检索结果-南通市图书馆

Last electroweak WIMP standing: pseudo-dirac higgsino status and compact stars as future probes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics C 2018年第4期42卷 117-134页

作者： Rebecca Krall matthew Reece Department of Physics Harvard University

Electroweak WIMPs are under intense scrutiny from direct detection, indirect detection, and collider experiments. Nonetheless the pure（pseudo-Dirac） higgsino, one of the simplest such WIMPs, remains elusive. We present an up-to-date assessment of current experimental constraints on neutralino dark matter. The strongest bound on pure higgsino dark matter currently may arise from AMS-02 measurements of antiprotons, though the interpretation of these results has sizable uncertainty. We discuss whether future astrophysical observations could offer novel ways to test higgsino dark matter, especially in the challenging regime with order Me V mass splitting between the two neutral higgsinos. We find that heating of white dwarfs by annihilation of higgsinos captured via inelastic scattering could be one useful probe, although it will require challenging observations of distant dwarf galaxies or a convincing case to be made for substantial dark matter content in ω Cen, a globular cluster that may be a remnant of a disrupted dwarf galaxy. White dwarfs and neutron stars give a target for astronomical observations that could eventually help to close the last, most difficult corner of parameter space for dark matter with weak interactions.

关键词： dark matter higgsino supersymmetry

Forecasting vulnerability of deep extraction level excavations to drawinduced cave loads

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2019年第3期11卷 527-534页

作者： matthew E.Pierce Pierce Engineering

Block and panel caving methods are increasingly used for mining of large and strong orebodies at large depths below the ground surface (>1 km). This paper focuses on the production phase of caving when the extraction level is fully developed and subjected to the weight of overlying caved material. A limit equilibrium solution for estimation of cave loads is critically reviewed and combined with existing empirical tools in order to forecast extraction level performance under cave loading. The analysis results, presented in nomogram form, suggest that the risk of severe squeezing of extraction level tunnels does not increase with cave depths below 500-1000 m due to the beneficial effects of arching. Under normal extraction ratios (ER = ~50%), severe squeezing experienced from cave loads in deep mines appears to be unlikely in all but the weakest rock masses (σcm < 5 MPa, where σcm is the rock mass global strength), even with poor draw control or low drawpoint availability. The likelihood of severe squeezing is greater when large draw areas (HR = 50-75 m, where HR is the hydraulic radius) are combined with low drawpoint availability or poor draw control and locally higher extraction ratios (ER = ~75%), even in better quality rock (σcm = 5-10 MPa). The analysis results are back-analyzed with the extraction level performance before and after a doubling production of rate and draw area at the deep ore zone (DOZ) mine in Indonesia. The extraction level conditions predicted by the nomograms correlate well with the experience at the DOZ, in which extraction level damage increases significantly over the production rampup, accompanied by a significant drop in drawpoint availability.

关键词： Block caving Panel caving Extraction level Draw control Squeezing

The importance of being connected:membrane contact sites and Parkinson’s disease

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2023年第10期18卷 2202-2203页

作者： matthew E.Gegg Department of Clinical and Movement Neurosciences UCL Queen Square Institute of NeurologyLondonUK

Membrane contact sites (MCS) occur between closely apposed organelles and are a means to transport ions and macromolecules between themselves,co-ordinate cellular metabolism,and direct organelle fission and *** MCS be... 详细信息

关键词： connected transport ordinate

TLR4 signaling and the inhibition of liver hepcidin expression by alcohol

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2014年第34期20卷 12161-12170页

作者： Emily Zmijewski Sizhao Lu Duygu Dee harrison-Findik Department of Internal Medicine University of Nebraska Medical CenterOmahaNE 68198-5820United States

AIM: To understand the role of toll-like receptor 4 (TLR4) signaling in the regulation of iron-regulatory hormone, hepcidin by chronic alcohol consumption.

关键词： Iron Small heterodimer partner protein Nuclear factor-κB Alcoholic liver disease Inflammation

Phenotypic trait matching predicts the topology of an insular plant–bird pollination network

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Integrative Zoology 2018年第3期13卷 339-347页

作者： matthew BIDDICK Kevin CBURNS School of Biological Sciences Victoria University of WellingtonWellingtonNew Zealand

Conceptualizing species interactions as networks has broadened our understanding of ecological ***,the factors shaping interaction patterns among species and,therefore,network structure remain *** potentially important factor is the matching of phenotypic ***,we tested for trait matching in a bird–flower visitation network from New *** first quantified the overall network structure and tested whether flower size could account for differences in the visitation rates of flowering *** then explored the relationship between the flower size and bill *** results showed that the interaction network is *** species with large flowers received more visits from birds than plant species with small ***,plant species with large flowers were visited more frequently by birds with large bills,while species with smaller flowers were visited more frequently by birds with small ***,the interaction patterns between birds and flowering plants could be predicted by their morphology,suggesting that phenotypic trait matching is an important predictor of network structure.

关键词： bird-flower visitation network flower morphology plant-animal interactions size coupling

A Structural Bisulfite Assay to Identify DN Cruciforms

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Molecular Plant 2016年第9期9卷 1328-1336页

作者： matthew Gentry Lars Hennig Department of Plant Biology Uppsala BioCenter Swedish University of Agricultural Sciences and Linnean Center for Plant Biology 75007 Uppsala Sweden

In the half century since the discovery of the double-helix structure of DNA, it has become increasingly clear that DNA functionality is based on much more than its sequence in a double-helical structure. Further advances have highlighted the importance of additional aspects of DNA structure： its packaging in the higher order chromatin structure, positioning of nucleosomes along the DNA, and the occurrence of non-helical DNA structures. Of these, the latter has been problematic to prove empirically. Here, we describe a method that uses non-denaturing bisulfite sequencing on isolated Arabidopsis thaliana nuclei to determine the location of cytosines positioned outside the double helix as a result of non-B-form DNA structures. We couple this with computational methods and S1 nuclease digest to reliably identify stable, non-B-form, cruciform structures. This enables us to identify a palindrome in the promoter of FLOWERING LOCUS T that forms a stable non-B-form structure. The stronger conservation of the ability to form a nonhelical secondary structure than of the sequence suggests that this structure is biologically relevant.

关键词： DNA structure cruciform DNA genome organization

Assessing the accessibility to fire hazards in preserving historical towns: Case studies in suburban Shanghai, China

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Architectural Research 2022年第4期11卷 731-746页

作者： harrison Huang Lu Li Yan Gu College of Civil Engineering and Architecture Zhejiang UniversityHangzhouChina Department of Environmental Design Fuzhou UniversityFuzhouChina Center for Balance Architecture of Zhejiang University China Architectural Design&Research Institute of Zhejiang University China

Protecting large-scale heritage settlements from being damaged by fires has become increasingly crucial in developing areas that lack adequate legislation, emergency planning, and particularly efficient techniques. This study provides a systematic emergency assessment methodology for evaluating the accessibility of specific fire-fighting techniques to mitigate fire hazards in historical towns and examines how the integration of municipal and local fire services works. Specifically, this paper examines the accessibility of fire trucks, local fire services and the overall protection capacity. There are quantitative calculations of the obstruction degrees on main streets, the feasible moving distances of fire-fighting vehicles and firefighters at a given time, and the fire protection coverage and intensity in each town. Using these methods, this paper systematically assesses the fire resistance of three historical towns, Chuansha, Gaoqiao and Fengjing, as case studies. In contrast to previous studies focusing on the vulnerability of buildings in large historical settlements, this assessment method combines an examination of street networks and various emergency response techniques and is particularly applicable to developing areas.

关键词： Accessibility to fire hazards Emergency assessments Fire-fighting techniques Heritage protection Historical towns Developing areas

Corrosion of magnesium and magnesium–calcium alloy in biologically-simulated environment

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2014年第5期24卷 539-546页

作者： Richard harrison Diana Maradze Simon Lyons Yufeng Zheng Yang Liu Wolfson Centre for Stem Cells Tissue Engineering and Modelling (STEM) Centre for Biomolecular Sciences University of Nottingham College of Engineering Peking University Wolfson School of Mechanical and Manufacturing Engineering Loughborough University Loughborough

A study of biocompatibility and corrosion of both metallic magnesium(Mg) and a magnesium alloy containing 1% calcium(Mg–Ca) were investigated in in vitro culture conditions with and without the presence of bone marrow derived human mesenchymal stem cells(h MSCs).Chemical analysis of the degraded samples was performed using XRD and FEGSEM. The results from the XRD analysis strongly suggested that crystalline phase of magnesium carbonate was present on the surface of both the Mg and Mg–Ca samples. Flame absorption spectrometry was used to analyse the release of magnesium and calcium ions into the cell culture medium. Magnesium concentration was kept consistently at a level ranging from 40 to 80 m M for both Mg and Mg–Ca samples. No cell growth was observed when in direct contact with the metals apart from a few cells observed at the bottom of culture plate containing Mg–Ca alloy. In general, in vitro study of corrosion of Mg–Ca in a biologicallysimulated environment using cell culture medium with the presence of h MSCs demonstrated close resemblances to in vivo corrosion. Although in vitro corrosion of Mg–Ca revealed slow corrosion rate and no immediate cytotoxicity effects to h MSCs, its corrosion rate was still too high to achieve normal stem cell growth when cells and alloys were cultured in vitro in direct contact.

关键词： Magnesium Biometal Corrosion Biocompatibility Stem cells In vitro

Modeling Biodiversity Benefits and External Costs from a Keystone Predator Reintroduction Policy

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2012年第3期9卷 385-394页

作者： Yohan LEE Jane L. harrison Cristina EISENBERG Byungdoo LEE Department of Forest Ecosystem and Society Oregon State University Corvallis OR 97331 U.S.A Department of Forest Engineering Resources and Management Oregon State University Corvallis OR 97331 U.S.A Korea Forest Research Institute Hoegiro 57 Dongdaemun-gu Seoul 130-712 South Korea

In this paper, an economic model was constructed to determine the optimal wolf population and distribution across the Northern Rocky Mountains. Both ecological and economic concepts were incorporated in an implicitly spatial social welfare maximization problem. This interdisciplinary model relies on multiple data sources, including current wolf population and distribution information, opportunity cost to local landowners, and contingent valuation studies to determine willingness-to-pay for wolves. Economic models tend to externalize ecological concerns and ecological models often omit the complex human dimensions of conservation policy. Accordingly, this model can serve as a guide for integrating best practices from both fields. The model presented here is sufficiently general to apply to wolves in other ecosystems and to other highly interacting species such as beavers and bison. The Northern Rocky Mountain wolf was used as an example of how this economic model works, but this model can be applied far more broadly.

关键词： Wolf Economics Biodiversity Ecological economics Opportunity cost Conservationpolicy Endangered species