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排序方式: 共有105条查询结果,搜索用时 31 毫秒
81.
Christian Hotz‐Behofsits Florian Huber Thomas Otto Zörner 《Journal of forecasting》2018,37(6):627-640
In this paper we forecast daily returns of crypto‐currencies using a wide variety of different econometric models. To capture salient features commonly observed in financial time series like rapid changes in the conditional variance, non‐normality of the measurement errors and sharply increasing trends, we develop a time‐varying parameter VAR with t‐distributed measurement errors and stochastic volatility. To control for overparametrization, we rely on the Bayesian literature on shrinkage priors, which enables us to shrink coefficients associated with irrelevant predictors and/or perform model specification in a flexible manner. Using around one year of daily data, we perform a real‐time forecasting exercise and investigate whether any of the proposed models is able to outperform the naive random walk benchmark. To assess the economic relevance of the forecasting gains produced by the proposed models we, moreover, run a simple trading exercise. 相似文献
82.
Nogo-A is a myelin-associated neurite outgrowth inhibitor and an antigen for monoclonal antibody IN-1 总被引:97,自引:0,他引:97
Chen MS Huber AB van der Haar ME Frank M Schnell L Spillmann AA Christ F Schwab ME 《Nature》2000,403(6768):434-439
The capacity of the adult brain and spinal cord to repair lesions by axonal regeneration or compensatory fibre growth is extremely limited. A monoclonal antibody (IN-1) raised against NI-220/250, a myelin protein that is a potent inhibitor of neurite growth, promoted axonal regeneration and compensatory plasticity following lesions of the central nervous system (CNS) in adult rats. Here we report the cloning of nogo A, the rat complementary DNA encoding NI-220/250. The nogo gene encodes at least three major protein products (Nogo-A, -B and -C). Recombinant Nogo-A is recognized by monoclonal antibody IN-1, and it inhibits neurite outgrowth from dorsal root ganglia and spreading of 3T3 fibroblasts in an IN-1-sensitive manner. Antibodies against Nogo-A stain CNS myelin and oligodendrocytes and allow dorsal root ganglion neurites to grow on CNS myelin and into optic nerve explants. These data show that Nogo-A is a potent inhibitor of neurite growth and an IN-1 antigen produced by oligodendrocytes, and may allow the generation of new reagents to enhance CNS regeneration and plasticity. 相似文献
83.
Serguei V. Triapitsyn Chrysalyn Dominguez John T. Huber George Japoshvili John M. Heraty 《Journal of Natural History》2020,54(9-12):585-596
ABSTRACT Based on morphological and molecular evidence, the European fairyfly Herulia sundholmi Hedqvist syn. n. (Hymenoptera: Mymaridae) is removed from previous synonymy with the Nearctic Macrocamptoptera metotarsa (Girault), and synonymised with the Palaearctic M. grangeri Soyka, which is newly recorded from Georgia, Slovakia and Spain. Macrocamptoptera bulagarica (Donev) syn. n., known from Bulgaria and Italy, is also synonymised with M. grangeri. An updated key to females of the three currently recognised species of the rarely collected genus Macrocamptoptera Girault is given. 相似文献
84.
85.
Structure of cytochrome c nitrite reductase. 总被引:1,自引:0,他引:1
O Einsle A Messerschmidt P Stach G P Bourenkov H D Bartunik R Huber P M Kroneck 《Nature》1999,400(6743):476-480
The enzyme cytochrome c nitrite reductase catalyses the six-electron reduction of nitrite to ammonia as one of the key steps in the biological nitrogen cycle, where it participates in the anaerobic energy metabolism of dissimilatory nitrate ammonification. Here we report on the crystal structure of this enzyme from the microorganism Sulfurospirillum deleyianum, which we solved by multiwavelength anomalous dispersion methods. We propose a reaction scheme for the transformation of nitrite based on structural and spectroscopic information. Cytochrome c nitrite reductase is a functional dimer, with 10 close-packed haem groups of type c and an unusual lysine-coordinated high-spin haem at the active site. By comparing the haem arrangement of this nitrite reductase with that of other multihaem cytochromes, we have been able to identify a family of proteins in which the orientation of haem groups is conserved whereas structure and function are not. 相似文献
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88.
W Zhou EA Otto A Cluckey R Airik TW Hurd M Chaki K Diaz FP Lach GR Bennett HY Gee AK Ghosh S Natarajan S Thongthip U Veturi SJ Allen S Janssen G Ramaswami J Dixon F Burkhalter M Spoendlin H Moch MJ Mihatsch J Verine R Reade H Soliman M Godin D Kiss G Monga G Mazzucco K Amann F Artunc RC Newland T Wiech S Zschiedrich TB Huber A Friedl GG Slaats JA Joles R Goldschmeding J Washburn RH Giles S Levy A Smogorzewska F Hildebrandt 《Nature genetics》2012,44(8):910-915
Chronic kidney disease (CKD) represents a major health burden. Its central feature of renal fibrosis is not well understood. By exome sequencing, we identified mutations in FAN1 as a cause of karyomegalic interstitial nephritis (KIN), a disorder that serves as a model for renal fibrosis. Renal histology in KIN is indistinguishable from that of nephronophthisis, except for the presence of karyomegaly. The FAN1 protein has nuclease activity and acts in DNA interstrand cross-link (ICL) repair within the Fanconi anemia DNA damage response (DDR) pathway. We show that cells from individuals with FAN1 mutations have sensitivity to the ICL-inducing agent mitomycin C but do not exhibit chromosome breakage or cell cycle arrest after diepoxybutane treatment, unlike cells from individuals with Fanconi anemia. We complemented ICL sensitivity with wild-type FAN1 but not with cDNA having mutations found in individuals with KIN. Depletion of fan1 in zebrafish caused increased DDR, apoptosis and kidney cysts. Our findings implicate susceptibility to environmental genotoxins and inadequate DNA repair as novel mechanisms contributing to renal fibrosis and CKD. 相似文献
89.
In this paper we aim to improve existing empirical exchange rate models by accounting for uncertainty with respect to the underlying structural representation. Within a flexible Bayesian framework, our modeling approach assumes that different regimes are characterized by commonly used structural exchange rate models, with transitions across regimes being driven by a Markov process. We assume a time-varying transition probability matrix with transition probabilities depending on a measure of the monetary policy stance of the central bank at home and in the USA. We apply this model to a set of eight exchange rates against the US dollar. In a forecasting exercise, we show that model evidence varies over time, and a model approach that takes this empirical evidence seriously yields more accurate density forecasts for most currency pairs considered. 相似文献
90.
Summary A method for the individual rearing of the codling mothLaspeyresia pomonella is described. The method allows the collection of exactly dated eggs and the rearing of a large number of larvae in a small space. By using the second medium described, it is possible to watch all developmental stages at any time without disturbing them. The average larval survival rate is 70–80%. 相似文献