Showing papers by "University of Miami published in 1994"

Behavioral inhibition, behavioral activation, and affective responses to impending reward and punishment: The BIS/BAS Scales

Abstract: J. A. Gray (1981, 1982) holds that 2 general motivational systems underlie behavior and affect: a behavioral inhibition system (BIS) and a behavioral activation system (BAS). Self-report scales to assess dispositional BIS and BAS sensitivities were created. Scale development (Study 1) and convergent and discriminant validity in the form of correlations with alternative measures are reported (Study 2). In Study 3, a situation in which Ss anticipated a punishment was created. Controlling for initial nervousness, Ss high in BIS sensitivity (assessed earlier) were more nervous than those low in BIS sensitivity. In Study 4, a situation in which Ss anticipated a reward was created. Controlling for initial happiness, Ss high in BAS sensitivity (Reward Responsiveness and Drive scales) were happier than those low in BAS sensitivity. In each case the new scales predicted better than an alternative measure. Discussion is focused on conceptual implications.

Reduction of maternal-infant transmission of human immunodeficiency virus type 1 with zidovudine treatment. Pediatric AIDS Clinical Trials Group Protocol 076 Study Group.

Abstract: Background and Methods Maternal-infant transmission is the primary means by which young children become infected with human immunodeficiency virus type 1 (HIV). We conducted a randomized, double-blind, placebo-controlled trial of the efficacy and safety of zidovudine in reducing the risk of maternal-infant HIV transmission. HIV-infected pregnant women (14 to 34 weeks' gestation) with CD4+ T-lymphocyte counts above 200 cells per cubic millimeter who had not received antiretroviral therapy during the current pregnancy were enrolled. The zidovudine regimen included antepartum zidovudine (100 mg orally five times daily), intrapartum zidovudine (2 mg per kilogram of body weight given intravenously over a one-hour period, then 1 mg per kilogram per hour until delivery), and zidovudine for the newborn (2 mg per kilogram orally every six hours for six weeks). Infants with at least one positive HIV culture of peripheral-blood mononuclear cells were classified as HIV-infected. Results From April 1991 through Decemb...

Retrieval of water-leaving radiance and aerosol optical thickness over the oceans with SeaWiFS: a preliminary algorithm

Abstract: The second generation of ocean-color-analyzing instruments requires more accurate atmospheric correction than does the Coastal Zone Color Scanner (CZCS), if one is to utilize fully their increased radiometric sensitivity. Unlike the CZCS, the new instruments possess bands in the near infrared (NIR) that are solely for aiding atmospheric correction. We show, using aerosol models, that certain assumptions regarding the spectral behavior of the aerosol reflectance employed in the standard CZCS correction algorithm are not valid over the spectral range encompassing both the visible and the NIR. Furthermore, we show that multiple-scattering effects on the algorithm depend significantly on the aerosol model. Following these observations, we propose an algorithm that utilizes the NIR bands for atmospheric correction to the required accuracy. Examples of the dependence of the error on the aerosol model, the turbidity of the atmosphere, and surface roughness (waves) are provided. The error in the retrieved phytoplankton-pigment concentration (the principal product of ocean-color sensors) induced by errors in the atmospheric correction are shown to be <20% in approximately 90% of the cases examined. Finally, the aerosol thickness (τ(α)) is estimated through a simple extension of the correction algorithm. Simulations suggest that the error in the recovered value of τ(α) should be ≲ 10%.

The influence of store environment on quality inferences and store image

Abstract: The study reported here examines how combinations of specific elements in the retail store environment influence consumers’ inferences about merchandise and service quality and discusses the extent to which these inferences mediate the influence of the store environment on store image. Results show that ambient and social elements in the store environment provide cues that consumers use for their quality inferences. In addition, store environment, merchandise quality, and service quality were posited to be antecedents of store image—with the latter two serving as mediators—rather than components of store image (as they are typically treated in the store image literature). Theoretical and managerial implications of the findings are discussed, and future research directions are proposed.

Testing the iron hypothesis in ecosystems of the equatorial Pacific Ocean

Abstract: The idea that iron might limit phytoplankton growth in large regions of the ocean has been tested by enriching an area of 64 km2 in the open equatorial Pacific Ocean with iron This resulted in a doubling of plant biomass, a threefold increase in chlorophyll and a fourfold increase in plant production Similar increases were found in a chlorophyll-rich plume down-stream of the Galapagos Islands, which was naturally enriched in iron These findings indicate that iron limitation can control rates of phytoplankton productivity and biomass in the ocean

A chemically and electrochemically switchable molecular shuttle

Abstract: THE developing field of nanotechnology has generated wide interest across a broad range of scientific disciplines1. In particular, the realization of nanoscale switching devices might have far-reaching implications for computing and biomimetic engineering2–4. But miniaturization of existing semiconductor technology may not be the best approach to the fabrication of structures whose dimensions are smaller than the wavelength of the radiation used in optical lithography and etching techniques5. The approach observed in the natural world, whereby nanostructures are built up through the self-assembly6–9 of smaller molecular entities, holds substantial promise. Nature abounds with molecular switching devices which perform a variety of functions, such as the transport of metabolites across cell membranes or the signalling of nerve impulses. These processes are commonly controlled by stimuli such as changes in ion concentrations and electrical potentials. Here we report the synthesis of a supramolecular structure (compound 1-[PF6]4, Fig. 1A) that can be reversibly switched between two states by proton concentration changes or by electrochemical means. The super-molecule is a rotaxane comprising a molecular ring threaded on an axle containing two ‘docking points’. We can effect controlled switching of the ring from one of these positions to the other. We use 1H NMR and ultra violet/visible spectroscopy to characterize the dynamics of the bead's movement along the thread before and after switching.

Efficacy of Divalproex vs Lithium and Placebo in the Treatment of Mania

Abstract: Objective. —To compare the effectiveness of divalproex sodium with that of lithium and placebo in patients with acute mania. Design. —Randomized, double-blind, parallel-group study of treatment outcomes in patients with manic-depressive illness. Patients. —A total of 179 hospitalized, acutely manic patients meeting the Research Diagnostic Criteria for manic disorder, approximately half of whom had been nonresponsive to lithium previously, were studied at nine university-affiliated hospitals. Interventions. —After a minimum 3-day washout period, random assignment for 21 days to divalproex, lithium, or placebo in a 2:1:2 ratio. Dosage of divalproex and lithium was increased if tolerated to a target concentration of 1041 μmol/L (150 μg/ mL) or 1.5 mmol/L (conventionally expressed as milliequivalents per liter), respectively. Main Outcome Measures. —Primary outcome measures were changes in the Mania Rating scale derived from the Schedule for Affective Disorders and Schizophrenia. Results. —Intent-to-treat analysis for efficacy was based on data from 68, 35, and 73 patients in the divalproex, lithium, and placebo groups, respectively. Groups were initially comparable except that all eight patients with four or more manic episodes in the previous year were in the divalproex group. In 30%, 33%, and 51% of the above groups, treatment was prematurely terminated due to lack of efficacy, with fewer premature terminations from divalproex than placebo (P=.017). The proportions of patients improving at least 50% were higher for divalproex and lithium groups than for the placebo group: 48% for divalproex (P=.004) and 49% for lithium (P=.025) vs 25% for placebo. Divalproex was as effective in rapid-cycling manic patients as in other patients. Conclusions. —Both divalproex and lithium were significantly more effective than placebo in reducing the symptoms of acute mania. The efficacy of divalproex appears to be independent of prior responsiveness to lithium. (JAMA. 1994;271:918-924)

Situational coping and coping dispositions in a stressful transaction.

Abstract: After reporting dispositional coping styles, students reported situational coping and 4 classes of affect (from threat, challenge, harm, and benefit appraisals) 2 days before an exam, after the exam but before grades were posted, and after posting of grades. Coping did not predict lower levels of future distress; indeed, some coping seemed to induce feelings of threat. Feelings of harm before the exam induced several kinds of coping after the exam, mostly dysfunctional. Confidence about one's grade was a better predictor of emotions throughout than was coping. Dispositional coping predicted comparable situational coping at low-moderate levels in most cases. Coping dispositions did not reliably predict emotions, however, with these exceptions: Dispositional denial was related to threat, as was dispositional use of social support; dispositional use of alcohol was related to both threat and harm.

The Moderating Effects of Message Framing and Source Credibility on the Price-perceived Risk Relationship

Abstract: One factor that research has identified as a critical determinant of consumers' willingness to buy a new product or brand is the perceived risk associated with the purchase. Consequently, a better understanding of the factors affecting consumers' perceptions of the financial and performance risk entailed by the purchase of a new brand is of both theoretical and pragmatic importance. Previous research has suggested that a new product's price affects consumers' perceptions of risk. The current article extends and integrates previous research by proposing that the effect of price on consumers' perceptions of risk is moderated by two communication factors: message framing and source credibility. The results of an experiment support the predictions that the influence of price on consumers' perceptions of performance risk is greater when the message is framed negatively or the credibility of the source is low. In addition, the results support the prediction that the effect of price on consumers' perceptions of financial risk is greater when the message is framed positively.

Implantable spinal assist device

Abstract: An implantable device (2) for restoring normal bio-mechanical function to a motion segment of the spine which includes a curvilinear body (4) composed of a composite material made-up of a fiber material interspersed in a matrix material.

Leader-Member Exchange and Supervisor Career Mentoring as Complementary Constructs in Leadership Research

Abstract: The literature on transformational and transactional leadership suggests integrating the leader-member exchange (LMX) approach with research on mentoring. Using LISREL VII confirmatory factor analy...

Joint attention, developmental level, and symptom presentation in autism

Abstract: Recent data suggest that a disturbance in the development of joint attention skills is a specific characteristic of young autistic children. This observation may have both theoretical and clinical significance. However, many pertinent issues remain to be addressed with regard to the parameters of joint attention disturbance in children with autism. This study attempted to address several of these issues. The study examines the effects of mental age and IQ on the joint attention skills of children with autism, mental retardation, and normal development. The study also examined the relation of joint attention behaviors to the parent's report of symptoms presented by children with autism. The results suggested that, differences in IQ and mental age may be related to differences in the type of joint attention skill deficits displayed by children with autism. The results also suggested that joint attention disturbance is associated with a circumscribed, but social cluster of symptoms observed among young autistic children by their parents. The implications of these findings for developmental models of autism are discussed.

Gender Differences in Expected Outcomes of Mentoring Relationships

Abstract: We investigated differences in the costs and benefits associated with being a mentor in a matched sample of 80 male and BO female executives. Women were as likely as men to be mentors and reported ...

Involuntary stepping after chronic spinal cord injury. Evidence for a central rhythm generator for locomotion in man.

Abstract: We investigated a pattern of involuntary lower extremity stepping-like movements which recently appeared in a subject with a 17-year history of neurologically incomplete injury to the cervical spinal cord. The movements were rhythmic, alternating and forceful, involved all muscles of the lower extremities and could be reliably evoked by lying the subject down (supine) and extending his hips. Once in this position, the movements continued spontaneously, in the absence of external sensory perturbations, with a step-cycle duration of ˜3.5 s (0.3 Hz). This rate could be either increased or temporarily halted by specific sensory inputs. Anaesthetizing the subject's right hip joint, in which we found evidence of pathology, led to a marked attenuation of the stepping movements for a period of ˜15 min. We believe that a combination of (i) preserved but limited supraspinal tonic facilitation, and (ii) abnormal, perhaps noxious afferent inflow from the subject's right hip to the spinal cord may underlie the appearance of this highly unusual and involuntary movement pattern. The striking similarity between the movement and EMG patterns in this subject and those described in many reports using the surgically reduced cat model suggests that we were witnessing the first well-defined example of a central rhythm generator for stepping in the adult human.

Early microvascular and neuronal consequences of traumatic brain injury: a light and electron microscopic study in rats.

Abstract: The purpose of this study was to document the early morphologic consequences of moderate traumatic brain injury (TBI) in anesthetized Sprague-Dawley rats. Normothermic rats (37°C) were injured with a fluid percussion pulse (1.7–2.1 atm) administered by an injury cannula positioned parasagittally over the right cerebral cortex (n = 7). At 45 min following TBI, rats were injected with the protein tracer horseradish peroxidase (HRP) and perfusion fixed or immersion fixed 15 min later for light and electron microscopic analysis. Blood–brain barrier (BBB) breakdown to HRP was present overlying the pial surface and superficial cortical layers of the injured hemisphere. A focal area of severe HRP leakage was also present at the gray–white interface of the lateral cortex. Light microscopic examination of this site revealed petechial hemorrhages associated with small venules. Dark shrunken neurons and swollen astrocytes were detected within cortical areas overlying the evolving contusion, CA3 and CA4 hipp...

Reliability of Drug Users' Self-Reported HIV Risk Behaviors and Validity of Self-Reported Recent Drug Use.

Abstract: This study examined the reliability and validity of the Risk Behavior Assessment, a structured interview questionnaire designed to evaluate drug use and sexual HIV risk behaviors. Participants were 218 drug users currently not in treatment who completed the RBA two times over a 48-hour period and gave urine samples on both occasions. We examined internal consistency and test-retest reliability and found that, overall, drug users reliably report drug use and sexual behavior, although the reliability of reports of specific needle practice and sexual behavior items was somewhat lower. Validity results indicated that drug users' accurately report use of cocaine and opiates. These findings indicate that this self-report questionnaire, when administered by trained interviewers, reliably measures HIV risk behaviors in a drug-using population and provides a valid assessment of recent drug use.

Parkinson's disease and brain levels of organochlorine pesticides

Abstract: Epidemiological studies have suggested an etiologic relationship between pesticide exposure and Parkinson's disease (PD). Organochlorine pesticides were assayed in postmortem brain samples from 20 PD, 7 Alzheimer's disease (AD), and 14 nonneurological control cases. The three groups were similar in age at death, sex, and demographic variables. Only two of 16 pesticide residues screened were detected. A long-lasting residue of DDT (pp-DDE) was found in the majority of cases of PD and AD, as well as in all the control cases; pp-DDT was significantly more likely to be found in AD controls than the PD cases (Fisher's exact two-tailed, p = 0.04). Dieldrin was detected in 6 of 20 PD brains, 1 of 7 AD, and in none of 14 control samples. Despite the relatively small number of brains assayed, the association between Dieldrin and the diagnosis of PD was highly significant (p = 0.03). Dieldrin, a lipid-soluble, long-lasting mitochondrial poison, should be investigated as a potential etiological agent of Parkinsonism.

Emotional disclosure through writing or speaking modulates latent Epstein-Barr virus antibody titers.

Abstract: Healthy Epstein-Barr virus (EBV) seropositive undergraduates (N = 57) completed a personality inventory, provided blood samples, and were randomly assigned to write or talk about stressful events, or to write about trivial events, during three weekly 20-min sessions, after which they provided a final blood sample. Individuals assigned to the verbal/stressful condition had significantly lower EBV antibody titers (suggesting better cellular immune control over the latent virus) after the intervention than those in the written/stressful group, who had significantly lower values than those in the written/trivial control group. Subjects assigned to the written/stressful condition expressed more negative emotional words than the verbal/stressful and control groups and more positive emotional words than the verbal/stressful group at each time point. The verbal/stressful group expressed more negative emotional words compared with the control group at baseline. Content analysis indicated that the verbal/stressful group achieved the greatest improvements in cognitive change, self-esteem, and adaptive coping strategies.

A line in the sea

Abstract: THE ocean has considerable spatial and temporal heterogeneity in biomass and productivity owing in part to the effects of ocean circulation and mixing1,2. Water mass boundaries (fronts) in coastal waters are well-known sites of enhanced biological activity3,4. Comparatively little is known of open-ocean fronts, and one of the few biological studies of an oceanic front showed phytoplankton biomass at only slightly higher densities than in surrounding waters5. Here we present photographs and measurements from satellites, aircraft, ships and the Space Shuttle Atlantis which show dramatic biological responses to circulation and mixing processes associated with an open-ocean front. Breaking waves (whitecaps) caused by water turbulence and mixing, and very dark green water caused by extremely high concentrations (>20 mg of chlorophyll a per m3) of buoyant diatoms (Rhizosolenia sp.) made a distinct line in the sea visible for hundreds of kilometres. The line traced the northern edge of a westward-progagating (50 km per day) tropical instability wave (1,000-km wavelength) delineating the boundary between cold, upwelled waters and warmer waters to the north. High phytoplankton biomass and primary production associated with the extensive diatom patches may explain anecdotal observations of high animal abundance along this frontal boundary.

The effects of mother's physical and emotional unavailability on emotion regulation

Abstract: In summary, emotion dysregulation can develop from brief or more prolonged separations from the mother as well as from the more disturbing effects of her emotional unavailability, such as occurs when she is depressed Harmonious interaction with the mother or the primary caregiver (attunement) of the mother's physical unavailability were seen in studies of separations from the mother due to her hospitalization or to her conference trips These separations affected the infants' play behaviors and sleep patterns Comparisons between hospitalizations and conference trips, however, suggested that the infants' behaviors were more negatively affected by the hospitalizations than the conference trips This probably related to these being hospitalizations for the birth of another baby--the infants no longer had the special, exclusive relationship with their mothers after the arrival of the new sibling This finding highlights the critical importance of emotional availability The mother had returned from the hospital, but, while she was no longer physically unavailable, she was now emotionally unavailable Emotional unavailability was investigated in an acute form by comparing two laboratory situations, the still face paradigm and the momentary leave taking The still face had more negative effects on the infants' interaction behaviors than the physical separation The most extreme form of emotional unavailability, mother's depression, had the most negative effects The disorganization or emotion dysregulation in this case is more prolonged Changes in physiology (heart rate, vagal tone, and cortisol levels), in play behavior, affect, activity level, and sleep organization as well as other regulating functions such as eating and toileting, and even in the immune system persist for the duration of the mother's depression My colleagues and I have suggested that these changes occur because the infant is being chronically deprived of an important external regulator of stimulation (the mother) and thus fails to develop emotion regulation or organized behavioral and physiological rhythms Finally, individual differences were discussed, including those related to maturity (eg, prematurity) and temperament/personality (eg, uninhibited/inhibited or externalizing/internalizing) and those deriving from degree of mother-infant mismatch, such as dissimilar temperaments Further investigations are needed to determine how long the effects of such early dysregulation endure, how they affect the infant's long-term development, how their effect differs across individuals and across development, and whether they can be modified by early intervention Eventually, with increasing age, developing skills, and diversity of experience, infants develop individualized regulatory styles That process, and how it is affected by the mother's physical and emotional unavailability, also requires further investigation

Post-traumatic brain hypothermia reduces histopathological damage following concussive brain injury in the rat

Abstract: The purposes of this study were (1) to document the histopathological consequences of moderate traumatic brain injury (TBI) in anesthetized Sprague-Dawley rats, and (2) to determine whether post-traumatic brain hypothermia (30 degrees C) would protect histopathologically. Twenty-four hours prior to TBI, the fluid percussion interface was positioned over the right cerebral cortex. On the 2nd day, fasted rats were anesthetized with 70% nitrous oxide, 1% halothane, and 30% oxygen. Under controlled physiological conditions and normothermic brain temperature (37.5 degrees C), rats were injured with a fluid percussion pulse ranging from 1.7 to 2.2 atmospheres. In one group, brain temperature was maintained at normothermic levels for 3 h after injury. In a second group, brain temperature was reduced to 30 degrees C at 5 min post-trauma and maintained for 3 h. Three days after TBI, brains were perfusion-fixed for routine histopathological analysis. In the normothermic group, damage at the site of impact was seen in only one of nine rats. In contrast, all normothermic animals displayed necrotic neurons within ipsilateral cortical regions lateral and remote from the impact site. Intracerebral hemorrhagic contusions were present in all rats at the gray-white interface underlying the injured cortical areas. Selective neuronal necrosis was also present within the CA3 and CA4 hippocampal subsectors and thalamus. Post-traumatic brain hypothermia significantly reduced the overall sum of necrotic cortical neurons (519 +/- 122 vs 952 +/- 130, mean +/- SE, P = 0.03, Kruskal-Wallis test) as well as contusion volume (0.50 +/- 0.14 vs 2.14 +/- 0.71 mm3, P = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

The personal style inventory: Preliminary validation studies of new measures of sociotropy and autonomy

Abstract: We conducted five studies with depressed patients, demographically matched controls, and college students to develop and psychometrically evaluate new measures of concerns about interpersonal relationships (sociotropy) and autonomous achievement (autonomy), constructs that have been proposed to confer vulnerability to depression. The final version of the Personal Style Inventory (PSI) Sociotropy and Autonomy scales showed a good factor structure, internal consistency reliability, and test-retest stability, a low correlation with each other, and weak or no gender differences. Convergent and discriminant validity were examined with respect to depressive symptom levels, the Dependency and Self-Criticism scales of the Revised Depressive Experiences Questionnaire, and a social desirability scale and were generally acceptable. Further evaluations of the construct validity of the PSI are indicated.

The role of the Schwann cell in trophic support and regeneration.

Abstract: Schwann cells show remarkable versatility in undertaking a broad repertoire of functions. Ensheathment and myelination are specifically regulated by contact with axons, and the Schwann cell is centrally. involved in extracellular matrix production in the peripheral nerve trunk. Additional Schwann cell functions include the promotion of both peripheral and central nervous system regeneration, provision of a versatile source of trophic factors, the capacity to remyelinate central nervous system axons, and the restoration of electrophysiological conduction. Since it is now possible to isolate Schwann cells both from neonatal and adult human peripheral nerve, their ability to promote regenerative efforts by many central neurons suggests a role for Schwann cell autografts in influencing central nervous system repair.

A new approach to parathyroidectomy.

Abstract: Objective To decrease the operative time for parathyroidectomy in patients with hypercalcemic (primary) hyperparathyroid disease, a combination of preoperative localization of a parathyroid tumor with an effective nuclear scan (scintigram) and intraoperative monitoring of parathyroid hormone (quick parathyroid hormone measurement) to ensure excision of all hyperfunctioning tissue was studied. Summary Background Data For many years, persistent hypercalcemia after parathyroidectomy (3% to 10%) has been constant and is usually due to the surgeon's failure to remove all hyperfunctioning glands. A marked decrease in parathormone level after excision of a single large gland predicts operative success and a return to normal calcium levels