1,026 research outputs found
Time trends in survival and readmission following coronary artery bypass grafting in Scotland, 1981-96: retrospective observational study
Improvements in coronary revascularisation techniques and an increase in the use of percutaneous interventions1 have led to a rise in the number of coronary artery bypass grafting operations in older patients with more severe cardiac disease and worse comorbidity and who have previously undergone revascularisation procedures. 2 3 Advances in surgical and anaesthetic techniques have prevented a worsening risk profile from being translated into an increase in perioperative deaths. 2 3 The aim of our study was to examine time trends in major outcomes up to two years after coronary artery bypass grafting
Influence of radiative damping on the optical-frequency susceptibility
Motivated by recent discussions concerning the manner in which damping
appears in the electric polarizability, we show that (a) there is a dependence
of the nonresonant contribution on the damping and that (b) the damping enters
according to the "opposite sign prescription." We also discuss the related
question of how the damping rates in the polarizability are related to
energy-level decay rates
Solid-state laser system for laser cooling of Sodium
We demonstrate a frequency-stabilized, all-solid laser source at 589 nm with
up to 800 mW output power. The laser relies on sum-frequency generation from
two laser sources at 1064 nm and 1319 nm through a PPKTP crystal in a
doubly-resonant cavity. We obtain conversion efficiency as high as 2 W/W^2
after optimization of the cavity parameters. The output wavelength is tunable
over 60 GHz, which is sufficient to lock on the Sodium D2 line. The robustness,
beam quality, spectral narrowness and tunability of our source make it an
alternative to dye lasers for atomic physics experiments with Sodium atoms
Transcriptional regulation of the urokinase receptor (u-PAR) - A central molecule of invasion and metastasis
The phenomenon of tumor-associated proteolysis has been acknowledged as a decisive step in the progression of cancer. This short review focuses on the urokinase receptor (u-PAR), a central molecule involved in tumor-associated invasion and metastasis, and summarizes the transcriptional regulation of u-PAR. The urokinase receptor (u-PAR) is a heavily glycosylated cell surface protein and binds the serine protease urokinase specifically and with high affinity. It consists of three similar cysteine-rich repeats and is anchored to the cell membrane via a GPI-anchor. The u-PAR gene comprises 7 exons and is located on chromosome 19q13. Transcriptional activation of the u-PAR promoter region can be induced by binding of transcription factors (Sp1, AP-1, AP-2, NF-kappaB). One current study gives an example for transcriptional downregulation of u-PAR through a PEA3/ets transcriptional silencing element. Knowledge of the molecular regulation of this molecule in tumor cells could be very important for diagnosis and therapy in the near future
Estuarine Infauna Within Incidentally Retained Sediment in Artificial Rockpools
Artificial coastal structures (ACSs) are primarily designed to provide services for
human use, such as flood defence or shipping, and are generally poor for marine
biodiversity. Consequently, there has been significant research effort to enhance these
hard structures to increase biodiversity and habitat availability via eco-engineering. On
seawalls and breakwaters, this has included the creation of habitats for benthic species
found on natural rocky shores, including the provision of cracks, crevices and water
retaining features, such as artificial rockpools. When sediment retention in these features
has occurred, it has often been deemed detrimental to the overarching aim of the
intervention. Yet, it is soft sediment habitat that is impacted the most through coastal
construction. As ecological enhancement of a flood defence scheme, nine concrete
retrofit rockpools were installed at three different tidal elevations between mean high
water neap tide and mean tide level on steel sheet piling on the Arun Estuary in
Littlehampton Harbour, United Kingdom, which naturally filled with mud 1 year after
installation. To explore how analogous the faunal assemblages and sediment profile of
rockpool mud were to two local mudflats, core samples were taken and analysed for
species richness, abundance, biomass, assemblage structure, median grain size, and
organic matter content. More benthic species were observed in the artificial rockpool
than in the local mudflats. Although the rockpools were placed at higher tidal levels than
the lower shore mudflat, their assemblage structure and species richness were more
similar to the lower shore mudflat at the base of the sheet piling than the upper shore
mudflat. This study demonstrates that retained sediment within eco-engineered features
on hard ACSs can create habitat for benthic assemblages. Providing sediment-retentive
features on ACSs has the potential to provide a novel eco-engineering option that may
be appropriate for some heavily modified waterbodies on sheltered, depositional coasts
Resumming the color-octet contribution to e+ e- -> J/psi + X
Recent observations of the spectrum of J/psi produced in e+ e- collisions at
the Upsilon(4S) resonance are in conflict with fixed-order calculations using
the Non-Relativistic QCD (NRQCD) effective field theory. One problem is that
leading order color-octet mechanisms predict an enhancement of the cross
section for J/psi with maximal energy that is not observed in the data.
However, in this region of phase space large perturbative corrections (Sudakov
logarithms) as well as enhanced nonperturbative effects are important. In this
paper we use the newly developed Soft-Collinear Effective Theory (SCET) to
systematically include these effects. We find that these corrections
significantly broaden the color-octet contribution to the J/psi spectrum. Our
calculation employs a one-stage renormalization group evolution rather than the
two-stage evolution used in previous SCET calculations. We give a simple
argument for why the two methods yield identical results to lowest order in the
SCET power counting.Comment: 27 pages, 7 figure
Threshold for strong thermal dephasing in periodically poled KTP in external cavity frequency doubling
Tracking Performance of the Scintillating Fiber Detector in the K2K Experiment
The K2K long-baseline neutrino oscillation experiment uses a Scintillating
Fiber Detector (SciFi) to reconstruct charged particles produced in neutrino
interactions in the near detector. We describe the track reconstruction
algorithm and the performance of the SciFi after three years of operation.Comment: 24pages,18 figures, and 1 table. Preprint submitted to NI
Spatial Stability of Incompressible Attachment-Line Flow
Linear stability analysis of incompressible attachment-line flow is presented within the spatial framework. The system of perturbation equations is solved using spectral collocation. This system has been solved in the past using the temporal approach and the current results are shown to be in excellent agreement with neutral temporal calculations. Results amenable to direct comparison with experiments are then presented for the case of zero suction. The global solution method utilized for solving the eigenproblem yields, aside from the well-understood primary mode, the full spectrum of least-damped waves. Of those, a new mode, well separated from the continuous spectrum is singled out and discussed. Further, relaxation of the condition of decaying perturbations in the far-field results in the appearance of sinusoidal modes akin to those found in the classical Orr-Sommerfeld problem. Finally, the continuous spectrum is demonstrated to be amenable to asymptotic analysis. Expressions are derived for the location, in parameter space, of the continuous spectrum, as well as for the limiting cases of practical interest. In the large Reynolds number limit the continuous spectrum is demonstrated to be identical to that of the Orr-Sommerfeld equation
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