406 research outputs found

    In Support of the Good Reasons Approach to Understanding Responsibility

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    Tree transducers and tree languages

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    Tree transducers (automata which read finite labeled trees and output finite labeled trees) are used to define a hierarchy of families of “tree languages” (sets of trees). In this hierarchy, families generated by “top-down” tree transducers (which read trees from the root toward the leaves) alternate with families generated by “bottom-up” tree transducers (which read trees from the leaves toward the root). A hierarchy of families of string languages is obtained from the first hierarchy by the “yield” operation (concatenating the labels of the leaves of the trees). Both hierarchies are conjectured to be infinite, and some results are presented concerning this conjecture. A study is made of the closure properties of the top-down and bottom-up families in the hierarchies under various tree and string operations. The families are shown to be closed under certain operations if and only if the hierarchies are finite

    Understanding Mothers of Late Preterm Infants

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    The experience of becoming a mother is a personal and social experience influenced by individual characteristics, friends and family, and the infant. The journey to become a mother encompasses concepts of maternal competence and responsiveness. The purpose of this study was to examine maternal competence and responsiveness to the infant in mothers of late preterm infants compared to mothers of full term infants. The conceptual model for this work was based on the work of Reva Rubin describing maternal identity and role development. Maternal competence and responsiveness are components of maternal role and are influenced by social support, maternal self-esteem, well-being, stress and mood. In addition, infant temperament and perception of infant vulnerability influence development of maternal competence and responsiveness. A non-experimental repeated measures design was used to compare maternal competence and responsiveness in two groups of postpartum mothers. One group consisted of mothers of late preterm infants 34-36, 6/7 weeks gestation. The second group consisted of mothers of term infants, \u3e/=37 weeks gestation. Both primiparas and multiparas were included in the study. Data was collected in the initial postpartum period prior to discharge from the hospital and again at six-weeks postpartum. No statistically significant differences in development of maternal competence or responsiveness between mothers of LPIs and term infants were identified. This study adds to our knowledge concerning outcomes of mothers of late preterm infants and development of competence and responsiveness

    Honeybee Associative Learning Performance and Metabolic Stress Resilience Are Positively Associated

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    Background: Social-environmental influences can affect animal cognition and health. Also, human socio-economic status is a covariate factor connecting psychometric test-performance (a measure of cognitive ability), educational achievement, lifetime health, and survival. The complimentary hypothesis, that mechanisms in physiology can explain some covariance between the same traits, is disputed. Possible mechanisms involve metabolic biology affecting integrity and stability of physiological systems during development and ageing. Knowledge of these relationships is incomplete, and underlying processes are challenging to reveal in people. Model animals, however, can provide insights into connections between metabolic biology and physiological stability that may aid efforts to reduce human health and longevity disparities. Results: We document a positive correlation between a measure of associative learning performance and the metabolic stress resilience of honeybees. This relationship is independent of social factors, and may provide basic insights into how central nervous system (CNS) function and metabolic biology can be associated. Controlling for social environment, age, and learning motivation in each bee, we establish that learning in Pavlovian conditioning to an odour is positively correlated with individual survival time in hyperoxia. Hyperoxia induces oxidative metabolic damage, and provides a measure of metabolic stress resistance that is often related to overall lifespan in laboratory animals. The positive relationship between Pavlovian learning ability and stress resilience in the bee is not equally established in other model organisms so far

    Orthogonal Packings in Two Dimensions

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    Lower Bounds for On-Line Two-Dimensional Packing Algorithms

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    Coordinated Science Laboratory was formerly known as Control Systems LaboratoryJoint Services Electronics Program / DAAG-29-78-C-001
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