796 research outputs found

    Solar activity during Skylab: Its distribution and relation to coronal holes

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    Solar active regions observed during the period of Skylab observations (May 1973-February 1974) were examined for properties that varied systematically with location on the sun, particularly with respect to the location of coronal holes. Approximately 90 percent of the optical and X-ray flare activity occurred in one solar hemisphere (136-315 heliographic degrees longitude). Active regions within 20 heliographic degrees of coronal holes were below average in lifetimes, flare production, and magnetic complexity. Histograms of solar flares as a function of solar longitude were aligned with H alpha synoptic charts on which active region serial numbers and coronal hole boundaries were added

    Decadal-scale thermohaline variability in the Atlantic sector of the Southern Ocean

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    An enhanced Altimetry Gravest Empirical Mode (AGEM), including both adiabatic and diabatic trends, is developed for the Antarctic Circumpolar Current (ACC) south of Africa using updated hydrographic CTD sections, Argo data, and satellite altimetry. This AGEM has improved accuracy compared to traditional climatologies and other proxy methods. The AGEM for the Atlantic Southern Ocean offers an ideal technique to investigate the thermohaline variability over the past two decades in a key region for water mass exchanges and transformation. In order to assess and attribute changes in the hydrography of the region, we separate the changes into adiabatic and diabatic components. Integrated over the upper 2000 dbar of the ACC south of Africa, results show mean adiabatic changes of 0.16 ± 0.11°C decade−1 and 0.006 ± 0.014 decade−1, and diabatic differences of −0.044 ± 0.13°C decade−1 and −0.01 ± 0.017 decade−1 for temperature and salinity, respectively. The trends of the resultant AGEM, that include both adiabatic and diabatic variability (termed AD-AGEM), show a significant increase in the heat content of the upper 2000 dbar of the ACC with a mean warming of 0.12 ± 0.087°C decade−1. This study focuses on the Antarctic Intermediate Water (AAIW) mass where negative diabatic trends dominate positive adiabatic differences in the Subantarctic Zone (SAZ), with results indicating a cooling (−0.17°C decade−1) and freshening (−0.032 decade−1) of AAIW in this area, whereas south of the SAZ positive adiabatic and diabatic trends together create a cumulative warming (0.31°C decade−1) and salinification (0.014 decade−1) of AAIW

    Central Venous Catheter Infection with Brevibacterium sp. in an Immunocompetent Woman: Case Report and Review of the Literature

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    Brevibacterium spp. were considered apathogenic until a few reports of infections in immunocompromised patients were published. Herein, we present a case of a catheter-related septicemia with Brevibacterium casei in an immunocompetent patient receiving continuous iloprost infusion for pulmonary arterial hypertension and review the clinical presentation of this mainly emerging opportunistic pathoge

    Slowly cycling Rho kinase-dependent actomyosin cross-bridge slippage explains intrinsic high compliance of detrusor smooth muscle

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    Biological soft tissues are viscoelastic because they display timeindependent pseudoelasticity and time-dependent viscosity. However, there is evidence that the bladder may also display plasticity, defined as an increase in strain that is unrecoverable unless work is done by the muscle. In the present study, an electronic lever was used to induce controlled changes in stress and strain to determine whether rabbit detrusor smooth muscle (rDSM) is best described as viscoelastic or viscoelastic plastic. Using sequential ramp loading and unloading cycles, stress-strain and stiffness-stress analyses revealed that rDSM displayed reversible viscoelasticity, and that the viscous component was responsible for establishing a high stiffness at low stresses that increased only modestly with increasing stress compared with the large increase produced when the viscosity was absent and only pseudoelasticity governed tissue behavior. The study also revealed that rDSM underwent softening correlating with plastic deformation and creep that was reversed slowly when tissues were incubated in a Ca2+ -containing solution. Together, the data support a model of DSM as a viscoelastic-plastic material, with the plasticity resulting from motor protein activation. This model explains the mechanism of intrinsic bladder compliance as slipping cross bridges, predicts that wall tension is dependent not only on vesicle pressure and radius but also on actomyosin cross-bridge activity, and identifies a novel molecular target for compliance regulation, both physiologically and therapeutically

    The present and future system for measuring the Atlantic meridional overturning circulation and heat transport

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    of the global combined atmosphere-ocean heat flux and so is important for the mean climate of the Atlantic sector of the Northern Hemisphere. This meridional heat flux is accomplished by both the Atlantic Meridional Overturning Circulation (AMOC) and by basin-wide horizontal gyre circulations. In the North Atlantic subtropical latitudes the AMOC dominates the meridional heat flux, while in subpolar latitudes and in the subtropical South Atlantic the gyre circulations are also important. Climate models suggest the AMOC will slow over the coming decades as the earth warms, causing widespread cooling in the Northern hemisphere and additional sea-level rise. Monitoring systems for selected components of the AMOC have been in place in some areas for decades, nevertheless the present observational network provides only a partial view of the AMOC, and does not unambiguously resolve the full variability of the circulation. Additional observations, building on existing measurements, are required to more completely quantify the Atlantic meridional heat transport. A basin-wide monitoring array along 26.5°N has been continuously measuring the strength and vertical structure of the AMOC and meridional heat transport since March 31, 2004. The array has demonstrated its ability to observe the AMOC variability at that latitude and also a variety of surprising variability that will require substantially longer time series to understand fully. Here we propose monitoring the Atlantic meridional heat transport throughout the Atlantic at selected critical latitudes that have already been identified as regions of interest for the study of deep water formation and the strength of the subpolar gyre, transport variability of the Deep Western Boundary Current (DWBC) as well as the upper limb of the AMOC, and inter-ocean and intrabasin exchanges with the ultimate goal of determining regional and global controls for the AMOC in the North and South Atlantic Oceans. These new arrays will continuously measure the full depth, basin-wide or choke-point circulation and heat transport at a number of latitudes, to establish the dynamics and variability at each latitude and then their meridional connectivity. Modeling studies indicate that adaptations of the 26.5°N type of array may provide successful AMOC monitoring at other latitudes. However, further analysis and the development of new technologies will be needed to optimize cost effective systems for providing long term monitoring and data recovery at climate time scales. These arrays will provide benchmark observations of the AMOC that are fundamental for assimilation, initialization, and the verification of coupled hindcast/forecast climate models

    Sensitivity of gyre-scale marine connectivity estimates to fine-scale circulation

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    We investigated the connectivity properties of an idealized western boundary current system separating two ocean gyres, where the flow is characterized by a well-defined mean circulation as well as energetic fine-scale features (i.e., mesoscale and submesoscale currents). We used a time-evolving 3D flow field from a high-resolution (HR-3D) ocean model of this system. In order to evaluate the role of the fine scales in connectivity estimates, we computed Lagrangian trajectories in three different ways: using the HR-3D flow, using the same flow but filtered on a coarse-resolution grid (CR-3D), and using the surface layer flow only (HR-SL). We examined connectivity between the two gyres along the western boundary current and across it by using and comparing different metrics, such as minimum and averaged values of transit time between 16 key sites, arrival depths, and probability density functions of transit times. We find that when the fine-scale flow is resolved, the numerical particles connect pairs of sites faster (between 100 to 300 d) than when it is absent. This is particularly true for sites that are along and near the jets separating the two gyres. Moreover, the connectivity is facilitated when 3D instead of surface currents are resolved. Finally, our results emphasize that ocean connectivity is 3D and not 2D and that assessing connectivity properties using climatologies or low-resolution velocity fields yields strongly biased estimates.</p

    Not all intravenous immunoglobulin preparations are equally well tolerated

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    Intravenous immunoglobulin (IVIG) is used for many indications beyond the original substitution in primary antibody deficiency. Whereas many reports mention adverse reactions, no comparative data exist concerning the incidence of side-effects among the different brands of IVIG. We describe here our experience with the use of different IVIG formulations and their tolerability in a select cohort of 40 patients. The IVIG dose ranged from 0.4 to 3 g/kg/day and was given for 1–2742 days. Fourteen patients (35%) experienced mild to severe adverse reactions during or within 48 h of administration of standard IVIG preparation, which did not recur after switching to an alternative preparation. Adverse reactions included headache, fever, chills, nausea, emesis, hypotension and muscle cramps. One patient experienced a severe adverse reaction; he had a 3-day headache following IVIG infusion. Among the 16 patients who received alternative preparation initially, none experienced adverse reactions. In conclusion, this study shows that IVIG preparations are not all equally well tolerated in patients. The data suggest that, perhaps to a comparable extent to the preparation itself, the infusion rate has a major effect. If a reduction in the infusion rate does not minimize side-effects, one should consider switching the IVIG formulation

    Bosentan therapy for chronic thromboembolic pulmonary hypertension. A national open label study assessing the effect of Bosentan on haemodynamics, exercise capacity, quality of life, safety and tolerability in patients with chronic thromboembolic pulmonary hypertension (BOCTEPH-Study).

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    we performed an open-label national study to evaluate the effects of Bosentan on haemodynamics, exercise capacity, quality of life, safety and tolerability in patients with chronic thromboembolic pulmonary hypertension (CTEPH). fifteen patients with CTEPH not eligible or waiting for surgery were enrolled. The primary endpoint was the change in pulmonary vascular resistance (PVR). Secondary endpoints included quality of life (measured by the Minnesota living with heart failure questionnaire, MLHF), 6 minute walk distance (6MWD), World Health Organization (WHO) functional class, Borg dyspnoea scale, plasma endothelin, serum values of disease severity such as uric acid, N-terminal-pro brain natriuretic peptide (NTproBNP), C-reactive protein measured by a highly sensitive method (CRPs) and other serum and haemodynamic parameters. after six months of treatment with bosentan, the PVR decreased from 852 (319) to 657(249) dyn*s*m-5 (p = 0.02). Quality of life considerably improved from a mean total score of 48(14) to 35(17) (p = 0.003) with improvements in the physical (from 25(5) to 17(7)) and emotional (from 11(6) to 6(5)) subscores (p = 0.005 and 0.011), respectively. The 6MWD improved from 389(78) to 443(79) meters (p = 0.005). 4 patients (27%) improved and 11 patients (73%) maintained their WHO class with no deterioration during the six months of bosentan treatment (p = 0.02). Uric acid serum levels declined from 525(145) to 453(151) micromol/l (p = 0.006), NTproBNP and CRPs declined insignificantly. Endothelin serum levels increased from 4.3(1.5) to 5.9(2.2) pg/ml (p = 0.025). Patients tolerated the treatment well, and there were no severe adverse events or deaths. this open-label study suggests a beneficial effect of bosentan therapy not only on pulmonary haemodynamics, but also on quality of life and exercise capacity for patients with severe CTEPH
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