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At least 811 records · Page 45

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DOE OSTI2019

Multiomics resolution of molecular events during a day in the life of Chlamydomonas

The unicellular green alga Chlamydomonas reinhardtii displays metabolic flexibility in response to a changing environment. We analyzed expression patterns of its three genomes in cells grown under light–dark cycles. Nearly 85% of transcribed genes show differential expression, with different sets of transcripts being up-regulated over the course of the day to coordinate cellular growth before undergoing cell division. Parallel measurements of select metabolites and pigments, physiological parameters, and a subset of proteins allow us to infer metabolic events and to evaluate the impact of the transcriptome on the proteome. Among the findings are the observations that Chlamydomonas exhibits lower respiratory activity at night compared with the day; multiple fermentation pathways, some oxygen-sensitive, are expressed at night in aerated cultures; we propose that the ferredoxin, FDX9, is potentially the electron donor to hydrogenases. The light stress-responsive genes PSBS , LHCSR1 , and LHCSR3 show an acute response to lights-on at dawn under abrupt dark-to-light transitions, while LHCSR3 genes also exhibit a later, second burst in expression in the middle of the day dependent on light intensity. Each response to light (acute and sustained) can be selectively activated under specific conditions. Our expression dataset, complemented with coexpression networks and metabolite profiling, should constitute an excellent resource for the algal and plant communities.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2021

Connectivity and edge effects increase bee colonization in an experimentally fragmented landscape

Though landscape corridors increase dispersal of many animals and plants, it remains unknown whether these positive effects extend to the process of colonization and establishment of new populations in fragments. Working in experimentally fragmented landscapes, we tested how two aspects of habitat fragments altered by corridors – connectivity and edge-to-area ratio – determine patterns of colonization by a solitary, cavity-nesting bee Megachile rotundata. We found that though connectivity initially affected rates of nest-site occupation, edge-to-area ratio ultimately determined the final patterns of patch occupation and nest building, likely due to habitat selection by our focal species. Bee colonization was also higher in patches with higher abundances of their preferred food resources, flowers from the Fabaceae family. Our results show the importance of considering the effects of both connectivity and edge on population dynamics in habitat-based conservation.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2022

Root system architecture in cereals: progress, challenges and perspective

We report roots are essential multifunctional plant organs involved in water and nutrient uptake, metabolite storage, anchorage, mechanical support, and interaction with the soil environment. Understanding of this ‘hidden half’ provides potential for manipulation of root system architecture (RSA) traits to optimize resource use efficiency and grain yield in cereal crops. Unfortunately, root traits are highly neglected in breeding due to the challenges of phenotyping, but could have large rewards if the variability in RSA traits can be fully exploited. Until now, a plethora of genes have been characterized in detail for their potential role in improving RSA. The use of forward genetics approaches to find sequence variations in genes underpinning desirable RSA would be highly beneficial. Advances in computer vision applications have allowed image-based approaches for high-throughput phenotyping of RSA traits that can be used by any laboratory worldwide to make progress in understanding root function and dissection of the genetics. At the same time, the frontiers of root measurement include non-invasive methods like X-ray computer tomography and magnetic resonance imaging that facilitate new types of temporal studies. Root physiology and ecology are further supported by spatiotemporal root simulation modeling. The discovery of component traits providing improved resilience and yield advantage in target environments is a key necessity for mainstreaming root-based cereal breeding. The integrated use of pan-genome resources, now available in most cereals, coupled with new in-field phenotyping platforms has the potential for precise selection of superior genotypes with improved RSA.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2015

MO-DE-BRA-05: Developing Effective Medical Physics Knowledge Structures: Models and Methods

Purpose: Develop a method and supporting online resources to be used by medical physics educators for teaching medical imaging professionals and trainees so they develop highly-effective physics knowledge structures that can contribute to improved diagnostic image quality on a global basis. Methods: The different types of mental knowledge structures were analyzed and modeled with respect to both the learning and teaching process for their development and the functions or tasks that can be performed with the knowledge. While symbolic verbal and mathematical knowledge structures are very important in medical physics for many purposes, the tasks of applying physics in clinical imaging--especially to optimize image quality and diagnostic accuracy--requires a sensory conceptual knowledge structure, specifically, an interconnected network of visually based concepts. This type of knowledge supports tasks such as analysis, evaluation, problem solving, interacting, and creating solutions. Traditional educational methods including lectures, online modules, and many texts are serial procedures and limited with respect to developing interconnected conceptual networks. A method consisting of the synergistic combination of on-site medical physics teachers and the online resource, CONET (Concept network developer), has been developed and made available for the topic Radiographic Image Quality. This was selected as the inaugural topic, others to follow, because it can be used by medical physicists teaching the large population of medical imaging professionals, such as radiology residents, who can apply the knowledge. Results: Tutorials for medical physics educators on developing effective knowledge structures are being presented and published and CONET is available with open access for all to use. Conclusion: An adjunct to traditional medical physics educational methods with the added focus on sensory concept development provides opportunities for medical physics teachers to share their knowledge and experience at a higher cognitive level and produce medical professionals with the enhanced ability to apply physics to clinical procedures.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

Evolution of high cellulolytic activity in symbiotic Streptomyces through selection of expanded gene content and coordinated gene expression

In this study, the evolution of cellulose degradation was a defining event in the history of life. Without efficient decomposition and recycling, dead plant biomass would quickly accumulate and become inaccessible to terrestrial food webs and the global carbon cycle. On land, the primary drivers of plant biomass deconstruction are fungi and bacteria in the soil or associated with herbivorous eukaryotes. While the ecological importance of plant-decomposing microbes is well established, little is known about the distribution or evolution of cellulolytic activity in any bacterial genus. Here we show that in Streptomyces , a genus of Actinobacteria abundant in soil and symbiotic niches, the ability to rapidly degrade cellulose is largely restricted to two clades of host-associated strains and is not a conserved characteristic of the Streptomyces genus or host-associated strains. Our comparative genomics identify that while plant biomass degrading genes (CAZy) are widespread in Streptomyces , key enzyme families are enriched in highly cellulolytic strains. Transcriptomic analyses demonstrate that cellulolytic strains express a suite of multi-domain CAZy enzymes that are coregulated by the CebR transcriptional regulator. Using targeted gene deletions, we verify the importance of a highly expressed cellulase (GH6 family cellobiohydrolase) and the CebR transcriptional repressor to the cellulolytic phenotype. Evolutionary analyses identify complex genomic modifications that drive plant biomass deconstruction in Streptomyces , including acquisition and selective retention of CAZy genes and transcriptional regulators. Our results suggest that host-associated niches have selected some symbiotic Streptomyces for increased cellulose degrading activity and that symbiotic bacteria are a rich biochemical and enzymatic resource for biotechnology.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2023

Measurement-based quantum simulation of Abelian lattice gauge theories

Numerical simulation of lattice gauge theories is an indispensable tool in high energy physics, and their quantum simulation is expected to become a major application of quantum computers in the future. In this work, for an Abelian lattice gauge theory in d d spacetime dimensions, we define an entangled resource state (generalized cluster state) that reflects the spacetime structure of the gauge theory. We show that sequential single-qubit measurements with the bases adapted according to the former measurement outcomes induce a deterministic Hamiltonian quantum simulation of the gauge theory on the boundary. Our construction includes the (2+1) ( 2 + 1 ) -dimensional Abelian lattice gauge theory simulated on three-dimensional cluster state as an example, and generalizes to the simulation of Wegner’s lattice models M_{(d,n)} M ( d , n ) that involve higher-form Abelian gauge fields. We demonstrate that the generalized cluster state has a symmetry-protected topological order with respect to generalized global symmetries that are related to the symmetries of the simulated gauge theories on the boundary.Our procedure can be generalized to the simulation of Kitaev’s Majorana chain on a fermionic resource state. We also study the imaginary-time quantum simulation with two-qubit measurements and post-selections, and a classical-quantum correspondence, where the statistical partition function of the model M_{(d,n)} M ( d , n ) is written as the overlap between the product of two-qubit measurement bases and the wave function of the generalized cluster state.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2017

SPI Conformance Gel Applications in Geothermal Zonal Isolation

Zonal isolation in geothermal injection and producing wells is important while drilling the wells when highly fractured geothermal zones are encountered and there is a need to keep the fluids from interfering with the drilling operation. Department of Energy’s (DOE) Energy Efficiency and Renewable Energy (EERE) objectives are to advance technologies to make it more cost effective to develop, produce, and monitor geothermal reservoirs and produce geothermal energy. Thus, zonal isolation is critical to well cost, reservoir evaluation and operations. Traditional cementing off of the lost circulation or thief zones during drilling is often done to stem the drilling mud losses. This is an expensive and generally unsuccessful technique losing the potential of the remaining fracture system. Selective placement of strong SPI gels into only the offending fractures can maintain and even improve operational efficiency and resource life. The SPI gel system is a unique silicate based gel system that offers a promising solution to thief zones and conformance problems with water and CO2 floods and potentially geothermal operations. This gel system remains a low viscosity fluid until an initiator (either internal such as an additive or external such as CO2) triggers gelation. This is a clear improvement over current mechanical methods of using packers, plugs, liners and cementing technologies that often severely damage the highly fractured area that is isolated. In the SPI gels, the initiator sets up the fluid into a water-like (not a precipitate) gel and when the isolated zone needs to be reopened, the SPI gel may be removed with an alkaline solution without formation damage occurring. In addition, the SPI gel in commercial quantities is expected to be less expensive than competing mechanical systems and has unique deep placement possibilities. This project seeks to improve upon the SPI gel integrity by modifying the various components to impart temperature stability for use in geothermal.

15 GEOTHERMAL ENERGY↗

DOE OSTI2021

Geo Thermal Cloud: Cloud Fusion of Big Data and Multi-Physics Models using Machine Learning for Discovery, Exploration, and Development of Hidden Geothermal Resources

The project is motivated by the challenges, risks, and costs associated with geothermal exploration and production. Many processes and parameters impacting geothermal conditions are poorly understood. Diverse datasets are available to help characterize subsurface geothermal conditions (public and proprietary; satellite, airborne surveys, vegetation/water sampling, geological, geophysical, etc.). Yet, it is not clear how to properly leverage these datasets for geothermal exploration due to an incomplete understanding of how physical processes impacting subsurface geothermal conditions are represented in these observations. Recent advancements in machine learning (ML) provide great promise to resolve these issues. The tremendous challenges and risks of geothermal exploration and production bring the demand for novel ML methods and tools that can (1) analyze large field datasets, (2) assimilate model simulations (large inputs and outputs), (3) process sparse datasets, (4) perform transfer learning (between sites with different exploratory levels), (5) extract hidden geothermal signatures in the field and simulation data, (6) label geothermal resources and processes, (7) identify high-value data acquisition targets, and (8) guide geothermal exploration and production by selecting optimal exploration, production, and drilling strategies. Our goals and work under Phases 1 and 2 (as proposed) of this project address all these needs.

15 GEOTHERMAL ENERGY↗

DOE OSTI2024

Ocean surface radiation measurement best practices

Ocean surface radiation measurement best practices have been developed as a first step to support the interoperability of radiation measurements across multiple ocean platforms and between land and ocean networks. This document describes the consensus by a working group of radiation measurement experts from land, ocean, and aircraft communities. The scope was limited to broadband shortwave (solar) and longwave (terrestrial infrared) surface irradiance measurements for quantification of the surface radiation budget. Best practices for spectral measurements for biological purposes like photosynthetically active radiation and ocean color are only mentioned briefly to motivate future interactions between the physical surface flux and biological radiation measurement communities. Topics discussed in these best practices include instrument selection, handling of sensors and installation, data quality monitoring, data processing, and calibration. It is recognized that platform and resource limitations may prohibit incorporating all best practices into all measurements and that spatial coverage is also an important motivator for expanding current networks. Thus, one of the key recommendations is to perform interoperability experiments that can help quantify the uncertainty of different practices and lay the groundwork for a multi-tiered global network with a mix of high-accuracy reference stations and lower-cost platforms and practices that can fill in spatial gaps.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1977

Landsat digital data application to forest vegetation and land use classification in Minnesota

Landsat digital data were used to map eleven categories of land cover in north central Minnesota. The classification accuracy of these maps was found to be very low and they were not adequate for use by field level resource managers. A discussion of the advantages and disadvantages of various processing systems, different algorithms, and the problems in selecting training sets, is included.

Mead, R. A.↗

NASA NTRS1979

Comparison of alternate fuels for aircraft

Liquid hydrogen, liquid methane, and synthetic aviation kerosene were assessed as alternate fuels for aircraft in terms of cost, capital requirements, and energy resource utilization. Fuel transmission and airport storage and distribution facilities are considered. Environmental emissions and safety aspects of fuel selection are discussed and detailed descriptions of various fuel production and liquefaction processes are given. Technological deficiencies are identified.

Witcofski, R. D.↗

NASA NTRS1981

Calibration of a turbidity meter for making estimates of total suspended solids concentrations and beam attenuation coefficients in field experiments

Management of water resources such as a reservoir requires using analytical models which describe such parameters as the suspended sediment field. To select or develop an appropriate model requires making many measurements to describe the distribution of this parameter in the water column. One potential method for making those measurements expeditiously is to measure light transmission or turbidity and relate that parameter to total suspended solids concentrations. An instrument which may be used for this purpose was calibrated by generating curves of transmission measurements plotted against measured values of total suspended solids concentrations and beam attenuation coefficients. Results of these experiments indicate that field measurements made with this instrument using curves generated in this study should correlate with total suspended solids concentrations and beam attenuation coefficients in the water column within 20 percent.

Usry, J. W.↗

NASA NTRS1992

Lunar Prospector: a Preliminary Surface Remote Sensing Resource Assessment for the Moon

The potential existence of lunar volatiles is a scientific discovery that could distinctly change the direction of pathways of inner solar system human expansion. With a dedicated germanium gamma ray spectrometer launched in the early 1990's, surface water concentrations of 0.7 percent could be detected immediately upon full lunar polar orbit operations. The expense of lunar base construction and operation would be dramatically reduced over a scenario with no lunar volatile resources. Global surface mineral distribution could be mapped out and integrated into a GIS database for lunar base site selection. Extensive surface lunar mapping would also result in the utilization of archived Apollo images. A variety of remote sensing systems and their parameters have been proposed for use in the detection of these lunar ice masses. The detection or nondetection of subsurface and surface ice masses in lunar polar crater floors could dramatically direct the development pathways that the human race might follow in its radiation from the Earth to habitable locales in the inner terran solar system. Potential sources of lunar volatiles are described. The use of remote sensing to detect lunar volatiles is addressed.

Mardon, A. A.↗

NASA NTRS1992

Workshop on Geology of the Apollo 17 Landing Site

The topics covered include the following: petrology, lithology, lunar rocks, lunar soil, geochemistry, lunar geology, lunar resources, oxygen production, ilmenite, volcanism, highlands, lunar maria, massifs, impact melts, breccias, lunar crust, Taurus-Littrow, minerals, site selection, regolith, glasses, geomorphology, basalts, tectonics, planetary evolution, anorthosite, titanium oxides, chemical composition, and the Sudbury-Serenitatis analogy.

Ryder, G.↗

NASA NTRS2002

Development of a Two-Wheel Contingency Mode for the MAP Spacecraft

The Microwave Anisotropy Probe (MAP) is a follow-on mission to the Cosmic Background Explorer (COBE), and is currently collecting data from its orbit near the second Sun-Earth libration point. Due to limited mass, power, and financial resources, a traditional reliability concept including fully redundant components was not feasible for MAP. Instead, the MAP design employs selective hardware redundancy in tandem with contingency software modes and algorithms to improve the odds of mission success. One direction for such improvement has been the development of a two-wheel backup control strategy. This strategy would allow MAP to position itself for maneuvers and collect science data should one of its three reaction wheels fail. Along with operational considerations, the strategy includes three new control algorithms. These algorithms would use the remaining attitude control actuators-thrusters and two reaction wheels-in ways that achieve control goals while minimizing adverse impacts on the functionality of other subsystems and software.

Starin, Scott R.↗

NASA NTRS2005

A Total Factor Productivity Based Structure for Tactical Cluster Assessment: Empirical Investigation in the Airline Industry

In this paper we analyze and assess the efficiency of the United States (U.S.) airline industry through the total factor productivity (TFP) method. While airlines use various resources to produce a heterogeneous group of outputs, this article focuses on certain fundamental outputs as final products of selected airlines. The results from this analysis indicate that the national airlines (US. domestic carriers) have higher TFP as compared to the major airlines. While major airlines have drastically cut costs in the past few years, they also need to improve efficiency or risk going out of business. In this paper, we investigate the efficiency and productivity of a selection of U.S. airlines for the years 1996 through 2001. These years have been chosen as a good example of years in which the industry experienced normal growth and generally positively returns. Subsequent to 2001 the industry experienced two severe external shocks, namely, the September 11, 2001. terrorist attacks and the Iraq war. These anomalous shocks make the years after 2001 inconsistent with respect to the type of index developed in this article.

Vasigh, Bijan↗

NASA NTRS2004

Simulation of Aerosols and Chemistry with a Unified Global Model

This project is to continue the development of the global simulation capabilities of tropospheric and stratospheric chemistry and aerosols in a unified global model. This is a part of our overall investigation of aerosol-chemistry-climate interaction. In the past year, we have enabled the tropospheric chemistry simulations based on the GEOS-CHEM model, and added stratospheric chemical reactions into the GEOS-CHEM such that a globally unified troposphere-stratosphere chemistry and transport can be simulated consistently without any simplifications. The tropospheric chemical mechanism in the GEOS-CHEM includes 80 species and 150 reactions. 24 tracers are transported, including O3, NOx, total nitrogen (NOy), H2O2, CO, and several types of hydrocarbon. The chemical solver used in the GEOS-CHEM model is a highly accurate sparse-matrix vectorized Gear solver (SMVGEAR). The stratospheric chemical mechanism includes an additional approximately 100 reactions and photolysis processes. Because of the large number of total chemical reactions and photolysis processes and very different photochemical regimes involved in the unified simulation, the model demands significant computer resources that are currently not practical. Therefore, several improvements will be taken, such as massive parallelization, code optimization, or selecting a faster solver. We have also continued aerosol simulation (including sulfate, dust, black carbon, organic carbon, and sea-salt) in the global model to cover most of year 2002. These results have been made available to many groups worldwide and accessible from the website http://code916.gsfc.nasa.gov/People/Chin/aot.html.

Chin, Mian↗

NASA NTRS2013

Closeout Report for the Refractory Metal Accelerated Heat Pipe Life Test Activity

With the selection of a gas-cooled reactor, this heat pipe accelerated life test activity was closed out and its resources redirected. The scope of this project was to establish the long-term aging effects on Mo-44.5%Re sodium heat pipes when subjected to space reactor temperature and mass fluences. To date, investigators have demonstrated heat pipe life tests of alkali metal systems up to .50,000 hours. Unfortunately, resources have not been available to examine the effect of temperature, mass fluence, or impurity level on corrosion or to conduct post-test forensic examination of heat pipes. The key objective of this effort was to establish a cost/time effective method to systematically test alkali metal heat pipes with both practical and theoretical benefits. During execution of the project, a heat pipe design was established, a majority of the laboratory test equipment systems specified, and operating and test procedures developed. Procurements for the heat pipe units and all major test components were underway at the time the stop work order was issued. An extremely important outcome was the successful fabrication of an annular wick from Mo-5%Re screen (the single, most difficult component to manufacture) using a hot isostatic pressing technique. This Technical Publication (TP) includes specifics regarding the heat pipe calorimeter water-cooling system, vendor design for the radio frequency heating system, possible alternative calorimeter designs, and progress on the vanadium equilibration technique. The methods provided in this TP and preceding project documentation would serve as a good starting point to rapidly implement an accelerated life test. Relevant test data can become available within months, not years, and destructive examination of the first life test heat pipe might begin within 6 months of test initiation. Final conclusions could be drawn in less than a quarter of the mission duration for a long-lived, fission-powered, deep space probe.

Martin, J.↗