Molecular characterization of cultured Perkinsus marinus isolates

Perkinsus marinus is the causative agent of the oyster disease Dermo in the eastern oyster, Crassostrea virginica. In vitro propagation of the parasite has led to the establishment of multiple isolates by several investigators. Little work, however, has been done to characterize different isolates. In this study multiple isolates were examined for genetic and biochemical diversity. at two loci, the ITS region and the ATAN region, there was as much intra-isolate genetic variation among DNA sequences of some isolates as there was inter-isolate variation. Variation was also observed at a third loci, a subtilisin-like serine protease gene. This is the first report of a serine protease gene in P. marinus. In addition, a second, very similar subtilisin-like gene, may have also been isolated which was 95% similar in DNA sequence to the first and encoded amino acid changes in conserved regions. Examination of the extracellular proteins produced by eight P. marinus isolates from the Chesapeake Bay revealed differences in protein profiles, protease activity, protease profiles, growth rates, cell size and viability. The degree to which the differences observed were due to strain variation or to complex biochemical interactions of the parasite is unknown. However, isolates of similar viability, growth rates and cell size still had differences in protein and protease band profiles as well as in proteolytic activity, suggesting that there may be some genetic basis for the observed differences. The variation detected at both the genetic and molecular level suggests that multiple isolates should be examined when conducting biochemical and physiological studies on the parasite and for designing molecular diagnostic probes and PCR primers

Bifurcations and Chaos in Time Delayed Piecewise Linear Dynamical Systems

We reinvestigate the dynamical behavior of a first order scalar nonlinear delay differential equation with piecewise linearity and identify several interesting features in the nature of bifurcations and chaos associated with it as a function of the delay time and external forcing parameters. In particular, we point out that the fixed point solution exhibits a stability island in the two parameter space of time delay and strength of nonlinearity. Significant role played by transients in attaining steady state solutions is pointed out. Various routes to chaos and existence of hyperchaos even for low values of time delay which is evidenced by multiple positive Lyapunov exponents are brought out. The study is extended to the case of two coupled systems, one with delay and the other one without delay.Comment: 34 Pages, 14 Figure

Sexual Selection for Male Mobility in a Giant Insect with Female‐Biased Size Dimorphism

Female-biased size dimorphism in which females are larger than males is prevalent in many animals, but the factors causing this pattern of dimorphism are still poorly understood. The agility hypothesis suggests that female-biased size dimorphism arises because smaller males are favoured in scramble competition for mates. Using radio telemetry, we assessed the agility hypothesis in the Cook Strait giant weta (Deinacrida rugosa), a species with strong female-biased size dimorphism, and tested the prediction that male traits promoting mobility (i.e. longer legs, smaller bodies) are useful in scramble competition for mates and thus promote reproductive success. Our predictions were supported: males with longer legs and smaller bodies exhibited greater mobility (daily linear displacement when not mating) and more mobile males had greater insemination success. No phenotypic traits predicted female mobility or insemination success. In species with female-biased size dimorphism, sexual selection on males is often considered to be weak compared to species in which males are large and/or possess weaponry. We found that male giant weta experience sexual selection intensities on par with males of a closely related harem-defending polygynous species, likely because of strong scramble competition with other males

The impact of security bollards on evacuation flow

Individual bollard and bollard arrays (BA) have become a common design of Vehicle Security Barriers surrounding crowded spaces, in particular busy rail and underground stations, airports and many key commercial and public buildings. While guidance on the general installation of BA is available this earlier advice did not take into consideration the potential impact a BA may have on pedestrian flow during emergency evacuation. To address this issue, FSEG in collaboration with the CPNI and DfT investigated the potential impact that security bollards may have on evacuation flows through a series of full-scale experiments. In total 50 trials were conducted over three days on two weekends in March 2013. The experiment for each unique trial set up was repeated three times in order to ensure that the collected data was repeatable and representative of the trial conditions. The trials took place in the Queen Anne Courtyard of the University of Greenwich. Some 630 participants were recruited to take part in the trials, of which 458 actually participated. The trials were designed to capture the conditions produced as the population left a simulated station exit: at the point of exit (Exit flow trials) and when this population is incident upon the BA (BA flow trials). These trials were designed to control a number of key parameters in order to explore two specific questions: How does BA stand-off distance impact exit flow? And how does the BA impact flow passing through the BA? A key finding from these trials is that if the BA stand-off distance is greater than 3m there is not expected to be any adverse impact on exit flow due to the presence of the BA. However, it is essential that the BA is sufficiently wide so that it does not restrict the natural diffusion of the crowd as it exits

Radio-telemetric evidence of migration in the gregarious but not the solitary morph of the Mormon cricket (Anabrus simplex : Orthoptera: Tettigoniidae

Abstract The Mormon cricket, Anabrus simplex, is one of just a few species of katydids (or bushcrickets, Orthoptera: Tettigoniidae) that, like migratory locusts, appear to have solitary and migratory morphs. Using radio telemetry we studied movements of individuals of two morphs of this flightless species. Individuals within each migratory band had similar rates of movements along similar directional headings whereas solitary individuals moved little and showed little evidence of directionality in movement. Our results also add to other recent radio-telemetry studies showing that flightless insects of 1-2 g in mass can be tracked successfully using these methods

Mutual Information for the Detection of Crush

Fatal crush conditions occur in crowds with tragic frequency. Event organizers and architects are often criticised for failing to consider the causes and implications of crush, but the reality is that both the prediction and prevention of such conditions offer a significant technical challenge. Full treatment of physical force within crowd simulations is precise but often computationally expensive; the more common method of human interpretation of results is computationally “cheap” but subjective and time-consuming. This paper describes an alternative method for the analysis of crowd behaviour, which uses information theory to measure crowd disorder. We show how this technique may be easily incorporated into an existing simulation framework, and validate it against an historical event. Our results show that this method offers an effective and efficient route towards automatic detection of the onset of crush

Rat adrenal uptake and metabolism of high density lipoprotein cholesteryl ester

Metabolism of high density lipoprotein (HDL) cholesteryl ester (CE) by cultured rat adrenal cells was studied. Addition of [3H]CE-HDL to cells pretreated with adrenocorticotrophin in lipoprotein poor media resulted in a time- and concentration-dependent accumulation of [3H]cholesteryl ester and production of [3H]cholesterol and [3H]corticosterone. HDL-CE metabolism could be described as the sum of a high affinity ([ HDL-cholesterol]1/2 max = 16 micrograms/ml) and low affinity ([ HDL-cholesterol]1/2 max greater than 70 micrograms/ml) process. [3H]Cholesterol was found both intracellularly and in the media. Accumulation of [3H]cholesteryl ester could not be attributed to uptake and re-esterification of unesterified cholesterol since addition of Sandoz 58-035, an inhibitor of acyl coenzyme A:cholesterol acyltransferase, did not prevent ester accumulation. Moreover, addition of chloroquine did not inhibit cholesteryl ester hydrolysis indicating that hydrolysis was not lysosomally mediated. Aminoglutethimide prevented conversion of [3H]CE-HDL to steroid hormones but did not inhibit [3H]cholesteryl ester uptake. Cellular accumulation of [3H] cholesteryl ester exceeded accumulation of 125I-apoproteins 5-fold at 1 h and 35-fold at 24 h indicating selective uptake of cholesteryl ester moiety. We conclude that rat adrenal cells possess a mechanism for selective uptake of HDL cholesteryl esters which provides substrate for steroidogenesis. These results constitute the first direct demonstration that cholesteryl esters in HDL can be used as steroidogenic substrate by the rat adrenal cortex

Positive Fluid Balance Is Associated with Higher Mortality and Prolonged Mechanical Ventilation in Pediatric Patients with Acute Lung Injury

Introduction. We analyzed a database of 320 pediatric patients with acute lung injury (ALI), to test the hypothesis that positive fluid balance is associated with worse clinical outcomes in children with ALI. Methods. This is a post-hoc analysis of previously collected data. Cumulative fluid balance was analyzed in ml per kilogram per day for the first 72 hours after ALI while in the PICU. The primary outcome was mortality; the secondary outcome was ventilator-free days. Results. Positive fluid balance (in increments of 10 mL/kg/24 h) was associated with a significant increase in both mortality and prolonged duration of mechanical ventilation, independent of the presence of multiple organ system failure and the extent of oxygenation defect. These relationships remained unchanged when the subgroup of patients with septic shock (n = 39) were excluded. Conclusions. Persistently positive fluid balance may be deleterious to pediatric patients with ALI. A confirmatory, prospective randomized controlled trial of fluid management in pediatric patients with ALI is warranted

A review of post-incident studies for wildland-urban interface fires

Abstract Post-incident studies provide direct and valuable information to further the scientific understanding of Wildland-Urban Interface (WUI) fires. Most post-incident studies involve data collection in the field (i.e. a "research field deployment"). In this review, technical reports of post-incident studies for WUI fire and other natural disasters were analyzed and professionals directly involved in WUI fire research field deployments were interviewed. The goal of this review is to provide a resource for future WUI studies regarding the development of safe and effective fieldwork procedures, the collection and integration of accurate and relevant data, and the establishment of practical lessons learned. Three main stages of WUI fire post-incident studies are identified and described in detail. Data collection methodologies, data attributes, logistical practices and lessons-learned were compiled from various past studies and are presented here in the context of application to WUI fire