8,376 research outputs found
Design study of general aviation collision avoidance system
The selection and design of a time/frequency collision avoidance system for use in general aviation aircraft is discussed. The modifications to airline transport collision avoidance equipment which were made to produce the simpler general aviation system are described. The threat determination capabilities and operating principles of the general aviation system are illustrated
Report of a workshop on large whale medical intervention : indications and technology development
Sponsors: Woods Hole Oceanographic Institution, Center for Coastal Studies, New England Aquarium. Location: Carriage House, Woods Hole Oceanographic Institution, Woods Hole MA 02543. Date: Monday February 7th 2000This one day interdisciplinary workshop, attended by 12 veterinarians 11 whale
biologists, an engineer and the NMFS Regional Stranding Coordinator, was convened by
Michael Moore, with financial support from the Woods Hole Oceanographic Institution Cecil
and Ida Green Technology Innovation Fund. The goal was to examine ways in which veterinary
medical techniques could assist in efforts to mitigate right whale mortality. In particular the
indications and technology for the use of sedation during disentanglement efforts and antibiotic
therapy for wounds after disentanglement were considered.Woods Hole Oceanographic Institution Cecil
and Ida Green Technology Innovation Fun
Quantitative Trait Locus Mapping of Winter Hardiness Metabolites in Autotetraploid Alfalfa (M. sativa)
In winter hardy alfalfa cultivars, cold acclimation occurs prior to the onset of freezing temperatures and normally is accompanied with a series of metabolic and morphological adjustments. We are studying the accumulation pattern of metabolites throughout the autumn previous to freezing and relating them to winter survival in an Fl segregating population between the cross of M. sativa subsp. sativa and subsp. falcata. Morphological components and soluble carbohydrates, protein, amino-N groups, and free fatty acids were measured in 2001 and 2002 in the field. Broad sense heritability was intermediate for shoot and root mass and height, and for metabolites, ranged from low (TNC=0.04) to high (starch=0.80). The genetic correlation between winter injury was not significant for most of the metabolites, except for soluble protein and amino-N group concentrations. The presence of allele al of MSAIC B, a cold-related gene, was positively associated with autumn plant height but negatively associated with root mass in the WISFAL-6 parent. Numerous QTL were detected for concentrations of metabolites. Our results suggest that winter injury and autumn biomass are controlled by different loci in this population
Quantum and classical chaos for a single trapped ion
In this paper we investigate the quantum and classical dynamics of a single
trapped ion subject to nonlinear kicks derived from a periodic sequence of
Guassian laser pulses. We show that the classical system exhibits diffusive
growth in the energy, or 'heating', while quantum mechanics suppresses this
heating. This system may be realized in current single trapped-ion experiments
with the addition of near-field optics to introduce tightly focussed laser
pulses into the trap.Comment: 8 pages, REVTEX, 8 figure
Silicon fertilisation affects morphological and immune defences of an insect pest and enhances plant compensatory growth
Herbivorous insects have evolved various anti-predator defences, including morphological, behavioural, and immune defences, which can make biocontrol of herbivorous pests challenging. Silicon (Si) accumulation in plants is a potent physical defence against mandibulate insects. However, it remains uncertain how Si affects the anti-predator defences of insect herbivores and plant defences following herbivory. We grew the model grass, Brachypodium distachyon, hydroponically with (+Si) or without (âSi) Si and investigated the plant-mediated effects of Si on the anti-predator defences of the cotton bollworm, Helicoverpa armigera, integrating morphological (i.e. integument resistance and thickness), behavioural, and immune defences. We also examined the effects of Si on plant compensatory growth and leaf trichome production. Larval growth, leaf consumption, and integument resistance were lower when feeding on +Si plants compared to when feeding on âSi plants. Larval integument thickness, defensive behaviours, haemocyte density, and lysozyme-like activity in the haemolymph
were unaffected by Si. Larvae fed on +Si plants had higher haemolymph phenoloxidase (PO) and total-PO activities than larvae fed on âSi plants, although this did not enhance the melanisation response of larvae. Furthermore, Si supplies increased plant compensation for herbivory and constitutive trichome production, whereas herbivory induced trichome production only on âSi plants. We provide the first evidence for plant-mediated effects of Si on anti-predator defences of an insect herbivore. We suggest that the lower integument resistance of larvae when feeding on Si-supplemented plants could contribute to their
vulnerability to natural enemies and that high PO activity may impose fitness costs (e.g. delayed development)
Technical Report: TeraGrid eXtreme Digital Campus Cyberinfrastructure and Campus Bridging Requirements Elicitation Meeting
In an effort to systematically investigate requirements for TeraGrid XD, the XROADS collaboration held during 2009 a series of requirements elicitation meetings (REM) with small groups of stakeholders. This report summarizes the conduct of and results from a requirements elicitation meeting on the topics of campus bridging and campus cyberinfrastructure. The meetingâs goal was to develop a clearer and more functional definition of what the next phase of the TeraGrid should do to be a resource broadly useful to and used by university and college campuses throughout the US.This report depends very much on the prior involvement of several XROADS partners in the TeraGrid, which has been funded in part by the NSF via the following grant awards:
0504086, 0503697, and 0742145 to the University of Chicago; 0451237 and 0504075 to Indiana University; and 0122272, 0332113, 0451566, 0503944, 0910847 to the University of California San Diego
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Root herbivore performance suppressed when feeding on a jasmonate-induced pasture grass
1. Plants defend themselves from insect herbivore attack using a range of physical and chemical defences which are in many cases regulated by phytohormones such as jasmonates. While much more is known about how jasmonates regulate defence against aboveâground herbivores (e.g. herbivores of leaves), there is increasing interest in how they influence belowâground defences.
2. For the Poaceae, most belowâground studies focus on highly domesticated cereals. Here it is demonstrated how exogenous application of methyl jasmonate (MeJA) to the leaf blades of a nonâdomesticated pasture grass (Microlaena stipoides) caused a more than twoâfold decrease in relative growth rate (RGR) of a rootâfeeding chafer (Dermolepida albohirtum). MeJA treatment did not affect root consumption rates, but substantially reduced the efficiency of conversion of ingested food to body mass.
3. Nonâtargeted metabolomics identified significant changes in the metabolome of MeJAâinduced plants, with three compounds (a galactolipid, a trihydroxy fatty acid and a lysophospholipid) found to be correlated with herbivore RGR, although their roles in herbivore defence remain uncertain.
4. This study suggests that an important Australian pasture grass can become better defended against root herbivores via enhanced jasmonate activity
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Effects of elevated temperature and CO2 on aboveground-belowground systems: a case study with plants, their mutualistic bacteria and root/shoot herbivores
Interactions between above- and belowground herbivores have been prominent in the field of aboveground-belowground ecology from the outset, although little is known about how climate change affects these organisms when they share the same plant. Additionally, the interactive effects of multiple factors associated with climate change such as elevated temperature (eT) and elevated atmospheric carbon dioxide (eCO2) are untested. We investigated how eT and eCO2 affected larval development of the lucerne weevil (Sitona discoideus) and colonization by the pea aphid (Acyrthosiphon pisum), on three cultivars of a common host plant, lucerne (Medicago sativa). Sitona discoideus larvae feed on root nodules housing N2-fixing rhizobial bacteria, allowing us to test the effects of eT and eCO2 across trophic levels. Moreover, we assessed the influence of these factors on plant growth. eT increased plant growth rate initially (6, 8 and 10 weeks after sowing), with cultivar âSequelâ achieving the greatest height. Inoculation with aphids, however, reduced plant growth at week 14. eT severely reduced root nodulation by 43%, whereas eCO2 promoted nodulation by 56%, but only at ambient temperatures. Weevil presence increased net root biomass and nodulation, by 31 and 45%, respectively, showing an overcompensatory plant growth response. Effects of eT and eCO2 on root nodulation were mirrored by weevil larval development; eT and eCO2 reduced and increased larval development, respectively. Contrary to expectations, aphid colonization was unaffected by eT or eCO2, but there was a near-significant 10% reduction in colonization rates on plants with weevils present belowground. The contrasting effects of eT and eCO2 on weevils potentially occurred through changes in root nodulation patterns
Secondary Electron Yield Measurements of Fermilab's Main Injector Vacuum Vessel
We discuss the progress made on a new installation in Fermilab's Main
Injector that will help investigate the electron cloud phenomenon by making
direct measurements of the secondary electron yield (SEY) of samples irradiated
in the accelerator. In the Project X upgrade the Main Injector will have its
beam intensity increased by a factor of three compared to current operations.
This may result in the beam being subject to instabilities from the electron
cloud. Measured SEY values can be used to further constrain simulations and aid
our extrapolation to Project X intensities. The SEY test-stand, developed in
conjunction with Cornell and SLAC, is capable of measuring the SEY from samples
using an incident electron beam when the samples are biased at different
voltages. We present the design and manufacture of the test-stand and the
results of initial laboratory tests on samples prior to installation.Comment: 3 pp. 3rd International Particle Accelerator Conference (IPAC 2012)
20-25 May 2012, New Orleans, Louisian
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