Fracture-toughness tests and displacement and crack-stability analyses of tungsten round bend specimens

Plane-strain fracture-toughness tests were performed using the recently proposed round-bar bend test procedure with a liquid-phase sintered tungsten alloy. The tests included a direct comparison of fracture toughness from rectangular and round-bend specimens and measurements of load-line compliance using the unloading technique ofJ-integral fracture tests. Complementary displacement and crack-growth stability analyses of the round bar were performed as an extension of recent work in these two areas.Paper was presented at the 1990 SEM Spring Conference on Experimental Mechanics held in Albuquerque, NM.     

A combinatorial approach toward the discovery of non-peptide, subtype-selective somatostatin receptor ligands

The tetradecapeptide somatostatin is widely distributed throughout the body and is thought to be involved with a variety of regulatory functions. Recently, five human somatostatin receptors (hSSTR1-5) have been cloned and characterized. Several selective peptidal agonists of the hSSTR receptors are known, and we sought to apply this information to the design of novel non-peptide small molecule ligands for each receptor. Initial computational methods identified a 200 nM murine SSTR2 active compound via a database search of our sample collection. A combinatorial library was designed around the structural class of the compound with the goal of rapidly developing this initial lead into the desired subtype-selective small molecules in order to characterize the pharmacology of each of the receptor subtypes. The library was synthesized using the resin-archive, iterative deconvolution format. The total number of unique compounds in the library was expected to be 131,670, present in 79 mixtures of 1330 or 2660 compounds per mixture. Through sequences of screening and mixture deconvolution, the components of selective and highly active (Ki = 50 pM to 200 nM) non-peptide small molecule ligands for somatostatin subtypes 1, 2, 4, and 5 were identified. In addition to discovering compounds with the desired activity and selectivity, useful structure/activity information was generated which can be used in the design of new compounds and second-generation combinatorial libraries.     

结构非线性分析中求解预定荷载水平的改进弧长法

本文对目前广泛应用于结构非线性分析之中的弧长法进行改进。改进后的弧长法除保持原有优点外，能够在自动跟踪结构非线性平衡路径的同时，进一步求得位于结构平衡睡径任一区段的任意预先指定的荷载水平及相应的变形。本文的方法可以推广应用于求解预先指定的应力或位移。数值算例表明了本文方法的计算精度、效率及可靠性。     

The Group of Galois Extensions Over Orders in

In this paper we characterize all Galois extensions over where is an arbitrary -Hopf order in . We conclude that the abelian group of -Galois extensions is isomorphic to a certain quotient of units groups in . This result generalizes the classification of -Galois extensions, where , due to Roberts, and also to Hurley and Greither.

     

Book Reviews

Linear Algebra, 2nd edition by Serge Lang (1971). Addison-Wesley Publishing Company.

Linear Algebra with Applications by Hugh G. Campbell. Appleton-Century-Crofts, New York, 1971. xiii + 396 pp. + A45.An Engineering Approach to Linear Algebra, by W. W. Sawyer. Cambridge University Press, Cambridge, 1972. 304 pp. ($11.50)

An Engineering Approach to Linear Algebra, By W. W. Sawyer. Cambridge University Press, Cambridge, 1972. 304 pp. ($11.50) Sparse Matrices, by R. P. Tewarson. ($11.95)

Sparse Matrices, by R. P. Tewarson. ($11.95)     

Kohlenoxyd und Kohlendioxyd

Ohne Zusammenfassung     

EXTRARETINAL PHOTORECEPTION IN BIRDS

Abstract— It is clearly established that in birds, as in the other lower vertebrates, brain photoreception is a critically important perceptual mode. In this review, the variety of extraretinally-mediated responses has been described, and the physiological properties and anatomical location of extraretinal photoreceptors have been briefly discussed. In order to deepen our understanding of its place in the sensory armamentarium, several unresolved problems have been pointed out.