检索结果-南通市图书馆

Theory and classification of mass extinction causation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2024年第1期11卷 16-36页

作者： Thomas j.Algeo jun Shen State Key Laboratory of Biogeology and environmental geology China University of Geosciences—Wuhan State Key Laboratory of geological Processes and Mineral Resources China University of Geosciences—Wuhan Department of geosciences University of Cincinnati

Theory regarding the causation of mass extinctions is in need of systematization, which is the focus of this contribution. every mass extinction has both an ultimate cause, i.e. the trigger that leads to various climato-environmental changes, and one or more proximate cause(s), i.e. the specific climato-environmental changes that result in elevated biotic mortality. With regard to ultimate causes, strong cases can be made that bolide(i.e. meteor) impacts, large igneous province(LIP) eruptions and bioevolutionary events have each triggered one or more of the Phanerozoic Big Five mass extinctions, and that tectono-oceanic changes have triggered some second-order extinction events. Apart from bolide impacts, other astronomical triggers(*** flares, gamma bursts and supernova explosions) remain entirely in the realm of speculation. With regard to proximate mechanisms, most extinctions are related to either carbon-release or carbon-burial processes, the former being associated with climatic warming, ocean acidification, reduced marine productivity and lower carbonate δ13C values, and the latter with climatic cooling, increased marine productivity and higher carbonate δ13C values. environmental parameters such as marine redox conditions and terrestrial weathering intensity do not show consistent relationships with carbon-cycle *** this context, mass extinction causation can be usefully classified using a matrix of ultimate and proximate factors. Among the Big Five mass extinctions, the end-Cretaceous biocrisis is an example of a bolide-triggered carbon-release event, the end-Permian and end-Triassic biocrises are examples of LIP-triggered carbon-release events, and the Late Ordovician and Late Devonian biocrises are examples of bioevolution-triggered carbon-burial events. Whereas the bolide-impact and LIP-eruption mechanisms appear to invariably cause carbon release, bioevolutionary triggers can result in variable carbon-cycle changes, e.g. carbon burial durin

关键词： biocrisis ultimate cause proximate cause bolide large igneous province bioevolutionary event

Mortality rate after total knee arthroplasty or total hip arthroplasty in patients with a history of liver transplant

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

World journal of Orthopedics 2024年第4期15卷 310-311页

作者： e Carlos Rodriguez-Merchan Department of Orthopedic Surgery La Paz University Hospital-IdiPazMadrid 28046Spain

In this editorial I comment on the article by Ahmed et al published in a recent issue of the World j Orthop 2023;14:*** is well known that patients who have unde.gone a liver transplant(LT)may need to have a total hip arthroplasty(THA)or total knee arthroplasty(TKA)*** et al stated that the mortality rate in these patients was similar to the one of the.general ***,there are three articles previously published that found higher mortality in LT patients who experienced THA/TKA than in the.general population(individuals without LT).Therefore,in this editorial I would like to point out that there is controversy in the literature regarding whether LT patients unde.going THA/TKA have higher mortality than the.general ***,future research should attempt to resolve this controversy.

关键词： Liver transplant Total knee arthroplasty Total hip arthroplasty Results Mortality

Recent Ventures in Interdisciplinary Arctic Research:The ARCPATH Project

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2024年第8期41卷 1559-1568页

作者： Astrid e.j.OgILVIe Leslie A.KINg Noel KeeNLYSIDe François COUNILLON Brynhildur DAVIÐSDÓTTIR Níels eINARSSON Se.gey gULeV Ke FAN Torben KOeNIgK james R.MCgOODWIN Marianne H.RASMUSSON Shuting YANg Institute of Arctic and Alpine Research(INSTAAR) University of ColoradoBoulder CO 80303USA Stefansson Arctic Institute AkureyriÍS-600Iceland Royal Roads University BC V9B 5Y2Canada University of Be.gen Bergen N-5007Norway Nansen environmental and Remote Sensing Centre Bergen N-5007Norway University of Iceland Reykjavík 102Iceland Shirshov Institute of Oceanology Moscow 117218Russia Moscow State University Moscow 11991Russia Chinese Academy of Sciences Beijing 100045China Swedish Meteorological and Hydrological Institute SE-60176 NorrköpingSweden Danish Meteorological Institute CopenhagenØ2100Denmark Obukhov Institute of Atmospheric Physics RAS119017MoscowRussia

This paper celebrates Professor Yongqi gAO's significant achievement in the field of interdisciplinary studies within the context of his final research project Arctic Climate Predictions: Pathways to Resilient Sustainable Societies-ARCPATH(https://***/en/projects/finished-projects/arcpath). The disciplines represented in the project are related to climatology, anthropology, marine biology, economics, and the broad spectrum of social-ecological studies. Team members were drawn from the Nordic countries, Russia, China, the United States, and Canada. The project was transdisciplinary as well as interdisciplinary as it included collaboration with local knowle.ge holders. ARCPATH made significant contributions to Arctic research through an improved understanding of the mechanisms that drive climate variability in the Arctic. In tandem with this research, a combination of historical investigations and social, economic, and marine biological fieldwork was carried out for the project study areas of Iceland, greenland, Norway, and the surrounding seas, with a focus on the joint use of ocean and sea-ice data as well as social-ecological drivers. ARCPATH was able to provide an improved framework for predicting the near-term variation of Arctic climate on spatial scales relevant to society, as well as evaluating possible related changes in socioeconomic realms. In summary, through the integration of information from several different disciplines and research approaches, ARCPATH served to create new and valuable knowle.ge on crucial issues, thus providing new pathways to action for Arctic communities.

关键词： Recent Ventures in Interdisciplinary Arctic Research:The ARCPATH Project

Intracranial pressure is elevated at 24h post-stroke inmice

在线全文

学校读者我要写书评

暂无评论

Neuroprotection 2024年第1期2卷 60-64页

作者： Kirby e.Warren Rebecca j.Hood Fredrick R.Walker Neil j.Spratt School of Biomedical Sciences and Pharmacy University of NewcastleCallaghanAustralia Hunter Medical Research Institute NewLambton HeightsAustralia School of Biomedicine Discipline of Anatomy and PathologyFaculty of Health and Medical SciencesThe University of AdelaideAdelaideAustralia Department of Neurology John Hunter HospitalNewLambton HeightsAustralia

Background:It has long been assumed that post-stroke intracranial pressure(ICP)elevation occurs because of large infarct and edema ***,we have repeatedly shown IcP elevation at 24 h post-stroke in the presence of little to no edema in *** processes are often conserved across species and types of ***,we aimed to determine if an ICP rise occurs at 24 h post-stroke in the presence of small infarct and edema volumes in ***:Mice were randomized by random number table to either photothrombotic stroke or sham surgery(n=15).epidural ICP was recorded using a fiber optic catheter at 1 h post-stroke(baseline)and between 23 and ***:ICP was significantly higher at 24 h compared to baseline in stroke animals(n=6;10.71±6.45mmHg vs.3.74±2.20mmHg,respec-tively;p=0.03).ICP at 24 h was also significantly higher in stroke mice compared to sham(n=6;3.45±1.43mmHg;p=0.02).There was no change in ICP in sham mice(p=0.9).edema volumes in stroke animals were small(0.04±0.04 mm3)and unlikely to have caused significant ICP ***:This study provides evidence of an edema-independent ICP elevation following small ischemic stroke in *** occurrence of this rise supports our findings in other species and suggests it is caused by a previously undescribed mechanism.

关键词： cerebraledema intracranial pressure ischemic stroke

Why ecosystem characteristics predicted from remotely sensed data are unbiased and biased at the same time-and how this affects applications

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Forest ecosystems 2024年第1期11卷 24-31页

作者： goran Ståhl Terje.gobakken Svetlana Saarela Henrik j.Persson Magnus ekstrom Sean P.Healey Zhiqiang Yang johan Holmgren eva Lindbe.g Kenneth Nystrom emanuele Papucci Patrik Ulvdal Hans OleØrka erik Næsset Zhe.gyang Hou Håkan Olsson Ronald e.McRoberts Department of Forest Resource Management Swedish University of Agricultural Sciences90183UmeåSweden Faculty of environmental Sciences and Natural Resource Management Norwegian University of Life SciencesÅsNorway USDA Forest Service Rocky Mountain Research StationOgdenUTUSA The Key Laboratory for Silviculture and Conservation of Ministry of education Beijing Forestry UniversityBeijing100083China Department of Forest Resources University of MinnesotaSt.PaulMNUSA

Remotely sensed data are frequently used for predicting and mapping ecosystem characteristics,and spatially explicit wall-to-wall information is sometimes proposed as the best possible source of information for ***,wall-to-wall information typically relies on model-based prediction,and several features of model-based prediction should be understood before extensively relying on this type of *** such feature is that model-based predictors can be considered both unbiased and biased at the same time,which has important implications in several areas of *** this discussion paper,we first describe the conventional model-unbiasedness paradigm that underpins most prediction techniques using remotely sensed(or other)auxiliary *** this point of view,model-based predictors are typically ***,we show that for specific domains,identified based on their true values,the same model-based predictors can be considered biased,and sometimes severely *** suggest distinguishing between conventional model-bias,defined in the statistical literature as the difference between the expected value of a predictor and the expected value of the quantity being predicted,and design-bias of model-based estimators,defined as the difference between the expected value of a model-based estimator and the true value of the quantity being *** show that model-based estimators(or predictors)are typically design-biased,and that there is a trend in the design-bias from overestimating small true values to underestimating large true ***,we.give examples of applications where this is important to acknowle.ge and to potentially make adjustments to correct for the design-bias *** argue that relying entirely on conventional model-unbiasedness may lead to mistakes in several areas of application that use predictions from remotely sensed data.

关键词： Bias Model-based inference Design-based inference

Thermoluminescence characterization of natural and synthetic irradiated Ce-monazites

在线全文

学校读者我要写书评

暂无评论

journal of Rare earths 2024年第4期42卷 643-650页

作者： V.Correcher C.Boronat j.garcia-guinea j.F.Benavente T.Rivera-Montalvo CIeMAT Av.Complutense 4028040MadridSpain MNCN-CSIC J.Gutierrez Abascal 228006MadridSpain Instituto Politécnico Nacional CICATA-IPNAv.Legaria 694Mexico City11500Mexico

The thermoluminescence(TL)emission of synthetic and natural Ce-monazites was characterized here to determine the potential application in the identification of microscopic defects from a qualitative point of view trying to link each TL peak to a chemical-physical *** kinetic parameters that lead the luminescence processes were calculated by means of variable heating rate and computing glow curve deconvolution methods and allow identifying three.groups of components at~90,130 and 290℃(for the mineral sample)and~90,170,220,270 and 320℃(for the synthetic CePO_(4):Nd_(0.20),La_(0.25)).The main differences appreciated in these complex TL curves are mainly due to(i)the content of impurities(natural sample contains lanthanides as well as U 0.60%and Th 5.22%)and(ii)the degree of crystallinity of the samples which is directly related to the type of impurities(synthetic monazite relies only on Nd and La).The behavior of the dose response in the range of 1-8 gy is similar for both samples;the TL intensity increases linearly as the dose increases without changes in the position of the maxima,denoting first-order kinetic luminescence *** peak could be mostly associated with structural defects(i.e.,phase transitions),chemical reactions(i.e.,Ce3+?Ce4+redox reaction,dehydration or dehydroxylation processes)or intrinsic defects(i.e.,Frenkel defects,ODCs or NBOHCs).

关键词： Thermoluminescence Kineticparameters Phosphate Ce-monazite Defects Rare earths

Organochlorides Mediate Oxidation Reactions Induced by Low Dose Ionizing Radiation

在线全文

学校读者我要写书评

暂无评论

CCS Chemistry 2024年第7期6卷 1712-1720页

作者： junche.g Liu Tobias g.Brevé Bing Xu Peter-Leon Hagedoorn Antonia g.Denkova Rienk eelkema Department of Radiation Science and Technology Delft University of Technology2629 JB Delft Department of Chemical e.gineering Delft University of Technology2629 HZ Delft Department of Biotechnology Delft University of Technology2629 HZ Delft

The controlled release of drugs using local ionizing radiation presents a promising approach for targeted cancer treatment,particularly when applied in concurrent *** these approaches,radiation-generated reactive species often play an important ***,the reactive species that can be used to trigger release have low yield and lack ***,we demonstrate the.generation of highly oxidative species when aqueous solutions containing low concentrations of organochlorides(such as chloroform)are irradiated with ionizing radiation at therapeutically relevant *** reactive species were identified as peroxyl radicals,which formed in a reaction cascade between organochlorides and aqueous *** employed stilbene-based probes to investigate the oxidation process,showing double bond oxidation and *** translate this reactivity into a radiation-sensitive material,we synthesized a micelle-forming amphiphilic block copolymer that has stilbene as the linker between two *** exposure to ionizing radiation,the oxidation of stilbene led to the cleavage of the polymer,which induces the dissociation of the block-copolymer micelles and the release of loaded drugs.

关键词： drug delivery micelles radiation chemistry reactive oxygen species ionizing radiation reaction mechanisms

Study of the Physical and Mechanical Properties of Titanium in Volume by the MeAM Method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Modeling and Numerical Simulation of Material Science 2024年第1期14卷 58-68页

作者： Yahnn j. Mighensle Mimboui Alain S. Dzabana Honguelet Timothée Nsongo Faculty of Science and Technology Marien Ngouabi University Brazzaville Congo Research group on Physical and Chemical Properties of Materials Brazzaville Congo Association Alpha Sciences Beta Technologies Brazzaville Congo geological and Mining Research Centre Brazzaville Congo

In this work we present the results of our study on the physical and mechanical properties of titanium in volume. The work consisted in determining its physical and mechanical properties under different crystallographic structures (HCP, FCC, BCC and SC) using the Modified embedded Atom Method (MeAM) and the MeAM potential of titanium. We used the LAMMPS calculation code, based on classical molecular dynamics, to determine the most stable structure of titanium, which is the hexagonal compact structure (HCP) with crystal parameters a = 2.952 Å and c = 4.821 Å and a cohesion ene.gy of -4.87 eV. This structure is seconded by the cubic centred structure (BCC) with a lattice parameter a = 3.274 Å and a cohesive ene.gy of -4.84 eV. It was shown that titanium can crystallise into a third structure which is the face-centred cubic (FCC) structure with a lattice parameter a = 4.143 Å and a cohesive ene.gy of -4.82 eV. The results obtained in this study were compared with the theoretical results and showed considerable agreement.

关键词： MeAM Potential LAMMPS Code Molecular Dynamics elastic Constants Modules Ovito

《耳鸣患者皮层和皮层下听觉区超高场MRI的研究》摘译

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

听力学及言语疾病杂志 2024年第4期32卷 384-385页

作者：申丽君文之(摘译) 曹永茂(审校) Berlot e Arts R Smit j 武汉大学人民医院耳鼻咽喉头颈外科武汉430060 武汉大学人民医院放射科

耳鸣研究的难点之一在于难以将耳鸣感知与其他合并症进行区分,例如听力损失和声音耐受性降低(DST)经常同时出现。在研究耳鸣动物模型时,区分起来尤其困难。对耳鸣患者研究时往往未能充分控制混杂因素。最近的研究表明,在仔细控制听力损... 详细信息

耳鸣研究的难点之一在于难以将耳鸣感知与其他合并症进行区分,例如听力损失和声音耐受性降低(DST)经常同时出现。在研究耳鸣动物模型时,区分起来尤其困难。对耳鸣患者研究时往往未能充分控制混杂因素。最近的研究表明,在仔细控制听力损失和DST后,耳鸣组和对照组之间先前存在的差异消失了。另一个难点是非侵入性测量技术的空间分辨率有限。为了检测诸如内侧膝状体(MgB)和下丘(IC)等皮层下听觉结构的频率响应特异性,需要高空间分辨率。由于这些结构仅为几立方毫米(例如内侧膝状体为4 mm×5 mm×4.5 mm),常规磁场(3T及以下)下的功能磁共振成像(fMRI)的空间分辨率为2 mm×2 mm×2 mm,无法检查这些微小结构中频率响应的特异性。7T的超高场(UHF)磁共振成像(MRI)提供的灵敏度有足够的分辨率显示微小的听觉皮层下结构的响应,便于详细描述其频率拓扑。本实验研究旨在UHF-MRI应用于耳鸣患者探索耳鸣的机制。

关键词：内侧膝状体立方毫米耳鸣患者混杂因素听力损失皮层下高空间分辨率动物模型