4,122 research outputs found
Building Bridges: Opportunities Abound for P-20 Collaborations
PK-12 leaders value opportunities to collaborate with outside entities to improve student achievement and career-readiness. With increasing federal and state student-performance expectations for more than 1.4 million students enrolled in Texas public schools, collaborating with a public or private university, a community college, or a technical or health institute can provide important mutual benefits
Regrowth-related defect formation and evolution in 1 MeV amorphized (001) Ge
Geimplanted with 1MeV Si⁺ at a dose of 1×10¹⁵cm⁻² creates a buried amorphous layer that, upon regrowth, exhibits several forms of defects–end-of-range (EOR), regrowth-related, and clamshell defects. Unlike Si, no planar {311} defects are observed. The minimal EOR defects are small dotlike defects and are very unstable, dissolving between 450 and 550°C. This is in contrast to Si, where the EOR defects are very stable. The amorphous layer results in both regrowth-related defects and clamshell defects, which were more stable than the EOR damage.This work is supported by Semiconductor Research Corporation
Contract No. 00057787
Calibration of the Ames Anechoic Facility. Phase 1: Short range plan
A calibration was made of the acoustic and aerodynamic characteristics of a small, open-jet wind tunnel in an anechoic room. The jet nozzle was 102 mm diameter and was operated subsonically. The anechoic-room dimensions were 7.6 m by 5.5 m by 3.4 m high (wedge tip to wedge tip). Noise contours in the chamber were determined by various jet speeds and exhaust collector positions. The optimum nozzle/collector separation from an acoustic standpoint was 2.1 m. Jet velocity profiles and turbulence levels were measured using pressure probes and hot wires. The jet was found to be symmetric, with no unusual characteristics. The turbulence measurements were hampered by oil mist contamination of the airflow
Hypersaline microbial self-powered biosensor with increased sensitivity
The on-line, self-powered monitoring of the organic carbon content in hypersaline solutions (e.g. chemical oxygen demand, COD) based on a microbial biosensor would avoid the generation of toxic waste, originated by common COD analytical methods, and reduce the release of pollutants into the environment. Herein, a disposable cathode was applied to microbial fuel cells (MFCs) for the environmental friendly monitoring of the COD reaching a sensitivity one order of magnitude higher compared to the MFC with an air breathing cathode. Additionally, the entrapment of bacterial cells in alginate-capsules ensured a considerable linear range (up to approximately 10,000 mg COD L−1), providing opportunities for the wide application of the device to hypersaline solutions characterized by different origins and contamination levels
Calibrating Type Ia Supernovae using the Planetary Nebula Luminosity Function I. Initial Results
We report the results of an [O III] lambda 5007 survey for planetary nebulae
(PN) in five galaxies that were hosts of well-observed Type Ia supernovae: NGC
524, NGC 1316, NGC 1380, NGC 1448 and NGC 4526. The goals of this survey are to
better quantify the zero-point of the maximum magnitude versus decline rate
relation for supernovae Type Ia and to validate the insensitivity of Type Ia
luminosity to parent stellar population using the host galaxy Hubble type as a
surrogate. We detected a total of 45 planetary nebulae candidates in NGC 1316,
44 candidates in NGC 1380, and 94 candidates in NGC 4526. From these data, and
the empirical planetary nebula luminosity function (PNLF), we derive distances
of 17.9 +0.8/-0.9 Mpc, 16.1 +0.8/-1.1 Mpc, and 13.6 +1.3/-1.2 Mpc respectively.
Our derived distance to NGC 4526 has a lower precision due to the likely
presence of Virgo intracluster planetary nebulae in the foreground of this
galaxy. In NGC 524 and NGC 1448 we detected no planetary nebulae candidates
down to the limiting magnitudes of our observations. We present a formalism for
setting realistic distance limits in these two cases, and derive robust lower
limits of 20.9 Mpc and 15.8 Mpc, respectively.
After combining these results with other distances from the PNLF, Cepheid,
and Surface Brightness Fluctuations distance indicators, we calibrate the
optical and near-infrared relations for supernovae Type Ia and we find that the
Hubble constants derived from each of the three methods are broadly consistent,
implying that the properties of supernovae Type Ia do not vary drastically as a
function of stellar population. We determine a preliminary Hubble constant of
H_0 = 77 +/- 3 (random) +/- 5 (systematic) km/s/Mpc for the PNLF, though more
nearby galaxies with high-quality observations are clearly needed.Comment: 25 pages, 12 figures. Accepted for publication by the Astrophysical
Journal. Figures degraded to comply with limit. Full paper is available at:
http://www.as.ysu.edu/~jjfeldme/pnlf_Ia.pd
Additive effects of two growth QTL on cattle chromosome 14
The document attached has been archived with permission from the World Congress on Genetics Applied to Livestock Production.DNA-marker technology has the potential to assist seed-stock beef producers with genetic improvement of traits that are difficult to measure, and to assist research workers in identifying chromosomal regions containing quantitative trait loci (QTL), and eventually genes, which control animal performance traits. A collaborative study was established in 1995 between AgResearch in New Zealand (NZ) and Adelaide University in Australia to search for DNA markers significantly linked to production, carcass and meat quality traits in beef cattle. The present paper reports on a sub-set of that data, namely evidence from microsatellite markers on chromosome (Chr) 14 of significant linkage to growth traits and hot carcass weight (HSCW) at a standard level of trim
Cross-sectional transmission electron microscopy method and studies of implant damage in single crystal diamond
Few transmission electron microscopy(TEM) studies of single crystaldiamond have been reported, most likely due to the time and difficulty involved in sample preparation. A method is described for creating a TEM cross section of single crystaldiamond using a focused ion beam and in situ lift-out. The method results in samples approximately 10μm long by 3μm deep with an average thickness of 100–300nm. The total time to prepare a cross-sectional TEM sample of diamond is less than 5h. The method also allows for additional thinning to facilitate high resolution TEM imaging, and can be applied to oddly shaped diamond samples. This sample preparation technique has been applied to the study of ion implantation damage in single crystaldiamond and its evolution upon annealing. High-pressure–high-temperature diamonds were implanted with Si+ at an energy of 1MeV and a temperature of 30°C. One sample, with a (110) surface, was implanted with a dose of 1×10¹⁴Sicm−2 and annealed at 950°C for 10 and 40min. No significant defect formation or evolution was discernible by cross-sectional transmission electron microscopy. Another sample, with a (100) orientation, was implanted with 1MeV at 1×10¹⁵Sicm⁻² and annealed at 1050°C for 10min. Prior to annealing, a heavily damaged but still crystalline region was observed. Upon annealing, the sample showed no signs of conversion either to an amorphous form of carbon or to graphite. This is unexpected as the energy and dose are above the previously reported graphitization threshold for diamond. Higher annealing temperatures and possibly a high vacuum will be required for future study of defect formation, evolution, and phase transformations in ion-implanted single crystaldiamond
Larval dispersal in a changing ocean with an emphasis on upwelling regions
Dispersal of benthic species in the sea is mediated primarily through small, vulnerable larvae that must survive minutes to months as members of the plankton community while being transported by strong, dynamic currents. As climate change alters ocean conditions, the dispersal of these larvae will be affected, with pervasive ecological and evolutionary consequences. We review the impacts of oceanic changes on larval transport, physiology, and behavior. We then discuss the implications for population connectivity and recruitment and evaluate life history strategies that will affect susceptibility to the effects of climate change on their dispersal patterns, with implications for understanding selective regimes in a future ocean. We find that physical oceanographic changes will impact dispersal by transporting larvae in different directions or inhibiting their movements while changing environmental factors, such as temperature, pH, salinity, oxygen, ultraviolet radiation, and turbidity, will affect the survival of larvae and alter their behavior. Reduced dispersal distance may make local adaptation more likely in well-connected populations with high genetic variation while reduced dispersal success will lower recruitment with implications for fishery stocks. Increased dispersal may spur adaptation by increasing genetic diversity among previously disconnected populations as well as increasing the likelihood of range expansions. We hypothesize that species with planktotrophic (feeding), calcifying, or weakly swimming larvae with specialized adult habitats will be most affected by climate change. We also propose that the adaptive value of retentive larval behaviors may decrease where transport trajectories follow changing climate envelopes and increase where transport trajectories drive larvae toward increasingly unsuitable conditions. Our holistic framework, combined with knowledge of regional ocean conditions and larval traits, can be used to produce powerful predictions of expected impacts on larval dispersal as well as the consequences for connectivity, range expansion, or recruitment. Based on our findings, we recommend that future studies take a holistic view of dispersal incorporating biological and oceanographic impacts of climate change rather than solely focusing on oceanography or physiology. Genetic and paleontological techniques can be used to examine evolutionary impacts of altered dispersal in a future ocean, while museum collections and expedition records can inform modern-day range shifts
Ditopic Receptors Based on Dihomooxacalix[4]arenes Bearing Phenylurea Moieties With Electron-Withdrawing Groups for Anions and Organic Ion Pairs
Two bidentate dihomooxacalix[4]arene receptors bearing phenylurea moieties substituted with electron-withdrawing groups at the lower rim via a butyl spacer (CF3-Phurea 5b and NO2 Phurea 5c) were obtained in the cone conformation in solution, as shown by NMR. The X-ray crystal structure of 5b is reported. The binding affinity of these receptors toward several relevant anions was investigated by 1H NMR, UV-Vis absorption in different solvents, and fluorescence titrations. Compounds 5b and 5c were also tested as ditopic receptors for organic ion pairs, namely monoamine neurotransmitters and trace amine hydrochlorides by 1H NMR studies. The data showed that both receptors follow the same trend and, in comparison with the unsubstituted phenylurea 5a, they exhibit a significant enhancement on their host-guest properties, owing to the increased acidity of their urea NH protons. NO2-Phurea 5c is the best anion receptor, displaying the strongest complexation for F 12, closely followed by the oxoanions BzO 12, AcO 12, and HSO4-. Concerning ion pair recognition, both ditopic receptors presented an outstanding efficiency for the amine hydrochlorides, mainly 5c, with association constants higher than 109 M 122 in the case of phenylethylamine and tyramine
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