7,045 research outputs found
Comparative Effectiveness of Step-up Therapies in Children with Asthma Prescribed Inhaled Corticosteroids : A Historical Cohort Study
This work was supported by the Respiratory Effectiveness Group. Acknowledgments We thank the Respiratory Effectiveness Group for funding this work, Annie Burden for assistance with statistics, and Simon Van Rysewyk and Lisa Law for assistance with medical writing.Peer reviewedPostprin
Analyzing the 3D Printed Material Tango Plus FLX930 for Using in Self-Folding Structure
Self-folding is the ability of the structure to fold and/or unfold without human intervention or any application of external manipulation. It is known that the structure of folding object consists of two essential parts. These parts are the faces and the creases. In this paper, it is assumed that the faces could be built by using solid materials, and the crease lines can be built using soft material which provides a high bent ability. Furthermore, these two materials should be combined built without using any connections between them. Fortunately, the 3D printer provides this capability. It can print two types of different materials at the same time for the same structure. Therefore, a 3D printer is chosen to fabricate a folding structure using two types of material. These types are the Vero for solid faces and Tango plus FLX930 for the soft creases lines. The soft material at hinge part (creases lines) subjected to the load directly when the structure folds. It should have a clear view of the mechanical properties of this material. Therefore, several mechanical tests for Tango FLX930 material are operated to calculate its mechanical properties and find the force that required to fold it
Sensitivity of orbiting JEM-EUSO to large-scale cosmic-ray anisotropies
The two main advantages of space-based observation of extreme-energy
(~eV) cosmic-rays (EECRs) over ground-based observatories are
the increased field of view, and the all-sky coverage with nearly uniform
systematics of an orbiting observatory. The former guarantees increased
statistics, whereas the latter enables a partitioning of the sky into spherical
harmonics. We have begun an investigation, using the spherical harmonic
technique, of the reach of \J\ into potential anisotropies in the
extreme-energy cosmic-ray sky-map. The technique is explained here, and
simulations are presented. The discovery of anisotropies would help to identify
the long-sought origin of EECRs.Comment: 7 pages, 6 figures. To appear in the proceedings of the Cosmic Ray
Anisotropy Workshop, Madison Wisconsin, September 201
Fisher choice may increase prevalence of green turtle fibropapillomatosis disease
This document is protected by copyright and was first published by Frontiers. All rights reserved. It is reproduced with permission.Open access journalDisease in wildlife populations is often controlled through culling. But when healthy individuals are removed and diseased individuals are left in the population, it is anticipated that prevalence of disease increases. Although this scenario is presumably common in exploited populations where infected individuals are less marketable, it is not widely reported in the literature. We describe this scenario in a marine turtle fishery in the Turks and Caicos Islands (TCI), where green turtles are harvested for local consumption. During a 2-year period, we recorded the occurrence of fibropapillomatosis (FP) disease in green turtles (Chelonia mydas) captured during in-water surveys and compared it with that of turtles landed in the fishery. 13.4% (n = 32) of turtles captured during in-water surveys showed externally visible signs of FP. FP occurred at specific geographic locations where fishing also occurred. Despite the disease being prevalent in the size classes selected by fishers, FP was not present in any animals landed by the fishery (n = 162). The majority (61%) of fishers interviewed expressed that they had caught turtles with FP. Yet, 82% of those that had caught turtles with the disease chose to return their catch to the sea, thereby selectively harvesting healthy turtles and leaving those with the disease in the population. Our study illustrates that fisher choice may increase the prevalence of FP disease and highlights the importance of this widely neglected driver in the disease dynamics of exploited wildlife populations.Natural Environment Research Council (NERC) CASE PhD studentshi
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The ISSI international study team on the martian PBL – status report and plan
Dynamical processes in the Martian boundary layer provide the means of communication between surface ice deposits and the free atmosphere, and the means of lifting dust from the surface. The boundary layer is therefore one of the most important components of the Martian climate system. The Martian boundary layer differs from that of the Earth in that it is more strongly forced, it is deeper, and the relative importance of radiative and convective heat fluxes in the lower boundary layer can be quite different. In order to understand the Martian boundary layer, a combination of theoretical, modeling and observational studies are necessary. Interactions between theorists, modelers, and observational scientists are needed to make progress and to provide a basis for analysis of data expected from Phoenix, Mars Science Laboratory, ExoMars and other future landed missions (such as a surface network mission), or missions such as balloons or other aircraft operating in the neutral atmosphere. The prime goal of this project under the auspices of the International Space Science Institute (ISSI) is to review and assess the current knowledge and understanding of Martian planetary boundary layer and its interactions with the surface and free atmosphere. We aim to promote international communication and collaboration to enhance the rate of acquisition of knowledge and understanding. This will be achieved through an International Study Team and publication of overview papers and individual reports on recent advances in this area
Dusty Plasma Correlation Function Experiment
Dust particles immersed within a plasma environment, such as those in
protostellar clouds, planetary rings or cometary environments, will acquire an
electric charge. If the ratio of the inter-particle potential energy to the
average kinetic energy is high enough the particles will form either a "liquid"
structure with short-range ordering or a crystalline structure with long range
ordering. Many experiments have been conducted over the past several years on
such colloidal plasmas to discover the nature of the crystals formed, but more
work is needed to fully understand these complex colloidal systems. Most
previous experiments have employed monodisperse spheres to form Coulomb
crystals. However, in nature (as well as in most plasma processing
environments) the distribution of particle sizes is more randomized and
disperse. This paper reports experiments which were carried out in a GEC rf
reference cell modified for use as a dusty plasma system, using varying sizes
of particles to determine the manner in which the correlation function depends
upon the overall dust grain size distribution. (The correlation function
determines the overall crystalline structure of the lattice.) Two dimensional
plasma crystals were formed of assorted glass spheres with specific size
distributions in an argon plasma. Using various optical techniques, the pair
correlation function was determined and compared to those calculated
numerically.Comment: 6 pages, Presented at COSPAR '0
A Sensitivity Study of the Enceladus Torus
We have developed a homogeneous model of physical chemistry to investigate
the neutral-dominated, water-based Enceladus torus. Electrons are treated as
the summation of two isotropic Maxwellian distributionsa thermal component
and a hot component. The effects of electron impact, electron recombination,
charge exchange, and photochemistry are included. The mass source is neutral
HO, and a rigidly-corotating magnetosphere introduces energy via pickup of
freshly-ionized neutrals. A small fraction of energy is also input by Coulomb
collisions with a small population ( 1%) of supra-thermal electrons. Mass
and energy are lost due to radial diffusion, escaping fast neutrals produced by
charge exchange and recombination, and a small amount of radiative cooling. We
explore a constrained parameter space spanned by water source rate, ion radial
diffusion, hot-electron temperature, and hot-electron density. The key findings
are: (1) radial transport must take longer than 12 days; (2) water is input at
a rate of 100--180 kg s; (3) hot electrons have energies between 100 and
250 eV; (4) neutrals dominate ions by a ratio of 40:1 and continue to dominate
even when thermal electrons have temperatures as high as 5 eV; (5)
hot electrons do not exceed 1% of the total electron population within the
torus; (6) if hot electrons alone drive the observed longitudinal variation in
thermal electron density, then they also drive a significant variation in ion
composition.Comment: 9 pages text, 3 tables, 9 figure
Carbonation of surface protected concrete
Concrete structures are exposed to carbonation that may cause rapid decay, shortening their service life and raising maintenance and repair costs. Carbonation lowers the alkalinity of the concrete depassivating the steel reinforcement. Two limit states can be identified with regard to service life. The first limit state ends when the steel is depassivated. The second limit state is based on cracking of the concrete cover due
to oxides generated during corrosion. The service life includes a certain propagation period of corrosion during which the cross-sectional area of steel is progressively decreased, the bond between steel and concrete is reduced and the effective cross-sectional area of concrete is diminished due to spalling of the cover.
Surface treatment is commonly used to improve the resistance of concrete to carbonation. A barrier is formed retarding the carbonation reactions in the interior of the concrete. In this study surface protected
concretes were compared with non-protected concretes. The used surface protected concretes presented generally lower carbonation diffusion coefficients than the non-protected concretes. The use of epoxy
resin showed better protection than the use of acrylic and siloxane resins. The composition of the concretes is an important factor affecting the diffusion of carbonation. The influence of the water–cement ratio was very important. The carbonation diffusion coefficients increased with the water–cement ratio. The prescriptive methodology is not a guarantee to obtain the desired service lives of 50 or 100 years. The desired services lives were only obtained with the use of surface protection treatments
Extracting non-linear integrate-and-fire models from experimental data using dynamic I–V curves
The dynamic I–V curve method was recently introduced for the efficient experimental generation of reduced neuron models. The method extracts the response properties of a neuron while it is subject to a naturalistic stimulus that mimics in vivo-like fluctuating synaptic drive. The resulting history-dependent, transmembrane current is then projected onto a one-dimensional current–voltage relation that provides the basis for a tractable non-linear integrate-and-fire model. An attractive feature of the method is that it can be used in spike-triggered mode to quantify the distinct patterns of post-spike refractoriness seen in different classes of cortical neuron. The method is first illustrated using a conductance-based model and is then applied experimentally to generate reduced models of cortical layer-5 pyramidal cells and interneurons, in injected-current and injected- conductance protocols. The resulting low-dimensional neuron models—of the refractory exponential integrate-and-fire type—provide highly accurate predictions for spike-times. The method therefore provides a useful tool for the construction of tractable models and rapid experimental classification of cortical neurons
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