Personal, Social, and Environmental Correlates of Walking to School Behaviors: Case Study in Austin, Texas

Walking is an affordable and environmentally clean mode of transportation that can bring additional benefits as healthy physical activity. This cross-sectional study examines the prevalence and correlates of walking to or from school in eight elementary schools in Austin, Texas, which have high percentages of low-income, Hispanic students. A survey of 1,281 parents was conducted, including questions about personal, social, and environmental factors that may influence their decisions on the children's school transportation. Binary logistic regressions were used to estimate the odds of choosing walking as the children's typical school travel mode. The results showed that walking was a typical mode for 28 and 34% of trips to and from school, respectively, and mostly accompanied by an adult. Parents' education level, family's car ownership, children's and parents' personal barriers, and having the school bus service reduced the likelihood of walking, while positive peer influences encouraged walking. Among the physical environmental factors, living close to school was the strongest positive predictor; safety concerns and the presence of highway or freeway en route were negative correlates. We concluded that the location of school is a key, as it determines the travel distance and the presence of highway or freeway en route. In addition to environmental improvements, educational and other assistance programs are needed for both parents and children to overcome their personal barriers and safety concerns. Health and disparity issues require further attention, as many underprivileged children have no other means of school transportation but walking in unsafe and poor environments

A higher-order panel method for third-harmonic diffraction problems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, February 1997.Includes bibliographical references (leaves 119-123).by Xuemei Zhu.Ph.D

Community environments and walking-to-school behaviors: multi-level correlates and underlying disparities

Walking can be a safe, healthy, and affordable mode of school transportation. However, most students today do not use walking for their school travel. More research is needed to understand the correlates of walking to or from school and to identify effective interventions. This is a cross-sectional study of 73 public elementary schools in the Austin Independent School District of Texas. The first phase used geographic information systems and field audits to examine school-level disparities in the environmental support for walking in schools’ attendance areas. The second phase involved surveys of students’ parents or guardians to identify the multi-level correlates of using walking as their children’s typical school travel mode. In the first phase, results from analyses of variance and linear regressions indicated the existence of disparities. Lower economic status of student population was associated with poorer street conditions (e.g., maintenance, visual quality, amenities, and perceived safety), shorter distances to school, and lower traffic volumes. Higher percentage of Hispanic students within a school was associated with increased danger from traffic and crime and more sidewalks, greater population density, and mixed land uses. The second phase used binary logistic regressions to predict walking to or from school. Among the personal and social factors, parents’ education, car ownership, personal barriers, and school bus availability were negative correlates, while parents’ and children’s positive attitude and regular walking habit and supportive peer influences were positive correlates. Of the physical environmental factors, long distance and safety concerns were the strongest negative correlates, followed by the presence of highways or freeways, convenience stores, office buildings, and bus stops en route. In conclusion, environmental interventions are needed to develop centrallylocated neighborhood schools, barrier-free attendance areas, and well-maintained pedestrian infrastructure. Disparities and fine-grained differences are found in the environmental support for walking. A high priority for low-income, Hispanic children and interventions tailored for specific contexts and populations appear necessary. Safety improvement is indispensible in terms of both traffic and crime and should be supplemented with educational programs that target both parents and children. Finally, multi-agency collaborations are needed at the policy level to support and facilitate these multi-level interventions

Magnetic Properties of One-Dimensional Quasiperiodic Co/Pt Multilayers

We have fabricated Fibonacci [Co/Pt] multilayers with two constituent Co/Pt bilayers, as well as periodic multilayers of the same Co/Pt bilayers, all of which exhibit perpendicular magnetic anisotropy. Magnetic properties of the quasiperiodic and periodic [Co/Pt] multilayers have been studied macroscopically by vibrating sample magnetometry and microscopically by magnetic force microscopy. The Fibonacci [CoPt] multilayers show enhanced squareness in magnetic hysteresis loops compared to the corresponding periodic [Co/Pt]n multilayers, due to a smaller density of isolated nucleation sites in the saturation state

Energy Conservation and Heat Transfer Enhancement for Mixed Convection on the Vertical Galvanizing Furnace

The alloying temperature is an important parameter that affects the properties of galvanized products. The objective of this study is to explore the mechanism of conjugate mixed convection in the vertical galvanizing furnace and propose a novel energy conservation method to improve the soaking zone temperature based on the flow pattern and heat transfer characteristics. Herein, the present study applied the k-ε two-equation turbulence model to enclose the Navier-Stokes fluid dynamic and energy conservation equations, and the temperature distributions of the steel plate and air-flow field in the furnace were obtained for six Richardson numbers between 1.91 ⋅ 105 and 6.30 ⋅ 105. In the industrial practice, the side baffles were installed at the lateral opening of the cooling tower to alter the height of vertical flow passage, which affected the Richardson number. The results indicate that the Richardson number of 2.4 ⋅ 105 generated the highest heat absorption and maximal temperature in the steel plate due to the balance between natural and forced convection. Furthermore, the results of the on-line experiments validated the simulation research. The method enhanced the steel plate temperature in the soaking zone without increasing the heat power, thereby characterizing it as energy conservation technology

Magnetic Properties of One-Dimensional Quasiperiodic Co/Pt Multilayers

We have fabricated Fibonacci [Co/Pt] multilayers with two constituent Co/Pt bilayers, as well as periodic multilayers of the same Co/Pt bilayers, all of which exhibit perpendicular magnetic anisotropy. Magnetic properties of the quasiperiodic and periodic [Co/Pt] multilayers have been studied macroscopically by vibrating sample magnetometry and microscopically by magnetic force microscopy. The Fibonacci [CoPt] multilayers show enhanced squareness in magnetic hysteresis loops compared to the corresponding periodic [Co/Pt]n multilayers, due to a smaller density of isolated nucleation sites in the saturation state

Control of astrocyte progenitor specification, migration and maturation by Nkx6.1 homeodomain transcription factor.

Although astrocytes are the most abundant cell type in the central nervous system (CNS), little is known about their molecular specification and differentiation. It has previously been reported that transcription factor Nkx6.1 is expressed in neuroepithelial cells that give rise to astrocyte precursors in the ventral spinal cord. In the present study, we systematically investigated the function of Nkx6.1 in astrocyte development using both conventional and conditional Nkx6.1 mutant mice. At early postnatal stages, Nkx6.1 was expressed in a subpopulation of astrocytes in the ventral spinal cord. In the conventional Nkx6.1KO spinal cord, the initial specification of astrocyte progenitors was affected by the mutation, and subsequent migration and differentiation were disrupted in newborn mice. In addition, the development of VA2 subtype astrocytes was also inhibited in the white matter. Further studies with Nkx6.1 conditional mutants revealed significantly delayed differentiation and disorganized arrangement of fibrous astrocytes in the ventral white matter. Together, our studies indicate that Nkx6.1 plays a vital role in astrocyte specification and differentiation in the ventral spinal cord