1,042 research outputs found

    Remark on Pauli-Villars Lagrangian on the Lattice

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    It is interesting to superimpose the Pauli-Villars regularization on the lattice regularization. We illustrate how this scheme works by evaluating the axial anomaly in a simple lattice fermion model, the Pauli-Villars Lagrangian with a gauge non-invariant Wilson term. The gauge non-invariance of the axial anomaly, caused by the Wilson term, is remedied by a compensation among Pauli-Villars regulators in the continuum limit. A subtlety in Frolov-Slavnov's scheme for an odd number of chiral fermions in an anomaly free complex gauge representation, which requires an infinite number of regulators, is briefly mentioned.Comment: 14 pages, Phyzzx. The final version to appear in Phys. Rev.

    Dynamical structure factors of the magnetization-plateau state in the S=1/2S=1/2 bond-alternating spin chain with a next-nearest-neighbor interaction

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    We calculate the dynamical structure factors of the magnetization-plateau state in the S=1/2S=1/2 bond-alternating spin chain with a next-nearest-neighbor interaction. The results show characteristic behaviors depending on the next-nearest-neighbor interaction α\alpha and the bond-alternation δ\delta. We discuss the lower excited states in comparison with the exact excitation spectrums of an effective Hamiltonian. From the finite size effects, characteristics of the lowest excited states are investigated. The dispersionless mode of the lowest excitation appears in adequate sets of α\alpha and δ\delta, indicating that the lowest excitation is localized spatially and forms an isolated mode below the excitation continuum. We further calculate the static structure factors. The largest intensity is located at q=πq=\pi for small δ\delta in fixed α\alpha. With increasing δ\delta, the wavenumber of the largest intensity shifts towards q=π/2q=\pi/2, taking the incommensurate value.Comment: to appear in Phys. Rev. B (2001

    High pressure phase diagrams of CeRhIn5_5 and CeCoIn5_5 studied by ac calorimetry

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    The pressure-temperature phase diagrams of the heavy fermion antiferromagnet CeRhIn5_5 and the heavy fermion superconductor CeCoIn5_5 have been studied under hydrostatic pressure by ac calorimetry and ac susceptibility measurements using diamond anvil cells with argon as pressure medium. In CeRhIn5_5, the use of a highly hydrostatic pressure transmitting medium allows for a clean simultaneous determination by a bulk probe of the antiferromagnetic and superconducting transitions. We compare our new phase diagram with the previous ones, discuss the nature (first or second order) of the various lines, and the coexistence of antiferromagnetic order and superconductivity. The link between the collaps of the superconducting heat anomaly and the broadening of the antiferromagnetic transition points to an inhomogeneous appearence of superconductivity below Pc1.95P_c \approx 1.95 GPa. Homogeneous bulk superconductivity is only observed above this critical pressure. We present a detailed analysis of the influence of pressure inomogeneities on the specific heat anomalies which emphasizes that the observed broadening of the transitions near PcP_c is connected with the first order transition. For CeCoIn5_5 we show that the large specific heat anomaly observed at TcT_c at ambient pressure is suppressed linearly at least up to 3 GPa

    Coexistence of magnetism and superconductivity in CeRh1-xIrxIn5

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    We report a thermodynamic and transport study of the phase diagram of CeRh1-xIrxIn5. Superconductivity is observed over a broad range of doping, 0.3 < x < 1, including a substantial range of concentration (0.3 < x <0.6) over which it coexists with magnetic order (which is observed for 0 < x < 0.6). The anomalous transition to zero resistance that is observed in CeIrIn5 is robust against Rh substitution. In fact, the observed bulk Tc in CeRh0.5Ir0.5In5 is more than double that of CeIrIn5, whereas the zero-resistance transition temperature is relatively unchanged for 0.5 < x < 1

    Survey of genetic counselors and clinical geneticists' use and attitudes toward pharmacogenetic testing

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    Pharmacogenetic (PGx) testing aims to improve therapeutic outcomes through tailoring treatment based on a patient’s genetic risk for non-response and/or an adverse event. Given their expertise, geneticists could facilitate the use of PGx testing; however, , the preparedness and perceived role of the clinical genetics community is unclear. To assess the attitudes, preparedness, and perceived roles of geneticists in the delivery of PGx testing, we conducted a survey of 1500 randomly selected board-certified genetic counselors and clinical geneticists in the U.S (response rate: 37.8% (n=516)). Twelve percent of genetic counselors and 41% of clinical geneticists indicated that they had ordered or coordinated patient care for PGx testing, a seemingly high proportion at this early stage of adoption. Almost all respondents had some education on pharmacogenetics, though only 28% of counselors and 58% of clinical geneticists indicated they felt well-informed about PGx testing. About half of counselors (52%) and clinical geneticists (46%) felt they would play ‘some’ role in the delivery of PGx testing; 17% and 19%, respectively, felt that they would play ‘no’ or ‘a little’ role. At this early stage of PGx testing, the role of geneticists and genetic counselors is unclear. However, their experience may aid in readying PGx testing and informing delivery strategies into clinical practice

    phot1 inhibition of ABCB19 primes lateral auxin fluxes in the shoot apex required for phototropism

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    It is well accepted that lateral redistribution of the phytohormone auxin underlies the bending of plant organs towards light. In monocots, photoreception occurs at the shoot tip above the region of differential growth. Despite more than a century of research, it is still unresolved how light regulates auxin distribution and where this occurs in dicots. Here, we establish a system in Arabidopsis thaliana to study hypocotyl phototropism in the absence of developmental events associated with seedling photomorphogenesis. We show that auxin redistribution to the epidermal sites of action occurs at and above the hypocotyl apex, not at the elongation zone. Within this region, we identify the auxin efflux transporter ATP-BINDING CASSETTE B19 (ABCB19) as a substrate target for the photoreceptor kinase PHOTOTROPIN 1 (phot1). Heterologous expression and physiological analyses indicate that phosphorylation of ABCB19 by phot1 inhibits its efflux activity, thereby increasing auxin levels in and above the hypocotyl apex to halt vertical growth and prime lateral fluxes that are subsequently channeled to the elongation zone by PIN-FORMED 3 (PIN3). Together, these results provide new insights into the roles of ABCB19 and PIN3 in establishing phototropic curvatures and demonstrate that the proximity of light perception and differential phototropic growth is conserved in angiosperm

    Lipid-soluble Vitamins A, D, and E in HIV-Infected Pregnant women in Tanzania.

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    There is limited published research examining lipid-soluble vitamins in human immunodeficiency virus (HIV)-infected pregnant women, particularly in resource-limited settings. This is an observational analysis of 1078 HIV-infected pregnant women enrolled in a trial of vitamin supplementation in Tanzania. Baseline data on sociodemographic and anthropometric characteristics, clinical signs and symptoms, and laboratory parameters were used to identify correlates of low plasma vitamin A (<0.7 micromol/l), vitamin D (<80 nmol/l) and vitamin E (<9.7 micromol/l) status. Binomial regression was used to estimate risk ratios and 95% confidence intervals. Approximately 35, 39 and 51% of the women had low levels of vitamins A, D and E, respectively. Severe anemia (hemoglobin <85 g/l; P<0.01), plasma vitamin E (P=0.02), selenium (P=0.01) and vitamin D (P=0.02) concentrations were significant correlates of low vitamin A status in multivariate models. Erythrocyte Sedimentation Rate (ESR) was independently related to low vitamin A status in a nonlinear manner (P=0.01). The correlates of low vitamin D status were CD8 cell count (P=0.01), high ESR (ESR >81 mm/h; P<0.01), gestational age at enrollment (nonlinear; P=0.03) and plasma vitamins A (P=0.02) and E (P=0.01). For low vitamin E status, the correlates were money spent on food per household per day (P<0.01), plasma vitamin A concentration (nonlinear; P<0.01) and a gestational age <16 weeks at enrollment (P<0.01). Low concentrations of lipid-soluble vitamins are widely prevalent among HIV-infected women in Tanzania and are correlated with other nutritional insufficiencies. Identifying HIV-infected persons at greater risk of poor nutritional status and infections may help inform design and implementation of appropriate interventions

    Search for dinucleon decay into pions at Super-Kamiokande

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    A search for dinucleon decay into pions with the Super-Kamiokande detector has been performed with an exposure of 282.1 kiloton-years. Dinucleon decay is a process that violates baryon number by two units. We present the first search for dinucleon decay to pions in a large water Cherenkov detector. The modes 16^{16}O(pp)(pp) \rightarrow 14^{14}Cπ+π+\pi^{+}\pi^{+}, 16^{16}O(pn)(pn) \rightarrow 14^{14}Nπ+π0\pi^{+}\pi^{0}, and 16^{16}O(nn)(nn) \rightarrow 14^{14}Oπ0π0\pi^{0}\pi^{0} are investigated. No significant excess in the Super-Kamiokande data has been found, so a lower limit on the lifetime of the process per oxygen nucleus is determined. These limits are: τppπ+π+>7.22×1031\tau_{pp\rightarrow\pi^{+}\pi^{+}} > 7.22 \times 10^{31} years, τpnπ+π0>1.70×1032\tau_{pn\rightarrow\pi^{+}\pi^{0}} > 1.70 \times 10^{32} years, and τnnπ0π0>4.04×1032\tau_{nn\rightarrow\pi^{0}\pi^{0}} > 4.04 \times 10^{32} years. The lower limits on each mode are about two orders of magnitude better than previous limits from searches for dinucleon decay in iron.Comment: 20 pages, 17 figures. Accepted for publication in Physical Review D on March 30, 201
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