305 research outputs found
Structural dynamics verification facility study
The need for a structural dynamics verification facility to support structures programs was studied. Most of the industry operated facilities are used for highly focused research, component development, and problem solving, and are not used for the generic understanding of the coupled dynamic response of major engine subsystems. Capabilities for the proposed facility include: the ability to both excite and measure coupled structural dynamic response of elastic blades on elastic shafting, the mechanical simulation of various dynamical loadings representative of those seen in operating engines, and the measurement of engine dynamic deflections and interface forces caused by alternative engine mounting configurations and compliances
Towards predictive modelling of near-edge structures in electron energy loss spectra of AlN based ternary alloys
Although electron energy loss near edge structure analysis provides a tool
for experimentally probing unoccupied density of states, a detailed comparison
with simulations is necessary in order to understand the origin of individual
peaks. This paper presents a density functional theory based technique for
predicting the N K-edge for ternary (quasi-binary) nitrogen alloys by adopting
a core hole approach, a methodology that has been successful for binary nitride
compounds. It is demonstrated that using the spectra of binary compounds for
optimising the core hole charge ( for cubic TiAlN
and for wurtzite AlGaN), the predicted spectra
evolutions of the ternary alloys agree well with the experiments. The spectral
features are subsequently discussed in terms of the electronic structure and
bonding of the alloys.Comment: 11 pages, 9 figures, 1 tabl
Composition and luminescence studies of InGaN epilayers grown at different hydrogen flow rates
Indium gallium nitride (In(x)Ga(1-x)N) is a technologically important material for many optoelectronic devices, including LEDs and solar cells, but it remains a challenge to incorporate high levels of InN into the alloy while maintaining sample quality. A series of InGaN epilayers was grown with different hydrogen flow rates (0-200 sccm) and growth temperatures (680-750 °C) to obtain various InN fractions and bright emission in the range 390-480 nm. These 160-nm thick epilayers were characterized through several compositional techniques (wavelength dispersive x-ray spectroscopy, x-ray diffraction, Rutherford backscattering spectrometry) and cathodoluminescence hyperspectral imaging. The compositional analysis with the different techniques shows good agreement when taking into account compositional gradients evidenced in these layers. The addition of small amounts of hydrogen to the gas flow at lower growth temperatures is shown to maintain a high surface quality and luminescence homogeneity. This allowed InN fractions of up to ~16% to be incorporated with minimal peak energy variations over a mapped area while keeping a high material quality
Carrier distribution in InGaN/GaN tricolor multiple quantum well light emitting diodes
Carrier transport in InGaN light emitting diodes has been studied by comparing the electroluminescence (EL) from a set of triple quantum well structures with different indium content in each well, leading to multicolor emission. Both the sequence and width of the quantum wells have been varied. Comparison of the EL spectra reveals the current dependent carrier transport between the quantum wells, with a net carrier flow toward the deepest quantum well. (C) 2009 American Institute of Physics. (doi:10.1063/1.3244203
Changes in mortality patterns and place of death during the COVID-19 pandemic:A descriptive analysis of mortality data across four nations
Background: Understanding patterns of mortality and place of death during the COVID-19 pandemic is important to help provide appropriate services and resources. Aims: To analyse patterns of mortality including place of death in the United Kingdom (UK) (England, Wales, Scotland and Northern Ireland) during the COVID-19 pandemic to date. Design: Descriptive analysis of UK mortality data between March 2020 and March 2021. Weekly number of deaths was described by place of death, using the following definitions: (1) expected deaths: average expected deaths estimated using historical data (2015–19); (2) COVID-19 deaths: where COVID-19 is mentioned on the death certificate; (3) additional non-COVID-19 deaths: above expected but not attributed to COVID-19; (4) baseline deaths: up to and including expected deaths but excluding COVID-19 deaths. Results: During the analysis period, 798,643 deaths were registered in the UK, of which 147,282 were COVID-19 deaths and 17,672 were additional non-COVID-19 deaths. While numbers of people who died in care homes and hospitals increased above expected only during the pandemic waves, the numbers of people who died at home remained above expected both during and between the pandemic waves, with an overall increase of 41%. Conclusions: Where people died changed during the COVID-19 pandemic, with an increase in deaths at home during and between pandemic waves. This has implications for planning and organisation of palliative care and community services. The extent to which these changes will persist longer term remains unclear. Further research could investigate whether this is reflected in other countries with high COVID-19 mortality
Group-Based Parent Training Interventions for Parents of Children with Autism Spectrum Disorders: a Literature Review
© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Parents of children with autism spectrum disorders should have access to interventions to help them understand and support their child. This literature review examines the existing evidence for group-based parent training interventions that support parents of children with autism. From the literature, core intervention processes and outcomes are identified and include parenting and parent behaviour, parent health, child behaviour and peer and social support. Results show a positive trend for intervention effectiveness, but findings are limited by low-quality studies and heterogeneity of intervention content, outcomes and outcome measurement. Future research should focus on specifying effective intervention ingredients and modes of delivery, consistent and reliable outcome measurement, and improving methodological rigour to build a more robust evidence base
Fine-tuning language models to find agreement among humans with diverse preferences
Recent work in large language modeling (LLMs) has used fine-tuning to align
outputs with the preferences of a prototypical user. This work assumes that
human preferences are static and homogeneous across individuals, so that
aligning to a a single "generic" user will confer more general alignment. Here,
we embrace the heterogeneity of human preferences to consider a different
challenge: how might a machine help people with diverse views find agreement?
We fine-tune a 70 billion parameter LLM to generate statements that maximize
the expected approval for a group of people with potentially diverse opinions.
Human participants provide written opinions on thousands of questions touching
on moral and political issues (e.g., "should we raise taxes on the rich?"), and
rate the LLM's generated candidate consensus statements for agreement and
quality. A reward model is then trained to predict individual preferences,
enabling it to quantify and rank consensus statements in terms of their appeal
to the overall group, defined according to different aggregation (social
welfare) functions. The model produces consensus statements that are preferred
by human users over those from prompted LLMs (>70%) and significantly
outperforms a tight fine-tuned baseline that lacks the final ranking step.
Further, our best model's consensus statements are preferred over the best
human-generated opinions (>65%). We find that when we silently constructed
consensus statements from only a subset of group members, those who were
excluded were more likely to dissent, revealing the sensitivity of the
consensus to individual contributions. These results highlight the potential to
use LLMs to help groups of humans align their values with one another
Evaluation of the impact of a school gardening intervention on children's fruit and vegetable intake: a randomised controlled trial.
Background: Current academic literature suggests that school gardening programmes can provide an interactive environment with the potential to change children’s fruit and vegetable intake. This is the first cluster randomised controlled trial (RCT) designed to evaluate whether a school gardening programme can have an effect on children’s fruit and vegetable intake.
Methods: The trial included children from 23 schools; these schools were randomised into two groups, one to receive the Royal Horticultural Society (RHS)-led intervention and the other to receive the less involved Teacher-led intervention. A 24-hour food diary (CADET) was used to collect baseline and follow-up dietary intake 18 months apart. Questionnaires were also administered to evaluate the intervention implementation.
Results: A total of 641 children completed the trial with a mean age of 8.1 years (95% CI: 8.0, 8.4). The unadjusted results from multilevel regression analysis revealed that for combined daily fruit and vegetable intake the Teacher-led group had a higher daily mean change of 8 g (95% CI: −19, 36) compared to the RHS-led group -32 g (95% CI: −60, −3). However, after adjusting for possible confounders this difference was not significant (intervention effect: −40 g, 95% CI: −88, 1; p = 0.06). The adjusted analysis of process measures identified that if schools improved their gardening score by 3 levels (a measure of school gardening involvement - the scale has 6 levels from 0 ‘no garden’ to 5 ‘community involvement’), irrespective of group allocation, children had, on average, a daily increase of 81 g of fruit and vegetable intake (95% CI: 0, 163; p = 0.05) compared to schools that had no change in gardening score.
Conclusions: This study is the first cluster randomised controlled trial designed to evaluate a school gardening intervention. The results have found very little evidence to support the claims that school gardening alone can improve children’s daily fruit and vegetable intake. However, when a gardening intervention is implemented at a high level within the school it may improve children’s daily fruit and vegetable intake by a portion. Improving children’s fruit and vegetable intake remains a challenging task
Tamoxifen for prevention of breast cancer: extended long-term follow-up of the IBIS-I breast cancer prevention trial
© Cuzick et al. Open Access article distributed under the terms of CC BY.http://dx.doi.org/10.1016/S1470-2045(14)71171-
Predicting the Risk of Disease Recurrence and Death Following Curative-intent Radiotherapy for Non-small Cell Lung Cancer: The Development and Validation of Two Scoring Systems From a Large Multicentre UK Cohort
AIMS: There is a paucity of evidence on which to produce recommendations on neither the clinical nor the imaging follow-up of lung cancer patients after curative-intent radiotherapy. In the 2019 National Institute for Health and Care Excellence lung cancer guidelines, further research into risk-stratification models to inform follow-up protocols was recommended. MATERIALS AND METHODS: A retrospective study of consecutive patients undergoing curative-intent radiotherapy for non-small cell lung cancer from 1 October 2014 to 1 October 2016 across nine UK trusts was carried out. Twenty-two demographic, clinical and treatment-related variables were collected and multivariable logistic regression was used to develop and validate two risk-stratification models to determine the risk of disease recurrence and death. RESULTS: In total, 898 patients were included in the study. The mean age was 72 years, 63% (562/898) had a good performance status (0-1) and 43% (388/898), 15% (134/898) and 42% (376/898) were clinical stage I, II and III, respectively. Thirty-six per cent (322/898) suffered disease recurrence and 41% (369/898) died in the first 2 years after radiotherapy. The ASSENT score (age, performance status, smoking status, staging endobronchial ultrasound, N-stage, T-stage) was developed, which stratifies the risk for disease recurrence within 2 years, with an area under the receiver operating characteristic curve (AUROC) for the total score of 0.712 (0.671-0.753) and 0.72 (0.65-0.789) in the derivation and validation sets, respectively. The STEPS score (sex, performance status, staging endobronchial ultrasound, T-stage, N-stage) was developed, which stratifies the risk of death within 2 years, with an AUROC for the total score of 0.625 (0.581-0.669) and 0.607 (0.53-0.684) in the derivation and validation sets, respectively. CONCLUSIONS: These validated risk-stratification models could be used to inform follow-up protocols after curative-intent radiotherapy for lung cancer. The modest performance highlights the need for more advanced risk prediction tools
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