Showing papers by "University of Massachusetts Amherst published in 1977"
TL;DR: The dynamics of pattern formation is studied for lateral-inhibition type homogeneous neural fields with general connections and it is proved that there are five types of pattern dynamics.
Abstract: The dynamics of pattern formation is studied for lateral-inhibition type homogeneous neural fields with general connections. Neural fields consisting of single layer are first treated, and it is proved that there are five types of pattern dynamics. The type of the dynamics of a field depends not only on the mutual connections within the field but on the level of homogeneous stimulus given to the field. An example of the dynamics is as follows: A fixed size of localized excitation, once evoked by stimulation, can be retained in the field persistently even after the stimulation vanishes. It moves until it finds the position of the maximum of the input stimulus. Fields consisting of an excitatory and an inhibitory layer are next analyzed. In addition to stationary localized excitation, fields have such pattern dynamics as production of oscillatory waves, travelling waves, active and dual active transients, etc.
1,996 citations
TL;DR: The work-family role system as discussed by the authors is composed of the male work role, the female work role and the female family role, and the male family role may be fully actualized, or may be only partly actualized or latent.
Abstract: The study of work and the study of the family have traditionally constituted separate sub-disciplines in sociology. Rapoport and Rapoport (1965) and Kanter (1976), among others, have aptly stressed the need for greater examination of work and family roles in relation to each other. Such joint consideration is necessary to describe how individuals' functioning in either of these spheres is affected by their involvement in the other. Further, the current examination of sex roles brings added impetus to the analysis of work-family interrelationships. A major part of what is usually meant by change in "sex roles" is specifically change in the traditional allocation of work and family roles between men and women. Traditional sex role norms prescribed the specialization of work and family responsibilities by sex, but a new option for each sex to integrate roles in both work and the family is now emerging. This paper analyzes some aspects of what I term the "work-family role system." The work-family role system is composed of the male work role, the female work role, the female family role, and the male family role. Each of these roles may be fully actualized, or may be only partly actualized or latent, as is often the case with the female work role and the male family role. The analysis of these four roles as a system provides a useful way of organizing research about the relations among these roles, and suggests new relations to be examined. It also makes possible some inferences about the dynamics of future changes in women's and men's roles in work and the family. Analyzing men's and women's work and family roles as components of a role system involves specifying how each role articulates with the others to which it is linked, and how variations in the nature of each role, or whether the role is actualized at all, affects the others. For example, to describe the link between the female work and the female family roles, we consider how the extent of the female work role (ranging from no paid work at all, to the most demanding and highest status full time work) both affects and is affected by the extent of the female family role. These links can be considered at two conceptual levels. They can be analyzed at the level of the individual couple, e.g., the relation between wives' employment status and wives' role performance in the family. Each link can also be considered at the
927 citations
TL;DR: This paper shows that this program module assignment problem can be solved efficiently by making use of the well-known Ford–Fulkerson algorithm for finding maximum flows in commodity networks as modified by Edmonds and Karp, Dinic, and Karzanov.
Abstract: In a distributed computing system a modular program must have its modules assigned among the processors so as to avoid excessive interprocessor communication while taking advantage of specific efficiencies of some processors in executing some program modules. In this paper we show that this program module assignment problem can be solved efficiently by making use of the well-known Ford–Fulkerson algorithm for finding maximum flows in commodity networks as modified by Edmonds and Karp, Dinic, and Karzanov. A solution to the two-processor problem is given, and extensions to three and n-processors are considered with partial results given without a complete efficient solution.
740 citations
TL;DR: The physiological importance of stigma type is shown by the correlations that exist between the characteristics of the receptive surface and self-incompatibility system, and various taxonotnic regularities emerge.
696 citations
TL;DR: The experimental group patients demonstrated higher appointment-keeping ratios and were less satisifed with care received in the clinic on the day of their visit than were placebo patients, while the placebo group patient-provider interaction was characterized as mutually sympathetic.
Abstract: The purpose of this study was to investigate the effectiveness, dynamics, and consequences of a health education intervention designed to increase patient question asking during the patient's medical visit Data were collected at a Baltimore family and community health center which provides outpatient services to a low income, predominantly black and female population The majority of the study participants were, in addition, elderly and chronically ill A total of 294 patients and 3 providers took part in the study The study design included random assignment of patients to experimental and placebo groups with two non-equivalent (non-randomized) control groups Findings included: (1) The experimental group patients asked more direct questions and fewer indirect questions than did placebo group patients (2) The experimental group patient-provider interaction was characterized by negative affect, anxiety, and anger, while the placebo group patient-provider interaction was characterized as mutually sympathetic (3) The experimental group patients were less satisfied with care received in the clinic on the day of their visit than were placebo patients (4) The experimental group patients demonstrated higher appointment-keeping ratios (an average number of appointments kept divided by an average number of appointments made) during a four-month prospective monitoring period
648 citations
TL;DR: In this paper, the formal and physical elements of the indicated nucleation and growth criterion for melting are discussed and the existence of upper and lower limits on the melting temperature is outlined.
Abstract: The way that small particles melt is a crucial clement in the construction of a thermodynamic treatment of the relation between particle size and melting temperature. There are indications that melting is initiated at the surface and that the solid–liquid interface sweeps rapidly through the solid at the melting temperature. The formal and physical elements of the indicated nucleation and growth criterion for melting are discussed and the existence of upper and lower limits on the melting temperature is outlined. Theoretical predictions show satisfactory agreement with experimental observations.
545 citations
TL;DR: Primitive neural models of association and concept-formation are presented, which will elucidate the distributed and multiply superposed manner of retaining knowledge in the brain.
Abstract: The present paper looks for possible neural mechanism underlying such high-level brain functioning as association and concept-formation. Primitive neural models of association and concept-formation are presented, which will elucidate the distributed and multiply superposed manner of retaining knowledge in the brain. The models are subject to two rules of self-organization of synaptic weights, orthogonal and covariance learning. The convergence of self-organization is proved, and the characteristics of these learning rules are shown. The performances, especially the noise immunity, of the association net and concept-formation net are analyzed.
493 citations
TL;DR: This model of spontaneous diabetes in nonobese rats displays insulin deficiency, glucagon excess, and ketosis, with a dramatic inflammatory lesion during active β-cell destruction, in relation to the severity of the syndrome.
Abstract: A new, spontaneously diabetic syndrome has been recognized in nonobese outbred Wistar rats of both sexes. The age at detection of first glycosuria has varied from 48 to 120 days, with a mean of 67 days. Eighteen rats have been studied, 14 untreated and four during and after cessation of insulin treatment. The affected animals have demonstrated a spectrum of severity, with hyperglycemia (252-732 mg./dl.), hypoinsulinemia (0-1 ng./ml.), and hyperketonemia. The severely ketotic rats, with total blood ketone body levels between 6 and 13 mM, showed rapid loss in weight and dehydration over one to six days. The moderately ketotic (1-5 mM) declined gradually in weight over 15 days, with marked polyuria and glycosuria. The stable rats, with ketonemia less than 1 mM, sustained their weights, polyuria, and glycosuria for longer than 40 days. A relative or absolute increase in plasma immunoreactive glucagon and elevated levels of free fatty acids and branched-chain amino acids were observed in relation to the severity of the syndrome. Intraperitoneal arginine or tolbutamide elicited no insulin response, but the glucagon response to arginine was exaggerated. Pancreatic insulin content was normal or moderately decreased. Light-microscopic examination of pancreases of ketotic animals at the end stage of the disease showed islets to be very small and rare, consisting virtually of non-beta cells. In stable and earlier ketotic rats, the islets were small, with reduction in beta-cell number and a striking inflammatory cell infiltration. Surviving beta cells showed variable degranulation. This model of spontaneous diabetes in nonobese rats displays insulin deficiency, glucagon excess, and ketosis, with a dramatic inflammatory lesion during active beta-cell destruction.
433 citations
TL;DR: A new culture medium, based on the amino-acid composition of t setse hemolymph and containing fetal bovine serum, was designed for the maintenance of tsetse organs and the cultivation of various trypanosomatids.
Abstract: SYNOPSIS. A new culture medium (SM), based on the amino-acid composition of tsetse hemolymph and containing fetal bovine serum, was designed for the maintenance of tsetse organs and the cultivation of various trypanosomatids. For optimum growth 20% (v/v) serum was required. The medium supported prolonged peristalsis of the alimentary tract and salivary glands of pre-emerged Glossina morsitans morsitans. In established cultures, derived from bloodstream forms of pleomorphic Trypanosoma brucei brucei and Trypanosoma brucei rhodesiense strains, inocula of ∼ 106 procyclics/ml yielded 4–5 × 107 organisms/ml after 4 or 5 days of incubation at 28 C. Bloodstream forms of a cloned monomorphic T. b. brucei strain were also able to transform into procyclics, which, however, multiplied at a lower rate, with maximum yields of ∼ 2 × 107 after 5 days. Cultures of Trypanosoma congolense and of a nearly monomorphic Trypanosoma brucei gambiense strains could be established in SM medium only in the presence of tsetse alimentary tract. The procyclic trypomastigotes of these species, adapted to SM medium and able to grow in it without Glossina organs, gave maximum populations of ∼ 4.5 × 107 cells/ml.
Promastigotes of Leishmania donovani, cultivated routinely in a diphasic Table's medium, multiplied actively upon being transferred into SM medium, producing yields of ∼ 4 × 107 cells/ml.
422 citations
TL;DR: The authors argued that the null determiner is not to be regarded as the plural of the indefinite article a. A brief analysis is sketched in which bare plurals are treated in all instances as proper names of kinds of things.
Abstract: It is argued that the English ‘bare plural’ (an NP with plural head that lacks a determiner), in spite of its apparently diverse possibilities of interpretation, is optimally represented in the grammar as a unified phenomenon. The chief distinction to be dealt with is that between the ‘generic’ use of the bare plural (as in ‘Dogs bark’) and its existential or ‘indefinite plural’ use (as in ‘He threw oranges at Alice’). The difference between these uses is not to be accounted for by an ambiguity in the NP itself, but rather by explicating how the context of the sentence acts on the bare plural to give rise to this distinction. A brief analysis is sketched in which bare plurals are treated in all instances as proper names of kinds of things. A subsidiary argument is that the null determiner is not to be regarded as the plural of the indefinite article a.
370 citations
TL;DR: A mathematical model for the population dynamics of conjugationally transmitted plasmids in bacterial populations is presented and its properties analyzed, and a broad set of physical conditions, resource concentrations and dilution rates are predicted.
Abstract: A mathematical model for the population dynamics of conjugationally transmitted plasmids in bacterial populations is presented and its properties analyzed. Consideration is given to nonbacteriocinogenic factors that are incapable of incorporation into the chromosome of their host cells, and to bacterial populations maintained in either continuous (chemostat) or discrete (serial transfer) culture. The conditions for the establishment and maintenance of these infectious extrachromosomal elements and equilibrium frequencies of cells carrying them are presented for different values of the biological parameters: population growth functions, conjugational transfer and segregation rate constants. With these parameters in a biologically realistic range, the theory predicts a broad set of physical conditions, resource concentrations and dilution rates, where conjugationally transmitted plasmids can become established and where cells carrying them will maintain high frequencies in bacterial populations. This can occur even when plasmid-bearing cells are much less fit (i.e., have substantially lower growth rates) than cells free of these factors. The implications of these results and the reality and limitations of the model are discussed and the values of its parameters in natural populations speculated upon.
TL;DR: Pollens of certain Cruciferae produce tubes capable of penetrating the Crocus stigma cuticle, suggesting that notwithstanding the taxonomie remoteness of Crucifierae and Iridaceae the enzyme activation systems are quite similar.
TL;DR: In this paper, a revisionist analysis of the "Model Minority" Thesis is presented, with the focus on the education and the socialization of Asian Americans, and the model minority is used.
Abstract: (1977). Education and the Socialization of Asian Americans: A Revisionist Analysis of the “Model Minority” Thesis. Amerasia Journal: Vol. 4, No. 2, pp. 23-51.
TL;DR: The Libben site, a Late Woodland ossuary and occupation site from the Great Black Swamp of northern Ohio has yielded a well-preserved skeletal sample of 1327 articulated individuals, making it the largest and most comprehensively censused North American prehistoric cemetery.
Abstract: The Libben site, a Late Woodland ossuary and occupation site from the Great Black Swamp of northern Ohio has yielded a well-preserved skeletal sample of 1327 articulated individuals. The outstanding preservation and completeness of the site and the utilization of an exhaustive aging methodology make this the largest and most comprehensively censused North American prehistoric cemetery. Survivorship data indicate a robust, successful population. Life expectancy at birth was 20 years. Among adults, male mortality was consistently higher than female, a condition possibly related to high interpersonal and intergroup aggression. Infant mortality was generally low, and a general hypothesis concerning the elevation of infant mortality and the simultaneous depression of adult mortality among aboriginal peoples after European contact is suggested.
TL;DR: A theory of latent traits as discussed by the authors supposes that in testing situations, examinee performance on a test can be predicted (or explained) by defining characteristics of examinees, referred to as traits, estimating scores for examinees on these traits, and using the scores to predict or explain test performance.
Abstract: A theory of latent traits supposes that in testing situations, examinee performance on a test can be predicted (or explained) by defining characteristics of examinees, referred to as traits, estimating scores for examinees on these traits, and using the scores to predict or explain test performance (Lord and Novick, 1968). Since the traits are not directly measurable and therefore "unobservable," they are often referred to as latent traits or abilities. A latent trait model specifies a relationship between observable examinee test performance and the unobservable traits or abilities assumed to underlie performance on the test. The relationship between the "observable" and the "unobservable" quantities is described by a mathematical function. For this reason, latent trait models are mathematical models. Also, latent trait models are based on assumptions about the test data. When selecting a particular latent trait model to apply to one's test data, it is necessary to consider whether the test data satisfy the assumptions of the model. If they do not, different test models should be considered. Alternately, some psychometricians (for example, Wright, 1968) have recommended that test developers design their tests so as to satisfy the assumptions of the particular latent trait model they are interested in using. Recent work by Lord (1968, 1974a), Lord and Novick (1968), Wright (1968), Wright and Panchapakesan (1969), Samejima (1969, 1972), Bock and Wood (1971), and Whitely and Dawis (1974) has been helpful in introducing educational measurement specialists to the topic of latent trait models. Also, the work of these and other individuals has contributed substantially to the current interest among test practitioners in applying the models to a wide variety of educational and psychological testing problems. Latent trait models are now being used to "explain" examinee test performance as well as to provide a framework for solving test design problems and other important testing questions that have, to date, gone unresolved (Lord, 1977; Wright, 1977a, 1977b). Why has the use of latent trait models in practical testing situations been low? There are at least five reasons. For one, the topic of latent trait theory represents a complex branch of the field of test theory. The advanced mathematical skills required to study many of the papers published on the topic have probably discouraged many potential
TL;DR: In this paper, structural distortions of cyclic phosphoranes are shown to form a continuous series between the idealized trigonal bipyramidal (D 3h) and square pyramidal representations.
Abstract: Structural distortions of cyclic phosphoranes are shown to form a continuous series between the idealized trigonal bipyramidal (D 3h) and square pyramidal (C 4v) representations. The particular form of the distortions is along the Berry intramolecular exchange coordinate. Despite the lack of symmetry in the makeup of the cyclic substituents, a local C 2v constraint is closely followed. The origin of the mode of distortion is discussed in relation to the two sets of bond properties peculiar to five-coordinate geometries and the closeness in energy of the two idealized structures, enhanced by the presence of ring constraints. These findings reinforce the operation of successive Berry rearrangements postulated to account for NMR exchange data on a wide variety of phosphorane derivatives.
TL;DR: The coronal level of the paraventricular nucleus was revealed as the rostral focus of a longitudinal satiety neurocircuitry in hyperphagia, obesity, and excessive linear growth, but not hyperdipsia.
TL;DR: Analysis and computer simulation over a single-pole channel show that the proposed scheme can reduce the complexity of the MLSE while retaining much of its performance advantages.
Abstract: A decision-feedback equalizer (DFE) is proposed as a prefilter which limits the complexity of a maximum-likelihood sequence estimator (MLSE) implemented by the Viterbi algorithm (VA) for channels having a long impulse response. By imbedding a DFE into the structure of the MLSE, the overall impulse response of the system is truncated to a short duration. With this practical receiver, a compromise may be made between performance and complexity by properly choosing the duration of a desired impulse response. A technique is also developed to estimate the performance of the receiver numerically, taking into account the effect of incorrect decision feedback on the VA. Analysis and computer simulation over a single-pole channel show that the proposed scheme can reduce the complexity of the MLSE while retaining much of its performance advantages.
Proceedings Article•
22 Aug 1977TL;DR: Experiences gained while successfully applying the Hearsay-II architecture to the problem of speech understanding are described, and the paradigm of viewing problem solving in terms of hypothesize-and-test actions distributed among distinct representations of the problem has been shown to be computationally feasible.
Abstract: The Hearsay model has heen presented as a paradigm for attacking errorful knowledge-intensive problems requiring multiple, cooperating knowledge sources. The Hearsay-II architecture is the latest attempt to explore the model. This paper describes experiences gained while successfully applying this architecture to the problem of speech understanding. The major conclusions are: 1. The paradigm of viewing problem solving in terms of hypothesize-and-test actions distributed among distinct representations of the problem has been shown to be computationally feasible. 2. A global working memory (the "blackboard"), in which the distinct representations are integrated in a uniform manner, has made it convenient to construct and integrate the individual sources of knowledge needed for the problem solution. 3. The use of a uniform data-directed structure for controlling knowledge-source activity has made the system easy to understand and modify. 4. A solution has been demonstrated to the problem of focus-of-attention in this type of control environment. This solution does not need to be modified when the sources of knowledge in the system are changed.
TL;DR: Blue jays learned to respond differentially to the presence or absence of Catocala moths in slides, providing an objective measure of crypticity, useful for the study of visual detection of prey.
Abstract: Blue jays learned to respond differentially to the presence or absence of Catocala moths in slides. This detection of the moths by the jays was affected by the background upon which the moth was placed and its body orientation, thus providing an objective measure of crypticity. These procedures are useful for the study of visual detection of prey.
TL;DR: Near normal growth of follicles in isolated abdomens after topical application of juvenile hormone (JH) indicates that the thoracic factor is JH from the corpora allata and demonstrates the feasibility of using this system as a JH assay.
TL;DR: While the sympathetic response during marked hypoglycemia may have been initiated by alterations in cerebal metabolism, the feeding response evidently was not, and a decrease in the utilization of glucose per se does not appear to be the critical stimulus in either case.
Abstract: Intravenous infusions of manose or B-hydroxybutyrate, metabolic fuels which can be oxidized by brain, abolished adrenal discharge of epinephrine in rats during insulin-induced hypoglycemia, whereas infusion of fructose, a sugar which does not cross the blood-brain barrier, did not. In contrast, increased feeding behavior during hypoglycemia was prevented both by the sugars and by B-hydroxybutyrate. Thus, while the sympathetic response during marked hypoglycemia may have been initiated by alterations in cerebal metabolism, the feeding response evidently was not, and a decrease in the utilization of glucose per se does not appear to be the critical stimulus in either case.
TL;DR: The complexities encountered in applying segmentation techniques to color images of natural scenes involving complex textured objects are analyzed and new ways of using the techniques to overcome some of the problems are explored.
TL;DR: A variety of yeast-like fungi representing the genera Candida, Cryptococcus, Rhodotorula, Torulopsis, and Trichosporon was inhibited in vitro in the presence of an aqueous extract of garlic.
Abstract: A variety of yeast-like fungi representing the genera Candida, Cryptococcus, Rhodotorula, Torulopsis, and Trichosporon was inhibited in vitro in the presence of an aqueous extract of garlic. Fungi ...
TL;DR: For instance, this article found that women whose moods are responsive to the menstrual cycle are physically active, socially assertive, sexually orgasmic women for whom the maternal role is important.
TL;DR: Changes in food intake are neither necessary nor sufficient to cause some of the body weight changes induced by ovarian hormones, and more attention should be paid to metabolic factors when studying gonadal influences on body weight.
22 Aug 1977
TL;DR: This general focusing mechanism facilitates the experimental evaluation of a variety of specific attentional control policies and allows the modular addition of specialized heuristics for the speech understanding task.
Abstract: Using the concepts of stimulus and response frames of scheduled Knowledge source instantiations, competition among alternative responses, goals, and the desirability of a knowledge source instantiation, a general attentional control mechanism is developed. This general focusing mechanism facilitates the experimental evaluation of a variety of specific attentional control policies (such as best-first, bottom-up, and top-down search strategies) and allows the modular addition of specialized heuristics for the speech understanding task. Empirical results demonstrate the effectiveness of the focusing principles, and possible directions for future research are considered.