84 research outputs found

    Is there Correlation between Fine Structure and Dark Energy Cosmic Dipoles?

    Full text link
    We present a detailed analysis (including redshift tomography) of the cosmic dipoles in the Keck+VLT quasar absorber and in the Union2 SnIa samples. We show that the fine structure constant cosmic dipole obtained through the Keck+VLT quasar absorber sample at 4.1σ4.1\sigma level is anomalously aligned with the corresponding dark energy dipole obtained through the Union2 sample at 2σ2\sigma level. The angular separation between the two dipole directions is 11.3±11.811.3^\circ \pm 11.8^\circ. We use Monte Carlo simulations to find the probability of obtaining the observed dipole magnitudes with the observed alignment, in the context of an isotropic cosmological model with no correlation between dark energy and fine structure constant α\alpha. We find that this probability is less than one part in 10610^6. We propose a simple physical model (extended topological quintessence) which naturally predicts a spherical inhomogeneous distribution for both dark energy density and fine structure constant values. The model is based on the existence of a recently formed giant global monopole with Hubble scale core which also couples non-minimally to electromagnetism. Aligned dipole anisotropies would naturally emerge for an off-centre observer for both the fine structure constant and for dark energy density. This model smoothly reduces to \lcdm for proper limits of its parameters. Two predictions of this model are (a) a correlation between the existence of strong cosmic electromagnetic fields and the value of α\alpha and (b) the existence of a dark flow on Hubble scales due to the repulsive gravity of the global defect core (`Great Repulser') aligned with the dark energy and α\alpha dipoles. The direction of the dark flow is predicted to be towards the spatial region of lower accelerating expansion. Existing data about the dark flow are consistent with this prediction.Comment: 14 pages 11 figures (two column revtex). Aceepted in Phys. Rev. D (to appear). Significant extensions (mostly on section 4 on the theoretical model), added references, corrected typos. The data, updated mathematica and C program files used for the numerical analysis may be downloaded from http://leandros.physics.uoi.gr/defsdipole

    Natural and Nature-Derived Products Targeting Human Coronaviruses

    Get PDF
    The ongoing pandemic of severe acute respiratory syndrome (SARS), caused by the SARS-CoV-2 human coronavirus (HCoV), has brought the international scientific community before a state of emergency that needs to be addressed with intensive research for the discovery of pharmacological agents with antiviral activity. Potential antiviral natural products (NPs) have been discovered from plants of the global biodiversity, including extracts, compounds and categories of compounds with activity against several viruses of the respiratory tract such as HCoVs. However, the scarcity of natural products (NPs) and small-molecules (SMs) used as antiviral agents, especially for HCoVs, is notable. This is a review of 203 publications, which were selected using PubMed/MEDLINE, Web of Science, Scopus, and Google Scholar, evaluates the available literature since the discovery of the first human coronavirus in the 1960s; it summarizes important aspects of structure, function, and therapeutic targeting of HCoVs as well as NPs (19 total plant extracts and 204 isolated or semi-synthesized pure compounds) with anti-HCoV activity targeting viral and non-viral proteins, while focusing on the advances on the discovery of NPs with anti-SARS-CoV-2 activity, and providing a critical perspective

    Parametrization for the Scale Dependent Growth in Modified Gravity

    Full text link
    We propose a scale dependent analytic approximation to the exact linear growth of density perturbations in Scalar-Tensor (ST) cosmologies. In particular, we show that on large subhorizon scales, in the Newtonian gauge, the usual scale independent subhorizon growth equation does not describe the growth of perturbations accurately, as a result of scale-dependent relativistic corrections to the Poisson equation. A comparison with exact linear numerical analysis indicates that our approximation is a significant improvement over the standard subhorizon scale independent result on large subhorizon scales. A comparison with the corresponding results in the Synchronous gauge demonstrates the validity and consistency of our analysis.Comment: 10 pages, 5 figures. Minor modifications and references added to match published versio

    Aesthetics of protest: An examination of the photojournalistic approach to protest imagery

    Get PDF
    Images of protests and demonstrations are crucial to both social movements and protesters who wish to communicate their identity and their messages to wider audiences. However, the photographing of such political events by press photographers is a complex process. The current analysis focuses on questions of aesthetics surrounding issues of visuality regarding protests and demonstrations. Based on empirical data from 17 semi-structured in-depth interviews with Greek photojournalists, this paper examines what is photographed during a protest and how this is affected by the photojournalists’ aesthetic criteria. Drawing on scholarly work on photojournalism (Ritchin and Åker) and photography (Sontag), this article discusses that besides the presumption in the principal of recording reality, photojournalists’ practice is also infused with subjective language and influenced by art photographers’ techniques. Thereupon, the main argument of this paper is that the employment of hybridized photographing practices by photojournalists can have an impact upon their visual decisions with regard to what and how is photographed during a protest. The product of such practices is usually high quality, captivating images with apparent affective qualities

    Use of sealants in pancreatic surgery: Critical appraisal of the literature

    No full text
    Background/Aims: Fibrin sealants containing both fibrin and thrombin have been used to control bleeding, reinforce suture lines and enhance tissue healing. However, the literature provides contradictory results. Methods: A systematic literature search was performed to determine the use of fibrin sealants in pancreatic surgery. These articles were then critically appraised according to their methodologies, outcomes and conclusions. Results: Twenty-four studies were found, including 6 controlled randomized trials. Of these, 16 studies were analyzed. Many methodological flaws and lack of consistency in definitions were found, making comparisons between studies difficult if not impossible. Conclusion: Because of the heterogeneity and lack of high-level evidence, the current literature does not allow us any conclusion: neither is there proof that fibrin sealants are of any real utility in pancreatic surgery, nor that they do not work. Further large-scale controlled trials are necessary before concluding that they do or do not provide any advantages in pancreatic surgery. Copyright © 2009 S. Karger AG, Basel

    Meta-analysis of endoscopy and surgery versus surgery alone for common bile duct stones with the gallbladder in situ

    No full text
    Background: There is no clear consensus on the better therapeutic approach (endoscopic versus surgical) to choledocholithiasis. This study is a meta-analysis of the available evidence. Methods: A search of the Medline and ISI databases identified 12 studies that met the inclusion criteria for data extraction. The analysis was performed using a random-effects model. The outcome was calculated as an odds ratio (OR) or relative risk (RR) with 95 per cent confidence intervals (c.i.). Results: Outcomes of 1357 patients were studied. There was no significant difference in successful duct clearance (OR 0.85 (95 per cent c.i. 0.64 to 1.12); P = 0.250), mortality (RR 1.79 (95 per cent c.i. 0.66 to 4.83); P = 0.250), total morbidity (RR 0.89 (95 per cent 0.71 c.i. to 1.13); P = 0.350), major morbidity (RR 1.34 (95 per cent c.i. 0.92 to 1.97); P = 0.130) or need for additional procedures (OR 1.37 (95 per cent c.i. 0.82 to 2.29); P = 0.230) between the endoscopic and surgical groups. There was also no significant difference between the endoscopic and laparoscopic surgery groups. Conclusion: Both approaches have similar outcomes, and treatment should be determined by local resources and expertise

    Laparoscopic fenestration for the treatment of patients with severe adult polycystic liver disease

    No full text
    Background: The purpose of this study was to present our experience in laparoscopic fenestration for patients with severe symptomatic adult polycystic liver disease (APLD), analyze its feasibility, and evaluate its immediate and mid-term outcome. Methods: Between January 2000 and January 2002, 9 patients underwent laparoscopic fenestration for symptomatic APLD in our laparoendoscopic unit. All patients had both liver lobes affected with Multiple cysts, whereas type If disease (present in 8 patients) was not a contraindication for the procedure. The results were retrospectively evaluated. Results: Conversion to laparotomy was required in 1 patient who was submitted to a second laparoscopic procedure (2 years postoperatively) after being admitted to our department with sepsis. Complete regression of symptoms was achieved in 7 of our patients (77.8 %). One death occurred because of acute renal failure established 5 weeks after the patient was discharged. During a mean follow-up of 25.8 months, 2 patients presented with recurrence of their symptoms (22.2 %). One of them was reoperated on; both of them remain symptom free 14 months postoperatively. Conclusions: Laparoscopic fenestration appears to be a useful and effective approach for severe APLD. It is associated with short hospital stay and a significant symptom-free period. Despite the reported morbidity, aggressive and meticulous deroofing of as many cysts as possible can be successfully applied for carefully Selected patients with type II disease. (C) 2005 Excerpta Medica Inc. All rights reserved
    corecore