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1.
The problem of prediction in time series using nonparametric functional techniques is considered. An extension of the local linear method to regression with functional explanatory variable is proposed. This forecasting method is compared with the functional Nadaraya–Watson method and with finite‐dimensional nonparametric predictors for several real‐time series. Prediction intervals based on the bootstrap and conditional distribution estimation for those nonparametric methods are also compared. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

2.
有机功能材料薄膜与器件   总被引:2,自引:0,他引:2  
具有光、电、磁物理功能的有机材料的出现促进新思想、新概念、新材料的发展;有机功能材料的电子状态、导电机理以及杂质的影响完全有别于无机金属和半导体,因此,在深入探索结构与功能的关系的基础上,有可能开展分子、聚集态以及器件设计的研究。若与有机化合物的结构多样化,良好的加工性、成膜和成纤性等特点相结合,有可能实现无机电子材料所难兼具的电子行为。进而实现“分子电路”的设想。这里,我们对有机功能材料的基本概念、种类,功能材料薄膜的沉积、器件的构筑,分子电子学和分子器件的概念作了一个较为全面的介绍。  相似文献   

3.
In this paper we consider a novel procedure to forecasting the US zero coupon bond yields for a continuum of maturities by using the methodology of nonparametric functional data analysis (NP‐FDA). We interpret the US yields as curves since the term structure of interest rates defines a relation between the yield of a bond and its maturity. Within the NP‐FDA approach, each curve is viewed as a functional random variable and the dynamics present in the sample are modeled without imposing any parametric structure. In order to evaluate forecast the performance of the proposed estimator, we consider forecast horizons h = 1,3,6,12… months and the results are compared with widely known benchmark models. Our estimates with NP‐FDA present predictive performance superior to its competitors in many situations considered, especially for short‐term maturities. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

4.
Protein amyloid is often deposited in connection with neurodegenerative diseases. Such deposits generally possess three principal drawbacks: cytotoxicity, lack of spatial control in their deposition and structural polymorphism. These are typical features of biologically non-optimized systems which have not been exposed to evolutionary pressure. Nevertheless, Nature uses the cross-beta self-organizing principle in many structural contexts where a strong but pliable material is needed. Functional amyloid is found in humans, invertebrates, fungi and, not least, bacteria, in which amyloid may be the rule rather than the exception. Detailed case studies reveal how directed nucleation can use tailor-made proteins optimized to assume a specific amyloid conformation, leading to remarkably robust assemblies. This makes it highly challenging to purify and analyze the products formed in vivo. We contrast pathogenic and in-vitro-formed amyloid with functional amyloid, paying particular reference to bacterial amyloid, and discuss challenges and perspectives in identifying and characterizing this class of protein.  相似文献   

5.
MicroRNAs (miRNAs) are a recently discovered family of small regulatory molecules that function by modulating protein production. There are approximately 500 known mammalian miRNA genes, and each miRNA may regulate hundreds of different protein-coding genes. Mature miRNAs bind to target mRNAs in a protein complex known as the miRNA-induced silencing complex (miRISC), sometimes referred to as the miRNP (miRNA-containing ribonucleoprotein particles), where mRNA translation is inhibited or mRNA is degraded. These actions of miRNAs have been shown to regulate several developmental and physiological processes including stem cell differentiation, haematopoiesis, cardiac and skeletal muscle development, neurogenesis, insulin secretion, cholesterol metabolism and the immune response. Furthermore, aberrant expression has been implicated in a number of diseases including cancer and heart disease. The role of miRNAs in these developmental, physiological and pathological processes will be reviewed. Received 3 August 2007; received after revision 3 October 2007; accepted 5 October 2007  相似文献   

6.
茶多酚分析方法研究与最新进展   总被引:21,自引:0,他引:21  
本文对茶多酚的各种分离方法、检测方法,在各领域的应用以及发展趋势进行分析和评述,着重介绍茶多酚的主要成分—儿茶素的高效液相色谱和毛细管电泳分析方法以及茶多酚的生物活性在生活领域的应用。  相似文献   

7.
8.
Dendritic cells (DC) are specialized antigen-presenting cells. Bone marrow monocytes have been widely used to generate murine myeloid DC. We found that mouse macrophages derived from bone marrow CD11b+ monocytes influenced the differentiation of these precursors into DC. Modulation of differentiation was demonstrated by the down-regulation of CD11c, CD40, and CD86 expression and by IL-12 production. DC differentiated in the presence of conditioned medium from bone marrow-derived macrophage culture (MCM) had impaired ability to stimulate proliferation of, and IFN- γ production by, allogeneic CD4+ T cells. This inhibition of DC differentiation was mainly mediated by secretory products from macrophages but not by cell-cell contact. MCM contained higher concentrations of macrophage-colony-stimulating factor (M-CSF), IL-10, and TGF- β1, whereas IL-6 remained unchanged compared with conditioned medium from fresh monocytes. M-CSF may be the major mediator in MCM inhibiting DC differentiation. This study demonstrates an important influence of bone marrow-derived macrophages on DC precursors during DC differentiation. Received 12 September 2006; received after revision 20 October 2006; accepted 13 November 2006  相似文献   

9.
Summary Dendritic depolarization, which seems to be involved in the induction of long-term potentiation (LTP), was elicited by localized glutamate application. When paired to low frequency synaptic activation in the same area, the subsequent changes had features in common with LTP, expressed as an increased probability of firing and shorter spike latency. The EPSP was not significantly increased.  相似文献   

10.
目的采用脑静息态功能磁共振成像技术(fMRI)观察骨性关节炎慢性疼痛患者双侧丘脑腹后外侧核(ventral posterolateral nucleus VPLN)与全脑功能连接情况。方法对16名骨性关节炎慢性疼痛患者与16名健康志愿者双侧丘脑腹外侧核(VPLN)与全脑功能连通性进行脑静息态fMRI检查,使用rest1.4软件计算并分析两组受试者VPLN与全脑功能连通性的差异(激活闽值P〈0.05,像素范围〉85)。结果骨性关节炎慢性疼痛患者双侧丘脑VPLN与额叶、枕叶等脑区功能连通性存在减弱的情况,而与小脑、中脑、海马等脑区的功能连通性增强。结论慢性疼痛患者双侧VPL与感受及编码疼痛的兴奋性大脑皮层功能连通性降低,而与参与镇痛的抑制性中枢脑区的功能连通性增加。  相似文献   

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