International Nuclear Information System (INIS)
Clark, R.M.
2004-01-01
It has been suggested that a change of nuclear shape may be described in terms of a phase transition and that specific nuclei may lie close to the critical point of the transition. Analytical descriptions of such critical-point nuclei have been introduced recently and they are described briefly. The results of extensive searches for possible examples of critical-point behavior are presented. Alternative pictures, such as describing bands in the candidate nuclei using simple ΔK = 0 and ΔK = 2 rotational-coupling models, are discussed, and the limitations of the different approaches highlighted. A possible critical-point description of the transition from a vibrational to rotational pairing phase is suggested
Unconventional Quantum Critical Points
Xu, Cenke
2012-01-01
In this paper we review the theory of unconventional quantum critical points that are beyond the Landau's paradigm. Three types of unconventional quantum critical points will be discussed: (1). The transition between topological order and semiclassical spin ordered phase; (2). The transition between topological order and valence bond solid phase; (3). The direct second order transition between different competing orders. We focus on the field theory and universality class of these unconventio...
Critical point predication device
International Nuclear Information System (INIS)
Matsumura, Kazuhiko; Kariyama, Koji.
1996-01-01
An operation for predicting a critical point by using a existent reverse multiplication method has been complicated, and an effective multiplication factor could not be plotted directly to degrade the accuracy for the prediction. The present invention comprises a detector counting memory section for memorizing the counting sent from a power detector which monitors the reactor power, a reverse multiplication factor calculation section for calculating the reverse multiplication factor based on initial countings and current countings of the power detector, and a critical point prediction section for predicting the criticality by the reverse multiplication method relative to effective multiplication factors corresponding to the state of the reactor core previously determined depending on the cases. In addition, a reactor core characteristic calculation section is added for analyzing an effective multiplication factor depending on the state of the reactor core. Then, if the margin up to the criticality is reduced to lower than a predetermined value during critical operation, an alarm is generated to stop the critical operation when generation of a period of more than a predetermined value predicted by succeeding critical operation. With such procedures, forecasting for the critical point can be easily predicted upon critical operation to greatly mitigate an operator's burden and improve handling for the operation. (N.H.)
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.
DEFF Research Database (Denmark)
Jensen, Ole B.; Wind, Simon; Lanng, Ditte Bendix
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...... elsewhere (Jensen & Morelli 2011). In this article, we will only discuss the conceptual and theoretical framing superficially, since our real interest is to show and discuss the concept's application value to spatial design in a number of urban design studios. The 'data' or the projects presented are seven...... in urban design at Aalborg University, where urban design consists of both an analytical and an interventionist field of operation. Furthermore, the content of the CPC concept links to research in mobilities, the network city, and urban design. These are among the core pillars of both the masters programme...
Energy Technology Data Exchange (ETDEWEB)
Walaas, I; Fonnum, F
1979-01-01
The origin of fibers containing different neurotransmitter candidates in the nucleus accumbens of rat brain has been studied with surgical and chemical lesion techniques. Destruction of the medial forebrain bundle decreased the activity of aromatic amino acid decarboxylase by 80% in the nucleus. Cutting of the fornix or a hemitransection decreased the high affinity uptake of glutamate by 45% and the endogenous level of glutamate by 33%. The high affinity uptake of glutamate was concentrated in the synaptosomal fraction and the decrease after the lesion was most pronounced in this fraction. Restricted lesions indicated that fibers in the fimbria/fornix coming from the subiculum were responsible for this part of the glutamate uptake in the nucleus. Local injection of kainic acid into the nucleus was accompanied by a 75% decrease in choline acetyltransferase and a 35% decrease in acetylcholineserase activities, a 70% decrease in glutamate decarboxylase activity and a 60% decrease in the high affinity uptake of ..gamma..-aminobutyrate, a 45% decrease in high affinity glutamate uptake, and no change in aromatic amino acid decarboxylase activity. Performing a lesion of the fornix after kainic acid injection led to an 85% decrease in high affinity glutamate uptake, without further affecting the other neuronal markers. The results indicate that all aminergic fibers to the nucleus accumbens are ascending in the medial forebrain bundle, that the subiculum-accumbens fibers are glutamergic and the nucleus also contains intrinsic glutamergic or aspartergic cells. Cholinergic and ..gamma..-aminobutyrate-containing cells are wholly intrinsic to the nucleus.
Critical points in magnetic systems
International Nuclear Information System (INIS)
Bongaarts, A.L.M.
1975-01-01
The magnetical phase transitions of CsCoCl 3 .2H 2 O and CsCoCl 3 .2D 2 O are investigated by neutron diffraction techniques with special attention to the critical points in the phase diagrams. CsCoCl 3 .2H 2 O turned out to be a one-dimentional magnetic antiferromagnet with ferromagnetic and antiferromagnetic interactions. In the vicinity of the Neel point, the critical behavior in zero magnetic field could be described as a three-dimentional long range ordering, while the fluctuations in the system are one-dimensional. In the presence of a magnetic field, the behavior of the system in the critical region of the magnetic phase diagram between the Neel temperature at zero field (3.3degK) and 1.85degK, was in good agreement with the theory. Below 1.85degK, the phase transition in a magnetic field changes into a line of triple points whose end point could be identified as a tricritical point, i.e., an intersection of three critical lines. The parameters derived from observations in the neighborhood of this tricritical point obey the scaling laws but are not in numerical agreement with theoretical predictions
Interval Mathematics Applied to Critical Point Transitions
Directory of Open Access Journals (Sweden)
Benito A. Stradi
2012-03-01
Full Text Available 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 if a mixture of a given composition does not have one. This study uses an interval Newton/Generalized Bisection algorithm that provides a mathematical and computational guarantee that all mixture critical points are located. The technique is illustrated using several example problems. These problems involve cubic equation of state models; however, the technique is general purpose and can be applied in connection with other nonlinear problems.
The existence of trajectories joining critical points
International Nuclear Information System (INIS)
Yu Shuxiang.
1985-01-01
In this paper, using the notion of an isolating block and the concept of canonical regions, three existence criteria of trajectories connecting a pair of critical points of planar differential equations are given. (author)
A ∼ 3.8 hr PERIODICITY FROM AN ULTRASOFT ACTIVE GALACTIC NUCLEUS CANDIDATE
Energy Technology Data Exchange (ETDEWEB)
Lin, Dacheng; Irwin, Jimmy A. [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States); Godet, Olivier; Webb, Natalie A.; Barret, Didier, E-mail: dlin@ua.edu [CNRS, IRAP, 9 avenue du Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France)
2013-10-10
Very few galactic nuclei are found to show significant X-ray quasi-periodic oscillations (QPOs). After carefully modeling the noise continuum, we find that the ∼3.8 hr QPO in the ultrasoft active galactic nucleus candidate 2XMM J123103.2+110648 was significantly detected (∼5σ) in two XMM-Newton observations in 2005, but not in the one in 2003. The QPO root mean square (rms) is very high and increases from ∼25% in 0.2-0.5 keV to ∼50% in 1-2 keV. The QPO probably corresponds to the low-frequency type in Galactic black hole X-ray binaries, considering its large rms and the probably low mass (∼10{sup 5} M {sub ☉}) of the black hole in the nucleus. We also fit the soft X-ray spectra from the three XMM-Newton observations and find that they can be described with either pure thermal disk emission or optically thick low-temperature Comptonization. We see no clear X-ray emission from the two Swift observations in 2013, indicating lower source fluxes than those in XMM-Newton observations.
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.
QCD and the chiral critical point
International Nuclear Information System (INIS)
Gavin, S.; Gocksch, A.; Pisarski, R.D.
1994-01-01
As an extension of QCD, consider a theory with ''2+1'' flavors, where the current quark masses are held in a fixed ratio as the overall scale of the quark masses is varied. At nonzero temperature and baryon density it is expected that in the chiral limit the chiral phase transition is of first order. Increasing the quark mass from zero, the chiral transition becomes more weakly first order, and can end in a chiral critical point. We show that the only massless field at the chiral critical point is a σ meson, with the universality class that of the Ising model. Present day lattice simulations indicate that QCD is (relatively) near to the chiral critical point
The QCD Critical Point and Related Observables
Energy Technology Data Exchange (ETDEWEB)
Nahrgang, Marlene
2016-12-15
The search for the critical point of QCD in heavy-ion collision experiments has sparked enormous interest with the completion of phase I of the RHIC beam energy scan. Here, I review the basics of the thermodynamics of the QCD phase transition and its implications for experimental multiplicity fluctuations in heavy-ion collisions. Several sources of noncritical fluctuations impact the observables and need to be understood in addition to the critical phenomena. Recent progress has been made in dynamical modeling of critical fluctuations, which ultimately is indispensable to understand potential signals of the QCD critical point in heavy-ion collision.
Quench dynamics across quantum critical points
International Nuclear Information System (INIS)
Sengupta, K.; Powell, Stephen; Sachdev, Subir
2004-01-01
We study the quantum dynamics of a number of model systems as their coupling constants are changed rapidly across a quantum critical point. The primary motivation is provided by the recent experiments of Greiner et al. [Nature (London) 415, 39 (2002)] who studied the response of a Mott insulator of ultracold atoms in an optical lattice to a strong potential gradient. In a previous work, it had been argued that the resonant response observed at a critical potential gradient could be understood by proximity to an Ising quantum critical point describing the onset of density wave order. Here we obtain numerical results on the evolution of the density wave order as the potential gradient is scanned across the quantum critical point. This is supplemented by studies of the integrable quantum Ising spin chain in a transverse field, where we obtain exact results for the evolution of the Ising order correlations under a time-dependent transverse field. We also study the evolution of transverse superfluid order in the three-dimensional case. In all cases, the order parameter is best enhanced in the vicinity of the quantum critical point
Critical point analysis of phase envelope diagram
Energy Technology Data Exchange (ETDEWEB)
Soetikno, Darmadi; Siagian, Ucok W. R. [Department of Petroleum Engineering, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Kusdiantara, Rudy, E-mail: rkusdiantara@s.itb.ac.id; Puspita, Dila, E-mail: rkusdiantara@s.itb.ac.id; Sidarto, Kuntjoro A., E-mail: rkusdiantara@s.itb.ac.id; Soewono, Edy; Gunawan, Agus Y. [Department of Mathematics, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)
2014-03-24
Phase diagram or phase envelope is a relation between temperature and pressure that shows the condition of equilibria between the different phases of chemical compounds, mixture of compounds, and solutions. Phase diagram is an important issue in chemical thermodynamics and hydrocarbon reservoir. It is very useful for process simulation, hydrocarbon reactor design, and petroleum engineering studies. It is constructed from the bubble line, dew line, and critical point. Bubble line and dew line are composed of bubble points and dew points, respectively. Bubble point is the first point at which the gas is formed when a liquid is heated. Meanwhile, dew point is the first point where the liquid is formed when the gas is cooled. Critical point is the point where all of the properties of gases and liquids are equal, such as temperature, pressure, amount of substance, and others. Critical point is very useful in fuel processing and dissolution of certain chemicals. Here in this paper, we will show the critical point analytically. Then, it will be compared with numerical calculations of Peng-Robinson equation by using Newton-Raphson method. As case studies, several hydrocarbon mixtures are simulated using by Matlab.
Critical point analysis of phase envelope diagram
International Nuclear Information System (INIS)
Soetikno, Darmadi; Siagian, Ucok W. R.; Kusdiantara, Rudy; Puspita, Dila; Sidarto, Kuntjoro A.; Soewono, Edy; Gunawan, Agus Y.
2014-01-01
Phase diagram or phase envelope is a relation between temperature and pressure that shows the condition of equilibria between the different phases of chemical compounds, mixture of compounds, and solutions. Phase diagram is an important issue in chemical thermodynamics and hydrocarbon reservoir. It is very useful for process simulation, hydrocarbon reactor design, and petroleum engineering studies. It is constructed from the bubble line, dew line, and critical point. Bubble line and dew line are composed of bubble points and dew points, respectively. Bubble point is the first point at which the gas is formed when a liquid is heated. Meanwhile, dew point is the first point where the liquid is formed when the gas is cooled. Critical point is the point where all of the properties of gases and liquids are equal, such as temperature, pressure, amount of substance, and others. Critical point is very useful in fuel processing and dissolution of certain chemicals. Here in this paper, we will show the critical point analytically. Then, it will be compared with numerical calculations of Peng-Robinson equation by using Newton-Raphson method. As case studies, several hydrocarbon mixtures are simulated using by Matlab
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,
Universal signatures of fractionalized quantum critical points.
Isakov, Sergei V; Melko, Roger G; Hastings, Matthew B
2012-01-13
Ground states of certain materials can support exotic excitations with a charge equal to a fraction of the fundamental electron charge. The condensation of these fractionalized particles has been predicted to drive unusual quantum phase transitions. Through numerical and theoretical analysis of a physical model of interacting lattice bosons, we establish the existence of such an exotic critical point, called XY*. We measure a highly nonclassical critical exponent η = 1.493 and construct a universal scaling function of winding number distributions that directly demonstrates the distinct topological sectors of an emergent Z(2) gauge field. The universal quantities used to establish this exotic transition can be used to detect other fractionalized quantum critical points in future model and material systems.
Fermion-induced quantum critical points
Li, Zi-Xiang; Jiang, Yi-Fan; Jian, Shao-Kai; Yao, Hong
2017-01-01
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 t...
Critical point inequalities and scaling limits
International Nuclear Information System (INIS)
Newman, C.M.
1979-01-01
A refined and extended version of the Buckingham-Gunton inequality relating various pairs of critical exponents is shown to be valid for a large class of statistical mechanical models. If this inequality is an equality (in the refined sense) and one of the critical exponents has a non-Gaussian value, then any scaling limit must be non-Gaussian. This result clarifies the relationships between the nontriviality of triviality of the scaling limit for ordinary critical points in four dimensions (or tricritical points in three dimensions) and the existence of logarithmic factors in the asymptotics which define the two critical exponents. (orig.) [de
Deconfined Quantum Critical Points: Symmetries and Dualities
Directory of Open Access Journals (Sweden)
Chong Wang
2017-09-01
Full Text Available The deconfined quantum critical point (QCP, separating the Néel and valence bond solid phases in a 2D antiferromagnet, was proposed as an example of (2+1D criticality fundamentally different from standard Landau-Ginzburg-Wilson-Fisher criticality. In this work, we present multiple equivalent descriptions of deconfined QCPs, and use these to address the possibility of enlarged emergent symmetries in the low-energy limit. The easy-plane deconfined QCP, besides its previously discussed self-duality, is dual to N_{f}=2 fermionic quantum electrodynamics, which has its own self-duality and hence may have an O(4×Z_{2}^{T} symmetry. We propose several dualities for the deconfined QCP with SU(2 spin symmetry which together make natural the emergence of a previously suggested SO(5 symmetry rotating the Néel and valence bond solid orders. These emergent symmetries are implemented anomalously. The associated infrared theories can also be viewed as surface descriptions of (3+1D topological paramagnets, giving further insight into the dualities. We describe a number of numerical tests of these dualities. We also discuss the possibility of “pseudocritical” behavior for deconfined critical points, and the meaning of the dualities and emergent symmetries in such a scenario.
Dynamic trapping near a quantum critical point
Kolodrubetz, Michael; Katz, Emanuel; Polkovnikov, Anatoli
2015-02-01
The study of dynamics in closed quantum systems has been revitalized by the emergence of experimental systems that are well-isolated from their environment. In this paper, we consider the closed-system dynamics of an archetypal model: spins driven across a second-order quantum critical point, which are traditionally described by the Kibble-Zurek mechanism. Imbuing the driving field with Newtonian dynamics, we find that the full closed system exhibits a robust new phenomenon—dynamic critical trapping—in which the system is self-trapped near the critical point due to efficient absorption of field kinetic energy by heating the quantum spins. We quantify limits in which this phenomenon can be observed and generalize these results by developing a Kibble-Zurek scaling theory that incorporates the dynamic field. Our findings can potentially be interesting in the context of early universe physics, where the role of the driving field is played by the inflaton or a modulus field.
Higgs inflation at the critical point
Bezrukov, Fedor
2014-01-01
Higgs inflation can occur if the Standard Model (SM) is a self-consistent effective field theory up to inflationary scale. This leads to a lower bound on the Higgs boson mass, $M_h \\geq M_{\\text{crit}}$. If $M_h$ is more than a few hundreds of MeV above the critical value, the Higgs inflation predicts the universal values of inflationary indexes, $r\\simeq 0.003$ and $n_s\\simeq 0.97$, independently on the Standard Model parameters. We show that in the vicinity of the critical point $M_{\\text{crit}}$ the inflationary indexes acquire an essential dependence on the mass of the top quark $m_t$ and $M_h$. In particular, the amplitude of the gravitational waves can exceed considerably the universal value.
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.
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.
Dynamical Response near Quantum Critical Points.
Lucas, Andrew; Gazit, Snir; Podolsky, Daniel; Witczak-Krempa, William
2017-02-03
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.
Detecting quantum critical points using bipartite fluctuations.
Rachel, Stephan; Laflorencie, Nicolas; Song, H Francis; Le Hur, Karyn
2012-03-16
We show that the concept of bipartite fluctuations F provides a very efficient tool to detect quantum phase transitions in strongly correlated systems. Using state-of-the-art numerical techniques complemented with analytical arguments, we investigate paradigmatic examples for both quantum spins and bosons. As compared to the von Neumann entanglement entropy, we observe that F allows us to find quantum critical points with much better accuracy in one dimension. We further demonstrate that F can be successfully applied to the detection of quantum criticality in higher dimensions with no prior knowledge of the universality class of the transition. Promising approaches to experimentally access fluctuations are discussed for quantum antiferromagnets and cold gases.
Unbounded critical points for a class of lower semicontinuous functionals
Pellacci, Benedetta; Squassina, Marco
2003-01-01
In this paper we prove existence and multiplicity results of unbounded critical points for a general class of weakly lower semicontinuous functionals. We will apply a suitable nonsmooth critical point theory.
Spectroscopy of the odd-odd chiral candidate nucleus 102Rh
Directory of Open Access Journals (Sweden)
Yavahchova M.S.
2014-03-01
Full Text Available Excited states in 102Rh were populated in the fusion-evaporation reaction 94Zr(11B, 3n102Rh at a beam energy of 36 MeV, using the INGA spectrometer at IUAC, New Delhi. The angular correlations and the electromagnetic character of some of the 03B3-ray transitions observed in 102Rh were investigated in detail. A new candidate for achiral twin band was identified in 102Rh for the first time.
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...
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...
The critical point of quantum chromodynamics through lattice and ...
Indian Academy of Sciences (India)
The Padé approximants are the rational functions. PL. M (z) = .... Deviations from a smooth behaviour near the critical point are visible in these extrap- ... see that there is evidence, albeit statistically not very significant, that the kurtosis changes.
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.; 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.; Blondel, A.; Blumer, J.; Boldizsar, L.; Bravar, A.; Brzychczyk, J.; Bubak, A.; Bunyatov, S.A.; Choi, K.-U.; Chung, P.; Cleymans, J.; Derkach, D.A.; Diakonos, F.; Dominik, W.; Dumarchez, J.; Engel, R.; Ereditato, A.; Feofilov, G.A.; Ferrero, A.; Gazdzicki, M.; Golubeva, M.; Grzeszczuk, A.; Guber, F.; Hasegawa, T.; Haungs, A.; Igolkin, S.; Ivanov, A.S.; Ivashkin, A.; Katrynska, N.; Kielczewska, D.; Kisiel, J.; Kobayashi, T.; Kolev, D.; Kolevatov, R.S.; Kondratiev, V.P.; Kowalski, S.; Kurepin, A.; Lacey, R.; Lyubushkin, V.V.; Majka, Z.; Marchionni, A.; Marcinek, A.; Maris, I.; Matveev, V.; Meregaglia, A.; Messina, M.; Mijakowski, P.; Montaruli, T.; Murphy, S.; Nakadaira, T.; Naumenko, P.A.; Nikolic, V.; Nishikawa, K.; Palczewski, T.; Planeta, R.; Popov, B.A.; Posiadala, M.; Przewlocki, P.; Rauch, W.; Ravonel, M.; Rohrich, D.; Rondio, E.; Rossi, B.; Roth, M.; Rubbia, A.; Sadovsky, A.; Sakashita, K.; Sekiguchi, T.; Seyboth, P.; Shibata, M.; Sissakian, A.N.; Sorin, A.S.; Staszel, P.; Stepaniak, J.; Strabel, C.; Stroebele, H.; Tada, M.; Taranenko, A.; Tsenov, R.; Ulrich, R.; Unger, M.; Vechernin, V.V.; 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.
Defect production in nonlinear quench across a quantum critical point.
Sen, Diptiman; Sengupta, K; Mondal, Shreyoshi
2008-07-04
We show that the defect density n, for a slow nonlinear power-law quench with a rate tau(-1) and an exponent alpha>0, which takes the system through a critical point characterized by correlation length and dynamical critical exponents nu and z, scales as n approximately tau(-alphanud/(alphaznu+1)) [n approximately (alphag((alpha-1)/alpha)/tau)(nud/(znu+1))] if the quench takes the system across the critical point at time t=0 [t=t(0) not = 0], where g is a nonuniversal constant and d is the system dimension. These scaling laws constitute the first theoretical results for defect production in nonlinear quenches across quantum critical points and reproduce their well-known counterpart for a linear quench (alpha=1) as a special case. We supplement our results with numerical studies of well-known models and suggest experiments to test our theory.
The location of the second critical point of water
Kanno, Hitoshi; Miyata, Kuniharu
2006-05-01
Based on the DTA data for homogeneous ice nucleation of emulsified liquid water at low temperatures and high pressures, the location of the second critical point (SCP) of water, which is expected to exist in addition to the normal liquid-vapor critical point, is estimated to be at 145 K pressure). It is shown that SCP is closely associated with the break point of the curve for the homogeneous ice nucleation temperature ( TH) of liquid water and with the transition between low density and high density amorphous solid water (LDA and HDA). Although the existence of SCP has become more realistic, the location seems to be less favorable to the water model of the second-critical-point interpretation.
Universal Postquench Prethermalization at a Quantum Critical Point
Gagel, Pia; Orth, Peter P.; Schmalian, Jörg
2014-11-01
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.
Critical Point in Self-Organized Tissue Growth
Aguilar-Hidalgo, Daniel; Werner, Steffen; Wartlick, Ortrud; González-Gaitán, Marcos; Friedrich, Benjamin M.; Jülicher, Frank
2018-05-01
We present a theory of pattern formation in growing domains inspired by biological examples of tissue development. Gradients of signaling molecules regulate growth, while growth changes these graded chemical patterns by dilution and advection. We identify a critical point of this feedback dynamics, which is characterized by spatially homogeneous growth and proportional scaling of patterns with tissue length. We apply this theory to the biological model system of the developing wing of the fruit fly Drosophila melanogaster and quantitatively identify signatures of the critical point.
Critical point phenomena: universal physics at large length scales
International Nuclear Information System (INIS)
Bruce, A.; Wallace, D.
1993-01-01
This article is concerned with the behaviour of a physical system at, or close to, a critical point (ebullition, ferromagnetism..): study of the phenomena displayed in the critical region (Ising model, order parameter, correlation length); description of the configurations (patterns) formed by the microscopic degrees of freedom near a critical point, essential concepts of the renormalization group (coarse-graining, system flow, fixed-point and scale-invariance); how these concepts knit together to form the renormalization group method; and what kind of problems may be resolved by the renormalization group method. 12 figs., 1 ref
Root and critical point behaviors of certain sums of polynomials
Indian Academy of Sciences (India)
Seon-Hong Kim
2018-04-24
Apr 24, 2018 ... Root and critical point behaviors of certain sums of polynomials. SEON-HONG KIM1,∗. , SUNG YOON KIM2, TAE HYUNG KIM2 and SANGHEON LEE2. 1Department of Mathematics, Sookmyung Women's University, Seoul 140-742, Korea. 2Gyeonggi Science High School, Suwon 440-800, Korea.
A magnetically induced quantum critical point in holography
Gursoy, U.; Gnecchi, A.; Toldo, C.; Papadoulaki, O.
We investigate quantum critical points in a 2+1 dimensional gauge theory at finite chemical potential χ and magnetic field B. The gravity dual is based on 4D NN = 2 Fayet-Iliopoulos gauged supergravity and the solutions we consider — that are constructed analytically — are extremal, dyonic,
Electron self-trapping at quantum and classical critical points
Auslender, M.I.; Katsnelson, M.I.
2006-01-01
Using Feynman path integral technique estimations of the ground state energy have been found for a conduction electron interacting with order parameter fluctuations near quantum critical points. In some cases only singular perturbation theory in the coupling constant emerges for the electron ground
Vector boson excitations near deconfined quantum critical points.
Huh, Yejin; Strack, Philipp; Sachdev, Subir
2013-10-18
We show that the Néel states of two-dimensional antiferromagnets have low energy vector boson excitations in the vicinity of deconfined quantum critical points. We compute the universal damping of these excitations arising from spin-wave emission. Detection of such a vector boson will demonstrate the existence of emergent topological gauge excitations in a quantum spin system.
Spotlighting quantum critical points via quantum correlations at finite temperatures
International Nuclear Information System (INIS)
Werlang, T.; Ribeiro, G. A. P.; Rigolin, Gustavo
2011-01-01
We extend the program initiated by T. Werlang et al. [Phys. Rev. Lett. 105, 095702 (2010)] in several directions. Firstly, we investigate how useful quantum correlations, such as entanglement and quantum discord, are in the detection of critical points of quantum phase transitions when the system is at finite temperatures. For that purpose we study several thermalized spin models in the thermodynamic limit, namely, the XXZ model, the XY model, and the Ising model, all of which with an external magnetic field. We compare the ability of quantum discord, entanglement, and some thermodynamic quantities to spotlight the quantum critical points for several different temperatures. Secondly, for some models we go beyond nearest neighbors and also study the behavior of entanglement and quantum discord for second nearest neighbors around the critical point at finite temperature. Finally, we furnish a more quantitative description of how good all these quantities are in spotlighting critical points of quantum phase transitions at finite T, bridging the gap between experimental data and those theoretical descriptions solely based on the unattainable absolute zero assumption.
Universal post-quench prethermalization at a quantum critical point
Orth, Peter P.; Gagel, Pia; Schmalian, Joerg
2015-03-01
We consider an open system near a quantum critical point that is suddenly moved towards the critical point. The bath-dominated diffusive non-equilibrium 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 a powerlaw rise of order and correlations after an initial collapse of the equilibrium state and a crossover to thermalization that occurs arbitrarily late for sufficiently shallow quenches. [1] P. Gagel, P. P. Orth, J. Schmalian, Phys.Rev. Lett. (in press) arXiv:1406.6387
Multi-critical points in weakly anisotropic magnetic systems
International Nuclear Information System (INIS)
Basten, J.A.J.
1979-02-01
This report starts with a rather extensive presentation of the concepts and ideas which constitute the basis of the modern theory of static critical phenomena. It is shown how at a critical point the semi-phenomenological concepts of universality and scaling are directly related to the divergence of the correlation length and how they are extended to a calculational method for critical behaviour in Wilson's Renormalization-Group (RG) approach. Subsequently the predictions of the molecular-field and RG-theories on the phase transitions and critical behaviour in weakly anisotropic antiferromagnets are treated. In a magnetic field applied along the easy axis, these materials can display an (H,T) phase diagram which contains either a bicritical point or a tetracritical point. Especially the behaviour close to these multi-critical points, as predicted by the extended-scaling theory, is discussed. (Auth.)
Solving the Richardson equations close to the critical points
Energy Technology Data Exchange (ETDEWEB)
DomInguez, F [Departamento de Matematicas, Universidad de Alcala, 28871 Alcala de Henares (Spain); Esebbag, C [Departamento de Matematicas, Universidad de Alcala, 28871 Alcala de Henares (Spain); Dukelsky, J [Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain)
2006-09-15
We study the Richardson equations close to the critical values of the pairing strength g{sub c}, where the occurrence of divergences precludes numerical solutions. We derive a set of equations for determining the critical g values and the non-collapsing pair energies. Studying the behaviour of the solutions close to the critical points, we develop a procedure to solve numerically the Richardson equations for arbitrary coupling strength.
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.
Detection of quantum critical points by a probe qubit.
Zhang, Jingfu; Peng, Xinhua; Rajendran, Nageswaran; Suter, Dieter
2008-03-14
Quantum phase transitions occur when the ground state of a quantum system undergoes a qualitative change when an external control parameter reaches a critical value. Here, we demonstrate a technique for studying quantum systems undergoing a phase transition by coupling the system to a probe qubit. It uses directly the increased sensibility of the quantum system to perturbations when it is close to a critical point. Using an NMR quantum simulator, we demonstrate this measurement technique for two different types of quantum phase transitions in an Ising spin chain.
Slow dynamics at critical points: the field-theoretical perspective
International Nuclear Information System (INIS)
Gambassi, Andrea
2006-01-01
The dynamics at a critical point provides a simple instance of slow collective evolution, characterised by aging phenomena and by a violation of the fluctuation-dissipation relation even for long times. By virtue of the universality in critical phenomena it is possible to provide quantitative predictions for some aspects of these behaviours by field-theoretical methods. We review some of the theoretical results that have been obtained in recent years for the relevant (universal) quantities, such as the fluctuation-dissipation ratio, associated with the non-equilibrium critical dynamics
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
Interplay of quantum and classical fluctuations near quantum critical points
International Nuclear Information System (INIS)
Continentino, Mucio Amado
2011-01-01
For a system near a quantum critical point (QCP), above its lower critical dimension d L , there is in general a critical line of second-order phase transitions that separates the broken symmetry phase at finite temperatures from the disordered phase. The phase transitions along this line are governed by thermal critical exponents that are different from those associated with the quantum critical point. We point out that, if the effective dimension of the QCP, d eff = d + z (d is the Euclidean dimension of the system and z the dynamic quantum critical exponent) is above its upper critical dimension d c there is an intermingle of classical (thermal) and quantum critical fluctuations near the QCP. This is due to the breakdown of the generalized scaling relation ψ = νz between the shift exponent ψ of the critical line and the crossover exponent νz, for d + z > d c by a dangerous irrelevant interaction. This phenomenon has clear experimental consequences, like the suppression of the amplitude of classical critical fluctuations near the line of finite temperature phase transitions as the critical temperature is reduced approaching the QCP. (author)
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.
Optical Studies of Pure Fluids about Their Critical Points
Pang, Kian Tiong
Three optical experiments were performed on pure fluids near their critical points. In the first two setups, CH_3F and H_2C:CF _2 were each tested in a temperature -controlled, prism-shaped cell and a thin parallel-windows cell. In the prism cell, a laser beam was additionally deflected by the fluid present. From the deflection data, the refractive index was related to the density to find the Lorentz-Lorenz function. Critical temperature (T _{c}), density, refractive index and electronic polarizability were found. In the second experiment, a critically-filled, thin parallel-windows cell was placed in one arm of a Mach-Zehnder interoferometer. Fluid density was monitored by changes in the fringe pattern with changing cell temperature. The aim was to improve on the precision of T_{c}: T_{c}{rm (CH}_3 F) = (44cdot9087 +/- 0cdot0002)C; T _{c}{rm(H}_2C:CF _2) = (29cdot7419 +/- 0cdot0001)C; and, to study the coexistence curve and diameter as close to T_{c} as possible. The critical behaviour was compared to the theoretical renormalization group calculations. The derived coefficients were tested against a proposed three-body interaction to explain the field-mixing term in the diameter near the critical point. It was found that H_2C:CF_2 behaved as predicted by such an interaction; CH _3F (and CHF_3) did not. The third experiment was a feasibility study to find out if (critical) isotherms could be measured optically in a setup which combined the prism and parallel-windows cells. The aim was to map isotherms in as wide a range of pressure and density as possible and to probe the critical region directly. Pressure was monitored by a precise digital pressure gauge. CH_3F and CHF _3 were tested in this system. It was found that at low densities, the calculated second and third virial coefficients agreed with reference values. However, the data around the critical point were not accurate enough for use to calculate the critical exponent, delta . The calculated value was
Quantum Critical Point revisited by the Dynamical Mean Field Theory
Xu, Wenhu; Kotliar, Gabriel; Tsvelik, Alexei
Dynamical mean field theory is used to study the quantum critical point (QCP) in the doped Hubbard model on a square lattice. The QCP is characterized by a universal scaling form of the self energy and a spin density wave instability at an incommensurate wave vector. The scaling form unifies the low energy kink and the high energy waterfall feature in the spectral function, while the spin dynamics includes both the critical incommensurate and high energy antiferromagnetic paramagnons. We use the frequency dependent four-point correlation function of spin operators to calculate the momentum dependent correction to the electron self energy. Our results reveal a substantial difference with the calculations based on the Spin-Fermion model which indicates that the frequency dependence of the the quasiparitcle-paramagnon vertices is an important factor. The authors are supported by Center for Computational Design of Functional Strongly Correlated Materials and Theoretical Spectroscopy under DOE Grant DE-FOA-0001276.
Quantum critical point revisited by dynamical mean-field theory
Xu, Wenhu; Kotliar, Gabriel; Tsvelik, Alexei M.
2017-03-01
Dynamical mean-field theory is used to study the quantum critical point (QCP) in the doped Hubbard model on a square lattice. The QCP is characterized by a universal scaling form of the self-energy and a spin density wave instability at an incommensurate wave vector. The scaling form unifies the low-energy kink and the high-energy waterfall feature in the spectral function, while the spin dynamics includes both the critical incommensurate and high-energy antiferromagnetic paramagnons. We use the frequency-dependent four-point correlation function of spin operators to calculate the momentum-dependent correction to the electron self-energy. By comparing with the calculations based on the spin-fermion model, our results indicate the frequency dependence of the quasiparticle-paramagnon vertices is an important factor to capture the momentum dependence in quasiparticle scattering.
Quantum critical point revisited by dynamical mean-field theory
International Nuclear Information System (INIS)
Xu, Wenhu; Kotliar, Gabriel; Rutgers University, Piscataway, NJ; Tsvelik, Alexei M.
2017-01-01
Dynamical mean-field theory is used to study the quantum critical point (QCP) in the doped Hubbard model on a square lattice. We characterize the QCP by a universal scaling form of the self-energy and a spin density wave instability at an incommensurate wave vector. The scaling form unifies the low-energy kink and the high-energy waterfall feature in the spectral function, while the spin dynamics includes both the critical incommensurate and high-energy antiferromagnetic paramagnons. Here, we use the frequency-dependent four-point correlation function of spin operators to calculate the momentum-dependent correction to the electron self-energy. Furthermore, by comparing with the calculations based on the spin-fermion model, our results indicate the frequency dependence of the quasiparticle-paramagnon vertices is an important factor to capture the momentum dependence in quasiparticle scattering.
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.
Thermal conductivity at a disordered quantum critical point
International Nuclear Information System (INIS)
Hartnoll, Sean A.; Ramirez, David M.; Santos, Jorge E.
2016-01-01
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. At no point do we use the replica trick.
International Nuclear Information System (INIS)
Annuar, A.; Gandhi, P.; Alexander, D. M.; Lansbury, G. B.; Moro, A. Del; Arévalo, P.; Ballantyne, D. R.; Baloković, M.; Brightman, M.; Harrison, F. A.; Bauer, F. E.; Boggs, S. E.; Craig, W. W.; Brandt, W. N.; Christensen, F. E.; Hailey, C. J.; Hickox, R. C.; Matt, G.; Puccetti, S.; Ricci, C.
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 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 H ≳ 5 × 10 24 cm −2 . The range of 2–10 keV absorption-corrected luminosity inferred from the best-fitting models is L 2–10,int = (0.8–1.7) × 10 42 erg s −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
Annuar, A.; Gandhi, P.; 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.
2015-12-01
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 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 NH ≳ 5 × 1024 cm-2. The range of 2-10 keV absorption-corrected luminosity inferred from the best-fitting models is L2-10,int = (0.8-1.7) × 1042 erg s-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.
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.
International Nuclear Information System (INIS)
Comerford, Julia M.; Pooley, David; Gerke, Brian F.; Madejski, Greg M.
2011-01-01
We report Chandra observations of a double X-ray source in the z = 0.1569 galaxy SDSS J171544.05+600835.7. The galaxy was initially identified as a dual active galactic nucleus (AGN) candidate based on the double-peaked [O III] λ5007 emission lines, with a line-of-sight velocity separation of 350 km s -1 , in its Sloan Digital Sky Survey spectrum. We used the Kast Spectrograph at Lick Observatory to obtain two long-slit spectra of the galaxy at two different position angles, which reveal that the two Type 2 AGN emission components have not only a velocity offset, but also a projected spatial offset of 1.9 h -1 70 kpc on the sky. Chandra/ACIS observations of two X-ray sources with the same spatial offset and orientation as the optical emission suggest that the galaxy most likely contains Compton-thick dual AGNs, although the observations could also be explained by AGN jets. Deeper X-ray observations that reveal Fe K lines, if present, would distinguish between the two scenarios. The observations of a double X-ray source in SDSS J171544.05+600835.7 are a proof of concept for a new, systematic detection method that selects promising dual AGN candidates from ground-based spectroscopy that exhibits both velocity and spatial offsets in the AGN emission features.
Universal postquench coarsening and aging at a quantum critical point
Gagel, Pia; Orth, Peter P.; Schmalian, Jörg
2015-09-01
The nonequilibrium dynamics of a system that is located in the vicinity of a quantum critical point is affected by the critical slowing down of order-parameter correlations with the potential for novel out-of-equilibrium universality. After a quantum quench, i.e., a sudden change of a parameter in the Hamiltonian, such a system is expected to almost instantly fall out of equilibrium and undergo aging dynamics, i.e., dynamics that depends on the time passed since the quench. Investigating the quantum dynamics of an N -component φ4 model coupled to an external bath, we determine this universal aging and demonstrate that the system undergoes a coarsening, governed by a critical exponent that is unrelated to the equilibrium exponents of the system. We analyze this behavior in the large-N limit, which is complementary to our earlier renormalization-group analysis, allowing in particular the direct investigation of the order-parameter dynamics in the symmetry-broken phase and at the upper critical dimension. By connecting the long-time limit of fluctuations and response, we introduce a distribution function that shows that the system remains nonthermal and exhibits quantum coherence even on long time scales.
Effective intermolecular potential and critical point for C60 molecule
Ramos, J. Eloy
2017-07-01
The approximate nonconformal (ANC) theory is applied to the C60 molecule. A new binary potential function is developed for C60, which has three parameters only and is obtained by averaging the site-site carbon interactions on the surface of two C60 molecules. It is shown that the C60 molecule follows, to a good approximation, the corresponding states principle with n-C8H18, n-C4F10 and n-C5F12. The critical point of C60 is estimated in two ways: first by applying the corresponding states principle under the framework of the ANC theory, and then by using previous computer simulations. The critical parameters obtained by applying the corresponding states principle, although very different from those reported in the literature, are consistent with the previous results of the ANC theory. It is shown that the Girifalco potential does not correspond to an average of the site-site carbon-carbon interaction.
Equilibration of matter near the QCD critical point
International Nuclear Information System (INIS)
Bravina, L V; Arsene, I; Nilsson, M S; Tywoniuk, K; Zabrodin, E E
2006-01-01
The relaxation of hot and dense nuclear matter to local equilibrium in the central zone of heavy-ion collisions at energies around 40 A GeV is studied within the microscopic transport model. Dynamical calculations performed for the central cell in the reaction are compared to the predictions of the thermal statistical model. It is found that kinetic, thermal and chemical equilibrations of the expanding hadronic matter are nearly approached for the period of 10-18 fm/c. Within this time, the matter in the cell expands almost isentropically. It is quite interesting that in the T-μ B plane the system crosses the critical point predicted by lattice QCD calculations. Similar to the cells studied at lower (AGS) and higher (SPS, RHIC) energies, the central cell at 40 A GeV possesses negative (though small) net strangeness. Several peculiarities are observed as well. These features can be attributed to the transition from baryon-dominated to meson-dominated matter, discussed recently
Energy scales and magnetoresistance at a quantum critical point
Energy Technology Data Exchange (ETDEWEB)
Shaginyan, V.R. [Petersburg Nuclear Physics Institute, RAS, Gatchina, 188300 (Russian Federation); Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); CTSPS, Clark Atlanta University, Atlanta, GA 30314 (United States)], E-mail: vrshag@thd.pnpi.spb.ru; Amusia, M.Ya. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Msezane, A.Z. [CTSPS, Clark Atlanta University, Atlanta, GA 30314 (United States); Popov, K.G. [Komi Science Center, Ural Division, RAS, 3a Chernova street, Syktyvkar, 167982 (Russian Federation); Stephanovich, V.A. [Opole University, Institute of Mathematics and Informatics, Opole, 45-052 (Poland)
2009-03-02
The magnetoresistance (MR) of CeCoIn{sub 5} is notably different from that in many conventional metals. We show that a pronounced crossover from negative to positive MR at elevated temperatures and fixed magnetic fields is determined by the scaling behavior of quasiparticle effective mass. At a quantum critical point (QCP) this dependence generates kinks (crossover points from fast to slow growth) in thermodynamic characteristics (like specific heat, magnetization, etc.) at some temperatures when a strongly correlated electron system transits from the magnetic field induced Landau-Fermi liquid (LFL) regime to the non-Fermi liquid (NFL) one taking place at rising temperatures. We show that the above kink-like peculiarity separates two distinct energy scales in QCP vicinity - low temperature LFL scale and high temperature one related to NFL regime. Our comprehensive theoretical analysis of experimental data permits to reveal for the first time new MR and kinks scaling behavior as well as to identify the physical reasons for above energy scales.
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.
Scanning electron microscope autoradiography of critical point dried biological samples
International Nuclear Information System (INIS)
Weiss, R.L.
1980-01-01
A technique has been developed for the localization of isotopes in the scanning electron microscope. Autoradiographic studies have been performed using a model system and a unicellular biflagellate alga. One requirement of this technique is that all manipulations be carried out on samples that are maintained in a liquid state. Observations of a source of radiation ( 125 I-ferritin) show that the nuclear emulsion used to detect radiation is active under these conditions. Efficiency measurement performed using 125 I-ferritin indicate that 125 I-SEM autoradiography is an efficient process that exhibits a 'dose dependent' response. Two types of labeling methods were used with cells, surface labeling with 125 I and internal labeling with 3 H. Silver grains appeared on labeled cells after autoradiography, removal of residual gelatin and critical point drying. The location of grains was examined on a flagellated green alga (Chlamydomonas reinhardi) capable of undergoing cell fusion. Fusion experiments using labeled and unlabeled cells indicate that 1. Labeling is specific for incorporated radioactivity; 2. Cell surface structure is preserved in SEM autoradiographs and 3. The technique appears to produce reliable autoradiographs. Thus scanning electron microscope autoradiography should provide a new and useful experimental approach
Discovery of a Mid-infrared Echo from the TDE Candidate in the Nucleus of ULIRG F01004−2237
Energy Technology Data Exchange (ETDEWEB)
Dou, Liming [Center for Astrophysics, Guangzhou University, Guangzhou 510006 (China); Wang, Tinggui; Jiang, Ning; Yang, Chenwei; Peng, Bo [CAS Key Laboratory for Researches in Galaxies and Cosmology, University of Sciences and Technology of China, Hefei, Anhui 230026 (China); Yan, Lin [Caltech Optical Observatories, Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Cutri, Roc M. [IPAC, Mail Code 100-22, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125 (United States); Mainzer, Amy, E-mail: doulm@gzhu.edu.cn, E-mail: twang@ustc.edu.cn, E-mail: lyan@ipac.caltech.edu [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
2017-05-20
We present the mid-infrared (MIR) light curves (LCs) of a tidal disruption event candidate in the center of a nearby ultraluminous infrared galaxy F01004−2237 using archival WISE and NEOWISE data from 2010 to 2016. At the peak of the optical flare, F01004−2237 was IR quiescent. About three years later, its MIR fluxes have shown a steady increase, rising by 1.34 and 1.04 mag in 3.4 and 4.6 μ m up to the end of 2016. The host-subtracted MIR peak luminosity is 2–3 × 10{sup 44} erg s{sup −1}. We interpret the MIR LCs as an infrared echo, i.e., dust reprocessed emission of the optical flare. Fitting the MIR LCs using our dust model, we infer a dust torus of the size of a few parsecs at some inclined angle. The derived dust temperatures range from 590–850 K, and the warm dust mass is ∼7 M {sub ⊙}. Such a large mass implies that the dust cannot be newly formed. We also derive the UV luminosity of 4–11 × 10{sup 44} erg s{sup −1}. The inferred total IR energy is 1–2 × 10{sup 52} erg, suggesting a large dust covering factor. Finally, our dust model suggests that the long tail of the optical flare could be due to dust scattering.
Two critical tests for the Critical Point earthquake
Tzanis, A.; Vallianatos, F.
2003-04-01
It has been credibly argued that the earthquake generation process is a critical phenomenon culminating with a large event that corresponds to some critical point. In this view, a great earthquake represents the end of a cycle on its associated fault network and the beginning of a new one. The dynamic organization of the fault network evolves as the cycle progresses and a great earthquake becomes more probable, thereby rendering possible the prediction of the cycle’s end by monitoring the approach of the fault network toward a critical state. This process may be described by a power-law time-to-failure scaling of the cumulative seismic release rate. Observational evidence has confirmed the power-law scaling in many cases and has empirically determined that the critical exponent in the power law is typically of the order n=0.3. There are also two theoretical predictions for the value of the critical exponent. Ben-Zion and Lyakhovsky (Pure appl. geophys., 159, 2385-2412, 2002) give n=1/3. Rundle et al. (Pure appl. geophys., 157, 2165-2182, 2000) show that the power-law activation associated with a spinodal instability is essentially identical to the power-law acceleration of Benioff strain observed prior to earthquakes; in this case n=0.25. More recently, the CP model has gained support from the development of more dependable models of regional seismicity with realistic fault geometry that show accelerating seismicity before large events. Essentially, these models involve stress transfer to the fault network during the cycle such, that the region of accelerating seismicity will scale with the size of the culminating event, as for instance in Bowman and King (Geophys. Res. Let., 38, 4039-4042, 2001). It is thus possible to understand the observed characteristics of distributed accelerating seismicity in terms of a simple process of increasing tectonic stress in a region already subjected to stress inhomogeneities at all scale lengths. Then, the region of
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.
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.
Critical point dewetting: competition between the gravity and the dispersion force
International Nuclear Information System (INIS)
Ohmasa, Y; Takahashi, S; Fujii, K; Yao, M
2008-01-01
Near the critical temperature of an immiscible binary liquid system, a solid substrate is usually covered completely by one of the liquid phases. This phenomenon is called the 'critical point wetting , which is predicted by Cahn in 1977, and have been confirmed for many fluid systems experimentally. However, we found that liquid Se-Tl system on a quartz substrate does not show the critical point wetting near the liquid-liquid critical point. On a contrary, when the temperature goes down from the critical point, a Se-rich wetting film intrudes between the Tl-rich bulk liquid and the quartz wall. This result is a clear evidence of the 'critical point dewetting' phenomenon. It is suggested from a theoretical consideration that the critical point dewetting takes place as a result of the competition between the long-range dispersion force and the gravity
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
An assessment of the melting, boiling, and critical point data of the alkali metals
International Nuclear Information System (INIS)
Ohse, R.W.; Babelot, J.F.; Magill, J.
1985-01-01
The measured melting, boiling and critical point data of the alkali metals are reviewed. Emphasis has been given to the assessment of the critical point data. The main experimental techniques for measurements in the critical region are described. The selected data are given. Best estimates of the critical constants of lithium are given. (author)
Susceptibilities from a black hole engineered EoS with a critical point
International Nuclear Information System (INIS)
Portillo, Israel
2017-01-01
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 µ 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 µB = 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. (paper)
Robustness of critical points in a complex adaptive system: Effects of hedge behavior
Liang, Yuan; Huang, Ji-Ping
2013-08-01
In our recent papers, we have identified a class of phase transitions in the market-directed resource-allocation game, and found that there exists a critical point at which the phase transitions occur. The critical point is given by a certain resource ratio. Here, by performing computer simulations and theoretical analysis, we report that the critical point is robust against various kinds of human hedge behavior where the numbers of herds and contrarians can be varied widely. This means that the critical point can be independent of the total number of participants composed of normal agents, herds and contrarians, under some conditions. This finding means that the critical points we identified in this complex adaptive system (with adaptive agents) may also be an intensive quantity, similar to those revealed in traditional physical systems (with non-adaptive units).
An assessment of the melting, boiling, and critical point data of the alkali metals
International Nuclear Information System (INIS)
Ohse, R.W.; Babelot, J.-F.; Magill, J.
1985-01-01
The paper reviews the measured melting, boiling and critical point data of alkali metals. A survey of the static heat generation methods for density and pressure-volume-temperature measurements is given. Measured data on the melting and boiling temperatures of lithium, sodium, potassium, rubidium and caesium are summarised. Also measured critical point data for the same five alkali metals are presented, and discussed. (U.K.)
Model for a Ferromagnetic Quantum Critical Point in a 1D Kondo Lattice
Komijani, Yashar; Coleman, Piers
2018-04-01
Motivated by recent experiments, we study a quasi-one-dimensional model of a Kondo lattice with ferromagnetic coupling between the spins. Using bosonization and dynamical large-N techniques, we establish the presence of a Fermi liquid and a magnetic phase separated by a local quantum critical point, governed by the Kondo breakdown picture. Thermodynamic properties are studied and a gapless charged mode at the quantum critical point is highlighted.
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.
Visualizing Robustness of Critical Points for 2D Time-Varying Vector Fields
Wang, B.; Rosen, P.; Skraba, P.; Bhatia, H.; Pascucci, V.
2013-01-01
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.
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.
Matter fields near quantum critical point in (2+1)-dimensional U(1) gauge theory
International Nuclear Information System (INIS)
Liu Guozhu; Li Wei; Cheng Geng
2010-01-01
We study chiral phase transition and confinement of matter fields in (2+1)-dimensional U(1) gauge theory of massless Dirac fermions and scalar bosons. The vanishing scalar boson mass, r=0, defines a quantum critical point between the Higgs phase and the Coulomb phase. We consider only the critical point r=0 and the Coulomb phase with r>0. The Dirac fermion acquires a dynamical mass when its flavor is less than certain critical value N f c , which depends quantitatively on the flavor N b and the scalar boson mass r. When N f f c , the matter fields carrying internal gauge charge are all confined if r≠0 but are deconfined at the quantum critical point r=0. The system has distinct low-energy elementary excitations at the critical point r=0 and in the Coulomb phase with r≠0. We calculate the specific heat and susceptibility of the system at r=0 and r≠0, which can help to detect the quantum critical point and to judge whether dynamical fermion mass generation takes place.
International Nuclear Information System (INIS)
Jaqaman, H.R.
1977-01-01
The nucleus--nucleus interaction is studied within the framework of the generator coordinate method that permits an easy incorporation of the full effects of antisymmetrization. It is found that the interaction, as far as the elastic scattering problem is concerned, can be described by a simple effective potential that is equivalent to the original many-body (and hence non-local) problem. The potential is obtained by dividing the wavefunction into a long-range part and a short-range part and requiring the former to satisfy a Schroedinger equation. This enables avoiding dealing with the troublesome short-range part of the wavefunction and provides a direct link with the optical model so that the potential obtained here is equivalent to the real part of the optical potential (the imaginary part is not investigated). The effective potential is found to consist of three parts: an interaction term between the nucleons belonging to different nuclei, a kinetic energy term due to the change in the intrinsic kinetic energy of the system as a result of the antisymmetrization, and finally an l-dependent part. The kinetic energy term is found to be very repulsive and effectively gives a hard core, and is calculated for the α--α and 16 O-- 16 O cases. The full potential is calculated for the α--α case for the S, D, and G partial waves and then used to calculate the corresponding phase shifts that are then compared with experimental results and other microscopic calculations. Finally, some recent results and analyses of fusion and deep inelastic reactions are reviewed that seem to indicate the presence of a hard core in the nucleus--nucleus potential. Such a hard core is present in the potential obtained in the sudden approximation
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.
Completely mixed state is a critical point for three-qubit entanglement
International Nuclear Information System (INIS)
Tamaryan, Sayatnova
2011-01-01
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.
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.
Universal conductance and conductivity at critical points in integer quantum Hall systems.
Schweitzer, L; Markos, P
2005-12-16
The sample averaged longitudinal two-terminal conductance and the respective Kubo conductivity are calculated at quantum critical points in the integer quantum Hall regime. In the limit of large system size, both transport quantities are found to be the same within numerical uncertainty in the lowest Landau band, and , respectively. In the second-lowest Landau band, a critical conductance is obtained which indeed supports the notion of universality. However, these numbers are significantly at variance with the hitherto commonly believed value . We argue that this difference is due to the multifractal structure of critical wave functions, a property that should generically show up in the conductance at quantum critical points.
Molecular dynamics simulation of a binary mixture near the lower critical point
Energy Technology Data Exchange (ETDEWEB)
Pousaneh, Faezeh; Edholm, Olle, E-mail: oed@kth.se [Theoretical Biological Physics, Department of Theoretical Physics, Royal Institute of Technology (KTH), AlbaNova University Center, SE-106 91 Stockholm (Sweden); Maciołek, Anna [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3, D-70569 Stuttgart (Germany)
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.
International Nuclear Information System (INIS)
March, N.H.
2003-08-01
Sarkisov (J. Chem. Phys. 119, 373, 2003) has recently discussed the structural behaviour of a simple fluid near the liquid-vapour critical point. His work, already compared with computer simulation studies, is here brought into direct contact for the heavier condensed rare gases Ar, Kr and Xe with (a) experiment and (b) earlier theoretical investigations. Directions for future studies then emerge. (author)
One-norm geometric quantum discord and critical point estimation in the XY spin chain
Energy Technology Data Exchange (ETDEWEB)
Cheng, Chang-Cheng; Wang, Yao; Guo, Jin-Liang, E-mail: guojinliang80@163.com
2016-11-15
In contrast with entanglement and quantum discord (QD), we investigate the thermal quantum correlation in terms of Schatten one-norm geometric quantum discord (GQD) in the XY spin chain, and analyze their capabilities in detecting the critical point of quantum phase transition. We show that the one-norm GQD can reveal more properties about quantum correlation between two spins, especially for the long-range quantum correlation at finite temperature. Under the influences of site distance, anisotropy and temperature, one-norm GQD and its first derivative make it possible to detect the critical point efficiently for a general XY spin chain. - Highlights: • Comparing with entanglement and QD, one-norm GQD is more robust versus the temperature. • One-norm GQD is more efficient in characterization of long-range quantum correlation between two distant qubits. • One-norm GQD performs well in highlighting the critical point of QPT at zero or low finite temperature. • One-norm GQD has a number of advantages over QD in detecting the critical point of the spin chain.
Hierarchy of exactly solvable spin-1/2 chains with so (N)_I critical points
Lahtinen, V.; Mansson, T.; Ardonne, E.
2014-01-01
We construct a hierarchy of exactly solvable spin-1/2 chains with so(N)1 critical points. Our construction is based on the framework of condensate-induced transitions between topological phases. We employ this framework to construct a Hamiltonian term that couples N transverse field Ising chains
Critical points for finite Fibonacci chains of point delta-interactions and orthogonal polynomials
International Nuclear Information System (INIS)
De Prunele, E
2011-01-01
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)
Critical point relascope sampling for unbiased volume estimation of downed coarse woody debris
Jeffrey H. Gove; Michael S. Williams; Mark J. Ducey; Mark J. Ducey
2005-01-01
Critical point relascope sampling is developed and shown to be design-unbiased for the estimation of log volume when used with point relascope sampling for downed coarse woody debris. The method is closely related to critical height sampling for standing trees when trees are first sampled with a wedge prism. Three alternative protocols for determining the critical...
An Improved Computational Method for the Calculation of Mixture Liquid-Vapor Critical Points
Dimitrakopoulos, Panagiotis; Jia, Wenlong; Li, Changjun
2014-05-01
Knowledge of critical points is important to determine the phase behavior of a mixture. This work proposes a reliable and accurate method in order to locate the liquid-vapor critical point of a given mixture. The theoretical model is developed from the rigorous definition of critical points, based on the SRK equation of state (SRK EoS) or alternatively, on the PR EoS. In order to solve the resulting system of nonlinear equations, an improved method is introduced into an existing Newton-Raphson algorithm, which can calculate all the variables simultaneously in each iteration step. The improvements mainly focus on the derivatives of the Jacobian matrix, on the convergence criteria, and on the damping coefficient. As a result, all equations and related conditions required for the computation of the scheme are illustrated in this paper. Finally, experimental data for the critical points of 44 mixtures are adopted in order to validate the method. For the SRK EoS, average absolute errors of the predicted critical-pressure and critical-temperature values are 123.82 kPa and 3.11 K, respectively, whereas the commercial software package Calsep PVTSIM's prediction errors are 131.02 kPa and 3.24 K. For the PR EoS, the two above mentioned average absolute errors are 129.32 kPa and 2.45 K, while the PVTSIM's errors are 137.24 kPa and 2.55 K, respectively.
Understanding and Modeling the Evolution of Critical Points under Gaussian Blurring
Kuijper, A.; Florack, L.M.J.; Heyden, A.; Sparr, G.; Nielsen, M.; Johansen, P.
2002-01-01
In order to investigate the deep structure of Gaussian scale space images, one needs to understand the behaviour of critical points under the influence of parameter-driven blurring. During this evolution two different types of special points are encountered, the so-called scale space saddles and the
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.
Shift of critical points in the parametrically modulated Henon map with coexisting attractors
International Nuclear Information System (INIS)
Saucedo-Solorio, J.M.; Pisarchik, A.N.; Aboites, V.
2002-01-01
We study how the critical point positions change in the parametrically modulated Henon map with coexisting period-1 and period-3 attractors. In particular, a new type of scaling law is found coinciding with that evidenced by laser experiments. We show that resonance phenomena play a crucial role in deformation of attractors and their basins of attraction
Pseudo-critical point in anomalous phase diagrams of simple plasma models
International Nuclear Information System (INIS)
Chigvintsev, A Yu; Iosilevskiy, I L; Noginova, L Yu
2016-01-01
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 < Z < Z 2 ). The most remarkable is appearance of pseudo-critical points at both boundary values Z = Z 1 ≈ 35.5 and Z = Z 2 ≈ 40.0. It should be stressed that critical isotherm is exactly cubic in both these pseudo-critical points. In this study we have improved our previous calculations and utilized more complicated model components equation of state provided by Chabrier and Potekhin (1998 Phys. Rev. E 58 4941). (paper)
Temperature dependence of the interband critical points of bulk Ge and strained Ge on Si
Fernando, Nalin S.; Nunley, T. Nathan; Ghosh, Ayana; Nelson, Cayla M.; Cooke, Jacqueline A.; Medina, Amber A.; Zollner, Stefan; Xu, Chi; Menendez, Jose; Kouvetakis, John
2017-11-01
Epitaxial Ge layers on a Si substrate experience a tensile biaxial stress due to the difference between the thermal expansion coefficients of the Ge epilayer and the Si substrate, which can be measured using asymmetric X-ray diffraction reciprocal space maps. This stress depends on temperature and affects the band structure, interband critical points, and optical spectra. This manuscripts reports careful measurements of the temperature dependence of the dielectric function and the interband critical point parameters of bulk Ge and Ge epilayers on Si using spectroscopic ellipsometry from 80 to 780 K and from 0.8 to 6.5 eV. The authors find a temperature-dependent redshift of the E1 and E1 + Δ1 critical points in Ge on Si (relative to bulk Ge). This redshift can be described well with a model based on thermal expansion coefficients, continuum elasticity theory, and the deformation potential theory for interband transitions. The interband transitions leading to E0‧ and E2 critical points have lower symmetry and therefore are not affected by the stress.
Flow topology of rare back flow events and critical points in turbulent channels and toroidal pipes
Chin, C.; Vinuesa, R.; Örlü, R.; Cardesa, J. I.; Noorani, A.; Schlatter, P.; Chong, M. S.
2018-04-01
A study of the back flow events and critical points in the flow through a toroidal pipe at friction Reynolds number Re τ ≈ 650 is performed and compared with the results in a turbulent channel flow at Re τ ≈ 934. The statistics and topological properties of the back flow events are analysed and discussed. Conditionally-averaged flow fields in the vicinity of the back flow event are obtained, and the results for the torus show a similar streamwise wall-shear stress topology which varies considerably for the spanwise wall-shear stress when compared to the channel flow. The comparison between the toroidal pipe and channel flows also shows fewer back flow events and critical points in the torus. This cannot be solely attributed to differences in Reynolds number, but is a clear effect of the secondary flow present in the toroidal pipe. A possible mechanism is the effect of the secondary flow present in the torus, which convects momentum from the inner to the outer bend through the core of the pipe, and back from the outer to the inner bend through the pipe walls. In the region around the critical points, the skin-friction streamlines and vorticity lines exhibit similar flow characteristics with a node and saddle pair for both flows. These results indicate that back flow events and critical points are genuine features of wall-bounded turbulence, and are not artifacts of specific boundary or inflow conditions in simulations and/or measurement uncertainties in experiments.
Electric conductivity of alkali metal vapors in the region of critical point
International Nuclear Information System (INIS)
Likal'ter, A.A.
1982-01-01
A behaviour of alkali metal conductivity in the vicinity of a critical point has been analyzed on the base of deVeloped representations on a vapor state. A phenomenological conductivity theory has been developed, which is in a good agreement with experimental data obtained
Czech Academy of Sciences Publication Activity Database
Kouhia, R.; Tůma, Miroslav; Mäkinen, J.; Fedoroff, A.; Marjamäki, H.
108-109, October (2012), s. 110-117 ISSN 0045-7949 R&D Projects: GA ČR(CZ) GAP108/11/0853 Institutional research plan: CEZ:AV0Z10300504 Keywords : non-linear eigenvalue problem * equilibrium equations * critical points * preconditioned iterations Subject RIV: BA - General Mathematics Impact factor: 1.509, year: 2012
Nucleus Ruber of Actinopterygians.
Nakayama, Tomoya; Miyajima, Satoshi; Nishino, Hirotaka; Narita, Junya; Abe, Hideki; Yamamoto, Naoyuki
2016-01-01
Nucleus ruber is known as an important supraspinal center that controls forelimb movements in tetrapods, and the rubral homologue may serve similar functions in fishes (motor control of pectoral fin). However, two apparently different structures have been identified as 'nucleus ruber' in actinopterygians. One is nucleus ruber of Goldstein (1905) (NRg), and the other nucleus ruber of Nieuwenhuys and Pouwels (1983) (NRnp). It remains unclear whether one of these nuclei (or perhaps both) is homologous to tetrapod nucleus ruber. To resolve this issue from a phylogenetic point of view, we have investigated the distribution of tegmental neurons retrogradely labeled from the spinal cord in eight actinopterygian species. We also investigated the presence/absence of the two nuclei with Nissl- or Bodian-stained brain section series of an additional 28 actinopterygian species by comparing the morphological features of candidate rubral neurons with those of neurons revealed by the tracer studies. Based on these analyses, the NRg was identified in all actinopterygians investigated in the present study, while the NRnp appears to be absent in basal actinopterygians. The phylogenetic distribution pattern indicates that the NRg is the more likely homologue of nucleus ruber, and the NRnp may be a derived nucleus that emerged during the course of actinopterygian evolution. © 2016 S. Karger AG, Basel.
Elliptic Euler–Poisson–Darboux equation, critical points and integrable systems
International Nuclear Information System (INIS)
Konopelchenko, B G; Ortenzi, G
2013-01-01
The structure and properties of families of critical points for classes of functions W(z, z-bar ) obeying the elliptic Euler–Poisson–Darboux equation E(1/2, 1/2) are studied. General variational and differential equations governing the dependence of critical points in variational (deformation) parameters are found. Explicit examples of the corresponding integrable quasi-linear differential systems and hierarchies are presented. There are the extended dispersionless Toda/nonlinear Schrödinger hierarchies, the ‘inverse’ hierarchy and equations associated with the real-analytic Eisenstein series E(β, β-bar ;1/2) among them. The specific bi-Hamiltonian structure of these equations is also discussed. (paper)
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.
Fermionic quantum critical point of spinless fermions on a honeycomb lattice
International Nuclear Information System (INIS)
Wang, Lei; Corboz, Philippe; Troyer, Matthias
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 the Ising order parameter to the Dirac fermions at low energy drastically affects the quantum critical behavior. Encouraged by a recent discovery (Huffman and Chandrasekharan 2014 Phys. Rev. B 89 111101) of the absence of the fermion sign problem in this model, we study the fermionic quantum critical point using the continuous-time quantum Monte Carlo method with a worm-sampling technique. We estimate the transition point V/t=1.356(1) with the critical exponents ν=0.80(3) and η=0.302(7). Compatible results for the transition point are also obtained with infinite projected entangled-pair states. (paper)
Entanglement entropy of 2D conformal quantum critical points: hearing the shape of a quantum drum.
Fradkin, Eduardo; Moore, Joel E
2006-08-04
The entanglement entropy of a pure quantum state of a bipartite system A union or logical sumB is defined as the von Neumann entropy of the reduced density matrix obtained by tracing over one of the two parts. In one dimension, the entanglement of critical ground states diverges logarithmically in the subsystem size, with a universal coefficient that for conformally invariant critical points is related to the central charge of the conformal field theory. We find that the entanglement entropy of a standard class of z=2 conformal quantum critical points in two spatial dimensions, in addition to a nonuniversal "area law" contribution linear in the size of the AB boundary, generically has a universal logarithmically divergent correction, which is completely determined by the geometry of the partition and by the central charge of the field theory that describes the critical wave function.
Singularity of the London penetration depth at quantum critical points in superconductors.
Chowdhury, Debanjan; Swingle, Brian; Berg, Erez; Sachdev, Subir
2013-10-11
We present a general theory of the singularity in the London penetration depth at symmetry-breaking and topological quantum critical points within a superconducting phase. While the critical exponents and ratios of amplitudes on the two sides of the transition are universal, an overall sign depends upon the interplay between the critical theory and the underlying Fermi surface. We determine these features for critical points to spin density wave and nematic ordering, and for a topological transition between a superconductor with Z2 fractionalization and a conventional superconductor. We note implications for recent measurements of the London penetration depth in BaFe2(As(1-x)P(x))2 [K. Hashimoto et al., Science 336, 1554 (2012)].
Conductivity of Weakly Disordered Metals Close to a "Ferromagnetic" Quantum Critical Point
Kastrinakis, George
2018-05-01
We calculate analytically the conductivity of weakly disordered metals close to a "ferromagnetic" quantum critical point in the low-temperature regime. Ferromagnetic in the sense that the effective carrier potential V(q,ω ), due to critical fluctuations, is peaked at zero momentum q=0. Vertex corrections, due to both critical fluctuations and impurity scattering, are explicitly considered. We find that only the vertex corrections due to impurity scattering, combined with the self-energy, generate appreciable effects as a function of the temperature T and the control parameter a, which measures the proximity to the critical point. Our results are consistent with resistivity experiments in several materials displaying typical Fermi liquid behaviour, but with a diverging prefactor of the T^2 term for small a.
Finite Blaschke products with prescribed critical points, Stieltjes polynomials, and moment problems
Semmler, Gunter; Wegert, Elias
2017-09-01
The determination of a finite Blaschke product from its critical points is a well-known problem with interrelations to several other topics. Though existence and uniqueness of solutions are established for long, we present new aspects which have not yet been explored to their full extent. In particular, we show that the following three problems are equivalent: (i) determining a finite Blaschke product from its critical points, (ii) finding the equilibrium position of moveable point charges interacting with a special configuration of fixed charges, and (iii) solving a moment problem for the canonical representation of power moments on the real axis. These equivalences are not only of theoretical interest, but also open up new perspectives for the design of algorithms. For instance, the second problem is closely linked to the determination of certain Stieltjes and Van Vleck polynomials for a second order ODE and characterizes solutions as global minimizers of an energy functional.
Critical point of Nf=3 QCD from lattice simulations in the canonical ensemble
International Nuclear Information System (INIS)
Li Anyi; Alexandru, Andrei; Liu, Keh-Fei
2011-01-01
A canonical ensemble algorithm is employed to study the phase diagram of N f =3 QCD using lattice simulations. We lock in the desired quark number sector using an exact Fourier transform of the fermion determinant. We scan the phase space below T c and look for an S-shape structure in the chemical potential, which signals the coexistence phase of a first order phase transition in finite volume. Applying Maxwell construction, we determine the boundaries of the coexistence phase at three temperatures and extrapolate them to locate the critical point. Using an improved gauge action and improved Wilson fermions on lattices with a spatial extent of 1.8 fm and quark masses close to that of the strange, we find the critical point at T E =0.925(5)T c and baryon chemical potential μ B E =2.60(8)T c .
Searching for the QCD Critical Point with the Energy Dependence of pt Fluctuations
Novak, John; STAR Collaboration
2013-10-01
If systems produced in relativistic heavy-ion collisions pass near the QCD critical point while cooling, the correlation length of the system may diverge due to the phenomena of critical opalescence. The transverse momentum distribution, being related to the state variable temperature, might be sensitive to this change in correlation length. Non-monotonic behavior with changing incident energy or centrality of any transverse momentum observable that is sensitive to the correlation length could thus be indicative of the QCD critical point. Accordingly, we report measurements related to transverse momentum fluctuations such as as a function of event centrality and incident energy for Au+Au collisions at √{sNN} = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV using the STAR detector at RHIC. The results are compared to UrQMD model predictions and previous experimental measurements.
Precise Determination of Quantum Critical Points by the Violation of the Entropic Area Law
Xavier, J. C.; Alcaraz, F. C.
2011-01-01
Finite-size scaling analysis turns out to be a powerful tool to calculate the phase diagram as well as the critical properties of two dimensional classical statistical mechanics models and quantum Hamiltonians in one dimension. The most used method to locate quantum critical points is the so called crossing method, where the estimates are obtained by comparing the mass gaps of two distinct lattice sizes. The success of this method is due to its simplicity and the ability to provide accurate r...
Wang, Qian; Qin, Pinquan; Wang, Wen-ge
2015-10-01
Based on an analysis of Feynman's path integral formulation of the propagator, a relative criterion is proposed for validity of a semiclassical approach to the dynamics near critical points in a class of systems undergoing quantum phase transitions. It is given by an effective Planck constant, in the relative sense that a smaller effective Planck constant implies better performance of the semiclassical approach. Numerical tests of this relative criterion are given in the XY model and in the Dicke model.
Morishige, Kunimitsu
2009-06-02
To examine the mechanisms for capillary condensation and for capillary evaporation in porous glass, we measured the hysteresis critical points and desorption scanning curves of nitrogen in four kinds of porous glasses with different pore sizes (Vycor, CPG75A, CPG120A, and CPG170A). The shapes of the hysteresis loop in the adsorption isotherm of nitrogen for the Vycor and the CPG75A changed with temperature, whereas those for the CPG120A and the CPG170A remained almost unchanged with temperature. The hysteresis critical points for the Vycor and the CPG75A fell on the common line observed previously for ordered mesoporous silicas. On the other hand, the hysteresis critical points for the CPG120A and the CPG170A deviated appreciably from the common line. This strongly suggests that capillary evaporation of nitrogen in the interconnected and disordered pores of both the Vycor and the CPG75A follows a cavitation process at least in the vicinity of their hysteresis critical temperatures in the same way as that in the cagelike pores of the ordered silicas, whereas the hysteresis critical points in the CPG120A and the CPG170A have origin different from that in the cagelike pores. The desorption scanning curves for the CPG75A indicated the nonindependence of the porous domains. On the other hand, for both the CPG120A and the CPG170A, we obtained the scanning curves that are expected from the independent domain theory. All these results suggest that sample spanning transitions in capillary condensation and evaporation take place inside the interconnected pores of both the CPG120A and the CPG170A.
Energy Technology Data Exchange (ETDEWEB)
Barlow, Nathaniel S., E-mail: nsbsma@rit.edu [School of Mathematical Sciences, Rochester Institute of Technology, Rochester, New York 14623 (United States); Schultz, Andrew J., E-mail: ajs42@buffalo.edu; Kofke, David A., E-mail: kofke@buffalo.edu [Department of Chemical and Biological Engineering, University at Buffalo, State University of New York, Buffalo, New York 14260 (United States); Weinstein, Steven J., E-mail: sjweme@rit.edu [Department of Chemical Engineering, Rochester Institute of Technology, Rochester, New York 14623 (United States)
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.
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.
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 points at both boundary values Z = Z 1 ≈ 35.5 and Z = Z 2 ≈ 40.0. It should be stressed that critical isotherm is exactly cubic in both these pseudo-critical points. In this study we have improved our previous calculations and utilized more complicated model components equation of state provided by Chabrier and Potekhin (1998 Phys. Rev. E 58 4941).
Merli, Marcello; Pavese, Alessandro
2018-03-01
The critical points analysis of electron density, i.e. ρ(x), from ab initio calculations is used in combination with the catastrophe theory to show a correlation between ρ(x) topology and the appearance of instability that may lead to transformations of crystal structures, as a function of pressure/temperature. In particular, this study focuses on the evolution of coalescing non-degenerate critical points, i.e. such that ∇ρ(x c ) = 0 and λ 1 , λ 2 , λ 3 ≠ 0 [λ being the eigenvalues of the Hessian of ρ(x) at x c ], towards degenerate critical points, i.e. ∇ρ(x c ) = 0 and at least one λ equal to zero. The catastrophe theory formalism provides a mathematical tool to model ρ(x) in the neighbourhood of x c and allows one to rationalize the occurrence of instability in terms of electron-density topology and Gibbs energy. The phase/state transitions that TiO 2 (rutile structure), MgO (periclase structure) and Al 2 O 3 (corundum structure) undergo because of pressure and/or temperature are here discussed. An agreement of 3-5% is observed between the theoretical model and experimental pressure/temperature of transformation.
Zero-field quantum critical point in CeCoIn5.
Tokiwa, Y; Bauer, E D; Gegenwart, P
2013-09-06
Quantum criticality in the normal and superconducting states of the heavy-fermion metal CeCoIn5 is studied by measurements of the magnetic Grüneisen ratio ΓH and specific heat in different field orientations and temperatures down to 50 mK. A universal temperature over magnetic field scaling of ΓH in the normal state indicates a hidden quantum critical point at zero field. Within the superconducting state, the quasiparticle entropy at constant temperature increases upon reducing the field towards zero, providing additional evidence for zero-field quantum criticality.
Duality between the Deconfined Quantum-Critical Point and the Bosonic Topological Transition
Directory of Open Access Journals (Sweden)
Yan Qi Qin
2017-09-01
Full Text Available 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 CP^{1} model (NCCP^{1} and noncompact quantum electrodynamics (QED with two flavors (N=2 of massless two-component Dirac fermions. The easy-plane NCCP^{1} model is the field theory of the putative deconfined quantum-critical point separating a planar (XY 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 XY model with additional multispin couplings and show that it hosts a continuous transition between the XY 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
Impact of resonance decays on critical point signals in net-proton fluctuations
Energy Technology Data Exchange (ETDEWEB)
Bluhm, Marcus; Schaefer, Thomas [North Carolina State University, Department of Physics, Raleigh, NC (United States); Nahrgang, Marlene [SUBATECH, UMR 6457, Universite de Nantes, Ecole des Mines de Nantes, IN2P3/CNRS, Nantes (France); Duke University, Department of Physics, Durham, NC (United States); Bass, Steffen A. [Duke University, Department of Physics, Durham, NC (United States)
2017-04-15
The non-monotonic beam energy dependence of the higher cumulants of net-proton fluctuations is a widely studied signature of the conjectured presence of a critical point in the QCD phase diagram. In this work we study the effect of resonance decays on critical fluctuations. We show that resonance effects reduce the signatures of critical fluctuations, but that for reasonable parameter choices critical effects in the net-proton cumulants survive. The relative role of resonance decays has a weak dependence on the order of the cumulants studied with a slightly stronger suppression of critical effects for higher-order cumulants. (orig.)
Dynamical simulation of a linear sigma model near the critical point
Energy Technology Data Exchange (ETDEWEB)
Wesp, Christian; Meistrenko, Alex; Greiner, Carsten [Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt, Max-von-Laue-Strasse 1, D-60438 Frankfurt (Germany); Hees, Hendrik van [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, D-60438 Frankfurt (Germany)
2014-07-01
The intention of this study is the search for signatures of the chiral phase transition. To investigate the impact of fluctuations, e.g. of the baryon number, on the transition or a critical point, the linear sigma model is treated in a dynamical 3+1D numerical simulation. Chiral fields are approximated as classical fields, quarks are described by quasi particles in a Vlasov equation. Additional dynamic is implemented by quark-quark and quark-sigma-field interaction. For a consistent description of field-particle interactions, a new Monte-Carlo-Langevin-like formalism has been developed and is discussed.
Noise and time delay induce critical point in a bistable system
Zhang, Jianqiang; Nie, Linru; Yu, Lilong; Zhang, Xinyu
2014-07-01
We study relaxation time Tc of time-delayed bistable system driven by two cross-correlated Gaussian white noises that one is multiplicative and the other is additive. By means of numerical calculations, the results indicate that: (i) Combination of noise and time delay can induce two critical points about the relaxation time at some certain noise cross-correlation strength λ under the condition that the multiplicative intensity D equals to the additive noise intensity α. (ii) For each fixed D or α, there are two symmetrical critical points which locates in the regions of positive and negative correlations, respectively. Namely, as λ equals to the critical value λc, Tc is independent of the delay time and the result of Tc versus τ is a horizontal line, but as |λ|>|λc| (or |λ|decreases) with the delay time increasing. (iii) In the presence of D = α, the change of λc with D is two symmetrical curves about the axis of λc = 0, and the critical value λc is close to zero for a smaller D, which approaches to +1 or -1 for a greater D.
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...
Critical point in the phase diagram of primordial quark-gluon matter from black hole physics
Critelli, Renato; Noronha, Jorge; Noronha-Hostler, Jacquelyn; Portillo, Israel; Ratti, Claudia; Rougemont, Romulo
2017-11-01
Strongly interacting matter undergoes a crossover phase transition at high temperatures T ˜1012 K and zero net-baryon density. A fundamental question in the theory of strong interactions, QCD, is whether a hot and dense system of quarks and gluons displays critical phenomena when doped with more quarks than antiquarks, where net-baryon number fluctuations diverge. Recent lattice QCD work indicates that such a critical point can only occur in the baryon dense regime of the theory, which defies a description from first principles calculations. Here we use the holographic gauge/gravity correspondence to map the fluctuations of baryon charge in the dense quark-gluon liquid onto a numerically tractable gravitational problem involving the charge fluctuations of holographic black holes. This approach quantitatively reproduces ab initio results for the lowest order moments of the baryon fluctuations and makes predictions for the higher-order baryon susceptibilities and also for the location of the critical point, which is found to be within the reach of heavy-ion collision experiments.
Interactions and ``puff clustering'' close to the critical point in pipe flow
Vasudevan, Mukund; Hof, Björn
2017-11-01
The first turbulent structures to arise in pipe flow are puffs. Albeit transient in nature, their spreading determines if eventually turbulence becomes sustained. Due to the extremely long time scales involved in these processes it is virtually impossible to directly observe the transition and the flow patterns that are eventually assumed in the long time limit. We present a new experimental approach where, based on the memoryless nature of turbulent puffs, we continuously recreate the flow pattern exiting the pipe. These periodic boundary conditions enable us to show that the flow pattern eventually settles to a statistically steady state. While our study confirms the value of the critical point of Rec 2040 , the flow fields show that puffs interact over longer ranges than previously suspected. As a consequence puffs tend to cluster and these regions of large puff densities travel across the puff pattern in a wave like fashion. While transition in Couette flow has been shown to fall into the ``directed percolation'', pipe flow may be more complicated since long range interactions are prohibited for the percolation transition type. Extensive measurements at the critical point will be presented to clarify the nature of the transition.
Critical point in the QCD phase diagram for extremely strong background magnetic fields
International Nuclear Information System (INIS)
Endrödi, Gergely
2015-01-01
Lattice simulations have demonstrated that a background (electro)magnetic field reduces the chiral/deconfinement transition temperature of quantum chromodynamics for eB<1 GeV 2 . On the level of observables, this reduction manifests itself in an enhancement of the Polyakov loop and in a suppression of the light quark condensates (inverse magnetic catalysis) in the transition region. In this paper, we report on lattice simulations of 1+1+1-flavor QCD at an unprecedentedly high value of the magnetic field eB=3.25 GeV 2 . Based on the behavior of various observables, it is shown that even at this extremely strong field, inverse magnetic catalysis prevails and the transition, albeit becoming sharper, remains an analytic crossover. In addition, we develop an algorithm to directly simulate the asymptotically strong magnetic field limit of QCD. We find strong evidence for a first-order deconfinement phase transition in this limiting theory, implying the presence of a critical point in the QCD phase diagram. Based on the available lattice data, we estimate the location of the critical point.
Intrinsic low pass filtering improves signal-to-noise ratio in critical-point flexure biosensors
International Nuclear Information System (INIS)
Jain, Ankit; Alam, Muhammad Ashraful
2014-01-01
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.
Search for signatures of phase transition and critical point in heavy ion collisions
International Nuclear Information System (INIS)
Tokarev, M.V.; Kechechyan, A.; Alakhverdyants, A.; Zborovsky, I.
2011-01-01
The general concepts in the critical phenomena related with the notions of 'scaling' and 'universality' are considered. Behavior of various systems near a phase transition is displayed. Search for clear signatures of the phase transition of the nuclear matter and location of the critical point in heavy ion collisions (HIC) is discussed. The experimental data on inclusive spectra measured in HIC at RHIC and SPS over a wide range of energies s NN 1/2 = 9-200 GeV are analyzed in the framework of z-scaling. A microscopic scenario of the constituent interactions is presented. Dependence of the energy loss on the momentum of the produced hadron, energy and centrality of the collision is studied. Self-similarity of the constituent interactions described in terms of momentum fractions is used to characterize the nuclear medium by 'specific heat' and colliding nuclei by fractal dimensions. Preferable kinematical regions to search for signatures of the phase transition of the nuclear matter produced in HIC are discussed. Discontinuity of the 'specific heat' is assumed to be a signature of the phase transition and the critical point
Entropy excess in strongly correlated Fermi systems near a quantum critical point
Energy Technology Data Exchange (ETDEWEB)
Clark, J.W., E-mail: jwc@wuphys.wustl.edu [McDonnell Center for the Space Sciences and Department of Physics, Washington University, St. Louis, MO 63130 (United States); Zverev, M.V. [Russian Research Centre Kurchatov Institute, Moscow, 123182 (Russian Federation); Moscow Institute of Physics and Technology, Moscow, 123098 (Russian Federation); Khodel, V.A. [Russian Research Centre Kurchatov Institute, Moscow, 123182 (Russian Federation); McDonnell Center for the Space Sciences and Department of Physics, Washington University, St. Louis, MO 63130 (United States)
2012-12-15
A system of interacting, identical fermions described by standard Landau Fermi-liquid (FL) theory can experience a rearrangement of its Fermi surface if the correlations grow sufficiently strong, as occurs at a quantum critical point where the effective mass diverges. As yet, this phenomenon defies full understanding, but salient aspects of the non-Fermi-liquid (NFL) behavior observed beyond the quantum critical point are still accessible within the general framework of the Landau quasiparticle picture. Self-consistent solutions of the coupled Landau equations for the quasiparticle momentum distribution n(p) and quasiparticle energy spectrum {epsilon}(p) are shown to exist in two distinct classes, depending on coupling strength and on whether the quasiparticle interaction is regular or singular at zero momentum transfer. One class of solutions maintains the idempotency condition n{sup 2}(p)=n(p) of standard FL theory at zero temperature T while adding pockets to the Fermi surface. The other solutions are characterized by a swelling of the Fermi surface and a flattening of the spectrum {epsilon}(p) over a range of momenta in which the quasiparticle occupancies lie between 0 and 1 even at T=0. The latter, non-idempotent solution is revealed by analysis of a Poincare mapping associated with the fundamental Landau equation connecting n(p) and {epsilon}(p) and validated by solution of a variational condition that yields the symmetry-preserving ground state. Significantly, this extraordinary solution carries the burden of a large temperature-dependent excess entropy down to very low temperatures, threatening violation of the Nernst Theorem. It is argued that certain low-temperature phase transitions, notably those involving Cooper-pair formation, offer effective mechanisms for shedding the entropy excess. Available measurements in heavy-fermion compounds provide concrete support for such a scenario. - Highlights: Black-Right-Pointing-Pointer Extension of Landau
The Subtle Balance between Lipolysis and Lipogenesis: A Critical Point in Metabolic Homeostasis.
Saponaro, Chiara; Gaggini, Melania; Carli, Fabrizia; Gastaldelli, Amalia
2015-11-13
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.
Photoinduced second harmonic generation of LaFe4Sb12near spin fluctuated critical points
International Nuclear Information System (INIS)
Nouneh, K.; Viennois, R.; Kityk, I.V.; Terki, F.; Charar, S.; Benet, S.; Paschen, S.
2004-01-01
The temperature dependence of the resistivity, the Seebeck coefficient and photoinduced second harmonic generation (PISHG) are studied near the quantum critical point in the skutterudite compound LaFe 4 Sb 12 , possessing increased spin fluctuations. We observed a large maximum of the PISHG at a temperature of about 15 K. The PISHG signal increases substantially below 35 K. We found a correlation between the temperature dependences of PISHG, resistivity and Seebeck coefficient. We proposed a phenomenological explanation for the occurrence of the PISHG signal in LaFe 4 Sb 12 implying strong spin fluctuations exist in this system, which may present some interest for the study of other spin fluctuation systems. Physical insight into the phenomenon observed is grounded in the participation of anharmonic electron-phonon and electron-paramagnon interactions stimulated by inducing light in the interactions with the photoexcited dipole moments. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Bohr model description of the critical point for the first order shape phase transition
Budaca, R.; Buganu, P.; Budaca, A. I.
2018-01-01
The critical point of the shape phase transition between spherical and axially deformed nuclei is described by a collective Bohr Hamiltonian with a sextic potential having simultaneous spherical and deformed minima of the same depth. The particular choice of the potential as well as the scaled and decoupled nature of the total Hamiltonian leads to a model with a single free parameter connected to the height of the barrier which separates the two minima. The solutions are found through the diagonalization in a basis of Bessel functions. The basis is optimized for each value of the free parameter by means of a boundary deformation which assures the convergence of the solutions for a fixed basis dimension. Analyzing the spectral properties of the model, as a function of the barrier height, revealed instances with shape coexisting features which are considered for detailed numerical applications.
Bohr model description of the critical point for the first order shape phase transition
Directory of Open Access Journals (Sweden)
R. Budaca
2018-01-01
Full Text Available The critical point of the shape phase transition between spherical and axially deformed nuclei is described by a collective Bohr Hamiltonian with a sextic potential having simultaneous spherical and deformed minima of the same depth. The particular choice of the potential as well as the scaled and decoupled nature of the total Hamiltonian leads to a model with a single free parameter connected to the height of the barrier which separates the two minima. The solutions are found through the diagonalization in a basis of Bessel functions. The basis is optimized for each value of the free parameter by means of a boundary deformation which assures the convergence of the solutions for a fixed basis dimension. Analyzing the spectral properties of the model, as a function of the barrier height, revealed instances with shape coexisting features which are considered for detailed numerical applications.
Picture change error in quasirelativistic electron/spin density, Laplacian and bond critical points
Bučinský , Luká š; Kucková , Lenka; Malček, Michal; Koží šek, Jozef; Biskupič, Stanislav; Jayatilaka, Dylan; Bü chel, Gabriel E.; Arion, Vladimir B.
2014-01-01
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.
LaCu6-xAgx : A promising host of an elastic quantum critical point
Poudel, L.; Cruz, C. de la; Koehler, M. R.; McGuire, M. A.; Keppens, V.; Mandrus, D.; Christianson, A. D.
2018-05-01
Structural properties of LaCu6-xAgx have been investigated using neutron and x-ray diffraction, and resonant ultrasound spectroscopy (RUS) measurements. Diffraction measurements indicate a continuous structural transition from orthorhombic (Pnma) to monoclinic (P21 / c) structure. RUS measurements show softening of natural frequencies at the structural transition, consistent with the elastic nature of the structural ground state. The structural transition temperatures in LaCu6-xAgx decrease with Ag composition until the monoclinic phase is completely suppressed at xc = 0.225 . All of the evidence is consistent with the presence of an elastic quantum critical point in LaCu6-xAgx .
Magnetic-field control of quantum critical points of valence transition.
Watanabe, Shinji; Tsuruta, Atsushi; Miyake, Kazumasa; Flouquet, Jacques
2008-06-13
We study the mechanism of how critical end points of first-order valence transitions are controlled by a magnetic field. We show that the critical temperature is suppressed to be a quantum critical point (QCP) by a magnetic field, and unexpectedly, the QCP exhibits nonmonotonic field dependence in the ground-state phase diagram, giving rise to the emergence of metamagnetism even in the intermediate valence-crossover regime. The driving force of the field-induced QCP is clarified to be cooperative phenomena of the Zeeman and Kondo effects, which create a distinct energy scale from the Kondo temperature. This mechanism explains the peculiar magnetic response in CeIrIn(5) and the metamagnetic transition in YbXCu(4) for X=In as well as the sharp contrast between X=Ag and Cd.
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.
Signals for the QCD phase transition and critical point in a Langevin dynamical model
International Nuclear Information System (INIS)
Herold, Christoph; Bleicher, Marcus; Yan, Yu-Peng
2013-01-01
The search for the critical point is one of the central issues that will be investigated in the upcoming FAIR project. For a profound theoretical understanding of the expected signals we go beyond thermodynamic studies and present a fully dynamical model for the chiral and deconfinement phase transition in heavy ion collisions. The corresponding order parameters are propagated by Langevin equations of motions on a thermal background provided by a fluid dynamically expanding plasma of quarks. By that we are able to describe nonequilibrium effects occurring during the rapid expansion of a hot fireball. For an evolution through the phase transition the formation of a supercooled phase and its subsequent decay crucially influence the trajectories in the phase diagram and lead to a significant reheating of the quark medium at highest baryon densities. Furthermore, we find inhomogeneous structures with high density domains along the first order transition line within single events.
Order parameter fluctuations at a critical point - an exact result about percolation -
International Nuclear Information System (INIS)
Botet, Robert
2011-01-01
The order parameter of the system in the critical state, is expected to undergo large non-Gaussian fluctuations. However, almost nothing is known about the mathematical forms of the possible probability distributions of the order parameter. A remarkable exception is the site-percolation on the Bethe lattice, for which the complete order-parameter distribution has been recently derived at the critical point. Surprisingly, it appears to be the Kolmogorov-Smirnov distribution, well known in very different areas of mathematical statistics. In the present paper, we explain first how this special distribution could appear naturally in the context of the critical systems, under the assumption (still virtually unstudied) of the exponential distribution of the number of domains of a given size. In a second part, we present for the first time the complete derivation of the order-parameter distribution for the critical percolation model on the Bethe lattice, thus completing a recent publication announcing this result.
Condensation of Methane in the Metal-Organic Framework IRMOF-1: Evidence for Two Critical Points.
Höft, Nicolas; Horbach, Jürgen
2015-08-19
Extensive grand canonical Monte Carlo simulations in combination with successive umbrella sampling are used to investigate the condensation of methane in the nanoporous crystalline material IRMOF-1. Two different types of novel condensation transitions are found, each of them ending in a critical point: (i) a fluid-fluid transition at higher densities (the analog of the liquid-gas transition in the bulk) and (ii) a phase transition at low densities on the surface of the IRMOF-1 structure. The nature of these transitions is different from the usual capillary condensation in thin films and cylindrical pores where the coexisting phases are confined in one or two of the three spatial dimensions. In contrast to that, in IRMOF-1 the different phases can be described as bulk phases that are inhomogeneous due to the presence of the metal-organic framework. As a consequence, the condensation transitions in IRMOF-1 belong to the three-dimensional (3D) Ising universality class.
Determining the Critical Point of a Sigmoidal Curve via its Fourier Transform
International Nuclear Information System (INIS)
Bilge, Ayse Humeyra; Ozdemir, Yunus
2016-01-01
A sigmoidal curve y(t) is a monotone increasing curve such that all derivatives vanish at infinity. Let t_n be the point where the nth derivative of y(t) reaches its global extremum. In the previous work on sol-gel transition modelled by the Susceptible-Infected- Recovered (SIR) system, we observed that the sequence { t_n } seemed to converge to a point that agrees qualitatively with the location of the gel point [2]. In the present work we outline a proof that for sigmoidal curves satisfying fairly general assumptions on their Fourier transform, the sequence { t_n } is convergent and we call it “the critical point of the sigmoidal curve”. In the context of phase transitions, the limit point is interpreted as a junction point of two different regimes where all derivatives undergo their highest rate of change. (paper)
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.
Zhang, Chendong; Chen, Yuxuan; Johnson, Amber; Li, Ming-yang; Li, Lain-Jong; Mende, Patrick C.; Feenstra, Randall M.; Shih, Chih Kang
2015-01-01
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.
Engineering Surface Critical Behavior of (2 +1 )-Dimensional O(3) Quantum Critical Points
Ding, Chengxiang; Zhang, Long; Guo, Wenan
2018-06-01
Surface critical behavior (SCB) refers to the singularities of physical quantities on the surface at the bulk phase transition. It is closely related to and even richer than the bulk critical behavior. In this work, we show that three types of SCB universality are realized in the dimerized Heisenberg models at the (2 +1 )-dimensional O(3) quantum critical points by engineering the surface configurations. The ordinary transition happens if the surface is gapped in the bulk disordered phase, while the gapless surface state generally leads to the multicritical special transition, even though the latter is precluded in classical phase transitions because the surface is in the lower critical dimension. An extraordinary transition is induced by the ferrimagnetic order on the surface of the staggered Heisenberg model, in which the surface critical exponents violate the results of the scaling theory and thus seriously challenge our current understanding of extraordinary transitions.
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.
A simple method for determining the critical point of the soil water retention curve
DEFF Research Database (Denmark)
Chen, Chong; Hu, Kelin; Ren, Tusheng
2017-01-01
he transition point between capillary water and adsorbed water, which is the critical point Pc [defined by the critical matric potential (ψc) and the critical water content (θc)] of the soil water retention curve (SWRC), demarcates the energy and water content region where flow is dominated......, a fixed tangent line method was developed to estimate Pc as an alternative to the commonly used flexible tangent line method. The relationships between Pc, and particle-size distribution and specific surface area (SSA) were analyzed. For 27 soils with various textures, the mean RMSE of water content from...... the fixed tangent line method was 0.007 g g–1, which was slightly better than that of the flexible tangent line method. With increasing clay content or SSA, ψc was more negative initially but became less negative at clay contents above ∼30%. Increasing the silt contents resulted in more negative ψc values...
Theory of First Order Chemical Kinetics at the Critical Point of Solution.
Baird, James K; Lang, Joshua R
2017-10-26
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 exploit 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 pseudoequilibrium 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.
Core-softened fluids, water-like anomalies, and the liquid-liquid critical points.
Salcedo, Evy; de Oliveira, Alan Barros; Barraz, Ney M; Chakravarty, Charusita; Barbosa, Marcia C
2011-07-28
Molecular dynamics simulations are used to examine the relationship between water-like anomalies and the liquid-liquid critical point in a family of model fluids with multi-Gaussian, core-softened pair interactions. The core-softened pair interactions have two length scales, such that the longer length scale associated with a shallow, attractive well is kept constant while the shorter length scale associated with the repulsive shoulder is varied from an inflection point to a minimum of progressively increasing depth. The maximum depth of the shoulder well is chosen so that the resulting potential reproduces the oxygen-oxygen radial distribution function of the ST4 model of water. As the shoulder well depth increases, the pressure required to form the high density liquid decreases and the temperature up to which the high-density liquid is stable increases, resulting in the shift of the liquid-liquid critical point to much lower pressures and higher temperatures. To understand the entropic effects associated with the changes in the interaction potential, the pair correlation entropy is computed to show that the excess entropy anomaly diminishes when the shoulder well depth increases. Excess entropy scaling of diffusivity in this class of fluids is demonstrated, showing that decreasing strength of the excess entropy anomaly with increasing shoulder depth results in the progressive loss of water-like thermodynamic, structural and transport anomalies. Instantaneous normal mode analysis was used to index the overall curvature distribution of the fluid and the fraction of imaginary frequency modes was shown to correlate well with the anomalous behavior of the diffusivity and the pair correlation entropy. The results suggest in the case of core-softened potentials, in addition to the presence of two length scales, energetic, and entropic effects associated with local minima and curvatures of the pair interaction play an important role in determining the presence of water
International Nuclear Information System (INIS)
Jeong, Woo Seok; Lee, Jeong Ik; Jeong, Yong Hoon; No, Hee Cheon
2010-01-01
Most of the existing designs of a Sodium cooled Fast Reactor (SFR) have a Rankine cycle as an electric power generation cycle. This has the risk of a sodium water reaction. To prevent any hazards from a sodium water reaction, an indirect Brayton cycle using Supercritical Carbon dioxide (S-CO 2 ) as the working fluids for a SFR is an alternative approach to improve the current SFR design. The supercritical Brayton cycle is defined as a cycle with operating conditions above the critical point and the main compressor inlet condition located slightly above the critical point of working fluid. This is because the main advantage of the cycle comes from significantly decreased compressor work just above the critical point due to high density near boundary between supercritical state and subcritical state. For this reason, the minimum temperature and pressure of cycle are just above the CO 2 critical point. In other words, the critical point acts as a limitation of the lowest operating condition of the cycle. In general, lowering the minimum temperature of a thermodynamic cycle can increase the efficiency and the minimum temperature can be decreased by shifting the critical point of CO 2 as mixed with other gases. In this paper, potential enhancement of S-CO 2 cycle coupled with KALIMER-600, which has been developed at KAERI, was investigated using a developed cycle code with a gas mixture property program
Supercritical CO2 Brayton cycle compression and control near the critical point
International Nuclear Information System (INIS)
Wright, S. A.; Fuller, R.; Noall, J.; Radel, R.; Vernon, M. E.; Pickard, P. S.
2008-01-01
This report describes the supercritical compression and control issues, the analysis, and the measured test results of a small-scale supercritical CO 2 (S-CO 2 ) compression test-loop. The test loop was developed by Sandia and is described in a companion paper in this conference. The results of these experiments will for the first time evaluate and experimentally demonstrate supercritical compression and the required compressor inlet control approaches on an appropriate scale in a series of test loops at Sandia National Laboratories. The Sandia effort is focused on the main compressor of a supercritical Brayton loop while a separate DOE Gen lV program focus is on studying similar behavior in re-compression Brayton cycles that have dual compressors. One of the main goals of this program is to develop and demonstrate the ability to design, operate, and control the supercritical compression process near the critical point due to highly non-linear behavior near this point. This Sandia supercritical test-loop uses a 50 kW radial compressor to pump supercritical CO 2 (S-CO 2 ) through an orifice and through a water-cooled gas-chiller. At the design point the compressor flow rate is 3.5 kg/s, the inlet pressure is 7, 690 kPa, the pressure ratio is 1.8, the inlet temperature is 305 K, and the shaft speed is 75, 000 rpm. The purpose of the loop is to study the compression and control issues near the critical point. To study compression we intend to compare the design code predictions for efficiency and change in enthalpy (or pressure ratio / head) of the radial compressor with the measured results from actual tests. In the tests the inlet flow, temperature, and pressure, will be varied around the critical point of CO 2 (Tc=304.2 K, and Pc=7.377 MPa). To study control, the test loop will use a variety of methods including inventory control, shaft speed control, and cooling water flow rate, and cooling water temperature control methods to set the compressor inlet temperature
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.
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.
Coherent inflationary dynamics for Bose-Einstein condensates crossing a quantum critical point
Feng, Lei; Clark, Logan W.; Gaj, Anita; Chin, Cheng
2018-03-01
Quantum phase transitions, transitions between many-body ground states, are of extensive interest in research ranging from condensed-matter physics to cosmology1-4. Key features of the phase transitions include a stage with rapidly growing new order, called inflation in cosmology5, followed by the formation of topological defects6-8. How inflation is initiated and evolves into topological defects remains a hot topic of debate. Ultracold atomic gas offers a pristine and tunable platform to investigate quantum critical dynamics9-21. We report the observation of coherent inflationary dynamics across a quantum critical point in driven Bose-Einstein condensates. The inflation manifests in the exponential growth of density waves and populations in well-resolved momentum states. After the inflation stage, extended coherent dynamics is evident in both real and momentum space. We present an intuitive description of the quantum critical dynamics in our system and demonstrate the essential role of phase fluctuations in the formation of topological defects.
Thermal properties of ionic systems near the liquid-liquid critical point.
Méndez-Castro, Pablo; Troncoso, Jacobo; Pérez-Sánchez, Germán; Peleteiro, José; Romaní, Luis
2011-12-07
Isobaric heat capacity per unit volume, C(p), and excess molar enthalpy, h(E), were determined in the vicinity of the critical point for a set of binary systems formed by an ionic liquid and a molecular solvent. Moreover, and, since critical composition had to be accurately determined, liquid-liquid equilibrium curves were also obtained using a calorimetric method. The systems were selected with a view on representing, near room temperature, examples from clearly solvophobic to clearly coulombic behavior, which traditionally was related with the electric permittivity of the solvent. The chosen molecular compounds are: ethanol, 1-butanol, 1-hexanol, 1,3-dichloropropane, and diethylcarbonate, whereas ionic liquids are formed by imidazolium-based cations and tetrafluoroborate or bis-(trifluromethylsulfonyl)amide anions. The results reveal that solvophobic critical behavior-systems with molecular solvents of high dielectric permittivity-is very similar to that found for molecular binary systems. However, coulombic systems-those with low permittivity molecular solvents-show strong deviations from the results usually found for these magnitudes near the liquid-liquid phase transition. They present an extremely small critical anomaly in C(p)-several orders of magnitude lower than those typically obtained for binary mixtures-and extremely low h(E)-for one system even negative, fact not observed, up to date, for any liquid-liquid transition in the nearness of an upper critical solution temperature. © 2011 American Institute of Physics
Scaling functions for the Inverse Compressibility near the QCD critical point
Lacey, Roy
2017-09-01
The QCD phase diagram can be mapped out by studying fluctuations and their response to changes in the temperature and baryon chemical potential. Theoretical studies indicate that the cumulant ratios Cn /Cm used to characterize the fluctuation of conserved charges, provide a valuable probe of deconfinement and chiral dynamics, as well as for identifying the position of the critical endpoint (CEP) in the QCD phase diagram. The ratio C1 /C2 , which is linked to the inverse compressibility, vanishes at the CEP due to the divergence of the net quark number fluctuations at the critical point belonging to the Z(2) universality class. Therefore, it's associated scaling function can give insight on the location of the critical end point, as well as the critical exponents required to assign its static universality class. Scaling functions for the ratio C1 /C2 , obtained from net-proton multiplicity distributions for a broad range of collision centralities in Au+Au (√{sNN} = 7.7 - 200 GeV) collisions will be presented and discussed.
Quench dynamics near a quantum critical point: Application to the sine-Gordon model
International Nuclear Information System (INIS)
De Grandi, C.; Polkovnikov, A.; Gritsev, V.
2010-01-01
We discuss the quench dynamics near a quantum critical point focusing on the sine-Gordon model as a primary example. We suggest a unified approach to sudden and slow quenches, where the tuning parameter λ(t) changes in time as λ(t)∼υt r , based on the adiabatic expansion of the excitation probability in powers of υ. We show that the universal scaling of the excitation probability can be understood through the singularity of the generalized adiabatic susceptibility χ 2r+2 (λ), which for sudden quenches (r=0) reduces to the fidelity susceptibility. In turn this class of susceptibilities is expressed through the moments of the connected correlation function of the quench operator. We analyze the excitations created after a sudden quench of the cosine potential using a combined approach of form-factors expansion and conformal perturbation theory for the low-energy and high-energy sector, respectively. We find the general scaling laws for the probability of exciting the system, the density of excited quasiparticles, the entropy and the heat generated after the quench. In the two limits where the sine-Gordon model maps to hard-core bosons and free massive fermions we provide the exact solutions for the quench dynamics and discuss the finite temperature generalizations.
Systems near a critical point under multiplicative noise and the concept of effective potential
Shapiro, V. E.
1993-07-01
This paper presents a general approach to and elucidates the main features of the effective potential, friction, and diffusion exerted by systems near a critical point due to nonlinear influence of noise. The model is that of a general many-dimensional system of coupled nonlinear oscillators of finite damping under frequently alternating influences, multiplicative or additive, and arbitrary form of the power spectrum, provided the time scales of the system's drift due to noise are large compared to the scales of unperturbed relaxation behavior. The conventional statistical approach and the widespread deterministic effective potential concept use the assumptions about a small parameter which are particular cases of the considered. We show close correspondence between the asymptotic methods of these approaches and base the analysis on this. The results include an analytical treatment of the system's long-time behavior as a function of the noise covering all the range of its table- and bell-shaped spectra, from the monochromatic limit to white noise. The trend is considered both in the coordinate momentum and in the coordinate system's space. Particular attention is paid to the stabilization behavior forced by multiplicative noise. An intermittency, in a broad area of the control parameter space, is shown to be an intrinsic feature of these phenomena.
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.
Dynamical susceptibility near a long-wavelength critical point with a nonconserved order parameter
Klein, Avraham; Lederer, Samuel; Chowdhury, Debanjan; Berg, Erez; Chubukov, Andrey
2018-04-01
We study the dynamic response of a two-dimensional system of itinerant fermions in the vicinity of a uniform (Q =0 ) Ising nematic quantum critical point of d - wave symmetry. The nematic order parameter is not a conserved quantity, and this permits a nonzero value of the fermionic polarization in the d - wave channel even for vanishing momentum and finite frequency: Π (q =0 ,Ωm)≠0 . For weak coupling between the fermions and the nematic order parameter (i.e., the coupling is small compared to the Fermi energy), we perturbatively compute Π (q =0 ,Ωm)≠0 over a parametrically broad range of frequencies where the fermionic self-energy Σ (ω ) is irrelevant, and use Eliashberg theory to compute Π (q =0 ,Ωm) in the non-Fermi-liquid regime at smaller frequencies, where Σ (ω )>ω . We find that Π (q =0 ,Ω ) is a constant, plus a frequency-dependent correction that goes as |Ω | at high frequencies, crossing over to |Ω| 1 /3 at lower frequencies. The |Ω| 1 /3 scaling holds also in a non-Fermi-liquid regime. The nonvanishing of Π (q =0 ,Ω ) gives rise to additional structure in the imaginary part of the nematic susceptibility χ″(q ,Ω ) at Ω >vFq , in marked contrast to the behavior of the susceptibility for a conserved order parameter. This additional structure may be detected in Raman scattering experiments in the d - wave geometry.
Existence of a critical point in the phase diagram of the ideal relativistic neutral Bose gas
International Nuclear Information System (INIS)
Park, Jeong-Hyuck; Kim, Sang-Woo
2011-01-01
We explore the phase transitions of the ideal relativistic neutral Bose gas confined in a cubic box, without assuming the thermodynamic limit nor continuous approximation. While the corresponding non-relativistic canonical partition function is essentially a one-variable function depending on a particular combination of temperature and volume, the relativistic canonical partition function is genuinely a two-variable function of them. Based on an exact expression for the canonical partition function, we performed numerical computations for up to 10 5 particles. We report that if the number of particles is equal to or greater than a critical value, which amounts to 7616, the ideal relativistic neutral Bose gas features a spinodal curve with a critical point. This enables us to depict the phase diagram of the ideal Bose gas. The consequent phase transition is first order below the critical pressure or second order at the critical pressure. The exponents corresponding to the singularities are 1/2 and 2/3, respectively. We also verify the recently observed 'Widom line' in the supercritical region.
Fluctuations and correlations of conserved charges near the QCD critical point
International Nuclear Information System (INIS)
Fu Weijie; Wu Yueliang
2010-01-01
We study the fluctuations and correlations of conserved charges, such as the baryon number, the electric charge and the strangeness, at the finite temperature and the nonzero baryon chemical potential in an effective model. The fluctuations are calculated up to the fourth-order and the correlations to the third-order. We find that the second-order fluctuations and correlations have a peak or valley structure when the chiral phase transition takes place with the increase of the baryon chemical potential; the third-order fluctuations and correlations change their signs during the chiral phase transition; and the fourth-order fluctuations have two maxima and one minimum. We also depict contour plots of various fluctuations and correlations of conserved charges in the plane of temperature and the baryon chemical potential. It is found that higher-order fluctuations and correlations of conserved charges are superior to the second-order ones to be used to search for the critical point in heavy ion collision experiments.
CePdAl. A frustrated Kondo lattice at a quantum critical point
Energy Technology Data Exchange (ETDEWEB)
Fritsch, Veronika [EP 6, Electronic Correlations and Magnetism, University of Augsburg (Germany); Karlsruhe Institute of Technology (Germany); Sakai, Akito; Gegenwart, Philipp [EP 6, Electronic Correlations and Magnetism, University of Augsburg (Germany); Huesges, Zita; Lucas, Stefan; Stockert, Oliver [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Kittler, Wolfram; Taubenheim, Christian; Grube, Kai; Loehneysen, Hilbert von [Karlsruhe Institute of Technology (Germany); Huang, Chien-Lung [Karlsruhe Institute of Technology (Germany); Max Planck Institute for Chemical Physics of Solids, Dresden (Germany)
2016-07-01
CePdAl is one of the rare frustrated Kondo lattice systems that can be tuned across a quantum critical point (QCP) by means of chemical pressure, i. e., the substitution of Pd by Ni. Magnetic frustration and Kondo effect are antithetic phenomena: The Kondo effect with the incipient delocalization of the magnetic moments, is not beneficial for the formation of a frustrated state. On the other hand, magnetic frustrated exchange interactions between the local moments can result in a breakdown of Kondo screening. Furthermore, the fate of frustration is unclear when approaching the QCP, since there is no simple observable to quantify the degree of frustration. We present thermodynamic and neutron scattering experiments on CePd{sub 1-x}Ni{sub x}Al close to the critical concentration x ∼0.14. Our experiments indicate that even at the QCP magnetic frustration is still present, opening the perspective to find new universality classes at such a quantum phase transition.
International Nuclear Information System (INIS)
Centner, Terence J.
2016-01-01
While the public and governments debate the advisability of engaging in shale gas production, the United States has proceeded to develop its resources with an accompanying remarkable increase in natural gas production. The development of shale gas has not been without problems, and some countries have decided that shale gas production should not proceed until more is known about the accompanying health issues and environmental damages. From experiences in the United States, careful consideration of five critical points relating to shale gas production can form the basis for developing strategies for reducing discharges of pollutants: (1) casing and cementing, (2) handling wastewater, (3) venting and flaring, (4) equipment with air emissions, and (5) seismic events. For each strategy, institutional responses to markedly reduce the risks of harm to people and the environment are identified. These responses offer state and local governments ideas for enabling shale gas resources to be developed without sacrificing public health and environmental quality. - Highlights: •Shale gas development involves releases of unnecessary pollutants. •Major sources of unnecessary pollutants can be identified. •For major pollutant sources, strategies can be developed to reduce releases of contaminants. •Alternative strategies can offer firms and governments ways to reduce pollutant releases.
A QCD chiral critical point at small chemical potential: is it there or not?
de Forcrand, Philippe; Philipsen, Owe
2007-01-01
For a QCD chiral critical point to exist, the parameter region of small quark masses for which the finite temperature transition is first-order must expand when the chemical potential is turned on. This can be tested by a Taylor expansion of the critical surface (m_{u,d},m_s)_c(mu). We present a new method to perform this Taylor expansion numerically, which we first test on an effective model of QCD with static, dense quarks. We then present the results for QCD with 3 degenerate flavors. For a lattice with N_t=4 time-slices, the first-order region shrinks as the chemical potential is turned on. This implies that, for physical quark masses, the analytic crossover which occurs at mu=0 between the hadronic and the plasma regimes remains crossover in the mu-region where a Taylor expansion is reliable, i.e. mu less than or similar to T. We present preliminary results from finer lattices indicating that this situation persists, as does the discrepancy between the curvature of T_c(mu) and the experimentally observed...
International Nuclear Information System (INIS)
Val’kov, V. V.; Zlotnikov, A. O.
2013-01-01
Mechanisms of the appearance of anomalous properties experimentally observed at the transition through the quantum critical point in rare-earth intermetallides have been studied. Quantum phase transitions are induced by the external pressure and are manifested as the destruction of the long-range antiferromagnetic order at zero temperature. The suppression of the long-range order is accompanied by an increase in the area of the Fermi surface, and the effective electron mass is strongly renormalized near the quantum critical point. It has been shown that such a renormalization is due to the reconstruction of the quasiparticle band, which is responsible for the formation of heavy fermions. It has been established that these features hold when the coexistence phase of antiferromagnetism and superconductivity is implemented near the quantum critical point.
International Nuclear Information System (INIS)
Zhang Yu; Pan Feng; Liu Yuxin; Luo Yanan; Draayer, J. P.
2011-01-01
An analytically solvable model, X(3/2j+1), is proposed to describe odd-A nuclei near the X(3) critical point. The model is constructed based on a collective core described by the X(3) critical point symmetry coupled to a spin-j particle. A detailed analysis of the spectral patterns for cases j=1/2 and j=3/2 is provided to illustrate dynamical features of the model. By comparing theory with experimental data and results of other models, it is found that the X(3/2j+1) model can be taken as a simple yet very effective scheme to describe those odd-A nuclei with an even-even core at the critical point of the spherical to axially deformed shape phase transition.
International Nuclear Information System (INIS)
Marano, S.
1998-01-01
In 1911 E.Rutherford discovered the nucleus. Since then the nucleus has been investigated with more and more powerful tools but it remains the main field of study of nuclear physics. As it is impossible to take into account the interaction of all the nucleons, a theory based on the hypothesis that each nucleon undergoes an average interaction force has been set up. 2 representations have emerged: the Skyrme force and the Gogny force. Both representations match experimental results but are unable to describe fission yields or the multi-fragmentation of very hot nuclei. The mean-field theory can predict the shape of the nuclei according to its energy level. An experimental program involving the Vivitron accelerator and the Euroball detector is due to begin to validate it. By bombarding targets with exotic nuclei nuclear physicists detect new structures and test their collision models. About ten years ago nuclear halos were observed with lithium 11 nuclei. In this nucleus 2 neutrons move in a space larger than the nucleus itself. This discovery has triggered the elaboration of new theories based on nuclear clusters. At very high temperatures the mean-field theory predicts that nuclear matter acts as a fluid. Following the nuclei temperature different ways of decay appear: first evaporation then multi-fragmentation and vaporization. This ultimate stage occurs around 100 milliard celsius degree temperature when the nuclei decays in a multitude of light particles. Isomeric states are studied and could be seen as a way of storing energy. In a very pedagogical way this article gives information to understand the challenges that face nuclear physics today and highlights the contributions of Cea in this field. (A.C.)
International Nuclear Information System (INIS)
Monthus, Cecile; Garel, Thomas
2009-01-01
For Anderson localization on the Cayley tree, we study the statistics of various observables as a function of the disorder strength W and the number N of generations. We first consider the Landauer transmission T N . In the localized phase, its logarithm follows the traveling wave form T N ≅(ln T N )-bar + ln t* where (i) the disorder-averaged value moves linearly (ln(T N ))-bar≅-N/ξ loc and the localization length diverges as ξ loc ∼(W-W c ) -ν loc with ν loc = 1 and (ii) the variable t* is a fixed random variable with a power-law tail P*(t*) ∼ 1/(t*) 1+β(W) for large t* with 0 N are governed by rare events. In the delocalized phase, the transmission T N remains a finite random variable as N → ∞, and we measure near criticality the essential singularity (ln(T ∞ ))-bar∼-|W c -W| -κ T with κ T ∼ 0.25. We then consider the statistical properties of normalized eigenstates Σ x |ψ(x)| 2 = 1, in particular the entropy S = -Σ x |ψ(x)| 2 ln |ψ(x)| 2 and the inverse participation ratios (IPR) I q = Σ x |ψ(x)| 2q . In the localized phase, the typical entropy diverges as S typ ∼( W-W c ) -ν S with ν S ∼ 1.5, whereas it grows linearly as S typ (N) ∼ N in the delocalized phase. Finally for the IPR, we explain how closely related variables propagate as traveling waves in the delocalized phase. In conclusion, both the localized phase and the delocalized phase are characterized by the traveling wave propagation of some probability distributions, and the Anderson localization/delocalization transition then corresponds to a traveling/non-traveling critical point. Moreover, our results point toward the existence of several length scales that diverge with different exponents ν at criticality
Directory of Open Access Journals (Sweden)
Sarkar Amal
2013-11-01
Full Text Available In this paper we report the measurements of the various moments mean (M, standard deviation (σ skewness (S and kurtosis (κ of the net-Kaon multiplicity distribution at midrapidity from Au+Au collisions at √sNN = 7.7 to 200 GeV in the STAR experiment at RHIC in an effort to locate the critical point in the QCD phase diagram. These moments and their products are related to the thermodynamic susceptibilities of conserved quantities such as net baryon number, net charge, and net strangeness as also to the correlation length of the system. A non-monotonic behavior of these variable indicate the presence of the critical point. In this work we also present the moments products Sσ, κσ2 of net-Kaon multiplicity distribution as a function of collision centrality and energies. The energy and the centrality dependence of higher moments of net-Kaons and their products have been compared with it0s Poisson expectation and with simulations from AMPT which does not include the critical point. From the measurement at all seven available beam energies, we find no evidence for a critical point in the QCD phase diagram for √sNN below 200 GeV.
Search for the critical point of strongly interacting matter at the CERN SPS NA61/SHINE experiment
Turko, L
2015-01-01
The NA61/SHINE experiment performs a detailed study of the onset of deconfinement and search for critical point of hadronic matter by colliding nuclei of different sizes at various beam momenta from 13A to 158A GeV/c. Experimental setup and results on the theoretically expected signatures are discussed.
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.
International Nuclear Information System (INIS)
Jeong, Woo Seok; Jeong, Yong Hoon
2013-01-01
Highlights: • Supercritical CO 2 -based gas mixture Brayton cycles were investigated for a SFR. • The critical point of CO 2 is the lowest cycle operating limit of the S-CO 2 cycles. • Mixing additives with CO 2 changes the CO 2 critical point. • CO 2 –Xe and CO 2 –Kr cycles achieve higher cycle efficiencies than the S-CO 2 cycles. • CO 2 –H 2 S and CO 2 –cyclohexane cycles perform better at higher heat sink temperatures. -- Abstract: The supercritical carbon dioxide Brayton cycle (S-CO 2 cycle) has attracted much attention as an alternative to the Rankine cycle for sodium-cooled fast reactors (SFRs). The higher cycle efficiency of the S-CO 2 cycle results from the considerably decreased compressor work because the compressor behaves as a pump in the proximity of the CO 2 vapor–liquid critical point. In order to fully utilize this feature, the main compressor inlet condition should be controlled to be close to the critical point of CO 2 . This indicates that the critical point of CO 2 is a constraint on the minimum cycle condition for S-CO 2 cycles. Modifying the CO 2 critical point by mixing additive gases could be considered as a method of enhancing the performance and broadening the applicability of the S-CO 2 cycle. Due to the drastic fluctuations of the thermo-physical properties of fluids near the critical point, an in-house cycle analysis code using the NIST REFPROP database was implemented. Several gases were selected as potential additives considering their thermal stability and chemical interaction with sodium in the temperature range of interest and the availability of the mixture property database: xenon, krypton, hydrogen sulfide, and cyclohexane. The performances of the optimized CO 2 -containing binary mixture cycles with simple recuperated and recompression layouts were compared with the reference S-CO 2 , CO 2 –Ar, CO 2 –N 2 , and CO 2 –O 2 cycles. For the decreased critical temperatures, the CO 2 –Xe and CO 2
Nucleus-nucleus total reaction cross sections
International Nuclear Information System (INIS)
DeVries, R.M.; Peng, J.C.
1980-01-01
We compare sigma/sub R/(E) for nucleus-nucleus systems (obtained from existing direct measurements and derived from elastic scattering data) with nucleon-nucleon and nucleon-nucleus data. The energy dependence of sigma/sub R/(E) for nucleus-nucleus systems is found to be quite rapid; there appears to be no evidence for an energy independent, geometric sigma/sub R/. Simple parameter free microscopic calculations are able to quantitatively reproduce the data and thus, emphasize the dominance of nucleon-nucleon interactions in medium energy nucleus-nucleus collisions
Roy, Bitan; Foster, Matthew S.
2018-01-01
We compute the effects of generic short-range interactions on gapless electrons residing at the quantum critical point separating a two-dimensional Dirac semimetal and a symmetry-preserving band insulator. The electronic dispersion at this critical point is anisotropic (Ek=±√{v2kx2+b2ky2 n } with n =2 ), which results in unconventional scaling of thermodynamic and transport quantities. Because of the vanishing density of states [ϱ (E )˜|E |1 /n ], this anisotropic semimetal (ASM) is stable against weak short-range interactions. However, for stronger interactions, the direct Dirac-semimetal to band-insulator transition can either (i) become a fluctuation-driven first-order transition (although unlikely in a particular microscopic model considered here, the anisotropic honeycomb lattice extended Hubbard model) or (ii) get avoided by an intervening broken-symmetry phase. We perform a controlled renormalization group analysis with the small parameter ɛ =1 /n , augmented with a 1 /n expansion (parametrically suppressing quantum fluctuations in the higher dimension) by perturbing away from the one-dimensional limit, realized by setting ɛ =0 and n →∞ . We identify charge density wave (CDW), antiferromagnet (AFM), and singlet s -wave superconductivity as the three dominant candidates for broken symmetry. The onset of any such order at strong coupling (˜ɛ ) takes place through a continuous quantum phase transition across an interacting multicritical point, where the ordered phase, band insulator, Dirac, and anisotropic semimetals meet. We also present the phase diagram of an extended Hubbard model for the ASM, obtained via the controlled deformation of its counterpart in one dimension. The latter displays spin-charge separation and instabilities to CDW, spin density wave, and Luther-Emery liquid phases at arbitrarily weak coupling. The spin density wave and Luther-Emery liquid phases deform into pseudospin SU(2)-symmetric quantum critical points separating the
Directory of Open Access Journals (Sweden)
Bitan Roy
2018-03-01
Full Text Available We compute the effects of generic short-range interactions on gapless electrons residing at the quantum critical point separating a two-dimensional Dirac semimetal and a symmetry-preserving band insulator. The electronic dispersion at this critical point is anisotropic (E_{k}=±sqrt[v^{2}k_{x}^{2}+b^{2}k_{y}^{2n}] with n=2, which results in unconventional scaling of thermodynamic and transport quantities. Because of the vanishing density of states [ϱ(E∼|E|^{1/n}], this anisotropic semimetal (ASM is stable against weak short-range interactions. However, for stronger interactions, the direct Dirac-semimetal to band-insulator transition can either (i become a fluctuation-driven first-order transition (although unlikely in a particular microscopic model considered here, the anisotropic honeycomb lattice extended Hubbard model or (ii get avoided by an intervening broken-symmetry phase. We perform a controlled renormalization group analysis with the small parameter ε=1/n, augmented with a 1/n expansion (parametrically suppressing quantum fluctuations in the higher dimension by perturbing away from the one-dimensional limit, realized by setting ε=0 and n→∞. We identify charge density wave (CDW, antiferromagnet (AFM, and singlet s-wave superconductivity as the three dominant candidates for broken symmetry. The onset of any such order at strong coupling (∼ε takes place through a continuous quantum phase transition across an interacting multicritical point, where the ordered phase, band insulator, Dirac, and anisotropic semimetals meet. We also present the phase diagram of an extended Hubbard model for the ASM, obtained via the controlled deformation of its counterpart in one dimension. The latter displays spin-charge separation and instabilities to CDW, spin density wave, and Luther-Emery liquid phases at arbitrarily weak coupling. The spin density wave and Luther-Emery liquid phases deform into pseudospin SU(2-symmetric quantum critical
International Nuclear Information System (INIS)
Sharma, S.C.; Kafle, S.R.S.
1983-01-01
The effect of gravity on density distributions has been studied in ethane and methane near their critical points using the linear-model parametric equation of state. The results obtained from this study are used to further understand the sensitivity of orthopositronium annihilation rates to density fluctuations in molecular gases. It is shown that the influence of gravity is too small to account for the recently observed dependence of orthopositronium annihilation rates on the density of ethane gas at 306.4 K. However, a significant variation in local density vs height is calculated at temperatures closer to the gas--liquid critical point. The density and temperature dependencies of the annihilation rates of orthopositronium atoms, recently observed in ethane and methane gases, are discussed in terms of the findings of this study
Yang, Shengfeng; Zhou, Naixie; Zheng, Hui; Ong, Shyue Ping; Luo, Jian
2018-02-01
First-order interfacial phaselike transformations that break the mirror symmetry of the symmetric ∑5 (210 ) tilt grain boundary (GB) are discovered by combining a modified genetic algorithm with hybrid Monte Carlo and molecular dynamics simulations. Density functional theory calculations confirm this prediction. This first-order coupled structural and adsorption transformation, which produces two variants of asymmetric bilayers, vanishes at an interfacial critical point. A GB complexion (phase) diagram is constructed via semigrand canonical ensemble atomistic simulations for the first time.
International Nuclear Information System (INIS)
Konopelchenko, B; Alonso, L MartInez; Medina, E
2010-01-01
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.
Fu, Bo; Zhu, Wei; Shi, Qinwei; Li, Qunxiang; Yang, Jinlong; Zhang, Zhenyu
2017-04-07
Exploiting the enabling power of the Lanczos method in momentum space, we determine accurately the quasiparticle and scaling properties of disordered three-dimensional Dirac semimetals surrounding the quantum critical point separating the semimetal and diffusive metal regimes. We unveil that the imaginary part of the quasiparticle self-energy obeys a common power law before, at, and after the quantum phase transition, but the power law is nonuniversal, whose exponent is dependent on the disorder strength. More intriguingly, whereas a common power law is also found for the real part of the self-energy before and after the phase transition, a distinctly different behavior is identified at the critical point, characterized by the existence of a nonanalytic logarithmic singularity. This nonanalytical correction serves as the very basis for the unusual power-law behaviors of the quasiparticles and many other physical properties surrounding the quantum critical point. Our approach also allows the ready and reliable determination of the scaling properties of the correlation length and dynamical exponents. We further show that the central findings are valid for both uncorrelated and correlated disorder distributions and should be directly comparable with future experimental observations.
Energy Technology Data Exchange (ETDEWEB)
Sivaraman, A.; Kobuyashi, R.; Mayee, J.W.
1984-02-01
Based on Pitzer's three-parameter corresponding states principle, the authors have developed a correlation of the latent heat of vaporization of aromatic coal liquid model compounds for a temperature range from the freezing point to the critical point. An expansion of the form L = L/sub 0/ + ..omega..L /sub 1/ is used for the dimensionless latent heat of vaporization. This model utilizes a nonanalytic functional form based on results derived from renormalization group theory of fluids in the vicinity of the critical point. A simple expression for the latent heat of vaporization L = D/sub 1/epsilon /SUP 0.3333/ + D/sub 2/epsilon /SUP 0.8333/ + D/sub 4/epsilon /SUP 1.2083/ + E/sub 1/epsilon + E/sub 2/epsilon/sup 2/ + E/sub 3/epsilon/sup 3/ is cast in a corresponding states principle correlation for coal liquid compounds. Benzene, the basic constituent of the functional groups of the multi-ring coal liquid compounds, is used as the reference compound in the present correlation. This model works very well at both low and high reduced temperatures approaching the critical point (0.02 < epsilon = (T /SUB c/ - T)/(T /SUB c/- 0.69)). About 16 compounds, including single, two, and three-ring compounds, have been tested and the percent root-mean-square deviations in latent heat of vaporization reported and estimated through the model are 0.42 to 5.27%. Tables of the coefficients of L/sub 0/ and L/sub 1/ are presented. The contributing terms of the latent heat of vaporization function are also presented in a table for small increments of epsilon.
Directory of Open Access Journals (Sweden)
Josiane Pasini
2017-06-01
Full Text Available Pears have a very sensitive epidermis and are prone to signal mechanical blemishes, which result in reduced visual quality and low consumer acceptance. The objective of this work was to identify critical points and the magnitude of impact forces on a packing line at a commercial packinghouse. The effect of injuries on ripening and quality of ´Packham´s Triumph´ pears was also evaluated after cold storage. The packing line was scrutinized on its transfer points, fruit drop heights and cushioning overlays, which allowed to acquire the maximum accelerations on each spot. The maximum acceleration forces were reproduced in the lab with ‘Packham’s Triumph’ pears to evaluate the effects on fruit quality after cold storage. Four critical points were noticed on the packing line: at the transfer from the conveyor belt to the lifting rollers, at the transfer from the lifting rollers to the washing ramp with rotatory brushes, at the entrance to the singulator at the end of the conveyor belt and at the drop from the sizer to the packing stalls. Ripening of ‘Packham’s Triumph’ pears invariably came about during cold storage, and independently of the imposed impacts. The impacts under the circumstances of the test did not affect the quality of ´Packham´s Triumph´ pears kept for up to 120 days at cold storage followed by five days at room temperature.
Multiple critical points and liquid-liquid equilibria from the van der Waals like equations of state
International Nuclear Information System (INIS)
Artemenko, Sergey; Lozovsky, Taras; Mazur, Victor
2008-01-01
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
The chiral critical point of $N_f$=3 QCD at finite density to the order $(\\mu/T)^4$
De Forcrand, Philippe
2008-01-01
QCD with three degenerate quark flavours at zero baryon density exhibits a first order thermal phase transition for small quark masses, which changes to a smooth crossover for some critical quark mass m^c_0, i.e. the chiral critical point. It is generally believed that as an (even) function of quark chemical potential, m_c(mu), the critical point moves to larger quark masses, constituting the critical endpoint of a first order phase transition in theories with m\\geq m^c_0. To test this, we consider a Taylor expansion of m_c(mu) around mu=0 and determine the first two coefficients from lattice simulations with staggered fermions on N_t=4 lattices. We employ two different techniques: a) calculating the coefficients directly from a mu=0 ensemble using a novel finite difference method, and b) fitting them to simulation data obtained for imaginary chemical potentials. The mu^2 and mu^4 coefficients are found to be negative by both methods, with consistent absolute values. Combining both methods gives evidence that...
Energy Technology Data Exchange (ETDEWEB)
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.
DEFF Research Database (Denmark)
Jensen, Ole B.; Morelli, Nicola
2011-01-01
. are connected (and disconnected) we get a much better understanding of how to design and intervene regardless if we are thinking about public spaces in the city or new systems of service design. The many networks orchestrating and facilitating contemporary everyday life are dependent on the strategic sites...
Perspective of ultrarelativistic nucleus-nucleus collisions
International Nuclear Information System (INIS)
Specht, H.J.
1985-01-01
The paper concerns the lectures given at the International School of nuclear physics, Erice, 1985, which survey the expectations for the field of ultrarelativistic nucleus-nucleus collisions. The primary motivation for the field, the organization of the lectures, and a description of the NA 34 experiment, are all briefly given. (U.K.)
High energy nucleus-nucleus collisions
International Nuclear Information System (INIS)
Bhalla, K.B.
1980-01-01
An attempt is made to explain nucleus-nucleus collisions based on nuclear emulsion experiments. Peripheral and central collisions are described in detail. Assuming the fireball model, the concepts of geometry, kinematics and thermodynamics in this model are discussed. Projectile and target fragmentations are studied. The advantages of using nuclear emulsions as detectors, are mentioned. Proton-nucleus collisions and nucleus-nucleus collisions are compared. Interactions, of projectiles such as Ca, B and C on targets such as Pb, Ag, Br etc. at very high energies (approximately 300 to 1700 Gev) are listed. A comparison of the near multiplicities in these interactions is given. A generalized explanation is given on the processes involved in these interactions. (A.K.)
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)
Tognetti, Vincent; Joubert, Laurent; Raucoules, Roman; De Bruin, Theodorus; Adamo, Carlo
2012-06-07
In this paper, we extend the work of Popelier and Logothetis [J. Organomet. Chem. 1998, 555, 101] on the characterization of agosticity by considerably enlarging the set of the studied organometallic molecules. To this aim, 23 representative complexes have been considered, including all first line transition metals at various oxidation states and exhibiting four types of agosticity (α, β, γ, and δ). From these examples, the concepts of agostic atom, agostic bond, and agostic interaction are defined and discussed, notably by advocating Bader's analysis of the electron density. The nature and the local properties of the bond critical points are then investigated, and the relationships with the main geometric parameters of the complexes are particularly examined. Moreover, new local descriptors based on kinetic energy densities are developed in order to provide new tools for bond characterization.
Zaletel, Michael P; Bardarson, Jens H; Moore, Joel E
2011-07-08
Universal logarithmic terms in the entanglement entropy appear at quantum critical points (QCPs) in one dimension (1D) and have been predicted in 2D at QCPs described by 2D conformal field theories. The entanglement entropy in a strip geometry at such QCPs can be obtained via the "Shannon entropy" of a 1D spin chain with open boundary conditions. The Shannon entropy of the XXZ chain is found to have a logarithmic term that implies, for the QCP of the square-lattice quantum dimer model, a logarithm with universal coefficient ±0.25. However, the logarithm in the Shannon entropy of the transverse-field Ising model, which corresponds to entanglement in the 2D Ising conformal QCP, is found to have a singular dependence on the replica or Rényi index resulting from flows to different boundary conditions at the entanglement cut.
Arakcheev, V. G.; Bagratashvili, Viktor N.; Valeev, A. A.; Gordienko, Vyacheslav M.; Kireev, Vyacheslav V.; Morozov, V. B.; Olenin, A. N.; Popov, Vladimir K.; Tunkin, V. G.; Yakovlev, D. V.
2004-01-01
The transformation of the Q-band of the low-frequency 1285-cm-1 component of the 2v2/v1 Fermi doublet of a CO2 molecule is studied in the critical point vicinity (Tc=31.03 °C, Pc=72.8 atm) by the CARS method. CARS spectra were recorded by changing pressure isothermically from 48 to 120 atm at several temperatures in the range between 25 and 36°C. At the temperature above 29°C, the pressure dependences of the Q-band width pass through the maximum, which exceeds by 40% —50% the typical Q-band width in the liquid phase. The position of the maximum shifts to higher pressures with increasing temperature. The inhomogeneous broadening of the Q-band is interpreted based on the cluster microstructure of a supercritical fluid.
Comparison of IBM-2 calculations with X(5) critical point symmetry for low lying states in 128-140Nd
International Nuclear Information System (INIS)
Uluer, I.; Olgun, D.; Inan, S.; Tuerkan, N.
2006-01-01
The X(5) would take place when moving continuously from the pure U(5) symmetry to the SU(3) symmetry and it implies a definite relations among the level energies and among the E2 transition strengths. It was recently shown that a signature of phase transition is observed in the chain of Sm, Mo and Nd isotopes, where 1 52Sm, 1 04Mo and 1 50Nd display the predicted features of the X(5) symmetry and mark therefore the critical point. However, more detailed studies and experiments are needed to get ideas about this signature. Without entering into detail we have firstly compared the results obtained in our previous study of 1 28- 1 40Nd with that of the limits in X(5) symmetry and then given a clear description about the validity of the Hamiltonian parameters used in the study. At the end, we have concluded that some of Nd isotopes display X(5) symmetry features
Pérez-Díez, Cristina; Real-Campaña, José Manuel; Noya-Castro, María Carmen; Andrés-Paricio, Felicidad; Reyes Abad-Sazatornil, María; Bienvenido Povar-Marco, Javier
2017-01-01
To determine the frequency of medication errors and incident types in a tertiary-care hospital emergency department. To quantify and classify medication errors and identify critical points where measures should be implemented to improve patient safety. Prospective direct-observation study to detect errors made in June and July 2016. The overall error rate was 23.7%. The most common errors were made while medications were administered (10.9%). We detected 1532 incidents: 53.6% on workdays (P=.001), 43.1% during the afternoon/evening shift (P=.004), and 43.1% in observation areas (P=.004). The medication error rate was significant. Most errors and incidents occurred during the afternoon/evening shift and in the observation area. Most errors were related to administration of medications.
International Nuclear Information System (INIS)
Kunihiro, Teiji; Minami, Yuki; Tsumura, Kyosuke
2009-01-01
The dynamical density fluctuations around the QCD critical point (CP) are analyzed using relativistic dissipative fluid dynamics, and we show that the sound mode around the QCD CP is strongly attenuated whereas the thermal fluctuation stands out there. We speculate that if possible suppression or disappearance of a Mach cone, which seems to be created by the partonic jets at RHIC, is observed as the incident energy of the heavy-ion collisions is decreased, it can be a signal of the existence of the QCD CP. We have presented the Israel-Stewart type fluid dynamic equations that are derived rigorously on the basis of the (dynamical) renormalization group method in the second part of the talk, which we omit here because of a lack of space.
Kunihiro, Teiji; Minami, Yuki; Tsumura, Kyosuke
2009-11-01
The dynamical density fluctuations around the QCD critical point (CP) are analyzed using relativistic dissipative fluid dynamics, and we show that the sound mode around the QCD CP is strongly attenuated whereas the thermal fluctuation stands out there. We speculate that if possible suppression or disappearance of a Mach cone, which seems to be created by the partonic jets at RHIC, is observed as the incident energy of the heavy-ion collisions is decreased, it can be a signal of the existence of the QCD CP. We have presented the Israel-Stewart type fluid dynamic equations that are derived rigorously on the basis of the (dynamical) renormalization group method in the second part of the talk, which we omit here because of a lack of space.
Pressure-induced unconventional superconductivity near a quantum critical point in CaFe2As2
International Nuclear Information System (INIS)
Kawasaki, S; Tabuchi, T; Zheng Guoqing; Wang, X F; Chen, X H
2010-01-01
75 As-zero-field nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements are performed on CaFe 2 As 2 under pressure. At P = 4.7 and 10.8 kbar, the temperature dependencies of nuclear-spin-lattice relaxation rate (1/T 1 ) measured in the tetragonal phase show no coherence peak just below T 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.
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).
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...
Pion production in nucleus--nucleus collisions
International Nuclear Information System (INIS)
Schroeder, L.S.
1975-06-01
Current work on pion production in high-energy nucleus-nucleus collisions is reviewed. The majority of existing data are of the inclusive variety in which a single final state pion is detected. Experimental data are compared and their possible contributions to obtaining new information on nuclear structure is discussed. Various models which attempt to explain the observed single-inclusive-pion spectra either on the basis of a nucleon-nucleus interaction in which Fermi motion is included or on some type of cooperative model are examined. Other areas of interest involving pion production include tests of charge symmetry and pion multiplicities. (9 figures, 1 table) (U.S.)
International Nuclear Information System (INIS)
Strugalski, Z.
1981-01-01
Qualitative picture of high energy hadron-nucleus collision process, emerging from the analysis of experimental data, is presented. Appropriate description procedure giving a possibility of reproducing various characteristics of this process in terms of the data on elementary hadron-nucleon interaction is proposed. Formula reproducing hadron-nucleus collision cross sections is derived. Inelastic collision cross sections for pion-nucleus and proton-nucleus reactions at wide energy interval are calculated for Pb, Ag, and Al targets. A-dependence of cross sections for pion-nucleus and proton-nucleus collisions at nearly 50 GeV/c momentum were calculated and compared with existing experimental data. Energy dependence of cross sections for hadron-nucleus collisions is determined simply by energy dependence of corresponding cross sections for hadron-nucleon collisions; A-dependence is determined simply by nuclear sizes and nucleon density distributions in nuclei
International Nuclear Information System (INIS)
Davidovs'ka, O.Yi.; Denisov, V.Yu.; Nesterov, V.O.
2010-01-01
Various approaches for nucleus-nucleus interaction potential evaluation are discussed in details. It is shown that the antisymmetrization of nucleons belonging to different nuclei and the Pauli principle give the essential contribution into the nucleus-nucleus potential at distances, when nuclei are strongly overlapping, and lead to appearance of the repulsive core of nucleus nucleus interaction at small distances between nuclei.
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.
International Nuclear Information System (INIS)
Anisimov, M.A.; Agayan, V.A.; Collings, P.J.
1998-01-01
The analogy with the liquid-gas critical point is analyzed to clarify the nature of the pretransitional behavior of physical properties in the vicinity of the Blue-Phase-III endash isotropic transition in chiral liquid crystalline systems. The analogy is unusual: temperature serves as the ordering field and entropy plays the role of the order parameter. Both mean field and parametric equations of state are formulated in terms of scaling fields. The scaling fields are linear combinations of the physical fields, which are temperature and chirality. It is shown that mixing of the physical field variables naturally leads to a strong asymmetry with respect to the transition temperature in the behavior of the physical properties that cannot be described by simple power laws. While the mean field theory gives a good description of the experimental data, the scaling theory, if one incorporates mixing of the field variables, gives even better agreement with the experimental data, placing this transition in the same universality class as the three-dimensional Ising model. copyright 1998 The American Physical Society
Rybczyński, Maciej
2014-01-01
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 indi- cate 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 di- agram and the evolution of the final hadron phase does not erase the fluctuations signals. Further information about the existence and nature of a phase transition in the SPS energy range can be gained from the studies of event-by-event fluctuations of final stat...
Antiproton production in nucleon-nucleus and nucleus-nucleus collisions at the CERN-SPS
International Nuclear Information System (INIS)
Kadija, K.; Schmitz, N.; Seyboth, P.
1996-01-01
A model for antiproton production in nucleon-nucleus and nucleus-nucleus collisions at 200 GeV per nucleon, based on the wounded nucleon model is developed. The predictions are compared to published nucleon-nucleus and sulphur-nucleus data. The results suggest the presence of similar antiproton production processes in nucleon-nucleus and nucleus-nucleus collisions near midrapidity. (orig.)
International Nuclear Information System (INIS)
Gibbs, W.R.
1984-01-01
The K + -nucleus system is reviewed and comparison with data is made. The principal conclusions are that the theoretical uncertainties in relating the K + -nucleus interaction to the K + -nucleon interaction are very small and hence the positive kaon makes an excellent probe of the nucleus. It is suggested that this particle may be more sensitive to non-nucleonic degrees of freedom (especially quarks) than classical probes
International Nuclear Information System (INIS)
Zhang, Xiu-xing; Li, Fu-li
2013-01-01
By using the lowest order expansion in the number of spins, we study the classical correlation (CC) and quantum correlations (QCs) between two spin subgroups of the Lipkin–Meshkov–Glick (LMG) model in both binary and trinary decompositions of spins. In the case of bipartitions, we find that the CC and all the QCs are divergent in the same singular behavior at the critical point of the LMG model. In the case of tripartitions, however, the CC is still divergent but the QCs remain finite at the critical point. The present result shows that the CC is very robust but the QCs are much frangible to the environment disturbance.
Quasiparticle mass enhancement close to the quantum critical point in BaFe2(As(1-x)P(x))2.
Walmsley, P; Putzke, C; Malone, L; Guillamón, I; Vignolles, D; Proust, C; Badoux, S; Coldea, A I; Watson, M D; Kasahara, S; Mizukami, Y; Shibauchi, T; Matsuda, Y; Carrington, A
2013-06-21
We report a combined study of the specific heat and de Haas-van Alphen effect in the iron-pnictide superconductor BaFe2(As(1-x)P(x))2. Our data when combined with results for the magnetic penetration depth give compelling evidence for the existence of a quantum critical point close to x=0.30 which affects the majority of the Fermi surface by enhancing the quasiparticle mass. The results show that the sharp peak in the inverse superfluid density seen in this system results from a strong increase in the quasiparticle mass at the quantum critical point.
Microscopic model of nucleus-nucleus collisions
International Nuclear Information System (INIS)
Harvey, B.G.
1986-04-01
The collision of two nuclei is treated as a collection of collisions between the nucleons of the projectile and those of the target nucleus. The primary projectile fragments contain only those nucleons that did not undergo a collision. The inclusive and coincidence cross sections result from the decay of the excited primary fragments. 15 refs., 5 figs
Directory of Open Access Journals (Sweden)
P. G. Kapiris
2003-01-01
Full Text Available In analogy to the study of critical phase transitions in statistical physics, it has been argued recently that the fracture of heterogeneous materials could be viewed as a critical phenomenon, either at laboratory or at geophysical scales. If the picture of the development of the fracture is correct one may guess that the precursors may reveal the critical approach of the main-shock. When a heterogeneous material is stretched, its evolution towards breaking is characterized by the appearance of microcracks before the final break-up. Microcracks produce both acoustic and electromagnetic(EM emission in the frequency range from VLF to VHF. The microcracks and the associated acoustic and EM activities constitute the so-called precursors of general fracture. These precursors are detectable not only at laboratory but also at geophysical scales. VLF and VHF acoustic and EM emissions have been reported resulting from volcanic and seismic activities in various geologically distinct regions of the world. In the present work we attempt to establish the hypothesis that the evolution of the Earth's crust towards the critical point takes place not only in a mechanical but also in an electromagnetic sense. In other words, we focus on the possible electromagnetic criticality, which is reached while the catastrophic rupture in the Earth's crust approaches. Our main tool is the monitoring of micro-fractures that occur before the final breakup, by recording their radio-electromagnetic emissions. We show that the spectral power law analysis of the electromagnetic precursors reveals distinguishing signatures of underlying critical dynamics, such as: (i the emergence of memory effects; (ii the decrease with time of the anti-persistence behaviour; (iii the presence of persistence properties in the tail of the sequence of the precursors; and (iv the acceleration of the precursory electro-magnetic energy release. Moreover, the statistical analysis of the amplitudes of
Deconfinement of quarks and gluons in nucleus-nucleus collisions
International Nuclear Information System (INIS)
Gorenstein, M.I.
2011-01-01
The energy dependence of hadron production in relativistic nucleus-nucleus collisions reveals the anomalies. They were predicted as the signals of the deconfinement phase transition and observed by NA49 collaboration in Pb+Pb collisions at the CERN SPS. This indicates the onset of the deconfinement in central nucleus-nucleus collisions at about 30 AGeV.
Diffractive ''semioptical'' model for nucleus-nucleus collisions
International Nuclear Information System (INIS)
Barashenkov, V.S.; Musulmanbekov, Zh.Zh.
1979-01-01
Diffraction Glauber theory for nucleus-nucleus collisions is considered in approximation when the initial nucleus interacts as a whole with nucleons of the target nucleus. Such an approach, being intermediate between precise Glauber theory and its optical limit, essentially simplifies numerical calculations and gives a good agreement with experiments as well. (author)
Schuler, Michael; Whitsitt, Seth; Henry, Louis-Paul; Sachdev, Subir; Läuchli, Andreas M
2016-11-18
The low-energy spectra of many body systems on a torus, of finite size L, are well understood in magnetically ordered and gapped topological phases. However, the spectra at quantum critical points separating such phases are largely unexplored for (2+1)D systems. Using a combination of analytical and numerical techniques, we accurately calculate and analyze the low-energy torus spectrum at an Ising critical point which provides a universal fingerprint of the underlying quantum field theory, with the energy levels given by universal numbers times 1/L. We highlight the implications of a neighboring topological phase on the spectrum by studying the Ising* transition (i.e. the transition between a Z_{2} topological phase and a trivial paramagnet), in the example of the toric code in a longitudinal field, and advocate a phenomenological picture that provides qualitative insight into the operator content of the critical field theory.
International Nuclear Information System (INIS)
Shimansky, Yu.I.; Shimanskaya, E.T.
1996-01-01
The temperature dependence of the density along the coexistence curve of benzene in the vicinity of the critical point and in a wide temperature range down to the triple point was investigated. The original results as well as literature data were statistically treated. A regression analysis of data on the critical exponents and critical amplitudes used as fitting parameters in a model equations was carried out. An adequate description of the order parameter by the three-term scaling equation in the entire two-phase (liquid-gas) region of benzene was obtained with experimental values of Β O -0.352 ±0.003 and δ = 1.3 ± 0.2, which are inconsistent with the Ising model (Β O = 0.325) and the Wegner exponent (δ = 0.5), respectively. It is shown that the equation with fixed classical exponents does not adequately describe the experimental data even far from the critical point
Xiu-Xing, Zhang; Fu-Li, Li
2012-01-01
We study the classical correlation (CC) and quantum discord (QD) between two spin subgroups of the Lipkin-Meshkov-Glick (LMG) model in both binary and trinary decompositions of spins. In the case of bipartition, we find that the classical correlations and all the quantum correlations including the QD, the entanglement of formation (EoF) and the logarithmic negativity (LN) are divergent in the same singular behavior at the critical point of the LMG model. In the case of tripartition, however, ...
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.
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.
Candidate sample acquisition systems for the Rosetta
International Nuclear Information System (INIS)
Magnani, P.G.; Gerli, C.; Colombina, G.; Vielmo, P.
1989-01-01
The Comet Nucleus Sample Return (CNSR) mission, one of the four cornerstones of the ESA scientific program, is one of the most complex space ventures within the next century, both from technological and deep space exploration point of view. In the Rosetta scenario the sample acquisition phase represents the most critical point for the global mission's success. The proposed paper illustrates the main results obtained in the context of the CNSR-SAS ongoing activity. The main areas covered are related to: (1) sample properties characterization (comet soil model, physical/chemical properties, reference material for testing); (2) concepts identification for coring, shovelling, harpooning and anchoring; (3) preferred concept (trade off among concepts, identification of the preferred configuration); and (4) proposed development activity for gaining the necessary confidence before finalizing the CNSR mission. Particular emphasis will be given to the robotic and flexibility aspects of the identified sample acquisition systems (SAS) configuration, intended as a means for the overall system performance enhancement
Dissipation in nucleus-nucleus collisions
International Nuclear Information System (INIS)
Santanu Pal
1984-01-01
This paper deals with the mechanism of one- and two-body dissipations in nucleus-nucleus collisions. The average energy transferred to nuclear excitations is calculated using a time-dependent density matrix approach with lowest-order approximations. Considering the nuclei as Fermi gases, and using a gaussian-type NN interaction as the basic perturbation, simplified expressions are obtained for energy dissipations. These expressions are quite instructive to follow a number of interesting aspects of one- and two-body dissipations. It is theoretically observed that the memory time for the two-body dissipation is significantly smaller than that of one-body dissipation. A threshold-type dependence of the transferred energy on the relative velocity between the two nuclei is also observed. This threshold velocity is found to be related with the intrinsic nucleon kinetic energy for two-body dissipation and with the nuclear size for the one-body case. This observation further suggests that the total dissipated energy is shared between the two nuclei approximately in the ratio of their masses. The physical origin of these observations is also explained. Numerical calculations further illustrate some characteristic features of one- and two-body dissipations. (orig.)
High energy nucleus-nucleus scattering and matter radius of unstable nucleus
International Nuclear Information System (INIS)
Sato, H.; Okuhara, Y.
1985-07-01
The interaction cross sections of high energy nucleus-nucleus scattering have been studied with the Glauber Model and Hartree-Fock like variational calculation for the nuclear structure. It is found that the experimental interaction cross sections of the light unstable nucleus-stable nucleus scatterings measured by INS-LBL collaboration are well reproduceable. (author)
Particle correlations in proton-nucleus and nucleus-nucleus collisions
International Nuclear Information System (INIS)
Nagamiya, Sh.
1981-01-01
Particle correlations in proton-nucleus and nucleus-nucleus collisions at energies of 1-2 GeV/nucleon are investigated. The problems of measurement of the mean free path lambda of protons inside the nucleus and the interaction radius of nucleus-nucleus collisions is considered. The value of lambda has been determined in two-proton coincidence experiment in proton-nucleus interaction at 800 MeV. The observed value of lambda is slightly longer than the expected from free nucleon-nucleon collisions. Some preliminary results on proton emission beyond free nucleon-nucleon kinemaics are given
Some experimental results of the investigation of hadron-nucleus and nucleus-nucleus interactions
International Nuclear Information System (INIS)
Azimov, S.A.; Gulamov, K.G.; Chernov, G.M.
1978-01-01
Recent experimental data on the hadron-nucleus and nucleus-nucleus inelastic interactions are analyzed. A particular attention is paid to the description of the leading hadron spectra and of the spectra of nucleon recoils in hadron-nucleus interactions. Some of the results of the experimental studies of correlations between secondary particles are discussed. This discussion demonstrates that an analysis of the multiparticle phenomena is very promising regarding the discrimination between the different models for the hadron-nucleus and nucleus-nucleus interactions. It is pointed out that the actual mechanism of the hadron-nucleus and nucleus-nucleus interactions is a rather complex one and can be described comprehensively by none of the existing models
Fluctuations and correlations in nucleus-nucleus collisions within transport approaches
International Nuclear Information System (INIS)
Konchakovski, Volodymyr P.
2009-01-01
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 optimal
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
Multifragmentation in peripheral nucleus-nucleus collisions
International Nuclear Information System (INIS)
Trautmann, W.; Adloff, J.C.; Bouissou, P.; Hubele, J.; Imme, G.; Iori, I.; Kreutz, P.; Leray, S.; Lindenstruth, V.; Liu, Z.; Lynen, U.; Meijer, R.J.; Milkau, U.; Moroni, A.; Mueller, W.F.J.; Ngo, C.; Ogilvie, C.A.; Pochodzalla, J.; Raciti, G.; Rudolf, G.; Schuettauf, A.; Stuttge, L.
1993-10-01
The complete fragmentation of highly excited nuclear systems into fragments of intermediate mass is observed in heavy-ion reactions at relativistic bombarding energies in the range of several hundreds of MeV per nucleon. Similar features are found for peripheral collisions between heavy nuclei and for more central collisions between a heavy and a light nucleus. The partition space explored in multifragment decays is well described by the statistical multifragmentation models. The expansion before breakup is confirmed by the analysis of the measured fragment energies of ternary events in their own rest frame. Collective radial flow is confined to rather small values in these peripheral-type reactions. Many conceptually different models seem to be capable of reproducing the charge correlations measured for the multifragment decays. (orig.)
Antiproton-nucleus interaction
International Nuclear Information System (INIS)
Gibbs, W.R.
1984-01-01
Several facets of antinucleon-nucleus interactions are explored. The topics treated are: coherent interactions, production of unusual states and particles in the nuclear medium, and the creation of extreme states of matter by antimatter annihilation. It is found that temperatures of the magnitude necessary to achieve the predicted quark-gluon phase transition are obtained. 20 references
Nucleus accumbens and impulsivity
Basar, K.; Sesia, T.; Groenewegen, H.J.; Steinbusch, H.W.; Visser-vandewalle, V.; Temel, Y.
2010-01-01
The multifaceted concept of impulsivity implies that different impulsivity aspects, mediated by different neural processes, influence behavior at different levels. The nucleus accumbens (NAc) is a key component of the neural processes regulating impulsivity. In this review, we discuss the findings
Quasi-elastic shadowing in nucleus-nucleus elastic scattering
Energy Technology Data Exchange (ETDEWEB)
Dymarz, R; Malecki, A [Institute of Nuclear Physics, Krakow (Poland); Gluski, K [Institute of Nuclear Research, Warsaw (Poland); Picchi, P [Turin Univ. (Italy). Ist. di Fisica; Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica)
1979-01-06
The complete evaluation of the Glauber multiple-scattering series for nucleus-nucleus collisions is a very difficult task and that is why various approximate formulae were proposed. In this work some of these approximations are discussed.
Mechanisms of High Energy Hadron-Nucleus and Nucleus-Nucleus Collision Processes
International Nuclear Information System (INIS)
Strugalski, Z.
1994-01-01
Mechanisms of high energy hadron-nucleus and nucleus-nucleus collision processes are depicted qualitatively, as prompted experimentally. In hadron-nucleus collisions the interaction of the incident hadron in intranuclear matter is localized in small cylindrical volume, with the radius as large as the strong interaction range is, centered on the hadron course in the nucleus. The nucleon emission is induced by the hadron in its passing through the nucleus; particles are produced via intermediate objects produced in 2 → 2 endoergic reactions of the hadron and its successors with downstream nucleons. In nucleus-nucleus collisions, the outcome of the reaction appears as the composition of statistically independent hadron-nucleus collision outcomes at various impact parameters. Observable effects supporting such mechanisms are discussed. 51 refs
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.
Deexcitation of superdeformed bands in the nucleus Tb-151
Finck, C; Appelbe, D; Beck, FA; Byrski, T; Cullen, D; Curien, D; deFrance, G; Duchene, G; Erturk, S; Haas, B; Khadiri, N; Kharraja, B; Prevost, D; Rigollet, C; Stezowski, O; Twin, P; Vivien, JP; Zuber, K
1997-01-01
The aim of this work is to get more informations about the decay-out of superdeformed bands. One of the best candidates in the mass A similar or equal to 150 region for that kind of research is the nucleus Tb-151. From previous works, it has been established that the first excited band goes lower in
Study of Relativistic Nucleus - Nucleus Collisions
2002-01-01
The aim of the experiment is to survey the reaction mechanisms involved in the collision of 60~GeV/nucleon and 200~GeV/nucleon light ions ($^{16}$0 and $^{32}$S provided by a new GSI-LBL injector) with different nuclei, to determine the stopping power of nuclear matter and to search for evidence of the formation of quark matter by comparison to hadron-nucleus reactions at the same incident energies. \\\\ The experimental set-up consists of a 2 m Streamer Chamber in the Vertex Magnet used to detect all the charged particles emerging from the interaction as well as the neutral strange particles that decay inside the chamber. The high energy of the forward-going particles are detected by four sets of calorimeters. A highly segmented Photon Position Detector (PPD) backed up by a 240 segment Ring Calorimeter will cover one unit of rapidity around mid-rapidity. An Intermediate Calorimeter will cover the rest of the forward phase space except for the region around beam rapidity, where a Veto Calorimeter will detect be...
Energy Technology Data Exchange (ETDEWEB)
Endo, T. (Hitachi, Ltd., Tokyo (Japan)); Arai, D.; Uematsu, M. (Keio University, Tokyo (Japan). Faculty of Science and Technology)
1993-02-25
Related to the natural gas transport by pipeline, etc., the critical point, dew point and bubble point of natural gas were presumed by calculation through equation of state for determining the exact thermophysical values. The natural gas is multi-component mixed fluid which is represented by methane as a representative component. It considerably differs in composition by its place of origin. Because the conventional method was complicated in process for thermodynamically determining the most stable composition of phases, algorithm of phasic equilibrium was applied by the equation of state which used the discrimination method by Nitta, et al. for the therodynamic stability of phases. The method by Michelsen was applied to the flash calculation, and figuration of both dew point and bubble point curves, while that by Heidemann, et al. was done to the critical point calculation. Peng-Robinson's was applied to an equation of state. To start the calculation, the constant of seven two-component systems the main component of which was methane was determined as a function of temperature based on the actually measured gas/liquid equilibrium value. Then, possibility of calculatively presuming the thermophysical values was shown through comparison of the actually measured values with those obtained by applying the present method to the above systems. Finally, the presumption was made for the natural gas which differed in place of origin. 17 refs., 15 figs., 2 tabs.
International Nuclear Information System (INIS)
Fowler, G.N.; Navarra, F.S.; Plumer, M.; Lawrence Berkeley Laboratory, Nuclear Science Division, Berkeley, California 94720); Vourdas, A.; Weiner, R.M.
1989-01-01
The interacting gluon model developed to describe the inelasticity distribution in hadron-nucleon collisions has been generalized and applied to hadron-nucleus and nucleus-nucleus interactions. Leading particle spectra and energy distributions in hadron-nucleus and nucleus-nucleus collisions are calculated
Meson-nucleus potentials and the search for meson-nucleus bound states
Metag, V.; Nanova, M.; Paryev, E. Ya.
2017-11-01
Recent experiments studying the meson-nucleus interaction to extract meson-nucleus potentials are reviewed. The real part of the potentials quantifies whether the interaction is attractive or repulsive while the imaginary part describes the meson absorption in nuclei. The review is focused on mesons which are sufficiently long-lived to potentially form meson-nucleus quasi-bound states. The presentation is confined to meson production off nuclei in photon-, pion-, proton-, and light-ion induced reactions and heavy-ion collisions at energies near the production threshold. Tools to extract the potential parameters are presented. In most cases, the real part of the potential is determined by comparing measured meson momentum distributions or excitation functions with collision model or transport model calculations. The imaginary part is extracted from transparency ratio measurements. Results on K+ ,K0 ,K- , η ,η‧ , ω, and ϕ mesons are presented and compared with theoretical predictions. The interaction of K+ and K0 mesons with nuclei is found to be weakly repulsive, while the K- , η ,η‧ , ω and ϕ meson-nucleus potentials are attractive, however, with widely different strengths. Because of meson absorption in the nuclear medium the imaginary parts of the meson-nucleus potentials are all negative, again with a large spread. An outlook on planned experiments in the charm sector is given. In view of the determined potential parameters, the criteria and chances for experimentally observing meson-nucleus quasi-bound states are discussed. The most promising candidates appear to be the η and η‧ mesons.
Nucleus-nucleus collision as superposition of nucleon-nucleus collisions
International Nuclear Information System (INIS)
Orlova, G.I.; Adamovich, M.I.; Aggarwal, M.M.
1999-01-01
Angular distributions of charged particles produced in 16 O and 32 S collisions with nuclear track emulsion were studied at momenta 4.5 and 200 A GeV/c. Comparison with the angular distributions of charged particles produced in proton-nucleus collisions at the same momentum allows to draw the conclusion, that the angular distributions in nucleus-nucleus collisions can be seen as superposition of the angular distributions in nucleon-nucleus collisions taken at the same impact parameter b NA , that is mean impact parameter between the participating projectile nucleons and the center of the target nucleus. (orig.)
Nucleus-Nucleus Collision as Superposition of Nucleon-Nucleus Collisions
International Nuclear Information System (INIS)
Orlova, G.I.; Adamovich, M.I.; Aggarwal, M.M.; Alexandrov, Y.A.; Andreeva, N.P.; Badyal, S.K.; Basova, E.S.; Bhalla, K.B.; Bhasin, A.; Bhatia, V.S.; Bradnova, V.; Bubnov, V.I.; Cai, X.; Chasnikov, I.Y.; Chen, G.M.; Chernova, L.P.; Chernyavsky, M.M.; Dhamija, S.; Chenawi, K.El; Felea, D.; Feng, S.Q.; Gaitinov, A.S.; Ganssauge, E.R.; Garpman, S.; Gerassimov, S.G.; Gheata, A.; Gheata, M.; Grote, J.; Gulamov, K.G.; Gupta, S.K.; Gupta, V.K.; Henjes, U.; Jakobsson, B.; Kanygina, E.K.; Karabova, M.; Kharlamov, S.P.; Kovalenko, A.D.; Krasnov, S.A.; Kumar, V.; Larionova, V.G.; Li, Y.X.; Liu, L.S.; Lokanathan, S.; Lord, J.J.; Lukicheva, N.S.; Lu, Y.; Luo, S.B.; Mangotra, L.K.; Manhas, I.; Mittra, I.S.; Musaeva, A.K.; Nasyrov, S.Z.; Navotny, V.S.; Nystrand, J.; Otterlund, I.; Peresadko, N.G.; Qian, W.Y.; Qin, Y.M.; Raniwala, R.; Rao, N.K.; Roeper, M.; Rusakova, V.V.; Saidkhanov, N.; Salmanova, N.A.; Seitimbetov, A.M.; Sethi, R.; Singh, B.; Skelding, D.; Soderstrem, K.; Stenlund, E.; Svechnikova, L.N.; Svensson, T.; Tawfik, A.M.; Tothova, M.; Tretyakova, M.I.; Trofimova, T.P.; Tuleeva, U.I.; Vashisht, Vani; Vokal, S.; Vrlakova, J.; Wang, H.Q.; Wang, X.R.; Weng, Z.Q.; Wilkes, R.J.; Yang, C.B.; Yin, Z.B.; Yu, L.Z.; Zhang, D.H.; Zheng, P.Y.; Zhokhova, S.I.; Zhou, D.C.
1999-01-01
Angular distributions of charged particles produced in 16 O and 32 S collisions with nuclear track emulsion were studied at momenta 4.5 and 200 A GeV/c. Comparison with the angular distributions of charged particles produced in proton-nucleus collisions at the same momentum allows to draw the conclusion, that the angular distributions in nucleus-nucleus collisions can be seen as superposition of the angular distributions in nucleon-nucleus collisions taken at the same impact parameter b NA , that is mean impact parameter between the participating projectile nucleons and the center of the target nucleus
Nucleus-Nucleus Collision as Superposition of Nucleon-Nucleus Collisions
Energy Technology Data Exchange (ETDEWEB)
Orlova, G I; Adamovich, M I; Aggarwal, M M; Alexandrov, Y A; Andreeva, N P; Badyal, S K; Basova, E S; Bhalla, K B; Bhasin, A; Bhatia, V S; Bradnova, V; Bubnov, V I; Cai, X; Chasnikov, I Y; Chen, G M; Chernova, L P; Chernyavsky, M M; Dhamija, S; Chenawi, K El; Felea, D; Feng, S Q; Gaitinov, A S; Ganssauge, E R; Garpman, S; Gerassimov, S G; Gheata, A; Gheata, M; Grote, J; Gulamov, K G; Gupta, S K; Gupta, V K; Henjes, U; Jakobsson, B; Kanygina, E K; Karabova, M; Kharlamov, S P; Kovalenko, A D; Krasnov, S A; Kumar, V; Larionova, V G; Li, Y X; Liu, L S; Lokanathan, S; Lord, J J; Lukicheva, N S; Lu, Y; Luo, S B; Mangotra, L K; Manhas, I; Mittra, I S; Musaeva, A K; Nasyrov, S Z; Navotny, V S; Nystrand, J; Otterlund, I; Peresadko, N G; Qian, W Y; Qin, Y M; Raniwala, R; Rao, N K; Roeper, M; Rusakova, V V; Saidkhanov, N; Salmanova, N A; Seitimbetov, A M; Sethi, R; Singh, B; Skelding, D; Soderstrem, K; Stenlund, E; Svechnikova, L N; Svensson, T; Tawfik, A M; Tothova, M; Tretyakova, M I; Trofimova, T P; Tuleeva, U I; Vashisht, Vani; Vokal, S; Vrlakova, J; Wang, H Q; Wang, X R; Weng, Z Q; Wilkes, R J; Yang, C B; Yin, Z B; Yu, L Z; Zhang, D H; Zheng, P Y; Zhokhova, S I; Zhou, D C
1999-03-01
Angular distributions of charged particles produced in {sup 16}O and {sup 32}S collisions with nuclear track emulsion were studied at momenta 4.5 and 200 A GeV/c. Comparison with the angular distributions of charged particles produced in proton-nucleus collisions at the same momentum allows to draw the conclusion, that the angular distributions in nucleus-nucleus collisions can be seen as superposition of the angular distributions in nucleon-nucleus collisions taken at the same impact parameter b{sub NA}, that is mean impact parameter between the participating projectile nucleons and the center of the target nucleus.
The imaginary part of the nucleus - nucleus optical potential
International Nuclear Information System (INIS)
Phatak, S.C.; Sinha, B.
1978-01-01
The contribution to the imaginary nucleus - nucleus optical potential has been estimated by evaluating the energy - conserving seocond-order term in the perturbation series. The incoming nuclear field is supposed to excite nucleons in a nucleus in this calculation and the nuclear excitations are approximated by particle-hole excitations in a Fermi gas. The resulting imaginary potential compares favourably with phenomenological potentials. (author)
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.
International Nuclear Information System (INIS)
Staśkiewicz, B.; Okrasiński, W.
2012-01-01
We propose a simple analytical form of the vapor–liquid equilibrium curve near the critical point for Lennard-Jones fluids. Coexistence densities curves and vapor pressure have been determined using the Van der Waals and Dieterici equation of state. In described method the Bernoulli differential equations, critical exponent theory and some type of Maxwell's criterion have been used. Presented approach has not yet been used to determine analytical form of phase curves as done in this Letter. Lennard-Jones fluids have been considered for analysis. Comparison with experimental data is done. The accuracy of the method is described. -- Highlights: ► We propose a new analytical way to determine the VLE curve. ► Simple, mathematically straightforward form of phase curves is presented. ► Comparison with experimental data is discussed. ► The accuracy of the method has been confirmed.
LaCu_{6-x}Ag_{x}: A promising host of an elastic quantum critical point
Energy Technology Data Exchange (ETDEWEB)
Poudel, Lekh [ORNL; Dela Cruz, Clarina R. [ORNL; Koehler, Michael R. [University of Tennessee, Knoxville (UTK); McGuire, Michael A. [ORNL; Keppens, Veerle [University of Tennessee, Knoxville (UTK); Mandrus, David [ORNL; Christianson, Andrew D. [ORNL
2018-05-01
Structural properties of LaCu_{6-x}Ag_{x} have been investigated using neutron and x-ray diffraction, and resonant ultrasound spectroscopy (RUS) measurements. Diffraction measurements indicate a continuous structural transition from orthorhombic (Pnma) to monoclinic (P2₁/C) structure. RUS measurements show softening of natural frequencies at the structural transition, consistent with the elastic nature of the structural ground state. The structural transition temperatures in LaCu_{6-x}Ag_{x} decrease with Ag composition until the monoclinic phase is completely suppressed at x_{c}=0.225. All of the evidence is consistent with the presence of an elastic quantum critical point in LaCu_{6-x}Ag_{x}.
International Nuclear Information System (INIS)
Pérez-Sánchez, G.; Troncoso, J.; Losada-Pérez, P.; Méndez-Castro, P.; Romaní, L.
2013-01-01
Highlights: • Highly precise liquid–liquid curves for [Bmim][BF 4 ] + perfluoroctanol are reported. • Critical behavior of heat capacity for the same system was also characterized. • In contrast to previous results, no coulombic/solvophobic crossover for coexistence curve diameter was found. • The system criticality shows characteristics both solvophobic and coulombic. -- Abstract: Liquid + liquid equilibrium of the system [Bmim][BF 4 ] + 1H, 1H, 2H, 2H perfluoroctanol using a highly precise methodology based on refractive index measurements was experimentally determined. In addition, isobaric heat capacity near the critical point was obtained. The performance of the new refractive index set-up was successfully checked against the coexistence curve of the system dimethyl carbonate + decane, since highly accurate data are available in the literature. The choice of [Bmim][BF 4 ] + 1H, 1H, 2H, 2H perfluoroctanol was motivated by a previous experimental work, whose results suggest that this system could present characteristics of both solvophobic and coulombic behavior, which are the two categories to which an ionic system can belong. Although this was previously observed for other ionic systems, this mixture presented a very striking feature: the diameter of the coexistence curve seemed to change its criticality in the studied temperature range, from solvophobic far away to coulombic close to the critical point. The results of this work reveal that, in fact, [Bmim][BF 4 ] + 1H, 1H, 2H, 2H perfluoroctanol presents characteristics of both solvophobic and coulombic criticality, but no evidence of the observed crossover over the experimental temperature range has been found
Energy Technology Data Exchange (ETDEWEB)
Bae, Seong Jun; Oh, Bongseong; Ahn, Yoonhan; Baik, Seongjoon; Lee, Jekyoung; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of)
2016-05-15
It was identified that controlling CO{sub 2} compressor operation near the critical point is one of the most important issues to operate a S-CO{sub 2} Brayton cycle with a high efficiency. Despite the growing interest in the S-CO{sub 2} Brayton cycle, a few previous research on the transient analysis of the S-CO{sub 2} system has been conducted previously. Moreover, previous studies have some limitation in the modelled test facility, and the experiment was not performed to observe specific scenario. The KAIST research team has conducted S-CO{sub 2} system transient experiments with the CO{sub 2} compressing test facility called SCO{sub 2}PE (Supercritical CO{sub 2} Pressurizing Experiment) at KAIST In this study, authors use the transient analysis code GAMMA (Gas Multidimensional Multicomponent mixture Analysis) code for analyzing the experiment. Two transient scenarios were selected in this study; over cooling and under cooling situations. The selected transient situation is of particular interest since the compressor inlet conditions start to drift away from the critical point of CO{sub 2}. The results represent that the GAMMA code can simulate the S-CO{sub 2} test facility, SCO{sub 2}PE. However, as shown in the cooling water flow rate increasing scenario, the GAMMA code shows calculation error when the phase change occurs. Furthermore, although the results of the cooling water flow rate decrease case shows reasonable agreement with the experimental data, there are still some unexplained differences between the experimental data and the GAMMA code prediction.
Global features of nucleus-nucleus collisions in ultrarelativistic domain
International Nuclear Information System (INIS)
Savina, M.V.; Shmatov, S.V.; Slavin, N.V.; Zarubin, P.I.
1998-01-01
HIJING generator simulation of nucleus-nucleus collisions at ultrarelativistic energies is presented. It is shown that the global characteristics of nucleus-nucleus collisions, such as distribution of a charged multiplicity, total and electromagnetic transverse energy over pseudorapidity are rather sensitive to some predictions of models of high-exited nuclear medium formation, namely parton energy losses in dense nuclear matter. These losses result in appearance of a broad maximum in global variable distributions over pseudorapidity. The most profound of this effect occurs at central heavy ion collisions at LHC energy
Higgs-boson production in nucleus-nucleus collisions
International Nuclear Information System (INIS)
Anon.
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
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.
Scaling phenomenon in relativistic nucleus-nucleus collisions
International Nuclear Information System (INIS)
Wong, C.Y.; Blankenbecler, R.
1980-01-01
New scaling variables for proton and pion production in relativistic nucleus-nucleus collisions are introduced which are the generalizations of the Feynmann scaling variable. They allow a simple description of the cross sections at forward and backward angles. 2 figures
Momentum loss in proton-nucleus and nucleus-nucleus collisions
International Nuclear Information System (INIS)
Khan, F.; Townsend, L.W.
1993-12-01
An optical model description, based on multiple scattering theory, of longitudinal momentum loss in proton-nucleus and nucleus-nucleus collisions is presented. The crucial role of the imaginary component of the nucleon-nucleon transition matrix in accounting for longitudinal momentum transfer is demonstrated. Results obtained with this model are compared with Intranuclear Cascade (INC) calculations, as well as with predictions from Vlasov-Uehling-Uhlenbeck (VUU) and quantum molecular dynamics (QMD) simulations. Comparisons are also made with experimental data where available. These indicate that the present model is adequate to account for longitudinal momentum transfer in both proton-nucleus and nucleus-nucleus collisions over a wide range of energies
Model for nucleus-nucleus, hadron-nucleus and hadron-proton multiplicity distributions
International Nuclear Information System (INIS)
Singh, C.P.; Shyam, M.; Tuli, S.K.
1986-07-01
A model relating hadron-proton, hadron-nucleus and nucleus-nucleus multiplicity distributions is proposed and some interesting consequences are derived. The values of the parameters are the same for all the processes and are given by the QCD hypothesis of ''universal'' hadronic multiplicities which are found to be asymptotically independent of target and beam in hadronic and current induced reactions in particle physics. (author)
The intercalatus nucleus of Staderini.
Cascella, Marco
2016-01-01
Rutilio Staderini was one of the leading Italian anatomists of the twentieth century, together with some scientists, such as Giulio Chiarugi, Giovanni Vitali, and others. He was also a member of a new generation of anatomists. They had continued the tradition of the most famous Italian scientists, which started from the Renaissance up until the nineteenth century. Although he carried out important studies of neuroanatomy and comparative anatomy, as well as embryology, his name is rarely remembered by most medical historians. His name is linked to the nucleus he discovered: the Staderini nucleus or intercalated nucleus, a collection of nerve cells in the medulla oblongata located lateral to the hypoglossal nucleus. This article focuses on the biography of the neuroanatomist as well as the nucleus that carries his name and his other research, especially on comparative anatomy and embryology.
Citizen Candidates Under Uncertainty
Eguia, Jon X.
2005-01-01
In this paper we make two contributions to the growing literature on "citizen-candidate" models of representative democracy. First, we add uncertainty about the total vote count. We show that in a society with a large electorate, where the outcome of the election is uncertain and where winning candidates receive a large reward from holding office, there will be a two-candidate equilibrium and no equilibria with a single candidate. Second, we introduce a new concept of equilibrium, which we te...
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.
Directory of Open Access Journals (Sweden)
J. K. Dong
2011-09-01
Full Text Available The in-plane resistivity ρ and thermal conductivity κ of the heavy-fermion superconductor Ce_{2}PdIn_{8} single crystals were measured down to 50 mK. A field-induced quantum critical point, occurring at the upper critical field H_{c2}, is demonstrated from the ρ(T∼T near H_{c2} and ρ(T∼T^{2} when further increasing the field. The large residual linear term κ_{0}/T at zero field and the rapid increase of κ(H/T at low field give evidence for nodal superconductivity in Ce_{2}PdIn_{8}. The jump of κ(H/T near H_{c2} suggests a first-order-like phase transition at low temperature. These results mimic the features of the famous CeCoIn_{5} superconductor, implying that Ce_{2}PdIn_{8} may be another interesting compound to investigate for the interplay between magnetism and superconductivity.
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.
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.
Silk fibroin porous scaffolds for nucleus pulposus tissue engineering
International Nuclear Information System (INIS)
Zeng, Chao; Yang, Qiang; Zhu, Meifeng; Du, Lilong; Zhang, Jiamin; Ma, Xinlong; Xu, Baoshan; Wang, Lianyong
2014-01-01
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
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.
Formation of light particles in nucleus-nucleus collisions
International Nuclear Information System (INIS)
Zagrebaev, V.; Penionzhkevich, Yu.
1993-01-01
The principal experimental results on the yield of the light charged particles in nucleus-nucleus collisions at the low and intermediate energies are reviewed. Inclusive spectra of light particles and their coincidences with the characteristic KX-rays, γ-rays, neutrons, projectile-like fragments, other light particles, fission fragments, and evaporation residues are analyzed. The main theoretical models used for the description of the light particle formation are briefly outlined together with their merits and shortcomings. The unsolved problems of fast light particle formation, in particular, and of nucleus-nucleus interaction dynamics, on the whole, are discussed with the outlooks of new experiments able to clear up some of these problems. (author) 144 refs., 40 figs., 2 tabs
Nucleus-nucleus interactions in the transition energy regime
International Nuclear Information System (INIS)
Volant, C.
1985-02-01
There are at least two ways for studying large interactions in nucleus-nucleus collisions. One way is to use the method of angular correlations between fission fragments. The aim of the experiments presented here was to make a survey on the role of the various experimental parameters. In that respect three targets have been studied and different projectiles and bombarding energies have been used. Results are presented and discussed
Diabatic interaction potential for nucleus-nucleus collisions
International Nuclear Information System (INIS)
Noerenberg, W.; Lukasiak, A.
1984-01-01
Within a refined method for the construction of diabatic states allowing for the treatment of the full spin-orbit coupling, characteristic features of the diabatic potential for nucleus-nucleus collisions are investigated. Approximately 90% of the strong repulsion results from diabatic particle-hole excitations, while only 10% is due to compression. The diabatic interaction potential describes a physical situation intermediate between adiabatic and sudden approximations. (orig.)
Bourouaine, Sofiane; Perez, Jean C.
2018-05-01
In this Letter, we present an analysis of two-point, two-time correlation functions from high-resolution numerical simulations of Reflection-driven Alfvén Turbulence near the Alfvén critical point r c. The simulations model the turbulence in a prescribed background solar wind model chosen to match observational constraints. This analysis allows us to investigate the temporal decorrelation of solar wind turbulence and the validity of Taylor’s approximation near the heliocentric distance r c, which Parker Solar Probe (PSP) is expected to explore in the coming years. The simulations show that the temporal decay of the Fourier-transformed turbulence decorrelation function is better described by a Gaussian model rather than a pure exponential time decay, and that the decorrelation frequency is almost linear with perpendicular wave number k ⊥ (perpendicular with respect to the background magnetic field {{\\boldsymbol{B}}}0). Based on the simulations, we conclude that Taylor’s approximation cannot be used in this instance to provide a connection between the frequency ω of the time signal (measured in the probe frame) and the wavevector k ⊥ of the fluctuations because the frequency k ⊥ V sc (V sc is the spacecraft speed) near r c is comparable to the estimated decorrelation frequency. However, the use of Taylor’s approximation still leads to the correct spectral indices of the power spectra measured at the spacecraft frame. In this Letter, based on a Gaussian model, we suggest a modified relationship between ω and k ⊥, which might be useful in the interpretation of future PSP measurements.
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.
K+ nucleus total cross sections
International Nuclear Information System (INIS)
Sawafta, R.
1990-01-01
The scattering of K + mesons from nuclei has attracted considerable interest in the last few years. The K + holds a very special position as the weakest of all strongly interaction probes. The average cross section is not larger than about 10 mb at lab momenta below 800 MeV/c, corresponding to a mean free path in the nucleus larger than 5 fm. Thus the K + is capable of probing the entire volume of the nucleus. Single scattering of the K + with a nucleon in the nucleus dominates the nuclear scattering, and only small and calculable higher order corrections are needed. The nucleon is a dynamical entity and its internal structure can, in principle, be altered by its surrounding nuclear environment. This work reports an experiment in which the K + is used to compare the nucleon in the nucleus with a free nucleon
182Pt as a possible candidate for X(5) symmetry
International Nuclear Information System (INIS)
Petkov, P; Gladnsihki, K A; Dewald, A; Fransen, C; Hackstein, M; Jolie, J; Pissulla, Th; Rother, W; Zell, K O
2012-01-01
Recently, a new island of X(5) nuclei has been suggested around A=180 exemplified by some Osmium isotopes. To investigate the limits of its region, a Recoil-distance Doppler shift lifetime measurement has been performed for 182 Pt. For the data analysis, the Differential decay curve method has been applied in a newly developed version convenient for low recoil velocities and a non-negligible fraction of nuclei stopped already in the target. The level energies and the newly deduced transition quadrupole moments in the yrast band reveal the persistence of X(5) features in the investigated nucleus, but other spectroscopic data and IBM and GCM calculations indicate shape coexistence and a position of 182 Pt close but not at the critical point of the shape-transition.
Dimuon enhancement in nucleus-nucleus ultrarelativistic interactions
International Nuclear Information System (INIS)
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.
1999-01-01
The study of muon pairs in the mass region 1.5 μμ 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·B and centrality is observed
Characterisation of a candidate dual AGN
Lena, D.; Panizo-Espinar, G.; Jonker, P. G.; Torres, M.; Heida, M.
2018-05-01
We present Chandra and optical observations of a candidate dual AGN discovered serendipitously while searching for recoiling black holes via a cross-correlation between the serendipitous XMM source catalog (2XMMi) and SDSS-DR7 galaxies with a separation no larger than ten times the sum of their Petrosian radii. The system has a stellar mass ratio M1/M2 ≈ 0.7. One of the galaxies (Source 1) shows clear evidence for AGN activity in the form of hard X-ray emission and optical emission-line diagnostics typical of AGN ionisation. The nucleus of the other galaxy (Source 2) has a soft X-ray spectrum, bluer colours, and optical emission line ratios dominated by stellar photoionisation with a "composite" signature, which might indicate the presence of a weak AGN. When plotted on a diagram with X-ray luminosity vs [OIII] luminosity both nuclei fall within the locus defined by local Seyfert galaxies. From the optical spectrum we estimate the electron densities finding n1 active nature of Source 1 can be established with confidence, whether the nucleus of Source 2 is active remains a matter of debate. Evidence that a faint AGN might reside in its nucleus is, however, tantalising.
The momentum distribution inside nucleus
International Nuclear Information System (INIS)
Fujita, T.
1985-01-01
Discussions are made on several reactions which can determine the momentum distribution inside nucleus. The first reaction discussed is the high energy heavy ion collision. This reaction involves many nucleons which interact strongly. Therefore, one must be careful for any possible final state interactions. The expression for the single particle momentum distribution is given. And it can be said that the expression is consistent with the description of the energetic neutrons from muon capture by heavy nucleus. The best way to determine the momentum distribution would be the lepton-nucleus scattering since it does not involve the strong interaction in the initial channel. Another reaction discussed is the backward proton production, which is governed by quite complicated reaction processes. Therefore, the determination of the momentum distribution is only indirect. Noverthless, it is found that this reaction presents a very interesting and important information on the momentum distribution. (Aoki, K.)
Nucleus management with irrigating vectis
Directory of Open Access Journals (Sweden)
Srinivasan Aravind
2009-01-01
Full Text Available The main objective in modern cataract surgery is to achieve a better unaided visual acuity with rapid post-surgical recovery and minimal surgery-related complications. Early visual rehabilitation and better unaided vision can be achieved only by reducing the incision size. In manual small incision cataract surgery (MSICS, incision is between 5.5 to 7 mm. Once the nucleus is prolapsed into the anterior chamber, it can be extracted through the tunnel. Nucleus extraction with an irrigating vectis is a very simple technique, which combines mechanical and hydrostatic forces to express out the nucleus. This technique is time-tested with good results and more than 95% of nuclei in MSICS are extracted in this way offering all the merits of phacoemulsification with the added benefits of having wider applicability, better safety, shorter learning curve and lower cost.
Baarlink, Christian; Grosse, Robert
2014-01-01
Many if not most proteins can, under certain conditions, change cellular compartments, such as, for example, shuttling from the cytoplasm to the nucleus. Thus, many proteins may exert functions in various and very different subcellular locations, depending on the signaling context. A large amount of actin regulatory proteins has been detected in the mammalian cell nucleus, although their potential roles are much debated and are just beginning to emerge. Recently, members of the formin family of actin nucleators were also reported to dynamically localize to the nuclear environment. Here we discuss our findings that specific diaphanous-related formins can promote nuclear actin assembly in a signal-dependent manner.
International Nuclear Information System (INIS)
Peng, J.C.
1986-05-01
Status and future prospects of antiproton-nucleus scattering experiments are presented. These scattering experiments were conducted at antiproton beam momentums of 300 and 600 MeV/c on target nuclei of 6 Li, 12 C, 16 O, 18 O, 40 Ca, 48 Ca, and 208 Pb. Antiproton-proton reactions investigated antiproton-nucleus bound or resonant states in antiproton reactions with d, 6 Li, 12 C, 63 Cu, and 209 Bi. Inelastic scattering experiments investigated the spin-isospin dependence of the NN interactions. 19 refs., 1 fig., 1 tab
Functionalized active-nucleus complex sensor
Pines, Alexander; Wemmer, David E.; Spence, Megan; Rubin, Seth
2003-11-25
A functionalized active-nucleus complex sensor that selectively associates with one or more target species, and a method for assaying and screening for one or a plurality of target species utilizing one or a plurality of functionalized active-nucleus complexes with at least two of the functionalized active-nucleus complexes having an attraction affinity to different corresponding target species. The functionalized active-nucleus complex has an active-nucleus and a targeting carrier. The method involves functionalizing an active-nucleus, for each functionalized active-nucleus complex, by incorporating the active-nucleus into a macromolucular or molecular complex that is capable of binding one of the target species and then bringing the macromolecular or molecular complexes into contact with the target species and detecting the occurrence of or change in a nuclear magnetic resonance signal from each of the active-nuclei in each of the functionalized active-nucleus complexes.
International Nuclear Information System (INIS)
Blin-Stoyle, R.J.
1979-01-01
The nucleus is a complicated many-body structure whose properties when carefully studied can frequently give important information about the underlying elementary particle interactions. This article reviews progress in research of this kind over the last twenty-five years. (author)
International Nuclear Information System (INIS)
Afnan, I.R.
1977-04-01
The latest developments in the construction of pion-nucleus optical potential are presented and a comparison with the latest data on π+ 12 C is made. The suggested mechanisms for the (p,π) reaction are discussed with a comparison of the theoretical results with experiment. (Author)
Single nucleon emission in relativistic nucleus-nucleus reactions
International Nuclear Information System (INIS)
Anon.
1992-01-01
Significant discrepancies between theory and experiment have previously been noted for nucleon emission via electromagnetic processes in relativistic nucleus-nucleus collisions. The present work investigates the hypothesis that these discrepancies have arisen due to uncertainties about how to deduce the experimental electromagnetic cross section from the total measured cross section. An optical-model calculation of single neutron removal is added to electromagnetic cross sections and compared to the total experimental cross sections. Good agreement is found thereby resolving some of the earlier noted discrepancies. A detailed comparison to the recent work of Benesh, Cook, and Vary is made for both the impact parameter and the nuclear cross section. Good agreement is obtained giving an independent confirmation of the parameterized formulas developed by those authors
Transverse Energy in nucleus-nucleus collisions: A review
International Nuclear Information System (INIS)
Tincknell, M.
1988-01-01
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
Development of injectable hydrogels for nucleus pulposus replacement
Thomas, Jonathan D.
Intervertebral disc degeneration has been reported as the underlying cause for 75% of cases of lower back pain and is marked by dehydration of the nucleus pulposus within the intervertebral disc. There have been many implant designs to replace the nucleus pulposus. Some researchers have proposed the replacement of the nucleus pulposus with hydrogel materials. The insertion of devices made from these materials further compromises the annulus of the disc. An ideal nucleus replacement could be injected into the disc space and form a solid in vivo. However, injectable replacements using curing elastomers and thermoplastic materials are not ideal because of the potentially harmful exothermic heat evolved from their reactions and the toxicity of the reactants used. We propose a hydrogel system that can be injected as a liquid at 25°C and solidified to yield a hydrogel within the intervertebral disc at 37°C. In aqueous solutions, these polymers have Lower Critical Solution Temperatures (LCST) between 25-37°C, making them unique candidate materials for this application. Poly(N-isopropylacrylamide) (PNIPAAm) is the most widely studied LCST polymer due to its drastic transition near body temperature. However, by itself, pure PNIPAAm forms a hydrogel that has low water content and can readily undergo plastic deformation. To increase the water content and impart elasticity to PNIPAAm hydrogels, grafted and branched hydrogel systems were created that incorporated the thermogelling PNIPAAm and hydrophilic poly(ethylene glycol) (PEG). In this research, the effects of polymer composition and monomer to initiator ratio, which controls polymer MW, on the in vitro swelling properties (mass, chemical, and compressive mechanical stability) of hydrogels formed from aqueous solutions of these polymers were evaluated. Immersion studies were also conducted in solutions to simulate the osmotic environment of the nucleus pulposus. The effects of repeated compression and unloading cycles
International Nuclear Information System (INIS)
Chieux, P.; Damay, P.
1978-01-01
A quantitative comparison is made between the thermodynamics as obtained from the long wavelength limit of a small angle neutron scattering experiment in the vicinity of a liquid-liquid critical point for the Li-ND 3 system and the data obtained from vapour pressure measurements. The agreement is fair. It is shown how the comparison always implies an underlying model of the interacting species leading to the liquid-liquid phase separation. (Auth.)
Kaonic nuclei and kaon-nucleus interactions
Ikuta, K; Masutani, K
2002-01-01
Although kaonic atoms provide valuable information concerning the K sup - -nucleus interaction at low energies, they cannot fully determine the K sup - - nucleus optical potential. We demonstrate that K sup - nuclear bound states, if they exist, can be useful in investigating the K sup - -nucleus interaction, especially in the interior of the nucleus. In order to show this possibility, we calculate the double differential cross sections for (K sup - , P) using the Green function method. (author)
Color oscillations of nucleons in a nucleus
International Nuclear Information System (INIS)
Petrov, V.A.; Smirnov, A.Yu.
1987-01-01
Possibility of nucleus description as an object consisting of quarks and gluons is considered. A model of two-nucleon interaction in a nucleus is presented and analytical expressions for the nucleus nucleon ground state wave functions and also for nuclear nucleon structure functions are obtained. The carried out analysis shows that the suggested model permits to express the nucleus structure functions at quark level only by means of nucleon and Δ-isobaric degrees of freedom
Hummingbird Comet Nucleus Analysis Mission
Kojiro, Daniel; Carle, Glenn C.; Lasher, Larry E.
2000-01-01
Hummingbird is a highly focused scientific mission, proposed to NASA s Discovery Program, designed to address the highest priority questions in cometary science-that of the chemical composition of the cometary nucleus. After rendezvous with the comet, Hummingbird would first methodically image and map the comet, then collect and analyze dust, ice and gases from the cometary atmosphere to enrich characterization of the comet and support landing site selection. Then, like its namesake, Hummingbird would carefully descend to a pre-selected surface site obtaining a high-resolution image, gather a surface material sample, acquire surface temperature and then immediately return to orbit for detailed chemical and elemental analyses followed by a high resolution post-sampling image of the site. Hummingbird s analytical laboratory contains instrumentation for a comprehensive molecular and elemental analysis of the cometary nucleus as well as an innovative surface sample acquisition device.
Comet Halley: nucleus and jets
International Nuclear Information System (INIS)
Sagdeev, R.Z.; Avanesov, G.A.; Barinov, I.V.
1986-06-01
The VEGA-1 and VEGA-2 spacecrafts made their closest approach to Comet Halley on 6 and 9 March, respectively. In this paper results of the onboard imaging experiment are discussed. The nucleus of the comet was clearly identifyable as an irregularly shaped object with overall dimensions of (16+-1)x(8+-1)x(8+-1) km. The nucleus rotates around its axis which is nearly perpendicular to the orbital plane, with a period of 53+-2 hours. Its albedo is only 0.04+-002. Most of the jet features observed during the second fly-by were spatially reconstructed. These sources form a quasi-linear structure on the surface. The dust above the surface is shown to be optically thin except certain specific dust jets. Brightness features on the surface are clearly seen. Correlating the data with other measurements it is concluded that the dirty snow-ball model probably has to be revised. (author)
Lasers probe the atomic nucleus
International Nuclear Information System (INIS)
Eastham, D.
1986-01-01
The article is contained in a booklet on the Revised Nuffield Advanced Physics Course, and concentrates on two techniques to illustrate how lasers probe the atomic nucleus. Both techniques employ resonance fluorescence spectroscopy for obtaining atomic transition energies. The first uses lasers to determine the change in the nuclear charge radius with isotope, the second concerns the use of lasers for ultrasensitive detection of isotopes and elements. The application of lasers in resonance ionization spectroscopy and proton decay is also described. (UK)
International Nuclear Information System (INIS)
Lyttleton, R.A.
1977-01-01
Descriptions of actual observed comets associate a range of ill-defined meanings with the term nucleus. In recent years use of the word has been even further extended (or contracted) to mean a postulated solid core constituting the permanent element of a comet and necessarily of size far below resolution and measurability. It is maintained by the postulants that this core, acted upon by solar radiation and the solar wind, is the fount and origin of practically the whole great variety of observed cometary physical phenomena. In order that this micro-nucleus shall 'explain' observed properties, it is endowed with a large number of entirely ad-hoc qualities specially devised to produce the very effects it is wished to explain, but the processes so proffered rely almost entirely on purely verbal asseverations that they will work in the way required. No source or mechanism of origin for the imaginary micro-nucleus, of which there would need to be myriads, is in sight, nor can the assumption explain the dynamical properties of long-period comets and their association with the galactic plane and the solar apex. The postulate is in any event ruled out by Occam's principle as having no basis in fact or theory and is not required to explain the observed properties of comets. The large number of additional special assumptions introduced mean that the structure as a whole does not constitute a proper scientific theory. (author)
Angular momentum and incident-energy dependence of nucleus-nucleus interaction
International Nuclear Information System (INIS)
Yamaguchi, S.
1991-01-01
The purpose of this paper is to understand intuitively the origin of the angular momentum and incident-energy dependence of the nucleus-nucleus interaction on the basis of the totally- antisymmetrized many-body theory. With the aim of understanding the structure of the nucleus-nucleus interaction, we show first that the nucleus-nucleus interaction can be written by the use of the density-distribution function and the phase-space distribution function instead of using the many-body wave function itself. And we show that the structure change of the density-distribution function with the increase of the angular momentum causes the angular momentum dependence of the nucleus-nucleus interaction and that the incident-energy dependence of the nucleus-nucleus interaction originates from the structure change of the phase-space distribution function
Classifiers for centrality determination in proton-nucleus and nucleus-nucleus collisions
Directory of Open Access Journals (Sweden)
Altsybeev Igor
2017-01-01
Full Text Available 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 experiment NA61/SHINE on SPS.
Energy Technology Data Exchange (ETDEWEB)
Moreira, B. D.; Goncalves, V. P.; De Santana Amaral, J. T. [Universidade Federal de Pelotas, Instituto de Fisica e Matematica (Brazil)
2013-03-25
In this contribution we study coherent interactions as a probe of the nonlinear effects in the Quantum Electrodynamics (QED). In particular, we study the multiphoton effects in the production of leptons pairs for proton-nucleus and nucleus-nucleus collisions for heavy nuclei. In the proton-nucleus we assume the ultrarelativistic proton as a source of photons and estimate the photoproduction of lepton pairs on nuclei at RHIC and LHC energies considering the multiphoton effects associated to multiple rescattering of the projectile photon on the proton of the nucleus. In nucleus - nucleus colllisions we consider the two nuclei as a source of photons. As each scattering contributes with a factor {alpha}Z to the cross section, this contribution must be taken into account for heavy nuclei. We consider the Coulomb corrections to calculate themultiple scatterings and estimate the total cross section for muon and tau pair production in proton-nucleus and nucleus-nucleus collisions at RHIC and LHC energies.
Relativistic nucleus-nucleus collisions: from the BEVALAC to RHIC
International Nuclear Information System (INIS)
Stock, Reinhard
2004-01-01
I briefly describe the initial goals of relativistic nuclear collision research, focusing on the LBL Bevatron/Bevalac facility in the 1970s. An early concept of high hadronic density fireball formation, and subsequent isentropic decay (preserving information of the high-density stage), led to an outline of physics observables that could determine the nuclear matter equation of state at several times the nuclear ground state matter density. With the advent of QCD the goal of locating and characterizing the hadron-parton deconfinement phase transformation suggested the need for higher √s, the research thus shifting to the BNL AGS and CERN SPS, and finally to RHIC at BNL. A set of physics observables is discussed where present data span the entire √s domain, from Bevalac and SIS at GSI, to high RHIC energy. Referring, selectively, to data concerning bulk hadron production, the overall √s evolution of directed and radial flow observables, and of pion pair Bose-Einstein correlation is discussed. The hadronization process is studied in the grand canonical statistical model. The resulting hadronization points in the plane T versus μ B converge onto the parton-hadron phase boundary predicted by finite μ B lattice QCD, from high SPS to RHIC energy. At lower SPS and high AGS energy a steep strangeness maximum occurs at which the Wroblewski parameter λ s ∼ 0.6; a possible connection to the QCD critical point is discussed. Finally the unique new RHIC physics is addressed: high-p T hadron suppression and jet 'tomography'
Strangeness production in nucleus-nucleus collisions: An experimental review
International Nuclear Information System (INIS)
Odyniec, G.
1990-12-01
In experiments with oxygen (60 and 200 GeV/N) and sulphur (200 GeV/N) ions at CERNSPS, large energy densities of the order of 2--3 GeV/fm 3 have been observed, which according to QCD calculations, satisfy necessary conditions for the formation of a quark gluon plasma (QGP) phase. Under such conditions, colour would no longer be confined to hadronic dimensions, and quarks and gluons will propagate freely throughout an extended volume. Somehow lower energy densities, of the order of 0.7--1 GeV/fm 3 , were observed in AGS experiments with 15 GeV/N silicon beams and heavy targets. These energy densities might be adequate for investigations of the pre-equilibrium stage, during which the momentum space distribution has been degradated from its initial value but is not yet thermal. First experimental results, available now, show promise of seeing signs of a new phase of matter. In this review the current status of the selective experimental results on strange-particle production, which are relevant to equilibration and QGP formation in nucleus-nucleus collisions, is presented
Applying the elastic model for various nucleus-nucleus fusion
International Nuclear Information System (INIS)
HASSAN, G.S.; RAGAB, H.S.; SEDDEEK, M.K.
2000-01-01
The Elastic Model of two free parameters m,d given by Scalia has been used for wider energy regions to fit the available experimental data for potential barriers and cross sections. In order to generalize Scalia's formula in both sub- and above-barrier regions, we calculated m, d for pairs rather than those given by Scalia and compared the calculated cross sections with the experimental data. This makes a generalization of the Elastic Model in describing fusion process. On the other hand, Scalia's range of interacting systems was 24 ≤ A ≤194 where A is the compound nucleus mass number. Our extension of that model includes an example of the pairs of A larger than his final limit aiming to make it as a general formula for any type of reactants: light, intermediate or heavy systems. A significant point is the comparison of Elastic Model calculations with the well known methods studying complete fusion and compound nucleus formation, namely with the resultants of using Proximity potential with either Sharp or Smooth cut-off approximations
International Nuclear Information System (INIS)
Turner, M.S.
1989-01-01
One of the simplest, yet most profound, questions we can ask about the Universe is, how much stuff is in it, and further what is that stuff composed of? Needless to say, the answer to this question has very important implications for the evolution of the Universe, determining both the ultimate fate and the course of structure formation. Remarkably, at this late date in the history of the Universe we still do not have a definitive answer to this simplest of questions---although we have some very intriguing clues. It is known with certainty that most of the material in the Universe is dark, and we have the strong suspicion that the dominant component of material in the Cosmos is not baryons, but rather is exotic relic elementary particles left over from the earliest, very hot epoch of the Universe. If true, the Dark Matter question is a most fundamental one facing both particle physics and cosmology. The leading particle dark matter candidates are: the axion, the neutralino, and a light neutrino species. All three candidates are accessible to experimental tests, and experiments are now in progress. In addition, there are several dark horse, long shot, candidates, including the superheavy magnetic monopole and soliton stars. 13 refs
Quarkonia Photoproduction at Nucleus Colliders
International Nuclear Information System (INIS)
D'Enterria, David
2008-01-01
Exclusive photoproduction of heavy quarkonia in high-energy ultraperipheral ion-ion interactions (γ A →V A, where V = J/ψ, Y and the nucleus A remains intact) offers a useful means to constrain the small-x nuclear gluon density. We discuss preliminary results on J/ψ photoproduction in Au-Au collisions at RHIC [D. d'Enterria [PHENIX Collaboration], Proceeds. Quark Matter'05, (arXiv:nucl-ex/0601001)], as well as full simulation-reconstruction studies of photo-produced Y in Pb-Pb interactions at the LHC [D. d'Enterria (ed.) et al. [CMS Collaboration], J. Phys. G. 34 2307 (2007)
International Nuclear Information System (INIS)
Besliu, Calin; Jipa, Alexandru; Iliescu, Bogdan; Felea, Daniel
2002-01-01
Some new aspects on the multifragmentation processes in nucleus-nucleus and nucleon-nucleus collisions at high energies are discussed in this work. Experimental data obtained in international collaborations (for example, MULTI Collaboration with KEK Tsukuba (Japan) and SKM 200 Collaboration with JINR Dubna (Russia)) are used to discuss new mechanisms in the target nucleus fragmentation. Correlations with stopping power, participant region size and energy density are included. Comparisons of the experimental results with the predictions of a phenomenological geometric model of intermediate mass fragment multiplicity, caloric curves and angular distributions are also presented. These results are used for global description of the multifragmentation processes in nucleon-nucleus and nucleus-nucleus collisions at relativistic energies. The size of the participant region and the average intermediate mass fragments multiplicity are taken into consideration using the free space probability. A few correlations between the deposited energy in the participant region and stability state of the intermediate mass fragments are presented in this work. The importance of the collision geometry in the multifragmentation processes is stressed. The results suggest different time moments for the incident nucleus fragmentation and for the target nucleus fragmentation. The associated entropies are distinct. (authors)
Notochord to Nucleus Pulposus Transition.
Lawson, Lisa; Harfe, Brian D
2015-10-01
A tissue that commonly deteriorates in older vertebrates is the intervertebral disc, which is located between the vertebrae. Age-related changes in the intervertebral discs are thought to cause most cases of back pain. Back pain affects more than half of people over the age of 65, and the treatment of back pain costs 50-100 billion dollars per year in the USA. The normal intervertebral disc is composed of three distinct regions: a thick outer ring of fibrous cartilage called the annulus fibrosus, a gel-like material that is surrounded by the annulus fibrosus called the nucleus pulposus, and superior and inferior cartilaginous end plates. The nucleus pulposus has been shown to be critical for disc health and function. Damage to this structure often leads to disc disease. Recent reports have demonstrated that the embryonic notochord, a rod-like structure present in the midline of vertebrate embryos, gives rise to all cell types found in adult nuclei pulposi. The mechanism responsible for the transformation of the notochord into nuclei pulposi is unknown. In this review, we discuss potential molecular and physical mechanisms that may be responsible for the notochord to nuclei pulposi transition.
Molecular orbitals of nucleons in nucleus-nucleus collisions
International Nuclear Information System (INIS)
Imanishi, B.; Oertzen, W. von.
1986-05-01
A formalism for the dynamical treatment of the molecular orbitals of valence nucleons in nucleus-nucleus collisions at low bombarding energy is developed with the use of the coupled-reaction-channel (CRC) method. The Coriolis coupling effects as well as the finite mass effects of the nucleon are taken into account in this model, of rotating molecular orbitals, RMO. First, the validity of the concept is examined from the view point of the multi-step processes in a standard CRC calculation for systems containing two identical [core] nuclei. The calculations show strong CRC effects particularly in the case where the mixing of different l-parity orbitals - called hybridization in atomic physics - occurs. Then, the RMO representation for active nucleons is applied to the same systems and compared to the CRC results. Its validity is investigated with respect to the radial motion (adiabaticity) and the rotation of the molecular axis (radial and rotational coupling). Characteristic molecular orbitals of covalent molecules appear as rotationally stable states (K = 1/2) with good adiabaticity. Using the RMO's we obtain a new interpretation of various scattering phenomena. Dynamically induced changes in the effective Q-values (or scaling of energies), dynamically induced moments of inertia and an dynamically induced effective (L · S) interaction are obtained as a result of the molecular orbital formation. Various experimental data on transfer and subbarrier fusion reactions are understood in terms of the RMO's and their adiabatic potentials. Landau-Zener transitions, which strongly depend on the total angular momentum of the system, definitely predict the observation of characteristic changes in the cross sections for the inelastic scattering 13 C( 12 C, 12 C) 13 C* (3.086 MeV, 1/2 + ) with the change of the bombarding energy. (author)
Double folding model of nucleus-nucleus potential: formulae, iteration method and computer code
International Nuclear Information System (INIS)
Luk'yanov, K.V.
2008-01-01
Method of construction of the nucleus-nucleus double folding potential is described. Iteration procedure for the corresponding integral equation is presented. Computer code and numerical results are presented
International Nuclear Information System (INIS)
Ngo, H.
1984-01-01
Several models, performed within a mean field theory, are developed for the calculation of nucleon-nucleus interaction potentials. The first part of the thesis deals with the nucleon-nucleus average interaction. It is mainly devoted to the calculation of dynamical corrections to the Hartree-Fock approximation. Two approaches are used: a microscopic model performed in the framework of the nuclear structure approach and a semi-phenomenological one, based on the application of the dispersion relations to the empirical imaginary potential. Both models take into account finite size effects like collectivity or threshold effects which are important at low energy. The Green's function properties are used for both models. The second part of this work is devoted to the interaction potential between two heavy ions. This calculation, which is performed in the framework of the sudden approximation, uses the energy density formalism (Thomas-Fermi approximation). It has been extended to finite temperature. At T=0 the experimental fusion barriers of heavy systems are reproduced within 4%. Their temperature dependence is studied. The proximity scaling is checked and a universal function is obtained at T=0 and at finite temperature. It is found that the proximity theorem is well satisfied on the average. The dispersion around the mean behaviour increases with increasing temperature. At last, P+A* and α+A* interaction potentials are calculated within a double folding model using a schematic effective interaction [fr
Optimized candidal biofilm microtiter assay
Krom, Bastiaan P.; Cohen, Jesse B.; Feser, Gail E. McElhaney; Cihlar, Ronald L.
Microtiter based candidal biofilm formation is commonly being used. Here we describe the analysis of factors influencing the development of candidal biofilms such as the coating with serum, growth medium and pH. The data reported here show that optimal candidal biofilm formation is obtained when
International Nuclear Information System (INIS)
Strugalski, Z.
1995-01-01
A physical meaning of the outcomes from hadronic and nuclear collision processes at high energies is presented, as prompted experimentally. The fast and slow stages in hadron-nucleus collisions are distinguished. Hadrons are produced via intermediate objects observed in hadron-nucleus collisions. The intermediate objects may be treated as the groups of quarks or the quark bags. 37 refs
Description of inelastic nucleus-nucleus interactions at medium energy using dual parton model
International Nuclear Information System (INIS)
Polanski, A.; Shmakov, S.Yu.; Uzhinskij, V.V.
1989-01-01
It is shown that the dual parton model taking into account the processes of diffraction dissociation to the low mass states and finite energy corrections to the asymptotic Abramovski-Gribov-Kancheli cutting rules allows satisfactory description of existing experimental data on hadron-nucleus and nucleus-nucleus interactions at medium energy. (orig.)
Do migrating cells need a nucleus?
Hawkins, Rhoda J
2018-03-05
How the nucleus affects cell polarity and migration is unclear. In this issue, Graham et al. (2018. J. Cell Biol. https://doi.org/10.1083/jcb.201706097) show that enucleated cells polarize and migrate in two but not three dimensions and propose that the nucleus is a necessary component of the molecular clutch regulating normal mechanical responses. © 2018 Hawkins.
Serotonin projection patterns to the cochlear nucleus.
Thompson, A M; Thompson, G C
2001-07-13
The cochlear nucleus is well known as an obligatory relay center for primary auditory nerve fibers. Perhaps not so well known is the neural input to the cochlear nucleus from cells containing serotonin that reside near the midline in the midbrain raphe region. Although the specific locations of the main, if not sole, sources of serotonin within the dorsal cochlear nucleus subdivision are known to be the dorsal and median raphe nuclei, sources of serotonin located within other cochlear nucleus subdivisions are not currently known. Anterograde tract tracing was used to label fibers originating from the dorsal and median raphe nuclei while fluorescence immunohistochemistry was used to simultaneously label specific serotonin fibers in cat. Biotinylated dextran amine was injected into the dorsal and median raphe nuclei and was visualized with Texas Red, while serotonin was visualized with fluorescein. Thus, double-labeled fibers were unequivocally identified as serotoninergic and originating from one of the labeled neurons within the dorsal and median raphe nuclei. Double-labeled fiber segments, typically of fine caliber with oval varicosities, were observed in many areas of the cochlear nucleus. They were found in the molecular layer of the dorsal cochlear nucleus, in the small cell cap region, and in the granule cell and external regions of the cochlear nuclei, bilaterally, of all cats. However, the density of these double-labeled fiber segments varied considerably depending upon the exact region in which they were found. Fiber segments were most dense in the dorsal cochlear nucleus (especially in the molecular layer) and the large spherical cell area of the anteroventral cochlear nucleus; they were moderately dense in the small cell cap region; and fiber segments were least dense in the octopus and multipolar cell regions of the posteroventral cochlear nucleus. Because of the presence of labeled fiber segments in subdivisions of the cochlear nucleus other than the
Actomyosin contractility rotates the cell nucleus.
Kumar, Abhishek; Maitra, Ananyo; Sumit, Madhuresh; Ramaswamy, Sriram; Shivashankar, G V
2014-01-21
The cell nucleus functions amidst active cytoskeletal filaments, but its response to their contractile stresses is largely unexplored. We study the dynamics of the nuclei of single fibroblasts, with cell migration suppressed by plating onto micro-fabricated patterns. We find the nucleus undergoes noisy but coherent rotational motion. We account for this observation through a hydrodynamic approach, treating the nucleus as a highly viscous inclusion residing in a less viscous fluid of orientable filaments endowed with active stresses. Lowering actin contractility selectively by introducing blebbistatin at low concentrations drastically reduced the speed and coherence of the angular motion of the nucleus. Time-lapse imaging of actin revealed a correlated hydrodynamic flow around the nucleus, with profile and magnitude consistent with the results of our theoretical approach. Coherent intracellular flows and consequent nuclear rotation thus appear to be an intrinsic property of cells.
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.
Percolation systems away from the critical point
Indian Academy of Sciences (India)
DEEPAK DHAR. Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India ... There is more to percolation theory than the critical exponents. Of course, an experi- .... simple qualitative arguments. In the summation ...
Percolation Systems away from the Critical Point
Dhar, Deepak
2001-01-01
This article reviews some effects of disorder in percolation systems even away from the critical density p_c. For densities below p_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 singuraties in the free energy of diluted ferromagnets, and lead to a very slow relaxation of magnetization. In biassed diffusion on percolation clusters,...
QCD critical point: The race is on
Indian Academy of Sciences (India)
2015-05-06
May 6, 2015 ... The aim of this article is to describe how things are different for strongly ... flavours) and one moderately heavier (strange) quark. ... an order parameter on a lattice, the chiral symmetry must be respected even on the lattice.
International Nuclear Information System (INIS)
Chirilli, Giovanni A.; Kovchegov, Yuri V.; Wertepny, Douglas E.
2015-01-01
We calculate the classical single-gluon production amplitude in nucleus-nucleus collisions including the first saturation correction in one of the nuclei (the projectile) while keeping multiple-rescattering (saturation) corrections to all orders in the other nucleus (the target). In our approximation only two nucleons interact in the projectile nucleus: the single-gluon production amplitude we calculate is order-g"3 and is leading-order in the atomic number of the projectile, while resumming all order-one saturation corrections in the target nucleus. Our result is the first step towards obtaining an analytic expression for the first projectile saturation correction to the gluon production cross section in nucleus-nucleus collisions.
International Nuclear Information System (INIS)
Moehring, H.; Ranft, J.; Capella, A.; Tran Thanh Van, J.
1993-01-01
Λ, bar Λ, and K S 0 production is studied in a Monte Carlo dual parton model for hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions with an SU(3) symmetric sea for chain formation (chain ends) but strangeness suppression in the chain fragmentation process. Additionally, (qq)-(bar q bar q) production from the sea was introduced into the chain formation process with the same probability as for the q→qq branching within the chain decay process. With these assumptions, multiplicity ratios and Feynman-x distributions for strange particles in h-h and multiplicity ratios in heavy ion collisions are reasonably well reproduced
International Nuclear Information System (INIS)
Kooner, Z.S.; Van Hook, W.A.
1986-01-01
An apparatus designed to measure vapor pressure differences between two similar liquids, such as isotopic isomers, or between a solution and its reference solvent at temperatures and pressures extending to the critical point is described. Vapor-phase volume is minimized and pressure is transmitted to the transducer through the liquid, thereby avoiding several experimental difficulties. Liquid can be injected into the heated part of the system by volumetrically calibrated screw injectors, thus permitting measurements of liquid molar volume, compressibility, and expansivity. The addition of a high-pressure circulating pump and injection valve allows the apparatus to be employed as a continuous dilution differential vapor pressure apparatus for determining partial molar free energies of solution. In the second part of the paper data on the vapor pressure, molar volume, compressibility, and expansivity and their isotope effects for C 6 H 6 and C 6 D 6 from room temperature to near the critical temperature are reported
Laser spectroscopy probes the nucleus
International Nuclear Information System (INIS)
Griffith, J.; Billowes, J.
1998-01-01
Extremely sensitive optical measurements are shedding new light on the shape and size of nuclei, and the properties of nuclear matter far from stability. Of the 7000 or so isotopes known to nuclear physicists, less than 270 are stable. In general isotopes become more and more unstable as we move away from the so-called valley of stability, and therefore become more difficult to study in experiments. The tests of the theory also become more demanding. Laser spectroscopy is one of the techniques that is helping to explore the properties of these isotopes and improve our understanding of the forces inside the nucleus. High-resolution laser spectroscopy of short-lived radioactive atoms now makes it possible to measure the nuclear charge radius of many elements, including many isotopes far from stability. The method can reveal fine details of the sizes, shapes and structures of nuclei. In addition, laser spectroscopy is making significant contributions to our understanding of the nuclear force in unstable nuclei with unusual, or extreme, proton-neutron ratios. In this article the authors discuss the latest advances in studying heavy nuclei. (author)
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.
Energy Technology Data Exchange (ETDEWEB)
Ni, Yicun; Skinner, J. L. [Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)
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.
Directory of Open Access Journals (Sweden)
Ceile Cristina Ferreira Nunes
2004-04-01
ítico calculada usando-se a expressão que leva em consideração a covariância entre e apresenta resultados mais satisfatórios e que não segue uma distribuição normal, pois apresenta uma distribuição de freqüência com assimetria positiva e formato leptocúrtico.The aim of this paper is determine variances for the analysis of the critical point of a second-degree regression equation in experimental situations with different variances through Monte Carlo simulation. In many theoretical or applied studies, one finds situations involving ratios of random variables and more frequently normal variables. Examples are provided by variables, which appear in economic dose research of nutrients in fertilization experiments, as well as in other problems in which there are interests in the random variable, estimator of the critic point in the regression . Data of five hundred thirty six trials in cotton yield were utilized to study the distribution of the critical point of a quadratic regression equation by adjusting a quadratic model. The parameters were evaluated using a least square method. From the estimations a MATLAB routine was implemented to simulate two sets with five thousands random errors with normal distribution and zero mean, relative to each of the theoretical variances: or = 0.1; 0.5; 1; 5; 10; 15; 20 and 50. The estimation of the variance of the critical point was obtained by three methods: (a usual formula for the variance; (b formula obtained by differentiation of the critical point estimator and (c formula for the computation of the variance of a quotient by taking into consideration the covariance between and . The results obtained for the statistic average for the regression between e , as well as its respective variances in terms of the several theoretical residual variances ( adopted show that those theoretical values are close to real ones. Moreover, there is a trend of increasing and with increase of the theoretical variance. It may
Observation of Top Quark Production in Proton-Nucleus Collisions
Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Escalante Del Valle, A.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Grossmann, J.; Hrubec, J.; Jeitler, M.; König, A.; Krammer, N.; Krätschmer, I.; Liko, D.; Madlener, T.; Mikulec, I.; Pree, E.; Rad, N.; Rohringer, H.; Schieck, J.; Schöfbeck, R.; Spanring, M.; Spitzbart, D.; Waltenberger, W.; Wittmann, J.; Wulz, C.-E.; Zarucki, M.; Chekhovsky, V.; Mossolov, V.; Suarez Gonzalez, J.; De Wolf, E. A.; Di Croce, D.; Janssen, X.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; De Bruyn, I.; De Clercq, J.; Deroover, K.; Flouris, G.; Lontkovskyi, D.; Lowette, S.; Marchesini, I.; Moortgat, S.; Moreels, L.; Python, Q.; Skovpen, K.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Beghin, D.; Bilin, B.; Brun, H.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Dorney, B.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Kalsi, A. K.; Lenzi, T.; Luetic, J.; Maerschalk, T.; Marinov, A.; Seva, T.; Starling, E.; Vander Velde, C.; Vanlaer, P.; Vannerom, D.; Yonamine, R.; Zenoni, F.; Cornelis, T.; Dobur, D.; Fagot, A.; Gul, M.; Khvastunov, I.; Poyraz, D.; Roskas, C.; Salva, S.; Tytgat, M.; Verbeke, W.; Zaganidis, N.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caputo, C.; Caudron, A.; David, P.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Saggio, A.; Vidal Marono, M.; Wertz, S.; Zobec, J.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Correa Martins Junior, M.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Coelho, E.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; Fonseca De Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Melo De Almeida, M.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Sanchez Rosas, L. J.; Santoro, A.; Sznajder, A.; Thiel, M.; Tonelli Manganote, E. J.; Torres Da Silva De Araujo, F.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Tomei, T. R. Fernandez Perez; Gregores, E. M.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Misheva, M.; Rodozov, M.; Shopova, M.; Sultanov, G.; Dimitrov, A.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Gao, X.; Yuan, L.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Jiang, C. H.; Leggat, D.; Liao, H.; Liu, Z.; Romeo, F.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Yazgan, E.; Zhang, H.; Zhang, S.; Zhao, J.; Ban, Y.; Chen, G.; Li, J.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Zhang, F.; Wang, Y.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Segura Delgado, M. A.; Courbon, B.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Sculac, T.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Mesic, B.; Starodumov, A.; Susa, T.; Ather, M. W.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Finger, M.; Finger, M.; Carrera Jarrin, E.; Assran, Y.; Elgammal, S.; Mahrous, A.; Dewanjee, R. K.; Kadastik, M.; Perrini, L.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Kirschenmann, H.; Pekkanen, J.; Voutilainen, M.; Havukainen, J.; Heikkilä, J. K.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Laurila, S.; Lehti, S.; Lindén, T.; Luukka, P.; Siikonen, H.; Tuominen, E.; Tuominiemi, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Faure, J. L.; Ferri, F.; Ganjour, S.; Ghosh, S.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Kucher, I.; Leloup, C.; Locci, E.; Machet, M.; Malcles, J.; Negro, G.; Rander, J.; Rosowsky, A.; Sahin, M. Ö.; Titov, M.; Abdulsalam, A.; Amendola, C.; Antropov, I.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Charlot, C.; Granier de Cassagnac, R.; Jo, M.; Lisniak, S.; Lobanov, A.; Martin Blanco, J.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Pigard, P.; Salerno, R.; Sauvan, J. B.; Sirois, Y.; Stahl Leiton, A. G.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Zghiche, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Jansová, M.; Le Bihan, A.-C.; Tonon, N.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fay, J.; Finco, L.; Gascon, S.; Gouzevitch, M.; Grenier, G.; Ille, B.; Lagarde, F.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Popov, A.; Sordini, V.; Vander Donckt, M.; Viret, S.; Toriashvili, T.; Bagaturia, I.; Autermann, C.; Feld, L.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Preuten, M.; Schomakers, C.; Schulz, J.; Teroerde, M.; Zhukov, V.; Albert, A.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hamer, M.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Teyssier, D.; Thüer, S.; Flügge, G.; Kargoll, B.; Kress, T.; Künsken, A.; Müller, T.; Nehrkorn, A.; Nowack, A.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Arndt, T.; Asawatangtrakuldee, C.; Beernaert, K.; Behnke, O.; Behrens, U.; Bermúdez Martínez, A.; Bin Anuar, A. A.; Borras, K.; Botta, V.; Campbell, A.; Connor, P.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Eren, E.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Grados Luyando, J. M.; Grohsjean, A.; Gunnellini, P.; Guthoff, M.; Harb, A.; Hauk, J.; Hempel, M.; Jung, H.; Kasemann, M.; Keaveney, J.; Kleinwort, C.; Korol, I.; Krücker, D.; Lange, W.; Lelek, A.; Lenz, T.; Leonard, J.; Lipka, K.; Lohmann, W.; Mankel, R.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Ntomari, E.; Pitzl, D.; Raspereza, A.; Savitskyi, M.; Saxena, P.; Shevchenko, R.; Stefaniuk, N.; Van Onsem, G. P.; Walsh, R.; Wen, Y.; Wichmann, K.; Wissing, C.; Zenaiev, O.; Aggleton, R.; Bein, S.; Blobel, V.; Centis Vignali, M.; Dreyer, T.; Garutti, E.; Gonzalez, D.; Haller, J.; Hinzmann, A.; Hoffmann, M.; Karavdina, A.; Klanner, R.; Kogler, R.; Kovalchuk, N.; Kurz, S.; Lapsien, T.; Marconi, D.; Meyer, M.; Niedziela, M.; Nowatschin, D.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Scharf, C.; Schleper, P.; Schmidt, A.; Schumann, S.; Schwandt, J.; Sonneveld, J.; Stadie, H.; Steinbrück, G.; Stober, F. M.; Stöver, M.; Tholen, H.; Troendle, D.; Usai, E.; Vanhoefer, A.; Vormwald, B.; Akbiyik, M.; Barth, C.; Baselga, M.; Baur, S.; Butz, E.; Caspart, R.; Chwalek, T.; Colombo, F.; De Boer, W.; Dierlamm, A.; Faltermann, N.; Freund, B.; Friese, R.; Giffels, M.; Harrendorf, M. A.; Hartmann, F.; Heindl, S. M.; Husemann, U.; Kassel, F.; Kudella, S.; Mildner, H.; Mozer, M. U.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Schröder, M.; Shvetsov, I.; Sieber, G.; Simonis, H. J.; Ulrich, R.; Wayand, S.; Weber, M.; Weiler, T.; Williamson, S.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Kyriakis, A.; Loukas, D.; Topsis-Giotis, I.; Karathanasis, G.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Kousouris, K.; Evangelou, I.; Foudas, C.; Gianneios, P.; Katsoulis, P.; Kokkas, P.; Mallios, S.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Strologas, J.; Triantis, F. A.; Tsitsonis, D.; Csanad, M.; Filipovic, N.; Pasztor, G.; Surányi, O.; Veres, G. I.; Bencze, G.; Hajdu, C.; Horvath, D.; Hunyadi, Á.; Sikler, F.; Veszpremi, V.; Beni, N.; Czellar, S.; Karancsi, J.; Makovec, A.; Molnar, J.; Szillasi, Z.; Bartók, M.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Choudhury, S.; Komaragiri, J. R.; Bahinipati, S.; Bhowmik, S.; Mal, P.; Mandal, K.; Nayak, A.; Sahoo, D. K.; Sahoo, N.; Swain, S. K.; Bansal, S.; Beri, S. B.; Bhatnagar, V.; Chawla, R.; Dhingra, N.; Kaur, A.; Kaur, M.; Kaur, S.; Kumar, R.; Kumari, P.; Mehta, A.; Singh, J. B.; Walia, G.; Kumar, Ashok; Shah, Aashaq; Bhardwaj, A.; Chauhan, S.; Choudhary, B. C.; Garg, R. B.; Keshri, S.; Kumar, A.; Malhotra, S.; Naimuddin, M.; Ranjan, K.; Sharma, R.; Bhardwaj, R.; Bhattacharya, R.; Bhattacharya, S.; Bhawandeep, U.; Dey, S.; Dutt, S.; Dutta, S.; Ghosh, S.; Majumdar, N.; Modak, A.; Mondal, K.; Mukhopadhyay, S.; Nandan, S.; Purohit, A.; Roy, A.; Roy Chowdhury, S.; Sarkar, S.; Sharan, M.; Thakur, S.; Behera, P. K.; Chudasama, R.; Dutta, D.; Jha, V.; Kumar, V.; Mohanty, A. K.; Netrakanti, P. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Dugad, S.; Mahakud, B.; Mitra, S.; Mohanty, G. B.; Sur, N.; Sutar, B.; Banerjee, S.; Bhattacharya, S.; Chatterjee, S.; Das, P.; Guchait, M.; Jain, Sa.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Sarkar, T.; Wickramage, N.; Chauhan, S.; Dube, S.; Hegde, V.; Kapoor, A.; Kothekar, K.; Pandey, S.; Rane, A.; Sharma, S.; Chenarani, S.; Eskandari Tadavani, E.; Etesami, S. M.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Rezaei Hosseinabadi, F.; Safarzadeh, B.; Zeinali, M.; Felcini, M.; Grunewald, M.; Abbrescia, M.; Calabria, C.; Colaleo, A.; Creanza, D.; Cristella, L.; De Filippis, N.; De Palma, M.; Errico, F.; Fiore, L.; Iaselli, G.; Lezki, S.; Maggi, G.; Maggi, M.; Miniello, G.; My, S.; Nuzzo, S.; Pompili, A.; Pugliese, G.; Radogna, R.; Ranieri, A.; Selvaggi, G.; Sharma, A.; Silvestris, L.; Venditti, R.; Verwilligen, P.; Abbiendi, G.; Battilana, C.; Bonacorsi, D.; Borgonovi, L.; Braibant-Giacomelli, S.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Chhibra, S. S.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Montanari, A.; Navarria, F. L.; Perrotta, A.; Rossi, A. M.; Rovelli, T.; Siroli, G. P.; Tosi, N.; Albergo, S.; Costa, S.; Di Mattia, A.; Giordano, F.; Potenza, R.; Tricomi, A.; Tuve, C.; Barbagli, G.; Chatterjee, K.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Lenzi, P.; Meschini, M.; Paoletti, S.; Russo, L.; Sguazzoni, G.; Strom, D.; Viliani, L.; Benussi, L.; Bianco, S.; Fabbri, F.; Piccolo, D.; Primavera, F.; Calvelli, V.; Ferro, F.; Ravera, F.; Robutti, E.; Tosi, S.; Benaglia, A.; Beschi, A.; Brianza, L.; Brivio, F.; Ciriolo, V.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Ghezzi, A.; Govoni, P.; Malberti, M.; Malvezzi, S.; Manzoni, R. A.; Menasce, D.; Moroni, L.; Paganoni, M.; Pauwels, K.; Pedrini, D.; Pigazzini, S.; Ragazzi, S.; Tabarelli de Fatis, T.; Buontempo, S.; Cavallo, N.; Di Guida, S.; Fabozzi, F.; Fienga, F.; Iorio, A. O. M.; Khan, W. A.; Lista, L.; Meola, S.; Paolucci, P.; Sciacca, C.; Thyssen, F.; Azzi, P.; Bacchetta, N.; Benato, L.; Bisello, D.; Boletti, A.; Carlin, R.; Carvalho Antunes De Oliveira, A.; Checchia, P.; De Castro Manzano, P.; Dorigo, T.; Dosselli, U.; Gasparini, F.; Gasparini, U.; Gozzelino, A.; Lacaprara, S.; Margoni, M.; Meneguzzo, A. T.; Pozzobon, N.; Ronchese, P.; Rossin, R.; Simonetto, F.; Torassa, E.; Zanetti, M.; Zotto, P.; Zumerle, G.; Braghieri, A.; Magnani, A.; Montagna, P.; Ratti, S. P.; Re, V.; Ressegotti, M.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Alunni Solestizi, L.; Biasini, M.; Bilei, G. M.; Cecchi, C.; Ciangottini, D.; Fanò, L.; Leonardi, R.; Manoni, E.; Mantovani, G.; Mariani, V.; Menichelli, M.; Rossi, A.; Santocchia, A.; Spiga, D.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Boccali, T.; Borrello, L.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Fedi, G.; Giannini, L.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Manca, E.; Mandorli, G.; Messineo, A.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Barone, L.; Cavallari, F.; Cipriani, M.; Daci, N.; Del Re, D.; Di Marco, E.; Diemoz, M.; Gelli, S.; Longo, E.; Margaroli, F.; Marzocchi, B.; Meridiani, P.; Organtini, G.; Paramatti, R.; Preiato, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bartosik, N.; Bellan, R.; Biino, C.; Cartiglia, N.; Cenna, F.; Costa, M.; Covarelli, R.; Degano, A.; Demaria, N.; Kiani, B.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Monteil, E.; Monteno, M.; Obertino, M. M.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. L.; Romero, A.; Ruspa, M.; Sacchi, R.; Shchelina, K.; Sola, V.; Solano, A.; Staiano, A.; Traczyk, P.; Belforte, S.; Casarsa, M.; Cossutti, F.; Della Ricca, G.; Zanetti, A.; Kim, D. H.; Kim, G. N.; Kim, M. S.; Lee, J.; Lee, S.; Lee, S. 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A.; Uribe Estrada, C.; Morelos Pineda, A.; Krofcheck, D.; Butler, P. H.; Ahmad, A.; Ahmad, M.; Hassan, Q.; Hoorani, H. R.; Saddique, A.; Shah, M. A.; Shoaib, M.; Waqas, M.; Bialkowska, H.; Bluj, M.; Boimska, B.; Frueboes, T.; Górski, M.; Kazana, M.; Nawrocki, K.; Szleper, M.; Zalewski, P.; Bunkowski, K.; Byszuk, A.; Doroba, K.; Kalinowski, A.; Konecki, M.; Krolikowski, J.; Misiura, M.; Olszewski, M.; Pyskir, A.; Walczak, M.; Bargassa, P.; Beirão Da Cruz E Silva, C.; Di Francesco, A.; Faccioli, P.; Galinhas, B.; Gallinaro, M.; Hollar, J.; Leonardo, N.; Lloret Iglesias, L.; Nemallapudi, M. 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2017-12-01
The first observation of top quark production in proton-nucleus collisions is reported using proton-lead data collected by the CMS experiment at the CERN LHC at a nucleon-nucleon center-of-mass energy of √{sN N }=8.16 TeV . The measurement is performed using events with exactly one isolated electron or muon candidate and at least four jets. The data sample corresponds to an integrated luminosity of 174 nb-1 . The significance of the t t ¯ signal against the background-only hypothesis is above 5 standard deviations. The measured cross section is σt t ¯=45 ±8 nb , consistent with predictions from perturbative quantum chromodynamics.
Observation of Top Quark Production in Proton-Nucleus Collisions.
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2017-12-15
The first observation of top quark production in proton-nucleus collisions is reported using proton-lead data collected by the CMS experiment at the CERN LHC at a nucleon-nucleon center-of-mass energy of sqrt[s_{NN}]=8.16 TeV. The measurement is performed using events with exactly one isolated electron or muon candidate and at least four jets. The data sample corresponds to an integrated luminosity of 174 nb^{-1}. The significance of the tt[over ¯] signal against the background-only hypothesis is above 5 standard deviations. The measured cross section is σ_{tt[over ¯]}=45±8 nb, consistent with predictions from perturbative quantum chromodynamics.
Saini, Anoop Kumar; Sharma, Vinay; Mathur, Pradeep; Shaikh, Mobin M.
2016-10-01
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.
International Nuclear Information System (INIS)
OLIMOV, K.; LUTPULLAEV, S.L.; PETROV, V.I.; OLIMOV, A.K.
2015-01-01
New experimental data on the partial inelasticity coefficients of negative pions produced in "1"6Op-collisions at 3.25 A GeV/s, pC-interactions at 4.2 and 9.9 GeV/s, and d,α,C(C)-collisions at 4.2 A GeV/s are presented. It is established that the behavior of partial inelasticity coefficients of pions at intermediate energies (<10 GeV) in hadron-nucleus collisions has a transitional character, reaching the limiting value at ultrahigh energies. It is shown that the mean values of partial inelasticity coefficients of pions produced in nucleus-nucleus collisions decrease with an increase in mass number of the projectile nucleus. (authors)
Neutrino-nucleus collision at intermediate energy
International Nuclear Information System (INIS)
Kosmas, T.S.; Oset, E.
1999-01-01
Neutrino-nucleus reactions at low and intermediate energy up to E ν = 500 MeV are studied for the most interesting nuclei from an experimental point of view. We focus on neutrino-nucleus cross-sections of semi-inclusive processes, for which recent measurements from radiochemical experiments at LAMPF and KARMEN laboratories are available. The method employed uses the modified Lindhard function for the description of the particle-hole excitations of the final nucleus via a local density approximation. (authors)
International Nuclear Information System (INIS)
Grishin, V.G.; Kladnitskaya, E.N.
1985-01-01
A phenomenological model for inelastic nucleus-nucleus interactions at momenta below 5 GeV/c per nucleon is described. Particle interactions inside the interacting nuclei are described by phenomenological models of hadron-nucleus and hadron-nucleon interactions. The Monte-Carlo model provides the kinematic variables for a set of events under study. The comparison of the model inclusive distri-- butions for different particles and nucleus-nucleus interactions agrees well with the experimental data
Study of Hadron Production in Hadron-Nucleus and Nucleus-Nucleus Collisions at the CERN SPS
Klochkov, V; Herve, A E; Kowalski, S; Kaptur, E A; Kowalik, K L; Dominik, W M; Matulewicz, T N; Krasnoperov, A; Feofilov, G; Vinogradov, L; Kovalenko, V; Johnson, S R; Planeta, R J; Rubbia, A; Marton, K; Messerly, B A; Puzovic, J; Bogomilov, M V; Bravar, A; 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; Mathes, H; Roehrich, D; Marcinek, A J; Marino, A D; Grebieszkow, K; Di luise, S; 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; Koziel, M E; Rondio, E; Larsen, D T; Czopowicz, T R; Seyboth, P; Turko, L; Guber, F; Marin, V; Busygina, O; Strikhanov, M; Taranenko, A; Cirkovic, 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; Blondel, A P P; Stroebele, H W; Posiadala, M Z; Kolesnikov, V; Andronov, E; Zimmerman, E D; Antoniou, N; Majka, Z; 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; Morgala, S J; Paolone, V; Damyanova, A; Gazdzicki, M; Unger, M T; Wilczek, A G; Stepaniak, J M; Seryakov, A; Susa, T; Staszel, P P; Brzychczyk, J; Maksiak, B; Tefelski, D B
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...
K sup + nucleus total cross sections
Energy Technology Data Exchange (ETDEWEB)
Sawafta, R.
1990-01-01
The scattering of K{sup +} mesons from nuclei has attracted considerable interest in the last few years. The K{sup +} holds a very special position as the weakest of all strongly interaction probes. The average cross section is not larger than about 10 mb at lab momenta below 800 MeV/c, corresponding to a mean free path in the nucleus larger than 5 fm. Thus the K{sup +} is capable of probing the entire volume of the nucleus. Single scattering of the K{sup +} with a nucleon in the nucleus dominates the nuclear scattering, and only small and calculable higher order corrections are needed. The nucleon is a dynamical entity and its internal structure can, in principle, be altered by its surrounding nuclear environment. This work reports an experiment in which the K{sup +} is used to compare the nucleon in the nucleus with a free nucleon.
The nucleus in Finland - The second report
International Nuclear Information System (INIS)
Aurela, Jorma; Korteniemi, Virpi; Halme-Tapanainen, Kristina
1993-01-01
The Finnish Nuclear Society (FNS) started the distribution of the Nucleus bulletin at the beginning of 1988. The volume of distribution has been extended since, including today nearly 1,000 persons. Both the English and the Finnish version of the bulletin is sent to various opinion leaders of society, i.e. the members of the parliament, ministries, the media, representatives of industry and other decision-makers of the energy field. After the five-year history of the Nucleus in Finland, it is time to look back and sum up the present status of the Nucleus. This report gives a short summary concerning the present distribution and its efficiency, the experiences gained and the influence of the bulletin in Finland. The first questionnaire was sent in November 1988, and the survey was repeated among the Finnish readers of the Nucleus in autumn 1992. The results of the latter survey are given in this report
Microtubules move the nucleus to quiescence.
Laporte, Damien; Sagot, Isabelle
2014-01-01
The nucleus is a cellular compartment that hosts several macro-molecular machines displaying a highly complex spatial organization. This tight architectural orchestration determines not only DNA replication and repair but also regulates gene expression. In budding yeast microtubules play a key role in structuring the nucleus since they condition the Rabl arrangement in G1 and chromosome partitioning during mitosis through their attachment to centromeres via the kinetochore proteins. Recently, we have shown that upon quiescence entry, intranuclear microtubules emanating from the spindle pole body elongate to form a highly stable bundle that spans the entire nucleus. Here, we examine some molecular mechanisms that may underlie the formation of this structure. As the intranuclear microtubule bundle causes a profound re-organization of the yeast nucleus and is required for cell survival during quiescence, we discuss the possibility that the assembly of such a structure participates in quiescence establishment.
Transport of glutathione into the nucleus.
Queval, Guillaume; Foyer, Christine
2014-10-01
The tripeptide thiol glutathione (GSH) is present in the nucleus of plant and animal cells. However, the functions of GSH in the nucleus remain poorly characterised. GSH appears to become sequestered in the nucleus at the early stages of the cell cycle. As part of our search for proteins that may be involved in GSH transport into the nucleus, we studied the functions of the nucleoporin called Alacrima Achalasia aDrenal Insufficiency Neurologic disorder (ALADIN). ALADIN is encoded by the Achalasia-Addisonianism-Alacrimia (AAAS) gene in mammalian cells. Defects in ALADIN promote adrenal disorders and lead to the triple A syndrome in humans. The ALADIN protein localizes to the nuclear envelope in Arabidopsis thaliana and interacts with other components of the nuclear pore complex (NPC). We characterised the functions of the ALADIN protein in an Arabidopsis thaliana T-DNA insertion knockout mutant, which shows slow growth compared to the wild type. Copyright © 2014. Published by Elsevier Inc.
Nuclear physics: Unexpected doubly-magic nucleus
International Nuclear Information System (INIS)
Janssens, R.V.F.
2009-01-01
Nuclei with a 'magic' number of both protons and neutrons, dubbed doubly magic, are particularly stable. The oxygen isotope 24 O has been found to be one such nucleus - yet it lies just at the limit of stability
Pion-nucleus cross sections approximation
International Nuclear Information System (INIS)
Barashenkov, V.S.; Polanski, A.; Sosnin, A.N.
1990-01-01
Analytical approximation of pion-nucleus elastic and inelastic interaction cross-section is suggested, with could be applied in the energy range exceeding several dozens of MeV for nuclei heavier than beryllium. 3 refs.; 4 tabs
Kaon-nucleus reactions and hypernuclei
International Nuclear Information System (INIS)
Dover, C.B.
1987-01-01
Recent advances in hypernuclear physics and kaon-nucleus scattering are discussed, with emphasis on the spectroscopy of Λ single particle states in heavy systems, as revealed by the (π + ,K + ) reaction. 26 refs., 8 figs
International Nuclear Information System (INIS)
Ye Yunxiu; Zhou Xin; Ji Gang; Su Shufang; Zhu Guohuai
1996-01-01
The transverse polarization of lambda produced in relativistic nucleus-nucleus collisions is determined. The effect from the interaction between spin moment and magnetic field is corrected. The near zero transverse polarization and non-correlation between transverse polarization and transverse momentum are obtained and compared to ones obtained from the nucleus-nucleus interactions at lower energies. This comparison shows that the production mechanism of lambdas in the relativistic nucleus-nucleus collisions is different from one in the nucleus-nucleus reactions at lower energies
Polarization and alignment of nucleus fission fragments
International Nuclear Information System (INIS)
Barabanov, A.L.; Grechukhin, D.P.
1987-01-01
Correlation of fragment orientation with orientation axis of fissile nucleus and with n-vector f vector of fragment divergence is considered. Estimations of polarization and alignment of fission fragments of preliminarily oriented nuclei in correlation (with n-vector f recording) and integral (with n-vector f averaging) experiments were conducted. It is shown that high sensitivity of polarization and fragment alignment to the character of nucleus movement at the stage of descent from barrier to rupture point exists
New aspects of the atomic nucleus
International Nuclear Information System (INIS)
Wilkinson, D.H.
1987-01-01
We are at last just beginning to identify convincing evidence for what we have long believed, namely that the nucleus is more than the sum of its neutron-proton parts taken pairwise because, for example, a cluster of three nucleons interacts differently from the sum of the interactions of its three pairs; there is an important collectivism in the life of a nucleus even before we ask what its nucleons are doing. (orig./WL)
Testing string dynamics in lepton nucleus reactions
International Nuclear Information System (INIS)
Gyulassy, M.; Pluemer, M.
1989-10-01
The sensitivity of nuclear attenuation of 10-100 GeV lepton nucleus (ell A) reactions to space-time aspects of hadronization is investigated within the context of the Lund string model. We consider two mechanisms for attenuation in a nucleus: final state cascading and string flip excitations. Implications for the evolution of the energy density in nuclear collisions are discussed. 16 refs., 10 figs
Numerical Simulation of the Kinetic Critical Nucleus
Sanada, Masaaki; Nishioka, Kazumi; Okada, Masahumi; Maksimov, Igor, L.
1997-01-01
Our main interest is to see whether the number density indicates a peak at the kinetically stable critical nucleus due to its kinetical stability. We have numerically calculated the time evolution of the number densities of clusters in the case of water vapor nucleation. We employ the condition in which the difference between the size of the thermodynamic crtitical nucleus and that of the kinetic one is appreciable. The results show that the peak does not appear in the number densities of clu...
Advances in hard nucleus cataract surgery
Directory of Open Access Journals (Sweden)
Wei Cui
2013-11-01
Full Text Available Security and perfect vision and fewer complications are our goals in cataract surgery, and hard-nucleus cataract surgery is always a difficulty one. Many new studies indicate that micro-incision phacoemulsification in treating hard nucleus cataract is obviously effective. This article reviews the evolution process of hard nuclear cataract surgery, the new progress in the research of artificial intraocular lens for microincision, and analyse advantages and disadvantages of various surgical methods.
Improved Cloud Condensation Nucleus Spectrometer
Leu, Ming-Taun
2010-01-01
An improved thermal-gradient cloud condensation nucleus spectrometer (CCNS) has been designed to provide several enhancements over prior thermal- gradient counters, including fast response and high-sensitivity detection covering a wide range of supersaturations. CCNSs are used in laboratory research on the relationships among aerosols, supersaturation of air, and the formation of clouds. The operational characteristics of prior counters are such that it takes long times to determine aerosol critical supersaturations. Hence, there is a need for a CCNS capable of rapid scanning through a wide range of supersaturations. The present improved CCNS satisfies this need. The improved thermal-gradient CCNS (see Figure 1) incorporates the following notable features: a) The main chamber is bounded on the top and bottom by parallel thick copper plates, which are joined by a thermally conductive vertical wall on one side and a thermally nonconductive wall on the opposite side. b) To establish a temperature gradient needed to establish a supersaturation gradient, water at two different regulated temperatures is pumped through tubes along the edges of the copper plates at the thermally-nonconductive-wall side. Figure 2 presents an example of temperature and supersaturation gradients for one combination of regulated temperatures at the thermally-nonconductive-wall edges of the copper plates. c) To enable measurement of the temperature gradient, ten thermocouples are cemented to the external surfaces of the copper plates (five on the top plate and five on the bottom plate), spaced at equal intervals along the width axis of the main chamber near the outlet end. d) Pieces of filter paper or cotton felt are cemented onto the interior surfaces of the copper plates and, prior to each experimental run, are saturated with water to establish a supersaturation field inside the main chamber. e) A flow of monodisperse aerosol and a dilution flow of humid air are introduced into the main
Quark matter formation in high energy nucleus-nucleus collisions - predictions and observations
International Nuclear Information System (INIS)
Otterlund, I.
1983-01-01
In this talk I give a short summary of the recent discussion around predictions and possible observations of quark-gluon plasma and fireballs in ultrarelativistic nucleus-nucleus collisions. In particular this talk is focused on heavy ion reactions at 200 A GeV. (orig./HSI)
Effective number of inelastically interacting nucleons in rare nucleus-nucleus production processes
International Nuclear Information System (INIS)
Korotkikh, V.L.; Lokhtin, I.P.
1992-01-01
A model of nucleus-nucleus interaction using one inelastic NN-interaction is suggested for the exclusive production processes with small cross-section. A-dependence nuclear coherent and incoherent production cross-section are predicted. 20 refs.; 4 figs
High density QCD and nucleus-nucleus scattering deeply in the saturation region
International Nuclear Information System (INIS)
Kormilitzin, Andrey; Levin, Eugene; Miller, Jeremy S.
2011-01-01
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(-ConstY 2 )). 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.
Production of strange and multistrange hadrons in nucleus-nucleus collisions at the SPS
Czech Academy of Sciences Publication Activity Database
Antinori, F.; Bakke, H.; Beusch, W.; Staroba, Pavel; Závada, Petr
1999-01-01
Roč. 661, - (1999), 130c-139c ISSN 0375-9474 Institutional research plan: CEZ:AV0Z1010920 Keywords : production * nucleus-nucleus collisions * hadrons * strangeness * model predictions Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 2.088, year: 1999
The mechanism of nuclear energy release in nucleus-nucleus collisions
International Nuclear Information System (INIS)
Strugalski, Z.; Strugalska-Gola, E.
1998-01-01
The mechanism of intranuclear energy release in reactions induced by nucleus-nucleus collisions at energies higher than ∼ 0.5 GeV/nucl. is presented - as prompted experimentally. The intranuclear energy release goes through local damages of the colliding nuclei
Study of η-nucleus interaction through the formation of η-nucleus ...
Indian Academy of Sciences (India)
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 ...
Structural dynamics of the cell nucleus
Wiegert, Simon; Bading, Hilmar
2011-01-01
Neuronal morphology plays an essential role in signal processing in the brain. Individual neurons can undergo use-dependent changes in their shape and connectivity, which affects how intracellular processes are regulated and how signals are transferred from one cell to another in a neuronal network. Calcium is one of the most important intracellular second messengers regulating cellular morphologies and functions. In neurons, intracellular calcium levels are controlled by ion channels in the plasma membrane such as NMDA receptors (NMDARs), voltage-gated calcium channels (VGCCs) and certain α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) as well as by calcium exchange pathways between the cytosol and internal calcium stores including the endoplasmic reticulum and mitochondria. Synaptic activity and the subsequent opening of ligand and/or voltage-gated calcium channels can initiate cytosolic calcium transients which propagate towards the cell soma and enter the nucleus via its nuclear pore complexes (NPCs) embedded in the nuclear envelope. We recently described the discovery that in hippocampal neurons the morphology of the nucleus affects the calcium dynamics within the nucleus. Here we propose that nuclear infoldings determine whether a nucleus functions as an integrator or detector of oscillating calcium signals. We outline possible ties between nuclear mophology and transcriptional activity and discuss the importance of extending the approach to whole cell calcium signal modeling in order to understand synapse-to-nucleus communication in healthy and dysfunctional neurons. PMID:21738832
The nuclear response and the imaginary potential for nucleus-nucleus collisions
International Nuclear Information System (INIS)
Phatak, S.C.; Sinha, B.
1983-01-01
The Fermi-gas model is used in this paper to study the nucleus-nucleus collision. The field produced by one of the nuclei is considered to act on nucleons in the other nucleus, which is treated as a Fermi gas of radius R. The imaginary part of the (non-local) nucleus-nucleus potential is then computed by evaluating the energy-conserving second-order term in which the intermediate states are particle-hole excitations produced in the Fermi gas. The equivalent local potential, obtained by using the Perey-Saxon method, is compared with phenomenological imaginary potentials. Later it is shown that, in the limit of small range of non-locality, the imaginary potential can be related to the nuclear response function. With this, one can write the nuclear friction coefficient that is used in phenomenological analyses of heavy-ion collisions in terms of the imaginary potential. (orig.)
The dynamic landscape of the cell nucleus.
Austin, Christopher M; Bellini, Michel
2010-01-01
While the cell nucleus was described for the first time almost two centuries ago, our modern view of the nuclear architecture is primarily based on studies from the last two decades. This surprising late start coincides with the development of new, powerful strategies to probe for the spatial organization of nuclear activities in both fixed and live cells. As a result, three major principles have emerged: first, the nucleus is not just a bag filled with nucleic acids and proteins. Rather, many distinct functional domains, including the chromosomes, resides within the confines of the nuclear envelope. Second, all these nuclear domains are highly dynamic, with molecules exchanging rapidly between them and the surrounding nucleoplasm. Finally, the motion of molecules within the nucleoplasm appears to be mostly driven by random diffusion. Here, the emerging roles of several subnuclear domains are discussed in the context of the dynamic functions of the cell nucleus.
The atomic nucleus as a target
International Nuclear Information System (INIS)
Strugalski, Z.; Pawlak, T.
1981-01-01
The purpose of this article is to characterize the atomic nucleus used as a target in hadron-nucleus collision experiments. The atomic nucleus can be treated as a lens-shaped ''slab'' of nuclear matter. Such ''slab'' should be characterized by the nuclear matter layer thickness at any impact parameter, by its average thickness, and by its maximal thickness. Parameters characterizing atomic nuclei as targets are given for the elements: 6 12 C, 7 14 N, 8 16 O, 9 19 F, 10 20 Ne, 13 27 Al, 14 28 Si, 16 32 S, 18 40 Ar, 24 52 Cr, 26 54 Fe, 27 59 Co, 29 64 Cu, 30 65 Zn, 32 73 Ge, 35 80 Br, 47 100 Ag, 53 127 I, 54 131 Xe, 73 181 Ta, 74 184 W, 79 197 Au, 82 207 Pb, 92 -- 238 U [ru
Dynamics of hadron-nucleus interactions
International Nuclear Information System (INIS)
Wallace, S.J.
1981-07-01
Recent progress in diffraction theory shows that proton-nucleus scattering at nonforward angles is dominated by the interference of waves from two or more bright spots. Analytic formulas based on asymptotic theories of diffraction yield valuable new insights into the scattering and these formulas can be readily extended to illuminate the role of dynamical ingredients, i.e., the nucleon-nucleon amplitudes. The governing parameters of the diffraction and some direct connections between the observed cross sections and the input dynamics are reviewed. New information regarding the nucleon-nucleon parameters based on recent phase shift analyses show some systematic differences from the effective NN amplitudes which produce fits to proton-nucleus diffraction data. Recent progress in understanding the role of Δ-isobars in proton-nucleus dynamics is reviewed. 126 references
Heinsbroek, J. A.; Gipson, C. D.; Kupchik, Y. M.; Spencer, S.; Smith, A. C. W.; Roberts-Wolfe, D.; Kalivas, P. W.
2016-01-01
The nucleus accumbens is a major input structure of the basal ganglia and integrates information from cortical and limbic structures to mediate goal-directed behaviors. Chronic exposure to several classes of drugs of abuse disrupts plasticity in this region, allowing drug-associated cues to engender a pathologic motivation for drug seeking. A number of alterations in glutamatergic transmission occur within the nucleus accumbens after withdrawal from chronic drug exposure. These drug-induced neuroadaptations serve as the molecular basis for relapse vulnerability. In this review, we focus on the role that glutamate signal transduction in the nucleus accumbens plays in addiction-related behaviors. First, we explore the nucleus accumbens, including the cell types and neuronal populations present as well as afferent and efferent connections. Next we discuss rodent models of addiction and assess the viability of these models for testing candidate pharmacotherapies for the prevention of relapse. Then we provide a review of the literature describing how synaptic plasticity in the accumbens is altered after exposure to drugs of abuse and withdrawal and also how pharmacological manipulation of glutamate systems in the accumbens can inhibit drug seeking in the laboratory setting. Finally, we examine results from clinical trials in which pharmacotherapies designed to manipulate glutamate systems have been effective in treating relapse in human patients. Further elucidation of how drugs of abuse alter glutamatergic plasticity within the accumbens will be necessary for the development of new therapeutics for the treatment of addiction across all classes of addictive substances. PMID:27363441
The chimeric eukaryote: origin of the nucleus from the karyomastigont in amitochondriate protists
Margulis, L.; Dolan, M. F.; Guerrero, R.
2000-01-01
We present a testable model for the origin of the nucleus, the membrane-bounded organelle that defines eukaryotes. A chimeric cell evolved via symbiogenesis by syntrophic merger between an archaebacterium and a eubacterium. The archaebacterium, a thermoacidophil resembling extant Thermoplasma, generated hydrogen sulfide to protect the eubacterium, a heterotrophic swimmer comparable to Spirochaeta or Hollandina that oxidized sulfide to sulfur. Selection pressure for speed swimming and oxygen avoidance led to an ancient analogue of the extant cosmopolitan bacterial consortium "Thiodendron latens." By eubacterial-archaebacterial genetic integration, the chimera, an amitochondriate heterotroph, evolved. This "earliest branching protist" that formed by permanent DNA recombination generated the nucleus as a component of the karyomastigont, an intracellular complex that assured genetic continuity of the former symbionts. The karyomastigont organellar system, common in extant amitochondriate protists as well as in presumed mitochondriate ancestors, minimally consists of a single nucleus, a single kinetosome and their protein connector. As predecessor of standard mitosis, the karyomastigont preceded free (unattached) nuclei. The nucleus evolved in karyomastigont ancestors by detachment at least five times (archamoebae, calonymphids, chlorophyte green algae, ciliates, foraminifera). This specific model of syntrophic chimeric fusion can be proved by sequence comparison of functional domains of motility proteins isolated from candidate taxa.
DEFF Research Database (Denmark)
Vrang, N.; Larsen, P.J.; Mikkelsen, J.D.
1995-01-01
Suprachiasmatic nucleus, paraventricular nucleus, circadian rhythms, phaseolus vulgaris-leucoagglutinin, corticotropin-releasing factor, dual immunocytochemistry......Suprachiasmatic nucleus, paraventricular nucleus, circadian rhythms, phaseolus vulgaris-leucoagglutinin, corticotropin-releasing factor, dual immunocytochemistry...
Experimental search for compression phenomena in fast nucleus--nucleus collisions
International Nuclear Information System (INIS)
Schopper, E.; Baumgardt, H.G.; Obst, E.
1977-01-01
The occurrence of compression phenomena and shock waves, connected with the increase of the density of the nuclear matter during the interpenetration of two fast nuclei, are discussed. Current experiments dealing with this problem are reviewed. Before considering the mechanism of the interpenetration of two fast nuclei it may be useful to look at more simple situations, i.e., proton-proton interactions, then to envelop them with nuclear matter, considering proton-nucleus interactions. Only very general features are described, which may give suggestions for the understanding of the nucleus-nucleus impact
TWO-PHOTON PHYSICS IN NUCLEUS-NUCLEUS COLLISIONS AT RHIC
International Nuclear Information System (INIS)
Nystrand, J.; Klein, S.
1998-01-01
Ultra-relativistic heavy-ions carry strong electromagnetic and nuclear fields. Interactions between these fields in peripheral nucleus-nucleus collisions can probe many interesting physics topics. This presentation will focus on coherent two-photon and photonuclear processes at RHIC. The rates for these interactions will be high. The coherent coupling of all the protons in the nucleus enhances the equivalent photon flux by a factor Z 2 up to an energy of ∼ 3 GeV. The plans for studying coherent interactions with the STAR experiment will be discussed. Experimental techniques for separating signal from background will be presented
Two-photon physics in nucleus-nucleus collisions at RHIC
International Nuclear Information System (INIS)
Nystrand, J.; Klein, S.
1998-01-01
Ultra-relativistic heavy-ions carry strong electromagnetic and nuclear fields. Interactions between these fields in peripheral nucleus-nucleus collisions can probe many interesting physics topics. This presentation will focus on coherent two-photon and photonuclear processes at RHIC. The rates for these interactions will be high. The coherent coupling of all the protons in the nucleus enhances the equivalent photon flux by a factor Z 2 up to an energy of ∼ 3 GeV. The plans for studying coherent interactions with the STAR experiment will be discussed. Experimental techniques for separating signal from background will be presented
What experiments on pinned nanobubbles can tell about the critical nucleus for bubble nucleation.
Xiao, Qianxiang; Liu, Yawei; Guo, Zhenjiang; Liu, Zhiping; Frenkel, Daan; Dobnikar, Jure; Zhang, Xianren
2017-12-22
The process of homogeneous bubble nucleation is almost impossible to probe experimentally, except near the critical point or for liquids under large negative tension. Elsewhere in the phase diagram, the bubble nucleation barrier is so high as to be effectively insurmountable. Consequently, there is a severe lack of experimental studies of homogenous bubble nucleation under conditions of practical importance (e.g., cavitation). Here we use a simple geometric relation to show that we can obtain information about the homogeneous nucleation process from Molecular Dynamics studies of bubble formation in solvophobic nanopores on a solid surface. The free energy of pinned nanobubbles has two extrema as a function of volume: one state corresponds to a free-energy maximum ("the critical nucleus"), the other corresponds to a free-energy minimum (the metastable, pinned nanobubble). Provided that the surface tension does not depend on nanobubble curvature, the radius of the curvature of the metastable surface nanobubble is independent of the radius of the pore and is equal to the radius of the critical nucleus in homogenous bubble nucleation. This observation opens the way to probe the parameters that determine homogeneous bubble nucleation under experimentally accessible conditions, e.g. with AFM studies of metastable nanobubbles. Our theoretical analysis also indicates that a surface with pores of different sizes can be used to determine the curvature corrections to the surface tension. Our conclusions are not limited to bubble nucleation but suggest that a similar approach could be used to probe the structure of critical nuclei in crystal nucleation.
Future prospects in N-nucleus interactions
International Nuclear Information System (INIS)
Moss, J.M.
1983-01-01
A detailed examination of two research areas, polarization observables and antiproton-nucleus reactions, which should have near-term future impact on the understanding of the interaction of medium-energy nucleons in nuclei is made. More speculative future experiments employing cooled beams, double spectrometer systems, and large Q-value, low momentum-transfer reactions are also discussed. 25 references, 4 figures
Consequences of hadron-nucleus multiplicity parametrization
International Nuclear Information System (INIS)
Singh, C.P.; Shyam, M.
1986-01-01
Some interesting consequences are analyzed of a new parametrization for the hadron-nucleus multiplicity distributions and they are compared with the experimental data. Further, it is illustrated how the scaling property for the average multiplicity will be modified and it is found that the experimental data support this behaviour. (orig.)
High energy hadron-nucleus scattering
International Nuclear Information System (INIS)
Koplik, J.; Mueller, A.H.
1975-01-01
Theoretical expectations for hadron-nucleus scattering at high energy if the basic hadron-hadron interaction is due to Regge poles and cuts arising in multiperipheral or soft field theory models are described. Experiments at Fermilab may provide a critical test of such models
Large philipsite crystal as ferromanganese nodule nucleus
Digital Repository Service at National Institute of Oceanography (India)
Ghosh, A.K.; Mukhopadhyay, R.
nodule accretion as approximately 2 mm/Ma and that of phillipsite growth as approximately 0.65 mm/Ka, the nucleus material appears to have been growing for approximately 4.5-5 Ma. Originally surfaced as a rock fragment from late Miocene volcanism...
Correlations in hadron-nucleus collisions
International Nuclear Information System (INIS)
Wosiek, B.
1976-09-01
The correlations between the particles produced in interactions of hadrons with emulsion nuclei were investigated. The data are in qualitative agreement with the models which describe the interactions with nuclei as subsequent collisions of the fast part of excited hadronic matter inside the nucleus. (author)
Inside a plant nucleus: discovering the proteins
Czech Academy of Sciences Publication Activity Database
Petrovská, Beáta; Šebela, M.; Doležel, Jaroslav
2015-01-01
Roč. 66, č. 6 (2015), s. 1627-1640 ISSN 0022-0957 R&D Projects: GA ČR(CZ) GA14-28443S; GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Cell nucleus * chromatin * genome function Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.677, year: 2015
Iliacus Abscess with Radiculopathy Mimicking Herniated Nucleus ...
African Journals Online (AJOL)
2016-05-02
May 2, 2016 ... radiculopathy mimicking herniated nucleus pulposus: Aadditional diagnostic value of magnetic resonance imaging. Niger J Clin Pract. 2017;20:392-3. This is an open access article distributed under the terms of the Creative Commons. Attribution-Non Commercial-Share Alike 3.0 License, which allows ...
Resonances in η-light nucleus systems
Indian Academy of Sciences (India)
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 ...
Compound nucleus studies withy reverse kinematics
International Nuclear Information System (INIS)
Moretto, L.G.
1985-06-01
Reverse kinematics reactions are used to demonstrate the compound nucleus origin of intermediate mass particles at low energies and the extension of the same mechanism at higher energies. No evidence has appeared in our energy range for liquid-vapor equilibrium or cold fragmentation mechanisms. 11 refs., 12 figs
Formation of proton-fragments in hadron-nucleus and nucleus-nucleus collisions at high energies
International Nuclear Information System (INIS)
Bazarov, E.Kh.; Olimov, K.; Petrov, V.I.; Lutpullaev, S.L.
2006-01-01
Full text: The investigation of production of protons in hadron- and nucleus-nucleus interactions is a key problem allowing one to establish the singularities of dynamics of nuclear interactions. The formation of proton-fragments at high energies of colliding particles proceeds within both the interaction of hadrons with nuclei and in the process of decay of the nucleus or its de-excitation at peripheral interactions. At different stages of interaction of impinging particle with target nucleus, the different mechanisms of formation of proton-fragments: the direct knock-out of intranuclear nucleons in the process of high energy cascade of an initial hadron, intranuclear cascade of produced particles, decay of the excited multi-nucleon fragments and of the thermalized remnant nucleus, and the coalescence of nuclear fragments to the new clusters are realized with the certain probability, connected to the interaction parameters (the interaction energy, the parameter of collision, the intranuclear density, the configuration of Fermi momentum of nucleons and clusters of target nucleus et al.). In its turn, the mechanisms of formation of the final nuclear fragments are closely related to the type of excitation of an initial nucleus. The peripheral interactions proceed at small transfers of the momentum of an impinging particle and represent the wide class of reactions covering the processes from diffractive or coulomb collective excitations of the whole nucleus to the direct quasi-elastic knock-out of the separate nucleons. Non-peripheral interactions are caused by comparatively high local transfers of momentum to the intranuclear clusters allowing the development of intranuclear cascade and the asymmetric redistribution of energy of an impinging particle. The central collisions causing the full decay of nucleus on nucleons or few-nucleon fragments, are the limiting case of the maximal development of the intranuclear cascade. The interaction of the initial particles with
Buijs, Frederik N.; Guzmán-Ruiz, Mara; León-Mercado, Luis; Basualdo, Mari Carmen; Escobar, Carolina; Kalsbeek, Andries; Buijs, Ruud M.
2017-01-01
The suprachiasmatic nucleus (SCN) is generally considered the master clock, independently driving all circadian rhythms. We recently demonstrated the SCN receives metabolic and cardiovascular feedback adeptly altering its neuronal activity. In the present study, we show that microcuts effectively
Buijs, R. M.; Hermes, M. H.; Kalsbeek, A.
1998-01-01
Vasopressin (VP) is one of the principal neurotransmitters of the suprachiasmatic nucleus (SCN). By means of anatomical, physiological and electrophysiological techniques we have demonstrated that VP containing pathways from the SCN serve to affect neuroendocrine and 'autonomic' neurons in the
Effective nucleus-nucleus potentials derived from the generator coordinate method
Energy Technology Data Exchange (ETDEWEB)
Friedrich, H; Canto, L F [Oxford Univ. (UK). Dept. of Theoretical Physics
1977-11-07
The equivalence of the generator coordinate method (GCM) and the resonating group method (RGM) and the formal equivalence of the RGM and the orthogonality condition model (OCM) lead to a relation connecting the effective nucleus-nucleus potentials of the OCM with matrix elements of the GCM. This relation may be used to derive effective nucleus-nucleus potentials directly from GCM matrix elements without explicit reference to the potentials of the RGM. In a first application local and l-independent effective potentials are derived from diagonal GCM matrix elements which represent the energy surfaces of a two-centre shell model. Using these potentials the OCM can reproduce the results of a full RGM calculation very well for the elastic scattering of two ..cap alpha..-particles and fairly well for elastic /sup 16/O-/sup 16/O scattering.
International Nuclear Information System (INIS)
Agakishiev, G.; Man'yakov, P.K.; Drees, A.
1997-01-01
The simple and fast detector of charged particle multiplicity for relativistic nucleus-nucleus collision studies is performed. The multiplicity detector has been designed for the first level trigger of the CERES/NA45 experiment to study Pb-Au collisions at CERN SPS energies. The detector has allowed a realization of the 40 ns trigger for selection of events with definite impact parameter. The construction, operation characteristics, method of calibration, and testing results are described in detail
Random matrix theory and analysis of nucleus-nucleus collision at high energies
International Nuclear Information System (INIS)
Shahaliev, E.I.; Inst. of Radiation Problems, Baku; ); Kuznetsov, A.A.; Suleymanov, M.K.; ); Teryaev, O.V.; )
2006-01-01
A novel method for analysis of experimental data obtained at relativistic nucleus-nucleus collisions is proposed. The method, based on the ideas of Random Matrix Theory, is applied to detect systematic errors that occur at measurements of momentum distributions of emitted particles. The unfolded momentum distribution is well described by the Gaussian orthogonal ensemble of random matrices, when the uncertainty in the momentum distribution is maximal. The method is free from unwanted background contributions [ru
Theory of and effects from elastoplasticity in nucleus-nucleus collisions
International Nuclear Information System (INIS)
Noerenberg, W.; Technische Hochschule Darmstadt
1985-02-01
Elastoplasticity of finite Fermi systems results from a coherent coupling between collective and intrinsic degrees of freedom and subsequent equilibration essentially due to two-body collisions. Within a non-markovian transport-theoretical approach referred to as dissipative diabatic dynamics (DDD), elastoplastical forms the link between giant vibrations and overdamped motion of nuclear. Obersvable effects resulting from this non-markovian behaviour in nucleus-nucleus collisions are discussed. (orig.)
Strangeness and charm production in nucleus-nucleus collisions at beam energies near the thresholds
International Nuclear Information System (INIS)
Senger, P.
2001-01-01
The creation of strangeness and charm in nucleus-nucleus collisions at threshold beam energies is discussed as a probe for compressed baryonic matter. Experimental data on strangeness production at SIS energies indicate that the properties of kaons and antikaons are modified in the dense nuclear medium. An experiment is proposed to explore the QCD phase diagram in the region of highest baryon densities. An important observable will be charm production close to threshold. (orig.)
International Nuclear Information System (INIS)
Imanishi, B.; Misono, S.; von Oertzen, W.; Voit, H.
1988-08-01
The molecular orbitals of the nucleon(s) in nucleus-nucleus collisions are dynamically defined as a linear combination of nucleon single-particle orbits (LCNO) in a rotating frame by using the coupled-reaction-channel (CRC) theory. Nucleon molecular orbitals and the promotions of nucleon, - especially due to the Landau-Zener radial coupling are discussed with the method above mentioned. (author)
Multi-quark effects in high energy nucleon-nucleon and nucleus-nucleus collisions
International Nuclear Information System (INIS)
Besliu, C.; Caraciuc, I.; Jipa, A.; Olariu, A.; Topor-Pop, R.; Cotorobai, F.; Pantea, D.; Popa, L.; Popa, V.; Topor-Pop, V.
1988-02-01
Recent data obtained in two experiments performed in the framework of the Bucharest-Dubna collaboration are presented, i.e.: the observation of narrow dibaryonic resonances is neutron-proton interactions in 1mHBC at different momenta of incident neutrons in the range 1-5 GeV/c, and the cumulative production of negative pions in nucleus-nucleus interactions in SKM-200 streamer chamber at 4.5 GeV/c. (authors)
Teacher Candidate Selection and Evaluation.
Collins, Mary Lynn; And Others
Summaries are presented of three papers presented at a summer workshop on Quality Assurance in Teacher Education conducted by the Association of Teacher Educators. The general topic covered by these presentations was teacher candidate selection and evaluation. Papers focused upon the following questions: (1) What entry level criteria should 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.
ψ' and J/ψ suppression in high-energy nucleon-nucleus and nucleus-nucleus collisions
International Nuclear Information System (INIS)
Wong, Cheuk-Yin.
1995-01-01
The observed features of ψ' to J/ψ suppression in pA and nucleus-nucleus collisions can be explained in terms of a two-component absorption model. For the hard component of the absorption due to the interaction of the produced c bar c systems with baryons at high relative energies, the absorption cross sections are insensitive to the radii of the c bar c systems, as described by the Additive Quark Model. For the soft component due to the low energy c bar c interactions with soft particles produced by other baryon-baryon collisions, the absorption cross sections are greater for ψ' than for J/ψ, because the breakup threshold for ψ' is much smaller than for ψ
International Nuclear Information System (INIS)
Szymanski, P.
2006-09-01
This work concerns soft hadronic interactions which in the Standard Model carry most of the observable cross-section but are not amenable to quantitative predictions due to the very nature of the QCD (Theory of Strong Interactions). In the low momentum transfer region the evolving coupling constant caused perturbation theory to break down. In this situation better experimental understanding of the physics phenomena is needed. One aspect of the soft hadronic interactions will be discussed in this work: transfer of the baryon number from the initial to the final state of the interaction. The past experimental knowledge on this process is presented, reasons for its unsatisfactory status are discussed and condition necessary for improvement are outlined: that is experimental apparatus with superior performance over the full range of available interactions: hadron-hadron collision, hadron-nucleus and nucleus-nucleus interactions. A consistent model-independent picture of the baryon number transfer process emerging from the data on the full range of interactions is shown. It offers serious challenge to theory to provide quantitative and detailed explanation of the measurements. (author)
Cell Nucleus-Targeting Zwitterionic Carbon Dots.
Jung, Yun Kyung; Shin, Eeseul; Kim, Byeong-Su
2015-12-22
An innovative nucleus-targeting zwitterionic carbon dot (CD) vehicle has been developed for anticancer drug delivery and optical monitoring. The zwitterionic functional groups of the CDs introduced by a simple one-step synthesis using β-alanine as a passivating and zwitterionic ligand allow cytoplasmic uptake and subsequent nuclear translocation of the CDs. Moreover, multicolor fluorescence improves the accuracy of the CDs as an optical code. The CD-based drug delivery system constructed by non-covalent grafting of doxorubicin, exhibits superior antitumor efficacy owing to enhanced nuclear delivery in vitro and tumor accumulation in vivo, resulting in highly effective tumor growth inhibition. Since the zwitterionic CDs are highly biocompatible and effectively translocated into the nucleus, it provides a compelling solution to a multifunctional nanoparticle for substantially enhanced nuclear uptake of drugs and optical monitoring of translocation.
Nucleus spectroscopy: extreme masses and deformations
International Nuclear Information System (INIS)
Theisen, Ch.
2009-12-01
The author proposes a synthesis of research activities performed since 1995 in the field of experimental nuclear physics, and more particularly in the investigation of two nucleus extreme states: deformation on the one hand, heavy and very heavy nuclei on the other hand. After a presentation of the context of investigations on deformation, rotation, and heavy nuclei, he gives an overview of developments regarding instruments (gamma spectrometers, detection of fission fragments, and detection at the focal plane of spectrometers or separators) and analysis techniques. Experiments and results are then reported and discussed, concerning super-deformed states with a high angular moment, spectroscopy of neutron-rich nuclei, very heavy nuclei close to nucleus map borders. He finally draws perspectives for middle and long term studies on the heaviest nuclei
η production in proton-nucleus reactions
International Nuclear Information System (INIS)
Cassing, W.; Batko, G.; Vetter, T.; Wolf, G.
1991-01-01
The production of η-mesons in proton-nucleus reactions is analysed with respect to primary nucleon-nucleon (NN→NN η ) and secondary pion-nucleon (πN→ηN) production processes on the basis of Hartree-Fock groundstate momentum distributions and free on-shell production processes. The folding model adopted compares well for meson production with more involved simulations based on VUU transport equations. Similar to K + production in proton-nucleus reactions the η-mesons are primarily produced by the πN→ηN channel. However, η-mesons are absorbed in nuclei via excitation of the N * (1535) resonance which leads to strong distortions of the primordial spectra. On the other hand, the experimental mass dependence of the differential cross sections might yield information about the in-medium properties of this resonance. (orig.)
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....
Polarization of lanthanum nucleus by dynamic polarization method
International Nuclear Information System (INIS)
Adachi, Toshikazu; Ishimoto, Shigeru; Masuda, Yasuhiro; Morimoto, Kimio
1989-01-01
Preliminary studies have been carried out concerning the application of a dynamic polarization method to polarizing lanthanum fluoride single crystal to be employed as target in experiments with time reversal invariance. The present report briefly outlines the dynamic polarization method and describes some preliminary studies carried out so far. Dynamic polarization is of particular importance because no techniques are currently available that can produce highly polarized static nucleus. Spin interaction between electrons and protons (nuclei) plays a major role in the dynamic polarization method. In a thermal equilibrium state, electrons are polarized almost completely while most protons are not polarized. Positively polarized proton spin is produced by applying microwave to this system. The most hopeful candidate target material is single crystal of LaF 3 containing neodymium because the crystal is chemically stable and easy to handle. The spin direction is of great importance in experiments with time reversal invariance. The spin of neutrons in the target can be cancelled by adjusting the external magnetic field applied to a frozen polarized target. In a frozen spin state, the polarity decreases slowly with a relaxation time that depends on the external magnetic field and temperature. (N.K.)
Is atomic energy different from a nucleus?
International Nuclear Information System (INIS)
Lee, Sun Young
1995-07-01
This book describes of two faces of nuclear energy : the secret of a nuclear, the history of nuclear energy : the scientists with a nuclear, the nuclear energy generation : the third disapprobation, a nuclear weapon : Choice of fear, the Korean peninsula and a nuclear and nuclear energy and utilization in peace. It consists of 31 questions and the answers of the questions about nuclear energy and nucleus.
Nuclear alignment following compound nucleus reactions
International Nuclear Information System (INIS)
Butler, P.A.; Nolan, P.J.
1981-01-01
A procedure for calculating the alignment of a nuclear state populated by a compound nucleus reaction is given and used to investigate how alignment varies for different types of population mechanisms. The calculations are compared to both predictions of Gaussian models for the state population distribution and to experimental data, for a variety of types of nuclear reactions. The treatment of alignment in the analysis of γ-ray angular distribution is discussed. (orig.)
Momentum distribution in the nucleus. II
International Nuclear Information System (INIS)
Amado, R.D.; Woloshyn, R.M.
1977-01-01
We calculate the single particle momentum distribution n(q) for a one-dimensional model with delta forces. There is a domain of q for which n(q) has an exponential falloff; but, after allowance is made for the nonsaturation in the model, that domain does not grow significantly with particle number. The relation of this result to large momentum scattering from the nucleus and to the Hartree approximation is briefly discussed
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.
Parity violation in the compound nucleus
International Nuclear Information System (INIS)
Mitchell, G. E.; Crawford, B. E.; Grossmann, C. A.; Lowie, L. Y.; Bowman, J. D.; Knudson, J.; Penttilae, S.; Seestrom, S. J.; Smith, D. A.; Yen, Yi-Fen; Yuan, V. W.; Delheij, P. P. J.; Haseyama, T.; Masaike, A.; Matsuda, Y.; Postma, H.; Roberson, N. R.; Sharapov, E. I.; Stephenson, S. L.
1999-01-01
Measurements have been performed on the helicity dependence of the neutron resonance cross section for many nuclei by our TRIPLE Collaboration. A large number of parity violations are observed. Generic enhancements amplify the signal for symmetry breaking and the stochastic properties of the compound nucleus permit the strength of the symmetry-breaking interaction to be determined without knowledge of the wave functions of individual states. A total of 15 nuclei have been analyzed with this statistical approach. The results are summarized
Study of fragmentation reactions of light nucleus
International Nuclear Information System (INIS)
Toneli, David Arruda; Carlson, Brett Vern
2011-01-01
Full text: The decay of the compound nucleus is traditionally calculated using a sequential emission model, such as the Weisskopf-Ewing or Hauser-Feshbach ones, in which the compound nucleus decays through a series of residual nuclei by emitting one particle at a time until there is no longer sufficient energy for further emission. In light compound nucleus, however, the excitation energy necessary to fully disintegrate the system is relatively easy to attain. In such cases, decay by simultaneous emission of two or more particles becomes important. A model which takes into account all these decay is the Fermi fragmentation model. Recently, the equivalence between the Fermi fragmentation model and statistical multifragmentation model used to describe the decay for highly excited fragments for reactions of heavy ions was demonstrated. Due the simplicity of the thermodynamic treatment used in the multifragmentation model, we have adapted it to the calculation of Fermi breakup of light nuclei. The ultimate goal of this study is to calculate the distribution of isotopes produced in proton-induced reactions on light nuclei of biological interest, such as C, O e Ca. Although most of these residual nuclei possess extremely short half-lives and thus represent little long-term danger, they tend to be deficient in neutrons and to decay by positron emission, which allows the monitoring of proton radiotherapy by PET (Positron Emission Tomography). (author)
Antinucleon-nucleus elastic and inelastic scattering
International Nuclear Information System (INIS)
Dover, C.B.; Millener, D.J.
1985-01-01
A general overview of the utility of antinucleon (anti N)-nucleus inelastic scattering studies is presented, emphasizing both the sensitivity of the cross sections to various components of the N anti N transition amplitudes and the prospects for the exploration of some novel aspects of nuclear structure. We start with an examination of the relation between NN and N anti N potentials, focusing on the coherences predicted for the central, spin-orbit and tensor components, and how these may be revealed by measurements of two-body spin observables. We next discuss the role of the nucleus as a spin and isospin filter, and show how, by a judicious choice of final state quantum numbers (natural or unnatural parity states, isospin transfer ΔT = 0 or 1) and momentum transfer q, one can isolate different components of the N anti N transition amplitude. Various models for the N anti N interaction which give reasonable fits to the available two-body data are shown to lead to strikingly different predictions for certain spin-flip nuclear transitions. We suggest several possible directions for future anti N-nucleus inelastic scattering experiments, for instance the study of spin observables which would be accessible with polarized anti N beams, charge exchange reactions, and higher resolution studies of the (anti p, anti p') reaction. We compare the antinucleon and the nucleon as a probe of nuclear modes of excitation. 40 refs., 13 figs
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...
Wang, Xiao-Dong; Peng, Xiao-Feng; Tian, Yong; Wang, Bu-Xuan
2005-05-01
In this paper, the concept of the molecular free path is introduced to derive a criterion distinguishing active molecules from inactive molecules in liquid phase. A concept of the critical aggregation concentration (CAC) of active molecules is proposed to describe the physical configuration before the formation of a nucleus during vapor-liquid phase transition. All active molecules exist as monomers when the concentration of active molecules is lower than CAC, while the active molecules will generate aggregation once the concentration of the active molecules reaches CAC. However, these aggregates with aggregation number, N, smaller than five can steadily exist in bulk phase. The other excess active molecules can only produce infinite aggregation and form a critical nucleus of vapor-liquid phase transition. Without any outer perturbation the state point of CAC corresponds to the critical superheated or supercooled state. Meanwhile, 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 of 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 provides solid theoretical evidences to clarify the definition of nucleation rate and understand nucleation phenomenon with the insight into the physical nature.
J/$\\psi$ production in proton-nucleus and nucleus-nucleus interactions at the CERN SPS
Abreu, M C; Alexa, C; Arnaldi, R; Ataian, M R; Baglin, C; Baldit, A; Bedjidian, Marc; Beolè, S; Boldea, V; Bordalo, P; Borges, G; Bussière, A; Capelli, L; Castanier, C; Castor, J I; Chaurand, B; Chevrot, I; Cheynis, B; Chiavassa, E; Cicalò, C; Claudino, T; Comets, M P; Constans, N; Constantinescu, S; Cortese, P; De Falco, A; De Marco, N; Dellacasa, G; Devaux, A; Dita, S; Drapier, O; Ducroux, L; Espagnon, B; Fargeix, J; Force, P; Gallio, M; Gavrilov, Yu K; Gerschel, C; Giubellino, P; Golubeva, M B; Gonin, M; Grigorian, A A; Grossiord, J Y; Guber, F F; Guichard, A; Gulkanian, H R; Hakobyan, R S; Haroutunian, R; Idzik, M; Jouan, D; Karavitcheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; Macciotta, P; MacCormick, M; Marzari-Chiesa, A; Masera, M; Masoni, A; Monteno, M; Musso, A; Petiau, P; Piccotti, A; Pizzi, J R; Prado da Silva, W L; Prino, F; Puddu, G; Quintans, C; Ramello, L; Ramos, S; Rato-Mendes, P; Riccati, L; Romana, A; Santos, H; Saturnini, P; Scalas, E; Scomparin, E; Serci, S; Shahoyan, R; Sigaudo, F; Silva, S; Sitta, M; Sonderegger, P; Tarrago, X; Topilskaya, N S; Usai, G L; Vercellin, Ermanno; Villatte, L; Willis, N
2002-01-01
The NA38 and NA50 experiments at the CERN SPS have measured charmonium production in different colliding systems with the aim of observing a phase transition from ordinary hadronic matter towards a state in which quarks and gluons are deconfined (quark-gluon plasma, QGP). This experimental research is based on the prediction that the J/ psi yield should be suppressed in deconfined matter. The analysis of the data collected by the NA50 experiment with Pb-Pb collisions at 158 GeV/c per nucleon shows that the J/ psi is anomalously suppressed with respect to the pattern observed in proton-nucleus and light ion reactions. (9 refs).
Energy Technology Data Exchange (ETDEWEB)
Jakobsson, B.; Berg, M.; Carlen, L.; Elmer, R.; Fokin, A.; Ghetti, R.; Martensson, J.; Noren, B.; Oskarsson, A.; Whitlow, H.J. [Department of Physics, University of Lund, Lund (Sweden); Ekstroem, C.; Ericsson, G.; Romanski, J.; van Veldhuizen, E.J.; Westerberg, L. [The Svedberg Laboratory and Department of Neutron Physics, University of Uppsala, Uppsala (Sweden); Julien, J. [Centre d`Etudes Nucleaires, Saclay (France); Skeppstedt, O. [Department of Physics, Chalmers Institute of Technology, Gothenburg (Sweden); Nyboe, K.; Thorsteinsen, T.F.; Amirelmi, S. [Department of Physics, University of Bergen, Bergen (Norway); Guttormsen, M.; Lo/vho/iden, G. [Department of Physics, University of Oslo, Oslo (Norway); Bellini, V.; Palazzolo, F.; Sperduto, M.L. [Istituto Nazionale di Fisica Nucleare/Laboratorio Nazionale del Sud, University of Catania, Catania (Italy); Bondorf, J.P.; Mishustin, I. [Niels Bohr Institute, Copenhagen (Denmark); Avdeichikov, V. [Joint Institute for Nuclear Research, Dubna (Russia); Lozhkin, O.V.; Murin, Y. [V.G. Khlopin Radium Institute, St.Petersburg (Russia)
1997-05-01
Slow ramping of the CELSIUS storage ring has been utilized to measure the yield of charged pions in proton and heavy ion induced collisions with continuously varying beam energy. Boltzmann-Uehling-Uhlenbeck predictions, including Fermi momenta of nucleons in nuclei, follow the general shape of the p-nucleus excitation functions quite well except for a general overestimation of the backward emission. For heavy ion reactions the calculated yield also falls off faster with decreasing beam energy than the data. No statistically significant narrow resonances are observed. {copyright} {ital 1997} {ital The American Physical Society}
Aspects of Coulomb dissociation and interference in peripheral nucleus-nucleus collisions
International Nuclear Information System (INIS)
Nystrand, Joakim; Baltz, Anthony; Klein, Spencer R.
2001-01-01
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
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.
International Nuclear Information System (INIS)
Harris, J.W.
1988-02-01
Experimental results on high energy nucleus-nucleus collisions have become available with the recent experiments at CERN utilizing 200 GeV/n oxygen and sulfur beams. Physics motivations for these experiments are presented: a description of predicted signatures for possible formation of a quark-gluon plasma and physical observables that are expected to provide important information for understanding the dynamics of these collisions. A presentation will be made of some of the first experimental results to emerge from this new field. 28 refs., 9 figs
International Nuclear Information System (INIS)
Noerenberg, W.; Cassing, W.
1984-05-01
The precompound emission of neutrons in central nucleus-nucleus collisions is investigated within the framework of dissipative diabatic dynamics. For 92 Mo + 92 Mo at bombarding energies between 7.5 and 20 MeV/u the differential neutron multiplicities dMsub(n)/dEsub(n) are estimated from the decay of highly excited diabatic single-particle states. The energy spectra have an almost exponential high-energy tail with effective temperatures up to 10 MeV for 20 MeV/u bombarding energy. (orig.)
Dynamics of hadronization in ultra-relativistic nucleus-nucleus collisions
International Nuclear Information System (INIS)
Friman, B.L.
1986-01-01
One of the main problems in the search for quark-gluon plasma in ultra-relativistic nucleus-nucleus collisions is finding a reliable signature for deconfinement. Several signatures have been suggested, e.g., dileptons with a spectrum characteristic of the plasma, an increase in the number of strange particles and effects due to the hadronization of the plasma. In this talk I will describe some recent work on the effects of the hadronization transition in the central rapidity region within the hydrodynamic model of Bjorken, Kajantie and McLerran. (orig.)
Model of homogeneous nucleus. Total and inelastic cross sections of nucleon-nucleus scattering
International Nuclear Information System (INIS)
Ponomarev, L.A.; Smorodinskaya, N.Ya.
1985-01-01
It is shown that the nucleon-nuckleus scattering amplitude at high energy can be easily calculated by generalization of the nucleon-nucleon scattering amplitude and satisfies a simple factorization relation. As distinct from the Glauber model, the suggested approach makes no use of the nucleonic structure of the nucleus and the hadron-nucleus scattering amplitude is not expressed in terms of hadron-nucleon scattering amplitudes. The energy dependence of total and inelastic cross sections is successfully described for a number of nuclei
Percolation Model of Nuclear Multifragmentation in High Energy Nucleus-Nucleus Interactions
International Nuclear Information System (INIS)
Abdel-Waged, Kh.
1994-01-01
A hybrid model based on Reggeon theory inspired model of nuclear distribution, which was successful in explaining the cascading of particles in high energy nucleus-nucleus interactions, and percolation model is proposed. In the framework of this model the yield of the fragment in p + Ag, Au at 350 GeV and C + Ag, Au at 3.6 GeV/nucleon as well as the charge distribution of fragments in Kr, Xe and U interactions with emulsion at ∼ 1 GeV/nucleon is correctly described. 32 refs., 3 figs
Proton rapidity distribution in nucleus-nucleus collisions at high energy
International Nuclear Information System (INIS)
Liu, F.H.
2002-01-01
The proton rapidity distributions in nucleus-nucleus collisions at the Alternating Gradient Synchrotron (AGS) and the Super Proton Synchrotron (SPS) energies are analysed by the revised thermalized cylinder model. The calculated results are compared and found to he in agreement with the experimental data of Si-AI and Si-Pb collisions at 14.6 A GeV/c, Pb-Pb collisions at 158 A GeV/c, and S-S collisions at 200 A GeV/c. (Author)
The isospin dependence of the nucleus-nucleus inelastic cross-section at high energy
International Nuclear Information System (INIS)
Rashdan, M.; Farhan, A.M.; Hassib, E.; Kareem, W. Abdel
2006-01-01
The isospin dependence of the nucleus-nucleus inelastic cross-section at high energy is investigated within the multiple scattering theory. The multiple integrals are evaluated by Monte Carlo method as well as by the optical limit approximation of the Glauber model. Calculations are performed for 14-23 N, 16-24 O and 18-26 F isotopes colliding with carbon target around 1 GeV. It is found that rms radii and the density distributions show a halo structure of 22 N, 23 O and 24 F
Particle production in high energy nucleus--nucleus experiments at Berkeley
International Nuclear Information System (INIS)
Schroeder, L.S.
1976-09-01
A review of high energy nucleus-nucleus experiments performed at the Berkeley Bevalac is presented. Earlier results on projectile and target fragmentation and pion production are briefly summarized. More recent results on Coulomb effects in projectile fragmentation, heavy ion total cross-sections, γ-ray production, and charged particle multiplicities are presented. Also, recent experiments which may shed light on phenomena arising from the central collision of two energetic nuclei, including recent evidence for and against the observation of nuclear shock waves, are reviewed
Alternative dark matter candidates. Axions
International Nuclear Information System (INIS)
Ringwald, Andreas
2017-01-01
The axion is arguably one of the best motivated candidates for dark matter. For a decay constant >or similar 10 9 GeV, axions are dominantly produced non-thermally in the early universe and hence are ''cold'', their velocity dispersion being small enough to fit to large scale structure. Moreover, such a large decay constant ensures the stability at cosmological time scales and its behaviour as a collisionless fluid at cosmological length scales. Here, we review the state of the art of axion dark matter predictions and of experimental efforts to search for axion dark matter in laboratory experiments.
Alternative dark matter candidates. Axions
Energy Technology Data Exchange (ETDEWEB)
Ringwald, Andreas
2017-01-15
The axion is arguably one of the best motivated candidates for dark matter. For a decay constant >or similar 10{sup 9} GeV, axions are dominantly produced non-thermally in the early universe and hence are ''cold'', their velocity dispersion being small enough to fit to large scale structure. Moreover, such a large decay constant ensures the stability at cosmological time scales and its behaviour as a collisionless fluid at cosmological length scales. Here, we review the state of the art of axion dark matter predictions and of experimental efforts to search for axion dark matter in laboratory experiments.
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...
Nuclear structure and neutrino-nucleus interaction
International Nuclear Information System (INIS)
Krmpotic, Francisco
2011-01-01
Recent years have witnessed an intense experimental and theoretical activity oriented towards a better comprehension of neutrino nucleus interaction. While the main motivation for this task is the demand coming from oscillation experiments in their search for a precise determination of neutrino properties, the relevance of neutrino interaction with matter is more wide-ranging. It is imperative for astrophysics, hadronic and nuclear physics, and physics beyond the standard model. The experimental information on neutrino induced reactions is rapidly growing, and the corresponding theoretical description is a challenging proposition, since the energy scales of interest span a vast region, going from few MeV for solar neutrinos, to tens of MeV for the interpretation of experiments with the muon and pion decay at rest and the detection of neutrinos coming from the core collapse of supernova, and to hundreds of MeV or few GeV for the detection of atmospheric neutrinos, and for the neutrino oscillation program of the MiniBooNE experiment. The presence of neutrinos, being chargeless particles, can only be inferred by detecting the secondary particles created in colliding and interacting with the matter. Nuclei are often used as neutrino detectors, and in particular 12 C which is a component of many scintillator detectors. Thus, the interpretation of neutrino data heavily relies on detailed and quantitative knowledge of the features of the neutrino-nucleus interaction. The nuclear structure methods used in the evaluation of the neutrino-nucleus cross section are reviewed. Detailed comparison between the experimental and theoretical results establishes benchmarks needed for verification and/or parameter adjustment of the nuclear models. Having a reliable tool for such calculation is of great importance in a variety of applications, such as the description of the r-process nucleosynthesis. (author)
Iterative h-minima-based marker-controlled watershed for cell nucleus segmentation.
Koyuncu, Can Fahrettin; Akhan, Ece; Ersahin, Tulin; Cetin-Atalay, Rengul; Gunduz-Demir, Cigdem
2016-04-01
Automated microscopy imaging systems facilitate high-throughput screening in molecular cellular biology research. The first step of these systems is cell nucleus segmentation, which has a great impact on the success of the overall system. The marker-controlled watershed is a technique commonly used by the previous studies for nucleus segmentation. These studies define their markers finding regional minima on the intensity/gradient and/or distance transform maps. They typically use the h-minima transform beforehand to suppress noise on these maps. The selection of the h value is critical; unnecessarily small values do not sufficiently suppress the noise, resulting in false and oversegmented markers, and unnecessarily large ones suppress too many pixels, causing missing and undersegmented markers. Because cell nuclei show different characteristics within an image, the same h value may not work to define correct markers for all the nuclei. To address this issue, in this work, we propose a new watershed algorithm that iteratively identifies its markers, considering a set of different h values. In each iteration, the proposed algorithm defines a set of candidates using a particular h value and selects the markers from those candidates provided that they fulfill the size requirement. Working with widefield fluorescence microscopy images, our experiments reveal that the use of multiple h values in our iterative algorithm leads to better segmentation results, compared to its counterparts. © 2016 International Society for Advancement of Cytometry. © 2016 International Society for Advancement of Cytometry.
[The perichromatin compartment of the cell nucleus].
Bogoliubov, D S
2014-01-01
In this review, the data on the structure and composition of the perichromatin compartment, a special border area between the condensed chromatin and the interchromatin space of the cell nucleus, are discussed in the light of the concept of nuclear functions in complex nuclear architectonics. Morphological features, molecular composition and functions of main extrachromosomal structures of the perichromatin compartment, perichromatin fibrils (PFs) and perichromatin granules (PGs) including nuclear stress-bodies (nSBs) that are derivates of the PGs under heat shock, are presented. A special attention was paid to the features of the molecular compositions of PFs and PGs in different cell types and at different physiological conditions.
The basic elementary particles as martensitic nucleus
International Nuclear Information System (INIS)
Aguinaco-Bravo, V. J.; Onoro, J.
1999-01-01
The martensitic transformation is a diffusional structural change that produces an important modification of the microstructure and properties of materials. In this paper we propose how the martensitic phase is nucleated from a basic elementary particle (bep). The bep is formed in several stages. Vacancies, divacancies, etc. are formed at high temperature, which collapse into prismatic dislocation loops during the cooling process. We define a bep as a dislocation loop reaching a critical radius and fulfilling certain elastic energy conditions. A martensitic nucleus is a bep that coincides crystallographically with the habit plane of the matrix. (Author) 16 refs
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
From the nucleus discovery to DWBA
International Nuclear Information System (INIS)
Fernandez, B.
2007-01-01
The author presents a brief review of the main events in the field of nuclear reactions that are acknowledged as milestones because of their importance due to either experimental setting or physical interpretation. It is shown that the pace of discoveries has been strongly dependent on the technical progress in detection means at the beginning of nuclear physics and now is linked to the development of simulation means. The discovery of the neutron, the development of the Geiger counter, the theory of the compound nucleus or the first direct reactions are among these milestones
Reliability of MRI findings in candidates for lumbar disc prosthesis
International Nuclear Information System (INIS)
Berg, Linda; Espeland, Ansgar; Neckelmann, Gesche; Gjertsen, Oeivind; Hellum, Christian; Johnsen, Lars G.; Eide, Geir E.
2012-01-01
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.)
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.)
11 CFR 100.154 - Candidate debates.
2010-01-01
... 11 Federal Elections 1 2010-01-01 2010-01-01 false Candidate debates. 100.154 Section 100.154 Federal Elections FEDERAL ELECTION COMMISSION GENERAL SCOPE AND DEFINITIONS (2 U.S.C. 431) Exceptions to Expenditures § 100.154 Candidate debates. Funds used to defray costs incurred in staging candidate debates in...
11 CFR 100.92 - Candidate debates.
2010-01-01
... 11 Federal Elections 1 2010-01-01 2010-01-01 false Candidate debates. 100.92 Section 100.92 Federal Elections FEDERAL ELECTION COMMISSION GENERAL SCOPE AND DEFINITIONS (2 U.S.C. 431) Exceptions to Contributions § 100.92 Candidate debates. Funds provided to defray costs incurred in staging candidate debates...
Acosta-Galvan, Guadalupe; Yi, Chun-Xia; van der Vliet, Jan; Jhamandas, Jack H.; Panula, Pertti; Angeles-Castellanos, Manuel; del Carmen Basualdo, María; Escobar, Carolina; Buijs, Ruud M.
2011-01-01
Food anticipatory behavior (FAA) is induced by limiting access to food for a few hours daily. Animals anticipate this scheduled meal event even without the suprachiasmatic nucleus (SCN), the biological clock. Consequently, a food-entrained oscillator has been proposed to be responsible for meal time
Mechanism of energy release from nucleus-target in hadron-nucleus collision
International Nuclear Information System (INIS)
Strugalski, Z.; Strugalska-Gola, E.
2000-01-01
The collisions of hadrons (protons, mesons) with 131 Xe nucleus and arising light nuclear fragments as nuclear refraction products have been observed in bubble chamber. Mechanism of energy release during these collisions has been discussed. The quantitative calculations has proved that this phenomena can be treated as potential energy source with use of many different target materials
Study of η-nucleus interaction through the formation of η-nucleus ...
Indian Academy of Sciences (India)
Abstract. The question of possible existence of η-mesic nuclei is quite intriguing. An- swer to this question will deeply enrich our understanding of η-nucleus interaction which is not so well-understood. We review the experimental efforts for the search of η-mesic nuclei and describe the physics motivation behind it.
High energy cosmic ray events of ultra-relativistic nucleus-nucleus collisions
International Nuclear Information System (INIS)
Burnett, T.H.; Dake, S.; Derricson, J.H.; Fountain, W.; Fuki, M.; Gregory, J.C.; Hayashi, T.; Hayashi, T.; Holynski, R.; Iwai, J.; Jones, W.V.; Jurak, A.; Lord, J.J.; Meegan, C.A.; Miyamura, O.; Oda, H.; Ogata, T.; Parnell, T.A.; Roberts, E.; Saito, T.; Strauss, S.; Tabuki, T.; Takahashi, Y.; Tominaga, T.; Watts, J.W.; Wilczynska, B.; Wilkes, R.J.; Wolter, W.; Bosiek, B.
1985-01-01
Japanese American Cooperative Emulsion Experiment (JACEE) has been measuring ultrarelativistic comic ray nucleus and sampling the events in the energy regions both 10 to 100 GeV/A and above TeV/A by balloon emulsion chamber since 1979. In this report main results obtained up to now will be described. (orig./HSI)
International Nuclear Information System (INIS)
D'Enterria, D.G.
2000-05-01
The thermodynamical properties of nuclear matter at moderate temperatures and densities, in the vicinity of the predicted nuclear liquid-gas phase transition, are studied using as experimental probe the hard-photons (E γ > 30 MeV) emitted in nucleus-nucleus collisions. Photon and charged-particle production in four different heavy-ion reactions (Ar 36 + Au 197 , Ag 107 , Ni 58 , C 12 at 60 A*MeV) is measured exclusively and inclusively coupling the TAPS photon spectrometer with two charged-particle and intermediate-mass-fragment detectors covering nearly 4π. We confirm that Bremsstrahlung emission in first-chance (off-equilibrium) proton-neutron collisions (pnγ) is the dominant origin of hard photons. We also firmly establish the existence of a thermal radiation component emitted in second-chance proton-neutron collisions. This thermal Bremsstrahlung emission takes place in semi-central and central nucleus-nucleus reactions involving heavy targets. We exploit this observation i) to demonstrate that thermal equilibrium is reached during the reaction, ii) to establish a new thermometer of nuclear matter based on Bremsstrahlung photons, iii) to derive the thermodynamical properties of the excited nuclear sources and, in particular, to establish a 'caloric curve' (temperature versus excitation energy), and iv) to assess the time-scales of the nuclear break-up process. (author)
Hadron-nucleus interactions with a small target-nucleus excitation
International Nuclear Information System (INIS)
Anzon, Z.V.; Chasnikov, I.Ya.; Shakhova, Ts.I.
1981-01-01
Hadron inelastic interactions in nuclear emulsion with a small target-nucleus excitation in the energy range 7.5-200 GeV have been studied. Possible reasons for the differences in production cross-section for events with even and odd number of S-particles are analysed
Scofield, M D; Heinsbroek, J A; Gipson, C D; Kupchik, Y M; Spencer, S; Smith, A C W; Roberts-Wolfe, D; Kalivas, P W
2016-07-01
The nucleus accumbens is a major input structure of the basal ganglia and integrates information from cortical and limbic structures to mediate goal-directed behaviors. Chronic exposure to several classes of drugs of abuse disrupts plasticity in this region, allowing drug-associated cues to engender a pathologic motivation for drug seeking. A number of alterations in glutamatergic transmission occur within the nucleus accumbens after withdrawal from chronic drug exposure. These drug-induced neuroadaptations serve as the molecular basis for relapse vulnerability. In this review, we focus on the role that glutamate signal transduction in the nucleus accumbens plays in addiction-related behaviors. First, we explore the nucleus accumbens, including the cell types and neuronal populations present as well as afferent and efferent connections. Next we discuss rodent models of addiction and assess the viability of these models for testing candidate pharmacotherapies for the prevention of relapse. Then we provide a review of the literature describing how synaptic plasticity in the accumbens is altered after exposure to drugs of abuse and withdrawal and also how pharmacological manipulation of glutamate systems in the accumbens can inhibit drug seeking in the laboratory setting. Finally, we examine results from clinical trials in which pharmacotherapies designed to manipulate glutamate systems have been effective in treating relapse in human patients. Further elucidation of how drugs of abuse alter glutamatergic plasticity within the accumbens will be necessary for the development of new therapeutics for the treatment of addiction across all classes of addictive substances. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.
Prestress mediates force propagation into the nucleus
International Nuclear Information System (INIS)
Hu Shaohua; Chen Jianxin; Butler, James P.; Wang Ning
2005-01-01
Several reports show that the nucleus is 10 times stiffer than the cytoplasm. Hence, it is not clear if intra-nuclear structures can be directly deformed by a load of physiologic magnitudes. If a physiologic load could not directly deform intra-nuclear structures, then signaling inside the nucleus would occur only via the mechanisms of diffusion or translocation. Using a synchronous detection approach, we quantified displacements of nucleolar structures in cultured airway smooth muscle cells in response to a localized physiologic load (∼0.4 μm surface deformation) via integrin receptors. The nucleolus exhibited significant displacements. Nucleolar structures also exhibited significant deformation, with the dominant strain being the bulk strain. Increasing the pre-existing tensile stress (prestress) in the cytoskeleton significantly increased the stress propagation efficiency to the nucleolus (defined as nucleolus displacement per surface deformation) whereas decreasing the prestress significantly lowered the stress propagation efficiency to the nucleolus. Abolishing the stress fibers/actin bundles by plating the cells on poly-L-lysine-coated dishes dramatically inhibited stress propagation to the nucleolus. These results demonstrate that the prestress in the cytoskeleton is crucial in mediating stress propagation to the nucleolus, with implications for direct mechanical regulation of nuclear activities and functions
International Nuclear Information System (INIS)
Zheng Wanhui; Gu Jiahui; Zhu Jiabi; Wang Gongqing
1988-01-01
The decay of 61 Cu nucleus has been investigated with Ge(Li) and H p Ge detector, semiconductor electron spectrometer and Ge(Li)-NaI γ-γ coincidence spectrometer. 35 γrays from 12 excited levels have been found. The single and coincidence spectra show that 545 keV, 1019keV γ fays and 1019keV energy level are wrong which appear in the 61 Cu decay scheme carried in > (the 7th edition 1978). the halflife time of 61 Cu nucleus and the internal conversion coefficient for 67 keV γ-transition are found to be T 1/2 =207.7±1.6min and α=0.12±0.01 respectively and then a decay scheme is proposed. In this paper more attention ia paid to discussing the energy levels of 1014, 1019, and 1997 keV as well as some weak γ rays
International Nuclear Information System (INIS)
Abdel-Hafiez, A.; Chernyavski, M.M.; Orlova, G.I.; Gulamov, K.G.; Navotny, V.SH.; Uzhinskii, V.V.
2000-01-01
Experimental data on multi-fragmentation of residual krypton nuclei created in the interactions of the krypton nuclei with photoemulsion nuclei ut energy of 0.9 GeV per nucleon are presented in a comparison with the analogous data on fragmentation of gold residual nuclei at the energy of 10.7 GeV/nucleon. It is shown for the first time that there are two regimes of nuclear multifragmentation: the former is when less than one-half of nucleons of projectile nucleus are knocked out, the later is when more than one-half of nucleons are knocked out. Residual nuclei with closed masses created at different reactions are fragmenting practically simultaneously when more than one-half of nucleons of original nuclei are knocked out. The evidence of existence of a radial flow of the spectator fragment at the decay of residual krypton nuclei is found
[Obesity studies in candidate genes].
Ochoa, María del Carmen; Martí, Amelia; Martínez, J Alfredo
2004-04-17
There are more than 430 chromosomic regions with gene variants involved in body weight regulation and obesity development. Polymorphisms in genes related to energy expenditure--uncoupling proteins (UCPs), related to adipogenesis and insulin resistance--hormone-sensitive lipase (HLS), peroxisome proliferator-activated receptor gamma (PPAR gamma), beta adrenergic receptors (ADRB2,3), and alfa tumor necrosis factor (TNF-alpha), and related to food intake--ghrelin (GHRL)--appear to be associated with obesity phenotypes. Obesity risk depends on two factors: a) genetic variants in candidate genes, and b) biographical exposure to environmental risk factors. It is necessary to perform new studies, with appropriate control groups and designs, in order to reach relevant conclusions with regard to gene/environmental (diet, lifestyle) interactions.
Nuclear energy release in hadron-nucleus collisions
International Nuclear Information System (INIS)
Strugalski, Z.; Strugalska-Gola, E.
1998-01-01
Energy release process in nuclear reactions induced by fast hadrons in hadron-nucleus collisions is discussed. Some portion of the internal nuclear energy is released when the locally damaged in a collision, and instable therefore, residual target nucleus transits itself into light nuclear fragments (nucleons, D, T) and a stable lighter final nucleus or some number of stable lighter nuclei. It is not excluded that in some of the collisions the induced intranuclear nuclear reactions may be energy overcompensating. Corresponding reconnaissance should be made - in analysing the nuclear reactions induced in hadron-nucleus collisions
Nucleus and nucleus-cytoskeleton connections in 3D cell migration
Energy Technology Data Exchange (ETDEWEB)
Liu, Lingling, E-mail: liulingling2012@163.com; Luo, Qing, E-mail: qing.luo@cqu.edu.cn; Sun, Jinghui, E-mail: sunjhemail@163.com; Song, Guanbin, E-mail: song@cqu.edu.cn
2016-10-15
Cell migration plays an important role in many physiological and pathological settings, ranging from embryonic development to cancer metastasis. Currently, accumulating data suggest that cells migrating in three-dimensional (3D) environments show well-defined differences compared to their well-established two-dimensional (2D) counterparts. During 3D migration, the cell body and nucleus must deform to allow cellular passage through the available spaces, and the deformability of the relatively rigid nucleus may constitute a limiting step. Here, we highlight the key evidence regarding the role of the nuclear mechanics in 3D migration, including the molecular components that govern the stiffness of the nucleus and review how the nuclear dynamics are connected to and controlled by cytoskeleton-based migration machinery. Intriguingly, nuclear movement must be coordinated with the cytoskeletal dynamics at the leading and trailing edges, which in turn impact the cytoplasmic dynamics that affect the migration efficiency. Thus, we suggest that alterations in the nuclear structure may facilitate cellular reorganizations that are necessary for efficient migration. - Graphical abstract: Schematic representations of a cell migrating on a 2D substrate and a cell migrating in a 3D extracellular matrix environment. (A) Nucleus-cytoskeleton connections are essential to 3D migration. Mechanical signals are transduced by integrins at the cell surface and channeled to cytoskeletal proteins, which generates prestress. The nucleus-cytoskeleton connections can either act as a stable skeleton to anchor the nuclei or provide active force to move the nuclei. The LINC complex is responsible for the nucleo-cytoskeletal coupling. Nesprins connect the cytoskeletal proteins to the inner nuclear membrane proteins SUN1 and SUN2. The SUN proteins connect to the lamins that form the lamina, which attaches to the chromatin. This physical connectivity transmits the mechanical signals from receptors at
Nucleus and nucleus-cytoskeleton connections in 3D cell migration
International Nuclear Information System (INIS)
Liu, Lingling; Luo, Qing; Sun, Jinghui; Song, Guanbin
2016-01-01
Cell migration plays an important role in many physiological and pathological settings, ranging from embryonic development to cancer metastasis. Currently, accumulating data suggest that cells migrating in three-dimensional (3D) environments show well-defined differences compared to their well-established two-dimensional (2D) counterparts. During 3D migration, the cell body and nucleus must deform to allow cellular passage through the available spaces, and the deformability of the relatively rigid nucleus may constitute a limiting step. Here, we highlight the key evidence regarding the role of the nuclear mechanics in 3D migration, including the molecular components that govern the stiffness of the nucleus and review how the nuclear dynamics are connected to and controlled by cytoskeleton-based migration machinery. Intriguingly, nuclear movement must be coordinated with the cytoskeletal dynamics at the leading and trailing edges, which in turn impact the cytoplasmic dynamics that affect the migration efficiency. Thus, we suggest that alterations in the nuclear structure may facilitate cellular reorganizations that are necessary for efficient migration. - Graphical abstract: Schematic representations of a cell migrating on a 2D substrate and a cell migrating in a 3D extracellular matrix environment. (A) Nucleus-cytoskeleton connections are essential to 3D migration. Mechanical signals are transduced by integrins at the cell surface and channeled to cytoskeletal proteins, which generates prestress. The nucleus-cytoskeleton connections can either act as a stable skeleton to anchor the nuclei or provide active force to move the nuclei. The LINC complex is responsible for the nucleo-cytoskeletal coupling. Nesprins connect the cytoskeletal proteins to the inner nuclear membrane proteins SUN1 and SUN2. The SUN proteins connect to the lamins that form the lamina, which attaches to the chromatin. This physical connectivity transmits the mechanical signals from receptors at
Spectroscopic Studies of the Nucleus GOLD-195
Fischer, Susan Marie
The nucleus ^{195}Au has been studied via in-beam gamma -ray and electron spectroscopy with the reactions ^{196}Pt(p,2n)^ {195}Au at beam energies of 12 and 16 MeV, and the reaction ^{rm nat }Ir(alpha,2n) ^{195}Au at a beam energy of 26 MeV. All experiments were performed at the University of Notre Dame tandem accelerator facility and utilized elements of the University of Pittsburgh multi-detector gamma-array and ICEBall mini-orange electron spectrometer. Fifty-five new transitions and thirty-six new energy levels have been observed. The U(6/4) supersymmetric algebra has been proposed to provide a simultaneous description for the positive parity states of the pair of nuclei ^{194 }Pt and ^{195}Au. The observed energy spectra for these nuclei show satisfactory agreement with the U(6/4) predicted spectra. The collective properties including relative B(E2) values for the Pt and Au nuclei in this mass region are also consistent with theoretical predictions. However, the measured E2/M1 mixing ratios for transitions in ^{195} Au indicate that the single particle description for the odd-A nucleus is incomplete. The new data for ^{195}Au is further combined with the existing data for ^{194} Pt and ^{195}Pt within the context of the larger U_{ nu}(6/12) otimes U_{pi}(6/4) supersymmetry. A consistent fit to the energy eigenvalue equation is obtained and a modified prediction for the negative parity states in the odd-odd nucleus ^{196} Au is made. Thus, the proposal of an underlying supersymmetry for the quartet of nuclei ^ {194}Pt-^{195} Pt-^{195}Au- ^{196}Au also appears valid. New transitions and levels involved in the negative parity h_{11/2} decoupled band in ^{195}Au have also been observed. The band appears to be much more fragmented at high spins than the analogous structures in the lighter odd-A Au nuclei, but it is unclear what the source of this difference is. It is, however, proposed that a consistent description for both the positive and negative parity
Dirac phenomenology and hyperon-nucleus interactions
Energy Technology Data Exchange (ETDEWEB)
Mares, J; Jennings, B K [TRIUMF, Vancouver, British Columbia (Canada); Cooper, E D [Fraser Valley Univ. College, Chilliwack, British Columbia (Canada). Dept. of Physics
1993-05-01
We discuss various aspects of hyperon-nucleus interactions in the relativistic mean field theory. First, characteristics of {Lambda}, {Sigma} and {identical_to} 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{omega}y. Second, optical potentials for {Lambda} and {Sigma} scattering off nuclei are developed based on a global nucleon-nucleon Dirac optical potential and SU(3) symmetry. The tensor coupling has a large effect on the predictions for the analyzing power. Third, the Dirac approach is used in the calculations of the non-mesonic decay of {Lambda} hypernuclei. The large discrepancy between the decay rates and data suggests the need for additional meson exchanges. (authors). 62 refs.,7 figs., 6 tabs.
Delta-nucleus dynamics: proceedings of symposium
International Nuclear Information System (INIS)
Lee, T.S.H.; Geesaman, D.F.; Schiffer, J.P.
1983-10-01
The appreciation of the role in nuclear physics of the first excited state of the nucleon, the delta Δ(1232), has grown rapidly in the past decade. The delta resonance dominates nuclear reactions induced by intermediate energy pions, nucleons, and electromagnetic probes. It is also the most important non-nucleonic degree of freedom needed to resolve many fundamental problems encountered in the study of low-energy nuclear phenomena. Clearly, a new phase of nuclear physics has emerged and conventional thinking must be extended to account for this new dimension of nuclear dynamics. The most challenging problem we are facing is how a unified theory can be developed to describe Δ-nucleus dynamics at all energies. In exploring this new direction, it is important to have direct discussions among researchers with different viewpoints. Separate entries were prepared for the 49 papers presented
Muonic atom-light nucleus interaction
International Nuclear Information System (INIS)
Kuz'michev, V.E.; Peresypkin, V.V.; Efetov, A.V.
1991-01-01
The effective potential of the interaction between light nucleus and two-particle atom at distances greater than its Bohr radius is obtained in the analytic form on the basis of a correct account of three Coulomb particle problem. Features of the interaction between p, t, 4 He, 7 Be nuclei and mesonic atoms μp, μt, μ 4 He and μ 7 Be, that arising from the differences in masses and charges of interacting particles, are studied. The corresponding potentials in the pre-threshold energy range are given. The coefficients of the symptotic formula for the effective are calculated in adiabatic approximation and with regard for the main off-shell corrections. 16 refs.; 4 figs
High energy hadron-nucleus collision
International Nuclear Information System (INIS)
Takagi, Fujio
1983-02-01
This is a lecture note concerning high energy hadron-nucleus collision. The lecture gives the inelastic total cross section and the Glanber approximate multiple scattering formula at first. The mechanism of nuclear spallation is described in a cylindrical image. The multiplicity, the one particle distribution and the time-space structure of particle production are discussed. Various models are presented. The attenuation of forward particles and the structure of hadrons are discussed for each model. The atomic number (A) dependence of the production of large transverse momentum particles and jet, and the A dependence of charged multiplicity are presented. The backward production of particles and many body correlation are discussed. Lepton pair production and the initial interaction of constituents, collective interaction, multi quark state and phase transition are described. (Kato, T.)
Parity violation in the compound nucleus
International Nuclear Information System (INIS)
Bowman, J.D.; Frankle, C.M.; Green, A.A.
1994-01-01
The status of parity violation in the compound nucleus is reviewed. The results of previous experimental results obtained by scattering polarized epithermal neutrons from heavy nuclei in the 3-p and 4-p p-wave strength function peaks are presented. Experimental techniques are presented. The extraction of the mean squared matrix element of the parity-violating interaction, M 2 , between compound-nuclear levels and the relationship of M 2 to the coupling strengths in the meson exchange weak nucleon-nucleon potential are discussed. The tendency of measured asymmetries to have a common sign and theoretical implications are discussed. New experimental results are presented that show that the common sign phenomenon is not universal, as theoretical models developed up to now would predict
An enlarged superfluid model of atomic nucleus
International Nuclear Information System (INIS)
Dumitrescu, O.; Horoi, M.
1989-01-01
The well known superfluid model (or quasiparticle phonon nuclear model (QPNM)) of atomic nucleus is enlarged by including an adequate four-nucleon effective interaction in addition to the pairing and long-range effective residual interactions. New experimental data can be explained without affecting those observables already described by the QPNM and in addition new features can be enumerated: 1) superfluidities of the neutron and proton systems may be generated by one another; 2) the phase structure is enriched by a new superfluid phase dominated by alpha-type correlations (ATC) and 3) superfluid isomers and their bands of elementary excitations are predicted. Unusual large two-nucleon and alpha transfer reactions cross sections as well as some unusual large alpha decay widths can be explained. (author). 46 refs, 3 figs, 2 tabs
Delta-nucleus dynamics: proceedings of symposium
Energy Technology Data Exchange (ETDEWEB)
Lee, T.S.H.; Geesaman, D.F.; Schiffer, J.P. (eds.)
1983-10-01
The appreciation of the role in nuclear physics of the first excited state of the nucleon, the delta ..delta..(1232), has grown rapidly in the past decade. The delta resonance dominates nuclear reactions induced by intermediate energy pions, nucleons, and electromagnetic probes. It is also the most important non-nucleonic degree of freedom needed to resolve many fundamental problems encountered in the study of low-energy nuclear phenomena. Clearly, a new phase of nuclear physics has emerged and conventional thinking must be extended to account for this new dimension of nuclear dynamics. The most challenging problem we are facing is how a unified theory can be developed to describe ..delta..-nucleus dynamics at all energies. In exploring this new direction, it is important to have direct discussions among researchers with different viewpoints. Separate entries were prepared for the 49 papers presented. (WHK)
Heavy nucleus resonant absorption calculation benchmarks
International Nuclear Information System (INIS)
Tellier, H.; Coste, H.; Raepsaet, C.; Van der Gucht, C.
1993-01-01
The calculation of the space and energy dependence of the heavy nucleus resonant absorption in a heterogeneous lattice is one of the hardest tasks in reactor physics. Because of the computer time and memory needed, it is impossible to represent finely the cross-section behavior in the resonance energy range for everyday computations. Consequently, reactor physicists use a simplified formalism, the self-shielding formalism. As no clean and detailed experimental results are available to validate the self-shielding calculations, Monte Carlo computations are used as a reference. These results, which were obtained with the TRIPOLI continuous-energy Monte Carlo code, constitute a set of numerical benchmarks than can be used to evaluate the accuracy of the techniques or formalisms that are included in any reactor physics codes. Examples of such evaluations, for the new assembly code APOLLO2 and the slowing-down code SECOL, are given for cases of 238 U and 232 Th fuel elements
The nucleus accumbens and learning and memory.
Setlow, B
1997-09-01
Recent research on the nucleus accumbens (NA) indicates that this brain region is involved in learning and memory processes in a way that is separable from its other well-known roles in behavior, such as motivation, reward, and locomotor activity. These findings have suggested that 1) the NA may be involved in declarative, or hippocampal formation-dependent learning and memory, and not in several other non-declarative forms of learning and memory, and 2) the NA may be selectively involved in certain stages of learning and memory. These characteristics suggest that the NA may be part of a larger striatal system which subserves acquisition and consolidation, but is not a site of long-term storage, of different forms of learning and memory.
Observation of the antimatter helium-4 nucleus.
2011-05-19
High-energy nuclear collisions create an energy density similar to that of the Universe microseconds after the Big Bang; in both cases, matter and antimatter are formed with comparable abundance. However, the relatively short-lived expansion in nuclear collisions allows antimatter to decouple quickly from matter, and avoid annihilation. Thus, a high-energy accelerator of heavy nuclei provides an efficient means of producing and studying antimatter. The antimatter helium-4 nucleus (4He), also known as the anti-α (α), consists of two antiprotons and two antineutrons (baryon number B = -4). It has not been observed previously, although the α-particle was identified a century ago by Rutherford and is present in cosmic radiation at the ten per cent level. Antimatter nuclei with B antimatter nuclei and a benchmark for possible future observations of 4He in cosmic radiation.
Dynamical and statistical aspects in nucleus-nucleus collisions around the Fermi energy
Energy Technology Data Exchange (ETDEWEB)
Tamain, B.; Bocage, F.; Bougault, R.; Brou, R. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; Assenard, M. [Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees; Auger, G.; Benlliure, J. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Bacri, C.O.; Borderie, B. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Bisquer, E. [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire] [and others
1997-12-31
Nucleus-nucleus collisions at low incident energy are mainly governed by statistical dissipative processes, fusion and deep inelastic reactions being the most important ones. Conversely, in the relativistic energy regime, dynamical effects play a dominant role and one should apply a participant-spectator picture in order to understand the data. In between, the intermediate energy region is a transition one in which it is necessary to disentangle dynamics from statistical effects. Moreover, the Fermi energy region corresponds to available energies comparable with nuclear binding energies and one may except to observe phase transition effects. Experiments performed recently with 4{pi} devices have given quite new data and a much better insight into involved mechanisms and hot nuclear matter properties. INDRA data related to reaction mechanisms and multifragmentation are presented. (author) 53 refs.
Dynamical and statistical aspects in nucleus-nucleus collisions around the Fermi energy
International Nuclear Information System (INIS)
Tamain, B.; Bocage, F.; Bougault, R.; Brou, R.; Bacri, C.O.; Borderie, B.; Bisquer, E.
1997-01-01
Nucleus-nucleus collisions at low incident energy are mainly governed by statistical dissipative processes, fusion and deep inelastic reactions being the most important ones. Conversely, in the relativistic energy regime, dynamical effects play a dominant role and one should apply a participant-spectator picture in order to understand the data. In between, the intermediate energy region is a transition one in which it is necessary to disentangle dynamics from statistical effects. Moreover, the Fermi energy region corresponds to available energies comparable with nuclear binding energies and one may except to observe phase transition effects. Experiments performed recently with 4π devices have given quite new data and a much better insight into involved mechanisms and hot nuclear matter properties. INDRA data related to reaction mechanisms and multifragmentation are presented. (author)
The calculation of nucleus-nucleus interaction cross sections at high energy in the Glauber approach
International Nuclear Information System (INIS)
Gal'perin, A.G.; Uzhinskij, V.V.
1994-01-01
Total, inelastic and elastic cross sections of nucleus-nucleus (AA)-interactions at high energy (HE) are calculated on the base of Glauber approach. The calculation scheme is realized as a set of routines. The statistical average method is used in calculations. Program runs in an interactive regime. User is prompted about charge and mass numbers of nuclei and NN-interaction characters at the energy he is interested in: total cross section, the slope parameter of differential cross section of elastic scattering and ratio of real part to imaginary part of elastic scattering amplitude at zero momentum transfer. These data can be extracted from proper compilations. Results of calculations are displayed and are written on user defined output file. The program runs on PC. 21 refs., 1 tab
Nucleus-Nucleus Scattering in the High-Energy Approximation and the Optical Folding Potential
Lukyanov, V K; Lukyanov, K V
2004-01-01
For the nucleus-nucleus scattering, the complex potential is obtained which corresponds to the eikonal phase of an optical limit of the Glauber-Sitenko high-energy approximation. The potential does not include free parameters, its real and imaginary parts depend on energy and are determined by the reported data on the nuclear density distributions and nucleon-nucleon scattering amplitude. Alternatively, for the real part, the folding potential can be utilized which includes the effective NN-forces and the exchange term, as well. As a result, the microscopic optical potential is constructed where contributions of the calculated real and imaginary parts are formed by fitting the two respective factors. An efficient of the approach is confirmed by agreements of calculations with the experimental data on elastic scattering cross-sections.
International Nuclear Information System (INIS)
Schuermann, B.; Malfliet, R.; Mies, S.; Zwermann, W.
1984-01-01
Foundations of the transport theory for studying K + , K - , π - and light fragment production in nucleus-nucleus interactions at high energies are given. Inclusive production of protons, K + and π - in the Ne+NaF reaction at 400 MeV and 21 GeV/nucleon is consdered, their differential cross sections are caculated. Differential cross sections of K - and π - production in Si+Si → K + +X and Ne+NaF → π - +X reactions at the energy of 2.1 GeV/nucleon, their energy dependence are estimated. Comparison of the calculated and experimental data is graphically presented. The model of the transport theory is shown to successfully reproduce inclusive spectra of different particles (p, d, π, K + , K - ) in a wide energy range of incident particles (from 400 MeV to 2 GeV/nucleon). This approach can be generalized for lower energies by generating a mean nuclear potentiasl field
On the geometric nature of high energy nucleus-nucleus reaction cross sections
International Nuclear Information System (INIS)
Townsend, L.W.; Wilson, J.W.; Bidasaria, H.B.
1982-01-01
Within the context of a high energy double-folding optical potential approximation to the exact nucleus-nucleus multiple-scattering series, eikonal scattering theory is used to investigate the validity of geometric reaction cross sections in relativistic heavy ion collisions. The potential used includes a finite range interaction and nuclear single-particle densities extracted from nuclear charge distributions by unfolding the proton charge distribution. Pauli correlation effects are also included in an approximate way. The sensitivity of the predictions to be assumed interaction, Pauli correlation approximation, and nuclear density distributions is investigated. These results are in agreement with early predictions concerning the geometric nature of relativistic heavy ion collisions and in disagreement with a recent analysis, utilizing the zero range approximation, which suggested otherwise. Reasons for the lack of agreement between the analyses are also presented. Finally, approximate applicability for geometric reaction cross sections are determined
Energy Technology Data Exchange (ETDEWEB)
Andronic, Anton
2014-07-15
This thesis is heterogeneous, comprising experimental papers at low energies (SIS-18 at GSI) and at the LHC, papers on phenomenology of high-energy nucleus-nucleus collisions, and papers on detectors. The overview covers the experimental papers and those on phenomenology. I have chosen to write it in a general manner, intended to be accessible to non-experts. It emphasizes recent measurements and their understanding at the LHC. The detector papers, which address many principle aspects of gaseous detectors, are summarized and placed in context in the review I co-wrote and which closes the stack. The detector papers included here are the outcome of an R and D program for the Transition Radiation Detector of ALICE.
Study of Strange and Multistrange Particles in Ultrarelativistic Nucleus-Nucleus Collisions
Vande vyvre, P; Feofilov, G; Snoeys, W; Hetland, K F; Campbell, M; Klempt, W
2002-01-01
% NA57\\\\ \\\\ The goal of the experiment is to study the production of strange and multi-strange particles in nucleus-nucleus collisions. This study was initiated at the OMEGA spectrometer, where three ion experiments have been performed: WA85 (S-W and p-W collisions at 200 A GeV/c), WA94 (S-S and p-S collisions at 200 A GeV/c) and WA97 (Pb-Pb, p-Pb and p-Be collisions at 160 A GeV/c).\\\\ \\\\ The experiment aims at extending the scope of WA97 by:\\\\ \\\\ - investigating the beam energy dependence of the enhancements of multi-strange particle production reported by the previous experiments, and by\\\\ \\\\\\\\ \\\\- measuring the yields of strange and multi-strange particles over an extended centrality range compared with the previous experiments.\\\\ \\\\ The apparatus consists mainly of silicon pixel detector planes.
Dissipation and fluctuation of the relative momentum in nucleus-nucleus collisions
International Nuclear Information System (INIS)
Feldmeier, H.; Spangenberger, H.
1984-07-01
The dissipation of the relative momentum in nucleus-nucleus collisions is treated in terms of a Langevin equation with a fluctuating force. Equations of motion for first and second moments of the macroscopic variables are derived directly from the Langevin equation. The properties of the fluctuating force which results from random particle exchange are investigated in detail. Drift and diffusion coefficients are calculated microscopically and analytical expressions are given which can be used in any trajectory calculation. An important feature of the model is that the Einstein relation between dissipation and fluctuation turns out to be only a limiting case of a more general expression which included nonthermal fluctuations. By treating the two nuclei as intrinsically equilibrated but not in thermal equilibrium with respect to each other several important aspects of the dissipative behaviour, seen in heavy ion collisions with final energies above the Coloumb barrier, can be understood. (orig.)
Transverse and radial flow in intermediate energy nucleus-nucleus collisions
International Nuclear Information System (INIS)
Vestfall, D. Gary
1997-01-01
We have studied transverse and radial flow in nucleus-nucleus collisions ranging in energy from 15 to 155 MeV/nucleon. We have measured the impact parameter dependence of the balance energy for Ar + Sc and compared the results with Quantum Molecular Dynamics calculations with and without momentum dependence. We have shown that transverse flow and the balance energy dependence on the isospin of the system using the systems 58 Fe + 58 Fe, 58 Ni + 58 Ni, and 58 Mn + 58 Fe. These results are compared with Boltzmann-Uehling-Uehlenbeck calculations incorporating isospin-dependence. We have measured radial flow for Ar + Sc and find that about 50% of the observed energy is related to radial flow. (author)
International Nuclear Information System (INIS)
Andronic, Anton
2014-07-01
This thesis is heterogeneous, comprising experimental papers at low energies (SIS-18 at GSI) and at the LHC, papers on phenomenology of high-energy nucleus-nucleus collisions, and papers on detectors. The overview covers the experimental papers and those on phenomenology. I have chosen to write it in a general manner, intended to be accessible to non-experts. It emphasizes recent measurements and their understanding at the LHC. The detector papers, which address many principle aspects of gaseous detectors, are summarized and placed in context in the review I co-wrote and which closes the stack. The detector papers included here are the outcome of an R and D program for the Transition Radiation Detector of ALICE.
Calculations of nucleus-nucleus microscopic optical potentials at intermediate energies
International Nuclear Information System (INIS)
Hanna, K.M.; Kuhtina, I.N.; Lukyanov, K.V.; Lukyanov, V.K.; Zemlyanaya, E.V.; Slowinski, B.
2006-01-01
Three types of microscopic nucleus-nucleus optical potentials are constructed using three patterns for their real and imaginary parts. Two of these patterns are the real V H and imaginary W H parts of the potential which reproduces the high-energy amplitude of scattering in the microscopic Glauber-Sitenko theory. Another template VDF is calculated within the standard double-folding model with the exchange term included. For either of the three tested potentials, the contribution of real and imaginary patterns is adjusted by introducing two fitted factors. Correspondingly, using numerical code ECIS, the elastic differential cross-sections were fitted to the experimental data on scattering of the 16,17 O heavy-ions at about hundred Mev/nucleon on various target-nuclei. The relativization effect is also included. The tables of the obtained factors which renormalize the strengths of the real and (or) imaginary parts of the calculated microscopic potentials are given
Method of a fast selection of inelastic nucleus-nucleus collisions for the CMS experiment
International Nuclear Information System (INIS)
Krasnov, V.A.; Malakhov, A.I.; Savina, M.V.; Shmatov, S.V.; Zarubin, P.I.
1998-01-01
On the basis of the HIJING generator simulation of heavy ion collisions at ultrarelativistic energy scale, a method of a fast selection of inelastic nucleus-nucleus interactions is proposed for the CMS experiment at LHC. The basic idea is to use the time coincidence of signals with resolution better than 1 ns from the two very forward calorimeter arms covering the acceptance 3<|η|<5. The method efficiency is investigated by variation of energy thresholds in the calorimeters for different colliding ion species, namely, PbPb, NbNb, CaCa, OO, pPb, pCa, pp. It is shown that a stable efficiency of event selection (∼98%) is provided in an energy threshold range up to 100 GeV for nuclear collisions at 5 TeV/nucleon in the centre of mass system. In the pp collision case the relevant efficiency drops from 93% down to 80%
New quasibound states of the compound nucleus in α -particle capture by the nucleus
Maydanyuk, Sergei P.; Zhang, Peng-Ming; Zou, Li-Ping
2017-07-01
We generalize the theory of nuclear decay and capture of Gamow that is based on tunneling through the barrier and internal oscillations inside the nucleus. In our formalism an additional factor is obtained, which describes distribution of the wave function of the the α particle inside the nuclear region. We discover new most stable states (called quasibound states) of the compound nucleus (CN) formed during the capture of α particle by the nucleus. With a simple example, we explain why these states cannot appear in traditional calculations of the α capture cross sections based on monotonic penetrabilities of a barrier, but they appear in a complete description of the evolution of the CN. Our result is obtained by a complete description of the CN evolution, which has the advantages of (1) a clear picture of the formation of the CN and its disintegration, (2) a detailed quantum description of the CN, (3) tests of the calculated amplitudes based on quantum mechanics (not realized in other approaches), and (4) high accuracy of calculations (not achieved in other approaches). These peculiarities are shown with the capture reaction of α +44Ca . We predict quasibound energy levels and determine fusion probabilities for this reaction. The difference between our approach and theory of quasistationary states with complex energies applied for the α capture is also discussed. We show (1) that theory does not provide calculations for the cross section of α capture (according to modern models of the α capture), in contrast with our formalism, and (2) these two approaches describe different states of the α capture (for the same α -nucleus potential).
HIJET: a Monte Carlo event generator for P-nucleus-nucleus collisions
International Nuclear Information System (INIS)
Ludlam, T.; Pfoh, A.; Shor, A.
1985-01-01
Comparisons are shown for the HIJET generated data and measured data for average multiplicities, rapidity distributions, and leading proton spectra in proton-nucleus and heavy ion reactions. The algorithm for the generator is one of an incident particle on a target of uniformly distributed nucleons. The dynamics of the interaction limit secondary interactions in that only the leading baryon may re-interact with the nuclear volume. Energy and four momentum are globally conserved in each event. 6 refs., 6 figs
BEEF CATTLE MUSCULARITY CANDIDATE GENES
Directory of Open Access Journals (Sweden)
Irida Novianti
2010-04-01
Full Text Available Muscularity is a potential indicator for the selection of more productive cattle. Mapping quantitative trait loci (QTL for traits related to muscularity is useful to identify the genomic regions where the genes affecting muscularity reside. QTL analysis from a Limousin-Jersey double backcross herd was conducted using QTL Express software with cohort and breed as the fixed effects. Nine QTL suggested to have an association with muscularity were identified on cattle chromosomes BTA 1, 2, 3, 4, 5, 8, 12, 14 and 17. The myostatin gene is located at the centromeric end of chromosome 2 and not surprisingly, the Limousin myostatin F94L variant accounted for the QTL on BTA2. However, when the myostatin F94L genotype was included as an additional fixed effect, the QTL on BTA17 was also no longer significant. This result suggests that there may be gene(s that have epistatic effects with myostatin located on cattle chromosome 17. Based on the position of the QTL in base pairs, all the genes that reside in the region were determined using the Ensembl data base (www.ensembl.org. There were two potential candidate genes residing within these QTL regions were selected. They were Smad nuclear interacting protein 1 (SNIP1 and similar to follistatin-like 5 (FSTL5. (JIIPB 2010 Vol 20 No 1: 1-10
Directory of Open Access Journals (Sweden)
Ramin Soltanzadeh
2012-01-01
Full Text Available The main part of each white blood cell (WBC is its nucleus which contains chromosomes. Although white blood cells (WBCs with giant nuclei are the main symptom of leukemia, they are not sufficient to prove this disease and other symptoms must be investigated. For example another important symptom of leukemia is the existence of nucleolus in nucleus. The nucleus contains chromatin and a structure called the nucleolus. Chromatin is DNA in its active form while nucleolus is composed of protein and RNA, which are usually inactive. In this paper, to diagnose this symptom and in order to discriminate between nucleoli and chromatins, we employ curvelet transform, which is a multiresolution transform for detecting 2D singularities in images. For this reason, at first nuclei are extracted by means of K-means method, then curvelet transform is applied on extracted nuclei and the coefficients are modified, and finally reconstructed image is used to extract the candidate locations of chromatins and nucleoli. This method is applied on 100 microscopic images and succeeds with specificity of 80.2% and sensitivity of 84.3% to detect the nucleolus candidate zone. After nucleolus candidate zone detection, new features that can be used to classify atypical and blast cells such as gradient of saturation channel are extracted.
The Confined Hydrogen Atom with a Moving Nucleus
Fernandez, Francisco M.
2010-01-01
We study the hydrogen atom confined to a spherical box with impenetrable walls but, unlike earlier pedagogical articles on the subject, we assume that the nucleus also moves. We obtain the ground-state energy approximately by means of first-order perturbation theory and show that it is greater than that for the case in which the nucleus is clamped…
On studies of the hadron-nucleus collision processes
International Nuclear Information System (INIS)
Strugalski, Z.
1992-01-01
A new way of hadron-nucleus collision process investigations in experiments is described. It is based on the properties of the hadron passage through layers of the intranuclear matter. The picture of the hadron-nucleus collision mechanism, as prompted experimentally, is presented. 37 refs.; 1 tab
Nucleus retroambiguus projections to the periaqueductal gray in the cat
Klop, EM; Mouton, LJ; Holstege, G
2002-01-01
The nucleus retroambiguus (NRA) of the caudal medulla is a relay nucleus by which neurons of the mesencephalic periaqueductal gray (PAG) reach motoneurons of pharynx, larynx, soft palate, intercostal and abdominal muscles, and several muscles of the hindlimbs. These PAG-NRA-motoneuronal projections
Nucleus-size pinning for determination of nucleation free-energy barriers and nucleus geometry
Sharma, Abhishek K.; Escobedo, Fernando A.
2018-05-01
Classical Nucleation Theory (CNT) has recently been used in conjunction with a seeding approach to simulate nucleation phenomena at small-to-moderate supersaturation conditions when large free-energy barriers ensue. In this study, the conventional seeding approach [J. R. Espinosa et al., J. Chem. Phys. 144, 034501 (2016)] is improved by a novel, more robust method to estimate nucleation barriers. Inspired by the interfacial pinning approach [U. R. Pedersen, J. Chem. Phys. 139, 104102 (2013)] used before to determine conditions where two phases coexist, the seed of the incipient phase is pinned to a preselected size to iteratively drive the system toward the conditions where the seed becomes a critical nucleus. The proposed technique is first validated by estimating the critical nucleation conditions for the disorder-to-order transition in hard spheres and then applied to simulate and characterize the highly non-trivial (prolate) morphology of the critical crystal nucleus in hard gyrobifastigia. A generalization of CNT is used to account for nucleus asphericity and predict nucleation free-energy barriers for gyrobifastigia. These predictions of nuclei shape and barriers are validated by independent umbrella sampling calculations.
International Nuclear Information System (INIS)
Ban-Hao, S.; Wong, C.
1985-01-01
In order to discern coherent or collective processes from incoherent processes in nucleus-nucleus reactions at high energies, we study the transverse-momentum distribution of the produced particles with an incoherent-multiple-collision model. In this model, the projectile nucleon makes successive inelastic collisions with nucleons in the target nucleus, the probability of such collisions being given by the thickness function and the nucleon-nucleon inelastic cross section. It is assumed that each baryon-baryon collision produces particles and degrades momenta just as a baryon-baryon collision in free space, and that there are no secondary collisions between the produced particles and the nucleons. We found that the average transverse momentum and the charged-multiplicity data at Fermilab and CERN ISR energies can be well explained by such a model. However, the average transverse momentum for some events observed by the Japanese-American cooperative emulsion experiment (JACEE) associated with large energy density in the central rapidity region differ markedly from the model results. Such a deviation indicates the presence of coherent or collective effects for these collisions and may indicate the possibility of a formation of quark-gluon plasma
Afferent projections to the deep mesencephalic nucleus in the rat
International Nuclear Information System (INIS)
Veazey, R.B.; Severin, C.M.
1982-01-01
Afferent projections to the deep mesencephalic nucleus (DMN) of the rat were demonstrated with axonal transport techniques. Potential sources for projections to the DMN were first identified by injecting the nucleus with HRP and examining the cervical spinal cord, brain stem, and cortex for retrogradely labeled neurons. Areas consistently labeled were then injected with a tritiated radioisotope, the tissue processed for autoradiography, and the DMN examined for anterograde labeling. Afferent projections to the medial and/or lateral parts of the DMN were found to originate from a number of spinal, bulbar, and cortical centers. Rostral brain centers projecting to both medial and lateral parts of the DMN include the ipsilateral motor and somatosensory cortex, the entopeduncular nucleus, and zona incerta. at the level of the midbrain, the ipsilateral substantia nigra and contralateral DMN likewise project to the DMN. Furthermore, the ipsilateral superior colliculus projects to the DMN, involving mainly the lateral part of the nucleus. Afferents from caudal centers include bilateral projections from the sensory nucleus of the trigeminal complex and the nucleus medulla oblongata centralis, as well as from the contralateral dentate nucleus. The projections from the trigeminal complex and nucleus medullae oblongatae centralis terminate in the intermediate and medial parts of the DMN, whereas projections from the contralateral dentate nucleus terminate mainly in its lateral part. In general, the afferent connections of the DMN arise from diverse areas of the brain. Although most of these projections distribute throughout the entire extent of the DMN, some of them project mainly to either medial or lateral parts of the nucleus, thus suggesting that the organization of the DMN is comparable, at least in part, to that of the reticular formation of the pons and medulla, a region in which hodological differences between medial and lateral subdivisions are known to exist
International Nuclear Information System (INIS)
Silveira, R. da
1996-07-01
Possible effects of quantum-mechanical interferences between gravitational forces and the nucleus-nucleus Coulomb interaction are discussed. It is shown that, although very small, these effects could be measured using low energy scattering between identical heavy nuclei, e.g. for the system 208 Pb + 208 Pb (E L = 5 MeV). (author)
Evolution of a protein folding nucleus.
Xia, Xue; Longo, Liam M; Sutherland, Mason A; Blaber, Michael
2016-07-01
The folding nucleus (FN) is a cryptic element within protein primary structure that enables an efficient folding pathway and is the postulated heritable element in the evolution of protein architecture; however, almost nothing is known regarding how the FN structurally changes as complex protein architecture evolves from simpler peptide motifs. We report characterization of the FN of a designed purely symmetric β-trefoil protein by ϕ-value analysis. We compare the structure and folding properties of key foldable intermediates along the evolutionary trajectory of the β-trefoil. The results show structural acquisition of the FN during gene fusion events, incorporating novel turn structure created by gene fusion. Furthermore, the FN is adjusted by circular permutation in response to destabilizing functional mutation. FN plasticity by way of circular permutation is made possible by the intrinsic C3 cyclic symmetry of the β-trefoil architecture, identifying a possible selective advantage that helps explain the prevalence of cyclic structural symmetry in the proteome. © 2015 The Protein Society.
Comparing Realistic Subthalamic Nucleus Neuron Models
Njap, Felix; Claussen, Jens C.; Moser, Andreas; Hofmann, Ulrich G.
2011-06-01
The mechanism of action of clinically effective electrical high frequency stimulation is still under debate. However, recent evidence points at the specific activation of GABA-ergic ion channels. Using a computational approach, we analyze temporal properties of the spike trains emitted by biologically realistic neurons of the subthalamic nucleus (STN) as a function of GABA-ergic synaptic input conductances. Our contribution is based on a model proposed by Rubin and Terman and exhibits a wide variety of different firing patterns, silent, low spiking, moderate spiking and intense spiking activity. We observed that most of the cells in our network turn to silent mode when we increase the GABAA input conductance above the threshold of 3.75 mS/cm2. On the other hand, insignificant changes in firing activity are observed when the input conductance is low or close to zero. We thus reproduce Rubin's model with vanishing synaptic conductances. To quantitatively compare spike trains from the original model with the modified model at different conductance levels, we apply four different (dis)similarity measures between them. We observe that Mahalanobis distance, Victor-Purpura metric, and Interspike Interval distribution are sensitive to different firing regimes, whereas Mutual Information seems undiscriminative for these functional changes.
Subthalamic nucleus detects unnatural android movement.
Ikeda, Takashi; Hirata, Masayuki; Kasaki, Masashi; Alimardani, Maryam; Matsushita, Kojiro; Yamamoto, Tomoyuki; Nishio, Shuichi; Ishiguro, Hiroshi
2017-12-19
An android, i.e., a realistic humanoid robot with human-like capabilities, may induce an uncanny feeling in human observers. The uncanny feeling about an android has two main causes: its appearance and movement. The uncanny feeling about an android increases when its appearance is almost human-like but its movement is not fully natural or comparable to human movement. Even if an android has human-like flexible joints, its slightly jerky movements cause a human observer to detect subtle unnaturalness in them. However, the neural mechanism underlying the detection of unnatural movements remains unclear. We conducted an fMRI experiment to compare the observation of an android and the observation of a human on which the android is modelled, and we found differences in the activation pattern of the brain regions that are responsible for the production of smooth and natural movement. More specifically, we found that the visual observation of the android, compared with that of the human model, caused greater activation in the subthalamic nucleus (STN). When the android's slightly jerky movements are visually observed, the STN detects their subtle unnaturalness. This finding suggests that the detection of unnatural movements is attributed to an error signal resulting from a mismatch between a visual input and an internal model for smooth movement.
Backward emission in hadron-nucleus collisions
International Nuclear Information System (INIS)
Stelte, N.; Weiner, R.
1981-01-01
Backward emission of hadrons in reactions of the type: P + T → a + anything, where the projectile P is a hadron, T a nuclear target and a a hadron or a light nucleus has been the subject of experimental investigation in the last decade in an energy range E starting in the hundred MeV region and extending up to 400 GeV projectile energy. The main interest in these reactions lies in the fact that they provide information about collective behavior of nucleons in nuclei (cumulative effect, i.e., the presence of secondary particles in a region of momentum space which cannot be populated by nucleon-nucleon interactions) although some authors have recently patronized this effect. In particular the consequences of nuclear limiting fragementation together with the cumulative effect can be used to obtain important information on transport properties and the equation of state of nuclear matter. Limiting fragmentation is a phenomenon discovered in the GeV region and applied to the reaction implies that in the high E limit two separate rapidity regions exist, one for the projectile and another for the target so that in each of the regions the inclusive cross section dsigma/dEd Ω becomes independent of the incoming energy. Here E and Ω refer to the kinetic energy and solid angle of the emitted particle
Heavy nucleus resonance absorption in heterogeneous lattices
International Nuclear Information System (INIS)
Coste, M.; Tellier, H.; Brienne-Raepsaet, C.; Van Der Gucht, C.
1992-01-01
To compute easily the neutron reaction rates in the resonance energy range, the reactor physicists use the self-shielding formalism and the effective cross-section concept. Usually, for these calculations, and equivalence process is used, in such a way that the absorption rate is correctly computed for the whole fuel pin. This procedure does not allow to preserve the spatial absorption rate distribution inside the pin. It is an important handicap if we want to reproduce the plutonium distribution in a spent fuel. To avoid this inconvenience, new improvements of the self-shielding formalism have been recently introduced in the new assembly calculation code of the French Atomic Energy Commission, APOLLO 2. With this improved formalism, it is now possible to represent the spatial and energetic dependence of the heavy nucleus absorption inside the fuel pin and to use a fine energy dependent equivalence process. As it does not exist clean experimental results for the spatial and energetic dependence of the absorption, the authors used reference calculations to qualify the self-shielding formalism. For the strongly self-shielded nuclei of interest in reactor physics, U238, Pu240 and Th232, the agreement between the self-shielding calculation and the reference ones is fairly good for the spatial and energetic dependence of the absorption rate
Control of nucleus accumbens activity with neurofeedback.
Greer, Stephanie M; Trujillo, Andrew J; Glover, Gary H; Knutson, Brian
2014-08-01
The nucleus accumbens (NAcc) plays critical roles in healthy motivation and learning, as well as in psychiatric disorders (including schizophrenia and attention deficit hyperactivity disorder). Thus, techniques that confer control of NAcc activity might inspire new therapeutic interventions. By providing second-to-second temporal resolution of activity in small subcortical regions, functional magnetic resonance imaging (fMRI) can resolve online changes in NAcc activity, which can then be presented as "neurofeedback." In an fMRI-based neurofeedback experiment designed to elicit NAcc activity, we found that subjects could increase their own NAcc activity, and that display of neurofeedback significantly enhanced their ability to do so. Subjects were not as capable of decreasing their NAcc activity, however, and enhanced control did not persist after subsequent removal of neurofeedback. Further analyses suggested that individuals who recruited positive aroused affect were better able to increase NAcc activity in response to neurofeedback, and that NAcc neurofeedback also elicited functionally correlated activity in the medial prefrontal cortex. Together, these findings suggest that humans can modulate their own NAcc activity and that fMRI-based neurofeedback may augment their efforts. The observed association between positive arousal and effective NAcc control further supports an anticipatory affect account of NAcc function. Copyright © 2014 Elsevier Inc. All rights reserved.
11 CFR 110.13 - Candidate debates.
2010-01-01
... debates include at least two candidates; and (2) The staging organization(s) does not structure the... PROHIBITIONS § 110.13 Candidate debates. (a) Staging organizations. (1) Nonprofit organizations described in 26..., subparts D and E. (b) Debate structure. The structure of debates staged in accordance with this section and...
A possible candidate for cold dark matter
Indian Academy of Sciences (India)
This additional scalar can be a viable candidate of cold dark matter (CDM) since the stability of is achieved by the application of Z 2 symmetry on . Considering as a possible candidate of CDM, Boltzmann's equation is solved to find the freeze-out temperature and relic density of for Higgs mass 120 GeV in the scalar ...
76 FR 36130 - Call for Candidates
2011-06-21
... financial information in decision-making. The Board meets in Washington, DC, for two days every other month... FEDERAL ACCOUNTING STANDARDS ADVISORY BOARD Call for Candidates AGENCY: Federal Accounting... candidates. Any applicant who provided the Federal Accounting Standards Advisory Board (FASAB or the Board...
Evaluating historical candidate genes for schizophrenia
DEFF Research Database (Denmark)
Farrell, M S; Werge, T; Sklar, P
2015-01-01
Prior to the genome-wide association era, candidate gene studies were a major approach in schizophrenia genetics. In this invited review, we consider the current status of 25 historical candidate genes for schizophrenia (for example, COMT, DISC1, DTNBP1 and NRG1). The initial study for 24 of thes...
11 CFR 9003.2 - Candidate certifications.
2010-01-01
... funds under 11 CFR 9003.2(c)(3) shall not count against such candidate's $50,000 expenditure limitation... expenditures. (8) Expenditures made using a credit card for which the candidate is jointly or solely liable will count against the limits of this section to the extent that the full amount due, including any...
Status of the search of coherent neutrino nucleus elastic scattering at KSNL
Sharma, V.; Singh, V.; Subrahmanyam, V. S.; Wong, H. T.
2018-04-01
Status of search of coherent elastic neutrino-nucleus scattering (CEνNS) for reactor neutrino flux at Kuo-Sheng nuclear laboratory is discussed. Different detector candidates being used for CEνNS detection across the globe while Germanium detector with its well matured technology and sub-keV threshold, seem to open unseen experimental approach to CEνNS is widely discussed. Reactor neutrinos having energy below 10 MeV are ideal source for the study of CEνNS interaction. We studied about the possible CEνNS signals with associated uncertainties and limit on percentage of channeled nuclei in germanium crystal is quoted. Detection of flavourless CEνNS interaction can play a key role to open the new window on understanding of some unknown processes of the nature.
Santos, Patrícia Dos; Targa, Adriano D S; Noseda, Ana Carolina D; Rodrigues, Lais S; Fagotti, Juliane; Lima, Marcelo M S
2017-09-01
Several efforts have been made to understand the involvement of rapid eye movement (REM) sleep for cognitive processes. Consolidation or retention of recognition memories is severely disrupted by REM sleep deprivation (REMSD). In this regard, pedunculopontine tegmental nucleus (PPT) and other brainstem nuclei, such as pontine nucleus (Pn) and oculomotor nucleus (OCM), appear to be candidates to take part in this REM sleep circuitry with potential involvement in cognition. Therefore, the objective of this study was to investigate a possible association between the performance of Wistar rats in a declarative memory and PPT, Pn, and OCM activities after different periods of REMSD. We examined c-Fos and choline acetyltransferase (ChaT) expressions as indicators of neuronal activity as well as a familiarity-based memory test. The animals were distributed in groups: control, REMSD, and sleep rebound (REB). At the end of the different REMSD (24, 48, 72, and 96 h) and REB (24 h) time points, the rats were immediately tested in the object recognition test and then the brains were collected. Results indicated that OCM neurons presented an increased activity, due to ChaT-labeling associated with REMSD that negatively correlated (r = -0.32) with the cognitive performance. This suggests the existence of a cholinergic compensatory mechanism within the OCM during REMSD. We also showed that 24 h of REMSD impacted similarly in memory, compared to longer periods of REMSD. These data extend the notion that REM sleep is influenced by areas other than PPT, i.e., Pn and OCM, which could be key players in both sleep processes and cognition.
Analysis of the thematic content of review Nucleus
International Nuclear Information System (INIS)
Guerra Valdes, Ramiro
2007-01-01
A computer programme for performing standardized analysis of research areas and key concepts of nuclear science and technology under development at Cubaenergia is presented. Main components of the information processing system, as well as computational methods and modules for thematic content analysis of INIS Database record files are described. Results of thematic content analysis of review Nucleus from 1986 to 2005 are shown. Furthermore, results of demonstrative study Nucleus, Science, Technology and Society are also shown. The results provide new elements to asses the significance of the thematic content of review Nucleus in the context of innovation in interrelated multidisciplinary research areas
Theoretical interpretation of medium energy nucleon nucleus inelastic scattering
International Nuclear Information System (INIS)
Lagrange, Christian
1970-06-01
A theoretical study is made of the medium energy nucleon-nucleus inelastic scattering (direct interaction), by applying the distorted wave Born approximation such as can be deduced from the paired equation method. It is applied to the interpretation of the inelastic scattering of 12 MeV protons by 63 Cu; this leads us to make use of different sets of wave functions to describe the various states of the target nucleus. We analyze the nature of these states and the shape of the nucleon-nucleus interaction potential, and we compare the results with those obtained from other theoretical and experimental work. (author) [fr
On angular distribution of nucleus fission fragments by fast neutrons
International Nuclear Information System (INIS)
Barabanov, A.L.; Grechukhin, D.P.
1987-01-01
Evaluation of amplitudes of quadrupole and hexadecapole components of angular distribution of nucleus fission fragments by neutrons with the energies E n < or approx. 6 MeV is conducted. Stability of this amplitude to permeability optical coefficient variations for neutrons is revealed. It is shown, that the ratio of these amplitudes as well as the character of their dependence on the target nucleus orientation degree are sensitive to the type of fission probability distribution along K projection if fissile nucleus J spin to the fragment scattering axis. This sensitivity may be used for fragment angular distribution anisotropy formation statistical model verification
Semi classical model of the neutron resonance compound nucleus
International Nuclear Information System (INIS)
Ohkubo, Makio
1995-01-01
A Semi-classical model of compound nucleus is developed, where time evolution and recurrence for many degrees of freedom (oscillators) excited simultaneously are explicitly considered. The effective number of oscillators plays the role in the compound nucleus, and the nuclear temperatures are derived, which are in good agreement with the traditional values. Time structures of the compound nucleus at resonance are considered, from which equidistant level series with an envelope of strength function of giant resonance nature is obtained. S-matrix formulation for fine structure resonance is derived. (author)
The Mathematical Model High Energy Collisions Process Hadron-Nucleus
International Nuclear Information System (INIS)
Wojciechowski, A.; Strugalska-Gola, E.; Strugalski, Z.
2002-01-01
During the passage high energy hadron by the heavy nucleus emitted are nucleons and many other particles from which most more group are nucleons and mesons π + π - π 0 . in this work we will present the mathematical model which is a simplified description of basic processes in the interior of the nucleus during passing of the hadron by the nucleus. Result of calculations we will compare with experimental results. Experimental data are based on photographs of 180 litre xenon bubble chambers (180 1 KKP) of Institute of Theoretical and Experimental Physics in Moscow (ITEF, Moscow) irradiated with the beam of mesons π - with momentum 3.5 GeV/c. (author)
On slow particle production in hadron-nucleus interactions
International Nuclear Information System (INIS)
Stenlund, E.; Otterlund, I.
1982-01-01
A model for slow particle production in hadron-nucleus interactions is presented. The model succesfully predicts correlations between the number of knock-on particles and the number of particles associated with the evaporation process as well as correlations with the number of collisions, ν, between the incident hadron and the nucleons inside the target nucleus. The model provides two independent possibilities to determine the number of primary intranuclear collisions, ν, i.e. by its correlation to the number of knock-on particles or to the number of evaporated particles. The good agreement indicates that the model gives an impact-parameter sensitive description of hardron nucleus reactions. (orig.)
Study on isotopic distribution produced by nucleus-nucleus collisions with modified SAA model
International Nuclear Information System (INIS)
Zhong Chen; Fang Deqing; Cai Xiangzhou; Shen Wenqing; Zhang Huyong; Wei Yibin; Ma Yugang
2003-01-01
Base on Brohm's Statistic-Ablation-Abrasion (SAA) model, the modified SAA model was developed via introducing the isospin dependence of nucleon distribution in nucleus and parameterized formulas for nucleon-nucleon cross section in nuclear matter. It can simulate well the isotopic distribution at both high and intermediate energies. By the improvement of computational method, the range of calculation of isotopic distribution can be increased from three order magnitude to eight order magnitude (even higher). It can reproduce experimental data and predict the isotopic distribution for very far from stability line which is very important from experimental viewpoint
Protein expression in the nucleus accumbens of rats exposed to developmental vitamin D deficiency.
Directory of Open Access Journals (Sweden)
John McGrath
Full Text Available INTRODUCTION: Developmental vitamin D (DVD deficiency is a candidate risk factor for schizophrenia. Animal models have confirmed that DVD deficiency is associated with a range of altered genomic, proteomic, structural and behavioural outcomes in the rat. Because the nucleus accumbens has been implicated in neuropsychiatric disorders, in the current study we examined protein expression in this region in adult rats exposed to DVD deficiency METHODS: Female Sprague Dawley rats were maintained on a vitamin D deficient diet for 6 weeks, mated and allowed to give birth, after which a diet containing vitamin D was reintroduced. Male adult offspring (n = 8 were compared to control male (n = 8. 2-D gel electrophoresis-based proteomics and mass spectroscopy were used to investigate differential protein expression. RESULTS: There were 35 spots, mapped to 33 unique proteins, which were significantly different between the two groups. Of these, 22 were down-regulated and 13 up-regulated. The fold changes were uniformly small, with the largest FC being -1.67. Within the significantly different spots, three calcium binding proteins (calbindin1, calbindin2 and hippocalcin were altered. Other proteins associated with DVD deficiency related to mitochondrial function, and the dynamin-like proteins. CONCLUSIONS: Developmental vitamin D deficiency was associated with subtle changes in protein expression in the nucleus accumbens. Disruptions in pathways related to calcium-binding proteins and mitochondrial function may underlie some of the behavioural features associated with animal models of developmental vitamin D deficiency.
DISCOVERY OF A FLAT-SPECTRUM RADIO NUCLEUS IN NGC 3115
Energy Technology Data Exchange (ETDEWEB)
Wrobel, J. M. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Nyland, K., E-mail: jwrobel@nrao.edu, E-mail: knyland@nrao.edu [New Mexico Tech, Department of Physics, 801 Leroy Place, Socorro, NM 87801 (United States)
2012-12-01
The early-type galaxy NGC 3115, at a distance of 10.2 Mpc, hosts the nearest billion-solar-mass black hole. Wong et al. recently inferred a substantial Bondi accretion rate near the black hole. Bondi-like accretion is thought to fuel outflows, which can be traced through their radio emission. This paper reports the discovery of a radio nucleus in NGC 3115, with a diameter less than 0.''17 (8.4 pc), a luminosity at 8.5 GHz of 3.1 Multiplication-Sign 10{sup 35} erg s{sup -1}, and a flat spectrum ({alpha} = -0.23 {+-} 0.20, S{proportional_to}{nu}{sup {alpha}}). The radio source coincides with the galaxy's photocenter and candidate X-ray nucleus. The emission is radio loud, suggesting the presence of an outflow on scales less than 10 pc. On such scales, the Bondi accretion could be impeded by heating due to disruption of the outflow.
Variability-based active galactic nucleus selection using image subtraction in the SDSS and LSST era
Energy Technology Data Exchange (ETDEWEB)
Choi, Yumi; Gibson, Robert R.; Becker, Andrew C.; Ivezić, Željko; Connolly, Andrew J.; Ruan, John J.; Anderson, Scott F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); MacLeod, Chelsea L., E-mail: ymchoi@astro.washington.edu [Physics Department, U.S. Naval Academy, 572 Holloway Road, Annapolis, MD 21402 (United States)
2014-02-10
With upcoming all-sky surveys such as LSST poised to generate a deep digital movie of the optical sky, variability-based active galactic nucleus (AGN) selection will enable the construction of highly complete catalogs with minimum contamination. In this study, we generate g-band difference images and construct light curves (LCs) for QSO/AGN candidates listed in Sloan Digital Sky Survey Stripe 82 public catalogs compiled from different methods, including spectroscopy, optical colors, variability, and X-ray detection. Image differencing excels at identifying variable sources embedded in complex or blended emission regions such as Type II AGNs and other low-luminosity AGNs that may be omitted from traditional photometric or spectroscopic catalogs. To separate QSOs/AGNs from other sources using our difference image LCs, we explore several LC statistics and parameterize optical variability by the characteristic damping timescale (τ) and variability amplitude. By virtue of distinguishable variability parameters of AGNs, we are able to select them with high completeness of 93.4% and efficiency (i.e., purity) of 71.3%. Based on optical variability, we also select highly variable blazar candidates, whose infrared colors are consistent with known blazars. One-third of them are also radio detected. With the X-ray selected AGN candidates, we probe the optical variability of X-ray detected optically extended sources using their difference image LCs for the first time. A combination of optical variability and X-ray detection enables us to select various types of host-dominated AGNs. Contrary to the AGN unification model prediction, two Type II AGN candidates (out of six) show detectable variability on long-term timescales like typical Type I AGNs. This study will provide a baseline for future optical variability studies of extended sources.
Lach, Theodore M.
2003-10-01
The CBM (model) of the nucleus has resulted in the prediction of two new quarks, an "up" quark of mass 237.31 MeV/c2 and a "dn" quark of mass 42.392 MeV/c2. These two new predicted quarks helped to determine that the masses of the quarks and leptons are all related by a geometric progression relationship. The mass of each quark or lepton is just the "geometric mean" of two related elementary particles, either in the same generation or in the same family. This numerology predicts the following masses for the electron family: 0.511000 (electron), 7.74 (predicted), 117.3, 1778.4 (tau), 26950.1 MeV. The geometric ratio of this progression is 15.154 (e to the power e). The mass of the tau in this theory agrees very well with accepted values. This theory suggests that all the "dn like" quarks have a mass of just 10X multiples of 4.24 MeV (the mass of the "d" quark). The first 3 "up like" quark masses are 38, 237.31 and 1500 MeV. This theory also predicts a new heavy generation with a lepton mass of 27 GeV, a "dn like" quark of 42.4 GeV, and an "up like" quark of 65 GeV. Significant evidence already exists for the existence of these new quarks, and lepton. Ref. Masses of the Sub-Nuclear Particles, nucl-th/ 0008026, @ http://xxx.lanl.gov. Infinite Energy, Vol 5, issue 30.
Semiclassical model for single-particle transitions in nucleus-nucleus interactions
International Nuclear Information System (INIS)
Milek, B.; Joint Inst. for Nuclear Research, Dubna; Technische Univ., Dresden; Reif, R.; Pham Khan Van; Revai, J.
1990-04-01
A previously elaborated semiclassical one-body model for the dynamics of a single particle, moving in two potentials, in heavy-ion reactions or in fissioning systems has been extended with respect to the inclusion of angular momenta and more realistic separable potentials. The collective relative motion is assumed to proceed along a trajectory which is calculated from classical equations of motion including conservative and phenomenological friction forces. The formalism has been derived involving three-dimensional trajectories for symmetric as well as for asymmetric nucleus-nucleus systems. The model allows for the calculation of correct quantum mechanical transition amplitudes to final bound and continuum states. It has been applied for the investigation of the excitation of a neutron during a fission process, covering also non-statistical differential emission probabilities. From the numerical calculations, using parameters adapted to 252 Cf(sf), one can conclude that in the underlying model without 'sudden' processes the energy spectrum consists of two parts. The low lying component is created in the neck region while a high lying part seems to be governed mainly by the dynamics of the underlying collective motion rather than by the specific initial conditions. (orig.)
Collision dynamics and particle production in relativistic nucleus- nucleus collisions at CERN
International Nuclear Information System (INIS)
Harris, J.W.
1990-03-01
The possibility of forming a quark-gluon plasma is the primary motivation for studying nucleus-nucleus collisions at very high energies. Various ''signatures'' for the existence of a quark-gluon plasma in these collisions have been proposed. These include an enhancement in the production of strange particles, suppression of J/Ψ production, observation of direct photons from the plasma, event-by-event fluctuations in the rapidity distributions of produced particles, and various other observables. However, the system will evolve dynamically from a pure plasma or mixed phase through expansion, cooling, hadronization and freezeout into the final state particles. Therefore, to be able to determine that a new, transient state of matter has been formed it will be necessary to understand the space-time evolution of the collision process and the microscopic structure of hadronic interactions, at the level of quarks and gluons, at high temperatures and densities. In this talk I will review briefly the present state of our understanding of the dynamics of these collisions and, in addition, present a few recent results on particle production from the NA35 experiment at CERN. 21 refs., 5 figs
Estimation of nuclear destruction in high energy nucleus-nucleus interactions
International Nuclear Information System (INIS)
Uzhinskij, V.V.
1995-01-01
It is assumed that: 1) a projectile particle invokes into target nucleus a cascade of quark-gluon exchanges; 2) the nucleons involved in the cascade are ejected from the nucleus which leads to the nuclear destruction. On these bases a simple model to estimate the nuclear destruction at the fast stage of the interaction is proposed. The allowed region of the model parameters is determined at the proton-emulsion high-energy interaction data analysis: an analysis of gold interactions with nuclei at an energy of 600 MeV/nucleon fixes the parameter values. The distributions on the energy in zero degree calorimeter (T ZDC ) in the interactions of Si+Al, Cu, Pb (14 GeV/nucleon) and Au+Au (10 GeV/nucleon) calculated in the framework of the model and in the cascade-evaporation model (CEM) are presented. The proposed model describes the nuclear destruction at intermediate and high energies better than CEM does. The estimation of the average values of impact parameter and the number of intra-nuclear collisions for Au+Au interactions in the events with different T ZDC is given. 34 refs., 11 figs
Energy Technology Data Exchange (ETDEWEB)
Adel, A. [Cairo University, Physics Department, Faculty of Science, Giza (Egypt); Majmaah University, Physics Department, College of Science, Al-Zulfi (Saudi Arabia); Alharbi, T. [Majmaah University, Physics Department, College of Science, Al-Zulfi (Saudi Arabia)
2017-01-15
The fusion cross sections for reactions involving medium and heavy nucleus-nucleus systems are investigated near and above the Coulomb barrier using the one-dimensional barrier penetration model. The microscopic nuclear interaction potential is computed by four methods, namely: the double-folding model based on a realistic density-dependent M3Y NN interaction with a finite-range exchange part, the Skyrme energy density functional in the semiclassical extended Thomas-Fermi approximation, the generalized Proximity potential, and the Akyuez-Winther interaction. The comparison between the calculated and the measured values of the fusion excitation functions indicates that the calculations of the DFM give quite satisfactory agreement with the experimental data, being much better than the other methods. New parameterized forms for the fusion barrier heights and positions are presented. Furthermore, the effects of deformation and orientation degrees of freedom on the distribution of the Coulomb barrier characteristics as well as the fusion cross sections are studied for the reactions {sup 16}O + {sup 70}Ge and {sup 28}Si + {sup 100}Mo. The calculated values of the total fusion cross sections are compared with coupled channel calculations using the code CCFULL and compared with the experimental data. Our results reveal that the inclusion of deformations and orientation degrees of freedom improves the comparison with the experimental data. (orig.)
Multiparticle excitations in the 149 Gd superdeformed nucleus. Signature of new C4 nucleus symmetry
International Nuclear Information System (INIS)
Theisen, C.
1995-01-01
The use of 8 π and EUROGAM phase I multi-detectors for the study of high spin states of 149 Gd nucleus has revealed unexpected new phenomenons about the superdeformation in this nucleus. The new excited bands confirm the omnipresence of twin bands phenomenon. A new multi-particle excitation (two protons and one neutron) has been discovered. Thanks to the second generation EUROGAM detector, unexpected discoveries such as C 4 symmetry, level interactions, complete backbending were obtained for the second potential well. The knowledge of interacting levels gives informations about the nucleon-nucleon residual interaction and could allow the determination of SD bands excitation energy. The complex processing and analysis of high multiplicity events has led to the development of new computing tools. An automatic band research program has been written for the discovery of new excited bands, and an exact method for the elimination of uncorrected events has been developed. The improvements of multi-detector performances should allow the discovery of more exceptional phenomenons and new anomalies in the SD bands. (J.S.). 222 refs., 86 figs., 38 tabs
Experimental problems of search for quark-gluon plasma in nucleus-nucleus interactions
International Nuclear Information System (INIS)
Okonov, Eh.O.
1987-01-01
Experimental problems for searching for quark-gluon (quagma) plasma in nucleus-nucleus interactions (NbNb,CaCa, ArPb, CnE, ONe) in the energy range E=0.4-1 GeV/A and 3.67 GeV/A and 200 GeV/A energies are discussed. Peculiarities of performing experiments on Dubna synchrophasotron and SPS Bevalac are discussed. The first results prove hadron matter thermalization sufficient for quagma manifestation. It is found that such characteristics of studied interactions as relative λ-hyperon yield, spectral (temperature) characteristics of λ k -hyperons (with higher values of transferred transverse momenta) and associatively produced peons are of greatest interest. The necessity of precise establishment of λ-hyperon group as excessive and differing in its origin from the other particles of the hadron phase is noted. It is shown that experimental approach used in Dubna research proved efficient and requires further development. It includes : selection of rare events (fluctuations) in central interactions of nuclei with high local excitation; search and research of peculiarities in the production of strange particles and in associative pion production; use of streamer spectrometer with a trigger system of rigid selection of central interactions