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This paper presents the results of the Electric Power Research Institute Short Range Forecasting Project (EPRI-SRF) performed by the Load Forecasts Department, Economics and Forecasts Division of Ontario Hydro, Ontario, Canada. In this study a variety of short-range forecasting techniques are applied to Ontario Hydro monthly data on total system energy demand. These techniques are available in a software package (FORECAST MASTER) developed for EPRI by two consultants—Scientific Systems, Inc. (SSI) and Quantitativ Economic Research, Inc. (QUERI). The methods used for this study were the univariate Box-Jenkins method, the multivariate state-space method, Bayesian vector autoregression and autoregress ve econometric regression. A comparison of the models developed show that the econometric models perform the best overall. The state-space models are more suitable for very short-term (one-step ahead) forecasts. Although the Box-Jenkins method has the advantage of simplicity in terms of estimation and data requirement, its performance was not as good as that of the others. Bayesian vector autoregresson results indicate that this program needs some modification for monthly data.  相似文献   
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Hattori D  Demir E  Kim HW  Viragh E  Zipursky SL  Dickson BJ 《Nature》2007,449(7159):223-227
Neurons are thought to use diverse families of cell-surface molecules for cell recognition during circuit assembly. In Drosophila, alternative splicing of the Down syndrome cell adhesion molecule (Dscam) gene potentially generates 38,016 closely related transmembrane proteins of the immunoglobulin superfamily, each comprising one of 19,008 alternative ectodomains linked to one of two alternative transmembrane segments. These ectodomains show isoform-specific homophilic binding, leading to speculation that Dscam proteins mediate cell recognition. Genetic studies have established that Dscam is required for neural circuit assembly, but the extent to which isoform diversity contributes to this process is not known. Here we provide conclusive evidence that Dscam diversity is essential for circuit assembly. Using homologous recombination, we reduced the entire repertoire of Dscam ectodomains to just a single isoform. Neural circuits in these mutants are severely disorganized. Furthermore, we show that it is crucial for neighbouring neurons to express distinct isoforms, but that the specific identity of the isoforms expressed in an individual neuron is unimportant. We conclude that Dscam diversity provides each neuron with a unique identity by which it can distinguish its own processes from those of other neurons, and that this self-recognition is essential for wiring the Drosophila brain.  相似文献   
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1 Results Biotransformations are enzyme- and whole cell-catalysed conversions of non-natural substrates to products.They are important tools in organic synthesis,especially for the syntheses of chiral molecules,where the reactions catalysed may be asymmetric syntheses or the resolution of racemates.The main advantages associated with the use of single enantiomer compounds are increased specificity and the avoidance of adverse side effects[1].Whole cell reactions are advantegous over enzyme-catalyzed rea...  相似文献   
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I distinguish between two ways in which Kuhn employs the concept of incommensurability based on for whom it presents a problem. First, I argue that Kuhn’s early work focuses on the comparison and underdetermination problems scientists encounter during revolutionary periods (actors’ incommensurability) whilst his later work focuses on the translation and interpretation problems analysts face when they engage in the representation of science from earlier periods (analysts’ incommensurability). Secondly, I offer a new interpretation of actors’ incommensurability. I challenge Kuhn’s account of incommensurability which is based on the compartmentalisation of the problems of both underdetermination and non-additivity to revolutionary periods. Through employing a finitist perspective, I demonstrate that in principle these are also problems scientists face during normal science. I argue that the reason why in certain circumstances scientists have little difficulty in concurring over their judgements of scientific findings and claims while in others they disagree needs to be explained sociologically rather than by reference to underdetermination or non-additivity. Thirdly, I claim that disagreements between scientists should not be couched in terms of translation or linguistic problems (aspects of analysts’ incommensurability), but should be understood as arising out of scientists’ differing judgments about how to take scientific inquiry further.  相似文献   
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Chickpea is an important food legume crop of Turkey and is largely grown for human consumption on low moisture or salt-affected soils. The objective of the study was to find the effects of NaCl stress at electrical conductivities of 4.5, 8.6, 12.7 and 16.3 dS/m and seed sizes (7, 8 and 9 mm) on germination and early seedling growth of three popular chickpea cultivars (AKN-97, Gokce and Uzunlu-99). Mean frequency of germination, germination time, germination index, root length, shoot length and seedling fresh weight showed seed size-dependent responses ofcultivars to salt stress. In general, small seeds germinated and grew more rapidly compared to medium and large seeds of the same cultivars against all levels of salt stress, with the best results in cultivar Uzunlu-99. No effect of NaCl treatments was observed on frequency of germination; however, a drastic decrease in early seedling growth was recorded at increased NaC1 concentrations. Regression analysis results showed a significantly positive relationship (P〈0.01) between seed size and mean germination time, whereas a significantly negative relationship was recorded between seed size and germination index, root length, shoot length. Moreover, linear regression values apparently confirmed that increased seed size in each cultivar affected decreased germination index, root and shoot lengths with enhanced mean germination time. Thus, it was concluded that the use of small seeds could considerably reduce the production costs of chickpea in salt-affected soils.  相似文献   
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1 Results Free radical reactions have become increasingly important,as well as a very attractive tool,in organic synthesis within the last two decades,due to their powerful,selective,specific,and mild reaction abilities.Mn(OAc)3 mediated oxidative free radical reactions have been extensively developed in the last twenty years[1,6].Numerous regio-,chemo-,and stereoselective synthetic methods have been developed in both inter-and intramolecular reactions,and have detailed the progress of Mn(OAc)3 mediated oxidative free radical reactions. The selective oxidation of enones led to α′-acetoxy-enones by Mn(OAc)3 oxidation.In general,Mn(OAc)3 oxidations are characterized by higher α′-regioselectivity and chemical yields,and milder reaction conditions,in turn tolerating many sensitive functional groups.The use of Mn(OAc)3 in combination with other carboxylic acids or manganese(Ⅱ) carboxylates extends this methodology to the preparation of a variety of α′-acyloxyenones that are otherwise inaccessible in a one-step procedure.We developed a general method for the synthesis of biaryls starting from arylhydrazines and aromatic solvents in the presence of Mn(OAc)3.We showed for the first time that Mn(OAc)3 is a versatile reagent for the generation of aryl radicals from arylhydrazines.In a subsequent work,we extended this method for the synthesis of heterobiaryls,which was able to be achieved in thepresence of heteroaromatic compounds such as furan and thiophene. Another biaryl coupling reaction starting with arylboronic acids,mediated by Mn(OAc)3,was developed.The treatment of arylboronic acids with Mn(OAc)3 in benzene at reflux temperature afforded the corresponding biphenyl in high yields[7].  相似文献   
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Disorganization of the neurofilament network is a prominent feature of several neurodegenerative disorders including amyotrophic lateral sclerosis (ALS), infantile spinal muscular atrophy and axonal Charcot-Marie-Tooth disease. Giant axonal neuropathy (GAN, MIM 256850), a severe, autosomal recessive sensorimotor neuropathy affecting both the peripheral nerves and the central nervous system, is characterized by neurofilament accumulation, leading to segmental distension of the axons. GAN corresponds to a generalized disorganization of the cytoskeletal intermediate filaments (IFs), to which neurofilaments belong, as abnormal aggregation of multiple tissue-specific IFs has been reported: vimentin in endothelial cells, Schwann cells and cultured skin fibroblasts, and glial fibrillary acidic protein (GFAP) in astrocytes. Keratin IFs also seem to be alterated, as most patients present characteristic curly or kinky hairs. We report here identification of the gene GAN, which encodes a novel, ubiquitously expressed protein we have named gigaxonin. We found one frameshift, four nonsense and nine missense mutations in GAN of GAN patients. Gigaxonin is composed of an amino-terminal BTB (for Broad-Complex, Tramtrack and Bric a brac) domain followed by a six kelch repeats, which are predicted to adopt a beta-propeller shape. Distantly related proteins sharing a similar domain organization have various functions associated with the cytoskeleton, predicting that gigaxonin is a novel and distinct cytoskeletal protein that may represent a general pathological target for other neurodegenerative disorders with alterations in the neurofilament network.  相似文献   
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