Flux noise in high-temperature superconductors

Spontaneously created vortex-antivortex pairs are the predominant source of flux noise in high-temperature superconductors. In principle, flux noise measurements allow to check theoretical predictions for both the distribution of vortex-pair sizes and for the vortex diffusivity. In this paper the flux-noise power spectrum is calculated for the highly anisotropic high-temperature superconductor Bi-2212, both for bulk crystals and for ultra-thin films. The spectrum is basically given by the Fourier transform of the temporal magnetic-field correlation function. We start from a Berezinskii-Kosterlitz-Thouless type theory and incorporate vortex diffusion, intra-pair vortex interaction, and annihilation of pairs by means of a Fokker-Planck equation to determine the noise spectrum below and above the superconducting transition temperature. We find white noise at low frequencies omega and a spectrum proportional to 1/omega^(3/2) at high frequencies. The cross-over frequency between these regimes strongly depends on temperature. The results are compared with earlier results of computer simulations.Comment: 9 pages, 4 PostScript figures, to be published in Phys. Rev.

Patient preferences for the design of a pharmacy-based colorectal cancer screening program

Purpose: To assess preferences for design of a pharmacy-based colorectal cancer (CRC) screening program (PharmFIT™) among screening-eligible adults in the United States (US) and explore the impact of rurality on pharmacy use patterns (e.g., pharmacy type, prescription pick-up preference, service quality rating). Methods: We conducted a national online survey of non-institutionalized US adults through panels managed by Qualtrics, a survey research company. A total of 1,045 adults (response rate 62%) completed the survey between March and April 2021. Sampling quotas matched respondents to the 2010 US Census and oversampled rural residents. We assessed pharmacy use patterns by rurality and design preferences for learning about PharmFIT™; receiving a FIT kit from a pharmacy; and completing and returning the FIT kit. Results: Pharmacy use patterns varied, with some notable differences across rurality. Rural respondents used local, independently owned pharmacies more than non-rural respondents (20.4%, 6.3%, p < 0.001) and rated pharmacy service quality higher than non-rural respondents. Non-rural respondents preferred digital communication to learn about PharmFIT™ (36% vs 47%; p < 0.001) as well as digital FIT counseling (41% vs 49%; p = 0.02) more frequently than rural participants. Preferences for receiving and returning FITs were associated with pharmacy use patterns: respondents who pick up prescriptions in-person preferred to get their FIT (OR 7.7; 5.3–11.2) and return it in-person at the pharmacy (OR 1.7; 1.1–2.4). Conclusion: Pharmacies are highly accessible and could be useful for expanding access to CRC screening services. Local context and pharmacy use patterns should be considered in the design and implementation of PharmFIT™

NMR and NQR Fluctuation Effects in Layered Superconductors

We study the effect of thermal fluctuations of the s-wave order parameter of a quasi two dimensional superconductor on the nuclear spin relaxation rate near the transition temperature Tc. We consider both the effects of the amplitude fluctuations and the Berezinskii-Kosterlitz-Thouless (BKT) phase fluctuations in weakly coupled layered superconductors. In the treatment of the amplitude fluctuations we employ the Gaussian approximation and evaluate the longitudinal relaxation rate 1/T1 for a clean s-wave superconductor, with and without pair breaking effects, using the static pair fluctuation propagator D. The increase in 1/T1 due to pair breaking in D is overcompensated by the decrease arising from the single particle Green's functions. The result is a strong effect on 1/T1 for even a small amount of pair breaking. The phase fluctuations are described in terms of dynamical BKT excitations in the form of pancake vortex-antivortex (VA) pairs. We calculate the effect of the magnetic field fluctuations caused by the translational motion of VA excitations on 1/T1 and on the transverse relaxation rate 1/T2 on both sides of the BKT transitation temperature T(BKT)<Tc. The results for the NQR relaxation rates depend strongly on the diffusion constant that governs the motion of free and bound vortices as well as the annihilation of VA pairs. We discuss the relaxation rates for real multilayer systems where the diffusion constant can be small and thus increase the lifetime of a VA pair, leading to an enhancement of the rates. We also discuss in some detail the experimental feasibility of observing the effects of amplitude fluctuations in layered s-wave superconductors such as the dichalcogenides and the effects of phase fluctuations in s- or d-wave superconductors such as the layered cuprates.Comment: 38 pages, 12 figure

Caracterización de harinas de tritíceas híbridas

Triticales (x Triticosecale Wittmack) y tricepiros (x Triticosecale Witt. X x Agrotricum A. Camus) se mejoran con la finalidad de obtener cultivares de doble propósito (forraje y grano). Para su utilización en consumo humano, la calidad de las harinas de triticales es frecuentemente evaluada midiendo el diámetro y factor de expansión de las galletitas horneadas. Estos indicadores están fuertemente relacionados al contenido de almidón dañado, proteína y polisacáridos no amiláceos de la harina que determinan sus propiedades de absorción de agua. Se evaluaron 25 líneas experimentales, ocho cultivares de triticale y uno de tricepiro en Santa Rosa, La Pampa, Argentina, durante 2012, mediante análisis de correlación simple y de conglomerados. Se observaron correlaciones positivas entre los valores de la capacidad de retención del solvente agua, carbonato de sodio, ácido láctico y sacarosa, índice de retención de agua alcalina, pentosanos solubles y almidón dañado. La caracterización de las harinas y la separación en grupos según sus propiedades fisicoquímicas permitieron la selección de genotipos con diferentes propiedades funcionales. En el análisis de conglomerados, el cluster 1 agrupó los materiales con mejores características fisicoquímicas de las harinas, lo cual aumenta las posibilidades de su empleo en la alimentación humana.Triticales (x Triticosecale Wittmack) and Tricepiros (x Triticosecale Witt. X x Agrotricum A. Camus) are improved in order to obtain dual-purpose cultivars (forage and grain). In order to use them for human consumption the quality of triticale four is frequently evaluated by measuring the diameter and spread factor of cookies. These indicators are strongly related to the contents of damaged starch, protein and non-starch polysaccharides of four, which determine its water absorption properties. During 2012, twenty-five experimental strains, eight triticale and one tricepiro cultivars were evaluated in Santa Rosa, La Pampa, Argentina by means of simple correlation and cluster analysis. Positive correlations between the values of solvent retention capacity of water, sodium carbonate, lactic acid and sucrose, retention rate of alkaline water, soluble pentosans and damaged starch were observed. The characterization of the tested fours and their differentiation based on their physicochemical properties allowed the selection of genotypes with different functional properties. In the cluster analysis, cluster 1 pooled the materials with the best physicochemical features of four, which increases the possibilities of its use for human consumption.Fil: Castaño, M. N.. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Ferrari, E. D.. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Picca, Aurora Maria Teresita. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Curti, María Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Ribotta, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; Argentina. Universidad Nacional de Córdoba. Secretaría de Ciencia y Tecnología. Instituto Superior de Investigación, Desarrollo y Servicio de Alimentos; ArgentinaFil: Leon, Alberto Edel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; ArgentinaFil: Ferreira, V. A.. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Grassi, E. M.. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Di Santo, Hernán Elías. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Castillo, E. A.. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Paccapelo, Hector Antonio. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentin

Measurement of the partial widths of the Z into up- and down-type quarks

Using the entire OPAL LEP1 on-peak Z hadronic decay sample, Z -> qbarq gamma decays were selected by tagging hadronic final states with isolated photon candidates in the electromagnetic calorimeter. Combining the measured rates of Z -> qbarq gamma decays with the total rate of hadronic Z decays permits the simultaneous determination of the widths of the Z into up- and down-type quarks. The values obtained, with total errors, were Gamma u = 300 ^{+19}_{-18} MeV and Gamma d = 381 ^{+12}_{-12} MeV. The results are in good agreement with the Standard Model expectation.Comment: 22 pages, 5 figures, Submitted to Phys. Letts.

Search for R-Parity Violating Decays of Scalar Fermions at LEP

A search for pair-produced scalar fermions under the assumption that R-parity is not conserved has been performed using data collected with the OPAL detector at LEP. The data samples analysed correspond to an integrated luminosity of about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An important consequence of R-parity violation is that the lightest supersymmetric particle is expected to be unstable. Searches of R-parity violating decays of charged sleptons, sneutrinos and squarks have been performed under the assumptions that the lightest supersymmetric particle decays promptly and that only one of the R-parity violating couplings is dominant for each of the decay modes considered. Such processes would yield final states consisting of leptons, jets, or both with or without missing energy. No significant single-like excess of events has been observed with respect to the Standard Model expectations. Limits on the production cross- section of scalar fermions in R-parity violating scenarios are obtained. Constraints on the supersymmetric particle masses are also presented in an R-parity violating framework analogous to the Constrained Minimal Supersymmetric Standard Model.Comment: 51 pages, 24 figures, Submitted to Eur. Phys. J.

Measurement of the Strong Coupling alpha s from Four-Jet Observables in e+e- Annihilation

Data from e+e- annihilation into hadrons at centre-of-mass energies between 91 GeV and 209 GeV collected with the OPAL detector at LEP, are used to study the four-jet rate as a function of the Durham algorithm resolution parameter ycut. The four-jet rate is compared to next-to-leading order calculations that include the resummation of large logarithms. The strong coupling measured from the four-jet rate is alphas(Mz0)= 0.1182+-0.0003(stat.)+-0.0015(exp.)+-0.0011(had.)+-0.0012(scale)+-0.0013(mass) in agreement with the world average. Next-to-leading order fits to the D-parameter and thrust minor event-shape observables are also performed for the first time. We find consistent results, but with significantly larger theoretical uncertainties.Comment: 25 pages, 15 figures, Submitted to Euro. Phys. J.