When fractures in otherwise hard rocks are filled with fluids (oil, gas, water, CO{sub 2}), the type and physical state of the fluid (liquid or gas) can make a large difference in the wave speeds and attenuation properties of seismic waves. The present work summarizes methods of deconstructing theses effects of fractures, together with any fluids contained within them, on wave propagation as observed in reflection seismic data. Additional studies of waves in fluid-saturated granular media show that the behavior can be quite different from that for fractured media, since these materials are typically much softer mechanically than are the fractured rocks (i.e., having a very small drained moduli). Important fluid effects in such media are often governed as much by fluid viscosity as by fluid bulk modulus.

The U.S. Department of Energy is pursuing an aggressive goal to cut the cost of solar water-heating systems in half. Replacing metal and glass components with less expensive plastic ones is a key strategy for that goal. This is a short (2-page) fact sheet about new technologies for solar water heaters.

In this article we provide a detailed description of a technique to obtain a simple parameterization for different exceptional Lie groups, such as G{sub 2}, F{sub 4} and E{sub 6}, based on their fibration structure. For the compact case, we construct a realization which is a generalization of the Euler angles for SU(2), while for the non compact version of G{sub 2(2)}/SO(4) we compute the Iwasawa decomposition. This allows us to obtain not only an explicit expression for the Haar measure on the group manifold, but also for the cosets G{sub 2}/SO(4), G{sub 2}/SU(3), F{sub 4}/Spin(9), E{sub 6}/F{sub 4} and G{sub 2(2)}/SO(4) that we used to find the concrete realization of the general element of the group. Moreover, as a by-product, in the simplest case of G{sub 2}/SO(4), we have been able to compute an Einstein metric and the vielbein. The relevance of these results in physics is discussed.

This brochure presents the capabilities that the Measurements and Characterization Division has in Analytical Microscopy, in which a variety of sophisticated techniques are used to study a material's topographical, crystallographic, structural, chemical, and luminescence properties.

This brochure presents the capabilities that the Measurements and Characterization Division has for transferring secure characterization data to clients over the Web, and for collaborating in R and D via the Web over distances (i.e., working as a virtual lab).

This brochure presents the capabilities that the Measurements and Characterization Division has in device performance, in which a variety of spectral responsivity and current-versus-voltage techniques are used to measure the spectral dependence of PV cells and module conversion efficiencies, and to measure the output performance of cells and modules under simulated and natural light.

This brochure presents the capabilities that the Measurements and Characterization Division has in Electro-Optical Characterization, in which a variety of spectroscopy, ellipsometry, and capacitance techniques are used to probe the fundamental electrical and optical properties of solid-state materials.

This brochure presents the capabilities that the Measurements and Characterization Division has in Surface Analysis, in which a variety of spectrometry and spectroscopy techniques are used to determine the chemical, elemental, and molecular composition of material surfaces and interfaces.

An account of the successful use of alternative fuels in a fleet of SuperShuttle passenger vans, which offer shared-rides between Boulder and Denver International Airport.

McStain Enterprises' new cottage-style homes built under the U.S. Department of Energy's Building America program are designed to greatly reduce energy costs and improve indoor air quality for their customers in Longmont, Colorado. In addition, energy-efficient features in the homes provide owners with greater durability and value, allow some buyers to qualify for special energy-efficient mortgages, and can result in higher resale values. Features include improved building envelope and air distribution systems, high-efficiency heating and cooling systems, improved indoor air quality, and Green Builder concepts from Colorado's Green Builder Program.

As 3D volumetric images of the human body become an increasingly crucial source of information for the diagnosis and treatment of a broad variety of medical conditions, advanced techniques that allow clinicians to efficiently and clearly visualize volumetric images become increasingly important. Interaction has proven to be a key concept in analysis of medical images because static images of 3D data are prone to artifacts and misunderstanding of depth. Furthermore, fading out clinically irrelevant aspects of the image while preserving contextual anatomical landmarks helps medical doctors to focus on important parts of the images without becoming disoriented. Our goal was to develop a tool that unifies interactive manipulation and context preserving visualization of medical images with a special focus on diffusion tensor imaging (DTI) data. At each image voxel, DTI provides a 3 x 3 tensor whose entries represent the 3D statistical properties of water diffusion locally. Water motion that is preferential to specific spatial directions suggests structural organization of the underlying biological tissue; in particular, in the human brain, the naturally occuring diffusion of water in the axon portion of neurons is predominantly anisotropic along the longitudinal direction of the elongated, fiber-like axons [MMM+02]. This property has made DTI …

Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for …

Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for …

Biodiesel is defined as fatty acid mono-alkylesters and is produced from triacylglycerols. In the current article we provide an overview of the structure, diversity and regulation of the metabolic pathways leading to intracellular fatty acid and triacylglycerol accumulation in three types of organisms (bacteria, algae and fungi) of potential biotechnological interest and discuss possible intervention points to increase the cellular lipid content. The key steps that regulate carbon allocation and distribution in lipids include the formation of malonyl-CoA, the synthesis of fatty acids and their attachment onto the glycerol backbone, and the formation of triacylglycerols. The lipid biosynthetic genes and pathways are largely known for select model organisms. Comparative genomics allows the examination of these pathways in organisms of biotechnological interest and reveals the evolution of divergent and yet uncharacterized regulatory mechanisms. Utilization of microbial systems for triacylglycerol and fatty acid production is in its infancy; however, genomic information and technologies combined with synthetic biology concepts provide the opportunity to further exploit microbes for the competitive production of biodiesel.

Contaminants in soil can impact human health and the environment through a complex web of interactions. Soils exist where the atmosphere, hydrosphere, geosphere, and biosphere converge. Soil is the thin outer zone of the earth's crust that supports rooted plants and is the product of climate and living organisms acting on rock. A true soil is a mixture of air, water, mineral, and organic components. The relative proportions of these components determine the value of the soil for agricultural and for other human uses. These proportions also determine, to a large extent, how a substance added to soil is transported and/or transformed within the soil (Spositio, 2004). In mass-balance models, soil compartments play a major role, functioning both as reservoirs and as the principal media for transport among air, vegetation, surface water, deeper soil, and ground water (Mackay, 2001). Quantifying the mass transport of chemicals within soil and between soil and atmosphere is important for understanding the role soil plays in controlling fate, transport, and exposure to multimedia pollutants. Soils are characteristically heterogeneous. A trench dug into soil typically reveals several horizontal layers having different colors and textures. As illustrated in Figure 1, these multiple layers are often divided into …

Just imagine living in Florida and your fantasies might turn to swaying palms, fresh orange juice and lots of air-conditioning. For most people, a summer spent in Florida's heat and humidity would be unbearable without it. So air-conditioning is a necessity. But it's also a big energy drain, accounting for about 35% of all electricity used in a typical Florida house. As the largest single source of energy consumption in Florida, a home's air-conditioning load represents the biggest energy challenge. The Florida Solar Energy Center (FSEC) designed a project to answer this challenge. Two homes were built with the same floor plan on near-by lots. The difference was that one (the ''control home'') conformed to local residential building practices, and the other (the ''Zero Energy home'') was designed with energy efficiency in mind and solar technology systems on the roof. The homes were then monitored carefully for energy use. The project's designers were looking to answer two important questions: Could a home in a climate such as central Florida's be engineered and built so efficiently that a relatively small PV system would serve the majority of its cooling needs--and even some of its daytime electrical needs? And, would that home …

NREL PV Working With Industry is a quarterly newsletter devoted to the research, development, and deployment performed by NREL staff in concert with their industry and university partners. The Fourth Quarter, 1999 issue, titled ''Knowledge is PV Power'' focuses on the contribution of the university-based subcontractors to the PV Program. The editorialist is Robert Birkmire, Director of the Institute of Energy Conversion, which is affiliated with the University of Delaware.

This issue of Alternative Fuel News contains information on the upcoming Clean Cities Conference to be held May 7--10, 2000 in San Diego, California. Highlighted in this issue is the success of the Clean Cities Program in creating clean corridors that permit fleets that serve multiple cities to purchase AFVs with confidence, knowing that fueling convenience and supply will not be a problem. Also look for articles on electric vehicles, transit buses; state and fuel provider enforcement; the Salt Lake and Greater Long Island Clean Cities coalitions, HEVs and fuel cells are a big hit at auto shows; DOE awards alternative fuel grants to 33 National Parks; and the Energy Policy Act (EPAct) Section 506 report.

This booklet is designed to guide you through the process of buying a grid-tied solar electric system. A word of caution: This is not a technical guide for designing or installing your system.

In a typical Florida house, air-conditioning accounts for about 35% of all the electricity the home uses. As the largest single source of energy consumption in Florida, a home's air-conditioning load represents the biggest energy challenge facing Florida residents. The Florida Solar Energy Center designed a project to meet this challenge. Two homes were built with the same floor plan on near-by lots. The difference was that one (the control home) conformed to local residential building practices, and the other (the Zero Energy home) was designed with energy efficiency in mind and a solar technology system on the roof. The homes were then monitored carefully for energy use. The projects designers were looked to answer two questions: (1) could a home in a climate such as central Florida be engineered and built so efficiently that a relatively small PV system would serve the majority of its cooling needs--and even some of its daytime electrical needs; and (2) would that home be as comfortable and appealing as the conventional model built alongside it? The answer was yes, even though it was conducted in the summer of 1998--one of the hottest summers on record in Florida.

This Wind Powering America brochure provides the perspectives on the benefits of wind power from 10 U.S. citizens from different sectors of society, including ranching, utility commissioner, parent, Native American, farmer/county commissioner, business owner, and independent turbine operator. It also provides basic facts about wind power, contacts for information about wind power, and a brief description of the Wind Powering America Initiative, its goals and its benefits.

A description of Tiger Teams, sponsored by DOE and NREL to help implement the use of alternative fuels by constituents of DOE's Clean Cities coalitions.

A small brochure about solar electricity for the general public to be handed out on Earth Day 2000.

Clouds present substantial concentrations of liquid-phase water, which can potentially serve as a medium for dissolution and reaction of atmospheric gases. The important precursors of acid deposition, SO{sub 2} and nitrogen oxides NO and NO{sub 2} are only sparingly soluble in clouds without further oxidation to sulfuric and nitric acids. In the case of SO{sub 2} aqueous-phase reaction with hydrogen peroxide, and to lesser extent ozone, are identified as important processes leading to this oxidation, and methods have been described by which to evaluate the rates of these reactions. The limited solubility of the nitrogen oxides precludes significant aqueous-phase reaction of these species, but gas-phase reactions in clouds can be important especially at night.