Showing papers by "University of Pennsylvania published in 1971"
TL;DR: An analysis of phobias using a more contemporary model of fear conditioning is proposed, and a reconstruction of the notion of symbolism is suggested.
1,336 citations
TL;DR: Conjoint measurement is a new development in mathematical psychology that can be used to measure the joint effects of a set of independent variables on the ordering of a dependent variable.
Abstract: Conjoint measurement is a new development in mathematical psychology that can be used to measure the joint effects of a set of independent variables on the ordering of a dependent variable. In this...
1,287 citations
TL;DR: In this paper, both the excitatory potential and the degree of manifest aggressiveness of communications were assessed to select: (a) an aggressive communication associated with a particular excITatory potential; (b) a nonaggressive communication with an excitulatory potential significantly below that of a; and (c) another nonaggressive communications with an eff ective potential significantly above that of an aggressive one.
668 citations
TL;DR: Psychometric functions were determined concurrently for detection of simple gratings and complex gratings, compatible with the assumption that the human visual system contains sensory channels, each selectively sensitive to different narrow ranges of spatial frequencies, whose outputs are detected independently.
Abstract: Psychometric functions were determined concurrently for detection of simple gratings (luminance sinusoidally modulated with spatial frequency f) and complex gratings (luminance modulated by the sum of two sinusoids, with frequencies f and f′). Results were used to test the hypothesis that the two components of a complex grating may be detected independently. In an extensive experiment with f = 14 cycles/deg, the independence hypothesis was consistently rejected only when f/f′=54 or 45, but rarely rejected when the value of f/f′ lay outside this range. In other experiments, f was between 1.9 and 22.4 cycles/deg. All results are compatible with the assumption that the human visual system contains sensory channels, each selectively sensitive to different narrow ranges of spatial frequencies, whose outputs are detected independently.
548 citations
TL;DR: In the present study HZOz was determined by the horse radish peroxidase dependent reaction of HzOZ with the fluorescent dye scopoletine, and a decrease ‘of fluorescence intensity demonstrates directly the decrease in HzOz.
541 citations
TL;DR: The change in mutual impedance ?
Abstract: The change in mutual impedance ?Z resulting from a change ?g in the conductivity of a particular region of a volume conductor is shown to be given by ?Z = - ?g?Lt?·L? dv. L? and L? are the lead fields associated with the two ports used to measure ?Z. The integration is over the region where the conductivity has changed. The superscript t indicates that the lead field is to be evaluated following the change in conductivity. An example involving a spherical conductor is provided.
500 citations
01 Jan 1971
TL;DR: A two-dimensional representation of the operations involved in instrumental training and Pavlovian conditioning is described, which discusses the current status of research and theory concerning these phenomena.
Abstract: Publisher Summary Aversive events occur frequently in the life histories of all organisms. Long-lasting behavior pecularities, emotional illnesses, and anomalies of perception and thinking are attributed to such events. Apart from genetic or constitutional variables that might lead to individual differences in reactivity to aversive stimuli, there are a host of environmental variables that help to understand such individual differences. Two such environmental variables are the predictability and controllability of aversive events. This chapter reviews some of the behavioral and physiological consequences of aversive events that are either unpredictable, uncontrollable by a subject, or both. Unpredictable painful events turn out to be more distressing than are predictable ones. They generate more ulcers and intensify subjective reports of painfulness and anxiety. Both people and animals choose, if given the choice, predictable painful events over unpredictable ones. Uncontrollable painful events can interfere with an organism's ability later to solve problems to escape or avoid these events. They can lead to a phenomenon labeled “helplessness.” The chapter discusses the current status of research and theory concerning these phenomena. It describes a two-dimensional representation of the operations involved in instrumental training and Pavlovian conditioning. The chapter further reviews a number of theoretical interpretations of the effects of uncontrollable shocks on subsequent escape/avoidance learning and discusses the theoretical interpretations of the effects of unpredictable shocks on behavioral and physiological responses: the preparatory response hypothesis and the safety signal hypotheses.
445 citations
TL;DR: In this article, the elastic and plastic properties of filaments of non-crystalline Pd 20 a/o Si alloy and the changes that occur on crystallization during and after heating at various temperatures have been examined.
435 citations
TL;DR: Two models of pattern vision were tested: a single-channel model in which pattern vision is a function of a single neural network and a multiple-channels model inWhich the stimulus information is processed by many channels, each sensitive to a narrow range of spatial frequencies.
434 citations
TL;DR: These inhibitors make it possible to isolate the two respiratory pathways and study their mode of action separately, and enhance an electron paramagnetic resonance signal near g = 2 in anaerobic, submitochondrial particles from skunk cabbage, which appears to be specific to the alternate oxidase and thus provides a means for its assay.
Abstract: Hydroxamic acids, R-CONHOH, are inhibitors specific to the respiratory pathway through the alternate, cyanide-insensitive terminal oxidase of plant mitochondria. The nature of the R group in these compounds affects the concentration at which the hydroxamic acids are effective, but it appears that all hydroxamic acids inhibit if high enough concentrations are used. The benzhydroxamic acids are effective at relatively low concentrations; of these, the most effective are m-chlorobenzhydroxamic acid and m-iodobenzhydroxamic acid. The concentrations required for half-maximal inhibition of the alternate oxidase pathway in mung bean (Phaseolus aureus) mitochondria are 0.03 mm for m-chlorobenzhydroxamic acid and 0.02 mm for m-iodobenzhydroxamic acid. With skunk cabbage (Symplocarpus foetidus) mitochondria, the required concentrations are 0.16 for m-chlorobenzhydroxamic acid and 0.05 for m-iodobenzhydroxamic acid. At concentrations which inhibit completely the alternate oxidase pathway, these two compounds have no discernible effect on either the respiratory pathway through cytochrome oxidase, or on the energy coupling reactions of these mitochondria. These inhibitors make it possible to isolate the two respiratory pathways and study their mode of action separately. These inhibitors also enhance an electron paramagnetic resonance signal near g = 2 in anaerobic, submitochondrial particles from skunk cabbage, which appears to be specific to the alternate oxidase and thus provides a means for its assay.
417 citations
TL;DR: This syndrome of sensory neglect appears to be involved in some of the deficits in feedinig and attack which follow bilateral lateral hypothalamic lesions.
Abstract: Unilateral lateral hypothalamlic lesions in rats produce deficits in orientation to contralateral visucal, olfactory, whisker-toluch, and somatosetnsory stimuli. This syndrome of sensory neglect appears to be involved in some of the deficits in feedinig and attack which follow bilateral lateral hypothalamic lesions.
TL;DR: A computer model of the metabolism of glutamate, glutamine, gamma-aminobutyrate, and the tricarboxylic acid cycle in mouse brain has been constructed in terms of 39 reactions among 19 substances or groups of substances (permitting manipulation of 30 independent variables).
Abstract: A computer model of the metabolism of glutamate, glutamine, gamma-aminobutyrate, and the tricarboxylic acid cycle in mouse brain has been constructed in terms of 39 reactions among 19 substances or groups of substances (permitting manipulation of 30 independent variables). The model is divided into two compartments, in conformity with previous models based on indirect evidence, and it is found that this compartmentation is indeed the same as that indicated directly with specifically (14)C-labelled acetate and glucose. The movement of materials between the large and small compartments has been studied; glutamine appears to flow from the small to the large compartment, gamma-aminobutyrate in the reverse direction.
TL;DR: Carotenoid absorbance changes observed in R. gelatinosa at 77°K appear to respond to the light-induced oxidation-reduction reactions of reaction center bacteriochlorophyll, the primary electron acceptor, and to the cytochromes; the carotenoids changes may result from electrostatic field alterations.
TL;DR: There is a group of children with disseminated neuroblastoma with a surprisingly good prognosis, and radiation therapy and chemotherapy may not be necessary in the management of certain children with this syndrome.
TL;DR: A complete kinetic scheme describing the effects of pH is presented and the possible chemical significance of the species E'0 is discussed, which is unreactive with glucose and it is probable that the turnover rate in the low pH range is limited by k2 in the absence of halide.
TL;DR: In this paper, the energy levels of A = 16 and 17 nuclei were compared with the information about the structure of the A = 17 and A = 14 systems, with emphasis on material leading to information about their structure.
TL;DR: In this paper, the amorphous form of Si and several related, tetrahedrally bonded semiconductors (Ge, GaAs, GaP, InSb) were studied in the presence of Raman scattering.
Abstract: Raman scattering has been studied in the amorphous form of Si and several related, tetrahedrally bonded semiconductors (Ge, GaAs, GaP, InSb). All vibrational modes of the material can take part in the scattering process, and the Raman spectrum is a measure of the density of vibrational states. The amorphous phases are found to have vibrational spectra very similar to the corresponding crystals, reflecting the similarity in short-range order of the two phases.
TL;DR: The duality of the elongation rate versus turgor relation and the prominent role of Y in regulating rate are the major features of growth control in Nitella.
Abstract: Several levels of control of elongation rate are revealed through the detailed study of responses of the Nitella internode to abrupt shifts in turgor. The immediate response, which apparently reflects the physical state of the cell, is approximately described by the equation r = ( P — Y ) m where r is rate, P is pressure, Y is the wall9s yielding threshold, and m is related to the wall9s apparent fluidity (reciprocal viscosity). Because P and Y are in the range 5 to 6 atmospheres, and ( P — Y ) is roughly 0.2 atmosphere, elongation rate is initially extremely sensitive to changes in P. A small step-down in turgor (0.7 atmosphere) stops growth, and a similar rise greatly accelerates it. These initial responses are, however, soon (15 minutes) compensated by changes in Y. An apparent metabolism-dependent reaction (azide-sensitive) lowers Y ; strain hardening (azide-insensitive) raises it. These two opposing processes, acting on Y , serve as a governor on ( P — Y ), tending to maintain it at a given value despite changes in P. This ability to compensate is itself a function of turgor. Turgor step-downs are less and less well compensated, leading to lower rate, as turgor falls from 5 atmospheres to about 2 atmospheres where growth appears not to resume. This is the lowest attainable yield value, Y 1 . The turgor dependency of compensation reflects a turgor requirement of the Y -lowering (“wall-softening”) process. Thus the relation between steady state, r s , and turgor is an indirect one, derived from time-dependent alterations of the cell wall. This relationship superficially resembles the instantaneously valid one in that, roughly, r s = ( P — Y 1 ) m s . Y 1 and m s , however, have much lower values than Y and m . The duality of the elongation rate versus turgor relation and the prominent role of Y in regulating rate are the major features of growth control in Nitella.
TL;DR: It is concluded that TRH may be closely related to prolactin releasing factors in crude hypothalamic extracts.
Abstract: Tea normal volunteers received 100 to 800 ug of TRH intravenously. Serum prolactin was measured by a specific radioimmunoassay before and at intervals after TRH administration. Serum prolactin began to rise within 5 minutes and was maximal after 15 to 20 minutes. The mean peak response at 15 minutes was 11 times the fasting level. Serum prolactin had returned to the baseline by 180 minutes. It is concluded that TRH may be closely related to prolactin releasing factors in crude hypothalamic extracts.
TL;DR: Using tissue-culture techniques, peripheral blood lymphocytes obtained from all patients undergoing various types of major operations have been found to develop depressed immunological competence, and the observation that this biosynthetic defect was most severe in lymphocytes harvested from individuals with heart-disease and cancer is significant.
TL;DR: In this paper, the immunobiology of mammalian reproduction has been discussed, including a highly selective antigen-antibody-like stereochemical interaction between highly specific components of the plasma membranes of eggs and sperms which provides a plausible basis for the tissue specificity and species specificity of fertilization.
Abstract: Publisher Summary This chapter discusses the immunobiology of mammalian reproduction. Mechanisms of the type that characterize immunological phenomena have been postulated by several authorities as indispensible components of two key events in the reproductive process: (1) a highly selective antigen–antibody–like stereochemical interaction between highly specific components of the plasma membranes of eggs and sperms which provides a plausible basis for the tissue specificity and species specificity of fertilization and (2) a local inflammatory response with which mononuclear leukocytic cells appear to be intimately associated, if not causally related, in the endometrium, having some features in common with a local delayed hypersensitivity reaction, at the site of implantation and which may be essential for nidation. The fact that spermatozoa have long been shown to possess cytospecific antigens, in addition to their recently established expression of transplantation antigens, suggests one kind of maternal sensitization that might under natural and/ or experimental conditions interfere with the early stage of the reproductive process. Sensitization to various components of seminal plasma has also long been entertained as another possible immunological complication of fertility.
TL;DR: In this paper, the authors isolated matrix-free cells from chick embryo tendons by digesting the tendons with trypsin and bacterial collagenase, and tested the cells with the Trypan Blue technique indicated that most of the cells were viable.
TL;DR: Chromatographic studies on CM-cellulose of collagens isolated from basement membranes of the glomerulus, lens capsule and Descemet's membrane indicate that the molecule is composed of three identical α -1 chains.
TL;DR: These findings suggest that in vivo red-cell glucose metabolism is significantly hypophosphatemic, and that total intravenous hyperalimentation with solutions lacking added inorganic phosphate is a viable treatment option for this condition.
Abstract: Within seven to 10 days after initiation of total intravenous hyperalimentation with solutions lacking added inorganic phosphate, five of eight adults were found to be significantly hypophosphatemic (serum inorganic phosphate less than 1 mg per 100 ml). Associated with this hypophosphatemia was a decrease in erythrocyte glucose-6-phosphate, fructose-6-phosphate, 3-phosphoglyceric acid, 2-phosphoglyceric acid, phosphoenolpyruvate, 2,3-diphosphoglycerate and adenosine triphosphate, and a marked increase in the concentration of "total triosre phosphates." The reduction in 2,3-diphosphoglycerate and adenosine triphosphate was accompanied by a striking increase in the red cell's affinity for oxygen. In an additional patient studied prospectively, the changes in erythrocyte metabolism were initially manifested by a slight rise in the "total triose phosphates," which was rapidly followed by alterations similar to those described above. These findings suggest that in vivo red-cell glucose metabolism is c...
TL;DR: In this paper, a Green's function theory of surface states is presented, starting from the energy eigenvalues of an infinite crystal, and the effect of alterations in the surface potential is included.
TL;DR: In this paper, it was shown that a strongly cyclic self-adjoint representation of a commutative *-algebra is standard if and only if the representation is strongly positive, i.e., the representations preserve a certain order relation.
Abstract: Unbounded *-representations of *-algebras are studied. Representations called self-adjoint representations are defined in analogy to the definition of a self-adjoint operator. It is shown that for self-adjoint representations certain pathologies associated with commutant and reducing subspaces are avoided. A class of well behaved self-adjoint representations, called standard representations, are defined for commutative *-algebras. It is shown that a strongly cyclic self-adjoint representation of a commutative *-algebra is standard if and only if the representation is strongly positive, i.e., the representations preserves a certain order relation. Similar results are obtained for *-representations of the canonical commutation relations for a finite number of degrees of freedom.
TL;DR: In the in vitro preparations (costochondral junctions of twenty-one-day-old rats), there is a distinct oxygen gradient corresponding to the morphological zones, and in vivo preparations (proximal tibial epiphyses of six-week-old rabbits) exhibited a very low-oxygen tension in the zone of hypertrophic cells and in the metaphysis.
Abstract: 1. A technique for measuring oxygen tension in different zones of the epiphyseal plate, the metaphysis and the diaphysis in vitro and in vivo is described.
2. In the in vitro preparations (costochondral junctions of twenty-one-day-old rats), there is a distinct oxygen gradient corresponding to the morphological zones, beginning with a low tension of 19.5 millimeters of mercury in the zone of small size cartilage cells and increasing progressively to a high tension of 95.2 millimeters of mercury in metaphyseal bone.
3. In sharp contrast, the in vivo preparations (proximal tibial epiphyses of six-week-old rabbits) exhibited a very low-oxygen tension in the zone of hypertrophic cells and in the metaphysis.
4. A steep gradient in oxygen tension was present between metaphyseal bone (19.8 millimeters of mercury) and diaphyseal bone (108.7 millimeters of mercury) in the in vivo preparations.
5. The significance of these findings is discussed, and the physiological role of oxygen in epiphyseal plate growth is examined.
TL;DR: The uneven reduction of dopamine and serotonin appears to preclude the possibility of a defect in the transport of precursor amino-acids into brain and in the synthesis, storage, and degradation of the monoamines in Parkinson's disease.