Disclination lines at homogeneous and heterogeneous colloids immersed in a chiral liquid crystal

In the present work we perform Monte Carlo simulations in the isothermal-isobaric ensemble to study defect topologies formed in a cholesteric liquid crystal due to the presence of a spherical colloidal particle. Topological defects arise because of the competition between anchoring at the colloidal surface and the local director. We consider homogeneous colloids with either local homeotropic or planar anchoring to validate our model by comparison with earlier lattice Boltzmann studies. Furthermore, we perform simulations of a colloid in a twisted nematic cell and discuss the difference between induced and intrinsic chirality on the formation of topological defects. We present a simple geometrical argument capable of describing the complex three-dimensional topology of disclination lines evolving near the surface of the colloid. The presence of a Janus colloid in a cholesteric host fluid reveals a rich variety of defect structures. Using the Frank free energy we analyze these defects quantitatively indicating a preferred orientation of the Janus colloid relative to the cholesteric helix.DFG, GRK 1524, Self-Assembled Soft-Matter Nanostructures at Interface

Coarse-grained treatment of the self-assembly of colloids suspended in a nematic host phase

The complex interplay of molecular scale effects, nonlinearities in the orientational field and long-range elastic forces makes liquid-crystal physics very challenging. A consistent way to extract information from the microscopic, molecular scale up to the meso- and macroscopic scale is still missing. Here, we develop a hybrid procedure that bridges this gap by combining extensive Monte Carlo (MC) simulations, a local Landau-de Gennes theory, classical density functional theory, and finite-size scaling theory. As a test case to demonstrate the power and validity of our novel approach we study the effective interaction among colloids with Boojum defect topology immersed in a nematic liquid crystal. In particular, at sufficiently small separations colloids attract each other if the angle between their center-of-mass distance vector and the far-field nematic director is about 30 degrees. Using the effective potential in coarse-grained two-dimensional MC simulations we show that self-assembled structures formed by the colloids are in excellent agreement with experimental data.DFG, GRK 1524, Self-Assembled Soft-Matter Nanostructures at Interface

Defect topologies in a nematic liquid crystal near a patchy colloid

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Chem. Phys. 136, 194703 (2012) and may be found at https://doi.org/10.1063/1.4717619.Using isothermal-isobaric Monte Carlo simulations we investigate defect topologies due to a spherical colloidal particle immersed in a nematic liquid crystal. Defects arise because of the competition between the preferential orientation at the colloid's surface and the far-field director ˆ0. Considering a chemically homogeneous colloid as a special case we observe the well-known surface and saturn ring defect topologies for weak and strong perpendicular anchoring, respectively; for homogeneous, strong parallel anchoring we find a boojum defect topology that has been seen experimentally [see P. Poulin and D. A. Weitz, Phys. Rev. E 57, 626 (1998)] but not in computer simulations. We also consider a heterogeneous, patchy colloid where the liquid-crystal molecules anchor either preferentially planar or perpendicular at the surface of the colloid. For a patchy colloid we observe a boojum ring defect topology in agreement with recent experimental studies [see M. Conradi, M. Ravnik, M. Bele, M. Zorko, S. Žumer, and I. Muševič, Soft Matter 5, 3905 (2009)]. We also observe two other novel defect topologies that have not been reported thus far neither experimentally nor theoretically.DFG, 65143814, GRK 1524: Self-Assembled Soft-Matter Nanostructures at Interface

The Pan African Thoracic Society Methods in Epidemiologic, Clinical and Operations Research Program: A story of success told through a history of publications

Objectives: Despite bearing a substantial burden of respiratory diseases, low- and middle-income countries in Africa contribute little to the research literature. Since 2007, the Pan African Thoracic Society’s Methods in Epidemiologic, Clinical, and Operations Research (PATS-MECOR) program has been working to strengthen capacity in lung health research in Africa. The aim of this study was to assess the research productivity of previous PATS-MECOR participants.Materials and Methods: A systematic review of publications attributed to past PATS-MECOR participants up until 2018 was carried out using a systematic search strategy based on their names on PubMed database.Results: A total of 210 participants drawn from 21 African countries attended PATS-MECOR between 2007 and 2016, of which more than three-quarters (76.7%) had ever published. Of the total 1673 included publications, 303 (12.7%) had multiple course attendees as coauthors. The median publication per published participant was 5 (IQR 2–13) articles. The percentages of the first author, second authors, or last authors publications were 371 (22.2%), 239 (14.3%), and 99 (5.9%), respectively. The top three journals published in were PLOS One 108 (6.6%), Lancet 80 (4.9%), and the International Journal of Tuberculosis and Lung Disease 52 (3.2%). The median citation of their publications was 11 (4–26). There was approximately a double-fold rise in the publication output of participants in their 1st year following attendance to PATS-MECOR compared to the year before the course (123, 68.0% vs. 58, 32.0%).Conclusion: The PATS-MECOR training program has been successful in research capacity building for African investigators as evidenced by a growing publication track record. There is a need to ensure sustainability and for increased collaboration and networking among the trained critical mass of researchers in the continent

Common genetic variants improve risk stratification after the atrial switch operation for transposition of the great arteries

Background: Clinical factors are used to estimate late complication risk in adults after atrial switch operation (AtrSO) for transposition of the great arteries (TGA), but heterogeneity in clinical course remains. We studied whether common genetic variants are associated with outcome and add value to a clinical risk score in TGA-AtrSO patients. Methods and results: This multicenter study followed 133 TGA-AtrSO patients (aged 28 [IQR 24–35] years) for 13 (IQR 9–16) years and examined the association of genome-wide single-nucleotide polymorphisms (SNPs) with a composite endpoint of symptomatic ventricular arrhythmia, heart failure hospitalization, ventricular assist device implantation, heart transplantation, or mortality. Thirty-two patients (24%) reached the endpoint. The genome-wide association study yielded one genome-wide significant (p 20%) risk. Stratified by the combined score, observed 5-year event-free survival was 100%, 79% and 31% for low, intermediate, and high-risk patients, respectively. Conclusions: Common genetic variants may explain some variation in the clinical course in TGA-AtrSO and improve risk stratification over clinical factors alone, especially in patients at intermediate clinical risk. These findings support the hypothesis that including genetic variants in risk assessment may be beneficial

The North Atlantic Ocean as habitat for Calanus finmarchicus : environmental factors and life history traits

This paper addresses relationships between the distribution and abundance of zooplankton and its habitat in the northern North Atlantic Ocean. Distributions of ten representative zooplankton taxa, from recent (2000-2009) Continuous Plankton Recorder data, are presented, along with basin-scale patterns of annual sea surface temperature and phytoplankton color. The distribution patterns represent the manifestation of very different physiological, life history and ecological interactions of each taxon with the North Atlantic habitat characteristics. The paper then focuses on a pan-Atlantic compilation of demographic and life history information for the planktonic copepod, Calanus finmarchicus, perhaps one of the most ecologically important and certainly the most studied zooplankton species in the North Atlantic. Abundance, dormancy, egg production and mortality in relation to temperature and phytoplankton biomass, using chlorophyll a as a proxy, are analyzed in the context of understanding factors involved in determining the distribution and abundance of C. finmarchicus across its range. Several themes emerge: (1) transport of C. finmarchicus is from the south to the north in the northeast Atlantic, but from the north to the south in the western North Atlantic, which has implications for understanding population responses to climate forcing on coastal shelves, , (2) recruitment to the youngest copepodite stages occurs during or just after the phytoplankton bloom in the east while it occurs after the bloom in many western sites, (3) while the deep basins in the Labrador Sea and Norwegian Sea are primary sources of C. finmarchicus production, the western North Atlantic marginal seas have an important role in sustaining high C. finmarchicus abundance on the western North Atlantic shelves, (4) differences in mean temperature and chlorophyll concentration between the western and eastern North Atlantic are reflected in regional differences in female body size and egg production responses, (5) differences in functional responses in egg production rate may reflect genetic differences between western and eastern populations, (6) dormancy duration is generally shorter in the deep waters adjacent to the lower latitude western North Atlantic shelves than in the east, and (7) differences in stage-specific mortality rates are related to bathymetry, temperature and potential predators, notably the abundance of congeners Calanus hyperboreus and C. glacialis, which likely feed on early life stages of C. finmarchicus. Two modeling approaches have previously been used to interpret the abundance and distribution of C. finmarchicus in relation to the North Atlantic habitat. A statistical approach based on ecological niche theory and a dynamical modeling approach, based on knowledge of spatial population dynamics and life history and implemented by recent developments in coupled physical-life cycle modeling. The strengths and weaknesses of each approach are discussed. A synthesis of the two modeling approaches to predict North Atlantic zooplankton species shifts, not only for C. finmarchicus, but also for other major taxa, is advocated. While the computational resource requirements and lack of species-specific life history information for physical-biological modeling hinder full application for many zooplankton taxa, use of the approach, where possible, to understand advective influences will provide insight for interpretation of statistical predictions from species distribution models

Biogeography of key mesozooplankton species in the North Atlantic and egg production of Calanus finmarchicus

-Here we present a new, pan-North-Atlantic compilation of data on key mesozooplankton species, including the most important copepod, Calanus finmarchicus. Distributional data of eight representative zooplankton taxa, from recent (2000–2009) Continuous Plankton Recorder data, are presented, along with basin-scale data of the phytoplankton colour index. Then we present a compilation of data on C. finmarchicus, including observations of abundance, demography, egg production and female size, with accompanying data on temperature and chlorophyll

If psychosis were cancer:a speculative comparison

Recently, health policy in the UK has begun to engage with the concept of ‘parity of esteem’ between physical and mental healthcare. This has led one recent initiative to improve service provision for first episode psychosis, which aims to bring it into line with some of the principles underpinning good practice in cancer care. In this paper, we consider some of the metaphorical consequences of likening psychosis to cancer. While we find the comparison unhelpful for clinical purposes, we argue that it can be a helpful lens through which to examine service provision for psychosis in young people. Through this lens, specialist community-based services would appear to compare reasonably well. Inpatient care for young people with psychosis, on the other hand, suffers very badly by comparison with inpatient facilities for teenage cancer care. We note some of the many positive features of inpatient cancer care for young adults, and—drawing upon previous research on inpatient psychiatric care—observe that many of these are usually absent from mental health facilities. We conclude that this metaphor may be a helpful rhetorical device for communicating the lack of ‘parity of esteem’ between mental and physical healthcare. This inequity must be made visible in health policy, in commissioning, and in service provision