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

Prediction of kidney survival in children with primary focal segmental glomerulosclerosis (a two-center study)

Background: Focal segmental glomerulosclerosis (FSGS) is one of the most common glomerulopathies in children leading to end stage renal disease (ESRD). Different values of median renal survival have been reported among different ethnicities and races. Many factors are assumed to be responsible for ESRD in these patients. In this study, we tried to determine median renal survival (MRS) and also some clinical and histopathological features predisposing FSGS patients to ESRD in two referral hospitals in Tehran. Methods: The study involved 103 FSGS patients (61 males and 42 females) with a mean age of 7.08 ± 0.68 years. The diagnosis was made based on kidney biopsies. All kidney biopsies were studied by light and immunofluorescent microscopes. Ocular grids (counting squares) were used as the standard method to calculate the percentage of cortical interstitial fibrosis (CIF). The percentage of glomerular sclerosis was presented as renal injury score. Glomerular filtration rate (GFR)�50 ml/min was considered as renal death or the end point. Patients were followed for 1 to 15 years, until occurrence of renal death. Results: The MRS was 9.04 ± 1.8 yrs. The renal survival reached 72, 47 and 17 after 5, 10 and 15 years, respectively. Univariate analysis showed significant reverse correlation (P50, peritubular fibrosis, periglomerular fibrosis, tubular atrophy and CIF�20. However, multivariate analysis revealed only a reverse correlation between renal survival with CIF�20 and also hypertension (P<0.0001 and P<0.05, respectively). Conclusions: In our patients, FSGS showed a rapid course towards ESRD compared with patients of western countries. Perhaps some ethnic and genetic factors such as angiotensin converting enzyme genotypes (ACE-DD) can be considered as a cause of this rapid progression. Also, we carried this study only on children and adolescents which might change the MRS results

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

Fungal peritonitis in Iranian children on continuous ambulatory peritoneal dialysis: a national experience.

INTRODUCTION. Fungal peritonitis (FP), causing catheter obstruction, dialysis failure, and peritoneal dysfunction, is a rare but serious complication of peritoneal dialysis. In this study, the frequency and risk factors of FP are evaluated in children who underwent peritoneal dialysis. MATERIALS AND METHODS. A retrospective multicenter study was performed at the 5 pediatric peritoneal dialysis centers in Iran from 1971 to 2006, and FP episodes among 93 children were reviewed. Risk ratios were calculated for the clinical and demographic variables to determine the risk factors of FP. RESULTS. Ninety-three children aged 39 months on average were included in study. Sixteen out of 155 episodes of peritonitis were fungi infections, all by Candida albicans. The risk of FP was higher in those with relapsing bacterial peritonitis (P = .009). Also, all of the patients had received antibiotics within the 1 month prior to the development of FP. Catheters were removed in all patients after 1 to 7 days of developing FP. Six out of 12 patients had catheter obstruction and peritoneal loss after the treatment and 5 died due to infection. CONCLUSIONS. Fungal peritonitis, accompanied by high morbidity and mortality in children should be reduced by prevention of bacterial peritonitis. Early removal of catheter after recognition of FP should be considered

Fungal peritonitis in Iranian children on continuous ambulatory peritoneal dialysis: a national experience.

INTRODUCTION. Fungal peritonitis (FP), causing catheter obstruction, dialysis failure, and peritoneal dysfunction, is a rare but serious complication of peritoneal dialysis. In this study, the frequency and risk factors of FP are evaluated in children who underwent peritoneal dialysis. MATERIALS AND METHODS. A retrospective multicenter study was performed at the 5 pediatric peritoneal dialysis centers in Iran from 1971 to 2006, and FP episodes among 93 children were reviewed. Risk ratios were calculated for the clinical and demographic variables to determine the risk factors of FP. RESULTS. Ninety-three children aged 39 months on average were included in study. Sixteen out of 155 episodes of peritonitis were fungi infections, all by Candida albicans. The risk of FP was higher in those with relapsing bacterial peritonitis (P = .009). Also, all of the patients had received antibiotics within the 1 month prior to the development of FP. Catheters were removed in all patients after 1 to 7 days of developing FP. Six out of 12 patients had catheter obstruction and peritoneal loss after the treatment and 5 died due to infection. CONCLUSIONS. Fungal peritonitis, accompanied by high morbidity and mortality in children should be reduced by prevention of bacterial peritonitis. Early removal of catheter after recognition of FP should be considered

The role of routine post-natal abdominal ultrasound for newborns in a resource-poor setting: a longitudinal study

<p>Abstract</p> <p>Background-</p> <p>Neonatal abdominal ultrasound is usually performed in Nigeria to investigate neonatal symptoms rather than as a follow up to evaluate fetal abnormalities which were detected on prenatal ultrasound. The role of routine obstetric ultrasonography in the monitoring of pregnancy and identification of fetal malformations has partly contributed to lowering of fetal mortality rates. In Nigeria which has a high maternal and fetal mortality rate, many pregnant women do not have ante-natal care and not infrequently, women also deliver their babies at home and only bring the newborns to the clinics for immunization. Even when performed, most routine obstetric scans are not targeted towards the detection of fetal abnormalities.</p> <p>The aim of the present study is to evaluate the benefit of routinely performing abdominal scans on newborns with a view to detecting possible abnormalities which may have been missed ante-natally.</p> <p>Methods-</p> <p>This was a longitudinal study of 202 consecutive, apparently normal newborns. Routine clinical examination and abdominal ultrasound scans were performed on the babies by their mother's bedside, before discharge. Neonates with abnormal initial scans had follow-up scans.</p> <p>Results-</p> <p>There were 108 males and 94 females. There were 12 (5.9%) abnormal scans seen in five male and seven female neonates. Eleven of the twelve abnormalities were in the kidneys, six on the left and five on the right. Three of the four major renal anomalies- absent kidney, ectopic/pelvic kidney and two cases of severe hydronephrosis were however on the left side. There was one suprarenal abnormality on the right suspected to be a possible infected adrenal haemorrage. Nine of the abnormal cases reported for follow- up and of these, two cases had persistent severe abnormalities.</p> <p>Conclusions-</p> <p>This study demonstrated a 5.9% incidence of genito urinary anomalies on routine neonatal abdominal ultrasound in this small population. Routine obstetric USS is very useful but inadequate availability of skilled personnel and cost implications create great challenges in poor resource settings like Nigeria. However, awareness should be created so that parents who can afford such investigations can make informed decisions.</p