336 research outputs found

    Adaptive reflection and focusing of Bose-Einstein condensates

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    We report adjustable magnetic `bouncing' and focusing of a dilute 87^{87}Rb Bose gas. Both the condensate production and manipulation are realised using a particularly straight-forward apparatus. The bouncing region is comprised of approximately concentric ellipsoidal magnetic equipotentials with a centre that can be adjusted vertically. We extend, and discuss the limitations of, simple Thomas-Fermi and Monte-Carlo theoretical models for the bouncing, which at present find close agreement with the condensate's evolution. Very strong focusing has been inferred and the observation of atomic matter-wave diffraction should be possible. Prospects look bright for applications in matter-wave atom-optics, due to the very smooth nature of the mirror

    A simple extended-cavity diode laser

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    Operating a laser diode in an extended cavity which provides frequency-selective feedback is a very effective method of reducing the laser's linewidth and improving its tunability. We have developed an extremely simple laser of this type, built from inexpensive commercial components with only a few minor modifications, A 780 nm laser built to this design has an output power of 80 mW, a Linewidth of 350 kHz, and it has been continuously locked to a Doppler-free rubidium transition for several days

    Measurement of the 1s-2s energy interval in muonium

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    Evaluation of the oesophagogastric cancer associated microbiome: a systematic review and quality assessment

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    Objective. Oesophagogastric cancer is the fifth most common cancer worldwide, with poor survival outcomes. The role of bacteria in the pathogenesis of oesophagogastric cancer remains poorly understood. Design. A systematic search identified studies assessing the oesophagogastric cancer microbiome. The primary outcome was to identify bacterial enrichment specific to oesophagogastric cancer. Secondary outcomes included appraisal of the methodology, diagnostic performance of cancer bacteria and the relationship between oral and tissue microbiome. Results. A total of 9295 articles were identified, and 87 studies were selected for analysis. Five genera were enriched in gastric cancer: Lactobacillus, Streptococcus, Prevotella, Fusobacterium and Veillonella. No clear trends were observed in oesophageal adenocarcinoma. Streptococcus, Prevotella and Fusobacterium were abundant in oesophageal squamous cell carcinoma. Functional analysis supports the role of immune cells, localised inflammation and cancer-specific pathways mediating carcinogenesis. STORMS reporting assessment identified experimental deficiencies, considering batch effects and sources of contamination prevalent in low-biomass samples. Conclusions. Functional analysis of cancer pathways can infer tumorigenesis within the cancer–microbe–immune axis. There is evidence that study design, experimental protocols and analytical techniques could be improved to achieve more accurate and representative results. Whole-genome sequencing is recommended to identify key metabolic and functional capabilities of candidate bacteria biomarkers

    Micronutrient deficiency following esophagectomy for cancer of the upper gastrointestinal tract

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    Objectives: For those patients who achieve long-term survival following esophagectomy, altered digestion and malabsorption may lead to a range of adverse gastrointestinal sequelae, including micronutrient deficiencies. The aim of the current study was to determine the prevalence of specific micronutrient deficiencies in patients following esophagectomy. Methods: Levels of vitamin A, vitamin E, vitamin D, vitamin B1, vitamin B12, folate, ferritin, zinc and calcium were measured in a single non-fasting blood sample in patients who has undergone esophagectomy. Findings were compared to both patients who had undergone gastrectomy and an age matched Western control population. Results: Forty-Four patients (33 male, 65.5 ± 10.2 yrs) a median of 26 months (IQR 12-46) following either two or three stage esophagectomy were recruited. Deficiency in one or more micronutrients was observed in 64% of patients who underwent esophagectomy. Micronutrients most commonly deficient following esophagectomy were vitamin D (21%), vitamin B12 (32%), ferritin (16%) and zinc (25%). Compared to patients who underwent gastrectomy, levels of vitamin B12 and red cell folate were significantly lower, and levels of vitamin E were significantly higher in the blood of patients following esophagetomy. Compared to a Western control population the mean levels of vitamins A, E, D and B12, ferritin and zinc were lower in patients following esophagectomy. Conclusion: Micronutrient deficiency is common after esophagectomy affecting two thirds of all patients. Regular screening of vitamin D, vitamin B12, ferritin and Zinc levels should be considered as well as prophylactic supplementation in this patient group to prevent deficiency

    Experimental demonstration of painting arbitrary and dynamic potentials for Bose-Einstein condensates

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    There is a pressing need for robust and straightforward methods to create potentials for trapping Bose-Einstein condensates which are simultaneously dynamic, fully arbitrary, and sufficiently stable to not heat the ultracold gas. We show here how to accomplish these goals, using a rapidly-moving laser beam that "paints" a time-averaged optical dipole potential in which we create BECs in a variety of geometries, including toroids, ring lattices, and square lattices. Matter wave interference patterns confirm that the trapped gas is a condensate. As a simple illustration of dynamics, we show that the technique can transform a toroidal condensate into a ring lattice and back into a toroid. The technique is general and should work with any sufficiently polarizable low-energy particles.Comment: Minor text changes and three references added. This is the final version published in New Journal of Physic
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