25 resultados para SENSITIVE HALF-TIMES
em Brock University, Canada
Resumo:
ABSTRACT Photosynthetic state transitions were investigated in the cyanobacterium Synechococcus sp. PCC 7002 in both wild-type cells and mutant cells lacking phycobilisomes. Preillumination in the presence of DCMU (3(3,4 dichlorophenyl) 1,1 dimethyl urea) induced state 1 and dark adaptation induced state 2 in both wild-type and mutant cells as determined by 77K fluorescence emission spectroscopy. Light-induced transitions were observed in the wildtype after preferential excitation of phycocyanin (state 2) or preferential excitation of chlorophyll .a. (state 1). The state 1 and 2 transitions in the wild-type had half-times of approximately 10 seconds. Cytochrome f and P-700 oxidation kinetics could not be correlated with any current state transition model as cells in state 1 showed faster oxidation kinetics regardless of excitation wavelength. Light-induced transitions were also observed in the phycobilisomeless mutant after preferential excitation of short wavelength chlorophyll !l. (state 2) or carotenoids and long wavelength chlorophyll it (state 1). One-dimensional electrophoresis revealed no significant differences in phosphorylation patterns of resolved proteins between wild-type cells in state 1 and state 2. It is concluded that the mechanism of the light state transition in cyanobacteria does not require the presence of the phycobilisome. The results contradict proposed models for the state transition which require an active role for the phycobilisome.
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Genetic chimeras made by aggregating early mouse embryos have many uses in developmental biology and have also provided insights into embryonic growth regulation. There is an indication that the embryo can regulate for an increase in size because although aggregation chimeras are twice as big as normal embryos when made, they are born of normal size. Upward regula..... tion of size reduced embryos is also possible. Half embryos made by the isolation or destruction of one of the blastomeres of a 2-cell embryo are also born of normal size. Little is known about the timing or the mechanism of this size regulation. In this study, the timing of size regulation in double and half embryos was clearly established by comparison of cell numbers derived from serial reconstruction of light microscope sections of control and experimental embryos. It was shown that size regulation in double embryos occurred around 6dl6h and in half embryos by 7dOh. Size regulation occurred in all tissues at the same time indicating a single control mechanism for the entire embryo. More detailed examination of the growth of double embryos revealed that size regulation occurred by alteration in cell cycle length~ No excessive cell death was found in double embryos compared to the controls and continuous labelling with [3H] thymidine showed no large non-dividing cell population in double embryos. However, a comparison of the mitotic index of double and control embryos after colcemid treatment, revealed a large difference between the two around 5dl6h to 6d16h. During this period, control embryos underwent a proliferative burst not shown by the double embryos. The mechanism for cell cycle control is not clear; it may be intrinsic to the embryo or determined by the uterine environment. Evidence was found suggesting that differentiation in the postimplantation embryo was cell number dependent. The timing of differentiative events was examined in half, double and control embryos. Proamnion formation, which occurs prior to size regulation, occurs at the same cell number but at different times in the three groups of embryos. However mesoderm which appears after size regulation was seen at the same time in all grollps of embryos.
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Reduced capacity for executive cognitive function and for the autonomic control of cardiac responsivity are both concomitants of the aging process. These may be linked through their mutual dependence on medial prefrontal function, but the specifics ofthat linkage have not been well explored. Executive functions associated with medial prefrontal cortex involve various aspects ofperformance monitoring, whereas centrally mediated autonomic functions can be observed as heart rate variability (HRV), i.e., variability in the length of intervals between heart beats. The focus for this thesis was to examine the degree to which the capacity for phasic autonomic adjustments to heart rate relates to performance monitoring in younger and older adults, using measures of electrocortical and autonomic activity. Behavioural performance and attention allocation during two age-sensitive tasks could be predicted by various aspects of autonomic control. For young adults, greater influence of the parasympathetic system on HRV was beneficial for learning unfamiliar maze paths; for older adults, greater sympathetic influence was detrimental to these functions. Further, these relationships were primarily evoked when the task required the construction and use of internalized representations of mazes rather than passive responses to feedback. When memory for source was required, older adults made three times as many source errors as young adults. However, greater parasympathetic influence on HRV in the older group was conducive to avoiding source errors and to reduced electrocortical responses to irrelevant information. Higher sympathetic predominance, in contrast, was associated with higher rates of source error and greater electrocortical responses tq non-target information in both groups. These relations were not seen for 11 errors associated with a speeded perceptual task, irrespective of its difficulty level. Overall, autonomic modulation of cardiac activity was associated with higher levels of performance monitoring, but differentially across tasks and age groups. With respect to age, those older adults who had maintained higher levels of autonomic cardiac regulation appeared to have also maintained higher levels of executive control over task performance.
A biochemical predictor of performance during mesophilic anaerobic fermentation of starch wastewater
Resumo:
The aim of this study was to determine the potential of biochemical parameters, such as enzyme activity and adenosine triphosphate (ATP) levels, as monitors of process performance in the Upflow Anaerobic Sludge Blanket (UASB) reactor utilizing a starch wastewater. The acid and alkaline phosphatase activity and the ATP content of the UASB sludge were measured in response to changes in flow rate and nutrient loading. Conventional parameters of process performance, such as gas production, acetic acid production, COD, phosphorus, nitrogen and suspended solids loadings and % COD removal were also monitored. The response of both biochemical and conventional parameters to changing process conditions was then compared. Alkaline phosphatase activity exhibited the highest activity over the entire study perioda A high suspended solids loading was observed to upset the system in terms of gas production, acetic acid production and % COD removala The initial rate of increase in alkaline phosphatase activity following an increase in loading was four times as great during process upset than under conditions of good performance. The change in enzyme actiVity was also more sensitive to process upset than changes in acetic acid production. The change in ATP content of the sludge with time suggested that enzyme actiVity was changing independently of the actual viable biomass present. The bacterial composition of the anaerobic sludge granules was similar to that of other sludge bed systems, at the light and scanning electron microscope level. Isolated serum bottle cultures produced several acids involved in anaerobic carbohydrate metabolism. The overall performance of the UASB system indicated that higher loadings of soluble nutrients could have been tolerated by the system.
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A strain of Drosophila melanogaster (mid america stock culture no. hl16) has been reported to be deficient in aldehyde oxidase activity (Hickey and Singh 1982). This strain was characterized during the course of this study and compared to other mutant strains known to be deficient in aldehyde oxidase activity. During the course of this investigation, the hl16 strain was found to be temperature sensitive in its viability. It was found that the two phenotypes, the enzyme deficiency, and the temperature sensitive lethality were the result of two different mutations, both mapping to the X-chromosome. These two mutations were found to be separable by recombination. The enzyme deficiency was found to map to the same locus as the cinnamon mutation, another mutation which affects aldehyde oxidase production. The developmental profile of aldehyde oxidase in the hl16 strain was compared to the developmental profile in the Canton S wild type strain. The aldehyde oxidase activity in adult hl16 individuals was also compared to that of various other strains. It was also found that the aldehyde oxidase activity was temperature sensitive in the adult flies. The temperature sensitive lethality mutation was mapped to position 1-0.1.
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The Beckman Helium Discharge Detector has been found to be sensitive to the fixed gases oxygen, nitrogen, and hydrogen at detection levels 10-100 times more sensitive than possible with a Bow-Mac Thermal Conductivity Detector. Detection levels o~ approximately 1.9 E-4 ~ v/v oxygen, 3.1 E-4 ~ v/v nitrogen, and 3.0 E-3 ~ v/v hydrogen are estimated. Response of the Helium Discharge Detector was not linear, but is useable for quantitation over limited ranges of concentration using suitably prepared working standards. Cleanliness of the detector discharge electrodes and purity of the helium carrier and discharge gas were found to be critical to the operation of the detector. Higher sensitivities of the Helium Discharge Detector may be possible by the design and installation of a sensitive, solid-state electrometer.
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The effects of metiram (Polyram 80 DF) on the growth of Venturia inaequalis, cause of apple scab, and the degradation of metiram were examined in culture media. Samples of V. inaequalis conidia were collected from nine orchards in 1998 and six orchards in 1999 and tested for sensitivity. Samples were plated on water agar amended with metiram or mancozeb. Mean EC50 values (effective concentration of fungicide required to inhibit germination of half the conidia) for each population were calculated. The mean EC50 values for metiram ranged from 0.26 - 1.20 ^ig metiram a.i./ml, with differences (Student Newman Keul's Test (SNK), a=0.05) between populations. EC50 values for mancozeb ranged from 0.06 - 0.58 which were also different (SNK, a=0.05). Five of these populations were examined for mycelial growth sensitivity to metiram by testing 30 monoconidial isolates from each population on metiram amended potato dextrose agar. Mean EC50 values for populations were calculated and ranged from 3.44-5.94 |ig metiram/ml, and showed differences (Friedman Test, a=0.05). As the EC50 values obtained are far less than the concentrations applied in the field, results indicate that Ontario populations of V. inaequalis are still sensitive to metiram and mancozeb. The stability of metiram in PDA at 22°C was studied over a 10-day period. The initial concentration of metiram decreased by approximately 50% within the first day, and continued to decline slowly, to approximately 20% of the initial concentration. The factors possibly affecting initial metiram degradation, including agar, heat, and the use of glass or polystyrene Petri dish composition were examined. The effects from the polystyrene in the Petri dish composition were negligible, however more studies must be done to examine metiram degradation during the first 24 hours of preparation.
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Caption title.
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Through aggressive legislative and educational policies Indigenous languages globally have been shifted to the language of the dominant society. Globalization has brought previously geo-politically and/or geo-linguistically isolated people and language . groups into close proximity that necessitated interaction and at times intense power struggles. There are currently approximately 6,000 spoken languages in the world, more than half are either endangered, dying or disappearing altogether. Canadian statistics reveal an overall 3 % decline in the intergenerational transmission of language. Of the original 60 Indigenous languages spoken in Canada, 8 are extinct, 13 are nearly extinct, and 23 are critical. The remaining languages have a slim chance of survival. Within the next 100 years only 4 Indigenous languages will remain. The Hodenosaunee languages of Southern Ontario are not incl~ded among the list of languages that will survive the next 100 years. There are, without a doubt, complex challenges in the maintenance of Indigenous languages within a dominant-culture influenced environment. Given the increasing awareness of the social impact of linguistic integrity and preservation of languages on Indigenous people as a whole, this study considers how language is currently being used; the social, economic, and political implications of language shifting; the need to shift our social consciousness in order to understand the urgency in privileging our Hodenosaunee languages; as well as ways in which we might achieve those goals as individuals, as families, and as a community.
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A letter regarding an affidavit discussing the half pay of Daniel Shannon from the 25th June to the 21st of December 1819.
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Discusses the half pay and pensions of Officers living within His Majesty's Dominions. At the bottom, there is also a comment made by Robert Morrogh to Daniel Shannon concerning the above notice.
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Half-penny token struck for general circulation in Upper Canada, about 1816. The token is one of a few issues which commemorate Sir Issac Brock. The name Brock is misspelled "Brook" on this token. The other side bears the picture of a sailing vessel and the motto "Success to the Commerce of Upper Canada".
Resumo:
The present thesis describes syntheses, structural studies, and catalytic reactivity of new non-classical silane complexes of ruthenium and iron. The ruthenium complexes CpRu(PPri3)CI(T]2-HSiR3) (1) (SiR3 = SiCh (a), SiClzMe (b), SiCIMe2 (c), SiH2Ph (d), SiMe2Ph (e» were prepared by reactions of the new unsaturated complex CpRu(PPri3)CI with silanes. According to NMR studies and X-ray analyses, the complexes la-c exhibit unusual simultaneous Si··· H and Si··· CI-Ru interactions. The complex CpRu(PPri3)CI was also used for the preparation of the first examples of late transition metal agostic silylamido complexes CpRu(PPri3)(N(T]2-HSiMe2)R) (2) (R= Ar or But), which were characterized by NMR spectroscopy. The iron complexes CpFe(PMePri2)H2(SiR3) (3) (SiR3 = SiCh (a), SiClzMe (b), SiCIMe2 (c), SiH2Ph (d), SiMe2Ph (e» were synthesized by the reaction of the new borohydride iron complex CpFe(PMePri2)(B~) with silanes in the presence NEt3. The complexes 3 exhibit unprecedented two simultaneous and equivalent Si··· H interactions, which was confirmed by X-ray analyses and DFT calculations. A series of cationic ruthenium complexes [CpRu(PR3)(CH3CN)(112-HSiR'3)]BAF (PR3 = PPri 3 (4), PPh3 (5); SiR'3 = SiCh (a), SiClzMe (b), SiClMe2 (c), SiH2Ph (d), SiMe2Ph (e» was obtained by substitution of one of the labile acetonitrile ligands in [CpRu(PR3)(CH3CNh]BAF with sHanes. Analogous complexes [TpRu(PR3)(CH3CN)(T]2 -HSiR' 3)]BAF (5) were obtained by the reaction of TpRu(PR3)(CH3CN)CI with LiBAF in the presence of silanes. The complexes 4-5 were characterized by NMR spectroscopy, and the observed coupling constants J(Si-H) allowed us to estimate the extent of Si-H bond activation in these compounds. The catalytic activity in hydrosilylation reactions of all of the above complexes was examined. The most promising results were achieved with the cationic ruthenium precatalyst [CpRu(PPri3)(CH3CN)2t (6). Complex 6 shows good to excellent catalytic activity in the hydrosilylation of carbonyls, dehydrogenative coupling of silanes with alcohols, amines, acids, and reduction of acid chlorides. We also discovered very selective reduction of nitriles and pyridines into the corresponding N-silyl imines and l,4-dihydropyridines, respectively, at room temperature with the possibility of catalyst recycling. These chemoselective catalytic methods have no analogues in the literature. The reactions were proposed to proceed via an ionic mechanism with intermediate formation of the silane a-complexes 4.
Grant of Permission for lease of military lands from Sir Robert Prescott to Thomas Clark, 1798-1801.
Resumo:
Transcript (original spelling and grammar retained): By His Excellency Robert Prescott Esquire, Captain General and Governor in Chief in and over His Majestys Provinces of Upper and Lower Canada, General and Commander in Chief of all His Majesty’s forces in the Provinces of Upper and Lower Canada, Nova Scotia, New Brunswick and their several Dependencies and in the Island of Newfoundland &ca. &ca. &ca. I do hereby authorise and permit Thomas Clark of Queenstown in the County of Lincoln in the Province of Upper Canada merchant to take possession of all that Lot, piece and parcel of Land (being part of the land reserved by his Majesty for Military purposes) situate, lying and being at Queenstown in the Township of Newark, in the Home District in the said Province of Upper Canada, bounded and abutted as follows, that is to say beginning at the Distance of two Chains and ninety links from the South East End of his Majesty’s Store House, the said distance being measured along the Bank up Stream, thence South thirty nine degrees and an half West one Chain and fifty links thence south fifty degrees and an half East one Chain and thirty links thence North thirty nine degrees and an half East to the Edge of the Bank and from thence along the Bank to the place of beginning, containing thirty one perches and one hundred and twenty five square links and to occupy and hold the said Lot, piece and parcel of Land during pleasure subject nevertheless to the provisoes and Conditions herein after contained, that is to say. First on condition that it shall and may be lawful to and for His Majesty his Heirs and Successors and to and for the Commander in Chief of His Majesty Forces for the time being and to and for the Officer commanding his Majesty’s Forces in Upper Canada for the time being and to and for either of them to determine and make void this present permission to occupy during pleasure the said Lot, Piece or Parcel of Land above described at any time hereafter whenever he or they shall see fit so to do without any compensation or indemnification to the said Thomas Clark or any other Person or Persons whosoever for any Loss Injury or Damage which he the said Thomas Clark or any other Person or Persons whosoever may thereby sustain. Secondly on this further Condition that it shall and may be lawful to and for His Majesty his Heirs and Successors and to and for his and their Officers, Soldiers and Servants at any time hereafter by order of the Commander in Chief of His Majesty’s Forces for the time being or by order of the Officer commanding his Majesty’s forces in Upper Canada for the time being or by order of the Officer of His Majesty’s Corps of Royal Engineers commanding in the said Province of Upper Canada for the time being to enter upon the said Lot Piece and parcel of Land which the said Thomas Clark is hereby permitted to occupy during pleasure or upon any part thereof and to take down and from the said Lot piece and parcel of Land or from any part thereof to remove any dwelling House Store or other Buildings on the said Lot, piece or Parcel of Land or any part thereof erected and to remove any goods or Chattels on the said Lot piece and parcel of Land or on any part thereof or on any such dwelling House Store or other building found or being and that His Majesty his Heirs and Successors or any other Person or Persons whosoever shall not be liable or responsible to the said Thomas Clark or to any other Person or Persons whosoever for any Loss, Injury or Damage which he or they shall or may in such case sustain. Thirdly on this further Condition that the said Thomas Clark shall not erect on the said Lot Piece or Parcel of Land which the said Thomas Clark is hereby permitted to occupy during pleasure or upon any part thereof at any time or times hereafter any dwelling House store or other Building whatsoever of Stone or brick or of any other materials wood only exccepted and that if any dwelling House or Store or other building of Stone or brick or of any other materials except wood shall at any time be erected on the said Lot, piece or parcel of Land or upon any part thereof, then and in such case, this present permission and every Clause and Article thereof shall from thenceforth cease and determine and be absolutely and entirely null and void. And lastly on this further Condition that the said Thomas Clark or any other Person whosoever shall not assign this permission to occupy the said Lot, Piece or Parcel of Land above described to any Person of Persons whosoever, and if any such assignment shall be made by the said Thomas Clark or by any other Person in his right, or on his behalf, that then and in such case such assignment and this permission to occupy during pleasure the said Lot piece and parcel of Land above described, and every Clause and Article thereof shall from thenceforth cease and determine and be absolutely and entirely null and void. Given under my hand at the Castle of St. Lewis in the City of Quebec in the Province of Lower Canada this Ninth day of July in the year of our Lord one thousand seven hundred and ninety eight and in the thirty eighth year of His Majesty’s Reign. [Signed here by Robert Prescott] By Order of the Commander in Chief [Signed here by James Green (Illegible signature)] I the said Thomas Clark above named do hereby accept the above written Permission to occupy during pleasure the said Lot piece and parcel of Land above described upon and subject to the several Provisioes and Conditions above written and each and every of them severally and respectively. In witness whereof I have hereunto set my hand the Sixteenth day of August in the year of our Lord one thousand seven hundred and ninety eight and in the thirty eighth year of His Majesty’s Reign. [Signed here by Thomas Clark] Signed in the presence of [Illegible signature – looks like J. M Donell Lt. Col.] [Illegible – looks like 2d. Battn R. C. Sm?] [Signed here by C. Anderson] Whereas Inconveniences did arise from the peculiar situation of the Ground contiguous to the above described Lot of Land and the occupation thereof, if estimated by the above Limits would prove highly disadvantageous to Mr. Thomas Clark be it known that in consideration thereof we do permit the above Lot to extend one half Chain more in length up stream so as to comprehend the space allowed for the Road between Lots Two + Three, and we do hereby appropriate the said additional space wholly to the use of the said Thomas Clark. In witness whereof we have hereunto subscribed this Thirteenth Day of October in the Year of our Lord one thousand Eight Hundred and one. [Signed here by J. M’Donell Lt. Col] 2d. Battn. R. C. [in?] Com of Fort George + Dependencies Robt. Pilkington Captain Royal Engineers
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Sir George Yonge (1732-1812) was a baronet, politician and colonial governor. He was a Member of Parliament for Honiton from 1754-1761 and 1763-1796, British Secretary at War from 1782-1783 and 1783-1794, and Governor of the Cape colony from 1799-1801.