65 research outputs found

    Acute esotropia in the setting of heroin withdrawal

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    Acute onset of concomitant esotropia presenting with diplopia can be seen in the setting of heroin withdrawal. We report a case of acute esotropia in a young white male during heroin withdrawal. A sudden onset of eye deviation is usually considered an ominous sign and patients are subjected to a multitude of diagnostic tests and investigations. Acute esotropia in the setting of heroin withdrawal is typically self-limiting. This case presentation can increase the awareness among physicians for a timely diagnosis, and prevent unnecessary diagnostic testing and further consultations.Includes bibliographical reference

    Enhanced photoactivity and hydrogen generation of LaFeO 3 photocathode by plasmonic silver nanoparticle incorporation

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    This is the author accepted manuscript. The final version is available from ACS via the DOI in this record.A plasmonic LaFeO3-Ag (LFO-Ag) photocathode was synthesised by incorporating Ag nanoparticles to excite surface plasmon resonances (SPR) for enhanced light harvesting to drive photoelectrochemical (PEC) hydrogen evolution. The Ag nanoparticles were modelled using finite difference time domain (FDTD) simulations and the results show an optimal dimension of 50-80 nm for SPR enhancement. Nanostructured LFO films were prepared by a novel and inexpensive spray pyrolysis method and the Ag nanoparticles were dispersed uniformly on to the films by simple spin coating method. The LFO-Ag photocathode exhibited strong light absorption capability and high current density, twice that than of its untreated counterpart. This subsequently led to enhanced PEC hydrogen evolution, doubling the volume of hydrogen generated compared to untreated LFO. The enhancement is ascribed to the strong SPR effect and the synergy between the Ag nanoparticles and nanostructured LFO photocathode.We acknowledge UKIERI-DST2016-17-0089 project and Engineering and Physical Science Research Council, UK (EPSRC) under the research grant EP/R512801/1 for financial support. A.E. and S.S. would like to thank the Council of Scientific and Industrial Research (CSIR) for the award of Senior Research Fellowship. NSG Pilkington Glass Ltd. is acknowledged for kindly providing the FTO substrates for this work

    Experimental investigation of bifurcations in a thermoacoustic engine

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    In this study, variation in the characteristics of the pressure oscillations in a thermoacoustic engine is explored as the input heat flux is varied. A bifurcation diagram is plotted to study the variation in the qualitative behavior of the acoustic oscillations as the input heat flux changes. At a critical input heat flux (60 Watt), the engine begins to produce acoustic oscillations in its fundamental longitudinal mode. As the input heat flux is increased, incommensurate frequencies appear in the power spectrum. The simultaneous presence of incommensurate frequencies results in quasiperiodic oscillations. On further increase of heat flux, the fundamental mode disappears and second mode oscillations are observed. These bifurcations in the characteristics of the pressure oscillations are the result of nonlinear interaction between multiple modes present in the thermoacoustic engine. Hysteresis in the bifurcation diagram suggests that the bifurcation is subcritical. Further, the qualitative analysis of different dynamic regimes is performed using nonlinear time series analysis. The physical reason for the observed nonlinear behavior is discussed. Suggestions to avert the variations in qualitative behavior of the pressure oscillations in thermoacoustic engines are also provided

    Dynamic saturation in semiconductor optical amplifiers: accurate model, role of carrier density, and slow light

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    We developed an improved model in order to predict the RF behavior and the slow light properties of the SOA valid for any experimental conditions. It takes into account the dynamic saturation of the SOA, which can be fully characterized by a simple measurement, and only relies on material fitting parameters, independent of the optical intensity and the injected current. The present model is validated by showing a good agreement with experiments for small and large modulation indices.Comment: 9 pages, 5 figure

    A unified global investigation on the spectral effects of soiling losses of PV glass substrates: preliminary results

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    This is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordThe present work reports on the initial results of an international collaboration aiming to investigate the spectral effects of soiling losses. Identical glass coupons have been exposed outdoors for eight weeks in different locations worldwide, and weekly direct and hemispherical transmittance (T%) measurements are compared. Maximum losses as high as 7% and 50% in hemispherical and direct transmittance, respectively, have been found during the 8-week outdoor exposure. At the end of the data collection, a preliminary analysis of the spectral impact of soiling has been performed. The results show that the blue end of the spectrum is more affected and that lower hemispherical T% correlate to larger area covered by particles.Engineering and Physical Sciences Research Council (EPSRC)US Department of Energ

    Controllable ultra-broadband slow light in a warm Rubidium vapor

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    We study ultra-broadband slow light in a warm Rubidium vapor cell. By working between the D1 and D2 transitions, we find a several-nm window centered at 788.4 nm in which the group index is highly uniform and the absorption is small (<1%). We demonstrate that we can control the group delay by varying the temperature of the cell, and observe a tunable fractional delay of 18 for pulses as short as 250 fs (6.9 nm bandwidth) with a fractional broadening of only 0.65 and a power leakage of 55%. We find that a simple theoretical model is in excellent agreement with the experimental results. Using this model, we discuss the impact of the pulse's spectral characteristics on the distortion it incurs during propagation through the vapor.Comment: The first two authors contributed equally to this wor

    A unified global investigation on the spectral effects of soiling losses of PV glass substrates: preliminary results.

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    The present work reports on the initial results of an international collaboration aiming to investigate the spectral effects of soiling losses. Identical glass coupons have been exposed outdoors for eight weeks in different locations worldwide, and weekly direct and hemispherical transmittance (T%) measurements are compared. Maximum losses as high as 7% and 50% in hemispherical and direct transmittance, respectively, have been found during the 8-week outdoor exposure. At the end of the data collection, a preliminary analysis of the spectral impact of soiling has been performed. The results show that the blue end of the spectrum is more affected and that lower hemispherical T% correlate to larger area covered by particles

    Modelling photovoltaic soiling losses through optical characterization

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    The accumulation of soiling on photovoltaic (PV) modules affects PV systems worldwide. Soiling consists of mineral dust, soot particles, aerosols, pollen, fungi and/or other contaminants that deposit on the surface of PV modules. Soiling absorbs, scatters, and reflects a fraction of the incoming sunlight, reducing the intensity that reaches the active part of the solar cell. Here, we report on the comparison of naturally accumulated soiling on coupons of PV glass soiled at seven locations worldwide. The spectral hemispherical transmittance was measured. It was found that natural soiling disproportionately impacts the blue and ultraviolet (UV) portions of the spectrum compared to the visible and infrared (IR). Also, the general shape of the transmittance spectra was similar at all the studied sites and could adequately be described by a modified form of the Ångström turbidity equation. In addition, the distribution of particles sizes was found to follow the IEST-STD-CC 1246E cleanliness standard. The fractional coverage of the glass surface by particles could be determined directly or indirectly and, as expected, has a linear correlation with the transmittance. It thus becomes feasible to estimate the optical consequences of the soiling of PV modules from the particle size distribution and the cleanliness value

    The Gene Ontology knowledgebase in 2023

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    The Gene Ontology (GO) knowledgebase (http://geneontology.org) is a comprehensive resource concerning the functions of genes and gene products (proteins and noncoding RNAs). GO annotations cover genes from organisms across the tree of life as well as viruses, though most gene function knowledge currently derives from experiments carried out in a relatively small number of model organisms. Here, we provide an updated overview of the GO knowledgebase, as well as the efforts of the broad, international consortium of scientists that develops, maintains, and updates the GO knowledgebase. The GO knowledgebase consists of three components: (1) the GO-a computational knowledge structure describing the functional characteristics of genes; (2) GO annotations-evidence-supported statements asserting that a specific gene product has a particular functional characteristic; and (3) GO Causal Activity Models (GO-CAMs)-mechanistic models of molecular "pathways" (GO biological processes) created by linking multiple GO annotations using defined relations. Each of these components is continually expanded, revised, and updated in response to newly published discoveries and receives extensive QA checks, reviews, and user feedback. For each of these components, we provide a description of the current contents, recent developments to keep the knowledgebase up to date with new discoveries, and guidance on how users can best make use of the data that we provide. We conclude with future directions for the project
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