1,632 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
High-resolution conodont stratigraphy, biofacies, and extinctions around the Hangenberg Event in pelagic successions from Austria, Italy, and France.
No full textBased on high-resolution correlation of condensed pelagic successions of the Carnic Alps (northern Italy), Graz Palaeozoic (Austria), Montagne
Noire (southern France), and French Pyrenees, conodont stratigraphy, extinctions, and biofacies changes were studied around the Devonian/
Carboniferous boundary and compared regionally and internationally. Th e new and previous results allow us to distinguish 11 conodont biozones
from the Lower expansa Zone (upper Famennian) to the quadruplicata Zone (= Upper sandbergi Zone, top of lower Tournaisian). Fifty-six
conodont taxa are documented and assigned to conventional platform element genera. Th eir relative distribution is used to describe the vertical
biofacies evolution. Th e ranges of several species are extended and, in comparison with previous investigations, many new local records are
added. Some new ammonoid data from the Carnic Alps allow a correlation of cephalopod and conodont zones. Th e latter are partly (e.g., Lower
and Middle expansa zones) diffi cult to recognize because the defi ning index species are rare or locally absent; a revision of the zonal scheme is
desirable. New evidence confi rms that the disappearance of Palmatolepis gracilis gonioclymeniae Müller, 1956, is locally very diachronous and
not a meaningful level for correlation. Hence, the Middle praesulcata Zone is abandoned. Some additional conodont species disappear gradually
before the main extinction of the Hangenberg event. Palmatolepis and some dominant Famennian lineages of Bispathodus and Pseudopolygnathus
died out in all sections at the base of the Hangenberg Shale equivalent, at the same level as most ammonoids and benthic faunas of the pelagic
realm. Th e global pelagic conodont extinction rate was ca. 38%, but locally much higher rates are observed in the Prototethys realm. We suggest
using the signifi cant conodont extinction as a zonal boundary; the main part of the Hangenberg Event interval falls in a Bispathodus costatus
– Protognathodus kockeli Interregnum (CKI) that locally can have common Polygnathus inornatus Branson, 1934, or some Protognathodus
meischneri Ziegler, 1969. Th e former Upper praesulcata Zone is renamed the Protognathodus kockeli Zone. Due to the episodic rarity or absence
of siphonodellids close to the boundary, the base of the Carboniferous is alternatively drawn with the entry of Protognathodus kuehni Ziegler &
Leuteritz, 1970
Middle and Upper Devonian Cryptodonta (Bivalvia) from the Pelagic Hercynian Facies - Taxonomy, Stratigraphy, and Paleoecology
No full textGegenstand dieser Studie ist die reichhaltige Bivalvenfauna der pelagischen Fazies des Mittel- und Oberdevon, welche Teil einer typischen aber wenig diversen benthischen Lebensgemeinschaft des Tief- und Kaltwasser-Milieus ist. Diese ist bislang hinsichtlich ihrer stratigraphischen und geographischen Reichweite wenig erforscht. Außerdem ist die Systematik dieser Gruppe auf dem Stand des 19. Jahrhunderts. Untersucht wurden Exemplare aus Museums Sammlungen, inklusive aller verfügbaren Originaltypen, und Material aus jüngst beprobten Profilen Deutschlands, Frankreichs, Marokkos, Nord-Amerikas, Russlands und Polens. Mit dieser Arbeit wird erstmals eine systematische Revision der Bivalvenfauna der pelagischen Fazies des Givet und Oberdevons vorgelegt. Zudem wurden im Zuge dieser Studie erste Informationen über die Paläoökologie dieser Mollusken gesammelt. Die Biostratigraphie dieser Bivalven deutet auf eine Steuerung ihrer räumlichen und zeitlichen Verteilung durch globale Events hin
Middle and Upper Devonian Cryptodonta (Bivalvia) from the Pelagic Hercynian Facies - Taxonomy, Stratigraphy, and Paleoecology
No full textGegenstand dieser Studie ist die reichhaltige Bivalvenfauna der pelagischen Fazies des Mittel- und Oberdevon, welche Teil einer typischen aber wenig diversen benthischen Lebensgemeinschaft des Tief- und Kaltwasser-Milieus ist. Diese ist bislang hinsichtlich ihrer stratigraphischen und geographischen Reichweite wenig erforscht. Außerdem ist die Systematik dieser Gruppe auf dem Stand des 19. Jahrhunderts. Untersucht wurden Exemplare aus Museums Sammlungen, inklusive aller verfügbaren Originaltypen, und Material aus jüngst beprobten Profilen Deutschlands, Frankreichs, Marokkos, Nord-Amerikas, Russlands und Polens. Mit dieser Arbeit wird erstmals eine systematische Revision der Bivalvenfauna der pelagischen Fazies des Givet und Oberdevons vorgelegt. Zudem wurden im Zuge dieser Studie erste Informationen über die Paläoökologie dieser Mollusken gesammelt. Die Biostratigraphie dieser Bivalven deutet auf eine Steuerung ihrer räumlichen und zeitlichen Verteilung durch globale Events hin
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
Gut microbiome correlates of recurrent urinary tract infection: A longitudinal, multi-center study
No full textBACKGROUND: Urinary tract infections (UTI) affect approximately 250 million people annually worldwide. Patients often experience a cycle of antimicrobial treatment and recurrent UTI (rUTI) that is thought to be facilitated by a gut reservoir of uropathogenic
METHODS: 125 patients with UTI caused by an antibiotic-resistant organism (ARO) were enrolled from July 2016 to May 2019 in a longitudinal, multi-center cohort study. Multivariate statistical models were used to assess the relationship between uropathogen colonization and recurrent UTI (rUTI), controlling for clinical characteristics. 644 stool samples and 895 UPEC isolates were interrogated for taxonomic composition, antimicrobial resistance genes, and phenotypic resistance. Cohort UTI gut microbiome profiles were compared against published healthy and UTI reference microbiomes, as well as assessed within-cohort for timepoint- and recurrence-specific differences.
FINDINGS: Risk of rUTI was not independently associated with clinical characteristics. The UTI gut microbiome was distinct from healthy reference microbiomes in both taxonomic composition and antimicrobial resistance gene (ARG) burden, with 11 differentially abundant taxa at the genus level. rUTI and non-rUTI gut microbiomes in the cohort did not generally differ, but gut microbiomes from urinary tract colonized patients were elevated in
INTERPRETATION: The gut microbiome is implicated in UPEC urinary tract colonization during rUTI, serving as an ARG-enriched reservoir for UPEC. UPEC can asymptomatically colonize the gut and urinary tract, and post-antimicrobial blooms of gut
FUNDING: This work was supported in part by awards from the U.S. Centers for Disease Control and Prevention Epicenter Prevention Program (grant U54CK000482; principal investigator, V.J.F.); to J.H.K. from the Longer Life Foundation (an RGA/Washington University partnership), the National Center for Advancing Translational Sciences (grants KL2TR002346 and UL1TR002345), and the National Institute of Allergy and Infectious Diseases (NIAID) (grant K23A1137321) of the National Institutes of Health (NIH); and to G.D. from NIAID (grant R01AI123394) and the Eunice Kennedy Shriver National Institute of Child Health and Human Development (grant R01HD092414) of NIH. R.T.\u27s research was funded by the Deutsche Forschungsgemeinschaft (DFG; German Research Foundation; grant 402733540). REDCap is Supported by Clinical and Translational Science Award (CTSA) Grant UL1 TR002345 and Siteman Comprehensive Cancer Center and NCI Cancer Center Support Grant P30 CA091842. The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies
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
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