Rapidity distributions of strange particles in Pb-Pb at 158 A GeV/c

The production at central rapidity of K0s, Lambda, Xi and Omega particles in Pb-Pb collisions at 158 A GeV/c has been measured by the NA57 experiment over a centrality range corresponding to the most central 53% of the inelastic Pb-Pb cross section. We present the rapidity distribution of each particle in the central rapidity unit. The distributions are analysed based on hydrodynamical models of the collisions.Comment: Contribution to the Poster Proceedings of the Quark Matter 2005 Conference. To be published in Nukleonika, International Journal of Nuclear Researc

A unified approach to electron transport in double barrier structures

In this paper we show an approach to electron transport in double barrier structures which unifies the well known sequential and resonant tunneling models in the widest range of transport regimes, from completely coherent to completely incoherent. In doing so, we make a clear distinction between ``approaches'' and ``transport regimes,'' in order to clarify some ambiguities in the concept of sequential tunneling. Scattering processes in the well are accounted for by means of an effective mean free path, which plays the role of a relaxation length. Our approach is based on a recently derived formula for the density of states in a quantum well, as a function of the round trip time in the well and of trasmission and reflection probabilities for the whole structure and for each barrier.Comment: RevTeX file, 14 pages, 2 uuencoded Postscript figures, uses epsf.sty. To be published on Phys. Rev. B. Postscript files and hard copies available from the authors upon request ([email protected]

A COMPARATIVE STUDY OF ALTERNATIVE ECONOMETRIC PACKAGES: AN APPLICATION TO ITALIAN DEPOSIT INTEREST RATES

In examining the determinants of Italian deposit interest rates, we compares alternative econometric packages for estimating panel data. We focus on bank deposits, one of the main forms Italian households use to invest their financial wealth. We survey the literature on deposit rates, with particular reference to the large number of US studies. The empirical analysis is based on more than 8,000 observations for the years 1990-1996. Bank interest rates are taken from the Central Credit Register. We consider the rates on current accounts, certificates of deposit, and total deposits. Other variables are obtained from the Banking Supervision1s statistical returns. We look at the influence on interest rates of the Herfindahl index, the number of banks in each province, the rate of growth in deposits, the custodial holdings of bonds, the ratio of banking costs to total assets.With this abundance of panel data, many different specifications have been estimated using the fixed- and random-effects models. Our purpose is to examine the caveats about numerical accuracy raised by McCullogh and Vinod, who are concerned that little attention is paid to numerical accuracy in the selection of econometric packages. We compare the numerical value of the estimates of three of the most popular econometric packages featuring built-in panel data estimation algorithms: LIMDEP, STATA, and TSP. As a numerical benchmark we used Modeleasy, a general-purpose language allowing matrix operations.The preliminary results look quite promising:1) fixed-effects algorithms are numerically the same to the available decimal places.2) random-effects algorithms yield slightly different results because of the method for computing the variance components.In addition, we compare the relative efficiency of the random-effects algorithms provided by the three packages. This is done by means of a set of suitably designed Monte Carlo experiments, varying the time span and the number of provinces taken into account.

Uncertainty of Law and the Legal Process.

There is extensive literature on whether courts or legislators produce efficient rules, but which of them produces rules efficiently? Is there an optimal mix of litigation and legislation? The law is inevitably subject to a certain degree of uncertainty ex ante; uncertainty makes the outcomes of trials difficult to predict and, hence, prevents parties from settling disputes out of court. Conversely, the law is necessarily certain ex post: litigation fosters the creation of precedents that reduce uncertainty. We postulate that there is a natural balance between the degree of uncertainty of a legal system (kept under control by litigation) and its litigation rate (sustained by uncertainty). We describe such equilibrium rates of litigation and uncertainty in a formal model, study how they are affected by two different policies -litigation fees/subsidies and legislation - and compare the costs and benefits of the legislative and the judicial process of lawmaking. We then extend the analysis to explore the implications of this approach.incompleteness of law, complexity of law, litigation, judge-made law, legislation.

Progression of extrapyramidal signs in Alzheimer's disease. clinical and neuropathological correlates

Extrapyramidal signs (EPS) are frequent in Alzheimer's disease (AD) and core manifestation of related diseases, i.e., dementia with Lewy bodies and Parkinson's disease; furthermore, Lewy bodies and AD-type pathology occur in all three conditions

New wine in new bottles: Visualizing the progression over time of the epidemics of tobacco smoking and obesity through the use of modified population pyramids

Tobacco smoking and obesity greatly contribute to premature death and disease in developed countries. In order to measure the extent to which these risk factors affect a population, as well as to describe the progression of these epidemics over time, routine surveillance of the prevalence of obesity and smoking is carried out by international organizations, national departments of health, and statistical offices. To this end, summary measures—like age-standardized rates, and tabular and graphical representations, such as maps—are used. In this study, we argue that population pyramids, a widely used demographic tool, may be easily adapted to provide relevant visual information for public health purposes. By means of two juxtaposed histograms, one for each gender, population pyramids show either the proportion or the actual number of subjects in each age and gender subgroup. We suggest that stratifying each bar of the two histograms according to ordinal categories of the health condition or risk factor examined may provide useful details on the relationship between this condition or factor and key demographic variables like age and gender. In addition, the actual number of exposed subjects can be immediately read from the graph. We therefore built a statistical routine with Stata to create modified population-pyramid plots separately for overweight/obese and current/former smoker. Data were derived from five National Health Interview Surveys carried out in Italy between 1983 and 2005. For each survey, data on age, gender, smoking status, height, and weight were extracted for subjects aged 20–99. Age and gender-specific prevalence rates of overweight/obese, and of current/former/never smoker were computed and applied to population estimates performed by the Italian national statistical institute (ISTAT). The resulting estimated numbers of underweight/normal weight/overweight/obese individuals and of former/current/never smokers were used to create the modified population pyramids. In conclusion, modified population pyramids may contribute to assessing the impact of risk factors on a population in absolute terms, to evaluating how these risk factors are distributed by age and gender, and to assessing how the age and gender distribution of these risk factors changes over time.

On Strong convergence of Halpern's method using averaged type mappings

In this paper, inspired by Iemoto and Takahashi [S. Iemoto, W. Takahashi, Nonlinear Analysis 71, (2009), 2082-2089], we study the Halpern's method to approximate strongly fixed points of a nonexpansive mapping and of a nonspreading mapping. A crucial tool in our results is the regularization with the averaged type mappings [C. Byrne, Inverse Probl. 20, (2004), 103-120]

A Hierarchical Rate Splitting Strategy for FDD Massive MIMO under Imperfect CSIT

In a multiuser MIMO broadcast channel, the rate performance is affected by the multiuser interference when the Channel State Information at the Transmitter (CSIT) is imperfect. To tackle the interference problem, a Rate-Splitting (RS) approach has been proposed recently, which splits one user's message into a common and a private part, and superimposes the common message on top of the private messages. The common message is drawn from a public codebook and should be decoded by all users. In this paper, we propose a novel and general framework, denoted as Hierarchical Rate Splitting (HRS), that is particularly suited to FDD massive MIMO systems. HRS simultaneously transmits private messages intended to each user and two kinds of common messages that can be decoded by all users and by a subset of users, respectively. We analyse the asymptotic sum rate of HRS under imperfect CSIT. A closed-form power allocation is derived which provides insights into the effects of system parameters. Finally, simulation results validate the significant sum rate gain of HRS over various baselines.Comment: Accepted paper at IEEE CAMAD 201