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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Chapter 20: Advances and Application of CRISPR-Cas Systems

A new gene-editing technique called clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) proteins have revolutionized genome engineering because of its high efficiency, relatively low cost, and ease of use compared with other techniques such as zinc-finger nucleases and transcription activator-like effector nucleases. CRISPR-Cas systems have transformed biological research, quickly becoming the preferred method for engineering specific genome sequences in industrially relevant microbes, important food crops, and human cells. This powerful new tool has the potential for limitless applications ranging from the treatment of human diseases to improving food security to the generation of renewable and sustainable bioproducts and biofuels. In this chapter, we will discuss advances and applications for these CRISPR-Cas systems in biological engineering.

bacterial↗
NASA NTRS1986

Calibrated Ancillary System (CAS) user's guide, volume 9

The Calibrated Ancillary System (CAS) provides real-time calibrated parameters from the orbiter downlink (ancillary data) to the Goddard Space Flight Center (GSFC). This user's guide contains the introduction to the equipment, operation, general procedures, and specific procedures of CAS. Volume 9 contains the menu-independent CAS commands. Examples of each command and command parameters are presented. A listing of acronyms and applicable documentation is also provided.

Source record↗
NASA NTRS1987

The trace element chemistry of CaS in enstatite chondrites and some implications regarding its origin

The trace element distribution in oldhamite (CaS) extracted from enstatite chondrites was determined by INAA. Prior to extraction, the petrologic setting of the grains was studied microscopically, and their minor element contents determined by microprobe analysis; samples that displayed a wide range of minor element contents were selected for detailed elementary analysis. Those samples of CaS suspected to be more primitive on the basis of their minor element and petrologic siting contain the entire inventory of the host meteorite's light REE (LREE) and Eu, plus 30-50 percent of the heavy-REE inventory. In less primitive samples, the LREE are less enriched although Eu remains highly concentrated. Several other elements, including lithophiles and chalcophiles, are most enriched in the most primitive CaS. It is suggested that oldhamite played a key role in the redistribution of these elements during the metamorphism and evolution of enstatite-rich material.

Larimer, John W.↗
NASA NTRS1994

COMPTEL observations of Ti-44 gamma-ray line emission from Cas A

The Compton Telescope (COMPTEL) telescope aboard the Compton Gamma-Ray Observatory (CGRO) is capable of imaging gamma-ray line sources in the MeV region with a sensitivity of the order 10(exp -5) photons/(sq cm s). During two observations periods in July 1992 and February 1993 the Galactic plane in the region of the young supernova remnant Cas A was observed, showing evidence for line emission at 1.16 MeV from the decay of Ti-44 at a significance level of approximately 4 sigma. This is the first time a supernova remnant has been detected in the gamma-ray line from Ti-44 decay. Adopting a distance of 2.8 kpc to the Cas A remnant, the measured line flux (7.0 +/- 1.7) x 10(exp -5) photons/(sq cm s), can be translated into a Ti-44 mass ejected during the Cas A supernova explosion, between (1.4 +/- 0.4) x 10(exp -4) solar mass and (3.2 +/- 0.8) x 10(exp -4) solar mass, depending on the precise value of the Ti-44 mean life time and on the precise date of the event. Implications of this result for supernova nucleosynthesis models are discussed.

Iyudin, A. F.↗
NASA NTRS1995

The abundances of major elements in Cas A and Tycho supernova remnants

The objective of this program was to map the abundances of major elements such as O, Si, S, and Fe in the supernova remnants, Tycho and Cas A. The approach was based upon using archival cosmic X-ray data from several space missions, notably, the Einstein Observatory, EXOSAT, ROSAT, BBSRT, and ASCA. Two of the missions, Einstein and ROSAT, had high resolution telescopes that provided excellent images, but no spectral information. Two missions with much poorer resolution telescopes, BBXRT and ASCA, gave good spectral information through pulse height of signals in their cooled solid state detector, but rather crude spatial information. Our goal was to extract spectral information from the combined analysis of the Einstein and ROSAT images of Cas A and Tycho and to verify or refine the spectral map by checking its agreement with the BBSRT or ASCA spectra results for larger regions. In particular, we note that the Einstein and ROSAT telescopes have different spectral responses. The Einstein bandwidth includes the 2-4 keV region which is absent from ROSAT. Hence, by forming linear combinations of the Einstein and ROSAT images, we are able to resolve the contributions of the 0.5-2 keV band from the 2-4 keV band. The former contains lines of O and Fe while the latter is dominated by Si and S. We correct for the expansion that has taken place in the remnants during the ten-year interval between the Einstein and ROSAT measurements, but we must assume that no significant spectral changes have occurred during that time. The analysis of the Tycho SNR was completed and the results have been published. A copy of the paper is included. The analysis of Cas A has proved to be more complicated. It is continuing with support from another program. Part of the problem may be due to difficulties in the aspect information which is needed to precisely register the ROSAT and Einstein images.

Gorenstein, P.↗
NASA NTRS1994

Data Communications Requirements for CAS Applications

This paper discusses the long-haul data communications requirements needed to support visualization of Computational Aeroscience (CAS) simulations. A scientific computing model is presented, from which current communications requirements are derived. This model is then expanded to describe the CAS Collaborative Visualization Environment, in which scientists from multiple NASA centers will collaborate on multidisciplinary, time-accurate simulations. An analysis of this model, along with data from the TFCC Workload Model, shows that CAS data communications requirements will increase to 10-100 megabytes/second by 1996.

McCabe, James D.↗
DOE OSTI2021

CRISPR-Cas Genome Editing in the Cellulolytic Bacterium Clostridium thermocellum (C. thermocellum)

Clostridium thermocellum is an anaerobic thermophile that can efficiently degrade lignocellulosic biomass and directly convert it into value-added products such as ethanol. The cellulolytic and ethanologenic capabilities of C. thermocellum make it an excellent candidate for consolidated bioprocessing (CBP) for industrial production, where biomass degradation and fermentation occur simultaneously. In this organism, strain development for effective CBP has traditionally been hindered by the lack of genetic tools. Here, we detail our efficient two-step CRISPR-Cas genome editing protocol for C. thermocellum, using both the native Type I-B CRISPR-Cas system and an exogenous Type-II CRISPR system from Geobacillus stearothermophilus. As recombination is limiting in C. thermocellum genome engineering, we highlight effective thermophilic recombinases necessary to improve genome editing in these systems. We additionally provide design rules for the repair template and synthetic guide RNA (gRNA) for each system. Using these newly developed CRISPR and recombineering tools, targeted C. thermocellum engineering will substantiate efforts toward CBP strain development in industrial applications.

anaerobe↗
NASA NTRSDate not supplied

Convergent Aeronautics Solutions (CAS) High Voltage Hybrid Electric Propulsion (HVHEP) Activity

Overview of Convergent Aeronautics Solutions (CAS) High Voltage Hybrid Electric Propulsion (HVHEP) activity. CAS HVHEP activity demonstrated feasibility of variable frequency, variable high voltage power system using doubly fed electric machines (DFM), and provided 90% reduction in power electronic weight for 35 megawatt system. DFM enables multi-phase (9) ac operation, with enhanced control and integrated protection methods for improved safety through minimization of fault energy.

CAS↗
DOE OSTI2026

Production of Heavy α -Elements and 44 Ti in Cas A: Comparison to Abundances from 1D Core-collapse Supernova Models and Evidence for Carbon–Oxygen Shell Mergers

The merger between the carbon (C) and oxygen (O) shells hours to days before the collapse of a massive star significantly changes its nucleosynthesis, which is reflected in the elemental ratios observed in supernova remnants (SNRs). We present a nucleosynthesis study of 44 Ti production in core-collapse supernovae (CCSNe), highlighting large silicon (Si), sulfur (S), calcium (Ca), and, most importantly, argon (Ar) to neon (Ne) ratios as diagnostics for carbon–oxygen (C–O) shell mergers. We compare yields from eight different sets of CCSNe models to observations of Cassiopeia A (Cas A), and show that C–O shell mergers are consistently the models that best match X-ray and infrared observations. These models produce high Ar/Ne ratios (≳0.1), due to 20 Ne depletion and production of 36 Ar and 38 Ar, while lower ratios are obtained from nonmerger cases. Based on the Ar/Ne diagnostic, we compare the range of expected 44 Ti produced by C–O shell mergers, which is up to ∼20%–30% of the overall 44 Ti, but expected to be located outside the reverse shock. Based on the sets of models considered, the photon flux expected from the 44 Ti synthesized in the C–O shell merger in Cas A is below the NuSTAR and COSI detection limits, compatible with current limits locating most of the 44 Ti interior to the reverse shock, but might be detectable from proposed missions like ASCENT. Finally, for the SNR of 1987A, a dominant C–O merger origin of the observed 44 Ti is unlikely based on the observed redshift in its 44 Ti line.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

Short-term temporal studies of the X ray emission from Cas A, Tycho and Sco X-1

No evidence for stable 2-10 keV periodic emission from Cas A or Tycho in the period range 1 msec to 10 sec is found. Upper limits to the pulsed fraction are presented as a function of the assumed light curve, with absolute 99% confidence upper limits of 0.089 and 0.195 for Cas A and Tycho, respectively. Previously reported transient 1-10 Hz oscillations from Sco X-1 are not observed.

Holt, S. S.↗
NASA NTRS1973

Investigation of brightness changes in WZ Cas in photographic and visible light

The results are presented concerning statistical processing of a series of visual and photographic magnitudes for WZ Cas. The light distribution functions were determined, which appeared to be asymmetrical. Theoretical approximating distributions were calculated. The star is predominantly bright in yellow rays and faint in blue ones. The correlative analysis of visual magnitudes shows that the period of WZ Cas is not less than 400 days.

Kheylo, E. S.↗
NASA NTRS1973

X-ray observations of the supernova remnants Cas A and Tycho

A rocket-borne multilayer multianode proportional counter observation of Cas A and Tycho supernovae remnants shows no evidence for periodic emissions in the period range from 1 millisecond to 13 seconds. Comparison of inferred incident photon spectra and electromagnetic flux intensity as a function of energy rules out simple synchrotron or isothermal models for both Cas A and Tycho. It is concluded that there must still be a contemporary source of energy in the source region to connect the radio and X-ray emission from these remnants.

Brisken, A. F.↗
NASA NTRS1980

Co-Alignment System (CAS) study. Report on task 1-3

The design of a suitable coalignment system (CAS) for the Solar Extreme Ultraviolet Telescope and Spectrometer (SEUTS) is presented. The CAS provides offset adjustment capabilities to SEUTS which will be mounted on a single large pointing system with other devices. The suitability of existing designs is determined and modifications are suggested.

Anderson, N. T.↗
NASA NTRS1985

Analysis of estimation algorithms for CDTI and CAS applications

Estimation algorithms for Cockpit Display of Traffic Information (CDTI) and Collision Avoidance System (CAS) applications were analyzed and/or developed. The algorithms are based on actual or projected operational and performance characteristics of an Enhanced TCAS II traffic sensor developed by Bendix and the Federal Aviation Administration. Three algorithm areas are examined and discussed. These are horizontal x and y, range and altitude estimation algorithms. Raw estimation errors are quantified using Monte Carlo simulations developed for each application; the raw errors are then used to infer impacts on the CDTI and CAS applications. Applications of smoothing algorithms to CDTI problems are also discussed briefly. Technical conclusions are summarized based on the analysis of simulation results.

Goka, T.↗
NASA NTRS1986

Calibrated Ancillary System (CAS) user's guide, volume 2

The Calibrated Ancillary System (CAS) provides real-time calibrated parameters from the orbiter downlink (ancillary data) to the Goddard Space Flight Center (GSFC). This user's guide contains the introduction to the equipment, operation, general procedures, and specific procedures of CAS. Volume 2 describes the central status and control (CSAC) procedures, supervisor procedures, and logging procedures.

Source record↗
NASA NTRS1986

Calibrated Ancillary System (CAS) user's guide, volume 3

The Calibrated Ancillary System (CAS) provides real-time calibrated parameters from the orbiter downlink (ancillary data) to the Goddard Space Flight Center (GSFC). This user's guide contains the introduction to the equipment, operation, general procedures, and specific procedures of the CAS. Volume 3 describes logging and delogging procedures, real-time procedures, and error messages.

Source record↗
NASA NTRS1986

Calibrated Ancillary System (CAS) user's guide, volume 4

The Calibrated Ancillary System (CAS) provides real-time calibrated parameters from the orbiter downlink (ancillary data) to the Goddard Space Flight Center (GSFC). This user's guide contains the introduction to the equipment, operation, general procedures, and specific procedures of the CAS. Volume 4 presents the GSFC user mission planning procedures covering the mission planning main menu, bulletin board system, ancillary products menu, utility menu procedures, and ancillary support files procedures.

Source record↗
NASA NTRS1986

Calibrated Ancillary System (CAS) user's guide, volume 5

The Calibrated Ancillary System (CAS) provides real-time parameters from the orbiter downlink (ancillary data) to the Goddard Space Flight Center (GSFC). This user's guide contains the introduction to the equipment, operation, general procedures, and specific procedures of CAS. Volume 5 describes the testing user mission planning procedures including the bulletin board system and ancillary products procedures. Instructions for viewing the SDT/TDT (shuttle data tape/telemetry descriptor tape) data base and the file management menu are also given.

Source record↗