8,624 research outputs found

    A systematic experimental investigation of significant parameters affecting model tire hydroplaning

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    The results of a comprehensive parametric study of model and small pneumatic tires operating on a wet surface are presented. Hydroplaning inception (spin down) and rolling restoration (spin up) are discussed. Conclusions indicate that hydroplaning inception occurs at a speed significantly higher than the rolling restoration speed. Hydroplaning speed increases considerably with tread depth, surface roughness and tire inflation pressure of footprint pressure, and only moderately with increased load. Water film thickness affects spin down speed only slightly. Spin down speed varies inversely as approximately the one-sixth power of film thickness. Empirical equations relating tire inflation pressure, normal load, tire diameter and water film thickness have been generated for various tire tread and surface configurations

    Total Knee Arthroplasty Prehabilitation: Clinical Decisions related to Bony Malalignment, Neurologic Complexities, and Getting to Know a Patient

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    Background: The benefits of pre-operative habilitation or “prehabilitation” for total knee arthroplasty outcomes have been documented and researched over the last twenty years. However, the majority of these studies do not describe prehabilitation programs for patients with complex neurologic comorbidities. Purpose: The purpose of this case report is to describe clinical decisions made during the course of a prehabilitation program for a patient with a cerebellar disorder and bony malformation at her knee. Case Description: The patient was diagnosed with excessive tibial torsion when she was 60 years old and a year later diagnosed with uterine cancer and paraneoplastic cerebellar degeneration. The patient currently shows significant genu valgum at her right lower extremity and ambulates using a four wheeled walker, bilateral knee braces donned, and has an ataxic gait. Her goals for therapy are to improve her strength as she anticipates having a total knee arthroplasty, improve her balance, and stay active. Outcome Measures: Timed Up and Go (TUG), Berg Balance Scale, Dynamometer, as well as mass of weights lifted were used as outcome measures. Discussion: Low-load, high repetition and open kinetic chain movements were optimal means of strengthening for this particular patient, addressing both bony malformation and neurologic deficits. Additionally, the patient’s Timed Up and Go and Berg Balance Scale showed meaningful changes, possibly in part because the patient had good afferent signaling, but also because of the large amounts of time the patient dedicated to rehabilitation

    Truncated unity functional renormalization group for multiband systems with spin-orbit coupling

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    Although the functional renormalization group (fRG) is by now a well-established method for investigating correlated electron systems, it is still undergoing significant technical and conceptual improvements. In particular, the motivation to optimally exploit the parallelism of modern computing platforms has recently led to the development of the "truncated-unity" functional renormalization group (TU-fRG). Here, we review this fRG variant, and we provide its extension to multiband systems with spin-orbit coupling. Furthermore, we discuss some aspects of the implementation and outline opportunities and challenges ahead for predicting the ground-state ordering and emergent energy scales for a wide class of quantum materials.Comment: consistent with published version in Frontiers in Physics (2018

    On the π\pi and KK as qqˉq \bar q Bound States and Approximate Nambu-Goldstone Bosons

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    We reconsider the two different facets of π\pi and KK mesons as qqˉq \bar q bound states and approximate Nambu-Goldstone bosons. We address several topics, including masses, mass splittings between π\pi and ρ\rho and between KK and K∗K^*, meson wavefunctions, charge radii, and the K−πK-\pi wavefunction overlap.Comment: 15 pages, late

    Place-based policies and spatial disparities across European cities

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    Spatial disparities in income levels and worklessness in the European Union are profound, persistent and may be widening. We describe disparities across metropolitan regions and discuss theories and empirical evidence that help us understand what causes these disparities. Increases in the productivity benefits of cities, the clustering of highly educated workers and increases in their wage premium all play a role. Europe has a long-standing tradition of using capital subsidies, enterprise zones, transport investments and other place-based policies to address these disparities. The evidence suggests these policies may have partially offset increasing disparities but are not sufficient to fully offset the economic forces at work

    Letter from the Founders

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    Increase in hospital admissions for acute childhood asthma in Cape Town, 1978 - 1990

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    To determine whether hospital admissions for acute childhood asthma were rising in Cape Town in line with the experience of other countries, Red Cross War Memorial Children's Hospital's records for the period 1978 - 1990 were analysed. These were compared with total admissions for non-surgical causes and lower respiratory tract illness as well as those for bronchiolitis and pneumonia. Asthma admissions showed a sharp upward trend from 1978 to 1984, a slower rise through 1987 and a levelling off since. The profile of hospital admissions for respiratory illness was also analysed. Black children were under-represented among asthma admissions compared with those for pneumonia. Asthma admissions occurred throughout the year but showed seasonal peaks in May and November. Reasons for these trends and patterns are discussed, as well as hypotheses for further research into the epidemiology of asthma in South Africa

    Advanced experimental applications for x-ray transmission gratings Spectroscopy using a novel grating fabrication method

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    A novel fabrication method for soft x-ray transmission grating and other optical elements is presented. The method uses Focused-Ion-Beam (FIB) technology to fabricate high-quality free standing grating bars on Transmission Electron Microscopy grids (TEM-grid). High quality transmission gratings are obtained with superb accuracy and versatility. Using these gratings and back-illuminated CCD camera, absolutely calibrated x-ray spectra can be acquired for soft x-ray source diagnostics in the 100-3000 eV spectral range. Double grating combinations of identical or different parameters are easily fabricated, allowing advanced one-shot application of transmission grating spectroscopy. These applications include spectroscopy with different spectral resolutions, bandwidths, dynamic ranges, and may serve for identification of high-order contribution, and spectral calibrations of various x-ray optical elements

    Anthelmintic resistance in ovine gastrointestinal nematodes in inland southern Queensland

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    Objective To establish the prevalence of anthelmintic resistance in ovine gastrointestinal nematodes in southern Queensland. Design An observational parasitological study using the faecal egg count reduction test. Methods Sheep farms (n = 20) enrolled in this study met the twin criteria of using worm testing for drench decisions and having concerns about anthelmintic efficacy. On each farm, 105 sheep were randomly allocated to one of six treatment groups or an untreated control group. Faecal samples were collected on day 0 and days 10–14 for worm egg counts and larval differentiation. Single- and multi-combination anthelmintics, persistent and non-persistent, oral liquid or capsule, pour-on and injectable formulations were tested. Monepantel was not tested. Farmers also responded to a questionnaire on drenching practices. Results Haemonchus contortus was the predominant species. Efficacy <95% was recorded on 85% of farms for one or more anthelmintics and on 10% of farms for six anthelmintics. No resistance was identified on three farms. The 4-way combination product was efficacious (n = 4 farms). Napthalophos resistance was detected on one farm only. Resistance to levamisole (42% of farms), moxidectin injection (50% of farms) and the closantel/abamectin combination (67% of farms) was identified. Moxidectin oral was efficacious against Trichostrongylus colubriformis, which was predominant on only one farm. Of the farms tested, 55% ran meat breeds, 60% dosed more than the recommended dose rate and 70% always, mostly or when possible practised a ‘drench and move’ strategy. Conclusion This level of anthelmintic resistance in southern Queensland will severely compromise worm control and force increased use of monepantel

    The MAHB, the Culture Gap, and Some Really Inconvenient Truths

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    Humanity's failure to take adequate actions to stem a likely environmental collapse calls for extraordinary measures to understand and alter human behavior, argues Paul Ehrlich. His Millennium Assessment of Human Behavior (MAHB) aims to chart the path to a sustainable future
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