Showing papers by "University of Massachusetts Amherst published in 1973"

Buyers’ Subjective Perceptions of Price:

Abstract: Marketing researchers recently have expended considerable effort to investigate how price influences buyers’ decisions yielding a variety of results, some not entirely explainable. This article rev...

A coding theorem for multiple access channels with correlated sources

Abstract: A communication system is studied in which two users communicate with one receiver over a common discrete memoryless channel. The information to be transmitted by the users may be correlated. Their information rates are described by a point in a suitably defined three-dimensional rate space. A point in this rate space is called admissible if there exist coders and decoders for the channel that permit the users to transmit information over it at the corresponding rates with arbitrarily small error probability. The closure of the set of all admissible rate points is called the capacity region, and is the natural generalization of channel capacity to this situation. In this paper we show that e, which depends only on the channel, is convex and we give formulas to determine it exactly. Several simple channels are treated in detail and their capacity regions given explicitly.

Toward an integration of theory and method for criterion-referenced tests1,2

Abstract: In this paper, an attempt has been made to synthesize some of the current thinking in the area of criterion-referenced testing as well as to provide the beginning of an integration of theory and method for such testing. Since criterion-referenced testing is viewed from a decision-theoretic point of view, approaches to reliability and validity estimation consistent with this philosophy are suggested. Also, to improve the decision-making accuracy of criterion-referenced tests, a Bayesian procedure for estimating true mastery scores has been proposed. This Bayesian procedure uses information about other members of a student's group (collateral information), but the resulting estimation is still criterion referenced rather than norm referenced in that the student is compared to a standard rather than to other students. In theory, the Bayesian procedure increases the “effective length” of the test by improving the reliability, the validity, and more importantly, the decision-making accuracy of the criterion-referenced test scores.

Trans-β-farnesene, Alarm Pheromone of the Green Peach Aphid, Myzus persicae (Sulzer)

Abstract: THE chemical structure of the repellent odour found in the cornicle secretion of the aphid M. persicae1 has been identified as trans-β-farnesene.

Hydrogenation of unsaturated polymers with diimide

Abstract: We have studied the homogeneous hydrogenation of a series of unsaturated polymeric substrates with diimide formed from the thermal decomposition of p-toluenesulfonylhydrazide (TSH) at elevated temperatures (110 to 160°C) and in aromatic solvents. At a TSH/olefin ratio of 2.0, homopolymers of butadiene, polycyclohexadiene, and polyisoprene were quantitatively hydrogenated as were two styrene/butadiene copolymers. Alkyl branching at or near the residual polymer double bond, as in methyl rubber and poly-2.5-dimethyl-2.4-hexadiene, gave less than 50% hydrogenation. Polychloroprene was not hydrogenated by diimide (conversions less than 10%) which is in agreement with the behavior previously observed for low molecular weight olefins. The unsaturated polymers which were successfully hydrogenated were soluble and, hence, showed no excessive crosslinking. Polycyclohexadiene and polyisoprene, the only samples evaluated for molecular weight changes, exhibited no chain degradation. Some qualitative kinetic data were obtained using per cent conversion vs. time data. Under the conditions of toluene reflux and TSH/olefin ratios of 1.5, the relative rates of hydrogenation for cis, trans and vinyl butadiene units was kcis ≃ ktrans < kvinyl. Byproducts from the diimide generation resulted in the introduction of 0.2 to 1.0% of p-CH3C6H4SO2-groups into the polymer based upon 100% of the double bonds originally present. Die homogene Hydrierung einer Serie ungesattigter polymerer Substrate mit Diimid, dargestellt durch Thermolyse von p-Toluolsulfonylhydrazid (THS) bei 110–160°C, wurde in aromatischen Losungsmitteln untersucht. Bei einem TSH/Olefin-Verhaltnis von 2,0 wurden sowohl die Homopolymeren des Butadiens, das Polycyclohexadien und das Polyisopren, als auch zwei Styrol/Butadien-Copolymere quantitativ hydriert. Bei Alkylverzweigung an oder in Nachbarschaft der Doppelbindung des Polymeren, wie im Poly-2.5-dimethyl-2.4-hexadien, verlief die Hydrierung zu weniger als 50%. Polychloropren wurde in Ubereinstimmung mit fruheren Beobachtungen an niedermolekularen Olefinen durch Diimid (Umsetzung weniger als 10%) nicht hydriert. Die mit Erfolg hydrierten ungesattigten Polymeren waren loslich und zeigten daher keine ubermasig hohe Vernetzung. Polycyclohexadien und Polyisopren, die auf eine Ver-anderung des Molekulargewichtes hin untersucht wurden, zeigten keinen Kettenabbau. Qualitative kinetische Daten wurden aus Umsatz (%)/Zeit-Kurven ermittelt. Beim Siedepunkt des Toluols und bei einem TSH/Olefin-Verhdtnis von 1,s resultierte fur die relativen Hydrierungsgeschwindigkeiten der cis-, trans- und Vinylbutadieneinheiten: -CH3C6H4SO2-Gruppen, die aus den Nebenprodukten der Diimid-Darstellung stammen, wurden zu 0,2–1,0 % (bezogen auf 100% der urspriinglich vorhandenen Doppelbindungen) in das Polymere eingefuhrt.

Sexual and subsexual systems in homosporous pteridophytes: a new hypothesis

Abstract: Meiosis in homosporous ferns allows chromosomes to pair within homoeologous sets rather than restricting pairing to homologs; this allows homozygous spore mother cells to give rise to genetically heterogeneous meiospores. It is envisioned that such a meiotic system has evolved in homosporous ferns in response to a life cycle which allows the attainment of total homozygosity in one generation of selfing.

Tool-making and tool-using in the northern blue jay.

Abstract: Laboratory-raised Northeirn blue jays (Cyanocitta cristata) have been observed tearing pieces from pages of newspaper and utilizing them as tools to rake in food pellets which were otherwise out of reach. The frequency of this behavior was dependenit upon the motivational state of the jay and the presence of food pellets.

Film and pore diffusion studies with immobilized glucose oxidase

Abstract: Quantitative studies are reported of external film and internal pore diffusion effects for glucose oxidase immobilized on porous glass in a continuous, tubular, packed bed reactor. The McCune and Wilhelm model for external film diffusion is shown to describe these data over a particle Reynolds number range from 0.2 to 25. The Thiele analysis provides a good description of internal pore diffusion resistances. It appears that immobilized enzymes free of internal diffusional restrictions generally require the use of supports with pore sizes larger than those currently available in porous glass.

Some transformational extensions of Montague grammar

Abstract: Richard Montague’s work on English, as represented in Montague (1970a), (1970b), (1972), represents the first systematic attempt to apply the logician’s methods of formal syntax and semantics to natural language. With few exceptions,1 linguists and logicians had previously been agreed, although for different reasons, that the apparatus developed by logicians for treating the syntax and semantics of artificially constructed formal languages, while obviously fruitful within its restricted domain, was not in any direct way applicable to the analysis of natural languages. Logicians seem to have felt that natural languages were too unsystematic, too full of vagueness and ambiguity, to be amenable to their rigorous methods, or if susceptible to formal treatment, only at great cost.2 Linguists, on the other hand, emphasize their own concern for psychological reality, and the logicians’ lack of it, in eschewing the logicians’ approach: linguists, at least those of the Chomskyan school, are searching for a characterization of the class of possible human languages, hoping to gain thereby some insight into the structure of the mind, and the formal languages constructed by logicians appear to depart radically from the structures common to actual natural languages.

Toward a Framework for the Study of Political Change in the Iberic-Latin Tradition: The Corporative Model

Abstract: IN the early 1960's a great deal of “scare” literature was produced concerning Latin America. The titles and subtitles of many of the books and articles written during the period help bear this contention out: “The Eleventh Hour,” “Reform or Revolution,” “Evolution or Chaos.” The concern of scholars and public officials, stemming principally from the Cuban revolution, was that Latin America was about to explode in violent upheaval, that unless democratic reforms were quick in forthcoming, the Latin American nations would soon be the victims of Castro-Communist takeovers. The “one-minute-to-midnight” mentality shaped not only a great deal of official thinking and policy with regard to Latin America during the 1960's, but also permeated, in varying degrees of sophistication, the large body of development literature dealing with the area.

Origin of magnetic fields in the early universe.

Abstract: Primordial turbulence in the radiation era generates a weak seed magnetic field on all scales of the turbulence. This field is stochastically amplified by turbulence motions, and it is possible for magnetic and small-scale kinetic energies to attain equipartition within an expansion time. Field generation ceases at the epoch of equal radiation and matter densities, when the field strength is of the order of 1 G. It is estimated that the present intergalactic magnetic field has an intensity of \ensuremath{\sim}${10}^{\ensuremath{-}8}$ G and a scale-length of \ensuremath{\sim}Mparsec.

Photon Correlations in the Parametric Frequency Splitting of Light

Abstract: Correlation effects in parametric photon-pair production are studied within the framework of a physically realistic model. The analysis, which is fully quantum mechanical, takes into account the finite sizes of the target and the beam cross section, and allows for dispersion and anisotropy in the linear susceptibility. The correlations in position and time at which the two members of a parametrically generated pair may be detected are carefully evaluated. These correlations, which have been measured experimentally, are intrinsically quantum mechanical; i.e., they can be explained by no theory in which the subharmonic fields are described purely by $c$-number functions. A complete solution, from which field correlation functions of arbitrarily high order may be evaluated, is obtained by a method which at the same time allows for an arbitrary degree of parametric gain. The solution is expressed entirely in terms of a particular two-point field-correlation-function, as evaluated in lowest order in the incident field strength, at points distant from the target. The function in question is found by directly examining the fluctuating currents in the material medium, rather than by eliminating the matter variables at the outset through the introduction of a nonlinear electomagnetic susceptibility.

Orchestra Interaction: Some Features of Communication and Authority in an Artistic Organization

Abstract: Combining theoretical and empirical materials, this paper outlines why definitions of the situation are an important vehicle for analyzing the conditions under which communications are viewed as authoritative by subordinates in complex work organizations. It investigates an exemplary process of collective action—making orchestra music—as a means of understanding the development as well as the demise of consensually validated expertise. Evaluations of conductors as focal participants arise from musicians' conceptions of appropriate work roles and what they construe as information and knowledge which allow them to engage in lines of concerted action. Finally, the results are discussed with regard to their implications for the study of organizational dynamics generally.

The Effects of Repetition of Refutational and Supportive Advertising Appeals

Abstract: A laboratory experiment compared the effects of repetition of refutational and supportive advertising appeals. When respondents were segmented on the basis of product class experience, several sign...

Career Concerns and Mobility Motivations of Orchestra Musicians

Abstract: This paper offers a theoretical and empirical stance towards careers and professional socialization as subjective experience. Focusing on the problematic features of mobility, entrapment, and organ...

A data definition and mapping language

Abstract: : A data definition language is a declarative computer language for specifying data structures. Most data definition languages concentrate on the declaration of logical data structures with little concern for how these structures are physically realized on a computer system. However, the need for data definition languages which describe both the logical and physical aspects of data is increasingly apparent. Such languages will be a key element in the translation of data among computer systems, as well as in advanced data management systems and distributed data bases. The paper reviews past work in the data definition language for describing both logical and physical aspects of data. Applications of these generalized data definition languages are also discussed. (Author)

Effects of Hurricane Ginger on the Barrier Islands of North Carolina

Abstract: The two barrier-island systems of North Carolina responded to the storm waves and surges of Hurricane Ginger in a strikingly different manner. Within the northern sector, which has been stabilized by man, erosion and dune recession were extensive. In the southern sector, as yet relatively unmodified, overwash and associated deposition were the dominant processes. This difference offers important geologic, ecologic, and land management implications.

Expectancy and magnitude of reaction to a noxious UCS.

Abstract: The relationship between expectancy and magnitude of reaction to a noxious UCS was examined in studies using a classical conditioning paradigm, in habituation studies, and in studies using a count-up to stimulus presentation. An initial hypothesis that accurate expectancy reduces reactivity was found inadequate, and replaced by one that stated that accurate expectancy facilitates habituation. Although this hypothesis was consistent with the data reviewed, it was concluded that it, too, requires modification. The final hypothesis proffered was that accurate expectancy facilitates habituation when it fosters appropriate modulation of attention, which, for highly threatening stimulation, consists of a degree of restriction of attention to begin with, followed by increasing attention to new elements of the stimulus complex as reactivity to old elements is reduced.

Analysis of empirical data using two logistic latent trait models

Abstract: Although Birnbaum's logistic models have been known since 1957, there have been few applications to empirical data reported in the literature. In this study, the one- and two-parameter logistic models were compared with respect to their capacity to predict the distribution of statistics for estimating ability. The results of this study suggest that the two-parameter model will provide greatest improvement over the one-parameter model when applied to data from short tests where the variability of the discrimination parameters is substantial. Whether the gains are worth the increased cost of solving for the parameters of the more complex model is a question which requires investigation.

The stability of plane Couette flow with viscous heating

Abstract: An investigation of the stability of plane Couette flow with viscous heating of a Navier–Stokes–Pourier fluid with an exponential dependence of viscosity upon temperature is presented. Using classical small perturbation theory, the stability of the flow can be described by a sixth-order set of coupled ordinary differential equations. Using Galerkin's method, these equations are reduced to an algebraic eigenvalue problem. An eigenvalue with a negative real part means that the flow is unstable.Neutral stability curves are determined at Brinkman numbers of 15, 19, 25, 30,40,80 and 600 for Prandtl numbers of 1, s and 50. A Brinkman number of 19 corresponds approximately to the maximum shear stress which can be applied to the system.The results indicate that four different modes of instability occur: one termed an inviscid mode, arising from an inflexion point in the primary flow; a viscous mode, due to the stratification of viscosity in the flow field and an associated diffusive mechanism; a coupling mode, resulting from the convective and viscous dissipation terms in the energy equation; and finally a purely thermal mode.