Geomorphic evolution of pleistocene Lake Bonneville: temporal implications for surface processes on Mars

Journal ArticlePleistocene Lake Bonneville of the Great Basin offers unparalleled insight into temporal constraints for understanding the development of similar analog environments and processes on Mars. The extensive and well preserved lake system exhibits many intact features that include: prominent shorelines, spits, bay mouth barriers, deltas, gullies, outburst channels, and playa lake features, including patterned grounds and downwind aeolian systems. Although water is recognized as a geomorphic agent on Mars, remotely sensed datasets by themselves have limited utility for inferring how long it took for the formation of specific features. With the Lake Bonneville analog, we can address how long standing water might be geomorphically effective, and infer the rate of development for specific landforms (e.g., coastlines, wavecut terraces, outflow channels, rills)

The geology and geothermal setting of the Magic Reservoir Area, Blaine and Camas Counties, Idaho

Journal ArticleThe Magic Reservoir area straddles the Blaine- Camas county line in south-central Idaho, along the northern boundary of the central Snake River Plain. The rocks exposed at Magic Reservoir include a 5.8- million-year-old rhyolite flow, the Pliocene Square Mountain Basalt, multiple cooling units of a 5.6- million-year-old rhyolite ash-flow tuff, a 4.7-millionyear- old rhyolite dome, and Quaternary basalt flows and sediments. These newly reported ages for the rhyolites at Magic Reservoir reveal that they are the youngest, westernmost silicic volcanic rocks presently known in the Snake River Plain. They represent an anomalously young rhyolitic event that may include the Moonstone Mountain rhyolite dome to the northwest and the previously dated (Armstrong and others, 1975) 3-million-ycar-old Wedge Butte rhyolite dome to the southeast of Magic Reservoir. The area is cut by numerous normal faults trending northwest, northeast, and west. The northwest-trending faults are the dominant structures. They form a horst block at Hot Springs Landing and parallel the regional structural grain. The geothermal resource at Magic Reservoir occurs within the elevated heat flow province at the northern margin of the Snake River Plain. The system is probably controlled by the deep, convectivce circulation of fluids along faults at the intersection of the Hot Springs Landing horst with west- and northeast-trending fractures. Although the volcanic rocks in the Magic Reservoir area are young, they are too old to contribute any magmatic heat to the geothermal system

Geochemical variations in an alpine lake and watershed underlain by siliciclastic bedrock, Uinta Mountains, Utah

Journal ArticleA small watershed which includes several small lakes in the Uinta Mountains of northern Utah is underlain by monolithologic Precambrian siliciclastic rock with extremely limited buffering capacity. In spite of this, s\ stematic spatial and temporal variations in alkalinity, pH, and major elements occur in springs, small streams, and one lake within the watershed. Alkalinity changes by 3-fold over 1 km of vertical elevation within the watershed. Cations and silica show similar although less dramatic changes with respect to elevation. Silicate weathering seems to constitute the dominant mechanism of alkalinity generation. The water column in Marshall Lake shows significant seasonal stratification of temperature and chemical constituents. Vertical variation of alkalinity in the lake during the summer is related to the input of geochemically distinct water sources in the watershed. Vertical pH variations in Marshall Lake do not match alkalinity variations but instead are related to photosynthesis in the upper and middle portions of the water column. Thermal and chemical stratification is greater in the lake than in well-studied alpine lakes of the Sierra Nevada. Numerical hydrodynamic models suggest that temperature and chemical stratification of this Uinta Mountain lake can be attributed to lake depth (13 m vs more shallow depths of the Sierra lakes) or relatively weak wind shear stress. The combined watershed/lake study demonstrates the need for complete vertical water sampling in order to accurately characterize the geochemistry of deep (> 10 m) alpine lakes

Resistance estimation for temperature determination in PMSMs through signal injection

Real-time thermal management of electrical machines relies on sufficiently accurate indicators of temperature within a machine. One indicator of temperature in a permanent-magnet synchronous motor (PMSM) is the stator winding resistance. Detection of PMSM winding resistance in the literature has been made on machines with relatively high resistances, where the resistive voltage vector is significant under load. This paper describes a technique applied to sense the winding resistance where the resistance is low and hence the resistive is voltage difficult to detect. A current injection method is applied which enables the resistance to be determined, and hence the winding temperature in non-salient machines. This method can be applied under load, and in a manner that does not disturb shaft torque, or speed. The method is able to distinguish between changes in the electro-motive force (EMF) constant and the resistive voltage. Simulated results on an experimentally verified model illustrate the effectiveness of this approac

Controllability analysis of multi objective control systems

The performance requirements stated in project specifications often comprise conflicting objectives. These objectives may further be a complex mix of steady state and dynamic performance. Control devices such as solenoid actuators are often chosen purely on steady state force characteristics, due to the difficulty of appraising the conflicting and generally non-linear nature of the performance objectives. This can have ramifications in terms not only of the actuator performance, but also in the overall controllability of the system when closed-loop control is implemented. An example automotive application examining the multi objective controllability of electronically actuated valves is presented. Multi objective evolutionary techniques are utilised to derive the optimal force-displacement characteristics and also dynamic characteristics of the desired actuator under the constraint of design performance criteria. The selected actuator is then assessed for its controllability and dynamic performance

Detection of Organic-Rich Oil Shales of the Green River Formation, Utah, with Ground-Based Imaging Spectroscopy

Oil shales contain abundant immature organic matter and are a potential unconventional petroleum resource. Prior studies have used visible/shortwave infrared imaging spectroscopy to map surface exposures of deposits from satellite and airborne platforms and image cores in the laboratory. Here, we work at an intermediate, outcrop-scale, testing the ability of field-based imaging spectroscopy to identify oil shale strata and characterize the depositional environments that led to enrichment of organic matter in sedimentary rocks within the Green River Formation, Utah, USA. The oil shale layers as well as carbonates, phyllosilicates, gypsum, hydrated silica, and ferric oxides are identified in discrete lithologic units and successfully mapped in the images, showing a transition from siliciclastic to carbonate- and organic-rich rocks consistent with previous stratigraphic studies conducted with geological fieldwork

Tailoring force-displacement characteristics in medium-stroke linear variable reluctance actuators

The paper is concerned with the design of medium-stroke variable reluctance actuators that exploit the tangential component of force. A method of compensating for the roll-off in force as the stator and armature come into full alignment is presented, and the scope which this offers to tailor the force-displacement characteristic to meet the demands of a particular application is illustrated by means of a case study. The case study includes finite element analysis and experimental measurements on an actuator having a stroke of 8 mm and a rated force capability of 60 N

Co-administration of GF120918 significantly increases the systemic exposure to oral paclitaxel in cancer patients

Oral bioavailability of paclitaxel is very low, which is due to efficient transport of the drug by the intestinal drug efflux pump P-glycoprotein (P-gp). We have recently demonstrated that the oral bioavailability of paclitaxel can be increased at least 7-fold by co-administration of the P-gp blocker cyclosporin A (CsA). Now we tested the potent alternative orally applicable non-immunosuppressive P-gp blocker GF120918. Six patients received one course of oral paclitaxel of 120 mg/m2 in combination with 1000 mg oral GF120918 (GG918, GW0918). Patients received intravenous (i.v.) paclitaxel 175 mg/m2 as a 3-hour infusion during subsequent courses. The mean area under the plasma concentration–time curve (AUC) of paclitaxel after oral drug administration in combination with GF120918 was 3.27 ± 1.67 μM.h. In our previously performed study of 120 mg/m2 oral paclitaxel in combination with CsA the mean AUC of paclitaxel was 2.55 ± 2.29 μM.h. After i.v. administration of paclitaxel the mean AUC was 15.92 ± 2.46 μM.h. The oral combination of paclitaxel with GF120918 was well tolerated. The increase in systemic exposure to paclitaxel in combination with GF120918 is of the same magnitude as in combination with CsA. GF120918 is a good and safe alternative for CsA and may enable chronic oral therapy with paclitaxel. © 2001 Cancer Research Campaign http://www.bjcancer.co

Meeting Report: Consensus Statement—Parkinson’s Disease and the Environment: Collaborative on Health and the Environment and Parkinson’s Action Network (CHE PAN) Conference 26–28 June 2007

BackgroundParkinson's disease (PD) is the second most common neurodegenerative disorder. People with PD, their families, scientists, health care providers, and the general public are increasingly interested in identifying environmental contributors to PD risk.MethodsIn June 2007, a multidisciplinary group of experts gathered in Sunnyvale, California, USA, to assess what is known about the contribution of environmental factors to PD.ResultsWe describe the conclusions around which they came to consensus with respect to environmental contributors to PD risk. We conclude with a brief summary of research needs.ConclusionsPD is a complex disorder, and multiple different pathogenic pathways and mechanisms can ultimately lead to PD. Within the individual there are many determinants of PD risk, and within populations, the causes of PD are heterogeneous. Although rare recognized genetic mutations are sufficient to cause PD, these account for < 10% of PD in the U.S. population, and incomplete penetrance suggests that environmental factors may be involved. Indeed, interplay among environmental factors and genetic makeup likely influences the risk of developing PD. There is a need for further understanding of how risk factors interact, and studying PD is likely to increase understanding of other neurodegenerative disorders

Lions and Prions and Deer Demise

Background: Contagious prion diseases – scrapie of sheep and chronic wasting disease of several species in the deer family – give rise to epidemics that seem capable of compromising host population viability. Despite this prospect, the ecological consequences of prion disease epidemics in natural populations have received little consideration. Methodology/Principal Findings: Using a cohort study design, we found that prion infection dramatically lowered survival of free-ranging adult (.2-year-old) mule deer (Odocoileus hemionus): estimated average life expectancy was 5.2 additional years for uninfected deer but only 1.6 additional years for infected deer. Prion infection also increased nearly fourfold the rate of mountain lions (Puma concolor) preying on deer, suggesting that epidemics may alter predator–prey dynamics by facilitating hunting success. Despite selective predation, about one fourth of the adult deer we sampled were infected. High prevalence and low survival of infected deer provided a plausible explanation for the marked decline in this deer population since the 1980s. Conclusion: Remarkably high infection rates sustained in the face of intense predation show that even seemingly complete ecosystems may offer little resistance to the spread and persistence of contagious prion diseases. Moreover, the depression of infected populations may lead to local imbalances in food webs and nutrient cycling in ecosystems in which deer ar