Seismic Reflection Studies in Long Valley Caldera, Califomia

This is the published version, also available here: http://dx.doi.org/10.1029/90JB02401.Seismic reflection studies in Long Valley caldera, California, indicate that seismic methods may be successfully employed to image certain types of features in young silicic caldera environments. However, near-surface geological conditions within these environments severely test the seismic reflection method. Data quality are degraded by static, reverberation, and band-limiting problems due to these near-surface conditions. In Long Valley, seismic reflection and refraction methods were used to image both the shallow and deep geothermal aquifers within the area. The deep geothermal aquifer, the welded Bishop Tuff, was imaged as a fairly continuous reflector across the western moat of the caldera. Near-surface refraction information indicates that there may be a buried paleochannel system or horst and graben system that could control the shallow geothermal flow pattern. High-amplitude events observed in a wide-angle survey were originally interpreted as reflections from a contemporary magma body. However, a migration of the events utilizing the new generalized cellular migration algorithm indicates that these events are probably reflections from the faults of the caldera ring fracture system. The reflections may be caused by the high acoustic impedance contrast associated with the juxtaposition of relatively low-velocity, low-density, caldera fill against the granite plutons and metasediments of the Sierran basement along this fault system

Acoustic wave studies during fast ion beam interactions with solds

Ion beam material modification is currently being used for several important technological applications such as semiconductor doping [1], surface modification of metals [2], cold etching [1], micro machining [1] and material analysis [3]. Ion beam processing has many advantages [4]. The speed, homogeneity and reproducibility of the doping process are easily controlled. Tight control of the number of doping atoms is possible. Low purity dopants can be used. The target can be kept at low temperatures allowing for low melting temperature materials to be modified. Simple masking methods can be employed and doping can be performed through passive films. Low penetration depths can be achieved and multiple implantations can produce varied doping profiles. Devices with small dimensions can be manufactured due to the small size of the ion beam. Since ion implantation is not an equilibrium process, equilibrium solubility limits of the ion species in the target material can be exceeded. There are some disadvantages of this type of doping process. Damage is caused to the crystal structure creating defects. Implantation is limited to near-surface regions and theoretical profiles can be difficult to obtain due to effects of channeling and diffusion [5]

Cardiorespiratory Responses during Aquatic Treadmill Exercise and Land Treadmill Exercise in Adults with Diabetes

The purpose of this study was to compare the effect of aquatic treadmill (ATM) exercise to land treadmill (LTM) exercise in adults with type 2 diabetes. Five participants with type 2 diabetes (T2D group; 4 females, 1 male; age = 51±6 years; height = 170±7 cm; weight = 96±24 kg; body fat = 31.6±2.2%) and five participants without type 2 diabetes (control group; 4 females, 1 male; age = 51±6 years; height = 170±6 cm; weight = 71±15 kg; body fat = 26.8±4.6%) completed the study. Protocols for both ATM exercise and LTM exercise began at 2 mph with 0% grade and increased by 1 mph after 5 minutes at each stage. Termination occurred after participants completed the protocol or reached 85% of heart rate reserve. Heart rate, absolute and relative VO2, and systolic and diastolic blood pressure were measured at rest and during steady-state exercise at each intensity. Mean arterial pressure (MAP) was calculated. A 2 x 2 x 3 Mixed Factorial ANOVA and Bonferroni post hoc test with a significance level of .0125 were used. There was a significant difference (p2 of the two groups at 4 mph while performing the land treadmill exercise (T2D: 14.1±1.4 ml/kg/min vs. control: 18.4±1.6 ml/kg/min, p2 between participant groups or modes of exercise. Those with type 2 diabetes had an increased MAP versus those without type 2 diabetes while performing the land treadmill exercise at 2 mph (T2D: 93±3 mmHg vs. control: 81±5 mmHg, p2, and MAP respond similarly in both groups during ATM and LTM exercise at most treadmill speeds

Automated nondestructive evaluation method for characterizing ceramic and metallic hot gas filters.

In advanced coal-fired power generation, one technology under development to clean up hot gases before their use as fuel for gas turbines is rigid ceramic candle filters. These porous filters are typically 1.5 m long and 60 mm in diameter and are made of various ceramic materials, including clay-bonded SiC. The high costs of downtime in a large utility demands that nondestructive evaluation/characterization (NDE/C) methods be available. At shutdowns, data from such analysis are needed to decide which filters are still usable and which need to be replaced, and if possible, to estimate the remaining lifetimes. Thus our objective was to develop reliable low-cost NDE technology for these filters. Our approach was to develop NDE/C technology, referred to as acousto-ultrasonics (AU), for application to hot gas filters. Lamb waves generated by the AU method were analyzed to derive a stress wave factor (SWF). This technology was tested by comparing SWF data with the measured strength for a variety of rigid ceramic filters and was shown to work on iron-aluminide filters as well but no strength data have been obtained on the iron-aluminides at this time

Chapter 7: Wetlands

Contains fulltext : 205862.pdf (publisher's version ) (Open Access

Seismic imaging in Long Valley, California, by surface and borehole techniques: An investigation of active tectonics

The search for silicic magma in the upper crust is converging on the Long Valley Caldera of eastern California, where several lines of geophysical evidence show that an active magma chamber exists at mid‐to lower‐crustal depths. There are also other strong indications that magma may be present at depths no greater than about 5 km below the surface. In this paper, we review the history of the search for magma at Long Valley. We also present the preliminary results from a coordinated suite of seismic experiments, conducted by a consortium of institutions in the summer and fall of 1984, that were designed to refine our knowledge of the upper extent of the magma chamber. Major funding for the experiments was provided by the Geothermal Research Program of the U.S. Geological Survey (USGS) and by the Magma Energy Technology Program of the U.S. Department of Energy (DOE), a program to develop the technology necessary to extract energy directly from crustal magma. Additional funding came from DOE's Office of Basic Energy Sciences and the National Science Foundation (NSF). Also, because extensive use was made of a 0.9‐km‐deep well lent to us by Santa Fe Geothermal, Inc., the project was conducted partly under the auspices of the Continental Scientific Drilling Program (CSDP). As an integrated seismic study of the crust within the caldera that involved the close cooperation of a large number of institutions, the project was moreover viewed as a prototype for future scientific experiments to be conducted under the Program for Array Seismic Studies of the Continental Lithosphere (PASSCAL). The experiment thus represented a unique blend of CSDP and PASSCAL methods, and achieved goals consistent with both programs

Aquatic Ecosystems are the Largest Source of Methane on Earth

Methane concentrations in the atmosphere have almost tripled since the industrial revolution, contributing 16% of the additional radiative forcing by anthropogenic greenhouse gas emissions. Aquatic ecosystems are an important but poorly constrained source of methane (CH4) to the atmosphere. Here, we present the first global methane emission assessment from all major natural, impacted and human-made aquatic ecosystems including streams and rivers, freshwater lakes and reservoirs, aquaculture ponds, estuaries, coastal vegetated wetlands (mangroves, salt-marshes, seagrasses), tidal flats, continental shelves and the open ocean, in comparison to recent estimates from natural wetlands and rice paddies. We find that aquatic systems are the largest source of methane globally with contributions from small lakes and coastal ocean ecosystems higher than previously estimated. We suggest that increased biogenic methane from aquatic ecosystems due to a combined effect of climate-feedbacks and human disturbance, may contribute more than expected to rising methane concentrations in the atmosphere

Concentration-Dependent Effects of a Dietary Ketone Ester on Components of Energy Balance in Mice

Exogenous ketones may provide therapeutic benefit in treatment of obesity. Administration of the ketone ester (KE) R,S-1,3-butanediol acetoacetate diester (BD-AcAc) decreases body weight in mice, but effects on energy balance have not been extensively characterized. The purpose of this investigation was to explore concentration-dependent effects of BD-AcAc on energy intake and expenditure in mice. Forty-two male C57BL/6J mice were randomly assigned to one of seven isocaloric diets ( = 6 per group): (1) Control (CON, 0% KE by kcals); (2) KE5 (5% KE); (3) KE10 (10% KE); (4) KE15 (15% KE); (5) KE20 (20% KE); (6) KE25 (25% KE); and (7) KE30 (30% KE) for 3 weeks. Energy intake and body weight were measured daily. Fat mass (FM), lean body mass (LBM), and energy expenditure (EE) were measured at completion of the study. Differences among groups were compared to CON using ANOVA and ANCOVA. Mean energy intake was similar between CON and each concentration of KE, except KE30 which was 12% lower than CON ( \u3c 0.01). KE25 and KE30 had lower body weight and FM compared to CON, while only KE30 had lower LBM ( \u3c 0.03). Adjusted resting and total EE were lower in KE30 compared to CON ( \u3c 0.03), but similar for all other groups. A diet comprised of 30% energy from BD-AcAc results in lower energy intake, coincident with lower body weight and whole animal adiposity; while KE20 and KE25 have significantly lower body weight and adiposity effects independent of changes in energy intake or expenditure

Aquatic Ecosystems are the Most Uncertain but Potentially Largest Source of Methane on Earth

Atmospheric methane is a potent greenhouse gas that has tripled in concentration since pre-industrial times. The causes of rising methane concentrations are poorly understood given its multiple sources and complex biogeochemistry. Natural and human-made aquatic ecosystems, including wetlands, are potentially the largest single source of methane, but their total emissions relative to other sources have not been assessed. Based on a new synthesis of inventory, remote sensing and modeling efforts, we present a bottom-up estimate of methane emissions from streams and rivers, freshwater lakes and reservoirs, estuaries, coastal wetlands (mangroves, seagrasses, salt-marshes), intertidal flats, aquaculture ponds, continental shelves, along with recently published estimates of global methane emissions from freshwater wetlands, rice paddies, the continental slope and open ocean. Our findings emphasize the high variability of aquatic methane fluxes and a possibly skewed distribution of currently available data, making global estimates sensitive to statistical assumptions. Mean emissions make aquatic ecosystems the largest source of methane globally (53% of total global methane emissions). Median emissions are 42% of the total global methane emissions. We argue that these emissions will likely increase due to urbanization, eutrophication and climate change

Concentration-Dependent Effects of a Dietary Ketone Ester on Components of Energy Balance in Mice

Objectives: Exogenous ketones may provide therapeutic benefit in treatment of obesity. Administration of the ketone ester (KE) R,S-1,3-butanediol acetoacetate diester (BD-AcAc2) decreases body weight in mice, but effects on energy balance have not been extensively characterized. The purpose of this investigation was to explore concentration-dependent effects of BD-AcAc2 on energy intake and expenditure in mice.Methods: Forty-two male C57BL/6J mice were randomly assigned to one of seven isocaloric diets (n = 6 per group): (1) Control (CON, 0% KE by kcals); (2) KE5 (5% KE); (3) KE10 (10% KE); (4) KE15 (15% KE); (5) KE20 (20% KE); (6) KE25 (25% KE); and (7) KE30 (30% KE) for 3 weeks. Energy intake and body weight were measured daily. Fat mass (FM), lean body mass (LBM), and energy expenditure (EE) were measured at completion of the study. Differences among groups were compared to CON using ANOVA and ANCOVA.Results: Mean energy intake was similar between CON and each concentration of KE, except KE30 which was 12% lower than CON (P < 0.01). KE25 and KE30 had lower body weight and FM compared to CON, while only KE30 had lower LBM (P < 0.03). Adjusted resting and total EE were lower in KE30 compared to CON (P < 0.03), but similar for all other groups.Conclusions: A diet comprised of 30% energy from BD-AcAc2 results in lower energy intake, coincident with lower body weight and whole animal adiposity; while KE20 and KE25 have significantly lower body weight and adiposity effects independent of changes in energy intake or expenditure