Showing papers by "Stony Brook University published in 1978"

Threshold models of collective behavior.

Abstract: Models of collective behavior are developed for situations where actors have two alternatives and the costs and/or benefits of each depend on how many other actors choose which alternative. The key...

Spatial autocorrelation in biology: 1. Methodology

Abstract: Spatial autocorrelation analysis tests whether the observed value of a nominal, ordinal, or interval variable at one locality is independent of values of the variable at neighbouring localities. The computation of autocorrelation coefficients for nominal, ordinal, and for interval data is illustrated, together with appropriate significance tests. The method is extended to include the computation of correlograms for spatial autocorrelation. These show the autocorrelation coefficient as a function of distance between pairs of localities being considered, and summarize the patterns of geographic variation exhibited by the response surface of any given variable. Autocorrelation analysis is applied to microgeographic variation of allozyme frequencies in the snail Helix aspersa. Differences in variational patterns in two city blocks are interpreted. The inferences that can be drawn from correlograms are discussed and illustrated with the aid of some artificially generated patterns. Computational formulae, expected values and standard errors are furnished in two appendices.

Spatial autocorrelation in biology: 2. Some biological implications and four applications of evolutionary and ecological interest

Abstract: Spatial autocorrelation analysis tests whether the observed value of a variable at one locality is significantly dependent on values of the variable at neighbouring localities. The method was extended by us in an earlier paper to include the computation of correlograms for spatial autocorrelation. These show the autocorrelation coefficient as a function of distance between pairs of localities, and summarize the patterns of geographic variation exhibited by the response surface of any given variable. Identical variation patterns lead to identical correlograms, but different patterns may or may not yield different correlograms. Similarity in the correlograms of different variation patterns suggests similarity in the generating mechanism of the pattern. The inferences that can be drawn from correlograms are discussed and illustrated. Examination and analysis of variation patterns of several characters or gene frequencies for one population, or of several populations in different places or at different times, permit some conclusions about the nature of the populational processes generating the observed patterns. Autocorrelation analysis is applied to four biological situations differing in the nature of the data (interval or nominal), in the type of grid connecting the localities (regular or irregular), and the field of application (evolution or ecology). The examples comprise genotypes of individual mice, blood group frequencies in humans, gene frequency variation in a perennial herb, and the distribution of species of trees. The implications of our findings are discussed.

Introduction to system sensitivity theory

Abstract: The author stresses that this book is written at a basic introductory level: accordingly, the book neither contains a rigorous treatment of the covered theory, nor is the covered theory chosen at a level other than the fundamental concepts of sensitivity theory. It is the reviewer's opinion that the author has accomplished his aims: thus he has written an introductory textbook on sensitivity theory which both covers the fundamentals of the theory and provides a guided entry to more advanced theory and to research. Indeed, it is the reviewer's personal experience [2] that the existence of this textbook, enfolding a unified set of definitions and a unified set of terminologies, can both facilitate subsequent research in sensitivity and enable it to be conducted in a smoother less disjointed way than in the past. Relative to the importance of sensitivity theory, it is to be recalled that in system identification, and therefore in the control domain, there exists

Brownian dynamics as smart Monte Carlo simulation

Abstract: A new Monte Carlo simulation procedure is developed which is expected to produce more rapid convergence than the standard Metropolis method. The trial particle moves are chosen in accord with a Brownian dynamics algorithm rather than at random. For two model systems, a string of point masses joined by harmonic springs and a cluster of charged soft spheres, the new procedure is compared to the standard one and shown to manifest a more rapid convergence rate for some important energetic and structural properties.

The Philosophical Arguments

Abstract: There is a serious difficulty in identifying which individuals belong to the class of the mentally retarded. However, under cetain circumstances, it would seem morally permissible to sterilize some mildly retarded people without their consent. Involuntary sterilization might be in the best interest of the people who, while capable of engaging in and enjoying sex, would not be able to bear the physiological and psychological stresses connected with pregnancy, delivery and child raising. These people have great difficulty in managing nonpermanent forms of contraception, therefore sterilization could be the only responsible contraceptive choice. Also, involuntary sterilization in the right cases would foster, rather than deny, the membership of the mildly mentally retarded in the moral community, and enhance the dignity of their position. Policies regarding these positions should come from the political process.

Course characteristics and college students' ratings of their teachers: What we know and what we don't

Abstract: From showing in a general way that there is “room” for course context to influence class (average) ratings of instruction, this review proceeds to a search for specific course characteristics that are associated with these ratings. Extant research has centered around five such characteristics: class size, course level, the “electivity” of the course, the particular subject matter of the course, and the time of day that the course is held. Although statistically significant zero-order relationships do not appear in every piece of research located for review, such relationships are more likely to be found than not for the first four of these characteristics. The associations may not be particularly strong, but rather clear-cut patterns do emerge. Of the studies reporting an association between size of class and class ratings, most find it to be inverse, although several studies show a curvilinear (U-shaped) relationship. Teacher (and course) ratings tend to be somewhat higher for upper division courses and elective courses. Compared to other instructors, those teaching humanities, fine arts, and languages tend to receive somewhat higher ratings. The possible reasons for these relationships are many and complex. A precise understanding of the contribution of course characteristics to the ratings of teachers (and the courses themselves) is hampered by two circumstances. Studies in which relevant variables are controlled are far fewer in number than are the studies in which only the zero-order relationships between course characteristics and ratings are considered. More importantly, existing multivariate studies tend to underplay or ignore the exact place of course characteristics in a causal network of variables.

Sexual identity of 37 children raised by homosexual or transsexual parents.

Abstract: The author reports on 37 children who are being raised by female homosexuals or by parents who have changed sex (transsexuals): 21 by female homosexuals, 7 by male-to-female transsexuals, and 9 by female-to-male transsexuals. The children range in age from 3 to 20 years (mean = 9.3) and have lived in the sexually atypical households for 1-16 years (mean = 4.9). Thirty-six of the children report or recall childhood toy, game, clothing, and peer group preferences that are typical for their sex. The 13 older children who report erotic fantasies or overt sexual behaviors are all heterosexually oriented.

Properties of Conformal Supergravity

Abstract: We complete our program of constructing the gauge theory of the superconformal group, and show that the previously proposed action is completely invariant under both local supersymmetries. The gauge algebra closes off-shell as well as on-shell. A flat-space model with a local supersymmetry is also presented.

Interdiffusion and intrinsic diffusion in the Ni AI (δ) phase of the Al-Ni system

Abstract: Interdiffusion coefficients at 950 to 1150°C and the ratio of intrinsic diffusion coefficients at 1100°C were measured as functions of composition in the NiAl (δ) phase of the Al-Ni system, using a vapor-solid technique. Diffusivity values were also obtained for the Ni3Al (∈)and Ni (Al) solid solution (ζ) phases from 950 to 1150°C. The interdiffusion coefficient in NiAl (δ) varies several orders of magnitude over the δ phase field with a deep minimum in the diffusivity-composition curve at 48 to 49 at. pct Al. The ratio of intrinsic diffusion coefficients, Dni/DaI, in the δ phase also varies with composition from a value of 3 to 3.5 below 50 at. pct Al to 0.1 or less above 50 at. pct Al.

Acquisition of sign language by autistic children. i: expressive labelling

Abstract: There has been growing interest in teaching sign language to autistic children who have failed to develop speech. However, controlled experimentation in this area is nonexistent. In the present study, four nonverbal autistic children were taught expressive sign labels for common objects, using a training procedure that consisted of prompting, fading, and stimulus rotation. The efficacy of the procedure was demonstrated in a multiple-baseline design across objects. The results were reliable, replicable across children, and generalizable across therapists. A stimulus control analysis demonstrated that, for three of the children, correct signing was controlled solely by the visual cues associated with the presentation of a given object and was independent of respect to the known perceptual and linguistic deficits of autistic children.

A molar theory of reinforcement schedules.

Abstract: Behavior of subjects exposed to concurrent and individual interval and ratio schedules of reinforcement may be described in terms of a set of expressions relating the value of responses to their durations, a feedback equation relating reinforcement to response duration, and the assumption that subjects allocate their time among various responses so as to maximize value.

Transient creep and semibrittle behavior of crystalline rocks

Abstract: We review transient creep and semibrittle behavior of crystalline solids. The results are expected to be pertinent to crystalline rocks undergoing deformation in the depth range 5 to 20 km, corresponding to depths of focus of many major earthquakes. Transient creep data for crystalline rocks at elevated temperatures are analyzed but are poorly understood because of lack of information on the deformation processes which, at low to moderate pressure, are likely to be semibrittle in nature. Activation energies for transient creep at high effective confining pressure are much higher than those found for atmospheric pressure tests in which thermally-activated microfracturing probably dominates the creep rate. Empirical transient creep equations are extrapolated at 200° to 600°C, stresses from 0.1 to 1.0 kbar, to times ranging from 3.17 × 102 to 3.17 × 108 years. At the higher temperatures, appreciable transient creep strains may take place but the physical significance of the results is in question because the flow mechanisms have not been determined. The purpose of this paper is to stimulate careful research on this important topic.

Mass divergences in annihilation processes. I. Origin and nature of divergences in cut vacuum polarization diagrams

Abstract: The origin of mass divergences in internal loop momentum integrals of cut vacuum polarization diagrams is investigated. It is found that loop momentum configurations which can give rise to mass divergences are of a severely limited form and have a direct interpretation in terms of physically realizable processes. A power-counting procedure suitable for estimating the nature of mass divergences is developed, and it is found that in a large class of field theories, cross sections smeared over a small region of phase space are at worst logarithmically divergent.

Ethnicity and patterns of help-seeking.

Abstract: This study reconstructs and analyzes pathways of help-seeking traveled by severely disabled mental patients in the community. Ethnicity is a prime factor in differentiating patterns of help-seeking in that Chinese patients are kept for prolonged periods of time within their families in the beginning of pathways, while Anglo-Saxons and Middle Europeans are referred by their families or themselves to multiple social and mental health agencies. Native Indians are referred by persons other than family members or themselves between social and legal agencies in the community. Eventually all of these pathways lead to psychiatric inpatient intervention. There are major impediments to treatment in these patterns, most notably isolation and deterioration of patients within confines of families or lack of coordination of agencies in the community. Recommendations aimed at the improvement of treatment in the community are presented in light of these findings.

Jet and Lepton Pair Production in High-Energy Lepton-Hadron and Hadron-Hadron Scattering

Abstract: Cross sections for jet and lepton-pair production at large transverse momenta are studied in a class of renormalizable field theories including quantum chromodynamics. To all orders in perturbation theory, appropriate moments are seen to factorize short-distance from long-distance dependence in leptoproduction. Scale breaking is governed by the anomalous dimensions of twist-two operators. These results are extended to hadron-hadron scattering for theories where infrared divergences cancel in the sum over soft particle emissions, even in the limit that all particle masses vanish. This cancellation is explicitly demonstrated for totally massless QED.

Anomalies in the Earth’s Magnetic Field Increase the Scatter of Pigeons’ Vanishing Bearings

Abstract: Homing pigeons were released under sunny conditions at places with large variations in the total intensity of the Earth’s magnetic field. At five out of six such places, pigeons were more scattered in their homeward orientation than at magnetically normal sites. This suggests that some aspect of the magnetic field affects either the pigeon’s sun compass or its navigational system.

Breast cancer and acute leukemia: report of 24 cases and review of the literature.

Abstract: Twenty-four cases of breast cancer and acute leukemia and three cases of breast cancer and chronic myelocytic leukemia are reported. An additional 54 cases of acute leukemia and 13 cases of chronic myelocytic leukemia associated with breast cancer from the literature are reviewed. The mean interval between the diagnosis of breast cancer and the occurrence of acute leukemia is 6.9 years. In eight patients, the two diseases occurred simultaneously or within one year of each other. Four patients had acute lymphoblastic leukemia; the remainder had acute myelocytic leukemia or one of its variants. Seven patients received no postmastectomy radiotherapy or chemotherapy and the occurrence of acute leukemia between 1 and 23 years later cannot, therefore, be attributed to the therapy given for the breast cancer. Forty-one patients received postoperative radiotherapy to the mastectomy site. Combination chemotherapy was administered to eight patients, five of whom were also treated with radiotherapy. Acute leukemia is estimated to occur in patients treated for breast cancer with a sevenfold increased frequency over the expected number. This may be due to an increased risk of a second neoplasm in patients with a primary tumor; alternatively, the acute leukemia may be related to the radiotherapy and/or chemotherapy administered to treat the breast cancer. Late death from leukemia after chemotherapeutic or radiotherapeutic remission of metastatic breast cancer is preferable to morbidity and/or early death from inadequately treated breast cancer.

Seasonal and environmental variations in sediment accretion in a Long Island salt marsh

Abstract: Flax Pond is a small (0.5 km2) salt marsh on the north shore of Long Island, New York. Two 1 m2 plots within each of the following environments were covered with a marker layer of either brick dust or aluminum glitter: 1) bare mud flats; 2) areas newly colonized by Spartina alterniflora; and 3) high intertidal. S. alterniflora peat surfaces. Monthly cores revealed the amount of sediment that accumulated since placement of the marker. Accretion rates from October, 1974 to February, 1976 were as follows: bare mud flats −20.5 to 45.5 mm/yr; recently vegetated mud flats −9.5 to 37.0 mm/yr; and high intertidal peat surfaces −2.0 to 4.25 mm/yr. Sedimentation rates decrease with increasing elevation because of the reduced tidal submergence time and decreased height of the overlying water column. In areas of low elevation, ice and storms cause either erosion or a reduced rate of accretion during the winter months. The average mud accretion rate over the past 173 years is 3.4 mm/yr. Differences between the short-term rate and the long-term rate indicate substantial annual variation in the accumulation of mud in salt marshes. Short-term rates of peat accretion are similar to long-term estimates, indicating that rates of peat accretion are relatively constant over long intervals.