Conditions for spin squeezing in a cold 87Rb ensemble

We study the conditions for generating spin squeezing via a quantum non-demolition measurement in an ensemble of cold 87Rb atoms. By considering the interaction of atoms in the 5S_{1/2}(F=1) ground state with probe light tuned near the D2 transition, we show that, for large detunings, this system is equivalent to a spin-1/2 system when suitable Zeeman substates and quantum operators are used to define a pseudo-spin. The degree of squeezing is derived for the rubidium system in the presence of scattering causing decoherence and loss. We describe how the system can decohere and lose atoms, and predict as much as 75% spin squeezing for atomic densities typical of optical dipole traps.Comment: 9 pages, 3 figures, submitted to J. Opt. B: Quantum Semiclass. Opt. Proceedings of ICSSUR'0

Diffraction effects on light-atomic ensemble quantum interface

We present a simple method to include the effects of diffraction into the description of a light-atomic ensemble quantum interface in the context of collective variables. Carrying out a scattering calculation we single out the purely geometrical effect. We apply our method to the experimentally relevant case of Gaussian shaped atomic samples stored in single beam optical dipole traps and probed by a Gaussian beam. We derive analytical scaling relations for the effect of the interaction geometry and compare our findings to results from 1-dimensional models of light propagation.Comment: 13 pages, 7 figures, comments welcom

Homozygous C-terminal loss-of-function NaV1.4 variant in a patient with congenital myasthenic syndrome

No abstract availabl

Prospects for photon blockade in four level systems in the N configuration with more than one atom

We show that for appropriate choices of parameters it is possible to achieve photon blockade in idealised one, two and three atom systems. We also include realistic parameter ranges for rubidium as the atomic species. Our results circumvent the doubts cast by recent discussion in the literature (Grangier et al Phys. Rev Lett. 81, 2833 (1998), Imamoglu et al Phys. Rev. Lett. 81, 2836 (1998)) on the possibility of photon blockade in multi-atom systems.Comment: 8 page, revtex, 7 figures, gif. Submitted to Journal of Optics B: Quantum and Semiclassical Optic

Heterodyne non-demolition measurements on cold atomic samples: towards the preparation of non-classical states for atom interferometry

We report on a novel experiment to generate non-classical atomic states via quantum non-demolition (QND) measurements on cold atomic samples prepared in a high finesse ring cavity. The heterodyne technique developed for the QND detection exhibits an optical shot-noise limited behavior for local oscillator optical power of a few hundred \muW, and a detection bandwidth of several GHz. This detection tool is used in single pass to follow non destructively the internal state evolution of an atomic sample when subjected to Rabi oscillations or a spin-echo interferometric sequence.Comment: 23 page

Association between adherence to the Mediterranean diet and prevalence of cardiovascular risk factors

Objective: to determine the prevalence of cardiovascular risk factors in a cohort of workers and to quantify its association with compliance with the Mediterranean diet follow-up. Method: a cross-sectional descriptive study was carried out on a cohort of 23, 729 workers. Clinical data from annual medical examinations and the Mediterranean Diet Adherence Screener were used to assess adherence to the Mediterranean diet. Results: 51.3% of the participants showed good adherence to the Mediterranean diet. The multivariate analysis showed an inverse and significant association between the follow-up of the Mediterranean diet and the prevalence of abdominal obesity (Odds Ratio = 0.64, 95% CI 0.56; 0.73), dyslipidemia (Odds Ratio = 0.55, 95% CI 0.42; 0.73), and metabolic syndrome (Odds Ratio = 0.76, 95% CI 0.67; 0.86). Conclusions: our results suggest that the Mediterranean diet is potentially effective in promoting cardiovascular health. Implementing the interventions promoting the Mediterranean diet in the working population seems justified. Objetivo: determinar la prevalencia de factores de riesgo cardiovascular en una cohorte de trabajadores y cuantificar su asociación con el seguimiento de la dieta mediterránea. Método: se llevó a cabo un estudio descriptivo transversal sobre una cohorte de 23.729 trabajadores. Se utilizaron los datos clínicos procedentes de los exámenes médicos anuales y el Mediterranean Diet Adherence Screener para evaluar la adherencia a la dieta mediterránea. Resultados: el 51, 3% de los participantes presentó una buena adherencia a la dieta mediterránea. El análisis multivariante evidenció una asociación inversa y significativa entre el seguimiento de la dieta mediterránea y la prevalencia de obesidad abdominal (Odds Ratio = 0, 64, IC 95% 0, 56; 0, 73), dislipidemia (Odds Ratio = 0, 55, IC 95% 0, 42; 0, 73) y de síndrome metabólico (Odds Ratio = 0, 76, IC 95% 0, 67; 0, 86). Conclusión: nuestros resultados sugieren que la dieta mediterránea es potencialmente eficaz en la promoción de la salud cardiovascular. Parece justificada la implementación de intervenciones que promuevan la dieta mediterránea en la población trabajadora

Low penetrance in facioscapulohumeral muscular dystrophy type 1 with large pathological D4Z4 alleles: a cross-sectional multicenter study.

BackgroundFacioscapulohumeral muscular dystrophy type 1(FSHD1) is an autosomal dominant disorder associated with the contraction of D4Z4 less than 11 repeat units (RUs) on chromosome 4q35. Penetrance in the range of the largest alleles is poorly known. Our objective was to study the penetrance of FSHD1 in patients carrying alleles ranging between 6 to10 RUs and to evaluate the influence of sex, age, and several environmental factors on clinical expression of the disease. Methods A cross-sectional multicenter study was conducted in six French and one Swiss neuromuscular centers. 65 FSHD1 affected patients carrying a 4qA allele of 6¿10 RUs were identified as index cases (IC) and their 119 at-risk relatives were included. The age of onset was recorded for IC only. Medical history, neurological examination and manual muscle testing were performed for each subject. Genetic testing determined the allele size (number of RUs) and the 4qA/4qB allelic variant. The clinical status of relatives was established blindly to their genetic testing results. The main outcome was the penetrance defined as the ratio between the number of clinically affected carriers and the total number of carriers. Results Among the relatives, 59 carried the D4Z4 contraction. At the clinical level, 34 relatives carriers were clinically affected and 25 unaffected. Therefore, the calculated penetrance was 57% in the range of 6¿10 RUs. Penetrance was estimated at 62% in the range of 6¿8 RUs, and at 47% in the range of 9¿10 RUs. Moreover, penetrance was lower in women than men. There was no effect of drugs, anesthesia, surgery or traumatisms on the penetrance. Conclusions Penetrance of FSHD1 is low for largest alleles in the range of 9¿10 RUs, and lower in women than men. This is of crucial importance for genetic counseling and clinical management of patients and families