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Application of an Error Statistics Estimation Method to the PSAS Forecast Error Covariance Model

Advances in Atmospheric Sciences 2006年第1期23卷 33-44页

作者： Runhua YANG Jing GUO lars peter riishфjgaard Science Systems and Applications Inc. Lanham USA Science Applications International Corporation Beltsville USA Joint Center for Earth Systems Technology/UMBC Baltimore USA Global Modeling and Assimilation Office NASA Goddard Space Flight Center Greenbelt USA

In atmospheric data assimilation systems, the forecast error covariance model is an important component. However, the paralneters required by a forecast error covariance model are difficult to obtain due to the absence of the truth. This study applies an error statistics estimation method to the Pfiysical-space Statistical Analysis System （PSAS） height-wind forecast error covariance model. This method consists of two components： the first component computes the error statistics by using the National Meteorological Center （NMC） method, which is a lagged-forecast difference approach, within the framework of the PSAS height-wind forecast error covariance model; the second obtains a calibration formula to rescale the error standard deviations provided by the NMC method. The calibration is against the error statistics estimated by using a maximum-likelihood estimation （MLE） with rawindsonde height observed-minus-forecast residuals. A complete set of formulas for estimating the error statistics and for the calibration is applied to a one-month-long dataset generated by a general circulation model of the Global Model and Assimilation Office （GMAO）, NASA. There is a clear constant relationship between the error statistics estimates of the NMC-method and MLE. The final product provides a full set of 6-hour error statistics required by the PSAS height-wind forecast error covariance model over the globe. The features of these error statistics are examined and discussed.

关键词： forecast error statistics estimation data analysis forecast error covariance model

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Surface integral analogy approaches for predicting noise from 3D high-lift low-noise wings

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Acta Mechanica Sinica 2014年第3期30卷 326-338页

作者： Hua-Dong Yao lars Davidson lars-Erik Eriksson Shia-Hui Peng Olof Grundestam peter E.Eliasson Department of Applied Mechanics Chalmers University of Technology Department of Aeronautics and Systems Technology Swedish Defence Research Agency (FOI)

Three surface integral approaches of the acoustic analogies are studied to predict the noise from three concep- tual configurations of three-dimensional high-lift low-noise wings. The approaches refer to the Kirchhoff method, the Ffowcs Williams and Hawkings （FW-H） method of the permeable integral surface and the Curle method that is known as a special case of the FW-H method. The first two approaches are used to compute the noise generated by the core flow region where the energetic structures exist. The last approach is adopted to predict the noise specially from the pressure perturbation on the wall. A new way to con- struct the integral surface that encloses the core region is proposed for the first two methods. Considering the local properties of the flow around the complex object-the actual wing with high-lift devices-the integral surface based on the vorticity is constructed to follow the flow structures. The surface location is discussed for the Kirchhoff method and the FW-H method because a common surface is used for them. The noise from the core flow region is studied on the basis of the dependent integral quantities, which are indicated by the Kirchhoff formulation and by the FW-H formulation. The role of each wall component on noise contribution is analyzed using the Curle formulation. Effects of the volume integral terms of Lighthill＇s stress tensors on the noise pre-diction are then evaluated by comparing the results of the Curle method with the other two methods.

关键词： Aero-acoustics High-lift facilities Surface integral approaches of acoustic analogy

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Role of contrast enhanced ultrasonography in the assessment of hepatic metastases:A review

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World Journal of Hepatology 2010年第1期2卷 8-15页

作者： lars peter Skovgaard larsen Department of Radiology Aarhus University Hospital

Contrast enhanced ultrasonography(CEUS) has improved both the detection and characterization of foca liver *** is now possible to evaluate in real time the perfusion of focal liver lesions in the arterial,porta and late contrast phases,and thus to characterize focal liver lesions with high diagnostic *** a result,CEUS has taken a central diagnostic role in the evaluation of focal liver lesions that are indeterminate upon computed tomography(CT) and magnetic resonance *** combined use of second generation contrast agents and low mechanica index techniques is essential for the detection of liver metastases,and it now allows the examination of the entire liver in both the portal and late phases. Several studies have shown that using CEUS instead of conventional ultrasonography without contrast agents significantly improves sensitivity in detection of liver ***,the detection rate with CEUS seems to be similar to that of *** review describes the clinical role of CEUS in detecting liver metastases,including details about examination techniques,features of metastases observed with CEUS,and clinical results and guidelines.

关键词： Ultrasound Contrast-enhanced ultrasound Liver neoplasms Metastasis Ultrasound contrast agent

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Experimental human pain models in gastro-esophageal reflux disease and unexplained chest pain

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World Journal of Gastroenterology 2006年第18期12卷 2805-2817页

作者： Asbjφrn Mohr Drewes lars Arendt-Nielsen peter Funch-Jensen Hans Gregersen Center for Visceral Biomechanics and Pain Department of GastroenterologyAalborg Hospitaland Center for Sensory-Motor InteractionsDepartment of Health Science and TechnologyAalborg UniversityDenmark Department of Surgical Gastroenterology L Aarhus HospitalDenmark

Methods related to experimental human pain research aim at activating different nociceptors, evoke pain from different organs and activate specific pathways and mechanisms. The different possibilities for using mechanical, electrical, thermal and chemical methods in visceral pain research are discussed with emphasis of combinations (e.g., the multimodal approach). The methods have been used widely in assessment of pain mechanisms in the esophagus and have contributed to our understanding of the symptoms reported in these patients. Hence abnormal activation and plastic changes of central pain pathways seem to play a major role in the symptoms in some patients with gastro-esophageal reflux disease and in patients with functional chest pain of esophageal origin. These findings may lead to an alternative approach for treatment in patients that does not respond to conventional medical or surgical therapy.

关键词： Pain Gut Experimental Chest pain Esophagitis

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Gene-environment interaction and male reproductive function

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Asian Journal of Andrology 2010年第3期12卷 298-307,I0007页

作者： Jonatan Axelsson Jens peter Bonde Yvonne L. Giwercman lars Rylander Aleksander Giwercman Reproductive Medicine Centre Skane University Hospital Malmo 20502 Sweden Division of Occupational and Environmental Medicine Lund University Lund 22185 Sweden Department of Occupational Medicine Copenhagen University Bispebjerg Hospital Copenhagen NV2400 Denmark Department of Clinical Sctences Malmo Lund University Malmo 20502 Sweden

As genetic factors can hardly explain the changes taking place during short time spans, environmental and lifestyle-related factors have been suggested as the causes of time-related deterioration of male reproductive function. However, considering the strong heterogeneity of male fecundity between and within populations, genetic variants might be important determinants of the individual susceptibility to the adverse effects of environment or lifestyle. Although the possible mechanisms of such interplay in relation to the reproductive system are largely unknown, some recent studies have indicated that specific genotypes may confer a larger risk of male reproductive disorders following certain exposures. This paper presents a critical review of animal and human evidence on how genes may modify environmental effects on male reproductive function. Some examples have been found that support this mechanism, but the number of studies is still limited. This type of interaction studies may improve our understanding of normal physiology and help us to identify the risk factors to male reproductive malfunction. We also shortly discuss other aspects of gene-environment interaction specifically associated with the issue of reproduction, namely environmental and lifestyle factors as the cause of sperm DNA damage. It remains to be investigated to what extent such genetic changes, by natural conception or through the use of assisted reproductive techniques, are transmitted to the next generation, thereby causing increased morbidity in the offspring.

关键词： endocrine disruption gene-environment interaction persistent organic pollutants semen quality testicular cancer

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Pharmacological interventions for improved colonic anastomotic healing:A meta-analysis

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World Journal of Gastroenterology 2014年第35期20卷 12637-12648页

作者： Mari Nanna φines peter-Martin Krarup lars Nannestad Jorgensen Magnus Sven Agren Digestive Disease Center Bispebjerg HospitalUniversity of Copenhagen Copenhagen Wound Healing Center Bispebjerg HospitalUniversity of Copenhagen Department of Clinical Medicine Faculty of Health and Medical SciencesUniversity of Copenhagen

AIM: To identify pharmaceuticals for the prophylaxis of anastomotic leakage (AL), we systematically reviewed studies on anastomosis repair after colorectal surgery.

关键词： Anastomotic healing Colorectal surgery Experimental Breaking strength Bursting pressure Collagen Meta-analysis

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Effect of atomic structure on preferential oxidation of alloys:amorphous versus crystalline Cu-Zr

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Journal of Materials Science & Technology 2020年第5期40卷 128-134页

作者： Yifei Xu lars P.H.Jeurgens peter Schützendübe Shengli Zhu Yuan Huang Yongchang Liu Zumin Wang State Key Lab of Hydraulic Engineering Simulation and Safety School of Materials Science and EngineeringTianjin UniversityTianjin 300350China Swiss Federal Laboratories for Materials Science and Technology Laboratory for Joining Technologies and CorrosionUeberlandstrasse 1298600 DuebendorfSwitzerland Max Planck Institute for Intelligent Systems Heisenbergstrasse 3D-70569 StuttgartGermany

The effect of structural order in the parent alloy substrate on the oxidation kinetics and oxide phase evolution was investigated for the thermal oxidation of amorphous Cu33at.%Zr67at.%and crystalline CuZr2 alloys of identical compositions in the temperature range of 200–250?*** was found that,besides the strong preferential oxidation of Zr in both alloys,the lack of structural order in the amorphous Cu33at.%Zr67at.%alloy results in much slower oxidation kinetics,as well as in distinctly different microstructures of the oxide overgrowth and its Zr-depletion zone in the wake of the ZrO2 overlayer growth *** experimental findings can be rationalized on the basis of the strikingly different atomic mobilities of Cu,Zr and dissolved O in the amorphous and crystalline alloys,which also results in different nucleation barriers for crystalline oxide *** thus obtained knowledge on the underlying oxidation mechanisms provides new and profound insights into the surface engineering of metallic alloys.

关键词： Oxidation Atomic structure Amorphous alloys Cu-Zr HRTEM

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Value of three-dimensional reconstructions in pancreatic carcinoma using multidetector CT:Initial results

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World Journal of Gastroenterology 2009年第46期15卷 5827-5832页

作者： Miriam Klauβ Max Schbinger Ivo Wolf Jens Werner Hans-peter Meinzer Hans-Ulrich Kauczor lars Grenacher Department of Diagnostic and Interventional Radiology University of Heidelberg Department of Medical and Biological Informatics German Cancer Research Center(DKFZ) Surgical Clinic University of Heidelberg

AIM:To evaluate the use of three-dimensional imaging of pancreatic carcinoma using multidetector computed tomography(CT)in a prospective ***:Ten patients with suspected pancreatic tumors were examined prospectively using multidetec-tor CT(Somatom Sensation 16,Siemens,Erlangen,Germany).The images were evaluated for the pres-ence of a pancreatic carcinoma and invasion of the peripancreatic vessels and surrounding *** the isotropic CT data sets,a three-dimensional image was created with automatic vascular analysis and semi-automatic segmentation of the organs and pancreatic tumor by a *** CT examinations and the three-dimensional images were presented to the sur-geon directly before and during the patient's operation using the Medical Imaging Interaction Toolkit-based software "ReLiver".Immediately after surgery,the value of the two images was judged by the *** operation and the histological results served as the gold ***:Nine patients had a pancreatic carcinoma(all pT3),and one patient had a serous *** tumor inf iltrated the superior mesenteric *** inf iltration was correctly *** carcinomas were *** comparison to the CT image with axial and coronal reconstructions,the three-dimensional image was judged by the surgeons as better for operation planning and consistently described as ***:A 3D-image of the pancreas repre-sents an invaluable aid to the ***,the 3D-software must be further developed in order to be integrated into daily clinical routine.

关键词： Pancreatic carcinoma 3D-reconstruction Multidetector computed tomography Pancreatic carcinomainvasion Segmentation

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predictors for failure of stent treatment for benign esophageal perforations- a single center 10-year experience

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World Journal of Gastroenterology 2014年第30期20卷 10613-10619页

作者： Saga Persson peter Elbe Ioannis Rouvelas Mats Lindblad Koshi Kumagai lars Lundell Magnus Nilsson Jon A Tsai Division of Surgery Karolinska Institutet and GastroCentrumDepartment of Clinical SciencesIntervention and TechnologyKarolinska University Hospital Huddinge141 86 StockholmSweden

AIM: To investigate possible predictors for failed self-expandable metallic stent (SEMS) therapy in consecutive patients with benign esophageal perforation-rupture (EPR).

关键词： Esophageal perforation Stents Esophagectomy Morbidity Mortality Mediastinitis

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In Situ Etching for Total Control Over Axial and Radial Nanowire Growth

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Nano Research 2010年第4期3卷 264-270页

作者： Magnus T.Borgström Jesper Wallentin Johanna Trägårdh peter Ramvall Martin Ek LReine Wallenberg lars Samuelson Knut Deppert Solid State Physics Lund UniversityBox 118S-22100LundSweden Polymer&Materials Chemistry/nCHREM Lund UniversityS-22100 LundSweden H.H.Wills Physics Laboratory University of BristolTyndall AvenueBristol BS81TLUnited Kingdom

We report a method using in situ etching to decouple the axial from the radial nanowire growth pathway,independent of other growth *** a wide range of growth parameters can be explored to improve the nanowire properties without concern of tapering or excess structural defects formed during radial *** demonstrate the method using etching by HCl during InP nanowire *** improved crystal quality of etched nanowires is indicated by strongly enhanced photoluminescence as compared to reference nanowires obtained without etching.

关键词： MOVPE nanowire growth in situ etching photoluminescence

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