13 resultados para Formation of the historian
em Brock University, Canada
Resumo:
The Upper Cambrian Pika Formation in the southern Canadian Rocky Mountains forms a complete lithologic Grand Cycle. The overall pattern of deposition is one of shallowing upwards from a subtidal, muddy, storm-influenced basin to a shallow carbonate bank. The Pika passes gradationally into the overlying inter- to supratidal siliciclastics of the Arctomys Formation. This transition probably reflects a fall in relative sea level. 2 Twenty seven collections from three sections yielded trilobites. The faunas are assigned to two low-diversity biofacies: the Marjumia - Spencella Biofacies and the GZyphaspis - menomoniid Biofacies. In contrast to biofacies of deeper, open-shelf environments, such as the Wheeler and Marjum formations of Utah, the Pika biofacies lack agnostid trilobites. Consequently, agnostid-based zonations defined elsewhere in North America cannot be applied to the Pika and a new sequence of three zones and one informal fauna is proposed for use in inner shelf facies. Eleven species belonging to six genera are described and illustrated. The species Marjumia bagginsi is new. Other genera present are: Bolaspidella, Knechtelia, GZyphaspis and Spencella, in addition to a number of indeterminate forms
Resumo:
Boron trihalide and mixed boron trihalide adducts of trimethylamine have been prepared, and characterized by proton and fluorine N.M.R. spectroscopy. The acceptor power of the boron trihalides was seen to increase in the order BF3 < BC13 < BBr3 < BI3, corroborating previous evidence. The mixed boron trihalides had intermediate Lewis acidities. Solution reactions between adducts and free boron trihalides rapidly led to the formation of mixed adducts when the free boron trihalide is a stronger Lewis acid than that in the adduct. A slower reaction is observed when the free BX3 is a weaker Lewis aoid than that complexed. The mechanism of halogen exchange leading to the mixed (CH3)3NBX3 adducts was investigated. 10B labelling experiments precluded B-N bond rupture as a possible mechanism in solution; results are discussed in terms of halogen-bridged intermediates. Pre-ionization may be important for some systems. At higher temperatures, during gas phase reactions,B-N coordinate bond rupture may be the initial step of reaction. Two mixed adduots, namely (CH3)3NBClBr2 and (CH3)3NBHOIBr were prepared and characterized by Mass Spectrometry
Resumo:
The Pater metavolcanic suite (PVS) was extruded as part O'f the basal Pater Formation of the Huronian Supergroup ca. 2.4 Ga. They Ars classified as wi thin-plate tholeiites associated with an immature ri-fting episode, and are inter layered with associated vol cani clastic and metasedimentary units. Post-solidif ication alteration caused redistribution o-f the alkalies, Sr, Rb, Ba, Cu, and SiO^. Ce, Y, Zr, CFezOs (as total Fe), Al^Os, TiOa, and, PaOa are considered to have remained essentially immobile in least altered samples. Petrogenetic modelling indicates the PVS was derived from the partial melting of two geochemical ly similar sources in the sub-continental lithosphere. Fractionation was characterized by an oli vine-plagioclase assemblage and a sub-volcanic plagioclase-clinopyroxene assemblage. A comparative study indicates that enrichment of the postulated Huronian source cannot be reconciled by Archean contamination. Enrichment is thought to have been caused by hydrous veined metasomatic heterogeneities in the sub-continental lithosphere, generated by an Archean subduct ion event before 2.68 Ga.
Resumo:
Catalase is the enzyme which decomposes hydrogen peroxide to water and oxygen. Escherichia coli contains two catalases. Hydroperoxidase I (HPI) is a bifunctional catalase-peroxidase. Hydroperoxidase II (HPII) is only catalytically active toward H202. Expression of the genes encoding these proteins is controlled by different regimes. HPJI is thought to be a hexamer, having one heme d cis group per enzymatic subunit. HPII wild type protein and heme containing mutant proteins were obtained from the laboratory of P. Loewen (Univ. of Manitoba). Mutants constructed by oligonucleotidedirected mutagenesis were targeted for replacement of either the His128 residue or the Asn201 residue in the vicinity of the HPII heme crevice. His128 is the residue thought to be analogous to the His74 distal axial ligand of the heme in the bovine liver enzyme, and Asn201 is believed to be a residue critical to the function of the enzyme because of its role in orienting and interacting with the substrate molecule. Investigation of the nature of the hemes via absorption spectroscopy of the unmodified catalase proteins and their derived pyridine hemochromes showed that while the bovine and Saccharomyces cerevisiae catalase enzymes are protoheme-containing, the HPII wild type protein contains heme d, and the mutant proteins contain either solely protoheme, or heme d-protoheme mixtures. Cyanide binding studies supported this, as ligand binding was monophasic for the bovine, Saccharomyces cerevisiae, and wild type HPII enzymes, but biphasic for several of the HPII mutant proteins. Several mammalian catalases, and at least two prokaryotic catalases, are known to be NADPH binding. The function of this cofactor appears to be the prevention of inactivation of the enzyme, which occurs via formation of the inactive secondary catalase peroxide compound (compound II). No physiologically plausible scheme has yet been proposed for the NADPH mediation of catalase activity. This study has shown, via fluorescence and affinity chromatography techniques, that NADPH binds to the T (Typical) and A (Atypical) catalases of Saccharomyces cerevisiae, and that wild type HPII apparently does not bind NADPH. This study has also shown that NADPH is unlike any other hydrogen donor to catalase, and addresses its features as a unique donor by proposing a mechanism whereby NADPH is oxidized and catalase is protected from inactivation via the formation of protein radical species. Migration of this radical to a position close to the NADPH is also proposed as an adjunct hypothesis, based on similar electron migrations that are known to occur within metmyoglobin and cytochrome c peroxidase when reacted with H202. Validation of these hypotheses may be obtained in appropriate future experiments.
Resumo:
Exchange reactions between molecular complexes and excess acid
or base are well known and have been extensively surveyed in the
literature(l). Since the exchange mechanism will, in some way
involve the breaking of the labile donor-acceptor bond, it follows
that a discussion of the factors relating to bonding in molecular complexes
will be relevant.
In general, a strong Lewis base and a strong Lewis acid form a
stable adduct provided that certain stereochemical requirements are
met.
A strong Lewis base has the following characteristics (1),(2)
(i) high electron density at the donor site.
(ii) a non-bonded electron pair which has a low ionization potential
(iii) electron donating substituents at the donor atom site.
(iv) facile approach of the site of the Lewis base to the
acceptor site as dictated by the steric hindrance of the
substituents.
Examples of typical Lewis bases are ethers, nitriles, ketones,
alcohols, amines and phosphines.
For a strong Lewis acid, the following properties are important:(
i) low electron density at the acceptor site.
(ii) electron withdrawing substituents. (iii) substituents which do not interfere with the close
approach of the Lewis base.
(iv) availability of a vacant orbital capable of accepting
the lone electron pair of the donor atom.
Examples of Lewis acids are the group III and IV halides such
(M=B, AI, Ga, In) and MX4 - (M=Si, Ge, Sn, Pb).
The relative bond strengths of molecular complexes have been
investigated by:-
(i)
(ii)
(iii)
(iv)
(v]
(vi)
dipole moment measurements (3).
shifts of the carbonyl peaks in the IIIR. (4) ,(5), (6) ..
NMR chemical shift data (4),(7),(8),(9).
D.V. and visible spectrophotometric shifts (10),(11).
equilibrium constant data (12), (13).
heats of dissociation and heats of reactions (l~),
(16), (17), (18), (19).
Many experiments have bben carried out on boron trihalides in
order to determine their relative acid strengths. Using pyridine,
nitrobenzene, acetonitrile and trimethylamine as reference Lewis
bases, it was found that the acid strength varied in order:RBx3 >
BC1
3 >BF 3
• For the acetonitrile-boron trihalide and trimethylamine
boron trihalide complexes in nitrobenzene, an-NMR study (7) showed
that the shift to lower field was. greatest for the BB~3 adduct ~n~
smallest for the BF 3 which is in agreement with the acid strengths. If electronegativities of the substituents were the only
important effect, and since c~ Br ,one would expect
the electron density at the boron nucleus to vary as BF3
Resumo:
The Oak Ridges Moraine is a major physiographic feature of south-central Ontario, extending from Rice Lake westward to the Niagara Escarpment. While much previous work has largely postulated a relatively simple the origin of the moraine, recent investigations have concentrated on delineating the discernible glacigenic deposits (or landform architectural elements) which comprise the complex mosaic of the Oak Ridges Moraine. This study investigates the sedimentology of the Bloomington fan complex, one of the oldest elements of the Oak Ridges Moraine. The main sediment body of the Bloomington fan complex was deposited during early stages of the formation of the Oak Ridges Moraine, when the ice subdivided, and formed a confined, interlobate lake basin between the northern and southern lobes. Deposition from several conduits produced a fan complex characterized by multiple, laterally overlapping, fan bodies. It appears that the fans were active sequentially in an eastward direction, until the formation of the Bloomington fan complex was dominated by the largest fan fed by a conduit near the northeastern margin of the deposit. Following deposition of the fan complex, the northern and southern ice margins continued to retreat, opening drainage outlets to the west and causing water levels to drop in the lake basin. Glaciofluvial sediment was deposited at this time, cutting into the underlying fan complex. Re-advancing northern ice then closed westerly outlets, and caused water levels to increase, initiating the re-advance of the southern ice. As the southern ice approached the Bloomington fan, it deposited an ice-marginal sediment complex consisting of glacigenic sediment gravity flows, and glaciolacustrine and glaciofluvial sediments exhibiting north and northwesterly paleocurrents. Continued advance of the southern ice, overriding the fan complex, ii produced large-scale glaciotectonic deformation structures, and deposited the Halton Till. The subaqueous fan depositional model that is postulated for the Bloomington fan complex differs from published models due to the complex facies associations produced by the multiple conduit sources of sediment feeding the fans. The fluctuating northern and southern ice margins, which moved across the study area in opposite directions, controlled the water level in the interlobate basin and caused major changes in depositional environments. The influence of these two lobes also caused deposition from two distinct source directions. Finally, erosion, deposition, and deformation of the deposit with the readvance of the southern ice contributed further to the complexity of the Bloomington fan complex.
Resumo:
Dr. James A. Gibson was born in Ottawa on January 29, 1912 to John W. and Belle Gibson. At an early age the family moved to Victoria, B.C. where John W. Gibson was a director of the Elementary Agricultural Education Branch, Department of Education. Gibson received his early education in Victoria, receiving a B.A. (honours) at UBC in 1931. In 1931 he was awarded the Rhodes scholarship and received his B.A., M.A., B.Litt and D. Phil at New College, Oxford. This was to be the beginning of a long and dedicated relationship with the Rhodes Scholar Association. Upon his return to Canada, Dr. Gibson lectured in Economics and Government at the University of British Columbia. In 1938 he was married to Caroline Stein in Philadelphia, and the same year joined the staff of the Department of External Affairs as a Foreign Service officer. Within twenty minutes of his arrival he was seconded to the Office of the Prime Minister and Secretary of State for External Affairs, W. L. Mackenzie King in charge of War Records and Liaison Officer. This was a critical time in the history of Canada, and Dr. Gibson experienced firsthand several milestones, including the Royal Visit of King George VI and Queen Elizabeth in 1939. Dr. Gibson was present at the formation of the United Nations in San Francisco in 1945, being part of the Prime Minister’s professional staff as well as attending conferences in Washington, Quebec and London as an advisor to the Canadian delegation. Gibson contributed many articles to the publication bout de papier about his experiences during these years. After his resignation in 1947, Gibson joined the staff of the fledgling Carleton College, as a lecturer. In 1949 he was appointed a professor and in 1951 became Dean of Arts and Sciences. Dr. Gibson acted as President from 1955 to 1956 upon the sudden death of Dr. MacOdrum. In 1963 Dr. Gibson accepted the invitation of the Brock University Founders’ Committee, chaired by Arthur Schmon, to become the founding president. Dr. Gibson guided the new University from a converted refrigeration plant, to an ever expanding University campus on the brow of the Niagara Escarpment. Dr. Gibson remained firmly “attached” to Brock University. Even after official retirement, in 1974, he retained the title President Emeritus. Gibson’s final official contribution was an unpublished ten year history of the University. In retirement Gibson remained active in scholarly pursuits. He was a visiting scholar at the Center of Canadian Studies, University of Edinburgh; continued his ongoing research activities focusing on W. L. Mackenzie King, the Office of the Governor General of Canada, and political prisoners transported to Van Dieman’s Land. He remained active in the Canadian Association of Rhodes Scholars, becoming editor from 1975 to 1994 and was appointed Editor Emeritus and Director for Life in 1995 in honour of his dedicated and outstanding service. In 1993 he was awarded one of Canada’s highest achievements, the Order of Canada. Gibson retained close ties with Brock University and many of its faculty. He maintained an office in the Politics Department where he became a vital part of the department. In 1996 Brock University honoured Gibson by naming the University Library in his honour. James A. Gibson Library staff was instrumental in celebrating the 90th birthday of Gibson in 2002, with a widely attended party in the Pond Inlet where many former students, including Silver Badgers. The attendees also included former and current colleagues from Brock University, Canadian Rhodes Scholars Association, family and friends. Gibson was later to remark that the highlight of this event was the gift of his original academic robe which he had personally designed in 1964. In 2003 Dr. Gibson moved to Ottawa to be near some of his children and the city of his birth and early career. In that year “two visits to Brock ensued: the first, to attend a special celebration of the James A. Gibson Library; his late to attend the 74th Convocation on Saturday, October 18, 2003. A week later, in Ottawa, he went for a long walk, returned to his residence, Rideau Gardens, went into the lounge area, took off his coat and folded it up, put it on the back of his chair, sat down, folded his hands in his lap, closed his eyes, and died”. With sources from: Carleton University The Charlatan, Gibson CV, and Memorial Service Programme
Resumo:
During infection, the model plant Arabidopsis thaliana is capable of activating long lasting defence responses both in tissue directly affected by the pathogen and in more distal tissue. Systemic acquired resistance (SAR) is a type of systemic defence response deployed against biotrophic pathogens resulting in altered plant gene expression and production of antimicrobial compounds. One such gene involved in plant defence is called pathogenesis-related 1 (PR1) and is under the control of several protein regulators. TGA II-clade transcription factors (namely TGA2) repress PR1 activity prior to infection by forming large oligomeric complexes effectively blocking gene transcription. After pathogen detection, these complexes are dispersed by a mechanism unknown until now and free TGA molecules interact with the non-expressor of pathogenesis-related gene 1 (NPR1) protein forming an activating complex enabling PR1 transcription. This study elucidates the TGA2 dissociation mechanism by introducing protein kinase CK2 into this process. This enzyme efficiently phosphorylates TGA2 resulting in two crucial events. Firstly, the DNA-binding ability of this transcription factor is completely abolished explaining how the large TGA2 complexes are quickly evicted from the PR1 promoter. Secondly, a portion of TGA2 molecules dissociate from the complexes after phosphorylation which likely makes them available for the formation of the TGA2-NPR1 activating complex. We also show that phosphorylation of a multiserine motif found within TGA2’s N terminus is responsible for the change of affinity to DNA, while modification of a single threonine in the leucine zipper domain seems to be responsible for deoligomerization. Despite the substantial changes caused by phosphorylation, TGA2 is still capable of interacting with NPR1 and these proteins together form a complex on DNA promoting PR1 transcription. Therefore, we propose a change in the current model of how PR1 is regulated by adding CK2 which targets TGA2 displacing it’s complexes from the promoter and providing solitary TGA2 molecules for assembly of the activating complex. Amino acid sequences of regions targeted by CK2 in Arabidopsis TGA2 are similar to those found in TGA2 homologs in rice and tobacco. Therefore, the molecular mechanism that we have identified may be conserved among various plants, including important crop species, adding to the significance of our findings.
Resumo:
The rock sequence of the Tertiary Beda Formation of S. W. concession 59 and 59F block in Sirte Basin of Libya has been subdivided into twelve platformal carbonate microfacies. These microfacies are dominated by muddy carbonates, such as skeletal mudstones, wackestones, and packstones with dolomites and anhydrite. Rock textures, faunal assemblages and sedimentary structures suggest shallow, clear, warm waters and low to moderate energy conditions within the depositional shelf environment. The Beda Formation represents a shallowing-upward sequence typical of lagoonal and tidal flat environments marked at the top by sabkha and brackish-water sediments. Microfossils include benthonic foraminifera, such as miliolids, Nummulites, - oerculina and other smaller benthonics, in addition to dasycladacean algae, ostracods, molluscs, echinoderms, bryozoans and charophytes. Fecal pellets and pelloids, along with the biotic allochems, contributed greatly to the composition of the various microfacies. Dolomite, where present, is finely crystalline and an early replacement product. Anhydrite occurs as nodular, chickenwire and massive textures indicating supratidal sabkha deposition. Compaction, micr it i zat ion , dolomit izat ion , recrystallization, cementation, and dissolution resulted in alteration and obliteration of primary sedimentary structures of the Beda Formation microfacies. The study area is located in the Gerad Trough which developed as a NE-SW trending extensional graben. The Gerad trough was characterized by deep-shallow water conditions throughout the deposition of the Beda Formation sediments. The study area is marked by several horsts and grabens; as a result of extent ional tectonism. The area was tectonically active throughout the Tertiary period. Primary porosity is intergranular and intragranular, and secondary processes are characterized by dissolution, intercrystalline, fracture and fenestral features. Diagenesis, through solution leaching and dolomitization, contributed greatly to porosity development. Reservoir traps of the Beda Formation are characterized by normal fault blocks and the general reservoir characteristics/properties appear to be facies controlled.
Resumo:
The aim of this study was to investigate the neural correlates of operant conditioning in a semi-intact preparation of the pond snail, Lymnaea stagnalis. Lymnaea learns, via operant conditioning, to reduce its aerial respiratory behaviour in response to an aversive tactile stimulus to its open pneumostome. This thesis demonstrates the successful conditioning of na'ive semiintact preparations to show learning in the dish. Furthermore, these conditioned preparations show long-term memory that persists for at least 18 hours. As the neurons that generate this behaviour have been previously identified I can, for the first time, monitor neural activity during both learning and long-term memory consolidation in the same preparation. In particular, I record from the respiratory neuron Right Pedal Dorsal 1 (RPeD 1) which is part of the respiratory central pattern generator. In this study, I demonstrate that preventing RPeDl impulse activity between training sessions reduces the number of sessions needed to produce long-term memory in the present semi-intact preparation.
Resumo:
Since the first offshore Lake Erie well was drilled in 1941, the Grimsby and Thorold formations of the Cataract Group have been economically important to the oil and gas industry of Ontario. The Cataract Group provides a significant amount of Ontario's gas production primarily from wells located on Lake Erie. The Grimsby - Thorold formations are the result of nearshore estuarine processes influenced by tides on a prograding shelf and are composed of subtidal channel complexes, discrete tidal channels, mud flats and non-marine deposits. Deposition was related to a regressive - transgressive cycle associated with eustatic sea level changes caused by the melting and resurgence of continental glaciation centred in Africa in the Late Ordovician/Early Silurian. Grimsby deposition began during a regression with the deposition of subtidal channel complexes incised into the marine deposits of the Cabot Head Formation. The presence of mud drapes and mud couplets suggest that these deposits were influenced by tides. These deposits dominate the lower half of the Grimsby. Deposition continued with a change from these subtidal channel complexes to laterally migrating, discrete, shallow tidal channels and mud flats. These were in turn overlain by the non-marine deposits of the Thorold Formation. Grimsby - Thorold deposition ended with a major transgression replacing siliciclastic deposition with primarily carbonate deposition. Sediment was sourced from the east and southeast and associated with a continuation of the Taconic Orogeny into the Early Silurian. The fluvial head of the estuary prograded from a shoreline that was located in western New York and western Pennsylvania running NNE-SSW and then turning NW-SE and paralleling the present day Lake Erie shoreline. iii The facies attributed to the Grimsby - Thorold formations can be ascribed to the three zones within the tripartite zonation suggested by Dalrymple et ale (1992) for estuaries, that is, a marine-dominated facies, a mixed energy facies, and a facies that is dominated by fluvial processes. Also, sediments within the Grimsby - Thorold are commonly fining upwards sequences which are common in estuarine settings whereas deltaic deposits are normally composed of coarsening upwards sequences in a vertical wedge shape with coarser material near the head. The only coarsening observed was in the Thorold Formation and attributed to non-marine deposition by palynological evidence. The presence of a lag deposit at the base of the sediments of the Grimsby Thorold formations suggests that they were incised into the Cabot Head Formation. Further, the thickness of Early Silurian sediments located between the top of the Queenston Formation, where Early Silurian sedimentation began, to the top of the Reynales - Irondequoit formation are constant whether the Grimsby - Thorold formations are present or not. Also, cross-sections using a sand body located in the Cabot Head Formation for correlation further imply that the Grimsby Formation has been incised into the previous deposits of the Cabot Head.
Resumo:
This qualitative study explores Thomas Green's (1999) treatise, Voices: The Educational Formation of Conscience; for the purpose of reconstruing the transformative usefulness of conscience in moral education. Conscience is "reflexive judgment about things that matter" (Green, 1999, p. 21). Paul Lehmann (1963) suggested that we must "do the conscience over or do the conscience in" (p. 327). Thomas Green "does the conscience over", arguing that a philosophy of moral education, and not a moral philosophy, provides the only framework from which governance of moral behaviour can be understood. Narratives from four one-to-one interviews and a focus group are analysed and interpreted in search of: (a) awareness and understanding of conscience, (b) voices of conscience, (c) normation, (d) reflexive emotions, and (e) the idea of the sacred. Participants in this study (ages 16-21) demonstrated an active awareness of their conscience and a willingness to engage in a reflective process of their moral behaviour. They understood their conscience to be a process of self-judgment about what is right and wrong, and that its authority comes from within themselves. Narrative accounts from childhood indicated that conscience is there "from the beginning" with evidence of selfcorrecting behaviour. A maturing conscience is accompanied by an increased cognitive capacity, more complicated life experiences, and individualization. Moral motivation was grounded in " a desire to connect with things that are most important." A model for conscience formation is proposed, which visualizes a critical path of reflexive emotions. It is argued that schools, striving to shape good citizens, can promote conscience formation through a "curriculum of moral skills"; a curriculum that embraces complexity, diversity, social criticism, and selfhood.
Resumo:
This exploratory mixed method research project was designed to investigate an area of doctoral education that has received little attention in the past. This research focused specifically on the non-intellectual, hoped-for by-products of doctoral education; the dynamic processes of developing and maintaining both a sense of community and informal mentoring relationships. The design of the study captured the experiences of doctoral students and alumni at various time periods in the doctoral program. Participants represented a diverse group of students with differences in professional and academic backgrounds and life stages. A pilot study for this research suggested that the presence of a sense of community and informal mentoring may provide the necessary relationships to support this diversity. The primary question at the forefront of this study was: Do doctoral students feel connected to one another? Five subquestions were developed to address this research topic: Does a sense of community already exist and flourish in doctoral education? Are the programs and resources of the doctoral program organized to nurture the creation and maintenance of a sense of community? Is a sense of community a foundational element in the formation of naturally occurring relationships among doctoral students? What educational and socio-emotional benefits are associated with informal mentoring relationships during the doctoral experience? and Do doctoral students perceive a change in their development as stewards of their discipline over time? The principal methods used to investigate these research questions combined both quantitative and qualitative techniques in a concurrent time sequence. The quantitative portion of the study involved a questionnaire, while the qualitative portion involved two approaches; face-to-face interviews and an open-ended question at the end of the questionnaire. Findings from the study indicated that the presence of both sense of community and informal mentoring enhance the overall quality of doctoral education. Program elements that enhanced or hindered connection between students were identified. Both the dynamics and the emotional, social, and academic benefits of informal mentoring were elucidated. Over time participants perceived changes in their development of the qualities assqciated with stewardship. This study brought the "hoped-for by-products" associated with doctoral education from the background shadows to an illuminated position at the forefront of inquiry.