635 research outputs found

    Intracranial internal carotid aneurysm causing diplopia

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    Internal carotid intracranial aneurysms are a relatively rare form of intracranial aneurysm that presents with diplopia, retro-orbital pain and unilateral headaches. The symptoms are progressive and the diagnosis should be considered in a patient presenting with these complaints. Underlying hypertension and advanced age are specific risk factors

    Perforated Meckel diverticulum

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    Perforation of a Meckel diverticulum (MD) is a rare complication that can often mimic appendicitis. This case report identifies a child who presented to our Emergency Department (ED) with right lower quadrant abdominal pain, free fluid and air in the abdomen and pelvis, and inflammatory changes visualized on Ultrasonography (US) and computer tomography (CT) scan. In our patient, ruptured appendicitis was suspected, and the diagnosis of ruptured MD was ultimately made by laparoscopy. This case demonstrates that a healthy degree of suspicion for complicated MD should be present when dealing with a questionable diagnosis of appendicitis, particularly in the pediatric population

    Multi-resonant high-Q plasmonic metasurfaces

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    Resonant metasurfaces are devices composed of nanostructured sub-wavelength scatterers that generate narrow optical resonances, enabling applications in filtering, nonlinear optics, and molecular fingerprinting. It is highly desirable for these applications to incorporate such devices with multiple, high-quality-factor resonances; however, it can be challenging to obtain more than a pair of narrow resonances in a single plasmonic surface. Here, we demonstrate a multi-resonant metasurface that operates by extending the functionality of surface lattice resonances, which are the collective responses of arrays of metallic nanoparticles. This device features a series of resonances with high quality factors (Q ~ 40), an order of magnitude larger than what is typically achievable with plasmonic nanoparticles, as well as a narrow free spectral range. This design methodology can be used to better tailor the transmission spectrum of resonant metasurfaces and represents an important step towards the miniaturization of optical devices.Comment: 8 pages, 4 figures, includes MATLAB code in Supplementary Material

    Marine Reserves Shape Seascapes on Scales Visible From Space

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    Marine reserves can effectively restore harvested populations, and ā€˜mega-reservesā€™ increasingly protect large tracts of ocean. However, no method exists of monitoring ecological responses at this large scale. Herbivory is a key mechanism structuring ecosystems, and this consumerā€“resource interaction\u27s strength on coral reefs can indicate ecosystem health. We screened 1372, and measured features of 214, reefs throughout Australia\u27s Great Barrier Reef using high-resolution satellite imagery, combined with remote underwater videography and assays on a subset, to quantify the prevalence, size and potential causes of ā€˜grazing halosā€™. Halos are known to be seascape-scale footprints of herbivory and other ecological interactions. Here we show that these halo-like footprints are more prevalent in reserves, particularly older ones (approx. 40 years old), resulting in predictable changes to reef habitat at scales visible from space. While the direct mechanisms for this pattern are relatively clear, the indirect mechanisms remain untested. By combining remote sensing and behavioural ecology, our findings demonstrate that reserves can shape large-scale habitat structure by altering herbivores\u27 functional importance, suggesting that reserves may have greater value in restoring ecosystems than previously appreciated. Additionally, our results show that we can now detect macro-patterns in reef species interactions using freely available satellite imagery. Low-cost, ecosystem-level observation tools will be critical as reserves increase in number and scope; further investigation into whether halos may help seems warranted. Significance statement: Marine reserves are a widely used tool to mitigate fishing impacts on marine ecosystems. Predicting reserves\u27 large-scale effects on habitat structure and ecosystem functioning is a major challenge, however, because these effects unfold over longer and larger scales than most ecological studies. We use a unique approach merging remote sensing and behavioural ecology to detect ecosystem change within reserves in Australia\u27s vast Great Barrier Reef. We find evidence of changes in reefs\u27 algal habitat structure occurring over large spatial (thousands of kilometres) and temporal (40+ years) scales, demonstrating that reserves can alter herbivory and habitat structure in predictable ways. This approach demonstrates that we can now detect aspects of reefs\u27 ecological responses to protection even in remote and inaccessible reefs globally

    Blockade of Interferon Beta, but Not Interferon Alpha, Signaling Controls Persistent Viral Infection

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    SummaryAlthough type I interferon (IFN-I) is thought to be beneficial against microbial infections, persistent viral infections are characterized by high interferon signatures suggesting that IFN-I signaling may promote disease pathogenesis. During persistent lymphocytic choriomeningitis virus (LCMV) infection, IFNĪ± and IFNĪ² are highly induced early after infection, and blocking IFN-I receptor (IFNAR) signaling promotes virus clearance. We assessed the specific roles of IFNĪ² versus IFNĪ± in controlling LCMV infection. While blockade of IFNĪ² alone does not alter early viral dissemination, it is important in determining lymphoid structure, lymphocyte migration, and anti-viral TĀ cell responses that lead to accelerated virus clearance, approximating what occurs during attenuation of IFNAR signaling. Comparatively, blockade of IFNĪ± was not associated with improved viral control, but with early dissemination of virus. Thus, despite their use of the same receptor, IFNĪ² and IFNĪ± have unique and distinguishable biologic functions, with IFNĪ² being mainly responsible for promoting viral persistence
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