4,352 research outputs found
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Thirlwall's law and the specification of export and import functions
The contribution of this paper is threefold. First, it proposes general specifications for export and import functions that encompass the contributions of both Kaldorian and Schumpeterian literatures on the determinants of trade performance. Second, the paper provides evidence of the impact of nonprice competitiveness, measured by the growth of relative economic efficiency on export and import growth in different technological sectors. Third, it shows that the magnitude of income elasticities of demand is partially determined by relative economic efficiency
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The Multi-Sectoral Thirlwall’s Law: evidence from 14 developed European countries using product-level data
The paper reports estimates of import and export functions for five technological sectors in 14 developed European countries. These functions have never before been estimated for developed countries adopting a technological classification of sectors. The paper compares estimates of income elasticities found using vector errorcorrection models employing aggregate deflators, with estimates found using crossproduct panels employing product-specific quality-adjusted price indexes recently calculated by Feenstra and Romalis (2014). The results indicate that the income elasticities of imports and exports are higher for medium- and high-tech manufactures, which suggests the importance of moving from the production of simple goods to the production of goods with high technological content. The estimates suggest also that the Multi-Sectoral Thirlwall’s Law holds for the countries analysed, while comparing the estimates revealed that cross-product panels with quality-adjusted prices generate considerably more robust results. The investigation reveals that using a more recent time period generates estimates of income elasticities of demand for primary products and resource based manufactures that tend to be higher than the estimates found by studies that have used longer time periods, while the opposite holds for low-, medium-, and high-tech manufactures.This is the author accepted manuscript. The final version is available from Taylor & Francis via http://dx.doi.org/10.1080/02692171.2015.110220
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Differences in increasing returns between technological sectors: A panel data investigation using the EU KLEMS database
Purpose
The purpose of this paper is twofold: to investigate the existence of different degrees of returns to scale in low-tech and high-tech manufacturing industries; and to examine whether the degrees of returns to scale change through time.
Design/methodology/approach
The empirical investigation implemented in the paper uses data from the EU KLEMS Database, covering a sample of 12 manufacturing industries in 11 OECD countries over the period 1976-2006. The investigation employed two different estimation methods: instrumental variables and system GMM. The robustness of the results was assessed by employing two different specifications of Kaldor-Verdoorn’s Law, by using lags and five-year averages to smooth business-cycle fluctuations, and by dividing the sample into two time periods.
Findings
The results reported in the paper provide strong evidence in support of the hypothesis of substantial increasing returns to scale in manufacturing. The investigation suggests that high-tech manufacturing industries exhibit larger degrees of returns to scale than low-tech manufacturing industries. Finally, the analysis revealed also that the magnitude of the returns to scale in manufacturing have increased in the last decades, driven by increases in the magnitude of returns to scale observed in high-tech industries.
Originality/value
No previous work has assessed the hypothesis that increasing returns to scale vary according to the technological content of industries. Moreover, no previous work has used system GMM or data from EU KLEMS to test Kaldor-Verdoorn’s Law. Most importantly, the findings of the paper present new evidence on the degree of returns to scale in high-tech and low-tech manufacturing industries.
The authors would like to thank Dr. Marta Spreafico and two anonymous referees for their helpful comments. The usual disclaimer applies. Financial support from the Coordination for the Improvement of Higher Education Personnel (CAPES-Brazil), process number 0257-11-7, is gratefully acknowledged.This is the author accepted manuscript. The final version is available from Journal of Economic Studies via https://doi.org/10.1108/JES-03-2015-004
Case Report: Rare Convexity Meningeal Chondroma Mimicking a Meningioma
Background: Intracranial chondromas account for 0.2-0.3% of all intracranial neoplastic lesions and less than a quarter arise in the convexity or falx. Despite its benign nature, exceedingly rare malignant transformations exist. The misdiagnosis with meningiomas is frequent and may be related with chondromas' similar insidious clinical presentation and imaging features. Standalone surgery is advised and complete resection provides the definitive treatment.
Case description: A 44-year-old female presents with insidious headache, visual disturbances, and papilledema. The imaging studies were compatible with frontal parasagittal meningioma. Surgery revealed a meningeal based mass, mostly avascular and with a well-demarked surgical plane from the brain parenchyma. Complete resection with meningeal margins was achieved and the histopathologic examination revealed a chondroma. The patient symptoms subsided and no surgical complications existed.
Conclusion: Intracranial convexity chondromas constitute a rare differential diagnosis for meningiomas. The present case reinforces the current scarce data and serves as reminder for clinicians diagnosing and treating intracranial tumors.info:eu-repo/semantics/publishedVersio
Multifrequency Strategies for the Identification of Gamma-Ray Sources
More than half the sources in the Third EGRET (3EG) catalog have no firmly
established counterparts at other wavelengths and are unidentified. Some of
these unidentified sources have remained a mystery since the first surveys of
the gamma-ray sky with the COS-B satellite. The unidentified sources generally
have large error circles, and finding counterparts has often been a challenging
job. A multiwavelength approach, using X-ray, optical, and radio data, is often
needed to understand the nature of these sources. This chapter reviews the
technique of identification of EGRET sources using multiwavelength studies of
the gamma-ray fields.Comment: 35 pages, 22 figures. Chapter prepared for the book "Cosmic Gamma-ray
Sources", edited by K.S. Cheng and G.E. Romero, to be published by Kluwer
Academic Press, 2004. For complete article and higher resolution figures, go
to: http://www.astro.columbia.edu/~muk/mukherjee_multiwave.pd
Synthetic RNA Silencing of Actinorhodin Biosynthesis in Streptomyces coelicolor A3(2)
We demonstrate the first application of synthetic RNA gene silencers in Streptomyces coelicolor A3(2). Peptide nucleic acid and expressed antisense RNA silencers successfully inhibited actinorhodin production. Synthetic RNA silencing was target-specific and is a new tool for gene regulation and metabolic engineering studies in Streptomyces.Peer reviewe
Protective effect of stromal Dickkopf-3 in prostate cancer: opposing roles for TGFBI and ECM-1
Aberrant transforming growth factor–β (TGF-β) signaling is a hallmark of the stromal microenvironment in cancer. Dickkopf-3 (Dkk-3), shown to inhibit TGF-β signaling, is downregulated in prostate cancer and upregulated in the stroma in benign prostatic hyperplasia, but the function of stromal Dkk-3 is unclear. Here we show that DKK3 silencing in WPMY-1 prostate stromal cells increases TGF-β signaling activity and that stromal cellconditioned media inhibit prostate cancer cell invasion in a Dkk-3-dependent manner. DKK3 silencing increased the level of the cell-adhesion regulator TGF-β–induced protein (TGFBI) in stromal and epithelial cell-conditioned media, and recombinant TGFBI increased prostate cancer cell invasion. Reduced expression of Dkk-3 in patient tumors was associated with increased expression of TGFBI. DKK3 silencing reduced the level of extracellular matrix protein-1 (ECM-1) in prostate stromal cell-conditioned media but increased it in epithelial cell-conditioned media, and recombinant ECM-1 inhibited TGFBI-induced prostate cancer cell invasion. Increased ECM1 and DKK3 mRNA expression in prostate tumors was associated with increased relapse-free survival. These observations are consistent with a model in which the loss of Dkk-3 in prostate cancer leads to increased secretion of TGFBI and ECM-1, which have tumor-promoting and tumor-protective roles, respectively. Determining how the balance between the opposing roles of extracellular factors influences prostate carcinogenesis will be key to developing therapies that target the tumor microenvironment
Evaluating the Quality of Research into a Single Prognostic Biomarker: A Systematic Review and Meta-analysis of 83 Studies of C-Reactive Protein in Stable Coronary Artery Disease
Background
Systematic evaluations of the quality of research on a single prognostic biomarker are rare. We sought to evaluate the quality of prognostic research evidence for the association of C-reactive protein (CRP) with fatal and nonfatal events among patients with stable coronary disease.
Methods and Findings
We searched MEDLINE (1966 to 2009) and EMBASE (1980 to 2009) and selected prospective studies of patients with stable coronary disease, reporting a relative risk for the association of CRP with death and nonfatal cardiovascular events. We included 83 studies, reporting 61,684 patients and 6,485 outcome events. No study reported a prespecified statistical analysis protocol; only two studies reported the time elapsed (in months or years) between initial presentation of symptomatic coronary disease and inclusion in the study. Studies reported a median of seven items (of 17) from the REMARK reporting guidelines, with no evidence of change over time.
The pooled relative risk for the top versus bottom third of CRP distribution was 1.97 (95% confidence interval [CI] 1.78–2.17), with substantial heterogeneity (I2 = 79.5). Only 13 studies adjusted for conventional risk factors (age, sex, smoking, obesity, diabetes, and low-density lipoprotein [LDL] cholesterol) and these had a relative risk of 1.65 (95% CI 1.39–1.96), I2 = 33.7. Studies reported ten different ways of comparing CRP values, with weaker relative risks for those based on continuous measures. Adjusting for publication bias (for which there was strong evidence, Egger's p<0.001) using a validated method reduced the relative risk to 1.19 (95% CI 1.13–1.25). Only two studies reported a measure of discrimination (c-statistic). In 20 studies the detection rate for subsequent events could be calculated and was 31% for a 10% false positive rate, and the calculated pooled c-statistic was 0.61 (0.57–0.66).
Conclusion
Multiple types of reporting bias, and publication bias, make the magnitude of any independent association between CRP and prognosis among patients with stable coronary disease sufficiently uncertain that no clinical practice recommendations can be made. Publication of prespecified statistical analytic protocols and prospective registration of studies, among other measures, might help improve the quality of prognostic biomarker research
The phase difference between neural drives to antagonist muscles in essential tremor is associated with the relative strength of supraspinal and afferent input
The pathophysiology of essential tremor (ET), the most common movement disorder, is not fully understood. We investigated which factors determine the variability in the phase difference between neural drives to antagonist muscles, a long-standing observation yet unexplained. We used a computational model to simulate the effects of different levels of voluntary and tremulous synaptic input to antagonistic motoneuron pools on the tremor. We compared these simulations to data from 11 human ET patients. In both analyses, the neural drive to muscle was represented as the pooled spike trains of several motor units, which provides an accurate representation of the common synaptic input to motoneurons. The simulations showed that, for each voluntary input level, the phase difference between neural drives to antagonist muscles is determined by the relative strength of the supraspinal tremor input to the motoneuron pools. In addition, when the supraspinal tremor input to one muscle was weak or absent, Ia afferents provided significant common tremor input due to passive stretch. The simulations predicted that without a voluntary drive (rest tremor) the neural drives would be more likely in phase, while a concurrent voluntary input (postural tremor) would lead more frequently to an out-of-phase pattern. The experimental results matched these predictions, showing a significant change in phase difference between postural and rest tremor. They also indicated that the common tremor input is always shared by the antagonistic motoneuron pools, in agreement with the simulations. Our results highlight that the interplay between supraspinal input and spinal afferents is relevant for tremor generation
IL-4-secreting CD4+ T cells are crucial to the development of CD8+ T-cell responses against malaria liver stages.
CD4+ T cells are crucial to the development of CD8+ T cell responses against hepatocytes infected with malaria parasites. In the absence of CD4+ T cells, CD8+ T cells initiate a seemingly normal differentiation and proliferation during the first few days after immunization. However, this response fails to develop further and is reduced by more than 90%, compared to that observed in the presence of CD4+ T cells. We report here that interleukin-4 (IL-4) secreted by CD4+ T cells is essential to the full development of this CD8+ T cell response. This is the first demonstration that IL-4 is a mediator of CD4/CD8 cross-talk leading to the development of immunity against an infectious pathogen
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