Showing papers by "Purdue University published in 1972"

Organization and maintenance of large ordered indexes

Abstract: Organization and maintenance of an index for a dynamic random access file is considered. It is assumed that the index must be kept on some pseudo random access backup store like a disc or a drum. The index organization described allows retrieval, insertion, and deletion of keys in time proportional to logk I where I is the size of the index and k is a device dependent natural number such that the performance of the scheme becomes near optimal. Storage utilization is at least 50% but generally much higher. The pages of the index are organized in a special datastructure, so-called B-trees. The scheme is analyzed, performance bounds are obtained, and a near optimal k is computed. Experiments have been performed with indexes up to 100000 keys. An index of size 15000 (100000) can be maintained with an average of 9 (at least 4) transactions per second on an IBM 360/44 with a 2311 disc.

Postnatal development of the cerebellar cortex in the rat. II. Phases in the maturation of Purkinje cells and of the molecular layer

Abstract: The growth and synaptic maturation of Purkinje cells and of the molecular layer were studied in the cerebellar cortex of rats aged 0, 3, 5, 7, 10, 12, 15, 21 and 30 days with histological (including Golgi), histochemical, autoradiographic and electron microscopic techniques. Five phases were distinguished in the maturation of Purkinje cells. During the first phase, Purkinje cells become dispersed and aligned in a monolayer but as yet few or no synapses are formed. Next, two transient structures appear: a hypertrophied apical cone composed of „reticular” cytoplasm, and lateral perisomatic processes which establish conspicuous asymmetrical synapses with climbing fibers. During the third phase the perisomatic processes disappear; the „reticular” cytoplasm streams upward into the growing dendrites; the soma is invaded by permanent inconspicuous, symmetrical synapses of basket cells; and, finally, it is surrounded by glial processes, which marks the end of the synaptic maturation of the soma. During the fourth phase parallel fibers form synapses with dendritritic spines in the lower half of the molecular layer. During the fifth phase, which occurs after the disappearance of the external germinal layer, parallel fibers establish synapses with dendritic spines in the upper molecular layer. The „march” of synaptogenesis in the molecular layer from the bottom upward is characterized by three successive events: an initial gradient in the appearance and disappearance of coated vesicles, heralding synaptogenesis; a similar subsequent trend in the formation of synapses; and finally, the interposition in the same sequence of glial processes between Purkinje cell dendrities and parallel fibers, marking the cessation of synaptogenesis.

Postnatal development of the cerebellar cortex in the rat. I. The external germinal layer and the transitional molecular layer.

Abstract: The multiplication of cells in the proliferative zone of the external germinal layer and the early steps in the differentiation of basket, stellate and granule cells were studied in the cerebellar cortex of rats aged 0, 3, 5, 7, 10, 12, 15, 21 and 30 days with histological, histochemical, autoradiographic and electron microscopic techniques. Between 0–9 days the proliferative zone has a constant depth of four to five cells; the bipolar cells in the underlying premigratory zone increase in depth during this period from 0–6 cells. Thereafter, there is a decline in the cell depth of both zones. In the premigratory zone there is a gradient in the length of the extruded processes of the bipolar cells (concentration of such profiles), the future parallel fibers. Presumably when the latter reach their final length, the cell body migrates downward and the parallel fiber becomes part of the upper zone of the molecular layer. Thus, parallel fibers are progessively formed on the surface of others from the bottom upward by a stacking process and the external germinal layer, as a consequence, is continually pushed upward. This design makes possible the assembly of a matrix of very long, thin and straight beams of horizontally oriented parallel fibers which pile up vertically according to their age. When synaptogenesis starts during the second week in the molecular layer the enlarging junctional processes produce a spurt in the growth of this layer. Basket cells which are formed in the pyramis on days 6–7 are arrested in the formative molecular layer because their processes are oriented at a right angle to the underlying bed of parallel fibers. Therefore, there is also a stacking of the cells of the molecular layer from the bottom upward as a function of time of onset of their differentiation. Parallel fiber synapses may be seen on differentiating basket cells as early as the seventh day, forming connections with these inhibitory interneurons before they synapse with spines of Purkinje cells.

Postnatal development of the cerebellar cortex in the rat. 3. Maturation of the components of the granular layer.

Abstract: The migration of granule cells and the maturation of the various elements of the granular layer were studied in the cerebellar cortex of rats aged 0, 3, 5, 7, 10, 12, 15, 21 and 30 days with histological, histochemical, autoradiographic and electron microscopic techniques. The bulk of the granule cells are formed during the second week, but due to the time required for their migration and the lag in the formation of dendrites, few glomerular synapses are formed with mossy fibers before the beginning of the third week and the process is still in progress at 30 days, long after the dissolution of the external germinal layer. The maturation of Golgi cells is a protracted process. Their axons synapse with granule cell dendrites as soon as the glomeruli begin to mature. Evidence was obtained that mossy fibers synapse with the dendrites of Golgi cells. Towards the end of the second week the Lugaro cells are formed and synapses appear on their somata during the third week. Among these synapses the recurrent collaterals of Purkinje cell axons were identified. The Lugaro cells may be the primary targets of the infra and supraganglionic plexuses formed by these collaterals. In conclusion it was suggested that there are three major, successive stages in the neurogenesis of the cerebellar cortex, the morphogenic, synaptogenic and gliogenic. However, in the large Purkinje cell the synaptic maturation of one region (the soma) may begin before the morphogenic and synaptogenic maturation of the entire cell (the dendrites) is completed.

Concept of structural control

Abstract: In an ideal situation, completely safe structures can be designed if exact information is known concerning loads and strengths involved during the lifetime of these structures, and exact methods of structural analysis are available. In the real world uncertainties exist in this information as well as in the method of analysis. To account for these uncertainties, various factors of safety have been used in the design of structures. Probabilistic methods have been applied for the interpretation as well as determination of these factors of safety. Techniques in structural analysis are being refined continuously. The objective herein is to present the concept of structural control as an alternative approach to the safety problems of structural engineering. Pertinent points of the control theory are reviewed along with certain pioneering work in this direction. The practicality of this concept is illustrated with an example using analog parallel logic devices.

Density Compensation in Island Faunas

Abstract: This paper analyzes factors determining the extent of density compensation on islands: i.e., is the summed population density of individuals of all species on islands equal to the summed mainland density as a result of niche expansions and higher abundances of island species compensating for the absence of many mainland species? In addition, a method is described for estimating bird population densities based on analysis of the time dependence or mist—netting yields. Puercos Island in the Pearl Archipelago off Panama has less than one—third as many resident birds species as comparable mainland habitats. Analysis of the Pearl avifauna suggests that about one—quarter of the island species may be relicts of the Pleistocene land bridge and that the remainder are subsequent over—water colonists. The successful colonists are a highly nonrandom sample of the mainland avifauna in such respects as family composition, social structure, and second—growth habitat origin. Song—based censuses and analysis of mist—netting show that Puercos has a slightly density of individuals than the mainland. Niche shifts between islands and mainland, or among different islands, include habitat expansions, wider ranges of vertical foraging strata, abundance increases checkerboard distribution patterns, and decreased morphological variability. Comparison of the present study with other studies shows that summed population densities on islands may be higher than, comparable to, or less than mainland levels, depending upon the particular island, habitat, and group of animals studied. Among factors affecting the extent of density colonists less appropriate to the vacated habitat, tending to lower island densities; and underrepresentation of large species on islands, tending to increase island population densities for a given biomass.

Oestrogen and nuclear binding sites. Determination of specific sites by [3H]oestradiol exchange

Abstract: A method was developed for the determination of the number of specific oestradiol-binding sites in the nuclear fraction of oestrogen-sensitive tissues. The method is based on the exchange of [3H]oestradiol with non-labelled oestradiol that is bound to nuclear binding sites. The number of specific nuclear binding sites after the injection of 2.5μg of oestradiol, an amount sufficient to saturate all binding sites, is 1.6–1.7pmol per immature uterus. The number of sites occupied after an injection of physiological amounts of oestradiol (0.1μg) was 0.46pmol. The injection of oestradiol results in an increased number of nuclear binding sites in uterus and vagina, but has no effect on kidney or muscle. Injections of testosterone or progesterone failed to increase the number of uterine nuclear binding sites. This method permits an evaluation of the number of oestradiol-binding sites in the nuclear fraction of various tissues as a function of either endogenous oestradiol or non-labelled oestradiol administered by injection.

Crystal structure of human carbonic anhydrase C.

Abstract: The three dimensional structure of human carbonic anhydrase C has been determined at 2.0 A resolution. The active site has been identified by the binding of inhibitors and the location of the zinc ion.

Experimental reorganization of the cerebellar cortex. I. Morphological effects of elimination of all microneurons with prolonged x-irradiation started at birth

Abstract: The heads of Long-Evans rats were irradiated from birth with a schedule of repeated doses of low-level x-ray which prevented the acquisition of the postnatally-forming basket, stellate and granule cells. The absence of these microneurons led to several changes in the organization of the cerebellar cortex, studied at 30 days of age with light and electron microscopy. The somata of Purkinje cells were not strung out in a monolayer. Their primary dendrites were randomly oriented and arborized differently depending on the position of their somata in the depth of the cortex. Many Purkinje cell perisomatic processes, normally seen only in infants, were retained. Climbing and mossy fibers formed inconspicuous, symmetrical synapses with the somata and conspicuous, asymmetrical synapses with the perisomatic processes and dendritic thorns of Purkinje cells. Massive Purkinje cell dendrites with innumerable thorns made up much of the neuropil of the cortex. The dendritic thorns, in addition to forming true synapses, also established pseudosynapses with glial processes and synapses devoid of vesicles with the surface or the interior of Purkinje cell dendrites. The latter type of contact apparently led to autolysis of part of the dendrite, which was the only clear pathological phenomenon observed. These results indicated considerable autonomy in the growth of Purkinje cell dendrites, which arborized richly and sprouted innumerable small processes in the absence of parallel fibers, and formed postsynaptic dense membranes in contiguity with inappropriate processes, such as those of Purkinje cells or astrocytes.

A study of job characteristics and job dimensions as based on the Position Analysis Questionnaire (PAQ).

Abstract: : It was hypothesized that, across the spectrum of jobs, there is some underlying 'structure' of human work in terms of the human behaviors involved. The project was directed toward the identification of behaviorial job elements and of their organization into job dimensions, and the exploration of certain possible practical applications of job data based on such job elements or dimensions. The project involved the development of a job analysis instrument called the Position Analysis Questionnaires (PAQ) that included 189 job elements of a worker-oriented nature. Principal components analysis procedures were used in the analyses of two types of data based on the PAQ. One set consisted of job data for 536 jobs that were analyzed with the PAQ. The other consisted of 'attribute profiles' of the job elements; (These consisted of median ratings of the relevance of 67 human attributes to each job element). (Author)

Transform picture coding

Abstract: Picture coding by first dividing the picture into sub-pictures and then performing a linear transformation on each sub-picture cud quantizing and coding the resulting coefficients is introduced from a heuristic point of view. Various transformation, quantization, and coding strategies are discussed. A survey of all known applications of these techniques to monochromatic image coding is presented along with a summary of the dependence of performance on the basic system parameters and some conclusions.

In-vitro auxin binding to particulate cell fractions from corn coleoptiles.

Abstract: When low concentrations (e.g. 10-6 M) of labelled 3-indoleacetic acid (14C-IAA) or α-naphthaleneacetic acid (14C-NAA) are added in vitro to homogenates of corn coleoptiles, radioactivity is reversibly bound to pelletable particles. From the saturation kinetics of the binding it is possible to estimate an apparent K M between 10-6 M and 10-5 M and a concentration of specific sites of 10-7–10-6 M per tissue volume. The binding is auxin-specific. Among many compounds tested, only auxins and such auxin analogues that are known to interact directly with auxin in transport and/or growth were found to interfere with this binding. For instance, the growth-active d-dichlorophenoxyisopropionic acid at 10-4 M inhibits 14C-NAA binding more than the less active l-isomer. The auxin-binding fractions are practically free of DNA and cytochrome-C oxidase and contain binding sites for 1-naphthylphthalamic acid. The results are discussed in context with the hyothesis—derived mainly from physiological data—that auxin receptors are localized at the plasma membrane.

Configurational Excitations in Condensed Matter, and the ``Bond Lattice'' Model for the Liquid‐Glass Transition

Abstract: The characteristics of glasslike transitions in supercooled liquids and plastic crystals are discussed and a nearest neighbor interaction scheme, termed the ``bond lattice'' model, is proposed to account for the thermodynamic aspects of the phenomenon. Although the excitations of the bond lattice have features in common with those of the Ising lattice, the bond lattice has a zeroth order (noncooperative) case in which the thermodynamic properties are meaningful and readily evaluated. The zeroth order expressions appear adequate to account for the configurational heat capacity of the covalent bonded liquid ZnCl2, but are clearly incapable of explaining the transition behavior of most molecular and hydrogenbonded glasses. In these cases it is believed the configurational excitations have considerable cooperative character. While the complex cooperative problem is not properly treated in this paper, we show how an ad hoc introduction of temperature‐dependent bond energies (a sort of Bragg‐Williams approximat...

Some results concerning the identifiability of parallel and serial processes

Abstract: A mathematical characterization of serial, parallel and hybrid processes is given, and this characterization is related to several current experimental paradigms. Non-identifiability (mimicking) between two systems (i.e. models of systems) is defined as equivalence of probability distributions on element completion times for the two systems, where n elements are available for processing by each. Results are then presented for a class of systems with exponential processing times, and it is seen that several interesting cases of parallel and serial systems are equivalent to systems of the opposite type. Evidence that will allow accurate discrimination between parallel and serial processing for this and other classes of systems either requires more complete and precise information about the actual probability distributions of the systems or more specialized sets of converging operations than is usually obtained in psychological experimentation. For example, it is noted that at the level of first moments (means), even a parallel independent system can predict results usually associated with a serial system (an overall increasing linear mean reaction time curve as a function of the number of elements to be processed). Next, a functional equation is developed that must hold in order for mimicking to occur between parallel and serial systems within the same general family of probability distributions, and three special cases are examined. A parallel system with gamma-distributed processing times for element completion is then investigated, and it is shown that a strictly serial system cannot mimic it, but an interesting hybrid system can. This is followed by discussion of two kinds of partial identifiability, mimicking at the level of means and possible predicted differences at higher levels, and mimicking by approximation. Some qualitative considerations that may enter into conclusions as to parallelity or seriality of processing are then introduced. Last, it is suggested that in a broad sense questions related to parallel and serial systems concern fundamental aspects of information-processing structure and distribution of processing energy and hence merit further mathematical investigation.

Phosphotungstic Acid-Chromic Acid as a Selective Electron-Dense Stain for Plasma Membranes of Plant Cells

Abstract: A mixture consisting of 1% phosphotungstic acid (PTA) in 10% chromic acid (CrO3) selectively stains the plasma membrane of plant cells. Whole tissue or pelleted cell fractions are prepared for electron microscopy using conventional methods including glutaraldehyde fixation and OsO4 postfixation, dehydration in acetone and embedding in Epon. To stain the plasma membrane, thin sections are transferred with a plastic loop to the surface of a 1% aqueous solution of periodic acid for 30 min for destaining. Following transfer through 5 distilled water rinses, the sections are exposed to the PTA-CrO3 mixture for 5 min, rinsed and mounted on grids for viewing with the electron microscope. The selectivity of the stain is retained in homogenates and serves to identify the plant plasma membrane in cell fractions.

An Attitude Model for the Study of Brand Preference

Abstract: his characteristics is a prelude to identifying the causes of preference and the means by which it can be influenced. This study of consumer brand preference was an application of a model of consumer attitudes; the basic hypothesis was that measures specific to the preference alternatives, rather than more general measures such as those of socioeconomic and personality characteristics, would lead to successful predictions. While the approach is intuitively appealing and seemingly obvious, this study is the first to publicly present results from testing the hypothesis.

Tubular and filamentous structures in pollen tubes: Possible involvement as guide elements in protoplasmic streaming and vectorial migration of secretory vesicles

Abstract: An ultrastructural study of the pollen tubes of Lilium and Clivia has demonstrated three different classes of longitudinal structures which could influence patterns of protoplasmic streaming and/or serve as “guide elements” in the vectorial migration of secretory vesicles: (a), cortical and noncortical microtubules; (b), microfilaments; and (c), subcortical tubules and cisternae of the endoplasmic reticulum (“subsurface cisternae”) Morphological details of these structures are described Colchicine concentrations which lead to the complete disappearance of the microtubules affect neither germination of the pollen nor cytoplasmic streaming and tip growth of the elongating pollen tubes Tip growth is initially uninhibited by cycloheximide, and cytoplasmic streaming is insensitive to this inhibitor However, both of these processes are sensitive to cytochalasin B and vinblastine Our results suggest that neither microtubules nor subsurface cisternae are essential for cytoplasmic streaming and directional secretion of cell surface materials in the pollen tube but would be consistent with an involvement of microfilamentous structures in these processes Additionally, the possible importance of the lateral cross-link elements interconnecting all three types of structures is discussed

Boranes in Organic Chemistry

Abstract: Publisher Summary This chapter discusses boranes in organic chemistry, diborane as a reducing agent, volatile compounds of uranium, the alkali metal hydride approach to diborane, and alkali metal borohydrides. The search for solvents led to the discovery of sodium borohydride's being an excellent reducing agent for aldehydes and ketones. The search for catalysts to enhance the reducing power of sodium borohydride led to an anomalous result in the reduction of ethyl oleate. Investigation of this anomalous result led to the discovery of hydroboration. Hydroboration made the organoboranes readily available for the first time. This led to a systematic exploration of the chemistry of the organoboranes and established the fact that they constitute the most versatile organometallic available currently. The chapter describes molecular addition compounds and steric strains, steric assistance in solvolysis, the nonclassical ion problem, selective reductions, hydroboration, and versatile organoboranes. On the theoretical side, study of the dissociation of addition compounds of amines with trimethylborane, boron trifluoride, and borane provides a new quantitative approach to steric strains. These studies quickly removed doubts as to the importance of steric effects in chemical behavior and led to the study of related carbon compounds and the establishment of steric effects as an important factor in their behavior. One phase of these studies involved steric assistance to ionization in highly branched tertiary halides and related derivatives.

Synaptogenesis in the Rat Cerebellum: Effects of Early Hypo- and Hyperthyroidism

Abstract: The number of synapses in the molecular layer of the rat cerebellum is reduced by early hypo-and hyperthyroidism within 30 days. Hypothyroidism retards synaptogenesis after 10 days, while hyperthyroidism accelerates synaptogenesis initially, but by 21 days the number of synapses is reduced. The sensitivity of developing synapses to thyroid hormone may permit analysis of the events triggering synaptogenesis.

Purification of an Ion-Stimulated Adenosine Triphosphatase from Plant Roots: Association with Plasma Membranes

Abstract: A membrane-bound adenosine triphosphatase (EC 3.6.1.3) that requires Mg(++) and that is stimulated by monovalent ions has been purified 7- to 8-fold from homogenates of oat (Avena sativa L. Cult. Goodfield) roots by discontinuous sucrose-gradient centrifugation. The enzyme was substrate specific; adenosine triphosphate was hydrolyzed 25 times more rapidly than other nucleoside triphosphates. The membrane fraction containing adenosine triphosphatase was enriched in plasma membranes, which were identified by the presence of a glucan synthetase (EC 2.4.1.12), a high sterol to phospholipid ratio, and by a stain consisting of periodic acid, chromic acid, and phosphotungstic acid that is specific for plant plasma membranes. Oat-root plasma membranes and the associated adenosine triphosphatase were purified on either a 6-layer discontinuous sucrose gradient or on a simplified gradient consisting of only two sucrose layers.These results represent the first demonstration that plant plasma membranes contain an adenosine triphosphatase that is activated by monovalent ions, and this finding further implicates the enzyme in the absorption of inorganic ions by plant roots.

Rhetorical sensitivity and social interaction

Abstract: Contemporary attitudes toward communication can be viewed as two‐dimensional—expressive and instrumental. The argument of this article is that the instrumental, or as we would label it, the rhetorical approach, best promises to facilitate human understanding and to effect social cohesion. Five characteristics of rhetorical sensitivity are described. These are features which, if incorporated and operationalized in discourse, can help men make the most of social interactions. The rhetorically sensitive person (a) tries to accept role‐taking as part of the human condition, (b) attempts to avoid stylized verbal behavior, (c) is characteristically willing to undergo the strain of adaptation, (d) seeks to distinguish between all information and that information acceptable for communication, and (e) tries to understand that an idea can be rendered in multi‐form ways.

An experimental study of relationships between attitudes, brand preference, and choice

Abstract: This paper examines the effectiveness of models of preference and choice based on specific product attributes. An experiment with soft drink brands produced data that reflect preference rankings, choice, and evaluation of specific attributes at different points in time. Deterministic and stochastic choice models are examined.