Elastic scattering of low energy pions by nuclei and the in-medium isovector pi N amplitude

Measurements of elastic scattering of 21.5 MeV pi+ and pi- by Si, Ca, Ni and Zr were made using a single arm magnetic spectrometer. Absolute calibration was made by parallel measurements of Coulomb scattering of muons. Parameters of a pion-nucleus optical potential were obtained from fits to all eight angular distributions put together. The `anomalous' s-wave repulsion known from pionic atoms is clearly observed and could be removed by introducing a chiral-motivated density dependence of the isovector scattering amplitude, which also greatly improved the fits to the data. The empirical energy dependence of the isoscalar amplitude also improves the fits to the data but, contrary to what is found with pionic atoms, on its own is incapable of removing the anomaly.Comment: 20 pages, 5 figures, 5 tables. V2 added details on uncertainties,extended discussion. To appear in PR

The in-medium isovector pi N amplitude from low energy pion scattering

Differential cross sections for elastic scattering of 21.5 MeV positive and negative pions by Si, Ca, Ni and Zr have been measured as part of a study of the pion-nucleus potential across threshold. The `anomalous' repulsion in the s-wave term was observed, as is the case with pionic atoms. The extra repulsion can be accounted for by a chiral-motivated model where the pion decay constant is modified in the medium. Unlike in pionic atoms, the anomaly cannot be removed by merely introducing an empirical on-shell energy dependence.Comment: 9 pages, 2 figures. Minor changes, to appear in PR

Characterization of the casein gene complex in West Africa goats and description of a new αs1-casein polymorphism

The analysis of casein polymorphisms was carried out in West Africa goat populations: Red Sokoto (n = 57), West African Dwarf Nigeria (n = 27), West African Dwarf Cameroon (n = 39), and Borno (n = 37). The 4 casein genes alphas1 (CSN1S1), beta (CSN2), alphas2 (CSN1S2), and kappa (CSN3) were typed at the DNA level. No null alleles were found in any of the genes analyzed. A PCR single-strand conformation polymorphism method was implemented for the identification of CSN1S1*F allele simultaneously with A/01, B/E, N and the new allele. The allele differed from CSN1S1*B by a synonymous transversion TCG->TCT in the codon corresponding to Ser66 of the mature protein. The new allele, named CSN1S1*B', occurred at a high frequency in all the populations, ranging from 0.295 (West African Dwarf Cameroon) to 0.405 (Borno). A greater frequency was found for alleles associated with high alphas1-casein quantity, as has already been observed in the goat populations from the Mediterranean area. The intermediate E allele occurred only in the Red Sokoto and at a low frequency. The faint F allele occurred in 3 populations at frequencies lower than 0.03. Linkage disequilibrium occurred in all the populations, with highly significant differences in Borno, Red Sokoto, and West Africa Dwarf Nigeria, and significant differences in West Africa Dwarf Cameroon. Only 10 haplotypes showed frequencies >= 0.05 in at least 1 of the 4 populations considered, and the overall frequency was >0.1 only for 4 haplotypes: BAAB, B'ACA, ACAB, and BACA (in the order CSN1S1-CSN2-CSN1S2-CSN3). Haplotype BAAB, postulated as an ancestral haplotype in previous studies, was the most common haplotype in all breeds except Borno, where B'ACA was predominant. The results obtained are of considerable significance given that very little information exists on the subject for African goats. The high frequency of strong alleles in the calcium-sensitive caseins as well as the high linkage disequilibrium found among the casein genes in the African breeds analyzed may suggest that specific casein haplotypes have already been selected due to their advantages for nutrition. Haplotypes providing greater protein and casein content would increase the energy content of milk, thus resulting in more favorable growth and survival of young goats and humans consuming the milk

Evolução dos índices de sonolência e fadiga em pacientes com síndrome da apnéia obstrutiva do sono portadores ou não de associação com síndrome das pernas inquietas após CPAP nasal

Objetivo: A associação síndrome de apnéia obstrutiva do sono / síndrome de pernas inquietas (SAOS-SPI) tem sido mencionada na literatura há muito. Ambas podem ser responsáveis por queixas de fadiga e sonolência secundárias à fragmentação do sono noturno. O objetivo deste estudo é avaliar a evolução dos sintomas de fadiga e sonolência diurna excessiva antes e após o tratamento com pressão aérea positiva contínua (CPAP) em pacientes portadores de SAOS, com e sem SPI. Método: Estudo prospectivo e comparativo entre um grupo de 13 pacientes com SAOS e um grupo de 17 com SAOS +SPI. Exames laboratoriais e polissonografia (PSG) foram realizados no início do estudo. A escala de sonolência de Epworth (ESE) e o questionário de fadiga/depressão de Pichot (PIC) foram aplicados antes do tratamento com CPAP e 3 meses após. Os resultados foram comparados. Resultados: No início do estudo não foram encontradas diferenças significativas na avaliação laboratorial e PSG. Ambos os grupos apresentavam inicialmente pontuação semelhante na avaliação da ESE e PIC (p=0,73 e 0,08, respectivamente). Após CPAP, os pacientes SAOS+SPI apresentaram maiores ESE e PIC (p=0,017 e 0,03, respectivamente). Conclusão: Apesar de resposta inicial favorável em ambos os grupos, o CPAP foi aparentemente menos eficaz na redução das queixas de fadiga e sonolência nos pacientes apnéicos com associação a SPI.Background and Purpose: The association of obstructive sleep apnea syndrome (OSAS) and restless legs syndrome (RLS) has been reported in the literature for many years. Both conditions may be responsible for fatigue and somnolence complaints secondary to nocturnal sleep disruption. The primary concern of this study is to evaluate the outcome of fatigue and daytime sleepiness symptoms at baseline and after continuous positive air pressure (CPAP) treatment in OSAS patients with and without RLS. Method: A prospective and comparative study between a group of 13 patients with OSAS and a group of 17 patients with OSAS+RLS. Laboratory blood tests and polysomnography were performed at baseline. The Epworth Sleepiness Scale (ESS) and the Pichot’s questionnaire of fatigue/depression (PIC) were applied before and after 3 months of CPAP treatment. Results were compared. Results: No significant differences were found on PSG and laboratory results at baseline. Both groups had similar ESS and PIC scores at baseline (p=0.73 and 0.08, respectively). After n-CPAP, OSAS+RLS patients showed higher ESS and PIC scores (p=0.017 and 0.03, respectively). Conclusions: Despite a favorable general response, n-CPAP seemed less effective in treating fatigue and sleepiness in the OSAS+RLS group

Low Energy Analyzing Powers in Pion-Proton Elastic Scattering

Analyzing powers of pion-proton elastic scattering have been measured at PSI with the Low Energy Pion Spectrometer LEPS as well as a novel polarized scintillator target. Angular distributions between 40 and 120 deg (c.m.) were taken at 45.2, 51.2, 57.2, 68.5, 77.2, and 87.2 MeV incoming pion kinetic energy for pi+ p scattering, and at 67.3 and 87.2 MeV for pi- p scattering. These new measurements constitute a substantial extension of the polarization data base at low energies. Predictions from phase shift analyses are compared with the experimental results, and deviations are observed at low energies.Comment: 15 pages, 4 figure

Measurement of the Eta Production in Proton Proton Collisions with the COSY Time of Flight Spectrometer

The reaction pp -> pp eta was measured at excess energies of 15 and 41 MeV at an external target of the Juelich Cooler Synchrotron COSY with the Time of Flight Spectrometer. About 25000 events were measured for the excess energy of 15 MeV and about 8000 for 41 MeV. Both protons of the process pp eta were detected with an acceptance of nearly 100% and the eta was reconstructed by the missing mass technique. For both excess energies the angular distributions are found to be nearly isotropic. In the invariant mass distributions strong deviations from the pure phase space distributions are seen.Comment: 15 pages, 14 figures, 4 table

Improved study of a possible Theta+ production in the pp -> p K0 sigma+ reaction with the COSY-TOF spectrometer

The pp -> p K0 Sigma+ reaction was investigated with the TOF spectrometer at COSY at 3.059 GeV/c incident beam momentum. The main objective was to clarify whether or not a narrow exotic S = +1 resnance, the Theta+ pentaquark, is populated at 1.53 GeV/c2 in the K0 p subsystem with a data sample of much higher statistical significance compared to the previously reported data in this channel. An analysis of these data does not confirm the existence of the Theta+ pentaquark. This is expressed as an upper limit for the cross section sigma (pp -> p K0 Sigma+) < 0.15 microbarn at the 95 percent confidence level.Comment: 11 pages, 5 figure