81 research outputs found

    Origin of Nepheline-normative High-K Ankaramites and the Evolution of Eastern Srednogorie Arc in SE Europe

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    Eastern Srednogorie is part of the Apuseni-Banat-Timok-Srednogorie magmatic belt in SE Europe, the main arc related to the Late Cretaceous subduction and closure of the Tethys Ocean between Africa and Europe. Extrusive and shallow intrusive magmatism in the Eastern Srednogorie is abundant and extremely diverse in composition, covering a wide range from ultramafic volcanic rocks to granites; this provides a unique opportunity to study processes of primitive melt formation and magma evolution in an arc environment. In contrast to other parts of the belt, relatively mafic lavas predominate here. Three magmatic regions are distinguished within Eastern Srednogorie from south to north: Strandzha, Yambol-Burgas and East Balkan. Systematic differences exist between these regions, notably the increased alkalinity of samples from the Yambol-Burgas region in the central part. All rocks display a clear subduction-like signature in their trace-element patterns, particularly the enrichment in large ion lithophile elements and light rare earth elements relative to high field strength elements. A distinct primitive nepheline-normative ankaramite magma type is recognized among the mafic volcanic rocks from the Yambol-Burgas region and melt inclusions entrapped in olivine and clinopyroxene from a cumulitic rock. Lower crustal clinopyroxene and amphibole cumulates carried to the surface as xenoliths in a mafic dike represent a possible source for the ankaramite. Modeling of the melting process suggests that low degrees of batch melting of a clinopyroxene-rich, amphibole-bearing source similar to the cumulate xenoliths at 1 GPa, temperatures of 1240-1300°C, oxidized conditions and a water content of 0·2 wt % reproduce accurately most of the observed major- and trace-element characteristics of the studied ankaramites. The elevated Rb, K2O, Th, Ba content and higher Pb isotope ratios of the predicted liquids compared with the ankaramites are explained by mixing of the ankaramite magma with lherzolite partial melts derived from the subduction-modified mantle wedge. Underplating of such mantle-derived magmas at the crust-mantle boundary in an extensional environment as a response to slab roll-back provides also the necessary heat to melt lower crustal cumulates. Fractional crystallization of mainly clinopyroxene plus olivine and Fe-Ti oxides in a deep (equivalent to 8 kbar pressure) magma chamber produced most of the observed range of shoshonitic basalts and basaltic andesites in Eastern Srednogorie. The more evolved intermediate varieties were probably formed by mixing and crystallization at lower temperatures in lower pressure magma chambers. Whole-rock Sr and Pb isotope compositions indicate variable degrees of admixing of basement rocks to generate the intermediate to acid Late Cretaceous magmas, but assimilation was minimal for magmas with less than 53 wt % SiO2. The proposed model for the evolution of the magmatism in Eastern Srednogorie involves initial formation of the calc-alkaline and high-K arc magmatism in the Strandzha and East Balkan regions, followed by roll-back induced intra-arc rifting and the formation of high-K, shoshonitic and ultra-high-K magmatism, including primitive ankaramites in the Yambol-Burgas regio

    Rhodiola rosea L.:from golden root to green cell factories

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    Baseline characteristics of patients in the reduction of events with darbepoetin alfa in heart failure trial (RED-HF)

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    <p>Aims: This report describes the baseline characteristics of patients in the Reduction of Events with Darbepoetin alfa in Heart Failure trial (RED-HF) which is testing the hypothesis that anaemia correction with darbepoetin alfa will reduce the composite endpoint of death from any cause or hospital admission for worsening heart failure, and improve other outcomes.</p> <p>Methods and results: Key demographic, clinical, and laboratory findings, along with baseline treatment, are reported and compared with those of patients in other recent clinical trials in heart failure. Compared with other recent trials, RED-HF enrolled more elderly [mean age 70 (SD 11.4) years], female (41%), and black (9%) patients. RED-HF patients more often had diabetes (46%) and renal impairment (72% had an estimated glomerular filtration rate <60 mL/min/1.73 m2). Patients in RED-HF had heart failure of longer duration [5.3 (5.4) years], worse NYHA class (35% II, 63% III, and 2% IV), and more signs of congestion. Mean EF was 30% (6.8%). RED-HF patients were well treated at randomization, and pharmacological therapy at baseline was broadly similar to that of other recent trials, taking account of study-specific inclusion/exclusion criteria. Median (interquartile range) haemoglobin at baseline was 112 (106–117) g/L.</p> <p>Conclusion: The anaemic patients enrolled in RED-HF were older, moderately to markedly symptomatic, and had extensive co-morbidity.</p&gt

    Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF

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    M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe

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    High-resolution spectroscopic observations around the Hα line of FK Co

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    The data augmentation (DA) algorithm is a widely used Markov chain Monte Carlo (MCMC) algorithm that is based on a Markov transition density of the form p(x|x ′ ) = � Y f X|Y (x|y)f Y |X(y|x ′ ) dy, where f X|Y and f Y |X are conditional densities. The PX-DA and marginal augmentation algorithms (Liu and Wu, 1999; Meng and van Dyk, 1999) are alternatives to DA that often converge much faster and are only slightly more computationally demanding. The transition densities of these alternative algorithms can be written in the form pR(x|x ′ ) = � � Y Y f X|Y (x|y ′)R(y, dy ′)f Y |X(y|x ′ ) dy, where R is a Markov transition function on Y. We prove that when R satisfies certain conditions, the MCMC algorithm driven by pR is at least as good as that driven by p in terms of performance in the central limit theorem and in the operator norm sense. These results are brought to bear on a theoretical comparison of the DA, PX-DA and marginal augmentation algorithms. Our focus is on situations where the group structure exploited by Liu and Wu (1999) is available. We show that the PX-DA algorithm based on Haar measure is at least as good as any PX-DA algorithm constructed using a proper prior on the group
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