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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Communications satellites in the national and global health care information infrastructure: their role, impact, and issues

Health care services delivered from a distance, known collectively as telemedicine, are being increasingly demonstrated on various transmission media. Telemedicine activities have included diagnosis by a doctor at a remote location, emergency and disaster medical assistance, medical education, and medical informatics. The ability of communications satellites to offer communication channels and bandwidth on demand, connectivity to mobile, remote and under served regions, and global access will afford them a critical role for telemedicine applications within the National and Global Information Infrastructure (NII/GII). The importance that communications satellites will have in telemedicine applications within the NII/GII the differences in requirements for NII vs. GII, the major issues such as interoperability, confidentiality, quality, availability, and costs, and preliminary conclusions for future usability based on the review of several recent trails at national and global levels are presented.

Zuzek, J. E.↗
NASA NTRS1995

Information Infrastructure Technology and Applications (IITA) Program: Annual K-12 Workshop

The purpose of the K-12 workshop is to stimulate a cross pollination of inter-center activity and introduce the regional centers to curing edge K-1 activities. The format of the workshop consists of project presentations, working groups, and working group reports, all contained in a three day period. The agenda is aggressive and demanding. The K-12 Education Project is a multi-center activity managed by the Information Infrastructure Technology and Applications (IITA)/K-12 Project Office at the NASA Ames Research Center (ARC). this workshop is conducted in support of executing the K-12 Education element of the IITA Project The IITA/K-12 Project funds activities that use the National Information Infrastructure (NII) (e.g., the Internet) to foster reform and restructuring in mathematics, science, computing, engineering, and technical education.

Hunter, Paul↗
NASA NTRS1995

The Federal Role in Bringing Education into the National Information Infrastructure

One of the most important issues facing Congress is to work with business, education, and the states to enable the nation's shools to better prepare students for a technological work force and to ensure that education has a place on the National Information Infrastructure (NII). This document provides background and important information for national leaders concerned about education, the information infrastructure, and related issues for the Federal government.

Cradler, John↗
NASA NTRS1998

A 2 THz Heterodyne Array Receiver for SOFIA

We proposed to perform a comprehensive design study of a 16-element heterodyne array receiver for SOFIA. The array was designed to utilize hot-electron bolometers in an efficient, low-cost waveguide mount to achieve low noise performance between approx. 1500 and 2400 GHz. Due to the prevailing physical conditions in the interstellar medium, this frequency range is one of the richest in the FIR portion of the spectrum. An array designed for this wavelength range will make excellent use of the telescope and the available atmospheric transmission, and will provide a new perspective on stellar, chemical, and galaxy evolution in the present as well as past epochs. A few of the most important molecular and atomic species which the instrument will sample are CII, OI, CO, OH, NII, and CH. The system used the most sensitive detectors available in an efficient optical system. The local oscillator was a compact CO2 pumped far-infrared laser currently under development for SOFIA. The backend spectrometer was an array acousto-optic spectrometer (aAOS). The spectrometer utilizes proven hardware and technologies to provide broadband performance (greater than or equal to 1 GHz per AOS channel) and high spectral resolution (1 MHz) with the maximum sensitivity and minimum complexity and cost. The proposed instrument would be the fastest and most sensitive heterodyne receiver ever to operate in the 1.5 - 2.4 THz band. One of the key technologies developed for the proposed instrument is the laser micromachining of waveguide structures. These structures provide both the optical link between the instrument and the telescope (via an array of efficient feedhorns) and the impedance transformation between the detectors and free space. With the assistance of funds provided from this grant, we were able to fabricate and test the world's first laser micromachined feedhorns. Figure 1 is a photograph of the 2 THz double feedhorn structure designed and constructed under the auspices of this grant. The quality of the waveguide structure is far better than that obtainable using any other fabrication technique. Figure 2 is the beam pattern obtained from it. The beam parameters are an excellent match to what is expected from theory. The success of this experiment demonstrates the viability of using laser micromachined components in the development of high performance, large format array receivers. Figure 3 is an illustration of the focal plane array concept we developed lot- SOFIA base upon this work. Un- fortunately, our instrument proposal was not selected as a first generation SOFIA instrument. However, we have continued our development efforts and will propose to build a 2nd generation instrument based on the same design concepts. Our work under NAG 2-1057 was very rewarding and we appreciate the opportunity provided by NASA to pursue it. The research led directly to publishing 2 papers (listed below) and the award of an NSF grant to our group to construct a laser micromachining system on the University of Arizona campus.

Walker, Christopher K.↗
NASA NTRS1994

Far-Infrared Line Observations of SGR A West

Using NASA's Kuiper Airborne Observatory (KAO), we have measured lines of [SIII] 19 and 33 micrometers, [FeIII] 23 micrometers, [OIII] 52 and 88 micrometers, [NIII] 57 micrometer, and [NII] 122 and 205 micrometers arising in the unusual HII region Sgr A West at the Galactic Center. The emission is consistent with photoionization of the low density (approximately 1000/cc) cavity gas, but the N+ emission could arise predominantly in the higher density "mini-spiral" ionized streamers unresolved in our beam.

Erickson, Edwin F.↗
NASA NTRS1998

A 2 THz Heterodyne Array Receiver for SOFIA: Summary of Research

We proposed to perform a comprehensive design study of a 16-element heterodyne array receiver for SOFIA. The array was designed to utilize hot-electron bolometers in an efficient, low-cost waveguide mount to achieve low noise performance between approximately 1500 and 2400 GHz. Due to the prevailing physical conditions in the interstellar medium, this frequency range is one of the richest in the Far-Infra Red (FIR) portion of the spectrum. An array designed for this wavelength range will make excellent use of the telescope and the available atmospheric transmission, and will provide a new perspective on stellar, chemical, and galactic evolution in the present as well as past epochs. A few of the most important molecular and atomic species which the instrument will sample are CII, OI, CO, OH, NII, and CH. The system used the most sensitive detectors available in an efficient optical system. The local oscillator was a compact CO2 pumped far-infrared laser currently under development for SOFIA. The backend spectrometer was an array acousto-optic spectrometer (aAOS). The spectrometer utilizes proven hardware and technologies to provide broadband performance (> 1 GHz per AOS channel) and high spectral resolution (1 MHz) with the maximum sensitivity and minimum complexity and cost. The proposed instrument would be the fastest and most sensitive heterodyne receiver ever to operate in the 1.5 - 2.4 THz band. One of the key technologies developed for the proposed instrument is the laser micromachining of waveguide structures. These structures provide both the optical link between the instrument and the telescope (via an array of efficient feedhorns) and the impedance transformation between the detectors and free space. With the assistance of funds provided from this grant, we were able to fabricate and test the world's first laser micromachined feedhorns. The quality of the waveguide structure is far better than that obtainable using any other fabrication technique. The beam parameters are an excellent match to what is expected from theory. The success of this experiment demonstrates the viability of using laser micromachined components in the development of high performance, large format array receivers. We have continued our development efforts and will propose to build a 2nd generation instrument based on the same design concepts.

Walker, Christopher K.↗
NASA NTRS1996

A 2 THz Heterodyne Array Receiver for SOFIA

We proposed to perform a comprehensive design study of a 16-element heterodyne array receiver for SOFIA. The array was designed to utilize hot-electron bolometers in an efficient, low-cost waveguide mount to achieve low noise performance between approx. 1500 and 2400 GHz. Due to the prevailing physical conditions in the interstellar medium, this frequency range is one of the richest in the FIR portion of the spectrum. An array designed for this wavelength range will make excellent use of the telescope and the available atmospheric transmission, and will provide a new perspective on stellar, chemical, and galaxy evolution in the present as well as past epochs. A few of the most important molecular and atomic species which the instrument will sample are CII, OI, CO, OH, NII, and CH. The system used the most sensitive detectors available in an efficient optical system. The local oscillator was a compact CO2 pumped far-infrared laser currently under development for SOFIA. The backend spectrometer was an array acousto-optic spectrometer (aAOS). The spectrometer utilizes proven hardware and technologies to provide broadband performance (greater than or equal to 1 GHz per AOS channel) and high spectral resolution (1 MHz) with the maximum sensitivity and minimum complexity and cost. The proposed instrument would be the fastest and most sensitive heterodyne receiver ever to operate in the 1.5 - 2.4 THz band. One of the key technologies developed for the proposed instrument is the laser micromachining of waveguide structures. These structures provide both the optical link between the instrument and the telescope (via an array of efficient feedhorns) and the impedance transformation between the detectors and free space. With the assistance of funds provided from this grant, we were able to fabricate and test the world's first laser micromachined feedhorns. The quality of the waveguide structure is far better than that obtainable using any other fabrication technique. The beam parameters are an excellent match to what is expected from theory. The success of this experiment demonstrates the viability of using laser micromachined components in the development of high performance, large format array receivers. Unfortunately, our instrument proposal was not selected as a first generation SOFIA instrument. However, we have continued our development efforts and will propose to build a 2nd generation instrument based on the same design concepts.

Walker, Christopher K.↗
NASA NTRS1991

Design and Analysis Tools for Concurrent Blackboard Systems

A blackboard system consists of a set of knowledge sources, a blackboard data structure, and a control strategy used to activate the knowledge sources. The blackboard model of problem solving is best described by Dr. H. Penny Nii of the Stanford University AI Laboratory: "A Blackboard System can be viewed as a collection of intelligent agents who are gathered around a blackboard, looking at pieces of information written on it, thinking about the current state of the solution, and writing their conclusions on the blackboard as they generate them. " The blackboard is a centralized global data structure, often partitioned in a hierarchical manner, used to represent the problem domain. The blackboard is also used to allow inter-knowledge source communication and acts as a shared memory visible to all of the knowledge sources. A knowledge source is a highly specialized, highly independent process that takes inputs from the blackboard data structure, performs a computation, and places the results of the computation in the blackboard data structure. This design allows for an opportunistic control strategy. The opportunistic problem-solving technique allows a knowledge source to contribute towards the solution of the current problem without knowing which of the other knowledge sources will use the information. The use of opportunistic problem-solving allows the data transfers on the blackboard to determine which processes are active at a given time. Designing and developing blackboard systems is a difficult process. The designer is trying to balance several conflicting goals and achieve a high degree of concurrent knowledge source execution while maintaining both knowledge and semantic consistency on the blackboard. Blackboard systems have not attained their apparent potential because there are no established tools or methods to guide in their construction or analyze their performance.

McManus, John W.↗
NASA NTRS1999

Broadband Satellite Technologies and Markets Assessed

The current usage of broadband (data rate greater than 64 kilobits per second (kbs)) for multimedia network computer applications is increasing, and the need for network communications technologies and systems to support this use is also growing. Satellite technology will likely be an important part of the National Information Infrastructure (NII) and the Global Information Infrastructure (GII) in the next decade. Several candidate communications technologies that may be used to carry a portion of the increased data traffic have been reviewed, and estimates of the future demand for satellite capacity have been made. A study was conducted by the NASA Lewis Research Center to assess the satellite addressable markets for broadband applications. This study effort included four specific milestones: (1) assess the changing nature of broadband applications and their usage, (2) assess broadband satellite and terrestrial technologies, (3) estimate the size of the global satellite addressable market from 2000 to 2010, and (4) identify how the impact of future technology developments could increase the utility of satellite-based transport to serve this market.

Wallett, Thomas M.↗
NASA NTRS2000

Submillimeter Astronomy Investigation of Line Specra (SAILS) - a balloon borne instrument

The Submillimeter Astronomy Investigation of Line Specra (SAILS) is a balloon-borne experiment under study for a 100 day ultra-long duration balloon mission. The experiment would survey the galactic plane with 1 arc minute angular resolution and 1 km/sec velocity resolution in the important submillimeter lines of CII, NII, and OI.

balloons optical resolving power radioactive trace↗
NASA NTRS2015

L'CO/LFIR Relations with CO Rotational Ladders of Galaxies Across the Herschel SPIRE Archive

We present a catalog of all CO (carbon monoxide) (J (total angular momentum quantum number) equals 1-0 through J equals 13-12), [CI], and [NII] lines available from extragalactic spectra from the Herschel SPIRE (Spectral and Photometric Imaging Receiver) Fourier Transform Spectrometer (FTS) archive combined with observations of the low-J CO lines from the literature and from the Arizona Radio Observatory. This work examines the relationships between L (sub FIR (Far Infra Red)), L prime (sub CO), and L (sub CO) / L (sub CO, 1-0). We also present a new method for estimating probability distribution functions (PDFs) from marginal signal-to-noise ratio Herschel FTS spectra, which takes into account the instrumental "ringing" and the resulting highly correlated nature of the spectra. The slopes of Log (L (sub FIR)) versus Log (L prime (sub CO)) are linear for all mid- to high-J CO lines. The mid- to high-J CO luminosity relative to CO J equals 1-0 increases with increasing L (sub FIR), indicating higher excitement of the molecular gas, though these ratios do not exceed approximately 100. The luminosities relative to CO J equals 1-0 remain relatively at from J equals 6-5 through J equals13-2, across many orders of magnitude of L (sub FIR). Qualitative comparisons to current theoretical models do not match these flat SLED (spectral line energy distributions) shapes, indicating the need for more comprehensive modeling of the excitation processes of warm molecular gas in nearby galaxies.

Submillimeter Data↗
NASA NTRS2020

Eta Carinae & the Homunculus: Far Infrared Sub-millimeter Spectral Lines detected with the Herschel Space Observatory

The evolved massive binary star η Carinae underwent eruptive mass loss events that formed the complex bi-polar “Homunculus” nebula harboring tens of solar masses of unusually nitrogen-rich gas and dust. Despite expectations for the presence of a significant molecular component to the gas, detections have been observationally challenged by limited access to the far-infrared and the intense thermal continuum. A spectral survey of the atomic and rotational molecular transitions was carried out with theHerschel Space Observatory, revealing a rich spectrum of broad emission lines originating in the ejecta. Velocity profiles of selected PACS lines correlate well with known substructures: Hi in the central core; NH and weak [Cii] within the Homunculus; and [Nii] emissions in fast-moving structures external to the Homunculus.We have identified transitions from [Oi], Hi, and 18 separate light C- and O-bearing molecules including CO, CH, CH+, and OH, and a wide set of N-bearing molecules,NH, NH+, N2H+, NH2, NH3, HCN, HNC, CN, and N2H+. Half of these are new detections unprecedented for any early-type massive star environment. A very low ratio[12C/13C]≤4 is estimated from five molecules and their isotopologues. We demonstrate that non-LTE effects due to the strong continuum are significant. Abundance patterns are consistent with line formation in regions of carbon and oxygen depletions with nitrogen enhancements, reflecting an evolved state of the erupting star with efficient transport of CNO-processed material to the outer layers. The results offer many opportunities for further observational and theoretical investigations of the molecular chemistry under extreme physical and chemical conditions around massive stars in their final stages of evolution.

T. R. Gull↗
NASA NTRS2022

The Dense, Warm Interstellar Medium (D-WIM): Unravelling a New Phase of the ISM A PRIMA FIR Probe Mission Project

We propose a study of the Dense Warm Interstellar Medium (D-WIM) via the two fine structure lines of ionized nitrogen (\NII). This new phase of the interstellar medium (ISM) has density 10 $\cmv \le n(e) \le$ 100 $\cmv$, and has effectively been identified throughout much of the Milky Way and in nearby galaxies. :The unexpected conditiosn in the D-WIM immediately raise important questions both about this phase of the ISM and its relationship to the ISM as a while. These include: what is the structure of the D-WIM -- e.g. filling factor, distribution, and morphology?; what is the origin of the D-WIM?; what supports its ionization and what is its evolution given huge overpressure relative to the $\ge$ 100 times more diffuse Warm Ionized Medium (WIM)?; what is its possible relationship to stars - is it the the remnants of very old HII regions that were produced by clusters of masive stars? The PRIMA survey requires a coverage of a large fraction of the plane, plus selected regions at high galactic latitudes. A sensitivity of 10$^{-9}$ $Wm^{-2}sr^{-1}$ would be highly desirable. A spectral resolution $R$ of 10$^4$ will isolate individual spectral features. $R$ = 10$^3$ would be acceptable to measure the total intensity. This PRIMA survey could be part of a broader survey of the ISM, and include a number of other important ISM tracers such as [CII] 158 \um, [OI] 63 \um\ and [OI] 146 \um, depending on wavelength coverage of the instrument. The sensitivity requirement for study of the D-WIM is likely more stringent than for the other lines, and may require special consideration for successful implementation as well as for determining the area that can be observed.

Lis, Dariusz↗
DOE OSTI2026

A New Record Census of Dwarf AGN and a Bimodal $M_{\rm BH}$-$M_{\star}$ Scaling Relation with DESI DR1

Using the first spectroscopic data release from the Dark Energy Spectroscopic Instrument (DESI DR1), we search for AGN signatures in 1,678,787 low-redshift ($0.001 \le z \le 0.45$) line-emitting galaxies. Based on the [NII]-BPT emission-line ratio diagnostic, we identify AGN in 314,245/1,211,573 (25.9%) high-mass ($\log (M_{\star}/M_{\odot}) > 9.5$) and 9648/467,214 (2.1%) dwarf ($\log (M_{\star}/M_{\odot}) \le 9.5$) galaxies. Among these AGN, 17,949 are broad-line candidates (BL-AGN) with broad H$α$ emission, enabling black hole (BH) mass estimates using single-epoch virial methods. We find that the AGN fraction in line-emitting galaxies increases monotonically with stellar mass, rising from $\sim$1.4% at the low-mass end to $\sim$93.3% at the high-mass end. Using the large BL-AGN sample, we extend the $M_{\rm BH} - M_{\star}$ scaling relation down to $\log (M_{\star}/M_{\odot}) \approx 7.8$ and $\log (M_{\rm BH}/M_{\odot}) \approx 4.4$. In the context of high-redshift overmassive BHs, our results suggest that galaxies and their central BHs may follow two distinct evolutionary pathways across cosmic time. With this paper, we release the EmFit value-added catalog, containing emission-line flux and width measurements for $\sim$7.4 million galaxies, the largest catalog with emission-line decomposition into narrow, broad, and outflow components to date. This work significantly expands upon the early DESI results and provides a statistical sample for probing the galaxy$-$BH connection in the low-mass galaxy regime.

Pucha, Ragadeepika [Utah U.; Arizona U., Astron. D↗
DOE OSTI2023

Changing temperature profiles and the risk of dengue outbreaks

As temperatures change worldwide, the pattern and competency of disease vectors will change, altering the global distribution of both the burden of infectious disease and the risk of the emergence of those diseases into new regions. To evaluate the risk of potential summer dengue outbreaks triggered by infected travelers under various climate scenarios, we develop an SEIR-type model, run numerical simulations, and conduct sensitivity analyses under a range of temperature profiles. Our model extends existing theoretical frameworks for studying dengue dynamics by introducing temperature dependence of two key parameters: the mosquito extrinsic incubation period and the lifespan of mosquitoes, which empirical data suggests are both highly temperature dependent. We find that changing temperature significantly alters dengue risk in an inverted U-shape, with temperatures in the range 27-31°C producing the highest risk. As temperatures increase beyond 31°C, the determinants of dengue risk begin to shift from mosquito biting rate and carrying capacity to the duration of the human infectious period, suggesting that changing temperatures not only alter dengue risk but also the potential efficacy of control measures. To illustrate the role of spatial and temporal temperature heterogeneity, we select five US cities where the primary dengue vector, the mosquito Aedes aegypti , has been observed, and which have had dengue cases in the past: Los Angeles, Houston, Miami, Brownsville, and Phoenix. Our analysis suggests that an increase of 3°C leads to an approximate doubling of the risk of dengue in Los Angeles and Houston, but a reduction of risk in Miami, Brownsville, and Phoenix due to extreme heat.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Molecular Epidemiology of HIV-1 in Ghana: Subtype Distribution, Drug Resistance and Coreceptor Usage

The greatest HIV-1 genetic diversity is found in West/Central Africa due to the pandemic’s origins in this region, but this diversity remains understudied. We characterized HIV-1 subtype diversity (from both sub-genomic and full-genome viral sequences), drug resistance and coreceptor usage in 103 predominantly (90%) antiretroviral-naive individuals living with HIV-1 in Ghana. Full-genome HIV-1 subtyping confirmed the circulating recombinant form CRF02_AG as the dominant (53.9%) subtype in the region, with the complex recombinant 06_cpx (4%) present as well. Unique recombinants, most of which were mosaics containing CRF02_AG and/or 06_cpx, made up 37% of sequences, while “pure” subtypes were rare (<6%). Pretreatment resistance to at least one drug class was observed in 17% of the cohort, with NNRTI resistance being the most common (12%) and INSTI resistance being relatively rare (2%). CXCR4-using HIV-1 sequences were identified in 23% of participants. Overall, our findings advance our understanding of HIV-1 molecular epidemiology in Ghana. Extensive HIV-1 genetic diversity in the region appears to be fueling the ongoing creation of novel recombinants, the majority CRF02_AG-containing, in the region. The relatively high prevalence of pretreatment NNRTI resistance but low prevalence of INSTI resistance supports the use of INSTI-based first-line regimens in Ghana.

59 BASIC BIOLOGICAL SCIENCES↗