27,025 research outputs found
The prevalence, influential factors and mechanisms of relative age effects in UK Rugby League.
Relative age effects (RAEs), reflecting observed inequalities in participation and attainment as a result of annual age-grouping policies in youth sport, are common in most team sports. The aims of this study were to determine if and when RAEs become apparent in Rugby League, determine how influential variables (e.g., gender) lead and clarify whether player retention at junior representative levels can explain persistent RAEs. Player data were collected for the male and female community games ranging from Under 7s to Senior (N=15,060) levels, junior representative selections (i.e., Regional) and professional players (N=298). Chi-square analyses found significant (P<0.05) uneven birth date distributions beginning at the earliest stages of the game and throughout into senior professionals. In junior representative selections, 47.0% of Regional and 55.7% of National representative players were born in Quartile 1, with RAE risk increasing with performance level. Gender and nationality were also found to moderate RAE risk. When tracking representative juniors, over 50% were retained for similar competition the following season. Findings clearly demonstrate that RAEs exist throughout Rugby League with early selection, performance level and retention processes, appearing to be key contributing factors responsible for RAE persistence
Study of Cypermethrin Cytogenesis effects on Human Lymphocytes Using In-Vitro Techniques
The Cytogenetic effects of Cypermethrin a synthetic pyrithroid insecticide was investigated on human lymphocytes cultured in-vitro. Utilizing the trypan blue dye exclusion technique assay the LC50 of cypermethrin was found to be 36 uM. Based on LC50 value, hypermethrin was found to be low toxic to lymphocyte culture. Cypermethrin showed an increase in the frequency of chromosomal aberrations and found to be significant. Karyotype analysis revealed more satellite associations and chromosomal breaks in cypermethrin treated samples. Low-doses of the pesticide also induced singlestrand breaks in the DNA as assessed by comet assay. The pesticide caused increase in the comet tail length with increase in pesticide concentration, implicating genotoxicity in somatic cells. It is concluded that In vitro assays could give important information of the mechanism of toxicity at low dosages and impact on genetic material of human origi
Numerical Simulations of Dynamos Generated in Spherical Couette Flows
We numerically investigate the efficiency of a spherical Couette flow at
generating a self-sustained magnetic field. No dynamo action occurs for
axisymmetric flow while we always found a dynamo when non-axisymmetric
hydrodynamical instabilities are excited. Without rotation of the outer sphere,
typical critical magnetic Reynolds numbers are of the order of a few
thousands. They increase as the mechanical forcing imposed by the inner core on
the flow increases (Reynolds number ). Namely, no dynamo is found if the
magnetic Prandtl number is less than a critical value .
Oscillating quadrupolar dynamos are present in the vicinity of the dynamo
onset. Saturated magnetic fields obtained in supercritical regimes (either
or ) correspond to the equipartition between magnetic and
kinetic energies. A global rotation of the system (Ekman numbers ) yields to a slight decrease (factor 2) of the critical magnetic
Prandtl number, but we find a peculiar regime where dynamo action may be
obtained for relatively low magnetic Reynolds numbers (). In this
dynamical regime (Rossby number , spheres in opposite direction) at
a moderate Ekman number (), a enhanced shear layer around the inner
core might explain the decrease of the dynamo threshold. For lower
() this internal shear layer becomes unstable, leading to small
scales fluctuations, and the favorable dynamo regime is lost. We also model the
effect of ferromagnetic boundary conditions. Their presence have only a small
impact on the dynamo onset but clearly enhance the saturated magnetic field in
the ferromagnetic parts. Implications for experimental studies are discussed
Tissue ablation with 100-fs and 200-ps laser pulses
The authors used water and human skin tissue to compare the surgical potential of 100-fs and 200-ps laser pulses. For investigation of threshold behavior of 100-fs and 200-ps pulses, the authors use water as a model for tissue. In addition to having a lower threshold, they find that energy deposition is much more consistent with 100-fs pulses. The authors also compared 100-fs and 200-ps laser pulse effects on the surface and in the bulk of human skin tissue. On the surface, pulses with 100-fs and 200-ps duration leave similar size ablation regions. In the bulk both 100-fs and 200-ps pulses produce cavities, however, 100-fs pulses result in a smaller cavity size. On both the surface and in the bulk 100-fs pulses show less collateral tissue damage than 200-ps pulses.published_or_final_versio
Reasoning about goal-directed real-time teleo-reactive programs
The teleo-reactive programming model is a high-level approach to developing real-time systems that supports hierarchical composition and durative actions. The model is different from frameworks such as action systems, timed automata and TLA+, and allows programs to be more compact and descriptive of their intended behaviour. Teleo-reactive programs are particularly useful for implementing controllers for autonomous agents that must react robustly to their dynamically changing environments. In this paper, we develop a real-time logic that is based on Duration Calculus and use this logic to formalise the semantics of teleo-reactive programs. We develop rely/guarantee rules that facilitate reasoning about a program and its environment in a compositional manner. We present several theorems for simplifying proofs of teleo-reactive programs and present a partially mechanised method for proving progress properties of goal-directed agents. © 2013 British Computer Society
Few-Shot Single-View 3-D Object Reconstruction with Compositional Priors
The impressive performance of deep convolutional neural networks in
single-view 3D reconstruction suggests that these models perform non-trivial
reasoning about the 3D structure of the output space. However, recent work has
challenged this belief, showing that complex encoder-decoder architectures
perform similarly to nearest-neighbor baselines or simple linear decoder models
that exploit large amounts of per category data in standard benchmarks. On the
other hand settings where 3D shape must be inferred for new categories with few
examples are more natural and require models that generalize about shapes. In
this work we demonstrate experimentally that naive baselines do not apply when
the goal is to learn to reconstruct novel objects using very few examples, and
that in a \emph{few-shot} learning setting, the network must learn concepts
that can be applied to new categories, avoiding rote memorization. To address
deficiencies in existing approaches to this problem, we propose three
approaches that efficiently integrate a class prior into a 3D reconstruction
model, allowing to account for intra-class variability and imposing an implicit
compositional structure that the model should learn. Experiments on the popular
ShapeNet database demonstrate that our method significantly outperform existing
baselines on this task in the few-shot setting
Energy-Efficient UAV Trajectories: Simulation vs Emulation
This paper uses an emulator to verify an energy-efficient trajectory for an unmanned aerial vehicle (UAV) acting as a portable access point (PAP) to serve a set of users. Specifically, we use the Common Open Research Emulator (CORE), and Extendable Mobile Ad-hoc Network Emulator (EMANE), which allow us to take theoretical assumptions regarding data transfer rates and transmission characteristics and test them in the virtualized wireless networking setting the two tools provide us. The optimal fly-hover-communicate trajectory that maximizes the system's energy efficiency is obtained using a circle-packing algorithm. The CORE-EMANE emulator results match the simulated results, thereby verifying the practicality of the obtained trajectory solution
Approche expérimentale de l’utilisation de glyphosate dans le contrôle de Melaleuca quinquenervia (Myrtaceae), une espèce envahissante dans la réserve communautaire de la forêt d’Analalava-Foulpointe (Madagascar)
Le Niaouli Melaleuca quinquenervia est une des espèces envahissantes les plus agressives à Madagascar et elle gagne de plus en plus de terrain en colonisant des milieux marécageux autour de la Nouvelle Aire Protégée de la forêt d’Analalava Foulpointe. L’inquiétude sur son envahissement augmente, et même si l’éradication paraît d’ores et déjà impossible, il convient de trouver dès maintenant une solution efficace pour contrôler son expansion jusqu’à l’aire protégée. Seul le contrôle chimique peut être envisagé pour cette espèce qui fait preuve d’une grande résilience face à la coupe et au feu. Cette étude vise à identifier le meilleur protocole d’utilisation de glyphosate dans le contrôle de l’invasion de M. quinquenervia dans la forêt d’Analalava Foulpointe. Cinq solutions de glyphosate de concentrations différentes, S1 (0 g /l), S2 (90 g/l), S3 (180 g/l), S4 (270g/l) et S5 (360g/l) ont été testées sur 200 individus, soit 40 individus pour chaque solution. Les solutions de glyphosate sur la surface coupée du tronc d’un individu ont été appliquées soit au pinceau, soit au pulvérisateur. Des suivis ont été faits pendant quatre mois, observant l’état des individus traités et l’impact du traitement sur les plantes ligneuses environnantes. La plupart des individus traités sont morts, présentant plus de 85% de taux de mortalité. Certaines plantes non ciblées ont été touchées (19 % des individus recensés), quel que soit la concentration en ingrédient actif de glyphosate et l’équipement utilisés. De cette expérience, le meilleur protocole d’utilisation de glyphosate est la concentration de 90 g/l de l’ingrédient actif appliquée sur la surface coupée d’un tronc traité en utilisant un pinceau.Melaleuca quinquenervia, one of the most aggressive invasive species in Madagascar, gains more and more ground and colonizes wetland environments around the New Protected Area of the Analalava forest in Foulpointe. Concerns over its invasion increase and even if eradication seems already impossible, we must now find an effective solution to control its expansion towards the protected area. Only chemical control may be considered for this species, given its resilience to cutting and fire. This study aims at identifying the best protocol for the use of glyphosate in controlling the invasion of M. quinquenervia in the Analalava forest in Foulpointe. Five solutions of different concentrations of glyphosate, S1 (0 g/l), S2 (90 g/l), S3 (180 g/l), S4 (270 g/l), and S5 (360 g/l) were tested on 200 individuals, or 40 individuals for each solution. Glyphosate solutions were applied on the cut surface of the trunk of an individual using either a brush or a sprayer. The controls were done for four months by observing the status on treated individuals and the impacts of the treatment on non - target plants. Most individuals treated are dead, showing an 85 % rate mortality. Some non - target plants were affected (19 % of the surveyed ones), regardless of the concentration of active ingredient glyphosate and of the equipment used. From these experiments, the best protocol for the glyphosate use is a concentration of 90 g/l of the active ingredient applied to the cut surface of the trunk treaty using a brush
Free proline, soluble sugars and soluble proteins concentration as affected by salt stress in two sugarcane (Saccharum sp.) cultivars differing in their salt tolerance
Salt stress is one of the environmental stresses which affect negatively the agricultural production of the world. In this study, the effects of salt stress on free proline, soluble sugars and soluble proteins accumulation were investigated in two sugarcane (Saccharum sp.) cultivars: CP66-346 (salt- tolerant) and CP65-357 (salt-sensitive). Young plants of these cultivars were exposed, in a hydroponic system, to four concentrations of NaCl (0, 17, 34 and 68 mM). These concentrations correspond to an electric conductivity of 1; 2.83; 4.26 and 6.63 mS/cm, respectively. Free proline, soluble sugars and proteins accumulation were quantified after 2 weeks of stress. Proline and soluble sugars concentrations increased significantly in leaves and roots under salinity. Furthermore, NaCl caused an increase in soluble proteins concentration in leaves and roots of the tolerant cultivar CP66-346 and a decrease in leaves and roots of the sensitive CP65-357. Salttolerant CP66-346 plants accumulated more soluble sugars in leaves than CP65-357, while both cultivars accumulated similar quantities of proline in leaves. These results provided evidence that soluble sugars could contribute mainly to counteract the negative water potential of the outside medium and that protein synthesis stimulation was implicated in sugarcane salt tolerance. Proline appeared as a symptom in salt-stressed sugarcane plants rather than as an indicator of tolerance.Keywords: Sugarcane, Saccharum sp., proline, soluble sugars, soluble proteins, salt-toleranc
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