30,823 research outputs found
Long secondary periods in variable red giants
‘The definitive version is available at www3.interscience.wiley.com '. Copyright Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.15401.xWe present a study of a sample of Large Magellanic Cloud red giants exhibiting Long Secondary Periods (LSPs). We use radial velocities obtained from VLT spectral observations and MACHO and OGLE light curves to examine properties of the stars and to evaluate models for the cause of LSPs. This sample is much larger than the combined previous studies of Hinkle et al. and Wood, Olivier & Kawaler. Binary and pulsation models have enjoyed much support in recent years. Assuming stellar pulsation, we calculate from the velocity curves that the typical fractional radius change over an LSP cycle is greater than 30 per cent. This should lead to large changes in Teff that are not observed. Also, the small light amplitude of these stars seems inconsistent with the radius amplitude. We conclude that pulsation is not a likely explanation for the LSPs. The main alternative, physical movement of the star – binary motion – also has severe problems. If the velocity variations are due to binary motion, the distribution of the angle of periastron in our large sample of stars has a probability of 1.4 × 10−3 that it comes from randomly aligned binary orbits. In addition, we calculate a typical companion mass of 0.09 M⊙ . Less than 1 per cent of low-mass main-sequence stars have companions near this mass (0.06–0.12 M⊙) whereas ∼25–50 per cent of low-mass red giants end up with LSPs. We are unable to find a suitable model for the LSPs and conclude by listing their known properties.Peer reviewe
Kenaf : a possible multi-purpose crop for the Ord River Irrigation area
Kenaf is a tropical crop which shows promise for use in paper pulp, oil and protein production; the young growth is a nutritious animal feed.
It has proved a highly productive crop in the Ord River Irrigation area, raising speculation about its possible use as a commercial crop there. In this article a CSIRO research worker describes the properties of kenaf and reviews research results with the crop on the Or
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
Extremal Graph Theory for Metric Dimension and Diameter
A set of vertices \emph{resolves} a connected graph if every vertex
is uniquely determined by its vector of distances to the vertices in . The
\emph{metric dimension} of is the minimum cardinality of a resolving set of
. Let be the set of graphs with metric dimension
and diameter . It is well-known that the minimum order of a graph in
is exactly . The first contribution of this
paper is to characterise the graphs in with order
for all values of and . Such a characterisation was
previously only known for or . The second contribution is
to determine the maximum order of a graph in for all
values of and . Only a weak upper bound was previously known
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
Short-Chained Oligo(Ethylene Oxide)-Functionalized Gold Nanoparticles: Realization Of Significant Protein Resistance
Protein corona formed on nanomaterial surfaces play an important role in the bioavailability and cellular uptake of nanomaterials. Modification of surfaces with oligoethylene glycols (OEG) are a common way to improve the resistivity of nanomaterials to protein adsorption. Short-chain ethylene oxide (EO) oligomers have been shown to improve the protein resistance of planar Au surfaces. We describe the application of these EO oligomers for improved protein resistance of 30 nm spherical gold nanoparticles (AuNPs). Functionalized AuNPs were characterized using UV-Vis spectroscopy, dynamic light scattering (DLS), and zeta potential measurements. Capillary electrophoresis (CE) was used for separation and quantitation of AuNPs and AuNP-protein mixtures. Specifically, nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM) was employed for the determination of equilibrium and rate constants for binding between citrate-stabilized AuNPs and two model proteins, lysozyme and fibrinogen. Semi-quantitative CE analysis was carried out for mixtures of EO-functionalized AuNPs and proteins, and results demonstrated a 2.5-fold to 10-fold increase in protein binding resistance to lysozyme depending on the AuNP surface functionalization and a 15-fold increase in protein binding resistance to fibrinogen for both EO oligomers examined in this study
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
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