Showing papers by "Boston University published in 1984"

Business Unit Strategy, Managerial Characteristics, and Business Unit Effectiveness at Strategy Implementation

Abstract: Data from 58 strategic business units (SBUs) reveal that greater marketing/sales experience, greater willingness to take risk, and greater tolerance for ambiguity on the part of the SBU general manager contribute to effectiveness in the case of “build” SBUs but hamper it in the case of “harvest” SBUs.

Projections to the frontal cortex from the posterior parietal region in the rhesus monkey.

Abstract: The projections to the frontal cortex from the various subdivisions of the posterior parietal region in the rhesus monkey were studied by means of autoradiographic technique. The rostral superior parietal lobule (area PE) projects to the dorsal areas 4 and 6 on the lateral surface of the frontal lobe as well as to the supplementary motor area (MII) on its medial surface. The caudal area PE sends its connections to dorsal area 6 and MII. The projections from the medial parietal cortex (areas PEc and PGm) are similar to those of the superior parietal lobule but they tend to concentrate in the more rostral part of dorsal area 6, MII, and in the cingulate gyrus (area 24). The most caudal part of the medial parietal cortex also projects to area 8. The anteriormost part of the inferior parietal lobule (area PF) projects to the ventral area 6, including the caudal bank of the lower branch of the arcuate sulcus, to the ventral area 46 below the sulcus principalis, and to the frontal and pericentral opercular cortex. The middle inferior parietal lobule (areas PFG and PG) projects to the ventral part of area 46 and area 8, whilst the posteriormost inferior parietal lobule (caudal PG and area Opt) is connected with both dorsal and ventral area 46, dorsal area 8, as well as the anteriormost dorsal area 6, and the cingulate gyrus (area 24).

Deregulation and bank financial policy

Abstract: The standard view that banks can value maximize by exploiting non-risk-rated deposit insurance ignores the potential loss of a valuable bank charter due to insolvency. Recognition of this effect changes the bank's optimal financial policy and can induce extreme risk-averting as well as risk-taking behavior. However, as the value of the bank charter falls, the risk-taking strategy is more apt to dominate. Therefore, current deregulation of the banking industry, by easing entry and devaluing charters, holds the potential for increases in the incidence of insolvency unless offsetting policies are instituted.

Phenomenological methodology in the human sciences.

Abstract: The author suggests that phenomenological methodology differs from traditional methodologies both in purpose and procedure. The task of a phenomenological researcher is to “see” the logic or meaning of an experience, for any subject, rather than to discover causal connections or patterns of correlation. The nature of the task demands extensive study of a small sample, allowing the subjects to speak for themselves and to reveal the logic of their experience as lived. The author reviews verification procedures relevant to phenomenological studies and discusses the limitations inherent in phenomenological research.

Biological communities at the Florida escarpment resemble hydrothermal vent taxa.

Abstract: Dense biological communities of large epifaunal taxa similar to those found along ridge crest vents at the East Pacific Rise were discovered in the abyssal Gulf of Mexico. These assemblages occur on a passive continental margin at the base of the Florida Escarpment, the interface between the relatively impermeable hemipelagic clays of the distal Mississippi Fan and the jointed Cretaceous limestone of the Florida Platform. The fauna apparently is nourished by sulfide rich hypersaline waters seeping out at near ambient temperatures onto the sea floor.

Control of extracellular potassium levels by retinal glial cell K+ siphoning

Abstract: Efflux of K+ from dissociated salamander Muller cells was measured with ion-selective microelectrodes. When the distal end of an isolated cell was exposed to high concentrations of extracellular K+, efflux occurred primarily from the endfoot, a cell process previously shown to contain most of the K+ conductance of the cell membrane. Computer simulations of K+ dynamics in the retina indicate that shunting ions through the Muller cell endfoot process is more effective in clearing local increases in extracellular K+ from the retina than is diffusion through extracellular space.

Accurate estimation of the number of tuples satisfying a condition

Abstract: We present a new method for estimating the number of tuples satisfying a condition of the type attribute rel constant, where rel is one of "=", ">", "

Subarachnoid and intracerebral hemorrhage: natural history, prognosis, and precursive factors in the Framingham Study.

Abstract: No uniformly accepted hypothesis explains the genesis and rupture of intracranial aneurysms. We followed 5,184 men and women prospectively for 26 years; 36 cases of aneurysmal subarachnoid hemorrhage (SAH) accounted for 62% of all intracranial hemorrhages. Blood pressure before SAH was higher in these patients than in controls. Definite hypertension (greater than or equal to 160 mm Hg and/or greater than or equal to 95 mm Hg) at entry to the study or at closest exam before SAH was more frequent than in controls. Cigarette smoking, particularly heavy smoking, was also more frequent among cases.

The pilot Stroke Data Bank: definition, design, and data.

Abstract: Four university centers collaborated to contribute 1158 patients with acute episodes of cerebrovascular disease to the pilot Stroke Data Bank, initiated by NINCDS in 1978. During the pilot project a standard set of data collection forms were developed and used at each of the collaborating centers. Data on clinical course, laboratory findings, therapy and outcome were gathered prospectively throughout the patient's hospitalization and at specified follow-up intervals. Using operational definitions of stroke sub-types, consecutive cases were systematically allocated to specific categories of brain and vascular pathology. The definitions were based on clinical criteria as well as on laboratory data, including computerized tomography (CT), and angiography findings. This paper describes the pilot Stroke Data Bank and presents the distribution of cases by diagnostic and demographic categories. It represents one of the largest series of prospectively collected stroke cases studied by CT (90% of the cases) and angiography (42%). Based upon the methods and processes of this pilot study, a main phase of the Stroke Data Bank has been established to address a number of questions pertaining to stroke classification, evolution, diagnosis, and prognosis.

Photoreceptor excitation and adaptation by inositol 1,4,5-trisphosphate

Abstract: A central question concerning vision is the identity of the biochemical pathway that underlies phototransduction. The large size of the ventral photoreceptors of Limulus polyphemus renders them a favourite preparation for investigating this problem1. The fact that a single photon opens approximately 1,000 ionic channels in these photoreceptors2,3 suggests the need for an internal transmitter. We have investigated whether inositol 1,4,5-trisphosphate (InsP3) functions as such an internal transmitter, given that InsP3 may act as an intracellular messenger in other cellular processes4,5. Here we report that in Limulus, intracellular pressure injection of InsP3 both excites and adapts ventral photoreceptors in a manner similar to light.

Direct connections of rat visual cortex with sensory, motor, and association cortices

Abstract: Each division of rat visual cortex, areas 17, 18a, and 18b, has connections with sensory, motor, and association cortices. These corticocortical connections were sampled using anterograde autoradiographic and retrograde horseradish peroxidase labeling techniques. Area 17 is connected via reciprocal pathways with each division of visual cortex, the posterior one-third of motor area 8, association area 7, and posteroventral area 36 of temporal cortex. It also receives projections from perirhinal areas 13 and 35. Area 18a has reciprocal connections with areas 17 and 18b, a patch in posterior somatosensory area 3, and dorsal auditory area 41. Like area 17, area 18a receives afferents from and projects to the posterior one-third of motor area 8. The connections of area 18a with association cortices are extensive; these regions include parietal areas 7, 39, 40, and 14, posteroventral and dorsal area 36, and perirhinal cortex. Area 18b is connected with areas 17 and 18a, a patch in medial area 3, and dorsal area 41. There are reciprocal projections between area 18b and posterior area 8. As for association cortex, area 18b projects to frontal area 11, area 7, posteroventral and dorsal area 36, and perirhinal cortex. In addition, area 18b receives input from and projects efferents to the dorsal claustrum. Most of the interconnections among areas 17, 18a, and 18b originate from neurons in layers II, III, and V and end in terminal fields in layers I–III and V. In contrast, projections of other sensory, motor, and association cortices to visual cortex originate mainly from neurons in layer V and to a lesser extent from layer II. The reciprocal pathways from visual cortex terminate predominantly in the supragranular layers. In conclusion, these corticocortical pathways provide the basis for cortical visuosensory and visuomotor integration that may aid the rat in the coordination of visually guided behaviors.

Further observations on parieto-temporal connections in the rhesus monkey.

Abstract: The origin, course, and termination of parieto-temporal connections in the rhesus monkey were studied by autoradiographic techniques. The caudal third of the inferior parietal lobule (including the adjacent lower bank of the intraparietal sulcus) is the chief source of these projections. It projects to three separate architectonic areas in the superior temporal sulcus and to three different areas on the ventral surface of the temporal lobe: the parahippocampal gyrus, presubiculum, and perirhinal cortex. The mid-inferior parietal lobule and medial surface of the parietal lobe, by contrast, project only to the caudal upper bank of the superior temporal sulcus. The rostral inferior parietal lobule and the superior parietal lobule, as well as the postcentral gyrus and rostral parietal operculum, do not project to the temporal lobe. Fibers travel from the posterior parietal region to temporal cortex by way of several different routes. One fiber bundle courses in the superior temporal gyrus and terminates in the superior temporal sulcus. Another proceeds ventrally, between the depth of the superior temporal sulcus and the geniculocalcarine tract, to the parahippocampal area. A separate bundle, coursing part of the way in the company of the cingulum bundle, conveys posterior parietal fibers to the presubiculum.

Nuclearites—a novel form of cosmic radiation

Abstract: E. Witten (personal communication) has raised the intriguing possibility that nuclear matter consisting of aggregates of up, down and strange quarks in roughly equal proportions may be less massive than ordinary nuclear matter of the same quark number consisting of protons and neutrons (triplets of non-strange quarks). These nuggets of strange quark matter may be stable for almost any baryon number (A), including values intermediate between those of ordinary nuclei (A≲263) and neutron stars (A ∼ 1057). We use the term ‘nuclearite’ to describe such strange quark nuggets in collision with Earth and suggest experiments to detect these encounters.

Neural dynamics of brightness perception: features, boundaries, diffusion, and resonance.

Abstract: A real-time visual processing theory is used to unify the explanation of monocular and binocular brightness data. This theory describes adaptive processes which overcome limitations of the visual uptake process to synthesize informative visual representations of the external world. The brightness data include versions of the Craik-O’Brien-Cornsweet effect and its exceptions, Bergstrom’s demonstrations comparing the brightnesses of smoothly modulated and step-like luminance profiles, Hamada’s demonstrations of nonclassical differences between the perception of luminance decrements and increments, Fechner’s paradox, binocular brightness averaging, binocular brightness summation, binocular rivalry, and fading of stabilized images and ganzfelds. Familiar concepts such as spatial frequency analysis, Mach bands, and edge contrast are relevant but insufficient to explain the totality of these data. Two parallel contour-sensitive processes interact to generate the theory’s brightness, color, and form explanations. A boundary-contour process is sensitive to the orientation and amount of contrast but not to the direction of contrast in scenic edges. It generates contours that form the boundaries of monocular perceptual domains. The spatial patterning of these contours is sensitive to the global configuration of scenic elements. A feature-contour process is insensitive to the orientation of contrast, but is sensitive to both the amount of contrast and to the direction of contrast in scenic edges. It triggers a diffusive filling-in reaction of featural quality within perceptual domains whose boundaries are dynamically defined by boundary contours. The boundary-contour system is hypothesized to include the hypercolumns in visual striate cortex. The feature-contour system is hypothesized to include the blobs in visual striate cortex. These preprocessed monocular activity patterns enter consciousness in the theory via a process of resonant binocular matching that is capable of selectively lifting whole monocular patterns into a binocular representation of form-and-color-in-depth. This binocular process is hypothesized to occur in area V4 of the visual pre striate cortex.

Scaling Approach for the Kinetics of Recombination Processes

Abstract: A scaling theory is developed to describe the time evolution of the irreversible diffusive recombination process $A+B\ensuremath{\rightarrow}\mathrm{inert}$. Fluctuations are shown to alter radically the decay laws predicted from the rate-equation approach. For unequal initial densities, the minority species is predicted to decay as ${t}^{\ensuremath{-}\ensuremath{\alpha}}$ for short times, crossing over to an $\mathrm{exp}(\ensuremath{-}A{t}^{\ensuremath{\alpha}})$ decay for long times, with $\ensuremath{\alpha}=\frac{d}{4}$ and $\ensuremath{\alpha}=\frac{(d+1)}{4}$ for unbiased and biased diffusion, respectively.

Contingency Linkages Between Strategy and General Manager Characteristics: A Conceptual Examination

Abstract: Prior research relating general manager characteristics to organizational strategy has (a) tended to operationalize these characteristics in vague and untestable terms; (b) focused almost solely on the implications of differences in business unit level strategic mission; and (c) rarely examined strategy-general manager linkages in the context of a key criterion variable, namely, effectiveness. This paper develops specific testable propositions that link six managerial characteristics to strategy and effectiveness at two hierarchical levels: corporate and strategic business unit.

Regional specialization of retinal glial cell membrane.

Abstract: Neural activity generates increases in extracellular K+ concentration, [K+]0, which must be regulated in order to maintain normal brain function1. Glial cells are thought to play an important part in this regulation through the process of K+ spatial buffering2–4: K+-mediated current flow through glial cells redistributes extracellular K+ following localized [K+]0 increases. As is the case in other glia, the retinal Muller cell is permeable almost exclusively to K+ (ref. 5). Recent experiments6–8 have suggested that this K+ conductance may not be distributed uniformly over the cell surface. In the present study, two novel techniques have been used to assess the Muller cell K+ conductance distribution. The results demonstrate that 94% of all membrane conductance lies in the endfoot process of the cell. This strikingly asymmetric distribution has important consequences for theories concerning K+ buffering and should help to explain the generation of the electroretinogram.

An autoradiographic study of the mouse olfactory epithelium: Evidence for long-lived receptors

Abstract: In order to try to determine whether differentiated olfactory receptors turn over (die and are replaced by newly differentiated cells) during adult life, mice were injected with a single dose of 3H-thymidine at either 2 or 4 months of age and allowed to survive for up to 12 months; they were caged in a laminar flow unit to prevent rhinitis. Counts of labeled receptor cells detected autoradiographically after injection at 2 months of age revealed that, following an initial decrease from 1 to 3 months of survival, numbers of labeled cells remained approximately constant, at least up to 12 months of survival. Cells still labeled at 12 months of survival were confirmed as receptor cells by electron microscopic examination of reembedded sections. The hypothesis is suggested that in the absence of disease-related destruction of the olfactory epithelium, most or all receptor cell turnover represents newly formed cells that fail to establish synapses with the olfactory bulb; fully differentiated receptor cells may be quite long-lived.

Uncoupling by Acetic Acid Limits Growth of and Acetogenesis by Clostridium thermoaceticum.

Abstract: When cells of the anaerobic thermophile Clostridium thermoaceticum grow in batch culture and homoferment glucose to acetic acid, the pH of the medium decreases until growth and then acid production cease, at about pH 5. We postulated that the end product of fermentation limits growth by acting as an uncoupling agent. Thus, when the pH of the medium is low, the cytoplasm of the cells becomes acidified below a tolerable pH. We have therefore measured the internal pH of growing cells and compared these values with those of nongrowing cells incubated in the absence of acetic acid. Growing cells maintained an interior about 0.6 pH units more alkaline than the exterior throughout most of batch growth (i.e., ΔpH = 0.6). We also measured the transmembrane electrical potential (ΔΨ), which decreased from 140 mV at pH 7 at the beginning of growth to 80 mV when the medium had reached pH 5. The proton motive force, therefore, was 155 mV at pH 7, decreasing to 120 mV at pH 5. When further fermentation acidified the medium below pH 5, both the ΔpH and the ΔΨ collapsed, indicating that these cells require an internal pH of at least 5.5 to 5.7. Cells harvested from stationary phase and suspended in citrate-phosphate buffer maintained a ΔpH of 1.5 at external pH 5.0. This ΔpH was dissipated by acetic acid (at the concentrations found in the growth medium) and other weak organic acids, as well as by ionophores and inhibitors of glycolysis and of the H+-ATPase. Nongrowing cells had a ΔΨ which ranged from about 116 mV at external pH 7 to about 55 mV at external pH 5 and which also was sensitive to ionophores. Since acetic acid, in its un-ionized form, diffuses passively across the cytoplasmic membrane, it effectively renders the membrane permeable to protons. It therefore seems unlikely that mutations at one or a few loci would result in C. thermoaceticum cells significantly more acetic acid tolerant than their parental type.

Outcome assessment in clinical trials. Evidence for the sensitivity of a health status measure.

Abstract: Health status measures are conceptually relevant to the assessment of clinical outcome in the rheumatic diseases, but their ability to detect meaningful changes in health has not been clearly demonstrated. This report describes the performance of a self-administered health status questionnaire in a randomized, double-blind, 21-week comparison of placebo, oral gold, and injectable gold in rheumatoid arthritis patients. Outcome was assessed by standard clinical measures, including joint count, grip strength, and laboratory tests, and by the Arthritis Impact Measurement Scales, a reliable and valid health status measure that assesses physical disability, psychological status, and pain. Data from the clinical and health status measures produced highly similar conclusions: injectable and oral gold are more effective than placebo for rheumatoid arthritis, and injections are slightly more effective than oral gold. The health status measure was thus quite sensitive to clinically meaningful drug-induced improvements. These findings provide justification for the further application of health status measures to clinical trials of chronic disease.

Predicting the vocational capacity of the chronically mentally ill. Research and policy implications.

Abstract: In response to the growing recognition that adequately trained personnel and appropriate in- tervention techniques were not available to meet the rehabilitation needs of psychiatrical ly disabled per- sons, the first Rehabilitation Research and Training Center in Mental Health was established in August 1979. Because the Center's mandate is to focus on problems of national scope and because the chronically mentally ill have recently been severely adversely af- fected by Social Security Administration actions that have terminated disability benefits, a review of the research literature surrounding the vocational capacity of psychiatrical ly disabled persons was undertaken. This article details results of that review, identifies needed research in the area of employability of the chronically mentally ill, and notes implications for policy.

Nucleus Raphe Dorsalis in Dementia of the Alzheimer Type: Neurofibrillary Changes and Neuronal Packing Density

Abstract: Within the reticulate core of the brain the nucleus raphe dorsalis (NRD) is a major site of predilection for the neurofibrillary tangle (NFT) in dementia of the Alzheimer type (DAT) and, according to some studies, its primary brain stem site. In a quantitative study we have shown in six aged control brains an average of 5.2 NFT per histological section or 25.8 per mm3 and in seven age-matched brains with DAT a highly significant six-fold increase, respectively 35.3 NFT per histological section or 188.5 per mm3. There was no significant difference between the two groups in overall neuronal cell packing density. There was, however, a significant decrease in a subpopulation of neurons in DAT, a large polygonal neuron. Despite the prominence of the NRD as a target for NFT, the actual proportion of affected NRD cells was small, 0.35% in controls and 2.25% in DAT.

Effects of Organizational Structure of Marketing Planning on Credibility and Utilization of Plan Output

Abstract: The authors investigate the effects of the organizational structure used for marketing planning on the credibility and utilization of marketing plans. Data on 53 organizations were obtained from mu...