Evidence for the genetic basis and inheritance of ocean and river-maturing ecotypes of Pacific lamprey (Entosphenus tridentatus) in the Klamath River, California

Surveys of genetic variation have improved our understanding of the relationship between fitness-related phenotypes and their underlying genetic basis. However, how this information can be used to inform conservation has been unclear in many cases. The objective of this study was to combine next-generation genetic sequencing with traditional ecological knowledge to evaluate imperiled anadromous Pacific lamprey (Entosphenus tridentatus) and apply the findings to conservation in the context of resolving Native American traditional food security issues. In the Klamath River of California, a previously identified Pacific lamprey ocean-maturing ecotype was distinguished by a relatively advanced maturity of female fish (e.g., large egg mass) upon freshwater entry compared to a relatively immature river-maturing ecotype. However, relative run-timing and the genetic basis of this ecotypic differentiation was not known. I collected 219 returning adult Pacific lamprey at-entry to the Klamath River over a 12-month period, genotyped them at 308 neutral and adaptive single nucleotide polymorphism (SNP) loci, and recorded morphological traits, including egg mass as an indicator of female sexual maturity. The onset for freshwater migration for the ocean-maturing ecotype was predominantly the winter whereas the river-maturing ecotype entered during all seasons and a genetic basis of the ecotype diversity was revealed. Genotype-phenotype association mapping identified sixteen SNPs significantly associated to egg mass forming two groups of linked loci and ten other SNPs significantly associated to total length. A duplicate dominant epistasis inheritance model best supported the ocean- and river-maturing ecotypes, accurately predicting ecotype in 83% of the samples. The adaptive genetic variation revealed is useful for conservation planning as it indicates that the river-maturing ecotype carries standing genetic variation capable of producing both ecotypes (e.g., both heterozygous and homozygous individuals), while the ocean-maturing ecotype is almost exclusively homozygous. An ecological application of these molecular findings is that when assessing stream restoration projects, the river-maturing ecotypes could perhaps be prioritized as they contain the genetic diversity capable of producing both ecotypes (i.e., heterozygosity), whereas the ocean-maturing ecotypes do not. I recommend distinguishing the river-maturing and ocean-maturing ecotypes of Pacific lamprey by adopting the names ke’ween (lamprey “eel”) and tewol (ocean), respectively, using terms from the Yurok language, in recognition of the importance of Pacific lamprey to Pacific Northwest fishing tribes

Wind-Tunnel Balance Characterization for Hypersonic Research Applications

Wind-tunnel research was recently conducted at the NASA Langley Research Center s 31-Inch Mach 10 Hypersonic Facility in support of the Mars Science Laboratory s aerodynamic program. Researchers were interested in understanding the interaction between the freestream flow and the reaction control system onboard the entry vehicle. A five-component balance, designed for hypersonic testing with pressurized flow-through capability, was used. In addition to the aerodynamic forces, the balance was exposed to both thermal gradients and varying internal cavity pressures. Historically, the effect of these environmental conditions on the response of the balance have not been fully characterized due to the limitations in the calibration facilities. Through statistical design of experiments, thermal and pressure effects were strategically and efficiently integrated into the calibration of the balance. As a result of this new approach, researchers were able to use the balance continuously throughout the wide range of temperatures and pressures and obtain real-time results. Although this work focused on a specific application, the methodology shown can be applied more generally to any force measurement system calibration

New Horizons: Long-Range Kuiper Belt Targets Observed by the Hubble Space Telescope

We report on Hubble Space Telescope (HST) observations of three Kuiper Belt Objects (KBOs), discovered in our dedicated ground-based search campaign, that are candidates for long-range observations from the New Horizons spacecraft: 2011 JY31, 2011 HZ102, and 2013 LU35. Astrometry with HST enables both current and future critical accuracy improvements for orbit precision, required for possible New Horizons observations, beyond what can be obtained from the ground. Photometric colors of all three objects are red, typical of the Cold Classical dynamical population within which they reside; they are also the faintest KBOs to have had their colors measured. None are observed to be binary with HST above separations of ~0.02 arcsec (~700 km at 44 AU) and {\Delta}m less than or equal to 0.5.Comment: Pages: 11, Figures: 2, Tables: 3, Icarus, available online May 2014 (http://dx.doi.org/10.1016/j.icarus.2014.04.014

Thermal and Pressure Characterization of a Wind Tunnel Force Balance Using the Single Vector System

Wind tunnel research at NASA Langley Research Center s 31-inch Mach 10 hypersonic facility utilized a 5-component force balance, which provided a pressurized flow-thru capability to the test article. The goal of the research was to determine the interaction effects between the free-stream flow and the exit flow from the reaction control system on the Mars Science Laboratory aeroshell during planetary entry. In the wind tunnel, the balance was exposed to aerodynamic forces and moments, steady-state and transient thermal gradients, and various internal balance cavity pressures. Historically, these effects on force measurement accuracy have not been fully characterized due to limitations in the calibration apparatus. A statistically designed experiment was developed to adequately characterize the behavior of the balance over the expected wind tunnel operating ranges (forces/moments, temperatures, and pressures). The experimental design was based on a Taylor-series expansion in the seven factors for the mathematical models. Model inversion was required to calculate the aerodynamic forces and moments as a function of the strain-gage readings. Details regarding transducer on-board compensation techniques, experimental design development, mathematical modeling, and wind tunnel data reduction are included in this paper

The Relationship between Tropical Cyclone Activity, Nutrient Loading, and Algal Blooms over the Great Barrier Reef

The Great Barrier Reef, the world’s largest coral reef ecosystem, is subject to many environmental stressors. This study utilizes remotely sensed Moderate Resolution Imaging Spectroradiometer (MODIS) chlorophyll a concentration data to explore statistically significant relationships between local-scale tropical cyclone disturbance and relative water quality between 2004–2014. The study reveals that tropical cyclone activity reduces water quality at 8- and 16-day time lags. Relationships suggest that at early stages (during and just after cyclone activity) algal response is induced primarily through wind-driven sediment re-suspension. However, wind speed in isolation only increases minimum levels of chlorophyll a, rather than mean or extreme upper values. At greater time lags (16-day), it is suggested that nutrient runoff from rainfall (and perhaps storm surge) increase phytoplankton activity, leading to detrimental ecological effects. The analyses systematically demonstrate the dominance of tropical cyclone size on mean and extreme values of chlorophyll a during and after tropical cyclone activity (at 0-, 8-, and 16-day time lags). Both the total area affected and the area from which nutrients can be extracted have more impact on chlorophyll a concentrations than either the duration or intensity of the cyclone. Findings indicate that efforts to reduce nutrient and sediment leaching into the reef lagoon from the Queensland coastal lands need to be continued and improved. This will be particularly important in the context of climate change, since tropical cyclone frequency, dynamics and characteristics are likely to change

The mass and density of the dwarf planet (225088) 2007 OR10

The satellite of (225088) 2007 OR10 was discovered on archival Hubble Space Telescope images and along with new observations with the WFC3 camera in late 2017 we have been able to determine the orbit. The orbit's notable eccentricity, e$\approx$0.3, may be a consequence of an intrinsically eccentric orbit and slow tidal evolution, but may also be caused by the Kozai mechanism. Dynamical considerations also suggest that the moon is small, D$_{eff}$ $<$ 100 km. Based on the newly determined system mass of 1.75x10$^{21}$ kg, 2007 OR10 is the fifth most massive dwarf planet after Eris, Pluto, Haumea and Makemake. The newly determined orbit has also been considered as an additional option in our radiometric analysis, provided that the moon orbits in the equatorial plane of the primary. Assuming a spherical shape for the primary this approach provides a size of 1230$\pm$50 km, with a slight dependence on the satellite orbit orientation and primary rotation rate chosen, and a bulk density of 1.75$\pm$0.07 g cm$^{-3}$ for the primary. A previous size estimate that assumed an equator-on configuration (1535$^{+75}_{-225}$ km) would provide a density of 0.92$^{+0.46}_{-0.14}$ g cm$^{-3}$, unexpectedly low for a 1000 km-sized dwarf planet.Comment: Accepted for publication in Icaru

Multiple Incommensurate Magnetic States in the Kagome Antiferromagnet Na2Mn3Cl8

The kagome lattice can host exotic magnetic phases arising from frustrated and competing magnetic interactions. However, relatively few insulating kagome materials exhibit incommensurate magnetic ordering. Here, we present a study of the magnetic structures and interactions of antiferromagnetic Na$_2$Mn$_3$Cl$_8$ with an undistorted Mn$^{2+}$ kagome network. Using neutron-diffraction and bulk magnetic measurements, we show that Na$_2$Mn$_3$Cl$_8$ hosts two different incommensurate magnetic states, which develop at $T_{N1} = 1.6$ K and $T_{N2} = 0.6$ K. Magnetic Rietveld refinements indicate magnetic propagation vectors of the form $\mathbf{q} = (q_{x},q_{y},\frac{3}{2})$, and our neutron-diffraction data can be well described by cycloidal magnetic structures. By optimizing exchange parameters against magnetic diffuse-scattering data, we show that the spin Hamiltonian contains ferromagnetic nearest-neighbor and antiferromagnetic third-neighbor Heisenberg interactions, with a significant contribution from long-ranged dipolar coupling. This experimentally-determined interaction model is compared with density-functional-theory simulations. Using classical Monte Carlo simulations, we show that these competing interactions explain the experimental observation of multiple incommensurate magnetic phases and may stabilize multi-$\mathbf{q}$ states. Our results expand the known range of magnetic behavior on the kagome lattice.Comment: 13 pages, 8 figure

Characterisation of lignocellulosic sugars from municipal solid waste residue.

Municipal solid waste (MSW) contains significant quantities of plant-derived carbohydrates which have the potential to be exploited as a biomass source. This study evaluated the chemical composition and fractionation of MSW water-insoluble organic matter remaining after recycling of other components (MSWR). The organic matter was prepared as a dry, alcohol insoluble residue (MSWR-AIR, comprising w = 6% of original MSW) and size fractionated into fractions A, B, C & D. Carbohydrates were present in all the sub-fractions, comprising up to w = 54%; their complexity was also assessed by FT-IR spectroscopy. The lignin content in the samples ranged from w = 11–22%. The most carbohydrate-rich subfraction (C; w = 4% original MSW) was sequentially extracted to provide information on the likely constituent cell wall-derived polymers, sugar compositions and uronic acid content. The results indicate that approximately w = 25% of the MSWR-AIR comprises glucose, which appears to be mostly cellulosic in origin. The results are discussed in relation to the potential for exploitation