1,489 research outputs found

    Organic Carbon Burial following the Middle Eocene Climatic Optimum (MECO) in the central - western Tethys

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    We present trace metal geochemistry and stable isotope records for the middle Eocene Alano di Piave section, NE Italy, deposited during magnetochron C18n in the marginal Tethys Ocean. We identify a \sim 500 kyr long carbon isotope perturbation event we infer to be the middle Eocene Climatic Optimum (MECO) confirming the northern hemisphere expression and global occurrence of MECO. Interpreted peak climatic conditions are followed by the rapid deposition of two organic rich intervals (\le3\% TOC) and contemporaneous positive δ13\delta^{13}C excursions. These two intervals are associated with increases in the concentration of sulphur and redox-sensitive trace metals, and low concentrations of Mn, as well as coupled with the occurrence of pyrite. Together these changes imply low, possibly dysoxic, bottom water O2_{2} conditions promoting increased organic carbon burial. We hypothesize that this rapid burial of organic carbon lowered global {\it p}CO2_{2} following the peak warming and returned the climate system to the general Eocene cooling trend

    Can be gravitational waves markers for an extra-dimension?

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    The main issue of the present letter is to fix specific features (which turn out being independent of extradimension size) of gravitational waves generated before a dimensional compactification process. Valuable is the possibility to detect our prediction from gravitational wave experiment without high energy laboratory investigation. In particular we show how gravitational waves can bring information on the number of Universe dimensions. Within the framework of Kaluza-Klein hypotheses, a different morphology arises between waves generated before than the compactification process settled down and ordinary 4-dimensional waves. In the former case the scalar and tensor degrees of freedom can not be resolved. As a consequence if were detected gravitational waves having the feature here predicted (anomalous polarization amplitudes), then they would be reliable markers for the existence of an extra dimension.Comment: 5 pages, two figure, to appear on Int. Journ. Mod. Phys.

    Indexed left atrial volume, C-reactive protein and erythrocyte sedimentation rate as predictors of recurrence of non-valvular atrial fibrillation after successful cardioversion

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    Indexed left atrial volume, C-reactive protein and erythrocyte sedimentation rate as predictors of recurrence of non-valvular atrial fibrillation after successful cardioversio

    Indexed left atrial volume is superior to left atrial diameter in predicting nonvalvular atrial fibrillation recurrence after successful cardioversion: a prospective study.

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    BACKGROUND: Although indexed left atrial volume (iLAV) is the most accurate measure of left atrial size, it has not been evaluated prospectively as predictor of recurrence of atrial fibrillation (AFib) after successful cardioversion (CV). METHODS: We prospectively selected 76 patients (mean age 66.1 ± 13.6 years, 65.8% men) with AFib who underwent successful CV. Baseline clinical and echocardiographic characteristics were obtained before CV. LAV was measured using Simpson's method and indexed to body surface area. All patients were scheduled for follow-up visit at 1, 6, 12 months, and then annually. A 24-hour Holter ECG was performed within 6 months and each time the patients reported symptoms suggestive of arrhythmia. RESULTS: The 52 patients (68.4%) with AFib recurrence had larger iLAV (35.5 ± 8.9 mL/m(2) vs 27.0 ± 6.7 mL/m(2) , P < 0.001). Anteroposterior LA diameter was not associated with AFib relapse (OR 1.08, 95% CI: 0.96-1.21, P = 0.09). Each unit increase in iLAV was associated with a 1.15-fold increased risk of recurrence (OR 1.15, 95% CI: 1.06-1.25, P < 0.001). In a multivariable model, iLAV remained the only independent predictor of relapse (adjusted OR 1.14, 95% CI: 1.02-1.28, P = 0.02). The area under ROC curves, generated to compare LA diameter, and iLAV as predictors of AFib recurrence were 0.56 (SE 0.07) versus 0.78 (SE 0.05), respectively (P = 0.003). CONCLUSION: This is the first prospective study to show that larger iLAV, as a more accurate measure of LA remodeling than anteroposterior diameter, is strongly and independently associated with a higher risk of AFib recurrence after CV

    Efficacy of pulsatile flow perfusion in adult cardiac surgery: Hemodynamic energy and vascular reactivity

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    Background: The role of pulsatile (PP) versus non-pulsatile (NP) flow during a cardiopulmonary bypass (CPB) is still debated. This study’s aim was to analyze hemodynamic effects, endothelial reactivity and erythrocytes response during a CPB with PP or NP. Methods: Fifty-two patients undergoing an aortic valve replacement were prospectively randomized for surgery with either PP or NP flow. Pulsatility was evaluated in terms of energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE). Systemic (SVRi) and pulmonary (PVRi) vascular resistances, endothelial markers levels and erythrocyte nitric-oxide synthase (eNOS) activity were collected at different perioperative time-points. Results: In the PP group, the resultant EEP was 7.3% higher than the mean arterial pressure (MAP), which corresponded to 5150 ± 2291 ergs/cm3 of SHE. In the NP group, the EEP and MAP were equal; no SHE was produced. The PP group showed lower SVRi during clamp-time (p = 0.06) and lower PVRi after protamine administration and during first postoperative hours (p = 0.02). Lower SVRi required a higher dosage of norepinephrine in the PP group (p = 0.02). Erythrocyte eNOS activity results were higher in the PP patients (p = 0.04). Renal function was better preserved in the PP group (p = 0.001), whereas other perioperative variables were comparable between the groups. Conclusions: A PP flow during a CPB results in significantly lower SVRi, PVRi and increased eNOS production. The clinical impact of increased perioperative vasopressor requirements in the PP group deserves further evaluation

    On Symmetries of Extremal Black Holes with One and Two Centers

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    After a brief introduction to the Attractor Mechanism, we review the appearance of groups of type E7 as generalized electric-magnetic duality symmetries in locally supersymmetric theories of gravity, with particular emphasis on the symplectic structure of fluxes in the background of extremal black hole solutions, with one or two centers. In the latter case, the role of an "horizontal" symmetry SL(2,R) is elucidated by presenting a set of two-centered relations governing the structure of two-centered invariant polynomials.Comment: 1+13 pages, 2 Tables. Based on Lectures given by SF and AM at the School "Black Objects in Supergravity" (BOSS 2011), INFN - LNF, Rome, Italy, May 9-13 201

    Posterior reconstruction during robotic-assisted radical cystectomy with intracorporeal orthotopic ileal neobladder: description and outcomes of a simple step

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    A posterior reconstruction (PR) might improve the fluidity and delicacy of the maneuvers related to the neovesico-urethral anastomosis during robotic-assisted radical cystectomy (RARC). Our objective is to describe in detail the surgical steps of PR and to assess its feasibility and functional outcomes. The data regarding patients undergoing a totally intracorporeal RARC with neobladder and PR for high-grade and/or muscle-invasive urothelial cancer of the bladder at Karolinska University Hospital between October 2015 and November 2016 by a single surgeon (PW) were reviewed. Prior to the anastomosis, a modified posterior Rocco’s repair involving the Denonvillier’s fascia, the rhabdosphincter, and the posterior side of the ileal neobladder neck was performed. The steps are shown in a video at https://doi.org/10.1089/vid.2019.0029. The primary outcome was urinary continence; the secondary outcomes were urinary leakage, intermittent catheterization, and complications related to the reconstructive steps. Eleven male patients with a median age and BMI of 67&nbsp;years and 24, respectively, underwent RARC with PR associated to the neovesico-urethral anastomosis. Overall and posterior reconstruction time were 300′ (195–320) and 6′ (4–7), respectively. The daytime and nighttime continence rates were 100% and 44% at 12&nbsp;months, respectively; the median pad weight was 3.5&nbsp;g and 108&nbsp;g at daytime and nighttime, respectively. One urinary leakage from the urethrovesical anastomosis was treated conservatively. Two patients perform intermittent catheterization. The posterior reconstruction during RARC is safe and feasible, providing good continence rates. It supported a careful suturing of the anastomosis as well as an uncomplicated catheter placement

    Energy efficiency and preservation of 20th century architecture

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    This paper follows the discussion on the energy efficiency of heritage buildings by dealing with the task of preserving 20th century buildings and making them more sustainable. It is confirmed that a thorough analysis of each case is needed, since the cultural value of modern heritage risks being overwhelmed by the effort to improve its energy efficiency. The Urbino University Colleges are a masterpiece of the 20th century. They were designed by architect Giancarlo de Carlo, built between 1962 and 1983 and still host 1000 students. A conservation plan was outlined in 2016 with the aim of developing the long-term and sustainable preservation of such a huge complex. A specific goal in terms of sustainability was lowering the heating costs to save funds for conservation activities. The efforts were thus to balance building conservation, energy efficiency and users’ comfort. A thermal analysis, an energy retrofit design, a test on a pilot site, a comparison between before and after, are the tools that have been used to achieve this objective. Results provide some operational indications to merge conservation and sustainability in a 20th century heritage building

    Ion diffusion modelling of Fricke-agarose dosemeter gels

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    In Fricke-agarose gels, an accurate determination of the spatial dose distribution is hindered by the diffusion of ferric ions. In this work, a model was developed to describe the diffusion process within gel samples of finite length and, thus, permit the reconstruction of the initial spatial distribution of the ferric ions. The temporal evolution of the ion concentration as a function of the initial concentration is derived by solving Fick's second law of diffusion in two dimensions with boundary reflections. The model was applied to magnetic resonance imaging data acquired at high spatial resolution (0.3 mm) and was found to describe accurately the observed diffusion effect
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