4,551 research outputs found
Calibration--granule pesticide applicators
"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
"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
"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
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
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
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
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
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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