252 research outputs found
Study on the Departure Process of Discrete-Time Geo
This paper presents an analysis of the departure process of a discrete-time Geo/G/1 queue
with randomized vacations. By using probability decomposition techniques and renewal process, the
expression of expected number of departures during time interval (0+,n+] is derived. The relation
among departure process, server state process, and service renewal process is obtained. The relation
displays the decomposition characteristic of the departure process. Furthermore, the approximate
expansion of the expected number of departures is gained. Since the departure process also often
corresponds to an arrival process for a downstream queue in queueing network, it is hoped that the
results obtained in this paper may provide useful information for queueing network
Anomalous tensile strength and thermal expansion, and low thermal conductivity in wide band gap boron monoxide monolayer
Most recently the formation of boron monoxide (BO) in the two-dimensional
(2D) form has been confirmed experimentally (J. Am. Chem. Soc. 2023, 145,
14660). Motivated by the aforementioned finding, herein we theoretically
explore the key physical properties of the single-layer and suspended BO.
Density functional theory (DFT) results reveal that BO monolayer yields a large
indirect band gap of 3.78 (2.18) eV on the basis of HSE06(PBE) functional.
Ab-initio molecular dynamics results reveal the remarkable thermal stability of
the BO monolayer at 1000 K. The thermal and mechanical properties at room
temperature are furthermore investigated using a machine learning interatomic
potential (MLIP). The developed MLIP-based model close to the ground state
could very precisely reproduce the DFT predictions for the mechanical
properties of the BO monolayer. The elastic modulus, tensile strength and
lattice thermal conductivity of the BO monolayer at room temperature are
predicted to be 107 GPa, 25 GPa and 5.6 W/mK, respectively. At the room
temperature the BO monolayer is noticeably predicted to yield an ultrahigh
negative thermal expansion coefficient, by almost 17 folds larger than that of
the single-layer graphene. The presented results reveal the large indirect
electronic band gap, decent thermal and dynamical stability, anomalously low
elastic modulus to tensile strength ratio, ultrahigh negative thermal expansion
coefficients and low lattice thermal conductivity of the BO monolayer
Channels coordination game model based on result fairness preference and reciprocal fairness preference: a behavior game forecasting and analysis method,β
In a distribution channel, channel members are not always self-interested, but altruistic in some conditions. Based on this assumption, this paper adopts a behavior game method to analyze and forecast channel members' decision behavior based on result fairness preference and reciprocal fairness preference by embedding a fair preference theory in channel research of coordination. The behavior game forecasts that a channel can achieve coordination if channel members consider behavior elements. Using the behavior game theory model we established, we can prove that if retailers only consider the result fairness preference and they are not jealous of manufacturers' benefit, manufacturers will be more friendly to retailers. In such case, the total utility of the channel is higher compared with that of self-interest channel, and the utility of channel members is Pareto improved. If both manufactures and retailers consider reciprocal fairness preference, the manufacturers will give a lower wholesale price to the retailers. In return, the retailers will also reduce retail prices. Therefore, the total utility of the channels will not be less than the total utility of the channel coordination, as long as the reciprocity wholesale prices meet certain conditions
Genome-Wide Profiling of Cardinium-Responsive MicroRNAs in the Exotic Whitefly, Bemisia tabaci (Gennadius) Biotype Q
Although the bacterial symbiont Cardinium has profound effects on the ecological adaptation of its host, the whitefly Bemisia tabaci (Gennadius) biotype Q (hereafter referred to as B. tabaci Q), the molecular mechanism underlying interactions between these two organisms is not yet fully understood. In this study, sRNA libraries were constructed, amplified, and sequenced for Cardinium-infected (C+) and uninfected (Cββ) B. tabaci Q with identical genetic backgrounds. Subsequently, the genes targeted by the differentially expressed miRNAs were predicted by integrating the B. tabaci Q genome data. A total of 125 known and 100 novel miRNAs were identified, among which 23 significant differentially expressed miRNAs were identified in both libraries. It is noteworthy that an analysis of target genes showed that Cardinium-responsive miRNA-regulated genes were functional in apoptosis, reproduction, development, immune response, thermotolerance and insecticide resistance. GO and KEGG pathway analysis revealed that some miRNA-target genes are closely associated with energy metabolism. A major finding of this study was the identification of several miRNAs that may be involved in physiological processes in response to environmental stress, i.e., insecticides and high temperatures. This information will provide a foundation to help further elucidate the functions of Cardinium in B. tabaci Q
Association between childhood sexual abuse and early sexual debut among Chinese adolescents: The role of sexual and reproductive health education
BackgroundDespite accumulating evidence of the long-term impacts of childhood sexual abuse (CSA), few studies have investigated the association between CSA and early sexual debut among adolescents. In this study, we examine the relationship between CSA and early initiation of sexual intercourse among Chinese youth, and the role of school-based sex education in this association, based on a nationally representative survey.MethodsData were collected from the Survey of Youth Access to Reproductive Health in China (YARHC) conducted in 2009. Multivariable logistic regression models were used to investigate the association between CSA experience and early sexual debut, and the interaction terms between sexual and reproductive health education and CSA were included to examine the role of education in the association between CSA and early sexual debut.ResultsAmong 4,907 sexually experienced youth, 1,062 (21.6%) made their early sexual debut. After adjusting for sociodemographic characteristics, it was found that CSA experience was significantly associated with early sexual debut, with an adjusted odds ratio of 3.13 (95% CI: 1.67β5.87). Receiving any type of sexuality education (reproductive health, sexually transmitted disease (STD) and HIV prevention, or contraception use) was not associated with a decreased risk of early sexual debut.ConclusionOur results indicate a greater risk of early sexual debut among Chinese adolescents with a history of CSA, and only 46.7% sexually experienced youth had received prior sex education, which suggested an inadequacy of school-based sexuality education. To reduce this risk, targeted intervention with timely and adequate sexuality education for both early starters of sexual intercourse and CSA victims is warranted in China
Puerarin Induces Mitochondria-Dependent Apoptosis in Hypoxic Human Pulmonary Arterial Smooth Muscle Cells
Background: Pulmonary vascular medial hypertrophy in hypoxic pulmonary arterial hypertension (PAH) is caused in part by decreased apoptosis in pulmonary artery smooth muscle cells (PASMCs). Puerarin, an isoflavone purified from the Chinese medicinal herb kudzu, ameliorates chronic hypoxic PAH in animal models. Here we investigated the effects of puerarin on apoptosis of hypoxic human PASMCs (HPASMCs), and to determine the possible underlying mechanisms. Methodology/Principal Findings: HPASMCs were cultured for 24 h in normoxia or hypoxia (5 % O2) conditions with and without puerarin. Cell number and viability were determined with a hemacytometer or a cell counting kit. Apoptosis was detected with a TUNEL test, rhodamine-123 (R-123) fluorescence, a colorimetric assay, western blots, immunohistochemical staining and RT-PCR. Hypoxia inhibited mitochondria-dependent apoptosis and promoted HPASMC growth. In contrast, after puerarin (50 mM or more) intervention, cell growth was inhibited and apoptosis was observed. Puerarin-induced apoptosis in hypoxic HPASMCs was accompanied by reduced mitochondrial membrane potential, cytochrome c release from the mitochondria, caspase-9 activation, and Bcl-2 down-regulation with concurrent Bax up-regulation. Conclusions/Significance: Puerarin promoted apoptosis in hypoxic HPASMCs by acting on the mitochondria-dependent pathway. These results suggest a new mechanism of puerarin relevant to the management of clinical hypoxic pulmonar
Rapid Estimation of Binding Activity of Influenza Virus Hemagglutinin to Human and Avian Receptors
A critical step for avian influenza viruses to infect human hosts and cause epidemics or pandemics is acquisition of the ability of the viral hemagglutinin (HA) to bind to human receptors. However, current global influenza surveillance does not monitor HA binding specificity due to a lack of rapid and reliable assays. Here we report a computational method that uses an effective scoring function to quantify HA-receptor binding activities with high accuracy and speed. Application of this method reveals receptor specificity changes and its temporal relationship with antigenicity changes during the evolution of human H3N2 viruses. The method predicts that two amino acid differences at 222 and 225 between HAs of A/Fujian/411/02 and A/Panama/2007/99 viruses account for their differences in binding to both avian and human receptors; this prediction was verified experimentally. The new computational method could provide an urgently needed tool for rapid and large-scale analysis of HA receptor specificities for global influenza surveillance.National Key Project (2008ZX10004-013)National Institutes of Health (U.S.) (grant AI07443)Singapore-MIT Alliance for Research and TechnologyMassachusetts Institute of Technology. International Science and Technology Initiatives Global Seed FundNational Basic Research Program (973 Program) (2009CB918503)National Basic Research Program (973 Program) (2006CB911002
Converse Flexoelectricity of Low-Dimensional Bismuth Selenite (Bi2Se3) Revealed by Piezoresponse Force Microscopy (PFM)
Many kinds of two-dimensional (2D) van der Waals (vdW) have been demonstrated
to exhibit electromechanical coupling effects, which makes them promising
candidates for next-generation devices, such as piezotronics and
nanogenerators. Recently, flexoelectricity was found to account for the
out-of-plane electromechanical coupling in many 2D transition metal
dichalcogenides (TMDs) who only exhibit in-plane piezoelectricity. However, low
dimensional vdW three-dimensional (3D) topological insulators (TIs) have been
overlooked regarding their electromechanical properties. In this study, for the
first time, we experimentally investigate the electromechanical coupling of low
dimensional 3D TIs with a centrosymmetric crystal structure, where a binary
compound, bismuth selenite (Bi2Se3), is taken as an example. The results of
piezoresponse force microscope (PFM) tests on the Bi2Se3 nanoflakes show that
the material exhibits both out-of-plane and in-plane electromechanical
responses. The Bi2Se3 nanoflake with a thickness of 37 nm possesses an
effective out-of-plane piezoelectric coefficient of ~0.65 pm V-1. With careful
analyses, the electromechanical responses are verified to arise from the
converse flexoelectricity. The measured effective out-of-plane piezoelectric
coefficient is mainly contributed by flexoelectric coefficient, {\mu}_39, which
is estimated to be approximately 0.13 nC m-1. However, it is rather difficult
to obtain the in-plane component of the flexoelectric tensor from the in-plane
PFM measurements since the direction of the in-plane stress is always not
normal to the AFM cantilever axis. The results provide useful guidance for
understanding the flexoelectric effect of low dimensional vdW materials with
centrosymmetric crystal structures. Moreover, the work can pave to way to
explore the electromechanical devices based on the flexoelectricity of vdW TIs.Comment: 6 figure
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