2,435 research outputs found

    Density of States in Landau Level Tails of GaAs-AlxGa1-xAs Heterostructures

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    From an analysis of the thermally activated resistivity as a function of the magnetic field in the quantum Hall regime we deduced the position of the Fermi energy in the mobility gap as a function of the filling factor and therefore the density of states. The measured density of states is best described by a Gaussian like profile superimposed on a constant background

    The Strategic Assessment Model (STRATAM): Studying and Preventing Strategic Failure

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    The purpose of this study is to introduce the Strategic Assessment Model (STRATAM), a model designed to assist in the prevention of strategic failure. STRATAM aids firstly in the assessment of a strategy, as well as its crafting and evolution; secondly, it aims to enable and possibly streamline civil-military strategic debates on military operations. It is argued that strategic blunders in many cases result from latent organizational failures on one’s own side. Therefore, STRATAM combines Clausewitz’ theory of war and strategy with organizational failure theory. To demonstrate the use of this model, this paper uses Operation Cast Lead (or the Gaza War) of 2008-2009 as a case study. The paper’s findings include that the ultimate reasons for strategic failure were on one hand Clausewitzian; on the other hand, the Israeli Defense Force’s failure in organizational learning from a previous war two years earlier. The timely, strategic assessment and an effective civil-military debate about the effects of ongoing military operations might have prevented this failure. STRATAM would have provided the necessary language, structure, and relevance to identify actual and potential strategic failures with the goal to evolve the strategy

    Early protection against pathogenic virus infection at a mucosal challenge site after vaccination with attenuated simian immunodeficiency virus

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    Atraumatic application of attenuated SIVmac23Δnef vaccine to the tonsils of rhesus macaques provided protection against challenge 26 weeks later with infectious SIVmac251 applied through this route. Early events at the mucosal portal of entry of challenge virus were followed. Wild-type virus was detected in nonvaccinated controls by day 4, and then simian immunodeficiency virus (SIV) replicated vigorously at days 7 and 14. In contrast, a challenge of 10 of 10 vaccinees with SIV did not significantly raise RNA levels in the plasma or increase infected cells in lymphoid tissues, as assessed by single-cell labeling for viral RNA and nef protein. Vaccine virus was found in the tonsils of all vaccinees, but challenge virus was only detected at this portal of entry in 4 of 10 monkeys. In the tonsil, the challenge virus did not induce an expansion of perforin+ killer cells. However, there was a significant increase in γδ T cells and mature dendritic cells relative to unvaccinated controls. Therefore, during tonsillar SIVΔnef vaccination, infection is blocked early at the entry portal, which we propose is due in part to innate functions of γδ T and dendritic cells

    Current clinical practice in using adjunctive extracorporeal blood purification in sepsis and septic shock: results from the ESICM “EXPLORATION” survey

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    Background: Despite a lack of clear evidence extracorporeal blood purification (EBP) is increasingly used as an adjunctive treatment in septic shock based on its biological plausibility. However, current state of praxis and believes in both efficacy and level of evidence are very heterogeneous. Methods: The "EXPLORATION" (Current Clinical Practice in using adjunctive extracorporeal blood purification in septic shock), a web-based survey endorsed by the European Society of Intensive Care Medicine (ESICM), questioned both the current local clinical practices as well as future perspectives of EBP in sepsis and septic shock. Results: One hundred and two people participated in the survey. The majority of three quarters of participants (74.5%) use adjunctive EBP in their clinical routine with a varying frequency of description. Unselective cytokine adsorption (CA) (37.5%) and therapeutic plasma exchange (TPE) (34.1%) were by far the most commonly used modalities. While the overall theoretical rational was found to be moderate to high by the majority of the participants (74%), the effectively existing clinical evidence was acknowledged to be rather low (66%). Although CA was used most frequently in clinical practice, both the best existing clinical evidence endorsing its current use (45%) as well the highest potential to be explored in future clinical trials (51.5%) was attributed to TPE. Conclusions: Although the majority of participants use EBP techniques in their clinical practice and acknowledge a subjective good theoretical rationale behind it, the clinical evidence is assessed to be limited. While both CA and TPE are by far the most common used technique, both clinical evidence as well as future potential for further exploration in clinical trials was assessed to be the highest for TPE

    Modulating flowering time and prevention of pod shatter in oilseed rape

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    Floral induction is a key developmental switch in plants that leads to the production of flowers, fruits and seeds, which are of paramount importance for human life. To meet the demands of several crop harvests per year, or the growth of crop plants in regions with short vegetation times and for the production of ornamental plants, the timing of the floral transition is very important. The discovery of genes that are involved in flowering time control in model plants should allow the modulation of this developmental switch also in plants with economic value. By using a transgenic approach, we showed that a single MADS box gene accelerated flowering and seed ripening in summer rape plants. The MADSB transgene also partially substituted for the strict temperature requirements for flowering in winter rape plants. Transgenic winter rape plants expressing the MADSB transgene also produced more rigid siliques than wild type winter rape plants, and this prevented precocious seed dispersa
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