1,437 research outputs found
Author response: Sensitivity to image recurrence across eye-movement-like image transitions through local serial inhibition in the retina
No full textStandard models of stimulus encoding in the retina postulate that image presentations activate neurons according to the increase of preferred contrast inside the receptive field. During natural vision, however, images do not arrive in isolation, but follow each other rapidly, separated by sudden gaze shifts. We here report that, contrary to standard models, specific ganglion cells in mouse retina are suppressed after a rapid image transition by changes in visual patterns across the transition, but respond with a distinct spike burst when the same pattern reappears. This sensitivity to image recurrence depends on opposing effects of glycinergic and GABAergic inhibition and can be explained by a circuit of local serial inhibition. Rapid image transitions thus trigger a mode of operation that differs from the processing of simpler stimuli and allows the retina to tag particular image parts or to detect transition types that lead to recurring stimulus patterns
Assessment of motion of a swing leg and gait rehabilitation with a gravity balancing exoskeleton.
No full textEndoscopic Vein Harvesting Is Associated With Increased Endothelial Microparticle Secretion:A Randomised Ex-Vivo Analysis
No full textObjectives: Endoscopic vein harvesting (EVH) for coronary artery bypass graft surgery has been associated with both positive and negative clinical outcome in a range of studies. In the worst cases, relationships with increased occlusion, myocardial infarction and mortality have been described. EVH could induce endothelial damage leading to loss of graft function. In an attempt to assess endothelial integrity, this study was designed to compare endothelial injury using endothelial microparticle (EMP) secretion as a sensitive marker of dysfunction in vessels harvested using endoscopic versus standard techniques.Methods: A prospective randomised and technician-blinded study design was used to compare standard open technique (SOT, n = 10) vs EVH (n = 5). Once the vein had been harvested, 2 cm was cut after being filled with heparinised patient serum and clipped on either end. All the solution in the vein lumen was washed out using PBS and analysed using flow cytometry to quantify EMPs.Results: There were significantly more Annexin V + CD31 + EMPs in the EVH group compared to the SOT group (mean number of events = 4558.4 vs 86.5, P = 0.001), and also a significant increase in Annexin V + MPs in the EVH group (mean number of events = 4558.4 vs 1238.3, P = 0.027).Conclusion: In this ex-vivo study, EMP secretion was elevated in vessels harvested using endoscopic compared to standard open techniques, which is indicative of endothelial injury. This could contribute to the negative associations with EVH. Long-term clinical data is clearly warranted to translate these findings
Gait Training following stroke: A pilot study combining a gravity-balanced orthosis, functional electrical stimulation and visual feedback.
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The molecular diagnosis of Pneumocystis pneumonia in children using nasopharyngeal aspirate samples
No full textPneumocystis pneumonia (PCP) is an important opportunistic infection caused by thefungus Pneumocystis jirovecii. The incidence of PCP in sub-Saharan Africa is on theincrease. This is due to the progression of the HIV-pandemic and limited access to healthcare facilities, specific highly active anti-retroviral therapy and chemoprophylaxis. It is a major cause of hospitalization and mortality in HIV-infected children with in-hospital case-fatality rates ranging from 20-63%
Metamaterial enhancement of metal-halide perovskite luminescence
No full textMetal-halide perovskites are rapidly emerging as solution-processable optical materials for light-emitting applications. Here, we adopt a plasmonic metamaterial approach to enhance photoluminescence emission and extraction of methylammonium lead iodide (MAPbI3) thin films based on the Purcell effect. We show that hybridization of the active metal-halide film with resonant nanoscale sized slits carved into a gold film can yield more than 1 order of magnitude enhancement of luminescence intensity and nearly 3-fold reduction of luminescence lifetime corresponding to a Purcell enhancement factor of more than 300. These results show the effectiveness of resonant nanostructures in controlling metal-halide perovskite light emission properties over a tunable spectral range, a viable approach toward highly efficient perovskite light-emitting devices and single-photon emitter
Advances in label-free optical biosensing: direct comparison of whispering gallery mode sensors with surface plasmon resonance
No full textPaper presented at: Single Molecule Spectroscopy and Imaging Technical Conference, 19-21 January 2008, San Jose, California, USA. Proceedings of SPIE, v. 6862Whispering gallery modes (WGM) in fluorescent dielectric microcavities have recently become an attractive alternative to state-of-the-art label-free optical biosensors due to their high sensitivity to molecular adsorption and their ease of operation under a variety of environmental conditions. In particular the true microscopic dimension of the sensor as well as its purely radiative control without any need for external coupling opens new opportunities for label-free biosensing on microscopic scale. While these are obvious advantages, a direct comparison of the performance of WGM biosensors with well-established techniques of known high sensitivity, such as surface plasmon resonance sensors, has not been undertaken to date, thus obscuring the opportunities of the newly rising approach. We have therefore studied the performance of both WGM biosensors and a commercial SPR sensor using a selection of specifically and non-specifically binding biomolecules in-situ and under same conditions. The WGM biosensors consist of 10 μm dye-doped polystyrene beads immobilized in a flow cell. The performance of the two techniques is compared in view of the efficiency and sensitivity towards detection of both model interaction pairs (e.g. biotin/Streptavidin) and specific interaction pairs such as antigen-antibody with a lower degree of interaction affinities.A. François, S. Krishnamoorthy, M. Himmelhau
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