Localized vibration modes of defect pairs in silicon

Absorption bands and localized vibrational modes of silicon doped with boron compounds containing phosphorus, arsenic, antimony, or lithiu

Fire-grazing interaction: An ecological process

The ecological interactions between fire and grazing are widespread throughout fire-prone ecosystems. It is an ecological process that drives ecosystem structure and function, influencing broad, landscape level events to fine, localized processes. The fire-grazing interaction occurs when spatially distinct fires are present across a landscape and move through time, forcing grazing animals to choose among burned and unburned areas. The mechanisms of this interaction occur at multiple levels. At broad, landscape level scales, animals are attracted to and focus their grazing on recently burned areas. This attraction decreases as the amount of time since fire progresses. For bison (Bison bison) and cattle (Bos taurus) in tallgrass prairie of North America, the influence of time since fire supersedes most landscape features (e.g., distance to water, topography, etc.), indicative of the overall strength of the fire-grazing interaction.Mechanisms of the fire-grazing interaction are also present at finer, patch level scales. Forage quality and quantity differences between burned areas are responsible for preferential grazing of burned areas. Forage quality is inversely related to time since fire, so that recently burned areas are greatest in quality, while areas with greater time since fire are significantly lower. The opposite relationship is present with forage quantity, with burned areas having small amounts of quantity compared to areas with greater time since fire. Tradeoffs between forage quality and quantity emerge and influence the attraction of grazing animals to burned areas.The light environment at finer, plot level scales is also determined by the amount of time since fire within the fire-grazing interaction. The preferential grazing of recently burned areas maintain high light environments throughout the growing season. These areas differ from that of fire alone, where light limitations quickly return after fire. The high light environment allows for increased photosynthetic rate of dominant prairie plants, but at the expense of low leaf area through continual preferential grazing by animals. As a result, total carbon gain by plants is reduced compared to areas with greater time since fire. These results feedback and affect forage quality and quantity

War As Remembrance: Novel Reconstructs A Lovestruck Childhood Overwhelmed By Events

John Reed\u27s first novel, A Still Small Voice, is told as a memoir of Alma Flynt, an orphan girl who is taken in by her Aunt Bettina in Kentucky, just prior to the War. Alma learns herb and root healing from her aunt and falls in love with John Warren Cleveland, the younger son of the neighbor...

A Floristic Study in the Diamond Creek Drainage Area, Gila National Forest, New Mexico

The Diamond Creek drainage is one of the major watershed systems of the Gila National Forest in southwestern New Mexico. The purposes of this study were to catalog the vascular plants of a portion of this drainage area, describe the vegetation zones, locate any threatened, endangered, or sensitive plant species, and assess plant regeneration in areas that have been burned. The study area is located in the eastern portion of the Gila National Forest along the Black Range in the northwest corner of Sierra County. It covers approximately 5600 hectares (14000 acres) and ranges in elevation from 2250 to 3000 m (7400 to 9850 ft). Collected from the upper main Diamond Creek drainage area were 348 species including an additional six infraspecific taxa. The five largest families (by number of species and infraspecific taxa) in the study area were the Asteraceae (58), Poaceae (52), Fabaceae (24), Rosaceae (19), and Cyperaceae (17). The study area can be classified as Montane Coniferous Forest with most of the study area dominated by Pinus ponderosa and Pseudotsuga menziesii var. glauca. This overall vegetation type is fractured by narrow canyons, open meadows, perennial and intermittent streams, and rock outcrops. Three sensitive plant species were located in the study area: Erigeron scopulinus, Senecio sacramentanus, and Draba mogollonica. Two fires have occurred in the study area in recent times. These burned areas are primarily covered by shrubs including Quercus gambelii, Robinia neomexicana var. neomexicana, and Populus tremuloides

Quick actuating closure and handling system

A quick activating closure and handling system, which utilizes conical sections for locking, was developed to allow quick access to the combustor internal components of the 8 ft High Temperature Tunnel. These critical components include the existing methane spraybar, a transpiration cooled nozzle and the new liquid oxygen (LOX) injection system housed within the combustor. A substantial cost savings will be realized once the mechanism is installed since it will substantially reduce the access time and increase the time available for conducting wind tunnel tests. A need exists for more frequent inspections when the wind tunnel operates at the more severe conditions generated by using LOX in the combustor. A loads analysis and a structural (finite element) analysis were conducted to verify that the new closure system is compatible with the existing pressure shell. In addition, strain gages were placed on the pressure vessel to verify how the pressure shell reacts to transient pressure loads. A scale model of the new closure system was built to verify the operation of the conical sections in the locking mechanisms

Single acting translational/rotational brake

A brake system is provided that applies braking forces on surfaces in both the translational and rotational directions using a single acting self-contained actuator that travels with the translational mechanism. The brake engages a mechanical lock and creates a frictional force on the translational structure preventing translation while simultaneously creating a frictional torque that prevents rotation of the vertical support. The system may include serrations on the braking surfaces to provide increased braking forces

Grasslands of the Great Plains: Their Nature and Use

This book is the result of a long-felt need by the authors and their students for a comprehensive survey of the numerous studies that have been made on plains grasslands. From southern Texas far into Saskatchewan the mid and short grasses form a magnificent prairie nearly 2,500 miles in length and approximately 400 miles wide. Kinds of communities, their composition, nature, significance and uses are fully described. Such information is of value not only to students, range technicians, and other professional conservationists, but also to ranchers and other land owners-in fact, to anyone interested in the economy of our midwestern grasslands. The damaging effects of drought on forage production in this unstable climate and the restoration of the plant cover are of such great importance that they have been given special attention. Climate, soils, and. the proper use of the forage for its sustained production are described. A third of a century of study and experimentation in plains grassland by the authors permits accurate description and interpretation. Important studies that have been made on the vegetation since the coming of the white man to the present day are reviewed. Early investigations have been recorded in papers, bulletins and books, many of which are now out of print or difficult of access. Therefore permission was asked and promptly given by the Carnegie Institution of Washington, Duke University Press, Ecological Monographs, Ecology, and several other journals to re-use materials originally furnished by the authors. Such sources are carefully cited in the text. Only by such cooperation has this book been made possible. This great prairie land has been thoroughly examined as to its way of life both above ground and deep into the soil, which it has helped to build and so efficiently protects. Extensive, long-time investigations have elucidated many problems. The scope of the work has been broadened and deepened by the aid of a large number of advanced students who have sought graduate study in this field. To them, many of whom are today leaders in conservation of range management or in teaching a new generation of students the values of ecology in our economy, we are deeply grateful for their interest and cooperation. Two of them are so familiar with the grasslands of Texas and New Mexico, respectively, that each has contributed a chapter to this book. Both common and scientific names of grasses are according to Hitchcock and Chase (1950) revised Manual of the Grasses of the United States. Other scientific names follow Gleason\u27s New Britton and Brown Illustrated Flora (1952) or Harrington\u27s Manual of the Plants of Colorado (1954). Common names are nearly all according to the second edition (1913) of Britton and Brown or the second edition of Standardized Plant Names (1942). 404 page

Online Learning and Mentors: Addressing the Shortage of Rural Special Educators Through Technology and Collaboration

This article describes a promising model in comprehensive special education personnel preparation to support the recruitment and retention of special education teachers in rural areas. The approach draws on several bodies of research to include best practices for teacher education, online service delivery, collaboration among key stakeholders, and the development of strong mentoring and induction programs. The implementation plan, based on evidence-based practice in special education and online learning, is presented. A key element of this plan is developing and maintaining strong relationships among rural districts, the state department of education, and higher education