4,391 research outputs found
A Life History Study of Caecilius Aurantiacus (Hagen) (Psocoptera: Caeciliidae)
Caecilius aurantiacus is a common, widely distributed psocid in well established forested areas of North America. Published information on this species is fragmentary and limited primarily to taxonomy. This paper is a description of the habits and biology of this small, little-known, but common insect. Of the 212 named species in the genus Caecilius (Smithers, 1967), the bionomics of only Caecilius manteri have been published
Relationship of herd average somatic cell count and spontaneous recovery from subclinical mastitis
The rate of spontaneous recovery from subclinical mastitis was evaluated in
56 Kansas. DHI herds participating in the Somatic Cell Count (SCC) program. Herds
were classified as low (>300,000) or high (>600,000) based on herd sec average.
Comparisons between low and high SCC-herds were made for each cow's ability to
recover from a subclinical case of mastitis (>600,000 SCC). Low-SCC herds had a
rate of spontaneous recovery that was more than three times greater than that of
high-SCC herds. Average SCC of cows with subclinical mastitis was similar in low
and high herds J as well as the average sec of cows following spontaneous
recovery. Results illustrate the importance of monitoring monthly sec reports.
Proper attention to good procedures of milking management includes: attention to
milking techniques, proper function of milking equipment, and attention to
sanitation and housing conditions. As a result, herds with low SCC tests will have
higher production and fewer subclinical cases of mastitis
Cold Case Files: The Athenian Grain Merchants 386 B.C.
While most economic analysis of the effects of market power has focused on monopoly power (a single seller of a good) or cartels among sellers, there has always remained some degree of interest in monopsony power (a single buyer) or buying cartels. In the United States there have been antitrust cases involving monopsony and buyer's cartels at least as far back as 1925, and there is continuing interest in the potential for monopsony power in the retail and health care sectors. This paper examines one of the earliest known antitrust or competition policy cases for possible lessons concerning antitrust treatment of monopsony power in the present day. In 388 B.C., grain regulators in Athens, Greece, were attempting to respond to a sharp increase in grain prices. They encouraged grain importers to form a buyers' cartel with the purpose of decreasing the price of imported grain. However, this action resulted in an overall increase in price and the grain merchants soon found themselves on trial for their lives. In this paper the information presented at that trial is used to evaluate the grain merchants' actions and the impact of monopsony on prices and consumption more generally.
Low-altitude wind measurements from wide-body jet transports
For a 2-week period in the spring of 1977, data were collected onboard wide-body jet transports for the determination of winds and wind shear during landings and take-offs. The data represent about 640 take-offs or landings at 14 airports in Europe and the United States. Analysis of the wind-shear data indicates that shears of a given value are equally likely to occur at any altitude in the lower 1400-ft section of the atmosphere. Analysis of the data indicates that low shears (plus or minus .033 knot/per ft) have a 67-percent chance of occurrence during a landing or take-off, while higher values (plus or minus 0.15 knot/per ft) have a 0.5-percent chance of occurrence. A determination of the duration of a given shear was not made
The potential influence of rain on airfoil performance
The potential influence of heavy rain on airfoil performance is discussed. Experimental methods for evaluating rain effects are reviewed. Important scaling considerations for extrapolating model data are presented. It is shown that considerable additional effort, both analytical and experimental, is necessary to understand the degree of hazard associated with flight operations in rain
Unsuccessful Concepts for Aircraft Wake Vortex Minimization
Exploratory concepts are described which were investigated to achieve a reduction in the vortex induced rolling upsets produced by heavy aircraft trailing vortexes. The initial tests included the use of mass injection, oscillating devices, wingtip shape design, interacting multiple vortexes, and end plates. Although later refinements of some of these concepts were successful, initial test results did not indicate a capability of these concepts to significantly alter the vortex induced rolling upset on a following aircraft
A Systematic Search for Molecular Outflows Toward Candidate Low-Luminosity Protostars and Very Low Luminosity Objects
We present a systematic single-dish search for molecular outflows toward a
sample of 9 candidate low-luminosity protostars and 30 candidate Very Low
Luminosity Objects (VeLLOs; L_int < 0.1 L_sun). The sources are identified
using data from the Spitzer Space Telescope catalogued by Dunham et al. toward
nearby (D < 400 pc) star forming regions. Each object was observed in 12CO and
13CO J = 2-1 simultaneously using the sideband separating ALMA Band-6 prototype
receiver on the Heinrich Hertz Telescope at 30 arcsecond resolution. Using
5-point grid maps we identify five new potential outflow candidates and make
on-the-fly maps of the regions surrounding sources in the dense cores B59,
L1148, L1228, and L1165. Of these new outflow candidates, only the map of B59
shows a candidate blue outflow lobe associated with a source in our survey. We
also present larger and more sensitive maps of the previously detected L673-7
and the L1251-A IRS4 outflows and analyze their properties in comparison to
other outflows from VeLLOs. The accretion luminosities derived from the outflow
properties of the VeLLOs with detected CO outflows are higher than the observed
internal luminosity of the protostars, indicating that these sources likely had
higher accretion rates in the past. The known L1251-A IRS3 outflow is detected
but not remapped. We do not detect clear, unconfused signatures of red and blue
molecular wings toward the other 31 sources in the survey indicating that
large-scale, distinct outflows are rare toward this sample of candidate
protostars. Several potential outflows are confused with kinematic structure in
the surrounding core and cloud. Interferometric imaging is needed to
disentangle large-scale molecular cloud kinematics from these potentially weak
protostellar outflows.Comment: 42 pages, 19 figures, Accepted for publication in the Astronomical
Journa
Aircraft wake-vortex minimization by use of flaps
A survey was made of research on the alleviation of the trailing vortex hazard by altering span loading with flaps on the generator airplane. Flap configurations of the generator that shed multiple vortices were found to have wakes that dispersed by vortex merging and sinusoidal instability. Reductions of approximately 50 percent in both the wake rolling moment imposed on a following aircraft and the aircraft separation requirement were achieved in the ground based and flight test experiments by deflecting the trailing edge flaps more inboard than outboard. Significantly, this configuration did not increase the drag or vibration on the generating aircraft compared to the conventional landing configuration. Ground based results of rolling moment measurement and flow visualization are shown, using a water tow facility, an air tow facility, and a wind tunnel. Flight test results are also shown, using a full scale B-747 airplane. General agreement was found among the results of the various ground based facilities and the flight tests
Evaluation of a contact-analog display in landing approaches with a helicopter
Evaluation of contact analog display in landing approaches with helicopter
Low speed wind tunnel investigation of span load alteration, forward-located spoilers, and splines as trailing-vortex-hazard alleviation devices on a transport aircraft model
The effectiveness of a forward-located spoiler, a spline, and span load alteration due to a flap configuration change as trailing-vortex-hazard alleviation methods was investigated. For the transport aircraft model in the normal approach configuration, the results indicate that either a forward-located spoiler or a spline is effective in reducing the trailing-vortex hazard. The results also indicate that large changes in span loading, due to retraction of the outboard flap, may be an effective method of reducing the trailing-vortex hazard
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