952 research outputs found

    Large scale processing of seismic data in search of regional and global stress patterns

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    A composite compute program has been devised for a fast reduction of multistation seismic data in the period range 50–500 sec for mantle surface waves and 20–100 sec for body waves. The analysis aims at the reconstruction of the seismic source from the spectrum of its far radiation field and the correlation of its parameters with its depth, size and regional environment. The capability of the computational procedure has been demonstrated in two studies of WWNSS records: one includes a spectral analysis of surface waves from a shallow shock in the Kurile Islands; the other includes a spectral analysis of P waves from 9 shocks in the depth range 550–700 km at Fiji, Mariana, Java, Japan, Peru and Brazil. Other applications of the proposed data processing routine are foreseen; a tsunami warning system and focal depth determination from spectral modal ratios. It is believed that a persistent search for stress patterns, based on the processing of a sufficiently large sample of seismic events, is essential to any future program of earthquake prediction

    Field induced evolution of regular and random 2D domain structures and shape of isolated domains in LiNbO<sub>3</sub> and LiTaO<sub>3</sub>

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    The shapes of isolated domains produced by application of the uniform external electric field in different experimental conditions were investigated experimentally in single crystalline lithium niobate LiNbO3 and lithium tantalate LiTaO3. The study of the domain kinetics by computer simulation and experimentally by polarization reversal of the model structure using two-dimensional regular electrode pattern confirms applicability of the kinetic approach to explanation of the experimentally observed evolution of the domain shape and geometry of the domain structure. It has been shown that the fast domain walls strictly oriented along X directions appear after domain merging

    High Spectral Resolution Measurement of the Sunyaev–Zel'dovich Effect Null with Z-Spec

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    The Sunyaev-Zel'dovich (SZ) effect spectrum crosses through a null where ΔT_CMB = 0 near ν_0 = 217 GHz. In a cluster of galaxies, ν0 can be shifted from the canonical thermal SZ effect value by corrections to the SZ effect scattering due to the properties of the inter-cluster medium. We have measured the SZ effect in the hot galaxy cluster RX J 1347.5 – 1145 with Z-Spec, an R ~ 300 grating spectrometer sensitive between 185 and 305 GHz. These data comprise a high spectral resolution measurement around the null of the SZ effect and clearly exhibit the transition from negative to positive ΔT_CMB over the Z-Spec band. The SZ null position is measured to be ν_0 = 225.8 ± 2.5(stat.) ± 1.2(sys.) GHz, which differs from the canonical null frequency by 3.0σ and is evidence for modifications to the canonical thermal SZ effect shape. Assuming the measured shift in ν0 is due only to relativistic corrections to the SZ spectrum, we place the limit kT_e = 17.1 ± 5.3 keV from the zero-point measurement alone. By simulating the response of the instrument to the sky, we are able to generate likelihood functions in {y_0, T_e, v_pec} space. For v_pec = 0 km s^(–1), we measure the best-fitting SZ model to be y_0 = 4.6^(+0.6)_(–0.9) × 10^(–4), T_e, 0 = 15.2^(+12)_(–7.4) keV. When v pec is allowed to vary, a most probable value of v_pec = + 450 ± 810 km s^(–1) is found

    Gallbladder Ejection Fraction is Unrelated to Gallbladder Pathology in Children and Adolescents

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    Objectives: Biliary dyskinesia is a common diagnosis that frequently results in cholecystectomy. In adults, most clinicians use a cut off value for the gallbladder ejection fraction (GBEF) of <35% to define the disease. This disorder is not well characterized in children. Our aim was to determine the relation between GBEF and gallbladder pathology using a large statewide medical record repository. Methods: We obtained records from all patients of 21 years and younger who underwent hepatic iminodiacetic acid (HIDA) testing within the Indiana Network for Patient Care from 2004 to 2013. GBEF results were obtained from radiology reports using data mining techniques. Age, sex, race, and insurance status were obtained for each patient. Any gallbladder pathology obtained subsequent to an HIDA scan was also obtained and parsed for mention of cholecystitis, cholelithiasis, or cholesterolosis. We performed mixed effects logistic regression analysis to determine the influence of age, sex, race, insurance status, pathologist, and GBEF on the presence of these histologic findings. Results: Two thousand eight hundred forty-one HIDA scans on 2558 patients were found. Of these, 310 patients had a full-text gallbladder pathology report paired with the HIDA scan. GBEF did not correlate with the presence of gallbladder pathology (cholecystitis, cholelithiasis, or cholesterolosis) when controlling for age, sex, race, insurance status, and pathologist using a mixed effects model. Conclusions: Hypokinetic gallbladders are no more likely to have gallbladder pathology than normal or hyperkinetic gallbladders in the setting of a patient with both a HIDA scan and a cholecystectomy. Care should be used when interpreting the results of HIDA scans in children and adolescents

    Functional modelling in evolvable assembly systems

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    The design and reconfiguration of adaptive production systems is a key driver in modern advanced manufacturing. We summarise the use of an ap-proach from the field of functional modelling to capture the function, behaviour, and structure of a system. This model is an integral part of the Evolvable Assembly Systems architecture, allowing the system to adapt its behaviour in response to changing product requirements. The integrated approach is illustrated with an example taken from a real EAS instantiation

    Absence of association between behavior problems in childhood and hypertension in midlife

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    Background It is known that behavior in childhood is associated with certain physical and mental health problems in midlife. However, there is limited evidence on the role of childhood behavior problems in the development of hypertension in adulthood. The present study aimed to examine whether behavior problems in childhood influenced the risk of hypertension in midlife in the United Kingdom 1958 birth cohort. Methods The 1958 British birth cohort comprised 17,638 individuals born in the first week of March 1958 in the United Kingdom. Behavior problems were assessed at 7, 11, and 16 years of age by parents and teachers. At age 45, blood pressure was measured and hypertension was recorded if blood pressure was ≥140/90 mm Hg or if the participants were informed by their health professionals that they had high blood pressure. Behavioral information was reported according to the Rutter Children's Behaviour Questionnaire (RCBQ) and the Bristol Social Adjustment Guide (BSAG). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to examine behavior problems in childhood in relation to hypertension at 45 years of age according to logistic regression analysis, with adjustment for sex, social class in childhood and adulthood, childhood cognition, birth weight, gestational age at birth, body mass index (BMI), smoking, alcohol consumption, and physical activity. Results Behavior problems reported by parents at 7, 11, and 16 years were not associated with hypertension in midlife (OR, 0.93; 95% CI, 0.81, 1.07; OR, 0.95; 95% CI, 0.81, 1.11; OR, 0.98; 95% CI, 0.85, 1.12, respectively). Similarly, teacher-reported behavior problems at 7, 11, and 16 years were not associated with hypertension in midlife (OR, 0.92; 95% CI, 0.72, 1.18; OR, 0.92; 95% CI, 0.84, 1.02; OR, 1.03; 95% CI, 0.92, 1.15, respectively). Further separate analyses showed similar results for males and females. Conclusion There is no association between behavior problems in childhood and hypertension in midlife

    Nanoscale piezoelectric response across a single antiparallel ferroelectric domain wall

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    Surprising asymmetry in the local electromechanical response across a single antiparallel ferroelectric domain wall is reported. Piezoelectric force microscopy is used to investigate both the in-plane and out-of- plane electromechanical signals around domain walls in congruent and near-stoichiometric lithium niobate. The observed asymmetry is shown to have a strong correlation to crystal stoichiometry, suggesting defect-domain wall interactions. A defect-dipole model is proposed. Finite element method is used to simulate the electromechanical processes at the wall and reconstruct the images. For the near-stoichiometric composition, good agreement is found in both form and magnitude. Some discrepancy remains between the experimental and modeling widths of the imaged effects across a wall. This is analyzed from the perspective of possible electrostatic contributions to the imaging process, as well as local changes in the material properties in the vicinity of the wall

    Epidemiology of occupational hypersensitivity pneumonitis; reports from the SWORD scheme in the UK from 1996 to 2015

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    Objective To estimate the reported incidence of occupational hypersensitivity pneumonitis (OHP) in the UK and to consider whether the pattern of attributed causation has changed over time. Methods All cases of OHP reported to the SWORD scheme between January 1996 and December 2015 were classified into 1 of 10 categories of the suspected agent. Cases were grouped into four 5-year time periods to examine any changing pattern in incidence or suspected causation. For each time period, the annual incidence was calculated using the estimated number of reported cases and the working population of the UK. Results Between 1996 and 2015, there were 202 actual cases of OHP reported to SWORD, equating to an estimated 818 cases, when adjusting for the sampling ratio. Over this period, the annual UK incidence was 1.4 per million workers. The mean (SD) age of reported cases was 52 (13) years, and cases were four-times more likely to be men than women. Over the study period, there was a fall in the proportion of cases reported to be due to agricultural exposures (44–12%), and an increase in cases due to metalworking fluids (MWFs, 2–45%). Conclusions Over the last 20 years, the incidence of OHP in the UK has been ∼1–2 cases per million workers per year. Working with water-based MWFs is now the most commonly suspected causative exposure for OHP cases reported to the SWORD scheme in the UK
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