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For censored response variable against projected co-variable, a generalized linear model with an unknown link function can cover almost all existing models under censorship. Its special cases include the accelerated failure time m...
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For censored response variable against projected co-variable, a generalized linear model with an unknown link function can cover almost all existing models under censorship. Its special cases include the accelerated failure time model with censored data. Such a model in the uncensored case is called the single-index model in econometrics. In this paper, we systematically study the asymptotic properties. We derive the central limit theorem and the law of the iterated logarithm for an estimator of the direction parameter. We also obtain the optimal convergence rate of an estimator of the unknown link function in the model.
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Dendritic cells (DCs) are professional antigen-presenting cells that have the ability to sense infection and tissue stress, sample and present antigen to T lymphocytes, and induce different forms of immunity and tolerance. The fun...
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Dendritic cells (DCs) are professional antigen-presenting cells that have the ability to sense infection and tissue stress, sample and present antigen to T lymphocytes, and induce different forms of immunity and tolerance. The functional versatility of DCs depends on their remarkable ability to translate collectively the information from both the invading microbes and their resident tissue microenvironments and then make an appropriate immune response. Recent progress in understanding TLR biology has illuminated the mechanisms by which DCs link innate and adaptive antimicrobial immune responses. However, how tissue microenvironments shape the function of DCs has remained elusive. Recent studies of TSLP (thymic stromal lymphopoietin), an epithelial cell-derived cytokine that strongly activates DCs, provide evidence at a molecular level that epithelial cells/tissue microenvironments directly communicate with DCs. We review recent progress on how TSLP expressed within thymus and peripheral lymphoid and nonlymphoid tissues regulates DC-mediated central tolerance, peripheral T cell homeostasis, and inflammatory Th2 responses.
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As a truly meshless method of boundary-type, the hybrid boundary node method (HBNM) has the advantages of both boundary element method (BEM) and meshless method. The main problem is that it is only suitable for the homogeneous pro...
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As a truly meshless method of boundary-type, the hybrid boundary node method (HBNM) has the advantages of both boundary element method (BEM) and meshless method. The main problem is that it is only suitable for the homogeneous problems. Now, the dual reciprocity method (DRM) is introduced into HBNM to deal with the integral for the inhomogeneous terms of the governing equations, and the rigid body motion approach is employed to solve the hyper-singular integrations. A new meshless method named dual reciprocity hybrid boundary node method (DRHBNM) is proposed and applied to solve free vibration problems. In this method, the solution composes into two parts, i.e., the general solution and the particular solution. The general solution is solved by HBNM and the particular one is obtained by DRM. DRHBNM is a true boundary-type meshless method. It does not require the 'boundary element mesh', either for the purpose of interpolation of the variables, or for the integration of 'energy'. The points in the domain are only used to interpolate particular solution by the radial basis function. Finally, the boundary variables are interpolated by the independent smooth boundary segments. The Q-R algorithm and Householder algorithm are applied to solve the eigenvalues and eigenvectors of the transformed matrix. Numerical examples for free vibration problems show that a good convergence with mesh refinement is achievable and the computational results for the natural circular frequencies and free vibration modes are very accurate. Furthermore, the computation parameters have little influence on the results and can be chosen in a wide range. It is shown that the present method is effective and can be widely applied in practical engineering. (C) 2008 Elsevier Ltd. All rights reserved.
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From a rare freshwater lake characteristic of alkalescence, named "Cattle Pond", on the Dongdao Island of South China Sea (16 degrees 39'-16 degrees 41'N, 112 degrees 43'-112 degrees 45'E), we collected two undisturbed sediment co...
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From a rare freshwater lake characteristic of alkalescence, named "Cattle Pond", on the Dongdao Island of South China Sea (16 degrees 39'-16 degrees 41'N, 112 degrees 43'-112 degrees 45'E), we collected two undisturbed sediment cores that contain seabird droppings. In this paper, we determined the concentration-versus-depth profiles of the geochemical elements in the ornithogenic sediment layers of the two cores, analyzed these profiles by various statistical methods, and studied their geochemical characteristics. The concentration profiles of As, Cd, Cu, Se, Zn, P and S are significantly correlated with each other and with loss on ignition (LOI) at 550 degrees C, the measure for the abundance of organic matter. Similar geochemical characteristics, however, were not observed in the upper sediment layer of the Cattle Pond notably affected by cattle excrements, as well as in the bottom sediment layer compositionally dominated by coral sand and gravel. This shows that these "bio-elements" are mainly derived from seabird feces and their geochemical composition is an important geochemical characteristic of the lacustrine ornithogenic sediments. By Q-mode factor analysis (QFA) on the concentration profiles of these bio-elements, we reconstructed the historical seabird population on Dongdao Island between 1350 and 350 year B.P., and observed significant fluctuations in the calculated population. The fluctuations seem to be related to the change of sea surface temperature (SST) in the Southern China Sea. This study provides new paleoenvironmental information of past seabird population changes in low latitude areas using an indirect geochemical method.
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Cardiac slow delayed rectifier (I(Ks)) channel complex consists of KCNQ1 channel and KCNE1 auxiliary subunits. The extracellular juxtamembranous region of KCNE1 is an unstructured loop that contacts multiple KCNQ1 positions in a g...
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Cardiac slow delayed rectifier (I(Ks)) channel complex consists of KCNQ1 channel and KCNE1 auxiliary subunits. The extracellular juxtamembranous region of KCNE1 is an unstructured loop that contacts multiple KCNQ1 positions in a gating-state-dependent manner. Congenital arrhythmia-related mutations have been identified in the extracellular S1-S2 linker of KCNQ1. These mutations manifest abnormal phenotypes only when coexpressed with KCNE1, pointing to the importance of proper KCNQ1/KCNE1 interactions here in I(Ks) channel function. We investigate the interactions between the KCNE1 loop (positions 36-47) and KCNQ1 S1-S2 linker (positions 140-148) by means of disulfide trapping and voltage clamp techniques. During transitions among the resting-state conformations, KCNE1 positions 36-43 make contacts with KCNQ1 positions 144, 145, and 147 in a parallel fashion. During conformational changes in the activated state, KCNE1 position 40 can make contacts with all three KCNQ1 positions, while the neighboring KCNE1 positions (36, 38, 39, and 41) can make contact with KCNQ1 position 147. Furthermore, KCNQ1 positions 143 and 146 are high-impact positions that cannot tolerate cysteine substitution. To maintain the proper I(Ks) channel function, position 143 requires a small side chain with a hydroxyl group, and position 146 requires a negatively charged side chain. These data and the proposed molecular motions provide insights into the mechanisms by which mutations in the extracellular juxtamembranous region of the I(Ks) channel impair its function.
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The mandibular processes are specified as at least two independent functional regions: two large lateral regions where morphogenesis is dependent on fibroblast growth factor (FGF)-8 signaling, and a small medial region where morph...
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The mandibular processes are specified as at least two independent functional regions: two large lateral regions where morphogenesis is dependent on fibroblast growth factor (FGF)-8 signaling, and a small medial region where morphogenesis is independent of FGF-8 signaling. To gain insight into signaling pathways that may be involved in morphogenesis of the medial region, we have examined the roles of pathways regulated by FGFs and bone morphogenetic proteins (BMPs) in morphogenesis of the medial and lateral regions of the developing chick mandible. Our results show that, unlike in the lateral region, the proliferation and growth of the mesenchyme in the medial region is dependent on signals derived from the overlying epithelium. We also show that medial and lateral mandibular mesenchyme respond differently to exogenous FGFs and BMPs. FGF-2 and FGF-4 can mimic many of the effects of mandibular epithelium from the medial region, including supporting the expression of Msx genes, outgrowth of the mandibular processes and elongation of Meckel's cartilage. On the other hand, laterally placed FGF beads did not induce ectopic expression of Msx genes and did not affect the growth of the mandibular processes. These functional studies, together with our tissue distribution studies, suggest that FGF-mediated signaling (other than FGF-8), through interactions with FGF receptor-2 and downstream target genes including Msx genes, is part of the signaling pathway that mediates the growth-promoting interactions in the medial region of the developing mandible. Our observations also suggest that BMPs play multiple stage- and region-specific roles in mandibular morphogenesis. In this study, we show that exogenous BMP-7 applied to the lateral region at early stages of development (stage 20) caused apoptosis, ectopic expression of Msx genes, and inhibited outgrowth of the mandibular processes and the formation of Meckel's cartilage. Our additional experiments suggest that the differences between the effects of BMP-7 on lateral mandibular mesenchyme at stage 20 and previously reported results at stage 23 (Wang et al., [1999] Dev. Dyn. 216:320-335) are related to differences in stages of differentiation in that BMP-7 promotes apoptosis in undifferentiated lateral mandibular mesenchyme, whereas it promotes chondrogenesis at later stages of development. We also showed that, unlike mandibular epithelium and medially placed FGF beads, medially placed BMP-7 did not support outgrowth of the isolated mesenchyme and at stage 20 induced the formation of a duplicated rod of cartilage extending from the body of Meckel's cartilage. These observations suggest that BMPs do not play essential roles in growth-promoting interactions in the medial region of the developing mandible. However, BMP-mediated signaling is a part of the signaling pathways regulating chondrogenesis of the mandibular mesenchyme.
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Sheng-Mai San (SMS), a traditional Chinese medicine formula, has been used for the treatment of cardiovascular disease in Asia over long period of time. While its effectiveness has been confirmed by clinical use, its active chemic...
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Sheng-Mai San (SMS), a traditional Chinese medicine formula, has been used for the treatment of cardiovascular disease in Asia over long period of time. While its effectiveness has been confirmed by clinical use, its active chemical constituents remain unclear. In this paper, an HPLC-DAD-MS/MS method is described for the efficient and rapid identification of the chemical constituents in SMS extract. MS/MS fragmentation behavior of authentic compounds was proposed for aiding the structural identification of the components. A total of 53 compounds were identified or tentatively characterized by comparing their retention times, UV and MS spectra with those of authentic compounds or literature data. HPLC/UV and MS techniques were employed to screen for the potential bioactive components in rat plasma after oral administration of SMS. Twenty-five compounds including 14 prototype components and 11 metabolites were detected in dosed rat plasma compared with blank rat plasma. This identification and structural elucidation of the chemical constituents in the medicine formula and rat plasma may provide important experimental data for further pharmacological and clinical research.
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In this paper, the existence of (L-2(R-n), L-2 (R-n))-pullback attractors and (L-2(R-n), H-1 (R-n))-pullback attractors are proved for reaction-diffusion equation in unbounded domains. (c) 2007 Elsevier Inc. All rights reserved.
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Low-order models (LOM) described by a system of nth-order (nonlinear) ordinary differential equations (ODE) of the type (x) over dot (i) = x(T) A((i))x + B(i)x + c(i). i = 1, 2,..., n (where x is a column vector, A((i)) is a n x n...
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Low-order models (LOM) described by a system of nth-order (nonlinear) ordinary differential equations (ODE) of the type (x) over dot (i) = x(T) A((i))x + B(i)x + c(i). i = 1, 2,..., n (where x is a column vector, A((i)) is a n x n matrix, B-i is a row vector, c(i) is a scalar and T denotes the transpose) routinely arise when we apply the Galerkin type projection techniques to the quasi-geostrophic potential vorticity equation (with forcing, dissipation and topography), Rayleigh-Bernard convection and Burgers' equation, to mention a few. To Our knowledge there is no systematic method for testing if a given LOM conserves energy. Our goal in this paper is twofold. First, we derive a set of sufficient conditions on the structural parameters (A((i)), B-i and c(i) for i = 1, 2,..., n) for conserving energy. It is well known in Mathematical Physics that the Volterra gyrostat and many of its special cases including the Euler gyroscope represent a prototype of energy conserving dynamical systems. It turns out that a special case of our sufficient condition is closely related to the Volterra gyrostats. Exploiting this relation, we then derive an algorithm for rewriting the LOM (corresponding to the special case of our sufficient conditions) as a system of coupled gyrostats which brings out the inherent relation between the energy conserving LOM and the system Of Coupled gyrostats. (C) 2007 Elsevier Ltd. All rights reserved.
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Illumination variation is one of the critical factors affecting face recognition rate. A novel approach for human face illumination compensation is presented in this paper. It constructs the nine-dimension face illumination subspa...
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Illumination variation is one of the critical factors affecting face recognition rate. A novel approach for human face illumination compensation is presented in this paper. It constructs the nine-dimension face illumination subspace based on quotient image. In addition, with the aim to improve algorithm efficiency, a half-face illumination image is proposed and the low-dimension training set of the face image under different illumination conditions are obtained by means of PICA and wavelet transform. After processing, two different illumination compensation strategies are given: one is adding light, and the other is removing light. Based on the illumination compensation strategy, we implement the typical illumination sample image synthesis and the standard illumination sample image synthesis on a PCA feature subspace and a wavelet transform subspace, respectively, and the illumination compensation of the gray images and the color images are further realized. Experimental results based on the Yale Face Database B, the Extended Yale Face Database B and the CAS-PEAL Face Database indicate that execution time after compensation is approximately half the time and face recognition rate is improved by 20% compared with that of the original images. (C) 2008 Elsevier Inc. All rights reserved.
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