1,338 research outputs found

    Agenesis of the Gallbladder: A Phantom Menace

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    Objective: Gallbladder agenesis (GBA) is a rare congenital disorder with an estimated incidence of about 0.06%. Despite the absence of a gallbladder, these patients may present with symptoms mimicking biliary colic or cholecystitis. Ultrasound findings and liver function tests are often misleading. Some of these patients undergo laparoscopy without successful identification of gallbladder and paradoxically report symptom relief. Case: We present a case of GBA in a 54 year-old female, who presented with right-sided abdominal pain. The clinical history and examination were consistent with biliary colic. Initial investigations, including liver function tests, upper endoscopy and ultrasound did not demonstrate upper gastrointestinal pathology and did not clearly identify a gallbladder. Subsequent HIDA scan and CT of the abdomen did not visualize a gallbladder. An MRCP confirmed gallbladder agenesis. The patient was managed conservatively and was symptom free on discharge and follow-up. Discussion: We wish to highlight four learning points: 1. Patients with gallbladder agenesis often present with biliary symptoms. 2. Ultrasound and CT of the liver may not always identify this anomaly. 3. MRCP is the gold standard for making a diagnosis of gall- bladder agenesis. 4. Surgeons must have a high index of suspicion of GBA when the gallbladder is poorly visualized or not identified on ultrasound.

    Computational Controversy

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    Climate change, vaccination, abortion, Trump: Many topics are surrounded by fierce controversies. The nature of such heated debates and their elements have been studied extensively in the social science literature. More recently, various computational approaches to controversy analysis have appeared, using new data sources such as Wikipedia, which help us now better understand these phenomena. However, compared to what social sciences have discovered about such debates, the existing computational approaches mostly focus on just a few of the many important aspects around the concept of controversies. In order to link the two strands, we provide and evaluate here a controversy model that is both, rooted in the findings of the social science literature and at the same time strongly linked to computational methods. We show how this model can lead to computational controversy analytics that have full coverage over all the crucial aspects that make up a controversy.Comment: In Proceedings of the 9th International Conference on Social Informatics (SocInfo) 201

    The (pseudo)issue of the conformal frame revisited

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    The issue of the equivalence between Jordan and Einstein conformal frames in scalar-tensor gravity is revisited, with emphasis on implementing running units in the latter. The lack of affine parametrization for timelike worldlines and the cosmological constant problem in the Einstein frame are clarified, and a paradox in the literature about cosmological singularities appearing only in one frame is solved. While, classically, the two conformal frames are physically equivalent, they seem to be inequivalent at the quantum level.Comment: 29 pages, latex, to appear in Phys. Rev.

    Resolved structure in the nuclear region of the ultraluminous infrared galaxy Mrk 273

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    We have studied the core morphology of the ultraluminous infrared galaxy Mrk 273 by combining a high-resolution adaptive optics near-infrared image with an optical image from the Hubble Space Telescope and interferometric radio continuum data, all at spatial resolutions of 150 mas or better. The near-infrared image reveals that the nucleus has two main components, both of which have radio counterparts. The strongest component (N) shows very similar extended structure in the radio and near-infrared. It has a flat radio spectrum and is resolved into a double-lobed structure (Ne; Nw), with a separation of 90\pm5 mas (70 parsec). A similar structure is detected in the near-infrared. We identify this component as the location of the active nucleus. The second component (SW), strong in the near-infrared but relatively weak in the radio, is located 1\sim1 arcsecond to the southwest. We interpret this as an obscured starburst region associated with the merger. The radio continuum images show a third, strong, component (SE) which has previously been interpreted as a second nucleus. However, it shows no associated optical or near-infrared emission, suggesting that it is in fact a background source.Comment: 8 pages, Latex. 4 postscript files. Better quality version of figure 1 available from ftp://star.herts.ac.uk/pub/Knapen/mrk273 . Accepted, ApJ Letter

    Limited Lifespan of Fragile Regions in Mammalian Evolution

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    An important question in genome evolution is whether there exist fragile regions (rearrangement hotspots) where chromosomal rearrangements are happening over and over again. Although nearly all recent studies supported the existence of fragile regions in mammalian genomes, the most comprehensive phylogenomic study of mammals (Ma et al. (2006) Genome Research 16, 1557-1565) raised some doubts about their existence. We demonstrate that fragile regions are subject to a "birth and death" process, implying that fragility has limited evolutionary lifespan. This finding implies that fragile regions migrate to different locations in different mammals, explaining why there exist only a few chromosomal breakpoints shared between different lineages. The birth and death of fragile regions phenomenon reinforces the hypothesis that rearrangements are promoted by matching segmental duplications and suggests putative locations of the currently active fragile regions in the human genome
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