The effects of group expectations and self-esteem upon self-evaluation.

This study explores the effect of a specific level of achievement upon an individual's evaluations of his performance when the achievement is relative to an aspiration level set by a group and to the member's stabilized expectations about himself as represented by his self-esteem. Ss were assigned to one of 4 conditions, composed of the combinations of high and low group expectations and relevance and non-relevance of task to the purposes of the group. Half of the Ss within each experimental condition were allowed to succeed and the other half made to fail. Several specific hypotheses within this framework were tested. "The group's expectations appear to have been more potent as a scale of reference than the individual's self-esteem in determining his evaluation of his performance. When the influence of the group was weakest (task was non-relevant) persons high in self-esteem… differed in the way they evaluated their performance. When the influence of the group was strongest (task was relevant) there was no difference in the way that persons high or low in self-esteem rated their achievement." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Direct Selective Tosylation of Some Pentosides

Direct selective tosylation of benzyl α-D-xylopyranoside leads first to the 3-O-tosyl, then to the 2,3-di-O-tosyl derivative. The same procedure applied to benzyl β-D-arabinopyranoside leads first to the 2-O-tosyl then to the 2,3-di-O-tosyl derivatives. The ease of preparation and separation of these products offers a definite advantage over indirect methods that rely on the use of temporary masking groups.     

Size as a factor in the brittle-ductile transition and the strength of some materials

Attention is called to a new phenomenon: in certain materials, specimen size (or, its energy-storage capacity) influences its brittle-ductile transition and strength. This effect is not the recognized statistical one (which only concerns the nucleation of fracture), but derives from the strain-energy in the system and concerns the stability of slow-growing cracks after nucleation. Recent experimental observations, in which this effect was noted, are cited and a theory proposed to account for them. This theory is based on the fact that a highly unstable equilibrium exists between the respective rates of strain-energy release and energy demand. When the system is over-stocked with strain-energy, any sudden drop in energy demand creates an excess of energy released. This then takes the form of kinetic energy capable of doing work against the remaining resistance, in turn, resulting in a lower fracture load and reduced ductility. Specimen size enters these considerations only in so far as it governs the amount of stored energy; consequently the effect is most pronounced in flexure.Although the effect was so far observed in materials with moderate ductility, it is speculated that fine techniques might reveal its presence both ideally brittle and ideally ductile materials.

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Zusammenfassung Augenmerk wird auf ein neues Phenomen gelenkt: In gewissen Werkstoffen beeinflusst die Grosse des Prüfkörpers (oder sein Energiespeicherungsvermögen) den Uebergang vom spröden zum verformbaren Verhalten, Diese Erscheinung hat nichts mit dem bekannten statistischen Effekt zu' tun (der sich nur auf den Bruchanriss bezieht), sondern ist eine Folge der Formänderungsenergie in dem System und äussert sich in der Stabilität each dem ersten Anriss langsam fortschreitender Risse. Neuere Beobachtungen, in dessen dieser Effekt festgestellt wurde, werden angeführt und eine Theorie wird aufgestellt, die ihnen Rechnung tragen soll, Diese Theorie gründet sich auf die Tatsache, dass ein hochgradig labiles Gleichgewicht zwischen der jeweiligen Freisetzungsrate der Verformungsenergie und dem Energiebedarf besteht. Wenn das System mit Verformungsenergie überladen ist, verursacht jeder plötzliche Abfall des Energiebedarfs einen Uebersehuss freigesetzter Energie. Dieser tritt als kinetische Energie in Erscheinung, die imstande ist, sich in Ueberwindung des verbleibenden Widerstandes umzusetzen und so zu einer niedrigeren.Bruchlast and zu verringerter Verformbarkeit führt. Die Grösse des Prüfkörpers erscheint in diesen Betrachtungen nur insofern, als sie den Betrag der verfügbaren Energiespeicherung bestimmt; demgemäss zeigt sich der Effekt am stärksten bei der Biegungsbeanspruchung.Obwohl der Effekt bis jetzt nur in Werkstoffen von mässiger Verformbarkeit beobachtet wurde, wird vetmutet, dass Feinmesstechniken sein Auftreten sowohl in ideal sproden als auch in ideal verformbaren Werkstoffen nachweisen könnten.

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Résumé On attire l'attention sur un phénomène nouveau: pour certains materiaux, la dimension des éprouvettes (ou leur capacité d'accumulation d'énergie) possède une influence sur leur résistance et leurs propriétés de transition de ductilité. Cet effet ne procède pas de l'aspect statistique qui concerne la formation du premier nodule de rupture, mais est en rélation avec l'énergie de déformation dans le système, et intéresse la stabilité des fissures en cours d'extension lente après nucléation. On cite des observations expérimentales récentes, où un tel effet dimensionnel a été relevé, et l'on propose une théorie pour entenir compte.Cette théorie est basée sur le fait qu'il existe un état d'équilibre extrêmement instable entre les pour-centages respectifs d'énergie libérée et d'énergie requise pour la fissuration. Lorsque l'énergie de déformation est surabondante dans le système, toute chute soudaine de l'énergie requise se traduit par un excès brutal d'énergie libéree. Celle-ci prend la forme d'une énergie cinétrique qui est à même d'effectuer un travail vis-à-vis de la résistance offerte á la rupture, ce qui entrâine, à son tour, un abaissement de la charge de rupture et une diminution de la ductilité. La dimension de l'éprouvette n' intervient dans ce phénomène que pour autant qu' elle régisse la quantité d' energie accumulée; l'effet en est donc plus prononcé dans les essais de flexion.Malgré que l'effet dimensionnel des éprouvettes sur les propriétés de résistance á la rupture fragile n'a, jusqu' ici, été constaté que pour des matériaux de ductilité moyenne, on pense qu'un affinage des techniques expérimentales est susceptible de le révéler également dans les matériaux idéalement fragiles et idéalement ductiles.

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On leave from Douglas Aircraft Co., Inc., Missile and Space System Division, Santa Monica, California.     

Effect of one type of need complementarity on marriage partner's conformity to one another's judgments.

The hypothesis tested was that when the husband's need to receive affection (Succorance) is similar in strength to the wife's complementary need to give affection (Nurturance), the tendency of spouses to be influenced by one another will be relatively high. 55 paid volunteer couples filled out a forced-choice need questionnaire. Husbands' Succorance scores and wives' Nurturance scores were split at their medians, and couples were classified according to the 4 combinations of high and low scores. Social influence was tested on a visual discrimination task. It was found that this type of complementarity was directly related to acceptance of the spouse's judgments by husbands, but not by wives. As expected, conformity was not related to complementarity based upon husband's Nurturance and wife's Succorance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamic modeling of the fixture-workpiece system

This paper presents a methodology for dynamic modeling and simulation of a fixture-workpiece system. A simulation approach is required since standards typically do not exist for dynamic situations like machining operations. In addition, an accurate model is developed for the contact interface at each locating and clamping region on the workpiece's surface. An end milling operation is simulated to analyze the effects of various factors on workpiece accuracy and demonstrate the advantage of the simulation approach. The clamping forces required to keep the workpiece in contact with its locators are obtained, and the influences of locator placement, clamp placement, clamping forces, and clamping sequence on linear and angular errors are reported. Elastic effects of the locator-workpiece and clamp-workpiece contacts, yielding nonlinear dynamic equations of motion, are included in the model. Since system dynamics are considered, results are obtained as a function of time. The study compares well with previous experimental work by other investigators, and the method shows promise as a fixture design tool.     

Implementing a model for understanding goal-oriented discourse

This article describes the design decisions taken in implementing a processing model for understanding goal-oriented discourse. This model analyzes a restricted form of discourse known as arguments. Two main contributions are: (i) an integrated processing algorithm, which combines basic processing constraints with an interpretation of clue words–words and phrases which serve to indicate the structure of the discourse; (ii) a working version of the “evidence oracle,” which establishes connections between utterances in the discourse. This oracle determines if an “evidence” relation is intended between two utterances, and builds a model of the speaker based on the evidence relations found. This article thus emphasizes the general insights gained from the implementation exercise, both for the specification of a discourse analysis model, and for the general problem of recognizing a speaker's intentions and plans.     

Depressed index substrate tubes to eliminate leaky-mode losses in single-mode fibers

Silica tubing to be used as substrate tubes for MCVD has was demonstrated for a fiber having only one-fourth the deposited clad-merical tubing in that it is both dehydrated and fluorinated during processing to yield a silica which is dry and whose refractive index is lower than that of silica. These tubes are advantageously used to prepare single-mode fibers having fluorinated-silica cladding which controls dispersion and reduces scattering losses. In this case, the refractive index of the deposited cladding can be matched to that of the outer tube thus avoiding leaky-mode losses commonly encountered in depressed-index clad fibers. Using such an approach, low loss (0.28 dB/km at 1.55 μm) was demonstrated for a fiber having only one-fourth the deposited cladding required when a commercial silica tube is used. Such tubes could provide ecomomies to the processing of and the performance of complex cladding single-mode structures and impact multimode fiber designs.