A bijection between noncrossing and nonnesting partitions of types A and B

The total number of noncrossing partitions of type $\Psi$ is the $n$th Catalan number $\frac{1}{n+1}\binom{2n}{n}$ when $\Psi=A_{n-1}$, and the binomial $\binom{2n}{n}$ when $\Psi=B_n$, and these numbers coincide with the correspondent number of nonnesting partitions. For type A, there are several bijective proofs of this equality, being the intuitive map that locally converts each crossing to a nesting one of them. In this paper we present a bijection between nonnesting and noncrossing partitions of types A and B that generalizes the type A bijection that locally converts each crossing to a nesting.Comment: 11 pages, 11 figures. Inverse map described. Minor changes to correct typos and clarify conten

Brand effects, mobility costs and industry evolution

In this paper I present a model that was built in order to analyse the interdependencies between labour market dynamics and the evolution of industries’ structure. Being inspired by the case of consultancy services, the model integrates many of the features typically found in those industries. In particular, problems of incomplete information, the role of ‘brand effects’, and constraints in the supply of specialised labour, are taken into account. This model is able to reproduce many of the empirical regularities that have been identified in studies of industrial dynamics on the basis of causal mechanisms that are absent from most theoretical models, and it shows to be a useful tool in understanding some features of the evolution of real world industries.

Does innovation (really) matter for success? The case of an IT Consulting Firm

The paper discusses to what extent innovation is a crucial variable in explaining the success of NOVABASE, a Portuguese IT consultancy firm. In order to proceed with this discussion, the evolution of NOVABASE is described, emphasizing the most important steps in the firm’s trajectory, which are shown to result from the joint influences of upstream technological change, downstream market opportunities, and the firm’s strategic options. Then, the paper reviews some contributions stemming form studies of innovation in services, building on these to form the framework of analysis used in the empirical research. The main results of the empirical work are then presented, leading to the discussion of the possible answers to the question in title.

Towards an integrated approach to industry dynamics and labour mobility

Industrial dynamics and labour mobility are two fields of economic research that have developed fast in recent years, but along what are essentially separate lines. This paper shows that the processes those two fields deal with can be highly interdependent, and demonstrates the usefulness of (and the opportunity for) an integrated approach to the dynamics of industries and labour mobility. It concludes with a list of questions that inform a research agenda dedicated to such approach.

On Noncrossing and nonnesting partitions of type D

We present an explicit bijection between noncrossing and nonnesting partitions of Coxeter systems of type D which preserves openers, closers and transients.Comment: 13 pages, 10 figures. A remark on a reference has been correcte

Electrophysiological studies in healthy subjects involving caffeine

Copyright ©2012 IOS Press All rights reserved.We review the electrophysiological studies concerning the effects of caffeine on muscle, lower and upper motor neuron excitability and cognition. Several different methods have been used, such as electromyography, recruitment analysis, H-reflex, transcranial magnetic stimulation (TMS), electroencephalography and event-related potentials. The positive effect of caffeine on vigilance, attention, speed of reaction, information processing and arousal is supported by a number of electrophysiological studies. The evidence in favor of an increased muscle fiber resistance is not definitive, but higher or lower motor neuron excitability can occur as a consequence of a greater excitation of the descending input from the brainstem and upper motor neurons. TMS can address the influence of caffeine on the upper motor neuron. Previous studies showed that cortico-motor threshold and intracortical excitatory and inhibitory pathways are not influenced by caffeine. Nonetheless, our results indicate that cortical silent period (CSP) is reduced in resting muscles after caffeine consumption, when stimulating the motor cortex with intensities slightly above threshold. We present new data demonstrating that this effect is also observed in fatigued muscle. We conclude that CSP can be considered a surrogate marker of the effect of caffeine in the brain, in particular of its central ergogenic effect

A calculadora e a resolução de problemas: uma experiência na sala de aula

[Resumo] Parece ser de consenso geral que a Educação Matemática deve ajustar-se as necessidades da sociedade e dos alunos. As competencias matemáticas básicas tradicionais nao sao suficientes para os desafios actuais. O que se aprende na escola elementar é a base para todos os estudos matemáticos posteriores. As grandes finalidades do ensino da Matemática no 10 Ciclo assentam no desenvolvimento de tres capacidades fundamentais: (a) a capacidade de raciocínio; (b) a capacidade de comunicação; (c) a capacidade de resolução de problemas. Defende-se que a resolução de situaçoes problemáticas, numéricas ou nao numéricas, deve estar presente em todos os tópicos de ensino. Neste contexto, nao pode deixar de dar-se importancia aos meios de cálculos. O cálculo mental, o cálculos escrito e o cálculo realizado com a calculadora devem ser explorados na sala de aula e trabalhados pelos alunos. É importante que as crianças do 1.0 Ciclo estejam aptas a efectuar cálculos utilizando qualquer um destes meios, bem como a decidir qual dos meios é mais adequado a determinada situação. Contudo, parece haver urna resistencia a utilização da calculadora na sala de aula, enquanto meio auxiliar de cálculo. Assim, esta investigação visa, fundamentalmente, compreender o papel atribuído a calculadora pelas crianças, na resolu~aode problemas. O estudo incide sobre urna turma do 40ano, do 10 Ciclo, da cidade de Braga. Analisam-se estratégias e meios de cálculo utilizados pelas crianças na resolução de problemas

Exploring young children’s reasoning and naming of fractions

This study investigates the effects of a teaching intervention on children’s reasoning and naming of fractions in quotient, part-whole and operator situations. A pre-test, intervention and post-test design was used with 37 six- to seven-year-olds from primary schools in Braga, Portugal. The children had not been taught about fractions in school. Reasoning and labelling questions were presented in the three situations in the pre- and post-test. During teaching, each intervention group learned about fractions in only one of the three situations. Children who were taught in the quotient situation made significant progress in the reasoning and naming fractions, but did not transfer this learning to the other situations. Children taught in the part-whole or in the operator situations only learned how to label fractions, showing no progress on reasoning items. However, they used the labels in both part-whole and operator items. Thus these situations affect differently children’s understanding of fractions.CIEC - Centro de Investigação em Estudos da Criança, IE, UMinho (UI 317 da FCT), PortugalFundos Nacionais através da FCT (Fundação para a Ciência e a Tecnologia) e cofinanciado pelo Fundo Europeu de Desenvolvimento Regional (FEDER) através do COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) com a referência POCI-01-0145-FEDER-007562info:eu-repo/semantics/publishedVersio