检索结果-南通市图书馆

Optimal Control of Service Rates of Discrete-Time(s,Q)Queueing-Inventory Systems with Finite Buffer

在线全文

学校读者我要写书评

暂无评论

journal of Systems Science and Systems Engineering 2024年第3期33卷 261-280页

作者： L.Iniya B.Sivakumar g.Arivarignan School of Mathematics Madurai Kamaraj UniversityMaduraiTamilnaduIndia Department of Statistics Manonmaniam Sundaranar UniversityTirunelveliTamilnaduIndia

This article,we develop an optimal policy to control the service rate of a discrete time queueing-inventory system with finite *** customers arrive according to a Bernoulli process and the service time for the customers are *** the buffer size attains its maximum,any arriving new customers are considered to be *** customers are served one by one according to FCFS rule and each customers request random number of *** inventory is replenished according to a(s,Q)inventory policy with geometric lead *** main objectives of this article are to determine the service rates to be employed at each slot so that the long run expected cost rate is minimized for fixed inventory level and fixed buffer size and to minimize the expected waiting time for a fixed inventory level and fixed buffer *** problems are modelled as Markov decision *** establish the existence of a stationary policy and employ linear programming method to find the optimal service *** provide some numerical examples to illustrate the behaviour of the model.

关键词： Queueing-inventory system discrete time batch demand-Markov decision process

The great catastrophe: causes of the Permo-Triassic marine mass extinction

维普期刊数据库评论

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 37-50页

作者： Paul B.Wignall David P.g.Bond School of Earth & Environment University of Leeds School of Environmental Sciences University of Hull

The marine losses during the Permo-Triassic mass extinction were the worst ever experienced. All groups were badly affected, especially amongst the benthos(e.g. brachiopods, corals, bryozoans, foraminifers,ostracods). Planktonic populations underwent a fundamental change with eukaryotic algae being replaced by nitrogen-fixing bacteria, green-sulphur bacteria, sulphate-reducing bacteria and prasinophytes. Detailed studies of boundary sections, especially those in South China, have resolved the crisis to a ～55 kyr interval straddling the Permo-Triassic boundary. Many of the losses occur at the beginning and end of this interval painting a picture of a two-phase extinction. Improved knowledge of the extinction has been supported by numerous geochemical studies that allow diverse proposed extinction mechanisms to be studied. A transition from oxygenated to anoxic-euxinic conditions is seen in most sections globally, although the intensity and timing shows regional variability. Decreased ocean ventilation coincides with rapidly rising temperatures and many extinction scenarios attribute the losses to both anoxia and high *** kill mechanisms include ocean acidification for which there is conflicting support from geochemical proxies and, even less likely, siltation(burial under a massive influx of terrigenous sediment) which lacks substantive sedimentological evidence. The ultimate driver of the catastrophic changes at the end of the Permian was likely Siberian Trap eruptions and their associated carbon dioxide emissions with consequences such as warming, ocean stagnation and acidification. Volcanic winter episodes stemming from Siberian volcanism have also been linked to the crisis, but the short-term nature of these episodes(g evidence for rapid warming during the crisis makes this an unlikely cause. Finally, whilst the extinction is well studied in equatorial latitudes, a different history is found in northern Boreal latitudes

关键词： ocean anoxia ocean acidification siltation productivity collapse volcanic winter

Neutrophils in the tumor microenvironment-when a company becomes a crowd

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Cellular & Molecular Immunology 2024年第4期21卷 313-314页

作者： Zvi g.Fridlender Zvi granot Faculty of Medicine Hebrew University of JerusalemJerusalemIsrael Institute of Pulmonary Medicine Hadassah-Hebrew University Medical Center91120 JerusalemIsrael Department of Developmental Biology and Cancer Research Institute for Medical Research Israel CanadaFaculty of MedicineHebrew University91120 JerusalemIsrael

Traditionally,neutrophils are perceived as terminally differentiated cells with defined functions and limited *** is commonly believed that circulating,marginating and tissue-infiltrating neutrophils belong to the same homogeneous population and are capable of switching between these *** research has stagnated since the early 1980s,maintaining a narrow and simplistic view of their capabilities.

关键词： narrow infiltrating differentiated

Analysis of ancient mass extinction recoveries in marine environments: generating strategies for managing outcomes of the current mass extinction

维普期刊数据库评论

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 8-10页

作者： David j.Bottjer Department of Earth Sciences University of Southern California

The defining feature of a mass extinction and its associated recovery is the global amount of extinction that occurred[1]. However, there is finer-scale detail to the story, as seen in the ongoing modern mass extinction(the sixth mass extinction), which exhibits variable effects among marine ecosystems and environments, and hence geographic areas [1].

关键词：

global weirding at mass extinction horizons

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2024年第1期11卷 10-12页

作者： gregory j.Retallack Department of Earth Sciences University of Oregon

A strong motivation for studying mass extinctions is understanding how current climatic and biodiversity crises will affect creatures living on land such as ourselves. Perhaps the question is: how bad can it get? In that case, terrestrial Permian-Triassic mass extinctions are an irresistible worst-case scenario [1].

关键词：

Transmission of amyloid-βpathology in humans:a perspective on clinical evidence

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第2期19卷 390-392页

作者： Celso S.g.Catumbela Rodrigo Morales Department of Neurology McGovern Medical SchoolThe University of Texas Health Science Center at HoustonHoustonTXUSA Centro Integrativo de Biologia y Quimica Aplicada(CIBQA) Universidad Bernardo O’HigginsSantiagoChile

Transmission of misfolded amyloid-β(Aβ)aggregates between human subjects:Protein misfolding disorders are a family of diseases characterized by the accumulation of misfolded protein *** proteinaceous structures,also known as amyloids,are key drivers of fatal neurodegenerative disorders such as prion diseases,Alzheimer’s disease(AD),Parkinson’s disease,and others.

关键词： amyloid diseases Aβ

Features of sampling stream sediments of large river valleys under cryolithogenesis conditions in the Balygychan-Sugoy trough,North-East of Russia

在线全文

学校读者我要写书评

暂无评论

Acta geochimica 2024年第4期43卷 638-660页

作者： Artem S.Makshakov Raisa g.Kravtsova A.P.Vinogradov Institute of geochemistry Siberian Branch of the Russian Academy of SciencesFavorskiy Str 1AIrkutskRussia 664033

Comprehensive research has been implemented to raise the efficiency of the geochemical survey of stream sediments(SSs)that formed under the cryolithogenesis *** authors analysed the composition,structure and specific features of the formation of exogenous anomalous geochemical fields(AgFs)identified through SSs of large river valleys of IV *** our case,these were the valleys of Maly Ken,Ken and Tap *** rivers are located in the central and southern parts of the Balygychan-Sugoy trough enclosed in the Magadan region,North-East of *** authors proposed a new technique to sample loose alluvium of SSs in the large river valleys along the *** profiles were located across the *** AgFs of Au,Ag,Pb,Zn,Sn,Bi,Mo and W were *** between elements have been *** elements are the main indicator elements of Au-Ag,Ag-Pb,Sn-Ag,Mo-W and Sn-W mineralization occurring on the sites under *** results obtained were compared with the results of geochemical surveys of *** is concluded that the AgFs recognized along the profiles reflect the composition and structure of eroded and drained ore zones,uncover completely and precisely the pattern of element distribution in loose sediments of large water *** alluvium fractiongnificant in a practical sense,as it concentrated numerous ore *** of this fraction in the river valleys of IV order does not cause any difficulty,for this kind of material is *** developed technique of alluvium sampling within large river valleys is efficient in searching for diverse mineralization at all stages of prognostic *** is applicable for geochemical survey of SSs performed at different scales both in the North-East of Russia,as well as other regions with similar climatic conditions,where the SSs are formed under the cryolithogenesis conditions.

关键词： Stream sediments Large river valleys geochemical fields Mineralization Indicator elements geochemical survey

Resident immune responses to spinal cord injury:role of astrocytes and microglia

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第8期19卷 1678-1685页

作者： Sydney Brockie Cindy Zhou Michael g.Fehlings Division of genetics and Development Krembil Research InstituteUniversity Health NetworkTorontoONCanada Institute of Medical Science University of TorontoTorontoONCanada Division of Neurosurgery and Spine Program Department of SurgeryUniversity of TorontoTorontoONCanada

Spinal cord injury can be traumatic or non-traumatic in origin,with the latter rising in incidence and prevalence with the aging demographics of our *** r,as the global population ages,individuals with co-existent degenerative spinal pathology comprise a growing number of traumatic spinal cord injury cases,especially involving the cervical spinal *** makes recovery and treatment approaches particula rly challenging as age and comorbidities may limit regenerative *** these reasons,it is critical to better understand the complex milieu of spinal cord injury lesion pathobiology and the ensuing inflammatory *** review discusses microglia-specific purinergic and cytokine signaling pathways,as well as microglial modulation of synaptic stability and plasticity after ***,we evaluate the role of astrocytes in neurotransmission and calcium signaling,as well as their border-forming response to neural *** the inflammatory and reparative roles of these cells have eluded our complete understanding and remain key therapeutic targets due to their extensive structural and functional roles in the nervous *** advances have shed light on the roles of glia in neurotransmission and reparative injury responses that will change how interventions are *** key processes and existing knowledge gaps will allow future research to effectively target these cells and harness their regenerative potential.

关键词： astrocytes glial signaling microglia spinal cord injury synaptic transmission

Coupled Inversion of Pressure and Tiltmeter Data for Mapping Hydraulic Fracture geometry

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2024年第3期37卷 396-405页

作者： Zuorong Chen Xiaofang jiang Zhejun Pan Robert g.jeffrey National Key Laboratory of Continental Shale Oil Northeast Petroleum UniversityDaqing163318China SCT Operation Pty.Ltd. PO Box 824WollongongNSW2520Australia

Pressure and tilt data are jointly inverted to simultaneously map the orientation and dimensions of a hydraulic *** deformation induced by a fracture under internal pressure is modeled using the distributed dislocation *** planar fracture is represented by four quarter ellipses,joined at the center and sharing *** configuration provides a straightforward model for characterizing asymmetric fracture *** inverse problem of mapping the fracture geometry is formulated using the Bayesian probabilistic method,combining the a priori information on the fracture model with updated information from pressure and tilt *** the nonlinear inverse problem is achieved by pseudo-randomly sampling the posterior probability distribution through the Markov chain Monte Carlo *** resulting posterior probability distribution is then explored to assess uncertainty,resolution,and correlation between model *** experiments are conducted to verify the accuracy and validity of the proposed analysis method in mapping the fracture geometry using synthetic pressure and tilt data.

关键词： Hydraulic fracture mapping Coupled inversion Tilt Treating pressure