2,652 research outputs found

    Searches for Gravitational Waves from Binary Neutron Stars: A Review

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    A new generation of observatories is looking for gravitational waves. These waves, emitted by highly relativistic systems, will open a new window for ob- servation of the cosmos when they are detected. Among the most promising sources of gravitational waves for these observatories are compact binaries in the final min- utes before coalescence. In this article, we review in brief interferometric searches for gravitational waves emitted by neutron star binaries, including the theory, instru- mentation and methods. No detections have been made to date. However, the best direct observational limits on coalescence rates have been set, and instrumentation and analysis methods continue to be refined toward the ultimate goal of defining the new field of gravitational wave astronomy.Comment: 30 pages, 5 Figures, to appear in "Short-Period Binary Stars: Observations, Analyses, and Results", Ed.s Eugene F. Milone, Denis A. Leahy, David W. Hobil

    CAS9 transcriptional activators for target specificity screening and paired nickases for cooperative genome engineering

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    Prokaryotic type II CRISPR-Cas systems can be adapted to enable targeted genome modifications across a range of eukaryotes.1–7. Here we engineer this system to enable RNA-guided genome regulation in human cells by tethering transcriptional activation domains either directly to a nuclease-null Cas9 protein or to an aptamer-modified single guide RNA (sgRNA). Using this functionality we developed a novel transcriptional activation–based assay to determine the landscape of off-target binding of sgRNA:Cas9 complexes and compared it with the off-target activity of transcription activator–like (TAL) effector proteins8, 9. Our results reveal that specificity profiles are sgRNA dependent, and that sgRNA:Cas9 complexes and 18-mer TAL effector proteins can potentially tolerate 1–3 and 1–2 target mismatches, respectively. By engineering a requirement for cooperativity through offset nicking for genome editing or through multiple synergistic sgRNAs for robust transcriptional activation, we suggest methods to mitigate off-target phenomena. Our results expand the versatility of the sgRNA:Cas9 tool and highlight the critical need to engineer improved specificity

    The efficacy of four-slice helical CT in evaluating pancreatic trauma: a single institution experience

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    <p>Abstract</p> <p>Study objective</p> <p>To assess the efficacy of computed tomography (CT) in evaluating patients with pancreatic trauma.</p> <p>Methods</p> <p>We undertook a retrospective review of all blunt trauma patients admitted to the Chi-Mei Medical Center from January 2004 to June 2006. Every patients underwent abdominal CT scan in emergency department and the CT scans were obtained with a four-slice helical CT. Diagnosis of a pancreatic injury in these patients was by surgical observation or by CT findings. Radiographic pancreatic injuries were classified as deep or superficial lesions. Deep lesions were defined as the hematomas or lacerations >50% thickness of the pancreas. Superficial lesions were described as the hematomas or lacerations <50% thickness of the pancreas; pancreatic edema; and focal fluid accumulation around the pancreas</p> <p>Results</p> <p>Nineteen patients with pancreatic trauma, fourteen males and five females, average age 40.6 ± 21.4 years, were included. Most patients (73.7%) with pancreatic trauma had associated organ injuries. CT was performed in all patients and laparotomy in 14 patients. CT was 78.9% sensitive in detecting pancreatic trauma. All deep pancreatic lesions revealed on CT required surgical treatment, and complication was discovered in two patients undergoing delayed surgery. Superficial lesions were managed conservatively.</p> <p>Conclusion</p> <p>Four-slice helical CT can detect most pancreatic trauma and provide practical therapeutic guidance. Delayed operation might result in complications and is associated with prolonged hospital stays.</p

    Fermi Gamma-ray Imaging of a Radio Galaxy

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    The Fermi Gamma-ray Space Telescope has detected the gamma-ray glow emanating from the giant radio lobes of the radio galaxy Centaurus A. The resolved gamma-ray image shows the lobes clearly separated from the central active source. In contrast to all other active galaxies detected so far in high-energy gamma-rays, the lobe flux constitutes a considerable portion (>1/2) of the total source emission. The gamma-ray emission from the lobes is interpreted as inverse Compton scattered relic radiation from the cosmic microwave background (CMB), with additional contribution at higher energies from the infrared-to-optical extragalactic background light (EBL). These measurements provide gamma-ray constraints on the magnetic field and particle energy content in radio galaxy lobes, and a promising method to probe the cosmic relic photon fields.Comment: 27 pages, includes Supplementary Online Material; corresponding authors: C.C. Cheung, Y. Fukazawa, J. Knodlseder, L. Stawar

    Pesticides and Parkinson’s Disease—Is There a Link?

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    Parkinson’s disease (PD) is an idiopathic disease of the nervous system characterized by progressive tremor, bradykinesia, rigidity, and postural instability. It has been postulated that exogenous toxicants, including pesticides, might be involved in the etiology of PD. In this article we present a comprehensive review of the published epidemiologic and toxicologic literature and critically evaluate whether a relationship exists between pesticide exposure and PD. From the epidemiologic literature, there does appear to be a relatively consistent relationship between pesticide exposure and PD. This relationship appears strongest for exposure to herbicides and insecticides, and after long durations of exposure. Toxicologic data suggest that paraquat and rotenone may have neurotoxic actions that potentially play a role in the development of PD, with limited data for other pesticides. However, both the epidemiology and toxicology studies were limited by methodologic weaknesses. Particular issues of current and future interest include multiple exposures (both pesticides and other exogenous toxicants), developmental exposures, and gene–environment interactions. At present, the weight of evidence is sufficient to conclude that a generic association between pesticide exposure and PD exists but is insufficient for concluding that this is a causal relationship or that such a relationship exists for any particular pesticide compound or combined pesticide and other exogenous toxicant exposure
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