Cosmological structure formation from soft topological defects

Some models have extremely low-mass pseudo-Goldstone bosons that can lead to vacuum phase transitions at late times, after the decoupling of the microwave background.. This can generate structure formation at redshifts z greater than or approx 10 on mass scales as large as M approx 10 to the 18th solar masses. Such low energy transitions can lead to large but phenomenologically acceptable density inhomogeneities in soft topological defects (e.g., domain walls) with minimal variations in the microwave anisotropy, as small as delta Y/T less than or approx 10 to the minus 6 power. This mechanism is independent of the existence of hot, cold, or baryonic dark matter. It is a novel alternative to both cosmic string and to inflationary quantum fluctuations as the origin of structure in the Universe

Research on the external fluid mechanics of ocean thermal energy conversion plants : report covering experiments in a current

This report describes a set of experiments in a physical model study to explore plume transport and recirculation potential for a range of generic Ocean Thermal Energy Conversion (OTEC) plant designs and ambient conditions. Tests were conducted in a thermally-stratified 12 m x 18 m x 0.6 m basin, at an undistorted length scale ratio of 1:300, which allowed the upper 180 m of the ocean to be studied. Conditions which have been tested include a range of plant sizes (nominally 200 MWe - 600 MWe); a range of discharge configurations (mixed vs. non-mixed evaporator and condenser flows, multiple vs. radial slot discharge port(s), variation of discharge-intake separation and variation of discharge angle); and a range of ambient current speeds (0.15 - 1.0 m/s), and density profiles (surface mixed layers of 31 to 64 m). The tests described herein complement those reported previously (Adams et al., 1979) for a stagnant-ambient environment.Measurements included temperature, dye concentration and visual observations from still and motion pictures. Results derived from these measurements are presented in tables and graphs in prototype dimensions for direct use by OTEC designers. Many of the results are also analyzed and presented in non-dimensional terms to extend their generality. No significant recirculation was observed for any tests with a discharge directed with a vertical (downward) component. For tests with a horizontal discharge, recirculation was observed to be a complex function of a number of parameters. For sufficiently shallow discharge submergence, low to moderate current speeds, and with plants employing a radial slot discharge, recirculation could result from dynamic pressures caused by the proximity of the free surface - despite the negative plume buoyancy. This mode was labelled "confinement-induced" recirculation and led to measurements of direct recirculation ranging from 25% to 40%.For certain combinations of ambient current speed and generally positive plume buoyancy (resultIng from deeper discharge submergence), the plume was observed to billow upward resulting in "current-induced" recirculation. This was observed for both radial slot and multiple port discharge configurations although somewhat greater recirculation was observed with the former configuration. Measured recirculation for current-induced recirculation fell in the range 0 to 10% with a peak occurring at intermediate current speeds of about 0.5 m/s. Experiments with a mixed evaporator and condenser discharge showed less tendency for direct recirculation of either type than the separate (evaporator only) discharges, but the effects of recirculation, as measured by the drop in evaporator intake temDerature (below the ambient temperature at the level of the intake) were not very different. A simple mathematical model, based on the governing length scales, was successfully calibrated to the observed values of direct recirculation for the radial discharge case.Various measures of plume transport were summarized to help designers predict the impact of OTEC operation on the environment and to establish guidelines for spacing of multiple plants. Minimum near field dilutions were observed in the range between 5 and 10 indicating that the peak concentration of any chemicals contained in the discharge would be between 10 and 20% of the discharge concentration. Near field horizontal and vertical dimensions of the plume wake were found to be correlated with a length scale derived from discharge kinematic momentum flux and ambient current speed. The rise and fall of the equilibrium plume elevation (above or below the discharge elevation) was found to be governed by a ratio of length scales based on the ambient density profile and the discharge kinematic momentum and buoyancy fluxes

A Role for Nogo Receptor in Macrophage Clearance from Injured Peripheral Nerve

SummaryWe report a role for Nogo receptors (NgRs) in macrophage efflux from sites of inflammation in peripheral nerve. Increasing numbers of macrophages in crushed rat sciatic nerves express NgR1 and NgR2 on the cell surface in the first week after injury. These macrophages show reduced binding to myelin and MAG in vitro, which is reversed by NgR siRNA knockdown and by inhibiting Rho-associated kinase. Fourteen days after sciatic nerve crush, regenerating nerves with newly synthesized myelin have fewer macrophages than cut/ligated nerves that lack axons and myelin. Almost all macrophages in the cut/ligated nerves lie within the Schwann cell basal lamina, while in the crushed regenerating nerves the majority migrate out. Furthermore, crush-injured nerves of NgR1- and MAG-deficient mice and Y-27632-treated rats show impaired macrophage efflux from Schwann cell basal lamina containing myelinated axons. These data have implications for the resolution of inflammation in peripheral nerve and CNS pathologies

A Comparison of GPS Workload Demands in Match Play and Small-Sided Games by the Positional Role in Youth Soccer

The external demands of small-sided games (SSGs) according to the positional role are currently unknown. Using a Catapult Minimax X3 5 Hz GPS, with a 100 Hz tri-axial accelerometer, we compared the accumulated tri-axial player workload per min (PLacc·min(-1)) during friendly youth match play (MP) (11 vs. 11) and SSGs (2 vs. 2, 3 vs. 3, and 4 vs. 4). Significant differences existed between all SSGs and MP for PLacc·min(-1) (F = 21.91, p < 0.001, η2 = 0.38), and individual X (F = 27.40, p < 0.001, η2 = 0.43), Y (F = 14.50, p < 0.001, η2 = 0.29) and Z (F = 19.28, p < 0.001, η2 = 0.35) axis loads. Across all conditions, mean PLacc·min(-1) was greater for midfielders (p = 0.004, CI: 0.68, 4.56) and forwards (p = 0.037, CI: 0.08, 3.97) than central defenders. In all conditions, greater Y axis values existed for wide defenders (p = 0.024, CI: 0.67, 1.38), midfielders (p = 0.006, CI: 0.18, 1.50) and forwards (p = 0.007, CI: 0.17, 0.15) compared to central defenders. Midfielders reported greater Z axis values compared to central defenders (p = 0.002, CI: 0.40, 2.23). We concluded that SSGs elicited greater external loads than MP, and previous studies may have underestimated the demands of SSGs

Equine Rhinitis A Virus and Its Low pH Empty Particle: Clues Towards an Aphthovirus Entry Mechanism?

Equine rhinitis A virus (ERAV) is closely related to foot-and-mouth disease virus (FMDV), belonging to the genus Aphthovirus of the Picornaviridae. How picornaviruses introduce their RNA genome into the cytoplasm of the host cell to initiate replication is unclear since they have no lipid envelope to facilitate fusion with cellular membranes. It has been thought that the dissociation of the FMDV particle into pentameric subunits at acidic pH is the mechanism for genome release during cell entry, but this raises the problem of how transfer across the endosome membrane of the genome might be facilitated. In contrast, most other picornaviruses form ‘altered’ particle intermediates (not reported for aphthoviruses) thought to induce membrane pores through which the genome can be transferred. Here we show that ERAV, like FMDV, dissociates into pentamers at mildly acidic pH but demonstrate that dissociation is preceded by the transient formation of empty 80S particles which have released their genome and may represent novel biologically relevant intermediates in the aphthovirus cell entry process. The crystal structures of the native ERAV virus and a low pH form have been determined via highly efficient crystallization and data collection strategies, required due to low virus yields. ERAV is closely similar to FMDV for VP2, VP3 and part of VP4 but VP1 diverges, to give a particle with a pitted surface, as seen in cardioviruses. The low pH particle has internal structure consistent with it representing a pre-dissociation cell entry intermediate. These results suggest a unified mechanism of picornavirus cell entry

The tripartite associations between bacteriophage, Wolbachia, and arthropods

© 2006 Bordenstein et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The definitive version was published in PLoS Pathogens 2(2006): e43, doi:10.1371/journal.ppat.0020043.By manipulating arthropod reproduction worldwide, the heritable endosymbiont Wolbachia has spread to pandemic levels. Little is known about the microbial basis of cytoplasmic incompatibility (CI) except that bacterial densities and percentages of infected sperm cysts associate with incompatibility strength. The recent discovery of a temperate bacteriophage (WO-B) of Wolbachia containing ankyrin-encoding genes and virulence factors has led to intensifying debate that bacteriophage WO-B induces CI. However, current hypotheses have not considered the separate roles that lytic and lysogenic phage might have on bacterial fitness and phenotype. Here we describe a set of quantitative approaches to characterize phage densities and its associations with bacterial densities and CI. We enumerated genome copy number of phage WO-B and Wolbachia and CI penetrance in supergroup A- and B-infected males of the parasitoid wasp Nasonia vitripennis. We report several findings: (1) variability in CI strength for A-infected males is positively associated with bacterial densities, as expected under the bacterial density model of CI, (2) phage and bacterial densities have a significant inverse association, as expected for an active lytic infection, and (3) CI strength and phage densities are inversely related in A-infected males; similarly, males expressing incomplete CI have significantly higher phage densities than males expressing complete CI. Ultrastructural analyses indicate that approximately 12% of the A Wolbachia have phage particles, and aggregations of these particles can putatively occur outside the Wolbachia cell. Physical interactions were observed between approximately 16% of the Wolbachia cells and spermatid tails. The results support a low to moderate frequency of lytic development in Wolbachia and an overall negative density relationship between bacteriophage and Wolbachia. The findings motivate a novel phage density model of CI in which lytic phage repress Wolbachia densities and therefore reproductive parasitism. We conclude that phage, Wolbachia, and arthropods form a tripartite symbiotic association in which all three are integral to understanding the biology of this widespread endosymbiosis. Clarifying the roles of lytic and lysogenic phage development in Wolbachia biology will effectively structure inquiries into this research topic.This work was supported by grants from the NASA Astrobiology Institute (NNA04CC04A) and National Institutes of Health (R01 GM62626-01) to JJW, and by the Marine Biological Laboratory's Program in Global Infectious Diseases, funded by the Ellison Medical Foundation, to SRB

‘Getting Back Into the Swing of Things’: A Qualitative Study Into Barriers and Facilitators to Golf Participation for Stroke Survivors

This paper draws on interviews with four stroke survivors (age range = 52–68 years), who participated in a six week ‘Get-into-Golf’ program and four coaches with experiences of delivering disability golf sessions, to examine the barriers and facilitators to golf participation. Findings indicate a positive response from participants, who referred to the social and physical benefits of the program that was perceived to promote independence. The results also highlight that considerations in regards to format, equipment, cost, access and overall awareness should be borne in mind for golf programs among people with disabilities. Golf clubs could employ this framework to help facilitate the participation of people with physical limitations. It is argued that opportunities to promote golf as a lifelong physical activity among people with disabilities may be missed in clubs where personnel are unsure of the barriers and facilitators to participation outlined here

Tip-Leakage Vortex Inception on a Ducted Rotor

The tip-leakage vortex occurring on a ducted rotor was examined using both three component Laser Doppler Velocimetry (LDV) and planar Particle Imaging Velocimetry (PIV). The vortex strength and core size were examined for different vortex cross sections downstream of the blade trailing edge. The variability of these quantities are observed with PIV and the average quantities are compared between LDV and PIV. Developed cavitation is also examined for the leakage vortex. The implication of vortex variability on cavitation inception is discussed

The Ministry of Works and the Development of Souvenir Guides from 1955

The first formal guidebooks for historic sites placed in state guardianship in the United Kingdom appeared in 1917. There was an expansion of the series in the 1930s and 1950s. However, from the late 1950s the Ministry of Works, and later the Ministry of Public Buildings and Works, started to produce an additional series of illustrated souvenir guides. One distinct group covered Royal Palaces: the Tower of London, Hampton Court Palace, Queen Victoria's residence of Osborne House on the Isle of Wight, and Holyroodhouse in Edin-burgh. This was followed by guides for archaeological sites such as Stone-henge and Avebury, the Neolithic flint mines at Grime's Graves, the Roman villa at Lullingstone, and Hadrian's Wall. In 1961, a series of guides, with covers designed by Kyffin Williams, was produced for the English castles constructed in North Wales. These illustrated guides, some with colour, prepared the way for the fully designed guides now produced by English Heritage, Cadw, and Historic Environment Scotland