226 research outputs found
A promising material for non-linear optics: Observation of second harmonic generation from 4-[N-(4-carboxypentyl)-N-methylamino]-4′-nitrostilbene- coated substrates
Glass coated with a nitro amino stilbene carboxylic acid using the Langmuir-Blodgett technique gave a non-centrosymmetric material exhibiting second harmonic generation, 1.06 to 0.53 μm
A pilot Internet "Value of Health" Panel: recruitment, participation and compliance
Objectives
To pilot using a panel of members of the public to provide preference data via the Internet
Methods
A stratified random sample of members of the general public was recruited and familiarised with the standard gamble procedure using an Internet based tool. Health states were perdiodically presented in "sets" corresponding to different conditions, during the study. The following were described: Recruitment (proportion of people approached who were trained); Participation (a) the proportion of people trained who provided any preferences and (b) the proportion of panel members who contributed to each "set" of values; and Compliance (the proportion, per participant, of preference tasks which were completed). The influence of covariates on these outcomes was investigated using univariate and multivariate analyses.
Results
A panel of 112 people was recruited. 23% of those approached (n = 5,320) responded to the invitation, and 24% of respondents (n = 1,215) were willing to participate (net = 5.5%). However, eventual recruitment rates, following training, were low (2.1% of those approached). Recruitment from areas of high socioeconomic deprivation and among ethnic minority communities was low. Eighteen sets of health state descriptions were considered over 14 months. 74% of panel members carried out at least one valuation task. People from areas of higher socioeconomic deprivation and unmarried people were less likely to participate. An average of 41% of panel members expressed preferences on each set of descriptions. Compliance ranged from 3% to 100%.
Conclusion
It is feasible to establish a panel of members of the general public to express preferences on a wide range of health state descriptions using the Internet, although differential recruitment and attrition are important challenges. Particular attention to recruitment and retention in areas of high socioeconomic deprivation and among ethnic minority communities is necessary. Nevertheless, the panel approach to preference measurement using the Internet offers the potential to provide specific utility data in a responsive manner for use in economic evaluations and to address some of the outstanding methodological uncertainties in this field
Impact of discussion on preferences elicited in a group setting
BACKGROUND: The completeness of preferences is assumed as one of the axioms of expected utility theory but has been subject to little empirical study. METHODS: Fifteen non-health professionals was recruited and familiarised with the standard gamble technique. The group then met five times over six months and preferences were elicited independently on 41 scenarios. After individual valuation, the group discussed the scenarios, following which preferences could be changed. Changes made were described and summary measures (mean and median) before and after discussion compared using paired t test and Wilcoxon Signed Rank Test. Semi-structured telephone interviews were carried out to explore attitudes to discussing preferences. These were transcribed, read by two investigators and emergent themes described. RESULTS: Sixteen changes (3.6%) were made to preferences by seven (47%) of the fifteen members. The difference between individual preference values before and after discussion ranged from -0.025 to 0.45. The average effect on the group mean was 0.0053. No differences before and after discussion were statistically significant. The group valued discussion highly and suggested it brought four main benefits: reassurance; improved procedural performance; increased group cohesion; satisfying curiosity. CONCLUSION: The hypothesis that preferences are incomplete cannot be rejected for a proportion of respondents. However, brief discussion did not result in substantial number of changes to preferences and these did not have significant impact on summary values for the group, suggesting that incompleteness, if present, may not have an important effect on cost-utility analyses
Laterality and Flight: Concurrent Tests of Side-Bias and Optimality in Flying Tree Swallows
Behavioural side-bias occurs in many vertebrates, including birds as a result of hemispheric specialization and can be advantageous by improving response times to sudden stimuli and efficiency in multi-tasking. However, behavioural side-bias can lead to morphological asymmetries resulting in reduced performance for specific activities. For flying animals, wing asymmetry is particularly costly and it is unclear if behavioural side-biases will be expressed in flight; the benefits of quick response time afforded by side-biases must be balanced against the costs of less efficient flight due to the morphological asymmetry side-biases may incur. Thus, competing constraints could lead to context-dependent expression or suppression of side-bias in flight. In repeated flight trials through an outdoor tunnel with obstacles, tree swallows (Tachycineta bicolor) preferred larger openings, but we did not detect either individual or population-level side-biases. Thus, while observed behavioural side-biases during substrate-foraging and copulation are common in birds, we did not see such side-bias expressed in obstacle avoidance behaviour in flight. This finding highlights the importance of behavioural context for investigations of side-bias and hemispheric laterality and suggests both proximate and ultimate trade-offs between species-specific cognitive ecology and flight biomechanics
Developing a utility index for the Aberrant Behavior Checklist (ABC-C) for fragile X syndrome
Purpose This study aimed to develop a utility index (the
ABC-UI) from the Aberrant Behavior Checklist-Community
(ABC-C), for use in quantifying the benefit of
emerging treatments for fragile X syndrome (FXS).
Methods The ABC-C is a proxy-completed assessment of
behaviour and is a widely used measure in FXS. A subset
of ABC-C items across seven dimensions was identified to
include in health state descriptions. This item reduction
process was based on item performance, factor analysis and
Rasch analysis performed on an observational study dataset,
and consultation with five clinical experts and a
methodological expert. Dimensions were combined into
health states using an orthogonal design and valued using
time trade-off (TTO), with lead-time TTO methods used
where TTO indicated a state valued as worse than dead.
Preference weights were estimated using mean, individual
level, ordinary least squares and random-effects maximum
likelihood estimation [RE (MLE)] regression models.
Results A representative sample of the UK general public
(n = 349; mean age 35.8 years, 58.2 % female) each valued
12 health states. Mean observed values ranged from
0.92 to 0.16 for best to worst health states. The RE (MLE)
model performed best based on number of significant
coefficients and mean absolute error of 0.018. Mean utilities
predicted by the model covered a similar range to that
observed.
Conclusions The ABC-UI estimates a wide range of
utilities from patient-level FXS ABC-C data, allowing
estimation of FXS health-related quality of life impact for
economic evaluation from an established FXS clinical trial
instrument
Hypoxia shapes the immune landscape in lung injury and promotes the persistence of inflammation
Hypoxemia is a defining feature of acute respiratory distress syndrome (ARDS), an often-fatal complication of pulmonary or systemic inflammation, yet the resulting tissue hypoxia, and its impact on immune responses, is often neglected. In the present study, we have shown that ARDS patients were hypoxemic and monocytopenic within the first 48 h of ventilation. Monocytopenia was also observed in mouse models of hypoxic acute lung injury, in which hypoxemia drove the suppression of type I interferon signaling in the bone marrow. This impaired monopoiesis resulted in reduced accumulation of monocyte-derived macrophages and enhanced neutrophil-mediated inflammation in the lung. Administration of colony-stimulating factor 1 in mice with hypoxic lung injury rescued the monocytopenia, altered the phenotype of circulating monocytes, increased monocyte-derived macrophages in the lung and limited injury. Thus, tissue hypoxia altered the dynamics of the immune response to the detriment of the host and interventions to address the aberrant response offer new therapeutic strategies for ARDS
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