Velocity of sound in a Bose-Einstein condensate in the presence of an optical lattice and transverse confinement

We study the effect of the transverse degrees of freedom on the velocity of sound in a Bose-Einstein condensate immersed in a one-dimensional optical lattice and radially confined by a harmonic trap. We compare the results of full three-dimensional calculations with those of an effective 1D model based on the equation of state of the condensate. The perfect agreement between the two approaches is demonstrated for several optical lattice depths and throughout the full crossover from the 1D mean-field to the Thomas Fermi regime in the radial direction.Comment: final versio

Microbiological aspects of methane emission in a ricefield soil from the Camargue (France) : 2. Methanotrophy and related microflora

Les principaux facteurs qui influencent l'activité méthanotrophe du sol (épaisseur du sol, humidité, addition d'engrais et dessiccation) ont été étudiés in vitro sur un sol de rizière de Camargue (France) afin de standardiser une méthode pour estimer l'activité méthanotrophe potentielle (PMA) d'un sol. La possibilité d'énumérer les méthanotrophes du sol a été étudiée et les souches dominantes du sol incubé pendant un mois sous un mélange de 80% air/20% CH4 ont été isolées. La méthanotrophie in vitro est un phénomène quantifiable par unité de surface plutôt que par unité de poids de sol. L'activité maximale (PMA)(1.8 mole m-2 j-1) a été mesurée sur un échantillon à une humidité voisine de la capacité au champ et incubé pendant un mois sous air/CH4. Les consommations de CH4 et d'O2 ainsi que la production de CO2 sont fortement corrélées. La consommation d'O2 liée à l'activité hétérotrophe du sol est négligeable comparée à celle due à l'activité méthanotrophe. L'addition d'engrais à des concentrations utilisées en agriculture est sans effet sur la PMA qui est restée stable pendant deux ans dans le sol conservé à l'état sec. Une très forte contamination rend les étalements sur boites de Pétri inexploitables pour dénombrer les bactéries méthanotrophes du sol. Les populations estimées par MPN sont faibles dans le sol sec (2.5 x 102 g-1) et atteignent 5 x 108 g-1 dans le sol enrichi. La morphologie des souches isolées indique leur appartenance aux bactéries méthanotrophes de type II. (Résumé d'auteur

First-Principles Study on Electron Conduction in Sodium Nanowire

We present detailed first-principles calculations of the electron-conduction properties of a three-sodium-atom nanowire suspended between semi-infinite crystalline Na(001) electrodes during its elongation. Our investigations reveal that the conductance is ~1 G0 before the nanowire breaks and only one channel with the characteristic of the $3s$ orbital of the center atom in the nanowire contributes to the electron conduction. Moreover, the channel fully opens around the Fermi level, and the behavior of the channel-current density is insensitive to the structural deformation of the nanowire. These results verify that the conductance trace as a function of the electrode spacing exhibits a flat plateau at ~1 G0 during elongation.Comment: 8 pages, 5 figure

Photovoltaic Restoration of Central Vision in Atrophic Age-Related Macular Degeneration

PURPOSE: Loss of photoreceptors in atrophic age-related macular degeneration results in severe visual impairment, although some peripheral vision is retained. To restore central vision without compromising the residual peripheral field, we developed a wireless photovoltaic retinal implant (PRIMA; Pixium Vision, Paris, France) in which pixels convert images projected from video glasses using near-infrared light into electric current to stimulate the nearby inner retinal neurons. DESIGN: We carried out a first-in-human clinical trial to test the safety and efficacy of the prosthesis in patients with geographic atrophy (ClinicalTrials.gov identifier, NCT03333954). PARTICIPANTS: Five patients with geographic atrophy zone of at least 3 optic disc diameters, no foveal light perception, and best-corrected visual acuity of 20/400 to 20/1000 in the worse-seeing study eye. METHODS: The 2-mm wide, 30-μm thick chip, containing 378 pixels (each 100 μm in diameter), was implanted subretinally in the area of atrophy (absolute scotoma). MAIN OUTCOME MEASURES: Anatomic outcomes were assessed with fundus photography and OCT for up to 12 months of follow-up. Prosthetic vision was assessed by mapping light perception, bar orientation, letter recognition, and Landolt C acuity. RESULTS: In all patients, the prosthesis was implanted successfully under the macula, although in 2 patients, it was implanted in unintended locations: within the choroid and off center by 2 mm. All 5 patients could perceive white-yellow prosthetic visual patterns with adjustable brightness in the previous scotomata. The 3 with optimal placement of the implant demonstrated prosthetic acuity of 20/460 to 20/550, and the patient with the off-center implant demonstrated 20/800 acuity. Residual natural acuity did not decrease after implantation in any patient. CONCLUSIONS: Implantation of the PRIMA did not decrease the residual natural acuity, and it restored visual sensitivity in the former scotoma in each of the 5 patients. In 3 patients with the proper placement of the chip, prosthetic visual acuity was only 10% to 30% less than the level expected from the pixel pitch (20/420). Therefore, the use of optical or electronic magnification in the glasses as well as smaller pixels in future implants may improve visual acuity even further

Challenges around COVID-19 at a tertiary-level healthcare facility in South Africa and strategies implemented for improvement

SARS-CoV-2 has resulted in a global pandemic within months following its initial detection. South Africa (SA), like many other countries, was not prepared for the impact this novel infection would have on the healthcare system. In this paper, the authors discuss the challenges experienced while facing COVID-19 at a tertiary-level institution in Gauteng province, SA, and the dynamic strategies implemented to deal with the epidemic

A prospective observational study of on-treatment plasma homocysteine levels as a biomarker of toxicity, depression and vitamin supplementation lead-in time pre pemetrexed, in patients with non-small cell lung cancer and malignant mesothelioma

OBJECTIVES: Vitamin supplementation reduces pemetrexed toxicity. Raised plasma homocysteine reflects deficiency in vitamin B12 and folate, and is suppressed by supplementation. This observational study of 112 patients receiving pemetrexed-based chemotherapy assessed homocysteine levels after 3 weeks of vitamin supplementation, hypothesising high levels would correlate with ongoing deficiency, thus increased toxicity. MATERIAL AND METHODS: Primary endpoint was the composite of proportion of patients with treatment delay/ dose reduction/ drug change or hospitalisation during the first six weeks of chemotherapy, comparing those with normal plasma homocysteine (successfully supplemented, SS) and those with high homocysteine (unsuccessfully supplemented, USS). Secondary endpoints included toxicity and analyses for depression. Post-hoc analysis examined correlation between interval of vitamin and folate supplementation and pemetrexed on primary endpoint and grade 3-4 toxicities. RESULTS: Eighty-four patients (84%) were successfully supplemented (SS group). The proportion of patients undergoing a treatment delay/ dose reduction/ drug change or hospitalisation in SS group was 44.0% (95% confidence interval [CI] 33.2%-55.3%) and in USS group was 18.8% (95% CI 4.0%-45.6%) (p = 0.09). Twelve percent of patients gave a past history of depression however 66% of patients had an on study Hospital Anxiety and Depression (HAD) score of >7. Supplementation status was not associated with depression. The median overall survival (OS) was 11.8 months (95% CI 8.6-16.5) in the SS group and 8.8 months (95% CI 6.6-16.2) in the US group (p = 0.5). The number of days (<7 or ≥ 7 days) between vitamin B12 and folate initiation and pemetrexed administration, had no effect on the primary endpoint and grade 3-4 toxicities. CONCLUSION: On-treatment homocysteine levels were not a biomarker of toxicity or depression. Standard vitamin supplementation is adequate in the majority of patients receiving pemetrexed. High HAD score were noted in this population giving an opportunity for mental health intervention. The lead-in time for vitamin supplementation can be short

Capacidade para o trabalho em indivíduos com lesões músculo-esqueléticas crônicas

OBJECTIVE: To evaluate the impact of personal, clinical, and occupational aspects on work ability of workers with and without work-related musculoskeletal disorders using the Work Ability Index. METHODS: There were participating 127 workers of industrial production lines of a medium-size multinational company. An approved version of the Work Ability Index, a questionnaire developed by Finland's Institute of Occupational Health, was used. Pain scale was also applied. A descriptive analysis was carried out using the Chi-square test and it was also performed a logistic regression analysis. RESULTS: A significant association was identified between the Work Ability Index and all personal, clinical and occupational aspects. Regression analysis showed that pain and sick leave together accounted for 59% of poor work ability. CONCLUSIONS: Different levels of pain severity were associated with distinct as well as equivalent levels of work ability loss. The results suggest that either pain reports were consistent or being both pain and work ability self-reported they therefore reflect the same perception mechanisms. Future studies might contribute to further understanding the trends found.OBJETIVO: Avaliar o impacto de fatores pessoais, do trabalho e da lesão na capacidade funcional dos trabalhadores com e sem história de acometimento de lesões músculo-esqueléticas relacionadas ao trabalho, através da aplicação do índice de capacidade para o trabalho. MÉTODOS: Participaram do estudo 127 trabalhadores da linha de produção de uma empresa multinacional de porte médio. Foi aplicada uma tradução autorizada do índice de capacidade para o trabalho, um questionário elaborado pelo Instituto de Saúde Ocupacional da Finlândia, assim como uma escala de dor. Os resultados foram analisados descritivamente, por meio do teste qui-quadrado e pela análise de regressão logística. RESULTADOS: Todos os fatores pessoais, ocupacionais e clínicos analisados apresentaram relação significativa com a capacidade para o trabalho. A análise de regressão mostrou que as variáveis de dor e afastamentos, quando associadas, explicam 59% das ocorrências de baixa capacidade para o trabalho. CONCLUSÕES: Diferentes níveis de dor refletiram níveis também distintos e equivalentes de perda da capacidade para o trabalho, o que pode sugerir que os relatos de dor são consistentes. Ou, por outro lado, que ambos - dor e incapacidade - são baseados em auto-relatos e, portanto, estão permeados pelos mesmos mecanismos de percepção. Estudos futuros podem contribuir para melhor avaliar essas tendências

Superfluid to Mott insulator transition in one, two, and three dimensions

We have created one-, two-, and three-dimensional quantum gases and study the superfluid to Mott insulator transition. Measurements of the transition using Bragg spectroscopy show that the excitation spectra of the low-dimensional superfluids differ significantly from the three-dimensional case