520 research outputs found

    Forecasting Time Series from Clusters.

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    Forecasting large numbers of time series is a costly and time-consuming exercise. Before forecasting a large number of series that are logically connected in some way, the authors can first cluster them into groups of similar series. In this paper they investigate forecasting the series in each cluster. Similar series are first grouped together using a clustering procedure that is based on a test of hypothesis. The series in each cluster are then pooled together and forecasts are obtained. Simulated results show that this procedure for forecasting similar series performs reasonably well.Autoregressive models, Clustering technique, Mean square forecast error, Pooled series,

    Bayesian Trace Statistics for the Reduced Rank Regression Model.

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    Estimation of the reduced rank regression model requires restrictions be imposed upon the model. Two forms of restrictions are commonly used. Earlier Bayesian work relied on the triangular method of identification which imposes an a priori ordering on the variables in the system, however, incorrect ordering of the variables can result in model misspecification. Bayesian estimation of the reduced rank regression model without ordering restrictions was presented in Strachan (1998) and follows the classical approach of Anderson (1951) and Johansen (1998). This method of estimation avoids placing restrictions on the space spanned by the reduced rank relations and simplifies testing of restrictions on that space. In this paper, a method for estimating approximate marginal likelihoods and Bayes factors is presented for this model, using Laplace approximations for integrals. These Bayes factors algebraically resemble the Johansen trace statistic (1995), hence the title. We consider the model with rank r and no restrictions on the reduced rank relations.Reduced rank regression, marginal likelihoods, Bayes factors, Bayesian analysis

    Modeling of solvent flow effects in enzyme catalysis under physiological conditions

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    A stochastic model for the dynamics of enzymatic catalysis in explicit, effective solvents under physiological conditions is presented. Analytically-computed first passage time densities of a diffusing particle in a spherical shell with absorbing boundaries are combined with densities obtained from explicit simulation to obtain the overall probability density for the total reaction cycle time of the enzymatic system. The method is used to investigate the catalytic transfer of a phosphoryl group in a phosphoglycerate kinase-ADP-bis phosphoglycerate system, one of the steps of glycolysis. The direct simulation of the enzyme-substrate binding and reaction is carried out using an elastic network model for the protein, and the solvent motions are described by multiparticle collision dynamics, which incorporates hydrodynamic flow effects. Systems where solvent-enzyme coupling occurs through explicit intermolecular interactions, as well as systems where this coupling is taken into account by including the protein and substrate in the multiparticle collision step, are investigated and compared with simulations where hydrodynamic coupling is absent. It is demonstrated that the flow of solvent particles around the enzyme facilitates the large-scale hinge motion of the enzyme with bound substrates, and has a significant impact on the shape of the probability densities and average time scales of substrate binding for substrates near the enzyme, the closure of the enzyme after binding, and the overall time of completion of the cycle.Comment: 15 pages in double column forma

    A Millimeter-scale Single Charged Particle Dosimeter for Cancer Radiotherapy

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    This paper presents a millimeter-scale CMOS 64Ă—\times64 single charged particle radiation detector system for external beam cancer radiotherapy. A 1Ă—\times1 ÎĽm2\mu m^2 diode measures energy deposition by a single charged particle in the depletion region, and the array design provides a large detection area of 512Ă—\times512 ÎĽm2\mu m^2. Instead of sensing the voltage drop caused by radiation, the proposed system measures the pulse width, i.e., the time it takes for the voltage to return to its baseline. This obviates the need for using power-hungry and large analog-to-digital converters. A prototype ASIC is fabricated in TSMC 65 nm LP CMOS process and consumes the average static power of 0.535 mW under 1.2 V analog and digital power supply. The functionality of the whole system is successfully verified in a clinical 67.5 MeV proton beam setting. To our' knowledge, this is the first work to demonstrate single charged particle detection for implantable in-vivo dosimetry

    Differential rates of perinatal maturation of human primary and nonprimary auditory cortex

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    Abstract Primary and nonprimary cerebral cortex mature along different timescales; however, the differences between the rates of maturation of primary and nonprimary cortex are unclear. Cortical maturation can be measured through changes in tissue microstructure detectable by diffusion magnetic resonance imaging (MRI). In this study, diffusion tensor imaging (DTI) was used to characterize the maturation of Heschl’s gyrus (HG), which contains both primary auditory cortex (pAC) and nonprimary auditory cortex (nAC), in 90 preterm infants between 26 and 42 weeks postmenstrual age (PMA). The preterm infants were in different acoustical environments during their hospitalization: 46 in open ward beds and 44 in single rooms. A control group consisted of 15 term-born infants. Diffusion parameters revealed that (1) changes in cortical microstructure that accompany cortical maturation had largely already occurred in pAC by 28 weeks PMA, and (2) rapid changes were taking place in nAC between 26 and 42 weeks PMA. At term equivalent PMA, diffusion parameters for auditory cortex were different between preterm infants and term control infants, reflecting either delayed maturation or injury. No effect of room type was observed. For the preterm group, disturbed maturation of nonprimary (but not primary) auditory cortex was associated with poorer language performance at age two years

    Long-term effects of lifetime trauma exposure in a rural community sample

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    Background This study examines the long-term outcomes of lifetime trauma exposure, including factors that contribute to the development of PTSD, in a sample of rural adults. Methods In 623 rural community residents, lifetime trauma exposure, PTSD, other psychiatric disorders and lifetime suicidal ideation were assessed using the World Mental Health Composite International Diagnostic Interview. Logistic regressions were used to examine relationships between potentially traumatic events (PTEs) and lifetime PTSD and other diagnoses. Results 78.2 % of participants reported at least on PTE. Rates were broadly comparable with Australian national data: the most commonly endorsed events were unexpected death of a loved one (43.7 %); witnessing injury or death (26.3 %); and life-threatening accident (19.3 %). While the mean age of the sample was 55 years, the mean age of first trauma exposure was 19 years. The estimated lifetime rate of PTSD was 16.0 %. Events with the strongest association with PTSD were physical assault and unexpected death of a loved one. Current functioning was lowest among those with current PTSD, with this group reporting elevated psychological distress, higher mental health service use, a greater number of comorbidities, and lower perceived social support. Respondents with a past PTE but no PTSD history were generally similar in terms of their current wellbeing to those with no lifetime PTE. Conclusions PTEs may have diverse psychological and social consequences beyond the development of PTSD. Ensuring that adequate support services are available in rural areas, particularly in the period immediately following a PTE, may reduce the long-term impact of traumatic events

    Overview of Therapeutic Ultrasound Applications and Safety Considerations

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135598/1/jum2012314623.pd

    The Vermont oxford neonatal encephalopathy registry: Rationale, methods, and initial results

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    BACKGROUND: In 2006, the Vermont Oxford Network (VON) established the Neonatal Encephalopathy Registry (NER) to characterize infants born with neonatal encephalopathy, describe evaluations and medical treatments, monitor hypothermic therapy (HT) dissemination, define clinical research questions, and identify opportunities for improved care. METHODS: Eligible infants were ≥ 36 weeks with seizures, altered consciousness (stupor, coma) during the first 72 hours of life, a 5 minute Apgar score of ≤ 3, or receiving HT. Infants with central nervous system birth defects were excluded. RESULTS: From 2006–2010, 95 centers registered 4232 infants. Of those, 59% suffered a seizure, 50% had a 5 minute Apgar score of ≤ 3, 38% received HT, and 18% had stupor/coma documented on neurologic exam. Some infants experienced more than one eligibility criterion. Only 53% had a cord gas obtained and only 63% had a blood gas obtained within 24 hours of birth, important components for determining HT eligibility. Sixty-four percent received ventilator support, 65% received anticonvulsants, 66% had a head MRI, 23% had a cranial CT, 67% had a full channel encephalogram (EEG) and 33% amplitude integrated EEG. Of all infants, 87% survived. CONCLUSIONS: The VON NER describes the heterogeneous population of infants with NE, the subset that received HT, their patterns of care, and outcomes. The optimal routine care of infants with neonatal encephalopathy is unknown. The registry method is well suited to identify opportunities for improvement in the care of infants affected by NE and study interventions such as HT as they are implemented in clinical practice

    Electronic Structure of Te and As Covered Si(211)

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    Electronic and atomic structures of the clean, and As and Te covered Si(211) surface are studied using pseudopotential density functional method. The clean surface is found to have (2 X 1) and rebonded (1 X 1) reconstructions as stable surface structures, but no \pi-bonded chain reconstruction. Binding energies of As and Te adatoms at a number of symmetry sites on the ideal and (2 X 1) reconstructed surfaces have been calculated because of their importance in the epitaxial growth of CdTe and other materials on the Si(211) surface. The special symmetry sites on these surfaces having the highest binding energies for isolated As and Te adatoms are identified. But more significantly, several sites are found to be nearly degenerate in binding energy values. This has important consequences for epitaxial growth processes. Optimal structures calculated for 0.5 ML of As and Te coverage reveal that the As adatoms dimerize on the surface while the Te adatoms do not. However, both As and Te covered surfaces are found to be metallic in nature.Comment: 17 pages, 9 figures, accepted for publication in Phys. Rev.

    Field Bund & Border as Alternative Land Use for Forage Production: A Case of Marginal Farmer in Bundelkhand Region of India

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    In India, if marginal farmers are approached for production of forage grasses in their agricultural lands, the response of the farmers would be straight forward „NO‟ to the forage crops on agricultural lands. The reason is that food grains (cereals & pulses), vegetables, oilseeds, fruits, etc. are grown on agricultural land and get the first preference for family members, while the forage grasses are least preferred, as crops residues are being fed to livestock. More than 60% of the farm produce come from the small farms only. The productivity of the marginal and small farmers is the solution for growing population food needs. Most of the marginal and small farmers cultivate the farm land with the support of their family members and local labour which the quality of the work is higher. They grow multiple crops and sow as soon as they harvest. The last four decades has witnessed a sharp decline in the average size of operational land holdings in India. The average size of operational land holdings has reduced by half from 2.28 ha in 1970-71 to 1.6 ha in 2010-11. Land holdings in the marginal category (less than 1 ha) constitute 67% of the operational holdings in India (2010-11). Marginal and small holdings together, constitute 85% in terms of number of operational holdings and 44% of the operated area in the country. Thus, over the period, the marginal category has emerged as a distinct and dominant class by itself with its average size dwindling to a mere 0.38 ha. (NABARD, 2014). This is the case study of an illiterate & marginal farmer, Shri Vijay Singh Kushwaha (37) S/o shri Dhan Singh resides in Kushwaha Dera at village Parasai (under Babina development block) in Jhansi district of Uttar Pradesh, Bundelkhand region of central India. He used to cultivate only monsoon crops, was the target of an extension programme initiated by ICAR-Central Agroforestry Research Institute, Jhansi in 2011 under the project “Enhancing groundwater recharge and water use efficiency in Semi-Arid Tropics region through watershed interventions, Parasai-Sindh watershed, Jhansi”. The watershed is being developed in consortia mode with ICAR-Central Agroforestry Research Institute, Jhansi, and International Crop Research Institute for Semi-Arid Tropics (ICRISAT), Hyderabad. The watershed comprises three villages namely Parasai, Chhatpur and Bachhauni and located between 250 23‟56‟‟ to 250 27‟ 9.34‟‟ N latitude and 780 19‟ 45.71‟‟ to 780 22‟ 42.57‟‟E longitude. The watershed is about 35 km in the West of the district headquarter. Bundelkhand is prone to severe drought leading to huge migration towards cities in search of livelihoods and the scarcity of green fodder posed as one of the major hindrances for dairy and livestock production activity in the region
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