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A COVID-19 epidemic model with latency period

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Infectious Disease Modelling 2020年第1期5卷 323-337页

作者： Z.Liu P.magal.O.Seydi G.Webb School of Mathematical Sciences Beijing Normal UniversityBeijing100875People's Republic of China Univ.Bordeaux France CNRSIMBUMR 5251F-33400TalenceFrance Département Tronc Commun École Polytechnique de ThiésSenegal Mathematics Department Vanderbilt UniversityNashvilleTNUSA

At the beginning of a COVID-19 infection,there is a period of time known as the exposed or latency period,before an infected person is capable of transmitting the infection to another *** develop two differential equations models to account for this *** first is a model that incorporates infected persons in the exposed class,before transmission is *** second is a model that incorporates a time delay in infected persons,before transmission is *** apply both models to the COVID-19 epidemic in *** estimate the epidemiological parameters in the models,such as the transmission rate and the basic reproductive number,using data of reported *** thus evaluate the role of the exposed or latency period in the dynamics of a COVID-19 epidemic.

关键词： Corona virus Reported and unreported cases Isolation Quarantine Public closings Epidemic mathematical model

Senecio bonariensis Hook.&*** arsenic phytoextractor from water in laboratory and field trials

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Emerging Contaminants 2019年第1期5卷 15-22页

作者： Vanesa Perez Cuadra Viviana Cambi Martín Esposito María Gabriela Sica magal.Verolo Amira Siniscalchi Elisa Rosalia Parodi Depto.Biología Bioquímica y Farmacia.Universidad Nacional del Sur(UNS)San Juan 670C.P.8000Bahía BlancaProv.Buenos AiresArgentina CCT BB-INBIOSUR UNS-CONICET San Juan 671C.P.8000Bahía BlancaProv.Buenos AiresArgentina Departamento de Agronomía(UNS) San Andres 800C.P.8000Bahía BlancaProv.Buenos AiresArgentina CCT BB-PLAPIQUI-UNS-CONICET Camino La Carrindanga km 7C.P.8000Bahía BlancaProv.Buenos AiresArgentina CCT BB-IADO-UNS-CONICET Camino La Carrindanga km 7C.P.8000Bahía BlancaProv.Buenos AiresArgentina

The use of plant species to cleanse groundwater with excessive concentrations of arsenic(As)derived from contact with weathered materials has become a valuable option to treat *** aim of this work was to analyze the bioaccumulation capacity of As of Senecio bonariensis(Asteraceae)through controlled laboratory tests and uncontrolled trials in the field in order to generate a low cost method applicable in rural areas that do not have systems of water *** collected from the natural environment were arranged in hydroponic crops under controlled and uncontrolled conditions,in the first case with increasing concentrations of As for 45 days,and in the second,with a constant concentration of As for a period in a range between 45 and 90 *** plants were processed and dried for the measurement of *** both tests,in all the samples there was a noticeable accumulation of As,generally greater in roots than in *** controlled conditions the plants accumulated more As in relation to greater concentration of this element in the *** all the trials a high bioaccumulation of As was found,which turns the plant into a *** to the ability of *** to accumulate As,and even more because of the great biomass produced by this species,it becomes an excellent one to be used for the remediation of arsenical waters.

关键词： Senecio bonariensis Phytoremediation Arsenic Underground water

Use of natural trophic resources by Eastern oysters and Pacific oysters of different ploidy

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Aquaculture and Fisheries 2021年第1期6卷 75-83页

作者： Darien D.Mizuta Gary H.Wikfors Shannon L.Meseck Yaqin Li Mark S.Dixon Hyun Jeong Lim In Joon Hwang magal.Bazzano Steven Pitchford Northeast Fisheries Science Center(NEFSC) NOAA212 Rogers AveMilfordCT06460USA East Sea Fisheries Research Institute National Institute of Fisheries ScienceGangneung25435South Korea West Sea Fisheries Institute National Institute of Fisheries ScienceIncheon22383South Korea

Ploidy manipulation,such as triploidy,in farmed oysters has been used as a tool to enhance oyster quality throughout all seasons because triploid oysters allocate less energy to gametogenesis,and therefore are deemed better performers than fertile ***,scientific reports describing no differences between ploidies and,in certain conditions,disadvantages of triploids are not *** the use of triploid oyster seed increases culture cost for growers,consistency in performance of triploids is considered to be an important ***,research to assess how ploidy affects physiological processes underlying oyster performance is fundamental for the aquaculture *** work was undertaken to assess if ploidy-based differences in performance in the two most commonly cultivated commercial species of oyster in the United States,Crassostrea virginica and Crassostrea gigas,are associated with filtration,feeding,and *** test this hypothesis,biodeposition measurements were made with oysters exposed to ambient water conditions at locations and seasons providing a variety of environmental *** did not show differences in filtration and feeding associated with ploidy,but physiological feeding variables fluctuated with environmental characteristics associated with spatial and seasonal differences.A preliminarily test of the hypothesis that differences in energy metabolism may account for differences in performance among ploidy levels indicates that basal metabolic rates of diploid,triploid,and tetraploid Eastern oysters are not different.

关键词： Ploidy Farmed oysters Feeding Biodeposition Seston Metabolism

Apoptosis in rat transient focal cerebral ischemic stroke:clinical implications

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中国临床神经科学 2000年第Z1期8卷 18-19页

作者： Shoushu Jiao Jue Wang Gal Hever Rongzheng Kuang Jean-Claude Louis Ella magal Department of Neuroscience AmgenInc.One Amgen Center Dr.Thousand OaksCalifornia91320USA

In the early phase of cerebral ischemia,factors threatening neuronal survival in the penumbra include mainly glutamate excitotoxicity,free radical damage and energy failure resulting from recurrent depolarization ***,at later times,other mechanisms come into *** initial ischemic event activates a variety of genetic programs that unfold over the course of hours and *** positron emission tomography and magnetic resonance based techniques demonstrate that the development of irretrievable tissue damage is relatively slow,progressing over the course of several days in some cases,and a viable tissue,defined by hemodynamic and metabolic criteria,is still present many hours after stroke in human or in *** findings suggest that the brain can potentially be“rescued”from infarction many hours after onset of ischemia and challenge the widespread notion of an early and short“therapeutic window”(~3-6h).This realization is of critical importance for stroke therapy because most patients reach medical attention at a time when current therapeutic strategies may no longer be ***,it would be highly desirable to develop therapeutic interventions that can be instituted many hours after the onset of *** believe that addressing the mechanisms of delayed cell death is key to a successful *** studies presented here were designed to document the potential contribution of apoptosis to ischemia induced neuronal *** will discuss the morphological,biochemical and pharmacological evidence for apoptosis in the ischemic stroke.

关键词： positron emission tomography magnetic resonance cerebral ischemia ischemic stroke neuronal death cell death