595 research outputs found

    Spin polarization and magneto-luminescence of confined electron-hole systems

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    A BCS-like variational wave-function, which is exact in the infinite field limit, is used to study the interplay among Zeeman energies, lateral confinement and particle correlations induced by the Coulomb interactions in strongly pumped neutral quantum dots. Band mixing effects are partially incorporated by means of field-dependent masses and g-factors. The spin polarization and the magneto-luminescence are computed as functions of the number of electron-hole pairs present in the dot and the applied magnetic field.Comment: To appear in Phys. Rev.

    Statistical analysis plan for the OPTIMUM study: optimising immunisation using mixed schedules, an adaptive randomised controlled trial of a mixed whole-cell/acellular pertussis vaccine schedule

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    Objective: The purpose of this double-blind, randomised, controlled trial is to compare allergic outcomes in children following vaccination with acellular pertussis (aP) antigen (standard of care in Australia) given at 2 months of age versus whole cell pertussis (wP) in the infant vaccine schedule. Participants: Up to 3000 Australian infants 6 to <12 weeks of age born ≥32 weeks gestation. Interventions: The intervention is a wP containing vaccine as the first scheduled pertussis vaccine dose instead of an aP containing vaccine. Outcomes: The primary outcome is a binary indicator of history of IgE-mediated food allergy at the age of 12 months confirmed, where necessary, with an oral food challenge before 18 months of age. Secondary outcomes include (1) history of parent-reported clinician-diagnosed new onset of atopic dermatitis by 6 or 12 months of age with a positive skin prick test to any allergen before 12 months of age, (2) geometric mean concentration in pertussis toxin-specific IgG before and 21 to 35 days after a booster dose of aP at 18 months of age, and (3) sensitisation to at least one allergen by 12 months of age. Results: Operating characteristics of trial decision rules were evaluated by trial simulation. The selected rules for success and futility approximately maintain type I error of 0.05 and achieved power 0.85 for a reduction in the primary outcome from 10% in the control group to 7% in the intervention group. Discussion: A detailed, prospective statistical analysis plan (SAP) is presented for this Bayesian adaptive design. The plan was written by the trial statistician and details the study design, pre-specified adaptive elements, decision thresholds, statistical methods, and the simulations used to evaluate the operating characteristics of the trial. Application of this SAP will minimise bias and supports transparent and reproducible research. Trial registration: Australia & New Zealand Clinical Trials Registry, ACTRN12617000065392. Registered on 12 January 2017 Study protocol: https://doi.org/10.1136/bmjopen-2020-04283

    The shortage of kidneys for transplantation in Australia

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    The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included.Timothy Mathew, Randall Faull and Paul Snellin

    The views of patients and carers in treatment decision making for chronic kidney disease: systematic review and thematic synthesis of qualitative studies

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    Objective To synthesise the views of patients and carers in decision making regarding treatment for chronic kidney disease, and to determine which factors influence those decisions

    Spin splitting of X-related donor impurity states in an AlAs barrier

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    We use magnetotunneling spectroscopy to observe the spin splitting of the ground state of an X-valley-related Si-donor impurity in an AlAs barrier. We determine the absolute magnitude of the effective Zeeman spin splitting factors of the impurity ground state to be gI_{I}= 2.2 ±\pm 0.1. We also investigate the spatial form of the electron wave function of the donor ground state, which is anisotropic in the growth plane

    Protocol for Pertussis Immunisation and Food Allergy (PIFA): A case-control study of the association between pertussis vaccination in infancy and the risk of IgE-mediated food allergy among Australian children

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    © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted. Introduction Atopic diseases, including food allergy, have become a predominant cause of chronic illness among children in developed countries. In Australia, a rise in hospitalisations among infants coded as anaphylaxis to foods coincided with the replacement of whole-cell pertussis (wP) vaccine with subunit acellular pertussis (aP) vaccine on the national immunisation schedule in the late 1990s. Atopy is characterised by a tendency to mount T helper type 2 (Th2) responses to otherwise innocuous environmental antigens. Compared with infants who receive aP as their first pertussis vaccine, those who receive wP appear less likely to mount Th2 immune responses to either vaccine or extraneous antigens. We therefore speculate that removal of wP from the vaccine schedule contributed to the observed rise in IgE-mediated food allergy among Australian infants. Methods and analysis This is a retrospective individually matched case-control study among a cohort of Australian children born from 1997 to 1999, the period of transition from wP to aP vaccines; we include in the cohort children listed on Australia's comprehensive population-based immunisation register as having received a first dose of either pertussis vaccine by 16 weeks old. 500 cohort children diagnosed as having IgE-mediated food allergy at specialist allergy clinics will be included as cases. Controls matched to each case by date and jurisdiction of birth and regional socioeconomic index will be sampled from the immunisation register. Conditional logistic regression will be used to estimate OR (±95% CI) of receipt of wP (vs aP) as the first vaccine dose among cases compared with controls. Ethics and dissemination The study is approved by all relevant human research ethics committees: Western Australia Child and Adolescent Health Services (2015052EP), Women's and Children's Hospital (HREC/15/WCHN/162), Royal Children's Hospital (35230A) and Sydney Children's Hospital Network (HREC/15/SCHN/405). Outcomes will be disseminated through publication and scientific presentation. Trial registration number NCT02490007

    Catastrophic Plate Tectonics: A Global Flood Model of Earth History

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    In 1859 Antonio Snider proposed that rapid, horizontal divergence of crustal plates occurred during Noah\u27s Flood. Modem plate tectonics theory is now confiated with assumptions of uniformity of rate and ideas of continental \u27drift\u27. Catastrophic plate tectonics theories, such as Snider proposed more than a century ago, appear capable of explaining a wide variety of data -- including Biblical and geologic data which the slow tectonics theories are incapable of explaining. We would like to propose a catastrophic plate tectonics theory as a framework for earth history. Geophysically, we begin with a pre-Flood earth differentiated into core, mantle, and crust, with the crust hOrizontally differentiated into sialic craton and mafic ocean floor. The Flood was initiated as slabs of oceanic floor broke loose and subducted along thousands of kilometers of pre-Flood continental margins. Deformation of the mantle by these slabs raised the temperature and lowered the viscosity of the mantle in the vicinity of the slabs. A resulting thermal runaway of the slabs through the mantle led to meters-per-second mantle convection. Cool oceanic crust which descended to the core/mantle boundary induced rapid reversals of the earth\u27s magnetic field. Large plumes originating near the core/mantle boundary expressed themselves at the surface as fissure eruptions and flood basalts. Flow induced in the mantle also produced rapid extension along linear belts throughout the sea floor and rapid horizontal displacement of continents. Upwelling magma jettisoned steam into the atmosphere causing intense global rain. Rapid emplacement of isostatically lighter mantle material raised the level of the ocean floor, displacing ocean water onto the continents. When virtually all the pre-Flood oceanic floor had been replaced with new,less-dense, less-subductable, oceanic crust, catastrophic plate motion stopped. Subsequent cooling increased the density of the new ocean floor, producing deeper ocean basins and a reservoir for post-Flood oceans. Sedimentologically, we begin with a substantial reservoir of carbonate and clastic sediment in the pre-Flood ocean. During the Flood hot brines associated with new ocean floor added precipitites to that sediment reservoir, and warming ocean waters and degassing magmas added carbonates - especially high magnesium carbonates. Also during the Flood, rapid plate tectonics moved pre-Flood sediments toward the continents. As ocean plates subducted near a continental margin, its bending caused upwarping of sea floor, and its drag caused downwarping 609 of continental crust, facilitating the placement of sediment onto the continental margin. Once there, earthquake induced sea waves with ocean-to-Iand movement redistributed sediment toward continental interiors. Resulting sedimentary units tend to be thick, uniform, of unknown provenance, and extend over regional, inter-regional, and even continental areas. After the Flood, the earth experienced a substantial period of isostatic readjustment, where local to regional catastrophes with intense earthquake and volcanic activity were common. Post-Flood sedimentation continued to be rapid but was dominantly basinal on the continents. Left-over heat in the new oceans produced a significantly warmer climate just after the Flood. In the following centuries, as the earth cooled, floral and faunal changes tracked the changing climate zonation. The warmer oceans caused continental transport of moisture that led to the advance of continental glaciers and ultimately to the formation of polar ice caps

    Genetic parameters, heterosis, and breed effects for body condition score and mature cow weight in beef cattle

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    Understanding the genetic relationship between mature cow weight (MWT) and body condition score (BCS) is useful to implement selection programs focused on cow efficiency. The objectives of this study were to estimate genetic parameters, heterosis, and breed effects for MWT and BCS. In total, 25,035 and 24,522 overlapping records were available for MWT and BCS on 6,138 and 6,131 cows, respectively, from the Germplasm Evaluation program, a crossbred beef population at the U.S. Meat Animal Research Center. Pedigree was available for 48,013 individuals. Univariate animal models were used to estimate heritabilities for each trait by parity. Bivariate animal models were used to estimate genetic correlations between parities within a trait and between traits within parities. Bivariate repeatability animal models were used to estimate genetic correlations between traits across parities. Estimates of heritability for different parities ranged from 0.43 ± 0.05 to 0.55 ± 0.07 for MWT and from 0.12 ± 0.03 to 0.25 ± 0.04 for BCS and were lower with the repeatability model at 0.40 ± 0.02 and 0.11 ± 0.01 for MWT and BCS, respectively. Estimates of repeatability were high for MWT (0.67 ± 0.005) and low for BCS (0.22 ± 0.006). Estimates of genetic correlation for MWT and BCS between parities were, in general, high, especially between consecutive parities. Estimates of genetic correlation between MWT and BCS were positive and moderate, ranging from 0.32 ± 0.09 to 0.68 ± 0.14. The direct heterosis estimates were 21.56 ± 3.53 kg (P ≤ 0.001) for MWT and 0.095 ± 0.034 (P ≤ 0.001) for BCS. Ordered by decreasing MWT, the breeds ranked Brahman, Charolais, Angus, Simmental, Salers, Hereford, Santa Gertrudis, Chiangus, Brangus, Red Angus, Shorthorn, Maine-Anjou, Gelbvieh, Beefmaster, Limousin, and Braunvieh. Ordered by decreasing BCS, the breeds ranked Brahman, Red Angus, Charolais, Angus, Hereford, Brangus, Beefmaster, Chiangus, Salers, Simmental, Maine-Anjou, Limousin, Santa Gertrudis, Shorthorn, Gelbvieh, and Braunvieh. Estimates of breed differences for MWT were also adjusted for BCS (AMWT), and in general, AMWT depicted smaller differences between breeds with some degree of re-ranking (r = 0.59). These results suggest that MWT and BCS are at least moderately genetically correlated and that they would respond favorably to selection. Estimates of breed differences and heterotic effects could be used to parameterize multibreed genetic evaluations for indicators of cow maintenance energy requirements

    The effects of temperature and body mass on jump performance of the locust Locusta migratoria

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    Locusts jump by rapidly releasing energy from cuticular springs built into the hind femur that deform when the femur muscle contracts. This study is the first to examine the effect of temperature on jump energy at each life stage of any orthopteran. Ballistics and high-speed cinematography were used to quantify the energy, distance, and take-off angle of the jump at 15, 25, and 35°C in the locust Locusta migratoria. Allometric analysis across the five juvenile stages at 35°C reveals that jump distance (D; m) scales with body mass (M; g) according to the power equation D = 0.35M0.17±0.08 (95% CI), jump take-off angle (A; degrees) scales as A = 52.5M0.00±0.06, and jump energy (E; mJ per jump) scales as E = 1.91M1.14±0.09. Temperature has no significant effect on the exponent of these relationships, and only a modest effect on the elevation, with an overall Q10 of 1.08 for jump distance and 1.09 for jump energy. On average, adults jump 87% farther and with 74% more energy than predicted based on juvenile scaling data. The positive allometric scaling of jump distance and jump energy across the juvenile life stages is likely facilitated by the concomitant relative increase in the total length (Lf+t; mm) of the femur and tibia of the hind leg, Lf+t = 34.9M0.37±0.02. The weak temperature-dependence of jump performance can be traced to the maximum tension of the hind femur muscle and the energy storage capacity of the femur's cuticular springs. The disproportionately greater jump energy and jump distance of adults is associated with relatively longer (12%) legs and a relatively larger (11%) femur muscle cross-sectional area, which could allow more strain loading into the femur's cuticular springs. Augmented jump performance in volant adult locusts achieves the take-off velocity required to initiate flight.Edward P. Snelling, Christie L. Becker, Roger S. Seymou
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