Electrophoretic Properties of Highly Charged Colloids: A Hybrid MD/LB Simulation Study

Using computer simulations, the electrophoretic motion of a positively charged colloid (macroion) in an electrolyte solution is studied in the framework of the primitive model. Hydrodynamic interactions are fully taken into account by applying a hybrid simulation scheme, where the charged ions (i.e. macroion and electrolyte), propagated via molecular dynamics (MD), are coupled to a Lattice Boltzmann (LB) fluid. In a recent experiment it was shown that, for multivalent salt ions, the mobility $\mu$ initially increases with charge density $\sigma$, reaches a maximum and then decreases with further increase of $\sigma$. The aim of the present work is to elucidate the behaviour of $\mu$ at high values of $\sigma$. Even for the case of monovalent microions, we find a decrease of $\mu$ with $\sigma$. A dynamic Stern layer is defined that includes all the counterions that move with the macroion while subject to an external electrical field. The number of counterions in the Stern layer, $q_0$, is a crucial parameter for the behavior of $\mu$ at high values of $\sigma$. In this case, the mobility $\mu$ depends primarily on the ratio $q_0/Q$ (with $Q$ the valency of the macroion). The previous contention that the increase in the distortion of the electric double layer (EDL) with increasing $\sigma$ leads to the lowering of $\mu$ does not hold for high $\sigma$. In fact, we show that the deformation of the EDL decreases with increase of $\sigma$. The role of hydrodynamic interactions is inferred from direct comparisons to Langevin simulations where the coupling to the LB fluid is switched off. Moreover, systems with divalent counterions are considered. In this case, at high values of $\sigma$ the phenomenon of charge inversion is found.Comment: accepted in J. Chem Phys., 10 pages, 9 figure

Decline and Fall of the Standard Model?

Motivations for physics beyond the Standard Model are reviewed, with particular emphasis on supersymmetry at the TeV scale. Constraints on the minimal supersymmetric extension of the Standard Model with universal soft supersymmetry-breaking terms (CMSSM) are discussed. These are also combined with the supersymmetric interpretation of the anomalous magnetic moment of the muon. The prospects for observing supersymmetry at accelerators are reviewed using benchmark scenarios to focus the discussion. Prospects for other experiments are discussed, including the detection of cold dark matter, mu -> e gamma and related processes, as well as proton decay.Comment: Invited talk at 20th International Symposium on Lepton and Photon Interactions at High Energies, Rome, 2001, 16 pages LaTeX, 13 eps figures, uses special .cls file (included

Kepler Observations of Very Low-Mass Stars

Observations of very low-mass stars with Kepler represent an excellent opportunity to search for planetary transits and to characterize optical photometric variability at the cool end of the stellar mass distribution. In this paper, we present low-resolution red optical spectra that allow us to identify 18 very low-mass stars that have Kepler light curves available in the public archive. Spectral types of these targets are found to lie in the range dM4.5--dM8.5, implying spectrophotometric distances from 17 pc to 80 pc. Limits to the presence of transiting planets are placed from modelling of the Kepler light curves. We find that the size of the planets detectable by Kepler around these small stars typically lie in the range 1 to 5 Earth radii within the habitable regions (P$\le$10 days). We identify one candidate transit with a period of 1.26 days that resembles the signal produced by a planet slightly smaller than the Moon. However, our pixel by pixel analysis of the Kepler data shows that the signal most likely arises from a background contaminating eclipsing binary. For 11 of these objects reliable photometric periods shorter than 7 days are derived, and are interpreted as rotational modulation of magnetic cool spots. For 3 objects we find possible photometric periods longer than 50 days that require confirmation. H$_\alpha$ emission measurements and flare rates are used as a proxies for chromospheric activity and transversal velocities are used as an indicator of dynamical ages. These data allow us to discuss the relationship between magnetic activity and detectability of planetary transits around very low-mass stars. We show that Super-Earth planets with sizes around 2 Earth radii are detectable with Kepler around about two thirds of the stars in our sample, independently from their level of chromospheric activity.Comment: Accepted for publication in Astronomy and Astrophysic

Incidence and prevalence of celiac disease and dermatitis herpetiformis in the UK over two decades: population-based study

OBJECTIVES: Few studies have quantified the incidence and prevalence of celiac disease (CD) and dermatitis herpetiformis (DH) nationally and regionally by time and age groups. Understanding this epidemiology is crucial for hypothesizing about causes and quantifying the burden of disease. METHODS: Patients with CD or DH were identified in the Clinical Practice Research Datalink between 1990 and 2011. Incidence rates and prevalence were calculated by age, sex, year, and region of residence. Incidence rate ratios (IRR) adjusted for age, sex, and region were calculated with Poisson regression. RESULTS: A total of 9,087 incident cases of CD and 809 incident cases of DH were identified. Between 1990 and 2011, the incidence rate of CD increased from 5.2 per 100,000 (95% confidence interval (CI), 3.8-6.8) to 19.1 per 100,000 person-years (95% CI, 17.8-20.5; IRR, 3.6; 95% CI, 2.7-4.8). The incidence of DH decreased over the same time period from 1.8 per 100,000 to 0.8 per 100,000 person-years (average annual IRR, 0.96; 95% CI, 0.94-0.97). The absolute incidence of CD per 100,000 person-years ranged from 22.3 in Northern Ireland to 10 in London. There were large regional variations in prevalence for CD but not DH. CONCLUSIONS: We found a fourfold increase in the incidence of CD in the United Kingdom over 22 years, with large regional variations in prevalence. This contrasted with a 4% annual decrease in the incidence of DH, with minimal regional variations in prevalence. These contrasts could reflect differences in diagnosis between CD (serological diagnosis and case finding) and DH (symptomatic presentation) or the possibility that diagnosing and treating CD prevents the development of DH

Assessment of a non-invasive haemoglobin sensor NBM 200 among pregnant women in rural India

Objective: This study aimed to assess a non-invasive haemoglobin sensor NBM 200 in pregnant women in a rural Indian setting. Methods: The study population consisted of women between 3 to 5 months of pregnancy, from 33 villages in Tuljapur and Lohara blocks of Osmanabad district, Maharashtra between April 2014 and June 2015. Haemoglobin (Hb) measurements obtained from the non-invasive sensor NBM 200 were compared with measurements obtained from an automated haematology analyser Sysmex XP-100, using the Bland Altman method and Spearman’s Rank correlation coefficient. Interclass correlation coefficient (ICC), sensitivity and specificity values were used to assess the anaemia diagnostic accuracy of NBM 200 against the gold standard (Sysmex XP-100). Results: Data were obtained from 269 pregnant women (median age: 21 years, Interquartile range: 19 to 23 years). Haemoglobin levels estimated by the Sysmex XP-100 analyser ranged from 5.5 g/dL to 14.1 g/dL (mean: 10.0 g/dL, standard deviation (SD): 1.28), while measurements obtained from NBM 200 ranged from 9.5 g/dL to 14.6 g/dL (mean: 11.9 g/dL, SD: 1.43). The Spearman’s test found a significant, moderately positive correlation between the two methods (rs= 0.4, p<0.001), ICC was 0.22, and the Bland-Altman analysis showed a mean difference of -1.8 g/dL (95% Confidence interval (CI): -2.06 to -1.71) indicating a systematic overestimation of Hb using the NBM 200. The NBM 200 showed low sensitivity (33.7%; 95% CI: 27.3 - 40.5) but high specificity (91.8%; 95% CI: 81.9 - 97.3) for the diagnosis of anaemia. Conclusion: Haemoglobin measurements obtained from the NBM 200 were higher with consequent underestimation of anaemia as compared with the gold standard reference method. This limits the use of the NBM 200 as an anaemia diagnostic test in our study population consisting of women during pregnancy

Which patients are assessed by lung cancer nurse specialists? A national lung cancer audit study of over 128,000 patients across England

Background: Lung cancer nurse specialists (LCNS) are integral to the multidisciplinary clinical team, providing personalised physical and psycho-social interventions, and care management for people with lung cancer. The National Institute of Health and Care Excellence (NICE) recommend that all patients have access to a LCNS. We conducted a national study assessing whether there is variation in access to and timing of LCNS assessment. Methods: The National Cancer Action Team’s LCNS workforce census in England was linked with patient and hospital Trust data from the English National Lung Cancer Audit. Multivariate logistic regression was used to assess features associated with LCNS assessment. Results: 128,124 lung cancer patients were seen from 2007 to 2011. LCNS assessment confirmation was ‘yes’ in 62%, ‘no’ in 6% and ‘missing’ in 32%. Where (in clinic versus ward) and when (before versus after diagnosis) patients were assessed by a LCNS also varied. Older patients with poor performance status, early cancer stage, and comorbidities were less likely to be assessed; there was no difference with sex or socioeconomic group. Patients receiving any anti-cancer treatment were more likely to be assessed. Assessment was lower in Trusts with high annual patient numbers (odds ratio = 0.58, 95% confidence interval 0.37–0.91) and where LCNS caseload &gt; 250 (0.69, 0.41–1.16, although not statistically significant), but increased where workload was conducted mostly by band 8 nurses (2.22, 1.22–4.02). Conclusion: LCNS assessment varied by patient and Trust features, which may indicate unmet need for some patients. The current workforce needs to expand as well as retain experienced LCNSs

Risk factors for maternal anaemia and low birth weight in pregnant women living in rural India: a prospective cohort study

Objective: The aim of this prospective study was to estimate the prevalence and risk factors for maternal anaemia and low birth weight in pregnant women living in Maharashtra state, India. Study design: Prospective study Methods: Women between 3 to 5 months of pregnancy were recruited from 34 villages based in Maharashtra state. Baseline data collection, anthropometric measurements and blood investigations were performed. Participants were followed-up to record birth weight. Results: In total, 303 women were eligible, and 287 (95%) provided data. 77% were anaemic defined as haemoglobin less than 11.0 g/dL at the time of recruitment, with a mean corpuscular volume (MCV) of 80.5 fl/cell, (standard deviation: 7.22, range: 53.4 to 93.8). Increased risk of anaemia was seen in women with consanguineous marriages (odds ratio (OR): 2.41, 95% Confidence Interval (CI): 1.16 to 5.01, p=0.01) after adjustment for potential confounding factors. Post-delivery data from full-term singleton live births demonstrated a 7% prevalence of low birth weight. Consanguineous marriage was a major risk for low birth weight (OR: 4.10, 95% CI: 1.25 to 13.41, p=0.02). The presence of maternal anaemia during 3 to 5 months of pregnancy was associated with lower risk of low birth weight (unadjusted OR: 0.34, 95% CI: 0.13 to 0.92, p= 0.03). Conclusion: About 30% of our study participants were in a consanguineous marriage, which was identified as a potentially avoidable risk factor for both anaemia and low birth weight

Spectroscopic rotational velocities of brown dwarfs

We have obtained projected rotation velocities (vsini) of a sample of 19 ultracool dwarfs with spectral types in the interval M6.5-T8 using high-resolution, near-infrared spectra obtained with NIRSPEC and the Keck II telescope. Among our targets there are two young brown dwarfs, two likely field stars, and fifteen likely brown dwarfs (30-72 Mjup) of the solar neighborhood. Our results indicate that the T-type dwarfs are fast rotators in marked contrast to M-type stars. We have derived vsini velocities between <15 and 40 km/s for them, and have found no clear evidence for T dwarfs rotating strongly faster than L dwarfs. However, there is a hint for an increasing lower envelope on moving from mid-M to the L spectral types in the vsini-spectral type diagram that was previously reported in the literature; our vsini results extend it to even cooler types. Assuming that field brown dwarfs have a size of 0.08-0.1 Rsol, we can place an upper limit of 12.5 h on the equatorial rotation period of T-type brown dwarfs. In addition, we have compared our vsini measurements to spectroscopic rotational velocities of very young brown dwarfs of similar mass available in the literature. The comparison, although model-dependent, suggests that brown dwarfs lose some angular momentum during their contraction; however, their spin down time seems to be significantly longer than that of solar-type to early-M stars.Comment: Accepted for publication in ApJ (revised version