316 research outputs found
Minimally Invasive Mitral Valve Surgery III: Training and Robotic-Assisted Approaches.
Minimally invasive mitral valve operations are increasingly common in the United States, but robotic-assisted approaches have not been widely adopted for a variety of reasons. This expert opinion reviews the state of the art and defines best practices, training, and techniques for developing a successful robotics program
Minimally Invasive Mitral Valve Surgery I: Patient Selection, Evaluation, and Planning.
Widespread adoption of minimally invasive mitral valve repair and replacement may be fostered by practice consensus and standardization. This expert opinion, first of a 3-part series, outlines current best practices in patient evaluation and selection for minimally invasive mitral valve procedures, and discusses preoperative planning for cannulation and myocardial protection
Minimally Invasive Mitral Valve Surgery II: Surgical Technique and Postoperative Management.
Techniques for minimally invasive mitral valve repair and replacement continue to evolve. This expert opinion, the second of a 3-part series, outlines current best practices for nonrobotic, minimally invasive mitral valve procedures, and for postoperative care after minimally invasive mitral valve surgery
Galaxy Pairs in the Sloan Digital Sky Survey - II: The Effect of Environment on Interactions
We use a sample of close galaxy pairs selected from the Sloan Digital Sky
Survey Data Release 4 (SDSS DR4) to investigate in what environments galaxy
mergers occur and how the results of these mergers depend on differences in
local galaxy density. The galaxies are quantified morphologically using
two-dimensional bulge-plus-disk decompositions and compared to a control sample
matched in stellar mass, redshift and local projected density. Lower density
environments have fractionally more galaxy pairs with small projected
separations (r_p) and relative velocities (Delta v), but even high density
environments contain significant populations of pairs with parameters that
should be conducive to interactions. Metrics of asymmetry and colour are used
to identify merger activity and triggered star formation. The location of star
formation is inferred by distinguishing bulge and disk colours and calculating
bulge fractions from the SDSS images. Galaxies in the lowest density
environments show the largest changes in star formation rate, asymmetry and
bulge-total fractions at small separations, accompanied by bluer bulge colours.
At the highest local densities, the only galaxy property to show an enhancement
in the closest pairs is asymmetry. We interpret these results as evidence that
whilst interactions (leading to tidal distortions) occur at all densities,
triggered star formation is seen only in low-to-intermediate density
environments. We suggest that this is likely due to the typically higher gas
fractions of galaxies in low density environments. Finally, by
cross-correlating our sample of galaxy pairs with a cluster catalogue, we
investigate the dependence of interactions on clustercentric distance. It is
found that for close pairs the fraction of asymmetric galaxies is highest in
the cluster centres.Comment: Accepted by MNRAS, 15 page
Mode of action of DNA-competitive small molecule inhibitors of tyrosyl DNA phosphodiesterase 2
TDP2 is a 5’-tyrosyl DNA phosphodiesterase important for the repair of DNA adducts generated by non-productive (abortive) activity of topoisomerase II. TDP2 facilitates therapeutic resistance to topoisomerase poisons, which are widely used in the treatment of a range of cancer types. Consequently, TDP2 is an interesting target for the development of small molecule inhibitors that could restore sensitivity to topoisomerase-directed therapies. Previous studies identified a class of deazaflavin-based molecules that showed inhibitory activity against TDP2 at therapeutically useful concentrations, but their mode of action was uncertain. We have confirmed that the deazaflavin series inhibits TDP2 enzyme activity in a fluorescence-based assay, suitable for HTS-screening. We have gone on to determine crystal structures of these compounds bound to a ‘humanised’ form of murine TDP2. The structures reveal their novel mode of action as competitive ligands for the binding site of an incoming DNA substrate, and point the way to generating novel and potent inhibitors of TDP2
Photolithographic patterning of conducting polyaniline films via flash welding
In this work, two significant advances in photolithographic patterning of polyaniline (PANI) films are reported. Firstly, flash welding was enhanced through the use of polymeric substrates, enabling complete penetration of the welding of PANI films with thicknesses ranging from 5 to over 14 mu m, significantly thicker than reported previously. Masking of parts of the PANI films during flash welding enabled the formation of adjacent conducting and insulating regions as the welding changes the electrical properties of the film. Raman spectroscopy was used to determine the sharpness of these edges, and indicated that the interface between the flash welded and masked regions of the PANI films was typically less than 15 mu m wide. Secondly, using longpass filters, light with a wavelength less than 570 nm was found not to contribute to the welding process. This was confirmed by the use of a 635 nm laser diode for welding the PANI films. This novel approach enabled patterning of PANI films using a direct writing technique with a narrow wavelength light source
Amyloid-Associated Nucleic Acid Hybridisation
Nucleic acids promote amyloid formation in diseases including Alzheimer's
and Creutzfeldt-Jakob disease. However, it remains unclear whether the close
interactions between amyloid and nucleic acid allow nucleic acid secondary
structure to play a role in modulating amyloid structure and function. Here we
have used a simplified system of short basic peptides with alternating
hydrophobic and hydrophilic amino acid residues to study nucleic acid - amyloid
interactions. Employing biophysical techniques including X-ray fibre
diffraction, circular dichroism spectroscopy and electron microscopy we show
that the polymerized charges of nucleic acids concentrate and enhance the
formation of amyloid from short basic peptides, many of which would not
otherwise form fibres. In turn, the amyloid component binds nucleic acids and
promotes their hybridisation at concentrations below their solution
Kd, as shown by time-resolved FRET studies. The
self-reinforcing interactions between peptides and nucleic acids lead to the
formation of amyloid nucleic acid (ANA) fibres whose properties are distinct
from their component polymers. In addition to their importance in disease and
potential in engineering, ANA fibres formed from prebiotically-produced peptides
and nucleic acids may have played a role in early evolution, constituting the
first entities subject to Darwinian evolution
The dopamine D2 receptor antagonist sulpiride modulates striatal BOLD signal during the manipulation of information in working memory
The KMOS Cluster Survey (KCS) II - The Effect of Environment on the Structural Properties of Massive Cluster Galaxies at Redshift
We present results on the structural properties of massive passive galaxies in three clusters at 1.39<z<1.61 from the KMOS Cluster Survey. We measure light-weighted and mass-weighted sizes from optical and near-infrared Hubble Space Telescope imaging and spatially resolved stellar mass maps. The rest-frame R-band sizes of these galaxies are a factor of ∼2−3 smaller than their local counterparts. The slopes of the relation between the stellar mass and the light-weighted size are consistent with recent studies in clusters and the field. Their mass-weighted sizes are smaller than the rest frame R-band sizes, with an average mass-weighted to light-weighted size ratio that varies between ∼0.45 and 0.8 among the clusters. We find that the median light-weighted size of the passive galaxies in the two more evolved clusters is ∼24% larger than for field galaxies, independent of the use of circularized effective radii or semi-major axes. These two clusters also show a smaller size ratio than the less evolved cluster, which we investigate using color gradients to probe the underlying M∗/LH160 gradients. The median color gradients are ∇z−H∼−0.4 mag dex−1, twice the local value. Using stellar populations models, these gradients are best reproduced by a combination of age and metallicity gradients. Our results favor the minor merger scenario as the dominant process responsible for the observed galaxy properties and the environmental differences at this redshift. The environmental differences support that clusters experience accelerated structural evolution compared to the field, likely via an epoch of enhanced minor merger activity during cluster assembly
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