Mechanics of musculoskeletal repair devices

This paper applies the mechanics of engineering science and materials to the understanding of clinical devices used in Orthopaedics and Trauma. The rigidity of devices is described to be a function of material stiffness and its geometry relative to the loading axes. Structures are more rigid under loads that are applied along their long axes and are more flexible under bending and torsion, which increases with length. This may be applied to an individual plate, screw or bone and to the entire construct. Increasing the thickness of a plate greatly increases rigidity as a third power relationship exists between these variables. Similarly, increasing the diameter of a rod increases its rigidity by a fourth power relationship. A hollow cylindrical cross-section, as found in long bones, provides the most effective rigidity to weight ratio when complex stresses are applied. This paper provides examples to reinforce basic structural mechanics applied to medical devices

Quantifying Aphid Predation Rates of Generalist Predators in the Field

The community of predators within agroecosystems has the potential to restrict aphid populations, especially early in the season before exponential increases in density and prior to the arrival of specialist natural enemies. Although direct observations of predation, laboratory feeding trials and manipulative field studies have been used to estimate levels of biological control exerted by different species (or potentially negative interactions between them), it is often difficult to extrapolate results to naturally occurring interactions in the field. Over 100 investigations have utilized gut-content analysis to estimate aphid predation rates by predators. Throughout the last century, gut dissection, which enables the visual identification of aphid body parts, has been used in over 50% of studies although accurate identification and quantification of predation is difficult. Other techniques have included radio-labelling of prey, dissection of faecal samples, electrophoresis, stable isotope analysis and use of polyclonal antisera. In recent studies of invertebrate predation, monoclonal antibodies have been the most frequently applied technique but advances in molecular biology have enabled the detection of species-specific DNA sequences. The use of these applications to quantify predation by aphidophagous predators will be reviewed, with emphasis on potential sources of error and difficulties of quantitative interpretation. Despite the considerable focus currently directed towards molecular approaches, antibody-based techniques are likely to remain an important tool for studying predation rates of pests in the field, especially when antibodies have already been developed. However, the study of multiple predation events within complex generalist predator food webs is only likely through the detection of species-specific DNA sequences using molecular techniques

Development and Application of Operational Techniques for the Inventory and Monitoring of Resources and Uses for the Texas Coastal Zone

There are no author-identified significant results in this report

Spectrophotometric analysis of ternary uranyl systems to replace tri-N-butyl phosphate (TBP) in used fuel reprocessing

In this report, the interaction of monoamide/diamide and monoamide/diglycolamide mixtures with UO2+2 are investigated in pH = 1 methanolic nitric acid media. These monoamides include N,N-dimethylacetamide (DMAA), N,N-diethylacetamide (DEAA), N,N-dibutylacetamide (DBAA) and N,N-dibutylbutanamide (DBBA). N,N,N′N′-tetraethylmalonamide (TEMA) and N,N,N′,N′-tetraethyldiglycolamide (TEDGA), which were chosen as model diamides and diglycolamides, respectively. Complex stability constants for each ligand were modelled using the Stability Quotients Using Absorbance Data program using UV–visible data. Complex stoichiometry of ligand mixtures was determined using Job plots and UV–Vis spectrometry. Monoamides were confirmed to produce only disolvate complexes with UO2+2 in solution. The log10(K) values for monoamides were found to be independent of amine-side chain length, but were slightly dependent on the carbonyl-side chain length. TEDGA was found to produce multiple uranyl complexes in solution. Job plot data indicated that the uranyl cation strongly prefers to bond either only with the monoamide or diamide in ternary monoamide–diamide–UO2 systems. Monoamide–diglycolamide–UO2 systems were more complicated, with Job plot data indicating the potential for multiple ternary species being present is dependent on the monoamide structure

Development and application of operational techniques for the inventory and monitoring of resources and uses for the Texas coastal zone

The author has identified the following significant results. Four LANDSAT scenes were analyzed for the Harbor Island area test sites to produce land cover and land use maps using both image interpretation and computer-assisted techniques. When evaluated against aerial photography, the mean accuracy for three scenes was 84% for the image interpretation product and 62% for the computer-assisted classification maps. Analysis of the fourth scene was not completed using the image interpretation technique, because of poor quality, false color composite, but was available from the computer technique. Preliminary results indicate that these LANDSAT products can be applied to a variety of planning and management activities in the Texas coastal zone

What do young athletes implicitly understand about psychological skills?

One reason sport psychologists teach psychological skills is to enhance performance in sport; but the value of psychological skills for young athletes is questionable because of the qualitative and quantitative differences between children and adults in their understanding of abstract concepts such as mental skills. To teach these skills effectively to young athletes, sport psychologists need to appreciate what young athletes implicitly understand about such skills because maturational (e.g., cognitive, social) and environmental (e.g., coaches) factors can influence the progressive development of children and youth. In the present qualitative study, we explored young athletes’ (aged 10–15 years) understanding of four basic psychological skills: goal setting, mental imagery, self-talk, and relaxation. Young athletes (n = 118: 75 males and 43 females) completed an open-ended questionnaire to report their understanding of these four basic psychological skills. Compared with the older youth athletes, the younger youth athletes were less able to explain the meaning of each psychological skill. Goal setting and mental imagery were better understood than self-talk and relaxation. Based on these findings, sport psychologists should consider adapting interventions and psychoeducational programs to match young athletes’ age and developmental level

Quantification of Bt-endotoxin exposure pathways in carabid food webs across multiple transgenic events

Despite the reported specificity of Bacillus thuringiensis proteins against target pests, a number of studies have indicated that the uptake of Bt-endotoxins from bioengineered crops could have negative effects on natural enemies. It is therefore essential to quantify exposure pathways in non-target arthropod food webs across multiple transgenic events. Adult ground beetles (Coleoptera: Carabidae) were collected from transgenic corn fields expressing lepidopteran-specific Cry1Ab, coleopteran-specific Cry3Bb1, and both Cry1Ab and Cry3Bb1 (stacked event), as well as a non-transgenic isoline. Carabid gut-contents were screened for Cry1Ab Bt-endotoxin using enzyme-linked immunosorbent assay. Significant numbers of carabids tested positive for Cry1Ab from the lepidopteran-specific field: Harpalus pensylvanicus (39%, 25 of 64), Stenolophus comma (4%, 6 of 136), Cratacanthus dubius (50%, 1 of 2), Clivina bipustulata (50%, 1 of 2), and Cyclotrachelus sodalis (20%, 1 of 5). The highest proportion of Bt-endotoxin uptake was 4–6 weeks postanthesis. Only one species, H. pensylvanicus (5%, 4 of 75), screened positive for Cry1Ab from the stacked line, despite similar expression of this endotoxin in plant tissue harvested from both lines. This difference in Cry1Ab uptake could be due to changes in the non-target food web or differential rates of Bt-endotoxin decay between genetic events. This study has quantified the differential uptake of Cry1Ab Bt-endotoxin by the carabid community across multiple transgenic events, thus forming the framework for future risk-assessment of transgenic crops

\u3ci\u3eBacillus thuringiensis\u3c/i\u3e: Transgenic Crops

Bacillus thuringiensis (Bt) crops, genetically modified to express insecticidal toxins that target key pests of corn, cotton, rice, potato, and other crops, have been rapidly adopted and have become dominant fixtures in agroecosystems throughout the world. Due to the constitutive nature of Bt toxin expression, insecticidal proteins may be found in nearly all plant tissues, presenting multiple sources for Bt toxins to enter the environment, thus creating complex direct and indirect pathways for non-target organisms to be exposed to insecticidal proteins. The environmental impacts of Bt crops have been widely debated, although both benefits and risks do exist. Benefits of Bt crop adoption include reduced risks to non-target organisms when compared with conventional spray applications of insecticides, as well as economic savings to growers and increased global food security. Conversely, impacts on non-target organisms, presence in the human food supply, pleiotropic effects of genetic transformation, and gene escape to wild plant populations are all considered as viable risks of Bt technology. To address the potential risks of Bt crop technology, proposed approaches to the environmental management of Bt crops are discussed, including within-plant modifications, reduction in Bt toxin and transgene escape, and large-scale integration into integrated pest and resistance management programs. Additionally, continued study of the effects of Bt toxins on non-target organisms at multiple tiers is necessary for intelligent use of this valuable pest management tool. The global area planted to Bt crops is expanding, and new Bt products and combinations are in various stages of development. Although Bt technology may offer an environmentally superior alternative to many insecticide applications, further risk assessment research addressing the impacts of Bt crops on agroecosystem function are needed to promote environmental safety

Comparative Genetic Studies of Native and Introduced Coccinellidae in North America

During the past four decades, several species of aphidophagous Coccinellidae became established in North America, including Coccinella septempunctata, Harmonia axyridis, Hippodamia variegata, and Propylea quatuordecimpunctata. After their establishment, unknown circumstances favoured a rapid increase in population densities and distribution of H. axyridis and C. septempunctata at localities hundreds and thousands of kilometers from their release sites. Propylea quatuordecimpunctata and Hippodamia variegata have spread more slowly after becoming established in northeastern North America. Comparative studies based upon allozyme variation in these four introduced species and in six native North American species of ladybird beetles revealed no significant differences in genetic diversities. Genetic variation, assessed by allelic diversity and heterozygosity, was uncorrelated with the establishment and spread of these predatory species in North America. All ladybirds studied show a remarkable degree of dispersion with little detectable population subdivision