Showing papers by "Vanderbilt University published in 1984"

Measuring Tie Strength

Abstract: Little attention has been given to the measurement of the concept of tie strength. Using survey data on friendship ties, we apply multiple indicator techniques to construct and validate measures of tie strength. We conclude that: (1) there may be two distinct aspects of tie strength, having to do with the time spent in a relationship and the depth of the relationship; (2) a measure of "closeness" or intensity is the best indicator of strength; (3) there are difficulties with frequency and duration of contact as indicators of strength; (4) predictors of strength (e.g., kinship, neighboring) are not especially strongly related to the concept; and (5) the constructed measures of strength, particularly the one of "time spent," are valid in that they are related to predictor variables in anticipated directions. Tie strength is probably the network concept that has attracted the most research attention and the one that has led to the most in the way of substantive contributions. Research using the concept was initiated by the publication of Granovetter's (a) paper entitled "The Strength of Weak Ties," and Granovetter (c) has recently provided an overview of many of the studies that have invoked the concept. Substantive successes have been especially visible in the literature on the process of social mobility, where variations in tie strength have been shown to be systematically related to the outcomes of job search efforts, but there have been applications to other substantive concerns as well. These accomplishments based on the tie strength concept are notable ones. We find, however, an important gap in this literature. Little sustained attention has been given to the measurement of the concept of tie strength, and the (presumably differential) accuracy of the different mea*This paper was presented at the 1983 annual meeting of the American Sociological Association, session on Network Analysis. We thank Lois Verbrugge for help in understanding nuances of the data sources, and Mark Granovetter, Edward 0. Laumann, and Rachel Rosenfeld for helpful comments. Address correspondence to Peter V. Marsden, Department of Sociology, Hamilton Hall 070A, University of North Carolina, Chapel Hill, NC 27514. C) 1984 The University of North Carolina Press

Severe functional declines, work disability, and increased mortality in seventy-five rheumatoid arthritis patients studied over nine years

Abstract: Seventy-five patients with rheumatoid arthritis (RA) were reviewed 9 years after an extensive evaluation which included quantitative measures of functional capacity. These patients had received multiple intraarticular injections of thiotepa with corticosteroids early in their course, but appear demographically and functionally similar to other RA patients who had not received this therapy. Severe morbidity was seen over the 9-year period in the 55 surviving patients, including significantly lower overall functional capacity in 92% of patients studied, lower grip strength in 93%, and longer button test results in 84%. Work disability occurred in 85% of patients under age 65 who had been working full-time at disease onset. There was increased mortality at the 9-year review, similar to most reported series of RA patients from referral centers; however, a significant increase in neoplasia, which was of concern because of the use of intraarticular thiotepa, was not seen. In terms of functional capacity, including responses to questions about ability to perform activities, walking time, and the button test, those patients who had died prior to review had significantly lower baseline values than did those who survived. Of the 75 patients, 20 had died and 51 had lost significant functional capacity over a 9-year period, documented by quantitative measures of functional capacity.

Mephenytoin hydroxylation deficiency in Caucasians: Frequency of a new oxidative drug metabolism polymorphism

Abstract: The ability of normal subjects to hydroxylate mephenytoin (100 mg) or debrisoquine (10 mg) after oral dosing was investigated in 156 unrelated Caucasians living in middle Tennessee. Urinary recovery of 4-hydroxymephenytoin (4-OH-M) and the urinary S:R enantiomeric ratio of mephenytoin measured in an 8-hr urine sample were investigated as phenotypic traits for mephenytoin, and the urinary metabolic ratio of debrisoquine was used to determine the debrisoquine hydroxylase phenotype. Both urinary 4-OH-M and the S:R ratio of mephenytoin discriminated between extensive (EM) and poor (PM) metabolizers of mephenytoin. The frequencies of PMs for mephenytoin and debrisoquine hydroxylation activity were 2.6% and 7.0%. These two defects in oxidative metabolism were not observed in the same subjects, which suggests that 4-hydroxylation of mephenytoin is a new polymorphism independent of that for debrisoquine.

Prognostic factors in patients with resected stage I non-small cell lung cancer. A report from the Lung Cancer Study Group.

Abstract: The authors present prognostic information on recurrence and survival for resected Stage I lung cancer patients with squamous cell carcinoma, adenocarcinoma or large cell carcinoma. The data derive from 392 carefully staged patients and include results from the history and physical examination, preoperative laboratory tests, nature of the surgery, complications, initial pathologic findings following surgical resection, and final pathologic review. A simple multivariate model of recurrence, which is used to classify patients into low, intermediate, and high-risk groups, is based on tumor size and location (T1, T2), histologic type (squamous, nonsquamous/mixed) and nodal status (N0, N1). To model survival, the performance status and the presence of empyema, pneumonia, or wound infection were added to the previous factors. Not all factors associated with increased mortality are associated with increased risk of recurrence, and, in particular, postoperative empyema, pneumonia or wound infections carry an increased risk of death only. Serial measurements of performance status and leukocyte count have the potential for monitoring for increased risk of recurrence and death.

Unilateral Hearing Impairment in Children

Abstract: An overview and update are offered on difficulties experienced by children with monaural sensorineural deafness. It is the general consensus that children with unilateral hearing loss experience few, if any, communication and/or educational problems. The medical and educational status of a group (N = 60) of children with unilateral, hearing impairment are described. In addition, the auditory, linguistic, and behavioral manifestations of unilateral hearing impairment were studied in considerable detail for a subsample of these 60 children. The results revealed that approximately one third of the children with unilateral hearing loss had failed at least one grade. Nearly 50% of the group had either failed a grade and/or needed resource assistance in the schools. The small subsample of children with unilateral hearing loss performed much poorer than a matched group of children with normal hearing on both a localization and a syllable recognition task. Finally, the data on behavioral and linguistic manifestations of monaural hearing loss indicate that children with unilateral hearing impairment are experiencing more problems than previously supposed.

The Formation of Ability Conceptions: Developmental Trend or Social Construction?

Abstract: This paper examines a growing literature on the ways in which children develop conceptions of their own and their peers’ intellectual abilities, a phenomenon we will call ability formation. We show that this literature may be integrated usefully under a recently developed theory regarding the ways in which schools construct academic ability as a reality experienced by students. We argue that this perspective offers an advance on developmental interpretations of findings in this area.

Age and Sequencing Norms in the Transition to Adulthood

Abstract: The timing and sequencing of events marking the transition to adulthood have become the focus of a growing body of research. Recently, the concept of social norm has been used to provide an explanation for observed regularity in the process of transition to adulthood, and the degree of conformity to social norms governing the transition has been hypothesized to have consequences for individuals in adulthood. In this paper it is argued that the concept of social norm has limited usefulness as an explanation of behavior marking the transition to adulthood or as an explanation of its consequences. It is argued further that previous use of the concept in empirical research has been misleading because the research has not measured social norms. Over the past few years, sociologists have paid increasing attention to the study of age differentiation and the social organization of the life course. Much theorizing in this area assumes a normative model of the life course, whereby norms, or shared expectations, regarding an appropriate timetable for major life events frame the life course. These norms are assumed to be supported by informal sanctions, resulting when major deviations from the prescriptive timetable occur-for example, when a role transition occurs too early or too late (Elder, a, b; Neugarten and Datan; Neugarten et al; Riley et al.). This normative model of development over the life course has been in evidence in recent research on the transition to adulthood. Since the transition to adulthood is marked by a series of interrelated events representing movement from economic dependence and participation in the

Characterization of a monoclonal antibody to the rat liver glucocorticoid receptor.

Abstract: The rat liver glucocorticoid receptor was partially purified and used to immunize a BALB/c mouse whose splenic lymphocytes were fused with the nonsecreting myeloma cell line P3-AgX-653. The fusion products were selected in HAT (hypoxanthine, aminopterine, and thymidine) medium and a stable antibody-producing clone designated BuGRl obtained from 1 of 81 positive wells. Immunological specificity for the receptor was confirmed by sucrose density gradient analysis when the sedimentation constant of the specifically labeled receptor was altered by reaction with the antibody and by Western blot analysis, which showed that the BuGRl antibody detected a single band with a mobility (mol wt, ∼95,000) identical to that of the [3H]dexamethasone 21-mesylate-labeled rat glucocorticoid receptor. Similar sucrose gradient and Western blot experiments showed that the BuGRl antibody reacted with the mouse glucocorticoid receptor. BuGRl is a stable hybridoma producing an antibody which detects loci common to both rat and mou...

Structure of rat atrial natriuretic factor precursor deduced from cDNA sequence

Abstract: The atrium of the heart contains peptides, termed atrial natriuretic factors (ANFs), diuretic1 and smooth-muscle-relaxing2–4 activities. In view of its potent effects on salt metabolism in the kidney and on vascular smooth muscle, ANF is considered to play an important part in the control of fluid volume and vascular function. Several different ANF peptides varying in size have been isolated3–10 and their amino acid sequences determined4,6–10. Analysis of the sequences of the peptides suggests that they are derived by proteolysis from the same precursor. To examine this hypothesis, we have cloned cDNAs of the ANF precursor using rat atrial mRNA, determined its nucleotide sequence and deduced its amino acid sequence. The ANF precursor consists of 152 amino acid residues including a putative signal peptide sequence. This sequence contains the amino acid sequences of all the ANF peptides reported to date4,6–10.

Cognitive theories of persuasion

Abstract: Publisher Summary This chapter discusses the end-products of social psychological processes It reviews a research on a fairly extensive history in social psychology––persuasion Testifying to the present dominance of cognitive analyses, the cognitive theories of persuasion are concentrated and demonstrate the fruitfulness of these formulations The social psychological perspectives are developed to be useful to practitioners The theories of persuasion are designed to account for the attitude and belief change that occurs in people who are exposed to relatively complex messages that consist of a position advocated by a communicator Some of the limitations of the cognitive emphasis of most contemporary theories of persuasion consider several viewpoints that emphasize motivation as cognition The mathematically formulated combinatorial models are reviewed, which have explanatory value primarily in relation to the effects of the content of the persuasive message The applications of persuasion theory to more practical concerns are also described in the chapter Theories that have elaborated the cognitive mediation of persuasion are also considered in the chapter

Receptive-field properties of neurons in middle temporal visual area (MT) of owl monkeys.

Abstract: Response properties of single neurons in the middle temporal visual area (MT) of anesthetized owl monkeys were determined and quantified for flashed and moving bars of light under computer control for position, orientation, direction of movement, and speed. Receptive-field sizes, ranging from 4 to 25 degrees in width, were considerably larger than receptive fields with corresponding eccentricities in the striate cortex. Neurons were highly binocular with most cells equally or nearly equally activated by either eye. Neurons varied in selectivity for axis and direction of moving bars. Some neurons demonstrated little or no selectivity, others were bidirectional on a single axis, while the largest group was highly selective for direction with little or no response to bar movement opposite to the preferred direction. Over 70% of neurons were classified as highly selective and 90% showed some preference for direction and/or axis of stimulus movement. Neurons typically responded to bar movement only over a restricted range of velocities. The majority of neurons responded best to a particular velocity within the 5-60 degrees/s range, with marked attenuation of the response for velocities greater or less than the preferred. Some neurons failed to show significant response attenuation even at the lowest tested velocity, while other neurons preferred velocities of 100 degrees/s or more and failed to attenuate to the highest velocities. Response magnitude varied with stimulus dimensions. Increasing the length of the moving bar typically increased the magnitude of the response slightly until the stimulus exceeded the receptive-field borders. Other neurons responded less to increases in bar length within the excitatory receptive field. Neurons preferred narrow bars less than 1 degree in width, and marked reductions in responses characteristically occurred with wider stimuli. Moving patterns of randomly placed small dots were often as effective as or more effective than single bars in activating neurons. Selectivity for direction of movement remained for the dot pattern. for the dot pattern. Poststimulus time (PST) histograms of responses to bars flashed at a series of 21 different positions across the receptive field, in the "response-plane" format, indicated a spatially and temporally homogeneous receptive-field structure for nearly all neurons. Cells characteristically showed transient excitation at both stimulus onset and offset for all effective stimulus locations. Some cells responded mainly at bright stimulus onset or offset.

Method for locating the illuminated tip of an endotracheal tube

Abstract: An improvement in catheters and other medical tubes and in the method of use thereof, which facilitates the precise positioning of the tips of such tubes within body passages. The improved method and device are particularly useful in the care and treatment of premature infants. The medical tube has a fiberoptic light conductor extending lengthwise through the wall thereof, the conductor ending in a light emitting and redirecting terminus adjacent the tube's free or distal end. The opposite end of the conductor is operatively connected to an external source of high-intensity light in the visible range. Light emitted laterally from the tip of such an indwelling tube may be visually and externally observed through the body wall of the patient for accurately and quickly determining the anatomical location of that tip. In a preferred embodiment, the tube is formed of transparent, flexible, thermoplastic material and the light-emitting terminus of the conductor is beveled and is completely embedded within the wall of the tube, so that light emitted from the terminus must pass through the tube's transparent wall.

A Customer-oriented Approach for Determining Market Structures:

Abstract: A framework for market analysis based on customer perceptions of substitutability-in-use is presented. An empirical application in the financial/banking services market is used to illustrate that w...

Arginine vasopressin potentiates adrenocorticotropin release induced by ovine corticotropin-releasing factor.

Abstract: Arginine vasopressin (AVP) stimulates ACTH release in man and acts synergistically with synthetic ovine corticotropin-releasing factor (oCRF) in vitro. This study was designed to examine in man the combined effects of synthetic AVP (10 U intramuscularly) and oCRF (1 micrograms/kg intravenously) on ACTH release. Five normal male volunteers participated in five separate experiments: (a) AVP alone; (b) oCRF alone; (c) AVP followed by oCRF 15 min later; (d) simultaneous AVP and oCRF; and (e) insulin-induced hypoglycemia. Plasma immunoreactive ACTH (IR-ACTH) and IR-cortisol were measured for 4 h after injection of each hormone; basal levels for all subjects were less than or equal to 9 +/- 1.2 pg/ml and 4.9 +/- 0.4 micrograms/dl (mean +/- SE), respectively. AVP and oCRF, when given individually, caused rapid rises in IR-ACTH to similar peak levels of 25 +/- 6.6 and 33 +/- 4.6 pg/ml, respectively. AVP given 15 min before oCRF caused a 2.6-fold potentiation of the oCRF response, with a peak IR-ACTH of 85 +/- 4.6 pg/ml. AVP given at the same time as oCRF produced a fourfold potentiation of the peak IR-ACTH response to 132 +/- 11 pg/ml. These ACTH responses were far greater than those previously observed after 30-fold greater doses of oCRF alone. By way of comparison, insulin-induced hypoglycemia caused a peak IR-ACTH of 169 +/- 20 pg/ml. IR-ACTH returned to base line at 60-90 min after AVP alone, whereas the prolonged effect of oCRF was apparent whether it was given alone or in combination with AVP. The mean peak IR-cortisol responses to AVP, oCRF, and AVP given 15 min before oCRF were similar (16.5 +/- 0.9, 16.4 +/- 2.3, and 18.5 +/- 0.8 micrograms/dl, respectively), but the peak IR-cortisol responses to AVP and oCRF given simultaneously and to insulin-induced hypoglycemia were 1.5 and 1.7 times greater, respectively. IR-cortisol returned to base line within 2-3 h after AVP alone, but remained elevated for at least 4 h after oCRF alone or in combination with AVP. These results indicate that AVP acts synergistically with oCRF to release ACTH in man and suggest that AVP may play a physiologic role in modulating the ACTH response mediated by corticotropin-releasing factor.

The somatotopic organization of the ventroposterior thalamus of the squirrel monkey, Saimiri sciureus.

Abstract: Multiunit microelectrode mapping techniques were used to investigate the organization of the somatosensory thalamus in squirrel monkeys. Receptive fields and response characteristics were determined for closely spaced recording sites along arrays of electrode penetrations that passed through the ventral thalamus dorsoventrally, rostrocaudally, or lateromedially. The results were related to thalamic architecture and led to the following conclusions: (1) A large, single, systematic representation of the body surface occupied most or all of the ventroposterior nucleus, VP. The nucleus was further defined by a distinct cytoarchitectonic appearance, produced by densely packed, deeply stained neurons. (2) Recording sequences in VP were characterized by (a) abrupt shifts in receptive field locations over short recording distances indicating that the electrode had crossed discontinuities or folds in the representation, (b) long sequences of overlapping receptive fields indicating regions of continuous representation and the maintenance of adjacency in the map, and (c) similar receptive field locations for sites along the trajectory of a penetration indicating regions of isorepresentation. Major somatotopic discontinuities were associated with crossing narrow cell-poor laminae that partially divided VP into subnuclei related to the hand, foot, trunk, and tail in lateral VP and the face in medial VP. Somatotopic discontinuities occurred for electrode penetrations in all three planes, but discontinuities were greater and more frequent for lateromedial electrode penetrations. Lines of isorepresentation and gradual change were most extensive in the rostrocaudal and dorsoventral planes. We hypothesize that the disruptions, regions of isorepresentation, and regions of gradual change result from the thickening, splitting, and folding of a two-dimensional representation of the skin surface to occupy a three-dimensional volume. (3) The magnifications of various skin surfaces in VP were variable so that some skin surfaces, especially the tips of the digits, occupied relatively large portions of the nucleus, while other skin surfaces such as the trunk activated little tissue. It appeared that regions of isorepresentation varied in extent according to magnification factor and position in the map. (4) Within VP, neurons could be classified as slowly adapting or rapidly adapting to maintained skin indentation. Each type of neuron formed small groups or clusters in the nucleus so that several successive recording sites typically encountered one type before a sequence of the other type was observed.(ABSTRACT TRUNCATED AT 400 WORDS)

The mental representation of knowledge acquired from maps.

Abstract: The experiments reported here, tested how knowledge acquired from simple maps is mentally represented and processed. These experiments also tested a new methodology for examining spatial representations. The main question addressed in this research was how route and distance information are represented in cognitive maps. In particular, the experiments examined the relative contributions of route and Euclidean distance on a map to determining the psychological distance between locations in the mental representation of that map. For example, in Figure 1, the cities Sedona and Emmet are equidistant from Nesmith in terms of Euclidean distance. However, Sedona is much closer to Nesmith than is Emmet in terms of route distance. In Experiments 1 and 2, we attempted to determine if the psychological distance between cities in a cognitive map would be primarily dependent on the route distance or the Euclidean distance between those cities on the real map. The second goal of this research was to test a new methodology for examining the

Prognostic significance of estrogen receptor status in breast cancer in relation to tumor stage, axillary node metastasis, and histopathologic grading

Abstract: The value of estrogen receptor (ER) measurements for predicting recurrence and survival rates in primary breast cancer was examined in 121 women who were followed from 5 to 12 years after mastectomy with a median follow-up of 64 months. The prognostic significance of the ER status was evaluated independently and in association with tumor stage, axillary node metastasis, and histopathologic grade. The independent evaluation demonstrated no statistically significant difference in prognosis between women with ER-negative and ER-positive cancers, although the latter group tended to have a longer time to recurrence and longer survival. Multivariate analysis of the data by Cox's proportional hazard regression techniques revealed a synergistic effect of ER status on the risk associated with axillary node metastasis. Patients with nodal metastasis were at 2.8 times the risk of recurrence compared to patients without metastasis. For women with nodal metastasis whose primary cancer was ER-negative, this risk increased to 4.6 times compared to women without metastasis and ER-positive tumors (P = 0.0003). The risk of cancer-related death was 5.6 times more likely for poorly differentiated tumors than for highly differentiated tumors. Patients with poorly differentiated ER-negative tumors were at an even higher risk (7.0) of dying than women with highly differentiated ER-positive carcinomas (P = 0.009). In conjunction with tumor stage, axillary node metastasis and histopathologic grade ER determination is useful for identifying subpopulations at increased risk of tumor recurrence or mortality.

Interorganizational Cooperation and Decision Making Autonomy in a Consortium Multihospital System

Abstract: This paper discusses interorganizational relationships within one type of multihospital system, a consortium. Reasons for the development of this type of system are presented. Hypotheses are proposed explaining how the general strategic-level decisions of hospitals may be influenced as a result of consortium affiliation.