Paragenetic history of the Ordovician Trenton Group carbonates, Southwestern Ontario

Geochemical examination of the rock matrix and cements from core material extracted from four oil wells within southwestern Ontario suggest various stages of diagenetic alteration and preservation of the Trenton Group carbonates. The geochemical compositions of Middle Ordovician (LMC) brachiopods reflect the physicochemical water conditions of the ambient depositional environment. The sediments appear to have been altered in the presence of mixed waters during burial in a relatively open diagenetic microenvironment. Conodont CAl determination suggests that the maturation levels of the Trenton Group carbonates are low and proceeded at temperatures of about 30 - 50°C within the shallow burial environment. The Trenton Group carbonates are characterized by two distinct stages of dolomitization which proceeded at elevated temperatures. Preexisting fracture patterns, and block faulting controlled the initial dolomitization of the precursor carbonate matrix. Dolomitization progressed In the presence of warm fluids (60 75°C) with physicochemical conditions characteristic of a progressively depleted basinal water. The matrix is mostly Idiotopic-S and Idiotopic-E dolomite, with Xenotopic-A dolomite dominating the matrix where fractures occur. The second stage of dolomitization involved hydrothermal basinal fluid(s) with temperatures of about 60 - 70°C. These are the postulated source for the saddle dolomite and blocky calcite cements occurring in pore space and fractures. Rock porosity was partly occluded by Idiotopic-E type dolomite. Late stage saddle dolomite, calcite, anhydrite, pyrite, marcasite and minor sphalerite and celestite cements effectively fill any remaining porosity within specific horizons. Based on cathode luminescence, precipitation of the different diagenetic phases probably proceeded in open diagenetic systems from chemically homogeneous fluids. Ultraviolet fluorescence of 11 the matrix and cements demonstrated that hydrocarbons were present during the earliest formation of saddle dolomite. Oxygen isotope values of -7.6 to -8.5 %0 (PDB), and carbon isotope values of - 0.5 and -3.0 %0 (PDB) from the latest stage dog-tooth calcite cement suggest that meteoric water was introduced into the system during their formation. This is estimated to have occurred at temperatures of about 25 - 40°C. Specific facies associations within the Trenton Group carbonates exhibit good hydrocarbon generating potential based on organic carbon preservation (1-3.5%). Thermal maturation and Lopatin burial-history evaluations suggest that hydrocarbons were generated within the Trenton Group carbonates some time after 300 Ma . Progressively depleted vanadium trends measured from hydrocarbon samples within southwestern Ontario suggests its potential use as a hydrocarbon migration indicator on local (within an oilfield) and on regional scales.

The effect of elevated muscle fluid volume on indices of muscle damage following an acute bout of eccentric exercise

The primary purpose of the current investigation was to develop an elevated muscle fluid level using a human in-vivo model. The secondary purpose was to determine if an increased muscle fluid content could alter the acute muscle damage response following a bout of eccentric exercise. Eight healthy, recreationally active males participated in a cross-over design involving two randomly assigned trials. A hydration trial (HYD) consisting of a two hour infusion of a hypotonic (0.45%) saline at a rate of 20mL/minVl .73m"^ and a control trial (CON), separated by four weeks. Following the infusion (HYD) or rest period (CON), participants completed a single leg isokinetic eccentric exercise protocol of the quadriceps, consisting of 10 sets of 10 repetitions with a one minute rest between each set. Muscle biopsies were collected prior to the exercise, immediately following and at three hours post exercise. Muscle analysis included determination of wet-dry ratios and quantification of muscle damage using toluidine blue staining and light microscopy. Blood samples were collected prior to, immediately post, three and 24 hours post exercise to determine changes in creatine kinase (CK), lactate dehydrogenase (LD), interleukin-6 (IL-6) and Creactive protein (CRP) levels. Results demonstrated an increased muscle fluid volume in the HYD condition following the infusion when compared to the CON condition. Isometric peak torque was significantly reduced following the exercise in both the HYD and CON conditions. There were no significant differences in the number of areas of muscle damage at any of the time points in either condition, with no differences between conditions. CK levels were significantly greater 24hour post exercise compared to pre, immediately and three hours post similarly in both conditions. LD in the HYD condition followed a similar trend as CK with 24 hour levels higher than pre, immediately post and three hours post and LD levels were significantly greater 24 hours post compared to pre levels in the CON condition, with no differences between conditions. A significant main effect for time was observed for CRP (p<0.05) for time, such that CRP levels increased consistently at each subsequent time point. However, CRP and IL-6 levels were not different at any of the measured time points when comparing the two conditions. Although the current investigation was able to successfully increase muscle fluid volume and an increased CK, LD and CRP were observed, no muscle damage was observed following the eccentric exercise protocol in the CON or HYD conditions. Therefore, the hypotonic infusion used in the HYD condition proved to be a viable method to acutely increase muscle fluid content in in-vivo human skeletal muscle.

Effect of diurnal cycling temperatures on cardiovascular- ventilatory function in statically-acclimated rainbow trout, Salmo gairdneri

Four groups of rainbow trout, Salmo gairdneri, were acclimated to 2°, 10°, and 18°e, and to a diurnal temperature cycle (100 ± 4°C). To evaluate the influence of cycling temperatures in terms of an immediate as opposed to acclimatory response various ventilatory-cardiovascular rate functions were observed for trout, either acclimated to cycling temperatures or acclimated to constant temperatures and exposed to a diurnal temperature cycle for the first time (10° ± 4°C for trout acclimated to 10°C; 18°+ 4°C for trout acclimated to l8°e). Gill resistance and the cardiac to ventilatory rate ratio were then calculated. Following a post preparatory recovery period of 36 hr, measurements were made over a 48 hour period with the first 24 hours being at constant temperature in the case of statically-acclimated fish followed by 24 hours under cyclic temperature conditions. Trout exhibited marked changes in oxygen consumption (Vo ) with temp- 2 erature both between acclimation groups, and in response to the diurnal temperature cycle. This increase in oxygen uptake appears to have been achieved by adjustment of ventilatory and, to some extent, cardiovascular activity. Trout exhibited significant changes in ventilatory rate (VR), stroke volume (Vsv), and flow (VG) in response to temperature. Marked changes in cardiac rate were also observed. These findings are discussed in relation to their importance in convective oxygen transport via water and blood at the gills and tissues. Trout also exhibited marked changes in pressure waveforms associated with the action of the resp; ratory pumps with temperature. Mean differenti a 1 pressure increased with temperature as did gill resistance and utilization. This data is discussed in relation to its importance in diffusive oxygen transport and the conditions for gas exchange at the gills. With one exception, rainbow trout were able to respond to changes in oxygen demand and availability associated with changes in temperature by means of adjustments in ventilation, and possibly pafusion, and the conditions for gas exchange at the gills. Trout acclimated to 18°C, however, and exposed to high cyclic temperatures, showed signs of the ventilatory and cardiovascular distress problems commonly associated with low circulating levels of oxygen in the blood. It appears these trout were unable to fully meet the oxygen requirements associated with c~ling temperatures above 18°C. These findings were discussed in relation to possible limitations in the cardiovascular-ventilatory response at high temperatures. The response of trout acclimated to cycling temperatures was generally similar to that for trout acclimated to constant temperatures and exposed to cycling temperatures for the first time. This result suggested that both groups of fish may have been acclimated to a similar thermal range, regardless of the acclimation regime employed. Such a phenomenon would allow trout of either acclimation group to respond equally well to the imposed temperature cycle. Rainbow trout showed no evidence of significant diurnal rhythm in any parameters observed at constant temperatures (2°, 10°, and 18° C), and under a 12/12 light-dark photoperiod regime. This was not taken to indicate an absence of circadian rhythms in these trout, but rather a deficiency in the recording methods used in the study.

Ionic regulation in goldfish, Carassius auratus, acclimated to constant and diurnally-cycling temperature conditions

The effects of a diurnal sine-wave temperature cycle (250 +- 5° C) on the wa terI-e etc r o1 yt est a t us 0 f gol df1' Sh , Carassius auratus, was assessed through determination of Na+, K+, Mg2+, Ca2+, Cl- and water content in plasma, Red blood cells and muscle tissue. Animals were also acclimated to o 0 0 static temperatures (20 C, 25 c, 30 C) corresponding to the high, low and mid-ooint temperatures of the cycle. All groups were sampled at 03:00, 09:00, 15:00 and 21:00 hr. Hemoglobin content and packed cell volume, as well as electrolyte and 'water levels were determined for each animal and red cell ion concentrations and ion : hemoglobin ratios estimated. Cycled animals were distinct from those at constant temperatures in several respects. Hematological parameters were elevated above those of animals at constant temperature and were, on a diurnal basis, more stable. Red blood cell electrolyte levels varied in an adaptively appropriate fashion to cycle temperatures. This was not the case in the constant temperature groups_ Under the cycling regime, plasma ion levels were more diurnally stable than those of constant temperature fish. Although muscle parameters in cycled fish exhibited more fluctuation than was observed in plasma, these also tended to be relatively more stable than was the caseErythrocytic data are discussed in terms of their effects on hemoglobin-oxygen affinity while plasma and muscle observations were considered from the standpoint of overall water-electrolyte balance. In general, cycled fish appeared to be capable of stabilizing overall body fluid composition, while simultaneously effecting adaptively-appropriate modifications in the erythrocytic ionic microenvironment of hemoglobin. The sometimes marked diurnal variability of water-electrolyte status in animals held at constant temperature as opposed to the conservation of cycled fish suggests that this species is, in some fashion, programmed for regulation in a thermally-fluctuating environment. If this interpretation is valid and a phenomenon of general occurrence, some earlier studies involving constant acclimation of eurythermal species normally occupying habitats which vary in temperature on a daily basis may require reconsideration. at constant temperature.

The effects of the menstrual cycle and hormonal contraceptives on the central thermoeffector threshold temperatures and width of the interthreshold zone

Basal body temperature (BBT) and thermoeffector thresholds increase following ovulation in many women. This study investigated if solely central thermoregulatory alterations are responsible. Seven females in a non-contraceptive group (NCG) were compared with 5 monophasic contraceptive users (HCG) on separate accounts: pre-ovulation (Trial I; d 2-5) and post-ovulation (Trial 2; 4-8 d post-positive ovulation) for NCG, and active phase for HCG (d 2-5, d 18-21). During immersion in 28°C water to the axilla, participants exercised for 20-30 min on an underwater ergometer. After steadily sweating, immersion continued until metabolism increased two-fold due to shivering. Rectal (Tre) BBT was not different between trials for neither NCG (1: 37.34±0.16°C; 2: 37.35±0.27°C) nor HCG. At exercise termination, Tre forehead sweating cessation increased (P<0.05) in trial 2 irrespective of group (1: 37.55±0.39°C; 2: 37.90±0,46°C). Tre shivering onset did not increase (P>0.05) in trial 2 (1: 36.91±0.50°C; 2: 37.07±0,45°C). The widths of the interthreshold zone increased (P<0.05) in trial 2 (1: 0.64±0.22°C; 2: 0.82±0.37°C) due to the increased sweating threshold only. HCG cooled quicker (1: -l.15±0,43°C; 2: -1.00±0.50°C) than NCG participants (1: - 0.58±0.22°C; 2: -0.52±O.29°C), and tympanic (Tty) sweat thresholds were significantly (P<0.05) decreased (1: 34.76±0.54°C; 2: 35.39±0.61°C) versus NCG (l: 35.57±0.77°C; 2: 35.89±1.04°C). Lastly, Tre and Tty thresholds were significantly different (P

CENTRAL NORTH ATLANTIC PALEOCEANOGRAPHY DURING THE MIDDLE PLEISTOCENE (ca. 726–603 ka): INSIGHTS FROM THE DINOFLAGELLATE CYST RECORD

Integrated Ocean Drilling Program (IODP) Site U1313, located at the northern boundary of the subtropical gyre in the central North Atlantic, lies within the southern part of the ice-rafted debris belt. Seventy-three palynological samples were studied from an uninterrupted interval ca. 726–603 ka (upper Marine Isotope Stage [MIS] 18 through lower MIS 15) to resolve conflicting paleoceanographic interpretations. Glacial stages were characterized by high productivity surface waters reflecting a southward shift of the Arctic Front. Sea surface salinities (SSSs) and sea surface temperatures (SSTs) were obtained by transfer functions using the Modern Analogue Technique. The lowest SSTs of 9ºC (±1.3) and 10ºC (±1.3) were recorded in glacial MIS 16 and MIS 18 respectively. However, these reconstructions are influenced by abundant heterotrophic taxa and may reflect elevated nutrient levels rather than lowered temperatures. Reworked palynomorphs uniquely indicate a Cretaceous as well as Paleozoic provenance for the first Heinrich-like events.

Examining the roles of core and local temperature on forearm skin blood flow

The interaction between local and reflexive control of skin blood flow (SkBF) is unclear. This thesis isolated the roles of rectal (Tre) and local (Tloc) temperature on forearm SkBF regulation at normal and elevated body temperatures, and to investigate the interaction between local and reflexive SkBF control. While either normothermic (Tre ~37.0°C) or hyperthermic (∆Tre +1.1°C), SkBF was assessed on the dorsal aspect of each forearm in 10 participants while Tloc was manipulated in an A-B-A-B fashion between neutral (33.0°C) and hot (38.5°C). Finally, local heating to 44°C was performed to elicit maximal SkBF. Data are presented as a percentage of maximal cutaneous vascular conductance (CVC), calculated as laser-Doppler flux divided by mean arterial pressure. Tloc manipulations performed during normothermia had significantly greater effects on CVC than during hyperthermia. The decreased modification to SkBF from the Tloc changes during hyperthermia suggests that strong reflexive vasodilation attenuates local SkBF control mechanisms.

Seasonal reproductive endothermy in tegu lizards

With some notable exceptions, small ectothermic vertebrates are incapable of endogenously sustaining a body temperature substantially above ambient temperature. This view was challenged by our observations of nighttime body temperatures sustained well above ambient (up to 10°C) during the reproductive season in tegu lizards (~2 kg). This led us to hypothesize that tegus have an enhanced capacity to augment heat production and heat conservation. Increased metabolic rates and decreased thermal conductance are the same mechanisms involved in body temperature regulation in those vertebrates traditionally acknowledged as “true endotherms” : the birds and mammals. The appreciation that a modern ectotherm the size of the earliest mammals can sustain an elevated body temperature through metabolic rates approaching that of endotherms enlightens the debate over endothermy origins, providing support for the parental care model of endothermy, but not for the assimilation capacity model of endothermy. It also indicates that, contrary to prevailing notions, ectotherms can engage in facultative endothermy, providing a physiological analog in the evolutionary transition to true endothermy.