547 research outputs found

    Design and Realization of On-line Enterprise Office Automation System

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    AbstractThis paper discusses the online business office automation system development process, office automation system requirement analysis, system function design, database design and implementation of the system is introduced, the system function and database design and realization of the system. Through the system function data flow analysis, get the logical structure of database system, and on this basis, the physical structure of database to create all kinds of information inquiry, update operation

    Employment hysteresis in the United States during the COVID-19 pandemic

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    In this paper, we test the validity of the employment hysteresis hypothesis. For this purpose, we use daily employment data at the national and state levels in the United States from January 8, 2020, to May 30, 2020. We apply the modified version of the Kapetanios-Shin unit root test, along with finite-sample critical values. We find that the employment hysteresis hypothesis is valid in the United States during the COVID-19 era. The validity of the findings does not change when data at the national and state levels are used. The evidence is also valid when the employment levels for all firms and small firms are considered. The results are also robust to employment levels for workers at different income levels and employment in five different sectors

    Dynamic Task Scheduling in Remote Sensing Data Acquisition from Open-Access Data Using CloudSim

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    With the rapid development of cloud computing and network technologies, large-scale remote sensing data collection tasks are receiving more interest from individuals and small and medium-sized enterprises. Large-scale remote sensing data collection has its challenges, including less available node resources, short collection time, and lower collection efficiency. Moreover, public remote data sources have restrictions on user settings, such as access to IP, frequency, and bandwidth. In order to satisfy users’ demand for accessing public remote sensing data collection nodes and effectively increase the data collection speed, this paper proposes a TSCD-TSA dynamic task scheduling algorithm that combines the BP neural network prediction algorithm with PSO-based task scheduling algorithms. Comparative experiments were carried out using the proposed task scheduling algorithms on an acquisition task using data from Sentinel2. The experimental results show that the MAX-MAX-PSO dynamic task scheduling algorithm has a smaller fitness value and a faster convergence speed

    Expression and evolutionary divergence of the non-conventional olfactory receptor in four species of fig wasp associated with one species of fig

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    <p>Abstract</p> <p>Background</p> <p>The interactions of fig wasps and their host figs provide a model for investigating co-evolution. Fig wasps have specialized morphological characters and lifestyles thought to be adaptations to living in the fig's syconium. Although these aspects of natural history are well documented, the genetic mechanism(s) underlying these changes remain(s) unknown. Fig wasp olfaction is the key to host-specificity. The <it>Or83b</it> gene class, an unusual member of olfactory receptor family, plays a critical role in enabling the function of conventional olfactory receptors. Four <it>Or83b</it> orthologous genes from one pollinator (PFW) (<it>Ceratosolen solmsi</it>) and three non-pollinator fig wasps (NPFWs) (<it>Apocrypta bakeri, Philotrypesis pilosa </it>and <it>Philotrypesis </it>sp.) associated with one species of fig (<it>Ficus hispida</it>) can be used to better understand the molecular mechanism underlying the fig wasp's adaptation to its host. We made a comparison of spatial tissue-specific expression patterns and substitution rates of one orthologous gene in these fig wasps and sought evidence for selection pressures.</p> <p>Results</p> <p>A newly identified <it>Or83b </it>orthologous gene was named <it>Or2</it>. Expressions of <it>Or2 </it>were restricted to the heads of all wingless male fig wasps, which usually live in the dark cavity of a fig throughout their life cycle. However, expressions were widely detected in the antennae, legs and abdomens of all female fig wasps that fly from one fig to another for oviposition, and secondarily pollination. Weak expression was also observed in the thorax of PFWs. Compared with NPFWs, the <it>Or2 </it>gene in <it>C. solmsi </it>had an elevated rate of substitutions and lower codon usage. Analyses using Tajima's <it>D</it>, Fu and Li's <it>D* </it>and <it>F* </it>tests indicated a non-neutral pattern of nucleotide variation in all fig wasps. Unlike in NPFWs, this non-neutral pattern was also observed for synonymous sites of <it>Or2 </it>within PFWs.</p> <p>Conclusion</p> <p>The sex- and species-specific expression patterns of <it>Or2 </it>genes detected beyond the known primary olfactory tissues indicates the location of cryptic olfactory inputs. The specialized ecological niche of these wasps explains the unique habits and adaptive evolution of <it>Or2 </it>genes. The <it>Or2 </it>gene in <it>C. solmsi </it>is evolving very rapidly. Negative deviation from the neutral model of evolution reflects possible selection pressures acting on <it>Or2 </it>sequences of fig wasp, particularly on PFWs who are more host-specific to figs.</p
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