Showing papers by "Yale University published in 1986"

Performance-oriented assessment of mobility problems in elderly patients

Abstract: M any people experience a decline in mobility with aging. The multiple chronic diseases and disabilities responsible for this decline also may predispose to falling. This decline is well recognized by clinicians caring for elderly patients. The Canadian Task Force on the Periodic Health Examination not only recognized the problem, but concluded that assessing physical, social, and psychologic functions as they impact on “Progressive Incapacity with Aging” was the most important assessment for patients over age 75.’ Prominent among their list of potentially preventable impairments were locomotory, sensory, and cognitive functions, each of which is intricately related to mobility. The Canadian Task Force further stated that protection of abilities should be emphasized over diagnosis. They believed that establishing the optimal content of the assessment was a high research priority. The purpose of the following discussion is to address the question of content of a functional mobility assessment appropriate for elderly patients. The limitations of relying solely on either a disease-oriented or a gait analytic approach are outlined. A practical performance-oriented assessment of mobility is described that incorporates useful features of both approaches. The recommended evaluation centers on the more effective use of readily (and frequently) obtained clinical data. Although limited to a discussion of ambulation as the expected mode of mobility (necessary because of space limitations), many of the concepts apply to other modes as well (eg, wheelchair).

Cointegration and Tests of Present Value Models

Abstract: In a model where a variable Y[sub t] is proportional to the present value, with constant discount rate, of expected future values of a variable y[sub t] the "spread" S[sub t]= Y[sub t] - [theta sub t] will be stationary for some [theta] whether or not y[sub t]must be differenced to induce stationarity. Thus, Y[sub t] and y[sub t] are cointegrated. The model implies that S[sub t] is proportional to the optimal forecast of [delta Y{sub t+1}] and also to the optimal forecast of S*[sub t], the present value of future [delta y{sub t}]. We use vector autoregressive methods, and recent literature on cointegrated processes, to test the model. When Y[sub t] is the long-term interest rate and y[sub t] the short-term interest rate, we find in postwar U.S. data that S[sub t] behaves much like an optimal forecast of S*[sub t] even though as earlier research has shown it is negatively correlated with [delta Y{sub t+1}]. When Y[sub t] is a real stock price index and y[sub t] the corresponding real dividend, using annual U.S. data for 1871-1986 we obtain less encouraging results for the model, al-though the results are sensitive to the assumed discount rate.

A triangular theory of love.

Abstract: This article presents a triangular theory of love According to the theory, love has three components: (a) intimacy, which encompasses the feelings of closeness, connectedness, and bondedness one experiences in loving relationships; (b) passion, which encompasses the drives that lead to romance, physical attraction, and sexual consummation; and (c) decision/commitment, which encompasses, in the short term, the decision that one loves another, and in the long term, the commitment to maintain that love The amount of love one experiences depends on the absolute strength of these three components, and the kind of love one experiences depends on their strengths relative to each other The three components interact with each other and with the actions that they produce and that produce them so as to form a number of different kinds of loving experiences The triangular theory of love subsumes certain other theories and can account for a number of empirical findings in the research literature, as well as for a number of experiences with which many are familiar firsthand It is proposed that the triangular theory provides a rather comprehensive basis for understanding many aspects of the love that underlies close relationships What does it mean "to love" someone? Does it always mean the same thing, and if not, in what ways do loves differ from each other? Why do certain loves seem to last, whereas others disappear almost as quickly as they are formed? This article seeks to answer these and other questions through a triangular theory of love This tripartite theory deals both with the nature of love and with loves in various kinds of relationships The presentation of the theory will be divided into three main parts In the first part, the main tenets of the theory will be explained and discussed, and the theory will be compared with other theories of love In the second part, the implications of the theory for close relationships and satisfaction in them will be described In the third part, the theory will be shown to account for many of the empirical phenomena that have been observed with regard to love

NMDA-receptor activation increases cytoplasmic calcium concentration in cultured spinal cord neurones

Abstract: Excitatory amino acids act via receptor subtypes in the mammalian central nervous system (CNS). The receptor selectively activated by N-methyl-D-aspartic acid (NMDA) has been best characterized using voltage-clamp and single-channel recording; the results suggest that NMDA receptors gate channels that are permeable to Na+, K+ and other monovalent cations. Various experiments suggest that Ca2+ flux is also associated with the activation of excitatory amino-acid receptors on vertebrate neurones. Whether Ca2+ enters through voltage-dependent Ca2+ channels or through excitatory amino-acid-activated channels of one or more subtype is unclear. Mg2+ can be used to distinguish NMDA-receptor-activated channels from voltage-dependent Ca2+ channels, because at micromolar concentrations Mg2+ has little effect on voltage-dependent Ca2+ channels while it enters and blocks NMDA receptor channels. Marked differences in the potency of other divalent cations acting as Ca2+ channel blockers compared with their action as NMDA antagonists also distinguish the NMDA channel from voltage-sensitive Ca2+ channels. However, we now directly demonstrate that excitatory amino acids acting at NMDA receptors on spinal cord neurones increase the intracellular Ca2+ activity, measured using the indicator dye arsenazo III, and that this is the result of Ca2+ influx through NMDA receptor channels. Kainic acid (KA), which acts at another subtype of excitatory amino-acid receptor, was much less effective in triggering increases in intracellular free Ca2+.

Identification of ZO-1 : a high molecular weight polypeptide associated with the tight junction (zonula occludens) in a variety of epithelia

Abstract: A tight junction-enriched membrane fraction has been used as immunogen to generate a monoclonal antiserum specific for this intercellular junction. Hybridomas were screened for their ability to both react on an immunoblot and localize to the junctional complex region on frozen sections of unfixed mouse liver. A stable hybridoma line has been isolated that secretes an antibody (R26.4C) that localizes in thin section images of isolated mouse liver plasma membranes to the points of membrane contact at the tight junction. This antibody recognizes a polypeptide of approximately 225,000 D, detectable in whole liver homogenates as well as in the tight junction-enriched membrane fraction. R26.4C localizes to the junctional complex region of a number of other epithelia, including colon, kidney, and testis, and to arterial endothelium, as assayed by immunofluorescent staining of cryostat sections of whole tissue. This antibody also stains the junctional complex region in confluent monolayers of the Madin-Darby canine kidney epithelial cell line. Immunoblot analysis of Madin-Darby canine kidney cells demonstrates the presence of a polypeptide similar in molecular weight to that detected in liver, suggesting that this protein is potentially a ubiquitous component of all mammalian tight junctions. The 225-kD tight junction-associated polypeptide is termed "ZO-1."

Preferences in human mate selection.

Abstract: In this article we examine preferences in mate choice within the broader context of the human mating system. Specifically, we discuss the consequences of mate preferences for the processes of assortative mating and sexual selection. In Study 1 (N = 184) we document (a) the mate characteristics that are consensually more and less desired, (b) the mate characteristics that show strong sex differences in their preferred value, (c) the degree to which married couples are correlated in selection preferences, and (d) the relations between expressed preferences and the personality and background characteristics of obtained spouses. In Study 2 (N = 100) we replicated the sex differences and consensual ordering of mate preferences found in Study I, using a different methodology and a differently composed sample. Lastly, we present alternative hypotheses to account for the replicated sex differences in preferences for attractiveness and earning potential. Neither men nor women prefer all members of the opposite sex equally. Some are favored over others, and one important research task is to identify the characteristics that prospective mates consider to be important. Although mate choice is clearly a crucial adult decision for more than 90% of the population (Price & Vandenberg, 1980), surprisingly little is known about the characteristics that men and women seek in potential mates (Thiessen & Gregg, 1980). In this article we develop a conception of the role of mate preferences within the human mating system. Specifically, we address the consequences for sexual selection and assortative mating. In two empirical studies we document several basic features of this conception.

A conception of adult development.

Abstract: Adult development is becoming an important field of study for psychology and other disciplines. Little has been done, however, to conceptualize the nature of adult development and to define the major issues in this field. The author summarizes his own formulations of life course, life cycle, life structure, and the adult development of the life structure in early and middle adulthood. He then discusses six major issues that must be dealt with by every structural approach to adult development: What are the alternative ways of defining a structural stage or period? What relative emphasis is given to the structures as compared to the transitional periods? How can we make best use of the distinction between hierarchical levels and seasons of development? Are there age-linked developmental periods in adulthood? What are the relative merits and limitations of various research methods? How can we bring together the developmental perspective and the socialization perspective? The study of adult development is, one might say, in its infancy. It has been taken seriously in the human sciences for only the past 30 years or so, largely under the impact of Erikson's (1950, 1958, 1969) germinal writings. Erikson's most obvious contribution was his theory of stages in ego development. What is less obvious is that his view of development is deeply grounded in his conceptions of the life cycle and the life course. Each ego stage has its primacy at a particular age level or segment of the life cycle, from infancy to old age. The sequence of age segments and ego stages thus provides a representation of the life cycle as a whole; the meaning of a stage is defined in part by its place in the total sequence. In addition, his developmental concepts arose out of his primary concern with the individual life course: the process of living, the idea of life history rather than case history, the use of biography rather than therapy or testing as his chief research method. Without abandoning the distinction between self (psyche, personality, inner world) and external world (society, culture, institutions, history), he gave first consideration to the life course--the engagement of self with world. Although a good deal has been learned since the 1950s about specific features of adult life, very little has been done to advance the general theory of adult development. At the same time, various fields of psychology (such as child development, gerontology, personality, social, clinical, and counseling psychology), as well as the social sciences and humanities, are becoming more aware that they need--and lack--an adult development perspective. Adult development is, in short, a significant problem for psychology as a discipline and an important link between psychology and other disciplines, including sociology, biology, and history. I have two primary aims here. First, I will present my conception of adulthood and of a developmental process within it. My intention is to explicate a theoretical position, not to prove it nor to argue for its superiority over others. The theory originated in my initial study of men's lives (Levinson, 1977, 1978). It has evolved over the last few years, particularly through my current research on women's lives (Levinson, in press). It is supported by a number of other studies (e.g., Gooden, 1980; Holt, 1980; Kellerman, 1975; Levinson, 1984; Stewart, 1976), but a great deal must yet be done to test and modify it. The theory includes the following elements: (a) The concepts of life course and life cycle, which provide an essential framework for the field of adult development; within this framework, studies of one process or age level can be connected to others, but without it, we have a miscellany of findings and no integrated domain of inquiry; (b) the concept of the individual life structure, which includes many aspects of personality and of the external world but is not identical with any of these and evolves in its own distinctive way; and (c) a conception of adult development--the evolution of the life structure in early and middle adulthood. Life structure development is different from, and should not be confused with, the development of personality, social roles, or other commonly studied processes. Second, I will discuss adult development as a field of study. I will consider six major issues that help to define what the field is about and what work must be done to establish it more securely. The list is not complete, but it provides a useful starting point. Reference will be made to the work of others, but the main goal is to clarify my own position. Let it be clear that my aim is not to give a comprehensive review of the work in this field nor to seek consensus among the disparate approaches. I hope that others will be stimulated to present contrasting views.

Structure of the receptor for platelet-derived growth factor helps define a family of closely related growth factor receptors

Abstract: The primary structure of the receptor for platelet-derived growth factor (PDGF), determined by means of cloning a cDNA that encodes the murine pre-PDGF receptor, is closely related to that of the v-kit oncogene product and the receptor for macrophage colony stimulating factor (CSF-1). Common structural features include the presence of long sequences that interrupt the tyrosine-specific protein kinase domains of each molecule. The PDGF and CSF-1 receptors also share a characteristic distribution of extracellular cysteine residues. Ubiquitin is covalently bound to the purified PDGF receptor, the human gene for which is on chromosome 5.

Concurrent overproduction of synapses in diverse regions of the primate cerebral cortex.

Abstract: Synapses develop concurrently and at identical rates in different layers of the visual, somatosensory, motor, and prefrontal areas of the primate cerebral cortex This isochronic course of synaptogenesis in anatomically and functionally diverse regions indicates that the entire cerebral cortex develops as a whole and that the establishment of cell-to-cell communication in this structure may be orchestrated by a single genetic or humoral signal This is in contrast to the traditional view of hierarchical development of the cortical regions and provides new insight into the maturation of cortical functions

Multiple, distinct forms of bovine and human protein kinase C suggest diversity in cellular signaling pathways.

Abstract: A new family of protein kinase C-related genes has been identified in bovine, human, and rat genomes. The alpha-, beta-, and gamma-type protein kinase sequences are highly homologous, include a kinase domain, and potential calcium-binding sites, and they contain interspersed variable regions. The corresponding genes are located on distinct human chromosomes; the possibility of even greater genetic complexity of this gene family is suggested by Northern and Southern hybridization analyses.

DNA bending at adenine . thymine tracts.

Abstract: Intrinsic bending of DNA molecules results from local structural polymorphism in regions of homopolymeric dA · dT which are at least 4 base pairs long; the A · T tracts must be repeated in phase with the helix screw. Bending, in the direction of base-pair tilt rather than roll, occurs at the junctions between the A · T tract and adjacent B-DNA, with a larger angle at the 3′ than at the 5′ end of the A tract.

The Dividend-Price Ratio and Expectations of Future Dividends and Discount Factors

Abstract: A linearization of a rational expectations present value model for corporate stock prices produces a simple relation between the log dividend-price ratio and mathematical expectations of future log real dividend changes and future real discount rates. This relation can be tested using vector autoregressive methods. Three versions of the linearized model, differing in the measure of discount rates, are tested for U. S. time series 1871-1986: versions using real interest rate data, aggregate real consumption data, and return variance data. The results yield a metric to judge the relative importance of real dividend growth, measured real discount rates and unexplained factors in determining the dividend-price ratio.

Aging and health: effects of the sense of control

Abstract: The relation between health and a sense of control may grow stronger in old age. This could occur through three types of processes: experiences particularly relevant to control may increase markedly in old age; the association between control and some aspect of health may be altered by age; and age may influence the association between control and health-related behaviors or the seeking of medical care. Studies show that there are detrimental effects on the health of older people when their control of their activities is restricted; in contrast, interventions that enhance options for control by nursing home patients promote health. With increasing age, however, variability in preferred amounts of control also increases, and sometimes greater control over activities, circumstances, or health has negative consequences including stress, worry, and self-blame. Mechanisms mediating the control-health relation include feelings of stress, symptom labeling, changes in the neuroendocrine and immune systems, and behavior relevant to health maintenance.

Depressive symptoms in relation to physical health and functioning in the elderly

Abstract: The associations between depressive symptoms and functional disability and chronic conditions are examined in an elderly cohort of 2,806 noninstitutionalized men and women living in New Haven, Connecticut who were interviewed in 1982 as a part of the Yale Health and Aging Project. The aim is to explore several potential sources of invalidity in using the Center for Epidemiologic Studies-Depression scale (CES-D) to measure depressive symptoms in elderly populations. In particular, the authors are concerned with the possibility that prevalent physical illnesses and disabilities may cause the older person to report many somatic complaints, a major component of most measures of depressive symptomatology, and thereby inflate his or her CES-D score. Mean CES-D scores are 4.86 for those without any disabilities and range to 13.51 for those with major functional disabilities. However, physical disability is significantly associated with virtually every item on the CES-D scale not just those somatically-oriented items. The addition of functional disability to a multivariate model including age subfactor analysis of responses from this elderly sample produces results almost identical to those reported by earlier investigators who studied younger and middle-aged adults. The authors conclude that physical disabilities among the elderly do not appear to be a major threat to the validity of the CES-D scale and that the strong associations between physical and mental health should be rigorously investigated.

Relational queries computable in polynomial time

Abstract: We characterize the polynomial time computable queries as those expressible in relational calculus plus a least fixed point operator and a total ordering on the universe. We also show that even without the ordering one application of fixed point suffices to express any query expressible with several alternations of fixed point and negation. This proves that the fixed point query hierarchy suggested by Chandra and Harel collapses at the first fixed point level. It is also a general result showing that in finite model theory one application of fixed point suffices.

Managerial Incentives and Capital Management

Abstract: The paper shows how career concerns rather than effort aversion can induce a natural incongruity in risk preferences between managers and superiors. A model, based on learning about managerial talent, is developed to study second-best contractual remedies. We show that the optimal wage contract is an option of the value of the manager's human capital for insurance reasons and that consequently rationing of capital is often required to counterbalance the manager's resulting incentive to overinvest. Rationing is strictly superior to price decentralization, offering one reason for the prevalence of centralized capital budgeting procedures.

Violence and the Word

Abstract: Legal interpretation' takes place in a field of pain and death. This is true in several senses. Legal interpretive acts signal and occasion the imposition of violence upon others: A judge articulates her understanding of a text, and as a result, somebody loses his freedom, his property, his children, even his life. Interpretations in law also constitute justifications for violence which has already occurred or which is about to occur. When interpreters have finished their work, they frequently leave behind victims whose lives have been torn apart by these organized, social practices of violence. Neither legal interpretation nor the violence it occasions may be properly understood apart from one another. This much is obvious, though the growing literature that argues for the centrality of interpretive practices in law blithely ignores it.2

Memory coherence in shared virtual memory systems

Abstract: This paper studies the memory coherence problem in designing and implementing a shared virtual memory on looselycoupled multiprocessors. Two classes of algorithms for solving the problem are presented. A prototype shared virtual memory on an Apollo ring has been implemented based on these algorithms. Both theoretical and practical results show that the memory coherence problem can indeed be solved efficiently on a loosely-coupled multiprocessor.

Lesions of the amygdala, but not of the cerebellum or red nucleus, block conditioned fear as measured with the potentiated startle paradigm.

Abstract: Rats were given 10 light-shock pairings on 2 successive days. At 24-48 hr following training, groups of rats received bilateral transection of the cerebellar peduncles, bilateral lesions of the red nucleus (which receives most of the cerebellar efferents), or bilateral lesions of the central nucleus of the amygdala. Control rats were sham operated. At 3-4 days after surgery, the rats were tested for potentiated startle (increased acoustic startle in the presence of the light previously paired with shock). Potentiated startle was blocked by lesions of the central nucleus of the amygdala. Transection of the cerebellar peduncles or lesions of the red nucleus did not block potentiated startle. A second experiment in which a visual prepulse test was used indicated that the blockade of potentiated startle observed in the animals with amygdala lesions could not be attributed to optic tract damage. A third experiment demonstrated that the absence of potentiation in the animals with amygdala lesions was not simply due to a lowered startle level ceiling, because these animals could show increased startle with increased stimulus intensity and with administration of strychnine, a drug that increases startle. Taken together, the results are consistent with the hypothesis that the amygdala is involved in fear conditioning, because potentiated startle is a measure of conditioned fear.

Learning to program = learning to construct mechanisms and explanations

Abstract: Teaching effective problem-solving skills in the context of teaching programming necessitates a revised curriculum for introductory computer programming courses.

The Concept of Strain in Organic Chemistry

Abstract: “Die Ringschliesung ist offenbar diejenige Erscheinung, welche am meisten uber die raumliche Anordnung der Atome Auskunft geben kann. Wenn eine Kette von 5 und 6 Gliedern sich leicht, eine von weniger oder mehr Gliedern sich schwierig oder auch gar nicht schliesen last, so mussen dafur offenbar raumliche Grunde vorhanden sein.… Die vier Valenzen des Kohlenstoffatoms wirken in den Richtungen, welche den Mittelpunkt der Kugel mit den Tetraederecken verbinden, und welche miteinander einen Winkel von 109°28′ machen. Die Richtung der Anziehung kann eine Ablenkung erfahren, die jedoch eine mit der Grose der Letzteren wachsende Spannung zur Folge hat,”[ ] This is the quintessence of the “ring-strain theory” formulated by Adolf von Baeyer over one hundred years ago. Although it is today only one facet of the many aspects of strain theory, it has repeatedly stimulated experimental and theoretical chemists. Among the most spectacular of the recent successes in synthetic chemistry are the syntheses of tetra-tert-butyltetrahedrane and [1.1.1]propellane. The reasons for the great stability of these two highly strained compounds are completely different. The experimental findings as well as the results of theoretical analysis by means of molecular mechanics and ab initio calculations have contributed decisively to our present state of knowledge of the structure, energy, and reactivity of organic compounds.