Neutrino-induced coherent pion production off nuclei reexamined

It is pointed out that so far all theoretical estimates of coherent pion production off nuclei induced by neutrinos rely on the 'local approximation' well known in photonuclear physics. The effects of dropping this approximation are discussed. It is found that in a plane wave approximation for the pion the local approximation overestimates the coherent neutrino-induced pion production on nuclei.Comment: v3: comments on pion FSI added, minor corrections; version as published in Phys. Rev.

Parameterization for subgrid-scale motion of ice-shelf calving fronts

A parameterization for the motion of ice-shelf fronts on a Cartesian grid in finite-difference land-ice models is presented. The scheme prevents artificial thinning of the ice shelf at its edge, which occurs due to the finite resolution of the model. The intuitive numerical implementation diminishes numerical dispersion at the ice front and enables the application of physical boundary conditions to improve the calculation of stress and velocity fields throughout the ice-sheet-shelf system. Numerical properties of this subgrid modification are assessed in the Potsdam Parallel Ice Sheet Model (PISM-PIK) for different geometries in one and two horizontal dimensions and are verified against an analytical solution in a flow-line setup

Hormonal modifications in patients admitted to an internal intensive care unit for acute hypoxaemic respiratory failure

AbstractTo clarify which endocrine modifications can be observed in acute hypoxaemic respiratory failure, 15 severely ill male patients [PAT; median age: 61 (range: 48 years); median height: 173 (range: 12) cm; median mass: 73 (range 31) kg] were investigated immediately upon admission to an intensive care unit (ICU) for this clinical disorder. Before starting treatment, the blood gases were measured and a number of selected hormones with special relevance for an ICU setting were determined. These are known to be modified by acute hypoxaemia in healthy subjects and to possess glucoregulatory properties, or an influence upon cardiocirculation or the vascular volume regulation: insulin, cortisol, adrenaline, noradrenaline, atrial natriuretic peptide, renin, aldosterone, angiotensin converting enzyme, and endothelin-I (ET). To elucidate whether potential endocrine changes resulted from acute hypoxaemia alone, the underlying disease, or unspecific influences connected with the ICU setting, all measurements were compared to those of a completely healthy reference group (REF) with comparable acute experimental hypoxaemia. The latter state was achieved by having the REF breathe a gas mixture with the oxygen content reduced to 14% (H).In the REF, neither the medians nor the distribution of endocrinologic measurements were modified significantly by acute hypoxaemia. In the PAT, the medians were increased considerably, yet with a slight diminution of ET. The distribution of individual values was considerably broader than in the REF with H.In conclusion, considerable increases in the means of the above hormones, with the exception of ET, can be registered in severely ill patients admitted to ICUs with acute hypoxaemic failure. However, such modifications cannot be considered attributable exclusively to acute arterial hypoxaemia. The underlying clinical disorders, such as septicaemia or an unspecific endocrine epiphenomenon, including severe and not only hypoxaemic stress, seem to be predominant

Parameterization for subgrid-scale motion of ice-shelf calving fronts

In order to explore the response of the Greenland ice sheet (GIS) to climate change on long (centennial to multi-millennial) time scales, a regional energy-moisture balance model has been developed. This model simulates seasonal variations of temperature and precipitation over Greenland and explicitly accounts for elevation and albedo feedbacks. From these fields, the annual mean surface temperature and surface mass balance can be determined and used to force an ice sheet model. The melt component of the surface mass balance is computed here using both a positive degree day approach and a more physically-based alternative that includes insolation and albedo explicitly. As a validation of the climate model, we first simulated temperature and precipitation over Greenland for the prescribed, present-day topography. Our simulated climatology compares well to observations and does not differ significantly from that of a simple parameterization used in many previous simulations. Furthermore, the calculated surface mass balance using both melt schemes falls within the range of recent regional climate model results. For a prescribed, ice-free state, the differences in simulated climatology between the regional energy-moisture balance model and the simple parameterization become significant, with our model showing much stronger summer warming. When coupled to a three-dimensional ice sheet model and initialized with present-day conditions, the two melt schemes both allow realistic simulations of the present-day GIS

Delayed Blanch Phenomenon in Children: Reevaluation Of 5-Year-old Children Originally Tested as Newborns

A follow-up study involving 50 children (who were 5 years old) from an original group of 100 who had been tested as newborns was carried out using the delayed blanch phenomenon. The reaction persisted in 78%. No correlation could be found between personal and family history of allergy and the presence or absence of the delayed blanch phenomenon

Molecular identification of Nectriaceae in infections of apple replant disease affected roots collected by Harris Uni-Core punching or laser microdissection

Apple replant disease (ARD) negatively affects growth and yield of apple plants worldwide. Fungi belonging to the Nectriaceae have often been isolated from roots grown in replant soils and thus are proposed among others as one biotic cause of the disease complex. Microscopic analyses of ARD-affected roots revealed characteristic symptoms associated with fungal infection sites. Here, two extraction methods of such tissue sites were applied to directly identify an unknown fungus that forms typical cauliflower-like structures in diseased root cortex cells. Punching small tissue samples of about 0.5 mm3 volume with the Harris Uni-Core is a quick and easy method to harvest symptomatic material. Secondly, a laser microdissection (LMD) protocol for apple roots was established. This technique allows the extraction of defined cell or tissue fractions from thin cryo-sections. Tissue harvesting was followed by the identification of fungi via PCR amplification of two gene fragments and Sanger sequencing. For Harris samples, Chelex was used for DNA stabilization, while LMD samples were directly submitted to PCR. In Harris samples, mainly the Nectriaceae species Dactylonectria torresensis, Ilyonectria robusta and Rugonectria rugulosa were identified. In addition to these, in LMD samples Cylindrocladiella sp. and Ilyonectria europaea were detected. Thus, the intracellular CF structures contained different species of Nectriaceae in the ARD-affected cortex cells. These results contribute considerably to the etiology of the ARD. Both protocols offer the possibility to identify fungi from selected symptomatic small root sections by molecular tools avoiding isolation and subsequent axenic pure cultures of single fungal isolates

Kinematic first-order calving law implies potential for abrupt ice-shelf retreat

Recently observed large-scale disintegration of Antarctic ice shelves has moved their fronts closer towards grounded ice. In response, ice-sheet discharge into the ocean has accelerated, contributing to global sea-level rise and emphasizing the importance of calving-front dynamics. The position of the ice front strongly influences the stress field within the entire sheet-shelf-system and thereby the mass flow across the grounding line. While theories for an advance of the ice-front are readily available, no general rule exists for its retreat, making it difficult to incorporate the retreat in predictive models. Here we extract the first-order large-scale kinematic contribution to calving which is consistent with large-scale observation. We emphasize that the proposed equation does not constitute a comprehensive calving law but represents the first-order kinematic contribution which can and should be complemented by higher order contributions as well as the influence of potentially heterogeneous material properties of the ice. When applied as a calving law, the equation naturally incorporates the stabilizing effect of pinning points and inhibits ice shelf growth outside of embayments. It depends only on local ice properties which are, however, determined by the full topography of the ice shelf. In numerical simulations the parameterization reproduces multiple stable fronts as observed for the Larsen A and B Ice Shelves including abrupt transitions between them which may be caused by localized ice weaknesses. We also find multiple stable states of the Ross Ice Shelf at the gateway of the West Antarctic Ice Sheet with back stresses onto the sheet reduced by up to 90 % compared to the present state

Reversibility of Superconducting Nb Weak Links Driven by the Proximity Effect in a Quantum Interference Device

We demonstrate the role of proximity effect in the thermal hysteresis of superconducting constrictions. From the analysis of successive thermal instabilities in the transport characteristics of micron-size superconducting quantum interference devices with a well-controlled geometry, we obtain a complete picture of the different thermal regimes. These determine whether the junctions are hysteretic or not. Below the superconductor critical temperature, the critical current switches from a classical weak-link behavior to one driven by the proximity effect. The associated small amplitude of the critical current makes it robust with respect to the heat generation by phase-slips, leading to a non-hysteretic behavior.Comment: 6 pages, 5 figures, including Supplementary Informatio