Trapping and sorting active particles: motility-induced condensation & smectic defects

We present an experimental realization of the collective trapping phase transition [Kaiser et al., PRL 108, 268307 (2012)], using motile polar granular rods in the presence of a V-shaped obstacle. We offer a theory of this transition based on the interplay of motility-induced condensation and liquid-crystalline ordering and show that trapping occurs when persistent influx overcomes the collective expulsion of smectic defect structures. In agreement with the theory, our experiments find that a trap fills to the brim when the trap angle $\theta$ is below a threshold $\theta_c$, while all particles escape for $\theta > \theta_c$. Our simulations support a further prediction, that $\theta_c$ goes down with increasing rotational noise. We exploit the sensitivity of trapping to the persistence of directed motion to sort particles based on the statistical properties of their activityComment: 6 pages, 5 figures, for supplementary mpg files, see "https://www.dropbox.com/sh/3cmswfoysdn0sb6/AACpEp-G3768B6Y62nDFj_Hea?dl=0". This paper supersedes our earlier version arXiv:1603.08535 and contains substantial new results including revised theoretical treatmen

Laplace Adomian Decomposition Method to study Chemical ion transport through soil

The paper deals with a theoretical study of chemical ion transport in soil under a uniform external force in the transverse direction, where the soil is taken as porous medium. The problem is formulated in terms of boundary value problem that consists of a set of partial differential equations, which is subsequently converted to a system of ordinary differential equations by applying similarity transformation along with boundary layer approximation. The equations hence obtained are solved by utilizing Laplace Adomian Decomposition Method (LADM). The merit of this method lies in the fact that much of simplifying assumptions need not be made to solve the non-linear problem. The decomposition parameter is used only for grouping the terms, therefore, the nonlinearities is handled easily in the operator equation and accurate approximate solution are obtained for the said physical problem. The computational outcomes are introduced graphically. By utilizing parametric variety, it has been demonstrated that the intensity of the external pressure extensively influences the flow behavior

Functional and radiological outcome in surgically managed posterior wall and column fractures of acetabulum

Background: The incidence of acetabular fractures has increased following road traffic accidents. The aim of the study is to evaluate functional and radiological outcome in surgically managed posterior wall and column fractures of acetabulum.Methods: This is a prospective study done at Nizam’s Institute of Medical Sciences, Hyderabad between May 2018 and May 2020. The sample size is 20 patients between the age group 18-60 years who presented to the hospital with closed posterior wall and/or column fractures of acetabulum with or without posterior dislocation of hip joint. Functional outcome is assessed by using the modified Merle D’ Aubigne Postel clinical grading system, radiological outcome by Matta et al and perioperative complication are assessed by retrospectively analyzing medical records and radiographics examination.Results: Functional outcome according to Merle D’ Aubigne and Postel score 16 patients (75%) showed good, 3 patients (20%) showed fair, 1 patient (5%) showed poor outcome. Radiological outcome according to Matta criteria, 16 patients (75%) showed excellent quality of joint reduction, 4 patients (25%) showed good quality of reduction of joint. There was significant correlation between anatomic reduction of the joint surface and functional outcome of the patient in our study (p value <0.05).Conclusions: Accurate joint reduction is of utmost importance in reduction of posterior wall or column fractures of acetabulum as posterior wall is the weight bearing zone. Functional outcome depends on fracture type, associated injuries, selection of patient, time between injury and surgery and postoperative rehabilitation

Active nonreciprocal attraction between motile particles in an elastic medium

We present a theory for the interaction between motile particles in an elastic medium on a substrate, relying on two arguments: a moving particle creates a strikingly fore-aft asymmetric distortion in the elastic medium; this strain field reorients other particles. We show that this leads to sensing, attraction and pursuit, with a non-reciprocal character, between a pair of motile particles. We confirm the predicted distortion fields and non-mutual trail-following in our experiments and simulations on polar granular rods made motile by vibration, moving through a dense monolayer of beads in its crystalline phase. Our theory should be of relevance to the interaction of motile cells in the extracellular matrix or in a supported layer of gel or tissue.Comment: Revised, experimental results added, SI expanded to include fits, some figures and bibliography modified, See Supplementary movies here https://www.dropbox.com/sh/od5lg00cxijk7b9/AAB3j6el7jFdaZ0q1xOo0Eqza?dl=

Prevalence of hypertension and its association with anthropometric parameters in adult population of Raipur city, Chhattisgarh, India

Background: Obesity is now an important emerging public health problem in India. It is one of the major risk factor for hypertension. Overweight persons have two to six fold increase in the risk of developing hypertension. This study was carried out with objective to find out prevalence of Hypertension and assess its association with four obesity-related indices- body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR).Methods: A cross-sectional community-based study was done among 640 study subjects of age group 25-59 years during July 2015 to June 2016. Multi stage random sampling method was used. Data collection was done using WHO STEPS instrument V 3.1. Privacy and confidentiality of data was maintained. Data was entered in the Microsoft excel, collected data was checked for its completeness and correctness before data analysis with the help of PSPP software.Results: Prevalence of hypertension among study subjects was found to be 22.19% (142 out of 640).With respect to body mass index, waist circumference, waist hip ratio and waist height ratio, 4.38%, 64.35%, 85.33%, 76.2% were found to be obese respectively. Hypertension was strongly associated with BMI (p<0.001), waist circumference (p<0.001), waist hip ratio (p<0.05), waist height ratio (p<0.05). Out of the four anthropometric variables waist hip ratio (WHR) was most strongly associated with hypertension (β=420.236, p=0.007).Conclusions: The study shows a rising burden of hypertension among study population. As WHR is the best indicator for measuring obesity, so measurement of WHR should be made compulsory in healthy life style clinics along with other parameters

Simulations of a weakly conducting droplet under the influence of an alternating electric field

We investigate the electrohydrodynamics of an initially spherical droplet under the influence of an external alternating electric field by conducting axisymmetric numerical simulations using a charge-conservative volume-of-fluid based finite volume flow solver. The mean amplitude of shape oscillations of a droplet subjected to an alternating electric field for leaky dielectric fluids is the same as the steady-state deformation under an equivalent root mean squared direct electric field for all possible electrical conductivity ratio $(K_r)$ and permittivity ratio $(S)$ of the droplet to the surrounding fluid. In contrast, our simulations for weakly conducting media show that this equivalence between alternating and direct electric fields does not hold for $K_r \ne S$. Moreover, for a range of parameters, the deformation obtained using the alternating and direct electric fields is qualitatively different, i.e. for low $K_r$ and high $S$, the droplet becomes prolate under alternating electric field but deforms to an oblate shape in the case of the equivalent direct electric field. A parametric study is conducted by varying the time period of the applied alternating electric field, the permittivity and the electrical conductivity ratios. It is observed that while increasing $K_r$ has a negligible effect on the deformation dynamics of the droplet for $K_r<S$, it enhances the deformation of the droplet when $K_r>S$ for both alternating and direct electric fields. We believe that our results may be of immense consequence in explaining the morphological evolution of droplets in a plethora of scenarios ranging from nature to biology.Comment: 10 pages, 8 figure

A Comparison of Methods for a Priori Bias Correction in Soil Moisture Data Assimilation

Data assimilation is being increasingly used to merge remotely sensed land surface variables such as soil moisture, snow and skin temperature with estimates from land models. Its success, however, depends on unbiased model predictions and unbiased observations. Here, a suite of continental-scale, synthetic soil moisture assimilation experiments is used to compare two approaches that address typical biases in soil moisture prior to data assimilation: (i) parameter estimation to calibrate the land model to the climatology of the soil moisture observations, and (ii) scaling of the observations to the model s soil moisture climatology. To enable this research, an optimization infrastructure was added to the NASA Land Information System (LIS) that includes gradient-based optimization methods and global, heuristic search algorithms. The land model calibration eliminates the bias but does not necessarily result in more realistic model parameters. Nevertheless, the experiments confirm that model calibration yields assimilation estimates of surface and root zone soil moisture that are as skillful as those obtained through scaling of the observations to the model s climatology. Analysis of innovation diagnostics underlines the importance of addressing bias in soil moisture assimilation and confirms that both approaches adequately address the issue