1,233 research outputs found

    COINTEGRATION AND THE FORECAST ACCURACY OF VAR MODELS

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    This paper assesses the forecast performance of a set of VAR models under a growing number of restrictions. With a maximum forecast horizon of 12 years, we show that the farther the horizon is, the more structured and restricted VAR models have to be to produce accurate forecasts. Indeed, unrestricted VAR models, not subjected to integration or cointegration, are poor forecasters for both short and long run horizons. Differenced VAR models, subject to integration, are reliable predictors for one-step horizons but ineffectual for multi-step horizons. Cointegrated VAR models including appropriate structural breaks and exogenous variables, as well as being subjected to over-identifying theory consistent restrictions, are excellent forecasters for both short and long run horizons. Hence, to obtain precise forecasts from VAR models, proper specification and cointegration are crucial for whatever horizons are at stake, while integration is relevant only for short run horizons.VAR demand systems; structural breaks, exogenous regressors, integration; cointegration; forecast accuracy.

    Testing Alternative Dynamic Systems for Modelling Tourism Demand

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    The goals in this paper are to contribute an empirical study of tourism demand dynamics, and to point out areas where the scrutiny of relationships between theoretical and empirical considerations are likely to produce new insights in this area of research. A flexible general form of a Dynamic Almost Ideal Demand System (DAIDS) is derived to analyse the UK tourism demand for its geographically proximate neighbours Portugal, Spain and France, in the period 1969-1997. Nested within the general dynamic structure are Deaton and Muellbauer’s static AIDS model itself, the partial adjustment model and the auto-regressive distributed lag model, which are tested against the general dynamic alternative. The empirical results obtained show that DAIDS is a data coherent and theoretically consistent model, providing evidence of the robustness of this methodology to conduct tourism demand analysis in a temporal context. Moreover, the dynamic model offers statistically strong evidence on the inadequacy of the orthodox static AIDS and the other restricted models to reconcile consistently data and theory within their formulations. Estimates for tourism price and expenditure elasticities are obtained, permitting a comparative analysis of the relative magnitudes and statistical relevance of long and short run sensitivity of the UK tourism demand to changes in its determinants.Tourism Demand, dynamic almost ideal system, partial adjustment system, autoregressive distributed lag system.

    The interdependence between the saving rate and technology across regimes : evidence from South Africa

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    Abstract: This paper hypothesises that the saving rate and technological progress are interdependently determined by a common exogenous source, so that an exogenous shock to the saving rate determines long-run growth transitions. In an open-economy setting, the saving rate measures the quality of investment-led policies. The evidence shows that the down-break across South Africa’s ‘faster-growing’ regime (1952-1976) and ‘slower-growing’ regime (1977-2003) was caused by a negative shock to the saving rate that simultaneously led to a slowdown in the growth rate of technology via a structural decrease in the learning-by-doing parameter. The down-break results suggest that the saving rate is potentially an important policy variable to engineer a sustainable up-break. To assess this prediction with real data, the analysis looks at what happened in the post- 2003 period (2004-2012). The results show that the up-break in the fixed investment rate was not matched by the saving rate, which implies that capital investment did not generate a faster rate of technological progress. The stylised facts suggest that a sustained increase in the total investment rate, which not only includes infrastructure investment, but also machinery and equipment investment and complementary foreign direct investment, may be an effective investment-led strategy to raise the economy’s growth rate on a sustainable basis

    A INTENÇÃO DE LEALDADE À UNIVERSIDADE A PARTIR DA ANÁLISE DO PERFIL DE ALUNOS DO CURSO DE ADMINISTRAÇÃO DE UMA UNIVERSIDADE PÚBLICA

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    Universidades cada vez mais necessitam ter um gerenciamento profissional, especialmente, objetivando o atendimento Ă s necessidades dos alunos. A lealdade de alunos pode contribuir para a existĂȘncia de benefĂ­cios pessoais, sociais e institucionais. Entretanto, algumas caracterĂ­sticas interferem na lealdade daqueles que buscam serviços na ĂĄrea de educação. Buscando conhecer as caracterĂ­sticas que influenciam na lealdade de alunos universitĂĄrios, o presente artigo buscou realizar uma pesquisa descritiva e quantitativa com alunos do curso de Administração de uma universidade pĂșblica no sul do Brasil. Os resultados indicam que alunos em geral sentem-se leais, e nesta pesquisa as mulheres. Alunos de maior idade tendem e ser mais leais, assim como aqueles que estudaram em escolas pĂșblicas e nasceram em outra cidade. A lealdade varia em relação a semestres que o aluno estava cursando

    Spatial distribution of heterochromatin bodies in the nuclei of Triatoma infestans (Klug)

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    Constitutive heterochromatin typically exhibits low gene density and is commonly found adjacent or close to the nuclear periphery, in contrast to transcriptionally active genes concentrated in the innermost nuclear region. In Triatoma infestans cells, conspicuous constitutive heterochromatin forms deeply stained structures named chromocenters. However, to the best of our knowledge, no information exists regarding whether these chromocenters acquire a precise topology in the cell nuclei or whether their 18S rDNA, which is important for ribosome function, faces the nuclear center preferentially. In this work, the spatial distribution of fluorescent Feulgen-stained chromocenters and the distribution of their 18S rDNA was analyzed in Malpighian tubule cells of T. infestans using confocal microscopy. The chromocenters were shown to be spatially positioned relatively close to the nuclear periphery, though not adjacent to it. The variable distance between the chromocenters and the nuclear periphery suggests mobility of these bodies within the cell nuclei. The distribution of 18S rDNA at the edge of the chromocenters was not found to face the nuclear interior exclusively. Because the genome regions containing 18S rDNA in the chromocenters also face the nuclear periphery, the proximity of the chromocenters to this nuclear region is not assumed to be associated with overall gene silencing.133CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP304668/2014-1; 304668/2014-1Não tem2015/10356-2This research was supported by the São Paulo State Research Foundation (FAPESP, Brazil; grant no. 2015/10356-2) and the Brazilian National Council for Research and Development (CNPq, grant no. 304668/2014-1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. C.H.L.I. received a fellowship from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil – Finance Code 001). M.L.S.M. received a fellowship from CNPq (grant no. 304668/2014-1)

    Neuroinflammation and Neurotransmission Mechanisms Involved in Neuropsychiatric Disorders

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    Some classical psychiatric disorders, such as schizophrenia, autism, major depression, bipolar and obsessive‐compulsive disorders, have been related to neuroinflammatory process, immunological abnormalities, and neurotransmission impairment beyond genetic mutations. Neuroinflammation is mostly regulated by glial cells, which respond to physiological and pathological stimuli by anti‐ and pro‐inflammatory cytokine and chemokine signaling; moreover, recent studies have indicated that glial cells also respond to the neurotransmitters. Neurotransmitters regulate many biological processes, such as cell proliferation and synaptogenesis, which contribute to the formation of functional circuits. Alterations in the neurotransmission can lead to many pathological changes that occur in brain disorders. For example, studies have shown that neuroinflammation can alter the metabolism of glutamate as well as the function of its transporters, resulting in cognitive, behavioral, and psychiatric impairments. Cytokines as IL‐1ÎČ and IL‐6 appear to have an important influence in the dopaminergic and serotoninergic neurons. These data together suggest that glial cells via cytokines and abnormal regulation of neurotransmitters can influence psychiatric disorders. The present knowledge about this issue does not allow answering whether neuroinflammation is the cause or the consequence of neurotransmission imbalance and emphasizes the importance to improve in vivo imaging methods and models to elucidate this enigma
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