAROT La Silla telescope we report the discovery of a supernova candidate located at R.A. = 17h48m48.7s, Decl. = -60o42'19.3" (equinox 2000.0), which is offset of 17" W and 4" N from the nucleus of ESO 139-28. The image was R filtered and magnitude was R=14.7. The presence of the candidate is confirmed on images taken on 2012 June 24.27 with the same telescope.
Nucleus-Nucleus Potential at Near-Barrier Energies from Self Consistent Calculations
Skalski, J
2003-01-01
We determine the static nucleus-nucleus potential from Hartree-Fock (HF) calculations with the Skyrme interaction. To this aim, HF equations are solved on a spatial mesh, with the initial configuration consisting of target and projectile positioned at various relative distances. For a number of reaction partners, the calculated barrier heights reasonably well compare with those extracted from the measured fusion and capture cross sections. At smaller target-projectile distances, our results show the intrinsic barriers to heavy compound nucleus formation. We speculate on their possible connection with the fusion hindrance observed for large Z sub T Z sub P.
Inner Structure of Boiling Nucleus and Interfacial Energy Between Nucleus and Bulk Liquid
Institute of Scientific and Technical Information of China (English)
WANG Xiao-Dong; TIAN Yong; PENG Xiao-Feng; WANG Bu-Xuan
2004-01-01
@@ A model of two-region structure of a nucleus is proposed to describe nucleus evolution. The interfacial tension between bulk liquid phase and nucleus is dependent on the density gradient in the transition region and varies with the structure change of the transition region. With the interfacial tension calculated using this model, the predicted nucleation rate is very close to the experimental measurement. Furthermore, this model and associated analysis provide solid theoretical evidence to clarify the definition of nucleation rate and understand the nucleation phenomenon with insight into the physical nature.
Lattice investigation of tetraquark candidates
Energy Technology Data Exchange (ETDEWEB)
Berlin, Joshua; Wagner, Marc [Goethe-Universitaet Frankfurt am Main, Institut fuer Theoretische Physik (Germany); Abdel-Rehim, Abdou; Alexandrou, Constantia; Gravina, Mario; Koutsou, Giannis [Department of Physics, University of Cyprus, Nicosia (Cyprus); Computation-based Science and Technology Research Center, Cyprus Institute, Nicosia (Cyprus); Dalla Brida, Mattia [School of Mathematics, Trinity College Dublin (Ireland)
2014-07-01
We present the status of an ongoing long-term lattice QCD project concerned with the study of light and heavy tetraquark candidates, using a variety of different creation operators. The computation of disconnected diagrams, which is technically challenging, is discussed in detail.
Candidate Prediction Models and Methods
DEFF Research Database (Denmark)
Nielsen, Henrik Aalborg; Nielsen, Torben Skov; Madsen, Henrik
2005-01-01
This document lists candidate prediction models for Work Package 3 (WP3) of the PSO-project called ``Intelligent wind power prediction systems'' (FU4101). The main focus is on the models transforming numerical weather predictions into predictions of power production. The document also outlines...
Candidate gene prioritization with Endeavour.
Tranchevent, Léon-Charles; Ardeshirdavani, Amin; ElShal, Sarah; Alcaide, Daniel; Aerts, Jan; Auboeuf, Didier; Moreau, Yves
2016-07-08
Genomic studies and high-throughput experiments often produce large lists of candidate genes among which only a small fraction are truly relevant to the disease, phenotype or biological process of interest. Gene prioritization tackles this problem by ranking candidate genes by profiling candidates across multiple genomic data sources and integrating this heterogeneous information into a global ranking. We describe an extended version of our gene prioritization method, Endeavour, now available for six species and integrating 75 data sources. The performance (Area Under the Curve) of Endeavour on cross-validation benchmarks using 'gold standard' gene sets varies from 88% (for human phenotypes) to 95% (for worm gene function). In addition, we have also validated our approach using a time-stamped benchmark derived from the Human Phenotype Ontology, which provides a setting close to prospective validation. With this benchmark, using 3854 novel gene-phenotype associations, we observe a performance of 82%. Altogether, our results indicate that this extended version of Endeavour efficiently prioritizes candidate genes. The Endeavour web server is freely available at https://endeavour.esat.kuleuven.be/.
Candidate Prediction Models and Methods
DEFF Research Database (Denmark)
Nielsen, Henrik Aalborg; Nielsen, Torben Skov; Madsen, Henrik
2005-01-01
This document lists candidate prediction models for Work Package 3 (WP3) of the PSO-project called ``Intelligent wind power prediction systems'' (FU4101). The main focus is on the models transforming numerical weather predictions into predictions of power production. The document also outlines...... the possibilities w.r.t. different numerical weather predictions actually available to the project....
Candidate cave entrances on Mars
Cushing, Glen E.
2012-01-01
This paper presents newly discovered candidate cave entrances into Martian near-surface lava tubes, volcano-tectonic fracture systems, and pit craters and describes their characteristics and exploration possibilities. These candidates are all collapse features that occur either intermittently along laterally continuous trench-like depressions or in the floors of sheer-walled atypical pit craters. As viewed from orbit, locations of most candidates are visibly consistent with known terrestrial features such as tube-fed lava flows, volcano-tectonic fractures, and pit craters, each of which forms by mechanisms that can produce caves. Although we cannot determine subsurface extents of the Martian features discussed here, some may continue unimpeded for many kilometers if terrestrial examples are indeed analogous. The features presented here were identified in images acquired by the Mars Odyssey's Thermal Emission Imaging System visible-wavelength camera, and by the Mars Reconnaissance Orbiter's Context Camera. Select candidates have since been targeted by the High-Resolution Imaging Science Experiment. Martian caves are promising potential sites for future human habitation and astrobiology investigations; understanding their characteristics is critical for long-term mission planning and for developing the necessary exploration technologies.
Fusion reactions with the one-neutron halo nucleus 15C
Alcorta, M; Back, B B; Bedoor, S; Bertone, P F; Deibel, C M; DiGiovine, B; Esbensen, H; Greene, J P; Hoffmann, C R; Jiang, C L; Lighthall, J C; Marley, S T; Pardo, R C; Paul, M; Rogers, A M; Ugalde, C; Wuosmaa, A H
2011-01-01
The structure of 15C, with an s1/2 neutron weakly bound to a closed-neutron shell nucleus 14C, makes it a prime candidate for a one-neutron halo nucleus. We have for the first time studied the cross section for the fusion-fission reaction 15C + 232Th at energies in the vicinity of the Coulomb barrier and compared it to the yield of the neighboring 14C + 232Th system measured in the same experiment. At sub-barrier energies, an enhancement of the fusion yield by factors of 2-5 was observed for 15C, while the cross sections for 14C match the trends measured for 12,13C.
Nucleus-associated actin in Amoeba proteus.
Berdieva, Mariia; Bogolyubov, Dmitry; Podlipaeva, Yuliya; Goodkov, Andrew
2016-10-01
The presence, spatial distribution and forms of intranuclear and nucleus-associated cytoplasmic actin were studied in Amoeba proteus with immunocytochemical approaches. Labeling with different anti-actin antibodies and staining with TRITC-phalloidin and fluorescent deoxyribonuclease I were used. We showed that actin is abundant within the nucleus as well as in the cytoplasm of A. proteus cells. According to DNase I experiments, the predominant form of intranuclear actin is G-actin which is associated with chromatin strands. Besides, unpolymerized actin was shown to participate in organization of a prominent actin layer adjacent to the outer surface of nuclear envelope. No significant amount of F-actin was found in the nucleus. At the same time, the amoeba nucleus is enclosed in a basket-like structure formed by circumnuclear actin filaments and bundles connected with global cytoplasmic actin cytoskeleton. A supposed architectural function of actin filaments was studied by treatment with actin-depolymerizing agent latrunculin A. It disassembled the circumnuclear actin system, but did not affect the intranuclear chromatin structure. The results obtained for amoeba cells support the modern concept that actin is involved in fundamental nuclear processes that have evolved in the cells of multicellular organisms.
An organism arises from every nucleus.
Directory of Open Access Journals (Sweden)
Nurullah Keklikoglu
2009-12-01
Full Text Available The fact that, cloning using somatic cell nuclear transfer (SCNT method has been performed, opened new horizons for cloning, and changed the way of our understanding and approach to cell and nucleus. The progress in cloning technology, brought the anticipation of the ability to clone an organism from each somatic cell nucleus. Therefore, the 'Cell Theory' is about to take the additional statement as "An organism arises from every nucleus". The development of gene targeting procedures which can be applied with SCNT, showed us that it may be possible to obtain different versions of the original genetic constitution of a cell. Because of this opportunity which is provided by SCNT, in reproductive cloning, it would be possible to clone enhanced organisms which can adapt to different environmental conditions and survive. Furthermore, regaining the genetic characteristics of ancestors or reverse herediter variations would be possible. On the other hand, in therapeutic cloning, more precise and easily obtainable alternatives for cell replacement therapy could be presented. However, while producing healthier or different organisms from a nucleus, it is hard to foresee the side effects influencing natural processes in long term is rather difficult.
Nonequilibrium distribution functions of nucleons in relativistic nucleus-nucleus collisions
Anchishkin, D; Cleymans, J; 10.5488/CMP.16.13201
2013-01-01
The collision smearing of the nucleon momenta about their initial values during relativistic nucleus-nucleus collisions is investigated. To a certain degree, our model belongs to the transport type, and we investigate the evolution of the nucleon system created at a nucleus-nucleus collision. However, we parameterize this development by the number of collisions of every particle during evolution rather than by the time variable. It is assumed that the group of nucleons which leave the system after the same number of collisions can be joined in a particular statistical ensemble. The nucleon nonequilibrium distribution functions, which depend on a certain number of collisions of a nucleon before freeze-out, are derived.
Study of -nucleus interaction through the formation of -nucleus bound state
Indian Academy of Sciences (India)
V Jha; B J Roy; A Chatterjee; H Machner
2006-05-01
The question of possible existence of -mesic nuclei is quite intriguing. Answer to this question will deeply enrich our understanding of -nucleus interaction which is not so well-understood. We review the experimental efforts for the search of -mesic nuclei and describe the physics motivation behind it. We present the description of an experiment for the search of -nucleus bound state using the GeV proton beam, currently being performed at COSY.
Centrality Dependence of Flow in High-Energy Nucleus-Nucleus Collisions
Institute of Scientific and Technical Information of China (English)
杨红艳; 周代翠; 杨纯斌; 蔡勖
2002-01-01
Directed flow and elliptic flow of final state particles in high-energy nucleus-nucleus collisions in the EMU01 experiment have been studied. The dependences of directed flow and elliptic flow on incident energy and impact centrality of outgoing particles are presented. The results exhibit strong dependence of flow on centrality and energy. We also suggest a more reliable way to determine the event plane resolution here.
Automatic Classification of Kepler Planetary Transit Candidates
McCauliff, Sean D.; Jenkins, Jon M.; Catanzarite, Joseph; Burke, Christopher J.; Coughlin, Jeffrey L.; Twicken, Joseph D.; Tenenbaum, Peter; Seader, Shawn; Li, Jie; Cote, Miles
2014-01-01
In the first three years of operation the Kepler mission found 3,697 planet candidates from a set of 18,406 transit-like features detected on over 200,000 distinct stars. Vetting candidate signals manually by inspecting light curves and other diagnostic information is a labor intensive effort. Additionally, this classification methodology does not yield any information about the quality of planet candidates; all candidates are as credible as any other candidate. The torrent of exoplanet disco...
Weakly interacting massive particle-nucleus elastic scattering response
Anand, Nikhil; Fitzpatrick, A. Liam; Haxton, W. C.
2014-06-01
Background: A model-independent formulation of weakly interacting massive particle (WIMP)-nucleon scattering was recently developed in Galilean-invariant effective field theory. Purpose: Here we complete the embedding of this effective interaction in the nucleus, constructing the most general elastic nuclear cross section as a factorized product of WIMP and nuclear response functions. This form explicitly defines what can and cannot be learned about the low-energy constants of the effective theory—and consequently about candidate ultraviolet theories of dark matter—from elastic scattering experiments. Results: We identify those interactions that cannot be reliably treated in a spin-independent/spin-dependent (SI/SD) formulation: For derivative- or velocity-dependent couplings, the SI/SD formulation generally mischaracterizes the relevant nuclear operator and its multipolarity (e.g., scalar or vector) and greatly underestimates experimental sensitivities. This can lead to apparent conflicts between experiments when, in fact, none may exist. The new nuclear responses appearing in the factorized cross section are related to familiar electroweak nuclear operators such as angular momentum l⃗(i) and the spin-orbit coupling σ⃗(i).l⃗(i). Conclusions: To unambiguously interpret experiments and to extract all of the available information on the particle physics of dark matter, experimentalists will need to (1) do a sufficient number of experiments with nuclear targets having the requisite sensitivities to the various operators and (2) analyze the results in a formalism that does not arbitrarily limit the candidate operators. In an appendix we describe a code that is available to help interested readers implement such an analysis.
Leishmaniasis: vaccine candidates and perspectives.
Singh, Bhawana; Sundar, Shyam
2012-06-06
Leishmania is a protozoan parasite and a causative agent of the various clinical forms of leishmaniasis. High cost, resistance and toxic side effects of traditional drugs entail identification and development of therapeutic alternatives. The sound understanding of parasite biology is key for identifying novel drug targets, that can induce the cell mediated immunity (mainly CD4+ and CD8+ IFN-gamma mediated responses) polarized towards a Th1 response. These aspects are important in designing a new vaccine along with the consideration of the candidates with respect to their ability to raise memory response in order to improve the vaccine performance. This review is an effort to identify molecules according to their homology with the host and their ability to be used as potent vaccine candidates.
Enthalpy screen of drug candidates.
Schön, Arne; Freire, Ernesto
2016-11-15
The enthalpic and entropic contributions to the binding affinity of drug candidates have been acknowledged to be important determinants of the quality of a drug molecule. These quantities, usually summarized in the thermodynamic signature, provide a rapid assessment of the forces that drive the binding of a ligand. Having access to the thermodynamic signature in the early stages of the drug discovery process will provide critical information towards the selection of the best drug candidates for development. In this paper, the Enthalpy Screen technique is presented. The enthalpy screen allows fast and accurate determination of the binding enthalpy for hundreds of ligands. As such, it appears to be ideally suited to aid in the ranking of the hundreds of hits that are usually identified after standard high throughput screening.
Candidate genes in panic disorder
DEFF Research Database (Denmark)
Howe, A. S.; Buttenschön, Henriette N; Bani-Fatemi, A.
2016-01-01
The utilization of molecular genetics approaches in examination of panic disorder (PD) has implicated several variants as potential susceptibility factors for panicogenesis. However, the identification of robust PD susceptibility genes has been complicated by phenotypic diversity, underpowered...... association studies and ancestry-specific effects. In the present study, we performed a succinct review of case-control association studies published prior to April 2015. Meta-analyses were performed for candidate gene variants examined in at least three studies using the Cochrane Mantel-Haenszel fixed......-effect model. Secondary analyses were also performed to assess the influences of sex, agoraphobia co-morbidity and ancestry-specific effects on panicogenesis. Meta-analyses were performed on 23 variants in 20 PD candidate genes. Significant associations after correction for multiple testing were observed...
Why do we have a caudate nucleus?
Villablanca, Jaime R
2010-01-01
In order to understand the physiological role of the caudate nucleus, we combine here our laboratory data on cats with reports of patients with selective damage to this nucleus. Cats with bilateral removal of the caudate nuclei showed a stereotyped behavior consisting of persistently approaching and then following a person, another cat, or any object, and attempting to contact the target. Simultaneously, the animals exhibited a friendly disposition and persistent docility together with purring and forelimbs treading/kneading. The magnitude and duration of this behavior was proportional to the extent of the removal reaching a maximum after ablations of 65% or more of the caudate tissue. These cats were hyperactive but they had lost the feline elegance of movements. Additional features of acaudate cats were: (1) postural and accuracy deficits (plus perseveration) in paw usage tasks including bar pressing for food reward; (2) cognitive and perceptual impairments on a T-maze battery of tasks and on the bar pressing tasks; (3) blockage or blunting of the species-specific behavioral response to a single injection of morphine; Unilateral caudate nucleus removal did not produce global behavioral effects, but only deficit in the contralateral paw contact placing reaction and paw usage/bar pressing. Moreover and surprisingly, we found hypertrophy of the ipsilateral caudate nucleus following prenatal focal neocortical removal. The findings in human were also behavioral (not neurological) and also occurred with unilateral caudate damage. The main manifestations consisted of loss of drive (apathy), obsessive-compulsive behavior, cognitive deficits, stimulus-bound perseverative behavior, and hyperactivity. Based on all of the above data we propose that the specific function of the caudate nucleus is to control approach-attachment behavior, ranging from plain approach to a target, to romantic love. This putative function would account well for the caudate involvement in the
Search for Double γ-Vibrational Bands in Neutron-Rich 105Mo Nucleus
Institute of Scientific and Technical Information of China (English)
DING Huai-Bo; CHEN Yong-Jing; LI Ming-Liang; ZHU Sheng-Jiang; J. H. Hamilton; A. V. Ramayya; J. K. Hwang; Y. X. Luo; J. O. Rasmussen; I. Y. Lee; CHE Xing-Lai
2006-01-01
Levels in the neutron-rich 105 Mo nucleus have been investigated by observing prompt γ-rays following the spon taneous fission fragments of 252 Cf with the Gammasphere detector array. The yrast band has been confirmed and updated. The other two collective bands with the band head levels at 870.5 and 1534.6 keV are newly observed,and they are suggested as the candidates for one-phonon K = 9/2 and two-phonon K = 13/2 double γ-vibrational bands, respectively. Systematic characteristics of these bands have been discussed.
Institute of Scientific and Technical Information of China (English)
XIE Wen-Jie
2011-01-01
The transverse momentum distributions of final-state particles produced in nucleus-nucleus (AA),proton-nucleus (pA),and proton-proton (pp) collisions at high energies are investigated using a multisource ideal gas model.Our calculated results show that the contribution of hard emission can be neglected in the study of transverse momentum spectra of charged pions and kaons produced in Cu-Cu collisions at (√SNN)=22.5 GeV.And if we consider the contribution of hard emission,the transverse momentum spectra of p and (P) produced in Cu-Cu collisions at (√SNN)=22.5 GeV,KsO produced in Pb-Pb collisions at 158 A GeV,J/ψ particles produced in p-Pb collisions at 400 GeV and π+,K+,p produced in proton-proton collisions at (√S)=200 GeV,can be described by the model,especially in the tail part of spectra.
Toward organometallic antischistosomal drug candidates.
Hess, Jeannine; Keiser, Jennifer; Gasser, Gilles
2015-01-01
In the recent years, there has been a growing interest in the use of novel approaches for the treatment of parasitic diseases such as schistosomiasis. Among the different approaches used, organometallic compounds were found to offer unique opportunities in the design of antiparasitic drug candidates. A ferrocenyl derivative, namely ferroquine, has even entered clinical trials as a novel antimalarial. In this short review, we report on the studies describing the use of organometallic compounds against schistosomiasis.
Rutherford, Radioactivity, and the Atomic Nucleus
Kragh, Helge
2012-01-01
Modern atomic and nuclear physics took its start in the early part of the twentieth century, to a large extent based upon experimental investigations of radioactive phenomena. Foremost among the pioneers of the new kind of physics was Ernest Rutherford, who made fundamental contributions to the structure of matter for more than three decades and, in addition, founded important research schools in Manchester and Cambridge. This paper reviews the most important aspects of Rutherford's scientific work in the period from about 1900 to 1920, and it also refers to some of his last experiments of the 1930s. The emphasis is on his theory of radioactive disintegration (1902), the discovery of the atomic nucleus (1911), and the first artificially produced element transformation (1919). Following the transmutation experiments, Rutherford developed elaborate models of the atomic nucleus, but these turned out to be unsuccessful. Other subjects could be included, but the three mentioned are undoubtedly those of the greates...
Correlations in neutrino-nucleus scattering
Van Cuyck, Tom; Jachowicz, Natalie; González-Jiménez, Raul; Martini, Marco; Ryckebusch, Jan; Van Dessel, Nils
2016-01-01
We present a detailed study of charged-current quasielastic neutrino-nucleus scattering and of the influence of correlations on one- and two-nucleon knockout processes. The quasielastic neutrino-nucleus scattering cross sections, including the influence of long-range correlations, are evaluated within a continuum random phase approximation approach. The short-range correlation formalism is implemented in the impulse approximation by shifting the complexity induced by the correlations from the wave functions to the operators. The model is validated by confronting $(e,e^\\prime)$ cross-section predictions with electron scattering data in the kinematic region where the quasielastic channel is expected to dominate. Further, the $^{12}$C$(\
Single pion production in neutrino nucleus scattering
Hernández, E; Vacas, M J Vicente
2013-01-01
We study one pion production in both charged and neutral current neutrino nucleus scattering for neutrino energies below 2 GeV. We use a theoretical model for one pion production at the nucleon level that we correct for medium effects. The results are incorporated into a cascade program that apart from production also includes the pion final state interaction inside the nucleus. Besides, in some specific channels coherent pion production is also possible and we evaluate its contribution as well. Our results for total and differential cross sections are compared with recent data from the MiniBooNE Collaboration. The model provides an overall acceptable description of data, better for NC than for CC channels, although theory is systematically below data. Differential cross sections, folded with the full neutrino flux, show that most of the missing pions lie on the forward direction and at high energies.
Coherency in Neutrino-Nucleus Elastic Scattering
Kerman, S; Deniz, M; Wong, H T; Chen, J -W; Li, H B; Lin, S T; Liu, C -P; Yue, Q
2016-01-01
Neutrino-nucleus elastic scattering provides a unique laboratory to study the quantum mechanical coherency effects in electroweak interactions, towards which several experimental programs are being actively pursued. We report results of our quantitative studies on the transitions towards decoherency. A parameter ($\\alpha$) is identified to describe the degree of coherency, and its variations with incoming neutrino energy, detector threshold and target nucleus are studied. The ranges of $\\alpha$ which can be probed with realistic neutrino experiments are derived, indicating complementarity between projects with different sources and targets. Uncertainties in nuclear physics and in $\\alpha$ would constrain sensitivities in probing physics beyond the standard model. The maximum neutrino energies corresponding to $\\alpha$>0.95 are derived.
Protein quality control in the nucleus
DEFF Research Database (Denmark)
Nielsen, Sofie V.; Poulsen, Esben Guldahl; Rebula, Caio A.
2014-01-01
to aggregate, cells have evolved several elaborate quality control systems to deal with these potentially toxic proteins. First, various molecular chaperones will seize the misfolded protein and either attempt to refold the protein or target it for degradation via the ubiquitin-proteasome system...... to be particularly active in protein quality control. Thus, specific ubiquitin-protein ligases located in the nucleus, target not only misfolded nuclear proteins, but also various misfolded cytosolic proteins which are transported to the nucleus prior to their degradation. In comparison, much less is known about...... these mechanisms in mammalian cells. Here we highlight recent advances in our understanding of nuclear protein quality control, in particular regarding substrate recognition and proteasomal degradation....
Neutrino-nucleus reactions in supernovae
Dzhioev, Alan A.; Vdovin, A. I.
2016-01-01
We study thermal effects on neutrino-nucleus reactions occurring under supernova conditions. The approach we use is based on the QRPA extended to finite temperature by the thermofield dynamics formalism. For the relevant supernova conditions we calculate inelastic neutrino scattering and neutrino absorption cross sections for two sample nuclei, 56Fe and 82Ge. In addition, we apply the approach to examine the rate of neutrino-antineutrino pair emission by hot nuclei.
Neutrino-nucleus reactions in supernovae
Directory of Open Access Journals (Sweden)
Dzhioev Alan A.
2016-01-01
Full Text Available We study thermal effects on neutrino-nucleus reactions occurring under supernova conditions. The approach we use is based on the QRPA extended to finite temperature by the thermofield dynamics formalism. For the relevant supernova conditions we calculate inelastic neutrino scattering and neutrino absorption cross sections for two sample nuclei, 56Fe and 82Ge. In addition, we apply the approach to examine the rate of neutrino-antineutrino pair emission by hot nuclei.
Theoretical highlights of neutrino-nucleus interactions
Alvarez-Ruso, Luis
2009-01-01
The recent theoretical developments in the field of neutrino-nucleus interactions in the few-GeV region are reviewed based on the presentations made at the NuInt09 Workshop. The topics of electron scattering and its connections with neutrino interactions, neutrino induced quasielastic scattering and pion production (coherent and incoherent) are covered, with special emphasis on the challenges that arise in the comparison with new experimental data.
Neutrino-nucleus CCQE-like scattering
Nieves, J; Simo, I Ruiz; Sanchez, F; Vacas, M J Vicente
2014-01-01
RPA correlations, spectral function and 2p2h (multi-nucleon) effects on charged-current neutrino-nucleus reactions without emitted pions are discussed. We pay attention to the influence of RPA and multi-nucleon mechanisms on the MiniBooNE and MINERvA flux folded differential cross sections, the MiniBooNE flux unfolded total cross section and the neutrino energy reconstruction.
Development of a Mobile Ice Nucleus Counter
Energy Technology Data Exchange (ETDEWEB)
Kok, Gregory [Droplet Measurement Technologies, Boulder, CO (United States); Kulkarni, Gourihar [Droplet Measurement Technologies, Boulder, CO (United States)
2014-07-10
An ice nucleus counter has been constructed. The instrument uses built-in refrigeration systems for wall cooling. A cascade refrigeration system will allow the cold wall to operate as low as -70°C, and a single stage system can operate the warm wall at -45C. A unique optical particle counter has been constructed using polarization detection of the scattered light. This allows differentiation of the particles exiting the chamber to determine if they are ice or liquid.
Development of a Mobile Ice Nucleus Counter
Energy Technology Data Exchange (ETDEWEB)
Kok, Gregory; Kulkarni, Gourihar
2014-07-10
An ice nucleus counter has been constructed. The instrument uses built-in refrigeration systems for wall cooling. A cascade refrigeration system will allow the cold wall to operate as low as -70 deg C, and a single stage system can operate the warm wall at -45 deg C. A unique optical particle counter has been constructed using polarization detection of the scattered light. This allows differentiation of the particles exiting the chamber to determine if they are ice or liquid.
Comet nucleus and asteroid sample return missions
1992-01-01
Three Advanced Design Projects have been completed this academic year at Penn State. At the beginning of the fall semester the students were organized into eight groups and given their choice of either a comet nucleus or an asteroid sample return mission. Once a mission had been chosen, the students developed conceptual designs. These were evaluated at the end of the fall semester and combined into three separate mission plans, including a comet nucleus same return (CNSR), a single asteroid sample return (SASR), and a multiple asteroid sample return (MASR). To facilitate the work required for each mission, the class was reorganized in the spring semester by combining groups to form three mission teams. An integration team consisting of two members from each group was formed for each mission so that communication and information exchange would be easier among the groups. The types of projects designed by the students evolved from numerous discussions with Penn State faculty and mission planners at the Johnson Space Center Human/Robotic Spacecraft Office. Robotic sample return missions are widely considered valuable precursors to manned missions in that they can provide details about a site's environment and scientific value. For example, a sample return from an asteroid might reveal valuable resources that, once mined, could be utilized for propulsion. These missions are also more adaptable when considering the risk to humans visiting unknown and potentially dangerous locations, such as a comet nucleus.
Oscillations of moments in high-energy nucleus-nucleus collisions
Institute of Scientific and Technical Information of China (English)
杨红艳; 周代翠; 钱琬燕; 王晓荣
2001-01-01
The definitions of density function and moment of multiplicity distribution are introduced,and the method of moment analysis in e+ e- and proton-proton (pp) interactions is extended into nu-cleus-nucleus (AA) interactions. We analyze the data for relativistic nucleus-nucleus collisions and cal-culate the values of Hq for charged particle multiplicity distributions, by which we study systematically the dependences of Hq on incident energy, mass of colliding system, pseudorapidity interval, centrality and truncation of multiplicity. We compare the oscillation structures induced by e + e-, pp and AA inter-actions, and the comparison and analysis are carried out between experimental data and QCD predic-tion. The latest results are given in this paper.
Reliability of MRI findings in candidates for lumbar disc prosthesis
Energy Technology Data Exchange (ETDEWEB)
Berg, Linda; Espeland, Ansgar [Haukeland University Hospital, Department of Radiology, Bergen (Norway); University of Bergen, Section for Radiology, Department of Surgical Sciences, Bergen (Norway); Neckelmann, Gesche [Haukeland University Hospital, Department of Radiology, Bergen (Norway); Gjertsen, Oeivind [Oslo University Hospital, Department of Neuroradiology, Oslo (Norway); Hellum, Christian [Oslo University Hospital, Department of Orthopaedics, Oslo (Norway); University of Oslo, Department of Orthopaedics, Oslo (Norway); Johnsen, Lars G. [University Hospital of Trondheim, National Centre for Diseases of the Spine, Trondheim (Norway); University Hospital of Trondheim, Orthopaedic Department, Trondheim (Norway); Eide, Geir E. [Haukeland University Hospital, Centre for Clinical Research, Bergen (Norway); University of Bergen, Department of Public Health and Primary Health Care, Bergen (Norway)
2012-07-15
Limited reliability data exist for localised magnetic resonance imaging (MRI) findings relevant to planning of treatment with lumbar disc prosthesis and later outcomes. We assessed the reliability of such findings in chronic low back pain patients who were accepted candidates for disc prosthesis. On pretreatment MRI of 170 patients (mean age 41 years; 88 women), three experienced radiologists independently rated Modic changes, disc findings and facet arthropathy at L3/L4, L4/L5 and L5/S1. Two radiologists rerated 126 examinations. For each MRI finding at each disc level, agreement was analysed using the kappa statistic and differences in prevalence across observers using a fixed effects model. All findings at L3/L4 and facet arthropathy at L5/S1 had a mean prevalence <10% across observers and were not further analysed, ensuring interpretable kappa values. Overall interobserver agreement was generally moderate or good (kappa 0.40-0.77) at L4-S1 for Modic changes, nucleus pulposus signal, disc height (subjective and measured), posterior high-intensity zone (HIZ) and disc contour, and fair (kappa 0.24) at L4/L5 for facet arthropathy. Posterior HIZ at L5/S1 and severely reduced subjective disc height at L4/L5 differed up to threefold in prevalence between observers (p < 0.0001). Intraobserver agreement was mostly good or very good (kappa 0.60-1.00). In candidates for disc prosthesis, mostly moderate interobserver agreement is expected for localised MRI findings. (orig.)
Transverse energy distributions in nucleus-nucleus collisions at 200 GeV/nucleon
Energy Technology Data Exchange (ETDEWEB)
Baglin, C.; Baldisseri, A.; Bussiere, A.; Guillaud, J.P.; Kossakowski, R.; Liaud, P.; Staley, F. (Institut National de Physique Nucleaire et de Physique des Particules, 74 - Annecy-le-Vieux (France). Lab. de Physique des Particules); Baldit, A.; Castor, J.; Chambon, T.; Devaux, A.; Fargeix, J.; Felgeyrolles, X.; Force, P.; Fredj, L.; Landaud, G.; Vazeille, F. (Institut National de Physique Nucleaire et de Physique des Particules, 63 - Clermont-Ferrand (France). Lab. de Physique Corpusculaire Clermont-Ferrand-2 Univ., 63 - Aubiere (France)); Sonderegger, P. (European Organization for Nuclear Research, Geneva (Switzerland)); Abreu, M.C.; Bordalo, P.; Ferreira, R.; Gago, J.M.; Lourenco, C.; Peralta, L.; Pimenta, M.; Ramos, S.; Silva, S.; Varela, J. (LIP, Lisbon (Portugal)); Gerschel, C.; Jouan, D.; Papillon, S.; Tarrago, X. (Institut National de Physique Nucleaire et de Physique des Particules, 91 - Orsay (France). Inst. de Physique Nucleaire Paris-11 Univ., 91 - Orsay (France)); Bus; NA38 Collaboration
1990-11-22
The transverse energy E{sub T} distributions of nucleus-nucleus collisions are studied in the framework of a simple geometrical model. The distributions for inclusive production of J/{psi} and muon pairs in the mass continuum are analyzed. The shape of the E{sub T} distribution of the continuum agrees with the model. The previously observed decrease of the ratio (J/{psi})/continuum with increasing E{sub T} is due to the behavior of the J/{psi}. (orig.).
Aspects of Coulomb dissociation and interference in peripheral nucleus-nucleus collisions
Energy Technology Data Exchange (ETDEWEB)
Nystrand, Joakim; Baltz, Anthony; Klein, Spencer R.
2001-10-21
Coherent vector meson production in peripheral nucleus-nucleus collisions is discussed. These interactions may occur for impact parameters much larger than the sum of the nuclear radii. Since the vector meson production is always localized to one of the nuclei, the system acts as a two-source interferometer in the transverse plane. By tagging the outgoing nuclei for Coulomb dissociation it is possible to obtain a measure of the impact parameter and thus the source separation in the interferometer. This is of particular interest since the life-time of the vector mesons are generally much shorter than the impact parameters of the collisions.
Jet tomography of high-energy nucleus-nucleus collisions at next-to-leading order
Energy Technology Data Exchange (ETDEWEB)
Vitev, Ivan [Los Alamos National Laboratory; Zhang, Ben - Wei [Los Alamos National Laboratory
2009-01-01
We demonstrate that jet observables are highly sensitive to the characteristics of the vacuum and the in-medium QCD parton showers and propose techniques that exploit this sensitivity to constrain the mechanism of quark and gluon energy loss in strongly-interacting plasmas. As a first example, we calculate the inclusive jet cross section in high-energy nucleus-nucleus collisions to {Omicron}({alpha}{sub s}{sup 3}). Theoretical predictions for the medium-induced jet broadening and the suppression of the jet production rate due to cold and hot nuclear matter effects in Au+Au and Cu+Cu reactions at RHIC are presented.
Azimuthal correlations of hadrons and fragments in nucleus-nucleus collisions
Institute of Scientific and Technical Information of China (English)
LI Hui-Ling
2011-01-01
Two-particle (two-fragment) azimuthal correlation functions are studied by using a simple formula which describes uniformly azimuthal distributions of final-state charged particles and nuclear fragments.This formula is obtained in the framework of a multi-source thermal model (or multi-source ideal gas model).The calculated results are compared and found to be in agreement with the experimental data of charged hadrons and nuclear fragments in nucleus-nucleus collisions at intermediate and high energies.
The effect of the relative nuclear size on the nucleus-nucleus interactions
Erofeeva, I. N.; Murzin, V. S.; Sivoklokov, S. Y.; Smirnova, L. N.
1985-01-01
The experimental data on the interactions of light nuclei (d, He(4), C(12)) at the momentum 4.2 GeV/cA with the carbon nuclei were taken in the 2-m propane bubble chamber. The distributions in the number of interacting nucleons, the spectra of protons, the mean energies of secondary pions and protons, the mean fractions of energy transferred to the pion and nucleon components are presented. The results of the investigation of the mechanism of nucleus-nucleus interactions can be used to calculate the nuclear cascades in the atmosphere.
Electromagnetic processes in nucleus-nucleus collisions relating to space radiation research
Norbury, John W.
1992-01-01
Most of the papers within this report deal with electromagnetic processes in nucleus-nucleus collisions which are of concern in the space radiation program. In particular, the removal of one and two nucleons via both electromagnetic and strong interaction processes has been extensively investigated. The theory of relativistic Coulomb fission has also been developed. Several papers on quark models also appear. Finally, note that the theoretical methods developed in this work have been directly applied to the task of radiation protection of astronauts. This has been done by parameterizing the theoretical formalism in such a fashion that it can be used in cosmic ray transport codes.
Melkumov, G L; Anticic, T; Baatar, B; Barna, D; Bartke, J; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Buncic, P; Cerny, V; Christakoglou, P; Chung, P; Chvala, O; Cramer, J G; Csató, P; Dinkelaker, P; Eckardt, V; Flierl, D; Fodor, Z; Foka, P; Friese, V; Gál, J; Gazdzicki, M; Genchev, V; Georgopoulos, G; Grebieszkow, K; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kikola, D; Gladysz-Dziadus, E; Kliemant, M; Kniege, S; Kolesnikov, V I; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Laszlo, A; Lacey, R; Van Leeuwen, M; Lvai, P; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Mateev, M; Melkumov, G L; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, S; Nicolic, V; Pálla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Peryt, W; Pikna, M; Pluta, J; Prindle, D; Pühlhofer, F; Renfordt, R; Roland, C; Roland5, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Siklér, F; Sitár, B; Skrzypczak, E; Slodkowski, M; Stefanek, G; Stock, R; Seyboth, P; Strabel, C; Ströbele, H; Susa, T; Szentpetery, I; Sziklai, J; Szuba, M; Szymanski, P; Trubnikov, V; Varga, D; Vassiliou, M; Veres, G I; Vesztergombi, G; Vranic, D; Wlodarczyk, Z; Wojtaszek11, A; Yoo, I K; Zimnyi, J; Wetzler, A
2007-01-01
The NA49 experiment has collected comprehensive data on particle production in nucleus-nucleus collisions over the whole SPS beam energies range, the critical energy domain where the expected phase transition to a deconfined phase is expected to occur. The latest results from Pb+Pb collisions between 20$A$ GeV and 158$A$ GeV on baryon stopping and light nuclei production as well as those for strange hyperons are presented. The measured data on $p$, $\\bar{p}$, $\\Lambda$, $\\bar{\\Lambda}$, $\\Xi^-$ and $\\bar{\\Xi}^+$ production were used to evaluate the rapidity distributions of net-baryons at SPS energies and to compare with the results from the AGS and the RHIC for central Pb+Pb (Au+Au) collisions. The dependence of the yield ratios and the inverse slope parameter of the $m_t$ spectra on the collision energy and centrality, and the mass number of the produced nuclei $^3He$, $t$, $d$ and $\\bar{d}$ are discussed within coalescence and statistical approaches. Analysis of the total multiplicity exhibits remarkable a...
Contemporary models of the atomic nucleus
Nemirovskii, P E
2013-01-01
Contemporary Models of the Atomic Nucleus discusses nuclear structure and properties, expounding contemporary theoretical concepts of the low-energy nuclear processes underlying in nuclear models. This book focuses on subjects such as the optical nuclear model, unified or collective model, and deuteron stripping reaction. Other topics discussed include the basic nuclear properties; shell model; theoretical analysis of the shell model; and radiative transitions and alpha-decay. The deuteron theory and the liquid drop nuclear model with its application to fission theory are also mentioned, but o