The late Archaean-early Proterozoic Witwatersrand basin is situated in the center of the Kaapvaal craton, South Africa. Two new heat flow determinations and 71 new heat flow estimates permit excellent definition of the heat flow pattern. Nonvertical heat conduction explains much of the observed local heat flow variability. Regionally, the heat flow in the basin is uniform, and the overall mean (51+6 mW m -2) is higher than the mean heat flow for Archaean cratons. Published data indicate that heat generated in the basin's strata (---7.5 mW m -2) is largely responsible for the excess heat flow; the subsediment heat flux is ---43.5 mW m -:. Seven new heat flow and heat production determinations in Archaean granite domes northwest of the basin average 33+2 mW m -: and 2.3+0.8 •zW m -3, respectively. Contrasted with the heat flux across the floor of the basin, the lower heat flow in the domes probably reflects a smaller radiogenic contribution from the crystalline crust below the domes. Published heat production data from upturned granitic basement exposed in the Vredefort dome in the center of the basin indicate that the radioactive contribution from the crust below the basin is --26.5 mW m -2.Subtracting this value and the contribution from the strata (--7.5 mW m -:) from the basin's surface heat flow (51 mW m -:) indicates that the heat flux through the Moho is approximately 17 mW m -2. Calculated lithospheric temperatures agree closely with pressure-temperature regimes inferred from studies of mantle inclusions in kimberlites in the Kaapvaal craton. Both data sets indicate that the cratonic lithosphere is considerably cooler and thicker than that below an equilibrium ocean. Implications of the cold, thick cratonic lithosphere for understanding the distribution of southern African diamondiferous kimberlites, and the density and buoyancy of the lithosphere, are discussed. been extensively mined and drilled during the 100 years since they were found to contain gold. Planning for refrigeration of deep mines necessitated a program of virgin rock temperature (VRT) measurements. This program resulted in a reasonably accurate knowledge of the temperature distribution to a depth of--•3 km within the strata on the margin of the basin. The regional pattern is illustrated in Figure 3, which shows average depths to various isotherms along the mining arc extending from Welkom in the south to Evander in the northeast. The extensive VRT data set summarized in Figure 3 suggests that the Witwatersrand basin should be one of the best geothermally understood basins, but only eight heat flow values have been determined [Bullard, 1939; Carte, 1954; Carte and van Rooyen, 1969]. This paper summarizes results of thermal conductivity measurements on rock formations in the basin and combines mean conductivities with documented borehole temperature gradients to obtain 71 new heat flow estimates. Heat flow determinations in two other boreholes in the basin are presented, as are heat flow and heat production determinations in seven boreholes t...

Accumulating epidemiological evidence supports the notion of brain reserve, but there has been no investigation of neurobiological change associated with brief mental activation training in humans. Healthy older individuals were therefore investigated with magnetic resonance spectroscopy (MRS) in different brain regions before and after 5 weeks of focused memory training. Recall of a test-word list of > 23 items was achieved accompanied by elevation of creatine and choline signals in the hippocampus. Those at risk for neural dysfunction, as indicated by lower neurometabolites at baseline, demonstrated the largest MRS increases after training. Biochemical changes related to cellular energy and cell-membrane turnover were found to increase after structured memory exercises and were limited to the medial temporal lobe.

Wildlife populations of conservation concern are limited in distribution, population size and persistence by various factors, including mortality. The fisher (Pekania pennanti), a North American mid-sized carnivore whose range in the western Pacific United States has retracted considerably in the past century, was proposed for threatened status protection in late 2014 under the United States Endangered Species Act by the United States Fish and Wildlife Service in its West Coast Distinct Population Segment. We investigated mortality in 167 fishers from two genetically and geographically distinct sub-populations in California within this West Coast Distinct Population Segment using a combination of gross necropsy, histology, toxicology and molecular methods. Overall, predation (70%), natural disease (16%), toxicant poisoning (10%) and, less commonly, vehicular strike (2%) and other anthropogenic causes (2%) were causes of mortality observed. We documented both an increase in mortality to (57% increase) and exposure (6%) from pesticides in fishers in just the past three years, highlighting further that toxicants from marijuana cultivation still pose a threat. Additionally, exposure to multiple rodenticides significantly increased the likelihood of mortality from rodenticide poisoning. Poisoning was significantly more common in male than female fishers and was 7 times more likely than disease to kill males. Based on necropsy findings, suspected causes of mortality based on field evidence alone tended to underestimate the frequency of disease-related mortalities. This study is the first comprehensive investigation of mortality causes of fishers and provides essential information to assist in the conservation of this species.

Interspecific killing is common among carnivores and can have population-level effects on imperiled species. The fisher (Pekania [Martes] pennanti) is a rare forest carnivore in western North America and a candidate for listing under the United States Endangered Species Act. Interspecific killing and intraguild predation are poorly understood in fishers and potential threats to existing western populations. We studied the prevalence and patterns of interspecific killing of fishers in the southern Sierra Nevada and Coastal Range of California. We collected forensic evidence and samples from the carcasses and predation sites, conducted full necropsies when possible, and used molecular methods to determine species of predators responsible for killing fishers. We recovered 101 (59 female, 42 male) fisher carcasses; for 62 (61%) carcasses, we attributed cause of death to interspecific killing. We found that bobcats (Lynx rufus, n ¼ 25 fisher mortalities), mountain lions (Puma concolor, n ¼ 20), and coyotes (Canis latrans, n ¼ 4) were predators of fishers in our study areas. Bobcats killed only female fishers, whereas mountain lions more frequently killed male than female fishers, confirming our hypothesis that female fishers would suffer lethal attacks by smaller predators than would male fishers. Coyotes rarely killed fishers. We found differences in pathologic characteristics of the predation events among the 3 predator species, which may be helpful in identifying predator species. Ó

Results of heat flow and heat production surveys at 13 localities in the Namaqua mobile belt, southern Africa, are presented. Twelve stations traverse the 1200-1100 m.y. old gneissic and metamorphic Bushmanland and Gordonia subprovinces. One station is situated in the Richtersveld subprovince, a 2000-1730 m.y. old volcano-sedimentary domain mildly affected by the 1200-1100 m.y. old orogeny. Surface heat flow in the mobile belt ranges from 39 to 81 mW m -2 and averages at 61+11 mW m -2. Surface heat production ranges from 0.8 •W m -3 in mafic rocks to extreme values of 6.9-12.3 •W m -3 in the Springbok district, western Namaqualand. High heat production in the Springbok district is associated with a thin, tabular granitic intrusive and is not representative of the basement. The mean heat production of the remaining stations in the mobile belt is 2.3+1.1 •W m -3. Linear regression analysis of the heat flow-heat production data yields a poor fit (correlation coefficient = 0.62) and imprecise estimates for the intercept (34+6 mW m -•) and slope (11+3 kin). The eastern margin of the mobile belt has relatively low heat flow and heat production; geothermal, geological, and gravity data suggest a relative depletion of crustal radiogenic heat production in the region. However, the average Namaqua heat flow is higher than worldwide averages for Proterozoic terrains. There is no geological or geophysical evidence for recent mantle heating below the Namaqua mobile belt, suggesting that an elevated crustal radioactive component is largely responsible for the elevated heat flow. In this respect, the mobile belt is similar to several mid-late Proterozoic heat flow provinces that are characterized by high average surface heat flow and probably have elevated crustal radiogenic heat input. These observations, and seismic data, suggest that the Namaqua crust consists of an upper layer that contributes 40-50%, on average, to the heat flow and a depleted lower layer; the inferred heat flow at midcrustal levels is 50-60% of the average surface heat flow. The mobile belt's average surface heat flow is 40-85% higher than that from the basement of the adjacent Archaean Kaapvaal craton, and its inferred midcrustal heat flow is similar to the lowest surface values in the craton. Heat production data from the Kaapvaal craton indicate that its upper crust is not depleted of heat sources. While enhanced radiogenic heat input from the Namaqua upper crust may account for part of the higher-than-craton heat flow, it cannot account for the full excess. Consequently, a larger equilibrium mantle heat flow, related to a reduced lithospheric thickness below Namaqualand, seems to be required by the new data. well-represented area is the central part of the Archaean Kaapvaal craton (Figure 1) where nine published results fall in the range 36-54 mW m -2. Scattered measurements in the younger mobile belts surrounding the craton yield higher values, reaching 69 mW m -2. These observations suggest that the craton and the mobile belts have different geother...