696 research outputs found
Dependence of energy dissipation on annealing temperature of meltāspun NdFeB permanent magnet materials
A model of magnetic hysteresis which was developed originally for soft magnetic materials has been applied to meltāspun ribbons of Nd2Fe14Bābased material. The crucial ideas in the model description of hysteresis center on a dissipation of energy due to hysteresis which is proportional to the change in magnetization. The Nd2Fe14B material was meltāspun amorphous and then annealed for a period of 24 h at temperatures ranging from 700 to 950āĀ°C. This resulted in different grain sizes, depending on annealing temperature. Consequently the hysteresis curves represent the properties of the material as a function of both annealing temperature and grain size. It was found that the magnetic properties varied systematically with annealing temperature, and hence grain size, as would be expected. When modeling the magnetic properties it was found that the model parameters also varied systematically, in particular, the energy dissipation parameter k was to a first approximation a simple linear function of the annealing temperature and decreased with increasing annealing temperature as a result of grain growth. Therefore, this study revealed a basic relationship between materials processing conditions, microstructure, model parameters, and magnetic properties
Single-photon emitting diode in silicon carbide
Electrically driven single-photon emitting devices have immediate
applications in quantum cryptography, quantum computation and single-photon
metrology. Mature device fabrication protocols and the recent observations of
single defect systems with quantum functionalities make silicon carbide (SiC)
an ideal material to build such devices. Here, we demonstrate the fabrication
of bright single photon emitting diodes. The electrically driven emitters
display fully polarized output, superior photon statistics (with a count rate
of 300 kHz), and stability in both continuous and pulsed modes, all at room
temperature. The atomic origin of the single photon source is proposed. These
results provide a foundation for the large scale integration of single photon
sources into a broad range of applications, such as quantum cryptography or
linear optics quantum computing.Comment: Main: 10 pages, 6 figures. Supplementary Information: 6 pages, 6
figure
Shared care obesity management in 3-10 year old children: 12 month outcomes of HopSCOTCH randomised trial
Objective: To determine whether general practice surveillance for childhood obesity, followed by obesity management across primary and tertiary care settings using a shared care model, improves body mass index and related outcomes in obese children aged 3-10 years. Design: Randomised controlled trial. Setting: 22 family practices (35 participating general practitioners) and a tertiary weight management service (three paediatricians, two dietitians) in Melbourne, Australia. Participants: Children aged 3-10 years with body mass index above the 95th centile recruited through their general practice between July 2009 and April 2010. Intervention: Children were randomly allocated to one tertiary appointment followed by up to 11 general practice consultations over one year, supported by shared care, web based software (intervention) or āusual careā (control). Researchers collecting outcome measurements, but not participants, were blinded to group assignment. Main outcome measures: Childrenās body mass index z score (primary outcome), body fat percentage, waist circumference, physical activity, quality of diet, health related quality of life, self esteem, and body dissatisfaction and parentsā body mass index (all 15 months post-enrolment). Results: 118 (60 intervention, 56 control) children were recruited and 107 (91%) were retained and analysed (56 intervention, 51 control). All retained intervention children attended the tertiary appointment and their general practitioner for at least one (mean 3.5 (SD 2.5, range 1-11)) weight management consultation. At outcome, children in the two trial arms had similar body mass index (adjusted mean difference ā0.1 (95% confidence interval ā0.7 to 0.5; P=0.7)) and body mass index z score (ā0.05 (ā0.14 to 0.03); P=0.2). Similarly, no evidence was found of benefit or harm on any secondary outcome. Outcomes varied widely in the combined cohort (mean change in body mass index z score ā0.20 (SD 0.25, range ā0.97-0.47); 26% of children resolved from obese to overweight and 2% to normal weight. Conclusions: Although feasible, not harmful, and highly rated by both families and general practitioners, the shared care model of primary and tertiary care management did not lead to better body mass index or other outcomes for the intervention group compared with the control group. Improvements in body mass index in both groups highlight the value of untreated controls when determining efficacy.Melissa Wake, Kate Lycett, Susan A Clifford, Matthew A Sabin, Jane Gunn, Kay Gibbons, Cathy Hutton, ZoĆ« McCallum, Sarah J Arnup, Gary Witter
Outcomes and costs of primary care surveillance and intervention for overweight or obese children: the LEAP 2 randomised controlled trial
addresses: Royal Children's Hospital, Murdoch Childrens Research Institute and University of Melbourne, Parkville, Vic 3052, Australia. [email protected]: PMCID: PMC2737607types: Journal Article; Multicenter Study; Randomized Controlled Trial; Research Support, Non-U.S. Gov'tCopyright Ā© 2009 by the BMJ Publishing Group Ltd. This articles was first published in: BMJ, 2009, Vol. 339, pp. b3308 -To determine whether ascertainment of childhood obesity by surveillance followed by structured secondary prevention in primary care improved outcomes in overweight or mildly obese children
Need Polynomial Systems Be Doubly-Exponential?
Polynomial Systems, or at least their algorithms, have the reputation of
being doubly-exponential in the number of variables [Mayr and Mayer, 1982],
[Davenport and Heintz, 1988]. Nevertheless, the Bezout bound tells us that that
number of zeros of a zero-dimensional system is singly-exponential in the
number of variables. How should this contradiction be reconciled?
We first note that [Mayr and Ritscher, 2013] shows that the doubly
exponential nature of Gr\"{o}bner bases is with respect to the dimension of the
ideal, not the number of variables. This inspires us to consider what can be
done for Cylindrical Algebraic Decomposition which produces a
doubly-exponential number of polynomials of doubly-exponential degree.
We review work from ISSAC 2015 which showed the number of polynomials could
be restricted to doubly-exponential in the (complex) dimension using McCallum's
theory of reduced projection in the presence of equational constraints. We then
discuss preliminary results showing the same for the degree of those
polynomials. The results are under primitivity assumptions whose importance we
illustrate.Comment: Extended Abstract for ICMS 2016 Presentation. arXiv admin note: text
overlap with arXiv:1605.0249
Shanghai RAPESEED Database: a resource for functional genomics studies of seed development and fatty acid metabolism of Brassica
The Shanghai RAPESEED Database (RAPESEED, http://rapeseed.plantsignal.cn/) was created to provide the solid platform for functional genomics studies of oilseed crops with the emphasis on seed development and fatty acid metabolism. The RAPESEED includes the resource of 8462 unique ESTs, of which 3526 clones are with full length cDNA; the expression profiles of 8095 genes and the Serial Analysis of Gene Expression (SAGE, 23 895 unique tags) and tag-to-gene data during seed development. In addition, a total of ā¼14 700 M3 mutant populations were generated by ethylmethanesulfonate (EMS) mutagenesis and related seed quality information was determined using the Foss NIR System. Further, the TILLING (Targeting Induced Local Lesions IN Genomes) platform was established based on the generated EMS mutant population. The relevant information was collected in RAPESEED database, which can be searched through keywords, nucleotide or protein sequences, or seed quality parameters, and downloaded
Exotic (anti)ferromagnetism in single crystals of Pr6Ni2Si3
The ternary intermetallic compound Pr6Ni2Si3, is a member of a structure
series of compounds based on a triangular structure where the number of Pr
atoms in the prism cross section can be systematically varied. Pr6Ni2Si3
contains two distinct Pr lattice sites which result in complex interactions
between the magnetic ions. Extensive measurements of specific heat and
magnetization on single crystal samples indicate that Pr6Ni2Si3 orders with
both a ferromagnet and an antiferromagnet component, with ordering temperatures
of 39.6 K and ~ 32 K, respectively. The ferromagnetic component // c-axis is
accompanied by a large hysteresis, and the antiferromagnetic component,_|_
c-axis is accompanied by a spin-flop-type transition. More detailed
measurements, of the vector magnetization, indicate that the ferromagnetic and
the antiferromagnetic order appear independent of each other. These results not
only clarify the behavior of Pr6Ni2Si3 itself, but also of the other members of
the structure series, Pr5Ni2Si3 and Pr15Ni7Si10.Comment: 9 pages, 13 figures, submitted to PR
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