Showing papers by "University of Pittsburgh published in 1976"

Short-term memory limitations in children: Capacity or processing deficits?

Abstract: This paper evaluates the assertion that short-term memory (STM) capacity increases with age. Initially an analysis is made of the STM system in terms of its parameters and control processes. No evidence was found that can suggest conclusively that either the capacity or the rate of information loss from STM varies with age. On the other hand, substantial evidence exists to show that the processing strategies used by adults are unavailable or deficient in children. Furthermore, considerable differences in the contents and complexity of the long-term memory (LTM) knowledge base (semantic and recognition networks can produce grossly different STM performance between age groups. The second half of this paper reviews three STM-related paradigms—memory span, serial probed recall, and recognition under limited exposure—that have consistently shown performance deficits in children. These deficits are explained in terms of the lack of proper control processes (or processing strategies), as well as an impoverished LTM knowledge base rather than a limitation in STM capacity.

Ion transport by rabbit colon. I. Active and passive components.

Abstract: Descending rabbit colon, stripped ofmuscularis externa, absorbs Na and Cl under short-circuit conditions and exhibits a residual ion flux, consistent with HCO3 secretion, whose magnitude is approximately equal to the rate of active Cl absorption. Net K transport was not observed under short-circuit conditions. The results of ion replacement studies and of treatment with ouabain or amiloride suggest that the short-circuit currentI sc is determined solely by the rate of active Na transport and that the net movements of Cl and HCO3 are mediated by a Na-independent, electrically-neutral, anion exchange process. Cyclic AMP stimulates an electrogenic Cl secretion, abolishes HCO3 secretion but does not affect the rate of Na absorption under short-circuit conditions. Studies of the effect of transepithelial potential difference on the serosa-to-mucosa fluxesJ sm i of Na, K and Cl suggest thatJ sm Na ,J sm K and one-third ofJ sm Cl may be attributed to ionic diffusion. The permeabilities of the passive conductance pathway(s) are such thatPK∶PNa∶PCl=1.0∶0.07∶0.11. Electrolyte transport byin vitro rabbit colon closely resembles that reported fromin vivo studies of mammalian colon and thus may serve as a useful model for the further study of colonic ion transport mechanisms.

Crystal structure of cholesterol monohydrate

Abstract: CHOLESTEROL, almost water insoluble, normally occurs in the body bound to lipoprotein, or incorporated in lipid aggregations such as bile micelles, or within certain biomembranes. When cholesterol levels are abnormally high, single crystals of the monohydrate tend to deposit; in bile, clumps of these crystals form gallstones1. Crystals of cholesterol monohydrate also occur in atherosclerotic lesions2. Earlier reports of crystal data for cholesterol monohydrate are not all consistent, although they indicate a structure of unusual complexity (refs 1, 3–5 and S. H. Kim and W. Warrant, personal communication). The crystal structure (Fig. 1)has now been determined by a molecular replacement method which was developed primarily for protein crystallography6.

Factors Influencing Innovation Success at the Project Level

Abstract: (1976). Factors Influencing Innovation Success at the Project Level. Research Management: Vol. 19, No. 3, pp. 15-20.

Maternal tasks in pregnancy.

Abstract: The directional goals which women strive towards during pregnancy are fourfold and seem to provide the basic framework of motivation in maternal behaviour. Two of the four tasks are directed toward the outer world during pregnancy on behalf of her child: ensuring safety and acceptance of her unborn child. The other two tasks are directed toward the formation of the maternal role and relationship: developing the capacity to give and binding-in to the as yet unborn child. The progression in pursuit of these tasks is directly related to the progress of pregnancy.

Hyperphagia and increased growth in rats after intraventricular injection of 5,7-dihydroxytryptamine.

Abstract: Juvenile male rats given intracerebroventricular injections of 5,7-dihydroxytryptamine, following treatment with desmethylimipramine, maintained body weight gains of 5 to 6 grams per day into adulthood and grew much larger than control rats. Biochemical analyses of brain tissue obtained 50 to 140 days after the injections revealed 60 to 86% depletions of telencephalic 5-hydroxytryptamine, with catecholamine levels unchanged. Hyperphagia did not develop despite comparable losses of 5-hydroxytryptamine when the pretreatment was withheld, perhaps because substantial depletions of norepinephrine occurred as well.

Food Additives and Hyperkinesis: A Controlled Double-Blind Experiment

Abstract: A double-blind crossover trial involving a control diet and a diet eliminating artificial flavors, colors, and natural salicylates as recommended by Feingold was conducted on 15 hyperkinetic children. Teachers and parents observed the children for one month prior to treatment, using standardized rating scales. Both parents and teachers reported fewer hyperkinetic symptoms on the K-P diet as compared to the pretreatment baseline. The teachers noted a highly significant reduction of symptoms on the K-P diet as compared to the control diet but the parents did not. The control diet ratings did not differ from the baseline period ratings for either parents or teachers. It is concluded that the K-P diet may reduce hyperkinetic symptoms, though this result is put forth with caution in view of several features inherent in the present study which need further evaluation, including objective measures of change, manipulation of the independent variable, and reducing the independent variable to more specific components.

Approaches to Multicultural Education in the United States: Some Concepts and Assumptions

Abstract: Review of the literature on multicultural education within the United States reveals that program proponents have provided no systematic delineation of the views. To promote conceptual clarity and to bring some order to the field's broad scope, the author suggests that extant programs can be organized into four approaches. Analysis stems primarily from the anthropological literature on acculturation, ethnicity, and cultural pluralism. A fifth approach is offered that builds upon anthropological definitions of both education and culture and provides one basis for the evaluation of the other four approaches.

Conflict, cooperation and trust in three power systems

Abstract: The central variables of power, conflict, cooperation and trust have traditionally been employed in a context-irrelevant fashion as general theoretical explanations for many social phenomena at the levels of organisms or persons, groups, organizations, societies and even supranational systems. This paper questions the assumed high cross-system applicability of these concepts by outlining three different prototypical power systems which seem to find frequent expression in everyday life: the unilateral power system, in which a strong source imposes influence on a weak target; the mixed power system, in which partially equivalent interactants bargain to agreement or deadlock; and the bilateral power system, in which interactants are in unit relation and formulate joint policy programs. Power, conflict, cooperation and trust are all found to require substantially different definition and treatment when considered in one as opposed to another of these prototypical systems. A context sensitive approach to conflict research is recommended, in which concepts are articulated with specific regard for the interactional system in which they will be applied. A preliminary effort is made to outline the nature of the variables in each system, allowing the treatment of existing as well as new, e.g., love and hate, topics as valid influence foci while maintaining a good consonance of theoretical expression with social experience. More generally, the dual issues of a bias toward context-irrelevant theory coupled with unrepresentative empirical forays are suggested as potentially debilitating problems for every subdiscipline concerned with social inquiry.

Maisonneuve fracture of the fibula.

Abstract: Study of seventeen cases of Maisonneuve fracture established that there are five stages in the development of a complete lesion. A strong external-rotation force with the foot in slight supination is thought to be responsible for the initial stages; this may change to neutral or slight pronation in the later stages. This is a severe injury to the ankle, which includes complete diastasis of the distal tibiofibular syndesmosis and often rupture of the anteromedial joint capsule and deltoid ligament or fracture of the medial malleolus. Surgical treatment is necessary in later stages.

Modularization and hierarchy in a family of operating systems

Abstract: This paper describes the design philosophy used in the construction of a family of operating systems. It is shown that the concepts of module and level do not coincide in a hierarchy of functions. Family members can share much software as a result of the implementation of run-time modules at the lowest system level.

Calcium-independent modulation of cyclic GMP and activation of guanylate cyclase by nitrosamines.

Abstract: Nitrosamines markedly increase concentrations of guanosine 39, 59 - monophosphate (cyclic GMP) in several tissues from the rat and in human colonic mucosa. These agents are effective in the absence of extracellular calcium and enhance guanylate cyclase activity in tissue homogenates. Stimulation of cyclic GMP was greatest in liver, where the carcinogenic activity of nitrosamines is also most pronounced.

Role of Insulin, Thyroxin and Cortisol in Luteinization of Porcine Granulosa Cells Grown in Chemically Defined Media

Abstract: In order to determine the exact hormonal requirements for luteinizationin vitro, porcine granulosa cells obtained from small (1-2 mm), medium (3-5 mm) and large (6-12 mm) follicles were grown in serum-free media in the presence of various combinations of luteinizing hormone (LH), follicle stimulating hormone (FSH), insulin, cortisol and thyroxin. Morphology as well as progestin secretion was monitored throughout an 8-10 day culture period. The cells were grown in either medium “199D,” which consisted of medium 199 plus 0.4 percent bovine serum albumin (BSA) and 0.2 percent lactalbumin hydrolysate, or the serumless medium of Neuman and Tytell (“SMD”), which already contains 0.2 percent lactalbumin hydrolysate, plus 0.4 percent BSA. Additional cells were grown in the presence of 15 percent pig serum in a balance of medium 199 (medium Y). Cell adherence to the glass and cell maintenance were both less in the serum free media compared to serum-containing medium V. In contrast, progestin secretion expressed per cell was consistently greater when the cells were grown in serum-free compared to serum-containing medium V. Cells harvested from large follicles were able to secrete more progestin compared to cells obtained from small or medium-sized follicles in both types of serum-free media. If cells were grown in serum-free media, addition of 1 mU/mI insulin had some stimulatory (50-200 percent) action upon cell maintenance as well as a small, slow developing stimulatory action upon progestin secretion. The insulin treatment led to an increase in cytoplasmic vacuoles and lipid droplets. Addition of either iO’� M triiodothyronine or thyroxine or 0.01 Mg/mI cortisol along with 1.0-10 mU/mI insulin led to a 3-5 fold stimulation of progestin secretion by cells harvested from small and large follicles. The thyroxin in combination with insulin brought about an increase in oil red 0 and hematoxylin and eosin stainable material present within the cytoplasmic. The cortisol brought about an increase in distinctness of nucleolar material. Addition of either cortisol or thyroxin in the absence of insulin consistently brought about cellular necrosis. In cultures of cells grown in serum-free medium obtained from small follicles, addition of a mixture of 0.1 jig/mI human LH plus 0.1 jig/mI human FSH, 1.0 mU/mI insulin plus either i07 M thyroxin or 0.01 Mg/mI cortisol brought about morphological luteinization and a 4-14 fold increase in progestin secretion above when LH and FSH were added alone. The LH and FSH failed to bring about full morphological luteinization in the absence of these hormones. Addition of a complete mixture of all these hormones brought about the best morphological luteinization and stimulation in progestin secretion. It can be concluded that spontaneous and LH- and FSH-induced granulosa cell luteinization in serum-free culture media is enhanced by the inclusion of a mixture of insulin, cortisol and thyroxin.

Cancer experience among coke by‐product workers

Abstract: This paper presents the site-specific cancer mortality, 1953-1966, for men employed in by-product coke plants in Allegheny County, Pa. Approximate relative risks, which take into account race, age, and calendar years of follow-up, have been calculated for various work areas of the coke plant. The major findings are: 1. As indicated previously by Lloyd and Redmond, men with five or more years at the coke ovens have an excess risk of dying from lung cancer and kidney cancer. 2. Cancers of the digestive system are significantly elevated in nonoven workers. Cancers of two sites, the colon and pancreas, account for the total excess in cancers of the digestive system. 3. Cancers of the buccal cavity and pharynx appear high in nonoven workers, although the number of deaths involved is small. These observations clearly indicate the need to consider nonoven as well as oven workers when evaluating cancer hazards in the coke plant.

Myopic Approximations for the Perishable Inventory Problem

Abstract: Recent work in describing optimal ordering policies for perishable inventory casts the problem as a multi-dimensional dynamic program, the dimensionality being one less than the useful lifetime of the product, m. As m becomes large the computational problem becomes severe so that developing approximations is a key problem. A bound on the perishing cost is obtained that is a function only of the total inventory on hand. Substituting this bound and an approximate transfer function, optimal policies can be computed myopically for the new problem. When the demand density possesses a monotone likelihood ratio, it is shown the function to be minimized is strictly pseudo-convex. Sample computations for special cases indicate that the approximation results in costs which are generally less than one percent higher than the optimal.

The Watson-Crick Model and Reductionism

Abstract: There are a number of interrelated problems that cluster around the issue of reduction in the sciences. The logical analysis of theory, the meaning of theoretical terms, the nature of scientific explanation, and various theses concerning the nature of scientific progress, are all closely connected with the problem of intertheoretic reduction. The recent influential and important works of T. S. Kuhn (1962) and P. Feyerabend (1962) are a testimony to the centrality of the analysis of reduction in philosophy of science.

The effects of ovariectomy, estrogen replacement, and neuraminidase treatment on the properties of the adenohypophysial glycoprotein hormones of the Rhesus monkey.

Abstract: A comparison of pituitary extracts from intact and ovariectomized monkeys revealed that, like FSH, LH from ovariectomized animals is larger in average apparent molecular size and disappears from the circulation of test rats less rapidly than does LH from intact females. In contrast, ovariectomy had no effect on the apparent molecular size of TSH nor on its disappearance rate following injection into test rats. Reversal of the effect of ovariectomy on the molecular size of both LH and FSH was achieved by the chronic administration of estradiol. The differences in apparent molecular size of gonadotropins from intact and ovariectomized monkeys were either reduced or abolished by digestion with the enzyme neuraminidase. These findings suggest that the qualitative changes in the gonadotropins consequent to ovariectomy represent a specific response to the removal of estrogen and are consonant with the view that this phenomenon involves changes in the sialic acid content of the gonadotropins. (Endocrinology 98: ...

Bubble swarm characteristics in bubble columns

Abstract: New correlations have been proposed for estimation of gas phase holdup, characteristic velocity, interfacial area for mass transfer and mean bubble size of bubble swarms under dispersed and fluidized operation of bubble columns employing single — and multi-orifice distributors. The analysis of results include available literature data of other investigators.

Anesthetic Management of Posterior Fossa Surgery in the Sitting Position

Abstract: From the surgical aspect, the sitting position gives good surgical access to the operative site, improves venous drainage, gives a better view of facial area for monitoring evoked responses from cranial nerve stimulation and allows for better ventilation. Conversely, the sitting position can present complications such as air emboli, postural hypotension and serious cardiac arrhythmias due to surgical stimulation of cranial nerves and brainstem. This paper presents our clinical experience in 180 neurosurgical procedures on the posterior fossa in the sitting position. The standardized anesthetic technique consisted of narcotic, muscle relaxant, nitrous oxide and controlled ventilation. All patients were monitored with ECG, direct arterial and venous pressure, discontinuous blood gases, and expiratory CO2 and urinary output. Air embolism was detected via Doppler ultrasonic detector and evacuated through a right atrial catheter. Air was detected, visualized and aspirated in 45 cases for an incidence of 25%, with most episodes occurring early in the procedure. In 11 cases (6%) air was detected on closure. There were no deaths in this series. Fifty-eight patients (32%) had a 10-20 mmHg drop in blood pressure on reaching the sitting position, 19 became temporarily hypertensive (10.5%), and the remainder were normotensive. In 46 patients (25%), bradycardia developed during retraction-manipulation-stimulation of structures on or adjacent to brainstem as well as to cranial nerves. Surgical stress also accounted for the 13 patients (7%) having frequent premature ventricular extrasystoles. One case of profound hypotension and another case of virtual cardiac standstill were noted during the use of the bipolar electrocautery at or near the fifth nerve exit from brainstem. Additional hemodynamic data, the physiopathology, diagnosis and treatment of air embolism is discussed.