Showing papers by "University of Pittsburgh published in 1975"

The development of spatial representations of large-scale environments

Abstract: Publisher Summary A series of neurological and philosophical discussions has led to suggestions that space is a model of the environment, constructed from the temporal integration of successive perceptions, which model man as neurologically disposed to create and organize. The model is coordinated to social conventions. It develops and is vulnerable to dissolution. Studies of adults' knowledge about their macroenvironment suggest that human “maps” are not literally maps. Rather, they tend to be fragmented, distorted projectively, and are often several multiple “mini-spatial-representations.” Landmarks and routes are the minimal elements of spatial representation. Survey-representations incorporate configurational elements (outlines, graphic skeletons, figurative metaphors) and may be the final derivative of dense, richly interconnected, and hierarchically organized route maps. The notion of “main sequences” was introduced as a potential explanation for the extensive parallelisms identified among ontogenesis, microgenesis, the course of pathology, and the recovery of function following pathological insult. The development of the sequence of spatial representations in children conforms to the “main sequence” identified in the construction of spatial representation in adults.

Uncertainty relations for information entropy in wave mechanics

Abstract: New uncertainty relations in quantum mechanics are derived. They express restrictions imposed by quantum theory on probability distributions of canonically conjugate variables in terms of corresponding information entropies. The Heisenberg uncertainty relation follows from those inequalities and so does the Gross-Nelson inequality.

Surgical disconnection of the medial basal hypothalamus and pituitary function in the rhesus monkey. I. Gonadotropin secretion.

Abstract: In an intial attempt to localize the central components of the neuroendocrine control systems whereby estrogens regulate gonadotropin secretion, the medial basal hypothalamus (MBH) was surgically isolated from the remainder of the brain in 18 female rhesus monkeys using a modified "Halasz knife". The completeness and localization of the resulting "cuts" were verified by examinations of serial 50 mugM coronal sections through each hypothalamus. The cuts extended from the optic chiasm to the mamillary bodies and from midline to the medial aspects of the optic tracts. The MBH "ISLANDS" ISOLATED BY THESE CUTS INCLUDED THE MEDIAN EMINENCE AND ARCUATE NUCLEI AS WELL AS PORTIONS OF THE VENTROMEDIAL NUCLEI, PREMAMILLARY AREAS AND MAMILLARY BODIES. Following complete MBH isolation, 6 of 7 otherwise intact monkeys responded to an estradiol benzoate (EB) injection with large LH and FSH surges. Three of these animals also displayed spontaneous gonadotropin surges which eventuated in ovulation as evidenced by sustained elevations in circulating progesterone levels. Similar patterns of LH and FSH secretion in response to EB administration were also observed in 6 of 7 intact animals in which only the superofrontal imputs to the MBH WERE INTERRUPTED. Four of these monkeys ovulated spontaneously. Circulating gonadotropin levels fell slightly in ovariectomized monkeys following complete MBH disconnection, but the circhoral, pulsatile rhythms of gonadotropin release persisted. These animals also responded to the negative and positive feedback actions of estrogen as evidenced by initial declines in circulating LH and FSH concentrations followed by surges of these hormones at the appropriate times following the injection of EB. It would appear from these observations that the sites of the negative and positive feedback actions of estrogen on LH and FSH secretion and, therefore, the sites of the central components of the neuroendocrine systems which control tonic and surge secretion of the gonadotropic hormones in the rhesus monkey may be resident within the MBH-hypophysial unit.

Structure of graphite by neutron diffraction

Abstract: THE structure of graphite1 consists of layers of linked hexagons of carbon atoms. The layers are stacked in a ⋯ ABAB ⋯ sequence so that half the atoms in a layer are directly above and below carbon atoms in the adjoining layers, and half are directly above and below centres of the hexagons. The hexagonal unit cell contains atoms at the (0, 0, 1/4), (1/3, 2/3, 1/4), (0, 0,−1/4) and (2/3, 1/3,−1/4) positions. Modifications to this structure have been proposed by several workers. Lukesh2 reported diffraction patterns indicating a lower symmetry, and Pauling3 has proposed an orthorhombic structure in which the interconnected six-membered rings are distorted so that two-thirds of the bonds are longer. Pauling based his model on the high compressibility of the basal planes, and considerations of stacking bonds in the layered structure. Ergun4 suggested that data on pyrolitic graphite indicated an apparent quinoid structure in the graphite layers, but errors in his analysis have been reported5. X-ray and neutron diffraction studies of graphite were undertaken in our laboratory to study the details of the electron charge density and atomic motion in the graphite structure. The results of the neutron diffraction work show that all in plane carbon–carbon distances have the same value 1.422±0.001 A.

Optimal Ordering Policies for Perishable Inventory-II

Abstract: This paper deals with the problem of computing optimal ordering policies for a single product with a lifetime of exactly m periods. Costs are charged against ordering, holding, shortages, and out-dating. To take explicit account of the perishability, we substitute a cost to be incurred at the time of outdating. The functional equation approach of dynamic programming is used to extend this model to the multiperiod case, and the structure of optimal ordering policies is analyzed.

Interpersonal conflict-handling behavior as reflections of Jungian personality dimensions.

Abstract: This study has sought to investigate the Jungian psychological correlates of an individual's choice of different interpersonal conflict-handling modes: competing, collaborating, compromising, avoid...

Tail pinch induces eating in sated rats which appears to depend on nigrostriatal dopamine.

Abstract: Mild tail pinch reliably and rapidly induced eating, gnawing, or licking behavior in all animals tested. Eating was by far the predominant response. Pharmacological analysis of the involvement of the brain catecholamines in tail-pinch behavior suggests that it is critically dependent on the nigrostriatal dopamine system.

Effects of vapor-phase deposition processes on the optical, chemical, and magnetic properties OE the lunar regolith

Abstract: The processes of solar wind sputtering and meteoritic impact vaporization have created materials in the lunar regolith which were deposited from a vapor phase. Although the quantity of such exotic condensed substances should theoretically be comparable with that of materials which have been melted by impacts, their existence in the fines has not been generally recognized. We have investigated the physical and chemical properties of materials deposited from vapors generated by hydrogen-ion sputtering and thermal evaporation of lunar and artificial ferrosilicates. Both processes are highly reducing. The deposits are enriched in Fe, have large, nonselective, optical absorptivities, and contain abundant sub-microscopic, superparamagnetic grains of metallic Fe which exhibit the characteristicg=2.1 ESR resonance. The sputter-deposited films are enriched in heavy elements. Thus the hypothesis that the lunar fines contain several percent of materials deposited from the vapor phase accounts in a natural manner for many of the unusual optical, physical and chemical properties of lunar soils. The vapor-deposits are probably concentrated in the agglutinate particles of the regolith.

DIALOG: a model of diagnostic logic for internal medicine

Abstract: A system for computer assisted medical diagnosis has been developed, which incorporates an innovative model of diagnostic logic. A supporting medical data base has also been assembled, now comprising approximately fifty percent of the major diseases of internal medicine. Using weighted associations between disease entitles and their manifestations, and employing a powerful attention focusing heuristic, the system has demonstrated competence In dealing with difficult clinical problems involving multiple diagnoses.

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.

NORMAL BIOLOGY OF α-FETOPROTEIN

Abstract: Synthesis of a-fetoprotein (AFP) by the human embryo can be detected at least as early as 29 days after conception.' At this stage of development, the liver is little more than-a diverticulum of hepatic buds and ducts, and there is only slight, if any, evidence of lobe formation. Yet, this embryonic .liver can synthesize not only AFP, but a host of other plasma proteins as well, including prealbumin, albumin, a,-antitrypsin, C1-esterase inhibitor, a,-macroglobulin, C3 or &c, 8-lipoprotein, hemopexin and transferrin.? A few days later, at 32 to 35 days after conception, the lobes of the liver can be discerned, and hepatic synthesis of a,-acid glycoprotein and ceruloplasmin becomes apparent.* By 38 to 40 days of gestation, an occasional embryo may demonstrate hepatic synthesis of fibrinogen, but most embryos do not synthesize fibrinogen until about 60 days of gestation.? Thus, early morphologic differentiation of the human liver is accompanied by the development of hepatic plasma protein synthesis. Hepatic synthesis of AFP takes place in the hepa t~cy te .~ The liver, however, is not the only source of AFP in the normal conceptus. At 32 to 35 days of gestation, the amount of AFP produced by the yolk sac rivals that synthesized by the liver.'.' At this stage of development, the yolk sac is a well-defined vesicle attached to the foregut by a narrow stalk, and it produces prealbumin, albumin, a,-antitrypsin and transferrin, among other proteins, in addition to AFP (FIGURE 1); with the exception of albumin, these proteins are synthesized in quantities equal to or even greater than those produced by equivalent amounts of liver from the same embryo. Synthesis of AFP, prealbumin, a,-antitrypsin and transferrin by the yolk sac is significantly decreased at 60 days or 8.5 weeks of gestation (TABLE 1) . By 11.5 weeks of gestation, the yolk sac may be noticeably atretic; its synthesis of prealbumin and a,-antitrypsin may be below detectable limits, and it produces only small amounts of AFP, albumin and transferrin. Thus, during its relatively brief existence as a well-developed structure, the yolk sac of the human conceptus synthesizes a number of plasma proteins, but as degenerative changes occur towards the end of the first trimester or the beginning of the second, the changes are accompanied by a decrease in plasma protein synthesis. In contrast to the relative insignificance of the yolk sac in human development, the yolk sac in the rat fetus and the yolk sac in the chick embryo remain well-developed structures with biologically important functions throughout antenatal development: in the rat, the yolk sac forms one of the fetal membranes and in the chick, the yolk sac envelops and absorbs the yolk necessary to nourish the embryo. The yolk sac in both of these species produces AFP until birth.5, Synthesis of AFP in the human conceptus also takes place in the gastrointestinal tract,, but the quantity produced is very much less than that synthesized by the liver. Trace amounts of AFP may also be produced by the kidneys in an occasional conceptus, or even by the placenta, but synthesis at either site

Optimal stimulation as theoretical basis of hyperactivity.

Abstract: Current theory and practice in the clinical and educational management of hyperactive children recommend reduction of environmental stimulation, assuming hyperactive and distractable behaviors to be due to overstimulation. This paper reviews research suggesting that hyperactive behavior may result from a homeostatic mechanism that functions to increase stimulation for a child experienceing insufficient sensory stimulation. It is suggested that the effectiveness of drug and behavior therapies, as well as evidence from the field of sensory deprivation, further support the theory of a homeostatic mechanism that attempts to optimize sensory input.

The Social Desirability Variable in Organizational Research: An Alternative Explanation for Reported Findings

Abstract: Because questionnaires are quite prevalent in management research, awareness of the effects of social desirability is critical. Data on measures of conflict behavior are presented to illustrate two...

Circulating levels of steroids and chorionic gonadotropin during pregnancy in the rhesus monkey, with special attention to the rescue of the corpus luteum in early pregnancy.

Abstract: Circulating levels of progesterone and estrogen in the pregnant rhesus monkey are indistinguishable from those of the nonpregnant animal until 12 days after the LH peak, when the first significant rise in chorionic gonadotropin (RhCG) levels is noted concomitant with an abrupt elevation in progesterone levels (the corpus Iuteum rescue). Serum RhCG concentration rises rapidly (doubling time = 2 days) to a peak at about day 23 of pregnancy, then falls to undetectable levels at day 35, and remains undetectable throughout the rest of gestation. Serum estrone and estradiol levels rise and fall with RhCG titers in early pregnancy, reaching a nadir on day 35 of gestation before placental estrogen secretion (largely estradiol) supervenes. Circulating estrogens reach a high and variable plateau at about day 80 of pregnancy and rise to maxima on the day prior to parturition. Serum progesterone levels in early pregnancy, while rising abruptly at the outset of RhCG secretion, fall in the face of waxing RhCG titers and increase again only as RhCG levels fall. Ovariectomy on day 23 of pregnancy causes a sharp fall in circulating levels of estrogens and no compromise of the continuation of pregnancy. These data suggest that the order of hormone production by the placenta is RhCG. first discernable at about 10-I I days after ovulation, followed by progesterone, whose secretion by the placenta is initiated prior to day 23 of pregnancy since ovariectomy at this time causes no fall in circulating progesterone levels, and lastly, estradiol and estrone. which rise rapidly in peripheral serum after day 35 of pregnancy. These data support the hypothesis that the shortlived stimulation of progesterone secretion by the corpus luteum in early pregnancy is caused by the initiation of placental RhCG secretion and that the failure of Iuteal progesterone secretion to be maintained in the face of rising RhCG titers may be an expression of the luteolytic effect of the increased luteal estrogen production also stimulated by this gonadotropin.

Effect of Earth's Rotation in Neutron Interferometry

Abstract: In a neutron interferometer experiment which can successfully demonstrate a quantitative fringe shift due to the different gravitational potential for the neutron in the two legs of the apparatus, an adjunctive consideration must be the nonzero angular velocity of Earth and the lab. As in the classic Michelson-Gale-Pearson experiment done with light, and offset in the fringe pattern is predicted. Such a shift may not be subliminal at present precision levels.

Plasma estrone, prolactin, neurophysin, and sex steroid-binding globulin in chronic alcoholic men

Abstract: The feminization frequently observed in men with alcoholic liver disease has not been satisfactorily explained by existing reports. We have measured plasma estrone, prolactin, estrogen-stimulated neuorphysin, and sex steroid-binding globulin concentrations in 50 men with chronic alcoholism and varying degrees of alcoholic liver disease in an effort to further elucidate possible hormonal mechanisms responsible for the observed feminization. Plasma concentrations of each of these parameters were at least two-fold elevated ( p ⪕ 0.01 ) when compared to values obtained for the same steroid or protein in plasma obtained from normal men. The plasma concentrations of estrone and prolactin in men studied with gynecomastia were significantly greater ( p ⪕ 0.01 and p ⪕ 0.05 , respectively) than were the concentrations of these two hormones in those without this physical sign. Similarly, those men with spider angiomata had significantly greater ( p ⪕ 0.01 ) plasma estrone levels than did the men without this cutaneous vascular abnormality. These significant hormone elevations may contribute to the pathogenesis of feminization so frequently observed in chronic alcoholic men.

Magnetocrystalline anisotropy of Sm Co 5 and its interpretation on a crystal-field model

Abstract: Results of magnetization measurements on carefully prepared single crystals of Sm${\mathrm{Co}}_{5}$ are presented over the temperature range 4-970 K. The contribution of the rare-earth sublattice magnetocrystalline anisotropy was evaluated using the data on Y${\mathrm{Co}}_{5}$ as "a blank." These results are interpreted on the basis of a singleion model. The following Hamiltonians were employed to obtain eigenvalues: $\mathcal{H}(\mathrm{parallel}\mathrm{to} c \mathrm{axis})=\ensuremath{\lambda}\stackrel{\ensuremath{\rightarrow}}{\mathrm{L}}\ifmmode\cdot\else\textperiodcentered\fi{}\stackrel{\ensuremath{\rightarrow}}{\mathrm{S}}+{\mathcal{H}}_{\mathrm{CF}}+2{\ensuremath{\mu}}_{B}{S}_{z}{H}_{\mathrm{ex}}$, $\mathcal{H}(\mathrm{perpendicular}\mathrm{to} c \mathrm{axis})=\ensuremath{\lambda}\stackrel{\ensuremath{\rightarrow}}{\mathrm{L}}\ifmmode\cdot\else\textperiodcentered\fi{}\stackrel{\ensuremath{\rightarrow}}{\mathrm{S}}+{\mathcal{H}}_{\mathrm{CF}}+2{\ensuremath{\mu}}_{B}{S}_{x}{H}_{\mathrm{ex}}$. ${H}_{\mathrm{ex}}$ was regarded as arising mainly from the cobalt sublattice. Contributions arising from the multiplets $^{6}H_{\frac{7}{2}}$ and $^{6}H_{\frac{9}{2}}$ to the ground multiplet $^{6}H_{\frac{5}{2}}$ were included. The crystal field was evaluated in terms of Racah's tensor-operator technique employing $3\ensuremath{-}j$ and $6\ensuremath{-}j$ symbols. With the two sets of eigenvalues obtained from the above expressions, the anisotropy energy to rotate the magnetization direction from the axis to the plane was calculated and compared with experimental results on single crystals of Sm${\mathrm{Co}}_{5}$. It is shown that the sign of the crystal-field parameter predicts the correct easy direction of magnetization and that the free-energy values calculated from 4 to 970 K are in reasonable agreement with experiment.

Temperature-sensitive viruses and the etiology of chronic and inapparent infections.

Abstract: Several mechanisms have been put forward to explain how persistently infected virus-carrier cell cultures are maintained. In this report, information is summarized which suggests that selection of temperature-sensitive mutants may be involved in either establishment or maintenance of persistent infections both in cell cultures and in animals. The possible relation of this mechanism to other mechanisms of regulation of persistent infections is also discussed. Finally, a practical suggestion is offered to researchers and clinicians seeking endogenous viruses from cultured cells and tissues that may harbor temperature-sensitive variants.

Photometric observations of Mercury from Mariner 10

Abstract: The elimination of the residual image problem which plagued previous Mariner imaging systems allowed photometry of moderately high quality to be carried out on Mercury by Mariner 10. The conclusions from the photometric analysis are as follows. To a surface resolution of 20 km, Mercury is covered with a dark fine-grained soil similar to the lunar regolith. No regions having anomalous polarization or color were discovered, which might have implied large amounts of metallic Fe or exposed bare rock. Photoclinometry suggests that the center of the Caloris Basin may be about 9 km below the outside rim. The heavily cratered plains have albedos of about 0.17, somewhat brighter than the lunar highlands. The albedos of the darker smooth plains and the interiors of bright fresh craters are systematically higher than their lunar counterparts. One consistent interpretation of the color and albedo relationships is that the dark smooth plains resemble the low-Ti, low-Fe lunar maria and that the crust is generally low in Ti, metallic Fe, and Fe(3+).

The pituitary-gonadal axis in men with protein-calorie malnutrition

Abstract: The pituitary-gonadal axis was studied in 28 men with severe protein-calorie malnutrition in a Calcutta hospital The men were selected for the severity of their malnutrition and for absence of other diseases They had clinical findings of hypogonadism and low total and unbound plasma testosterone During 2-5 months of refeeding there was clinical recovery and increase of plasma testosterone to normal Plasma LH was high in malnutrition, decreased during refeeding, and remained above normal after refeeding Some patients failed to show LH elevation in malnutrition despite low plasma tesosterone Plasma FSH was high in malnutrition, decreased during refeeding, and was near the level of normal Indian men after refeeding HCG 4000 IU im per day for 3 days produced subnormal increments in plasma testosterone both in malnutrition and after refeeding; corresponding decreases in FSH occurred It is concluded that the hypogonadism of protein-calorie malnutrition is primarily on the basis of diminished Leydig cell function Appropriate pituitary LH response is intact in some patients, but is either absent or inadequate in others Subclinical Leydig cell insufficiency, indicated by LH elevation and subnormal response to HCG, persists after refeeding has produced recovery from malnutrition and clinical hypogonadism FSH elevation in malnutrition may be secondary to the reduced Leydig cell function

Ventricular obstruction: effect on drinking induced by intracranial injection of angiotensin.

Abstract: Lesions of the subfornical organ (SFO) severely attenuated drinking induced by injections of angiotensin II into the lateral ventricles, but a few days (4 to 14) later a recovery of the drinking response is observed. A possible explanation for this is that other dipsogenic sites are involved which are beyond the interventricular foramen and that SFO lesions produce an obstruction by edema or debris at the foramen which blocks access of cerebrospinal fluid-borne angiotensin to those sites. This hypothesis is supported by tracer studies and by direct injection into the third ventricle of SFO-lesioned animals. Other studies reported implicate the anteroventral third ventricle as a likely site for angiotensin receptors.

Detection of Cardiac-Specific Creatine Kinase Isoenzyme in Sera with Normal or Slightly Increased Total Creatine Kinase Activity

Abstract: We describe a spectrophotometric kinetic assay for detecting creatine kinase MB isoenzyme activity in the 1 to 10 U/liter range. The MB isoenzyme was isolated [ Clin. Chem. 20, 36 (1974)] and assayed (Rosalki method) with an Abbott ABA-100. Good reproducibility was demonstrated for MB isoenzyme activities near 1 U/liter (CV = 2.6%). Sera with normal or slightly increased total creatine kinase activity were evaluated. Sera of 14 patients with acute myocardial infarction contained, per liter, 84 to 236 U of total creatine kinase activity and 4.6 to 28.0 U of isoenzyme MB activity; corresponding ranges for sera from healthy lab technicians and patients with noncardiac disease were 36 to 277 and 0 to 2.6 U. MB isoenzyme activity for infarction patients rose and fell sharply within three days after the infarction. Atypical time-course patterns, MB isoenzyme activity remaining abnormally great for five days, were observed in serum from patients with prolonged atrial fibrillation and congestive heart failure or cardiomyopathy; the BB isoenzyme (1 to 5 U/liter) was also detected in sera of such patients but was absent in sera from infarction patients. Quantification of column-isolated MB by the assay described is rapid, easy, specific, and extremely sensitive for measuring MB in the 1 to 10 U/liter range.

Persistent pancreatic glucagon but not insulin response to arginine in pancreatectomized dogs.

Abstract: Effects of total pancreatectomy on plasma glucagon, insulin and glucose responses to arginine were determined in 5 dogs. Portal vein and femoral artery samples were obtained in response to an arginine infusion (10 g/30 min) prior to, 1 h, 1 day and 1 week after pancreatectomy. Glucagon was measured using pancreatic-specific antiserum 30K (Unger, Dallas). Before pancreatectomy arginine significantly increased portal vein glucagon from 373 plus or minus 36 to 595 plus or minus 31 pg/ml and femoral artery levels from 233 plus or minus 28 to 342 plus or minus 74 pg/ml. Portal vein and femoral artery insulin concentrations of 74 plus or minus 21 and 17 plus or minus 3 muU/ml increased significantly to 173 plus or minus 64 and 31 plus or minus 7 muU/ml. Glucose levels did not change. One h after pancreatectomy, portal vein glucagon decreased to 121 plus or minus 15 pg/ml but increased to 230 plus or minus 42 pg/ml after arginine. Elevated blood glucose and the necessity for insulin treatment established the adequacy of pancreatectomy. Furthermore portal vein insulin levels were undetectable and unresponsive to arginine or a combination of glucose, glucagon, and tolbutamide 1 week after pancreatectomy. One day after pancreatectomy arginine significantly increased portal vein glucagon from 343 plus or minus 42 to 776 plus or minus 152 pg/ml. One week after pancreatectomy basal glucagon values were 374 plus or minus 30 in the portal vein and 360 plus or minus 49 in the femoral artery and responded to 1226 plus or minus 641 and 825 plus or minus 270 pg/ml, respectively, with arginine. Chromatography of plasma from one pancreatectomized dog on Sephadex G-50 after arginine stimulation revealed that much of the material cross-reacting with antibody 30K was eluted from the column earlier than either 125I-insulin or 125I-glucagon. In contrast, peak glucagon activity in plasma obtained from a normal human given arginine eluted from the column between the peak of 125I-insulin and 125I-glucagon; glucagon added to human plasma also was recovered in this same area between the 125I-insulin and 125I-glucagon peaks. These results suggest that some of the material that reacted with 30K antibody and which increased after pancreatectomy in response to arginine has a molecular weight greater than pancreatic glucagon. At autopsy no pancreatic tissue could be identified. Thus, after pancreatectomy, validated by absent insulin responses, the glucagon response to arginine was normal or increased. Since arginine is not thought to increase intestinal glucagon-like immunoreactive material, the source and nature of the material measured as glucagon after pancreatectomy is unknown, but may be important to any understanding of plasma glucagon measurements.

Glucoregulatory Feeding by Rats after Intraventricular 6-Hydroxydopamine or Lateral Hypothalamic Lesions

Abstract: Rats given intravenricular injections of 6-hydroxydopamine or bilateral electrolytic lesions of the lateral hypothalamus do not show the normal increase in food intake in response to large decreases in glucose utilization or exposure to severe cold stress. However, they will eat more during chronic glucoprivation that is less intense, or during exposure to more moderate cold stress. Thus, the feeding deficits of these lesioned rats may not reflect an inability to respond to certain qualitatively different stimuli, but rather an inability to respond to quantitatively different intensities of the same stimulus.