A twisted conformal field theory description of the Quantum Hall Effect

We construct an effective conformal field theory by using a procedure which induces twisted boundary conditions for the fundamental scalar fields. That allows to describe a quantum Hall fluid at Jain hierarchical filling, nu=m/(2pm+1), in terms of one charged scalar field and m-1 neutral ones. Then the resulting algebra of the chiral primary fields is U(1)xW_m. Finally the ground state wave functions are given as correlators of appropriate composite fields (a-electrons).Comment: 11 pages, plain Late

Patterns of trading profiles at the Nordic Stock Exchange. A correlation-based approach

We investigate the trading behavior of Finnish individual investors trading the stocks selected to compute the OMXH25 index in 2003 by tracking the individual daily investment decisions. We verify that the set of investors is a highly heterogeneous system under many aspects. We introduce a correlation based method that is able to detect a hierarchical structure of the trading profiles of heterogeneous individual investors. We verify that the detected hierarchical structure is highly overlapping with the cluster structure obtained with the approach of statistically validated networks when an appropriate threshold of the hierarchical trees is used. We also show that the combination of the correlation based method and of the statistically validated method provides a way to expand the information about the clusters of investors with similar trading profiles in a robust and reliable way.Comment: 25 pages, 8 figure

Backbone of credit relationships in the Japanese credit market

We detect the backbone of the weighted bipartite network of the Japanese credit market relationships. The backbone is detected by adapting a general method used in the investigation of weighted networks. With this approach we detect a backbone that is statistically validated against a null hypothesis of uniform diversification of loans for banks and firms. Our investigation is done year by year and it covers more than thirty years during the period from 1980 to 2011. We relate some of our findings with economic events that have characterized the Japanese credit market during the last years. The study of the time evolution of the backbone allows us to detect changes occurred in network size, fraction of credit explained, and attributes characterizing the banks and the firms present in the backbone.Comment: 14 pages, 8 figure

Bank-firm credit network in Japan. An analysis of a bipartite network

We present an analysis of the credit market of Japan. The analysis is performed by investigating the bipartite network of banks and firms which is obtained by setting a link between a bank and a firm when a credit relationship is present in a given time window. In our investigation we focus on a community detection algorithm which is identifying communities composed by both banks and firms. We show that the clusters obtained by directly working on the bipartite network carry information about the networked nature of the Japanese credit market. Our analysis is performed for each calendar year during the time period from 1980 to 2011. Specifically, we obtain communities of banks and networks for each of the 32 investigated years, and we introduce a method to track the time evolution of these communities on a statistical basis. We then characterize communities by detecting the simultaneous over-expression of attributes of firms and banks. Specifically, we consider as attributes the economic sector and the geographical location of firms and the type of banks. In our 32 year long analysis we detect a persistence of the over-expression of attributes of clusters of banks and firms together with a slow dynamics of changes from some specific attributes to new ones. Our empirical observations show that the credit market in Japan is a networked market where the type of banks, geographical location of firms and banks and economic sector of the firm play a role in shaping the credit relationships between banks and firms.Comment: 9 pages, 4 figures, 2 Table

Long-term ecology of investors in a financial market

The cornerstone of modern finance is the efficient market hypothesis. Under this hypothesis all information available about a financial asset is immediately incorporated into its price dynamics by fully rational investors. In contrast to this hypothesis many studies have pointed out behavioral biases in investors. Recently it has become possible to access databases that track the trading decisions of investors. Studies of such databases have shown that investors acting in a financial market are highly heterogeneous among them, and that heterogeneity is a common characteristic of many financial markets. The article describes an empirical study of the daily trading decisions of all Finnish investors investing Nokia stock over a time period of 15 years. The investigation is performed by adapting and using methods and tools in network science. By investigating daily trading decisions, and by constructing the time-evolution of statistically validated networks of investors, clusters of investors\u2014and their time evolution\u2014 which are characterized by similar trading profiles are detected. These clusters are performing distinct trading decisions on time scales ranging from several months to twelve years. These empirical observations show the presence of an ecology of groups of investors characterized by different attributes and by various investment styles over many years. Some of the detected clusters present a persistent over-expression of specific investor categories. The study shows that the logarithm of the ratio of pairs of statistically validated trading decisions is different for different values of the market volatility. These findings suggest that an ecology of investors is present in financial markets and that groups of traders are always competing, adopting, using and eventually discarding new investment strategies. This adaptation process is observed over a multiplicity of time scales, and is compatible with several conclusions of behavioral finance and with the assumptions of the so-called adaptive market hypothesis

Probing the non-canonical interface for agonist interaction with an α5 containing nicotinic acetylcholine receptor

Nicotinic acetylcholine receptors (nAChRs) containing the α5 subunit are of interest because genomewide association studies and candidate gene studies have identified polymorphisms in the α5 gene that are linked to an increased risk for nicotine dependence, lung cancer, and/or alcohol addiction. To probe the functional impact of an α5 subunit on nAChRs, a method to prepare a homogeneous population of α5-containing receptors must be developed. Here we use a gain of function (9') mutation to isolate populations of α5-containing nAChRs for characterization by electrophysiology. We find that the α5 subunit modulates nAChR rectification when co-assembled with α4 and β2 subunits. We also probe the α5-α4 interface for possible ligand-binding interactions. We find that mutations expected to ablate an agonist-binding site involving the α5 subunit have no impact on receptor function. The most straightforward interpretation of this observation is that agonists do not bind at the α5-α4 interface, in contrast to what has recently been demonstrated for the α4-α4 interface in related receptors. In addition, our mutational results suggest that the α5 subunit does not replace the α4 or β2 subunits and is relegated to occupying only the auxiliary position of the pentameric receptor

A general interpolation scheme for thermal fluctuations in superconductors

We present a general interpolation theory for the phenomenological effects of thermal fluctuations in superconductors. Fluctuations are described by a simple gauge invariant extension of the gaussian effective potential for the Ginzburg-Landau static model. The approach is shown to be a genuine variational method, and to be stationary for infinitesimal gauge variations around the Landau gauge. Correlation and penetration lengths are shown to depart from the mean field behaviour in a more or less wide range of temperature below the critical regime, depending on the class of material considered. The method is quite general and yields a very good interpolation of the experimental data for very different materials.Comment: some misprints have been corrected in Eq.(15),(19); more references and comments have been adde

Valutazione della sicurezza delle infrastrutture critiche nel settore civile, definizioni e metodologia

Le società industrializzate dipendono dal corretto funzionamento di un insieme d’infrastrutture tecnologiche, quali le reti elettriche, quelle viarie e ferroviarie e le reti di telecomunicazione che, per la loro rilevanza, sono genericamente indicate come infrastrutture critiche, perché intese come quei sistemi, o parte di essi, essenziali per il mantenimento delle funzioni vitali della società, della salute, della sicurezza e del benessere economico e sociale, il cui danneggiamento o la cui distruzione avrebbe un impatto significativo in quello Stato, a causa dell’impossibilità di mantenere tali funzioni. Infatti, guasti tecnici, disastri naturali ed eventi dolosi, se non addirittura terroristici, potrebbero avere degli effetti devastanti. Gli eventi degli ultimi anni hanno accelerato gli sforzi di individuazione e designazione delle infrastrutture critiche a livello nazionale ed europeo e hanno rafforzato le preoccupazioni per l’aumento della protezione delle infrastrutture critiche in settori sensibili per la sicurezza dell’individuo e della comunità. Si tratta di reali pericoli per lo sviluppo e il benessere sociale di un Paese che sembrano essere accresciuti dall’estremizzazione dei fenomeni climatici e dalla tormentata situazione socio-politica mondiale. Le minacce alla sicurezza delle infrastrutture critiche nel settore civile (scuole, ospedali, stadi, teatri, cinema multisala, stazioni ferroviarie, aeroportuali, marittime ecc.) sono uno dei principali problemi delle società industrializzate negli ultimi tempi. Nei loro confronti vengono sempre più richieste garanzie di massima sicurezza, per scongiurare qualsiasi incidente che potrebbe mettere in pericolo la salute e la sicurezza dei cittadini, ma anche costituire un impatto pericoloso per l'ambiente e l'economia di un paese. L’obiettivo della presente memoria è fornire in modo semplice ma puntuale gli elementi di base per comprendere la tematica insieme alle motivazioni della sua importanza sia a livello nazionale, sia europeo, sia internazionale. In particolare, dopo aver tracciato l’origine del problema, cioè il tipo di minacce e rischi che si intendono contrastare, nonché le nuove vulnerabilità gravanti sulla nostra società, si descrivono le azioni intraprese dall’Europa finalizzate a migliorare la protezione delle Infrastrutture Critiche nel settore civile, anche in riferimento alla Direttiva 2008/114/CE e alla normativa nazionale di recepimento (D.Lgs 11 aprile 2011, n. 61)

Performance Comparison of Alternative Hollow-Fiber Modules for Hemodialysis by Means of a CFD-Based Model

Commercial hemodialyzers are hollow-fiber cylindrical modules with dimensions and inlet– outlet configurations dictated mostly by practice. However, alternative configurations are possible, and one may ask how they would behave in terms of performance. In principle, it would be possible to depart from the standard counter-flow design, while still keeping high clearance values, thanks to the increase in the shell-side Sherwood number (Sh) due to the cross-flow. To elucidate these aspects, a previously developed computational model was used in which blood and dialysate are treated as flowing through two interpenetrating porous media. Measured Darcy permeabilities and mass transfer coefficients derived from theoretical arguments and CFD simulations conducted at unit-cell scale were used. Blood and dialysate were alternately simulated via an iterative strategy, while appropriate source terms accounted for water and solute exchanges. Several module configurations sharing the same membrane area, but differing in overall geometry and inlet–outlet arrangement, were simulated, including a commercial unit. Although the shell-side Sherwood number increased in almost all the alternative configurations (from 14 to 25 in the best case), none of them outperformed in terms of clearance the commercial one, approaching the latter (257 vs. 255 mL/min) only in the best case. These findings confirmed the effectiveness of the established commercial module design for the currently available membrane properties

Adjuvant benefit of a peptide-rich marine biology formula (LD-1227) in rheumatoid arthritis: a randomized, double-blind, controlled study

Introduction. There is a growing interest on non-chemical therapies among patients suffering from rheumatoid arthritis (RA), although safety, efficacy and properly designed studies are often lacking. Objective. The aim of the present investigation was to explore the clinical effectiveness of a marine nutraceutical, LD-1227, endowed by fine molecular biology studies, in the management of RA. Methods. The study design was a 12-week, randomized, double-blind study involving forty patients with stable longstanding RA who were randomized to receive either LD-1227 (n = 20) or Omega-3 (n = 20) on top of their established maintenance therapy. Results. At study recruitment and after 12 weeks of treatment, their Health Assessment Questionnaire (HAQ), erythrocyte sedimentation rate (ESR), visual analogue scale (VAS), and Disease Activity Score (DAS) 28, anxiety and depression analysis, C-reactive protein (CRP) levels, CXCL1, several pro-inflammatory interleukins levels and related gene expression, were compared between the two groups. Primary end point was the proportion of patients with response at weeks 12 as from the 20 % to 50% improvement criteria of the American College of Rheumatology (ACR20). At 12 weeks, ACR20 beneficial response was 81.0 % in LD-1227 group and 44 % in omega-3 group, (p< 0.01). The superiority of LD-1227 appeared also when considering the ACR50 response at 12 weeks (62% in LD-1227 group as compared to 31 % in omega-3 group, p< 0.01). The LD-1227-treated group displayed a significant improvement of VAS scale, HAQ score, morning stiffness and tender points (p < 0.01 vs control and p < 0.05 vs omega-3, respectively). From the biochemical viewpoint, patients in the LD-1227 group showed a lower level of CRP, IL-6, TNF-α, IL-1β, CXCL1, IFNγ, IL-15 and IP-10 and significant downregulation of related gene expressions. Unlike what observed in LD-1227 group, in the omega-3 group, CRP and DAS28 did not reach statistical difference. A substantial reduction of extra pain killer use was noted under LD-1227 treatment. Conclusion. One can conclude that LD-1227 may play a significant role on the management of RA and with a specrum and mechanisms of actions distinct from the canonical omega-3 while being devoid of any side effect or tolerability issues