Grassmann Integral Representation for Spanning Hyperforests

Given a hypergraph G, we introduce a Grassmann algebra over the vertex set, and show that a class of Grassmann integrals permits an expansion in terms of spanning hyperforests. Special cases provide the generating functions for rooted and unrooted spanning (hyper)forests and spanning (hyper)trees. All these results are generalizations of Kirchhoff's matrix-tree theorem. Furthermore, we show that the class of integrals describing unrooted spanning (hyper)forests is induced by a theory with an underlying OSP(1|2) supersymmetry.Comment: 50 pages, it uses some latex macros. Accepted for publication on J. Phys.

Explicit characterization of the identity configuration in an Abelian Sandpile Model

Since the work of Creutz, identifying the group identities for the Abelian Sandpile Model (ASM) on a given lattice is a puzzling issue: on rectangular portions of Z^2 complex quasi-self-similar structures arise. We study the ASM on the square lattice, in different geometries, and a variant with directed edges. Cylinders, through their extra symmetry, allow an easy determination of the identity, which is a homogeneous function. The directed variant on square geometry shows a remarkable exact structure, asymptotically self-similar.Comment: 11 pages, 8 figure

Ground-state properties of a supersymmetric fermion chain

We analyze the ground state of a strongly interacting fermion chain with a supersymmetry. We conjecture a number of exact results, such as a hidden duality between weak and strong couplings. By exploiting a scale free property of the perturbative expansions, we find exact expressions for the order parameters, yielding the critical exponents. We show that the ground state of this fermion chain and another model in the same universality class, the XYZ chain along a line of couplings, are both written in terms of the same polynomials. We demonstrate this explicitly for up to N = 24 sites, and provide consistency checks for large N. These polynomials satisfy a recursion relation related to the Painlev\'e VI differential equation, and using a scale-free property of these polynomials, we derive a simple and exact formula for their limit as N goes to infinity.Comment: v2: added more information on scaling function, fixed typo

Pattern of statin use in southern Italian primary care: Can prescription databases be used for monitoring long-term adherence to the treatment?

Objectives: We sought to evaluate the prescribing pattern of statins according to national and regional health policy interventions and to assess specifically the adherence to the therapy in outpatient setting in Southern Italy. Methods: A population-based study was performed on persons ≥15 years old, living in the catchment area of Caserta (Southern Italy), and registered in Arianna database between 2004 and 2010. Prevalence and incidence of new treatments with statins were calculated for each year and stratified by drug. Adherence to therapy was measured by Medication Possession Ratio. Sub-analyses by individual compound and type of cardiovascular prevention were performed. Results: From 2004 to 2010, the one-year prevalence of statin use increased from 44.9/1,000 inhabitants to 79.8/1,000, respectively, consistently with the incidence of new use from 16.2/1,000 to 19.5/1,000, except a slight decrease after criteria reimbursement revision

Context-Based File Block Classification

Part 2: FORENSIC TECHNIQUESInternational audienceBecause files are typically stored as sequences of data blocks, the file carving process in digital forensics involves the identification and collocation of the original blocks of files. Current file carving techniques that use the signatures of file headers and footers could be improved by first classifying each data block in the storage media as belonging to a given file type. Unfortunately, file block classification techniques tend to have low accuracy. One reason is that they do not account for compound files that contain subcomponents encoded as different data types. This paper presents a context-based classification approach that accounts for compound files and improves on block-by-block classification schemes by exploiting the contiguity of file blocks belonging to the same file on the storage media