Optical properties of suspensions of gold half-shells

Suspensions of mesoscale gold half-shells of controlled size were produced by microsphere-templated vapour deposition and their optical properties were studied. The transmission spectra of the particles exhibited an extinction peak that could be tuned from 530 to over 2000 nm by variation of the diameter of the template used. In this respect the optical properties of these reduced-symmetry particles are similar to those of full nanoshells, however they may be more convenient to prepare. © 2007 Elsevier B.V. All rights reserved

Putting context into organizational intervention design:Using tailored questionnaires to measure initiatives for worker well-being

Realistic evaluation emphasizes the importance of exploring the mechanisms through which organizational interventions are effected. A well-known mechanism in organizational interventions is the screening process. Standardized questionnaires, in popular use, neither consider individuals’ appraisals of working conditions nor the specific context of the workplace. Screening with items tailored to intervention contexts may overcome the limitations of standardized questionnaires. In the present study, we evaluate an approach to develop a tailored questionnaire to measure employees’ appraisals of their specific working conditions. First, we interviewed 56 employees and 17 managers and, later, developed tailored items focused on the working conditions in a postal service. In follow-up interviews, we explore participants’ experiences with the tailored questionnaire, including the development of initiatives, compared to their previous experiences with the company´s annual attitude survey that used standardized scales. Results indicated that participants felt the tailored questionnaire highlighted issues that had previously been ignored, that initiatives were easier to develop due to its specificity, and that the feedback strategy was useful in prioritizing questionnaires. Overall, it can be concluded that tailored questionnaires may be appropriate for use in organizational intervention research and more broadly that evaluations of organizational interventions need to be contextually grounded

Measurement of the vertical non-uniformity of the plasma sheath in a complex plasma

Employing an attenuated oscillation method, the anisotropic interaction force between two vertically aligned dust particles located in the sheath of a complex plasma was measured experimentally based on a linear approximation to the interaction force. Experimental data shows that although both particles experience a repulsive interaction force, the upper particle experiences a stronger magnitude force than does the lower. This result can be explained by the ion wakefield since the lower particle resides within the ion wakefield generated by the streaming ions passing through the sheath and around the upper particle

Direct and indirect effects of rotavirus vaccination: Comparing predictions from transmission dynamic models

Early observations from countries that have introduced rotavirus vaccination suggest that there may be indirect protection for unvaccinated individuals, but it is unclear whether these benefits will extend to the long term. Transmission dynamic models have attempted to quantify the indirect protection that might be expected from rotavirus vaccination in developed countries, but results have varied. To better understand the magnitude and sources of variability in model projections, we undertook a comparative analysis of transmission dynamic models for rotavirus. We fit five models to reported rotavirus gastroenteritis (RVGE) data from England and Wales, and evaluated outcomes for short- and long-term vaccination effects. All of our models reproduced the important features of rotavirus epidemics in England and Wales. Models predicted that during the initial year after vaccine introduction, incidence of severe RVGE would be reduced 1.8-2.9 times more than expected from the direct effects of the vaccine alone (28-50% at 90% coverage), but over a 5-year period following vaccine introduction severe RVGE would be reduced only by 1.1-1.7 times more than expected from the direct effects (54-90% at 90% coverage). Projections for the long-term reduction of severe RVGE ranged from a 55% reduction at full coverage to elimination with at least 80% coverage. Our models predicted short-term reductions in the incidence of RVGE that exceeded estimates of the direct effects, consistent with observations from the United States and other countries. Some of the models predicted that the short-term indirect benefits may be offset by a partial shifting of the burden of RVGE to older unvaccinated individuals. Nonetheless, even when such a shift occurs, the overall reduction in severe RVGE is considerable. Discrepancies among model predictions reflect uncertainties about age variation in the risk and reporting of RVGE, and the duration of natural and vaccine-induced immunity, highlighting important questions for future research

Is There a Causal Association between Genotoxicity and the Imposex Effect?

There is a growing body of evidence that indicates common environmental pollutants are capable of disrupting reproductive and developmental processes by interfering with the actions of endogenous hormones. Many reports of endocrine disruption describe changes in the normal development of organs and tissues that are consistent with genetic damage, and recent studies confirm that many chemicals classified to have hormone-modulating effects also possess carcinogenic and mutagenic potential. To date, however, there have been no conclusive examples linking genetic damage with perturbation of endocrine function and adverse effects in vivo. Here, we provide the first evidence of DNA damage associated with the development of imposex (the masculinization of female gastropods considered to be the result of alterations to endocrine-mediated pathways) in the dog-whelk Nucella lapillus. Animals (n = 257) that displayed various stages of tributyltin (TBT)-induced imposex were collected from sites in southwest England, and their imposex status was determined by physical examination. Linear regression analysis revealed a very strong relationship (correlation coefficient of 0.935, p < 0.0001) between the degree of imposex and the extent of DNA damage (micronucleus formation) in hemocytes. Moreover, histological examination of a larger number of dog-whelks collected from sites throughout Europe confirmed the presence of hyperplastic growths, primarily on the vas deferens and penis in both TBT-exposed male snails and in females that exhibited imposex. A strong association was found between TBT body burden and the prevalence of abnormal growths, thereby providing compelling evidence to support the hypothesis that environmental chemicals that affect reproductive processes do so partly through DNA damage pathways

Steady-state solution for dark states using a three-level system in coupled quantum dots

Quantum dots (QDs) are one of the promising candidates of interconnection between electromagnetic field and electrons in solid-state devices. Dark states appear as a result of coherence between the electromagnetic fields and the discrete energy levels of the system. Here, we theoretically solve the steady-state solutions of the density matrix equations for a thee-level double QD system and investigate the condition of the appearance of a dark state. We also numerically show the appearance of the dark state by time-dependent current characteristics.Comment: 5 pages, 5 figure

CD81 and claudin 1 coreceptor association: role in hepatitis C virus entry.

Hepatitis C virus (HCV) is an enveloped positive-stranded RNA hepatotropic virus. HCV pseudoparticles infect liver-derived cells, supporting a model in which liver-specific molecules define HCV internalization. Three host cell molecules have been reported to be important entry factors or receptors for HCV internalization: scavenger receptor BI, the tetraspanin CD81, and the tight junction protein claudin-1 (CLDN1). None of the receptors are uniquely expressed within the liver, leading us to hypothesize that their organization within hepatocytes may explain receptor activity. Since CD81 and CLDN1 act as coreceptors during late stages in the entry process, we investigated their association in a variety of cell lines and human liver tissue. Imaging techniques that take advantage of fluorescence resonance energy transfer (FRET) to study protein-protein interactions have been developed. Aequorea coerulescens green fluorescent protein- and Discosoma sp. red-monomer fluorescent protein-tagged forms of CD81 and CLDN1 colocalized, and FRET occurred between the tagged coreceptors at comparable frequencies in permissive and nonpermissive cells, consistent with the formation of coreceptor complexes. FRET occurred between antibodies specific for CD81 and CLDN1 bound to human liver tissue, suggesting the presence of coreceptor complexes in liver tissue. HCV infection and treatment of Huh-7.5 cells with recombinant HCV E1-E2 glycoproteins and anti-CD81 monoclonal antibody modulated homotypic (CD81-CD81) and heterotypic (CD81-CLDN1) coreceptor protein association(s) at specific cellular locations, suggesting distinct roles in the viral entry process

Symptoms and Stereotypes: Perceptions and Responses to Covid-19 in Malawi and Zambia

A large literature documents Covid-19’s health and economic effects. We focus instead on its political impact and its potential to exacerbate identity divisions, in particular. Psychologists argue that contagious disease increases threat perceptions and provokes policing of group boundaries. We explore how insider-outsider status and symptoms of illness shape perceptions of infection, reported willingness to help, and desire to restrict free movement of an ailing neighbor using a phone-based survey experiment administered three times in two neighboring African countries during different stages of the pandemic: Malawi, from May 5 to June 2, 2020 (n = 4,641); Zambia, from July 2 to August 13, 2020 (n = 2,198); and Malawi again, from March 9 to May 1, 2021 (n = 4,356). We study identities that are salient in Malawi and Zambia but have not induced significant prior violence, making our study a relatively hard test of disease threat theories. We find that symptoms more strongly shape perceptions and projected behavior than insider-outsider status in both countries and across time, suggesting that there are limits to the ability of pandemics to independently provoke identity politics de novo