6,810 research outputs found

    Cereal Leaf Beetle (Coleoptera: Chrysomelidae) Influence of Seeding Rate of Oats on Populations

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    In field and greenhouse studies, more cereal leaf beetle [Oulema melanopus (Lin- naeus)] eggs and larvae were found per unit area on spring oats, Avena sativa L., planted either at intermediate (54 kg/ha) or high (136 kg/ha) seeding rates, than when planted at a lower seeding rate (14 kg/ha). However, there were fewer eggs and larvae per stem in plantings of the high or intermediate rates than in those of the lower rate. Oats should not be planted at less than the recommended rates in beetle-infested areas

    Laparoscopic versus open colorectal resection for cancer and polyps: A cost-effectiveness study

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    Methods: Participants were recruited in 2006-2007 in a district general hospital in the south of England; those with a diagnosis of cancer or polyps were included in the analysis. Quality of life data were collected using EQ-5D, on alternate days after surgery for 4 weeks. Costs per patient, from a National Health Service perspective (in British pounds, 2006) comprised the sum of operative, hospital, and community costs. Missing data were filled using multiple imputation methods. The difference in mean quality adjusted life years and costs between surgery groups were estimated simultaneously using a multivariate regression model applied to 20 imputed datasets. The probability that laparoscopic surgery is cost-effective compared to open surgery for a given societal willingness-to-pay threshold is illustrated using a cost-effectiveness acceptability curve

    On the spectrum of atmospheric velocity fluctuations seen by MST/ST radar and their interpretation

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    The observations of the spectrum of atmospheric motions over the range of periods from a few minutes to many hours are considered that have been made with stratosphere-troposphere/mesosphere-stratosphere (ST/MST) radars in the past five years. This range of periods includes the periods associated with buoyancy waves and the scale of atmospheric motions often referred to by meteorologists as the mesoscale. The spectra of horizontal and vertical velocities are considered. Their interpretation is examined in terms of buoyancy wave theory and turbulence theory. To help in interpreting these spectra some recently determined aircraft wave number spectra are presented

    Ecological Observations on Predatory Coccinellidae (Coleoptera) in Southwestern Michigan

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    Ecological observations on habitat utilization by thirteen species of predatory Coccinellidae were made at a southern Michigan site during 1989 and 1990. Most of species were common during both years and used both agricul- tural and uncultivated habitats. Coccinella septempunctata and Coleomegilla maculata, were the most abundant in agricultural crops (alfalfa, maize, soy- bean and triticale), whereas Adalia bipunctata and Cycloneda munda, were the most abundant in deciduous and bushy habitats

    Application of Risk Informed Decision Making to Highly Reliable Three Dimensionally Woven Thermal Protection System for Mars Sample Return

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    The NASA Risk Informed Decision Making process is used to assess a trade space of three dimensionally woven thermal protection systems for application to the Mars Sample Return Earth Entry Vehicle. Candidate architectures are assessed based on mission assurance, technical development, cost, and schedule risk. Assessment methodology differed between the architectures, utilizing a four-point quantitative scale for mission assurance and technical development and highly tailored PERT techniques for cost and schedule. Risk results are presented, in addition to a review of RIDM effectiveness for this application

    The proposed flatland radar

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    A flexible very high frequency (VHF) stratosphere-troposphere (ST) radar configured for meteorological research is to be constructed near Urbana, Illinois. Measurement of small vertical velocities associated with synoptic-scale meteorology can be performed. A large Doppler microwave radar (CHILL) is located a few km from the site of the proposed ST radar. Since the microwave radar can measure the location and velocity of hydrometeors and the VHF ST radar can measure clear (or cloudy) air velocities, simultaneous observations by these two radars of stratiform or convective weather systems would provide valuable meteorological information

    Optimized magneto-optical isolator designs inspired by seedlayer-free terbium iron garnets with opposite chirality

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    Simulations demonstrate that undoped yttrium iron garnet (YIG) seedlayers cause reduced Faraday rotation in silicon-on-insulator (SOI) waveguides with Ce-doped YIG claddings. Undoped seedlayers are required for the crystallization of the magneto-optical Ce:YIG claddings, but they diminish the interaction of the Ce:YIG with the guided modes. Therefore new magneto-optical garnets, terbium iron garnet (TIG) and bismuth-doped TIG (Bi:TIG), are introduced that can be integrated directly on Si and quartz substrates without seedlayers. The Faraday rotations of TIG and Bi:TIG films at 1550nm were measured to be +500 and -500°/cm, respectively. Simulations show that these new garnets have the potential to significantly mitigate the negative impact of the seedlayers under Ce:YIG claddings. The successful growth of TIG and Bi:TIG on low-index fused quartz inspired novel garnet-core waveguide isolator designs, simulated using finite difference time domain (FDTD) methods. These designs use alternating segments of positive and negative Faraday rotation for push-pull quasi phase matching in order to overcome birefringence in waveguides with rectangular cross-sections

    Shaped nozzles for cryogenic buffer gas beam sources

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    Cryogenic buffer gas beams are important sources of cold molecules. In this work we explore the use of a converging-diverging nozzle with a buffer-gas beam. We find that, under appropriate circumstances, the use of a nozzle can produce a beam with improved collimation, lower transverse temperatures, and higher fluxes per solid angle

    Measurement of vertical velocity using clear-air Doppler radars

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    A new clear air Doppler radar was constructed, called the Flatland radar, in very flat terrain near Champaign-Urbana, Illinois. The radar wavelength is 6.02 m. The radar has been measuring vertical velocity every 153 s with a range resolution of 750 m almost continuously since March 2, 1987. The variance of vertical velocity at Flatland is usually quite small, comparable to the variance at radars located near rough terrain during periods of small background wind. The absence of orographic effects over very flat terrain suggests that clear air Doppler radars can be used to study vertical velocities due to other processes, including synoptic scale motions and propagating gravity waves. For example, near rough terrain the shape of frequency spectra changes drastically as the background wind increases. But at Flatland the shape at periods shorter than a few hours changes only slowly, consistent with the changes predicted by Doppler shifting of gravity wave spectra. Thus it appears that the short period fluctuations of vertical velocity at Flatland are alsmost entirely due to the propagating gravity waves

    Enabling Entry Technologies for Ice Giant Missions

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    The highest priority science goals for Ice Giant missions are: 1) Interior structure of the Planet, and 2) Bulk composition that includes isotopes and noble gases. The interaction between the planetary interior and the atmosphere requires sustained global measurements. Noble gas and Isotope measurements require in situ measurement. Drag modulated aerocapture utilizing ADEPT offers more mass delivered to the Ice Giants than with propulsive orbit insertion. The Galileo Probe entered at a hot spot which created interpretation challenges. Juno is providing valuable orbital measurements, but without in situ measurements the story is incomplete. Planetary scientists interested in Ice Giant missions should perform mission design studies with these new Entry System technologies to assess the feasibility within the context of the international collaboration framework. A mission architecture that includes probe(s) along with an orbiting spacecraft can deploy the probes at the desired location while taking simultaneous measurements from orbit to provide invaluable data that can correlate both global and local measurements. Entry System Technologies currently being developed by NASA are poised to enable missions that position the Orbiter & Probes through drag modulated aerocapture (ADEPT), and HEEET enables the Probes to survive the extreme environments encountered for entry into the atmospheric interior
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