Galactic cosmic ray radial gradients and the anomalous He component near maximum solar modulation and to radii beyond 34 AU from the Sun

Radial gradients for relativistic galactic cosmic rays (E 70 MeV) remained nearly constant at approx. 2.5%/AU from 1978-84, which includes the period of maximum solar modulation in 1981-82. For energies 30-70 MeV/n, gradients decreased at solar maximum to values of 1%/AU (protons) and 4%/AU (helium), and appear to be increasing again in 1983-84 toward the values found for solar minimum. The anomalous helium component has not reappeared, either at 1 AU or at Pioneer 10 at R 34 AU

Chopped corn.

This bulletin reports on Missouri Agricultural Experiment Station research project 138, Forest Harvesting--P. [2].Digitized 2007 AES

An LDEF 2 dust instrument for discrimination between orbital debris and natural particles in near-Earth space

The characteristics of a space dust instrument which would be ideally suited to carry out near-Earth dust measurements on a possible Long Duraction Exposure Facility reflight mission (LDEF 2) is discussed. As a model for the trajectory portion of the instrument proposed for LDEF 2, the characteristics of a SPAce DUSt instrument (SPADUS) currently under development for flight on the USA ARGOS mission to measure the flux, mass, velocity, and trajectory of near-Earth dust is summarized. Since natural (cosmic) dust and man-made dust particles (orbital debris) have different velocity and trajectory distributions, they are distinguished by means of the SPADUS velocity/trajectory information. The SPADUS measurements will cover the dust mass range approximately 5 x 10(exp -12) g (2 microns diameter) to approximately 1 x 10(exp -5) g (200 microns diameter), with an expected mean error in particle trajectory of approximately 7 deg (isotropic flux). Arrays of capture cell devices positioned behind the trajectory instrumentation would provide for Earth-based chemical and isotopic analysis of captured dust. The SPADUS measurement principles, characteristics, its role in the ARGOS mission, and its application to an LDEF 2 mission are summarized

Rubber Tires Lead!

When farm machines are operated in the field or on the road at speeds higher than 2 1/2 to 3 miles per hour they should be equipped with rubber tires. And when these machines are pulled behind rubber-tired tractors the speed should be as high as the operating conditions and the design of the machines permit. In most cases the speed will be higher than 2 1/2 to 3 miles per hour for most efficient use

Life, service and cost of service of pneumatic tractor tires

The experience of Iowa farm users of 199 sets of pneumatic tractor tires indicates satisfactory durability and field performance. These users, selected as a representative sample, were located in 73 counties and represent the equivalent of 381 years of individual observation

Wind electric plants

The foregoing summary is based on the results from several years’ investigation of and one year’s operation,1 under test, of a wind electric plant located at this Station; and from a study2 of the performance of 66 wind electric plants on Iowa farms. The objective of these investigations was to determine as far as practicable the possibilities and limitations of the wind electric plant under Iowa farmstead conditions. The origin of the windmill is obscure. There is some evidence that it was first used in Persia during the early centuries of the Christian era.3 It came into prominent use in Europe during the twelfth century. Murphy4 gives a brief sketch of the early history of the windmill in America, and Barbour5 gives a good description of a large variety of homemade mills used in the Middlewest just following pioneer days

Tractive efficiency of the farm tractor

1. Of the total power used in agriculture, about one-half is used for field work and one-fifth for hauling. 2. Of the total primary power used in Iowa (1930) in farm operations, tractors comprise 39.4 percent and trucks 20 percent. 3. The maximum tractive efficiency of tractors tested under various conditions varied from 40 percent for soft field conditions to 84 percent for smooth hard sod. CONCERNING STEEL TRACTOR WHEELS 4. The rolling resistance of tractors over the tractive surfaces was the principal cause for low efficiency. 5. Lugs or grousers of excessive length used to increase adhesion on a firm surface or turf may cause considerable loss in efficiency. With a wheel tractor weighing 5,620 pounds, the power required to overcome rolling resistance at a speed of 3 miles per hour varied from 2.45 horse power with drive wheels without lugs to 6.3 horse power with drive wheels equipped with 4-inch spade lugs. Because of the lugs, rolling resistance on oat stubble did not differ greatly from that on freshly plowed land. 6. On a loose soil of uniform texture, an increase in length of spade lugs from 4 to 7 inches increasingly lowered tractive efficiency. 7. On a loose soil of uniform texture, an increase in the width of the tire by use of an extension rim gave higher tractive efficiency. 8. On soil with a loose surface, but firm subsurface, a spade lug 9 inches long reaching firm soil resulted in a slightly increased efficiency over 6 and 7-inch lugs but was less than for 4 and 5-inch lugs. 9. Five-inch angle lugs mounted on a wheel 42 inches in diameter with a rim 12-inches wide gave higher tractive efficiency than spade lugs on freshly prepared loose soil. 10. Extension angle iron lugs increased tractive efficiency on loose soil materially, about one-fifth to one-fourth. 11. Angle iron lugs extending over wheel rims were advantageous on sticky soil, because the soil did not pack in between the lugs. 12. Increasing the weight from 1,750 to 2,250 pounds on a 12 x 42-inch traction wheel equipped with spade lugs increased the drawbar pull 75 to 100 pounds at maximum efficiency. The drawbar pull was increased approximately 200 pounds when the wheel was equipped with extension rims and angle lugs. 13. Angle iron lugs gave slightly better results with a 6-inch rim extension than without on freshly prepared loose soil. 14. Open type traction wheels performed practically the same as 12-inch rim wheels with lugs on firm traction surfaces of cinders or sod. The rim did not function, as the weight was carried entirely on the lugs. 15. On loose freshly prepared soil where the space between the lugs did not fill with soil, the rim wheel gave slightly higher tractive efficiency than open wheels. 16. The tractive efficiency of steel drive wheels was progressively raised by increasing the diameter from 38 to 58 inches by 4-inch increments. 17. The effect of wheel diameter is more marked on less firm traction surfaces. CONCERNING LOW PRESSURE PNEUMATIC TIRES 18. The rolling resistance of a wheel tractor. defined herewith as drawbar pull or its equivalent required to move the tractor over a given surface, was materially reduced by low pressure pneumatic tires for all conditions observed. 19. On a smooth hard surface the maximum tractive efficiency of a tractor equipped with pneumatic tires was 84 percent. 20. The maximum drawbar pull of a tractor equipped with low pressure pneumatic tires was materially reduced on stubble and loose soil. 21. The maximum drawbar pull of tractors equipped with low pressure pneumatic tires can be increased by additional weight, chains or lugs. 22. The maximum tractive efficiency was increased progressively with a decrease of inflation pressure from 20 to 16, 12 and 8 pounds per square inch. CONCERNING TRACKS 23. The tractive efficiency of a track tractor as observed is not materially influenced by normal variations of traction surfaces. 24. On freshly prepared loose soil maximum tractive efficiency of a track was lowered by increasing the height of hitch

Anatomic Fat Depots and Coronary Plaque Among Human Immunodeficiency Virus-Infected and Uninfected Men in the Multicenter AIDS Cohort Study.

Methods.  In a cross-sectional substudy of the Multicenter AIDS Cohort Study, noncontrast cardiac computed tomography (CT) scanning for coronary artery calcium (CAC) scoring was performed on all men, and, for men with normal renal function, coronary CT angiography (CTA) was performed. Associations between fat depots (visceral adipose tissue [VAT], abdominal subcutaneous adipose tissue [aSAT], and thigh subcutaneous adipose tissue [tSAT]) with coronary plaque presence and extent were assessed with logistic and linear regression adjusted for age, race, cardiovascular disease (CVD) risk factors, body mass index (BMI), and human immunodeficiency virus (HIV) parameters. Results.  Among HIV-infected men (n = 597) but not HIV-uninfected men (n = 343), having greater VAT was positively associated with noncalcified plaque presence (odds ratio [OR] = 1.04, P < .05), with a significant interaction (P < .05) by HIV serostatus. Human immunodeficiency virus-infected men had lower median aSAT and tSAT and greater median VAT among men with BMI <25 and 25-29.9 kg/m(2). Among HIV-infected men, VAT was positively associated with presence of coronary plaque on CTA after adjustment for CVD risk factors (OR = 1.04, P < .05), but not after additional adjustment for BMI. There was an inverse association between aSAT and extent of total plaque among HIV-infected men, but not among HIV-uninfected men. Lower tSAT was associated with greater CAC and total plaque score extent regardless of HIV serostatus. Conclusions.  The presence of greater amounts of VAT and lower SAT may contribute to increased risk for coronary artery disease among HIV-infected persons

On the Spatial Distribution of Stellar Populations in the Large Magellanic Cloud

We measure the angular correlation function of stars in a region of the Large Magellanic Cloud (LMC) that spans 2 degrees by 1.5 degrees. We find that the correlation functions of stellar populations are represented well by exponential functions of the angular separation for separations between 2 and 40 arcmin (corresponding to ~ 30 pc and 550 pc for an LMC distance of 50 kpc). The inner boundary is set by the presence of distinct, highly correlated structures, which are the more familiar stellar clusters, and the outer boundary is set by the observed region's size and the presence of two principal centers of star formation within the region. We also find that the normalization and scale length of the correlation function changes systematically with the mean age of the stellar population. The existence of positive correlation at large separations (~300 pc), even in the youngest population, argues for large-scale hierarchical structure in current star formation. The evolution of the angular correlation toward lower normalizations and longer scale lengths with stellar age argues for the dispersion of stars with time. We show that a simple, stochastic, self-propagating star formation model is qualitatively consistent with this behavior of the correlation function.Comment: 30 pages, 13 Figures. Scheduled for publication in AJ in June 199