Spatial Mixing and Non-local Markov chains

We consider spin systems with nearest-neighbor interactions on an $n$-vertex $d$-dimensional cube of the integer lattice graph $\mathbb{Z}^d$. We study the effects that exponential decay with distance of spin correlations, specifically the strong spatial mixing condition (SSM), has on the rate of convergence to equilibrium distribution of non-local Markov chains. We prove that SSM implies $O(\log n)$ mixing of a block dynamics whose steps can be implemented efficiently. We then develop a methodology, consisting of several new comparison inequalities concerning various block dynamics, that allow us to extend this result to other non-local dynamics. As a first application of our method we prove that, if SSM holds, then the relaxation time (i.e., the inverse spectral gap) of general block dynamics is $O(r)$, where $r$ is the number of blocks. A second application of our technology concerns the Swendsen-Wang dynamics for the ferromagnetic Ising and Potts models. We show that SSM implies an $O(1)$ bound for the relaxation time. As a by-product of this implication we observe that the relaxation time of the Swendsen-Wang dynamics in square boxes of $\mathbb{Z}^2$ is $O(1)$ throughout the subcritical regime of the $q$-state Potts model, for all $q \ge 2$. We also prove that for monotone spin systems SSM implies that the mixing time of systematic scan dynamics is $O(\log n (\log \log n)^2)$. Systematic scan dynamics are widely employed in practice but have proved hard to analyze. Our proofs use a variety of techniques for the analysis of Markov chains including coupling, functional analysis and linear algebra

First report on the percentiles of the glomerular filtration rate in iranian children using the 2009 schwartz equations

The glomerular filtration rate (GFR) is widely considered the best overall index of renal function. The Schwartz equations are designed for measuring the GFR in children between 1 and 16 years of age. In the present study, we investigated the percentiles of the GFR in a general population of Iranian children with no known renal disease via the 2009 Schwartz equations (updated and combined equations). Between 2010 and 2011, we selected 687 children aged 7�16 years from the Iranian province of Isfahan. Blood samples were analyzed for blood urea nitrogen, creatinine, and cystatin C. For each child, we calculated the GFR using 2 Schwartz equations. The Wilcoxon test was applied to examine the differences in the estimated GFRs between the equations. To determine the correlation between the GFRs obtained via the updated and combined Schwartz equations in the boys and the girls and also for the correlation between age and the GFR, we performed the Pearson or Spearman correlation coefficients. The statistical analyses were conducted using MedCalc, version 12.1.4.0 (MedCalc Software, Mariakerke, Belgium). The mean GFR was 100.06±19.80 mL/min/1.73 m2 based on the updated equation and 96.10±18.44 mL/min/1.73 m2 according to the combined equation. No significant differences were observed between these equations in estimating the GFRs. The correlation analysis for determining the association between age and the GFR estimated by the updated (r=0.05, P=0.1) and combined (r=0.06, P=0.09) Schwartz equations was not statistically significant. In conclusion, in the current study we showed that the updated and combined Schwartz equations exhibited high concordance in estimating GFR values in this age group. © 2018, Shiraz University of Medical Sciences. All rights reserved

First report on the percentiles of the glomerular filtration rate in iranian children using the 2009 schwartz equations

The glomerular filtration rate (GFR) is widely considered the best overall index of renal function. The Schwartz equations are designed for measuring the GFR in children between 1 and 16 years of age. In the present study, we investigated the percentiles of the GFR in a general population of Iranian children with no known renal disease via the 2009 Schwartz equations (updated and combined equations). Between 2010 and 2011, we selected 687 children aged 7�16 years from the Iranian province of Isfahan. Blood samples were analyzed for blood urea nitrogen, creatinine, and cystatin C. For each child, we calculated the GFR using 2 Schwartz equations. The Wilcoxon test was applied to examine the differences in the estimated GFRs between the equations. To determine the correlation between the GFRs obtained via the updated and combined Schwartz equations in the boys and the girls and also for the correlation between age and the GFR, we performed the Pearson or Spearman correlation coefficients. The statistical analyses were conducted using MedCalc, version 12.1.4.0 (MedCalc Software, Mariakerke, Belgium). The mean GFR was 100.06±19.80 mL/min/1.73 m2 based on the updated equation and 96.10±18.44 mL/min/1.73 m2 according to the combined equation. No significant differences were observed between these equations in estimating the GFRs. The correlation analysis for determining the association between age and the GFR estimated by the updated (r=0.05, P=0.1) and combined (r=0.06, P=0.09) Schwartz equations was not statistically significant. In conclusion, in the current study we showed that the updated and combined Schwartz equations exhibited high concordance in estimating GFR values in this age group. © 2018, Shiraz University of Medical Sciences. All rights reserved

Nature vs. Nurture: Dynamical Evolution in Disordered Ising Ferromagnets

We study the predictability of zero-temperature Glauber dynamics in various models of disordered ferromagnets. This is analyzed using two independent dynamical realizations with the same random initialization (called twins). We derive, theoretically and numerically, trajectories for the evolution of the normalized magnetization and twin overlap as the system size tends to infinity. The systems we treat include mean-field ferromagnets with light-tailed and heavy-tailed coupling distributions, as well as highly-disordered models with a variety of other geometries. In the mean-field setting with light-tailed couplings, the disorder averages out and the limiting trajectories of the magnetization and twin overlap match those of the homogenous Curie--Weiss model. On the other hand, when the coupling distribution has heavy tails, or the geometry changes, the effect of the disorder persists in the thermodynamic limit. Nonetheless, qualitatively all such random ferromagnets share a similar time evolution for their twin overlap, wherein the two twins initially decorrelate, before either partially or fully converging back together due to the ferromagnetic drift.Comment: 16 pages, 7 figure

Review of Person Re-identification Techniques

Person re-identification across different surveillance cameras with disjoint fields of view has become one of the most interesting and challenging subjects in the area of intelligent video surveillance. Although several methods have been developed and proposed, certain limitations and unresolved issues remain. In all of the existing re-identification approaches, feature vectors are extracted from segmented still images or video frames. Different similarity or dissimilarity measures have been applied to these vectors. Some methods have used simple constant metrics, whereas others have utilised models to obtain optimised metrics. Some have created models based on local colour or texture information, and others have built models based on the gait of people. In general, the main objective of all these approaches is to achieve a higher-accuracy rate and lowercomputational costs. This study summarises several developments in recent literature and discusses the various available methods used in person re-identification. Specifically, their advantages and disadvantages are mentioned and compared.Comment: Published 201

Congenital and childhood atrioventricular blocks: pathophysiology and contemporary management

Atrioventricular block is classified as congeni- tal if diagnosed in utero, at birth, or within the first month of life. The pathophysiological process is believed to be due to immune-mediated injury of the conduction system, which occurs as a result of transplacental pas- sage of maternal anti-SSA/Ro-SSB/La antibodies. Childhood atrioventricular block is therefore diagnosed between the first month and the 18th year of life. Genetic variants in multiple genes have been described to date in the pathogenesis of inherited progressive car- diac conduction disorders. Indications and techniques of cardiac pacing have also evolved to allow safe perma- nent cardiac pacing in almost all patients, including those with structural heart abnormalities

Person reidentification using spatiotemporal appearance

In many surveillance applications it is desirable to determine if a given individual has been previously observed over a network of cameras. This is the person reidentification problem. This paper focuses on reidentification algorithms that use the overall appearance of an individual as opposed to passive biometrics such as face and gait. Person reidentification approaches have two aspects: (i) establish correspondence between parts, and (ii) generate signatures that are invariant to variations in illumination, pose, and the dynamic appearance of clothing. A novel spatiotemporal segmentation algorithm is employed to generate salient edgels that are robust to changes in appearance of clothing. The invariant signatures are generated by combining normalized color and salient edgel histograms. Two approaches are proposed to generate correspondences: (i) a model based approach that fits an articulated model to each individual to establish a correspondence map, and (ii) an interest point operator approach that nominates a large number of potential correspondences which are evaluated using a region growing scheme. Finally, the approaches are evaluated on a 44 person database across 3 disparate views. © 2006 IEEE