Effect of body deformability on microswimming.

In this work we consider the following question: given a mechanical microswimming mechanism, does increased deformability of the swimmer body hinder or promote the motility of the swimmer? To answer this we run immersed-boundary-lattice-Boltzmann simulations of a microswimmer composed of deformable beads connected with springs. We find that the same deformations in the beads can result in different effects on the swimming velocity, namely an enhancement or a reduction, depending on the other parameters. To understand this we determine analytically the velocity of the swimmer, starting from the forces driving the motion and assuming that the deformations in the beads are known as functions of time and are much smaller than the beads themselves. We find that to the lowest order, only the driving frequency mode of the surface deformations contributes to the swimming velocity, and comparison to the simulations shows that both the velocity-promoting and velocity-hindering effects of bead deformability are reproduced correctly by the theory in the limit of small bead deformations. For the case of active deformations we show that there are critical values of the spring constant - which for a general swimmer corresponds to its main elastic degree of freedom - which decide whether the body deformability is beneficial for motion or not.

Characterization of antibiotic-resistant and potentially pathogenic Escherichia coli from soil fertilized with litter of broiler chickens fed antimicrobial-supplemented diets.

The objective of this study was to characterize antimicrobial resistance and virulence determinants of Escherichia coli from soil amended with litter from 36-day-old broiler chickens ( Gallus gallus domesticus ) fed with diets supplemented with a variety of antimicrobial agents. Soil samples were collected from plots before and periodically after litter application in August to measure E. coli numbers. A total of 295 E. coli were isolated from fertilized soil samples between August and March. Antibiotic susceptibility was determined by Sensititre, and polymerase chain reaction was performed to detect the presence of resistance and virulence genes. The results confirmed that E. coli survived and could be quantified by direct plate count for at least 7 months in soil following litter application in August. The effects of feed supplementation were observed on E. coli numbers in November and January. Among the 295 E. coli, the highest antibiotic resistance level was observed against tetracycline and ß-lactams associated mainly with the resistance genes tetB and bla(CMY-2), respectively. Significant treatment effects were observed for phylogenetic groups, antibiotic resistance profiles, and virulence gene frequencies. Serotyping, phylogenetic grouping, and pulsed-field gel electrophoresis confirmed that multiple-antibiotic-resistant and potentially pathogenic E. coli can survive in soil fertilized with litter for several months regardless of antimicrobials used in the feed.

Supporter-focused early intervention for recent sexual assault survivors: Study protocol for a pilot randomized clinical trial.

INTRODUCTION: Sexual assault is a common form of trauma that is associated with elevated risk for negative psychosocial outcomes. Although survivors' social relationships could serve as a major protective factor against negative outcomes, survivors' supporters often lack knowledge regarding effective responses and may inadvertently respond in ways that are detrimental to healing. Communication and Recovery Enhancement (CARE) is a 2-session early intervention for survivors of a past-10-week sexual assault and their supporters that aims to improve supporters' ability to respond effectively. OBJECTIVE: In this paper, we present a study protocol for a pilot randomized clinical trial of CARE (NCT05345405). The goal of this pilot trial is to understand the feasibility, acceptability, and preliminary efficacy of two versions of CARE: a version in which survivors and supporters attend sessions together (dyadic version) and a version in which supporters attend sessions alone (supporter-only version). METHODS: Survivors aged 14+ with elevated posttraumatic stress will enroll with a supporter of their choosing. Dyads will be randomized to dyadic CARE, supporter-only CARE, or waitlist control, and will complete self-report assessments at baseline, post-session-1, and follow-ups (1, 2, and 3 months post-baseline). We will use descriptive statistics, effect sizes, and exploratory statistical tests to characterize the acceptability of both CARE versions, impact on knowledge change from baseline to 1 month, impact on disclosure experiences at 1 month, and impact on functional outcomes at 3 months. DISCUSSION: Results will be used to inform future changes to CARE and determine whether a fully-powered randomized controlled trial is warranted.