Path integrals and degrees of freedom in many-body systems and relativistic field theories

The identification of physical degrees of freedom is sometimes obscured in the path integral formalism, and this makes it difficult to impose some constraints or to do some approximations. I review a number of cases where the difficulty is overcame by deriving the path integral from the operator form of the partition function after such identification has been made.Comment: 15 pages, volume in honor of prof.Yu.A.Simono

Boson Dominance in nuclei

We present a new method of bosonization of fermion systems applicable when the partition function is dominated by composite bosons. Restricting the partition function to such states we get an euclidean bosonic action from which we derive the Hamiltonian. Such a procedure respects all the fermion symmetries, in particular fermion number conservation, and provides a boson mapping of all fermion operators.Comment: 12 page

Precise half-life measurement of 110Sn and 109In isotopes

The half-lives of 110Sn and 109In isotopes have been measured with high precision. The results are T1/2 =4.173 +- 0.023 h for 110Sn and T1/2 = 4.167 +-0.018 h for 109In. The precision of the half-lives has been increased by a factor of 5 with respect to the literature values which makes results of the recently measured 106Cd(alpha,gamma)110Sn and 106Cd(alpha,p)109In cross sections more reliable.Comment: 3 pages, 2 figures, accepted for publication in Phys. Rev C as brief repor

Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis.

BACKGROUND: We studied the incidence, prevalence, and radiographic progression of symptomatic adjacent-segment disease, which we defined as the development of new radiculopathy or myelopathy referable to a motion segment adjacent to the site of a previous anterior arthrodesis of the cervical spine. METHODS: A consecutive series of 374 patients who had a total of 409 anterior cervical arthrodeses for the treatment of cervical spondylosis with radiculopathy or myelopathy, or both, were followed for a maximum of twenty-one years after the operation. The annual incidence of symptomatic adjacent-segment disease was defined as the percentage of patients who had been disease-free at the start of a given year of follow-up in whom new disease developed during that year. The prevalence was defined as the percentage of all patients in whom symptomatic adjacent-segment disease developed within a given period of follow-up. The natural history of the disease was predicted with use of a Kaplan-Meier survivorship analysis. The hypothesis that new disease at an adjacent level is more likely to develop following a multilevel arthrodesis than it is following a single-level arthrodesis was tested with logistic regression. RESULTS: Symptomatic adjacent-segment disease occurred at a relatively constant incidence of 2.9 percent per year (range, 0.0 to 4.8 percent per year) during the ten years after the operation. Survivorship analysis predicted that 25.6 percent of the patients (95 percent confidence interval, 20 to 32 percent) who had an anterior cervical arthrodesis would have new disease at an adjacent level within ten years after the operation. There were highly significant differences among the motion segments with regard to the likelihood of symptomatic adjacent-segment disease (p CONCLUSIONS: Symptomatic adjacent-segment disease may affect more than one-fourth of all patients within ten years after an anterior cervical arthrodesis. A single-level arthrodesis involving the fifth or sixth cervical vertebra and preexisting radiographic evidence of degeneration at adjacent levels appear to be the greatest risk factors for new disease. Therefore, we believe that all degenerated segments causing radiculopathy or myelopathy should be included in an anterior cervical arthrodesis. Although our findings suggest that symptomatic adjacent-segment disease is the result of progressive spondylosis, patients should be informed of the substantial possibility that new disease will develop at an adjacent level over the long term

O SUB-BOSQUE DE REFLORESTAMENTOS DE PINUS EM SÍTIOS DEGRADADOS DA REGIÃO DA FLORESTA ESTACIONAL DECIDUAL DO RIO GRANDE DO SUL

Analisou-se o sub-bosque de 12 povoamentos de Pinus sp. e um de Araucaria angustifolia O.Ktze., crescendo em solos degradados pelo uso agrícola na chamada 4a Colônia do Rio Grande do Sul. A Araucaria foi semeada diretamente, um dos povoamentos de Pinus, de 10 anos, resultou de uma renovação natural, os demais provêm de plantios de 25 a 30 anos atrás. Em 575 parcelas de 25 m² cada, distribuídas sistematicamente nos povoamentos, foram levantados o estrato arbóreo e a vegetação inferior, classificada em estratos de 0,3 a 1,3 m e maior que 1,3 m; no estrato inferior a 0,3 m somente a renovação natural de Pinus foi contada. A vegetação interna dos povoamentos se compôs de 121 espécies lenhosas, incluindo espécies desde comuns até nobres, mas também ornamentais ou frutíferas nativas e exóticas. Um bom número de espécies, porém, ocorreu com poucos representantes. Além disso registrou-se a presença freqüente de espécies não-arbóreas como ervas, gramas, samambaias e cipós. O número de espécies e o grau de cobertura do sub-bosque não dependiam da densidade do estrato superior de pinheiros. A abundância e a freqüência das espécies não variavam significativamente entre parcelas do centro dos povoamentos e da faixa periférica. O padrão de distribuição espacial das plantas dentro dos povoamentos foi quantificado pelo Índice de Cox. O Índice de Shannon foi usado como medida da diversidade em espécies; pelo Índice de Sörensen foi estudada a semelhança dos povoamentos. Conclui-se que plantios de exóticas nessa região não somente podem ser de interesse para os agricultores pelo elevado potencial produtivo em madeira, como também significam manchas de inesperada biodiversidade numa paisagem degradada. A riqueza do sub-bosque possivelmente se deve á extensão reduzida desses povoamentos

Progress on the hybrid gun project at UCLA

UCLA/INFN-LNF/Univ. Rome has been developing the hybrid gun which has an RF gun and a short linac for velocity bunching in one structure. After the cavity was manufactured at INFN-LNF in 2012, tests of the gun was carried out at UCLA. The field in the standing wave part was 20 % smaller than the simulation but the phase advance was fine. The cavity was commissioned successfully up to 13 MW. The beam test was performed at 11.5 MW and demonstrated the bunch compression

Post Quantum Cryptography from Mutant Prime Knots

By resorting to basic features of topological knot theory we propose a (classical) cryptographic protocol based on the `difficulty' of decomposing complex knots generated as connected sums of prime knots and their mutants. The scheme combines an asymmetric public key protocol with symmetric private ones and is intrinsecally secure against quantum eavesdropper attacks.Comment: 14 pages, 5 figure

Loop Variables for compact two-dimensional quantum electrodynamics

Variables parametrized by closed and open curves are defined to reformulate compact U(1) Quantum Electrodynamics in the circle with a massless fermion field. It is found that the gauge invariant nature of these variables accommodates into a regularization scheme for the Hamiltonian and current operators that is specially well suited for the study of the compact case. The zero mode energy spectrum, the value of the axial anomaly and the anomalous commutators this model presents are hence determined in a manifestly gauge invariant manner. Contrary to the non compact case, the zero mode spectrum is not equally spaced and consequently the theory does not lead to the spectrum of a free scalar boson. All the states are invariant under large gauge transformations. In particular, that is the case for the vacuum, and consequently the $\theta$-dependence does not appear.Comment: 24 pages, 1 figure, to be published in Phys. Rev.