2,060 research outputs found

    Feynman Rules in the Type III Natural Flavour-Conserving Two-Higgs Doublet Model

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    We consider a two Higgs-doublet model with S3S_3 symmetry, which implies a π2\pi \over 2 rather than 0 relative phase between the vacuum expectation values and and . The corresponding Feynman rules are derived accordingly and the transformation of the Higgs fields from the weak to the mass eigenstates includes not only an angle rotation but also a phase transformation. In this model, both doublets couple to the same type of fermions and the flavour-changing neutral currents are naturally suppressed. We also demonstrate that the Type III natural flavour-conserving model is valid at tree-level even when an explicit S3S_3 symmetry breaking perturbation is introduced to get a reasonable CKM matrix. In the special case β=α\beta = \alpha, as the ratio tanβ=v2v1\tan\beta = {v_2 \over v_1} runs from 0 to \infty, the dominant Yukawa coupling will change from the first two generations to the third generation. In the Feynman rules, we also find that the charged Higgs currents are explicitly left-right asymmetric. The ratios between the left- and right-handed currents for the quarks in the same generations are estimated.Comment: 16 pages (figures not included), NCKU-HEP/93-1

    Discovery of Novel Materials with Broad Resistance to Bacterial Attachment Using Combinatorial Polymer Microarrays

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    A new class of bacteria-attachment-resistant materials is discovered using a multi-generation polymer microarray methodology that reduces bacterial attachment by up to 99.3% compared with a leading commercially available silver hydrogel anti-bacterial material. The coverage of three bacterial species, Pseudomonas aeruginosa, Staphylococcus aureus, and uropathogenic Escherichia coli is assessed.National Institutes of Health (U.S.) (Grant R01 DE016516

    Influence of shear flow on vesicles near a wall: a numerical study

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    We describe the dynamics of three-dimensional fluid vesicles in steady shear flow in the vicinity of a wall. This is analyzed numerically at low Reynolds numbers using a boundary element method. The area-incompressible vesicle exhibits bending elasticity. Forces due to adhesion or gravity oppose the hydrodynamic lift force driving the vesicle away from a wall. We investigate three cases. First, a neutrally buoyant vesicle is placed in the vicinity of a wall which acts only as a geometrical constraint. We find that the lift velocity is linearly proportional to shear rate and decreases with increasing distance between the vesicle and the wall. Second, with a vesicle filled with a denser fluid, we find a stationary hovering state. We present an estimate of the viscous lift force which seems to agree with recent experiments of Lorz et al. [Europhys. Lett., vol. 51, 468 (2000)]. Third, if the wall exerts an additional adhesive force, we investigate the dynamical unbinding transition which occurs at an adhesion strength linearly proportional to the shear rate.Comment: 17 pages (incl. 10 figures), RevTeX (figures in PostScript

    Magnetic oxide semiconductors

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    Magnetic oxide semiconductors, oxide semiconductors doped with transition metal elements, are one of the candidates for a high Curie temperature ferromagnetic semiconductor that is important to realize semiconductor spintronics at room temperature. We review in this paper recent progress of researches on various magnetic oxide semiconductors. The magnetization, magneto-optical effect, and magneto-transport such as anomalous Hall effect are examined from viewpoint of feasibility to evaluate the ferromagnetism. The ferromagnetism of Co-doped TiO2 and transition metal-doped ZnO is discussed.Comment: 26 pages, 5 tables, 6 figure

    Concurrent acute myeloid leukemia and T lymphoblastic lymphoma in a patient with rearranged PDGFRB genes

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    Concurrent hematologic malignancies are relatively rare. We encountered a case of concurrent acute myeloid leukemia (AML) and T lymphoblastic lymphoma. The bone marrow chromosome analysis showed the karyotype 46, XY, t(5;12)(q33;p13), which indicated presence of PDGFRB gene translocations. Therefore, this disease belongs to the new WHO category of myeloid and lymphoid neoplasms with abnormalities in PDGFRA, PDGFRB and FGFR1 genes. Although such genetic mutations are prone to multi-lineage differentiation, the present case is in fact the first report of concurrent AML and T lymphoblastic lymphoma involving PDGFRB mutations. The patient was treated with cytarabine and daunomycin in combination with high dose dexamethasone. Allogeneic stem cell transplantation was performed after successful remission induction for both entities. The patient eventually died of chronic graft-versus-host-disease related infection. Based on such an experience, we suggest the decision of stem cell transplantation should be weighed carefully against the risks, especially when tyrosine kinase inhibitors are safe and potentially effective in dealing with such entities

    Covariant Light-Front Approach for s-wave and p-wave Mesons: Its Application to Decay Constants and Form Factors

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    We study the decay constants and form factors of the ground-state s-wave and low-lying p-wave mesons within a covariant light-front approach. Numerical results of the form factors for transitions between a heavy pseudoscalar meson and an s-wave or p-wave meson and their momentum dependence are presented in detail. In particular, form factors for heavy-to-light and B to D** transitions, where D** denotes generically a p-wave charmed meson, are compared with other model calculations. The experimental measurements of the decays B^- to D** pi^- and B to D D**_s are employed to test the decay constants of D**_s and the B to D** transition form factors. The heavy quark limit behavior of the decay constants and form factors is examined and it is found that the requirement of heavy quark symmetry is satisfied. The universal Isgur-Wise (IW) functions, one for s-wave to s-wave and two for s-wave to p-wave transitions, are obtained. The values of IW functions at zero recoil and their slope parameters can be used to test the Bjorken and Uraltsev sum rules.Comment: 59 pages, 6 figures. Version to appear in Phys. Rev. D. Changes are: (i) D_s to phi transition form factors are discussed and compared with the recent FOCUS measurements and (ii) zero mode effects are clarifie
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