Regional tectonic analysis of Venus equatorial highlands and comparison with Earth-based Magellan radar images

Research on regional tectonic analysis of Venus equatorial highlands and comparison with earth-based and Magellan radar images is presented. Over the past two years, the tectonic analysis of Venus performed centered on global properties of the planet, in order to understand fundamental aspects of the dynamics of the mantle and lithosphere of Venus. These include studies pertaining to the original constitutive and thermal character of the planet, as well as the evolution of Venus through time, and the present day tectonics. Parameterized convection models of the Earth and Venus were developed. The parameterized convection code was reformulated to model Venus with an initially hydrous mantle to determine how the cold-trap could affect the evolution of the planet

Stress distribution and topography of Tellus Regio, Venus

The Tellus Regio area of Venus represents a subset of a narrow latitude band where Pioneer Venus Orbiter (PVO) altimetry data, line-of-sight (LOS) gravity data, and Venera 15/16 radar images have all been obtained with good resolution. Tellus Regio also has a wide variety of surface morphologic features, elevations ranging up to 2.5 km, and a relatively low LOS gravity anomaly. This area was therefore chosen in order to examine the theoretical stress distributions resulting from various models of compensation of the observed topography. These surface stress distributions are then compared with the surface morphology revealed in the Venera 15/16 radar images. Conclusions drawn from these comparisons will enable constraints to be put on various tectonic parameters relevant to Tellus Regio. The stress distribution is calculated as a function of the topography, the equipotential anomaly, and the assumed model parameters. The topography data is obtained from the PVO altimetry. The equipotential anomaly is estimated from the PVO LOS gravity data. The PVO LOS gravity represents the spacecraft accelerations due to mass anomalies within the planet. These accelerations are measured at various altitudes and angles to the local vertical and therefore do not lend themselves to a straightforward conversion. A minimum variance estimator of the LOS gravity data is calculated, taking into account the various spacecraft altitudes and LOS angles and using the measured PVO topography as an a priori constraint. This results in an estimated equivalent surface mass distribution, from which the equipotential anomaly is determined

Lift Enhancement for Low-Aspect-Ratio Wings with Periodic Excitation

In an effort to enhance lift on low-aspect-ratio rectangular flat-plate wings in low-Reynolds-number post-stall flows, periodic injection of momentum is considered along the trailing edge in this numerical study. The purpose of actuation is not to reattach the flow but to change the dynamics of the wake vortices such that the resulting lift force is increased. Periodic forcing is observed to be effective in increasing lift for various aspect ratios and angles of attack, achieving a similar lift enhancement attained by steady forcing with less momentum input. Through the investigation on the influence of the actuation frequency, it is also found that there exists a frequency at which the flow locks on to a time-periodic high-lift state

Coping With Racism: Moderators of the Discrimination-Adjustment Link Among Mexican-Origin Adolescents

What strategies help ethnic minority adolescents to cope with racism? The present study addressed this question by testing the role of ethnic identity, social support, and anger expression and suppression as moderators of the discrimination-adjustment link among 269 Mexican-origin adolescents (Mage = 14.1 years), 12-17 years old from the Midwestern U.S. Results from multilevel moderation analyses indicated that ethnic identity, social support, and anger suppression, respectively, significantly attenuated the relations between discrimination and adjustment problems, whereas outward anger expression exacerbated these relations. Moderation effects differed according to the level of analysis. By identifying effective coping strategies in the discrimination-adjustment link at specific levels of analysis, the present findings can guide future intervention efforts for Latino youth

A DOUBLE HURDLE APPROACH TO EVALUATING NON-RESIDENTIAL WILDLIFE WATCHING IN THE UNITED STATES

In 1996, over 62 million U.S. residents participated in wildlife watching and spent in excess of 29 billion dollars in this recreational activity. Wildlife watching can be defined as the observation, study, and enjoyment of natural areas and its wild fauna and flora. Residential wildlife watching takes place within one mile of the participant's residence and is often an incidental or secondary activity. Non-residential wildlife watching refers to recreation taking place at a distance of at least one mile from the participant's residence. In recent years, a sharp decline in the number of wildlife watchers has been noted. Between 1991 and 1996, the number of wildlife watchers decreased by 17 percent. During this time interval, the largest decline in participation was observed in non-residential viewing. The number of non-residential wildlife watchers declined by 21 percent. This trend is damaging to towns and communities, especially rural communities which largely depend on recreation dollars. The mitigation or reversal of this trend hinges upon the identification of factors affecting participation and expenditures on wildlife viewing. The determining role of several socioeconomic attributes in explaining participation and expenditures on nature-related recreation has been widely studied in the leisure and recreation literature. However, most of these past studies have focused on fishing and hunting activities rather than the equally important non-residential wildlife watching. Hence, this study evaluates participation decisions and the extent of the participation in non-residential wildlife watching in the United States. Keywords: wildlife watching, limited dependent variables, double hurdlewildlife watching, limited dependent variables, double hurdle, Resource /Energy Economics and Policy,

The ecology of some Harpacticoid copepods of a California sand flat

The main purpose of this study is to describe the population ecology of eight species of harpacticoid copepods over a period of one year with emphasis on the effects of physical interactions and biotic factors on these populations. The species were: Amphiascopsis sintus (Claus) 1866, Stenhelia (D.) oblonga Lang, 1965, Heterolaphote variables Lang, 1965, Ectinosoma melaniceps Boek ? var. T. Scott, 1902, Paralophonte subterraneas Lang, 1965, Tisbe furcata (Baird) 1837, Diasaccus spinatus Cambell, 1929 and Parathelestris bulbiseta Cambell?