Barotropic response of the global atmosphere to large-scale tropical convective forcing

Spring 1999.Also issued as author's thesis (M.S.) -- Colorado State University, 1999.Includes bibliographical references.A nonlinear shallow water model on the sphere is used to study the effect of largescale tropical convective forcing on the response of the global circulation. Both the spatial and temporal characteristics of the forcing are found to significantly affect the production of tropical and extratropical circulation anomalies. The horizontal shape and location of the convective forcing determines the strength, stability, and symmetry of the upper tropospheric response, the proportion of energy transferred into westward- and eastward-dispersing Rossby modes, and the exact direction of energy propagation. Together, these effects produce teleconnection patterns similar to those observed in the atmosphere. The strongest eastward teleconnection patterns are produced when the convective forcing is meridionally elongated and/or centered off of the Equator. The timescale of the convective forcing determines the distribution of energy into Rossby, Kelvin, and gravity-inertia waves through a filtering on the wave spectrum. An analytical solution to the divergent barotropic vorticity equation is derived to highlight this timescale filter. When the forcing timescale is long, only the longest Rossby waves, with westward group velocities, can be excited at large amplitudes. As the timescale decreases, both the shorter Rossby waves, which have eastward group velocities, and the long gravity waves can be excited. The complete response of a stratified atmosphere is then shown to depend not only on the horizontal shape and timescale of the forcing, but also on its vertical structure. Lower tropospheric convective forcing excites a much more vigorous response in the circulation than does upper tropospheric forcing. Strong cyclonic vortices, which can be likened to tropical cyclones, are generated by the unstable breakdown of the flow in the lower troposphere. The initiation locations and the direction of propagation of these vortices are determined by the horizontal shape and orientation of the convective forcing, through differences in Rossby wave energy dispersion. This reasoning provides a simple explanation for observations that tropical cyclones which form in the Western North Pacific during a "reverse monsoon trough" episode tend to track to the north or northeast (Lander 1996), as opposed to the more climatologically favored northwestward tracks of most Western North Pacific tropical storms.Sponsored by the National Oceanic and Atmospheric Administration through TOGA/COARE NA37RJ0202

Segmental Kinematic Analysis of Planovalgus Feet during Walking in Children with Cerebral Palsy

Pes planovalgus (flatfoot) is a common deformity among children with cerebral palsy. The Milwaukee Foot Model (MFM), a multi-segmental kinematic foot model, which uses radiography to align the underlying bony anatomy with reflective surface markers, was used to evaluate 20 pediatric participants (30 feet) with planovalgus secondary to cerebral palsy prior to surgery. Three-dimensional kinematics of the tibia, hindfoot, forefoot, and hallux segments are reported and compared to an age-matched control set of typically-developing children. Most results were consistent with known characteristics of the deformity and showed decreased plantar flexion of the forefoot relative to hindfoot, increased forefoot abduction, and decreased ranges of motion during push-off in the planovalgus group. Interestingly, while forefoot characteristics were uniformly distributed in a common direction in the transverse plane, there was marked variability of forefoot and hindfoot coronal plane and hindfoot transverse plane positioning. The key finding of these data was the radiographic indexing of the MFM was able to show flat feet in cerebral palsy do not always demonstrate more hindfoot eversion than the typically-developing hindfoot. The coronal plane kinematics of the hindfoot show cases planovalgus feet with the hindfoot in inversion, eversion, and neutral. Along with other metrics, the MFM can be a valuable tool for monitoring kinematic deformity, facilitating clinical decision making, and providing a quantitative analysis of surgical effects on the planovalgus foot

Gender Disparity in HIV Prevalence: A National-Level Analysis of the Association between Gender Inequality and the Feminisation of HIV/AIDS in sub-Saharan Africa

The HIV pandemic in sub-Saharan Africa is often described as undergoing a ‘feminisation’ in which female HIV prevalence exceeds that of male in most age groups and countries. However, much of the variation between countries in the female-to-male (FTM) ratio of HIV prevalence remains unexplained. This paper uses information from DHS, World Bank, UNDP and UNAIDS to identify correlates of the FTM ratio at the country level, with a focus on gender inequality. The FTM ratio is investigated overall and for two age groups. Divergent results by age suggest that the influence of particular mechanisms depend on the age group in question, with epidemiological and demographic variables in particular demonstrating strong associations with the FTM ratio for 25-49 year olds. The mechanisms influencing gender disparity in HIV prevalence between younger adults remain unclear, with few significant correlates observed for the 15-24 age group.

Data Sharing: How Much Doesn't Get Submitted to GenBank?

Funding agencies and journals require researchers to deposit DNA sequences in public databases such as GenBank when the paper is published, but how often do authors fail to do so

Enhancing evidence-based diabetes and chronic disease control among local health departments: A multi-phase dissemination study with a stepped-wedge cluster randomized trial component

Examples of Intervention Dissemination Strategies and Description. (DOCX 22 kb

Upper Extremity Joint Dynamics During Walker Assisted Gait: A Quantitative Approach Towards Rehabilitative Intervention

Background Many children with spastic diplegic cerebral palsy (CP) use anterior or posterior walkers to aid ambulation. Prolonged use may lead to upper extremity (UE) pathology later in life, including arthritis and joint contractures. Purpose This study analyzes the dynamics (kinematics and kinetics) of the shoulder (glenohumeral), elbow, and wrist joints during anterior and posterior walker use. It also examines the dynamic effects of adjusting handle height and grip rotation. Methods Ten children with CP underwent motion analysis with upper and lower extremity marker sets and six-degree-of-freedom instrumented walker handles, while using both anterior and posterior walkers. One child underwent the same analysis, with added trials for wrist derotation (adjusted axial grip rotation) and wrist plus elbow derotation (adjusted handle height). A validated kinematic and kinetic model was applied to calculate UE joint angles, joint reaction forces (JRFs), and joint reaction moments (JRMs). Results Surprisingly, no statistically significant differences in UE angles, JRFs, or JRMs were observed between anterior and posterior walkers. Wrist derotation, however, decreased the flexion JRM seen at the wrist, and elbow derotation decreased the flexion JRM seen at the elbow. Conclusion Anterior and posterior walkers produce similar UE motion and peak loading values. Wrist and elbow joint derotation alters the dynamic effects experienced by the UEs. UE motion analysis during aided gait can be useful for optimizing UE loading conditions to limit pathology later in life

A study of the anti-androgenic effects of the phthalate ester, din-butyl phthalate, on two freshwater fish species, the fathead minnow and the three-spined stickleback

For the past few years there has been increasing concern surrounding a group of chemicals known as phthalate esters. In mammals, phthalates are known antiandrogens, interfering with the production or activity of testosterone. Phthalates are ubiquitous in the aquatic environment. With recent findings suggesting that antiandrogens may be responsible for much of the endocrine disruption found in wild fish populations, the study of phthalate esters has become integral to determining whether or not these anti-androgenic chemicals are of concern. I investigated whether di-n-butyl phthalate (DBP) was able to cause antiandrogenic endocrine disruption in fish under controlled laboratory conditions. Three experiments were undertaken. In the first study, two generations of fathead minnows were exposed to nominal concentrations of 6 to 100 μg/L for 21 and 150 days, respectively. The second experiment examined the effects of early life-stage exposure to DBP (50, 100 and 200 μg DBP/L) on three-spined sticklebacks. The final experiment examined the effects of DBP on adult male three-spined sticklebacks in a 21-day nesting study (15 and 35 μg DBP/L). DBP had no effect on the fecundity, survival, growth, sex ratio, or gonadal histology of the exposed fish in any of the experiments. Further, it failed to alter the expression of two steroidogenic genes in adult male sticklebacks. In contrast, DBP was often found to significantly alter plasma androgen concentrations in both species, and spiggin concentrations in the three-spined stickleback, most notably causing significantly reduced spiggin concentrations in the adult males exposed to DBP. Ultimately, DBP-exposure did not disrupt the ability of the fish to reproduce successfully, and did not appear to alter reproductive behaviours or the expression of secondary sexual characteristics. In conclusion, while DBP did appear to have some capacity for endocrine disruption in fish, it was unable to interfere with the ability of the fish to develop normally and reproduce successfully. Thus, environmentallyrelevant concentrations of phthalate esters are likely not of particular concern to fish populations.EThOS - Electronic Theses Online ServiceGBUnited Kingdo