Oxynitride glass fibers

Research at the Army Materials Technology Laboratory (AMTL) and elsewhere has shown that many glass properties including elastic modulus, hardness, and corrosion resistance are improved markedly by the substitution of nitrogen for oxygen in the glass structure. Oxynitride glasses, therefore, offer exciting opportunities for making high modulus, high strength fibers. Processes for making oxynitride glasses and fibers of glass compositions similar to commercial oxide glasses, but with considerable enhanced properties, are discussed. We have made glasses with elastic moduli as high as 140 GPa and fibers with moduli of 120 GPa and tensile strengths up to 2900 MPa. AMTL holds a U.S. patent on oxynitride glass fibers, and this presentation discusses a unique process for drawing small diameter oxynitride glass fibers at high drawing rates. Fibers are drawn through a nozzle from molten glass in a molybdenum crucible at 1550 C. The crucible is situated in a furnace chamber in flowing nitrogen, and the fiber is wound in air outside of the chamber, making the process straightforward and commercially feasible. Strengths were considerably improved by improving glass quality to minimize internal defects. Though the fiber strengths were comparable with oxide fibers, work is currently in progress to further improve the elastic modulus and strength of fibers. The high elastic modulus of oxynitride glasses indicate their potential for making fibers with tensile strengths surpassing any oxide glass fibers, and we hope to realize that potential in the near future

Clinician\u27s perceptions about working with LGBTQ military personnel and cultural competency

This qualitative exploratory study was completed to investigate clinician\u27s perceptions of working with LGBTQ military personnel in a therapeutic setting. Secondly, this study explored the concept of cultural competency as it relates to working with the LGBTQ military population. Using semi-structured interviews with clinicians currently in practice will military clients this study found that all nine participants felt competent in their work with LGBTQ clients. This study also found that although clinicians were aware of some specific issues LGBTQ military clients might face, there was a lack of more specific knowledge related to this population. This study also found a general consensus of lack of training regarding this population, denial of bias or homophobia with the population and absence of community changes since the repeal of Don\u27t Ask, Don\u27t Tell and the Defense of Marriage Act. This study concluded that educational workshops or trainings are the key to developing more culturally competent work with LGBTQ military personnel. Therefore, this study suggests that further research regarding work with LGBTQ military personnel and cultural competency is critical so that graduate schools can enhance their curriculum, graduate students can feel more competent and prepared, clients can feel more connected and less stigmatized in therapy and clinicians can feel more prepared and educated regarding key issues of this population

Hierarchical forest management planning and sustainable forest management in the boreal forest

In keeping with international efforts to encourage sustainable forest management, new legislation, regulations, and certification criteria have been brought into effect across boreal regions of the world in the past decade or less. These initiatives have established hierarchical systems of forest management planning that consider multiple uses of the forest and various aspects of sustainable forest management at different scales. We describe the systems established in Quebec, Ontario, Saskatchewan, Alberta, and British Columbia, Russia, Finland, and Sweden. Most jurisdictions employ some form of three-level planning framework, in which strategic, tactical, and operational plans and considerations are presented with successively greater detail and spatial explicitness. However, planning scales and time horizons vary considerably, as does the level of consideration given to biodiversity and social concerns. We examine these systems in the context of sustainable forest management, raising a number of questions to be addressed in future research, adaptive management, and policy reform. In particular, we note (1) a need of new landscape and regional planning tools to evaluate the long-term and large-scale impacts of various land uses and (2) a general lack of responsiveness to global carbon and climate change concerns

Summer Movements and Impact of Individual Striped Skunks, Mephitis mephitis, on Duck Nests in Saskatchewan

Striped Skunks (Mephitis mephitis) are important predators of duck eggs in the Canadian prairies. We estimated the impact of individual Striped Skunks on duck nests by intensive observations of foraging movements and depredation of duck nests in southern Saskatchewan, 1993-1994. Nightly, skunk movements were variable (range 0-20 km per night), and did not differ among seasons for females, or between males and females during the parturition/rearing season. Overall, nightly movement of Striped Skunks averaged 7.4 km for females (SD = 5.9 km, n = 20 females) and 6.7 km for males (SD = 3.2 km, n = 5 males). During 1,873 h of radio-tracking, we observed depredation of 10 duck nests by 8 skunks (7 F, 1 M). Using our observed estimate of one depredation for every 187 h, and averaged nightly activity of 8-10 h per night, we estimated that individual skunks find one duck nest every 19-23 nights. Thus, during the 60-day nesting season for ducks (mid-May to mid-July), individual skunks probably find 2-3 duck nests. These observations reinforce the growing evidence that, at normal duck nest densities (<2.5 nests/ha), depredation of eggs by Striped Skunks is opportunistic, and the impact of Striped Skunks on duck nests is a direct function of Striped Skunk abundance

Blending of nanoscale and microscale in uniform large-area sculptured thin-film architectures

The combination of large thickness ($>3$ $\mu$m), large--area uniformity (75 mm diameter), high growth rate (up to 0.4 $\mu$m/min) in assemblies of complex--shaped nanowires on lithographically defined patterns has been achieved for the first time. The nanoscale and the microscale have thus been blended together in sculptured thin films with transverse architectures. SiO$_x$ ($x\approx 2$) nanowires were grown by electron--beam evaporation onto silicon substrates both with and without photoresist lines (1--D arrays) and checkerboard (2--D arrays) patterns. Atomic self--shadowing due to oblique--angle deposition enables the nanowires to grow continuously, to change direction abruptly, and to maintain constant cross--sectional diameter. The selective growth of nanowire assemblies on the top surfaces of both 1--D and 2--D arrays can be understood and predicted using simple geometrical shadowing equations.Comment: 17 pages, 9 figure

Effects of light and intraspecific competition on growth and crown morphology of two size classes of understory balsam fir saplings

This paper characterizes the growth and crown morphology of young balsam fir saplings naturally regenerated under a gradient of understory light environments and intraspecific competition densities for two size classes (50-100 cm and 100-200 cm). Most growth and crown morphological parameters investigated were strongly related to the natural light gradient investigated (3-83% full sunlight), but the relationship tended to plateau at around 25% full sunlight. The relationships were generally better for the larger size class. Intraspecific competition did not significantly affect growth and crown morphology of saplings receiving less than 25% full sunlight, but it affected relative height growth, relative radial growth and the apical dominance ratio for those receiving more than 25% full sunlight (R2=0.506; p<0.001; R2=0.403; p<0.002; R2=0.348; p<0.001, respectively). These results suggest that live crown ratio, apical dominance ratio and the number of internodal branches can provide, alone or in combination, useful indicators of vigour for understory fir. Such a study provides the basic data inputs required for the development of empirically-derived mechanistic models that can predict understory tree growth and survival

Shoot growth and crown development: effect of crown position in three-dimensional simulations

Trees have been increasingly considered as modular organisms, with individual shoots forming autonomous units that respond semi-independently to their surrounding environment. However, there is evidence for fairly strict hormonal control of tree crown development. Studies on the hydraulic architecture of trees suggest a closer functional connection between shoots and crown development than is postulated by the theory of branch autonomy. We studied how shoot growth pattern influences growth and crown architecture in young Scots pine trees simulated by the LIGNUM model assuming that (a) the growth of a shoot mainly depends on its light climate and (b) the growth of a shoot is influenced by its position within the crown. We determined shoot position within the crown based on a recently developed vigor index. The vigor index compares the relative axis cross-sectional area from the base of the tree to each shoot and gives a value of 1 to the pathway of the greatest cross-sectional area. All other shoots attain values between 0 and 1 depending on their cross-sectional areas and the cross-sectional areas of the branches leading there from the main axis. The shoot light climate is characterized by annually intercepted photosynthetically active radiation. We compared the results from simulations (a) and (b) against an independent data set. The addition of a within-shoot position index (the vigor index) to our simulation (simulation b) resulted in a more realistic tree form than that obtained with simulation (a) alone. We discuss the functional significance of the results as well as the possibilities of using an index of shoot position in simulations of crown architecture

Morphological indicators of growth response of coniferous advance regeneration to overstorey removal in the boreal forest

Regeneration of forest stands through the preservation of existing advance regeneration has gained considerable interest in various regions of North America. The effectiveness of this approach relies on the capacity of regeneration to respond positively to overstory removal. Responses of advance regeneration to release is dependent on tree characteristics and site conditions interacting with the degree of physiological shock caused by the sudden change in environmental conditions. This paper presents a review of the literature describing the relationships between morphological indicators and the advance regeneration response to canopy removal. It focuses primarily on the following species: jack pine (Pinus banksiana Lamb.), lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), black spruce (Picea mariana (Mill.) B.S.P.), interior spruce (Picea glauca x engelmannii), white spruce (Picea glauca (Moench) Voss), balsam fir (Abies balsamea (L.) Mill.), and subalpine fir (Abies lasiocarpa (Hook.) Nutt). Pre-release height growth has been found to be a good indicator of post-release response for many species. Live-crown ratio also appears to be a good indicator of vigour for shade-tolerant species. The ratio of leader length to length of the longest lateral at the last whorl could serve to describe the degree of suppression before harvest for shade-tolerant species. Number of nodal and internodal branches or buds has been found to be related with vigour for many species. Logging damage has been shown to be an important determinant of seedling response to overstory removal. In contrast, height/diameter ratio has limited value for predicting response to release since it varies with site, species and other factors. No clear relationship between age, height at release and response to release could be demonstrated. This paper also suggests the use of combined indicators and critical threshold values for these indicators

Cosmological implications of the KATRIN experiment

The upcoming Karlsruhe Tritium Neutrino (KATRIN) experiment will put unprecedented constraints on the absolute mass of the electron neutrino, \mnue. In this paper we investigate how this information on \mnue will affect our constraints on cosmological parameters. We consider two scenarios; one where \mnue=0 (i.e., no detection by KATRIN), and one where \mnue=0.3eV. We find that the constraints on \mnue from KATRIN will affect estimates of some important cosmological parameters significantly. For example, the significance of $n_s<1$ and the inferred value of $\Omega_\Lambda$ depend on the results from the KATRIN experiment.Comment: 13 page