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排序方式: 共有108条查询结果,搜索用时 0 毫秒
81.
Alberto Cabrero Gonzalo Camba‐Mendez Astrid Hirsch Fernando Nieto 《Journal of forecasting》2009,28(3):194-217
The main focus of this paper is to model the daily series of banknotes in circulation. The series of banknotes in circulation displays very marked seasonal patterns. To the best of our knowledge the empirical performance of two competing approaches to model seasonality in daily time series, namely the ARIMA‐based approach and the Structural Time Series approach, has never been put to the test. The application presented in this paper provides valid intuition on the merits of each approach. The forecasting performance of the models is also assessed in the context of their impact on the liquidity management of the Eurosystem. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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83.
Nathália Vieceli Fernando O. Dur?o Carlos Guimar?es Carlos A. Nogueira Manuel F. C. Pereira Fernanda Margarido 《矿物冶金与材料学报》2016,23(7):731-742
The number of published studies related to the optimization of lithium extraction from low-grade ores has increased as the demand for lithium has grown. However, no study related to the kinetics of the concentration stage of lithium-containing minerals by froth flotation has yet been reported. To establish a factorial design of batch flotation experiments, we conducted a set of kinetic tests to determine the most selective alternative collector, define a range of pulp pH values, and estimate a near-optimum flotation time. Both collectors (Aeromine 3000C and Armeen 12D) provided the required flotation selectivity, although this selectivity was lost in the case of pulp pH values outside the range between 2 and 4. Cumulative mineral recovery curves were used to adjust a classical kinetic model that was modified with a non-negative parameter representing a delay time. The computation of the near-optimum flotation time as the maximizer of a separation efficiency (SE) function must be performed with caution. We instead propose to define the near-optimum flotation time as the time interval required to achieve 95%–99% of the maximum value of the SE function. 相似文献
84.
Optimization of an innovative approach involving mechanical activation and acid digestion for the extraction of lithium from lepidolite
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Nathália Vieceli Carlos A. Nogueira Manuel F. C. Pereira Fernando O. Dur o Carlos Guimar es Fernanda Margarido 《矿物冶金与材料学报》2018,25(1):11-19
The recovery of lithium from hard rock minerals has received increased attention given the high demand for this element. Therefore, this study optimized an innovative process, which does not require a high-temperature calcination step, for lithium extraction from lepidolite. Mechanical activation and acid digestion were suggested as crucial process parameters, and experimental design and response-surface methodology were applied to model and optimize the proposed lithium extraction process. The promoting effect of amorphization and the formation of lithium sulfate hydrate on lithium extraction yield were assessed. Several factor combinations led to extraction yields that exceeded 90%, indicating that the proposed process is an effective approach for lithium recovery. 相似文献
85.
Baltazar Aguirre HERNANDEZ Martn Eduardo FRIAS-ARMENTA Fernando VERDUZCO 《系统科学与系统工程学报(英文版)》2012,21(3):372-382
A valuable number of works has been published about Hurwitz and Schur polynomials in order to known better their properties.For example it is known that the sets of Hurwitz and Schur polynomials are open and no convex sets.Besides,the set of monic Schur polynomials is contractible.Now we study this set using ideas from differential topology,and we prove that the space of Schur complex polynomials with positive leading coefficient,and the space of Hurwitz complex polynomials which leading coefficient having positive real part,have structure of trivial vector bundle,and each space of (Schur complex and real,Hurwitz complex) polynomials has a differential structure diffeomorphic to some known spaces. 相似文献
86.
A truncating mutation of HDAC2 in human cancers confers resistance to histone deacetylase inhibition 总被引:1,自引:0,他引:1
Ropero S Fraga MF Ballestar E Hamelin R Yamamoto H Boix-Chornet M Caballero R Alaminos M Setien F Paz MF Herranz M Palacios J Arango D Orntoft TF Aaltonen LA Schwartz S Esteller M 《Nature genetics》2006,38(5):566-569
Disruption of histone acetylation patterns is a common feature of cancer cells, but very little is known about its genetic basis. We have identified truncating mutations in one of the primary human histone deacetylases, HDAC2, in sporadic carcinomas with microsatellite instability and in tumors arising in individuals with hereditary nonpolyposis colorectal cancer syndrome. The presence of the HDAC2 frameshift mutation causes a loss of HDAC2 protein expression and enzymatic activity and renders these cells more resistant to the usual antiproliferative and proapoptotic effects of histone deacetylase inhibitors. As such drugs may serve as therapeutic agents for cancer, our findings support the use of HDAC2 mutational status in future pharmacogenetic treatment of these individuals. 相似文献
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88.
Gudmundsson J Sulem P Gudbjartsson DF Jonasson JG Masson G He H Jonasdottir A Sigurdsson A Stacey SN Johannsdottir H Helgadottir HT Li W Nagy R Ringel MD Kloos RT de Visser MC Plantinga TS den Heijer M Aguillo E Panadero A Prats E Garcia-Castaño A De Juan A Rivera F Walters GB Bjarnason H Tryggvadottir L Eyjolfsson GI Bjornsdottir US Holm H Olafsson I Kristjansson K Kristvinsson H Magnusson OT Thorleifsson G Gulcher JR Kong A Kiemeney LA Jonsson T Hjartarson H Mayordomo JI Netea-Maier RT 《Nature genetics》2012,44(3):319-322
To search for sequence variants conferring risk of nonmedullary thyroid cancer, we focused our analysis on 22 SNPs with a P < 5 × 10(-8) in a genome-wide association study on levels of thyroid stimulating hormone (TSH) in 27,758 Icelanders. Of those, rs965513 has previously been shown to associate with thyroid cancer. The remaining 21 SNPs were genotyped in 561 Icelandic individuals with thyroid cancer (cases) and up to 40,013 controls. Variants suggestively associated with thyroid cancer (P < 0.05) were genotyped in an additional 595 non-Icelandic cases and 2,604 controls. After combining the results, three variants were shown to associate with thyroid cancer: rs966423 on 2q35 (OR = 1.34; P(combined) = 1.3 × 10(-9)), rs2439302 on 8p12 (OR = 1.36; P(combined) = 2.0 × 10(-9)) and rs116909374 on 14q13.3 (OR = 2.09; P(combined) = 4.6 × 10(-11)), a region previously reported to contain an uncorrelated variant conferring risk of thyroid cancer. A strong association (P = 9.1 × 10(-91)) was observed between rs2439302 on 8p12 and expression of NRG1, which encodes the signaling protein neuregulin 1, in blood. 相似文献
89.
Bradfield JP Taal HR Timpson NJ Scherag A Lecoeur C Warrington NM Hypponen E Holst C Valcarcel B Thiering E Salem RM Schumacher FR Cousminer DL Sleiman PM Zhao J Berkowitz RI Vimaleswaran KS Jarick I Pennell CE Evans DM St Pourcain B Berry DJ Mook-Kanamori DO Hofman A Rivadeneira F Uitterlinden AG van Duijn CM van der Valk RJ de Jongste JC Postma DS Boomsma DI Gauderman WJ Hassanein MT Lindgren CM Mägi R Boreham CA Neville CE Moreno LA Elliott P Pouta A Hartikainen AL Li M Raitakari O 《Nature genetics》2012,44(5):526-531
Multiple genetic variants have been associated with adult obesity and a few with severe obesity in childhood; however, less progress has been made in establishing genetic influences on common early-onset obesity. We performed a North American, Australian and European collaborative meta-analysis of 14 studies consisting of 5,530 cases (≥95th percentile of body mass index (BMI)) and 8,318 controls (<50th percentile of BMI) of European ancestry. Taking forward the eight newly discovered signals yielding association with P < 5 × 10(-6) in nine independent data sets (2,818 cases and 4,083 controls), we observed two loci that yielded genome-wide significant combined P values near OLFM4 at 13q14 (rs9568856; P = 1.82 × 10(-9); odds ratio (OR) = 1.22) and within HOXB5 at 17q21 (rs9299; P = 3.54 × 10(-9); OR = 1.14). Both loci continued to show association when two extreme childhood obesity cohorts were included (2,214 cases and 2,674 controls). These two loci also yielded directionally consistent associations in a previous meta-analysis of adult BMI(1). 相似文献
90.
Freilinger T Anttila V de Vries B Malik R Kallela M Terwindt GM Pozo-Rosich P Winsvold B Nyholt DR van Oosterhout WP Artto V Todt U Hämäläinen E Fernández-Morales J Louter MA Kaunisto MA Schoenen J Raitakari O Lehtimäki T Vila-Pueyo M Göbel H Wichmann E Sintas C Uitterlinden AG Hofman A Rivadeneira F Heinze A Tronvik E van Duijn CM Kaprio J Cormand B Wessman M Frants RR Meitinger T Müller-Myhsok B Zwart JA Färkkilä M Macaya A Ferrari MD Kubisch C Palotie A Dichgans M 《Nature genetics》2012,44(7):777-782
Migraine without aura is the most common form of migraine, characterized by recurrent disabling headache and associated autonomic symptoms. To identify common genetic variants associated with this migraine type, we analyzed genome-wide association data of 2,326 clinic-based German and Dutch individuals with migraine without aura and 4,580 population-matched controls. We selected SNPs from 12 loci with 2 or more SNPs associated with P values of <1 × 10(-5) for replication testing in 2,508 individuals with migraine without aura and 2,652 controls. SNPs at two of these loci showed convincing replication: at 1q22 (in MEF2D; replication P = 4.9 × 10(-4); combined P = 7.06 × 10(-11)) and at 3p24 (near TGFBR2; replication P = 1.0 × 10(-4); combined P = 1.17 × 10(-9)). In addition, SNPs at the PHACTR1 and ASTN2 loci showed suggestive evidence of replication (P = 0.01; combined P = 3.20 × 10(-8) and P = 0.02; combined P = 3.86 × 10(-8), respectively). We also replicated associations at two previously reported migraine loci in or near TRPM8 and LRP1. This study identifies the first susceptibility loci for migraine without aura, thereby expanding our knowledge of this debilitating neurological disorder. 相似文献