Kinetics of the reduction of metalloproteins by chromous ion

The reduction of Cu(330) in Rhus vernicifera laccase by chromous ion is 30% faster than reduction of Cu(614) at room temperature [pH 4.8, µ = 0.1 (NaCl)], and two parallel first-order paths, attributed to heterogeneity of the protein, are observed at both wavelengths. The reactions of stellacyanin, spinach and French-bean plastocyanins, and cytochrome c with chromous ion under similar conditions are faster than that with laccase by factors of 102 to 104, and are first order in protein concentration. Comparison of rates and activation parameters for the reduction of "blue" copper in laccase, stellacyanin, and the two plastocyanins indicates that reduction of the Cu(614) site in laccase may occur by intramolecular electron transfer from one of the Cu(330) sites. Our value of ΔH (17.4 kcal/mol) for the chromous ion reduction of cytochrome c is consistent with a mechanism in which major conformational changes in the protein must accompany electron transfer

Geometry of Empty Space is the Key to Near-Arrest Dynamics

We study several examples of kinetically constrained lattice models using dynamically accessible volume as an order parameter. Thereby we identify two distinct regimes exhibiting dynamical slowing, with a sharp threshold between them. These regimes are identified both by a new response function in dynamically available volume, as well as directly in the dynamics. Results for the selfdiffusion constant in terms of the connected hole density are presented, and some evidence is given for scaling in the limit of dynamical arrest.Comment: 11 page

Abell 1033: birth of a radio phoenix

Extended steep-spectrum radio emission in a galaxy cluster is usually associated with a recent merger. However, given the complex scenario of galaxy cluster mergers, many of the discovered sources hardly fit into the strict boundaries of a precise taxonomy. This is especially true for radio phoenixes that do not have very well defined observational criteria. Radio phoenixes are aged radio galaxy lobes whose emission is reactivated by compression or other mechanisms. Here, we present the detection of a radio phoenix close to the moment of its formation. The source is located in Abell 1033, a peculiar galaxy cluster which underwent a recent merger. To support our claim, we present unpublished Westerbork Synthesis Radio Telescope and Chandra observations together with archival data from the Very Large Array and the Sloan Digital Sky Survey. We discover the presence of two sub-clusters displaced along the N-S direction. The two sub-clusters probably underwent a recent merger which is the cause of a moderately perturbed X-ray brightness distribution. A steep-spectrum extended radio source very close to an AGN is proposed to be a newly born radio phoenix: the AGN lobes have been displaced/compressed by shocks formed during the merger event. This scenario explains the source location, morphology, spectral index, and brightness. Finally, we show evidence of a density discontinuity close to the radio phoenix and discuss the consequences of its presence.Comment: accepted MNRA

Health promotion interventions to prevent early childhood human influenza at the household level: A realist review to identify implications for programmes in Hong Kong

© 2014 John Wiley & Sons Ltd. Aims and objectives: To identify factors affecting the delivery of health promotion interventions to prevent early childhood human influenza at the household level. Background: Yearly, influenza epidemics seriously affect all age groups, particularly those with weakened immune systems, including children. Influenza is transmitted easily from person to person through droplet and direct contact. Maintaining personal hygiene, avoiding close contact with the infected person and proper hand washing are recommended as the most effective means of preventing the transmission of influenza. However, it is not clear what programme-related mechanisms and contexts are crucial to the successful delivery of interventions in the home. This study systematically reviewed published research studies to identify factors influencing the effective delivery of health promotion programmes targeting influenza in a household. Design: Realist review. Methods: A realist review methodology was selected to examine what interventions are effective in preventing and managing influenza at the household level and in what circumstances. A structured search of the peer-reviewed primary research literature was undertaken using a defined search protocol. Results: Eight studies were retrieved for the analysis. Mechanisms impacting on intervention delivery were identified, including timing of implementation, programme reach, organisational and healthcare worker involvement, mode and place of delivery, contact with infected person, health practice compliance and sustainability at home. Conclusion: These findings suggest contextual factors that could be identified through ecological approaches to health promotion that are crucial for policymakers to consider when designing interventions. Relevance to clinical practice: The active involvement of community nurses through an integrated household visiting programme may help to better deliver family-based health promotion interventions to prevent illnesses such as influenza in children

The approaches Hong Kong Chinese mothers adopt to teach their preschool children to prevent influenza: A multiple case study at household level

© 2016 The Author(s). Background: In Hong Kong, the population is at risk of seasonal influenza infection twice a year. Seasonal influenza is significantly associated with the increased hospitalization of children. Maintaining personal hygiene and vaccination are the most effective measures to prevent influenza infection. Research demonstrates a positive relationship between the health practices applied by parents and the behaviour of their children highlighting the importance of parental heath education. However, there is minimal research that provides an understanding of how Hong Kong Chinese parents teach their children to prevent seasonal influenza. Methods: Mixed methods research was undertaken that employed a multiple-case study approach to gain an understanding of parental teaching practices regarding seasonal influenza prevention. Purposive intensity sampling was adopted to recruit twenty parents and their healthy children. A thematic analysis was employed to examine the qualitative interview data and the quantitative survey data were examined descriptively. These data were then integrated to provide a more rigorous understanding of parental teaching strategies. Comparisons were made across cases to reveal commonalities and differences. Results: Five major themes were identified: processes parents used to teach personal hygiene; parent-child interaction during teaching; approaches to managing children's health behaviours; enhancing children's healthy practices; and parents' perspective of the role of the nurse in health promotion. Conclusions: This study provided valuable insight into the approach of Hong Kong Chinese parents in teaching their children to prevent seasonal influenza. The results indicate that parents can be better supported to develop effective strategies to teach their preschool children hygiene practices for seasonal influenza prevention. Partnerships with community nurses can play a role in building effective parent-child interactions to enhance children's learning and adoption of healthy practices

The role of culture in relation to the seasonal influenza prevention practices of Hong Kong Chinese parents with preschool children

© 2017 Institute of Health Promotion and Education. Aims and objectives: To explore the role of culture in the seasonal influenza prevention practices of Hong Kong Chinese parents with a healthy preschool child. Background: Cultural values and norms significantly influence parents’ health preventive practices and related health promotion strategies. Most research is concerned with influenza prevention and focuses on the factors affecting vaccination uptake, the use of facemasks and effective hand hygiene. There is limited research exploring the influence of culture on the seasonal influenza prevention practices of parents with a young child in Hong Kong. Design: Mixed methods using a multiple-case study approach. Methods: Purposive intensity sampling was employed to recruit 20 parents with children under five years old. A thematic analysis was employed to examine the qualitative interview data and the quantitative data were analysed descriptively. The data were then integrated to provide a more rigorous comprehension of parents’ cultural seasonal influenza preventive practices. Comparisons were conducted across the 20 cases and patterns examined. Results: Five themes were identified. They were sharing beds; boiling white vinegar to kill air-born germs; diet therapy to enhance health; self-prescribed Chinese medication to manage a child’s cold symptoms; and the co-use of Western and traditional Chinese medications to prevent seasonal influenza. Conclusions: The findings indicate that a pluralistic approach to health promotion should be considered to ensure the likelihood that families accept, support and comply with health advice in seasonal influenza prevention. The delivery of culturally appropriate health promotion requires a close partnership between nurses and parents

Efficiency of broadband four-wave mixing wavelength conversion using semiconductor traveling-wave amplifiers

We present a theoretical analysis and experimental measurements of broadband optical wavelength conversion by four-wave mixing in semiconductor traveling-wave amplifiers. In the theoretical analysis, we obtain an analytical expression for the conversion efficiency. In the experiments, both up and down-conversion efficiencies are measured as a function of wavelength shift for shifts up to 27 nm. The experimental data are well explained by the theoretical calculation. The observed higher conversion efficiency for wavelength down-conversion is believed to be caused by phase interferences that exist between various mechanisms contributing to the four-wave mixing process

Discovery of the supernova remnant G351.0-5.4

Context. While searching the NRAO VLA Sky Survey (NVSS) for diffuse radio emission, we have serendipitously discovered extended radio emission close to the Galactic plane. The radio morphology suggests the presence of a previously unknown Galactic supernova remnant. An unclassified {\gamma}-ray source detected by EGRET (3EG J1744-3934) is present in the same location and may stem from the interaction between high-speed particles escaping the remnant and the surrounding interstellar medium. Aims. Our aim is to confirm the presence of a previously unknown supernova remnant and to determine a possible association with the {\gamma}-ray emission 3EG J1744-3934. Methods. We have conducted optical and radio follow-ups of the target using the Dark Energy Camera (DECam) on the Blanco telescope at Cerro Tololo Inter-American Observatory (CTIO) and the Giant Meterwave Radio Telescope (GMRT). We then combined these data with archival radio and {\gamma}-ray observations. Results. While we detected the extended emission in four different radio bands (325, 1400, 2417, and 4850 MHz), no optical counterpart has been identified. Given its morphology and brightness, it is likely that the radio emission is caused by an old supernova remnant no longer visible in the optical band. Although an unclassified EGRET source is co-located with the supernova remnant, Fermi-LAT data do not show a significant {\gamma}-ray excess that is correlated with the radio emission. However, in the radial distribution of the {\gamma}-ray events, a spatially extended feature is related with SNR at a confidence level $\sim 1.5$ {\sigma}. Conclusions. We classify the newly discovered extended emission in the radio band as the old remnant of a previously unknown Galactic supernova: SNR G351.0-5.4.Comment: 6 pages, 6 figures, accepted A&

Terahertz four-wave mixing spectroscopy for study of ultrafast dynamics in a semiconductor optical amplifier

Ultrafast dynamics in a 1.5-µm tensile-strained quantum-well optical amplifier has been studied by highly nondegenerate four-wave mixing at detuning frequencies up to 1.7 THz. Frequency response data indicate the presence of two ultrafast physical processes with characteristic relaxation lifetimes of 650 fs and <100 fs. The longer time constant is believed to be associated with the dynamic carrier heating effect. This is in agreement with previous time-domain pump-probe measurements using ultrashort optical pulses