915 research outputs found
Design study for Thermal Infrared Multispectral Scanner (TIMS)
The feasibility of dividing the 8-12 micrometer thermal infrared wavelength region into six spectral bands by an airborne line scanner system was investigated. By combining an existing scanner design with a 6 band spectrometer, a system for the remote sensing of Earth resources was developed. The elements in the spectrometer include an off axis reflective collimator, a reflective diffraction grating, a triplet germanium imaging lens, a photoconductive mercury cadmium telluride sensor array, and the mechanical assembly to hold these parts and maintain their optical alignment across a broad temperature range. The existing scanner design was modified to accept the new spectrometer and two field filling thermal reference sources
Omstreden instituties: Instellingen in een geindividualiseerde samenleving
Although today's western societies are commonly characterized as highly individualized, two institutional consequences have hardly been addressed yet. They are therefor the focus of this issue of the Sociologisch Gids. First, it is studied how political parties and churches, two former 'peak institutions' that almost by themselves used to control an entire life domain, adjust to the newly emerged circumstances. Second, it is studied what behavioral patterns emerge within the political and religious domains to fill the void left by the decline of those peak institutions. By way of introduction to the four papers that address those two questions for the Low Countries, this introduction discusses the principal changes that have occured within both realms and the moral controversies that institutional decline and change inevitably gives rise to
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Letting wildfires burn : modeling the change in future suppression costs as the result of a suppress versus a let-burn management choice
Wildfire management policy over the past century, which attempts to exclude fire from fire-adapted ecosystems, has led to a build-up of fuels across the western United States. As a result, current wildfires contain larger areas of high severity, high intensity burns than seen prior to the policy implementation. There are three leading methods for dealing with this build-up of fuels. The first two, mechanical thinning and prescribed fire, are techniques used to enter an ecosystem and reduce the fuel loads in a specific area. Either can cost anywhere from a few hundred to several thousand dollars per hectare. The third method, wildland fire use, is comparatively cheap, while maintaining the benefit of reduced current and future suppression costs. However, it is commonly over-looked, in part because the fire management officer who allows a wildfire to spread when it could have been suppressed can be held liable for damage to property and loss of life, should such events occur.
In this thesis, I describe a method for estimating the future suppression cost savings that result from allowing a fire that occurs in the current year to burn. It was hypothesized that under some known, current conditions, given a random selection of future ignitions and weather, the present value of a landscape would be higher given that a fire in the current year was allowed to burn, rather than suppressed.
A computer program was used to simulate 100-year sample pathways, which included fire and growth events, on a study area in the southeastern Deschutes National Forest. Based on avoided suppression costs, and a crude estimate of timber losses, some of these potential futures demonstrated a higher present value of the landscape resulting from the let-burn management choice. Size of the current fire was the most important characteristics of a given sample pathway in determining the magnitude of the change in future suppression costs. As the size of the current fire increased, the benefit from the sample pathway also increased.
In the future, this analysis can be used as a framework for exploring questions pertaining to the use of weather, fuel, and ignition characteristics of current fires to determine when an ignition should be suppressed, and when it might be advantageous to let a fire burn
Effect-Directed Analysis of Municipal Landfill Soil Reveals Novel Developmental Toxicants in the Zebrafish Danio rerio
Effect-directed analysis (EDA) is an approach used to identify (unknown) contaminants in complex samples which cause toxicity, using a combination of biology and chemistry. The goal of this work was to apply EDA to identify developmental toxicants in soil samples collected from a former municipal landfill site. Soil samples were extracted, fractionated, and tested for developmental effects with an embryotoxicity assay in the zebrafish Danio rerio. Gas chromatograph mass selective detection (GC-MSD) chemical screening was used to reveal candidate developmental toxicants in fractions showing effects. In a parallel study, liquid chromatography-hybrid linear ion trap Orbitrap mass spectrometry was also applied to one polar subfraction (Hoogenboom et al. J. Chromatogr. A2009, 1216, 510-519). EDA resulted in the identification of a number of previously unknown developmental toxicants, which were confirmed to be present in soil by GC-MS. These included 11H-benzo[b]fluorene, 9-methylacridine, 4-azapyrene, and 2-phenylquinoline, as well as one known developmental toxicant (retene). This work revealed the presence of novel contaminants in the environment that may affect vertebrate development, which are not subject to monitoring or regulation under current soil quality assessment guidelines. © 2011 American Chemical Society
Testing Consumer Rationality using Perfect Graphs and Oriented Discs
Given a consumer data-set, the axioms of revealed preference proffer a binary
test for rational behaviour. A natural (non-binary) measure of the degree of
rationality exhibited by the consumer is the minimum number of data points
whose removal induces a rationalisable data-set.We study the computational
complexity of the resultant consumer rationality problem in this paper. This
problem is, in the worst case, equivalent (in terms of approximation) to the
directed feedback vertex set problem. Our main result is to obtain an exact
threshold on the number of commodities that separates easy cases and hard
cases. Specifically, for two-commodity markets the consumer rationality problem
is polynomial time solvable; we prove this via a reduction to the vertex cover
problem on perfect graphs. For three-commodity markets, however, the problem is
NP-complete; we prove thisusing a reduction from planar 3-SAT that is based
upon oriented-disc drawings
High resolution effect-directed analysis of steroid hormone (ant)agonists in surface and wastewater quality monitoring
Monitoring of chemical water quality is extremely challenging due to the large variety of compounds and the presence of biologically active compounds with unknown chemical identity. Previously, we developed a high resolution Effect-Directed Analysis (EDA) platform that combines liquid chromatography with high resolution mass spectrometry and parallel bioassay detection. In this study, the platform is combined with CALUX bioassays for (anti)androgenic, estrogenic and glucocorticoid activities, and the performance of the platform is evaluated. It appeared to render very repeatable results, with high recoveries of spiked compounds and high consistency between the mass spectrometric and bioassay results. Application of the platform to wastewater treatment plant effluent and surface water samples led to the identification of several compounds contributing to the measured activities. Eventually, a workflow is proposed for the application of the platform in a routine monitoring context. The workflow divides the platform into four phases, of which one to all can be performed depending on the research question and the results obtained. This allows one to make a balance between the effort put into the platform and the certainty and depth by which active compounds will be identified. The EDA platform is a valuable tool to identify unknown bioactive compounds, both in an academic setting as in the context of legislative, governmental or routine monitoring
Histological Chages of Testis and Caput Epididymis in the Goat after Cannulation of the Rete Testis
雄ヤギ5頭を用い, 精巣網カテーテル装着手術後の精巣および精巣上体頭の組織構造を観察するとともに精巣静脈血中のテストステロン濃度を調べた。カテーテル装着手術後の精巣は, いずれも萎縮し, 正常な精子形成過程が観察される精細管は少なかった。また, ライディヒ細胞の形態や染色性には異常は認められなかった。一方, 精巣上体頭では, 精巣上体管が萎縮し, 主細胞の高さは無傷のものよりも有意に減少した。同様の組織構造の変化は, 精巣輸出管を切除した場合の精巣および精巣上体頭でも認められた。精巣静脈血中のテストステロン濃度は無傷の場合94.4ng/mlであり, カテーテル装着手術後では86.5∿342.8ng/mlであった。 / The testis and caput epididymis of the goat after cannulation of the rete testis or efferentiectomy were examined histologically. The concentration of testosterone in testicular venous blood collected from the same animals was also measured by radioimmunoassay. After cannulation, seminiferous tubules showed a sign of degeneration, although no morphological change of Leydig cells was observed. Epididymal ducts were severely atrophied and the height of principal epithelial cells was significantly decreased. A similar damage was observed in the testis and epididymis after efferentiectomy. When the efferent duct bundle had been incompletely ligated at cannulation, or rete testis catheter was kept in place until sampling time, damages in the testis were less severe. And in the former case the epididymis was impaired less severely. The concentration of testosterone in testicular venous blood collected from an intact animal was 94.4ng/ml, while that obtained after cannulation was 86.5-342.8ng/ml. These results suggest that degeneration of germ cells in seminiferous tubules observed after cannulation of the rete testis or efferentiectomy may be caused by stagnation of rete testicular fluid in the tubules, and that testosterone in the fluid plays important roles in the maintenance of morphology and function of the principal cells in the caput epididymis
Decreasing employees' work stress by a participatory, organizational level work stress prevention approach: a multiple-case study in primary education
BACKGROUND: Work stress is an important problem among employees in education in the Netherlands. The present study aims to investigate the effects of a participatory organizational level work stress prevention approach to reduce (quantitative) job demands, increase resources (i.e. autonomy, supervisor and coworker support) and to re
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