Calibrated Langevin dynamics simulations of intrinsically disordered proteins

We perform extensive coarse-grained (CG) Langevin dynamics simulations of intrinsically disordered proteins (IDPs), which possess fluctuating conformational statistics between that for excluded volume random walks and collapsed globules. Our CG model includes repulsive steric, attractive hydrophobic, and electrostatic interactions between residues and is calibrated to a large collection of single-molecule fluorescence resonance energy transfer data on the inter-residue separations for 36 pairs of residues in five IDPs: $\alpha$-, $\beta$-, and $\gamma$-synuclein, the microtubule-associated protein $\tau$, and prothymosin $\alpha$. We find that our CG model is able to recapitulate the average inter-residue separations regardless of the choice of the hydrophobicity scale, which shows that our calibrated model can robustly capture the conformational dynamics of IDPs. We then employ our model to study the scaling of the radius of gyration with chemical distance in 11 known IDPs. We identify a strong correlation between the distance to the dividing line between folded proteins and IDPs in the mean charge and hydrophobicity space and the scaling exponent of the radius of gyration with chemical distance along the protein.Comment: 16 pages, 10 figure

Retrospective study of more than 9000 feline cutaneous tumours in the UK: 2006–2013

The aim of the study was to utilise a large database available from a UK-based, commercial veterinary diagnostic laboratory to ascertain the prevalence of different forms of cutaneous neoplasia within the feline population, and to detect any breed, sex or age predilections for the more common tumours

Evaluating the Whitening and Microstructural Effects of a Novel Whitening Strip on Porcelain and Composite Dental Materials.

AimsThe aim of this project was to evaluate the effects of 2 different whitening strips on color, microstructure and roughness of tea stained porcelain and composite surfaces.Methods54 porcelain and 72 composite chips served as samples for timed application of over-the-counter (OTC) test or control dental whitening strips. Chips were divided randomly into three groups of 18 porcelain and 24 composite chips each. Of these groups, 1 porcelain and 1 composite set served as controls. The remaining 2 groups were randomized to treatment with either Oral Essentials® Whitening Strips or Crest® 3D White Whitestrips™. Sample surface structure was examined by light microscopy, profilometry and Scanning Electron Microscopy (SEM). Additionally, a reflectance spectrophotometer was used to assess color changes in the porcelain and composite samples over 24 hours of whitening. Data points were analyzed at each time point using ANOVA.ResultsIn the light microscopy and SEM images, no discrete physical defects were observed in any of the samples at any time points. However, high-resolution SEM images showed an appearance of increased surface roughness in all composite samples. Using profilometry, significantly increased post-whitening roughness was documented in the composite samples exposed to the control bleaching strips. Composite samples underwent a significant and equivalent shift in color following exposure to Crest® 3D White Whitestrips™ and Oral Essentials® Whitening Strips.ConclusionsA novel commercial tooth whitening strip demonstrated a comparable beaching effect to a widely used OTC whitening strip. Neither whitening strip caused physical defects in the sample surfaces. However, the control strip caused roughening of the composite samples whereas the test strip did not

The pressure confined wind of the massive and compact superstar cluster M82-A1

The observed parameters of the young superstar cluster M82-A1 and its associated compact HII region are here shown to indicate a low heating efficiency or immediate loss, through radiative cooling, of a large fraction of the energy inserted by stellar winds and supernovae during the early evolution of the cluster. This implies a bimodal hydrodynamic solution which leads to a reduced mass deposition rate into the ISM, with a much reduced outflow velocity. Furthermore, to match the observed parameters of the HII region associated to M82-A1, the resultant star cluster wind is here shown to ought to be confined by a high pressure interstellar medium. The cluster wind parameters, as well as the location of the reverse shock, its cooling length and the radius of the standing outer HII region are derived analytically. All of these properties are then confirmed with a semi-analytical integration of the flow equations, which provides us also with the run of the hydrodynamic variables as a function of radius. The impact of the results is discussed and extended to other massive and young superstar clusters surrounded by a compact HII region.Comment: 19 pages, 4 figures, accepted for publication in Ap

Bis[μ-methyl­enebis(diphenyl­phosphine)]bis­[(5-nitro-1,10-phenanthroline)silver(I)] bis­(hexa­fluoridoanti­monate)

In the title compound, [Ag2(C12H7N3O2)2(C25H22P2)2](SbF6)2, the two AgI atoms are bridged by the two methyl­enebis(diphenyl­phosphine) ligands and an eight-membered centrosymmetric metallacyclic ring is formed. The metal atom exhibits a distorted tetra­hedral coordination geometry, coordinated by two P atoms of the bridging ligands and two N atoms of the chelating 5-nitro-1,10-phenanthroline ligand. The latter ligand shows minor disorder, adopting two orientations with site occupancy factors of 0.84 and 0.16

Chandra Discovery of a Binary Active Galactic Nucleus in Mrk 739

We have discovered a binary AGN in the galaxy Mrk 739 using Chandra and Swift BAT. We find two luminous L_2-10 keV=1.1*10^43 and 1.0*10^42 erg/s, unresolved nuclei with a projected separation of 3.4 kpc (5.8\pm0.1) coincident with two bulge components in the optical image. The western X-ray source (Mrk 739W) is highly variable (2.5x) during the 4-hour Chandra observation and has a very hard spectrum consistent with an AGN. While the eastern component was already known to be an AGN based on the presence of broad optical recombination lines, Mrk 739W shows no evidence of being an AGN in optical, UV, and radio observations, suggesting the critical importance of high spatial resolution hard X-ray observations (>2 keV) in finding these binary AGN. A high level of star formation combined with a very low L_[O III]/L_2-10 keV ratio cause the AGN to be missed in optical observations. CO observations of the (3-2) and (2-1) lines indicate large amounts of molecular gas in the system that could be driven towards the black holes during the violent galaxy collision and be key to fueling the binary AGN. Mrk 739E has a high Eddington ratio of 0.71 and a small black hole (log M_BH=7.05\pm0.3) consistent with an efficiently accreting AGN. Other than NGC 6240, this stands as the nearest case of a binary AGN discovered to date.Comment: 7 pages, 5 figures, Published in Astrophysical Journal Letters. Reformatted and fixed typos in v

KINETICS OF SIMULATED ON-WATER DRAGON BOAT PADDLING

INTRODUCTION: Dragon boat racing involves 20 paddlers propelling the boat through power at the blade which is transferred to boat movement through the paddler’s contact with the boat at the feet and seat. However, the magnitude of these forces and their synchronisation and contribution to boat movement is unknown. Thus the aim of this study is to investigate the kinetics of simulated on-water paddling

EFFECT OF STROKE RATE ON KINEMATIC CHARACTERISTICS OF SIMULATED ON-WATER DRAGON BOAT PADDLING

The purpose of this study was to determine the effect of stroke rate on the 3D kinematics of simulated on-water dragon boat paddling. Twenty dragon boat paddlers (female=12, male=8) ranging in experience level, paddled in a simulated on-water dragon boat condition in a motion laboratory at stroke rates of 40, 50 and 60 strokes·min-1. With an increase in stroke rate, there was a significant decrease in stroke length and increase in drive time to total stroke time ratio (