Polar Smectic Films

We report on a new experimental procedure for forming and studying polar smectic liquid crystal films. A free standing smectic film is put in contact with a liquid drop, so that the film has one liquid crystal/liquid interface and one liquid crystal/air interface. This polar environment results in changes in the textures observed in the film, including a boojum texture and a previously unobserved spiral texture in which the winding direction of the spiral reverses at a finite radius from its center. Some aspects of these textures are explained by the presence of a Ksb term in the bulk elastic free energy density that favors a combination of splay and bend deformations.Comment: 4 pages, REVTeX, 3 figures, submitted to PR

Front propagation into unstable and metastable states in Smectic C* liquid crystals: linear and nonlinear marginal stability analysis

We discuss the front propagation in ferroelectric chiral smectics (SmC*) subjected to electric and magnetic fields applied parallel to smectic layers. The reversal of the electric field induces the motion of domain walls or fronts that propagate into either an unstable or a metastable state. In both regimes, the front velocity is calculated exactly. Depending on the field, the speed of a front propagating into the unstable state is given either by the so-called linear marginal stability velocity or by the nonlinear marginal stability expression. The cross-over between these two regimes can be tuned by a magnetic field. The influence of initial conditions on the velocity selection problem can also be studied in such experiments. SmC$^*$ therefore offers a unique opportunity to study different aspects of front propagation in an experimental system

The clinical effectiveness of transurethral incision of the prostate : a systematic review of randomised controlled trials

The original publication is available at www.springerlink.com.Peer reviewedPostprin

Uric acid levels and outcome from coronary artery bypass grafting

ObjectiveElevated uric acid levels have been associated with an adverse cardiovascular outcome in several settings. Their utility in patients undergoing surgical revascularization has not, however, been assessed. We hypothesized that serum uric acid levels would predict the outcome of patients undergoing coronary artery bypass grafting.MethodsThe study cohort consisted of 1140 consecutive patients undergoing nonemergency coronary artery bypass grafting. Clinical details were obtained prospectively, and serum uric acid was measured a median of 1 day before surgery. The primary end point was all-cause mortality.ResultsDuring a median of 4.5 years, 126 patients (11%) died. Mean (± standard deviation) uric acid levels were 390 ± 131 μmol/L in patients who died versus 353 ± 86 μmol/L among survivors (hazard ratio 1.48 per 100 μmol/L; 95% confidence interval, 1.25–1.74; P < .001). The excess risk associated with an elevated uric acid was particularly evident among patients in the upper quartile (≥410 μmol/L; hazard ratio vs all other quartiles combined 2.18; 95% confidence interval, 1.53–3.11; P < .001). After adjusting for other potential prognostic variables, including the European System for Cardiac Operative Risk Evaluation, uric acid remained predictive of outcome.ConclusionIncreasing levels of uric acid are associated with poorer survival after coronary artery bypass grafting. Their prognostic utility is independent of other recognized risk factors, including the European System for Cardiac Operative Risk Evaluation

Observational and Dynamical Characterization of Main-Belt Comet P/2010 R2 (La Sagra)

We present observations of comet-like main-belt object P/2010 R2 (La Sagra) obtained by Pan-STARRS 1 and the Faulkes Telescope-North on Haleakala in Hawaii, the University of Hawaii 2.2 m, Gemini-North, and Keck I telescopes on Mauna Kea, the Danish 1.54 m telescope at La Silla, and the Isaac Newton Telescope on La Palma. An antisolar dust tail is observed from August 2010 through February 2011, while a dust trail aligned with the object's orbit plane is also observed from December 2010 through August 2011. Assuming typical phase darkening behavior, P/La Sagra is seen to increase in brightness by >1 mag between August 2010 and December 2010, suggesting that dust production is ongoing over this period. These results strongly suggest that the observed activity is cometary in nature (i.e., driven by the sublimation of volatile material), and that P/La Sagra is therefore the most recent main-belt comet to be discovered. We find an approximate absolute magnitude for the nucleus of H_R=17.9+/-0.2 mag, corresponding to a nucleus radius of ~0.7 km, assuming an albedo of p=0.05. Using optical spectroscopy, we find no evidence of sublimation products (i.e., gas emission), finding an upper limit CN production rate of Q_CN<6x10^23 mol/s, from which we infer an H2O production rate of Q_H2O<10^26 mol/s. Numerical simulations indicate that P/La Sagra is dynamically stable for >100 Myr, suggesting that it is likely native to its current location and that its composition is likely representative of other objects in the same region of the main belt, though the relatively close proximity of the 13:6 mean-motion resonance with Jupiter and the (3,-2,-1) three-body mean-motion resonance with Jupiter and Saturn mean that dynamical instability on larger timescales cannot be ruled out.Comment: 23 pages, 13 figures, accepted for publication in A

Typhoid Fever and Invasive Nontyphoid Salmonellosis, Malawi and South Africa

To determine the prevalence of invasive nontyphoid salmonellosis and typhoid fever in Malawi and South Africa, we compared case frequency and patient age distribution. Invasive nontyphoid salmonellosis showed a clear bimodal age distribution; the infection developed in women at a younger age than in men. Case frequency for typhoid fever was lower than for salmonellosis

Relationship between Antibody Susceptibility and Lipopolysaccharide O-Antigen Characteristics of Invasive and Gastrointestinal Nontyphoidal Salmonellae Isolates from Kenya

Background: Nontyphoidal Salmonellae (NTS) cause a large burden of invasive and gastrointestinal disease among young children in sub-Saharan Africa. No vaccine is currently available. Previous reports indicate the importance of the O-antigen of Salmonella lipopolysaccharide for virulence and resistance to antibody-mediated killing. We hypothesised that isolates with more O-antigen have increased resistance to antibody-mediated killing and are more likely to be invasive than gastrointestinal. Methodology/Principal findings: We studied 192 NTS isolates (114 Typhimurium, 78 Enteritidis) from blood and stools, mostly from paediatric admissions in Kenya 2000-2011. Isolates were tested for susceptibility to antibody-mediated killing, using whole adult serum. O-antigen structural characteristics, including O-acetylation and glucosylation, were investigated. Overall, isolates were susceptible to antibody-mediated killing, but S. Enteritidis were less susceptible and expressed more O-antigen than Typhimurium (p\u3c0.0001 for both comparisons). For S. Typhimurium, but not Enteritidis, O-antigen expression correlated with reduced sensitivity to killing (r = 0.29, 95% CI = 0.10-0.45, p = 0.002). Both serovars expressed O-antigen populations ranging 21-33 kDa average molecular weight. O-antigen from most Typhimurium were O-acetylated on rhamnose and abequose residues, while Enteritidis O-antigen had low or no O-acetylation. Both Typhimurium and Enteritidis O-antigen were approximately 20%-50% glucosylated. Amount of S. Typhimurium O-antigen and O-antigen glucosylation level were inversely related. There was no clear association between clinical presentation and antibody susceptibility, O-antigen level or other O-antigen features. Conclusion/Significance: Kenyan S. Typhimurium and Enteritidis clinical isolates are susceptible to antibody-mediated killing, with degree of susceptibility varying with level of O-antigen for S. Typhimurium. This supports the development of an antibody-inducing vaccine against NTS for Africa. No clear differences were found in the phenotype of isolates from blood and stool, suggesting that the same isolates can cause invasive disease and gastroenteritis. Genome studies are required to understand whether invasive and gastrointestinal isolates differ at the genotypic level

Male synthetic sling versus artificial urinary sphincter trial for men with urodynamic stress incontinence after prostate surgery (MASTER): Study protocol for a randomised controlled trial

© 2018 The Author(s). Background: Stress urinary incontinence (SUI) is a frequent adverse effect for men undergoing prostate surgery. A large proportion (around 8% after radical prostatectomy and 2% after transurethral resection of prostate (TURP)) are left with severe disabling incontinence which adversely effects their quality of life and many are reliant on containment measures such as pads (27% and 6% respectively). Surgery is currently the only option for active management of the problem. The overwhelming majority of surgeries for persistent bothersome SUI involve artificial urinary sphincter (AUS) insertion. However, this is expensive, and necessitates manipulation of a pump to enable voiding. More recently, an alternative to AUS has been developed - a synthetic sling for men which elevates the urethra, thus treating SUI. This is thought, by some, to be less invasive, more acceptable and less expensive than AUS but clear evidence for this is lacking. The MASTER trial aims to determine whether the male synthetic sling is non-inferior to implantation of the AUS for men who have SUI after prostate surgery (for cancer or benign disease), judged primarily on clinical effectiveness but also considering relative harms and cost-effectiveness. Methods/design: Men with urodynamic stress incontinence (USI) after prostate surgery, for whom surgery is judged appropriate, are the target population. We aim to recruit men from secondary care urological centres in the UK NHS who carry out surgery for post-prostatectomy incontinence. Outcomes will be assessed by participant-completed questionnaires and 3-day urinary bladder diaries at baseline, 6, 12 and 24 months. The 24-h urinary pad test will be used at baseline as an objective assessment of urine loss. Clinical data will be completed at the time of surgery to provide details of the operative procedures, complications and resource use in hospital. At 12 months, men will also have a clinical review to evaluate the results of surgery (including another 24-h pad test) and to identify problems or need for further treatment. Discussion: A robust examination of the comparative effectiveness of the male synthetic sling will provide high-quality evidence to determine whether or not it should be adopted widely in the NHS

The Main Belt Comets and ice in the Solar System

We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies

Seismic reflection images of a near-axis melt sill within the lower crust at the Juan de Fuca ridge

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 460 (2009): 89-93, doi:10.1038/nature08095.The oceanic crust extends over two thirds of the Earth’s solid surface and is generated along mid-ocean ridges from melts derived from the upwelling mantle. The upper and mid crust are constructed by dyking and seafloor eruptions originating from magma accumulated in mid-crustal lenses at the spreading axis, but the style of accretion of the lower oceanic crust is actively debated. Models based on geological and petrological data from ophiolites propose that the lower oceanic crust is accreted from melt sills intruded at multiple levels between the Moho transition zone (MTZ) and the mid-crustal lens, consistent with geophysical studies that suggest the presence of melt within the lower crust. However, seismic images of molten sills within the lower crust have been elusive. To date only seismic reflections from mid-crustal melt lenses and sills within the MTZ have been described, suggesting that melt is efficiently transported through the lower crust. Here we report deep crustal seismic reflections off the southern Juan de Fuca Ridge that we interpret as originating from a molten sill presently accreting the lower oceanic crust. The sill sits 5-6 km beneath the seafloor and 850-900 m above the MTZ, and it is located 1.4-3.2 km off thespreading axis. Our results provide evidence for the existence of low permeability barriers to melt migration within the lower section of modern oceanic crust forming at intermediate-to-fast spreading rates, as inferred from ophiolite studies.This research was supported by grants form the US NSF