807 research outputs found

    Maximally Localized States in Quantum Mechanics with a Modified Commutation Relation to All Orders

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    We construct the states of maximal localization taking into account a modification of the commutation relation between position and momentum operators to all orders of the minimum length parameter. To first order, the algebra we use reproduces the one proposed by Kempft, Mangano and Mann. It is emphasized that a minimal length acts as a natural regulator for the theory, thus eliminating the otherwise ever appearing infinities. So, we use our results to calculate the first correction to the Casimir Effect due to the minimal length. We also discuss some of the physical consequences of the existence of a minimal length, culminating in a proposal to reformulate the very concept of "position measurement"

    Impingement of Water Droplets on an Ellipsoid with Fineness Ratio 5 in Axisymmetric Flow

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    The presence of radomes and instruments that are sensitive to water films or ice formations in the nose section of all-weather aircraft and missiles necessitates a knowledge of the droplet impingement characteristics of bodies of revolution. Because it is possible to approximate many of these bodies with an ellipsoid of revolution, droplet trajectories about an ellipsoid of revolution with a fineness ratio of 5 were computed for incompressible axisymmetric air flow. From the computed droplet trajectories, the following impingement characteristics of the ellipsoid surface were obtained and are presented in terms of dimensionless parameters: (1) total rate of water impingement, (2) extent of droplet impingement zone, (3) distribution of impinging water, and (4) local rate of water impingement

    The strong enhancer element in the immediate early region of the human cytomegalovirus genome

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    The human cytomegalovirus (HCMV), a member of the herpesvirus group, was found to possess a strong transcription enhancer in the immediate early gene region. Co-transfection of enhancerless SV40 DNA with randomly fragmented HCMV DNA yielded two SV40-like recombinant viruses , each containing HCMV DNA fragments that were substituting for the missing SV40 enhancer. The two inserts , 341 and 262 bp in length , are overlapping segments of genuine viral DNA representing part of the 5'flanking region of the major immedistte early gene i n HCMV. Studies with deletion mutants showed that different nonoverlapping subsets of the HCMV enhancer region can substitute for the 72 bp repeats of SV40. Transient expression assays indicated that the HCMV enhancer is significantly stronger than the SV40 element, activating cis-linked heterologous promoters in a wide spectrum of cultured cells. It appears that the HCMV enhancer is positively regulated by viral immediate early genes

    Freirean critical pedagogy and the decolonization of minds : importance for community colleges in the U.S. higher education system

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    As an important part of U.S. higher education, community colleges provide access to post-secondary education for students commonly underrepresented in higher education and from marginalized segments of U.S. society. These students also carry with them a long history of colonization resulting in domination, oppression and exploitation. They are susceptible to conform to workforce vocational training that emphasizes rote skills acquisition and to fitting into the corporatized society as ‘obedient’ workers. A Freirean critical pedagogy with concepts of conscientização, praxis, and questioning can constitute an avenue for students to decolonize their minds leading to awareness of possibilities and realization of potentials. Employing a Freirean critical pedagogy can also counter this kind of workforce vocational training by developing a critical pedagogy of work education as envisioned by Simon, Dippo & Schenke (1991) or a democratic vocational education as articulated by Kincheloe (1999).peer-reviewe

    A survey study of evidence-based medicine training in US and Canadian medical schools

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    PURPOSE: The authors conducted a survey examining (1) the current state of evidence-based medicine (EBM) curricula in US and Canadian medical schools and corresponding learning objectives, (2) medical educators\u27 and librarians\u27 participation in EBM training, and (3) barriers to EBM training. METHODS: A survey instrument with thirty-four closed and open-ended questions was sent to curricular deans at US and Canadian medical schools. The survey sought information on enrollment and class size; EBM learning objectives, curricular activities, and assessment approaches by year of training; EBM faculty; EBM tools; barriers to implementing EBM curricula and possible ways to overcome them; and innovative approaches to EBM education. Both qualitative and quantitative methods were used for data analysis. Measurable learning objectives were categorized using Bloom\u27s taxonomy. RESULTS: One hundred fifteen medical schools (77.2%) responded. Over half (53%) of the 900 reported learning objectives were measurable. Knowledge application was the predominant category from Bloom\u27s categories. Most schools integrated EBM into other curricular activities; activities and formal assessment decreased significantly with advanced training. EBM faculty consisted primarily of clinicians, followed by basic scientists and librarians. Various EBM tools were used, with PubMed and the Cochrane database most frequently cited. Lack of time in curricula was rated the most significant barrier. National agreement on required EBM competencies was an extremely helpful factor. Few schools shared innovative approaches. CONCLUSIONS: Schools need help in overcoming barriers related to EBM curriculum development, implementation, and assessment. IMPLICATIONS: Findings can provide a starting point for discussion to develop a standardized competency framework

    Abundance analysis of a nitrogen-rich extreme-helium hot subdwarf from the SALT survey

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    We have performed a detailed spectral analysis of the helium-rich hot subdwarf EC 20187-4939 using data obtained in the SALT survey of helium-rich hot subdwarfs. We have measured its effective temperature, surface gravity and chemical abundances from the spectrum. Its radius has also been determined by fitting the spectral energy distribution using photometric data, from which a mass of 0.44 Msun has been inferred using the measurement of surface gravity. This star is particularly abundant in helium and nitrogen, whilst being both carbon and oxygen-weak. The surface abundances and mass have been found to be consistent with a helium white dwarf merger product. The abundance effects of alpha captures on nitrogen during the merger process and possible connections between EC 20187-4939 and other carbon-weak related objects are discussed.Comment: 10 pages, 5 figures, 5 tables, accepted for publication in MNRA

    Treatment of Heart Failure with Preserved Ejection Fraction

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90240/1/phco.31.3.312.pd

    Molecular analysis of endocrine disruption in hornyhead turbot at wastewater outfalls in southern california using a second generation multi-species microarray.

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    Sentinel fish hornyhead turbot (Pleuronichthysverticalis) captured near wastewater outfalls are used for monitoring exposure to industrial and agricultural chemicals of ~ 20 million people living in coastal Southern California. Although analyses of hormones in blood and organ morphology and histology are useful for assessing contaminant exposure, there is a need for quantitative and sensitive molecular measurements, since contaminants of emerging concern are known to produce subtle effects. We developed a second generation multi-species microarray with expanded content and sensitivity to investigate endocrine disruption in turbot captured near wastewater outfalls in San Diego, Orange County and Los Angeles California. Analysis of expression of genes involved in hormone [e.g., estrogen, androgen, thyroid] responses and xenobiotic metabolism in turbot livers was correlated with a series of phenotypic end points. Molecular analyses of turbot livers uncovered altered expression of vitellogenin and zona pellucida protein, indicating exposure to one or more estrogenic chemicals, as well as, alterations in cytochrome P450 (CYP) 1A, CYP3A and glutathione S-transferase-α indicating induction of the detoxification response. Molecular responses indicative of exposure to endocrine disruptors were observed in field-caught hornyhead turbot captured in Southern California demonstrating the utility of molecular methods for monitoring environmental chemicals in wastewater outfalls. Moreover, this approach can be adapted to monitor other sites for contaminants of emerging concern in other fish species for which there are few available gene sequences

    Youth sport during the COVID-19 pandemic: The influence of race and affluence on parents’ perspectives of youth participation

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    COVID-19 restrictions led to a nearly 50% decline in youth sport participation across the United States (Dorsch et al., 2021). Today, communities and sport organizations have resumed sport. However, research has yet to fully elucidate how COVID-19 restrictions impacted youth participation across different sociodemographic groups during the pandemic. The present study explored the association between race and affluence and their relationship with parents' attitudes toward children's youth sport participation before, during, and after the COVID-19 pandemic. Online questionnaires were completed by a nationally representative sample of 3706 parents (Mage = 39.57 ± 9.03 years) who had a child regularly participating in youth sport before COVID-19. Multivariate Analyses of Variance using Tukey post-hoc tests were conducted to examine the main effect differences by race and affluence and the interactive effects of race and affluence. Results suggest that race and affluence -- independently and in combination -- were salient categorical variables of children's weekly hours of sport participation during the COVID-19 pandemic. Findings highlight that White*high affluent groups had the highest rates of sport participation during the COVID-19 pandemic and that these families desire to invest more time and money at greater rates upon returning. Theoretically, designed intersectionality research is recommended to explore further effects of race and affluence in youth sport

    Feasibility of a Clutchless Dual-Shaft Hybrid Transmission System for Performance Applications

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    A novel hybrid-electric transmission concept was sought that yields higher acceleration and smoother gear-shifts compared to existing dual-clutch systems while improving the energy efficiency of the vehicle. After evaluating a range of strategies, the elimination of the clutch was identified as a viable method for reducing the vehicle's effective inertia and viscous losses. The proposed architecture implements a single electric motor, and two separate shafts for odd and even gears, to replace the functions of a clutch. High acceleration rates can be achieved using the electric motor when launching the vehicle. Furthermore, the torque from the electric motor (EM) and internal combustion engine (ICE) can be simultaneously delivered through the two shafts to sustain this high acceleration. A 0 to 100 km/hr time of 3.18 s was simulated for a 1600 kg vehicle using a 180 kW EM and 425 kW ICE. In addition, the EM can be used to match the speeds of consecutive gears on the two shafts to reduce jerk while shifting. Shift durations were found to vary between 0.2 and 0.9 s using this strategy. Other benefits include regenerative braking and the removal of the reverse gear since the EM can rotate in either direction. It was also found that the vehicle can be operated on only electric power in urban settings - represented by the NEDC driving cycle - if the battery is recharged through regenerative braking, and by the ICE the vehicle is stopped.Massachusetts Institute of Technology. Tata Center for Technology and Desig
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