98 research outputs found

    Theory of Chiral Modulations and Fluctuations in Smectic-A Liquid Crystals Under an Electric Field

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    Chiral liquid crystals often exhibit periodic modulations in the molecular director; in particular, thin films of the smectic-C* phase show a chiral striped texture. Here, we investigate whether similar chiral modulations can occur in the induced molecular tilt of the smectic-A phase under an applied electric field. Using both continuum elastic theory and lattice simulations, we find that the state of uniform induced tilt can become unstable when the system approaches the smectic-A--smectic-C* transition, or when a high electric field is applied. Beyond that instability point, the system develops chiral stripes in the tilt, which induce corresponding ripples in the smectic layers. The modulation persists up to an upper critical electric field and then disappears. Furthermore, even in the uniform state, the system shows chiral fluctuations, including both incipient chiral stripes and localized chiral vortices. We compare these predictions with observed chiral modulations and fluctuations in smectic-A liquid crystals.Comment: 11 pages, including 9 postscript figures, uses REVTeX 3.0 and epsf.st

    Singaporean caregivers’ experiences of placing a relative into long term care

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    Caregivers experience many difficulties and challenges with the process of providing care particularly at times of transition, such as when the care recipient moves into a nursing home. This qualitative study aims to understand caregiver experiences of this important process. Methods: Twelve interviews were conducted with caregivers with an older relative in a nursing home in Singapore. The resulting data was analysed through thematic analysis. Results: Five themes were identified: Filial and cultural expectations shape caregivers’ experience of pre-placement decisions and post-placement; View of the placement decision; Continued impact of caring; Engagement with the institution and Maintaining the relationship. Conclusions: Caregivers were found to place significant emphasis on cultural values, specifically on filial piety. This impacted their caregiving role prior to placement, when making the decision to place their relative into a nursing home and in their continued involvement after placement. Despite the changing role, the placement experience was fraught with persisting difficulties involving maintaining the relationship with the resident and developing a new relationship with the nursing home

    Cancer diagnostic profile in children with structural birth defects: An assessment in 15,000 childhood cancer cases

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    Background: Birth defects are established risk factors for childhood cancer. Nonetheless, cancer epidemiology in children with birth defects is not well characterized. Methods: Using data from population-based registries in 4 US states, this study compared children with cancer but no birth defects (n = 13,111) with children with cancer and 1 or more nonsyndromic birth defects (n = 1616). The objective was to evaluate cancer diagnostic characteristics, including tumor type, age at diagnosis, and stage at diagnosis. Results: Compared with the general population of children with cancer, children with birth defects were diagnosed with more embryonal tumors (26.6% vs 18.7%; q < 0.001), including neuroblastoma (12.5% vs 8.2%; q < 0.001) and hepatoblastoma (5.0% vs 1.3%; q < 0.001), but fewer hematologic malignancies, including acute lymphoblastic leukemia (12.4% vs 24.4%; q < 0.001). In age-stratified analyses, differences in tumor type were evident among children younger than 1 year and children 1 to 4 years old, but they were attenuated among children 5 years of age or older. The age at diagnosis was younger in children with birth defects for most cancers, including leukemia, lymphoma, astrocytoma, medulloblastoma, ependymoma, embryonal tumors, and germ cell tumors (all q < 0.05). Conclusions: The results indicate possible etiologic heterogeneity in children with birth defects, have implications for future surveillance efforts, and raise the possibility of differential cancer ascertainment in children with birth defects. Lay Summary: Scientific studies suggest that children with birth defects are at increased risk for cancer. However, these studies have not been able to determine whether important tumor characteristics, such as the type of tumor diagnosed, the age at which the tumor is diagnosed, and the degree to which the tumor has spread at the time of diagnosis, are different for children with birth defects and children without birth defects. This study attempts to answer these important questions. By doing so, it may help scientists and physicians to understand the causes of cancer in children with birth defects and diagnose cancer at earlier stages when it is more treatable

    Absorptive capacity and market orientation in public service provision

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    This is an Accepted Manuscript of an article published by Taylor & Francis Group in Journal of Strategic Marketing on 05.04.2012, available online at: http://www.tandfonline.com/10.1080/0965254X.2011.643915The application of market orientation to public organisations does not adequately account for the unique features of this context. Drawing on absorptive capacity literature, this is the first study to examine the role of the organisation's learning environment on the market orientation-performance interface for two opposing public management contexts. The research involved a national survey questionnaire to 1060 internal and external public leisure service providers in England. Empirical testing through structural equation modelling revealed that not all dimensions of market orientation are universally positive and marketing scholars should seek to examine and understand market orientation in the context of the organisation and its learning mechanisms, as absorptive capacity has clear and different moderation effects under different management contexts. © 2012 Copyright Taylor and Francis Group, LLC

    Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

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    We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

    Representational predicaments for employees: Their impact on perceptions of supervisors\u27 individualized consideration and on employee job satisfaction

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    A representational predicament for a subordinate vis-à-vis his or her immediate superior involves perceptual incongruence with the superior about the subordinate\u27s work or work context, with unfavourable implications for the employee. An instrument to measure the incidence of two types of representational predicament, being neglected and negative slanting, was developed and then validated through an initial survey of 327 employees. A subsequent substantive survey with a fresh sample of 330 employees largely supported a conceptual model linking being neglected and negative slanting to perceptions of low individualized consideration by superiors and to low overall job satisfaction. The respondents in both surveys were all Hong Kong Chinese. Two case examples drawn from qualitative interviews illustrate and support the conceptual model. Based on the research findings, we recommend some practical exercises to use in training interventions with leaders and subordinates. © 2013 Copyright Taylor and Francis Group, LLC

    5-Lipoxygenase Metabolic Contributions to NSAID-Induced Organ Toxicity

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    Pulmonary Function and Blood DNA Methylation A Multiancestry Epigenome-Wide Association Meta-analysis

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    Rationale: Methylation integrates factors present at birth and modifiable across the lifespan that can influence pulmonary function. Studies are limited in scope and replication. Objectives: To conduct large-scale epigenome-wide meta-analyses of blood DNA methylation and pulmonary function. Methods: Twelve cohorts analyzed associations of methylation at cytosine-phosphate-guanine probes (CpGs), using Illumina 450K or EPIC/850K arrays, with FEV1, FVC, and FEV1/FVC. We performed multiancestry epigenome-wide meta-analyses (total of 17,503 individuals; 14,761 European, 2,549 African, and 193 Hispanic/Latino ancestries) and interpreted results using integrative epigenomics. Measurements and Main Results: We identified 1,267 CpGs (1,042 genes) differentially methylated (false discovery rate,,0.025) in relation to FEV1, FVC, or FEV1/FVC, including 1,240 novel and 73 also related to chronic obstructive pulmonary disease (1,787 cases). We found 294 CpGs unique to European or African ancestry and 395 CpGs unique to never or ever smokers. The majority of significant CpGs correlated with nearby gene expression in blood. Findings were enriched in key regulatory elements for gene function, including accessible chromatin elements, in both blood and lung. Sixty-nine implicated genes are targets of investigational or approved drugs. One example novel gene highlighted by integrative epigenomic and druggable target analysis is TNFRSF4. Mendelian randomization and colocalization analyses suggest that epigenome-wide association study signals capture causal regulatory genomic loci. Conclusions: We identified numerous novel loci differentially methylated in relation to pulmonary function; few were detected in large genome-wide association studies. Integrative analyses highlight functional relevance and potential therapeutic targets. This comprehensive discovery of potentially modifiable, novel lung function loci expands knowledge gained from genetic studies, providing insights into lung pathogenesis

    Variants associated withHHIP expression have sex-differential effects on lung function

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    Background: Lung function is highly heritable and differs between the sexes throughout life. However, little is known about sex-differential genetic effects on lung function. We aimed to conduct the first genome-wide genotype-by-sex interaction study on lung function to identify genetic effects that differ between males and females. Methods: We tested for interactions between 7,745,864 variants and sex on spirometry-based measures of lung function in UK Biobank (N=303,612), and sought replication in 75,696 independent individuals from the SpiroMeta consortium. Results: Five independent single-nucleotide polymorphisms (SNPs) showed genome-wide significant (P</p
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