1,604 research outputs found

    On small Mixed Pattern Ramsey numbers

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    We call the minimum order of any complete graph so that for any coloring of the edges by kk colors it is impossible to avoid a monochromatic or rainbow triangle, a Mixed Ramsey number. For any graph HH with edges colored from the above set of kk colors, if we consider the condition of excluding HH in the above definition, we produce a \emph{Mixed Pattern Ramsey number}, denoted Mk(H)M_k(H). We determine this function in terms of kk for all colored 44-cycles and all colored 44-cliques. We also find bounds for Mk(H)M_k(H) when HH is a monochromatic odd cycles, or a star for sufficiently large kk. We state several open questions.Comment: 16 page

    Robust Machine Learning-Based Correction on Automatic Segmentation of the Cerebellum and Brainstem.

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    Automated segmentation is a useful method for studying large brain structures such as the cerebellum and brainstem. However, automated segmentation may lead to inaccuracy and/or undesirable boundary. The goal of the present study was to investigate whether SegAdapter, a machine learning-based method, is useful for automatically correcting large segmentation errors and disagreement in anatomical definition. We further assessed the robustness of the method in handling size of training set, differences in head coil usage, and amount of brain atrophy. High resolution T1-weighted images were acquired from 30 healthy controls scanned with either an 8-channel or 32-channel head coil. Ten patients, who suffered from brain atrophy because of fragile X-associated tremor/ataxia syndrome, were scanned using the 32-channel head coil. The initial segmentations of the cerebellum and brainstem were generated automatically using Freesurfer. Subsequently, Freesurfer's segmentations were both manually corrected to serve as the gold standard and automatically corrected by SegAdapter. Using only 5 scans in the training set, spatial overlap with manual segmentation in Dice coefficient improved significantly from 0.956 (for Freesurfer segmentation) to 0.978 (for SegAdapter-corrected segmentation) for the cerebellum and from 0.821 to 0.954 for the brainstem. Reducing the training set size to 2 scans only decreased the Dice coefficient ≤0.002 for the cerebellum and ≤ 0.005 for the brainstem compared to the use of training set size of 5 scans in corrective learning. The method was also robust in handling differences between the training set and the test set in head coil usage and the amount of brain atrophy, which reduced spatial overlap only by <0.01. These results suggest that the combination of automated segmentation and corrective learning provides a valuable method for accurate and efficient segmentation of the cerebellum and brainstem, particularly in large-scale neuroimaging studies, and potentially for segmenting other neural regions as well

    Knowledge and attitudes of men to prostate cancer

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    Objective: To ascertain the current level of understanding about prostate cancer (PCa), including treatment options and potential side effects of treatment, among older men. Design and Setting: Questionnaires administered by general practitioners (GPs) in 5 general practices in the Perth metropolitan and regional areas of Western Australia. Participants: Convenience sample of men aged 40-80 years (n=503) with or without prostate cancer presenting for routine consultations. Main outcome measures: Knowledge and attitudes of men to prostate cancer Results: Eighty percent of men did not know the function of the prostate and 48% failed to identify PCa as the most common internal cancer in men. Thirty-five percent had no knowledge of the treatments for PCa and 53% had no knowledge of the side effects of treatments. Asked how they would arrive at a decision about treatment, 70% stated they would ask the GP/specialist for all their options and then decide themselves. Conclusion: This study confirms a deficit in knowledge of the disease among men in the at risk age group. Lack of knowledge encompassed areas which could delay diagnosis and hence treatment. Overall the population preferred some GP/specialist involvement in treatment decision making

    Can job turnover improve technical efficiency? : a study of state-owned enterprises in Shanghai

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    This paper studies the relationship between job turnover and technical efficiency of state-owned enterprise (SOEs) in Shanghai\u27s manufacturing sector during the period of 1989-1992. Data Envelopment Analysis (DEA) is used to compute measure of technical efficiency for each enterprise. Our findings indicate that, for non-expanding SOEs, the relationship between job turnover (i.e., downsizing) and technical efficiency is a U-shaped one such that efficiency declines at low levels of turnover,but after a certain level, it starts to increase. In addition, we show that small non-expanding SOEs (i.e., with employment size less than 100) start to increase their efficiency at a lower level of turnover than other medium and large SOEs. We also find that for medium and large expanding SOEs, the turnover-efficiency relationship is a positive and linear one

    A quantitative study of spin-flip co-tunneling transport in a quantum dot

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    We report detailed transport measurements in a quantum dot in a spin-flip co-tunneling regime, and a quantitative comparison of the data to microscopic theory. The quantum dot is fabricated by lateral gating of a GaAs/AlGaAs heterostructure, and the conductance is measured in the presence of an in-plane Zeeman field. We focus on the ratio of the nonlinear conductance values at bias voltages exceeding the Zeeman threshold, a regime that permits a spin flip on the dot, to those below the Zeeman threshold, when the spin flip on the dot is energetically forbidden. The data obtained in three different odd-occupation dot states show good quantitative agreement with the theory with no adjustable parameters. We also compare the theoretical results to the predictions of a phenomenological form used previously for the analysis of non-linear co-tunneling conductance, specifically the determination of the heterostructure g-factor, and find good agreement between the two.Comment: 5 pages, 5 figure

    Low-cost high-performance W-band LNA MMICs for millimeter-wave imaging

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    The main limitation to the sensitivity of a radiometer or imager is its equivalent noise temperatures, T_e. Placing a low noise amplifier (LNA) at a radiometer's front end can dramatically reduce T_e. LNA performance has steadily improved over recent years, and here we report on a W-band LNA with the lowest T_e measured at room temperature. Furthermore, we present statistical RF data showing high yield and consistency for future high volume production that is needed for commercial radiometric imaging array applications such as security screening, aircraft landing, and other systems

    Commissioning and first light results of an L'-band vortex coronagraph with the Keck II adaptive optics NIRC2 science instrument

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    On March 2015 an L'-band vortex coronagraph based on an Annular Groove Phase Mask made up of a diamond sub-wavelength grating was installed on NIRC2 as a demonstration project. This vortex coronagraph operates in the L' band not only in order to take advantage from the favorable star/planet contrast ratio when observing beyond the K band, but also to exploit the fact that the Keck II Adaptive Optics (AO) system delivers nearly extreme adaptive optics image quality (Strehl ratios values near 90%) at 3.7μm. We describe the hardware installation of the vortex phase mask during a routine NIRC2 service mission. The success of the project depends on extensive software development which has allowed the achievement of exquisite real-time pointing control as well as further contrast improvements by using speckle nulling to mitigate the effect of static speckles. First light of the new coronagraphic mode was on June 2015 with already very good initial results. Subsequent commissioning nights were interlaced with science nights by members of the VORTEX team with their respective scientific programs. The new capability and excellent results so far have motivated the VORTEX team and the Keck Science Steering Committee (KSSC) to offer the new mode in shared risk mode for 2016B

    Providing High-Quality Care for Limited English Proficient Patients: The Importance of Language Concordance and Interpreter Use

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    Background: Provider–patient language discordance is related to worse quality care for limited English proficient (LEP) patients who speak Spanish. However, little is known about language barriers among LEP Asian-American patients. Objective: We examined the effects of language discordance on the degree of health education and the quality of interpersonal care that patients received, and examined its effect on patient satisfaction. We also evaluated how the presence/absence of a clinic interpreter affected these outcomes. Design: Cross-sectional survey, response rate 74%. Participants: A total of 2,746 Chinese and Vietnamese patients receiving care at 11 health centers in 8 cities. Measurements: Provider–patient language concordance, health education received, quality of interpersonal care, patient ratings of providers, and the presence/absence of a clinic interpreter. Regression analyses were used to adjust for potential confounding. Results: Patients with language-discordant providers reported receiving less health education (β = 0.17, p < 0.05) compared to those with language-concordant providers. This effect was mitigated with the use of a clinic interpreter. Patients with language-discordant providers also reported worse interpersonal care (β = 0.28, p < 0.05), and were more likely to give low ratings to their providers (odds ratio [OR] = 1.61; CI = 0.97–2.67). Using a clinic interpreter did not mitigate these effects and in fact exacerbated disparities in patients’ perceptions of their providers. Conclusion: Language barriers are associated with less health education, worse interpersonal care, and lower patient satisfaction. Having access to a clinic interpreter can facilitate the transmission of health education. However, in terms of patients’ ratings of their providers and the quality of interpersonal care, having an interpreter present does not serve as a substitute for language concordance between patient and provider.Version of Recor

    Effects of a short-term overfeeding with fructose or glucose in healthy young males

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    Consumption of simple carbohydrates has markedly increased over the past decades, and may be involved in the increased prevalence in metabolic diseases. Whether an increased intake of fructose is specifically related to a dysregulation of glucose and lipid metabolism remains controversial. We therefore compared the effects of hypercaloric diets enriched with fructose (HFrD) or glucose (HGlcD) in healthy men. Eleven subjects were studied in a randomised order after 7d of the following diets: (1) weight maintenance, control diet; (2) HFrD (3·5g fructose/kg fat-free mass (ffm) per d, +35% energy intake); (3) HGlcD (3·5g glucose/kg ffm per d, +35% energy intake). Fasting hepatic glucose output (HGO) was measured with 6,6-2H2-glucose. Intrahepatocellular lipids (IHCL) and intramyocellular lipids (IMCL) were measured by 1H magnetic resonance spectroscopy. Both fructose and glucose increased fasting VLDL-TAG (HFrD: +59%, P<0·05; HGlcD: +31%, P=0·11) and IHCL (HFrD: +52%, P<0·05; HGlcD: +58%, P=0·06). HGO increased after both diets (HFrD: +5%, P<0·05; HGlcD: +5%, P=0·05). No change was observed in fasting glycaemia, insulin and alanine aminotransferase concentrations. IMCL increased significantly only after the HGlcD (HFrD: +24%, NS; HGlcD: +59%, P<0·05). IHCL and VLDL-TAG were not different between hypercaloric HFrD and HGlcD, but were increased compared to values observed with a weight maintenance diet. However, glucose led to a higher increase in IMCL than fructos
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