Showing papers by "University of Massachusetts Amherst published in 1984"

Stochastic Relaxation, Gibbs Distributions, and the Bayesian Restoration of Images

Abstract: We make an analogy between images and statistical mechanics systems. Pixel gray levels and the presence and orientation of edges are viewed as states of atoms or molecules in a lattice-like physical system. The assignment of an energy function in the physical system determines its Gibbs distribution. Because of the Gibbs distribution, Markov random field (MRF) equivalence, this assignment also determines an MRF image model. The energy function is a more convenient and natural mechanism for embodying picture attributes than are the local characteristics of the MRF. For a range of degradation mechanisms, including blurring, nonlinear deformations, and multiplicative or additive noise, the posterior distribution is an MRF with a structure akin to the image model. By the analogy, the posterior distribution defines another (imaginary) physical system. Gradual temperature reduction in the physical system isolates low energy states (``annealing''), or what is the same thing, the most probable states under the Gibbs distribution. The analogous operation under the posterior distribution yields the maximum a posteriori (MAP) estimate of the image given the degraded observations. The result is a highly parallel ``relaxation'' algorithm for MAP estimation. We establish convergence properties of the algorithm and we experiment with some simple pictures, for which good restorations are obtained at low signal-to-noise ratios.

Phonology and Syntax: The Relation between Sound and Structure

Abstract: A fundamentally new approach to the theory of phonology and its relation to syntax is developed in this book, which is the first to address the question of the relation between syntax and phonology in a systematic way.This general theory differs from its predecessors in the generative tradition in several respects. By arguing that the intonational structure of a sentence determines certain aspects of its stress pattern or rhythmic structure, and not vice versa, it provides a novel view of the intonation-stress relation. It also offers a new theory of the focus-prosody relation that solves a variety of classic puzzles and involves an appeal to the place of a focused constituent in the predicate-argument structure of the sentence. The book also includes other novel features, among them a development of the metrical grid theory of stress (including a complete treatment of English word stress in this framework), the representation of juncture in terms of "silent" positions in the metrical grid (with a treatment of sandhi in terms of this rhythmic juncture), and a "rhythmic" nonsyntactic approach to the basic phonology of function words in EnglishElisabeth 0. Selkirk is Professor of Linguistics at the University of Massachusetts, Amherst. This book is tenth in the series, Current Studies in Linguistics.

A tetrahedral modeling method for electromagnetic scattering by arbitrarily shaped inhomogeneous dielectric bodies

Abstract: A method for calculating the electromagnetic scattering from and internal field distribution of arbitrarily shaped, inhomogeneous, dielectric bodies is presented. A volume integral equation is formulated and solved by using the method of moments. Tetrahedral volume elements are used to model a scattering body in which the electrical parameters are assumed constant in each tetrahedron. Special basis functions are defined within the tetrahedral volume elements to insure that the normal electric field satisfies the correct jump condition at interfaces between different dielectric media. An approximate Galerkin testing procedure is used, with special care taken to correctly treat the derivatives in the scalar potential term. Calculated internal field distributions and scattering cross sections of dielectric spheres and rods are compared to and found in agreement with other calculations. The accuracy of the fields calculated by using the tetrahedral cell method is found to be comparable to that of cubical cell methods presently used for modeling arbitrarily shaped bodies, while the modeling flexibility is considerably greater.

Potential integrals for uniform and linear source distributions on polygonal and polyhedral domains

Abstract: Formulas for the potentials due to uniform and Linearly varying source distributions defined on simply shaped domains are systematically developed and presented. Domains considered are infinite planar strips, infinite cylinders of polygonal cross sections, planar surfaces with polygonal boundaries, and volumetric regions with polyhedral boundaries. The expressions obtained are compact in form and their application in the numerical solution of electromagnetics problems by the method of moments is illustrated.

A marketing approach for customer retention

Abstract: Consumer marketing companies have lavished more resources on attracting new customers than on satisfying old customers. In today's low growth and highly competitive marketplace, however, customer retention increasingly joins customer getting as an important area of analysis and planning. Marketers can better cultivate relationships with existing customers in these ways: designing an optimal customer portfolio, formulating a special marketing mix, and modifying the marketing organization. The balancing of marketing efforts between winning new customers and holding onto old ones will prove instrumental in pursuing sales and profit growth in the 1980s.

A class of data structures for associative searching

Abstract: By interleaving the bits of the binary representations of the attribute values in a tuple, an integer corresponding to the tuple is created. A set of these integers represents a relation. The usual ordering of these integers corresponds to an ordering of multidimensional data that allows the use of conventional file organizations, such as Btrees, in the efficient processing of multidimensional queries (e.g. range queries). The class of data structures generated by this scheme includes a type of kd tree whose balance can be efficiently maintained, a multidimensional Btree which is simpler than previously proposed generalizations, and some previously reported data structures for range searching. All of the data structures in this class also support the efficient implementation of the set operations.

Scan blindness in infinite phased arrays of printed dipoles

Abstract: A comprehensive study of infinite phased arrays of printed dipole antennas is presented, with emphasis on the scan blindness phenomenon. A rigorus and efficient moment method procedure is used to calculate the array impedance versus scan angle. Data are presented for the input reflection coefficient for various element spacings and substrate parameters. A simple theory, based on coupling from Floquet modes to surface wave modes on the substrate, is shown to predict the occurrence of scan blindness. Measurements from a waveguide simulator of a blindness condition confirm the theory.

Dynamic Task Scheduling in Hard Real-Time Distributed systems

Abstract: This algorithm for scheduling tasks with hard real-time constraints—that is, tasks that must meet their deadlines-works dynamically on loosely coupled distributed systems.

Vasopressin injected into the hypothalamus triggers a stereotypic behavior in golden hamsters

Abstract: Microinjection of arginine vasopressin into the medial preoptic area of the hypothalamus of male and female golden hamsters triggered a complex, stereotypic behavior--flank marking--a type of scent marking used in olfactory communication. The flank marking was not elicited by saline, oxytocin, neurotensin, or angiotensin II. Vasopressin was ineffective when injected into other areas of the hypothalamus or into the lateral cerebroventricle.

An analysis of the crystallization behavior of poly(ethylene oxide)/poly(methyl methacrylate) blends by spectroscopic and calorimetric techniques

Abstract: Cristallisation et changements microstructuraux du PEO dans ces melanges par spectroscopie IR et calorimetrie differentielle

Analysis of an infinite array of rectangular microstrip patches with idealized probe feeds

Abstract: A solution is presented for the problem of an infinite array of microstrip patches fed with short current elements. The input reflection coefficient is calculated versus scan angle in an arbitrary scan plane, and the effects of substrate parameters and grid spacings are considered. The scan blindness phenomenom is observed and discussed in terms of a forced surface wave response. Measurements from waveguide simulators confirm the theory for thin substrates.

Songs of the Alder Flycatcher (Empidonax alnorum) and Willow Flycatcher (Empidonax traillii) are Innate

Abstract: -I studied the song development of five Willow Flycatchers (Empidonax traillii) and four Alder Flycatchers (Empidonax alnorum) taken from nests at 7-10 days of age. Three Willow Flycatchers and four Alder Flycatchers were tutored with songs of the other species, and two Willow Flycatchers served as controls, hearing only conspecific songs. All nine subjects, both females (when administered exogenous testosterone) and males, and both experimentals and controls, produced remarkably normal songs; slight differences between songs of wild and experimental subjects could be attributed to motivational states rather than to the effects of acoustic isolation in the laboratory. I found no microgeographic variation of wild songs, no evidence of learning from a tutor tape, nor any similarity of song characters among kin. The vocal development of these suboscine flycatchers is strikingly different from that of typical oscines, where vocal learning is the rule. Received 17 January 1983, accepted 1

A word’s meaning affects the decision in lexical decision

Abstract: The influence of an isolated word’s meaning on lexical decision reaction time (RT) was demonstrated through four experiments. Subjects in two experiments made lexical decision judgments, those in a third experiment pronounced the words used in the lexical decision task, and those in a fourth experiment quickly pronounced their first associative response to the words. Differences in lexical access time for the words were measured with the pronunciation task, and differences in meaning were assessed with the association task. Multiple regression analyses of lexical decision RT were conducted using associative RT, pronunciation RT, and other target word properties (printed frequency, length, instance dominance, and number of dictionary meanings) as predictor variables. These analyses revealed a relationship between lexical decision RT and associative RT after the effects of other variables had been partialed out. In addition, word frequency continued to have a significant relationship to lexical decision RT beyond that shared with pronunciation RT and the other variables. The results of these experiments indicate that at least some of the effect of word meaning and word frequency in lexical decision is attributable to a decision stage following lexical access.

Photoperiodic Control of Body Weight and Energy Metabolism in Syrian Hamsters (Mesocricetus auratus): Role of Pineal Gland, Melatonin, Gonads, and Diet

Abstract: The effects of photoperiod and the pineal hormone melatonin on the regulation of body weight and energy metabolism were examined in Syrian hamsters, Mesocricetus auratus. Short photoperiod-housed female and male hamsters showed increases in body weight gain, feed efficiency, carcass lipid, brown adipose tissue mass, and thermogenic capacity. These effects of short photoperiods were mimicked by afternoon melatonin injections to hamsters in long-day photoperiods and were exaggerated in hamsters fed high fat diets. To determine the role of the gonads in these effects, ovariectomized hamsters were treated similarly and found to exhibit changes in body weight and energy metabolism that were 80–90% of those in gonadally intact hamsters. The role of the pineal gland in short photoperiod-induced body weight gain was examined in shampinealectomized and pinealectomized hamsters. Short photoperiod-induced increases in body weight were seen in both pinealectomized and sham-pinealectomized hamsters. Thus, pinealectomy...

Gender and parenthood.

Abstract: This chapter examines several demographic trends relevant to parenthood in individual lives and to the social ambiance surrounding childbearing and rearing in contemporary society. A good starting place for understanding change in gender and parenting roles is several demographic trends: Longevity and the sex ration, marriage and fertility, and household composition. The chapter reviews gender differences in parenting as reflected in recent research on traditional and nontraditional family arrangements and the effect of significant male investment in parenting for child outcome. It then assesses the adequacy of current explanations of gender differences in parenting and demonstrates the relevance of an expanded explanatory model that draws upon bioevolutionary theory and the neurosciences. Three types of research permit a close-up view of what it is that men do when they carry primary child-care responsibility and how they differ from the more traditional circumstance of women carrying this responsibility. They are solo fathers, men in nontraditional family circumstances, and men in intact marriages.

Task support in an office system

Abstract: The tools in current office systems are designed to carry out simple tasks that are common to most offices. For example, tasks such as communication, time management and document production are supported by the electronic mail, calendar and text editor tools. It has been pointed out that this level of task support is only of limited effectiveness in addressing the problem of office productivity [HAMM79,HAMM80]. A more effective system would support higher-level tasks that are directly related to the goals or functions of the office. This type of task often involves decision-making, complex sequences of actions, and interaction with a number of other people. The crucial feature of these tasks is that, unlike the simple tasks mentioned previously, tasks that more closely implement a particular office's functions must be very office-specific. It will not be possible to provide a generic set of tools to directly support all office tasks. However, it should be possible to “customize” an office system by providing a means of describing the high-level tasks and how they can be supported with the existing set of tools.Descriptions of office tasks are usually called office procedures. Although the name implies that the activities described are very routine and structured, office procedures can also be used to describe more unstructured, management-level tasks. Office procedure formalisms have been used to define and analyse offices [ELLI80,BAIL83], and to automate office tasks [ZISM77]. A description of a task using a procedure formalism is subject to change and represents only a standard or typical way of carrying out that task. A system that uses office procedures to support tasks must provide mechanisms to deal with these limitations of procedures [FIKE80].

Bayes Smoothing Algorithms for Segmentation of Binary Images Modeled by Markov Random Fields

Abstract: A new image segmentation algorithm is presented, based on recursive Bayes smoothing of images modeled by Markov random fields and corrupted by independent additive noise. The Bayes smoothing algorithm yields the a posteriori distribution of the scene value at each pixel, given the total noisy image, in a recursive way. The a posteriori distribution together with a criterion of optimality then determine a Bayes estimate of the scene. The algorithm presented is an extension of a 1-D Bayes smoothing algorithm to 2-D and it gives the optimum Bayes estimate for the scene value at each pixel. Computational concerns in 2-D, however, necessitate certain simplifying assumptions on the model and approximations on the implementation of the algorithm. In particular, the scene (noiseless image) is modeled as a Markov mesh random field, a special class of Markov random fields, and the Bayes smoothing algorithm is applied on overlapping strips (horizontal/vertical) of the image consisting of several rows (columns). It is assumed that the signal (scene values) vector sequence along the strip is a vector Markov chain. Since signal correlation in one of the dimensions is not fully used along the edges of the strip, estimates are generated only along the middle sections of the strips. The overlapping strips are chosen such that the union of the middle sections of the strips gives the whole image. The Bayes smoothing algorithm presented here is valid for scene random fields consisting of multilevel (discrete) or continuous random variables.

Fault-related rocks: Suggestions for terminology

Abstract: Many traditional terms for fault-related rocks have undergone recent dynamic metamorphism under high-pressure discussions by various groups of specialists. A generally acceptable simplified framework encompassing these and associated structural terms is now needed for many geologic, engineering, and legal purposes. Such a framework is proposed here, focusing on a rate-of-strain versus rate-of-recovery diagram and relating this framework to the products of brittle and ductile deformation along faults.

Liquid crystal polymers with flexible spacers in the main chain

Abstract: This review is be concerned primarily with the synthesis and properties of such polymers which show thermotropic behaviour.

Physics and the ‘marginalist revolution’

Abstract: Interest in the origins of neoclassical theory has a number of motivations. The first is antiquarian: it is concerned with tracing the intellectual antecedents of a given inno vation. The second is epistemological: the methods of great discoverers are held to pro vide an exemplar for currently accepted methods of research. The third is ontological: the occurrence of independent simultaneous discovery is used to suggest the substan tiality and reality of the phenomenon identified. William Stanley Jevons, for instance, wrote that, 'The theory in question has in fact been independently discovered three or four times over and must be true' (Jevons, 1972, IV, p. 278). The fourth is practical: it provides a reservoir of metaphors and theoretical suggestions which might serve to prompt novel contemporary lines of inquiry which are obscured or slighted by modern theory. Confusion or doubt over the origins of modern neoclassical economic theory would introduce the possibility of serious historical, epistemological, ontological and practical confusions in its exposition. At present, the most popular textbook of the history of economic thought attempts to dispose of the issue by absolving itself of any responsibility for discussing origins:

The hazards of fine-needle aspiration biopsy

Abstract: Review of the literature and the results of the hospital survey substantiate the widely held belief that fine-needle aspiration biopsy is a very safe procedure. However, serious and even fatal complications, although rare, can and do occur and it is important to be aware of the possibility and to take all the appropriate precautions in order to reduce their incidence.