1,434 research outputs found

    Supernova explosions and the birth of neutron stars

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    We report here on recent progress in understanding the birth conditions of neutron stars and the way how supernovae explode. More sophisticated numerical models have led to the discovery of new phenomena in the supernova core, for example a generic hydrodynamic instability of the stagnant supernova shock against low-mode nonradial deformation and the excitation of gravity-wave activity in the surface and core of the nascent neutron star. Both can have supportive or decisive influence on the inauguration of the explosion, the former by improving the conditions for energy deposition by neutrino heating in the postshock gas, the latter by supplying the developing blast with a flux of acoustic power that adds to the energy transfer by neutrinos. While recent two-dimensional models suggest that the neutrino-driven mechanism may be viable for stars from about 8 solar masses to at least 15 solar masses, acoustic energy input has been advocated as an alternative if neutrino heating fails. Magnetohydrodynamic effects constitute another way to trigger explosions in connection with the collapse of sufficiently rapidly rotating stellar cores, perhaps linked to the birth of magnetars. The global explosion asymmetries seen in the recent simulations offer an explanation of even the highest measured kick velocities of young neutron stars.Comment: 10 pages, 8 figures, 19 ps files; to be published in Proc. of Conf. "40 Years of Pulsars: Millisecond Pulsars, Magnetars, and More", August 12-17, 2007, McGill Univ., Montreal, Canada; high-resolution images can be obtained upon request; incorrect panel in fig.8 replace

    Long-term lithium treatment in bipolar disorder. effects on glomerular filtration rate and other metabolic parameters

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    .BACKGROUND: Concerns about potential adverse effects of long-term exposure to lithium as a mood-stabilizing treatment notably include altered renal function. However, the incidence of severe renal dysfunction; rate of decline over time; effects of lithium dose, serum concentration, and duration of treatment; relative effects of lithium exposure vs. aging; and contributions of sex and other factors all remain unclear. METHODS: Accordingly, we acquired data from 12 collaborating international sites and 312 bipolar disorder patients (6142 person-years, 2669 assays) treated with lithium carbonate for 8-48 (mean 18) years and aged 20-89 (mean 56) years. We evaluated changes of estimated glomerular filtration rate (eGFR) as well as serum creatinine, urea-nitrogen, and glucose concentrations, white blood cell count, and body-mass index, and tested associations of eGFR with selected factors, using standard bivariate contrasts and regression modeling. RESULTS: Overall, 29.5% of subjects experienced at least one low value of eGFR ( 55; risk of ≥2 low values was 18.1%; none experienced end-stage renal failure. eGFR declined by 0.71%/year of age and 0.92%/year of treatment, both by 19% more among women than men. Mean serum creatinine increased from 0.87 to 1.17 mg/dL, BUN from 23.7 to 33.1 mg/dL, glucose from 88 to 122 mg/dL, and BMI from 25.9 to 26.6 kg/m2. By multivariate regression, risk factors for declining eGFR ranked: longer lithium treatment, lower lithium dose, higher serum lithium concentration, older age, and medical comorbidity. Later low eGFR was also predicted by lower initial eGFR, and starting lithium at age ≥ 40 years. LIMITATIONS: Control data for age-matched subjects not exposed to lithium were lacking. CONCLUSIONS: Long-term lithium treatment was associated with gradual decline of renal functioning (eGFR) by about 30% more than that was associated with aging alone. Risk of subnormal eGFR was from 18.1% (≥2 low values) to 29.5% (≥1 low value), requiring about 30 years of exposure. Additional risk factors for low eGFR were higher serum lithium level, longer lithium treatment, lower initial eGFR, and medical comorbidity, as well as older age

    UV‐based dynamic control improves the robustness of multicolumn countercurrent solvent gradient purification of oligonucleotides

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    Therapeutic oligonucleotides (ONs) have great potential to treat many diseases due to their ability to regulate gene expression. However, the inefficiency of standard purification techniques to separate the target sequence from molecularly similar variants is hindering development of large scale ON manufacturing at a reasonable cost. Multicolumn Countercurrent Solvent Gradient Purification (MCSGP) is a valuable process able to bypass the purity-yield tradeoff typical of single-column operations, and hence to make the ON production more sustainable from both an economic and environmental point of view. However, operating close to the optimum of MCSGP can be challenging, resulting in unstable process performance and in a drift in product quality, especially when running a continuous process for extended periods where process parameters such as temperature are prone to variation. In this work, we demonstrate how greater process robustness is introduced in the design and execution of MCSGP for the purification of a 20mer single-stranded DNA sequence through the implementation of UV-based dynamic control. With this novel approach, the cyclic steady state was reached already in the third cycle and disturbances coming from fluctuations in the feed quality, loading amount and temperature were effectively compensated allowing a stable operation close to the optimum. In response to the perturbations, the controlled process kept the standard deviation on product recovery below 3.4%, while for the non-controlled process it increased up to 27.5%.MCSGP is a twin-column chromatographic process able to by-pass the yield/purity tradeoff typical of single-column operations. In this work, the authors demonstrate the possibility of increasing the robustness of MCSGP through the design and implementation of UV-based dynamic process control, which automatically adjusts the duration of recycling and collection windows based on the UV chromatogram recorded online and user-defined UV thresholds. With this control, MCSGP is 8 times less sensitive to imposed fluctuations in input process parameters compared to the non-controlled operation. imag

    Implicaciones transnacionales en la historia de la psiquiatría: la reubicación de pacientes de Tirol del sur (Italia) en instituciones psiquiátricas alemanas, 1940-1945

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    Object of this article is the destiny of psychiatric inmates in Wuerttemberg asylums, 1940-1945. These patients from Italian regions of Vicenza, Udine, Trento, Alto Adige and various locations more were delegated and, to a substantial number, illegally deported to the German asylums Zwiefalten, Schussenried and Weissenau, all in South Wuerttemberg, in 1940 and 1943. Attention is focused on the pioneering state pre-negotiations, and the so-called option treaties between the German Reich and Fascist Italy as part of the general aspect of National Socialist bio-Politics. The treatment of these South Tyrol patients in the asylums themselves, as well as their fate will be put into the context of the resettlement actions at the margins of the Third Reich, which started in 1939 and widely affected the European continent. It is referred to other sub-groups of migrating population from Italy to the German Reich as well, as a contrasting aspect of this contributionEl objeto de este trabajo es investigar el destino de un grupo de pacientes psiquiátricos ingresados en asilos de Württemberg (Alemania) durante el periodo de 1940 a 1945. Dichos internos, procedentes principalmente de las regiones italianas de Vicenza, Udine, Trento y Alto Adigio, fueron enviados (y un número importante entre ellos ilegalmente deportados) a los psiquátricos alemanes de Zwiefalten, Schussenried y Weissenau, situados todos en el sur de la región alemana de Württemberg, entre 1940 y 1943. Especial atención se dedica a los llamados Acuerdos para la Opción entre el Reich alemán y la Italia fascista, como parte de la biopolítica nacionalsocialista. El tratamiento de estos pacientes surtiroleses en los asilos, así como su destino, se sitúa en el contexto de las acciones de reubicación de la población realizadas en las zonas limítrofes del Tercer Reich, que comenzaron en 1939 y afectaron a amplias zonas del continente europeo. Se estudian comparativamente también en esta contribución otros subgrupos poblacionales que emigraron por entonces de Italia al Reich alemán

    Analyzing Atomic Interactions in Molecules as Learned by Neural Networks

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    While machine learning (ML) models have been able to achieve unprecedented accuracies across various prediction tasks in quantum chemistry, it is now apparent that accuracy on a test set alone is not a guarantee for robust chemical modeling such as stable molecular dynamics (MD). To go beyond accuracy, we use explainable artificial intelligence (XAI) techniques to develop a general analysis framework for atomic interactions and apply it to the SchNet and PaiNN neural network models. We compare these interactions with a set of fundamental chemical principles to understand how well the models have learned the underlying physicochemical concepts from the data. We focus on the strength of the interactions for different atomic species, how predictions for intensive and extensive quantum molecular properties are made, and analyze the decay and many-body nature of the interactions with interatomic distance. Models that deviate too far from known physical principles produce unstable MD trajectories, even when they have very high energy and force prediction accuracy. We also suggest further improvements to the ML architectures to better account for the polynomial decay of atomic interactions

    Measurement of the production cross section for W-bosons in association with jets in pp collisions at s=7 TeV with the ATLAS detector

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    This Letter reports on a first measurement of the inclusive W + jets cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC, with the ATLAS detector. Cross sections, in both the electron and muon decay modes of the W-boson, are presented as a function of jet multiplicity and of the transverse momentum of the leading and next-to-leading jets in the event. Measurements are also presented of the ratio of cross sections sigma (W + >= n)/sigma(W + >= n - 1) for inclusive jet multiplicities n = 1-4. The results, based on an integrated luminosity of 1.3 pb(-1), have been corrected for all known detector effects and are quoted in a limited and well-defined range of jet and lepton kinematics. The measured cross sections are compared to particle-level predictions based on perturbative QCD. Next-to-leading order calculations, studied here for n <= 2, are found in good agreement with the data. Leading-order multiparton event generators, normalized to the NNLO total cross section, describe the data well for all measured jet multiplicitie

    Internal dynamics of the 3-Pyrroline-N-Oxide ring in spin-labeled proteins

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    Site-directed spin labeling is a versatile tool to study structure as well as dynamics of proteins using EPR spectroscopy. Methanethiosulfonate (MTS) spin labels tethered through a disulfide linkage to an engineered cysteine residue were used in a large number of studies to extract structural as well as dynamic information on the protein from the rotational dynamics of the nitroxide moiety. The ring itself was always considered to be a rigid body. In this contribution, we present a combination of high-resolution X-ray crystallography and EPR spectroscopy of spin-labeled protein single crystals demonstrating that the nitroxide ring inverts fast at ambient temperature while exhibiting nonplanar conformations at low temperature. We have used quantum chemical calculations to explore the potential energy that determines the ring dynamics as well as the impact of the geometry on the magnetic parameters probed by EPR spectroscopy

    Measurement of top quark–antiquark pair production in association with a W or Z boson in pp collisions at √s=8 TeV

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