9,363 research outputs found
Doubly Heavy Baryon Production at A High Luminosity Collider
Within the framework of nonrelativistic QCD, we make a detailed discussion on
the doubly heavy baryon production through the annihilation channel,
, at a high luminosity collider. Here
stands for the heavy or quark. In addition to the
channel through the usually considered diquark state
, contributions from the channels through
other same important diquark states such as have
also been discussed. Uncertainties for the total cross sections are predicted
by taking GeV and GeV. At a super
-factory running around the mass and with a high luminosity up to
, we estimate
that about events,
events and events can be
generated in one operation year. Such a -factory, thus, will provide a good
platform for studying the doubly heavy baryons in comparable to the CERN large
hadronic collider.Comment: 9 pages, 4 figures. To be published in Phys.Rev.
The Study on In-City Capacity Affected by Pedestrian Crossing
Currently, the urban road traffic congestion is serious and the traffic accident is happening at a high frequency; thus it has not satisfied the travel needs of security and affects the quality of urban trips. In order to effectively relieve the confliction of people and motor vehicle, to make sure of the safety of pedestrians crossing the road, and to improve the capacity of urban roads, this passage focuses on studying the influence of pedestrians crossing the roads on the capacity of urban roads in three pedestrian crossing approaches including freely crossing the street, uncontrolled crossing of the pedestrian crosswalk, and controlled crossing of the pedestrian crosswalk. Firstly, it confirms the general formula of the road capacity when pedestrians are crossing the road based on three preassumptions, combined with the survey data, and then constructs the empirical mathematical model of pedestrian crossing on the capacity impact. Lastly, it takes the step of case calculation and simulation evaluation and calculates errors between them, finding that the error between the model calculation and software simulation is small. The efficiency of the model is validated and improved
Hepatitis B virus reactivation in breast cancer patients undergoing chemotherapy: A review and meta-analysis of prophylaxis management
Hepatitis B virus (HBV) reactivation during or after chemotherapy in patients with breast cancer has become a remarkable clinical problem. Prophylactic nucleos(t)ide analogues (NAs) are recommended for patients with breast cancer who are hepatitis B surface antigen (HBsAg) positive before chemotherapy. We performed an up-to-date meta-analysis to compare the efficacy of prophylactic lamivudine use with nonprophylaxis in HBsAg-positive breast cancer patients undergoing chemotherapy. PubMed, the Cochrane Library and China National Knowledge Infrastructure (CNKI) databases were searched for relevant articles until June 2016. Eligible articles comparing the efficacy of prophylactic lamivudine use with nonprophylaxis in HBsAg-positive breast cancer patients undergoing chemotherapy were identified. Eight studies which had enrolled 709 HBsAg-positive breast cancer patients undergoing chemotherapy were analysed. Lamivudine prophylaxis significantly reduced the rates of chemotherapy-associated hepatitis B flares in chronic hepatitis B in breast cancer compared with patients with nonprophylaxis (odds ratio [OR]=0.15, 95% confidence interval [CI]: 0.07-0.35, P<.00001). Chemotherapy disruption rates attributed to HBV reactivation in the prophylaxis groups were significantly lower than the nonprophylaxis groups (OR=0.17, 95% CI: 0.07-0.43, P=.0002). Patients with lamivudine prophylaxis had a higher risk for tyrosine-methionine-aspartate-aspartate (YMDD) motif mutations than patients with nonprophylaxis (OR=6.33, 95% CI: 1.01-39.60, P=.05). Prophylactic antiviral therapy management is necessary for HBsAg-positive breast cancer patients undergoing chemotherapy, in spite of high correlation with lamivudine-resistant HBV variants with YMDD motif mutations
On the number of founding germ cells in humans
BACKGROUND: The number of founding germ cells (FGCs) in mammals is of fundamental significance to the fidelity of gene transmission between generations, but estimates from various methods vary widely. In this paper we obtain a new estimate for the value in humans by using a mathematical model of germ cell development that depends on available oocyte counts for adult women. RESULTS: The germline-development model derives from the assumption that oogonial proliferation in the embryonic stage starts with a founding cells at t = 0 and that the subsequent proliferation can be defined as a simple stochastic birth process. It follows that the population size X(t) at the end of germline expansion (around the 5(th )month of pregnancy in humans; t = 0.42 years) is a random variable with a negative binomial distribution. A formula based on the expectation and variance of this random variable yields a moment-based estimate of a that is insensitive to the progressive reduction in oocyte numbers due to their utilization and apoptosis at later stages of life. In addition, we describe an algorithm for computing the maximum likelihood estimation of the FGC population size (a), as well as the rates of oogonial division and loss to apoptosis. Utilizing both of these approaches to evaluate available oocyte-counting data, we have obtained an estimate of a = 2 – 3 for Homo sapiens. CONCLUSION: The estimated number of founding germ cells in humans corresponds well with values previously derived from chimerical or mosaic mouse data. These findings suggest that the large variation in oocyte numbers between individual women is consistent with a smaller founding germ cell population size than has been estimated by cytological analyses
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