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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Results of the plasma analyzer experiment on Pioneers 10 and 11

The plasma-analyzer experiments on Pioneers 10 and 11 have determined that the characteristics of the solar-wind interaction with the Jovian magnetosphere are basically similar to those observed for the solar-wind interaction of earth and differ mainly in terms of the scale size of the interaction. The Jovian magnetosheath flow field and the calculated normals to the Jovian magnetosphere indicate that the Jovian magnetosphere is extremely thick and blunt in shape. The size of the Jovian magnetosphere in the sunward (dayside) direction can change by as much as a factor of two in response to relatively minor changes in solar-wind dynamic pressure. The outer dayside Jovian magnetosphere is inflated with a high-beta thermal plasma.

Intriligator, D. S.↗
NASA NTRS2013

On the Statistical Analysis of X-ray Polarization Measurements

In many polarimetry applications, including observations in the X-ray band, the measurement of a polarization signal can be reduced to the detection and quantification of a deviation from uniformity of a distribution of measured angles of the form alpha plus beta cosine (exp 2)(phi - phi(sub 0) (0 (is) less than phi is less than pi). We explore the statistics of such polarization measurements using both Monte Carlo simulations as well as analytic calculations based on the appropriate probability distributions. We derive relations for the number of counts required to reach a given detection level (parameterized by beta the "number of sigma's" of the measurement) appropriate for measuring the modulation amplitude alpha by itself (single interesting parameter case) or jointly with the position angle phi (two interesting parameters case). We show that for the former case when the intrinsic amplitude is equal to the well known minimum detectable polarization (MDP) it is, on average, detected at the 3sigma level. For the latter case, when one requires a joint measurement at the same confidence level, then more counts are needed, by a factor of approximately equal to 2.2, than that required to achieve the MDP level. We find that the position angle uncertainty at 1sigma confidence is well described by the relation sigma(sub pi) equals 28.5(degrees) divided by beta.

Strohmayer, T. E.↗
DOE OSTI2022

CUPID: The Next-Generation Neutrinoless Double Beta Decay Experiment

We report CUPID is a next-generation tonne-scale bolometric neutrinoless double beta decay experiment that will probe the Majorana nature of neutrinos and discover lepton number violation in case of observation of this singular process. CUPID will be built on experience, expertise and lessons learned in CUORE and will be installed in the current CUORE infra-structure in the Gran Sasso underground laboratory. The CUPID detector technology, successfully tested in the CUPID-Mo experiment, is based on scintillating bolometers of Li 2 MoO 4 enriched in the isotope of interest 100 Mo. In order to achieve its ambitious science goals, the CUPID collaboration aims to reduce the backgrounds in the region of interest by a factor 100 with respect to CUORE. This performance will be achieved by introducing the high efficient α/β discrimination demonstrated by the CUPID-0 and CUPID-Mo experiments, and using a high transition energy double beta decay nucleus such as 100 Mo to minimize the impact of the gamma background. CUPID will consist of about 1500 hybrid heat-light detectors for a total isotope mass of 250 kg. The CUPID scientific reach is supported by a detailed and safe background model based on CUORE, CUPID-Mo and CUPID-0 results. The required performances have already been demonstrated and will be presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Hybrid analysis of radiative corrections to neutron decay with current algebra and effective field theory

We introduce a useful framework for high-precision studies of the neutron beta decay by merging the current algebra description and the fixed-order effective field theory calculation of the electroweak radiative corrections to the neutron axial form factor. We discuss the advantages of this hybrid method and show that it only requires a minimal amount of lattice QCD inputs to achieve a 10 –4 theory accuracy for the Standard Model prediction of the neutron lifetime and the axial-to-vector coupling ratio λ, both important to the search for physics beyond the Standard Model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Measurements of the polarization of several instabilities in the DIII-D tokamak

Recently, a method to infer the polarization of modes with frequencies much less than the ion cyclotron frequency was published [X.D. Du et al., Phys. Rev. Lett. 132 (2024) 215101]. The method uses measurements of electron temperature and density fluctuations δTₑ and δnₑ at the same spatial position to infer the local ratio of “acoustic polarization,” |δϕ ∥ |/(|δϕ ∥ |+|δψ|), where δϕ ∥ is the effective parallel potential and δψ is related to the parallel magnetic vector potential A ∥ . This paper summarizes key formulas, with emphasis on their range of validity, and elaborates on the workflow required to infer the acoustic polarization from experimental data. The drift-acoustic polarization of ellipticity-induced, toroidicity-induced, and reversed shear Alfvén eigenmodes is nearly zero, as expected for modes with predominately shear-Alfvénic polarization. The polarization of beta-induced Alfvén eigenmodes contains an acoustic component that increases with poloidal wave number. “Low frequency modes,” (instabilities that appear transiently when the minimum of the safety factor qₘᵢₙ passes through rational values) have large and highly variable acoustic polarization. In both experiment and simulation, fishbones have non-zero acoustic polarization that increases as the mode chirps down in frequency.

Alfven eigenmode↗
DOE OSTI2014

Recent Progress on Spherical Torus Research

The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio ($A = R_{0}/a$) reduced to A ~ 1.5, well below the normal tokamak operating range of A ≥ 2.5. As the aspect ratio is reduced, the ideal tokamak beta β (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as β ~ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation κ, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of attractive fusion energy power source. Since the start of the two megaampere class ST facilities in 2000, National Spherical Torus Experiment (NSTX) in the US and Mega Ampere Spherical Tokamak (MAST) in UK, active ST research has been conducted worldwide. More than sixteen ST research facilities operating during this period have achieved remarkable advances in all of fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

ROLE OF NUCLEONIC FERMI SURFACE DEPLETION IN NEUTRON STAR COOLING

The Fermi surface depletion of beta-stable nuclear matter is calculated to study its effects on several physical properties that determine the neutron star (NS) thermal evolution. The neutron and proton Z factors measuring the corresponding Fermi surface depletions are calculated within the Brueckner–Hartree–Fock approach, employing the AV18 two-body force supplemented by a microscopic three-body force. Neutrino emissivity, heat capacity, and in particular neutron {sup 3}PF{sub 2} superfluidity, turn out to be reduced, especially at high baryonic density, to such an extent that the cooling rates of young NSs are significantly slowed.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1982

The structure, energy balance, and winds of cool stars

Solar magnetic field phenomena which occur in cool stars are summarized. Factors which can produce magnetic fields in stars are listed. Information on cool star atmospheres, provided by high dispersion spectra, is discussed. These spectra show that in Beta Dra (G2 Ib) the transition lines are red shifted (an antiwind), perhaps indicating downflows in closed magnetic flux tubes, as seen in the solar flux tubes above sunspots. The G and K giants and supergiants are classed as active, quiet, or hybrid, depending on whether their atmospheres are dominated by closed magnetic flux tubes, open field geometries, or a predominantly open geometry with a few closed flux tubes embedded.

Linsky, J. L.↗
DOE OSTI2015

Removal of {sup 222}Rn daughters from metal surfaces

Removal of the long-lived {sup 222}Rn daughters ({sup 210}Pb, {sup 210}Bi and {sup 210}Po) from copper, stainless steel and germanium surfaces was investigated. As cleaning techniques etching and electro-polishing was applied to samples in a form of discs exposed earlier to a strong radon source. Reduction of the {sup 210}Pb activity was tested using a HPGe spectrometer, for {sup 210}Bi a beta spectrometer and for {sup 210}Po an alpha spectrometer was used. According to the conducted measurements electro-polishing was always more efficient compared to etching and in case of copper the activity reduction factors for {sup 210}Pb, {sup 210}Bi and {sup 210}Po were between 200 and 400. Etching does not remove {sup 210}Po from copper but works very efficiently from germanium. Results obtained for {sup 210}Pb and {sup 210}Bi for etched stainless steel were worse but still slightly better than those achieved for copper.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Epigenetic involvement of Alien/ESET complex in thyroid hormone-mediated repression of E2F1 gene expression and cell proliferation

Highlights: Black-Right-Pointing-Pointer Corepressor Alien interacts with histone methyltransferase ESET in vivo. Black-Right-Pointing-Pointer Alien/ESET complex is recruited to nTRE of T3-responsive gene by liganded TR{beta}1. Black-Right-Pointing-Pointer ESET-mediated H3K9 methylation is required for liganded TR{beta}1-repressed transcription. Black-Right-Pointing-Pointer ESET is involved in T3-repressed G1/S phase transition and proliferation. -- Abstract: The ligand-bound thyroid hormone receptor (TR) is known to repress via a negative TRE (nTRE) the expression of E2F1, a key transcription factor that controls the G1/S phase transition. Alien has been identified as a novel interacting factor of E2F1 and acts as a corepressor of E2F1. The detailed molecular mechanism by which Alien inhibits E2F1 gene expression remains unclear. Here, we report that the histone H3 lysine 9 (H3K9) methyltransferase (HMT) ESET is an integral component of the corepressor Alien complex and the Alien/ESET complex is recruited to both sites, the E2F1 and the nTRE site of the E2F1 gene while the recruitment to the negative thyroid hormone response element (nTRE) is induced by the ligand-bound TR{beta}1 within the E2F1 gene promoter. We show that, overexpression of ESET promotes, whereas knockdown of ESET releases, the inhibition of TR{beta}1-regulated gene transcription upon T3 stimulation; and H3K9 methylation is required for TR{beta}1-repressed transcription. Furthermore, depletion of ESET impairs thyroid hormone-repressed proliferation as well as the G1/S transition of the cell cycle. Taken together, our data indicate that ESET is involved in TR{beta}1-mediated transcription repression and provide a molecular basis of thyroid hormone-induced repression of proliferation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Beta Equilibrium under Neutron Star Merger Conditions

We calculate the nonzero-temperature correction to the beta equilibrium condition in nuclear matter under neutron star merger conditions, in the temperature range 1mEv < T ≲ 5 mEv. We improve on previous work using a consistent description of nuclear matter based on the IUF and SFHo relativistic mean field models. This includes using relativistic dispersion relations for the nucleons, which we show is essential in these models. We find that the nonzero-temperature correction can be of order 10 to 20 MeV, and plays an important role in the correct calculation of Urca rates, which can be wrong by factors of 10 or more if it is neglected.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Dicholine succinate, the neuronal insulin sensitizer, normalizes behavior, REM sleep, hippocampal pGSK3 beta and mRNAs of NMDA receptor subunits in mouse models of depression

Central insulin receptor-mediated signaling is attracting the growing attention of researchers because of rapidly accumulating evidence implicating it in the mechanisms of plasticity, stress response, and neuropsychiatric disorders including depression. Dicholine succinate (DS), a mitochondrial complex II substrate, was shown to enhance insulin-receptor mediated signaling in neurons and is regarded as a sensitizer of the neuronal insulin receptor. Compounds enhancing neuronal insulin receptor-mediated transmission exert an antidepressant-like effect in several pre-clinical paradigms of depression; similarly, such properties for DS were found with a stress-induced anhedonia model. Here, we additionally studied the effects of DS on several variables which were ameliorated by other insulin receptor sensitizers in mice. Pre-treatment with DS of chronically stressed C 57 BL6 mice rescued normal contextual fear conditioning, hippocampal gene expression of NMDA receptor subunit NR2A, the NR2A/NR2B ratio and increased REM sleep rebound after acute predation. In 18-month-old C57BL6 mice, a model of elderly depression, DS restored normal sucrose preference and activated the expression of neural plasticity factors in the hippocampus as shown by Illumina microarray. Finally, young naïve DS-treated C 57 BL6 mice had reduced depressive- and anxiety-like behaviors and, similarly to imipramine-treated mice, preserved hippocampal levels of the phosphorylated (inactive) form of GSK 3 beta that was lowered by forced swimming in pharmacologically naïve animals. Thus, DS can ameliorate behavioral and molecular outcomes under a variety of stress- and depression-related conditions. This further highlights neuronal insulin signaling as a new factor of pathogenesis and a potential pharmacotherapy of affective pathologies.

Behavioral Sciences↗
DOE OSTI2022

Parametric Decay of Alfvénic Wave Packets in Nonperiodic Low-beta Plasmas

The parametric decay of finite-size Alfvén waves in nonperiodic low-beta plasmas is investigated using one-dimensional (1D) hybrid simulations. Compared with the usual small periodic system, a wave packet in a large system under the absorption boundary condition shows different decay dynamics, including reduced energy transfer, localized density cavitation, and ion heating. The resulting Alfvén wave dynamics are influenced by several factors relating to this instability, including the growth rate, central wave frequency, and unstable bandwidth. A final steady state of the wave packet may be achieved when the instability does not have enough time to develop within the residual packet, and the packet size shows well-defined scaling dependencies on the growth rate, wave amplitude, and plasma beta. Under the proper conditions, enhanced secondary decay can also be excited in the form of a narrow, amplified wave packet. These results may help to interpret laboratory and spacecraft observations of Alfvén waves, and to refine our understanding of the associated energy transport and ion heating.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2012

Crystal Structures of the Outer Membrane Domain of Intimin and Invasin from Enterohemorrhagic E. coli and Enteropathogenic Y. pseudotuberculosis

Intimins and invasins are virulence factors produced by pathogenic Gram-negative bacteria. They contain C-terminal extracellular passenger domains that are involved in adhesion to host cells and N-terminal {beta} domains that are embedded in the outer membrane. Here, we identify the domain boundaries of an E. coli intimin {beta} domain and use this information to solve its structure and the {beta} domain structure of a Y. pseudotuberculosis invasin. Both {beta} domain structures crystallized as monomers and reveal that the previous range of residues assigned to the {beta} domain also includes a protease-resistant domain that is part of the passenger. Additionally, we identify 146 nonredundant representative members of the intimin/invasin family based on the boundaries of the highly conserved intimin and invasin {beta} domains. We then use this set of sequences along with our structural data to find and map the evolutionarily constrained residues within the {beta} domain.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Crystal structure of the mineral (Na,Ca,K){sub 2}(Ca,Na){sub 4}(Mg,Fe){sub 5}(Mg,Fe,Ti){sub 5}[Si{sub 12}Al{sub 4}O{sub 44}](F,O){sub 4}: a triclinic representative of the amphibole family

A mineral belonging to the amphibole family found at the Rothenberg paleovolcano (Eifel, Germany) was studied by single-crystal X-ray diffraction. The triclinic pseudomonoclinic unit-cell parameters are a = 5.3113(1) Angstrom-Sign , b = 18.0457(3) Angstrom-Sign ; c = 9.8684(2) Angstrom-Sign , {alpha} = 90.016(2) Degree-Sign , {beta} = 105.543(4) Degree-Sign , {gamma} = 89.985(2) Degree-Sign . The structure was solved by direct methods in sp. gr. P1 and refined to the R factor of 2.7% based on 6432 reflections with |F| > 3{sigma}(F) taking into account twinning. The mineral with the idealized formula (Na,Ca,K){sub 2}(Ca,Na){sub 4}(Mg,Fe){sub 5}(Mg,Fe,Ti){sub 5}[Si{sub 12}Al{sub 4}O{sub 44}](F,O){sub 4} has some symmetry and structural features that distinguish it from other minerals of this family.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1974

Copernicus spectra of beta Lyrae

The observations reported were made in August and September 1973. The principal data were scans in the low resolution mode at phases nearly coincident with the two light minima. Shorter scans were obtained at the two quadrature phases. The data show that the secondary component of beta Lyrae is a hotter object than the visible B8 star. The velocity amplitude of the lines suggests that the secondary is the more massive object, by a factor of several times.

Hack, M.↗
NASA NTRS1982

Absolute spectrophotometry of very large redshift quasars

Absolute spectrophotometric observations of 19 quasars with redshifts greater than 2.66 are reported. Observations were made with a multichannel spectrometer covering wavelengths from 3200 to 10000 A at low resolution and allowing accurate absolute fluxes to be determined for continuum and emission lines. Analysis of energy distribution measurements indicates the continuum spectral index redward of Lyman alpha to vary from -0.2 to -1.2. Average flux levels drop by 29% between Lyman alpha and Lyman beta, and by a further 10% below Lyman beta, and a drop or change of slope occurs near the Lyman limit, all of which are attributed to absorbing clouds at different redshifts. Estimations of a covering factor of 0.08 based on the Lyman alpha and He II 1640 lines are consistent with the production of these lines by recombination. The measured emission lines are observed to have intensities proportional to the continuum flux, with the exception of C IV, which shows the luminosity effect similar to that found by Baldwin (1977).

Oke, J. B.↗
NASA NTRS2001

Transient dissociation of polyribosomes and concurrent recruitment of calreticulin and calmodulin transcripts in gravistimulated maize pulvini

The dynamics of polyribosome abundance were studied in gravistimulated maize (Zea mays) stem pulvini. During the initial 15 min of gravistimulation, the amount of large polyribosomes transiently decreased. The transient decrease in polyribosome levels was accompanied by a transient decrease in polyribosome-associated mRNA. After 30 min of gravistimulation, the levels of polyribosomes and the amount of polyribosome-associated mRNA gradually increased over 24 h up to 3- to 4-fold of the initial value. Within 15 min of gravistimulation, total levels of transcripts coding for calreticulin and calmodulin were elevated 5-fold in maize pulvinus total RNA. Transcripts coding for calreticulin and calmodulin were recruited into polyribosomes within 15 min of gravistimulation. Over 4 h of gravistimulation, a gradual increase in the association of calreticulin and calmodulin transcripts with polyribosomes was seen predominantly in the lower one-half of the maize pulvinus; the association of transcripts for vacuolar invertase with polyribosomes did not change over this period. Our results suggest that within 15 min of gravistimulation, the translation of the majority of transcripts associated with polyribosomes decreased, resembling a general stress response. Recruitment of calreticulin and calmodulin transcripts into polyribosomes occurred predominantly in the lower pulvinus one-half during the first 4 h when the presentation time for gravistimulation in the maize pulvinus is not yet complete.

NASA Discipline Plant Biology↗