1,656 research outputs found
Ring-Pattern Dynamics in Smectic-C* and Smectic-C_A* Freely Suspended Liquid Crystal Films
Ring patterns of concentric 2pi-solitons in molecular orientation, form in
freely suspended chiral smectic-C films in response to an in-plane rotating
electric field. We present measurements of the zero-field relaxation of ring
patterns and of the driven dynamics of ring formation under conditions of
synchronous winding, and a simple model which enables their quantitative
description in low polarization DOBAMBC. In smectic C_A* TFMHPOBC we observe an
odd-even layer number effect, with odd number layer films exhibiting order of
magnitude slower relaxation rates than even layer films. We show that this rate
difference is due to much larger spontaneous polarization in odd number layer
films.Comment: 4 RevTeX pgs, 4 eps figures, submitted to Phys. Rev. Let
Brazilian Think Tanks and the Rise of Austerity Discourse
This article discusses the role of think tanks in the production of ideas guiding recent change in Brazilâs economic policy. It claims that think tanks are significant policy-making agents preparing the society for change â via their communicative discourse â but also attempting to influence the interaction between political elites â via their coordinative discourse. The polarization of think tanksâ communicative discourse in regard to austerity during two critical junctures for Brazil is analysed. Discursive institutionalism is applied in order to interpret data from four Brazilian think tanks: the Institute of Applied Economic Research, the Inter-Union Department of Statistics and Socioeconomic Studies, the Fernand Braudel Institute and the Brazilian Institute of Economy. These think tanks have very different organizational and ideological characteristics but a polarization of the discussion around austerity can be observed in the discourse of all four of them. The scale ranges from an active defence of the Brazilian development model to a full-scale endorsement of austerity
Women's reasons and perceptions around planning a homebirth with a registered midwife in Western Australia
Background: Qualitative evidence has provided rich descriptions around reasons for planning a homebirth with a midwife. Reasons and the importance, confidence and support around this option have not been examined by parity with a larger cohort. Aim: Examine women's characteristics, reasons and perceptions of the importance, confidence and support around choosing homebirth based upon parity. Methods: A mixed method approach was undertaken within a prospective cohort study in Western Australia where women planning a homebirth have the option of a publicly funded model or care from privately practising midwives. At recruitment a questionnaire collected demographic data, perceived importance, confidence and support plus reasons for choosing homebirth. A qualitative component included an open ended question that encouraged sharing of opinions providing textual data explored by content analysis. Findings: Reasons noted by 211 pregnant women for choosing homebirth were: avoidance of unnecessary intervention (58.8%), comfort and familiarity of home (34.1%), freedom of making own choices (25.6%), and having more continuity of care (24.2%). Reasons for planning homebirth were similar by parity, except for comfort of home being more important (44.0% vs 28.7%, p = 0.025) and continuity of care (13.3% vs 30.1%, p = 0.006) being less important to primigravid women. Themes revealed common beliefs around childbirth, appreciation for access to homebirth and a desire for greater awareness and less negativity around homebirth. Conclusion: Regardless of parity, homebirth was believed to be safe and supported by partners. Reasons identified from qualitative research to avoid intervention, the comfort of home, choice and continuity of care were supported
HD 178892 - a cool Ap star with extremely strong magnetic field
We report a discovery of the Zeeman resolved spectral lines, corresponding to
the extremely large magnetic field modulus =17.5 kG, in the cool Ap star HD
178892. The mean longitudinal field of this star reaches 7.5 kG, and its
rotational modulation implies the strength of the dipolar magnetic component
Bp>=23 kG. We have revised rotation period of the star using the All Sky
Automated Survey photometry and determined P=8.2478 d. Rotation phases of the
magnetic and photometric maxima of the star coincide with each other. We
obtained Geneva photometric observation of HD 178892 and estimated
Teff=7700+/-250 K using photometry and the hydrogen Balmer lines. Preliminary
abundance analysis reveals abundance pattern typical of rapidly oscillating Ap
stars.Comment: Accepted by Astronomy & Astrophysics; 4 pages, 4 figure
Searching for links between magnetic fields and stellar evolution. II. The evolution of magnetic fields as revealed by observations of Ap stars in open clusters and associations
The evolution of magnetic fields in Ap stars during the main sequence phase
is presently mostly unconstrained by observation because of the difficulty of
assigning accurate ages to known field Ap stars.
We are carrying out a large survey of magnetic fields in cluster Ap stars
with the goal of obtaining a sample of these stars with well-determined ages.
In this paper we analyse the information available from the survey as it
currently stands.
We select from the available observational sample the stars that are probably
(1) cluster or association members and (2) magnetic Ap stars. For the stars in
this subsample we determine the fundamental parameters T_eff, log(L/L_o), and
M/M_o. With these data and the cluster ages we assign both absolute age and
fractional age (the fraction of the main sequence lifetime completed). For this
purpose we have derived new bolometric corrections for Ap stars.
Magnetic fields are present at the surfaces of Ap stars from the ZAMS to the
TAMS. Statistically for the stars with M > 3 M_o the fields decline with
advancing age approximately as expected from flux conservation together with
increased stellar radius, or perhaps even faster than this rate, on a time
scale of about 3 10^7 yr. In contrast, lower mass stars show no compelling
evidence for field decrease even on a timescale of several times 10^8 yr.
Study of magnetic cluster stars is now a powerful tool for obtaining
constraints on evolution of Ap stars through the main sequence. Enlarging the
sample of known cluster magnetic stars, and obtaining more precise RMS fields,
will help to clarify the results obtained so far. Further field observations
are in progress.Comment: Accepted by Astronomy & Astrophysic
Ten steps or climbing a mountain: A study of Australian health professionals' perceptions of implementing the baby friendly health initiative to protect, promote and support breastfeeding
Background: The Baby Friendly Hospital (Health) Initiative (BFHI) is a global initiative aimed at protecting,
promoting and supporting breastfeeding and is based on the ten steps to successful breastfeeding. Worldwide,
over 20,000 health facilities have attained BFHI accreditation but only 77 Australian hospitals (approximately 23%)
have received accreditation. Few studies have investigated the factors that facilitate or hinder implementation of
BFHI but it is acknowledged this is a major undertaking requiring strategic planning and change management
throughout an institution. This paper examines the perceptions of BFHI held by midwives and nurses working in
one Area Health Service in NSW, Australia.
Methods: The study used an interpretive, qualitative approach. A total of 132 health professionals, working across four maternity units, two neonatal intensive care units and related community services, participated in 10 focus groups. Data were analysed using thematic analysis.
Results: Three main themes were identified: âBelief and Commitmentâ; âInterpreting BFHIâ and âClimbing a
Mountainâ. Participants considered the BFHI implementation a high priority; an essential set of practices that would
have positive benefits for babies and mothers both locally and globally as well as for health professionals. It was
considered achievable but would take commitment and hard work to overcome the numerous challenges including a number of organisational constraints. There were, however, differing interpretations of what was required to attain BFHI accreditation with the potential that misinterpretation could hinder implementation.
A model described by Greenhalgh and colleagues on adoption of innovation is drawn on to interpret the findings.
Conclusion: Despite strong support for BFHI, the principles of this global strategy are interpreted differently by
health professionals and further education and accurate information is required. It may be that the current
processes used to disseminate and implement BFHI need to be reviewed. The findings suggest that there is a
contradiction between the broad philosophical stance and best practice approach of this global strategy and the
tendency for health professionals to focus on the ten steps as a set of tasks or a checklist to be accomplished. The
perceived procedural approach to implementation may be contributing to lower rates of breastfeeding
continuation
Efficacy of BravectoÂź Plus spot-on solution for cats (280 mg/ml fluralaner and 14 mg/ml moxidectin) for the prevention of aelurostrongylosis in experimentally infected cats
Background: The feline lungworm Aelurostrongylus abstrusus affects the lower respiratory tract in cats worldwide. As infections may lead to chronic respiratory changes or even death, preventive treatment in cats with outdoor access is warranted. Methods: The preventive efficacy of a spot-on solution (BravectoÂź Plus spot-on solution for cats, MSD) against cat aelurostrongylosis was evaluated using three different preventive treatment regimes in a negative controlled, randomized and partially blinded laboratory efficacy study with 31 purposed-bred cats. The minimum recommended dose of 2.0 mg moxidectin + 40 mg fluralaner/kg bodyweight was applied once 12 (Group [G]1), 8 (G2) or 4 (G3) weeks before experimental infection with 300 third-stage larvae (L3) of A. abstrusus. Another group served as untreated control (G4). Individual faecal samples were analysed as of day 30 post infection (pi) to monitor larvae excretion. Necropsy was performed at days 47â50 pi. The lungs were examined macroscopically for pathological findings and (pre-)adult worms were counted to assess preventive efficacy. Results: Beginning at day 32â40 pi, all cats of the control group were constantly shedding larvae of A. abstrusus, whereas only one animal of G1 excreted larvae at several consecutive days. In addition, two cats of G1 and G3 and three of G2 were positive on a single occasion. The geometric mean (GM) of the maximum number of excreted larvae was 7574.29 in the control group compared to 1.10 (G1), 1.19 (G2) and 0.53 (G3), resulting in a GM reduction of > 99.9% in all treatment groups. All lungs of the control animals showed severe or very severe alterations at necropsy, while in 94.44% of the treated cats lung pathology was rated as absent or mild. The GM number of (pre-)adult A. abstrusus retrieved from the lungs was 26.57 in the control group, 0.09 in G1 and 0.00 in G2 and G3. Thus, GM worm count reduction was 99.66% in G1 and 100% in G2 and G3. Conclusions: A single application of BravectoÂź Plus spot-on solution at a dose of 2.0 mg moxidectin + 40 mg fluralaner/kg bodyweight reliably prevents cat aelurostrongylosis for at least 12 weeks.[Figure not available: see fulltext.
Drivers and uncertainties of future global marine primary production in marine ecosystem models
Past model studies have projected a global decrease in marine net primary production (NPP) over the 21st century, but these studies focused on the multi-model mean rather than on the large inter-model differences. Here, we analyze model-simulated changes in NPP for the 21st century under IPCC's high-emission scenario RCP8.5. We use a suite of nine coupled carbonâclimate Earth system models with embedded marine ecosystem models and focus on the spread between the different models and the underlying reasons. Globally, NPP decreases in five out of the nine models over the course of the 21st century, while three show no significant trend and one even simulates an increase. The largest model spread occurs in the low latitudes (between 30° S and 30° N), with individual models simulating relative changes between â25 and +40 %. Of the seven models diagnosing a net decrease in NPP in the low latitudes, only three simulate this to be a consequence of the classical interpretation, i.e., a stronger nutrient limitation due to increased stratification leading to reduced phytoplankton growth. In the other four, warming-induced increases in phytoplankton growth outbalance the stronger nutrient limitation. However, temperature-driven increases in grazing and other loss processes cause a net decrease in phytoplankton biomass and reduce NPP despite higher growth rates. One model projects a strong increase in NPP in the low latitudes, caused by an intensification of the microbial loop, while NPP in the remaining model changes by less than 0.5 %. While models consistently project increases NPP in the Southern Ocean, the regional inter-model range is also very substantial. In most models, this increase in NPP is driven by temperature, but it is also modulated by changes in light, macronutrients and iron as well as grazing. Overall, current projections of future changes in global marine NPP are subject to large uncertainties and necessitate a dedicated and sustained effort to improve the models and the concepts and data that guide their developmen
A Mercury Lander Mission Concept Study for the Next Decadal Survey
Mariner 10 provided our first closeup reconnaissance of Mercury during its three flybys in 1974 and 1975. MESSENGERs 20112015 orbital investigation enabled numerous discoveries, several of which led to substantial or complete changes in our fundamental understanding of the planet. Among these were the unanticipated, widespread presence of volatile elements (e.g., Na, K, S); a surface with extremely low Fe abundance whose darkening agent is likely C; a previously unknown landformhollows that may form by volatile sublimation from within rocks exposed to the harsh conditions on the surface; a history of expansive effusive and explosive volcanism; substantial radial contraction of the planet from interior cooling; offset of the dipole moment of the internal magnetic field northward from the geographic equator by ~20% of the planets radius; crustal magnetization, attributed at least in part to an ancient field; unexpected seasonal variability and relationships among exospheric species and processes; and the presence in permanently shadowed polar terrain of water ice and other volatile materials, likely to include complex organic compounds. Mercurys highly chemically reduced and unexpectedly volatile-rich composition is unique among the terrestrial planets and was not predicted by earlier hypotheses for the planets origin. As an end-member of terrestrial planet formation, Mercury holds unique clues about the original distribution of elements in the earliest stages of the Solar System and how planets (and exoplanets) form and evolve in close proximity to their host stars. The BepiColombo mission promises to expand our knowledge of this planet and to shed light on some of the mysteries revealed by the MESSENGER mission. However, several fundamental science questions raised by MESSENGERs pioneering exploration of Mercury can only be answered with in situ measurements from the planets surface
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