The effects of cationic surfactants on marine biofilm growth on hydrogels

A method for the quantification of biofilm formation on hydrogel protective coatings for optical sensors and cameras has been developed using fluorescein diacetate (FDA) hydrolysis. In conjunction with these measurements the release of the fouling resistant cationic surfactants benzalkonium chloride, tallowbenzyldimethylammonium chloride and dicocodimethylammonium chloride was measured, using high performance liquid chromatography (HPLC), to enable correlation to be made between release and biofilm resistance and thus determine the active lifetime of such coatings. Results indicate that the twin-chained material, dicocodimethylammonium chloride, produced superior biofouling resistance as, at the 12 week time point, little fouling was detected on this coating. The hydrogel containing the long-chained tallowbenzyldimethylammonium chloride (mainly C-16 and C-18 chains) was the next best fouling resistant material, withstanding biofilm formation for 9 weeks. This correlates with the fact that each of these materials had an extremely slow to zero release rate, due to their irreversible binding to the hydrogel over the experimental timescale. In comparison the shorter chained benzalkonium chloride (mainly C-12 and C-14). showed signs of biofilm formation at the 3 week time point

Risk factors for ischaemic colitis after surgery for abdominal aortic aneurysm: a systematic review and observational meta-analysis

BACKGROUND: Ischaemic colitis is an infrequent but serious complication following repair of abdominal aortic aneurysm (AAA), with high mortality rates. This systematic review set out to identify risk factors for the development of ischaemic colitis after AAA surgery. METHODS: A systematic search of the MEDLINE, EMBASE and CINAHL databases was performed. This search was limited to studies published in the English language after 1990. Abstracts were screened by two authors. Eligible studies were obtained as full text for further examination. Data was extracted by two authors, and any disputes were resolved via consensus. Extracted data was pooled using Mantel-Haenszel random effects models. Bias was assessed using two Cochrane-approved tools. Effect sizes are expressed as relative risk ratios alongside the 95 % confidence interval. Statistical significance was defined at the level of p < 0.05. RESULTS: From 388 studies identified in the initial search, 33 articles were included in the final synthesis and analysis. Risk factors were grouped into patient (female gender, disease severity) and operative factors (peri-procedural hypotension, operative modality). The risk of ischaemic colitis was significantly higher when undergoing emergency repair versus elective (risk ratio (RR) 7.36, 3.08 to 17.58, p < 0.001). Endovascular repair reduced the likelihood of ischaemic colitis (RR 0.22, 0.12 to 0.39, p < 0.001). DISCUSSION: The quality of published evidence on this subject is poor with many retrospective datasets and inconsistent reporting across studies. Despite this, emergency presentation and open repair should prompt close monitoring for the development of IC

Spatially Averaged Quantum Inequalities Do Not Exist in Four-Dimensional Spacetime

We construct a particular class of quantum states for a massless, minimally coupled free scalar field which are of the form of a superposition of the vacuum and multi-mode two-particle states. These states can exhibit local negative energy densities. Furthermore, they can produce an arbitrarily large amount of negative energy in a given region of space at a fixed time. This class of states thus provides an explicit counterexample to the existence of a spatially averaged quantum inequality in four-dimensional spacetime.Comment: 13 pages, 1 figure, minor corrections and added comment

A Non-Relativistic Weyl Anomaly

We examine the Weyl anomaly for a four-dimensional z=3 Lifshitz scalar coupled to Horava's theory of anisotropic gravity. We find a one-loop break-down of scale-invariance at second order in the gravitational background.Comment: LaTeX, 23 pages, no figures, JHEP style; v2: typos fixed to match the published versio

A systematic review of the intrapersonal correlates of motivational climate perceptions in sport and physical activity

Objectives: The purpose of this study was to systematically review and appraise the achievement goal literature (1990-2014) with a view to identifying the intra-individual correlates of motivational climate perceptions, and to identify research gaps and avenues in need for further development. Design: Systematic review. Method: Four databases were searched, leading to 104 published studies being sampled (121 independent samples) that met inclusion criteria. Correlates were grouped into 17 categories and qualitative analysis focussed on identifying the associations predicted by achievement goal theory. Effect sizes were calculated using the Hunter-Schmidt method for correcting sampling error. Results: A total population size of 34,156 (χ=316.3, σ=268.1) was sampled in the analysis, with the published mean ages ranging from 10.0 to 38.2 years (χ=16.5 years, σ=4.7). Perceptions of a task or mastery climate were consistently associated with a range of adaptive motivational outcomes including perceived competence, self-esteem, objective performance, intrinsic forms of motivational regulation, affective states, practice and competitive strategies and moral attitudes, and the experience of flow. Perceptions of an ego or performance climate were positively associated with extrinsic regulation and amotivation, negative affect, maladaptive strategy use, antisocial moral attitudes and perfectionism, but negatively associated to positive affect and feelings of autonomy and relatedness. Conclusions: After reviewing the sum total of research in this topic area, the authors appraise the options for future research to make meaningful progress in developing understanding of the social determination of motivation in sport and physical activity settings

Universal Features of Holographic Anomalies

We study the mechanism by which gravitational actions reproduce the trace anomalies of the holographically related conformal field theories. Two universal features emerge: a) the ratios of type B trace anomalies in any even dimension are independent of the gravitational action, being uniquely determined by the underlying algebraic structure b) the normalization of the type A and the overall normalization of the type B anomalies are given by action dependent expressions with the dimension dependence completely fixed.Comment: 17 pages, harvma

Probing CP Violation with the Deuteron Electric Dipole Moment

We present an analysis of the electric dipole moment (EDM) of the deuteron as induced by CP-violating operators of dimension 4, 5 and 6 including theta QCD, the EDMs and color EDMs of quarks, four-quark interactions and the Weinberg operator. We demonstrate that the precision goal of the EDM Collaboration's proposal to search for the deuteron EDM, (1-3)\times 10^{-27} e cm, will provide an improvement in sensitivity to these sources of one-two orders of magnitude relative to the existing bounds. We consider in detail the level to which CP-odd phases can be probed within the MSSM.Comment: 5 pages, 4 figures; precision estimates clarified, to appear in Phys. Rev.

Splitting the voter criticality

Recently some two-dimensional models with double symmetric absorbing states were shown to share the same critical behaviour that was called the voter universality class. We show, that for an absorbing-states Potts model with finite but further than nearest neighbour range of interactions the critical point is splitted into two critical points: one of the Ising type, and the other of the directed percolation universality class. Similar splitting takes place in the three-dimensional nearest-neighbour model.Comment: 4 pages, eps figures include