1,033 research outputs found

    Novel method for photovoltaic energy conversion using surface acoustic waves in piezoelectric semiconductors

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    This paper presents a novel principle for photovoltaic (PV) energy conversion using surface acoustic waves (SAWs) in piezoelectric semiconductors. A SAW produces a periodically modulated electric potential, which spatially segregates photoexcited electrons and holes to the maxima and minima of the SAW potential. The moving SAW collectively transports the carriers with the speed of sound to the electrodes made of different materials, which extract electrons and holes separately and generate dc output. The proposed active design is expected to have higher efficiency than passive designs of the existing PV devices and to produce enough energy to sustain the SAW.Comment: v.3 4 pages, 3 figures, submitted to proceedings of ECRYS-2011 to be published in Physica

    Fulminant neuroleptic malignant syndrome after perioperative withdrawal of antiParkinsonian medication

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    Neuroleptic malignant syndrome is a rare complication when using neuroleptic drugs. We report the case of a patient with severe Parkinson's disease who developed neuroleptic malignant syndrome after withdrawal of his antiParkinsonian medication for elective coronary artery bypass grafting. Sodium dantrolene may be a therapeutic option in severe case

    Mesoscopic spin confinement during acoustically induced transport

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    Long coherence lifetimes of electron spins transported using moving potential dots are shown to result from the mesoscopic confinement of the spin vector. The confinement dimensions required for spin control are governed by the characteristic spin-orbit length of the electron spins, which must be larger than the dimensions of the dot potential. We show that the coherence lifetime of the electron spins is independent of the local carrier densities within each potential dot and that the precession frequency, which is determined by the Dresselhaus contribution to the spin-orbit coupling, can be modified by varying the sample dimensions resulting in predictable changes in the spin-orbit length and, consequently, in the spin coherence lifetime.Comment: 10 pages, 2 figure

    Benefit of Apabetalone on Plasma Proteins in Renal Disease.

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    Introduction:Apabetalone, a small molecule inhibitor, targets epigenetic readers termed BET proteins that contribute to gene dysregulation in human disorders. Apabetalone has in vitro and in vivo anti-inflammatory and antiatherosclerotic properties. In phase 2 clinical trials, this drug reduced the incidence of major adverse cardiac events in patients with cardiovascular disease. Chronic kidney disease is associated with a progressive loss of renal function and a high risk of cardiovascular disease. We studied the impact of apabetalone on the plasma proteome in patients with impaired kidney function. Methods:Subjects with stage 4 or 5 chronic kidney disease and matched controls received a single dose of apabetalone. Plasma was collected for pharmacokinetic analysis and for proteomics profiling using the SOMAscan 1.3k platform. Proteomics data were analyzed with Ingenuity Pathway Analysis to identify dysregulated pathways in diseased patients, which were targeted by apabetalone. Results:At baseline, 169 plasma proteins (adjusted P value <0.05) were differentially enriched in renally impaired patients versus control subjects, including cystatin C and β2 microglobulin, which correlate with renal function. Bioinformatics analysis of the plasma proteome revealed a significant activation of 42 pathways that control immunity and inflammation, oxidative stress, endothelial dysfunction, vascular calcification, and coagulation. At 12 hours postdose, apabetalone countered the activation of pathways associated with renal disease and reduced the abundance of disease markers, including interleukin-6, plasminogen activator inhibitor-1, and osteopontin. Conclusion:These data demonstrated plasma proteome dysregulation in renally impaired patients and the beneficial impact of apabetalone on pathways linked to chronic kidney disease and its cardiovascular complications

    Genes in the postgenomic era

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    We outline three very different concepts of the gene - 'instrumental', 'nominal', and 'postgenomic'. The instrumental gene has a critical role in the construction and interpretation of experiments in which the relationship between genotype and phenotype is explored via hybridization between organisms or directly between nucleic acid molecules. It also plays an important theoretical role in the foundations of disciplines such as quantitative genetics and population genetics. The nominal gene is a critical practical tool, allowing stable communication between bioscientists in a wide range of fields grounded in well-defined sequences of nucleotides, but this concept does not embody major theoretical insights into genome structure or function. The post-genomic gene embodies the continuing project of understanding how genome structure supports genome function, but with a deflationary picture of the gene as a structural unit. This final concept of the gene poses a significant challenge to conventional assumptions about the relationship between genome structure and function, and between genotype and phenotype

    Rapid South Atlantic spreading changes and coeval vertical motion in surrounding continents: Evidence for temporal changes of pressure-driven upper mantle flow

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    International audienceThe South Atlantic region displays (1) a topographic gradient across the basin, with Africa elevated relative to South America, (2) a bimodal spreading history with fast spreading rates in Late Cretaceous and Eo-Oligocene, and (3) episodic regional uplift events in the adjacent continents concentrated in Late Cretaceous and Oligocene. Here we show that these observations can be linked by dynamic processes within Earth's mantle, through temporal changes in asthenosphere flow beneath the region. The topographic gradient implies westward, pressure-driven mantle flow beneath the basin, while the rapid spreading rate changes, on order 10 million years, require significant decoupling of regional plate motion from the large-scale mantle buoyancy distribution through a mechanically weak asthenosphere. Andean topographic growth in late Miocene can explain the most recent South Atlantic spreading velocity reduction, arising from increased plate boundary forcing associated with the newly elevated topography. But this mechanism is unlikely to explain the Late Cretaceous/Tertiary spreading variations, as changes in Andean paleoelevation at the time are small. We propose an unsteady pressure-driven flow component in the asthenosphere beneath the South Atlantic region to explain the Late Cretaceous/Tertiary spreading rate variations. Temporal changes in mantle flow due to temporal changes in regional mantle pressure gradients imply a correlation of horizontal and vertical motions: we find that this prediction from our models agrees with geologic and geophysical observations of the South Atlantic region, including episodes of passive margin uplift, regional basin reactivation, and magmatic activity

    Serving Their Needs: A Qualitative Examination of Nutrition Policy Implementation in the Early Care and Education Setting

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    Background: Childhood obesity is a growing problem in the United States and results in increased risk for chronic diseases such as diabetes, heart disease, and hypertension. Thirteen percent of youth in Georgia are obese. Identifying strategies to assist children in establishing healthy habits is essential to reduce the risk of childhood obesity. The Early Care and Education (ECE) setting is ideal for the implementation of obesity prevention practices. However, there are barriers present for implementing nutrition policies in this setting. This report explores the implementation of food and beverage best practices in the ECE setting and highlights barriers to and facilitators for adopting these policies. Methods: We conducted 24 interviews and 6 focus groups with ECE program directors and teachers in 6 regions in Georgia. The statewide sample included directors from child care learning centers, family child care homes, and license-exempt programs. A trained qualitative researcher facilitated focus groups and interviews. Data were audio recorded and transcribed verbatim. Qualitative data analysis software, NVivo 10, was used to code data and identify emergent themes. Results: Several key themes related to barriers to food and beverage policy implementation emerged including the need for: 1) enhanced parent communication, 2) resources to limit juice consumption, and 3) financial support to decrease food costs. Facilitators of nutrition policy implementation included: 1) ease of access to water, 2) children’s preferences for fruits and vegetables, and 3) availability of existing nutrition resources. Findings will inform the development of resources to support nutrition policy implementation as well as policy training for ECE teachers in Georgia. Conclusions: Study themes may provide insight about how to improve current resources and develop new solutions to improve adoption and implementation of nutrition policies in the ECE setting in the future
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