2,632 research outputs found
The relationships between reaction-time, the span of visual apprehension, depth perception, and selected items of a basketball skills test
Thesis (Ed.M.)--Boston Universit
The construction and evaluation of a health vocabulary test for grades four, five, and six
Thesis (Ed.D.)--Boston Universit
Nonequilibrium Green's function theory for nonadiabatic effects in quantum electron transport
We develop nonequilibribrium Green's function based transport theory, which
includes effects of nonadiabatic nuclear motion in the calculation of the
electric current in molecular junctions. Our approach is based on the
separation of slow and fast timescales in the equations of motion for the
Green's functions by means of the Wigner representation. Time derivatives with
respect to central time serves as a small parameter in the perturbative
expansion enabling the computation of nonadiabatic corrections to molecular
Green's functions. Consequently, we produce series of analytic expressions for
non-adiabatic electronic Green's functions (up to the second order in the
central time derivatives); which depend not solely on instantaneous molecular
geometry but likewise on nuclear velocities and accelerations. Extended formula
for electric current is derived which accounts for the non-adiabatic
corrections. This theory is concisely illustrated by the calculations on a
model molecular junction
Vegetation Response to a Subsurface Crude Oil Spill on a Subarctic Right-of-way, Tulita (Fort Norman), Northwest Territories, Canada
The plant species on a simulated pipeline corridor near Tulita (Fort Norman), Northwest Territories were studied prior to and for three years after an experimental point-spill of 3273 L (20 imperial barrels) of crude oil. Two distinct environments were examined: a cleared right-of-way (ROW) and a simulated pipeline trench. Each environment was subdivided on the basis of oil concentration into heavily oiled, lightly oiled, and unoiled sections. Total plant cover on the heavily oiled ROW declined by 73% in the first growing season; however, significant recovery took place in subsequent years. All other oiled environments had significant increases in total plant cover, but not until at least the second year after the spill. Of the 34 taxa identified, 13 declined significantly in abundance by the third growing season after the oil spill, mainly on the heavily oiled ROW. By the third post-spill growing season, mosses, Carex spp., Eriophorum spp., and agronomic grasses (Alopecurus arundinacea, Phleum pratense, Poa glauca and P. pratensis) had increased in abundance on at least one type of oiled substrate. However, the agronomic grasses, species sown on the Norman Wells pipeline, also declined significantly on the heavily oiled Trench. In contrast, the native grass Arctagrostis latifolia declined only on the heavily oiled ROW.On a étudié les espèces végétales présentes sur un corridor pipelinier simulé près de Tulita (Fort Norman), dans les Territoires du Nord-Ouest, avant un déversement expérimental ponctuel de pétrole brut de 3273 L (soit 20 barils impériaux) et durant les trois années suivantes. On a examiné deux environnements distincts: une emprise dégagée et une tranchée simulée de pipeline. On a divisé chaque environnement en sections en se basant sur la concentration en pétrole: forte, faible et nulle. Durant la première saison de croissance, l'ensemble du couvert végétal a diminué de 73 p. cent sur les sections de l'emprise où existait une forte concentration; un important reverdissement a toutefois pris place durant les années suivantes. Tous les autres endroits qui avaient reçu du pétrole ont connu d'importantes augmentations de l'ensemble du couvert végétal, mais, au plus tôt, à partir de la deuxième année suivant le déversement. Sur les 34 taxons identifiés, 13 avaient largement diminué en abondance à la troisième saison de croissance suivant le déversement, surtout dans les sections de l'emprise à forte concentration de pétrole. À la troisième saison de croissance suivant le déversement, les mousses des espèces Carex et Eriophorum et les herbes agronomiques (Alopecurus arundinacea, Phleum pratense, Poa glauca et P. pratensis) avaient augmenté en abondance à au moins un type de milieu où avait été déversé du pétrole. Toutefois, les herbes agronomiques - espèces semées sur le parcours du pipeline de Norman Wells - avaient aussi diminué de façon significative sur la tranchée où se trouvait une forte concentration de pétrole. Par contre, l'herbe indigène Arctagrostis latifolia n'avait diminué que sur l'emprise à forte concentration
Conditioning of Human Salivary Flow Using a Visual Cue for Sour Candy
Objective Although the “mouthwatering” to sight, smell, or thought of food is commonly accepted in food and nutrition research, the concept of mouthwatering and human salivary flow conditioning is not well accepted in salivary research. The objective of this study was to revisit whether human salivary flow could be classically conditioned to a previously neutral stimulus. Design Sour candy or a non-food control in opaque containers were presented to healthy participants (n = 8). Simple images were consistently paired with container contents. Participants viewed the images for 15 s, then opened the containers and ate (candy) or did not eat (non-food control) the contents. This was repeated 14 times (7 of each stimulus). Order was semi-randomized to ensure one candy and one non-food were presented as the first two and last two stimuli. Saliva was collected with cotton dental rolls during these presentations (first two and last two) after viewing the image for 15 s, but before opening the container. Results Participants were successfully conditioned to increase salivary flow in response to the image that predicted candy, as demonstrated by greater weight of saliva in response to 1) the candy-paired image than the non-food-paired image, and 2) the candy-paired image at the end of the first visit compared with the beginning (when the image had no meaning). However, the effect was attenuated during the second visit. Conclusions We demonstrate classical conditioning of human salivary flow is achievable, but the effect may not persist to a second visit
Dose–response functions and methodological insights for sensory tests with astringent stimuli
Sensations such as bitterness and astringency can limit the acceptance of many purportedly healthy foods. The purpose of this study was to investigate dose–response relationships of various astringent and bitter stimuli in a beverage, and to simultaneously gain additional methodological insight for the effects of wording, repeated tasting, and beverage matrix on these sensations. Untrained participants were presented with samples of a “flavored beverage” or water containing various concentrations of four stimuli (alum, malic acid, tannic acid, and quinine) and were asked to rate intensities of tastes (bitterness, sourness, and sweetness) and astringency subqualities (roughing, drying, and constricting or puckering) using a generalized visual analog scale. Using constricting in place of puckering had no effect on ratings. The effects of repeated tasting and beverage matrix on astringency perception were stimulus‐dependent. This study informs future investigations to understand the psychophysics of tastes and astringency
Pollution in the open oceans: 2009-2013
This review of pollution in the open oceans updates a report on this topic prepared by GESAMP five years previously (Reports and Studies No. 79, GESAMP, 2009). The latter report, the first from GESAMP focusing specifically on the oceans beyond the 200 m depth contour, was prepared for purposes of the Assessment of Assessments, the preparatory phase of a regular process for assessing the state of the marine environment, led jointly by the United Nations Environment Programme (UNEP) and the Intergovernmental Oceanographic Commission (UNESCO-IOC)
Performing heritage: the use of live 'actors' in heritage presentations
This paper investigates the phenomenon of 'living history' presentations of heritage, using live 'actors' to portray historical characters. Its aim is to discuss these presentations in the context of what may be understood as 'heritage', and of the nature of 'performance'. Four case studies of heritage sites, each important as a tourist attraction, have been selected for detailed study, together with a number of other examples of heritage performance. It is clear from the empirical work that different performance strategies are employed within the heritage industry and by individual 'actors'. Most of the performers take part as a leisure activity, and many do not consider themselves to be 'performing' at all. The greatest concern of participants lies in the degree of authenticity of the performance. Through 'living history', the 'actors' are drawn into an experience of heritage which has real meaning for them, and which may contribute both to a sense of identity and to an enhanced understanding of society, past and present. The popularity of such presentations with visitors also indicates that similar benefits are perceived by the 'audience'
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