23,706 research outputs found

    Analysis of losses in 2D photonic crystal waveguides using the 3D finite difference time domain (FDTD) method

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    Calculation of losses in 2-D photonic crystal membrane waveguides using the 3-D FDTD method

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    Multiproduct firms, export product scope and trade liberalization: the role of managerial efficiency

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    This paper provides a theoretical and empirical analysis on the effects of one-sided trade liberalization on firms’ export product scope. The model explicitly incorporates the cost of managing production and sales in addition to the usually-modeled production cost. The analysis predicts that the home country’s tariff cut reduces all home firms’ export product scope; whereas in response to the foreign country’s tariff cut, a home firm’s export product scope expands (shrinks) if the firm’s management cost is low (high), independent of the firm’s production cost. These predictions are confirmed by our empirical analysis based data of Chinese firms from 2000 to 2006.postprin

    Modelling and measurement of 2D photonic crystals with tapered hole profiles

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    Vapor Pressure of Ionic Liquids

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    We argue that the extremely low vapor pressures of room temperature ionic liquids near their triple points are due to the combination of strong ionic characters and of low melting temperatures.Comment: Initially submitted manuscript of article M. Bier and S. Dietrich, Mol. Phys. 108, 211 (2010) [Corrigendum: Mol. Phys. 108, 1413 (2010)

    Links of cytoskeletal integrity with disease and aging

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    Aging is a complex feature and involves loss of multiple functions and nonreversible phenotypes. However, several studies suggest it is possible to protect against aging and promote rejuvenation. Aging is associated with many factors, such as telomere shortening, DNA damage, mitochondrial dysfunction, and loss of homeostasis. The integrity of the cytoskeleton is associated with several cellular functions, such as migration, proliferation, degeneration, and mitochondrial bioenergy production, and chronic disorders, including neuronal degeneration and premature aging. Cytoskeletal integrity is closely related with several functional activities of cells, such as aging, proliferation, degeneration, and mitochondrial bioenergy production. Therefore, regulation of cytoskeletal integrity may be useful to elicit antiaging effects and to treat degenerative diseases, such as dementia. The actin cytoskeleton is dynamic because its assembly and disassembly change depending on the cellular status. Aged cells exhibit loss of cytoskeletal stability and decline in functional activities linked to longevity. Several studies reported that improvement of cytoskeletal stability can recover functional activities. In particular, microtubule stabilizers can be used to treat dementia. Furthermore, studies of the quality of aged oocytes and embryos revealed a relationship between cytoskeletal integrity and mitochondrial activity. This review summarizes the links of cytoskeletal properties with aging and degenerative diseases and how cytoskeletal integrity can be modulated to elicit antiaging and therapeutic effects

    The radiation of cynodonts and the ground plan of mammalian morphological diversity

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    Cynodont therapsids diversified extensively after the Permo-Triassic mass extinction event, and gave rise to mammals in the Jurassic. We use an enlarged and revised dataset of discrete skeletal characters to build a new phylogeny for all main cynodont clades from the Late Permian to the Early Jurassic, and we analyse models of morphological diversification in the group. Basal taxa and epicynodonts are paraphyletic relative to eucynodonts, and the latter are divided into cynognathians and probainognathians, with tritylodonts and mammals forming sister groups. Disparity analyses reveal a heterogeneous distribution of cynodonts in a morphospace derived from cladistic characters. Pairwise morphological distances are weakly correlated with phylogenetic distances. Comparisons of disparity by groups and through time are non-significant, especially after the data are rarefied. A disparity peak occurs in the Early/Middle Triassic, after which period the mean disparity fluctuates little. Cynognathians were characterized by high evolutionary rates and high diversity early in their history, whereas probainognathian rates were low. Community structure may have been instrumental in imposing different rates on the two clades

    Parametrization of Realistic Bethe-Salpeter Amplitude for the Deuteron

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    The parametrization of the realistic Bethe-Salpeter amplitude for the deuteron is given. Eight components of the amplitude in the Euclidean space are presented as an analytical fit to the numerical solution of the Bethe-Salpeter equation in the ladder approximation. An applicability of the parametrization to the observables of the deuteron is briefly discussed.Comment: LaTeX, 11 pages, 2 Postscript figures; Text of the Fortran program is available from the author by reques

    Upper ocean variability in the Bay of Bengal during the tropical cyclones Nargis and Laila

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    Upper ocean variability at different stages in the evolution of the tropical cyclones Nargis and Laila is evaluated over the Bay of Bengal (BoB) during May 2008 and May 2010 respectively. Nargis initially developed on 24 April 2008; intensified twice on 27–28 April and 1 May, and eventually made landfall at Myanmar on 2 May 2008. Laila developed over the western BoB in May 2010 and moved westward towards the east coast of India. Data from the Argo Profiling floats, the Research Moored Array for African–Asian–Australian Monsoon Analysis and prediction (RAMA), and various satellite products are analyzed to evaluate upper ocean variability due to Nargis and Laila. The analysis reveals pre-conditioning of the central BoB prior to Nargis with warm (>30 °C) Sea Surface Temperature (SST), low (<33 psu) Sea Surface Salinity (SSS) and shallow (<30 m) mixed layer depths during March–April 2008. Enhanced ocean response to the right of the storm track due to Nargis includes a large SST drop by ∼1.76 °C, SSS increase up to 0.74 psu, mixed layer deepening of 32 m, shoaling of the 26 °C isotherm by 36 m and high net heat loss at the sea surface. During Nargis, strong inertial currents (up to 0.9 ms−1) were generated to the right of storm track as measured at a RAMA buoy located at 15 °N, 90 °E, producing strong turbulent mixing that lead to the deepening of mixed layer. This mixing facilitated entrainment of cold waters from as deep as 75 m and, together with net heat loss at sea surface and cyclone-induced subsurface upwelling, contributed to the observed SST cooling in the wake of the storm. A similar upper ocean response occurs during Laila, though it was a significantly weaker storm than Nargi
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