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XFEL data analysis for structural biology

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Frontiers of Electrical and Electronic Engineering in china 2016年第3期4卷 159-176页

作者： Haiguang Liu John c. H. Spence complex Systems Division Beiiin.q Computational Science Research Center Beijing 100193 China Physics Department Arizona State University Tempe AZ 85287 USA

X-ray Free Electron Lasers （XFELs） have advanced research in structure biology, by exploiting their ultra-short and bright X-ray pulses. The resulting ＂diffraction before destruction＂ experimental approach allows data collection to outrun radiation damage, a crucial factor that has often limited resolution in the structure determination of biological molecules. Since the first hard X-ray laser （the Linac coherent Light Source （LcLS） at SLAc） commenced operation in 2009, serial femtosecond crystallography （SFX） has rapidly matured into a method for the structural analysis of nano- and micro-crystals. At the same time, single particle structure determination by coherent diffractive imaging, with one particle （such as a virus） per shot, has been under intense development. In this review we describe these applications of X-ray lasers in structural biology, with a focus particularly on aspects of data analysis for the computational research community. We summarize the key problems in data analysis and model reconstruction, and provide perspectives on future research using computational methods.

关键词： X-my Free Electron Laser single particle scattering serial crystallography phase retrieval orientationrecovery

Experimental and Numerical Studies of the Wave-Induced Responses of a River-to-Sea Ship

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Journal of Marine Science and Application 2018年第3期17卷 380-388页

作者： Yiwen Wang Weiguo Wu c.Guedes Soares School of Transportation Wuhan University of Technology Wuhan 430070China centre for Marine Technology and Ocean Engineering (cENTEc) Instituto Superior TecnicoUniversidade de Lisboa 1049-001 LisbonPortugal

The ship motions and wave-induced loads of a new type of river-to-sea ship are investigated experimentally and numerically. A river-to-sea ship is an unconventional type of container ship characterized by high breadth to draft ratio and low length to breadth ratio, which makes it more prone to hydroelasticity than conventional ships of the same size. A segmented model was tested under two loading conditions, namely, ballast and loaded conditions, to determine the vertical motions and wave-induced loads under each condition. Results are compared with numerical simulations in the frequency domain. The wave-induced responses are calculated by a nonlinear time domain code at each time step. The response amplitude operators of vertical ship responses in regular waves are analyzed, and the wave-induced responses are consistent with the experimental results.

关键词： River-to-sea ship Wave-induced responses Nonlinear time domain simulation Experiment

Optimal Selling Time in Stock Market over a Finite Time Horizon

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Acta Mathematicae Applicatae Sinica 2012年第3期28卷 557-570页

作者： S.c.P.YAM S.P.YUNG W.ZHOU The chinese University of Hong Kong China The University of Hong Kong China

In this paper, we examine the best time to sell a stock at a price being as close as possible to its highest price over a finite time horizon [0, T], where the stock price is modelled by a geometric Brownian motion and the ＇closeness＇ is measured by the relative error of the stock price to its highest price over [0, T]. More precisely, we want to optimize the expression：V^＊=sup 0≤τ≤T E[Vτ/MT],where （Vt）t≥0 is a geometric Drownian motion with constant drift α and constant volatility σ 〉 0, Mt = max Vs 0≤a〈t is the running maximum of the stock price, and the supremum is taken over all possible stopping times 0 ≤ τ≤T adapted to the natural filtration （Ft）t≥0 of the stock price. The above problem has been considered by Shiryacv, Xu and Zhou （2008） and Du Toit and Peskir （2009）. In this paper we provide an independent proof that when α=1/ 2 σ^2 , a selling strategy is optimal if and only if it sells the stock either at the terminal time T or at the 1 2 moment when the stock price hits its maximum price so far. Besides, when α 〉1/2σ^2 , selling the stock at the terminal time T is the unique optimal selling strategy. Our approach to the problem is purely probabilistic and has been inspired by relating the notion of dominant stopping pr of a stopping time τ to the optimal stopping strategy arisen in the classical ＂Secretary Problem＂.

关键词： optimal Stopping stock selling buy and hold local time

Population increase and changes in behavior and morphology in the critically Endangered Redonda ground lizard(Pholidoscelis atratus)following the successful removal of alien rats and goats

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Integrative Zoology 2021年第3期16卷 379-389页

作者： colin M.DONIHUE Jennifer c.DALTRY Shanna cHALLENGER Anthony HERREL UMR 7179 c.N.R.S/M.N.H.N. Département Adaptations du VivantParisFrance Department of Biology Washington University in St.LouisSt.LouisMissouriUSA Fauna&Flora International David Attenborough BuildingPembroke StreetCambridgeUK Department of Environment St.John’sAntigua Environmental Awareness Group St.John’sAntigua

Redonda is a small volcanic caribbean island that is home to at least 4 endemic lizard species,including the critically Endangered ground lizard(Pholidoscelis atratus).Black rats(Rattus rattus)and domestic goats(capra hircus)were introduced to the island at some time after its discovery by Europeans in the late *** had a devastating effect on the island,resulting in the loss of nearly all trees and most of the ground *** count surveys of *** in 2012 indicated low densities,and the invasive rats were observed hunting and preying on the *** populations of rats and goats were successfully removed in 2017 as part of an ecological restoration program,and native vegetation and invertebrate populations have increased rapidly *** surveys in 2017,2018,and 2019 show the lizard population has increased by more than *** 2017,as rats and goats were being removed,we evaluated the morphology and escape behavior of this species and repeated these measurements 1 year *** observed that *** had become bolder,with a reduced flight *** also detected changes in limb morphology related to locomotion and suggest possible explanations that will need to be further investigated in the *** results show how the removal of invasive species can rapidly affect lizard population recovery and behavior,potentially restoring island ecosystems to their pre-human interference dynamics.

关键词： Antigua and Barbuda caribbean conservation endangered species invasive alien species island biology Lesser Antilles pest removal

consensus on Intervals of communication Delay

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International Journal of Automation and computing 2018年第1期15卷 13-24页

作者： Heitor J.Savino Fernando O.Souza Luciano c.A.Pimenta Graduate Program in Electrical Engineering Federal University of Minas Gerais Institute of computing Federal University of Alagoas Department of Electronic Engineering Federal University of Minas Gerais

This paper brings out a structured methodology for identifying intervals of communication time-delay where consensus in directed networks of multiple agents with high-order integrator dynamics is achieved. It is built upon the stability analysis of a transformed consensus problem which preserves all the nonzero eigenvalues of the Laplacian matrix of the associated communication topology graph. It is shown that networks of agents with first-order integrator dynamics can be brought to consensus independently of communication delay, on the other hand, for agents with second-order integrator dynamics, the consensus is achieved independently of communication delay only if certain conditions axe satisfied. conversely, if such conditions axe not satisfied, it is shown how to compute the intervals of communication delay where multiple agents with second-order or higher-order can be brought to consensus. The paper is ended by showing an interesting example of a network of agents with second-order integrator dynamics which is consensable on the first time-delay interval, but as the time-delay increases, it loses consensability on the second time-delay interval, then it becomes consensable again on the third time-delay interval, and finally it does not achieve consensus any more on the fourth time-delay interval. This example shows the importance of analyzing consensus with time-delay in different intervals.

关键词： Time delay systems multi-agent systems consensus communication delay roots location.

Mapping tree canopies in urban environments using airborne laser scanning (ALS):a Vancouver case study

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Forest Ecosystems 2018年第4期5卷 429-437页

作者： Giona Matasci Nicholas c.coops David A.R.Williams Nick Page Department of Forest Resource Management Unlversity of British Columbia2424Main MallVancouverBC V6T IZ4Canada Vancouver Board of Parks and Recreation 2099Beach AvenueVancouverBC V6G IZ4Canada

Background: The distribution of forest vegetation within urban environments is critically important as it influences urban environmental conditions and the energy exchange through the absorption of solar radiation and modulation of evapotranspiration. It also plays an important role filtering urban water systems and reducing storm water ***: We investigate the capacity of ALS data to individually detect, map and characterize large(taller than15 m) trees within the city of Vancouver. Large trees are critical for the function and character of Vancouver’s urban forest. We used an object-based approach for individual tree detection and segmentation to determine tree locations(position of the stem), to delineate the shape of the crowns and to categorize the latter either as coniferous or ***: Results indicate a detection rate of 76.6% for trees > 15 m with a positioning error of 2.11 m(stem location). Extracted tree heights possessed a RMSE of 2.60 m and a bias of-1.87 m, whereas crown diameter was derived with a RMSE of 3.85 m and a bias of-2.06 m. Missed trees are principally a result of undetected treetops occurring in dense, overlapping canopies with more accurate detection and delineation of trees in open ***: By identifying key structural trees across Vancouver’s urban forests, we can better understand their role in providing ecosystem goods and services for city residents.

关键词： Urban forest Large trees Light detection and ranging Airborne laser scanning

Visual problems: a review of prevalence studies on visual impairment in school-age children

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International Journal of Ophthalmology(English edition) 2019年第6期12卷 1037-1043页

作者： Uchenna c.Atowa Rekha Hansraj Samuel O.Wajuihian Discipline of Optometry University of KwaZulu-Natal

childhood visual impairment(VI) have a significant impact on the educational achievement, career choices and social life of affected individual, and in children, is mainly due to either preventable or treatable causes. Reliable data on the prevalence and causes of VI in children will guide the development of a systematic vision screening program for its early detection and successful treatment of possible causes. The purpose of this literature review is to summarize the available data on prevalence and causes of VI in school-age children from various regions globally. A discussion on the major findings highlighting the definition criteria, classifications and limitations for further studies is also presented.

关键词： visual impairment school-age children vision screening school performance

STUDY ON VERTIcAL WATER TEMPERATURE MODEL FOR MIYUN RESERVOIR

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Journal of Hydrodynamics 2000年第4期12卷 75-83页

作者： Li, Y.L. chen, Y.c. Zhang, B.X. Dep. of Hydraulic Eng. Tsinghua Univ. Beijing 100084 China

According to the characters of the Miyun reservoir located in northeast Beijing, one-dimensional method is used to establish a mathematical model of temperature for the reservoir. In this model the heat exchange between water surface and atmosphere, effective diffusion, inflows, outflows, and thermal advection are considered comprehensively. The effective diffusion coefficient, decay coefficient of short wave in water, etc, are calibrated based on the observed stratification data of 1991 in the reservoir. The mathematical model is verified through the agreement with the data of 1992. This model can be used to predict the temperature distribution along the vertical direction for the Miyun reservoir and other similar reservoir.

关键词： computer simulation Heat transfer Mathematical models Temperature distribution

Dengue encephalitis - a case report

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Asian Pacific Journal of Tropical Medicine 2009年第2期2卷 74-75页

作者： P.c.Bhattacharyya Jagdish Prasad Agarwal Department of Medicine & Paediatric Down Town HospitalGuwahatiAssamIndia

Encephalitis is an uncommon manifestation of dengue *** we present a 4 years old female child from Northeast Region of India who suffered from dengue *** our knowledge,this is probably the first diagnosed case of deng... 详细信息

关键词： Encephalitis Dengue fever