Faraday spectroscopy of atoms confined in a dark optical trap

We demonstrate Faraday spectroscopy with high duty cycle and sampling rate using atoms confined to a blue-detuned optical trap. Our trap consists of a crossed pair of high-charge-number hollow laser beams, which forms a dark, box-like potential. We have used this to measure transient magnetic fields in a 500-micron-diameter spot over a 400 ms time window with nearly unit duty cycle at a 500 Hz sampling rate. We use these measurements to quantify and compensate time-varying magnetic fields to ~10 nT per time sample.Comment: 6 pages, 8 figures Accepted in Phys. Rev.

Cold atom confinement in an all-optical dark ring trap

We demonstrate confinement of $^{85}$Rb atoms in a dark, toroidal optical trap. We use a spatial light modulator to convert a single blue-detuned Gaussian laser beam to a superposition of Laguerre-Gaussian modes that forms a ring-shaped intensity null bounded harmonically in all directions. We measure a 1/e spin-relaxation lifetime of ~1.5 seconds for a trap detuning of 4.0 nm. For smaller detunings, a time-dependent relaxation rate is observed. We use these relaxation rate measurements and imaging diagnostics to optimize trap alignment in a programmable manner with the modulator. The results are compared with numerical simulations.Comment: 5 pages, 4 figure

Spatial variation of symbiotic dinoflagellates on coral reefs of the northern Persian Gulf

Density, mitotic index, Chlorophyll-a content and cell size of symbiotic dinoflagellates of dominant reef-building corals were measured at two different depths in Kish Island and from one depth of Larak Island in the Persian Gulf. The higher densities of symbionts were found in shallow waters of Kish Island. However, ANOVA analyses of the mitotic index yielded mixed results. The cell sizes of symbionts did not significantly differ among depths, except for Porites corals at one site in Kish Island which displayed the larger cells in deeper water. The comparison of symbiont attributes between islands exhibited intraspecific variability. Density of zooxanthellae was only different in Porites and Favia corals between islands. Chlorophyll-a density (cm-2) was significantly different between islands in all species, with higher values for Kish corals. Chlorophyll a cell-1 was only significantly different in Porites and Platygyra corals, with higher values for Larak Island. The symbiont cell sizes usually exhibited no variability, except for Porites corals with larger sizes in Kish Island

Efficient learning mechanisms hold in the social domain and are implemented in the medial prefrontal cortex

When we are learning to associate novel cues with outcomes, learning is more efficient if we take advantage of previously learned associations and thereby avoid redundant learning. The blocking effect represents this sort of efficiency mechanism and refers to the phenomenon in which a novel stimulus is blocked from learning when it is associated with a fully predicted outcome. Although there is sufficient evidence that this effect manifests itself when individuals learn about their own rewards, it remains unclear whether it also does when they learn about others' rewards. We employed behavioral and neuroimaging methods to address this question. We demonstrate that blocking does indeed occur in the social domain and it does so to a similar degree as observed in the individual domain. On the neural level, activations in the medial prefrontal cortex (mPFC) show a specific contribution to blocking and learning-related prediction errors in the social domain. These findings suggest that the efficiency principle that applies to reward learning in the individual domain also applies to that in the social domain, with the mPFC playing a central role in implementing i

The GaAs solar cells with V-grooved emitters

Geometrically structured surfaces have become increasingly important to solar cell efficiency improvements and radiation tolerance. Gallium arsenide solar cells with a V-grooved front surface which demonstrate improved optical coupling and higher short-circuit current compared to planar cells were fabricated. GaAs homojunction cells were fabricated by organometallic chemical vapor deposition (OMCVD) on an n+ substrate. The V-grooves were formed on the surface with an anisotropic etch, and an n-type buffer and p-type emitter were grown by OMCVD, followed by ohmic contacts. Reflectivity measurements show significantly lower reflectance for the microgrooved cell compared to the planar structure. The short circuit current of the V-grooved solar cell is consistently higher than that of the planar controls

Opium addiction in patients with coronary artery disease: A grounded theory study

Background: There are widespread misconceptions about the positive effects of opium on coronary artery disease (CAD). Thus, we performed a study to explore the opium addiction process contributing factors among CAD patients using a grounded theory approach. Methods: The sample comprised 30 addicted CAD patients and their family members, physicians, nurses and friends. Purposive and theoretical sampling was employed; semi-structured interviews were conducted. Coding and constant comparative analysis techniques were as proposed by Strauss and Corbin (1998). Results: The core category was 'Fighting for Survival', comprising three main themes, namely, 'the gateway', 'blowing into the fire' and 'getting stuck in the mud'. Conclusion: Increasing knowledge about the adverse effects of opium on the cardiovascular system would reinforce prevention and rehabilitation measures. Involving patients' family-members in addiction prevention and rehabilitation programs and referring patients to specialized rehabilitation centres could help patients quit opium. Healthcare providers (HCPs) should notice to the effects of opium consumption among CAD patients; nursing care must be holistic in nature. Although opium is stigmatised in Iran, HCPs must treat addicted CAD patients similar to other patients. Nursing students' must be aware of the negative effects of illegal drugs on CAD patients and the misconceptions regarding the positive effects thereof. Any misconceptions must be probed and clarified. Rehabilitation centres must be supervised by cardiologists and HCPs

A V-grooved GaAs solar cell

V-grooved GaAs solar cells promise the benefits of improved optical coupling, higher short-circuit current, and increased tolerance to particle radiation compared to planar cells. A GaAs homojunction cell was fabricated by etching a V-groove pattern into an n epilayer (2.1 x 10 to the 17th power per cu cm) grown by metalorganic chemical vapor deposition (MOCVD) on an n+ substrate (2.8 x 10 to the 18th power per cu cm) and then depositing and MOCVD p epilayer (4.2 x 10 to the 18th power per cu cm). Reflectivity measurements on cells with and without an antireflective coating confirm the expected decrease in reluctance of the microgrooved cell compared to the planar structure. The short circuit current of the V-grooved solar cell was 13 percent higher than that of the planar control

A comparative study of p(+)n and n(+)p InP solar cells made by a closed ampoule diffusion

The purpose was to demonstrate the possibility of fabricating thermally diffused p(+)n InP solar cells having high open-circuit voltage without sacrificing the short circuit current. The p(+)n junctions were formed by closed-ampoule diffusion of Cd through a 3 to 5 nm thick anodic or chemical phosphorus-rich oxide cap layer grown on n-InP:S Czochralski LEC grown substrates. For solar cells made by thermal diffusion the p(+)n configuration is expected to have a higher efficiency than the n(+)p configuration. It is predicted that the AM0, BOL efficiencies approaching 19 percent should be readily achieved providing that good ohmic front contacts could be realized on the p(+) emitters of thickness lower than 1 micron

Kyste epidermoïde intra medullaire: A propos d’un cas

IntroductionLes kystes épidermoïdes sont des tumeurs bénignes, le plus souvent congénitales. Au niveau rachidien la localisation est habituellement intra durale extra médullaire, rarement intra médullaire. Nous rapportons un nouveau cas de kyste épidermoïde intra médullaire, dorsal et discutons l’étiopathogénie, l’épidémiologie, la clinique, les caractéristiques  radiologiques et le traitement neurochirurgical.ObservationUn patient âgé de 16 ans est admis pour une paraparésie spastique progressive évoluant depuis 18 mois, sans troubles sensitifs, avec incontinence urinaire. L’imagerie par résonnance magnétique (IRM) médullaire a objectivé une lésion fusiforme intra médullaire en regard de la vertèbre T12. Elle était hypo intense en T1, hétérogène en T2 avec un fin rehaussement en couronne sur les séquences pondérées T1 après injection de Gadolinium. Le patient a été opéré par voie postérieur. Une myélotomie centrée sur la lésion a été réalisée. On a retrouvé une masse de consistance molle, de couleur blanc nacrée. Une exérèse complète a été réalisée. L’examen anatomopathologique a conclu à un kyste épidermoïde. Les suites post opératoires ont été marquées par une bonne amélioration clinique fonctionnelle (évolution de 6 mois).ConclusionLes kystes épidermoïdes sont des tumeurs bénignes rares exceptionnellement intra médullaire. L’approche diagnostic est établit par l’imagerie par résonance magnétique et le traitement est neurochirurgical. Le pronostic est globalement bon