63 research outputs found
Probing the topcolor-assisted technicolor model via the single t-quark production at Hadron colliders
In this paper, we systematically study the contribution of the TC2 model to
the single t-quark production at the Hadron colliders, specially at the LHC.
The TC2 model can contribute to the cross section of the single t-quark
production in two different ways. First, the existence of the top-pions and
top-higgs can modify the coupling via their loop contributions, and such
modification can cause the correction to the cross sections of all three
production modes. Our study shows that this kind of correction is negative and
very small in all cases. Thus it is difficult to observe such correction even
at the LHC. On the other hand, there exist the tree-level FC couplings in the
TC2 model which can also contribute to the cross sections of the and
production processes. The resonant effect can greatly enhance the
cross sections of the and productions. The first evidence of
the single t-quark production has been reported by the collaboration and
the measured cross section for the single t-quark production of
is compatible at the 10% level with the
standard model prediction. Because the light top-pion can make great
contribution to the production, the top-pion mass should be very
large in order to make the predicted cross section in the TC2 model be
consistent with the Tevatron experiments. More detailed information about the
top-pion mass and the FC couplings in the TC2 model should be obtained with the
running of the LHC.Comment: 30 pages, 3 tables, 10 figure
Modeling Financial Time Series Based on a Market Microstructure Model with Leverage Effect
The basic market microstructure model specifies that the price/return innovation and the volatility innovation are independent Gaussian white noise processes. However, the financial leverage effect has been found to be statistically significant in many financial time series. In this paper, a novel market microstructure model with leverage effects is proposed. The model specification assumed a negative correlation in the errors between the price/return innovation and the volatility innovation. With the new representations, a theoretical explanation of leverage effect is provided. Simulated data and daily stock market indices (Shanghai composite index, Shenzhen component index, and Standard and Poorβs 500 Composite index) via Bayesian Markov Chain Monte Carlo (MCMC) method are used to estimate the leverage market microstructure model. The results verify the effectiveness of the model and its estimation approach proposed in the paper and also indicate that the stock markets have strong leverage effects. Compared with the classical leverage stochastic volatility (SV) model in terms of DIC (Deviance Information Criterion), the leverage market microstructure model fits the data better
Novel syntheses of aryl quinoxaline C-nucleoside analogs by mild and efficient three-component sequential reactions
National Natural Science Foundation of China [21272219, 20972142]; State Key Laboratory of Bio-organic and Natural Products Chemistry, CAS [08417]Novel syntheses of C-nucleoside analogs with aryl quinoxalines as nucleobase surrogates have been accomplished by mild and efficient three-component sequential reactions in high yields with a wide scope of substrates. The mechanism was clarified by isolation of novel sugar 1,2-diketone derived from oxidation of the corresponding alkyne
The flavor-changing single-top quark production in the littlest Higgs model with T parity at the LHC
The littlest Higgs model with discrete symmetry named "T-parity"(LHT) is an
interesting new physics model which does not suffer strong constraints from
electroweak precision data. One of the important features of the LHT model is
the existence of new source of FC interactions between the SM fermions and the
mirror fermions. These FC interactions can make significant loop-level
contributions to the couplings , and furthermore enhance the cross
sections of the FC single-top quark production processes. In this paper, we
study some FC single-top quark production processes, and
, at the LHC in the LHT model. We find that the cross sections of
these processes are strongly depended on the mirror quark masses. The processes
and have large cross sections with heavy mirror
quarks. The observation of these FC processes at the LHC is certainly the clue
of new physics, and further precise measurements of the cross scetions can
provide useful information about the free parameters in the LHT model,
specially about the mirror quark masses.Comment: 20 pages, 5 figure
Antibody Dynamics of 2009 Influenza A (H1N1) Virus in Infected Patients and Vaccinated People in China
BACKGROUND: To evaluate the risk of the recurrence and the efficiency of the vaccination, we followed-up antibody responses in patients with the 2009 pandemic H1N1 influenza and persons who received the pandemic H1N1 vaccine in Guangzhou China. METHODS: We collected serum samples from 129 patients and 86 vaccinated persons at day 0, 15, 30, 180 after the disease onset or the vaccination, respectively. Antibody titers in these serum samples were determined by haemagglutination inhibition (HI) assay using a local isolated virus strain A/Guangdong Liwan/SWL1538/2009(H1N1). RESULTS: HI antibody positive rate of the patients increased significantly from 0% to 60% at day 15 (Ο(2)β=β78, P<0.001) and 100% at day 30 (Ο(2)β=β23, P<0.001), but decreased significantly to 52% at day 180 (Ο(2)β=β38, P<0.001), while that of vaccinated subjects increased from 0% to 78% at day 15 (Ο(2)β=β110, P<0.001) and 81% at day 30 (Ο(2)β=β0.32, Pβ=β0.57), but decreased significantly to 34% at day 180 (Ο(2)β=β39, P<0.001). Geometric mean titers (GMT) of HI antibodies in positive samples from the patients did not change significantly between day 15 and day 30 (Tβ=β0.92, Pβ=β0.36), but it decreased significantly from 80 at day 30 to 52 at day 180 (Tβ=β4.5, P<0.001). GMT of vaccinated persons increased significantly from 100 at day 15 to 193 at day 30 (Tβ=β4.5, P<0.001), but deceased significantly to 74 at day 180 (Tβ=β5.1, P<0.001). Compared to the patients, the vaccinated subjects showed lower seroconversion rate (Ο(2)β=β11, P<0.001; Ο(2)β=β5.9, Pβ=β0.015), but higher GMT (Tβ=β6.0, P<0.001; Tβ=β3.6, Pβ=β0.001) at day 30 and day 180, respectively. CONCLUSION: Vaccination of 2009 influenza A (H1N1) was effective. However, about half or more recovered patients and vaccinated persons might have lost sufficient immunity against the recurrence of the viral infection after half a year. Vaccination or re-vaccination may be necessary for prevention of the recurrence
Optimized gene editing technology for Drosophila melanogaster using germ line-specific Cas9
The ability to engineer genomes in a specific, systematic, and cost-effective way is critical for functional genomic studies. Recent advances using the CRISPR-associated single-guide RNA system (Cas9/sgRNA) illustrate the potential of this simple system for genome engineering in a number of organisms. Here we report an effective and inexpensive method for genome DNA editing in Drosophila melanogaster whereby plasmid DNAs encoding short sgRNAs under the control of the U6b promoter are injected into transgenic flies in which Cas9 is specifically expressed in the germ line via the nanos promoter. We evaluate the off-targets associated with the method and establish a Web-based resource, along with a searchable, genome-wide database of predicted sgRNAs appropriate for genome engineering in flies. Finally, we discuss the advantages of our method in comparison with other recently published approaches.Multidisciplinary SciencesSCI(E)46ARTICLE4719012-1901711
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