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Modeling the early transmission of COVID-19 in New York and San Francisco using a pairwise network model

Infectious Disease Modelling 2022年第1期7卷 212-230页

作者： Shanshan Feng Xiao-Feng Luo Xin Pei Zhen Jin Mark lewis Hao Wang Department of Mathematics North University of ChinaTaiyuanShanxi030051China College of Mathematics Taiyuan University of TechnologyShanxiTaiyuan030024China Complex System Research Center Shanxi UniversityTaiyuan030006ShanxiChina Shanxi Key Laboratory of Mathematical Techniques and Big Data Analysis on Disease Control and Prevention Shanxi UniversityTaiyuan030006ShanxiChina Department of Mathematics and Statistics Sciences University of AlbertaEdmontonAlbertaT6G 2G1Canada Department of Biological Sciences University of AlbertaEdmontonAlbertaT6G 2E9Canada

Classical epidemiological models assume mass ***,this assumption is violated when interactions are not *** the recent COVID-19 pandemic,and resulting shelter in place social distancing directives,mass action models must be modified to account for limited social *** this paper we apply a pairwise network model with moment closure to study the early transmission of COVID-19 in New York and San Francisco and to investigate the factors determining the severity and duration of outbreak in these two *** particular,we consider the role of population density,transmission rates and social distancing on the disease dynamics and *** analysis shows that there is a strongly negative correlation between the clustering coefficient in the pairwise model and the basic reproduction number and the effective reproduction *** shelter in place policy makes the clustering coefficient increase thereby reducing the basic reproduction number and the effective reproduction *** switching population densities in New York and San Francisco we demonstrate how the outbreak would progress if New York had the same density as San Francisco and *** results underscore the crucial role that population density has in the epidemic *** also show that under the assumption of no further changes in policy or transmission dynamics not lifting the shelter in place policy would have little effect on final outbreak size in New York,but would reduce the final size in San Francisco by 97%.

关键词： COVID-19 Social network Quarantine Social distance Clustering coefficient

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Q245R碳钢A-TIG焊接的数值模拟与实验研究

Q245R碳钢A-TIG焊接的数值模拟与实验研究

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作者： nathan Debucquois 哈尔滨工业大学

学位级别：硕士

活性钨极惰性气体保护焊(A-TIG)是最近一种类型的等离子焊接,其特征在于使用非自耗电极和由有源元件制成的涂层焊剂。因其与TIG焊接有相似的高质量焊接引起了最先进行业的兴趣,但与TIG焊接相比,其穿透深度有所增加。通过数值模拟和实验... 详细信息

活性钨极惰性气体保护焊(A-TIG)是最近一种类型的等离子焊接,其特征在于使用非自耗电极和由有源元件制成的涂层焊剂。因其与TIG焊接有相似的高质量焊接引起了最先进行业的兴趣,但与TIG焊接相比,其穿透深度有所增加。通过数值模拟和实验研究了用于Q245R钢的不同氧化物涂层的使用。还研究了焊接强度对焊接的影响。目的是通过数值模拟发现这两个参数对Q245R碳钢焊接的重要性。在了解了有关A-TIG模拟的现有文献后,提出并开发了用于模拟的不同模型,本论文所选用的模型是热力学平衡假设。然后在分析仿真结果后,给出了所测试的不同参数的影响。接着完成了实验过程以及对这些实验结果的分析。然后通过不同纵横比的视觉差异简单地对不同焊接效果进行了比较。根据最终目标,可以使用两种不同的方法来模拟等离子体。如果目的是确定焊接后板内的应力或相变,采用第一种方法热机械和冶金方法(TMM)。这种方法可以与特定的软件一起使用,并将侧重于凝固效果。如果更倾向于确定熔池的形成以及等离子体和熔池之间的相互作用,使用第二种方法热流体流动方法(HFF)。对于HFF方法,热物理,等离子体物理,流体物理和电磁物理必须一起解决。HFF方法用于该数值模拟,并且可以使用不同的模型进行模拟。实际上存在不同模型可用于模拟A-TIG焊接。其中一个模型包括单独模拟板,通过计算方式在正常等离子体和板之间的边界处近似不同参数,所需的不同参数,压力、热通量和电流密度可以用高斯方法近似。所用不同的输入参数,例如强度、效率、效果半径和高斯参数。另一种方法是以实验方式获取这些数据。然后,可以通过计算流体动力学软件(CFD)简单地模拟板内焊接,以便了解焊池的行为或使用特定软件来确定焊接的机械效果。本文选用第二种方法,即LTe方法(局部热力学平衡),它假定等离子体内的电子和离子的动能在局部平衡时由于足够高的碰撞水平而产生。该方法在等离子体内确认为真实,但不在边界处时需要特殊处理。该假设允许简单地使用麦克斯韦方程来解决等离子体内电子的电导率。该方法的不便之处在于该方法给出的结果高度依赖于所选择的网格划分。最后一个模型是使用非LTe假设的模型,这个模型不考虑简化,需要在扩散中使离子和电子之间产生差异。该方法解决了边界处的问题,但计算起来更复杂,并且在边界处需要更多数据。这些数据大多数都是通过实验获得的,这使得从头开始工作几乎不可能,需要使用文献中的数据或通过实验来测量这些数值。另一个模型可以用作LTe或非LTe模型的扩展。该模型的特殊性在于模拟焊接过程中形成的金属蒸汽。实际上,在焊接过程中,焊接板会释放出一些金属烟雾。这些烟雾的比例非常低,但对等离子体的热物理性质影响很大,尤其是在焊缝的周围。该模型实际上正在研究中,因为最近的研究只能模拟2种元素对等离子体的影响。尽管这些变化不容忽视,但如果没有这种模型,模拟效果会很好。为了减少计算时间模拟,在2D中使用轴对称模型完成。模拟在静态下完成,简化计算,避免了移动电极的繁重计算。这种模型不能用于精确的焊接模拟,因为不能模拟焊盘沿板的熔化和凝固,但由于焊接速度不是研究的参数,因此模拟时间不会以定性的方式对所研究的参数产生影响,只有确切的结果才能与实验相比较。在模拟中,纵横比,焊道尺寸,热影响区(HAZ)的尺寸以及熔池和等离子体内的流速将引起重视。热影响区对应于未熔化但由于受热而导致微观结构变化的区域,该温度称为Ac1。该温度已经通过计算确定,以便根据焊接参数比较该过渡区域的尺寸变化。模拟的目的是找出不同参数对焊池形状的影响。为此,计算了2组模拟,第一组模拟了焊接电流对焊池形状的影响。为此,模拟了3种不同的焊接强度,130A,150A和200A。第二组实验通过改变焊池中的氧浓度,研究涂层对焊池形状的影响。这会影响表面张力梯度。制备了3个选择的涂层,一个只有表面相变浓度的一半,一个与表面相变浓度相同,一个是表面相变浓度的一倍半。模拟结果表明,焊接强度的增加使等离子体温度升高,导致的穿透深度加深,从而使熔池的热通量增加,而且由于焊池内的焦耳效应更高,因电流导致的焊池加热。但是这种穿透深度的增加损害热影响区域的尺寸而变得更宽。此处未模拟的其他效应猜想也会影响焊池的温度,例如由于涂层对等离子体的电离引起的电弧收缩以及产生高电流的熔池顶部的熔渣的影响。电流对焊池内的流体流动有轻微影响,但效果只是最大速度范围,这是由洛伦兹力引起的,但是对流体流动的方向没有影响。模拟还表明,通过Marangoni效应,氧化物的数量正在推动焊池中的流动方向,实际上,一定量的氧化物低于表面相变量(SPT),同时导致表面张力梯度为负,因此,在焊池中向外流动,而等于或大于SPT量的氧化物含量将导致向内流动,从而导致焊接深度的急剧增加。由于选择了稳定模拟的事实,未模拟在该模拟上的影响是焊接点前后之间的阻力差。然

关键词： A-TIG 数值模拟 Q245R L.T.e假设

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A Degassing Inlet Structure for Aquaculture Ponds

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World Journal of engineering and Technology 2020年第2期8卷 159-167页

作者： Joshua M. A. Caasi eric Krebs nathan Huysman Jill M. Voorhees Michael e. Barnes School of engineering Benedictine College Atchison Kansas USA McNenny State Fish Hatchery South Dakota Department of Game Fish and Parks Spearfish South Dakota USA

Structures separating fish hatchery ponds from open spring water sources must restrict fish movement from the pond to the spring, allow for constant water flow, and potentially reduce incoming spring water gas supersaturation. This article describes a novel inlet structure that fulfills those requirements. In addition, it requires minimal maintenance, and allows for the quick and easy removal of debris in the event of partial plugging. This simple aluminum structure consists of a mount for attachment to the inflow pipe and a terminal splash plate with aeration holes. The splash plate is perpendicular to the water flow during normal operations to both prevent fish from jumping into the pipe and aerate the incoming water. However, it can be easily swiveled upward for the efficient removal of debris. Use of the inlet structure consistently decreased gas supersaturation in the spring water as it entered the fish production pond. By decreasing gas levels and maintaining water flows, potentially hazardous fish health issues can be avoided by using this structure. In addition, this relatively inexpensive and simple device will greatly reduce the labor required for removing debris compared to traditional screens.

关键词： Fish Hatchery Rearing Pond Splash Plate Inlet Structure Total Gas Pressure

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Long-Term Passive Integrated Transponders (PIT) Tag Retention in Juvenile Rainbow Trout and Brown Trout

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Open Journal of Marine Science 2020年第3期10卷 110-115页

作者： Barry J. Hanson Jacob L. Davis Jill M. Voorhees nathan Huysman Michael e. Barnes Department Game Fish and Parks McNenny State Fish Hatchery Spearfish SD USA Department Game Fish and Parks Outdoor Campus West Rapid City SD USA

Two hundred and forty-three juvenile rainbow trout Oncorhynchus mykiss ranging from 73 to 119 mm were implanted with 8, 9, or 10 mm Passive Integrated Transponder (PIT) tags, with tag retention and fish survival observed for 343 days. Similarly, 173 brown trout Salmo truttae="font-size:12px;font-family:Verdana;"> ranging from 71 to 86 mm were implanted with 8 or 10 mm PIT tags and observed for 293 days. Over the entire duration of the study, rainbow trout ejected only six tags, while no tags were ejected from the brown trout. All of the rainbow trout tag ejections occurred before 50 days post-tagging. There was no significant difference in the length or weight of fish that ejected tags compared to those that retained tags. No fish died during the trials. These results indicate that rainbow trout and brown trout at the sizes used in this study can be safely implanted with, and subsequently retain, up to 10 mm PIT tags for durations of nearly one year.

关键词： Tagging Salmonids Passive Integrated Transponders PIT Tag Fingerling

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Peroxidase-Like Reactivity at Iron-Chelation Sites in a Mesoporous Synthetic Melanin

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CCS Chemistry 2021年第3期3卷 1483-1490页

作者： Yijun Xie Kelsey A.Krug Kristine S.Cay Mark Kalaj Naneki C.McCallum Zofia e.Siwicka Zhao Wang nathan C.Gianneschi Michael D.Burkart Jeffrey D.Rinehart Materials Science and engineering Program University of CaliforniaSan DiegoLa JollaCA 92093 Department of Chemistry and Biochemistry University of CaliforniaSan DiegoLa JollaCA 92093 Department of Chemistry Northwestern UniversityEvanstonIL 60208 International Institute of Nanotechnology Simpson-Querrey InstituteChemistry of Life Processes InstituteNorthwestern UniversityEvanstonIL 60208 Pritzker School of Molecular engineering University of ChicagoChicagoIL 60637 Lurie Cancer Center Northwestern UniversityEvanstonIL 60208 Department of Materials Sciences and engineering Northwestern UniversityEvanstonIL 60208 Department of Biomedical engineering Northwestern UniversityEvanstonIL 60208

High catalytic activity and substrate specificity make enzymes a rich source of inspiration for catalyst ***-opting the advantages of natural materials while tuning them to a modified form and purpose,however,is not a straightforward synthetic *** of L-3,4-dihydroxyphenylalanine(L-DOPA)results in amorphous polymer nanoparticles that are similar in many ways to natural ***,the authors introduce mesoporosity and iron ion chelation to synthesize a variant of the L-DOPA polymer with high peroxidase-like *** results indicate catalytic reaction with peroxide under mildly acidic conditions(pH 5.4 and 6)with a greater maximum reaction velocity(Vmax)than horseradish peroxidase(HRP)at optimal pH 3.5–*** between Fe(Ⅲ)and Fe(Ⅱ)loading indicates that either can be used as a starting point to trigger reactivity,though Fe(Ⅱ)loading leads to materials with twice the Vmax of the Fe(Ⅲ)-loaded *** lack of catalyst degradation despite the redox changes and presence of radical species is consistent with the robust nature and redox versatility of polydopamine-based materials and demonstrates strong potential as a versatile redox-catalysis platform.

关键词： L-DOPA mesoporosity peroxidase-like reactivity iron ion chelation catalysis

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Using accelerometry to compare costs of extended migration in an arctic herbivore

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Current Zoology 2017年第6期63卷 667-674页

作者： Mitch D. WeeGMAN Stuart BeARHOP Geoff M. HILTON Alyn J. WALSH Larry GRIFFIN Yehezkel S. ReSHeFF Ran nathan Anthony DAVID Fox Centre for ecology and Conservation College of Life and Environmental Sciences University of Exeter Cornwall Campus Penryn TR109EZ UK Wildfowl & Wetlands Trust Slimbridge Gloucester GL2 7BT UK National Parks and Wildlife Service Wexford Wildfowl Reserve North Slob Wexford Ireland Wildfowl & Wetlands Trust Caerlaverock Wetland Centre Eastpark Farm Caerlaverock Durnfriesshire DG1 4RS UK Department of ecology Evolution and Behavior The Hebrew University of Jerusalem Givat Ram Jerusalem 91904 Israel Department of Bioscience Aarhus University Kale Grenavej 14 RФnde DK-8410 Denmark Present address: School of Natural Resources University of Missouri Columbia MO 65211 USA.

Understanding how individuals manage costs during the migration period is challenging because individuals are difficult to follow between sites; the advent of hybrid Global Positioning Systemacceleration （ACC） tracking devices enables researchers to link spatial and temporal attributes of avian migration with behavior for the first time ever. We fitted these devices on male Greenland white-fronted geese Anser albifrons flavirostris wintering at 2 sites （Loch Ken, Scotland and Wexford, Ireland） to understand whether birds migrating further during spring fed more on winter- ing and staging areas in advance of migration episodes. Although Irish birds flew significantly further （ca. 300 kin） than Scottish birds during spring, their cumulative hours of migratory flight, flight speed during migration, and overall dynamic body ACC （i.e., a proxy for energy expenditure） were not significantly different. Further, Irish birds did not feed significantly more or expend significantly more energy in advance of migration episodes. These results suggest broad individual plasticity in this species, although Scottish birds arriving on breeding areas in Greenland with greater energy stores （because they migrated less） may be better prepared for food scarcity, which might increase their reproductive success.

关键词： avian migration cost energy expenditure global positioning system-acceleration tracking devices Greenland whitefronted geese individual decision-making proportion of time feeding.

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Asymmetry in Resting Alpha Activity: effects of Handedness

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Open Journal of Medical Psychology 2012年第4期1卷 86-90页

作者： Ruth e. Propper Jenna Pierce Mark W. Geisler Stephen D. Christman nathan Bellorado Psychology Department Merrimack College North Andover USA Psychology Department Montclair State University Montclair USA Psychology Department San Francisco State University San Francisco USA Psychology Department University of Toledo Toledo USA

Study Aim: Frontal electroencephalographic (eeG) alpha band power during rest shows increased right, and/or de-creased left, hemisphere activity under conditions of state or trait withdrawal-associated affect. Non-right-handers (NRH) are more likely to have mental illnesses and dispositions that involve such withdrawal-related affect. The aim of the study was to examine whether NRH might be characterized by increased right, relative to left, hemisphere activity during rest. Methods: The present research investigated that hypothesis by examining resting eeG alpha power in consistently-right-handed (CRH) and NRH individuals. Results: In support of the hypothesis, NRH demonstrated de-creased right hemisphere alpha power, and therefore increased right hemisphere activity, during rest, compared to CRH. Conclusions: The study demonstrates further support for an association between increased right hemisphere activity and negative affect via an association between such eeG activity and NRH.

关键词： eeG Handedness Asymmetry emotion

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Transgenerational bone toxicity in F3 medaka (Oryzias latipes) induced by ancestral benzo[a]pyrene exposure: Cellular and transcriptomic insights

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Journal of environmental Sciences 2023年第5期127卷 336-348页

作者： Jiezhang Mo Miles Teng Wan DorisWai-Ting Au Jingchun Shi nathan Tam Xian Qin Napo K.M.Cheung Keng Po Lai Christoph Winkler Richard Yuen-Chong Kong Frauke Seemann Southern Marine Science and engineering Guangdong Laboratory(Guangzhou) Guangzhou 510000China Shenzhen Key Laboratory for the Sustainable Use of Marine Biodiversity Research Centre for the Oceans and Human HealthShenzhen Research InstituteCity University of Hong KongShenzhen 518057China State Key Laboratory of Marine Pollution and Department of Chemistry City University of Hong KongHong Kong SARChina Laboratory of environmental Pollution and Integrative Omics Guilin Medical UniversityHuan Cheng North 2nd Road 109Guilin 541004China Department of Biological Sciences National University of Singapore119077Singapore Center for Coastal Studies and Department of Life Sciences Texas A&M University-Corpus ChristiCorpus ChristiTexas 78412USA

Benzo[a]pyrene(BaP),a ubiquitous pollutant,raises environmental health concerns due to induction of bone toxicity in the unexposed *** of F0 ancestor medaka(Oryzias latipes)to 1μg/L BaP for 21 days causes reduced vertebral bone thickness in the unexposed F3 male *** reveal the inherited modifications,osteoblast(OB)abundance and molecular signaling pathways of transgenerational BaP-induced bone thinning were *** analysis showed a reduction in OB *** of the miRNA and mRNA transcriptomes revealed the dysregulation of Wnt signaling(frzb/ola-miR-1–3p,sfrp5/ola-miR-96–5p/miR-455–5p)and bone morphogenetic protein(Bmp)signaling(bmp3/ola-miR-96–5p/miR-181b-5p/miR-199a-5p/miR-205–5p/miR-455–5p).Both pathways are major indicators of impaired bone formation,while the altered Rank signaling in osteoclasts(c-fos/miR-205–5p)suggests a potentially augmented bone ***,a typical BaP-responsive pathway,the Nrf2-mediated oxidative stress response(gst/ola-miR-181b-5p/miR-199a-5p/miR-205),was also ***,mRNA levels of epigenetic modification enzymes(e.g.,hdac6,hdac7,kdm5b)were found *** findings indicated that epigenetic factors(e.g.,miRNAs,histone modifications)may directly regulate the expression of genes associated with transgenerational BaP bone toxicity and warrants further *** identified candidate genes and miRNAs may serve as potential biomarkers for BaP-induced bone disease and as indicators of historic exposures in wild fish for conservation purposes.

关键词： Polycyclic aromatic hydrocarbons (PAHs) Transcriptome Impaired bone formation Molecular pathways MicroRNAs Medaka(Oryzias latipes)

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用快速凝固铝粉制造的新型铝合金

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导弹与航天运载技术 1982年第11期 74-83页

作者： R.e.lewis 榕江

必须发展新型铝合金,以便在今后10年内为新型飞机、宇宙飞行器和导弹系统提供第一流性能指标。这些性能指标可引起结构部件的重量减轻,而其重量减轻反过来又可增大射程和有效载荷、延长使用寿命以及降低使用期间费用。最近进行的可行性... 详细信息

必须发展新型铝合金,以便在今后10年内为新型飞机、宇宙飞行器和导弹系统提供第一流性能指标。这些性能指标可引起结构部件的重量减轻,而其重量减轻反过来又可增大射程和有效载荷、延长使用寿命以及降低使用期间费用。最近进行的可行性和设计比较研究为选择可导致重量大大减轻的改进型铝合金的某些性能指标提供了依据。这些性能指标是:

关键词：薄片空气雾化激冷表面氧化膜结构重量旋流器合金粉末合金粉铝合金轻有色金属合金粒度分析铝粉金属粉末快速凝固超速凝固

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拜登的环境政策及其可持续性

拜登的环境政策及其可持续性

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作者： nathan William Rockwood 浙江大学

学位级别：硕士

As the *** among the world’s top emitters of greenhouse gases（GHGs）,it is vital to sustained climate change mitigation that successive presidential administrations establish and maintain consistent and effective *** are three objectives to this study: identify domestic and international factors that led to President Biden’s transition from President Trump’s agenda;define how to address traditional energy security concerns;and suggest how elements of *** can be utilized to sustain President Biden’s environmental agenda beyond his presidency.A two-pronged conceptual framework is utilized for analysis of international and domestic *** the international level,the efficacy of *** change policy is based on theories of global governance（e.g.,multiple bilateralisms（MBs））and Kenneth Waltz’s three levels of analysis: state-societal,interstate,and individual ***,*** policy is analyzed through the principles of federalism and separation of powers,as well as engagement with civic society,NGOs,and industry and business *** include comparative case studies of the eU,China,the U.S.,and India,within the context of the Conference of the Parties（COPs）and historical analysis over the last 30 ***,President Biden has taken several steps to return the *** a position of climate change leadership,with America’s reaffirmation of the Paris Climate Agreement（PCA）.He has reformed domestic environmental policy through executive orders,proposed Congressional legislation（e.g.,Build Back Better）,and innovative research and development programs（e.g.,the Advanced Research Projects Agency-Climate（ARPA-C））,effectively reversing President Trump’s *** the conclusions of this study are that the *** transform its energy landscape in the areas of power generation,transportation,building stock,and ***,sustaining policy beyond Biden’s tenure will require communication bet

关键词：拜登政府环境政策可持续性

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