102 research outputs found

    Structured illumination microscopy using micro-pixellated light-emitting diodes

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    Structured illumination is a flexible and economical method of obtaining optical sectioning in wide-field microscopy [1]. In this technique the illumination system is modified to project a single-spatial frequency grid pattern onto the sample [2, 3]. The pattern can only be resolved in the focal plane and by recording images for different transverse grid positions (or phases) an image of the in-focus parts of the object can be calculated. Light emitting diodes (LEDs) are becoming increasingly popular for lighting and illumination systems due to their low cost, small dimensions, low coherence, uniform illumination, high efficiency and long lifetime. These properties, together with recent developments in high brightness, ultraviolet operation and microstructured emitter design offer great potential for LEDs as light sources for microscopy. In this paper we demonstrate a novel structured illumination microscope using a blue micro-structured light emitting diode as the illumination source. The system is potentially very compact and has no-moving-parts

    A Model for the Stray Light Contamination of the UVCS Instrument on SOHO

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    We present a detailed model of stray-light suppression in the spectrometer channels of the Ultraviolet Coronagraph Spectrometer (UVCS) on the SOHO spacecraft. The control of diffracted and scattered stray light from the bright solar disk is one of the most important tasks of a coronagraph. We compute the fractions of light that diffract past the UVCS external occulter and non-specularly pass into the spectrometer slit. The diffracted component of the stray light depends on the finite aperture of the primary mirror and on its figure. The amount of non-specular scattering depends mainly on the micro-roughness of the mirror. For reasonable choices of these quantities, the modeled stray-light fraction agrees well with measurements of stray light made both in the laboratory and during the UVCS mission. The models were constructed for the bright H I Lyman alpha emission line, but they are applicable to other spectral lines as well.Comment: 19 pages, 5 figures, Solar Physics, in pres

    One-neutron transfer study of Xe 137 and systematics of 13/ 21+ and 13/ 22+ levels in N=83 nuclei

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    Excited states in Xe137 have been studied by using the near-barrier single-neutron transfer reactions C13(Xe136,C12γ)Xe137 and Be9(Xe136,Be8γ)Xe137 in inverse kinematics. Particle-γ and particle-γγ coincidence measurements have been performed with the Phoswich Wall and Digital Gammasphere detector arrays. Evidence is found for a 13/22+ level (E=3137keV) and for additional high-lying 3/2- and 5/2- states. The results are discussed in the framework of realistic shell-model calculations. These calculations are also extended to the 13/21+ and 13/22+ levels in the N=83 isotonic chain. They indicate that there is a need for a value of the neutron 0i13/2 single-particle energy (ESPE=2366keV) lower than the one proposed in the literature. It is also demonstrated that the population patterns of the j=±1/2 single-particle states in Xe137 are different for the two targets used in these measurements and the implications of this effect are addressed

    Association studies of up to 1.2 million individuals yield new insights into the genetic etiology of tobacco and alcohol use

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    Tobacco and alcohol use are leading causes of mortality that influence risk for many complex diseases and disorders 1 . They are heritable 2,3 and etiologically related 4,5 behaviors that have been resistant to gene discovery efforts 6–11 . In sample sizes up to 1.2 million individuals, we discovered 566 genetic variants in 406 loci associated with multiple stages of tobacco use (initiation, cessation, and heaviness) as well as alcohol use, with 150 loci evidencing pleiotropic association. Smoking phenotypes were positively genetically correlated with many health conditions, whereas alcohol use was negatively correlated with these conditions, such that increased genetic risk for alcohol use is associated with lower disease risk. We report evidence for the involvement of many systems in tobacco and alcohol use, including genes involved in nicotinic, dopaminergic, and glutamatergic neurotransmission. The results provide a solid starting point to evaluate the effects of these loci in model organisms and more precise substance use measures

    Machine Learning in Ecosystem Informatics

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    The Impact of Body Mass Index on Patient Reported Outcome Measures (Proms) and Complications Following Primary Hip Replacement

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    Influence of BMI upon patient outcomes and complications following THA was examined across a national cohort of patients. Outcomes were compared by BMI groups (19.0–29.9 kg/m2 [reference], 30.0–34.9 kg/m2 [obese class I], 35.0 kg/m2+ [obese class II/III]), adjusted for case-mix differences. Obese class I patients had a significantly smaller improvement in OHS (18.9 versus 20.5, P < 0.001) and a greater risk of wound complications (odds ratio [OR] = 1.57, P = 0.006). For obese class II/III patients, there were significantly smaller improvements in OHS and EQ-5D index (P < 0.001), and greater risk of wound complications (P = 0.006), readmission (P = 0.001) and reoperation (P = 0.003). Large improvements in patient outcomes were seen irrespective of BMI, although improvements were marginally smaller and complication rates higher in obese patients

    Revision and analysis of anglerfish (Lophius spp.) landing statistics for England and Wales

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