The order of the Roberge-Weiss endpoint (finite size transition) in QCD

We consider the endpoint of the Roberge-Weiss (RW) first order transition line present for imaginary baryon chemical potentials. We remark that it coincides with the finite size transition relevant in the context of large $N_c$ QCD and study its order in the theory with two degenerate flavors. The RW endpoint is first order in the limit of large and small quark masses, while it weakens for intermediate masses where it is likely in the Ising 3d universality class. Phenomenological implications and further speculations about the QCD phase diagram are discussed.Comment: 5 pages, 8 figures. Version accepted for publication in Physical Review D (R

Image Analysis Workflow for 2-D Electrophoresis Gels Based on ImageJ

A number of commercial software packages are currently available to perform digital two-dimensional electrophoresis (2D-GE) gel analysis. However, both the high cost of the commercial packages and the unavailability of a standard data analysis workflow, have prompted several groups to develop freeware systems to perform certain steps of gel analysis. Unfortunately, to the best of our knowledge none of them offer a package that performs all the steps envisaged in a 2D-GE gel analysis. Here we describe an ImageJ-based procedure, able to manage all the steps of a 2D-GE gel analysis. ImageJ is a free available image processing and analysis application developed by National Institutes of Health (NIH) and widely used in different life sciences fields as medical imaging, microscopy, western blotting and PAGE. Nevertheless no one has yet developed a procedure enabled to compare spots on 2D-GE gels. We collected all used ImageJ tools in a plug-in that allows us to perform the whole 2D-GE analysis. To test it, we performed a set of 2D-GE experiments on plasma samples from 9 patients victims of acute myocardial infarction and 8 controls, and we compared the results obtained by our procedure to those obtained using a widely diffuse commercial package, finding similar performance

College and University Ranking Systems: Global Perspectives and American Challenges

Examines how higher education ranking systems function, how other countries use ranking systems, and the impact of college rankings in the United States on student access, choice, and opportunity

Evidence for a floating phase of the transverse ANNNI model at high frustration

We study the transverse quantum ANNNI model in the region of high frustration (k>0.5) using the DMRG algorithm. We obtain a precise determination of the phase diagram, showing clear evidence for the existence of a floating phase, separated from the paramagnetic modulated phase by a high-order critical line ending at the multicritical point. We obtain simple and accurate formulae for the two critical lines.Comment: 20 pages, 16 figures. Major revision: numerical evidence improved, presentation clarified, discussion on KT phase transitions added, references update

Electric Waterborne Public Transportation in Venice: a Case Study

The paper reports the results of a study for moving the present diesel-based watercraft propulsion technology used for public transportation in Venice city and lagoon to a more efficient and smart electric propulsion technology, in view of its adopted in a near future. Energy generation and storage systems, electrical machines and drives, as well as economic, environmental and social issues are presented and discussed. Some alternative solutions based on hybrid diesel engine and electric and full electric powertrains are compared in terms of weights, costs and payback times. Previews researches on ship propulsion and electric energy storage developed by the University of Padua and preliminary experiences on electric boats carried out in Venice lagoon by the municipal transportation company ACTV and other stakeholders are the starting point for this study. Results can be transferred to other waterborne mobility systems

The sutures in dentistry

In oral surgery, the last phase of a surgical operation is represented by the tissues suture, that allows the wound lips edges approximation and their stabilization, to promote haemostasis, to avoid the alimentary residues accumulation on the incision line and allow the first intention healing. A good suture avoids that the displacing forces generated by the muscular insertions, functional movements and by the external agents destabilize or cause the surgical wound deiscence. The purpose of this study was to re-examine the suture threads characteristics, properties and biological interactions evaluating the different studies published in literature results and conclusions. In conclusion, the authors recommended the use of the different suture threads on the dependence of the oral surgery operation type that must be performed, of the patient compliance and of the various suture materials physical and biocompatibility characteristics

Pairing and polarization in systems with retarded interactions

In a system where a boson (e.g, a phonon) of finite frequency $\omega_0$ is coupled to electrons, two phenomena occur as the coupling is increased: electron pairing and polarization of the boson field. Within a path integral formalism and a Dynamical Mean-Field approach, we introduce {\it ad hoc} distribution function which allow us to pinpoint the two effects. When $\omega_0$ is smaller than the bandwidth $D$, pairing and polarization occur for fairly similar couplings for all considered temperatures. When $\omega_0 > D$, the two phenomena tend to coincide only for $T \gg \omega_0$, but are no longer tied for low temperatures so that a state of paired particles without finite polarization is stabilized.Comment: 4 pages, 2 figure

Does the Fine Structure Constant Really Vary in Time?

We discuss how laboratory experiments can be used to place constraints on possible variations of the fine structure constant alpha in the observationally relevant redshift interval z ~= 0 - 5, within a rather general theoretical framework. We find a worst case upper limit for Delta alpha / alpha of 8 x 10^-6 for z <= 5 and Delta alpha / alpha of 0.9 x 10^-6 for z <= 1.6. The derived limits are at variance with the recent findings by Webb et al. (1998), who claim an observed variation of Delta alpha/alpha = -2.6 +- 0.4 x 10^-5 at 1<z<1.6.Comment: 11 pages, 2 figures, ApJL in pres

Relaxation due to random collisions with a many-qudit environment

We analyze the dynamics of a system qudit of dimension mu sequentially interacting with the nu-dimensional qudits of a chain playing the ore of an environment. Each pairwise collision has been modeled as a random unitary transformation. The relaxation to equilibrium of the purity of the system qudit, averaged over random collisions, is analytically computed by means of a Markov chain approach. In particular, we show that the steady state is the one corresponding to the steady state for random collisions with a single environment qudit of effective dimension nu_e=nu*mu. Finally, we numerically investigate aspects of the entanglement dynamics for qubits (mu=nu=2) and show that random unitary collisions can create multipartite entanglement between the system qudit and the qudits of the chain.Comment: 7 pages, 6 figure

Stationary entanglement in N-atom subradiant degenerate cascade systems

We address ultracold $N$-atom degenerate cascade systems and show that stationary subradiant states, already observed in the semiclassical regime, also exist in a fully quantum regime and for a small number of atoms. We explicitly evaluate the amount of stationary entanglement for the two-atom configuration and show full inseparability for the three-atom case. We also show that a continuous variable description of the systems is not suitable to detect entanglement due to the nonGaussianity of subradiant states.Comment: 4 figure