Investigation of direct solar-to-microwave energy conversion techniques

Identification of alternative methods of producing microwave energy from solar radiation for purposes of directing power to the Earth from space is investigated. Specifically, methods of conversion of optical radiation into microwave radiation by the most direct means are investigated. Approaches based on demonstrated device functioning and basic phenomenologies are developed. There is no system concept developed, that is competitive with current baseline concepts. The most direct methods of conversion appear to require an initial step of production of coherent laser radiation. Other methods generally require production of electron streams for use in solid-state or cavity-oscillator systems. Further development is suggested to be worthwhile for suggested devices and on concepts utilizing a free-electron stream for the intraspace station power transport mechanism

On model updating of turbo-generator set

Models can be applied for simulating dynamical behavior of rotating machinery or specific faulty conditions. Efficient model updating techniques could be very useful for increasing model accuracy. Model updating of rotor systems is significantly different with respect to the well-known model updating techniques and related modal analyses performed in the field of vibrating structures. This paper investigates both the difficulties and the conditions of rotor vibrations measurement tests as well as the approximations introduced in the rotor model. Some experimental cases of turbo-generator machines indicate the difficulties and problems in the identification of eigen-frequencies and damping modal parameter. In the second part of the paper uncertainties and non-linearity of the model are investigated. An example of updating of some shaft and bearing parameters by means of an evolutionary algorithm, for fitting the natural frequencies of a shaft line, is presented and discussed. Model updating techniques of bearing coefficients are also discussed and a procedure is proposed to avoid misleading results of widely-used model updating approaches

Two-Dimensional Laser-Doppler Velocimetry in Turbulent Flows

Localized measurement of the velocity of flow In fluids may be accomplished by detecting the Doppler shift In frequency from coherent, monochromatic light scattered from micrometer sized contaminant particles within the flow. The versatility of applications of this technique, first used several years ago, has been expanded by recent research. The basic geometry of measurement, in which the scattered energy is recombined with light energy at the original frequency on the face of the photocathode of a photomultiplier tube, can be rearranged in many alternative configurations to meet the needs of the experimenter. By using a single laser, additional arrangements are possible for obtaining two- or three-dimensional measurements of velocity components. Several different velocimeters are described for making two-dimensional flow measurements, including both backscatter and forward scatter systems. Effects of flow system geometries on capabilities for measuring specific components are investigated. Effects of laser beam polarization are discussed and conclusions reached on methods of optimizing signal strength in each of two orthogonal measurement systems. Results of the application of a two-dimensional measurement system used for obtaining velocity profiles in turbulent flow in a smooth walled four-inch diameter pipe are presented. Operating at a Reynolds number of about 1.1 x 106, relative turbulent intensities were measured in the axial direction and normal to that direction. Standard techniques were utilized. A second readout system was employed to make a measurement of this parameter without the requirement of adding scattering centers to the flow

The effect of N-acetyl-aspartyl-glutamate and N-acetyl-aspartate on white matter oligodendrocytes

Elevations of the levels of N-acetyl-aspartyl-glutamate (NAAG) and N-acetyl-aspartate (NAA) are associated with myelin loss in the leucodystrophies Canavan's disease and Pelizaeus-Merzbacher-like disease. NAAG and NAA can activate and antagonize neuronal N-methyl-D-aspartate (NMDA) receptors, and also act on group II metabotropic glutamate receptors. Oligodendrocytes and their precursors have recently been shown to express NMDA receptors, and activation of these receptors in ischaemia leads to the death of oligodendrocyte precursors and the loss of myelin. This raises the possibility that the failure to develop myelin, or demyelination, occurring in the leucodystrophies could reflect an action of NAAG or NAA on oligodendrocyte NMDA receptors. However, since the putative subunit composition of NMDA receptors on oligodendrocytes differs from that of neuronal NMDA receptors, the effects of NAAG and NAA on them are unknown. We show that NAAG, but not NAA, evokes an inward membrane current in cerebellar white matter oligodendrocytes, which is reduced by NMDA receptor block (but not by block of metabotropic glutamate receptors). The size of the current evoked by NAAG, relative to that evoked by NMDA, was much smaller in oligodendrocytes than in neurons, and NAAG induced a rise in [Ca^{2+}]i in neurons but not in oligodendrocytes. These differences in the effect of NAAG on oligodendrocytes and neurons may reflect the aforementioned difference in receptor subunit composition. In addition, as a major part of the response in oligodendrocytes was blocked by tetrodotoxin (TTX), much of the NAAG-evoked current in oligodendrocytes is a secondary consequence of activating neuronal NMDA receptors. Six hours exposure to 1 mM NAAG did not lead to the death of cells in the white matter. We conclude that an action of NAAG on oligodendrocyte NMDA receptors is unlikely to be a major contributor to white matter damage in the leucodystrophies

Resourcing Scholar-Activism: Collaboration, Transformation, and the Production of Knowledge

In this article we offer a set of resources for scholar-activists to reflect on and guide their practice. We begin by suggesting that research questions should be triangulated to consider not only their scholarly merit but the intellectual and political projects the findings will advance and the research questions of interest to community and social movement collaborators

Nonstructural carbohydrates in tall fescue cultivars: Relationship to animal preference

Grazing animals prefer some plants to others. These choices are likely related to physical and chemical factors such as energy-dense carbohydrates contained in plants. This study quantified the nonstructural carbohydrate fractions in each of eight vegetatively growing, endophyte-free, tall fescue cultivars (Festuca arundinacea Schreb.) and relates their sugar concentrations to cattle grazing preferences. The experimental area consisted of eight cultivar plots replicated three times in each of three pastures. Within each pasture, forage was sampled between 0830 and 1000 h mountain daylight time (MDT) during each of four seasons and 2 yr. Freeze-dried forage samples were extracted with hot water and an amylase (Clarase) solution. Sugars were quantified colorimetrically using potassium-ferricyanide and glucose-oxidase methods. Cattle grazing preferences among these tall fescue cultivars were related to the concentrations of total nonstructural carbohydrates (TNC) (r2 = 0.49, P < 0.05). Other sugar fractions were not significantly related to grazing preference in this study. The nonstructural carbohydrate concentrations averaged over the entire study were glucose, 14; fructose, 5; sucrose, 40; fructan, 23; insoluble starch, 24; and TNC, 129 g kg-1. A forage selection criterion should include measures of the TNC because of their close relationship to animal grazing preference

Evaluating the long-term effectiveness of school-based depression, anxiety, and substance use prevention into young adulthood: Protocol for the climate school combined study

Background: Mental health and substance use disorders are the leading causes of global disability in children and youth. Both tend to first onset or escalate in adolescence and young adulthood, calling for effective prevention during this time. The Climate Schools Combined (CSC) study was the first trial of a Web-based combined universal approach, delivered through school classes, to prevent both mental health and substance use problems in adolescence. There is also limited evidence for the cost-effectiveness of school-based prevention programs. Objective: The aim of this protocol paper is to describe the CSC follow-up study, which aims to determine the long-term efficacy and cost-effectiveness of the CSC prevention program for depression, anxiety, and substance use (alcohol and cannabis use) up to 7 years post intervention. Methods: A cluster randomized controlled trial (the CSC study) was conducted with 6411 participants aged approximately 13.5 years at baseline from 2014 to 2016. Participating schools were randomized to 1 of 4 conditions: (1) control (health education as usual), (2) Climate Substance Use (universal substance use prevention), (3) Climate Mental Health (universal mental health prevention), or (4) CSC (universal substance use and mental health prevention). It was hypothesized that the CSC program would be more effective than conditions (1) to (3) in reducing alcohol and cannabis use (and related harms), anxiety, and depression symptoms as well as increasing knowledge related to alcohol, cannabis, anxiety, and depression. This long-term study will invite follow-up participants to complete 3 additional Web-based assessments at approximately 5, 6, and 7 years post baseline using multiple sources of locator information already provided to the research team. The primary outcomes include alcohol and cannabis use (and related harms) and mental health symptoms. An economic evaluation of the program will also be conducted using both data linkage as well as self-report resource use and quality of life measures. Secondary outcomes include self-efficacy, social networks, peer substance use, emotion regulation, and perfectionism. Analyses will be conducted using multilevel mixed-effects models within an intention-to-treat framework. Results: The CSC long-term follow-up study is funded from 2018 to 2022 by the Australian National Health and Medical Research Council (APP1143555). The first follow-up wave commences in August 2018, and the results are expected to be submitted for publication in 2022. Conclusions: This is the first study to provide a long-term evaluation of combined universal substance use and mental health prevention up to 7 years post intervention. Evidence of sustained benefits into early adulthood would provide a scalable, easy-to-implement prevention strategy with the potential for widespread dissemination to reduce the considerable harms, burden of disease, injury, and social costs associated with youth substance use and mental disorders