Non-equilibrium Lorentz gas on a curved space

The periodic Lorentz gas with external field and iso-kinetic thermostat is equivalent, by conformal transformation, to a billiard with expanding phase-space and slightly distorted scatterers, for which the trajectories are straight lines. A further time rescaling allows to keep the speed constant in that new geometry. In the hyperbolic regime, the stationary state of this billiard is characterized by a phase-space contraction rate, equal to that of the iso-kinetic Lorentz gas. In contrast to the iso-kinetic Lorentz gas where phase-space contraction occurs in the bulk, the phase-space contraction rate here takes place at the periodic boundaries

Heat transport in stochastic energy exchange models of locally confined hard spheres

We study heat transport in a class of stochastic energy exchange systems that characterize the interactions of networks of locally trapped hard spheres under the assumption that neighbouring particles undergo rare binary collisions. Our results provide an extension to three-dimensional dynamics of previous ones applying to the dynamics of confined two-dimensional hard disks [Gaspard P & Gilbert T On the derivation of Fourier's law in stochastic energy exchange systems J Stat Mech (2008) P11021]. It is remarkable that the heat conductivity is here again given by the frequency of energy exchanges. Moreover the expression of the stochastic kernel which specifies the energy exchange dynamics is simpler in this case and therefore allows for faster and more extensive numerical computations.Comment: 21 pages, 5 figure

Review:Mitigating the risks posed by intensification in livestock production: the examples of antimicrobial resistance and zoonoses

Major shifts in how animals are bred, raised and slaughtered are involved in the intensification of livestock systems. Globally, these changes have produced major increases in access to protein-rich foods with high levels of micronutrients. Yet the intensification of livestock systems generates numerous externalities including environmental degradation, zoonotic disease transmission and the emergence of antimicrobial resistance (AMR) genes. Where the process of intensification is most advanced, the expertise, institutions and regulations required to manage these externalities have developed over time, often in response to hard lessons, crises and challenges to public health. By exploring the drivers of intensification, the foci of future intensification can be identified. Low- and middle-income (LMICs) countries are likely to experience significant intensification in livestock production in the near future; however, the lessons learned elsewhere are not being transferred rapidly enough to develop risk mitigation capacity in these settings. At present, fragmentary approaches to address these problems present an incomplete picture of livestock populations, antimicrobial use, and disease risks in LMIC settings. A worldwide improvement in evidence-based zoonotic disease and AMR management within intensifying livestock production systems demands better information on the burden of livestock-associated disease, antimicrobial use and resistance and resources allocated to mitigation.</p

Log-periodic drift oscillations in self-similar billiards

We study a particle moving at unit speed in a self-similar Lorentz billiard channel; the latter consists of an infinite sequence of cells which are identical in shape but growing exponentially in size, from left to right. We present numerical computation of the drift term in this system and establish the logarithmic periodicity of the corrections to the average drift

A Simple Method for Synchronising Multiple IMUs Using the Magnetometer

This paper presents a novel method to synchronise multiple IMU (inertial measurement units) devices using their onboard magnetometers. The method described uses an external electromagnetic pulse to create a known event measured by the magnetometer of multiple IMUs and in turn used to synchronise these devices. The method is applied to 4 IMU devices decreasing their de-synchronisation from 270ms when using only the RTC (real time clock) to 40ms over a 1 hour recording. It is proposed that this can be further improved to approximately 3ms by increasing the magnetometer’s sample frequency from 25Hz to 300Hz

Electromechanical characterization of a tissue-engineered myocardial patch derived from extracellular matrix

ObjectiveExtracellular matrix scaffolds have been successfully used for myocardial wall repair. However, regional functional evaluation (ie, contractility, electrical conductivity) of the extracellular matrix scaffold during the course of remodeling has been limited. In the present study, we evaluated the remodeled scaffold for evidence of electrical activation.MethodsThe extracellular matrix patch was implanted into the porcine right ventricular wall (n = 5) to repair an experimentally produced defect. Electromechanical mapping was performed with the NOGA system (Biosense Webster Inc, Diamond Bar, Calif) 60 days after implantation. Linear local shortening was recorded to assess regional contractility. After sacrifice, detailed histologic examinations were performed.ResultsHistologic examinations showed repopulation of the scaffold with cells, including a monolayer of factor VIII–positive cells in the endocardial surface and multilayered α-smooth muscle actin–positive cells beneath the monolayer cells. The α-smooth muscle actin–positive cells tended to be present at the endocardial aspect of the remodeled scaffold and at the border between the remodeled scaffold and the normal myocardium. Electromechanical mapping demonstrated that the patch had low-level electrical activity (0.56 ± 0.37 mV; P < .0001) in most areas and moderate activity (2.20 ± 0.70 mV; P < .0001) in the margin between the patch and the normal myocardium (7.58 ± 2.23 mV).ConclusionsThe extracellular matrix scaffolds were repopulated by α-smooth muscle actin–positive cells 60 days after implantation into the porcine heart. The presence of the cells corresponded to areas of the remodeling scaffold that showed early signs of electrical conductivity

Squid Resources of the Gulf of Mexico and Southeast Atlantic Coasts of the United States

Five species of commercially important squid occur in the southeastern fisheries region of the United States, which includes the northern Gulf of Mexico and the Atlantic coast south of Cape Hatteras. These are Lo/igo pealei, Doryteuthis plei, Lolliguncula brevis, IIlex illecebrosus and I. coindeti, although the last two species are usually not separated in the reported catches due to difficulty of identification. Although there is considerable overlap in the distributions, the species exhibit somewhat different seasonal patterns of distribution as well as differences in depth and temperature preferences. With the exception of Lolliguncula brevis which inhabits the shallow inshore waters, major concentrations appear to be associated with topographic features such as the Charleston Bump, which cause upwellings of nutrient-rich waters, or with the nutrient-laden water around the delta of the Mississippi River. Anecdotal information from surveys and commercial fishermen supports the existence of substantial stocks of squid in the Gulf of Mexico and along the Atlantic coast from southern Florida to Cape Hatteras

A Review of the Squid Resources of the Southeast Fisheries Region of the United States

The six species of commercially important squid in the Southeastern Fisheries Region, (Loligo pealei, Dorytheuthis plei, Lolliguncula brevis, Illex illecebrosus, I. coindeti and I. oxygonius) show separate seasonal distribution patterns and depth and temperature preferences. With the exception of Lolliguncula brevis, major concentrations are associated with topographic features which cause upwellings, such as the Charleston Bump, and resulting nutrient rich waters or nutrient laden waters around the delta of the Mississippi River. Anecdotal information from surveys and commercial fishermen support the presence of considerable stocks of squid in the Gulf of Mexico and along the Atlantic coasts of Florida and the Carolinas

The Origin And Loss Of Periodic Patterning In The Turtle Shell

The origin of the turtle shell over 200 million years ago greatly modified the amniote body plan, and the morphological plasticity of the shell has promoted the adaptive radiation of turtles. The shell, comprising a dorsal carapace and a ventral plastron, is a layered structure formed by basal endochondral axial skeletal elements (ribs, vertebrae) and plates of bone, which are overlain by keratinous ectodermal scutes. Studies of turtle development have mostly focused on the bones of the shell; however, the genetic regulation of the epidermal scutes has not been investigated. Here, we show that scutes develop from an array of patterned placodes and that these placodes are absent from a soft-shelled turtle in which scutes were lost secondarily. Experimentally inhibiting Shh, Bmp or Fgf signaling results in the disruption of the placodal pattern. Finally, a computational model is used to show how two coupled reaction-diffusion systems reproduce both natural and abnormal variation in turtle scutes. Taken together, these placodal signaling centers are likely to represent developmental modules that are responsible for the evolution of scutes in turtles, and the regulation of these centers has allowed for the diversification of the turtle shell