Effective dynamics of microorganisms that interact with their own trail

Like ants, some microorganisms are known to leave trails on surfaces to communicate. We explore how trail-mediated self-interaction could affect the behavior of individual microorganisms when diffusive spreading of the trail is negligible on the timescale of the microorganism using a simple phenomenological model for an actively moving particle and a finite-width trail. The effective dynamics of each microorganism takes on the form of a stochastic integral equation with the trail interaction appearing in the form of short-term memory. For moderate coupling strength below an emergent critical value, the dynamics exhibits effective diffusion in both orientation and position after a phase of superdiffusive reorientation. We report experimental verification of a seemingly counterintuitive perpendicular alignment mechanism that emerges from the model.Comment: new figure with experimental results; expanded appendi

The solar array-induced disturbance of the Hubble Space Telescope pointing system

The investigation of the vibrational disturbances of the Hubble Space Telescope that were discovered soon after deployment in orbit is described in detail. It was found that the disturbances were particularly evident during orbital day-night crossings, and that the magnitudes of the disturbances were considerably larger than the design jitter requirements. This paper describes the process by which the vibrations were characterized and isolated to a particular mechanism. The analysis of the flight data and comparisons with computer simulation results showed that the source of the disturbances was the thermally driven deformation of the solar arrays in conjunction with frictional effects in the array mechanisms. The control system was successfully modified to attenuate the disturbances to tolerable levels pending mechanical and thermal redesign of the solar arrays. The new arrays were installed during the first space telescope servicing mission and, in combination with the enhanced control system algorithm, reduced the disturbances to satisfactory levels

Preseason changes in markers of lower body fatigue and performance in young professional rugby union players

This study investigated the changes in measures of neuromuscular fatigue and physical performance in young professional rugby union players during a preseason training period. Fourteen young (age: 19.1 ± 1.2 years) professional rugby union players participated in the study. Changes in measures of lower body neuromuscular fatigue (countermovement jump (CMJ) mean power, mean force, flight-time) and physical performance (lower body strength, 40 m sprint velocity) were assessed during an 11-week preseason period using magnitude-based inferences. CMJ mean power was likely to very likely decreased during week 2 (-8.1 ± 5.5% to -12.5 ± 6.8%), and likely to almost certainly decreased from weeks 5 to 11 (-10 ± 4.3% to -14.7 ± 6.9%), while CMJ flight-time demonstrated likely to very likely decreases during weeks 2, and weeks 4-6 (-2.41 ± 1% to -3.3 ± 1.3%), and weeks 9-10 (-1.9 ± 0.9% to -2.2 ± 1.5%). Despite this, possible improvements in lower body strength (5.8 ± 2.7%) and very likely improvements in 40 m velocity (5.5 ± 3.6%) were made. Relationships between changes in CMJ metrics and lower body strength or 40 m sprint velocity were trivial or small (<0.22). Increases in lower body strength and 40 m velocity occurred over the course of an 11-week preseason despite the presence of neuromuscular fatigue (as measured by CMJ). The findings of this study question the usefulness of CMJ for monitoring fatigue in the context of strength and sprint velocity development. Future research is needed to ascertain the consequences of negative changes in CMJ in the context of rugby-specific activities to determine the usefulness of this test as a measure of fatigue in this population

Generalized Master Equations for Non-Poisson Dynamics on Networks

The traditional way of studying temporal networks is to aggregate the dynamics of the edges to create a static weighted network. This implicitly assumes that the edges are governed by Poisson processes, which is not typically the case in empirical temporal networks. Consequently, we examine the effects of non-Poisson inter-event statistics on the dynamics of edges, and we apply the concept of a generalized master equation to the study of continuous-time random walks on networks. We show that the equation reduces to the standard rate equations when the underlying process is Poisson and that the stationary solution is determined by an effective transition matrix whose leading eigenvector is easy to calculate. We discuss the implications of our work for dynamical processes on temporal networks and for the construction of network diagnostics that take into account their nontrivial stochastic nature

Анализ современной распределенной термометрии в процессе разработки месторождений Западной Сибири

Объектом исследования является технология распределенной оптоволоконной термометрии. Цель исследования – анализ применения распределенной оптоволоконной термометрии в процессе разработки на месторождениях Западной. В процессе исследования был проведен анализ возможностей современных систем мониторинга разработки месторождения на основе распределенных оптоволоконных. Рассмотрены технологии и используемых данным типом оборудования и возможности анализа данных поступающих при долговременном мониторинге. Учтены современные тренды, способствующие применению данной технологии в разработке месторождений.The object of research is the technology of distributed fiber optic thermometry. The purpose of the study is to analyze the use of distributed fiber optic thermometry in the development process at Western deposits. During the study, an analysis was made of the capabilities of modern field development monitoring systems based on distributed fiber optic systems. The technologies and the equipment used by this type of equipment and the possibilities of analyzing the data received during long-term monitoring are considered. Modern trends that contribute to the application of this technology in field development are taken into account

A comparison of game-play characteristics between elite youth and senior Australian National Rugby League competitions

Objectives: To compare game-play characteristics between elite youth and senior Australian National Rugby League (NRL) competitions. Design: Longitudinal observational. Methods: The dataset consisted of 12 team performance indicators (e.g., ‘all runs’, ‘offloads’ and ‘tackles’) extracted from all 2016 national under 20 (U20) competition (elite youth; n = 372 observations) and National Rugby League (NRL) (elite senior; n = 378 observations) matches. Data was classified according to competition (Two levels: U20 and NRL) and modelled using two techniques. Firstly, non-metric multidimensional scaling resolved multivariate competition (dis)similarity, visualised using a two-dimensional ordination. Secondly, a conditional interference (CI) classification tree was grown to reveal the performance indicators most capable of explaining competition level. Results: Non-metric multidimensional scaling revealed high competition dissimilarity, with U20 and NRL teams orienting distinctive positions on the first dimension of the ordination surface. Five team performance indicators were retained within the CI tree (‘all runs’, ‘tackle breaks’, ‘tackles’, ‘missed tackles’, and ‘kicks’), which correctly classified 79% of the U20 observations and 93% of the NRL observations. Conclusions: Multivariate differences between elite youth and senior rugby league competitions were identified. Specifically, NRL game-play was classified by a greater number of ‘all runs’, and ‘tackles’ and a lower number of ‘missed tackles’ relative to the U20 competition. Given the national U20 competition is purported to assist with the development of prospective NRL players, junior coaches may consider training interventions that primarily aid the tackling capacities of players. This may subsequently assist with talent development and player progression in Australian rugby league

Complement depletion and persistent hemodynamic-hematologic responses in protamine-heparin reactions

Hypotension, bradycardia, pulmonary artery hypertension, neutropenia, and thrombocytopenia have been suspected to be due to complement activation following protamine reversal of heparin. This investigation examined these phenomena in complement-depleted animals. Eight dogs received intraperitoneal naja n. naja cobra venom factor (CVF), 20 U/kg, 48 and 24 hr prior to anticoagulation with sodium heparin, 150 IU/kg, and reversal 30 min later with protamine sulfate, 1.5 mg/kg. Decomplementation was confirmed in all dogs. Systemic blood pressure (BP), pulse (HR), pulmonary artery systolic and diastolic pressures, (PAS, PAD), cardiac output (CO), platelet count (PTC), and white blood count (WBC) with differential were monitored. The maximal mean changes for the entire group were BP, -43 mm Hg; HR, -16; PAS, +6 mm Hg; PAD, +3 mm Hg; CO, -27%; PTC, -49%; and WBC, -48%. These hemodynamic and hematologic responses, occurring in the face of CVF-induced decomplementation, support the conclusion that complement components C3 and C5-C9 are not influential factors contributing to these protamine-heparin-induced events.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27158/1/0000153.pd

Validating child vaccination status in a demographic surveillance system using data from a clinical cohort study: evidence from rural South Africa

&lt;p&gt;&lt;b&gt;Background:&lt;/b&gt; Childhood vaccination coverage can be estimated from a range of sources. This study aims to validate vaccination data from a longitudinal population-based demographic surveillance system (DSS) against data from a clinical cohort study.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Methods:&lt;/b&gt; The sample includes 821 children in the Vertical Transmission cohort Study (VTS), who were born between December 2001 and April 2005, and were matched to the Africa Centre DSS, in northern KwaZulu-Natal. Vaccination information in the surveillance was collected retrospectively, using standardized questionnaires during bi-annual household visits, when the child was 12 to 23 months of age. DSS vaccination information was based on extraction from a vaccination card or, if the card was not available, on maternal recall. In the VTS, vaccination data was collected at scheduled maternal and child clinic visits when a study nurse administered child vaccinations. We estimated the sensitivity of the surveillance in detecting vaccinations conducted as part of the VTS during these clinic visits.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Results:&lt;/b&gt; Vaccination data in matched children in the DSS was based on the vaccination card in about two-thirds of the cases and on maternal recall in about one-third. The sensitivity of the vaccination variables in the surveillance was high for all vaccines based on either information from a South African Road-to-Health (RTH) card (0.94-0.97) or maternal recall (0.94-0.98). Addition of maternal recall to the RTH card information had little effect on the sensitivity of the surveillance variable (0.95-0.97). The estimates of sensitivity did not vary significantly, when we stratified the analyses by maternal antenatal HIV status. Addition of maternal recall of vaccination status of the child to the RTH card information significantly increased the proportion of children known to be vaccinated across all vaccines in the DSS.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Conclusion:&lt;/b&gt; Maternal recall performs well in identifying vaccinated children aged 12-23 months (both in HIV-infected and HIV-uninfected mothers), with sensitivity similar to information extracted from vaccination cards. Information based on both maternal recall and vaccination cards should be used if the aim is to use surveillance data to identify children who received a vaccination.&lt;/p&gt

Inhibition of Oesophageal Squamous Cell Carcinoma Progression by in vivo Targeting of Hyaluronan Synthesis

<p>Abstract</p> <p>Background</p> <p>Oesophageal cancer is a highly aggressive tumour entity with at present poor prognosis. Therefore, novel treatment options are urgently needed. Hyaluronan (HA) is a polysaccharide present in the matrix of human oesophageal squamous cell carcinoma (ESCC). Importantly, in vitro ESCC cells critically depend on HA synthesis to maintain the proliferative phenotype. The aim of the present study is (1) to study HA-synthase (HAS) expression and regulation in human ESCC, and (2) to translate the <it>in vitro </it>results into a mouse xenograft model of human ESCC to study the effects of systemic versus tumour targeted HAS inhibition on proliferation and distribution of tumour-bound and stromal hyaluronan.</p> <p>Methods</p> <p>mRNA expression was investigated in human ESCC biopsies by semiquantitative real-time RT PCR. Furthermore, human ESCC were xenografted into NMRI nu/nu mice. The effects on tumour progression and morphology of 4-methylumbelliferone (4-MU), an inhibitor of HA-synthesis, and of lentiviral knock down of HA-synthase 3 (HAS3), the main HAS isoform in the human ESCC tissues and the human ESCC cell line used in this study, were determined. Tumour progression was monitored by calliper measurements and by flat-panel detector volume computed tomography (fpVCT). HA content, cellular composition and proliferation (Ki67) were determined histologically.</p> <p>Results</p> <p>mRNA of HAS isoform 3 (HAS3) was upregulated in human ESCC biopsies and HAS3 mRNA was positively correlated to expression of the epidermal growth factor (EGF) receptor. EGF was also proven to be a strong inductor of HAS3 mRNA expression <it>in vitro</it>. During the course of seven weeks, 4-MU inhibited progression of xenograft tumours. Interestingly, remodelling of the tumour into a more differentiated phenotype and inhibition of cell proliferation were observed. Lentiviral knockdown of HAS3 in human ESCC cells prior to xenografting mimicked all effects of 4-MU treatment suggesting that hyaluronan produced by ESCC is accountable for major changes in tumour environment <it>in vivo</it>.</p> <p>Conclusions</p> <p>Systemic inhibition of HA-synthesis and knockdown of tumour cell HAS3 cause decreased ESCC progression accompanied by tumour stroma remodelling and may therefore be used in novel approaches to ESCC therapy.</p