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MultiTaper Method-Singular Value Decomposition (MTM-SVD): variabilidad espacio-frecuencia de las fluctuaciones del nivel del mar en el Pacífico suroriental MultiTaper Method-Singular Value Decomposition (MTM-SVD): spatial-frequency variability of the sea level in the southeastern Pacific  [cached]
Marco Correa-Ramirez,Samuel Hormazabal
Latin american journal of aquatic research , 2012,
Abstract: Se utilizan dieciocho anos de datos satelitales de nivel del mar y esfuerzo del viento, en la región del Pacifico suroriental, para mostrar las cualidades del Multitaper Method - Singular Value Decomposition (MTM-SVD) como método de análisis de múltiples series de tiempo distribuidas en extensas áreas del océano. Se realiza una exhaustiva revisión del MTM-SVD, propuesto inicialmente por Mann & Park (1999), y se implementan los algoritmos computacionales en MATLAB, para aprovechar las capacidades de despliegue gráfico de los resultados y facilitar su interpretación y análisis. El MTM-SVD permitió obtener una visión general de las principales frecuencias de variabilidad del nivel del mar, determinar la fracción de la varianza explicada para cada una de estas frecuencias en las distintas regiones de la zona de estudio y determinar sus patrones de oscilación, tanto estacionarios como de propagación. Dentro de las principales frecuencias de variabilidad se encuentra que la senal anual e interanual domina en forma significativa gran parte del registro del nivel del mar en el Pacifico suroriental. La senal anual está asociada a las fluctuaciones del esfuerzo del viento y a la propagación de ondas de Rossby. La senal interanual se encuentra fuertemente asociada a las fluctuaciones de El Ni o y la Oscilación del Sur, que se extiende en la región mediante perturbaciones generadas en la costa, que posteriormente viajan hacia el oeste a una velocidad cercana a la velocidad teórica de propagación del primer modo baroclino de una onda de Rossby. Eighteen years of satellite data on sea level and wind stress in the southeastern Pacific region, were used to show the capabilities of Multitaper Method - Singular Value Decomposition (MTM-SVD) as a valuable method to analyze multiple time series distributed over a large area on the ocean. Here we performed a comprehensive review of the MTM-SVD method,that was first proposed by Mann & Park (1999), and also we done an implementation of the MTM-SVD algorithms in MATLAB (MAtrix LABoratory), in order to take advantage of the graphical capabilities that brings this computational language and make easier the result interpretation. The MTM-SVD allowed to obtain a regional view of the main frequencies of sea level variability, and showed the explained variance along the study area for each frequency. Besides, the method also shown the spatial oscillation patterns on each frequency, both stationary or propagation patterns. A significant annual and interannual variability appear dominate much of the sea level fluctuations in the south
The Use of MTM-SVD Technique to Explore the Joint Spatiotemporal Modes of Wind and Sea Surface Variability in the North Indian Ocean during 1993–2005  [PDF]
Thaned Rojsiraphisal,Balaji Rajagopalan,Lakshmi Kantha
International Journal of Oceanography , 2009, DOI: 10.1155/2009/214828
Abstract: Sea surface height (SSH) and sea surface temperature (SST) in the North Indian Ocean are affected predominantly by the seasonally reversing monsoons and in turn feed back on monsoon variability. In this study, a set of data generated from a data-assimilative ocean model is used to examine coherent spatiotemporal modes of variability of winds and surface parameters using a frequency domain technique, Multiple Taper Method with Singular Value Decomposition (MTM-SVD). The analysis shows significant variability at annual and semiannual frequencies in these fields individually and jointly. The joint variability of winds and SSH is significant at interannual (2-3 years) timescale related to the ENSO mode—with a “/dipole/” like spatial pattern. Joint variability with SST showed similar but somewhat weaker behavior. Winds appear to be the driver of variability in both SSH and SST at these frequency bands. This offers prospects for long-lead projections of the North Indian Ocean climate.
MTM-SVD方法在印度洋海表温度与华南降水耦合特征分析中的应用  [PDF]
海洋通报 , 2013, DOI: 10.11840/j.issn.1001-6392.2013.02.003
Abstract: MTM-SVD方法是一种将谱分析的多锥度方法(MTM)和变量场分解的奇异值分解(SVD)结合为一体的多变量频域分解方法。介绍了MTM-SVD方法的主要原理和功能,并将MTM-SVD方法用于印度洋海表温度与华南地区降水量的时-空耦合特征的分析中,给出了华南降水和印度洋海表温度场的LFV谱的结果,利用信号的空间和时间重建技术,分析了两变量场的时-空耦合的年代际尺度的演变特征。
基于MTM-SVD方法的西南地区降水季节内振荡特征分析  [PDF]
高原气象 , 2015, DOI: 10.7522/j.issn.1000-0534.2013.00156
Abstract: 利用19812010年中国西南地区气象站点逐日降水资料以及NCEP/NCAR逐日再分析资料,使用MTM-SVD方法分析了西南地区降水的季节内振荡特征,结果表明:西南地区降水存在显著的14.4候(70天左右)振荡周期,该季节内振荡在1985年前后最强,在整个研究时段内夏季更明显.典型循环重建表明,西南地区降水的季节内振荡整体上有一个从南向北的推进过程,对OLR的分析表明,南海—西太平洋地区和孟加拉湾地区是影响西南地区降水的两个关键区.在季节内振荡尺度上影响西南地区降水的OLR异常信号首先出现在爪哇岛附近,逐渐向东传播到马鲁古群岛地区,然后北跳传播到北半球的南海—西太平洋地区和孟加拉湾地区,最后两者先后向北推进影响西南地区降水.
基于MTM-SVD方法的黄河流域夏季降水年际变化及其主要影响因子分析  [PDF]
王春学 WANG Chunxue,李栋梁 LI Dongliang
大气科学 , 2012, DOI: 10.3878/j.issn.1006-9895.2011.11126
Abstract: 应用中国气象台站积雪日数资料和NCEP/NCAR再分析资料以及多锥度—奇异值分解方法(MTM-SVD),分析了近50年来黄河流域夏季降水的时空变化及其影响因子.发现黄河流域夏季降水存在显著的2~3年周期.在准3年周期上黄河流域夏季降水对前冬青藏高原东部积雪日数有很好的响应,当前冬高原积雪日数以正(负)异常为主时,接下来的夏季黄河流域降水偏少(多).这种响应存在年代际变化,在1983年之前最为明显,1983~1993年是个调整时期,1993年以后又开始明显.在准2年周期上黄河流域夏季降水对前冬西太平洋暖池SST有很好的响应,当前冬西太平洋暖池SST偏高(低)时,接下来的夏季黄河流域降水表现为东多(少)西少(多)型.这一响应同样存在年代际变化.前冬高原积雪和西太平洋暖池SST是影响黄河流域夏季降水的重要因子.
The Extraordinary SVD  [PDF]
Carla D. Martin,Mason A. Porter
Physics , 2011,
Abstract: The singular value decomposition (SVD) is a popular matrix factorization that has been used widely in applications ever since an efficient algorithm for its computation was developed in the 1970s. In recent years, the SVD has become even more prominent due to a surge in applications and increased computational memory and speed. To illustrate the vitality of the SVD in data analysis, we highlight three of its lesser-known yet fascinating applications: the SVD can be used to characterize political positions of Congressmen, measure the growth rate of crystals in igneous rock, and examine entanglement in quantum computation. We also discuss higher-dimensional generalizations of the SVD, which have become increasingly crucial with the newfound wealth of multidimensional data and have launched new research initiatives in both theoretical and applied mathematics. With its bountiful theory and applications, the SVD is truly extraordinary.
Patient-perceived value of Medication Therapy Management (MTM) services: a series of focus groups  [PDF]
Heidi Schultz, PharmD,Sarah M. Westberg, PharmD, BCPS,Djenane Ramalho de Oliveira, PhD,Amanda Brummel, PharmD
INNOVATIONS in Pharmacy , 2012,
Abstract: Objective: To determine the patient-perceived value of MTM services and non-financial barriers preventing patients with insurance coverage from receiving MTM services. Design: Focus groups. Setting: Fairview Pharmacy Services, Minneapolis, MN.Participants: Three focus groups, each with five to nine participants, consisting of different participant populations: (i) patients who paid out-of-pocket to receive MTM services; (ii) insurance beneficiaries, under which MTM is a covered benefit and participants may have received incentives for receiving MTM services; (iii) patients with an insurance plan which covers MTM services who were recruited to receive MTM services but declined. Intervention: MTM services. Main Outcome Measure: Patient-perceived value of MTM services and non-financial barriers. Results: Seven themes were identified relating to the patient-perceived value of MTM services: collaboration of the health care team, MTM pharmacist as a supporter/advocate/confidant, MTM pharmacist as a resource for questions and education, accessibility to the MTM pharmacist, financial incentives for participation in MTM services, MTM pharmacy as a specialty field, and the MTM pharmacist as a coordinator. Three themes were identified regarding patient-perceived non-financial barriers to receiving MTM services, including: availability of the MTM pharmacist, patient/physician lack of knowledge of MTM services, patient’s belief that MTM services are not needed. Conclusion: MTM is a service which patients identify as valuable. Patients are able to identify non-financial barriers that may prevent some patients from receiving MTM services. This study provides preliminary evidence of both the value and barriers perceived by patients.
基于MTM和灰色关联度的混合噪声自适应滤波算法  [PDF]
河南大学学报(自然科学版) , 2011,
Abstract: 利用MTM滤波算法和灰色关联度的特点,提出一种基于MTM滤波算法和灰色关联度相结合的混合噪声图像的自适应滤波算法.算法选取加窗混合噪声图像的MTM值,采用灰色
Caenorhabditis elegans Myotubularin MTM-1 Negatively Regulates the Engulfment of Apoptotic Cells  [PDF]
Wei Zou equal contributor,Qun Lu equal contributor,Dongfeng Zhao,Weida Li,James Mapes,Yuting Xie,Xiaochen Wang
PLOS Genetics , 2009, DOI: 10.1371/journal.pgen.1000679
Abstract: During programmed cell death, apoptotic cells are recognized and rapidly engulfed by phagocytes. Although a number of genes have been identified that promote cell corpse engulfment, it is not well understood how phagocytosis of apoptotic cells is negatively regulated. Here we have identified Caenorhabditis elegans myotubularin MTM-1 as a negative regulator of cell corpse engulfment. Myotubularins (MTMs) constitute a large, highly conserved family of lipid phosphatases. MTM gene mutations are associated with various human diseases, but the cellular functions of MTM proteins are not clearly defined. We found that inactivation of MTM-1 caused significant reduction in cell corpses in strong loss-of-function mutants of ced-1, ced-6, ced-7, and ced-2, but not in animals deficient in the ced-5, ced-12, or ced-10 genes. In contrast, overexpression of MTM-1 resulted in accumulation of cell corpses. This effect is dependent on the lipid phosphatase activity of MTM-1. We show that loss of mtm-1 function accelerates the clearance of cell corpses by promoting their internalization. Importantly, the reduction of cell corpses caused by mtm-1 RNAi not only requires the activities of CED-5, CED-12, and CED-10, but also needs the functions of the phosphatidylinositol 3-kinases (PI3Ks) VPS-34 and PIKI-1. We found that MTM-1 localizes to the plasma membrane in several known engulfing cell types and may modulate the level of phosphatidylinositol 3-phosphate (PtdIns(3)P) in vivo. We propose that MTM-1 negatively regulates cell corpse engulfment through the CED-5/CED-12/CED-10 module by dephosphorylating PtdIns(3)P on the plasma membrane.
酿酒酵母全基因组范围内筛选mtm1基因的抑制基因  [PDF]
生物化学与生物物理进展 , 2010,
Abstract: mtm1基因对于维持锰超氧化物歧化酶的活性和线粒体正常功能十分重要,mtm1基因的缺失会严重影响酵母锰超氧化物歧化酶活性,并损伤线粒体功能,因此在非发酵培养基上不能生长.利用mtm1基因缺失的突变体在非发酵培养基上的生长缺陷,转入酵母基因组文库筛选mtm1抑制基因,发现mtm1基因缺失造成的损伤一旦形成不可逆转,重新引入mtm1基因也无法挽救,直接筛选无法得到抑制基因.为了避免mtm1缺失造成的不可逆损伤,在野生型酵母中先转入带有mtm1基因的质粒,再敲除染色体上的mtm1基因,随后转入基因组文库,再利用药物5-氟乳清酸(5-foa)迫使细胞丢失表达mtm1基因的外源质粒,再筛选能在非发酵培养基上生长的转化子,通过这种方法筛选发现,por2等5个基因的过表达可以挽救mtm1基因缺失造成的非发酵培养基上的生长缺陷,为深入了解mtm1基因的功能提供了线索,对筛选其他造成不可逆损伤的突变基因的抑制基因提供了一条可行的研究思路.
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