1,250 research outputs found

    Molecular collisions. 16: Comparison of GPS with classical trajectory calculations of rotational inelasticity for the Ar-N2 system

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    Comparison of generalized phase shift treatment with classical trajectory calculations of rotational inelasticity cross sections of Ar-N2 scatterin

    Nova Geminorum 1912 and the Origin of the Idea of Gravitational Lensing

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    Einstein's early calculations of gravitational lensing, contained in a scratch notebook and dated to the spring of 1912, are reexamined. A hitherto unknown letter by Einstein suggests that he entertained the idea of explaining the phenomenon of new stars by gravitational lensing in the fall of 1915 much more seriously than was previously assumed. A reexamination of the relevant calculations by Einstein shows that, indeed, at least some of them most likely date from early October 1915. But in support of earlier historical interpretation of Einstein's notes, it is argued that the appearance of Nova Geminorum 1912 (DN Gem) in March 1912 may, in fact, provide a relevant context and motivation for Einstein's lensing calculations on the occasion of his first meeting with Erwin Freundlich during a visit in Berlin in April 1912. We also comment on the significance of Einstein's consideration of gravitational lensing in the fall of 1915 for the reconstruction of Einstein's final steps in his path towards general relativity.Comment: 31 p

    Disruption of a Yeast ADE6 Gene Homolog in Ustilago maydis

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    A putative homolog of the Sacharromyces cereviseae ADE6 and Escherichia coli purL genes is identified near a multigenic complex, which contains two genes, sid1 and sid2, involved in a siderophore biosynthetic pathway inUstilago maydis. The putative ADE6 homolog was mutated by targeted gene disruption. The resulting mutant strains demonstrated a requirement for exogenous adenine, indicating that the U. maydis ade6 homolog is required for purine biosynthesis

    Oral ibandronate for the treatment of metastatic bone disease in breast cancer: efficacy and safety results from a randomized, double-blind, placebo-controlled trial

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    Background: We report the first results of a randomized trial assessing a new oral aminobisphosphonate, ibandronate, in patients with bone metastases from breast cancer. Patients and methods: Patients (n = 435) received placebo, or oral ibandronate 20 mg or 50 mg once-daily for 96 weeks. The primary efficacy measure was the number of 12-week periods with new bone complications [skeletal morbidity period rate (SMPR)]. Multivariate Poisson regression analysis assessed the relative risk reduction of skeletal-related events. Secondary efficacy analyses included bone pain and analgesic use. Adverse events were monitored. Results: SMPR was significantly reduced with oral ibandronate [placebo 1.2, 20 mg group 0.97 (P = 0.024), 50 mg group 0.98 (P = 0.037)]. Ibandronate 50 mg significantly reduced the need for radiotherapy (P = 0.005 versus placebo). The relative risk of skeletal events was reduced by 38% (20 mg dose) and 39% (50 mg dose) versus placebo (P = 0.009 and P = 0.005). The tolerability profile of ibandronate was similar to placebo. Conclusions: Oral ibandronate is an effective and well-tolerated treatment for metastatic bone disease. The 50 mg dose is being further evaluated in clinical trials, and this dose was recently approved in the European Union for the prevention of skeletal events in patients with breast cancer and bone metastase

    Superdiffusion in Decoupled Continuous Time Random Walks

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    Continuous time random walk models with decoupled waiting time density are studied. When the spatial one jump probability density belongs to the Levy distribution type and the total time transition is exponential a generalized superdiffusive regime is established. This is verified by showing that the square width of the probability distribution (appropriately defined)grows as t2/γt^{2/\gamma} with 0<γ≤20<\gamma\leq2 when t→∞t\to \infty. An important connection of our results and those of Tsallis' nonextensive statistics is shown. The normalized q-expectation value of x2x^2 calculated with the corresponding probability distribution behaves exactly as t2/γt^{2/\gamma} in the asymptotic limit.Comment: 9 pages (.tex file), 1 Postscript figures, uses revtex.st

    Intravenous ibandronate reduces the incidence of skeletal complications in patients with breast cancer and bone metastases

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    Background: This phase III study compared the efficacy of the new potent bisphosphonate, ibandronate, with placebo as intravenous (i.v.) therapy in metastatic bone disease due to breast cancer. Patients and methods: A total of 466 patients were randomised to receive placebo (n = 158), or 2 mg (n = 154) or 6 mg (n = 154) ibandronate every 3-4 weeks for up to 2 years. The primary efficacy parameter was the number of 12-week periods with new bone complications, expressed as the skeletal morbidity period rate (SMPR). Bone pain, analgesic use and safety were evaluated monthly. Results SMPR was lower in both ibandronate groups compared with the placebo group; the difference was statistically significant for the ibandronate 6 mg group (P = 0.004 versus placebo). Consistent with the SMPR, ibandronate 6 mg significantly reduced the number of new bone events (by 38%) and increased time to first new bone event. Patients on ibandronate 6 mg also experienced decreased bone pain scores and analgesic use. Treatment with ibandronate was well tolerated. Conclusions: These results indicate that 6 mg i.v. ibandronate is effective and safe in the treatment of bone metastases from breast cance

    De novo Renal Transplantation after Kaposi Sarcoma: Favorable Outcome in a Patient Receiving Sirolimus and Mycophenolate-Based Immunosuppression

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    Immunosuppressive treatment increases the risk of infection and malignancy in organ transplant recipients. We report on a 42-year-old male renal transplant recipient who lost his first graft after reduction of immunosuppressive treatment due to Kaposi sarcoma and who successfully underwent a second renal transplant 10 years later. The patient's current treatment consists of low-dose prednisone, and the two antiproliferative immunosuppressants mycophenolate mofetil and rapamycin. 4.5 years after his second transplant, the serum creatinine is 1 mg/dl and the patient has no signs of recurrent disease

    F-18-FDG PET/CT in Infective Endocarditis:Indications and Approaches for Standardization

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    Purpose of Review: Additional imaging modalities, such as FDG-PET/CT, have been included into the workup for patients with suspected infective endocarditis, according to major international guidelines published in 2015. The purpose of this review is to give an overview of FDG-PET/CT indications and standardized approaches in the setting of suspected infective endocarditis. Recent Findings: There are two main indications for performing FDG-PET/CT in patients with suspected infective endocarditis: (i) detecting intracardiac infections and (ii) detection of (clinically silent) disseminated infectious disease. The diagnostic performance of FDG-PET/CT for intracardiac lesions depends on the presence of na

    Dose reduction for CT coronary calcium scoring with a calcium-aware image reconstruction technique: a phantom study

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    Objective: To assess the dose reduction potential of a calcium-aware reconstruction technique, which aims at tube voltage-independent computed tomography (CT) numbers for calcium. Methods and materials: A cardiothoracic phantom, mimicking three different patient sizes, was scanned with two calcium inserts (named D100 and CCI), containing calcifications varying in size and density. Tube voltage was varied both manually (range 70–150 and Sn100 kVp) and automatically. Tube current was automatically adapted to maintain reference image quality defined at 120 kVp. Data was reconstructed with the standard reconstruction technique (kernel Qr36) and the calcium-aware reconstruction technique (kernel Sa36). We assessed the radiation dose reduction potential (volumetric CT dose index values (CTDIvol)), noise (standard deviation (SD)), mean CT number (HU) of each calcification, and Agatston scores for varying kVp. Results were compared with the reference acquired at 120 kVp and reconstructed with Qr36. Results: Automatic selection of the optimal tube voltage resulted in a CTDIvol reduction of 22%, 15%, and 12% compared with the reference for the small, medium, and large phantom, respectively. CT numbers differed up to 64% for the standard reconstruction and 11% for the calcium-aware reconstruction. Similarly, Agatston scores deviated up to 40% and 8% for the standard and calcium-aware reconstruction technique, respectively. Conclusion: CT numbers remained consistent with comparable calcium scores when the calcium-aware image reconstruction technique was applied with varying tube voltage. Less consistency was observed in small calcifications with low density. Automatic reduction of tube voltage resulted in a dose reduction of up to 22%. Key Points: •

    Pretreatment with phenoxybenzamine attenuates the radial artery's vasoconstrictor response to α-adrenergic stimuli

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    AbstractBackgroundAlthough the radial artery bypass conduit has excellent intermediate-term patency, it has a proclivity to vasospasm. We tested the hypothesis that brief pretreatment of a radial artery graft with the irreversible adrenergic antagonist phenoxybenzamine attenuates the vasoconstrictor response to the vasopressors phenylephrine and norepinephrine compared with the currently used papaverine/lidocaine.MethodsSegments of human radial artery grafts were obtained after a 30-minute intraoperative pretreatment with a solution containing 20 mL of heparinized blood, 0.4 mL of papaverine (30 mg/mL), and 1.6 mL of lidocaine (1%). The segments were transported to the laboratory and placed into a bath containing Krebs-Henseleit solution and 10, 100, or 1000 μmol/L phenoxybenzamine or vehicle. The segments were tested in organ chambers for contractile responses to increasing concentrations of phenylephrine and norepinephrine (0.5-15 μmol/L).ResultsContractile responses to 15 μmol/L phenylephrine in control radial artery segments averaged 44.2% ± 9.1% of the maximal contractile response to 30 mmol/L KCl. Papaverine/lidocaine modestly attenuated contraction to 15 μmol/L phenylephrine (32.1% ± 5.9%; P = .22), but 1000 μmol/L phenoxybenzamine completely abolished radial artery contraction (−7.2% ± 4.4%; P < .001). The effect of 10 and 100 μmol/L phenoxybenzamine on attenuating vasocontraction was intermediate between 1000 μmol/L phenoxybenzamine and papaverine/lidocaine. Responses to 15 μmol/L norepinephrine in control radial artery segments averaged 54.7% ± 7.5% of maximal contraction to 30 mmol/L KCl. Papaverine/lidocaine modestly attenuated the contraction response of radial artery segments (35.6% ± 5.1%; P = .04). In contrast, 1000 μmol/L phenoxybenzamine showed the greatest attenuation of norepinephrine-induced contraction (−10.5% ± 2.0%; P < .001).ConclusionsA brief pretreatment of the human radial artery bypass conduit with 1000 μmol/L phenoxybenzamine completely attenuates the vasoconstrictor responses to the widely used vasopressors norepinephrine and phenylephrine. Papaverine/lidocaine alone did not block vasoconstriction to these α-adrenergic agonists
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