605 research outputs found
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Not All Continuous Dimensions Map Equally: Number-Brightness Mapping in Human Infants
Evidence for spontaneous mappings between the dimensions of number and length, time and length, and number and time, has been recently described in preverbal infants. It is unclear, however, whether these abilities reflect the existence of privileged mappings between certain quantitative dimensions, like number, space and time, or instead the existence of a magnitude system underlying the representation of any quantitative dimension, and allowing mappings across those dimensions. Four experiments, using the same methods from previous research that revealed a number-length mapping in eight-month-old infants, investigated whether infants of the same age establish mappings between number and a different, non-spatial continuous dimension: level of brightness. We show that infants are able to learn and productively use mappings between brightness and number when they are positively related, i.e., larger numbers paired with brighter or higher contrast levels, and fail when they are inversely related, i.e., smaller numbers paired with brighter or higher contrast levels, suggesting that they are able to learn this mapping in a specific direction. However, infants not only do not show any baseline preference for any direction of the number-brightness mapping, but fail at transferring the discrimination from one dimension (number) to the other (brightness). Although infants can map multiple dimensions to one another, the number-length mapping may be privileged early in development, as it is for adults
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Number-Space Mapping in Human Infants
Mature representations of number are built on a core system of numerical representation that connects to spatial representations in the form of a mental number line. The core number system is functional in early infancy, but little is known about the origins of the mapping of numbers onto space. In this article, we show that preverbal infants transfer the discrimination of an ordered series of numerosities to the discrimination of an ordered series of line lengths. Moreover, infants construct relationships between numbers and line lengths when they are habituated to unordered pairings that vary positively, but not when they are habituated to unordered pairings that vary inversely. These findings provide evidence that a predisposition to relate representations of numerical magnitude to spatial length develops early in life. A central foundation of mathematics, science, and technology therefore emerges prior to experience with language, symbol systems, or measurement devices.Psycholog
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Spontaneous Mapping of Number and Space in Adults and Young Children
Mature representations of space and number are connected to one another in ways suggestive of a ‘mental number line,’ but this mapping could either be a cultural construction or a reflection of a more fundamental link between the domains of number and geometry. Using a manual bisection paradigm, we tested for number line representations in adults, young school children, and preschool children. Non-symbolic numerical displays systematically distorted localization of the midpoint of a horizontal line at all three ages. Numerical and spatial representations therefore are linked prior to the onset of formal instruction, in a manner that suggests a privileged relation between spatial and numerical cognition.Psycholog
Tasa de éxito subjetivo y objetivo en pacientes operados con cinta suburetral transobturatriz: ocho años de seguimiento
Indexación: Scopus; Scielo.Antecedentes: La Incontinencia Urinaria de Esfuerzo (IOE) representa el 50% de las incontinencias urinarias en la mujer, produciendo un gran impacto en su calidad de vida. Actualmente el TOT es una de las técnicas quirúrgicas más utilizadas para su tratamiento. Objetivos: Determinar la tasa de éxito objetiva y subjetiva de las pacientes operadas por IOE e incontinencia de orina mixta (IOM) mediante TOT, y determinar la tasa de complicaciones perioperatorias.
Métodos: Se realizó un estudio retrospectivo de cohorte de 8 años de seguimiento, en el que se evaluó mediante anamnesis, examen fÃsico y protocolos quirúrgicos la tasa de éxito objetivo y subjetivo del TOT.
Resultados: La tasa de éxito objetivo y subjetivo fue 92% y 76% respectivamente. El 8,3% de las pacientes presentó alguna complicación y la tasa de exposición de malla fue de 1,2%.
Conclusiones: El TOT es una excelente alternativa para el tratamiento de la IOE en el Hospital de Quilpué.http://ref.scielo.org/6tnxn
Conceptualising routes to employability in higher education: the case of education studies
© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. This paper contributes to critical understandings of the significance of employability in current debates about the transformation of Higher Education (HE). We express our concerns about the implications of orientating HE to utilitarian demands in the light of a tendency to align discussions about the significance of studying at university with the idea of employability. The research underlying this article explores how the experience of UK university students in the context of education studies programmes shapes their conceptions of employability and their understanding of their subject of study. Ideas developed by Gert Biesta are used as a framework to discuss different forms in which thoughts about employability are articulated. The analysis of data that includes reflections on the experience of placement suggests that tensions between education as training for teachers and education as the possibility for change, point to the emergence of a new form of understanding employability that may have to work the boundary between both. We argue that lessons learnt from the case of education studies can be useful to other subjects and programmes of study that also share an interest in the theoretical study of a discipline or where a narrow career expectation is being challenged by broader possibilities
Scale-free Networks from Optimal Design
A large number of complex networks, both natural and artificial, share the
presence of highly heterogeneous, scale-free degree distributions. A few
mechanisms for the emergence of such patterns have been suggested, optimization
not being one of them. In this letter we present the first evidence for the
emergence of scaling (and smallworldness) in software architecture graphs from
a well-defined local optimization process. Although the rules that define the
strategies involved in software engineering should lead to a tree-like
structure, the final net is scale-free, perhaps reflecting the presence of
conflicting constraints unavoidable in a multidimensional optimization process.
The consequences for other complex networks are outlined.Comment: 6 pages, 2 figures. Submitted to Europhysics Letters. Additional
material is available at http://complex.upc.es/~sergi/software.ht
Preparation of polyfunctional arylzinc organometallics in toluene by halogen/zinc exchange reactions
A wide range of polyfunctional diaryl-and diheteroarylzinc species were prepared in toluene within 10 min to 5 h through an I/Zn or Br/Zn exchange reaction using bimetallic reagents of the general formula R’2Zn·2LiOR (R’=sBu, tBu, pTol). Highly sensitive functional groups, such as a triazine, a ketone, an aldehyde, or a nitro group, were tolerated in these exchange reactions, enabling the synthesis of a plethora of functionalized (hetero)arenes after quenching with various electrophiles. Insight into the constitution and reactivity of these bimetallic mixtures revealed the formation of highly active lithium diorganodialkoxyzincates of type[R’2Zn-(OR)2Li2]
Signatures of arithmetic simplicity in metabolic network architecture
Metabolic networks perform some of the most fundamental functions in living
cells, including energy transduction and building block biosynthesis. While
these are the best characterized networks in living systems, understanding
their evolutionary history and complex wiring constitutes one of the most
fascinating open questions in biology, intimately related to the enigma of
life's origin itself. Is the evolution of metabolism subject to general
principles, beyond the unpredictable accumulation of multiple historical
accidents? Here we search for such principles by applying to an artificial
chemical universe some of the methodologies developed for the study of genome
scale models of cellular metabolism. In particular, we use metabolic flux
constraint-based models to exhaustively search for artificial chemistry
pathways that can optimally perform an array of elementary metabolic functions.
Despite the simplicity of the model employed, we find that the ensuing pathways
display a surprisingly rich set of properties, including the existence of
autocatalytic cycles and hierarchical modules, the appearance of universally
preferable metabolites and reactions, and a logarithmic trend of pathway length
as a function of input/output molecule size. Some of these properties can be
derived analytically, borrowing methods previously used in cryptography. In
addition, by mapping biochemical networks onto a simplified carbon atom
reaction backbone, we find that several of the properties predicted by the
artificial chemistry model hold for real metabolic networks. These findings
suggest that optimality principles and arithmetic simplicity might lie beneath
some aspects of biochemical complexity
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