433 research outputs found

    Quantum-mechanical wavepacket transport in quantum cascade laser structures

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    We present a viewpoint of the transport process in quantum cascade laser structures in which spatial transport of charge through the structure is a property of coherent quantum-mechanical wavefunctions. In contrast, scattering processes redistribute particles in energy and momentum but do not directly cause spatial motion of charge.Comment: 6 pages, 5 figures included in tex, to appear in Physical Review

    An order for asymmetry in copulas, and implications for risk management

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    We investigate symmetry properties of bivariate copulas. For this, we introduce an order of asymmetry, as well as measures of asymmetry which are monotone in that order. As for applications, we show that asymmetry does occur in real financial data. This implies that in finance and risk management, asymmetric models should be favored against the usual symmetric ones

    An order for asymmetry in copulas, and implications for risk management

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    We investigate symmetry properties of bivariate copulas. For this, we introduce an order of asymmetry, as well as measures of asymmetry which are monotone in that order. As for applications, we show that asymmetry does occur in real financial data. This implies that in finance and risk management, asymmetric models should be favored against the usual symmetric ones

    Аналіз деформування матеріалу з множинними тріщинами термомеханічної втоми як розломно-блокового середовища

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    Recent advances in cancer biology have emerged important roles for microRNAs (miRNAs) in regulating tumor responses. However, their function in mediating intercellular communication within the tumor microenvironment is thus far poorly explored. Here, we found miR-206 to be abrogated in human pancreatic ductal adenocarcinoma (PDAC) specimens and cell lines. We show that miR-206 directly targets the oncogenes KRAS and annexin a2 (ANXA2), thereby acting as tumor suppressor in PDAC cells by blocking cell cycle progression, cell proliferation, migration and invasion. Importantly, we identified miR-206 as a negative regulator of oncogenic KRAS-induced nuclear factor-kappa B transcriptional activity, resulting in a concomitant reduction of the expression and secretion of pro-angiogenic and pro-inflammatory factors including the cytokine interleukin-8, the chemokines (C-X-C motif) ligand 1 and (C-C motif) ligand 2, and the granulocyte macrophage colony-stimulating factor. We further show that miR-206 abrogates the expression and secretion of the potent pro-lymphangiogenic factor vascular endothelial growth factor C in pancreatic cancer cells through an NF-kappa B-independent mechanism. By using in vitro and in vivo approaches, we reveal that re-expression of miR-206 in PDAC cells is sufficient to inhibit tumor blood and lymphatic vessel formation, thus leading to a significant delay of tumor growth and progression. Taken together, our study sheds light onto the role of miR-206 as a pleiotropic modulator of different hallmarks of cancer, and as such raising the intriguing possibility that miR-206 may be an attractive candidate for miRNA-based anticancer therapies.Funding Agencies|German Federal Ministry of Education and Research (NGFN grant) [01GS0816]; Deutsche Forschungsgemeinschaft (DIP project) [WI3499/1-1]</p

    Carcass Yield and Subprimal Cutout Value of Beef, High- and Low-Yielding Beef × Dairy, and Dairy Steers

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    This study compared carcass yield and cutout value of conventional beef and dairy cattle to high-yielding (HY) and low-yielding (LY) crossbred beef × dairy cattle and identified the contribution of carcass regions to carcass yield andcutout value among beef × dairy crossbreds. Carcasses of conventional beef, beef × dairy crossbred, and dairy cattle were selected according to industry-average slaughter endpoints for their cattle type. Carcasses were fabricated at a commercial processing facility, and weights of carcass components were obtained. Post hoc subsampling was used to segregate HY and LY beef × dairy crossbreds based on subprimal yield. Multiple linear regression was used to assess carcass yield and sub-primal cutout value between the 4 cattle types (n=21 to 26 per cattle type). Beef cattle and HY crossbreds produced 1.59 to 3.04 percentage units greater (P&lt;0.05) subprimal yield than LY crossbreds and dairy cattle. Dairy cattle produced at least 1.16 percentage units more (P&lt;0.05) bone than any other cattle type. Subprimal to bone was not different (P&gt;0.05) between HY crossbreds and beef cattle, and subprimal to fat was lesser (P&lt;0.05) in HY crossbreds than beef cattle. Subprimal cutout value was more than 5 US dollars (USD)/45.4 kg different (P&lt;0.05) between cattle types, which were ranked HY crossbreds &gt; beef cattle &gt; LY crossbreds &gt; dairy cattle. In beef × dairy cattle, subprimal to bone in the round contributed most greatly to an increase (P=0.02), by 3.79 USD/45.4 kg, in subprimal cutout value. Together, these results suggested carcass value of beef × dairy cattle may be maximized when cattle are harvested at a lesser overall fatness than conventional beef cattle and when considerable muscling, especially in the round, is achieved

    Optimizing the use of continuous glucose monitoring in young children with type 1 diabetes with an adaptive study design and multiple randomizations

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    Parents of young children with type 1 diabetes (T1D) experience unique, developmental challenges in managing their child's T1D, resulting in psychosocial distress. Only a small portion of young children reach glucose goals and adherence to diabetes devices that help improve T1D management have historically been low in this population. The purpose of this study is to test four interventions that couple developmentally tailored behavioral supports with education to optimize use of diabetes devices, improve glucose control, and reduce psychosocial distress for parents of young children with T1D. The study team designed four behavioral interventions, two aimed at improving glucose control and two aimed at optimizing use of diabetes devices. The goal of this paper is to describe the behavioral interventions developed for this study, including the results of a pilot test, and describe the methods and analysis plan to test this intervention strategy with ninety participants in a large-scale, randomized trial using a sequential multiple assignment randomization trial (SMART) design. A SMART design will permit a clinically relevant evaluation of the intervention strategy, as it allows multiple randomizations based on individualized assessments throughout the study instead of a fixed intervention dose seen in most traditional randomized controlled trials

    Amyloid-like aggregates sequester numerous metastable proteins with essential cellular functions

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    Protein aggregation is linked with neurodegeneration and numerous other diseases by mechanisms that are not well understood. Here, we have analyzed the gain-of-function toxicity of artificial β sheet proteins that were designed to form amyloid-like fibrils. Using quantitative proteomics, we found that the toxicity of these proteins in human cells correlates with the capacity of their aggregates to promote aberrant protein interactions and to deregulate the cytosolic stress response. The endogenous proteins that are sequestered by the aggregates share distinct physicochemical properties: They are relatively large in size and significantly enriched in predicted unstructured regions, features that are strongly linked with multifunctionality. Many of the interacting proteins occupy essential hub positions in cellular protein networks, with key roles in chromatin organization, transcription, translation, maintenance of cell architecture and protein quality control. We suggest that amyloidogenic aggregation targets a metastable subproteome, thereby causing multifactorial toxicity and, eventually, the collapse of essential cellular functions. PaperFlick: © 2011 Elsevier Inc

    Exploring the limits of ultracold atoms in space

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    Existing space-based cold atom experiments have demonstrated the utility of microgravity for improvements in observation times and for minimizing the expansion energy and rate of a freely evolving coherent matter wave. In this paper we explore the potential for space-based experiments to extend the limits of ultracold atoms utilizing not just microgravity, but also other aspects of the space environment such as exceptionally good vacuums and extremely cold temperatures. The tantalizing possibility that such experiments may one day be able to probe physics of quantum objects with masses approaching the Planck mass is discussed
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