Noninteracting Fermions in infinite dimensions

Usually, we study the statistical behaviours of noninteracting Fermions in finite (mainly two and three) dimensions. For a fixed number of fermions, the average energy per fermion is calculated in two and in three dimensions and it becomes equal to 50 and 60 per cent of the fermi energy respectively. However, in the higher dimensions this percentage increases as the dimensionality increases and in infinite dimensions it becomes 100 per cent. This is an intersting result, at least pedagogically. Which implies all fermions are moving with Fermi momentum. This result is not yet discussed in standard text books of quantum statistics. In this paper, this fact is discussed and explained. I hope, this article will be helpful for graduate students to study the behaviours of free fermions in generalised dimensionality.Comment: To appear in European Journal of Physics (2010

How Much do Heavy Quarks Thermalize in a Heavy Ion Collision?

We investigate the thermalization of charm quarks in high energy heavy ion collisions. To this end, we calculate the diffusion coefficient in the perturbative Quark Gluon Plasma and relate it to collisional energy loss and momentum broadening. We then use these transport properties to formulate a Langevin model for the evolution of the heavy quark spectrum in the hot medium. The model is strictly valid in the non-relativistic limit and for all velocities \gamma v < \alphas^{-1/2} to leading logarithm in $T/m_D$. The corresponding Fokker-Planck equation can be solved analytically for a Bjorken expansion and the solution gives a simple estimate for the medium modifications of the heavy quark spectrum as a function of the diffusion coefficient. Finally we solve the Langevin equations numerically in a hydrodynamic simulation of the heavy ion reaction. The results of this simulation are the medium modifications of the charm spectrum $R_{AA}$ and the expected elliptic flow $v_2(p_T)$ as a function of the diffusion coefficient.Comment: 34 pages, 9 figures. Inculdes a detailed comparison with Boltzmann simulation

A Model for Phase Transition based on Statistical Disassembly of Nuclei at Intermediate Energies

Consider a model of particles (nucleons) which has a two-body interaction which leads to bound composites with saturation properties. These properties are : all composites have the same density and the ground state energies of composites with k nucleons are given by -kW+\sigma k^{2/3} where W and \sigma are positive constants. W represents a volume term and \sigma a surface tension term. These values are taken from nuclear physics. We show that in the large N limit where N is the number of particles such an assembly in a large enclosure at finite temperature shows properties of liquid-gas phase transition. We do not use the two-body interaction but the gross properties of the composites only. We show that (a) the p-\rho isotherms show a region where pressure does not change as $\rho$ changes just as in Maxwell construction of a Van der Waals gas, (b) in this region the chemical potential does not change and (c) the model obeys the celebrated Clausius-Clapeyron relations. A scaling law for the yields of composites emerges. For a finite number of particles N (upto some thousands) the problem can be easily solved on a computer. This allows us to study finite particle number effects which modify phase transition effects. The model is calculationally simple. Monte-Carlo simulations are not needed.Comment: RevTex file, 21 pages, 5 figure

Microcanonical Lattice Gas Model for Nuclear Disassembly

Microcanonical calculations are no more difficult to implement than canonical calculations in the Lattice Gas Model. We report calculations for a few observables where we compare microcanonical model results with canonical model results.Comment: 7 pages, Revtex, 3 postscript figure

Reciprocity relations between ordinary temperature and the Frieden-Soffer's Fisher-temperature

Frieden and Soffer conjectured some years ago the existence of a ``Fisher temperature" T_F that would play, with regards to Fisher's information measure I, the same role that the ordinary temperature T plays vis-a-vis Shannon's logarithmic measure. Here we exhibit the existence of reciprocity relations between T_F and T and provide an interpretation with reference to the meaning of T_F for the canonical ensemble.Comment: 3 pages, no figure

Improving Patient Activation in Crisis and Chronic Care Through Rhetorical Approaches to New Media Technologies

As the U.S. population both increases and ages over the next 40 years, the numbers of patients requiring healthcare for both crisis-oriented and chronic conditions will grow in tandem (USHHS, 2009). This growth requires that healthcare practitioners and patients master new methodologies for communicating about care. Among these methodological possibilities are new and social media, such as websites, mobile phone text messaging, interactive websites, YouTube, Twitter, and Facebook. Here, communication and rhetoric of science scholars can help shape the future efficacy of Web 2.0 healthcare communication and the strategies its practitioners use toward patient activation

The role of the nature of the noise in the thermal conductance of mechanical systems

Focussing on a paradigmatic small system consisting of two coupled damped oscillators, we survey the role of the L\'evy-It\^o nature of the noise in the thermal conductance. For white noises, we prove that the L\'evy-It\^o composition (Lebesgue measure) of the noise is irrelevant for the thermal conductance of a non-equilibrium linearly coupled chain, which signals the independence between mechanical and thermodynamical properties. On the other hand, for the non-linearly coupled case, the two types of properties mix and the explicit definition of the noise plays a central role.Comment: 9 pages, 2 figures. To be published in Physical Review

Analog approach for the eigen-decomposition of positive definite matrices

AbstractThis paper proposes an analog approach for performing the eigen-decomposition of positive definite matrices. We show analytically and by simulations that the proposed circuit is guaranteed to converge to the desired eigenvectors and eigenvalues of positive definite matrices

Caloric Curves for small systems in the Nuclear Lattice Gas Model

For pedagogical reasons we compute the caloric curve for 11 particles in a $3^3$ lattice. Monte-Carlo simulation can be avoided and exact results are obtained. There is no back-bending in the caloric curve and negative specific heat does not appear. We point out that the introduction of kinetic energy in the nuclear Lattice Gas Model modifies the results of the standard Lattice Gas Model in a profound way.Comment: 12 pages, Revtex, including 4 postscript figure

The Nature of Radio Continuum Emission in the Dwarf Starburst Galaxy NGC 625

We present new multi-frequency radio continuum imaging of the dwarf starburst galaxy NGC 625 obtained with the Very Large Array. Data at 20, 6, and 3.6 cm reveal global continuum emission dominated by free-free emission, with only mild synchrotron components. Each of the major HII regions is detected; the individual spectral indices are thermal for the youngest regions (showing strongest H Alpha emission) and nonthermal for the oldest. We do not detect any sources that appear to be associated with deeply embedded, dense, young clusters, though we have discovered one low-luminosity, obscured source that has no luminous optical counterpart and which resides in the region of highest optical extinction. Since NGC 625 is a Wolf-Rayet galaxy with strong recent star formation, these radio properties suggest that the youngest star formation complexes have not yet evolved to the point where their thermal spectra are significantly contaminated by synchrotron emission. The nonthermal components are associated with regions of older star formation that have smaller ionized gas components. These results imply a range of ages of the HII regions and radio components that agrees with our previous resolved stellar population analysis, where an extended burst of star formation has pervaded the disk of NGC 625 over the last ~ 50 Myr. We compare the nature of radio continuum emission in selected nearby dwarf starburst and Wolf-Rayet galaxies, demonstrating that thermal radio continuum emission appears to be more common in these systems than in typical HII galaxies with less recent star formation and more evolved stellar clusters.Comment: ApJ, in press; 27 pages, 5 figures. Full-resolution version may be obtained at http://www.astro.umn.edu/~cannon/n625.vla.p