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International Journal of Statistical Mechanics
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  This is an Open Access Journal Open Access journal
   ISSN (Print) 2356-7112 - ISSN (Online) 2314-6850
   This journal is no longer being updated because:
    Journal ceased publication
  • Survival Analysis of Loss to Follow-Up Treatment among Tuberculosis
           Patients at Jimma University Specialized Hospital, Jimma, Southwest
           Ethiopia

    • Abstract: Background. Tuberculosis (TB) patients who do not complete treatment pose a potential public health risk through disease reactivation, increased transmission, and development of drug-resistance. This study is aimed at analyzing the time to loss to follow-up treatment and risk factors among TB patients. Methods. This was a retrospective cohort study based on record review of 510 TB patients enrolled in Jimma University Specialized Hospital. The Cox’s proportional hazard model and Kaplan-Meier curves were used to model the outcome of interest. Loss to follow-up was used as an outcome measure. Results. Out of 510 TB patients, 69 (13.5%) were lost to follow-up (LTFU) treatment. The median times of survival starting from the date of treatment initiation were 5.7 months. The majority of LTFU patients interrupted treatment during continuation phase. Treatment LTFU has an association with HIV status, weight, and residence. However, living in the rural area has a cause for LTFU patients on multivariate analysis (HR 4.4, 95% CI 1.58–12.19). Conclusions. High rate of LTFU was observed among TB patients in Southwest Ethiopia. Treatment LTFU was more frequently observed among patients who came from rural areas. This underlines the need for distributing TB treatment to the rural area.
      PubDate: Thu, 31 Dec 2015 06:50:58 +000
       
  • Fractional Diffusion Equations for Lattice and Continuum:
           Gr├╝nwald-Letnikov Differences and Derivatives Approach

    • Abstract: Fractional diffusion equations for three-dimensional lattice models based on fractional-order differences of the Grünwald-Letnikov type are suggested. These lattice fractional diffusion equations contain difference operators that describe long-range jumps from one lattice site to another. In continuum limit, the suggested lattice diffusion equations with noninteger order differences give the diffusion equations with the Grünwald-Letnikov fractional derivatives for continuum. We propose a consistent derivation of the fractional diffusion equation with the fractional derivatives of Grünwald-Letnikov type. The suggested lattice diffusion equations can be considered as a new microstructural basis of space-fractional diffusion in nonlocal media.
      PubDate: Mon, 08 Dec 2014 13:16:25 +000
       
  • A Fractional Entropy in Fractal Phase Space: Properties and
           Characterization

    • Abstract: A two-parameter generalization of Boltzmann-Gibbs-Shannon entropy based on natural logarithm is introduced. The generalization of the Shannon-Khinchin axioms corresponding to the two-parameter entropy is proposed and verified. We present the relative entropy, Jensen-Shannon divergence measure and check their properties. The Fisher information measure, the relative Fisher information, and the Jensen-Fisher information corresponding to this entropy are also derived. Also the Lesche stability and the thermodynamic stability conditions are verified. We propose a generalization of a complexity measure and apply it to a two-level system and a system obeying exponential distribution. Using different distance measures we define the statistical complexity and analyze it for two-level and five-level system.
      PubDate: Wed, 24 Sep 2014 00:00:00 +000
       
  • The Statistical Mechanics of Random Set Packing and a Generalization of
           the Karp-Sipser Algorithm

    • Abstract: We analyse the asymptotic behaviour of random instances of the maximum set packing (MSP) optimization problem, also known as maximum matching or maximum strong independent set on hypergraphs. We give an analytic prediction of the MSPs size using the 1RSB cavity method from statistical mechanics of disordered systems. We also propose a heuristic algorithm, a generalization of the celebrated Karp-Sipser one, which allows us to rigorously prove that the replica symmetric cavity method prediction is exact for certain problem ensembles and breaks down when a core survives the leaf removal process. The -phenomena threshold discovered by Karp and Sipser, marking the onset of core emergence and of replica symmetry breaking, is elegantly generalized to for one of the ensembles considered, where is the size of the sets.
      PubDate: Mon, 10 Mar 2014 09:07:19 +000
       
  • An Independence Test Based on Symbolic Time Series

    • Abstract: An independence test based on symbolic time series analysis (STSA) is developed. Considering an independent symbolic time series there is a statistic asymptotically distributed as a CHI-2 with degrees of freedom. Size and power experiments for small samples were conducted applying Monte Carlo simulations and comparing the results with BDS and runs test. The introduced test shows a good performance detecting independence in nonlinear and chaotic systems.
      PubDate: Mon, 24 Feb 2014 07:49:50 +000
       
  • Exact Solution to the Extended Zwanzig Model for Quasi-Sigmoidal
           Chemically Induced Denaturation Profiles: Specific Heat and
           Configurational Entropy

    • Abstract: Temperature and chemically induced denaturation comprise two of the most characteristic mechanisms to achieve the passage from the native state to any of the unstructured states in the denatured ensemble in proteins and peptides. In this work we present a full analytical solution for the configurational partition function of a homopolymer chain poly-X in the extended Zwanzig model (EZM) for a quasisigmoidal denaturation profile. This solution is built up from an EZM exact solution in the case where the fraction of native contacts follows exact linear dependence on denaturant’s concentration ; thus an analytical solution for in the case of an exact linear denaturation profile is also provided. A recently established connection between the number of potential nonnative conformations per residue and temperature-independent helical propensity complements the model in order to identify specific proteinogenic poly-X chains, where X represents any of the twenty naturally occurring aminoacid residues. From , equilibrium thermodynamic potentials like entropy and average internal energy and thermodynamic susceptibilities like specific heat are calculated for poly-valine (poly-V) and poly-alanine (poly-A) chains. The influence of the rate at which native contacts denature as function of on thermodynamic stability is also discussed.
      PubDate: Thu, 23 Jan 2014 07:10:18 +000
       
 
 
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