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In carrying out aeroelastic structural optimization analyses, the use of fixed vibration mode shapes may prove unsatisfactory since variations in mass and stiffness distributions result in changing modes. A method of structural optimization is presented in which the aeroelastic structural modal shapes are represented as functions of mass distribution, structural stiffness, and aerodynamic forces. The optimality condition is the minimum weight, which satisfies given structural strength constraints and precludes the onset of flutter over the airplane speed-altitude domain. Modern finite element and displacement mthods are used to describe the aeroelastic equations of motion in matrix form. Aerodynamic forces are given in quasi-static lift distribution vs displacement matrix form, and modal shapes are the solution of a matrix eigenvalue problem. The onset of flutter is that point at which diagonalization proves unattainable.

Workers' evaluative attitudes toward the four-day-week work schedule reflect their desires for increased leisure and perceptions of the effect of the four-forty schedule upon leisure. Personal and family characteristics, job characteristics, and job satisfaction are unrelated to attitudes toward the four-forty schedule. Favorable attitudes toward the fourday week are expressed by workers who view leisure in a days-per-week context and unfavorable attitudes are expressed by workers who view leisure in an hours-per-day context.

Moment inequalities analogous to Khintchine’s inequality (for sums of independent Bernoulli random variables) are obtained for a certain class of random variables which naturally arises in the context of ferromagnetic Ising models and φ4 Euclidean (quantum) field models in a positive external field. These results extend ones obtained previously which applied only to the mean zero (vanishing external field) case.

We prove a number of asymptotic results in theP(φ)2 theory in the limit when the space cut-offs are removed, in particular the behavior ofEl andZt,l ast,l→∞. Such results are used to study the question of orthogonality of infinite volume Euclidean measuresμ∞(λ) for varying interaction constants λ.

A series of inequalities for partition, correlation, and Ursell functions are derived as consequences of the Lee-Yang Theorem. In particular, then-point Schwinger functions ofeven φ4 models are bounded in terms of the 2-point function as strongly as is the case for Gaussian fields; this strengthens recent results of Glimm and Jaffe and shows that renormalizability of the 2-point function by fourth degree counter-terms implies existence of a φ4 field theory with a moment generating function which is entire of exponential order at most two. It is also noted that ifany (even) truncated Schwinger function vanishes identically, the resulting field theory is a generalized free field.

It is shown that aD-component Euclidean quantum field, ϕ=(ϕ1,...,ϕD), with λ|ϕ|4+β|ϕ2| interaction, can be obtained as a limit of (ferromagnetic) classical rotator models; this extends a result of Simon and Griffiths from the caseD=1. For these Euclidean field models, it is then shown that a Lee-Yang theorem applies forD=2 or 3 and that Griffiths' second inequality is valid forD=2; a complete proof is included of a Lee-Yang theorem for plane rotator and classical Heisenberg models. As an application of Griffiths' second inequality forD=2, an interesting relation between the “parallel” and “transverse” two-point correlations is obtained.

A new synthesis for carboranesiloxane polymers has been discovered. It involves the alcoholysis of the bis-chlorodimethylsilyl carborane monomers and the generation of the HCl catalyst in situ. Alcoholysis is applicable to the synthesis of most carboranesiloxane polymers with the exception of the SiB-1 homopolymers of the larger carboranes. The attack of the B-H moieties in the carborane cage can be minimized by the utilization of a tertiary alcohol or by the addition of excess acid when a primary alcohol is employed. (Author)

The principal result is that if G is any irreducible subgroup of GL(n, C) (C the complex field) such that |tr(7^)| is uniformly bounded for all A in G and some fixed n × n nonzero matrix T, then G is equivalent to a unitary group. Similar results are proved for certain associated representations of G.

The paper considers the possibility of constructing ultralocal theories, whose Hamiltonians contain no gradient terms and are therefore diagonal in position space, entirely in terms of currents with an equal time current algebra replacing the canonical commutation relations. It is shown that the free current theory can be defined in terms of a certain representation of the current algebra related to the group,S L(2,R). This representation is then constructed by using certain results of Araki and in the process a new infinitely divisible state on the universal covering group ofSL(2,R) is displayed. An ultralocal free theory can also be constructed for the canonical fields, and its relation to the free current theory is shown to involve a certain renormalization procedure reminiscent of the thermodynamic limit.

QUICK determinations of crest surge potential values by a simple direct method are often desirable in the laboratory to supplement the cathode-ray oscillograph which records the entire surge phenomenon. The generally used sphere-gap method of potential measurement has, however, the disadvantages that a number of tests must be made in the process of adjusting for the breakdown distance, and sometimes the effect of time lag1,2 of breakdown must be considered. In particular, it has been found in routine laboratory surge testing in connection with insulation co-ordination that sphere-gap measurements are erroneous for short duration potentials even with irradiation3 of the gap when making tests of breakdown on the front of a sharply rising potential wave. Also on such chopped waves it is rather unlikely that the sphere-gap setting would be very close to the breakdown value and accordingly a large number of tests have to be made. It is at times essential that the actual breakdown voltage be recorded in a single test since some test objects can be broken down only once.

Unmodified 5-SiB-1 polymers have been found to be at least equivalent to their 10-SiB-1 counter-parts with respect to thermal stability. The 5-SiB-1 polymers, moreover, are substantially more amenable to conversion into elastomers. The introduction of 15 to 20 mole per cent of m-C2B10 into the 5-SiB-1 backbone results in elastomers whose thermal stability, although less than that of the parent homopolymer is, nevertheless, substantially in excess of the published values for other carboranesiloxane polymers. The crystallization of the 5-SiB-1 copolymer containing 15 mole per cent C2B10 was inhibited by irradiation with 50 megarads of 3 mev betas. The 5-SiB-1 copolymer containing 20 mole per cent C2B10 on the other hand, remained a rubber at room temperature. (Author)

If the submission of yet another study of this monumental work should stand in need of some apology, I must plead the encouragement offered by a remark entered against a famous name in the visitors' book of those who have been before me. “There is something from which one may take a lesson.” I shall hope to show in this paper that that was far truer than Mozart can have dreamed.

Let A be an n X n non-negative matrix, that is, a matrix whose entries are non-negative numbers. The permanent of A is the scalarvalued function of A defined bywhere the summation extends over all permutations i1 … , in of the integers 1, … , n. The purpose of this paper is to prove several inequalities involving the permanent of A and the permanent of submatrices of A when suitable restrictions are placed on the row sums.

This program was written to show how a computerdriven display could be used as an input/output device when designing with modular building units. I t was written for the PDP-7 computer at the Cambridge University Mathematical Laboratory, which is equipped with a Type 340 Display and Light Pen (see Fig. 1). The user of the program can add wall units, windows, doors, etc., to his design by typing the appropriate request on a teleprinter. A picture of the unit then appears on the screen wherever the light pen is pointing, and can be moved about the screen until it is in its correct position. The user can then insert the unit permanently in the design, and the program auto­ matically aligns the unit with the modular grid. By means of the light pen, units can be erased, duplicated or moved to new positions. The designs are stored in the computer in a form which enables them to be compactly recorded on punched tape, and which allows the program to perform numerical processing on the design, including calculating areas. In the first part of this paper the operating techniques and general capabilities of the program are outlined, and the second part describes some of the programming methods adopted.

THE time lag of electrical breakdown of various air gaps and solid insulations is of particular importance in co-ordination1 of insulation for transient lightning surges. Generally, time lag of breakdown is in part a function of chance ionization conditions in the breakdown path and therefore the measurements become often of a statistical nature.2 Thus, where a large number of measurements are to be made, a direct method giving immediate readings free from the delays of photographic development would be a valuable auxiliary to cathode-ray oscillography.

The metabolism of Rickettsia tsutsugamushi (Gilliam strain) multiplying in irradiated L cells was investigated by methods involving the use of 14 C-labeled substrates and cycloheximide, an inhibitor of eukaryotic metabolism. Cycloheximide-resistant amino acid and adenine incorporations were appreciably higher in infected than in uninfected cultures during the period from 3 to 5 or 6 days postinoculation. The metabolism of R. rickettsi was similarly studied in primary duck embryo cells, which are more susceptible to infection with this rickettsia than are L cells. A difference in cycloheximide-resistant activity between infected and uninfected cultures was also noted, but was small. This finding is attributed to the more limited growth of R. rickettsi.

A special artificial-lightning generator has been developed through the University of Minnesota co-operation with the Naval Research Laboratory, to provide accurate laboratory duplication of thunderstorm-cloud field conditions. Conditions of electrical-field stress before the lightning discharge are produced by an automatically controlled transition of a generator of high-voltage direct current into a surge generator, resulting in a doubled field stress and a surge breakdown with lightning current characteristics. The combination is thus very suitable for studying certain phases of aircraft operation, particularly communications, under controlled laboratory conditions, corresponding to flight under electrical-storm conditions.

Carotid angiography (1) has become an established and increasingly popular procedure in neuroradiology. For diagnostic purposes, most of the emphasis has been placed on changes in the arterial phases. This paper is presented to emphasize the importance of changes in the deep veins of the brain. With serial filming, the deep veins are regularly visualized from four to six seconds after injection. If films are taken at one-second intervals, the deep veins are usually seen in two successive frames. Our present procedure is to take seven films in eight seconds, since the intracranial circulation may be slow in the presence of increased intracranial pressure. Normal Anatomy The normal anatomy of the pertinent deep veins is represented in Figures 1–4. No attempt to describe it in detail will be made. Several venous tributaries seen only occasionally are not illustrated. These include: (1) a posterior epithalamic vein which appears to arise near the pulvinar and joins the internal cerebral vein a short distance ...

Interference blankers have been developed to give improvement ratios of the order of 1000 in the presence of severe precipitation static of the order of 150,000 pulses per second. Recently the blanking technique has been applied to ADF receivers with the objectives of simplification, reduced size and weight, improved sensitivity in the presence of interference, reduced intermodulation distortion, maintenance of the relative phases of the sense and loop signals, and general compatibility with ADF receiver operation.

Natural frequencies and mode shapes of pressurized circular cylinders with flexible stringers and attached point-mass

The inability to predict the point of strike of natural lightning flashes to ground makes it very difficult to carry out repeated measurements under reasonably reproducible conditions. This difficulty has been overcome to some extent by measurements on discharges to high buildings, radio towers, power lines, and other fixed structures. During the last several years we have experimented with long wires carried aloft by rockets to induce strokes from overhead thunder-clouds. These strokes will be referred to as triggered lightning strokes. Early experiments with the schooner Azara [Newman, 1958, 1965] have been continued with our research vessel R. V. Thunderbolt in the vicinity of St. Petersburg, Florida. During August 1966, of 23 attempts 17 cloud-vessel lightning flashes were successfully triggered.