2,612 research outputs found

    Simulation of High-Dose Ion Implantation-Induced Transient Diffusion and of Electrical Activation of Boron in Crystalline Silicon

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    Abstract Coupled diffusion-reaction equations for boron and for point defects and rather simple initial conditions are used to model the implantation-induced transiently enhanced diffusion and the electrical activation of high-dose boron distributions during annealing

    Overexpression of Mcl-1 exacerbates lymphocyte accumulation and autoimmune kidney disease in lpr mice

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    Cell death by apoptosis has a critical role during embryonic development and in maintaining tissue homeostasis. In mammals, there are two converging apoptosis pathways: the ‘extrinsic’ pathway, which is triggered by engagement of cell surface ‘death receptors’ such as Fas/APO-1; and the ‘intrinsic’ pathway, which is triggered by diverse cellular stresses, and is regulated by prosurvival and pro-apoptotic members of the Bcl-2 family of proteins. Pro-survival Mcl-1, which can block activation of the proapoptotic proteins, Bax and Bak, appears critical for the survival and maintenance of multiple haemopoietic cell types. To investigate the impact on haemopoiesis of simultaneously inhibiting both apoptosis pathways, we introduced the vavP-Mcl-1 transgene, which causes overexpression of Mcl-1 protein in all haemopoietic lineages, into Faslpr/lpr mice, which lack functional Fas and are prone to autoimmunity. The combined mutations had a modest impact on myelopoiesis, primarily an increase in the macrophage/monocyte population in Mcl-1tg/lpr mice compared with lpr or Mcl-1tg mice. The impact on lymphopoiesis was striking, with a marked elevation in all major lymphoid subsets, including the non-conventional double-negative (DN) T cells (TCRβ+ CD4– CD8– B220+ ) characteristic of Faslpr/lpr mice. Of note, the onset of autoimmunity was markedly accelerated in Mcl-1tg/lpr mice compared with lpr mice, and this was preceded by an increase in immunoglobulin (Ig)-producing cells and circulating autoantibodies. This degree of impact was surprising, given the relatively mild phenotype conferred by the vavP-Mcl-1 transgene by itself: a two- to threefold elevation of peripheral B and T cells, no significant increase in the non-conventional DN T-cell population and no autoimmune disease. Comparison of the phenotype with that of other susceptible mice suggests that the development of autoimmune disease in Mcl-1tg/lpr mice may be influenced not only by Ig-producing cells but also other haemopoietic cell types

    Novel Medication Supply Model Guarantees Adequate Management and High Adherence to Polypharmacy in Older Opioid Users – Preliminary Results with Outpatients

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    Background: Life expectancy of older drug users has increased, primarily thanks to opioid agonist treatment (OAT). Nursing homes are often not adapted to accommodate patients with substance use disorders. Although care and adherence to polypharmacy in older opioid users need considerable resources e.g., daily visits to an outpatient clinic, outpatient treatment and surveillance are provided as long as possible. We developed a novel medication supply model with an electronic dispenser of pre-packed medications located at patient home, after allowing for law requirements concerning the dispensing of opioids, and present preliminary results from three illustrative outpatients. Methods: The community pharmacy provided unit-of-dose pouches with all solid oral medications directly to patient home. Opioids for substitution were obtained at the addiction clinic in at least weekly intervals, otherwise in the pouches. The pouches were loaded into a lockable, remote-controlled medication management aid that was programmed according to the patient’s medication schedule. The dispenser reminds patients with acoustic alerts to take their medication and records dates and times of medication retrievals. It automatically sends an alert if a patient misses to retrieve a dose. Results: Our three outpatients used the electronic dispenser during 659, 118 and 61 days, with a total of 5, 9, and 18 pills to take daily at 1, 3 and 5 intake times, respectively. The majority of the doses were taken on the preset time (94%, 68.2% and 73.7%) or deliberately in advance (pocket dose). Clinical benefits were initiation and maintenance of a therapy for dementia over 18 months and suppression of HIV viral load over 1.8 years (patient 1), prevention of further dose escalation of pain medication (patient 2) and release of prompts to initiate the existential task of cooking (patient 3). Conclusion: Our novel supply model allows adequate implementation and persistence of complex treatments with outpatients. Clinical outcomes improved, patients and caregivers were satisfied, and resources were saved

    Bound-to-bound and bound-to-continuum optical transitions in combined quantum dot - superlattice systems

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    By combining band gap engineering with the self-organized growth of quantum dots, we present a scheme of adjusting the mid-infrared absorption properties to desired energy transitions in quantum dot based photodetectors. Embedding the self organized InAs quantum dots into an AlAs/GaAs superlattice enables us to tune the optical transition energy by changing the superlattice period as well as by changing the growth conditions of the dots. Using a one band envelope function framework we are able, in a fully three dimensional calculation, to predict the photocurrent spectra of these devices as well as their polarization properties. The calculations further predict a strong impact of the dots on the superlattices minibands. The impact of vertical dot alignment or misalignment on the absorption properties of this dot/superlattice structure is investigated. The observed photocurrent spectra of vertically coupled quantum dot stacks show very good agreement with the calculations.In these experiments, vertically coupled quantum dot stacks show the best performance in the desired photodetector application.Comment: 8 pages, 10 figures, submitted to PR

    ESCIMO.spread (v2) : parameterization of a spreadsheet-based energy balance snow model for inside-canopy conditions

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    This article describes the extension of the ESCIMO.spread spreadsheet-based point energy balance snow model by (i) an advanced approach for precipitation phase detection, (ii) a method for cold content and liquid water storage consideration and (iii) a canopy sub-model that allows the quantification of canopy effects on the meteorological conditions inside the forest as well as the simulation of snow accumulation and ablation inside a forest stand. To provide the data for model application and evaluation, innovative low-cost snow monitoring systems (SnoMoS) have been utilized that allow the collection of important meteorological and snow information inside and outside the canopy. The model performance with respect to both, the modification of meteorological conditions as well as the subsequent calculation of the snow cover evolution, are evaluated using inside- and outside-canopy observations of meteorological variables and snow cover evolution as provided by a pair of SnoMoS for a site in the Black Forest mountain range (southwestern Germany). The validation results for the simulated snow water equivalent with Nash–Sutcliffe model efficiency values of 0.81 and 0.71 and root mean square errors of 8.26 and 18.07 mm indicate a good overall model performance inside and outside the forest canopy, respectively. The newly developed version of the model referred to as ESCIMO.spread (v2) is provided free of charge together with 1 year of sample data including the meteorological data and snow observations used in this study

    Structure of sufficient quantum coarse-grainings

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    Let H and K be Hilbert spaces and T be a coarse-graining from B(H) to B(K). Assume that density matrices D_1 and D_2 acting on H are given. In the paper the consequences of the existence of a coarse-graining S from B(K) to B(H) satisfying ST(D_1)=D_1 and ST(D_2)=D_2 are given. (This condition means the sufficiency of T for D_1 and D_2.) Sufficiency implies a particular decomposition of the density matrices. This decomposition allows to deduce the exact condition for equality in the strong subadditivity of the von Neumann entropy.Comment: 13 pages, LATE

    New Algorithm for Mixmaster Dynamics

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    We present a new numerical algorithm for evolving the Mixmaster spacetimes. By using symplectic integration techniques to take advantage of the exact Taub solution for the scattering between asymptotic Kasner regimes, we evolve these spacetimes with higher accuracy using much larger time steps than previously possible. The longer Mixmaster evolution thus allowed enables detailed comparison with the Belinskii, Khalatnikov, Lifshitz (BKL) approximate Mixmaster dynamics. In particular, we show that errors between the BKL prediction and the measured parameters early in the simulation can be eliminated by relaxing the BKL assumptions to yield an improved map. The improved map has different predictions for vacuum Bianchi Type IX and magnetic Bianchi Type VI0_0 Mixmaster models which are clearly matched in the simulation.Comment: 12 pages, Revtex, 4 eps figure

    Modular Design of Highly Active Unitized Reversible Fuel Cell Electrocatalysts

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    A modular, multicomponent catalyst design principle is introduced and exemplified using a three-component, oxygen reduction reaction/oxygen evolution reaction (ORR/OER) catalyst designed for the oxygen electrode of unitized reversible fuel cells (URFCs). The catalyst system exhibited unprecedented catalytic performance in liquid electrolyte and in single unitized reversible fuel cell tests. The distinct components, each active for either ORR or OER, are prepared and optimized independently of each other and physically mixed during electrode preparation. The new modular URFC catalyst, Cu-α-MnO2/XC-72R/NiFe-LDH, combined a carbon-supported, Cu-stabilized α-MnO2 ORR catalyst with a NiFe-LDH OER catalyst and displayed improved activity and stability under URFC cycling compared to platinum group metal references. Stepwise modular optimization of the carbon and the interlayer anions of the OER component led to a further improved derivative, Cu-α-MnO2/O-MWCNTs/NiFe-LDH-Cl–. This URFC catalyst outperformed all previous materials in terms of its combined overpotential ηORR-OER and performance stability in the rotating disk electrode (RDE) scale. Its single-cell performance is analyzed and discussed

    Linking the 8.2 ka Event and its Freshwater Forcing in the Labrador Sea

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    The 8.2 ka event was the last deglacial abrupt climate event. A reduction in the Atlantic meridional overturning circulation (AMOC) attributed to the drainage of glacial Lake Agassiz may have caused the event, but the freshwater signature of Lake Agassiz discharge has yet to be identified in (delta)18O of foraminiferal calcite records from the Labrador Sea, calling into question the connection between freshwater discharge to the North Atlantic and AMOC strength. Using Mg/Ca-paleothermometry, we demonstrate that approx. 3 C of near-surface ocean cooling masked an 1.0 % decrease in western Labrador Sea (delta)18O of seawater concurrent with Lake Agassiz drainage. Comparison with North Atlantic (delta)18O of seawater records shows that the freshwater discharge was transported to regions of deep-water formation where it could perturb AMOC and force the 8.2 ka event
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