1,463 research outputs found
Pharmacological basis and clinical evidence of dabigatran therapy
Dabigatran is an emerging oral anticoagulant which is a direct inhibitor of thrombin activity. It has been approved in the European Union and the United States of America for the prevention of thrombosis after major orthopedic surgery. It has also been approved by the American Food and Drug Administration and the European Medicines Agency for the prevention of stroke in chronic atrial fibrillation. Dabigatran provides a stable anticoagulation effect without any need to perform periodical laboratory controls. Of note, there is a growing amount of clinical evidence which shows its safety and efficacy. For these reasons, dabigatran may suppose a revolution in oral anticoagulation. However, two important limitations remain. First, it is contraindicated in patients with end-stage renal disease. Second, there is no evidence of the prevention of thrombosis in mechanical heart valves
Error estimates for the discretization of the velocity tracking problem
In this paper we are continuing our work (Casas and Chrysafinos, SIAM J Numer Anal 50(5):2281–2306, 2012), concerning a priori error estimates for the velocity tracking of two-dimensional evolutionary Navier–Stokes flows. The controls are of distributed type, and subject to point-wise control constraints. The discretization scheme of the state and adjoint equations is based on a discontinuous time-stepping scheme (in time) combined with conforming finite elements (in space) for the velocity and pressure. Provided that the time and space discretization parameters, t and h respectively, satisfy t = Ch2, error estimates of order O(h2) and O(h 3/2 – 2/p ) with p > 3 depending on the regularity of the target and the initial velocity, are proved for the difference between the locally optimal controls and their discrete approximations, when the controls are discretized by the variational discretization approach and by using piecewise-linear functions in space respectively. Both results are based on new duality arguments for the evolutionary Navier–Stokes equations
Depressive symptoms and mortality-findings from Helsinki birth cohort study
Background: Individuals with depression and depressive symptoms have a higher mortality rate than non-depressed individuals. The increased comorbidity and mortality associated with depression has remained largely unexplained. The underlying pathophysiological differences between depressive subtypes, melancholic and non-melancholic, may provide some explanation to this phenomenon.Methods: One thousand nine hundred and ninety five participants (mean age 61 years) from the Helsinki Birth Cohort Study were recruited for this prospective study and followed up for a mean of 14.1 years. Information regarding medical history, lifestyle, and biochemical parameters were obtained. Depressive symptoms were assessed using the Beck Depression Inventory. Standardized mortality ratios were calculated.Results: Participants were followed up for a total of 28,044 person-years. The melancholic depressive group had an increased adjusted risk of mortality [HR 1.49 (95% CI: 1.02-2.20)] when compared to the non-depressive group. Comparing mortality to the whole population of Finland using standardized mortality ratios (SMR) both the non-melancholic [1.11 (95% CI: 0.85-1.44)] and melancholic depressive [1.26 (95% CI: 0.87-1.81)] groups had higher mortality than the non-depressive group [0.82 (95% CI: 0.73-0.93)].Conclusions: Melancholic depressive symptoms are most strongly related to a higher mortality risk.</p
Magnetism in AV3Sb5 (Cs, Rb, K): Origin and Consequences for the Strongly Correlated Phases
The V-based kagome systems AV3Sb5 (A = Cs, Rb and K) are unique by virtue of
the intricate interplay of non-trivial electronic structure, topology and
intriguing fermiology, rendering them to be a playground of many mutually
dependent exotic phases like charge-order and superconductivity. Despite
numerous recent studies, the interconnection of magnetism and other complex
collective phenomena in these systems has yet not arrived at any conclusion.
Using first-principles tools, we demonstrate that their electronic structures,
complex fermiologies and phonon dispersions are strongly influenced by the
interplay of dynamic electron correlations, non-trivial spin-polarization and
spin-orbit coupling. An investigation of the first-principles-derived
inter-site magnetic exchanges with the complementary analysis of q-dependence
of the electronic response functions and the electron-phonon coupling indicate
that the system conforms as a frustrated spin-cluster, where the occurrence of
the charge-order phase is intimately related to the mechanism of
electron-phonon coupling, rather than the Fermi-surface nesting.Comment: Accepted in Physical Review Letter
Magnetism in AV3Sb5 (A = Cs, Rb, K): Complex Landscape of the Dynamical Magnetic Textures
We have investigated the dynamical magnetic properties of the V-based kagome
stibnite compounds by combining the ab-initio calculated magnetic parameters of
a spin Hamiltonian like inter-site exchange parameters, magnetocrystalline
anisotropy and site projected magnetic moments, with full-fledged simulations
of atomistic spin-dynamics. Our calculations reveal that in addition to a
ferromagnetic order along the [001] direction, the system hosts a complex
landscape of magnetic configurations comprised of commensurate and
incommensurate spin-spirals along the [010] direction. The presence of such
chiral magnetic textures may be the key to solve the mystery about the origin
of the experimentally observed inherent breaking of the C6 rotational symmetry-
and the time-reversal symmetry.Comment: Accepted In Physical Review
Pyrolysis-catalytic dry (CO2) reforming of waste plastics for syngas production: Influence of process parameters
Catalytic dry (CO2) reforming of waste plastics was carried out in a two stage, pyrolysis-catalytic reforming fixed bed reactor to optimise the production of syngas (H2 + CO). The effects of changing the process parameters of, catalyst preparation conditions, catalyst temperature, CO2 input rate and catalyst:plastic ratio were investigated. The plastics used was a mixture of plastics simulating that found in municipal solid waste and the catalyst used was Ni-Co-Al2O3. The results showed that changing each of the process conditions investigated, all significantly influenced syngas production. An increase of 17% of syngas production was achieved from the experiment with the catalyst prepared by rising-pH technique compared to preparation via the impregnation method. The optimum syngas production of 148.6 mmolsyngas g−1swp was attained at the catalytic dry reforming temperature of 800 °C and catalyst:plastic ratio of 0.5. The increase of CO2 input rate promoted a higher yield of syngas
Calcium:Magnesium Ratio in Local Groundwater and Incidence of Acute Myocardial Infarction among Males in Rural Finland
Several epidemiologic studies have shown an association between calcium and magnesium and coronary heart disease mortality and morbidity. In this small-area study, we examined the relationship between acute myocardial infarction (AMI) risk and content of Ca, Mg, and chromium in local groundwater in Finnish rural areas using Bayesian modeling and geospatial data aggregated into 10 km × 10 km grid cells. Data on 14,495 men 35–74 years of age with their first AMI in the years 1983, 1988, or 1993 were pooled. Geochemical data consisted of 4,300 measurements of each element in local groundwater. The median concentrations of Mg, Ca, and Cr and the Ca:Mg ratio in well water were 2.61 mg/L, 12.23 mg/L, 0.27 μg/L, and 5.39, respectively. Each 1 mg/L increment in Mg level decreased the AMI risk by 4.9%, whereas a one unit increment in the Ca:Mg ratio increased the risk by 3.1%. Ca and Cr did not show any statistically significant effect on the incidence and spatial variation of AMI. Results of this study with specific Bayesian statistical analysis support earlier findings of a protective role of Mg and low Ca:Mg ratio against coronary heart disease but do not support the earlier hypothesis of a protective role of Ca
Eight common genetic variants associated with serum dheas levels suggest a key role in ageing mechanisms
Dehydroepiandrosterone sulphate (DHEAS) is the most abundant circulating steroid secreted by adrenal glands-yet its function is unknown. Its serum concentration declines significantly with increasing age, which has led to speculation that a relative DHEAS deficiency may contribute to the development of common age-related diseases or diminished longevity. We conducted a meta-analysis of genome-wide association data with 14,846 individuals and identified eight independent common SNPs associated with serum DHEAS concentrations. Genes at or near the identified loci include ZKSCAN5 (rs11761528; p = 3.15×10-36), SULT2A1 (rs2637125; p = 2.61×10-19), ARPC1A (rs740160; p = 1.56×10-16), TRIM4 (rs17277546; p = 4.50×10-11), BMF (rs7181230; p = 5.44×10-11), HHEX (rs2497306; p = 4.64×10-9), BCL2L11 (rs6738028; p = 1.72×10-8), and CYP2C9 (rs2185570; p = 2.29×10-8). These genes are associated with type 2 diabetes, lymphoma, actin filament assembly, drug and xenobiotic metabolism, and zinc finger proteins. Several SNPs were associated with changes in gene expression levels, and the related genes are connected to biological pathways linking DHEAS with ageing. This study provides much needed insight into the function of DHEAS
- …