13 resultados para Short-selling restrictions

em Brock University, Canada


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Matings systems using signals for sexual communication have been studied extensively and results commonly suggest that females use these signals for locating males, species-identification, and mate choice. Although numerous mating systems employ multiple signals, research has generally focused on long-range signals perhaps due to their prominence and ease of study. This study focused on the short-range acoustic courtship song of crickets. The results presented here suggest this signal is under selection by female choice. Females mated preferentially with males having shorter silences between the two types of ticks within the song. The length of these silences (Gap 1) was correlated with male condition such that males having long silences were significantly lower in mass with respect to body size when compared to males having short silences. Both Gap 1 length and male condition were significantly repeatable within males over time suggesting the possibility these traits have a genetic basis. This study is the first empirical study to test female preferences within the natural variation of the courtship song. It now appears, at least in crickets, that both the longand short-range signals of a multi-signal mating system may contribute to male mating success.

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Traditional psychometric theory and practice classify people according to broad ability dimensions but do not examine how these mental processes occur. Hunt and Lansman (1975) proposed a 'distributed memory' model of cognitive processes with emphasis on how to describe individual differences based on the assumption that each individual possesses the same components. It is in the quality of these components ~hat individual differences arise. Carroll (1974) expands Hunt's model to include a production system (after Newell and Simon, 1973) and a response system. He developed a framework of factor analytic (FA) factors for : the purpose of describing how individual differences may arise from them. This scheme is to be used in the analysis of psychometric tes ts . Recent advances in the field of information processing are examined and include. 1) Hunt's development of differences between subjects designated as high or low verbal , 2) Miller's pursuit of the magic number seven, plus or minus two, 3) Ferguson's examination of transfer and abilities and, 4) Brown's discoveries concerning strategy teaching and retardates . In order to examine possible sources of individual differences arising from cognitive tasks, traditional psychometric tests were searched for a suitable perceptual task which could be varied slightly and administered to gauge learning effects produced by controlling independent variables. It also had to be suitable for analysis using Carroll's f ramework . The Coding Task (a symbol substitution test) found i n the Performance Scale of the WISe was chosen. Two experiments were devised to test the following hypotheses. 1) High verbals should be able to complete significantly more items on the Symbol Substitution Task than low verbals (Hunt, Lansman, 1975). 2) Having previous practice on a task, where strategies involved in the task may be identified, increases the amount of output on a similar task (Carroll, 1974). J) There should be a sUbstantial decrease in the amount of output as the load on STM is increased (Miller, 1956) . 4) Repeated measures should produce an increase in output over trials and where individual differences in previously acquired abilities are involved, these should differentiate individuals over trials (Ferguson, 1956). S) Teaching slow learners a rehearsal strategy would improve their learning such that their learning would resemble that of normals on the ,:same task. (Brown, 1974). In the first experiment 60 subjects were d.ivided·into high and low verbal, further divided randomly into a practice group and nonpractice group. Five subjects in each group were assigned randomly to work on a five, seven and nine digit code throughout the experiment. The practice group was given three trials of two minutes each on the practice code (designed to eliminate transfer effects due to symbol similarity) and then three trials of two minutes each on the actual SST task . The nonpractice group was given three trials of two minutes each on the same actual SST task . Results were analyzed using a four-way analysis of variance . In the second experiment 18 slow learners were divided randomly into two groups. one group receiving a planned strategy practioe, the other receiving random practice. Both groups worked on the actual code to be used later in the actual task. Within each group subjects were randomly assigned to work on a five, seven or nine digit code throughout. Both practice and actual tests consisted on three trials of two minutes each. Results were analyzed using a three-way analysis of variance . It was found in t he first experiment that 1) high or low verbal ability by itself did not produce significantly different results. However, when in interaction with the other independent variables, a difference in performance was noted . 2) The previous practice variable was significant over all segments of the experiment. Those who received previo.us practice were able to score significantly higher than those without it. J) Increasing the size of the load on STM severely restricts performance. 4) The effect of repeated trials proved to be beneficial. Generally, gains were made on each successive trial within each group. S) In the second experiment, slow learners who were allowed to practice randomly performed better on the actual task than subjeots who were taught the code by means of a planned strategy. Upon analysis using the Carroll scheme, individual differences were noted in the ability to develop strategies of storing, searching and retrieving items from STM, and in adopting necessary rehearsals for retention in STM. While these strategies may benef it some it was found that for others they may be harmful . Temporal aspects and perceptual speed were also found to be sources of variance within individuals . Generally it was found that the largest single factor i nfluencing learning on this task was the repeated measures . What e~ables gains to be made, varies with individuals . There are environmental factors, specific abilities, strategy development, previous learning, amount of load on STM , perceptual and temporal parameters which influence learning and these have serious implications for educational programs .

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On cover: Niagara.

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On leaf preceding t. p.: Who was Isaac Brock?

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It has been well documented, within the field of landscape ecology, that terrestrial fragmentation contributes to increased heterogeneity at the landscape level. It has also been observed that elevated areas of edge habitat occur within fragmented landscapes. Spatial and temporal edge effects were investigated in four areas designated as Nature Reserve Zones within Short Hills Provincial Park, near St. Catharines, Ontario. Random sampling along exposed edges was performed on trees and saplings, at 5 and 25 ill edge depths, using the point-centred quarter method. Diameter at breast height (dbh) and distance from point measurements were used to establish relative density, dominance, frequency and importance value. One-way analyses of variance were used on dbh measurements of tree species and Chi-Square contingency tables were used on size class distributions of saplings species to determine significant differences between 5 and 25 metres. Qualitative comparisons of importance values were also used to determine differences between 5 and 25 metres as well as between trees and saplings. These statistical and qualitative comparisons suggest that a significant overall spatial edge effect is currently exhibited by fragmented wooded islands within the park. The major species of the park, Acersaccharuln, may be exhibiting a temporal edge effect. The heterogeneous nature of the park may be of importance in understanding this area as a complex, ecological system. It is possible that the remaining forest tracts of the park have been affected, and continue to be affected by previous disturbances. Based on these findings, recommendations are made to the Ontario Ministry of Natural Resources concerning the management of Short Hills Provincial Park in accordance with their 1990 proposed Management Plan.

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‘The Father of Canadian Transportation’ is a term commonly associated with William Hamilton Merritt. Although he is most known for being one of the driving forces behind the building of the first Welland Canal, he was many things throughout his life; a soldier, merchant, promoter, entrepreneur and politician to name a few. Born on July 3, 1793 at Bedford, Westchester County, N.Y. to Thomas Merritt and Mary Hamilton, Merritt’s family relocated to Canada shortly after in 1796. The move came after Merritt’s father petitioned John Graves Simcoe for land in Upper Canada after serving under him in the Queen’s Rangers during the American Revolution. The family quickly settled into their life at Twelve Mile Creek in St. Catharines. Merritt’s father became sheriff of Lincoln County in 1803 while Merritt began his education in mathematics and surveying. After some brief travel and further education Merritt returned to Lincoln County, in 1809 to help farm his father’s land and open a general store. While a farmer and merchant, Merritt turned his attention to military endeavours. A short time after being commissioned as a Lieutenant in the Lincoln militia, the War of 1812 broke out. Fulfilling his duty, Merritt fought in the Battle of Queenston Heights in October of 1812, and numerous small battles until the Battle of Lundy’s Lane in July 1814. It was here that Merritt was captured and held in Cheshire, Massachusetts until the war ended. Arriving back in the St. Catharines area upon his release, Merritt returned to being a merchant, as well as becoming a surveyor and mill owner. Some historians hypothesize that the need to draw water to his mill was how the idea of the Welland Canals was born. Beginning with a plan to connect the Welland River with the Twelve mile creek quickly developed into a connection between the Lakes Erie and Ontario. Its main purpose was to improve the St. Lawrence transportation system and provide a convenient way to transport goods without having to go through the Niagara Falls portage. The plan was set in motion in 1818, but most living in Queenston and Niagara were not happy with it as it would drive business away from them. Along with the opposition came financial and political restraints. Despite these factors Merritt pushed on and the Welland Canal Company was chartered by the Upper Canadian Assembly on January 19, 1824. The first sod was turned on November 30, 1824 almost a year after the initial chartering. Many difficulties arose during the building of the canal including financial, physical, and geographic restrictions. Despite the difficulties two schooners passed through the canal on November 30, 1829. Throughout the next four years continual work was done on the canal as it expended and was modified to better accommodate large ships. After his canal was underway Merritt took a more active role in the political arena, where he served in various positions throughout Upper Canada. In 1851, Merritt withdrew from the Executive Council for numerous reasons, one of which being that pubic interest had diverted from the canals to railways. Merritt tried his hand at other public works outside transportation and trade. He looked into building a lunatic asylum, worked on behalf of War of 1812 veterans, aided in building Brock’s monument, established schools, aided refugee slaves from the U.S. and tried to establish a National Archives among many other feats. He was described by some as having “policy too liberal – conceptions too vast – views too comprehensive to be comprehensible by all”, but he still made a great difference in the society in which he lived. After his great contributions, Merritt died aboard a ship in the Cornwall canal on July 5, 1862. Dictionary of Canadian Biography Online http://www.biographi.ca/EN/ShowBio.asp?BioId=38719 retrieved October 2006 Today numerous groups carry on the legacy of Merritt and the canals both in the past and present. One such group is the Welland Canals Foundation. They describe themselves as: “. . . a volunteer organization which strives to promote the importance of the present and past Welland Canals, and to preserve their history and heritage. The Foundation began in 1980 and carries on events like William Hamilton Merritt Day. The group has strongly supported the Welland Canals Parkway initiative and numerous other activities”. The Welland Canals Foundation does not work alone. They have help from other local groups such as the St. Catharines Historical Society. The Society’s main objective is to increase knowledge and appreciation of the historical aspects of St. Catharines and vicinity, such as the Welland Canals. http://www.niagara.com/~dmdorey/hssc/dec2000.html - retrieved Oct. 2006 http://www.niagara.com/~dmdorey/hssc/feb2000.html - retrieved Oct. 2006

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On leaf preceding t. p.: Who was Isaac Brock? Printed by Clarke

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Memory is a multi-component cognitive ability to retain and retrieve information presented in different modalities. Research on memory development has shown that the memory capacity and the processes improve gradually from early childhood to adolescence. Findings related to the sex-differences in memory abilities in early childhood have been inconsistent. Although previous research has demonstrated the effects of the modality of stimulus presentation (auditory versus verbal) and the type of material to be remembered (visual/spatial versus auditory/verbal) on the memory processes and memory organization, the recent research with children is rather limited. The present study is a secondary analysis of data, originally collected from 530 typically developing Turkish children and adolescents. The purpose of the present study was to examine the age-related developments and sex differences in auditory-verbal and visual-spatial short-term memory (STM) in 177 typically developing male and female children, 5 to 8 years of age. Dot-Locations and Word-Lists from the Children's Memory Scale were used to measure visual-spatial and auditory-verbal STM performances, respectively. The findings of the present study suggest age-related differences in both visual-spatial and auditory-verbal STM. Sex-differences were observed only in one visual-spatial STM subtest performance. Modality comparisons revealed age- and task-related differences between auditory-verbal and visual-spatial STM performances. There were no sex-related effects in terms of modality specific performances. Overall, the results of this study provide evidence of STM development in early childhood, and these effects were mostly independent of sex and the modality of the task.

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Variations in different types of genomes have been found to be responsible for a large degree of physical diversity such as appearance and susceptibility to disease. Identification of genomic variations is difficult and can be facilitated through computational analysis of DNA sequences. Newly available technologies are able to sequence billions of DNA base pairs relatively quickly. These sequences can be used to identify variations within their specific genome but must be mapped to a reference sequence first. In order to align these sequences to a reference sequence, we require mapping algorithms that make use of approximate string matching and string indexing methods. To date, few mapping algorithms have been tailored to handle the massive amounts of output generated by newly available sequencing technologies. In otrder to handle this large amount of data, we modified the popular mapping software BWA to run in parallel using OpenMPI. Parallel BWA matches the efficiency of multithreaded BWA functions while providing efficient parallelism for BWA functions that do not currently support multithreading. Parallel BWA shows significant wall time speedup in comparison to multithreaded BWA on high-performance computing clusters, and will thus facilitate the analysis of genome sequencing data.

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The conjecture claiming that every planar graph is acyclic 5-choosable[Borodin et al., 2002] has been verified for several restricted classes of planargraphs. Recently, O. V. Borodin and A. O. Ivanova, [Journal of Graph Theory,68(2), October 2011, 169-176], have shown that a planar graph is acyclically 5-choosable if it does not contain an i-cycle adjacent to a j-cycle, where 3<=j<=5 if i=3 and 4<=j<=6 if i=4. We improve the above mentioned result and prove that every planar graph without an i-cycle adjacent to a j-cycle with3<=j<=5 if i=3 and 4<=j<=5 if i=4 is acyclically 5-choosable.

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Joanna Ellen Wood (1867-1927) was an acclaimed Canadian author who wrote several novels and short stories. Wood was born in Scotland, but emigrated to Canada with her family in 1869. In 1874 her father purchased a farm overlooking the Niagara River at Queenston. It is believed she was supported by her brother William, who encouraged her writing. She was based in New York City from 1887-1901, using William’s business address there to receive correspondence while she traveled or spent time in Queenston. Around 1906, Wood moved with her mother to Niagara-on-the-Lake, where she joined the Niagara Historical Society. By 1914, she was living in Buffalo, but later spent time at her sisters’ homes. It was at her sister’s home in Detroit where she suffered a stroke and died in 1927. Wood’s literary career was short-lived. She published her first novel, The Untempered Wind , in 1894, and a second novel, Judith Moore …, in 1898. Both novels received critical acclaim, and a third novel, Farden Ha', followed in 1902. Unfortunately the majority of Wood’s numerous and award-winning writings cannot be found. Her career peaked in 1901, when she was the highest paid Canadian fiction writer. For unknown reasons, her career abruptly ceased in 1902, with no further publications or mention made of her in the Canadian Magazine.

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A document outlining the rules and regulations for advertising liquor in Canada. The document is sorted by province and outlines the details for advertising, when allowed, in each province. The description of the contents reads "The purpose of this document is to provide a summary of Canadian advertising requirements and restrictions, by province for the distilled spirits industry as of September 23, 1976".

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This paper develops a model of short-range ballistic missile defense and uses it to study the performance of Israel’s Iron Dome system. The deterministic base model allows for inaccurate missiles, unsuccessful interceptions, and civil defense. Model enhancements consider the trade-offs in attacking the interception system, the difficulties faced by militants in assembling large salvos, and the effects of imperfect missile classification by the defender. A stochastic model is also developed. Analysis shows that system performance can be highly sensitive to the missile salvo size, and that systems with higher interception rates are more “fragile” when overloaded. The model is calibrated using publically available data about Iron Dome’s use during Operation Pillar of Defense in November 2012. If the systems performed as claimed, they saved Israel an estimated 1778 casualties and $80 million in property damage, and thereby made preemptive strikes on Gaza about 8 times less valuable to Israel. Gaza militants could have inflicted far more damage by grouping their rockets into large salvos, but this may have been difficult given Israel’s suppression efforts. Counter-battery fire by the militants is unlikely to be worthwhile unless they can obtain much more accurate missiles.