9 resultados para measuring productivity

em Brock University, Canada


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How does fire affect the plant and animal community of the boreal forest? This study attempted to examine the changes in plant composition and productivity, and small mammal demography brought about by fire in the northern boreal environment at Chick Lake, N.W.T. (65053fN, 128°14,W). Two 5*6 ha plots measuring 375m x 150m were selected for study during the summers of 1973 and 197^. One had been unburned for 120 years, the other was part of a fire which burned in the spring of 1969. Grids of 15m x 15m were established in each plot and meter square quadrats taken at each of the 250 grid intersections in order to determine plant composition and density. Aerial primary production was assessed by clipping and drying 80 samples of terminal new production for each species under investigation. Small mammal populations were sampled by placing a Sherman live trap at each grid intersection for ten days in every month. The two plots were similar in plant species composition which suggested that most regrowth in the burned area was from rootstocks which survived the fire. The plant data were submitted to a cluster analysis that revealed nine separate species associations, six of which occured in the burned area and eight of which occured in the control. These were subsequently treated as habitats for purposes of comparison with small mammal distributions. The burned area showed a greater productivity in flowers and fruits although total productivity in the control area was higher due to a large contribution from the non-vascular component. Maximum aerial productivity as dry wieght was measured at 157.1 g/m and 207.8 g/m for the burn and control respectively. Microtus pennsylvanicus and Clethrionomys rutilus were the two most common small mammals encountered; Microtus xanthognathus, Synaptomys borealis, and Phenacomys intermedius also occured in the area. Populations of M. pennsylvanicus and C. rutilus were high during the summer of 1973; however, M. pennsylvanicus was rare on the control but abundant on the burn, while C. rutilus was rare on the burn but abundant in the control. During the summer of 197^ populations declined, with the result that few voles of any species were caught in the burn while equal numbers of the two species were caught in the control. During the summer of 1973 M. pennsylvanicus showed a positive association to the most productive habitat type in the burn which was avoided by C. rutilus. In the control £• rutilus showed a similar positive association to the most productive habitat type which was avoided by M. pennsylvanicus. In all cases for the high population year of 1973# the two species never overlapped in habitat preference. When populations declined in 197^f "both species showed a strong association for the most productive habitat in the control. This would suggest that during a high population year, an abundant species can exclude competitors from a chosen habitat, but that this dominance decreases as population levels decrease. It is possible that M. pennsylvanicus is a more efficient competitor in a recently burned environment, while C. rutilus assumes this role once non-vascular regrowth becomes extensive.

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A naturally occurring population of photosynthetic bacteria, located in the meromictic Crawford Lake, was examined during two field seasons (1979-1981). Primary production, biomass, light intensity, lake transparency, pH and bicarbonate concentration were all monitored during this period at selected time intervals. Analysis of the data indicated that (l4C) bacterial photosynthesis was potentially limited by the ambient bicarbonate concentration. Once a threshold value (of 270 mg/l) was reached a dramatic (2 to 10 fold) increase in the primary productivity of the bacteria was observed. Light intensity appeared to have very little effect on the primary productivity of the bacteria, even at times when analyses by Parkin and Brock (1980a) suggested that light intensity could be limiting (i.e., 3.0-5.0 ft. candles). Shifts in the absorption maxima at 430 nrn of the .bacteriochlorophyll spectrum suggested that changes in the species or strain composition of the photosynthetic bacteria had occurred during the summer months. It was speculated that these changes might reflect seasonal variation in the wavelength of light reaching the bacteria. Chemocline erosion did not have the same effect on the population size (biomass) of the photosynthetic bacteria in Crawford Lake (this thesis) as it did in Pink Lake (Dickman, 1979). In Crawford Lake the depth of the chemocline was lowered with no apparent loss in biomass (according to bacteriochlorophyll data). A reverse current was. proposed to explain the observation. The photosynthetic bacteria contributed a significant proportion (10-60%) of the lake1s primary productivitya Direct evidence was obtained with (14C) labelling of the photosynthetic bacteria, indica.ting that the zooplankton were grazing the photosynthetic bacteria. This indicated that some of the photosynthetic bacterial productivity was assimilated into the food chain of the lake. Therefore, it was concluded that the photosynthetic bacteria made a significant contribution to the total productivity of Crawford Lake.

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This study \Alas initiated in response to the Junior Division Review (1985) publ ished by the Ministry of Education for the Province of Ontario. Curriculum integration is an element used within the educational paradigm designed by the Ontario Ministry of Education. It is a term frequent1y verbal ized b>' educators in this province, but because of 1 imi ted resource support regarding this methodology, it was open to broad interpretation resulting in an extreme v ar i at i on i nit simp 1 eme n tat i on • I n de ed, the Min i s try intimated that it was not occurring to any significant degree across the province. The objective of this thes is was· to define integration in the junior classroom and de-:.ign a meas.ur·ement in-:.tr-ument which would in turn high 1 i gh t indicators of curriculum integration. The :.tudy made a prel iminary, field-based survey of educa tiona 1 professionals in order to generate a relevant description of integrated curr-iculum programm i ng as def i ned in the j un i or classroom. The description was a compilation of views expressed by a random selection of teachers, consultants, supervisory officers and principals. The survey revea 1 ed a much more comprehens i ve vi et·<,l of the attributes of integrated programming than tradition would dictate and resulted in a functional definition tha t was broader than past prac t ices. Based on the information generated by this survey, an instrument ou t 1 in i ng program cr iter i a of was devised. an integrated junior cla~·sroom Th i s measuremen t i nstrumen t , designed for all levels of educators, was named uThe Han~.son I nstrumen t for the Measuremen t of Program Integrat ion in the Jun i or Cl assroom". It refl ected five categories intrinsic to the me thodol ogy of integration: Teacher Behaviour, Student Behaviour, Classroom Layout, Cl as~·r oom Environment and Progr amm i ng. Each category and the items therein were successfully tested in val idi ty and rel iabi 1 i ty checKs. Interestingly, the individual class was found to be the major variable programming in in the measuremen t the j un i or d i vis i on • of The integrated instrument demonstrated potential not onl)' a~· an initial measure of the degree of integrated curriculum, but as a guide to strategies to implement such a methodology.

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As the complexity of evolutionary design problems grow, so too must the quality of solutions scale to that complexity. In this research, we develop a genetic programming system with individuals encoded as tree-based generative representations to address scalability. This system is capable of multi-objective evaluation using a ranked sum scoring strategy. We examine Hornby's features and measures of modularity, reuse and hierarchy in evolutionary design problems. Experiments are carried out, using the system to generate three-dimensional forms, and analyses of feature characteristics such as modularity, reuse and hierarchy were performed. This work expands on that of Hornby's, by examining a new and more difficult problem domain. The results from these experiments show that individuals encoded with those three features performed best overall. It is also seen, that the measures of complexity conform to the results of Hornby. Moving forward with only this best performing encoding, the system was applied to the generation of three-dimensional external building architecture. One objective considered was passive solar performance, in which the system was challenged with generating forms that optimize exposure to the Sun. The results from these and other experiments satisfied the requirements. The system was shown to scale well to the architectural problems studied.

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Abstract A total of 378 grade 9 students participated in this study to address the problem that although metaphorical literacy and thought are expected and necessary for success in junior and senior high school and beyond, metaphorical concepts and thought are not required to be explicitly taught to these students. The students were from 20 different classes from 4 levels: English language learners (ELL), school to work (SSTW), applied, and academic. All were from 7 secondary schools within a board in southern Ontario. Nine classes made up the control group and 11 classes made up the treatment group. All classes were given 3 pretests and the posttest. The treatment group was given Socratic lessons and direct instruction on metaphorical thought and expressions during 1 semester and in conjunction with their other classroom material. The pretest scores (TOLD, Peabody, preproverbs concrete, and preproverbs abstract) did not reveal any effect of gender, but the academic students had higher scores than the applied students. The SSTW student results are more variable: (a) for the TOLD test, SSTW scores were between those of the academic and applied students; (b) for Peabody scores, SSTW students’ scores are the same as academic and are greater than applied; (c) for preproverbs concrete and preproverbs abstract, the SSTW scores are not different from the applied scores. The postproverbs concrete and postproverbs abstract scores for the treatment groups also showed no effect of gender but revealed that all students who received the treatment did better on their post scores. The positive changes of the treatment group illustrate a measured movement from literal understanding to abstract understanding using direct Socratic instruction and proverbs as a medium.

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The article focuses on stress factors, which include: Genetic Background, Individual Differences, Past Experiences. The conclusion of the article states "reducing handling stress of animals will improve their weight gain, reproductive performance, and ability to resist disease".

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Printed blank by which John Brown Cullen solemnly declares that he is experienced in the art of measuring and culling timber. He states that he is entering into the service of Burton and Bro. of Barrie He will make out the specification of the timber in berths 192 and 198 and submit his findings to Burton and Brother, Oct. 22, 1877.

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Map measuring 28 cm. x 24 cm. showing the Walter H. Dickson land along the road from Blenheim, n.d.