Tumbleweeds and airborne gravitational noise sources for LIGO

Gravitational-wave detectors are sensitive not only to astrophysical gravitational waves, but also to the fluctuating Newtonian gravitational forces of moving masses in the ground and air around the detector. This paper studies the gravitational effects of density perturbations in the atmosphere, and from massive airborne objects near the detector. These effects were previously considered by Saulson; in this paper I revisit these phenomena, considering transient atmospheric shocks, and the effects of sound waves or objects colliding with the ground or buildings around the test masses. I also consider temperature perturbations advected past the detector as a source of gravitational noise. I find that the gravitational noise background is below the expected noise floor even of advanced interferometric detectors, although only by an order of magnitude for temperature perturbations carried along turbulent streamlines. I also find that transient shockwaves in the atmosphere could potentially produce large spurious signals, with signal-to-noise ratios in the hundreds in an advanced interferometric detector. These signals could be vetoed by means of acoustic sensors outside of the buildings. Massive wind-borne objects such as tumbleweeds could also produce gravitational signals with signal-to-noise ratios in the hundreds if they collide with the interferometer buildings, so it may be necessary to build fences preventing such objects from approaching within about 30m of the test masses.Comment: 15 pages, 10 PostScript figures, uses REVTeX4.cls and epsfig.st

Hydrogen adsorption and cohesive energy of single-walled carbon nanotubes

Hydrogen adsorption on crystalline ropes of carbon single-walled nanotubes (SWNT) was found to exceed 8 wt.%, which is the highest capacity of any carbon material. Hydrogen is first adsorbed on the outer surfaces of the crystalline ropes. At pressures higher than about 40 bar at 80 K, however, a phase transition occurs where there is a separation of the individual SWNTs, and hydrogen is physisorbed on their exposed surfaces. The pressure of this phase transition provides a tube-tube cohesive energy for much of the material of 5 meV/C atom. This small cohesive energy is affected strongly by the quality of crystalline order in the ropes

Effect of two different participant information sheets on recruitment to a falls trial:an embedded randomised recruitment trial

Background/Aims: Recruitment to trials of intervention for older people who fall is challenging. Evidence suggests that the word falls has negative connotations for older people, and this may present a barrier to engaging with trials in this area. We therefore tested whether a participant information sheet that minimised reference to falls could improve recruitment rates. Methods: We conducted a study within a trial, embedded within a randomised controlled trial of vitamin K versus placebo to improve postural sway in patients aged 65 and over with a history of falls. Potential participants were identified from primary care lists in 14 practices and were randomised to receive either a standard participant information sheet or an information sheet minimising use of the word falls, instead focussing on maintenance of health, fitness and balance. The primary outcome for this embedded trial was the proportion of responses expressing interest in participating received in each arm. Secondary outcomes were the proportion of those contacted attending a screening visit, consenting at screening, and the proportion contacted who were randomised into the main trial. Results: In all, 4145 invitations were sent, with an overall response rate of 444 (10.7%). In all, 2148 individuals received the new information sheet (minimising reference to falls); 1997 received the standard information sheet. There was no statistically significant difference in response rate between those individuals sent the new information sheet and those sent the standard information sheet (10.1% vs 11.4%; difference 1.3% (95% confidence interval -0.6% to 3.2%); p = 0.19). Similarly, we found no statistically significant difference between the percentage of those who attended and consented at screening in the two groups (2.1% vs 2.7%; difference 0.6% (95% confidence interval: -0.4% to 1.6%); p = 0.20), and no statistically significant difference between the percentage randomised in the two groups (2.0% vs 2.6%; difference 0.6% (95% confidence interval -0.4% to 1.6%); p = 0.20). Conclusions: Use of a participant information sheet minimising reference to falls did not lead to a greater response rate in this trial targeting older people with a history of falls.</p

Current practice in the diagnosis and management of sarcopenia and frailty – results from a UK-wide survey

Objectives: Despite a rising clinical and research profile, there is limited information about how frailty and sarcopenia are diagnosed and managed in clinical practice. Our objective was to build a picture of current practice by conducting a survey of UK healthcare professionals. Methods: We surveyed healthcare professionals in NHS organisations, using a series of four questionnaires. These focussed on the diagnosis and management of sarcopenia, and the diagnosis and management of frailty in acute medical units, community settings and surgical units. Results: Response rates ranged from 49/177 (28%) organisations for the sarcopenia questionnaire to 104/177 (59%) for the surgical unit questionnaire. Less than half of responding organisations identified sarcopenia; few made the diagnosis using a recognised algorithm or offered resistance training. The commonest tools used to identify frailty were the Rockwood Clinical Frailty Scale or presence of a frailty syndrome. Comprehensive Geriatric Assessment was offered by the majority of organisations, but this included exercise therapy in less than half of cases, and medication review in only one-third to two-thirds of cases. Conclusions: Opportunities exist to improve consistency of diagnosis and delivery of evidence-based interventions for both sarcopenia and frailty

A 15 year record of high-frequency, in situ measurements of hydrogen at Mace Head, Ireland

Continuous high-frequency measurements of atmospheric molecular hydrogen have been made at Mace Head atmospheric research station on the west coast of Ireland from March 1994 to December 2008. The presented data provides information on long term trends and seasonal cycles of hydrogen in background northern hemispheric air. Individual measurements have been sorted using a Lagrangian dispersion model to separate clean background air from regionally polluted European air masses and those transported from southerly latitudes. No significant trend was observed in background northern hemispheric air over the 15 year record, elevations in yearly means were accounted for from large scale biomass burning events. Seasonal cycles show the expected pattern with maxima in spring and minima in late autumn. The mean hydrogen mole fraction in baseline northern hemispheric air was found to be 500.1 ppb. Air transported from southerly latitudes showed an elevation from baseline mean of 11.0 ppb, reflecting both the latitudinal gradient of hydrogen, with higher concentrations in the Southern Hemisphere, and the photochemical source of hydrogen from low northern latitudes. European polluted air masses arriving at Mace Head showed mean elevation of 5.3 ppb from baseline air masses, reflecting hydrogen's source from primary emissions like fossil fuel combustion. Forward modelling of transport of hydrogen to Mace Head suggests that the ratio of hydrogen to carbon monoxide in primary emissions is considerably less in non-traffic sources than traffic sources

Galactic Plane Hα\alpha Surveys: IPHAS & VPHAS+

The optical Galactic Plane H$\alpha$ surveys IPHAS and VPHAS+ are dramatically improving our understanding of Galactic stellar populations and stellar evolution by providing large samples of stars in short lived, but important, evolutionary phases, and high quality homogeneous photometry and images over the entire Galactic Plane. Here I summarise some of the contributions these surveys have already made to our understanding of a number of key areas of stellar and Galactic astronomy.Comment: 5 pages, 2 figures, refereed proceeding of the "The Universe of Digital Sky Surveys" conference, November 2014, to be published in the Astrophysics and Space Science Proceeding

On the Theory of Relativistic Strong Plasma Waves

The influence of motion of ions and electron temperature on nonlinear one-dimensional plasma waves with velocity close to the speed of light in vacuum is investigated. It is shown that although the wavebreaking field weakly depends on mass of ions, the nonlinear relativistic wavelength essentially changes. The nonlinearity leads to the increase of the strong plasma wavelength, while the motion of ions leads to the decrease of the wavelength. Both hydrodynamic approach and kinetic one, based on Vlasov-Poisson equations, are used to investigate the relativistic strong plasma waves in a warm plasma. The existence of relativistic solitons in a thermal plasma is predicted.Comment: 13 pages, 8 figure

Delayed bowel perforation following suprapubic catheter insertion

BACKGROUND: Complications of suprapubic catheter insertion are rare but can be significant. We describe an unusual complication of a delayed bowel perforation following suprapubic catheter insertion. CASE PRESENTATION: A gentleman presented with features of peritonitis and feculent discharge along a suprapubic catheter two months after insertion of the catheter. CONCLUSION: Bowel perforation is the most feared complication of suprapubic catheter insertion especially in patients with lower abdominal scar. The risk may be reduced with the use of ultrasound scan guidance

Interventions to prevent non-critical care hospital acquired pneumonia – a systematic review

Background: Hospital-acquired pneumonia is a significant burden to healthcare systems around the world. Although there is a considerable body of evidence on prevention of ventilator associated pneumonia, less is known about strategies to prevent hospital-acquired pneumonia in non-critical care settings. Objective: To systematically review the randomised controlled trial evidence for prevention of hospital-acquired pneumonia in non-critical care settings. Methods: We searched EMBASE, CINAHL+, MEDLINE and the Cochrane Library. Seventeen different searches were conducted in parallel through each database. Studies were included if they were randomised controlled trials reporting hospital-acquired pneumonia as an endpoint. Studies were excluded if they were performed in critical care or community settings. All studies published up to the end of December 2014 were considered, with no language restrictions. Data were independently extracted by two authors and the Delphi risk of bias tool was applied to assess trial quality. Results: Five thousand one hundred and one titles were identified across 17 searches. Only two studies were eligible for inclusion in the final review, one from a search of physical therapy interventions and one from a search of enteral feeding. The heterogeneity of the interventions did not permit meta-analysis. One trial suggested possible benefits to early mobilisation; the other trial suggested no benefit or harm from early enteral feeding via nasogastric tube. Both trials enrolled patients with acute stroke. No trials in non-stroke, non-critical care populations were eligible for inclusion in the review. Conclusions: There is currently insufficient trial evidence on preventing non-critical care hospital-acquired pneumonia to make recommendations on practice.</p