28,999 research outputs found
Environmental protection of titanium alloys at high temperatures
Various concepts were evaluated for protecting titanium alloys from oxygen contamination at 922 K (1200 F) and from hot-salt stress-corrosion at 755 K (900 F). It is indicated that oxygen-contamination resistance can be provided by a number of systems, but for hot-salt stress-corrosion resistance, factors such as coating integrity become very important. Titanium aluminides resist oxygen ingress at 922 K through the formation of alumina (on TiAl3) or modified TiO2 (on Ti3Al, TiAl) scales. TiAl has some resistance to attack by hot salt, but has limited ductility. Ductile Ti-Ni and Ti-Nb-Cr-Al alloys provide limited resistance to oxygen ingress, but are not greatly susceptible to hot-salt stress-corrosion cracking
Comparison of Allen Carr's Easyway programme with a specialist behavioural and pharmacological smoking cessation support service: a randomized controlled trial.
BACKGROUND AND AIMS: A combination of behavioural and pharmacological support is judged to be the optimal approach for assisting smoking cessation. Allen Carr's Easyway (ACE) is a single-session pharmacotherapy-free programme that has been in operation internationally for 38 years. We compared the effectiveness of ACE with specialist behavioural and pharmacological support delivered to the national standard in England. DESIGN: A two-arm, parallel-group, single-blind, randomized controlled trial. SETTING: London, UK, between February 2017 and May 2018. PARTICIPANTS: A total of 620 participants (310 in ACE and 310 in the combined behavioural and pharmacological support condition) were included in the analysis. Adult (≥ 18 years) smokers wanting to quit were randomized in a 1 : 1 ratio. Mean age for the total sample was 40.8 years, with 53.4% being male. Participant baseline characteristics (ethnicity, educational level, number of previous quit attempts, nicotine dependence) were evenly balanced between treatment groups. INTERVENTION AND COMPARATOR: The intervention was the ACE method of stopping smoking. This centres on a 4.5-6-hour session of group-based support, alongside subsequent text messages and top-up sessions if needed. It aims to make it easy to stop smoking by convincing smokers that smoking provides no benefits for them. The comparator was a specialist stop smoking service (SSS) providing behavioural and pharmacological support in accordance with national standards. MEASUREMENTS: The primary outcome was self-reported continuous abstinence for 26 weeks from the quit/quit re-set date verified by exhaled breath carbon monoxide measurement < 10 parts per million (p.p.m.). Primary analysis was by intention to treat. Secondary outcomes were: use of pharmacotherapy, adverse events and continuous abstinence up to 4 and 12 weeks. FINDINGS: A total of 468 participants attended treatment (255 ACE versus 213 SSS, P < 0.05). Of those who did attend treatment, 100 completed 6-month measures (23.7% ACE versus 20.7% SSS). Continuous abstinence to 26 weeks was 19.4% (60 of 310) in the ACE intervention and 14.8% (46 of 310) in the SSS intervention [risk difference for ACE versus SSS 4.5% (95% confidence interval (CI) = -1.4 to 10.4%, odds ratio (OR) = 1.38)]. The Bayes factor for superiority of the ACE condition was 1.24. CONCLUSION: There was no clear evidence of a difference in the efficacies of the Allen Carr's Easyway (ACE) and specialist smoking cessation support involving behavioural support and pharmacotherapy
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Creative User-Centered Visualization Design for Energy Analysts and Modelers
We enhance a user-centered design process with techniques that deliberately promote creativity to identify opportunities for the visualization of data generated by a major energy supplier. Visualization prototypes developed in this way prove effective in a situation whereby data sets are largely unknown and requirements open – enabling successful exploration of possibilities for visualization in Smart Home data analysis. The process gives rise to novel designs and design metaphors including data sculpting. It suggests: that the deliberate use of creativity techniques with data stakeholders is likely to contribute to successful, novel and effective solutions; that being explicit about creativity may contribute to designers developing creative solutions; that using creativity techniques early in the design process may result in a creative approach persisting throughout the process. The work constitutes the first systematic visualization design for a data rich source that will be increasingly important to energy suppliers and consumers as Smart Meter technology is widely deployed. It is novel in explicitly employing creativity techniques at the requirements stage of visualization design and development, paving the way for further use and study of creativity methods in visualization design
Spectropolarimetry of the H-alpha line in Herbig Ae/Be stars
Using the HiVIS spectropolarimeter built for the Haleakala 3.7m AEOS
telescope, we have obtained a large number of high precision spectropolarimetrc
observations (284) of Herbig AeBe stars collected over 53 nights totaling more
than 300 hours of observing. Our sample of five HAeBe stars: AB Aurigae,
MWC480, MWC120, MWC158 and HD58647, all show systematic variations in the
linear polarization amplitude and direction as a function of time and
wavelength near the H-alpha line. In all our stars, the H-alpha line profiles
show evidence of an intervening disk or outflowing wind, evidenced by strong
emission with an absorptive component. The linear polarization varies by 0.2%
to 1.5% with the change typically centered in the absorptive part of the line
profile. These observations are inconsistent with a simple disk-scattering
model or a depolarization model which produce polarization changes centered on
the emmissive core. We speculate that polarized absorption via optical pumping
of the intervening gas may be the cause.Comment: Accepted for publication in ApJ Letter
The lead discrepancy in intrinsically s-process enriched post-AGB stars in the Magellanic Clouds
Context: Our understanding of the s-process nucleosynthesis in asymptotic
giant branch (AGB) stars is incomplete. AGB models predict, for example, large
overabundances of lead (Pb) compared to other s-process elements in metal-poor
low-mass AGB stars. This is indeed observed in some extrinsically enhanced
metal-poor stars, but not in all. An extensive study of intrinsically s-process
enriched objects is essential for improving our knowledge of the AGB third
dredge-up and associated s-process nucleosynthesis. Aims: We compare the
spectral abundance analysis of the SMC post-AGB star J004441.04-732136.4 with
state-of-the-art AGB model predictions with a main focus on Pb. The low S/N in
the Pb line region made the result of our previous study inconclusive. We
acquired additional data covering the region of the strongest Pb line. Methods:
By carefully complementing re-reduced previous data, with newly acquired UVES
optical spectra, we improve the S/N of the spectrum around the strongest Pb
line. Therefore, an upper limit for the Pb abundance is estimated from a merged
weighted mean spectrum using synthetic spectral modeling. We then compare the
abundance results from the combined spectra to predictions of tailored AGB
evolutionary models from two independent evolution codes. In addition, we
determine upper limits for Pb abundances for three previously studied LMC
post-AGB objects. Results: Although theoretical predictions for
J004441.04-732136.4 match the s-process distribution up to tungsten (W), the
predicted very high Pb abundance is clearly not detected. The three additional
LMC post-AGB stars show a similar lack of a very high Pb abundance. Conclusion:
From our study, we conclude that none of these low-mass, low-metallicity
post-AGB stars of the LMC and SMC are strong Pb producers. This conflicts with
current theoretical predictions.Comment: 4 pages, 3 figure
The first direct detection of a gravitational micro-lens toward the Galactic bulge
We present a direct detection of the gravitational lens that caused the
microlensing event MACHO-95-BLG-37. This is the first fully resolved
microlensing system involving a source in the Galactic bulge, and the second
such system in general. The lens and source are clearly resolved in images
taken with the High Resolution Channel of the Advanced Camera for Surveys on
board the Hubble Space Telescope (HST) ~9 years after the microlensing event.
The presently available data are not sufficient for the final, unambiguous
identification of the gravitational lens and the microlensed source. While the
light curve models combined with the high resolution photometry for individual
objects indicate that the source is red and the lens is blue, the
color-magnitude diagram for the line of sight and the observed proper motions
strongly support the opposite case. The first scenario points to a metal-poor
lens with mass M = ~0.6 M_Sun at the distance D_l = ~4 kpc. In the second
scenario the lens could be a main-sequence star with M = 0.8 - 0.9 M_Sun about
half-way to the Galactic bulge or in the foreground disk, depending on the
extinction.Comment: Accepted for publication in Ap
The influence of hypercapnia and the infaunal brittlestar <i>Amphiura filiformis</i> on sediment nutrient flux – will ocean acidification affect nutrient exchange?
Rising levels of atmospheric carbon dioxide and the concomitant increased uptake of this by the oceans is resulting in hypercapnia-related reduction of ocean pH. Research focussed on the direct effects of these physicochemical changes on marine invertebrates has begun to improve our understanding of impacts at the level of individual physiologies. However, CO<sub>2</sub>-related impairment of organisms' contribution to ecological or ecosystem processes has barely been addressed. The burrowing ophiuroid <i>Amphiura filiformis</i>, which has a physiology that makes it susceptible to reduced pH, plays a key role in sediment nutrient cycling by mixing and irrigating the sediment, a process known as bioturbation. Here we investigate the role of <i>A. filiformis</i> in modifying nutrient flux rates across the sediment-water boundary and the impact of CO<sub>2</sub>- related acidification on this process. A 40 day exposure study was conducted under predicted pH scenarios from the years 2100 (pH 7.7) and 2300 (pH 7.3), plus an additional treatment of pH 6.8. This study demonstrated strong relationships between <i>A. filiformis</i> density and cycling of some nutrients; <iA. filiformis</i> activity increases the sediment uptake of phosphate and the release of nitrite and nitrate. No relationship between <i>A. filiformis</i> density and the flux of ammonium or silicate were observed. Results also indicated that, within the timescale of this experiment, effects at the individual bioturbator level appear not to translate into reduced ecosystem influence. However, long term survival of key bioturbating species is far from assured and changes in both bioturbation and microbial processes could alter key biogeochemical processes in future, more acidic oceans
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