Impacts of culture on driver knowledge and safety device usage among Hispanic farm workers

This study examines Hispanic migrant farm workers' driving behaviors and knowledge of the laws. These laborers worked and drove in California's agricultural region up to 8 months a year. Results are based on 167 face-to-face interviews conducted in Spanish at five labor camps and 126 observations conducted at these same camps in California. Most drivers were male licensed drivers (79%), who learned to drive at ages 8-14 in Mexico (42%). Those licensed in Mexico versus the US received more citations and unlicensed drivers were rated with poor driving skills. Drivers reported 'always' using seat belts (86%), yet admitted not buckling up within the previous 2 months. Observational data showed that only 37% used belts and 55% of drivers riding alone were belted. Reasons for non-use reflected cultural and economic issues and lack of effective media safety campaigns for this group. Most (75%) drivers with children (< 4 years) said they used child safety seats and others with 1+ children (< 4 years) used no safety seats (20%) or only one seat (53%). Observations showed that regardless of the number of riders aged 0-4, the number of car seats never exceeded one. In 66% of the cars where a single child was carried and where two children were carried, no car seats were used. In all of these cases there were other passengers and drivers who were not belted.     

Snowcover Influence on Backscattering from Terrain

The effects of snowcover on the microwave backscattering from terrain in the 8-35 GHz region are examined through the analysis of experimental data and by application of a semiempirical model. The model accounts for surface backscattering contributions by the snow-air and snow-soil interfaces, and for volume backscattering contributions by the snow layer. Through comparisons of backscattering data for different terrain surfaces measured both with and without snowcover, the masking effects of snow are evaluated as a function of snow water equivalent and liquid water content. The results indicate that with dry snowcover it is not possible to discriminate between different types of ground surface (concrete, asphalt, grass, and bare ground) if the snow water equivalent is greater than about 20 cm (or a depth greater than 60 cm for a snow density of 0.3 g · cm-3). For the same density, however, if the snow is wet, a depth of 10 cm is sufficient to mask the underlying surface.     

Human-systems interaction for virtual environment team training

Virtual environments are increasingly used to support collaborative activities and distance learning. However, few are designed to support students, instructors and simulations in multi-participant team training. This paper describes the Training Studio, a system for authoring, delivering and evaluating multi-participant team training in an immersed virtual environment. The Training Studio focuses on human-systems interaction, allowing multiple students to learn and perform team tasks. The Training Studio supports collaborative learning for either single or multi-participant activity. This is accomplished through the use of agents which are assigned to students to act as personal mentors or missing team members. Conducting team training within a virtual environment introduces complexities and issues unique to team training and multiple-participant virtual environments. This paper describes our approach to virtual environment team training, discussing issues confronted and resulting design considerations and implementations.     

Electromagnetic scattering from grassland. I. A fullyphase-coherent scattering model

A microwave scattering formulation is presented for grassland and other short vegetation canopies. The fact that the constituent elements of these targets can be as large as the vegetation layer make this formulation problematic. For example, a grass element may extend from the soil surface to the top of the canopy, and thus the upper portion of the element can be illuminated with far greater energy than the bottom. By modeling the long, thin elements of this type of vegetation as line dipole elements, this nonuniform illumination can be accounted for. Additionally, the stature and structure of grass plants can result in situations where the average inner-product of coherent terms are significant at lower frequencies. As a result, the backscattering coefficient cannot be modeled simply as the incoherent addition of the power from each element and scattering mechanism. To determine these coherent terms, a coherent model that considers scattered fields, and not power, is provided. This formulation is then used to provide a solution to the multiple coherent scattering terms, terms which include the correlation of the scattering between both dissimilar constituent elements and dissimilar scattering mechanisms. Finally, a major component of the grass family are cultural grasses, such as wheat and barley. This vegetation is often planted in row structures, a periodic organization that can likewise result in significant coherent scattering effects, depending on the frequency and illumination pattern. Therefore, a formulation is also provided that accounts for the unique scattering of these structures     

Statistical modeling of MOS devices for parametric yield prediction

In the manufacturing of VLSI circuits, engineering designs should take into consideration random variations arising from processing. In this paper, statistical modeling of MOS devices is reviewed, and effective and practical models are developed to predict the performance spread (i.e., parametric yield) of MOS devices and circuits due to the process variations. To illustrate their applications, the models are applied to the 0.25 μm CMOS technology, and measured data are included in support of the model calculations.     

Association of high viral load and abnormal liver function with high aflatoxin B1-albumin adduct levels in HIV-positive Ghanaians: preliminary observations

We examined the association between certain clinical factors and aflatoxin B(1)-albumin adduct (AF-ALB) levels in HIV-positive people. Plasma samples collected from 314 (155 HIV-positive and 159 HIV-negative) people were tested for AF-ALB levels, viral load, CD4+ T-cell count, liver function profile, malaria parasitaemia, and hepatitis B and C virus infections. HIV-positive participants were divided into high and low groups based on their median AF-ALB of 0.93 pmol mg(-1) albumin and multivariable logistic and linear regression methods used to assess relationships between clinical conditions and AF-ALB levels. Multivariable logistic regression showed statistically significant increased odds of having higher HIV viral loads (OR=2.84; 95% CI=1.17-7.78) and higher direct bilirubin levels (OR=5.47; 95% CI=1.03-22.85) among HIV-positive participants in the high AF-ALB group. There were also higher levels of total bilirubin and lower levels of albumin in association with high AF-ALB. Thus, aflatoxin exposure may contribute to high viral loads and abnormal liver function in HIV-positive people and so promote disease progression.