902 research outputs found
Review of \u3ci\u3eDamselflies of Texas: A Field Guide.\u3c/i\u3e By John C. Abbott.
Well-produced field guides are always in demand, and Damselflies of Texas is one such. This compact, camera-bag-friendly compendium displays each of the 77 species known to occur, or that have been historically documented, in the state. The guide\u27s first 50 pages are introductory and full of useful detail. There follows a large section devoted to species descriptions and a set of appendices
Exercise-based injury prevention for community-level adolescent pace bowlers
Sporting injuries are on the rise and wide-scale injury prevention strategies are needed in community-level sport. Research indicates that community-level adolescent pace bowlers could benefit from exercise-based injury prevention programs (IPPs), however, a specific program for this group has not been developed. The primary aim of this thesis was to therefore develop a specific IPP for community-level adolescent pace bowlers and investigate if this program could modify risk factors for injury in this population.
The Translating Research into Injury Prevention Practice (TRIPP) framework guided the progression of studies in this thesis. In Chapter 2, risk factors for injury in adolescent pace bowlers were systematically reviewed. The review included all experimental and observational studies that reported risk factors for non-contact injuries in pace bowlers aged 12-19 years. The Newcastle-Ottawa Quality Assessment Scale was used to assess risk of bias. In Chapter 3 the various barriers and facilitators to program implementation at the community-level were identified and used to guide the development of an IPP that was appropriate for community-level adolescent pace bowlers. In Chapters 4 and 5 a cluster-randomised controlled trial was employed to examine the efficacy of this IPP to modify neuromuscular risk factors and alter bowling kinematics. Eligible pace bowlers from eight cricket organisations (clusters) were recruited and then randomised into either an intervention group or control group. The intervention group completed an eight-week IPP while the control continued their normal cricket activity. Either side of the eight-week intervention period all participants attend a baseline and follow-up session where measures of muscle strength, muscle endurance, dynamic neuromuscular control and bowling kinematics were assessed. The treatment effect of the IPP was estimated with linear mixed models.
Chapter 2 identified several potentially modifiable risk factors for injury in adolescent pace bowlers and these included; excessive lateral trunk flexion while bowling, kinematics of pelvis and hip while bowling, reduced trunk endurance, and poor lumbo-pelvic-hip movement control. There were conflicting results amongst the studies which investigated the mixed technique, bowling workload, and quadratus lumborum asymmetry. Among the five cross-sectional studies, risk of bias was high and very high. Of the 11 cohort studies, three were rated as low risk of bias and eight as high risk of bias. With the information gathered in Chapter 2, an exercise program to modify risk factors was developed in Chapter 3. The program included exercises to improve; eccentric strength of the external shoulder rotators, hip adductor strength, eccentric hamstring strength, dynamic neuromuscular control of the lumbo-pelvic region and lower-limbs, and trunk extensor endurance. Chapter 3 also considered the various facilitators to program implementation at the community-level, and therefore included exercises that were; simple to learn, non-reliant on expensive equipment, and time-efficient. In Chapter 4 the efficacy of this newly developed IPP to modify neuromuscular risk factors was assessed. There were significant treatment effects (estimated marginal mean with 95% confidence intervals) favouring the intervention group for; isokinetic shoulder strength (90°/s) (0.05 Newton meters per kilogram (N.m/kg); 0.02 to 0.09), isokinetic hamstring strength (60°/s) (0.32 N.m/kg; 0.13 to 0.50), hip adductor strength dominant side (0.40 N.m/kg; 0.26 to 0.55) and non-dominant side (0.33 N.m/kg; 0.20 to 0.47), Star Excursion Balance Test reach distance dominant side (3.80 percent of leg length (%LL); 1.63 to 6.04) and non-dominant side (3.60 %LL; 1.43 to 5.78), and back endurance (20.4 seconds; 4.80 to 36.0). No differences were observed for isokinetic shoulder strength (180°/s) (p=0.09), isokinetic hamstring strength (180°/s) (p=0.07), lumbo-pelvic stability (p=0.90), and single leg squat knee valgus angle (dominant p=0.06, non-dominant p=0.15). In Chapter 5 there were significant treatment effects favouring the intervention group for shoulder counter-rotation (-3.75°; -7.19 to -0.32) and lateral trunk flexion relative to pelvis (-2.24°; -3.97 to -0.52). There were however, no significant between-group differences for; global angles of lateral trunk flexion at front foot contact (FFC) (1.2°; -2.5 to 4.8), global angles of lateral trunk flexion ball release (BR) (-0.5°; -3.0 to 2.0), pelvis rotation FFC (0.9°; -4.0 to 2.2), pelvis rotation BR (-1.1°; -5.7 to 3.6), front hip angle FFC (1.6°; -3.6 to 6.7), front hip angle BR (-1.6°; -5.0 to 1.9), front knee angle FFC (-1.1°; -4.5 to 2.3), front knee angle BR (1.7°; -5.6 to 9.1), or ball velocity (1.1 km/h; -7.5 to 9.7).
This thesis demonstrates that the TRIPP framework can used to successfully guide the process of injury prevention in community-level adolescent pace bowlers. The IPP in this thesis was also able to modify several neuromuscular and biomechanical risk factors, however a number of measures were not altered. Future research is needed to refine the current IPP and investigate if it can reduce injury risk in a real-world setting
A simple two-module problem to exemplify building-block assembly under crossover
Theoretically and empirically it is clear that a genetic algorithm with crossover will outperform a genetic algorithm without crossover in some fitness landscapes, and vice versa in other landscapes. Despite an extensive literature on the subject, and recent proofs of a principled distinction in the abilities of crossover and non-crossover algorithms for a particular theoretical landscape, building general intuitions about when and why crossover performs well when it does is a different matter. In particular, the proposal that crossover might enable the assembly of good building-blocks has been difficult to verify despite many attempts at idealized building-block landscapes. Here we show the first example of a two-module problem that shows a principled advantage for cross-over. This allows us to understand building-block assembly under crossover quite straightforwardly and build intuition about more general landscape classes favoring crossover or disfavoring it
Regionalized state training academies: a better use of law enforcement training resources
Examines the costs associated with different training academy models, single jurisdiction or regional
Natural Control and Spatial Distribution of Fall Armyworm (Spodoptera Frugiperda) Within Louisiana Corn Fields.
Spatial distribution of fall armyworm, Spodoptera frugiperda (J. E. Smith), (FAW) was studied in cornfields at the St. Gabriel Experiment Station in Louisiana from 1981 to 1983. Corn plants were sampled and FAW larvae counted and divided into categories of small, medium, and large for both single plant and five plant samples. Count data for each category by date were then fitted to Poisson, negative binomial, and Neyman type A distributions. Means and variances for each category by date were also analyzed with the Taylor Power law. Small larvae were more aggregated than the medium larvae which were more aggregated than the large larvae. One plant samples were more efficient than five plant samples. Prevalence of a nuclear polyhedrosis virus (NPV) was studied in 1981 and 1982 at St. Gabriel and in 1982 and 1983 at a private dairy farm 6 km east of Hammond, Louisiana. Information on FAW populations, climate, and virus prevalence were analyzed by multiple regression and regression models made for each location and for combined data. Important factors at St. Gabriel included corn height, number of larvae per plant, and temperature variables. Important factors at Hammond were all environmental--temperature, degree day, rain, and solar radiation. The most important variable for regression models made from the combined data was number of larvae per plant. Parasitism of FAW larvae by three species of parasite--Cotesia (Apanteles) marginiventris, Rogas laphygmae, and Chelonus sp.--was studied concurrently with NPV epizootiology. Regression models were constructed for parasitism by each species using the combined data sets. The R(\u272) values for the models were low, not exceeding 0.40. The only variable to appear in all models was corn height. The F(,1) offspring of larvae collected in St. Gabriel in 1981 and Hammond in 1982 were tested by bioassay against the locally occurring NPV. Heterogeneity with respect to the NPV increased with time. F(,1) larvae of parents surviving both NPV applications and naturally occurring NPV selection often gave bioassay results too heterogeneous to fit the probit model. Immigration of susceptible individuals was the most likely cause of the heterogeneity
Structure and morphology of nanocomposites
Since the pioneering work on nylon/clay nanocotnposites performed by Toyota in the early 1990's, where improvements in mechanical properties of the nylon polymer were reported, there has been a great deal of research focussed on blends of thermoplastic polymers and nanoparticles. However, there has been relatively little work exploring the incorporation of nanoparticles into thermosetting polymers. Of the work that has been conducted, full exfoliation, or separation of the nanoparticles required for mechanical and fire retardancy property enhancements, has been very difficult to achieve. Low resin viscosity and the application of ultrasonic vibration are known to be key factors in facilitating exfoliation in thermosetting nanocomposites. The Quickstep process is an out-of autoclave technique that utilises balanced pressure and liquid heating and cooling to cure composite components. As a result, cure cycle times are reduced, from several hours to just a few minutes. The Quickstep process is a recent Australian innovation and there are currently three Quickstep plants worldwide, located at Deakin University, Toyota, Japan and the University of Manchester, UK. Quickstep Technology has the potential to produce commercially ready thermosetting nanocomposites, by curing the matrix together with the nano-clay particles. The combination of rapid temperature ramp rates, leading to low resin viscosity, and the use of vibration through the fluid filled bladder, give the process a unique approach to manufacturing these materials. Results from sample characterisation and mechanical tests will be presented, to compare the mechanical properties of the thermoset nanocomposites to conventional composites. These mechanical properties will be correlated with various morphologies produced by modifying the processing parameters
Soil Modification as a Restoration Tool to Reduce Old World Bluestems in Texas Coastal Prairies
Nonnative Old World bluestem (OWB) grasses (e.g., Bothriochloas, Dichanthium spp.) have become dominant throughout the southern and central Great Plains, altering native plant communities and habitat quality for wildlife. Although conventional management strategies have not resulted in elimination or reduction of these grasses, modifying soil conditions to favor native plants may be an alternative restoration tool. We examined efficacy of 10 soil modification treatments (soil disturbance alone, pH increase, pH reduction, carbon addition, addition of soil mycorrhizae, and each combined with seeding of native vegetation) on 60 research plots at the Welder Wildlife Foundation Refuge in southern Texas in summer 2011. We sampled soil chemistry, vegetation density, cover, and height, and abundance of soil, terrestrial, and flying arthropods four and eight weeks after initial treatments. Severe drought prevented plant growth on treated plots and may have decreased the efficacy of soil treatments, especially pH reduction. As such, we compared vegetation and arthropod communities only between undisturbed plots dominated by native vegetation and dominated by OWBs. Species richness of vegetation was higher on plots dominated by native vegetation (4.4 species/m2, SE = 0.6) compared to plots dominated by OWBs (2 species/m2, SE = 0.5). Arthropods were more abundant in native vegetation (175 individuals/m2, SE = 4.1) relative to OWB-dominated plant communities (41, 1.3). Isopods and ants were the most abundant groups overall, although some of these taxa are nonnative. We will continue to collect data over the next two years to explore further soil modification as a restoration tool in grasslands impacted by OWBs
Decreased Plant and Arthropod Richness in Landscapes Dominated by Old World Bluestem Grasses: Implications for Wildlife
Old World bluestem grasses (OWBs, e.g., Bothriochloa, Dichanthium spp.) have become dominant throughout the southern and central Great Plains, altering native plant communities with concomitant effects for native wildlife. We examined plant and arthropod communities in areas dominated by native plants and areas dominated by OWBs at the Welder Wildlife Refuge in southern Texas. We sampled vegetation and arthropods on research plots (6 x 9-m, 5 each) every 4 weeks during summer 2011 and 2012. We found, on average, 2 (SE=0.2) more plant species, and 12-13 (SE=1.0) more arthropod species on native plant-dominated plots compared to OWB-dominated plots. Native plant-dominated plots also had 273 (SE=18.8) more individual arthropods in 2011, but 75 (SE=16.6) fewer than OWB-dominant plots in 2012, resulting from a population explosion and crash of woodlice in native plant-dominated plots. We recorded only 1 species of herbivorous arthropod from OWB-dominated plots in 2012; native plant-dominated plots had 5-6 (SE=0.68) additional herbivore species, suggesting that increased dominance by OWBs may create cascading effects on trophic dynamics. Because many species of wildlife depend on plants and arthropods for food, these changes in species richness and abundance suggest that restoration tools are required to reduce the competitive ability of OWBs. Traditional management strategies have not successfully reduced OWBs; as part of our research, we are modifying soil properties to attempt to provide novel management strategies for landowners to increase diversity of native species and habitat quality in grasslands impacted by OWBs
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