8,520 research outputs found

    Indirect Dissociative Recombination of LiH+^+ Molecules Fueled by Complex Resonance Manifolds

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    The LiH+^{+} molecule is prototypical of the indirect dissociative recombination (DR) process, in which a colliding electron destroys the molecule through Rydberg capture pathways. This Letter develops the first quantitative test of the Siegert state multichannel quantum defect theory description of indirect DR for a diatomic molecular ion. The R-matrix approach is adopted to calculate ab-initio quantum defects, functions of the internuclear distance that characterize both Rydberg states and the zero-energy collisions of electrons with LiH+^{+} ions. The calculated DR rate coefficient agrees accurately with recent experimental data (S. Krohn et al, Phys. Rev. Lett. 86, 4005). We identify the doorways to fast indirect DR as complex resonance manifolds, which couple closed channels having both high and low principal quantum numbers. This sheds new light on the competition between direct and indirect DR pathways, and suggests the reason why previous theory underestimated the DR rate by an order of magnitude.Comment: Submitted to PR

    Detection of known haemophilia B mutations and carrier testing by microarray

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    The molecular basis of haemophilia B is heterogeneous and many mutations of the Factor IX (FIX) gene have been characterised. Using the allele-specific arrayed primer extension (AS-APEX) technology, we have designed a FIX array to simultaneously analyse 69 mutations found in British, Thai and Chinese patients. This technology overcomes the problem of multiple reverse dot-blot analysis and has a 100% accuracy in the detection of both affected subjects and carriers in families with known mutations. In seven unknown mutations from Thailand, the array could detect the specific mutation in five and in the remainders the normal primer at specific spots failed to extend due to a mutation a few nucleotides upstream, thus allowing their identification. Hence this FIX array can detect 53% of the 2891 mutation entries in the FIX database. Each of the microarray slide can be used for three different test samples and would be useful for carrier testing for common mutations and prenatal diagnosis. It is simpler and more cost effective than genome sequencing and would be particularly useful in laboratories with limited technical capabilities. © 2005 Schattauer GmbH, Stuttgart.published_or_final_versio

    The dysbindin-containing complex (BLOC-1) in brain: developmental regulation, interaction with SNARE proteins and role in neurite outgrowth.

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    Previous studies have implicated DTNBP1 as a schizophrenia susceptibility gene and its encoded protein, dysbindin, as a potential regulator of synaptic vesicle physiology. In this study, we found that endogenous levels of the dysbindin protein in the mouse brain are developmentally regulated, with higher levels observed during embryonic and early postnatal ages than in young adulthood. We obtained biochemical evidence indicating that the bulk of dysbindin from brain exists as a stable component of biogenesis of lysosome-related organelles complex-1 (BLOC-1), a multi-subunit protein complex involved in intracellular membrane trafficking and organelle biogenesis. Selective biochemical interaction between brain BLOC-1 and a few members of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) superfamily of proteins that control membrane fusion, including SNAP-25 and syntaxin 13, was demonstrated. Furthermore, primary hippocampal neurons deficient in BLOC-1 displayed neurite outgrowth defects. Taken together, these observations suggest a novel role for the dysbindin-containing complex, BLOC-1, in neurodevelopment, and provide a framework for considering potential effects of allelic variants in DTNBP1--or in other genes encoding BLOC-1 subunits--in the context of the developmental model of schizophrenia pathogenesis

    Methods for estimating the case fatality ratio for a novel, emerging infectious disease.

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    During the course of an epidemic of a potentially fatal disease, it is important that the case fatality ratio be well estimated. The authors propose a novel method for doing so based on the Kaplan-Meier survival procedure, jointly considering two outcomes (death and recovery), and evaluate its performance by using data from the 2003 epidemic of severe acute respiratory syndrome in Hong Kong, People's Republic of China. They compare this estimate obtained at various points in the epidemic with the case fatality ratio eventually observed; with two commonly quoted, naïve estimates derived from cumulative incidence and mortality statistics at single time points; and with estimates in which a parametric mixture model is used. They demonstrate the importance of patient characteristics regarding outcome by analyzing subgroups defined by age at admission to the hospital

    Bluenose II: Towards Faster Design and Verification of Pipelined Circuits

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    The huge demand for electronic devices has driven semiconductor companies to create better products in terms of area, speed, power etc. and to deliver them to market faster. Delay to market can result in lost opportunities. The length of the design cycle directly affects the time to market. However, inadequate time for design and verification can cause bugs that will cause further delays to market and correcting the error after manufacturing is very expensive. A bug in an ASIC found after fabrication requires respinning the mask at a cost of several million dollars. Even as the pressure to reduce the length of the design cycles grows, the size and complexity of digital hardware circuits have increased, which puts even greater pressure on design and verification productivity. Pipelining is one optimization technique which has contributed to the increased complexity in hardware design. Pipeline increases throughput by overlapping the execution of instructions. It is a challenge to design and verify pipelines because the specification is written to describe how instructions are executed in sequence while there can be multiple instructions being executed in a pipeline at one time. The overlapping of instructions adds further complexity to the hardware in the form of hazards which arise from resource conflicts, data dependencies or speculation of parcels due to branch instructions. To address these issues, we present PipeNet, a metamodel for describing hardware design at a higher level of abstraction and Bluenose II, a graphical tool for manipulating a PipeNet model. PipeNet is based on a pipeline model in a formal pipeline verification framework. The pipeline model contains arbiters, flow-control state machines, datapath and data-routing. The designer describes the pipeline design using PipeNet. Based on the PipeNet model, Bluenose II generates synthesizable VHDL code and a HOL verification script. Bluenose II's ability to generate HOL scripts turns the HOL theorem prover into Bluenose II's external verification environment. A direct connection to HOL is implemented in the form of a console to display results from HOL directly in Bluenose II. The data structures that represent PipeNet are evaluated for their extensibility to accommodate future changes. Finally, a case study based on an implementation of a two-wide superscalar 32-bit RISC integer pipeline is conducted to examine the quality of the generated codes and the entire design process in Bluenose II. The generation of VHDL code is improved over that provided in Bluenose I, Bluenose II's predecessor

    Factors associated with medication adherence in school-aged children with asthma

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    Adherence to preventive asthma treatment is poor, particularly in children, yet the factors associated with adherence in this age group are not well understood. Adherence was monitored electronically over 6 months in school-aged children who attended a regional emergency department in New Zealand for an asthma exacerbation and were prescribed twice-daily inhaled corticosteroids. Participants completed questionnaires including assessment of family demographics, asthma responsibility and learning style. Multivariable analysis of factors associated with adherence was conducted. 101 children (mean (range) age 8.9 (6-15) years, 51% male) participated. Median (interquartile range) preventer adherence was 30% (17-48%) of prescribed. Four explanatory factors were identified: female sex (+12% adherence), Asian ethnicity (+19% adherence), living in a smaller household (-3.0% adherence per person in the household), and younger age at diagnosis (+2.7% for every younger year of diagnosis) (all p<0.02). In school-aged children attending the emergency department for asthma, males and non-Asian ethnic groups were at high risk for poor inhaled corticosteroid adherence and may benefit most from intervention. Four factors explained a small proportion of adherence behaviour indicating the difficulty in identifying adherence barriers. Further research is recommended in other similar populations

    Drawing Trees with Perfect Angular Resolution and Polynomial Area

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    We study methods for drawing trees with perfect angular resolution, i.e., with angles at each node v equal to 2{\pi}/d(v). We show: 1. Any unordered tree has a crossing-free straight-line drawing with perfect angular resolution and polynomial area. 2. There are ordered trees that require exponential area for any crossing-free straight-line drawing having perfect angular resolution. 3. Any ordered tree has a crossing-free Lombardi-style drawing (where each edge is represented by a circular arc) with perfect angular resolution and polynomial area. Thus, our results explore what is achievable with straight-line drawings and what more is achievable with Lombardi-style drawings, with respect to drawings of trees with perfect angular resolution.Comment: 30 pages, 17 figure

    Radiating Shear-Free Gravitational Collapse with Charge

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    We present a new shear free model for the gravitational collapse of a spherically symmetric charged body. We propose a dissipative contraction with radiation emitted outwards. The Einstein field equations, using the junction conditions and an ansatz, are integrated numerically. A check of the energy conditions is also performed. We obtain that the charge delays the black hole formation and it can even halt the collapse.Comment: 22 pages, 9 figures. It has been corrected several typos and included several references. Accepted for publication in GR

    Maternal L-carnitine supplementation ameliorates renal underdevelopment and epigenetic changes in male mice offspring due to maternal smoking

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    © 2018 John Wiley & Sons Australia, Ltd Objectives: Epidemiological and animal studies showed that L-carnitine (LC) supplementation can ameliorate oxidative stress-induced tissues damage. We have previously shown that maternal cigarette smoke exposure (SE) can increase renal oxidative stress in newborn offspring with postnatal kidney underdevelopment and renal dysfunction in adulthood, which were normalised by LC administration in the SE dams during pregnancy. Exposure to an adverse intrauterine environment may lead to alteration in the epigenome, a mechanism by which adverse prenatal conditions increase the susceptibility to chronic disease later in life. The current study aimed to determine whether maternal SE induces epigenetic changes in the offspring's kidney are associated with renal underdevelopment, and the protective effect of maternal LC supplementation. Method: Female Balb/c mice (7 weeks) were exposed to cigarette smoke (SE) or air (Sham) for 6 weeks prior to mating, during gestation and lactation. A subgroup of the SE dams received LC via drinking water (SE + LC, 1.5 mmol/L) throughout gestation and lactation. Male offspring were studied at postnatal day (P)1, P20, and 13 weeks. Results: Maternal SE altered the expression of renal development markers glial cell line-derived neurotrophic factor and fibroblast growth factor 2, which were associated with increased renal global DNA methylation and DNA methyltransferase 1 mRNA expression at birth. These disorders were reversed by maternal LC administration. Conclusion: The effect of maternal SE on renal underdevelopment involves global epigenetic alterations from birth, which can be prevented by maternal LC supplementation

    Maternal L-carnitine supplementation improves glucose and lipid profiles in female offspring of dams exposed to cigarette smoke

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    © 2018 John Wiley & Sons Australia, Ltd Sex differences in disease susceptibility due to maternal programming have been reported. We previously observed that maternal smoking induced renal disease and neurological changes are restricted to males, while both male and female offspring develop metabolic disorders. We have also found that maternal L-carnitine supplementation during gestation and lactation can significantly improve glucose intolerance and hyperlipidaemia in male offspring. This study aimed to determine whether such beneficial effects can also occur in female offspring. Balb/c female mice were exposed to cigarette smoke (SE) 6 weeks prior to gestation, during gestation and lactation. A subgroup of the SE dams was given L-carnitine (1.5 mmol/L in drinking water) during gestation and lactation. Female offspring were studied at 20 days (weaning) and 13 weeks (adulthood). Maternal smoking increased liver weight (%) and blood glucose levels at 20 days, as well as glucose intolerance and plasma triglycerides levels at adulthood (P <.05). The hepatic lipid metabolic marker adipose triglyceride lipase was downregulated in the SE offspring at 20 days (P <.05). At 13 weeks, the hepatic pro-inflammatory markers IL-1β and TNF-α mRNA expression were upregulated, while the anti-inflammatory marker IL-10 mRNA expression was downregulated in the SE offspring (P <.05). Liver fibrosis was apparent at 20 days and 13 weeks. Maternal L-carnitine supplementation either normalised or suppressed the detrimental effects induced by maternal smoke exposure (P <.05). We conclude that maternal L-carnitine supplementation improves metabolic parameters in the female offspring of SE dams
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