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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Rift Valley Fever Risk Map Model and Seroprevalence in Selected Wild Ungulates and Camels from Kenya

Since the first isolation of Rift Valley fever virus (RVFV) in the 1930s, there have been multiple epizootics and epidemics in animals and humans in sub-Saharan Africa. Prospective climate-based models have recently been developed that flag areas at risk of RVFV transmission in endemic regions based on key environmental indicators that precede Rift Valley fever (RVF) epizootics and epidemics. Although the timing and locations of human case data from the 2006-2007 RVF outbreak in Kenya have been compared to risk zones flagged by the model, seroprevalence of RVF antibodies in wildlife has not yet been analyzed in light of temporal and spatial predictions of RVF activity. Primarily wild ungulate serum samples from periods before, during, and after the 2006-2007 RVF epizootic were analyzed for the presence of RVFV IgM and/or IgG antibody. Results show an increase in RVF seropositivity from samples collected in 2007 (31.8%), compared to antibody prevalence observed from 2000-2006 (3.3%). After the epizootic, average RVF seropositivity diminished to 5% in samples collected from 2008-2009. Overlaying maps of modeled RVF risk assessments with sampling locations indicated positive RVF serology in several species of wild ungulate in or near areas flagged as being at risk for RVF. Our results establish the need to continue and expand sero-surveillance of wildlife species Kenya and elsewhere in the Horn of Africa to further calibrate and improve the RVF risk model, and better understand the dynamics of RVFV transmission.

Seroprevalence↗
NASA NTRS2015

Sulfur and Oxygen Isotopic Analysis of a Cosmic Symplectite from a Comet Wild 2 Stardust Terminal Particle

Introduction: Analyses of comet 81P/Wild 2 samples re-turned from the Stardust mission have uncovered surprising simi-larities to meteoritic material, including the identification of inner solar system grains [1-3]. The TEM characterization of terminal particle (TP) 4 from Stardust track #147 revealed an assemblage consisting of symplectically intergrown pentlandite and nanocrys-talline maghemite coexisting with high-Ca pyroxene [4]. Mineral-ogically similar cosmic symplectites (COS) containing pentlandite and magnetite in the primitive Acfer 094 meteorite are highly de-pleted in 16O (17O, 18O ~ 180 per mille) [5-7]. This isotopic signature is proposed to record alteration with primordial solar nebula water. Conversely, the normal O isotopic composition of the Stardust COS indicates alteration by a different aqueous reservoir, perhaps on the comet [8]. In this study, we analyzed the Wild 2 COS for S isotopes to further constrain its origin. Experimental: Thin sections of TP4 (12 m) were produced and their mineralogy was thoroughly characterized by TEM. Two of the sections were analyzed for O isotopes by isotopic imaging in the JSC NanoSIMS 50L. The sample in one of the slices was completely consumed. The remaining material in the adjacent slice was analyzed simultaneously for 16O, 32S, 33S, 34S, and 56Fe16O in electron multipliers using a Cs+ primary ion beam. Quasi-simulta-neous arrival (QSA) can have a significant effect on S isotopic ra-tios when using electron multipliers, resulting in undercounting of 32S [9]. Canyon Diablo troilite (CDT) was measured numerous times to deduce a correction factor for QSA and ensure measure-ment reproducibility. Isotopic ratios are reported relative to CDT. Results and Discussion: The Wild 2 COS is enriched in the heavy S isotopes relative to CDT (33S = 6.5 +/- 1.6 per mille; 34S = 5.1 +/- 0.7 per mille; 1). The degree of 33S enrichment indicates mass-inde-pendent fractionation (MIF) with 33S = 3.9 +/- 1.7 per mille. MIF of S has been observed in some chondrules (33S up to 0.11per mille) [10], but this effect has not been identified in sulfides from carbonaceous chondrites [11] or IDPs [12]. S isotopic analysis of Stardust impact craters also did not reveal MIF or anomalies, save for one potential 32S-rich presolar sulfide [13]. Measurement errors on these impact craters were much larger than those in this study, however. MIF of S has been proposed to result from heterogeneities in the solar neb-ula from nucleosynthetic components [14] or photochemical irra-diation of solar nebula gas [10]. Presolar SiC grains are observed to have 32S enrichments [15, 16] contrary to the S isotopic compo-sition of the cometary COS. The S isotopic composition more likely reflects irradiation of nebular gas.

Nguyen, A. N.↗
DOE OSTI2025

Taxogenomic Analysis of a Novel Yeast Species, Lachancea rosae Sp. Nov. F.A., Isolated From the Wild Rose Rosa californica

A novel Saccharomycotina yeast strain, yHQL494, was isolated from the rose hip of the wild rose Rosa californica from Castle Crags State Park, California, USA. Phylogenetic analyses of both whole genome data and the sequences from the D1/D2 region of the large ribosomal subunit (LSU) rRNA gene placed strain yHQL494 within the genus Lachancea and grouped it into a clade with Lachancea lanzarotensis and Lachancea meyersii. Taxogenomic analyses were conducted on publicly available genome sequences to gain a deeper insight into the carbon and nitrogen gene-trait associations across the Lachancea clade. The results of these analyses were found to be consistent across Lachancea species. Growth assays and microscopic analyses were conducted to determine the physiological characteristics of strain yHQL494, including the presence of hyphae or pseudohyphae, ascospore formation, fermentation abilities, and assimilation of carbon and nitrogen compounds. Based on the phenotypic and genomic characteristics of the strain yHQL494 T (=NRRL Y-64858 T , =CBS 18,574 T ), we propose a new species, Lachancea rosae sp. nov. f.a.

Bajgain, Yakendra [Villanova Univ., PA (United Sta↗
DOE OSTI2025

Community composition and abundance of wild bees at row crop-grassland interfaces in west central Nebraska

Abstract Perennial mixed forb and grassland habitats are crucial to conservation of pollinators and connectivity of habitats in intensely farmed landscapes. This study aims to understand the effects of land use on the pollinator community by describing bee abundance, species richness and community composition in perennial conservation grasslands and adjacent annual row crops located in west central Nebraska. In 2022 and 2023, we collected and identified bees via sticky traps at 4 locations (center and edge of adjacent grasslands and crop fields) at 6 replicated sites. We collected 1,768 specimens from sticky traps, resulting in 70 species within 28 genera. Halictidae accounted for 84% of the specimens collected. Bee abundance was influenced by the simple effects of land use (grassland vs. crops), edge adjacency, and the month and year of collection. Differences in bee abundance within a collection date were found mostly in early 2022 (May and June) and late 2023 (September), when the crop center location was generally the lowest, with some evidence for spillover of bees from the grassland into the crop edge during the early summer months. Bee species richness was affected only by month and was not significantly different by land use and edge adjacency. Bee community composition overlapped across the 4 locations, although there were significant dissimilarities between crop fields and grasslands. Surveys of the plant community revealed very low abundance of blooming stems and plant taxonomic richness at crop locations for all sampling periods, while grassland locations were comparatively high and varied over time. Plant communities showed no overlap between crop field and grassland locations. Overall, we found that conservation grasslands, while not seeded specifically with pollinator-attractive forbs, provide diverse resources to support wild bee communities in west central Nebraska; crop edges may also provide non-plant resources such as nesting sites and irrigation water. Going forward, better understanding pollinator species composition and resource utilization relative to land use characteristics and drought conditions will allow for better tailoring of conservation efforts and management strategies in Nebraska and across the larger region.

Entomology↗
DOE OSTI2025

Water Temperature, Prey Concentration and Salmonid Density Influence Daily Growth of Wild Juvenile Salmonids in Tributaries of the Upper Salmon River, Idaho ( USA )

ABSTRACT Theory, experiments and field studies indicate that the somatic growth rate of freshwater consumers is shaped by the individual, additive and multiplicative effects of multiple factors, including consumer size and condition, temperature, prey resources and biotic interactions. While our understanding of how these factors affect wild populations of freshwater consumers is improving, the topic remains poorly studied, especially with respect to mobile species. Here, we report on an 8‐year, seven‐stream ( n = 49 stream‐year combinations) observational study examining the individual and interactive effects of invertebrate prey concentration (F, mg/m 3 ), mean daily water temperature (T, °C) and juvenile Chinook salmon ( Oncorhynchus tshawytscha ) density (D, fish/100 m 2 ) on summer daily growth rates (%/d) of mobile, anadromous, juvenile Chinook salmon (age‐0+, n = 382) and sub‐yearling (age‐0+, n = 61) and yearling (age‐1+) steelhead trout ( O. mykiss , n = 70) rearing in cold (mean daily summer: 12.1°C, range: 4.2°C–16.7°C) mountain tributaries of the Salmon River basin in central Idaho (USA). AIC c model selection indicated that daily juvenile salmonid growth positively correlated with water temperature, prey biomass concentration, local juvenile Chinook density and the interaction between water temperature and food but with species and age‐specific differences. Water temperature was a covariate in all top‐ranked models, with daily growth (%/day) rate increasing (0.05%–0.23%/d) linearly with mean daily summer water temperature. In addition to a direct positive relationship with daily growth rate, there was evidence that prey concentration positively interacted with water temperature to accelerate daily growth (F × T). The positive relationship between juvenile salmonid daily growth rate and juvenile Chinook density is difficult to explain and could result from confounding factors. The individual success observed in these streams may contribute to population‐level benefits for the focal consumers, as prey‐rich, warm summers may result in larger individuals with higher energy reserves at the end of the summer/autumn growing season, contributing to improved overwinter survival. Our results, taken in combination with evidence from models, experiments and observational studies, have climate change implications. Current and predicted increases in water temperature will necessitate higher rates of prey consumption by aquatic ectothermic consumers to offset accelerated metabolic demands. Thus, to improve the resilience of mobile freshwater consumers in a warming climate, we suggest that natural resource managers not only consider physical and chemical habitat conditions but also biotic conditions, including the spatiotemporal quantity and quality of prey resources.

Kiffney, Peter. M. [Fish Ecology, Northwest Fisher↗
DOE OSTI2025

Hidden diversity: Transcriptomic and photosynthetic variation among common ‘wild type’ Chlamydomonas strains

The unicellular green alga Chlamydomonas reinhardtii is a widely studied reference organism, particularly in photosynthesis research. It employs photoprotective mechanisms, such as state transitions (ST) and non-photochemical quenching (NPQ), to cope with rapid light changes. Most widely used strains share a recent common ancestor yet differ by up to ~50 000 nuclear variants—genetic diversity that is often overlooked. Even among ‘wild type’ strains, we document significant phenotypic differences, such as pigment accumulation, and nutrient utilization. To elucidate the basis for this variation, we compared transcriptomes and physiological traits of seven commonly used laboratory strains, including the reference strain and the CLiP mutant library parental strain. Despite identical growth conditions, ~40% of genes were differentially expressed between strains. Most of these differences are attributable to changes that have accrued during laboratory propagation, and adverse conditions may have driven transcriptomic drift. At the physiological level, we catalog the range of strain-dependent responses related to photosynthesis and high light (HL) acclimation. Specifically, (i) all strains develop NPQ upon HL exposure, but to various degrees, (ii) they show a substantial variation in ST capacity, and (iii) they regulate the composition of the photosynthetic apparatus differently. We find that NPQ levels do not correlate with LHCSR3 expression, suggesting an additional layer of NPQ regulation. STs are constantly activated and independent of growth light intensities. Overall, our findings highlight significant strain-to-strain differences in virtually all photosynthetic parameters, emphasizing the importance of careful strain selection in future research endeavors.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2026

Genomic-based biosurveillance for avian influenza: whole genome sequencing from wild mallards sampled during autumn migration in 2022–2023 reveals a high co-infection rate on migration stopover site in Georgia

The Caucasus region, including Georgia, is an important intersection for migratory waterbirds, offering potential for avian influenza virus (AIV) transmission between populations from different geographic areas. In 2022 and 2023, wild ducks were sampled during autumn migration events in Georgia to study the genetic relationships and molecular characteristics of influenza strains. Sequencing and phylogenetic analysis were used to compare the sampled strains to reference sequences from Africa, Asia, and Europe, allowing assessment of genetic relationships and virus transmission between migratory birds. Protein language modeling identified potential co-infections. Of 225 duck samples, 128 tested positive for the influenza M gene. 55 influenza-positive samples underwent whole-genome sequencing, revealing significant diversity. Analysis of the hemagglutinin (HA) segment showed notable differences among subtypes. Most samples were H6N1 and H6N6, but co-infections with combinations like H6H3, N8N1, N6H9, N2N6, and H9H6/N1N2 were also identified. These findings demonstrate the high variability of influenza viruses in migratory waterbirds in Georgia, including a notable rate of co-infections. Some samples exhibited uncommon genetic characteristics compared to other strains from the same year, suggesting Georgia’s role as a mixing vessel for influenza viruses. This facilitates reassortment during co-infections and contributes to the genetic diversity observed across flyways.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1989

Editing wild points in isolation - Fast agreement for reliable systems (Preliminary version)

Consideration is given to the intuitively appealing notion of discarding sensor values which are strongly suspected of being erroneous in a modified approximate agreement protocol. Approximate agreement with editing imposes a time bound upon the convergence of the protocol - no such bound was possible for the original approximate agreement protocol. This new approach is potentially useful in the construction of asynchronous fault tolerant systems. The main result is that a wild-point replacement technique called t-worst editing can be shown to guarantee convergence of the approximate agreement protocol to a valid agreement value. Results are presented for a four-processor synchronous system in which a single processor may be faulty.

Kearns, Phil↗
NASA NTRS2004

Stardust Imaging of Comet Wild 2: First Look

On 2 January 2004 during its historic flight to return cometary dust samples to earth, the STARDUST spacecraft flew within the coma of comet Wild 2 and also took 72 images where the surface was resolved during the flyby. A combination of long and short exposures was used to observe the jets and the surface. Comet Surface: The images revealed a planetary body, one not having a significant atmosphere, quite different from any other such body seen from other spacecraft. Surface depressions, potentially a combination of craters and vents, were not bowl-shaped but typically had steep walls and flattened floors. One depression considered to be a vent, the source of a jet, had a depth to diameter ratio of approx.0.4, with near vertical walls. Jets: At least 10 to possibly 20 jets were active during the flyby. Some were traced back to the surface where they seem to originate from the near vertical walls of depressions (vents) that were facing the sun, having the highest solar insolation.

Newburn, R.↗
NASA NTRS2004

Streaming Clumps Ejection Model and the Heterogeneous Inner Coma of Comet Wild 2

The conventional concept of cometary comae is that they are dominated by fine particulates released individually by sublimation of surface volatiles and subsequent entrainment in the near-surface gas. It has long been recognized that such particulates could be relatively large, with early estimates that objects perhaps up to one meter in size may be levitated from the surface of the typical cometary nucleus. However, the general uniformity and small average particulate size of observed comae and the relatively smooth, monotonic increases and decreases in particle density during the Giotto flythrough of comet Halley s coma in 1986 reinforced the view that the bulk of the particles are released at the surface, are fine-sized and inert. Jets have been interpreted as geometrically constrained release of these particulates. With major heterogeneities observed during the recent flythrough of the inner coma of comet Wild 2, these views deserve reconsideration.

Clark, B. C.↗
NASA NTRS1989

Rootcap structure in wild type and in a starchless mutant of Arabidopsis

Rootcaps of the wild type (WT) and of a starchless, gravitropic mutant (TC7) of Arabidopsis thaliana L. were examined by electron microscopy to identify cellular polarities with respect to gravity. In columella cells, nuclei are located proximally, and the nuclear envelope is continuous with endoplasmic reticulum (ER) that is in turn connected to nearby plasmodesmata. Impregnation of ER with osmium ferricyanide revealed numerous contacts between columella plastids and ER in both genotypes. ER is present mostly in the outer regions of the columella protoplast except in older columella cells that are developing into peripheral cells. In vertical roots, only columella cells that are intermediate in development (story 2 cells) have a higher surface density (S) of ER in the distal compared to proximal regions of the cell. The distal but not the proximal S of the ER is constant throughout columella development. Plastids are less sedimented in TC7 columella cells compared to those of the WT. It is hypothesized that plastid contact with the ER plays a role in gravity perception in both genotypes.

NASA Discipline Plant Biology↗
NASA NTRS1998

Gravitropism and development of wild-type and starch-deficient mutants of Arabidopsis during spaceflight

The "starch-statolith" hypothesis has been used by plant physiologists to explain the gravity perception mechanism in higher plants. In order to help resolve some of the controversy associated with ground-based research that has supported this theory, we performed a spaceflight experiment during the January 1997 mission of the Space Shuttle STS-81. Seedlings of wild-type (WT) Arabidopsis, two reduced-starch strains, and a starchless mutant were grown in microgravity and then given a gravity stimulus on a centrifuge. In terms of development in space, germination was greater than 90% for seeds in microgravity, and flight seedlings were smaller (60% in total length) compared to control plants grown on the ground and to control plants on a rotating clinostat. Seedlings grown in space had two structural features that distinguished them from the controls: a greater density of root hairs and an anomalous hypocotyl hook structure. However, the slower growth and morphological changes observed in the flight seedlings may be due to the effects of ethylene present in the spacecraft. Nevertheless, during the flight hypocotyls of WT seedlings responded to a unilateral 60 min stimulus provided by a 1-g centrifuge while those of the starch-deficient strains did not. Thus the strain with the greatest amount of starch responded to the stimulus given in flight and therefore, these data support the starch-statolith model for gravity sensing.

short duration↗
NASA NTRS2001

Modest increased sensitivity to radiation oncogenesis in ATM heterozygous versus wild-type mammalian cells

Subpopulations that are genetically predisposed to radiation-induced cancer could have significant public health consequences. Individuals homozygous for null mutations at the ataxia telangiectasia gene are indeed highly radiosensitive, but their numbers are very small. Ataxia Telangiectasia heterozygotes (1-2% of the population) have been associated with somewhat increased radiosensitivity for some end points, but none directly related to carcinogenesis. Here, intralitter comparisons between wild-type mouse embryo fibroblasts and mouse embryo fibroblasts carrying ataxia telangiectasia mutated (ATM) null mutation indicate that the heterozygous cells are more sensitive to radiation oncogenesis than their normal, litter-matched, counterparts. From these data we suggest that Ataxia Telangiectasia heterozygotes could indeed represent a societally-significant radiosensitive human subpopulation.

Non-NASA Center↗
NASA NTRS2005

Topography of the 81/P Wild 2 Nucleus Derived from Stardust Stereoimages

On 2 January, 2004, the Stardust spacecraft flew by the nucleus of comet 81P/Wild 2 with a closest approach distance of approx. 240 km. During the encounter, the Stardust Optical Navigation Camera (ONC) obtained 72 images of the nucleus with exposure times alternating between 10 ms (near-optimal for most of the nucleus surface) and 100 ms (used for navigation, and revealing additional details in the coma and dark portions of the surface. Phase angles varied from 72 deg. to near zero to 103 deg. during the encounter, allowing the entire sunlit portion of the surface to be imaged. As many as 20 of the images near closest approach are of sufficiently high resolution to be used in mapping the nucleus surface; of these, two pairs of short-exposure images were used to create the nucleus shape model and derived products reported here. The best image resolution obtained was approx. 14 m/pixel, resulting in approx. 300 pixels across the nucleus. The Stardust Wild 2 dataset is therefore markedly superior from a stereomapping perspective to the Deep Space 1 MICAS images of comet Borrelly. The key subset of the latter (3 images) covered only about a quarter of the surface at phase angles approx. 50 - 60 and less than 50 x 160 pixels across the nucleus, yet it sufficed for groups at the USGS and DLR to produce digital elevation models (DEMs) and study the morphology and photometry of the nucleus in detail.

Kirk, R. L.↗