Percolation-induced exponential scaling in the large current tails of random resistor networks

There is a renewed surge in percolation-induced transport properties of diverse nano-particle composites (cf. RSC Nanoscience & Nanotechnology Series, Paul O'Brien Editor-in-Chief). We note in particular a broad interest in nano-composites exhibiting sharp electrical property gains at and above percolation threshold, which motivated us to revisit the classical setting of percolation in random resistor networks but from a multiscale perspective. For each realization of random resistor networks above threshold, we use network graph representations and associated algorithms to identify and restrict to the percolating component, thereby preconditioning the network both in size and accuracy by filtering {\it a priori} zero current-carrying bonds. We then simulate many realizations per bond density and analyze scaling behavior of the complete current distribution supported on the percolating component. We first confirm the celebrated power-law distribution of small currents at the percolation threshold, and second we confirm results on scaling of the maximum current in the network that is associated with the backbone of the percolating cluster. These properties are then placed in context with global features of the current distribution, and in particular the dominant role of the large current tail that is most relevant for material science applications. We identify a robust, exponential large current tail that: 1. persists above threshold; 2. expands broadly over and dominates the current distribution at the expense of the vanishing power law scaling in the small current tail; and 3. by taking second moments, reproduces the experimentally observed power law scaling of bulk conductivity above threshold

Review of emergency obstetric hysterectomies at a tertiary care hospital

Background: Emergency obstetric hysterectomy refers to surgical removal of pregnant or recently pregnant uterus with the pregnancy in utero or due to complications of delivery. This surgery is usually done as a last resort in life threatening obstetric hemorrhage. Objective of present study was to determine the incidence, sociodemographic and obstetric factors and indications associated with emergency obstetric hysterectomies. Methods: A retrospective, analytical study was conducted over a period of five years in the department of obstetrics and Gynecology of Government Medical college Thiruvananthapuram. Kerala. All cases of obstetric hysterectomy done during the study period in this hospital were analysed after getting approval from the institutional ethical committee. Results: During the study period there were total number of 78613 deliveries in SATH. Emergency obstetric hysterectomy was done for 86 cases. Obstetric hysterectomy rate in SATH during the study period was 0.109% or 1.09/1000 deliveries. Atonic postpartum hemorrhage (55%) was the most common indication followed by placenta praevia (27%). Majority were referred cases. Conclusions: Emergency obstetric hysterectomy can be a lifesaving procedure when other medical and surgical methods fail to control obstetric hemorrhage. This study highlights the unpredictable need of this procedure, need for identifying the at-risk cases and early referral to higher center

Archimedes' law and its corrections for an active particle in a granular sea

We study the origin of buoyancy forces acting on a larger particle moving in a granular medium subject to horizontal shaking and its corrections before fluidization. In the fluid limit Archimedes' law is verified; before the limit memory effects counteract buoyancy, as also found experimentally. The origin of the friction is an excluded volume effect between active particles, which we study more exactly for a random walker in a random environment. The same excluded volume effect is also responsible for the mutual attraction between bodies moving in the granular medium. Our theoretical modeling proceeds via an asymmetric exclusion process, i.e., via a dissipative lattice gas dynamics simulating the position degrees of freedom of a low density granular sea.Comment: 22 pages,5 figure

Evaluation of an enhanced service for medication review with follow up in Swiss community pharmacies: Pre-post study protocol.

In Switzerland, 20,000 people are hospitalized each year as result of drug related problems (DRPs). The sources of DRPs can be related to patients' behavior (i.e., wrong administration) or to health processes (i.e., drug-drug interaction). No community pharmacy (CP) service focus on DRPs related to patients' behavior is currently recognized or remunerated in Switzerland. A medication review with follow up (MRF) has been developed to evaluate prescription and non-prescription medication. To evaluate the impact of MRF service for the identification and management DRPs associated to patients' behavior and to describe pharmaceutical interventions carried out through MRF. A pre-post intervention study with a cluster design and one intervention group will be carried out in CPs in the canton of Vaud (Switzerland) for 15 months. Volunteer pharmacists will be trained on the identification and management of DRPs related to patients' behavior. After training, they will include randomly selected adults taking four or more chronic drugs prescribed for at least three months prior to recruitment. Then, they will conduct three pharmacist-patient face-to-face consultations at 6-month intervals. Tasks will be differentiated by pharmacy technician or pharmacist to triage expired medication or to manage DRPs in a structured manner, respectively. The primary outcome is the identification of DRPs associated to patients' behavior. Secondary outcomes are to assess patients' medication knowledge, number of expired medications, interventions carried out by pharmacists and pharmacists' satisfaction. The study will begin in April 2023 in 19 to 35 pharmacies that will recruit at least 162 patients. A sub analysis will be carried out for patients with 65 years old or over. The MRF intervention features a training designed for an enhanced evaluation of patient's behavior towards their medication. The study will allow the assessment and management of DRPs in Swiss CPs with the support of the local health authorities and pharmacist association. Clinicaltrials.gov NCT05348538

Network-Based Assessments of Percolation-Induced Current Distributions in Sheared Rod Macromolecular Dispersions

Conducting high-aspect-ratio rods with 1-10 nm-scale diameters dispersed in poorly conducting matrices at extremely low, O(1%), volume fractions induce dramatic gains in bulk conductivity at rod percolation threshold. Experimentally [Nan, Shen, and Ma, Annu. Rev. Mater. Res., 40 (2010), pp. 131-151], bulk conductivity abandons the prepercolation, linear scaling with volume fraction that follows from homogenization theory [Zheng et al., Adv. Funct. Mater., 15 (2005), pp. 627-638], and then postpercolation jumps orders of magnitude to approach that of the pure rod macromolecular phase as predicted by classical percolation theory [Stauffer and Aharony, Introduction to Percolation Theory, CRC Press, Boca Raton, FL, 1994]. Our aim here is to use the orientational probability distribution functions from kinetic Brownian rod dispersion flow codes [Forest, Wang, and Zhou, Rheol. Acta, 44 (2004), pp. 80-93] to generate physical three-dimensional (3D) nanorod dispersions, followed by graph-theoretic algorithms applied to each realization to address two practical materials science questions that lie beyond the above theoretical results. How does bulk conductivity scale in the presence of anisotropy induced by shear film flow at and above rod percolation threshold? What are the statistical distributions of current within the rod phase? Our techniques reveal a robust exponential, large current tail of the current distribution above percolation threshold that persists over a wide range of shear rates and volume fractions; the exponential rates are spatially anisotropic, with different scaling in the flow, flow gradient, and vorticity axes of the film. The second moment of the computed current distributions furthermore captures and reproduces the bulk conductivity scaling seen experimentally. These results extend the scaling behavior for the classical setting of 3D lattice bond percolation [Shi et al., Multiscale Model. Simul., 11 (2013), pp. 1298-1310] to physical 3D nanorod dispersions with random centers of mass and shear-induced anisotropy in the rod orientational distribution. © 2014 Society for Industrial and Applied Mathematics

A Testing Based Extraction Algorithm for Identifying Significant Communities in Networks

A common and important problem arising in the study of networks is how to divide the vertices of a given network into one or more groups, called communities, in such a way that vertices of the same community are more interconnected than vertices belonging to different ones. We propose and investigate a testing based community detection procedure called Extraction of Statistically Significant Communities (ESSC). The ESSC procedure is based on p-values for the strength of connection between a single vertex and a set of vertices under a reference distribution derived from a conditional configuration network model. The procedure automatically selects both the number of communities in the network and their size. Moreover, ESSC can handle overlapping communities and, unlike the majority of existing methods, identifies “background” vertices that do not belong to a well-defined community. The method has only one parameter, which controls the stringency of the hypothesis tests. We investigate the performance and potential use of ESSC and compare it with a number of existing methods, through a validation study using four real network data sets. In addition, we carry out a simulation study to assess the effectiveness of ESSC in networks with various types of community structure, including networks with overlapping communities and those with background vertices. These results suggest that ESSC is an effective exploratory tool for the discovery of relevant community structure in complex network systems

Inflammatory cytokines IL-1β and TNF-α regulate p75NTR expression in CNS neurons and astrocytes by distinct cell-type-specific signalling mechanisms

The p75NTR (where NTR is neurotrophin receptor) can mediate many distinct cellular functions, including cell survival and apoptosis, axonal growth and cell proliferation, depending on the cellular context. This multifunctional receptor is widely expressed in the CNS (central nervous system) during development, but its expression is restricted in the adult brain. However, p75NTR is induced by a variety of pathophysiological insults, including seizures, lesions and degenerative disease. We have demonstrated previously that p75NTR is induced by seizures in neurons, where it induces apoptosis, and in astrocytes, where it may regulate proliferation. In the present study, we have investigated whether the inflammatory cytokines IL (interleukin)-1β and TNF-α (tumour necrosis factor-α), that are commonly elevated in these pathological conditions, mediate the regulation of p75NTR in neurons and astrocytes. We have further analysed the signal transduction pathways by which these cytokines induce p75NTR expression in the different cell types, specifically investigating the roles of the NF-κB (nuclear factor κB) and p38 MAPK (mitogen-activated protein kinase) pathways. We have demonstrated that both cytokines regulate p75NTR expression; however, the mechanisms governing this regulation are cytokine- and cell-type specific. The distinct mechanisms of cytokine-mediated p75NTR regulation that we demonstrate in the present study may facilitate therapeutic intervention in regulation of this receptor in a cell-selective manner

Air-sea interaction in the Bay of Bengal

Author Posting. © The Oceanography Society, 2016. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 29, no. 2 (2016): 28–37, doi:10.5670/oceanog.2016.36.Recent observations of surface meteorology and exchanges of heat, freshwater, and momentum between the ocean and the atmosphere in the Bay of Bengal are presented. These observations characterize air-sea interaction at 18°N, 89.5°E from December 2014 to January 2016 and also at other locations in the northern Bay of Bengal. Monsoonal variability dominated the records, with winds to the northeast in summer and to the southwest in winter. This variability included a strong annual cycle in the atmospheric forcing of the ocean in the Bay of Bengal, with the winter monsoon marked by sustained ocean heat loss resulting in ocean cooling, and the summer monsoon marked by strong storm events with dark skies and rain that also resulted in ocean cooling. The spring intermonsoon was a period of clear skies and low winds, when strong solar heating and weak wind-driven mixing led to ocean warming. The fall intermonsoon was a transitional period, with some storm events but also with enough clear skies and sunlight that ocean surface temperature rose again. Mooring and shipboard observations are used to examine the ability of model-based surface fluxes to represent air-sea interaction in the Bay of Bengal; the model-based fluxes have significant errors. The surface forcing observed at 18°N is also used together with a one-dimensional ocean model to illustrate the potential for local air-sea interaction to drive upper-ocean variability in the Bay of Bengal.Deployment of the WHOI mooring and R. Weller and J.T. Farrar were supported by the US Office of Naval Research, grant N00014-13-1-0453. N. Suresh Kumar and B. Praveen Kumar acknowledge the financial support from Ministry of Earth Sciences (MoES, Government of India)