252 research outputs found
Kathetergestützte Aortenklappenimplantation: Was müssen Anästhesisten wissen?
Zusammenfassung: Der chirurgische Aortenklappenersatz gilt als Goldstandard in der Therapie der hochgradigen Aortenklappenstenose. Die veränderte Demografie konfrontiert die behandelnden medizinischen Fachdisziplinen jedoch mit einem zunehmend höheren Risikoprofil der Patienten; dies machte die Entwicklung neuer weniger invasiver Behandlungsalternativen in der operativen Therapie der Aortenklappenstenose erforderlich. Dieser Entwicklungsprozess führte über die Minithorakotomie hin zur kathetergestützten Aortenklappenimplantation ("transcatheter aortic valve implantation", TAVI). Die TAVI ist ein neues therapeutisches Verfahren zur Behandlung von Patienten mit hochgradiger Aortenklappenstenose und hohem perioperativen Morbiditäts- sowie Mortalitätsrisiko für einen konventionellen Aortenklappenersatz. Da die TAVI am schlagenden Herzen ohne Sternotomie und Herz-Lungen-Maschine durchgeführt werden kann, eignet sich dieses Verfahren insbesondere für den älteren, multimorbiden und/oder kardial voroperierten Patienten. Die ersten Ergebnisse großer prospektiver Multizenterstudien unterstreichen den Stellenwert der TAVI in der modernen Behandlung von Hochrisikopatienten mit symptomatischer Aortenklappenstenose. Die TAVI erfordert vom Anästhesisten neben dem Verständnis des chirurgischen Ablaufs die genaue Kenntnis des perioperativen anästhesiologischen Managements und der möglichen Komplikationen des Verfahren
Modeling the Void H I Column Density Spectrum
The equivalent width distribution function (EWDF) of \hone absorbers specific
to the void environment has been recently derived (Manning 2002), revealing a
large line density of clouds (dN/dz ~500 per unit z for Log (N_HI)> 12.4). I
show that the void absorbers cannot be diffuse (or so-called filamentary)
clouds, expanding with the Hubble flow, as suggested by N-body/hydro
simulations. Absorbers are here modeled as the baryonic remnants of
sub-galactic perturbations that have expanded away from their dark halos in
response to reionization at z ~ 6.5. A 1-D Lagrangian hydro/gravity code is
used to follow the dynamic evolution and ionization structure of the baryonic
clouds for a range of halo circular velocities. The simulation products at z=0
can be combined according to various models of the halo velocity distribution
function to form a column density spectrum that can be compared with the
observed. I find that such clouds may explain the observed EWDF if the halo
velocity distribution function is as steep as that advanced by Klypin (1999),
and the halo mass distribution is closer to isothermal than to NFW.Comment: 21 pages, 15 figures. Paper in press; ApJ 591, n
The Relationship Between Galaxies and Low Redshift Weak Lyman alpha Absorbers in the Directions of H1821+643 and PG1116+215
To study the nature of low z Lya absorbers in the spectra of QSOs, we have
obtained high signal-to-noise UV spectra of H 1821+643 (z = 0.297) and PG
1116+215 (z = 0.177) with the GHRS on the HST. The spectra have minimum S/N of
70-100 and 3 sigma limiting equivalent widths of 50-75 mA. We detect 26 Lya
lines with Wr > 50 mA toward H1821+643 and 13 toward PG1116+215, which implies
a density of 102+/-16 lines per unit redshift. The two-point correlation
function shows marginal evidence of clustering on ~500 km/s scales, but only if
the weakest lines are excluded. We have also used the WIYN Observatory to
measure galaxy redshifts in the ~1 degree fields centered on each QSO. We find
17 galaxy-absorber pairs within projected distances of 1 Mpc with velocity
separations of 350 km/s or less. Monte Carlo simulations show that if the Lya
lines are randomly distributed, the probability of observing this many close
pairs is 3.6e-5. We find that all galaxies with projected distances of 600 kpc
or less have associated Lya absorbers within 1000 km/s, and the majority of
these galaxies have absorbers within 350 km/s. We also find that the Lya
equivalent width is anticorrelated with the projected distance of the nearest
galaxy out to at least 600 kpc, but this should be interpreted cautiously
because there are potential selection biases. Statistical tests using the
entire sample also indicate that the absorbers are not randomly distributed. We
discuss the nature of the Lya absorbers in light of the new data.Comment: Accepted for publication in ApJ. 17 pages plus 11 tables and 17
figure
Updated Big Bang Nucleosynthesis confronted to WMAP observations and to the Abundance of Light Elements
We improve Standard Big Bang Nucleosynthesis (SBBN) calculations taking into
account new nuclear physics analyses (Descouvemont et al. 2003). Using a
Monte-Carlo technique, we calculate the abundances of light nuclei versus the
baryon to photon ratio.The results concerning omegab are compared to relevant
astrophysical and cosmological observations. Consistency between WMAP, SBBN
results and D/H data strengthens the deduced baryon density and has interesting
consequences on cosmic chemical evolution. A significant discrepancy between
the calculated Li-7 deduced from WMAP and the Spite plateau is clearly
revealed. To explain this discrepancy three possibilities are invoked :
uncertainties on the Li abundance, surface alteration of Li in the course of
stellar evolution or poor knowledge of the reaction rates related to Be-7
destruction. In particular, the possible role of the up to now neglected
Be-7(d,p)2He-4 and Be-7(d,alpha)Li5 reactions is considered. The impressive
advances in CMB observations provide a strong motivation for more efforts in
experimental nuclear physics and high quality spectroscopy to keep BBN in pace.Comment: accepted in ApJ, 22 pages, 5 figure
Cognitive conflicts in major depression : Between desired change and personal coherence
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposesThe notion of intrapsychic conflict has been present in psychopathology for more than a century within different theoretical orientations. However, internal conflicts have not received enough empirical attention, nor has their importance in depression been fully elaborated. This study is based on the notion of cognitive conflict, understood as implicative dilemma (ID), and on a new way of identifying these conflicts by means of the Repertory Grid Technique. Our aim was to explore the relevance of cognitive conflicts among depressive patientsPeer reviewedFinal Published versio
With a little help from my goals : integrating intergoal facilitation with the theory of planned behaviour to predict physical activity
Reproduced with permission from British Journal of Health Psychology © The British Psychological Society 2010.Peer reviewedPostprin
On the Possible Sources of D/H Dispersion at High Redshift
Recent observations suggest the existence of a white dwarf population in the
Galactic halo, while others suggest that deuterium has been astrated in systems
at high redshift and low metallicity. We propose that these observations could
be signatures of an early population of intermediate-mass stars. Such a
population requires a Population III initial mass function different from that
of the solar neighborhood, as perhaps also suggested by the observed cosmic
infrared background. Also, to avoid overproduction of C and N, it is required
that the Z=0 yields of these stars have low ( solar) abundances
as suggested by some recent calculations. Under these assumptions, we present a
model which reproduces the observed D vs Si trend, and predicts a high cosmic
Type Ia supernova rate, while producing a white dwarf population that accounts
for only 1.5% of the dark halo. This scenario can be tested by
observations of the cosmic supernova rate, and by confirmation and further
studies of the putative white dwarf halo population.Comment: AASTeX, 17 pages, 3 embedded eps fig
Large-scale structure in the Lyman-alpha forest II: analysis of a group of ten QSOs
The spatial distribution of Ly-alpha forest absorption systems towards ten
QSOs has been analysed to search for large-scale structure over the redshift
range 2.2 < z < 3.4. The QSOs form a closely spaced group on the sky and are
concentrated within a 1 deg^2 field. We have employed a technique based on the
first and second moments of the transmission probability density function which
is capable of identifying and assessing the significance of regions of over- or
underdense Ly-alpha absorption. We find evidence for large-scale structure in
the distribution of Ly-alpha forest absorption at the > 99 per cent confidence
level. In individual spectra we find overdense Ly-alpha absorption on scales of
up to 1200 km s^-1. There is also strong evidence for correlated absorption
across line of sight pairs separated by < 3 h^-1 proper Mpc (q_0 = 0.5). For
larger separations the cross-correlation signal becomes progressively less
significant.Comment: 15 pages, LaTeX, 6 Postscript figures, accepted for publication in
MNRA
Leptin and Amylin Act in an Additive Manner to Activate Overlapping Signaling Pathways in Peripheral Tissues: In vitro and ex vivo studies in humans
OBJECTIVE: Amylin interacts with leptin to alter metabolism. We evaluated, for the first time, amylin- and/or leptin-activated signaling pathways in human peripheral tissues (hPTs). RESEARCH DESIGN AND METHODS: Leptin and amylin signaling studies were performed in vitro in human primary adipocytes (hPAs) and human peripheral blood mononuclear cells (hPBMCs) and ex vivo in human adipose tissue (hAT) from male versus female subjects, obese versus lean subjects, and subjects with subcutaneous versus omental adipose tissue. RESULTS: The long form of leptin receptor was expressed in human tissues and cells studied in ex vivo and in vitro, respectively. Leptin and amylin alone and in combination activate signal transducer and activator of transcription 3 (STAT3), AMP-activated protein kinase, Akt, and extracellular signal-regulated kinase signaling pathways in hAT ex vivo and hPAs and hPBMCs in vitro; all phosphorylation events were saturable at leptin and amylin concentrations of ∼50 and ∼20 ng/ml, respectively. The effects of leptin and amylin on STAT3 phosphorylation in hPAs and hPBMCs in vitro were totally abolished under endoplasmic reticulum stress and/or in the presence of a STAT3 inhibitor. Results similar to those in the in vitro studies were observed in hAT studied ex vivo. CONCLUSIONS: Leptin and amylin activate overlapping intracellular signaling pathways in humans and have additive, but not synergistic, effects in signaling pathways studied in hPTs in vitro and ex vivo
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