An improved geometric inequality via vanishing moments, with applications to singular Liouville equations

We consider a class of singular Liouville equations on compact surfaces motivated by the study of Electroweak and Self-Dual Chern-Simons theories, the Gaussian curvature prescription with conical singularities and Onsager's description of turbulence. We analyse the problem of existence variationally, and show how the angular distribution of the conformal volume near the singularities may lead to improvements in the Moser-Trudinger inequality, and in turn to lower bounds on the Euler-Lagrange functional. We then discuss existence and non-existence results.Comment: some references adde

New improved Moser-Trudinger inequalities and singular Liouville equations on compact surfaces

We consider a singular Liouville equation on a compact surface, arising from the study of Chern-Simons vortices in a self dual regime. Using new improved versions of the Moser-Trudinger inequalities (whose main feature is to be scaling invariant) and a variational scheme, we prove new existence results.Comment: to appear in GAF

Existence of Multistring Solutions of the Self-Gravitating Massive W−W-Boson

We consider a semilinear elliptic system which include the model system of the $W-$strings in the cosmology as a special case. We prove existence of multi-string solutions and obtain precise asymptotic decay estimates near infinity for the solutions. As a special case of this result we solve an open problem posed in \cite{yan}Comment: 12 page

Statistical mechanics of clonal expansion in lymphocyte networks modelled with slow and fast variables

We study the Langevin dynamics of the adaptive immune system, modelled by a lymphocyte network in which the B cells are interacting with the T cells and antigen. We assume that B clones and T clones are evolving in different thermal noise environments and on different timescales. We derive stationary distributions and use statistical mechanics to study clonal expansion of B clones in this model when the B and T clone sizes are assumed to be the slow and fast variables respectively and vice versa. We derive distributions of B clone sizes and use general properties of ferromagnetic systems to predict characteristics of these distributions, such as the average B cell concentration, in some regimes where T cells can be modelled as binary variables. This analysis is independent of network topologies and its results are qualitatively consistent with experimental observations. In order to obtain full distributions we assume that the network topologies are random and locally equivalent to trees. The latter allows us to employ the Bethe-Peierls approach and to develop a theoretical framework which can be used to predict the distributions of B clone sizes. As an example we use this theory to compute distributions for the models of immune system defined on random regular networks.Comment: A more recent version (accepted for publication in Journal of Physics A: Mathematical and Theoretical) with improved figures, references, et

Cooperative and competitive behaviour among passengers during the Costa Concordia disaster

Despite the increase in regulation and codes, there is a relatively small body of scientific literature on maritime disasters management, especially in terms of human factors that affect the success of the evacuation and safety procedures. This paper provides an analysis of passengers’ behaviour during the Costa Concordia disaster of 2012, in which 32 people died. We use 49 passengers’ witness statement made available by the court of Grosseto to understand how the evacuation occurred. We examine whether the main factor in reducing the effectiveness of the evacuation procedure was the lack of effective management or the behaviours among evacuees, or a combination of the two. Results of the analysis suggest that passengers reacted with solidarity, helped each other and that such spontaneous and pro-social behaviour possibly contributed to reduce the number of casualties. By contrast, competitive behaviours happened only in relation to specific environmental constraints and were limited to the proximity of safety boats. The deficiencies in command in the Costa Concordia evacuation highlights the need to increase the skills of personnel called to manage an emergency at sea and the need to create ad hoc training programs that consider also unexpected scenarios. Understanding how people (both staff and public) deal with an emergency and the factors that affect their decision is pivotal to help planners to review their strategy, anticipate similar events, and consider all the factors in future plans and regulations. While human error is always a big factor in maritime disaster, its impact can be considered and mitigated with specific procedures and adaptable plans

Emergent Endotracheal Intubation and Mortality in Traumatic Brain Injury

Objective: To determine the relationship between emergent intubation (emergency department and field intubation cases combined) and mortality in patients with traumatic brain injury (TBI) while controlling for injury severity.Methods: Retrospective observational study of 981 (35.2% intubated, 64.8% not intubated) patients with TBI evaluating the association between intubation status and mortality. Logistic regression was used to analyze the data. Injury severity measures included Head/Neck Abbreviated Injury Scale (H-AIS), systolic blood pressure, type of head injury (blunt vs. penetrating), and a propensity score combining the effects of several other potential confounding variables. Age was also included in the model.Results: The simple association of emergent endotracheal intubation with death had an odds ratio (OR) of 14.3 (95% CI = 9.4 – 21.9). The logistic regression model including relevant covariates and a propensity score that adjusted for injury severity and age yielded an OR of 5.9 (95% CI = 3.2 – 10.9).Conclusions: This study indicates that emergent intubation is associated with increased risk of death after controlling for a number of injury severity indicators. We discuss the need for optimal paramedic training, and an understanding of the factors that guide patient selection and the decision to intubate in the field. [WestJEM.2008;9:184-189

Parallel processing in immune networks

In this work we adopt a statistical mechanics approach to investigate basic, systemic features exhibited by adaptive immune systems. The lymphocyte network made by B-cells and T-cells is modeled by a bipartite spin-glass, where, following biological prescriptions, links connecting B-cells and T-cells are sparse. Interestingly, the dilution performed on links is shown to make the system able to orchestrate parallel strategies to fight several pathogens at the same time; this multitasking capability constitutes a remarkable, key property of immune systems as multiple antigens are always present within the host. We also define the stochastic process ruling the temporal evolution of lymphocyte activity, and show its relaxation toward an equilibrium measure allowing statistical mechanics investigations. Analytical results are compared with Monte Carlo simulations and signal-to-noise outcomes showing overall excellent agreement. Finally, within our model, a rationale for the experimentally well-evidenced correlation between lymphocytosis and autoimmunity is achieved; this sheds further light on the systemic features exhibited by immune networks.Comment: 21 pages, 9 figures; to appear in Phys. Rev.

An ArsR/SmtB family member regulates arsenic resistance genes unusually arranged in Thermus thermophilus HB27.

Arsenic resistance is commonly clustered in ars operons in bacteria; main ars operon components encode an arsenate reductase, a membrane extrusion protein, and an As-sensitive transcription factor. In the As-resistant thermophile Thermus thermophilus HB27, genes encoding homologues of these proteins are interspersed in the chromosome. In this article, we show that two adjacent genes, TtsmtB, encoding an ArsR/SmtB transcriptional repressor and, TTC0354, encoding a Zn2+/Cd2+-dependent membrane ATPase are involved in As resistance; differently from characterized ars operons, the two genes are transcribed from dedicated promoters upstream of their respective genes, whose expression is differentially regulated at transcriptional level. Mutants defective in TtsmtB or TTC0354 are more sensitive to As than the wild type, proving their role in arsenic resistance. Recombinant dimeric TtSmtB binds in vitro to both promoters, but its binding capability decreases upon interaction with arsenate and, less efficiently, with arsenite. In vivo and in vitro experiments also demonstrate that the arsenate reductase (TtArsC) is subjected to regulation by TtSmtB. We propose a model for the regulation of As resistance in T. thermophilus in which TtSmtB is the arsenate sensor responsible for the induction of TtArsC which generates arsenite exported by TTC0354 efflux protein to detoxify cells

Classification and nondegeneracy of SU(n+1)SU(n+1) Toda system with singular sources

We consider the following Toda system \Delta u_i + \D \sum_{j = 1}^n a_{ij}e^{u_j} = 4\pi\gamma_{i}\delta_{0} \text{in}\mathbb R^2, \int_{\mathbb R^2}e^{u_i} dx -1$,$\delta_0$is Dirac measure at 0, and the coefficients$a_{ij}$form the standard tri-diagonal Cartan matrix. In this paper, (i) we completely classify the solutions and obtain the quantization result:$$\sum_{j=1}^n a_{ij}\int_{\R^2}e^{u_j} dx = 4\pi (2+\gamma_i+\gamma_{n+1-i}), \;\;\forall\; 1\leq i \leq n.$$This generalizes the classification result by Jost and Wang for$\gamma_i=0$,$\forall \;1\leq i\leq n$. (ii) We prove that if$\gamma_i+\gamma_{i+1}+...+\gamma_j \notin \mathbb Z$for all$1\leq i\leq j\leq n$, then any solution$u_i$ is \textit{radially symmetric} w.r.t. 0. (iii) We prove that the linearized equation at any solution is \textit{non-degenerate}. These are fundamental results in order to understand the bubbling behavior of the Toda system.Comment: 28 page