1,439 research outputs found
Ecology of the Festuca Grassland in Central Saskatchewan
No full textFor some time it has been realized that the grassland occuring in the 'park belt' or 'aspen grove region' bounding the Canadian prairies on the north, and forming the transition between it and the boreal forest, does not consist merely of extensions of the adjacent grassland communities (true prairie or mixed prairie) among the patches of woodland which occur in that region; but is characterized by a different group of dominant grasses from those occuring elsewhere in North America.
Although other investigators have mentioned this fact and written about the flora in other parts of the region, their data have been based largely on methods of estimation chiefly of a qualitative nature. In view of this, it was thought that an ecological survey based on quantitative methods might provide a better basis for classifying the vegetation of the area.
Accordingly, while being employed as an assistant in the Department of Plant Ecology of the University of Saskatchewan the author was given the opportunity, under the supervision of Dr. R.T. Coupland, to carry out investigations in those parts of the aspen grove region north and northwest of Saskatoon.
The author is considerably indebted to Dr. B.W. Currie of the Physics Department, for furnishing data on the climate of the area of research, and to Mr. H.C. Moss and his assistants, of the Saskachewan Soil Survey, who kindly undertook to examine and report on the soil samples which were collected in several of the sites studied. The author also wishes to express his gratitide to Mr. Jack F. Alex and Mr. W. Budz of the Department of Plant Ecology, who assisted greatly in both the field and laboratory work for this project. The financial assistance of the Saskatchewan Agricultural Research Foundation, which made this study possible, is also appreciated.
The author experienced a great deal of difficulty as a result of unfamiliarity with the topography, in particular with the vegetation of the plants, since he is more accustomed to the mountains and forests of British Columbia. Many problems of identifications were encountered in dealing with the wealth of species of grasses and composites, as well as problems of relationship between the communities found in certain locations and their topographical situation
Data on the mechanisms underlying succinate-induced aortic contraction
No full textAbstractWe describe the mechanisms underlying the vascular contraction induced by succinate. The data presented here are related to the article entitled “Pharmacological characterization of the mechanisms underlying the vascular effects of succinate” (L.N. Leite, N.A. Gonzaga, J.A. Simplicio, G.T. Vale, J.M. Carballido, J.C. Alves-Filho, C.R. Tirapelli, 2016) [1]. Succinate acts as a signaling molecule by binding to a G-protein-coupled receptor termed GPR91, “Citric acid cycle intermediates as ligands for orphan G-protein-coupled receptors” (W. He, F.J. Miao, D.C. Lin, R.T. Schwandner, Z. Wang, J. Gao, J.L. Chen, H. Tian, L. Ling, 2004) [2]. Here we include data on the contractile effect of succinate in the aorta. Succinate contracted both endothelium-intact and endothelium-denuded aortic rings isolated from male Wistar rats or C57BL/6 mice. Succinate was less effective at inducing contraction in arteries isolated from GPR91-deficient mice, when compared to its vascular effect in aortas from wild type mice. SB203508 (p38MAK inhibitor), SP600125 (JNK inhibitor) and Y27632 (Rho-kinase inhibitor) reduced succinate-induced contraction in both endothelium-intact and endothelium-denuded rat aortic rings, while PD98059 (ERK1/2 inhibitor) did not affect succinate-induced contraction. The contractile response induced by succinate on endothelium-intact and endothelium-denuded rat aortic rings was reduced by indomethacin (non-selective cyclooxygenase inhibitor), H7 (protein kinase C inhibitor), verapamil (Ca2+ channel blocker) and tiron (superoxide anion scavenger)
Coordination in an Adaptive Traffic Signal Control System
No full textCoordination between the intersections is used in traffic signal control for quite a long time. The objective of this thesis is to determine how beneficial network coordination is in an adaptive traffic signal control system that follows the multi-agent approach. As part of the research: Simulation results show that coordination in a multi-agent controller can reduce average delay of the users on the network depending on the average demand. The best performing coordination measure is platooning cars on the main streams at the first intersection of the arterial. This provide time for the downstream intersections to serve side streams and ensured that the main stream is not stopped at the downstream intersections on the arterial. The tested coordination measures reduced delay with 10% compared to the original settings.Transport and PlanningTransport & PlanningCivil Engineering and Geoscience
The implementation of a system description language and its semantic functions
No full textElectrical Engineering, Mathematics and Computer Scienc
Distributed Gaussian Process Hyperparameter Optimization for Multi-Agent Systems
No full textGaussian Process (GP) is a flexible non-parametric method which has a wide variety of applications e.g., field estimation using multi-agent systems. However, the training of the hyperparameters suffers from high computational complexity. Recently, distributed hyperparameter optimization with proximal gradients has been proposed to reduce complexity, however only for a network with a central station. In this work, exploiting edge-based constraints, we propose two fully-distributed algorithms pxADMMfd and pxADMMfd,fast for a network of multi-agent systems, which do not rely on a central station. In addition, asynchronous versions of the algorithms are also proposed to reduce the synchronization overhead in heterogeneous networks. Simulations are conducted for a field estimation problem, using both artificial, and real-world datasets, which show that the proposed fully-distributed algorithms successfully converge, at the cost of an increased number of iterations.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Signal Processing System
RadioAstron gravitational redshift experiment: status update
No full textA test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observations performed so far, currently being analyzed, have already allowed us to measure the effect with a relative accuracy of 4 × 10−4 . We expect to reach 2.5×10−5 with additional observations in 2016, an improvement of almost a magnitude over the 40-year old result of the GP-A mission
Relative Space-Time Kinematics of an Anchorless Network
No full textThe work described in this thesis was in part financially supported by STW-sponsored OLFAR project (Contract Number: 10556) within the Dutch ASSYS perspectief programSignal Processing System
Development of mycoinsecticide formulations and application techniques appropriate for pest control
No full textSIGLEAvailable from British Library Document Supply Centre-DSC:DXN038120 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Multi-Sensor Fusion for Localization of a Lunar Micro Rover Using Non-Vision Sensors
No full textAutonomous navigation is a critical aspect of robotic systems, particularly in hostile and uncertain environments, and robot localization is central to navigation. Robot localization establishes its position within its surroundings. This thesis addresses the challenge of robot localization, focusing on a lunar-like environment with constraints such as limited computational resources and the use of non-visual based sensors. In this thesis, three sensors — wheel encoders (WE), Sun sensor (SS), and inertial measurement unit (IMU) — are employed for localization. Each sensor contributes distinct information regarding position and orientation. However, individual sensor measurements suffer from inherent inaccuracies and errors, especially the IMU’s reliance on integration over time, leading to significant drift. To mitigate these challenges, three fusion methods are explored: sensor selection based on predefined thresholds, Kalman filtering, and weighted fusion. Results indi- cate substantial improvements in localization accuracy compared to individual sensor measurements. The weighted fusion method, in particular, demonstrates superior per- formance by assigning appropriate importance, according to their accuracy, to each sensor’s information, resulting in significantly reduced positioning errors. The maxi- mum localization error using this method is 92m, which is smaller than reported in the literature. Further, the maximum localization percentage error over 65m is around 8%, which is comparable to the literature with visual sensors. The weighted fusion method introduces only a marginal increase in the computational complexity. Thus, this method stands out for its simplicity and delivers results superior to those documented in existing literature for non-visual sensors. Despite promising results, the research is met with certain hurdles, notably the avail- ability and consistency of datasets. The reliance on existing datasets, such as the Devon Island Rover dataset, highlights the need for standardized and comprehensive datasets for thorough testing and validation. Calibration inconsistencies and verification issues further underscore the complexity of real-world implementation. Nevertheless, the findings of this thesis offer insights into the integration of multiple sensors for enhanced localization in lunar-like environments. By leveraging complementary sensor data and employing efficient fusion techniques, the proposed approach enables more accurate and reliable navigation of lunar micro rovers, thus advancing the capabilities of autonomous robotic systems for future lunar exploration missions.Electrical Engineering | Signals and System
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