On the Behavior of F2 and its Logarithmic Slopes

It is shown that the CKMT model for the nucleon structure function F2, taken as the initial condition for the NLO evolution equations in perturbative QCD, provides a good description of the HERA data when presented in the form of the logarithmic slopes of F2 vs x and Q2 (Caldwell-plot), in the whole available kinematic ranges. Also the results obtained for the behavior of the gluon component of a nucleon are presented.Comment: 16 pages, 10 figure

Hard Diffraction at HERA and the Gluonic Content of the Pomeron

We show that the previously introduced CKMT model, based on conventional Regge theory, gives a good description of the HERA data on the structure function F_2^D for large rapidity gap (diffractive) events. These data allow, not only to determine the valence and sea quark content of the Pomeron, but also, through their Q^2 dependence, give information on its gluonic content. Using DGLAP evolution, we find that the gluon distribution in the Pomeron is very hard and the gluons carry more momentum than the quarks. This indicates that the Pomeron, unlike ordinary hadrons, is a mostly gluonic object. With our definition of the Pomeron flux factor the total momentum carried by quarks and gluons turns out to be 0.3-0.4 - strongly violating the momentum sum rule.Comment: C-Shell archive of a PostScript file containing a 20 page paper with text and 12 figures in i

Structure Functions of Nuclei at Small x and Diffraction at HERA

Gribov theory is applied to investigate the shadowing effects in the structure functions of nuclei. In this approach these effects are related to the process of diffractive dissociation of a virtual photon. A model for this diffractive process, which describes well the HERA data, is used to calculate the shadowing in nuclear structure functions. A reasonable description of the x, Q^2 and A-dependence of nuclear shadowing is achieved.Comment: TeX, 10 pages, 7 figures in 6 ps-file

Spectroscopic time-series analysis of R Canis Majoris

R Canis Majoris is the prototype of a small group of Algol-type stars showing short orbital periods and low mass ratios. A previous detection of short-term oscillations in its light curve has not yet been confirmed. We investigate a new time series of high-resolution spectra with the aim to derive improved stellar and system parameters, to search for the possible impact of a third component in the observed spectra, to look for indications of activity in the Algol system, and to search for short-term variations in radial velocities. We disentangled the composite spectra into the spectra of the binary components. Then we analysed the resulting high signal-to-noise spectra of both stars. Using a newly developed program code based on an improved method of least-squares deconvolution, we were able to determine the radial velocities of both components also during primary eclipse. This allowed us to develop a better model of the system including the Rossiter-McLaughlin effect and to derive improved orbital parameters. Combining the results with those from spectrum analysis, we obtain accurate stellar and system parameters. We further deduce at least one oscillation frequency of 21.38 c/d. It could be detected during primary eclipses only and confirms a previous photometric finding. Results point to an amplitude amplification of non-radial pulsation modes due to the eclipse mapping effect. The presence of a He\,I line in the spectra indicates mass transfer in the R CMa system. Calculations of its Roche geometry give evidence that the cool secondary component may fill its Roche lobe. No evidence of a third body in the system could be found in the observed spectra.Comment: 12 pages, 14 figures, 5 table

The management of acute venous thromboembolism in clinical practice. Results from the European PREFER in VTE Registry

Venous thromboembolism (VTE) is a significant cause of morbidity and mortality in Europe. Data from real-world registries are necessary, as clinical trials do not represent the full spectrum of VTE patients seen in clinical practice. We aimed to document the epidemiology, management and outcomes of VTE using data from a large, observational database. PREFER in VTE was an international, non-interventional disease registry conducted between January 2013 and July 2015 in primary and secondary care across seven European countries. Consecutive patients with acute VTE were documented and followed up over 12 months. PREFER in VTE included 3,455 patients with a mean age of 60.8 ± 17.0 years. Overall, 53.0 % were male. The majority of patients were assessed in the hospital setting as inpatients or outpatients (78.5 %). The diagnosis was deep-vein thrombosis (DVT) in 59.5 % and pulmonary embolism (PE) in 40.5 %. The most common comorbidities were the various types of cardiovascular disease (excluding hypertension; 45.5 %), hypertension (42.3 %) and dyslipidaemia (21.1 %). Following the index VTE, a large proportion of patients received initial therapy with heparin (73.2 %), almost half received a vitamin K antagonist (48.7 %) and nearly a quarter received a DOAC (24.5 %). Almost a quarter of all presentations were for recurrent VTE, with >80 % of previous episodes having occurred more than 12 months prior to baseline. In conclusion, PREFER in VTE has provided contemporary insights into VTE patients and their real-world management, including their baseline characteristics, risk factors, disease history, symptoms and signs, initial therapy and outcomes

Persistence of strong silica-enriched domains in the Earth's lower mantle

The composition of the lower mantle—comprising 56% of Earth’s volume—remains poorly constrained. Among the major elements, Mg/Si ratios ranging from ∼0.9–1.1, such as in rocky Solar-System building blocks (or chondrites), to ∼1.2–1.3, such as in upper-mantle rocks (or pyrolite), have been proposed. Geophysical evidence for subducted lithosphere deep in the mantle has been interpreted in terms of efficient mixing, and thus homogenous Mg/Si across most of the mantle. However, previous models did not consider the effects of variable Mg/Si on the viscosity and mixing efficiency of lower-mantle rocks. Here, we use geodynamic models to show that large-scale heterogeneity associated with a 20-fold change in viscosity, such as due to the dominance of intrinsically strong (Mg, Fe)SiO3–bridgmanite in low-Mg/Si domains, is sufficient to prevent efficient mantle mixing, even on large scales. Models predict that intrinsically strong domains stabilize mantle convection patterns, and coherently persist at depths of about 1,000–2,200 km up to the present-day, separated by relatively narrow up-/downwelling conduits of pyrolitic material. The stable manifestation of such bridgmanite-enriched ancient mantle structures (BEAMS) may reconcile the geographical fixity of deep-rooted mantle upwelling centres, and geophysical changes in seismic-tomography patterns, radial viscosity, rising plumes and sinking slabs near 1,000 km depth. Moreover, these ancient structures may provide a reservoir to host primordial geochemical signatures

Ost-Europa,Bl. 2 : Nordost-Russland /von A. Petermann

1 Mapa. Dins de: Stieler's Hand-Atlas, nº 51. - Abans registre duplicat (RM 4430)1:3 700 00039 x 46 c