799 research outputs found

    Phenomenological discriminations of the Yukawa interactions in two-Higgs doublet models with Z2Z_2 symmetry

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    There are four types of two-Higgs doublet models under a discrete Z2Z_2 symmetry imposed to avoid tree-level flavour-changing neutral current, i.e. type-I, type-II, type-X and type-Y models. We investigate the possibility to discriminate the four models in the light of the flavour physics data, including BsBˉsB_s-\bar B_s mixing, Bs,dμ+μB_{s,d} \to \mu^+ \mu^-, BτνB\to \tau\nu and BˉXsγ\bar B \to X_s \gamma decays, the recent LHC Higgs data, the direct search for charged Higgs at LEP, and the constraints from perturbative unitarity and vacuum stability. After deriving the combined constraints on the Yukawa interaction parameters, we have shown that the correlation between the mass eigenstate rate asymmetry AΔΓA_{\Delta\Gamma} of Bsμ+μB_{s} \to \mu^+ \mu^- and the ratio R=B(Bsμ+μ)exp/B(Bsμ+μ)SMR={\cal B}(B_{s} \to \mu^+ \mu^-)_{exp}/ {\cal B}(B_{s} \to \mu^+ \mu^-)_{SM} could be sensitive probe to discriminate the four models with future precise measurements of the observables in the Bsμ+μB_{s} \to \mu^+ \mu^- decay at LHCb.Comment: 29 pages, 4 tables, 11 figures. v3: minor corrections included, matches published version in EPJ

    Multiple scattering effects on heavy meson production in p+A collisions at backward rapidity

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    We study the incoherent multiple scattering effects on heavy meson production in the backward rapidity region of p+A collisions within the generalized high-twist factorization formalism. We calculate explicitly the double scattering contributions to the heavy meson differential cross sections by taking into account both initial-state and final-state interactions, and find that these corrections are positive. We further evaluate the nuclear modification factor for muons that come form the semi-leptonic decays of heavy flavor mesons. Phenomenological applications in d+Au collisions at a center-of-mass energy s=200\sqrt{s}=200 GeV at RHIC and in p+Pb collisions at s=5.02\sqrt{s}=5.02 TeV at the LHC are presented. We find that incoherent multiple scattering can describe rather well the observed nuclear enhancement in the intermediate pTp_T region for such reactions.Comment: 10 pages, 6 figures, published version in PL

    MuLTI: Efficient Video-and-Language Understanding with MultiWay-Sampler and Multiple Choice Modeling

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    Video-and-language understanding has a variety of applications in the industry, such as video question answering, text-video retrieval and multi-label classification. Existing video-and-language understanding methods generally adopt heavy multi-modal encoders and feature fusion modules, which consume large amounts of GPU memory. Especially, they have difficulty dealing with dense video frames or long text that are prevalent in industrial applications. In this paper, we propose MuLTI, a highly accurate and memory-efficient video-and-language understanding model that achieves efficient and effective feature fusion through feature sampling and attention modules. Therefore, MuLTI can handle longer sequences with limited GPU memory. Then, we introduce an attention-based adapter to the encoders, which finetunes the shallow features to improve the model's performance with low GPU memory consumption. Finally, to further improve the model's performance, we introduce a new pretraining task named Multiple Choice Modeling to bridge the task gap between pretraining and downstream tasks and enhance the model's ability to align the video and the text. Benefiting from the efficient feature fusion module, the attention-based adapter and the new pretraining task, MuLTI achieves state-of-the-art performance on multiple datasets. Implementation and pretrained models will be released

    Effects of low temperature and drought on the physiological and growth changes in oil palm seedlings

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    Water deficiency and low temperature are two important ecological factors which affect the distribution and cultivation of oil palm. To find out how oil palm adapts to the environmental conditions, the dynamics of a series of important physiological components derived from the leaves of potted oil palm seedlings under drought stress (DS) (water with holding) and low temperature stress (LTS) (10°C) were studied. The results showed that low temperature and water stress inhibited the growth of oil palm seedlings. The relative conductivity, injury index, malondialdehyde (MDA) and proline content in the leaves increased to different degrees with the extension of low temperature and drought stress. Superoxide dismutase (SOD) and peroxidase (POD) activities increased and then decreased gradually with the duration of treatment time. The variations of the earlier mentioned parameters except proline content under low temperature stress were greater than that under drought stress. Thus, oil palm possibly showed different response mechanisms under low temperature and drought stress by mediations of these substances, in order to increase plant defense capability. These data provided the information that was utilized to initiate the breeding programme used to improve drought and cold tolerance in oil palm.Keywords: Oil palm, drought stress, low temperature stress, physiological characteristic

    catena-Poly[[triaqua­(pyridine-κN)nickel(II)]-μ-sulfato-κ2 O:O′]

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    The title compound, [Ni(SO4)(C5H5N)(H2O)3]n, was synthesized by the hydro­thermal reaction of NiSO4·6H2O, pyridine and water. The central NiII atom is coordinated in a distorted octa­hedral environment by a pyridine N atom, three aqua O atoms and two O atoms of bridging sulfate anions, yielding a zigzag chain. A three-dimensional network is generated via complex hydrogen bonds involving the sulfate and aqua ligands and a pyridine C—H group

    2′,10′-Dibromo­spiro­[cylohexane-1,6-di­benzo[d,f][1,3]dioxepine]

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    In the title compound, C18H16Br2O2, the dihedral angle between the aromatic rings is 35.55 (17)° and the cyclohexyl ring adopts a chair-like conformation. In the crystal, molecules are linked by van der Waals forces

    Surgical techniques for early-stage thymoma: Video-assisted thoracoscopic thymectomy versus transsternal thymectomy

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    ObjectiveThe present study compared the outcomes between patients who had undergone video-assisted thoracoscopic surgery (VATS) thymectomy and transsternal (TS) thymectomy for Masaoka stage I and II thymoma.MethodsThe outcomes of 262 patients without myasthenia gravis who had undergone surgery for Masaoka stage I and II thymoma from January 2008 to December 2012 at our center were retrospectively evaluated. The study included 125 patients who had undergone unilateral VATS thymectomy (VATS group) and 137 patients who had undergone TS thymectomy (TS group).ResultsThe VATS group had a shorter operative time than the TS group (170 vs 210 minutes, P < .001). The VATS group also had a smaller intraoperative blood loss (200 vs 450 mL, P < .001), smaller pleural drainage volume in the first 24 hours postoperatively (300 vs 500 mL, P < .0010), shorter postoperative pleural drainage duration (3 vs 5 days, P < .001), and shorter postoperative hospital stay (8 vs 10 days, P < .001). Four patients in the VATS group underwent conversion to open surgery because of injury to the innominate vein. The postoperative complication rate was similar between the 2 groups. One patient in the VATS group developed pleural recurrence, and one in the TS group developed local recurrence.ConclusionsUnilateral VATS thymectomy for Masaoka stage I and II thymoma is technically feasible and safe and is less invasive than TS thymectomy, with a shorter duration of surgery, less intraoperative blood loss, less postoperative pleural drainage, shorter postoperative pleural drainage duration, and shorter postoperative hospital stay. We have concluded that it is preferable to perform VATS thymectomy, although perhaps under certain circumstances sternotomy might be preferred. The oncologic outcomes were comparable between the 2 procedures. Additional follow-up is required to evaluate the long-term outcomes
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