7,545 research outputs found
Reducing Prawn-trawl Bycatch in Australia: An Overview and an Example from Queensland
Prawn trawling occurs in most states of Australia in tropical, subtropical, and temperate waters. Bycatch occurs
to some degree in all Australian trawl fisheries, and there is pressure to reduce the levels of trawl fishery bycatch. This paper gives a brief overview of the bycatch issues and
technological solutions that have been evaluated or adopted in Australian prawn-trawl fi sheries. Turtle excluder devices (TEDâs) and bycatch reduction devices (BRDâs) are
the principal solutions to bycatch in Australian prawn-trawl fisheries. This paper focuses on a major prawn-trawl fishery of northeastern Australia, and the results of
commercial use of TEDâs and BRDâs in the Queensland east coast trawl fishery are presented. New industry designs are
described, and the status of TED and BRD adoption and regulation is summarized. The implementation of technological solutions to reduce fishery bycatch is assumed generally to assist prawn-trawl fisheries within
Australia in achieving legislative requirements for minimal environmental impact and ecological sustainable development
Betti number signatures of homogeneous Poisson point processes
The Betti numbers are fundamental topological quantities that describe the
k-dimensional connectivity of an object: B_0 is the number of connected
components and B_k effectively counts the number of k-dimensional holes.
Although they are appealing natural descriptors of shape, the higher-order
Betti numbers are more difficult to compute than other measures and so have not
previously been studied per se in the context of stochastic geometry or
statistical physics.
As a mathematically tractable model, we consider the expected Betti numbers
per unit volume of Poisson-centred spheres with radius alpha. We present
results from simulations and derive analytic expressions for the low intensity,
small radius limits of Betti numbers in one, two, and three dimensions. The
algorithms and analysis depend on alpha-shapes, a construction from
computational geometry that deserves to be more widely known in the physics
community.Comment: Submitted to PRE. 11 pages, 10 figure
Human-centred design methods : developing scenarios for robot assisted play informed by user panels and field trials
Original article can be found at: http://www.sciencedirect.com/ Copyright ElsevierThis article describes the user-centred development of play scenarios for robot assisted play, as part of the multidisciplinary IROMEC1 project that develops a novel robotic toy for children with special needs. The project investigates how robotic toys can become social mediators, encouraging children with special needs to discover a range of play styles, from solitary to collaborative play (with peers, carers/teachers, parents, etc.). This article explains the developmental process of constructing relevant play scenarios for children with different special needs. Results are presented from consultation with panel of experts (therapists, teachers, parents) who advised on the play needs for the various target user groups and who helped investigate how robotic toys could be used as a play tool to assist in the childrenâs development. Examples from experimental investigations are provided which have informed the development of scenarios throughout the design process. We conclude by pointing out the potential benefit of this work to a variety of research projects and applications involving humanârobot interactions.Peer reviewe
Comparison of Space-Plant Versus Sward Plot Selection in Thickspike Wheatgrass (\u3ci\u3eElymus lanceolatus\u3c/i\u3e)
Thickspike wheatgrass (Elymus lanceolatus [Scribn. & J.G. Sm.] Gould) is an important native perennial grass species used for rangeland revegetation in North America. Plant breeding efforts relying on spaceâplant evaluations have resulted in limited improvement in this species. The purpose of this study was to characterize the performance of thickspike wheatgrass halfâsib families under spaceâplant and sward plot evaluations, estimate the correlation between measured traits in both evaluation settings, and determine the validity of selecting thickspike wheatgrass for rangeland revegetation in the nontarget environment spaceâplant plots. The study included 50 thickspike wheatgrass halfâsib families and five commercial cultivars and experimental populations which were evaluated over 3 years in spaceâplant and sward plot evaluations at a field site in Box Elder County, Utah, USA. Collected data included stand percentage, flag leaf height, and herbage dry mass. Narrowâsense heritability estimates were low to moderate (h2 \u3c 0.60) and Spearman and genetic correlation estimates among traits were also generally low to moderate. Overall, there was little evidence to suggest the use spaceâplant evaluations in thickspike wheatgrass improvement programmes
Occupational hazards, living conditions, and physical assault of sugar cane workers in KwaZulu Natal, South Africa
No Abstrac
CO-ORDINATION ANALYSIS OF LANDING STRATEGIES IN BEAM DISMOUNTS
INTRODUCTION: Landing strategies selected by female gymnasts performing somersault dismounts from the beam may be related to the availability of feedback (McNitt-Gray et al., 2001). This study aims to employ co-ordination analysis to examine how female gymnasts control dropping and landing from forward and backward somersault beam dismounts
Artificial neural networks and player recruitment in professional soccer
The aim was to objectively identify key performance indicators in professional soccer that influence outfield playersâ league status using an artificial neural network. Mean technical performance data were collected from 966 outfield playersâ (mean SD; age: 25 ± 4 yr, 1.81 ±) 90-minute performances in the English Football League. ProZoneâs MatchViewer system and online databases were used to collect data on 347 indicators assessing the total number, accuracy and consistency of passes, tackles, possessions regained, clearances and shots. Players were assigned to one of three categories based on where they went on to complete most of their match time in the following season: group 0 (n = 209 players) went on to play in a lower soccer league, group 1 (n = 637 players) remained in the Football League Championship, and group 2 (n = 120 players) consisted of players who moved up to the English Premier League. The models created correctly predicted between 61.5% and 78.8% of the playersâ league status. The model with the highest average test performance was for group 0 v 2 (U21 international caps, international caps, median tackles, percentage of first time passes unsuccessful upper quartile, maximum dribbles and possessions gained minimum) which correctly predicted 78.8% of the playersâ league status with a test error of 8.3%. To date, there has not been a published example of an objective method of predicting career trajectory in soccer. This is a significant development as it highlights the potential for machine learning to be used in the scouting and recruitment process in a professional soccer environment
Bosenova and three-body loss in a Rb-85 Bose-Einstein condensate
Collapsing Bose-Einstein condensates are rich and complex quantum systems for
which quantitative explanation by simple models has proved elusive. We present
new experimental data on the collapse of high density Rb-85 condensates with
attractive interactions and find quantitative agreement with the predictions of
the Gross-Pitaevskii equation. The collapse data and measurements of the decay
of atoms from our condensates allow us to put new limits on the value of the
Rb-85 three-body loss coefficient K_3 at small positive and negative scattering
lengths.Comment: 6 pages, 5 figure
Cold atom gravimetry with a Bose-Einstein Condensate
We present a cold atom gravimeter operating with a sample of Bose-condensed
Rubidium-87 atoms. Using a Mach-Zehnder configuration with the two arms
separated by a two-photon Bragg transition, we observe interference fringes
with a visibility of 83% at T=3 ms. We exploit large momentum transfer (LMT)
beam splitting to increase the enclosed space-time area of the interferometer
using higher-order Bragg transitions and Bloch oscillations. We also compare
fringes from condensed and thermal sources, and observe a reduced visibility of
58% for the thermal source. We suspect the loss in visibility is caused partly
by wavefront aberrations, to which the thermal source is more susceptible due
to its larger transverse momentum spread. Finally, we discuss briefly the
potential advantages of using a coherent atomic source for LMT, and present a
simple mean-field model to demonstrate that with currently available
experimental parameters, interaction-induced dephasing will not limit the
sensitivity of inertial measurements using freely-falling, coherent atomic
sources.Comment: 6 pages, 4 figures. Final version, published PR
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