Nonequilibrium Energy Transduction in Stochastic Strongly Coupled Rotary Motors

Living systems at the molecular scale are composed of many constituents with strong and heterogeneous interactions, operating far from equilibrium, and subject to strong fluctuations. These conditions pose significant challenges to efficient, precise, and rapid free energy transduction, yet nature has evolved numerous molecular machines that do just this. Using a simple model of the ingenious rotary machine FoF1-ATP synthase, we investigate the interplay between nonequilibrium driving forces, thermal fluctuations, and interactions between strongly coupled subsystems. This model reveals design principles for effective free energy transduction. Most notably, while tight coupling is intuitively appealing, we find that output power is maximized at intermediate-strength coupling, which permits lubrication by stochastic fluctuations with only minimal slippage.Comment: 17 pages, 12 figures. J. Phys. Chem. Lett., 202

Modulation of the F-actin cytoskeleton by c-Abl tyrosine kinase in cell spreading and neurite extension

The nonreceptor tyrosine kinase encoded by the c-Abl gene has the unique feature of an F-actin binding domain (FABD). Purified c-Abl tyrosine kinase is inhibited by F-actin, and this inhibition can be relieved through mutation of its FABD. The c-Abl kinase is activated by physiological signals that also regulate the actin cytoskeleton. We show here that c-Abl stimulated the formation of actin microspikes in fibroblasts spreading on fibronectin. This function of c-Abl is dependent on kinase activity and is not shared by c-Src tyrosine kinase. The Abl-dependent F-actin microspikes occurred under conditions where the Rho-family GTPases were inhibited. The FABD-mutated c-Abl, which is active in detached fibroblasts, stimulated F-actin microspikes independent of cell attachment. Moreover, FABD-mutated c-Abl stimulated the formation of F-actin branches in neurites of rat embryonic cortical neurons. The reciprocal regulation between F-actin and the c-Abl tyrosine kinase may provide a self-limiting mechanism in the control of actin cytoskeleton dynamics

Ecohealth interventions limit triatomine reinfestation following insecticide spraying in La Brea, Guatemala

In this study, we evaluate the effect of participatory Ecohealth interventions on domestic reinfestation of the Chagas disease vector Triatoma dimidiata after village-wide suppression of the vector population using a residual insecticide. The study was conducted in the rural community of La Brea, Guatemala between 2002 and 2009 where vector infestation was analyzed within a spatial data framework based on entomological and socio-economic surveys of homesteads within the village. Participatory interventions focused on community awareness and low-cost home improvements using local materials to limit areas of refuge and alternative blood meals for the vector within the home, and potential shelter for the vector outside the home. As a result, domestic infestation was maintained at ≤ 3% and peridomestic infestation at ≤ 2% for 5 years beyond the last insecticide spraying, in sharp contrast to the rapid reinfestation experienced in earlier insecticide only interventions. Copyright © 2013 by The American Society of Tropical Medicine and Hygiene

COVID-19 and its impacts: the situation in Niger republic

COVID-19 being a public health emergency of international concern has emerged in most African countries including Niger. Niger, a landlocked country, is tasked with controlling the pandemic. However, of the big challenges the country faced is the fragility of healthcare system which posed limitations to the fight against the virus. The virus overwhelmed the fragile healthcare system which led to inaccessibility of quality healthcare to the citizens coupled with issues of flooding and economic recession that happened during the pandemic. The healthcare sectored has further been crippled by exposure and infection of the already insufficient healthcare workers. In addition to this, there was the burden of NTDs and other communicable and non-communicable diseases that subverted the country in the depths of difficulties. As per the predictions of World Bank, the poverty curve is likely to escalate due to the outrageous impacts of COVID-19. Adding on to this, the occurrence of natural disasters such as flooding has further stretched the country. It's no coincidence that the country would confront plethora of challenges amidst the second wave. Therefore, timely decision and necessary interventions are needed to strengthen the country's fight against the pandemic. However, this is only feasible when Nigerien government, international allies and other wealthy nations work closely to ensure that the challenges faced by the healthcare system are tackled

Metal enrichment processes

There are many processes that can transport gas from the galaxies to their environment and enrich the environment in this way with metals. These metal enrichment processes have a large influence on the evolution of both the galaxies and their environment. Various processes can contribute to the gas transfer: ram-pressure stripping, galactic winds, AGN outflows, galaxy-galaxy interactions and others. We review their observational evidence, corresponding simulations, their efficiencies, and their time scales as far as they are known to date. It seems that all processes can contribute to the enrichment. There is not a single process that always dominates the enrichment, because the efficiencies of the processes vary strongly with galaxy and environmental properties.Comment: 18 pages, 8 figures, accepted for publication in Space Science Reviews, special issue "Clusters of galaxies: beyond the thermal view", Editor J.S. Kaastra, Chapter 17; work done by an international team at the International Space Science Institute (ISSI), Bern, organised by J.S. Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke

PCR reveals significantly higher rates of Trypanosoma cruzi infection than microscopy in the Chagas vector, Triatoma infestans: High rates found in Chuquisaca, Bolivia

<p>Abstract</p> <p>Background</p> <p>The Andean valleys of Bolivia are the only reported location of sylvatic <it>Triatoma infestans</it>, the main vector of Chagas disease in this country, and the high human prevalence of <it>Trypanosoma cruzi </it>infection in this region is hypothesized to result from the ability of vectors to persist in domestic, peri-domestic, and sylvatic environments. Determination of the rate of <it>Trypanosoma </it>infection in its triatomine vectors is an important element in programs directed at reducing human infections. Traditionally, <it>T. cruzi </it>has been detected in insect vectors by direct microscopic examination of extruded feces, or dissection and analysis of the entire bug. Although this technique has proven to be useful, several drawbacks related to its sensitivity especially in the case of small instars and applicability to large numbers of insects and dead specimens have motivated researchers to look for a molecular assay based on the polymerase chain reaction (PCR) as an alternative for parasitic detection of <it>T. cruzi </it>infection in vectors. In the work presented here, we have compared a PCR assay and direct microscopic observation for diagnosis of <it>T. cruzi </it>infection in <it>T. infestans </it>collected in the field from five localities and four habitats in Chuquisaca, Bolivia. The efficacy of the methods was compared across nymphal stages, localities and habitats.</p> <p>Methods</p> <p>We examined 152 nymph and adult <it>T. infestans </it>collected from rural areas in the department of Chuquisaca, Bolivia. For microscopic observation, a few drops of rectal content obtained by abdominal extrusion were diluted with saline solution and compressed between a slide and a cover slip. The presence of motile parasites in 50 microscopic fields was registered using 400× magnification. For the molecular analysis, dissection of the posterior part of the abdomen of each insect followed by DNA extraction and PCR amplification was performed using the TCZ1 (5' – CGA GCT CTT GCC CAC ACG GGT GCT – 3') and TCZ2 (5' – CCT CCA AGC AGC GGA TAG TTC AGG – 3') primers. Amplicons were chromatographed on a 2% agarose gel with a 100 bp size standard, stained with ethidium bromide and viewed with UV fluorescence.</p> <p>For both the microscopy and PCR assays, we calculated sensitivity (number of positives by a method divided by the number of positives by either method) and discrepancy (one method was negative and the other was positive) at the locality, life stage and habitat level. The degree of agreement between PCR and microscopy was determined by calculating Kappa (<it>k</it>) values with 95% confidence intervals.</p> <p>Results</p> <p>We observed a high prevalence of <it>T. cruzi </it>infection in <it>T. infestans </it>(81.16% by PCR and 56.52% by microscopy) and discovered that PCR is significantly more sensitive than microscopic observation. The overall degree of agreement between the two methods was moderate (Kappa = 0.43 ± 0.07). The level of infection is significantly different among communities; however, prevalence was similar among habitats and life stages.</p> <p>Conclusion</p> <p>PCR was significantly more sensitive than microscopy in all habitats, developmental stages and localities in Chuquisaca, Bolivia. Overall we observed a high prevalence of <it>T. cruzi </it>infection in <it>T. infestans </it>in this area of Bolivia; however, microscopy underestimated infection at all levels examined.</p

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO