Showing papers by "Case Western Reserve University published in 1972"
1,078 citations
TL;DR: In this paper, four experiments were reported which attempt to determine how people make classifications when categories are defined by sets of exemplars and not by logical rules, and the predominant strategy was to abstract a prototype representing each category and to compare the distance of novel patterns to each prototype, emphasizing those features which best discriminated the two categories.
992 citations
TL;DR: Experiments on turbulent circular jets issuing into cross flow from both heated and unheated jets were conducted in this paper, where the authors showed that turbulent circular planes can be generated by both heating and cooling.
Abstract: Experiments on turbulent circular jets issuing into cross flow from both heated and unheated jets
541 citations
TL;DR: Tail tendons from Fischer and Sprague-Dawly albino rats of ages from 2 weeks to 3 years were investigated under the polarizing microscope as regards structure and deformation behaviour and it was found that a model containing inflexible hinges, corresponding to the ‘elastica’ problem in mechanics gave reasonable fit with experiment.
Abstract: Tail tendons from Fischer and Sprague-Dawly albino rats of ages from 2 weeks to 3 years were investigated under the polarizing microscope as regards structure and deformation behaviour. Periodically extinguishing bands were observed along the otherwise featureless tendons. By analysing the behaviour of this extinction pattern under appropriate rotations of the tendon, it could be deduced that the orientation of the basic birefringent units varies periodically along the tendon and that this periodic pattern corresponds to a planar arrangement of the anisotropic entities. All the relevant parameters of this periodic structure could be determined in a representative manner from polarizing optics alone. Subdivision of the tendons revealed regularly undulating or rather crimped subunits in good correspondence to what has been deduced from the extinction bands in the intact tendons. The crimp angle was found to decrease while the periodicity increased - in approximate proportion to the length of the tail - with the age of the rat implying constancy of crimp number during the life time of the animal. On elongation the periodicity was gradually removed. The calculated fibre elongation necessary to eliminate the crimp was in good agreement with observation for mature rats but was larger for young rats implying the simultaneous stretching of the fibre itself. Stress-strain properties of tendons were measured and models for crimp straightening were tested. It was found that a model containing inflexible hinges, corresponding to the ‘elastica’ problem in mechanics gave reasonable fit with experiment. Analysis of stress-strain data on this basis leads to a basic load bearing unit, the diameter of which increases from 100 to 500 nm with the age of the animal. Implications of these findings for the structure and properties of the tendons, also in relation to ageing are pointed out.
527 citations
TL;DR: Temperature-shift experiments and analysis of SV40 viralDNA replication by gel electrophoresis have provided strong evidence that the ts gene product of the three mutants is directly required to initiate each new round of viral DNA replication but is not required to complete a cycle which has already begun.
Abstract: Three temperature-sensitive (ts) mutants of simian virus 40 (SV40) in complementation group A (tsA7, tsA28, tsA30) have been isolated and characterized in permissive and restrictive host cells. At 41 C in the AH line of African green monkey kidney cells, the mutants are deficient in an early function required to produce infectious viral deoxyribonucleic acid (DNA). Temperature-shift experiments and analysis of SV40 viral DNA replication by gel electrophoresis have provided strong evidence that the ts gene product of the three mutants is directly required to initiate each new round of viral DNA replication but is not required to complete a cycle which has already begun. The synthesis of mutant DNA molecules themselves can be initiated by a nonmutant gene product in viral complementation studies at 41 C. The cell, however, cannot substitute a host function to provide the initiator required for the replication of free viral DNA. The viral initiator is also required to establish the stable transformation of 3T3 cells.
520 citations
TL;DR: In this article, the complex nature of the natural convection phenomena in enclosures is discussed and the boundary value problem is formulated, assuming that the motion is two-dimensional and steady, the fluid is incompressible and frictional heating is negligible.
Abstract: Publisher Summary This chapter discusses the complex nature of the natural convection phenomena in enclosures. It discusses the two basic configurations of natural convection— that is, a rectangular cavity and a horizontal circular cylinder. In rectangular cavities, consideration is given to the two-dimensional convective motion generated by the buoyancy force on the fluid in a rectangle and to the associated heat transfer. The two long sides are vertical boundaries held at different temperatures and the short sides can either be heat conducting or insulated. Particular attention is given to the different flow regimes that can occur and the heat transfer across the fluid space between the two plane parallel vertical boundaries. Although heat transfer by radiation may not be negligible it is independent of the other types of heat transfer and can be fairly accurately calculated separately. To formulate the boundary value problem that describes this phenomena it is assumed that: (a) the motion is two-dimensional and steady, (b) the fluid is incompressible and frictional heating is negligible, and (c) the difference between the hot wall and cold wall temperatures is small relative to the absolute temperatures of the cold wall. In horizontal circular cylinder, consideration is given to the large Rayleigh number flow with the Prandtl number large and the Grashof number of unit order of the magnitude.
382 citations
TL;DR: In the 21st century, the professional and technical class will be pre-eminent, or, in more general terms, it will be a 'professionalized' society (Freidson, 1971, p. 467) as discussed by the authors.
Abstract: What will be the shape of the society in the 21st century? The year 2000 is only a generation away, and sociologists and 'futurologists' of varying academic persuasions already have delineated some of its minimum parameters. We will live, it is said, in a 'post-industrial' society. This means, according to Bell (1968, p. 152) that the professional and technical class will be pre-eminent, or, in more general terms, that it will be a 'professionalized' society (Freidson, 1971, p. 467). The knowledge explosion in science and technology is the rationale for these forecasts. Expanding knowledge calls for increasing numbers of professionals who have mastered the various bodies of esoteric information, and are capable of applying their technical skill and expertise to the manifold problems of mankind on a vulnerable and shrinking planet. Another related prediction suggests that the service ethos of the professional's style of work is becoming generalized to the total society. In this view, the imputed ideology of the personal service professions-'concern, sympathy and even affection for those who are to be helped by the professional practitioners'-will structure the social order along the ethical lines espoused by the counsellor (Halmos, 1970, p. 14). These estimates for the future elaborate on two basic characteristics of profession-mastery over knowledge and a humanitarian approach in application of that knowledge. They do not, however, explicidy address the third core element of profession: the autonomy of the professional, his freedom from lay control in carrying out his occupational role, in a word, his power. From Greenwood (1957) to Moore (1970), there have been a series of diverse, if often overlapping, definitions of the concept of profession. Basic to all, however, are the dimensions of knowledge monopoly,
259 citations
TL;DR: An elastic perfectly plastic mathematical model for the behavior of bone tissue is presented in an attempt to reconcile previous discrepancies in the literature in the calculated ultimate tensile strength from bending and tensile tests.
257 citations
01 Mar 1972-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: A model based on inhibitory interactions between oscillators representing leg activity has been constructed to explain the step pattern changes in both modes of walking and the temporal asymmetry of the adult pattern and appears to be applicable to the walking behaviour of other insects including the cockroach.
Abstract: The coordination of protraction leg movements in free walking first instar and adult stick insects has been examined by film and video-tape analysis. The first instar insect uses two alternative modes of walking which differ in the step frequency dependence of the time required to complete one metachronal cycle of protractions and the duration of the protraction cycle (Figs. 2, 4). The adult uses only one of these modes and its step patterns show a persistent right-left asymmetry in the timing of leg movements (Fig. 7). Two alternative methods of changing direction were found (Figs. 5, 9) and they appear to be related to the two modes of walking used by the animal. A model based on inhibitory interactions between oscillators representing leg activity has been constructed to explain the step pattern changes in both modes of walking and the temporal asymmetry of the adult pattern. This model appears to be applicable to the walking behaviour of other insects including the cockroach.
253 citations
TL;DR: In this article, a theoretical study of the vibrational spectra of α-D -glucose has been made by normal coordinate analysis and the predicted vibrational frequencies are compared with those observed in the infrared and Raman spectra, both as a crystalline solid and in aqueous solution.
241 citations
TL;DR: In this article, the capacity of the basal plane of high-pressure stress-annealed pyrolytic graphite has been examined in aqueous solution using an a.c. impedance bridge.
TL;DR: Infants' recognition memory, defined by novelty preferences, was found to be reliably greater when one properly oriented representation of a face was to be distinguished from another than when the same faces rotated 180° were to be differentiated.
TL;DR: A table of 10 enzymes which show both transients and cooperativity suggests that these phenomena do occur together and may be related mechanistically through the slow transition mechanism.
TL;DR: The designations, carnitine palmityltransferase A and B, represent enzymatic activities in two different intramitochondrial compartments with different functional roles, and further evidence is needed to determine if these are isoenzymes.
TL;DR: The fixative should make the demonstration of tissue-fixed immunoglobulins in skin biopsies in a useful diagnostic procedure in lupus erythematosus and bullous diseases a readily available clinical test.
TL;DR: The results are interpreted to mean that in newt tail regeneration, as in that of the lizard, the ependyma forms a pathway to guide regenerating cord fibers caudally.
TL;DR: In this paper, the intrinsic stress in thin polycrystalline nickel films vapor-deposited onto polished silicon substrates was measured by viewing the substrate deflection using an optical interference method.
TL;DR: The relation between the growth of axons and the development of their myelin sheaths was determined in rats for normal, myelinating sciatic nerves, and for an experimental model allowing to retard or accelerate axon growth.
Abstract: The relation between the growth of axons and the development of their myelin sheaths was determined in rats for normal, myelinating sciatic nerves, and for an experimental model allowing to retard or accelerate axon growth. Axon caliber was measured, and sheath development was determined from measurements of thickness (light microscopy), from counts of the number of turns of myelin lamellae (electron micrographs), and from the rate of the incorporation of acetate-H3 into ether-ethanol extractable lipids. An excellent correlation between changes in sheath thickness and acetate-H3 incorporation was obtained for all experiments. For the myelinating nerves the changes in the rate of acetate-H3 incorporation were related specifically to the rate with which new length of myelin leaflet was added to the existing turns of sheath.
The rate of axonal growth was manipulated by applying a snug ligature around the nerve by the fourteenth day, allowing the nerve to compress itself by its own growth. Most axons passed the constriction without interruption, but they were markedly hypoplastic distal to the constriction. After removal of the ligature these axons regrew to their normal caliber ranges. Examination of myelin sheath development in this model showed that retardation of axon growth retarded sheath growth, while acceleration of axon growth accelerated sheath growth. Thus, the rate of axon growth appeared to be the factor controlling the rate of myelin formation by the sheath cells.
An appendix describes a model consisting of two interrelated feedback mechanisms by which expansion of the axon may directly control the number of turns of myelin lamellae formed by the sheath cell. The model correspons on all points to established features in the fine structure of fibers.
TL;DR: Findings obtained by indirect methods have been generally confirmed by studies using other indirect methods, although the intramyocardial tissue pressure in the inner layers of the left ventricle has not always been found to exceed cavitary pressure.
Abstract: • Histological evidence indicates that the subendocardial layers of the left ventricle are vulnerable to ischemia: areas of necrosis in the subendocardium are greater than they are in the epicardium in transmural infarction (1) and in coronary insufficiency (2), suggesting that antegrade coronary blood flow in the subendocardial layers is less than that in the epicardium because of the proximity of the former to intracavitary left ventricular pressure (3). Initial studies showed a gradient in tissue pressure with systolic pressure in the subendocardium exceeding that in the left ventricular cavity and suggested that systolic extravascular compression could be a significant feature in the transmural distribution of coronary blood flow (3). These findings obtained by indirect methods have been generally confirmed (4-7) by studies using other indirect methods, although the intramyocardial tissue pressure in the inner layers of the left ventricle has not always been found to exceed cavitary pressure (8). Recently, a more direct measurement of myocardial tissue pressure by subminiature pressure transducers (9) has confirmed the presence of a transmural gradient with systolic pressure in the subendocardium of
TL;DR: This observation supports the thesis that cyclic AMP mediates the steroidogenic action of ACTH on the adrenal cortex and the bearing of these results on the second messenger theory is discussed.
TL;DR: In this paper, the tetragonal-monoclinic phase transformation in ZrO2 single crystals and polycrystals has been studied in both the forward and reverse directions and found to be martensitic.
TL;DR: Congestive failure, cardiomegaly, and arrhythmia correlated closely with persistence of murmurs, but increased P-R interval, acute QRS or T-voltage variation or both, and ST-T abnormalities did not.
Abstract: The prognosis for 115 rheumatic fever patients subsequently receiving regular intramuscular penicillin prophylaxis for at least 5 years was studied. Average follow-up was 9.3 years, and 57 patients were followed for 10 years or longer. Of the 79 patients with acute mitral regurgitation, 70% lost their murmur from 4 days to 8.5 years after it was first heard. This is in contrast to those with acute aortic regurgitation which persisted in 73%. No patient developed mitral or aortic stenosis: this suggests that regular prophylaxis may prevent the development of stenosis. Congestive failure, cardiomegaly, and arrhythmia correlated closely with persistence of murmurs, but increased P-R interval, acute QRS or T-voltage variation or both, and ST-T abnormalities did not.
TL;DR: In this paper, the theory of pure silica glass was reviewed and the following topics were treated: the nature of bonding as the basis for the new model; the distribution of oxygen angles and the volume of silicas; new interpretation of acoustic losses, pressure and temperature dependence of the compressibility, thermal expansion and specific heat.
Abstract: This paper deals with the theory of pure silica glass. Earlier theoretical work is reviewed first and then the following topics are treated: The nature of bonding as the basis for the new model; The distribution of oxygen angles and the volume of silicas; New interpretation of acoustic losses, pressure and temperature dependence of the compressibility, thermal expansion and specific heat.
TL;DR: A simple, fast, efficient, and accurate automated method is described for determining the quantity of glucose in 50 µl of serum or plasma using a hexokinase/glucose-6-phosphate dehydrogenase reaction requiring incubation at room temperature.
Abstract: A simple, fast, efficient, and accurate automated method is described for determining the quantity of glucose in 50 µl of serum or plasma. A hexokinase/glucose-6-phosphate dehydrogenase reaction requiring incubation at room temperature is used. The method is specific for glucose, and is not affected by increased concentrations of endogenous chemical substances in uremic sera or by several common drugs that interfere with other glucose methods. Results of parallel assays, in which glucose oxidase and o -toluidine are used, are compared.
TL;DR: The exact parallelism between depression of liver microsomal mixed function oxidase activity and resistance to the lethal effects of carbon tetrachloride affords strong evidence for the view that metabolism of CO2 by the livermicrosomal drug-metabolizing system is a necessary prerequisite for the toxicity of this liver poison.
TL;DR: It is proposed that adenyl cyclase in the intact plasma membrane is located in a compartment wherein calcium concentration is low and remains unaffected by the concentration of calcium in the extracellular space, and the strength of the signal generated by the interaction of adrenocorticotropic hormone with its receptor and transmitted to the adenYL cyclase compartment is proportionately increased.
Abstract: Corticosterone production by isolated adrenal cells in response to adrenocorticotropic hormone is reduced when the cells are incubated in a medium that contains no calcium. This reduction is associated with an equal reduction of accumulation of cyclic adenosine monophosphate. Production of corticosterone and accumulation of cyclic adenosine monophosphate are increased when the calcium concentration in the medium is increased (from zero to 7.65 millimolar). This is in contrast to the situation in "subcellular membrane fragments" of adrenal tissue where high calcium in the medium (> 1.0 millimolar) inhibits cyclic adenosine monophosphate accumulation. We propose that adenyl cyclase in the intact plasma membrane is located in a compartment wherein calcium concentration is low and remains unaffected by the concentration of calcium in the extracellular space. It is proposed that, as the concentration of calcium in the incubation medium is increased from zero to 7.65 millimolar, the strength of the signal generated by the interaction of adrenocorticotropic hormone with its receptor and transmitted to the adenyl cyclase compartment is proportionately increased.
TL;DR: Insensible water loss was determined from measurements of insensible weight loss during the first 7 weeks of life on 30 immature and nine small-for-gestational age, low birth weight infants, considerably higher than previously reported.
Abstract: Insensible water loss (IWL) was determined from measurements of insensible weight loss during the first 7 weeks of life on 30 immature and nine small-for-gestational age, low birth weight infants. Under standard conditions (single-walled incubator, infant nude, gavage feeding), 10 infants with birth weights less than 1,250 gm, gestational age 2.5 gm/kg/hr (equivalent to 60-120 ml/kg/day), considerably higher than previously reported. Studies following the insertion of a plastic heat shield revealed a 25% reduction in IWL. The heat shield facilitates achievement of neutral thermal environment and reduced water losses in low birth weight infants. IWL measurements in infants with birth weights >1,500 gm and those small-for-gestational age were similar to previously reported studies. Because of the known limited ability of small immature infants to increase metabolic rate, these extremely high losses are believed to represent disproportionately larger water losses from skin. Skin factors predisposing to large water loss in immature infants include thinner epidermis, increased water content, and increased permeability.
TL;DR: The results lead to the conclusion that the Schwann cell is the predominant agent of axon and myelin destruction and the entire contents, commingled organelles and neurofilaments, are destroyed.
Abstract: The sequence of degeneration in colchicine-poisoned or in transected peripheral nerve fibers is reported. The results lead us to conclude that the Schwann cell is the predominant agent of axon and myelin destruction. The Schwann cytoplasm burgeons, swells the Schmidt-Lanterman clefts and the adaxonal layer of cytoplasm, and invades the electron-dense bands of myelin. The axolemma and adaxonal membranes are eroded and Schwann organelles invade the axoplasm commingling with those of the axon to form a peripheral “reactive zone.” The reactive zone of organelles surrounds a core of compacted neurofilaments which may persist for days. Eventually the entire contents, commingled organelles and neurofilaments, are destroyed. The myelin sheath is destroyed without being separated from its Schwann cell of origin.
TL;DR: The mechanism of crystal slip in olivine in peridotite xenoliths from alkalic basalts has been investigated by highvoltage (up to 1 MeV) electron petrography as discussed by the authors.