12,301 research outputs found
Why the most risk averse people sometimes take the riskiest decisions:A perspective from psychology
Where the Rivers Flow
Philip Thomas présente quelques chants en relation avec les rivières de la Colombie Canadienne e t commente à propos de l’origine historique et des variations du chant “Where the Fraser River Flows”, chant que Joe Hill a écrit pour les travailleurs du chemin de fer alors en grève en 1912
The “Louis Riel Song”: A Perspective
Philip J. Thomas rend compte de différentes versions de la “chanson de Louis Riel, ” depuis l’enregistrement commercial et la parution du livre de Barbara Cass-Beggs (1963) ju squ’au début des années 80 alors qu’il l’entendait chantée par Joe Venne sur les ondes de CBC-AM; selon Donald Deschênes et Charlotte Cormier, cette chanson serait une variante de “Lettre de sang ” connue dans l’ensemble du Canada français. Thomas compare les thèmes de 29 interprétations de cette chanson afin d’en mieux saisir l’histoire de sa migration (cf. l’article de Deschênes plus haut)
Determination of renewable energy yield from mixed waste material from the use of novel image analysis methods
Two novel techniques are presented in this study which together aim to provide a system able to determine the renewable energy potential of mixed waste materials. An image analysis tool was applied to two waste samples prepared using known quantities of source-segregated recyclable materials. The technique was used to determine the composition of the wastes, where through the use of waste component properties the biogenic content of the samples was calculated. The percentage renewable energy determined by image analysis for each sample was accurate to within 5% of the actual values calculated. Microwave-based multiple-point imaging (AutoHarvest) was used to demonstrate the ability of such a technique to determine the moisture content of mixed samples. This proof-of-concept experiment was shown to produce moisture measurement accurate to within 10%. Overall, the image analysis tool was able to determine the renewable energy potential of the mixed samples, and the AutoHarvest should enable the net calorific value calculations through the provision of moisture content measurements. The proposed system is suitable for combustion facilities, and enables the operator to understand the renewable energy potential of the waste prior to combustion
Analysis of Nitrogen Loading Reductions for Wastewater Treatment Facilities and Non-Point Sources in the Great Bay Estuary Watershed
In 2009, the New Hampshire Department of Environmental Services (DES) published a proposal for numeric nutrient criteria for the Great Bay Estuary. The report found that total nitrogen concentrations in most of the estuary needed to be less than 0.3 mg N/L to prevent loss of eelgrass habitat and less than 0.45 mg N/L to prevent occurrences of low dissolved oxygen. Based on these criteria and an analysis of a compilation of data from at least seven different sources, DES concluded that 11 of the 18 subestuaries in the Great Bay Estuary were impaired for nitrogen. Under the Clean Water Act, if a water body is determined to be impaired, a study must be completed to determine the existing loads of the pollutant and the load reductions that would be needed to meet the water quality standard. Therefore, DES developed models to determine existing nitrogen loads and nitrogen loading thresholds for the subestuaries to comply with the numeric nutrient criteria. DES also evaluated the effects of different permitting scenarios for wastewater treatment facilities on nitrogen loads and the costs for wastewater treatment facility upgrades. This modeling exercise showed that: Nitrogen loads to the Great Bay, Little Bay, and the Upper Piscataqua River need to be reduced by 30 to 45 percent to attain the numeric nutrient criteria. Both wastewater treatment facilities and non-point sources will need to reduce nitrogen loads to attain the numeric nutrient criteria. The percent reduction targets for nitrogen loads only change minimally between wet and dry years. Wastewater treatment facility upgrades to remove nitrogen will be costly; however, the average cost per pound of nitrogen removed from the estuary due to wastewater facility upgrades is lower than for non-point source controls. The permitting options for some wastewater treatment facilities will be limited by requirements to not increase pollutant loads to impaired waterbodies. The numeric nutrient criteria and models used by DES are sufficiently accurate for calculating nitrogen loading thresholds for the Great Bay watershed. Additional monitoring and modeling is needed to better characterize conditions and nitrogen loading thresholds for the Lower Piscataqua River. This nitrogen loading analysis for Great Bay may provide a framework for setting nitrogen permit limits for wastewater treatment facilities and developing watershed implementation plans to reduce nitrogen loads
Determining the Properties and Evolution of Red Galaxies from the Quasar Luminosity Function
(Abridged) We study the link between quasars and the red galaxy population
using a model for the self-regulated growth of supermassive black holes in
mergers involving gas-rich galaxies. Using a model for quasar lifetimes and
evolution motivated by hydrodynamical simulations of galaxy mergers, we
de-convolve the observed quasar luminosity function at various redshifts to
determine the rate of formation of black holes of a given final mass.
Identifying quasar activity with the formation of spheroids in the framework of
the merger hypothesis, this enables us to deduce the corresponding rate of
formation of spheroids with given properties as a function of redshift. This
allows us to predict, for the red galaxy population, the distribution of galaxy
velocity dispersions, the mass function, mass density, star formation rates,
the luminosity function in many observed wavebands (NUV, U, B, V, R, I, J, H,
K), the total red galaxy number density and luminosity density, the
distribution of colors as a function of magnitude and velocity dispersion for
several different wavebands, the distribution of mass to light ratios vs. mass,
the luminosity-size relations, and the typical ages and distribution of ages
(formation redshifts) as a function of both mass and luminosity. For each of
these quantities, we predict the evolution from redshift z=0-6. Each of our
predictions agrees well with existing observations, without the addition of
tunable parameters; the essential observational inputs come from the observed
quasar luminosity function. These predictions are skewed by several orders of
magnitude if we adopt simpler, traditional models of quasar lifetimes in which
quasars turn on/off or follow simple exponential light curves, instead of the
more complicated evolution implied by our simulations.Comment: 28 pages, 22 figures, matches version accepted to Ap
Pencil-Beam Surveys for Faint Trans-Neptunian Objects
We have conducted pencil-beam searches for outer solar system objects to a
limiting magnitude of R ~ 26. Five new trans-neptunian objects were detected in
these searches. Our combined data set provides an estimate of ~90
trans-neptunian objects per square degree brighter than ~ 25.9. This estimate
is a factor of 3 above the expected number of objects based on an extrapolation
of previous surveys with brighter limits, and appears consistent with the
hypothesis of a single power-law luminosity function for the entire
trans-neptunian region. Maximum likelihood fits to all self-consistent
published surveys with published efficiency functions predicts a cumulative sky
density Sigma(<R) obeying log10(Sigma) = 0.76(R-23.4) objects per square degree
brighter than a given magnitude R.Comment: Accepted by AJ, 18 pages, including 6 figure
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