4,551 research outputs found

    Calibration--granule pesticide applicators

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    "Some pesticides are applied as granules with granule applicators. These granular pesticides are usually applied to the soil. Most granules used for row crops are applied with a band applicator or a broadcast applicator. Granules are prediluted with a fixed amount of pesticide; so there is no need for mixing."--First page..Maurice R. Gebhardt (Agricultural Research Service, U.S. Department of Agriculture ; Agricultural Engineering Department, College of Agriculture)Revised 4/87/8

    Sprayer calibration, part 2--band sprayers

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    "Pesticides are effective only after they have been applied in the correct amount. Too much pesticide can cause crop injury and leave harmful residues. Too little pesticide may cause inadequate and undependable control. The number of gallons applied per acre depends on (1) nozzle size, (2) pressure of the spray, and (3) ground speed of the sprayer. Spray calibration is a procedure to determine how much water and chemical is applied per acre."--First page.Maurice R. Gebhardt (Agricultural Research Service, USDA)Reviewed and reprinted 7/87/5

    Sprayer calibration : broadcast sprayers

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    "Pesticides are effective only if applied at the correct amount per acre. Too much pesticide can injure crops and leave harmful residues; too little can give inadequate and undependable control."--First page.Maurice R. Gebhardt (Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Agricultural Engineering Department, College of Agriculture)Revised 7/79/10

    Group-theoretic models of the inversion process in bacterial genomes

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    The variation in genome arrangements among bacterial taxa is largely due to the process of inversion. Recent studies indicate that not all inversions are equally probable, suggesting, for instance, that shorter inversions are more frequent than longer, and those that move the terminus of replication are less probable than those that do not. Current methods for establishing the inversion distance between two bacterial genomes are unable to incorporate such information. In this paper we suggest a group-theoretic framework that in principle can take these constraints into account. In particular, we show that by lifting the problem from circular permutations to the affine symmetric group, the inversion distance can be found in polynomial time for a model in which inversions are restricted to acting on two regions. This requires the proof of new results in group theory, and suggests a vein of new combinatorial problems concerning permutation groups on which group theorists will be needed to collaborate with biologists. We apply the new method to inferring distances and phylogenies for published Yersinia pestis data.Comment: 19 pages, 7 figures, in Press, Journal of Mathematical Biolog

    Dynamical Measurements of Black Hole Masses in Four Brightest Cluster Galaxies at 100 Mpc

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    We present stellar kinematics and orbit superposition models for the central regions of four Brightest Cluster Galaxies (BCGs), based upon integral-field spectroscopy at Gemini, Keck, and McDonald Observatories. Our integral-field data span radii from < 100 pc to tens of kpc. We report black hole masses, M_BH, of 2.1 +/- 1.6 x 10^10 M_Sun for NGC 4889, 9.7 + 3.0 - 2.6 x 10^9 M_Sun for NGC 3842, and 1.3 + 0.5 - 0.4 x 10^9 M_Sun for NGC 7768. For NGC 2832 we report an upper limit of M_BH < 9 x 10^9 M_Sun. Stellar orbits near the center of each galaxy are tangentially biased, on comparable spatial scales to the galaxies' photometric cores. We find possible photometric and kinematic evidence for an eccentric torus of stars in NGC 4889, with a radius of nearly 1 kpc. We compare our measurements of M_BH to the predicted black hole masses from various fits to the relations between M_BH and stellar velocity dispersion, luminosity, or stellar mass. The black holes in NGC 4889 and NGC 3842 are significantly more massive than all dispersion-based predictions and most luminosity-based predictions. The black hole in NGC 7768 is consistent with a broader range of predictions.Comment: 24 pages, 18 figures. Accepted for publication in Ap

    The supermassive black hole in NGC4486a detected with SINFONI at the VLT

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    The near-infrared integral field spectrograph SINFONI at the ESO VLT opens a new window for the study of central supermassive black holes. With a near-IR spatial resolution similar to HST optical and the ability to penetrate dust it provides the possibility to explore the low-mass end of the M-sigma relation (sigma<120km/s) where so far very few black hole masses were measured with stellar dynamics. With SINFONI we observed the central region of the low-luminosity elliptical galaxy NGC4486a at a spatial resolution of ~0.1arcsec in the K band. The stellar kinematics was measured with a maximum penalised likelihood method considering the region around the CO absorption band heads. We determined a black hole mass of M_BH=1.25^{+0.75}_{-0.79} x 10^7 M_sun (90% C.L.) using the Schwarzschild orbit superposition method including the full 2-dimensional spatial information. This mass agrees with the predictions of the M-sigma relation, strengthening its validity at the lower sigma end.Comment: 7 pages, 7 figures. Accepted by MNRA

    A 20 Thousand Solar Mass Black Hole in the Stellar Cluster G1

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    We present the detection of a 2.0(+1.4,-0.8)x10^4 solar mass black hole (BH) in the stellar cluster G1 (Mayall II), based on data taken with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. G1 is one of the most massive stellar clusters in M31. The central velocity dispersion (25 kms) and the measured BH mass of G1 places it on a linear extrapolation of the correlation between BH mass and bulge velocity dispersion established for nearby galaxies. The detection of a BH in this low-mass stellar system suggests that (1) the most likely candidates for seed massive BHs come from stellar clusters, (2) there is a direct link between massive stellar clusters and normal galaxies, and (3) the formation process of both bulges and massive clusters is similar due to their concordance in the M_BH/sigma relation. Globular clusters in our Galaxy should be searched for central BHs.Comment: 4 pages, accepted in The Astrophysical Journal Letters, October 200

    Optometric referral guide for physical and occupational therapists

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    The purpose of this manual is to provide an optometric referral guide for use by rehabilitative therapists. The manual will provide criteria to determine whether optometric services are indicated in either primary care or vision therapy. This guide is an effort to enhance comprehensive care for the patient and strengthen interdisciplinary interaction. The conditions requiring optometric referral, as discussed in this manual, include: Cerebrovascular Accident, Traumatic Brain Injury, and Demyelinating Disorders. Suggestions for optometric examination based on the overlapping populations that rehabilitative therapists and optometrists serve include: Geriatrics, Pediatrics, and Indigent Care. The manual reviews symptoms and signs of given visual disturbances as well as comanagement treatment strategies
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