Electrostatic Electron Microscopy. II

This paper is a continuation of the description of problems arising in the development and design of an electrostatic electron microscope. The present article discusses depth of focus, lens and field stops, shielding, manufacturing tolerances, the choice of the number of stages of magnification, and alternative methods of viewing and recording the final image. A following paper will describe a completed instrument

Electrostatic Electron Microscopy. III

This article, the final one of a series on the design of electrostatic electron microscopes, contains a description of an instrument which illustrates the principles previously discussed. The microscope described is believed to be the first constructed with the object of providing the greatest of simplicity in construction, operation, and maintenance with the design parameters balanced to give a particular range of resolving power. The range chosen is about ten times the light microscope. The instrument is permanently aligned and utilizes external photography. The over-all size and weight of the instrument, as well as the number and complexity of components, are materially less than previously described instruments

Impoundment Drawdown and Artificial Nest Structures as Management Strategies for Snowy Plovers

This paper presents preliminary work on two potential management techniques that might enhance populations of Snowy Plovers (Charadrius alexandrines). Large tracts of suitable plover nesting habitat are being degraded by vegetation encroachment at Great Sale Lake, Utah. Therefore, we used impoundment drawdown to create shorebird nesting habitat by eliminating unwanted vegetation at a diked wetland. Twenty-two pairs of Snowy Plovers, four pairs of American Avocets (Recurvirosta Americana), and one pair of Long-billed Curlew (Numenius americanus) nested in a 12-ha drawdown impoundment. Also, some apparently suitable nesting macrohabitants (sparsely vegetation salt flats) were not used by breeding plovers. We thought increasing the availability of potential nest-site microhabitants in these suitable macrohabitants might increase their use. We placed 1-m2 gravel pads on selected barren salt flats at Great Salt Lake, and Snowy Plovers readily used these artificial substrates; 50% of 32 small-grained structures were used for building scrapes and three structures had clutches initiated on them. These strategies represent potential management techniques that should be field tested by land managers to determine their effectiveness to enhance Snowy Plover populations

Factors Affecting the Immune System of the Ornate Box Turtle (\u3ci\u3eTerrapene ornata\u3c/i\u3e)

While many studies have detailed the complex intricacies of the endothermic immune system, relatively little is known about the immune system of ectotherms--specifically, reptiles. In an attempt to gain more knowledge about the factors affecting reptilian immune function, ornate box turtles (Terrapene ornata) were subjected to chronic stress in the form of high ambient temperatures in a semi-natural environment. It was hypothesized that chronic stress would lead to elevated levels of corticosterone in the blood, which would, in turn, suppress immune activity. It was found that body temperature and body mass in particular were significantly affected by chronic heat stress. Among turtles subjected to chronic heat stress, white blood cell to red blood cell ratios decreased and numbers of natural antibodies decreased--all of which suggests lowered immune activity. This decrease in immune activity correlated with increases in body temperature as well as body mass. Changes in corticosterone levels within and between both treatment groups were insignificant. Taken together, these results suggest that turtles subjected to chronic heat stress experienced improved health due to increased body mass, increased body temperature, and decreased immune function. This study reinforces the complexity of the stress response, and it highlights its far-reaching effects not only on immune function, but also on the body as a whole

Apollo experience report guidance and control systems: Primary guidance, navigation, and control system development

The primary guidance, navigation, and control systems for both the lunar module and the command module are described. Development of the Apollo primary guidance systems is traced from adaptation of the Polaris Mark II system through evolution from Block I to Block II configurations; the discussion includes design concepts used, test and qualification programs performed, and major problems encountered. The major subsystems (inertial, computer, and optical) are covered. Separate sections on the inertial components (gyroscopes and accelerometers) are presented because these components represent a major contribution to the success of the primary guidance, navigation, and control system

Contributions of phenotypic plasticity to differences in thermogenic performance between highland and lowland deer mice

Small mammals face especially severe thermoregulatory challenges at high altitude because the reduced O2 availability constrains the capacity for aerobic thermogenesis. Adaptive enhancement of thermogenic performance under hypoxic conditions may be achieved via physiological adjustments that occur within the lifetime of individuals (phenotypic plasticity) and/or genetically based changes that occur across generations, but their relative contributions to performance differences between highland and lowland natives are unclear. Here, we examined potentially evolved differences in thermogenic performance between populations of deer mice (Peromyscus maniculatus) that are native to different altitudes. The purpose of the study was to assess the contribution of phenotypic plasticity to population differences in thermogenic performance under hypoxia. We used a common-garden deacclimation experiment to demonstrate that highland deer mice have enhanced thermogenic capacities under hypoxia, and that performance differences between highland and lowland mice persist when individuals are born and reared under common-garden conditions, suggesting that differences in thermogenic capacity have a genetic basis. Conversely, population differences in thermogenic endurance appear to be entirely attributable to physiological plasticity during adulthood. These combined results reveal distinct sources of phenotypic plasticity for different aspects of thermogenic performance, and suggest that thermogenic capacity and endurance may have different mechanistic underpinnings. Includes Supplementary material

Operationalising and measuring language dominance

The paper offers a new way to measure language ability in bilinguals, based on measures of lexical richness. The validity of proposed approach is tested in a variety of ways

Nickel-Catalyzed Enantioconvergent Borylation of Racemic Secondary Benzylic Electrophiles

Nickel‐catalyzed cross‐coupling has emerged as the most versatile approach to date for achieving enantioconvergent carbon–carbon bond formation using racemic alkyl halides as electrophiles. In contrast, there have not yet been reports of the application of chiral nickel catalysts to the corresponding reactions with heteroatom nucleophiles to produce carbon–heteroatom bonds with good enantioselectivity. Herein, we establish that a chiral nickel/pybox catalyst can borylate racemic secondary benzylic chlorides to provide enantioenriched benzylic boronic esters, a highly useful family of compounds in organic synthesis. The method displays good functional group compatibility (e.g., being unimpeded by the presence of an indole, a ketone, a tertiary amine, or an unactivated alkyl bromide), and both of the catalyst components (NiCl_2⋅glyme and the pybox ligand) are commercially available