759 research outputs found

    RADIAL ELECTRIC FIELDS AND TRANSPORT BARRIERS

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    A Call to Action: Lessons from Ukraine for the Future Force

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    Fifty years ago, the US Army faced a strategic inflection point after a failed counterinsurgency effort in Vietnam. In response to lessons learned from the Yom Kippur War, the United States Army Training and Doctrine Command was created to reorient thinking and doctrine around the conventional Soviet threat. Today’s Army must embrace the Russo-Ukrainian conflict as an opportunity to reorient the force into one as forward-thinking and formidable as the Army that won Operation Desert Storm. This article suggests changes the Army should make to enable success in multidomain large-scale combat operations at today’s strategic inflection point

    Experimental analysis of the particle transport in the magnetized plasma column with an application to the helicon discharge

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    International audienceDifferent transport mechanisms in a magnetized radio frequency plasmadischarge in the IShTAR device are compared. The total cross fieldparticle transport systematically shows the best agreement with theturbulent diffusion. Also, the ion mobility dominated transport couldsubstantially contribute to radial losses. The relative role of paralleland perpendicular losses in the overall particle confinement is alsocompared. The total perpendicular particle losses are comparable or evenlarger than the parallel ones, imposing a practical limitation onachieving high density plasma simply combining several helicon antennaesequentially arranged along the glass tube. For the same reason,reducing the diameter of a source tube, in an attempt to achieve ahigher plasma density, could be not very efficient when perpendicularparticle loss is dominant

    Comparison of Edge and Internal Transport Barriers in Drift Wave Predictive Simulations

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    We have simulated the formation of an internal transport barrier on JET including a self-consistent treatment of ion and electron temperatures and poloidal and toroidal momentum. Similar simulations of edge transport barriers, including the L-H transition have also been made. However, here only polodal momentum and the temperatures were simulated. The internal barrier included an anomalous spinup of poloidal momentum similar to that in the experiment. Also the edge barrier was accompanied by a spinup of poloidal momentum. The experimental density (with no barrier) was used and kept fixed for the internal barrier. For the edge barrier the edge density was varied and it turned out that a lower edge density gave a stronger barrier. Electromagnetic and nonlocal effects were important for both types of barriers

    Identification of a highly transmissible animal-independent Staphylococcus aureus ST398 clone with distinct genomic and cell adhesion properties.

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    A methicillin-resistant Staphylococcus aureus (MRSA) clone known as ST398 has emerged as a major cause of acute infections in individuals who have close contact with livestock. More recently, the emergence of an animal-independent ST398 methicillin-sensitive S. aureus (MSSA) clone has been documented in several countries. However, the limited surveillance of MSSA has precluded an accurate assessment of the global spread of ST398 and its clinical relevance. Here we provide evidence that ST398 is a frequent source of MSSA infections in northern Manhattan and is readily transmitted between individuals in households. This contrasts with the limited transmissibility of livestock-associated ST398 (LA-ST398) MRSA strains between humans. Our whole-genome sequence analysis revealed that the chromosome of the human-associated ST398 MSSA clone is smaller than that of the LA-ST398 MRSA reference strain S0385, due mainly to fewer mobile genetic elements (MGEs). In contrast, human ST398 MSSA isolates harbored the prophage Ï•3 and the human-specific immune evasion cluster (IEC) genes chp and scn. While most of the core genome was conserved between the human ST398 MSSA clone and S0385, these strains differed substantially in their repertoire and composition of intact adhesion genes. These genetic changes were associated with significantly enhanced adhesion of human ST398 MSSA isolates to human skin keratinocytes and keratin. We propose that the human ST398 MSSA clone can spread independent of animal contact using an optimized repertoire of MGEs and adhesion molecules adapted to transmission among humans

    Does insecticide resistance contribute to heterogeneities in malaria transmission in The Gambia?

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    BACKGROUND: Malaria hotspots, areas with consistently higher than average transmission, may become increasingly common as malaria declines. This phenomenon, currently observed in The Gambia, may be caused by several factors, including some related to the local vectors, whose contribution is poorly understood. METHODS: Using WHO susceptibility bioassays, insecticide resistance status was determined in vector populations sampled from six pairs of villages across The Gambia, each pair contained a low and high prevalence village. RESULTS: Three vector species were observed (23.5% Anopheles arabiensis, 31.2% Anopheles gambiae, 43.3% Anopheles coluzzii and 2.0% An. coluzzii × An. gambiae hybrids). Even at a fine scale, significant differences in species composition were detected within village pairs. Resistance to both DDT and deltamethrin was more common in An. gambiae, most markedly in the eastern part of The Gambia and partly attributable to differing frequencies of resistance mutations. The Vgsc-1014F target site mutation was strongly associated with both DDT (OR = 256.7, (95% CI 48.6-6374.3, p < 0.001) and deltamethrin survival (OR = 9.14, (95% CI 4.24-21.4, p < 0.001). A second target site mutation, Vgsc-1575Y, which co-occurs with Vgsc-1014F, and a metabolic marker of resistance, Gste2-114T, conferred additional survival benefits to both insecticides. DDT resistance occurred significantly more frequently in villages with high malaria prevalence (p = 0.025) though this did not apply to deltamethrin resistance. CONCLUSION: Whilst causality of relationships requires further investigation, variation in vector species and insecticide resistance in The Gambia is associated with malaria endemicity; with a notably higher prevalence of infection and insecticide resistance in the east of the country. In areas with heterogeneous malaria transmission, the role of the vector should be investigated to guide malaria control interventions

    Preliminary reports on the 2016-2017 excavation of the Neolithic ossuary and terrace

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    This article reports on the first three systematic excavation seasons at the Neolithic ossuary of Grotte de La Faucille, Belgium. The site was dated on human bone to 4266 ± 40 14C BP (3011-2702 cal BC; 2 sigma), corresponding to the transition from the late to the final Neolithic. The area excavated to date is clearly reworked and the individuals are distributed across the site. Further excavation will focus on the inferior levels at the entrance and inside the cave. This report presents the preliminary analysis of the anthropological and archaeological evidence recorded to date. Five archaeological artefacts were discovered made on bone, tooth and flint. The site has produced skeletal and dental remains of at least 12 humans (MNI 6 juveniles and 6 adults) as well as a number of bone and lithic artefacts. The skeletal remains are fragmentary and some elements, such as the cranium, are highly underrepresented given the number of individuals. The potential to find the remainder of at least 12 individuals is promising and continued excavation may result in one of the largest recent excavation of a multiple Neolithic burial site of the 21st century. The results presented here and ongoing analysis have the potential to significantly expand our understanding of the mortuary behaviours, or variation in behaviours, of the Belgian Neolithic and contribute further to the lively debate on the spread of the Neolithic
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