The synthesis of the africane-type sesquiterpenoid, 1,5,8,8-tetramethyl-tricyclo[8,1,0,02,6]undec-5-en-9-ol-4-one

One of the alcohols derived from rearrangement of humulene-4,5-epoxide has been converted into a keto-alcohol, the angelate ester of which is a naturally-occurring sesquiterpenoid.     

Obstructions to homotopy equivalences

An obstruction theory is developed to decide when an isomorphism of rational cohomology can be realized by a rational homotopy equivalence (either between rationally nilpotent spaces, or between commutative graded differential algebras). This is used to show that a cohomology isomorphism can be so realized whenever it can be realized over some field extension (a result obtained independently by Sullivan).In particular an algorithmic method is given to decide when a c.g.d.a. has the same homotopy type as its cohomology (the c.g.d.a. is called formal in this case).The chief technique is the construction of a canonically filtered model for a commutative graded differential algebra (over a field of characteristic zero) by perturbing the minimal model for the cohomology algebra. This filtered model is also used to give a simple construction of the Eilenberg-Moore spectral sequence arising from the bar construction. An example is given of a c.g.d.a. whose Eilenberg-Moore sequence collapses, yet which is not formal.     

The Application of a Digital Computer to Mechanical Testing

A digital computer is being used to record raw data and to provide automatic data calculations for mechanical tests. The computer which is connected through an analog-digital converter to a universal testing machine and to a torsion tester, stores the raw loadstrain data, converts it to stress-strain data, and calculates any of the mechanical properties desired from the test. The computer can also provice a printout and a paper tape, both of which contain the stress-strain data points and the calculated data. In addition, the loadstrain data that are normally obtained from the test machine are still available. An oscilloscope display is obtained as the data are being recorded. Tests which are presently being performed using the computer are: tensile, compression, pin bearing, double shear and torsion. Data which are being recorded include: ultimate strength, offset yield strength, elastic and shear moduli, energy under the stress-strain curve, and a mathematical expression for the stress-strain curve. In addition to the mechanical load-strain curve provided by the test machine, the computer can provide a stressstrain curve and a listing of stress-strain data points.     

Polymer reactions. II. Thermal decomposition of polyethylene hydroperoxide

Polyethylene hydroperoxide (PEH) was prepared by low-temperature autoxidation initiated by AIBN. Over 85% of the total hydroperoxyl groups decompose by a rapid process, the remainder dissociate at about one-tenth of that rate. The results are the same whether PEH is decomposed in solution or in the solid state. Large amounts of scavenger have no effect on these decompositions; there is no radical-induced processes. The results suggest mechanisms of decomposition involving neighboring group assistance.     

On a matroid identity

The purpose of this note is to prove an identity for generalized Tutte-Grothendieck invariants, at least two special cases of which have already proved to be of considerable use. In addition, one of these special cases is used to strengthen results of Lindström on the critical exponent of a representable matroid and the chromatic number of a regular matroid.     

Passive Microwave Remote Sensing of Soil Moisture: The Effect of Tilled Row Structure

The tilled row structure is known to be one of the important factors affecting the observations of the microwave emission from a natural surface. Measurements of this effect were carried out with both L-and X-band radiometers mounted on a mobile truck on a bare 40 m × 45 m row tilled field. The soil moisture content during the measurements ranged from ~10 to ~30 percent by dry weight. The results of these measurements showed that the variations of the antenna temperatures with incident angle ? changed with the azimuthal angle ? measured from the row direction. In particular, at ? = 0° and ? ? 45°, the observed horizontally and vertically polarized antenna temperatures, TBH(?, ?) and TBV(?, ?), were not equal. In general, TBH(?°, ?) > TBV(?°, ?) when 0° ? ? < 45° and TBH(?°, ?) < TBV(0°, ?) when 45° < ? ? 90°. The difference between TBH(0°, ?) and TBV(0°, ?) was observed to decrease with ? approaching 45° and/or with soil moisture content. A numerical calculation based on a composite surface roughness-a small-scale RMS height variations superimposed on a large periodic row structure-was made and found to predict the observed features within the model's limit of accuracy. It was concluded that the difference between TBV(0°, ?) and TBH(0°, ?) was due to the change in the local angle of field emission within the antenna field of view caused by the large-scale row structure.