Fluidization and Active Thinning by Molecular Kinetics in Active Gels

We derive the constitutive equations of an active polar gel from a model for the dynamics of elastic molecules that link polar elements. Molecular binding kinetics induces the fluidization of the material, giving rise to Maxwell viscoelasticity and, provided that detailed balance is broken, to the generation of active stresses. We give explicit expressions for the transport coefficients of active gels in terms of molecular properties, including nonlinear contributions on the departure from equilibrium. In particular, when activity favors linker unbinding, we predict a decrease of viscosity with activity - active thinning - of kinetic origin, which could explain some experimental results on the cell cortex. By bridging the molecular and hydrodynamic scales, our results could help understand the interplay between molecular perturbations and the mechanics of cells and tissues.Comment: 6 pages, 2 figure

Analysis of the Nevada Test Site Early Warning System for Groundwater Contamination Potentially Migrating from Pahute Mesa to Oasis Valley, Nevada

This report is a limited technical analysis of the efficacy of the federal government\u27s groundwater monitoring program down gradient of the northwestern section of the NTS (Nevada Test Site), and its ability to provide early detection and warning of radioactivity in water in time to prevent harm to people and the environment. Concern over the efficacy of the groundwater monitoring program was triggered by the federal government\u27s repeated implication that since no radioactive contamination from underground nuclear tests had ever been detected in any of the water source locations they sampled around the NTS, then no contaminated water exists off site of the NTS. A more specific concern for this work is whether citizens and the environment near the western periphery of the NTS are being protected from radioactive groundwater contamination that is potentially migrating towards them from the nuclear tests detonated beneath the surface of the NTS on Pahute Mesa. This research was completed money allocated during Round 1 of the Citizens’ Monitoring and Technical Assessment Fund (MTA Fund). Clark University was named conservator of these works. If you have any questions or concerns please contact us at [email protected]://commons.clarku.edu/citizen_alert/1000/thumbnail.jp

Fingering instability of active nematic droplets

From the mitotic spindle up to tissues and biofilms, many biological systems behave as active droplets, which often break symmetry and change shape spontaneously. Here, I show that active nematic droplets can experience a fingering instability. I consider an active fluid that acquires nematic order through anchoring at the droplet interface, and I predict its morphological stability in terms of three dimensionless parameters: the anchoring angle, the penetration length of nematic order compared to droplet size, and an active capillary number. Droplets with extensile (contractile) stresses and planar (homeotropic) anchoring are unstable above a critical activity or droplet size. This instability is interfacial in nature: it arises through the coupling of active flows with interface motion, even when the bulk instability of active nematics cannot take place. In contrast to the dynamic states characteristic of active matter, the instability could produce static fingering patterns. The number of fingers increases with activity but varies non-monotonically with the nematic penetration length. Overall, these results pave the way towards understanding the self-organized shapes of biological systems, and towards designing patterns in active materials

Les campanyes de vacunació front al virus de la grip aviària, són eficaces?

Durant les últimes dècades s'han detectat brots de grip aviària causants d'una elevada mortalitat en aus, tant domèstiques com salvatges. La presència de virus de la influença (o grip) aviària d'alta patogenicitat (IAAP) suposa un risc elevat per l'economia i per la sanitat animal i humana. Per intentar prevenir i/o controlar futures epidèmies cal disposar de programes de control i vigilància del virus i de campanyes de vacunació adequades. Un estudi publicat recentment a la revista Clinical and Vaccine Immunology en el que han participat investigadors del Centre de Recerca en Sanitat Animal (CReSA), ha permès avaluar l'èxit de les campanyes de vacunació dutes a terme entre el 2006 i el 2008. Les dades es van recopilar dins un programa coordinat per l'Asociación Ibérica de Zoos y Acuarios i el Ministerio de Medio Ambiente y Medio Rural y Marino per avaluar l'eficàcia de la vacunació.Several avian influenza outbreaks have been reported to be responsible of high mortality in both domestic and wild birds. Highly pathogenic avian influenza (HPAI) viruses are a threat to the economy and animal and human health. Vaccination campaigns, together with good surveillance programs, are an important key to prevent and control future outbreaks. Researchers from Centre de Recerca en Sanitat Animal (CReSA) participated in a study published in Clinical and Vaccine Immunology with the objective to evaluate two vaccination campaigns carried out between 2006 and 2008. Data were collected during a program coordinated by the Iberic Association of Zoos and Aquariums (Asociación Ibérica de Zoos y Acuarios) and the Spanish Government to assess the efficacy of vaccination.Durante las últimas décadas se han detectado brotes de gripe aviar causantes de una elevada mortalidad en aves, tanto domésticas como salvajes. La presencia de virus de la influenza (o gripe) aviar de alta patogenicidad (IAAP) supone un riesgo elevado para la economía y para la sanidad animal y humana. Para intentar prevenir y / o controlar futuras epidemias es necesario disponer de programas de control y vigilancia del virus y de campañas de vacunación adecuadas. Un estudio publicado recientemente en la revista Clinical and Vaccine Immunology en el que han participado investigadores del Centro de Investigación en Sanidad Animal (CReSA), ha permitido evaluar el éxito de las campañas de vacunación llevadas a cabo entre 2006 y 2008. Los datos se recopilaron en un programa coordinado por la Asociación Ibérica de Zoos y Acuarios y el Ministerio de Medio Ambiente y Medio Rural y Marino para evaluar la eficacia de la vacunación

Resposta immunològica a la influença tipus A

Júlia Vergara Alert va defensar al CReSA-UAB el seu treball de tesi doctoral titulat "Immune response to influenza infection and vaccination", dirigit pel Dr. Ayub Darji. El principal objectiu d'aquesta tesi va ser estudiar la resposta immunològica causada per la infecció amb el virus de la influença tipus A (VIA) en models animals, amb l'objectiu final de dissenyar una vacuna front el VIA.Julia Vergara Alert defendió en el CReSA-UAB su trabajo de tesis doctoral titulado "Inmune Response to influenza infection and vaccination", dirigido por el Dr. Ayub Darji. El principal objetivo de esta tesis fue estudiar la respuesta inmunológica causada por la infección con el virus de la influenza tipo A (VIA) en modelos animales, con el objetivo final de diseñar una vacuna frente el VIA

Zoonotic diseases: Can the transmission of pathogens between animals and humans be controlled?

After being associated with more than six million deaths so far, the Covid-19 pandemic is one of the worst diseases of animal origin known to date. Other zoonotic diseases such as severe acute respiratory syndrome (2002–2004, which mainly affected China), Middle East respiratory syndrome (2012, mainly affecting the Middle East), Ebola (2013–2016 in West Africa), and Rift Valley fever (from 2016 to the present) have also caused major disease outbreaks in recent decades. In addition, and especially in low-income countries, some zoonotic diseases such as tuberculosis and rabies are endemic and cause thousands of deaths. Of note, up to 60 % of known infectious diseases and 75 % of emerging infectious diseases have an animal origin and are responsible for public health problems and economic losses.info:eu-repo/semantics/publishedVersio