770 research outputs found
On the road to prosperity? The economic geography of China's national expressway network
Over the past two decades, China has embarked on an ambitious program of expressway network expansion. By facilitating market integration, this program aims both to promote efficiency at the national level and to contribute to the catch-up of lagging inland regions with prosperous Eastern ones. This paper evaluates the aggregate and spatial economic impacts of China's newly constructed National Expressway Network, focussing, in particular, on its short-run impacts. To achieve this aim, the authors adopt a counterfactual approach based on the estimation and simulation of a structural "new economic geography" model. Overall, they find that aggregate Chinese real income was approximately 6 percent higher than it would have been in 2007 had the expressway network not been built. Although there is considerable heterogeneity in the results, the authors do not find evidence of a significant reduction in disparities across prefectural level regions or of a reduction in urban-rural disparities. If anything, the expressway network appears to have reinforced existing patterns of spatial inequality, although, over time, these will likely be reduced by enhanced migration
I can do that alone… or not? How idea generators juggle between the pros and cons of teamwork
The advantages of working with a team to develop an idea are well established but surprisingly little is known about why some idea generators ignore these advantages by developing their ideas alone. To answer this question, we study two important trade-offs. First, working with a team provides access to additional resources but also leads to increased coordination costs. Second, sharing the risks and costs of developing an idea necessitates sharing the potential rewards of a successful idea. We use unique data on idea generators and their submission of ideas to an innovation program in a large European company between 1996 and 2008 to show how the two different trade-offs affect the decision of idea generators to collaborate with a team
I can do that alone… or not? How idea generators juggle between the pros and cons of teamwork
The advantages of working with a team to develop an idea are well established but surprisingly little is known about why some idea generators ignore these advantages by developing their ideas alone. To answer this question, we study two important trade-offs. First, working with a team provides access to additional resources but also leads to increased coordination costs. Second, sharing the risks and costs of developing an idea necessitates sharing the potential rewards of a successful idea. We use unique data on idea generators and their submission of ideas to an innovation program in a large European company between 1996 and 2008 to show how the two different trade-offs affect the decision of idea generators to collaborate with a team
Exploring break-points and interaction effects among predictors of the international digital divide
Cataloged from PDF version of article.The deepening of the digital divide between countries has prompted international
organizations and governments to work together toward reducing the problem over
the next 15 years. However, such efforts will likely succeed only if they are based on a
firm grasp of the divide's underlying causes. In this paper we report the results of a
comprehensive analysis of the determinants of the international digital divide. Our
results confirm many findings of past research, but also extend existing knowledge in
important ways. By employing Multivariate Adaptive Regression Splines (MARS), we
discover non-linearities and interaction effects among the predictors. We then
articulate significant policy implications based upon these findings
Ideas with impact : how connectivity shapes diffusion
Despite a growing body of research on idea diffusion, there is a lack of knowledge on why some ideas successfully diffuse and stand out from the crowd while others do not surface or remain unnoticed. We address this question by looking into the characteristics of an idea, specifically its connectivity in a content network. In a content network, ideas connect to other ideas through their content the words that the ideas have in common. We hypothesize that a high connectivity of an idea in a content network is beneficial for idea diffusion because this idea will more likely be conceived as novel yet at the same time also as more useful because it appears as more familiar to the audience. Moreover, we posit that a high social connectivity of the team working on the idea further enhances the effect of high content connectivity on idea diffusion. Our study focuses on academic conference publications and the co-authorship data of a community of computer science researchers from 2006 to 2012. We find confirmation for our hypotheses and discuss the implications of these findings
Diagnosing melanoma patients entering American Joint Committee on Cancer stage IV, C-reactive protein in serum is superior to lactate dehydrogenase
Optimized EPI for fMRI studies of the orbitofrontal cortex: compensation of susceptibility-induced gradients in the readout direction
Object Most functional magnetic resonance imaging (fMRI) studies record the blood oxygen leveldependent (BOLD) signal using gradient-echo echo-planar imaging (GE EPI). EPI can suffer from substantial BOLD sensitivity loss caused by magnetic field inhomogeneities. Here, BOLD sensitivity losses due to susceptibility- induced gradients in the readout (RO) direction are characterized and a compensation approach is developed
The left superior temporal gyrus is a shared substrate for auditory short-term memory and speech comprehension: evidence from 210 patients with stroke
Competing theories of short-term memory function make specific predictions about the functional anatomy of auditory short-term memory and its role in language comprehension. We analysed high-resolution structural magnetic resonance images from 210 stroke patients and employed a novel voxel based analysis to test the relationship between auditory short-term memory and speech comprehension. Using digit span as an index of auditory short-term memory capacity we found that the structural integrity of a posterior region of the superior temporal gyrus and sulcus predicted auditory short-term memory capacity, even when performance on a range of other measures was factored out. We show that the integrity of this region also predicts the ability to comprehend spoken sentences. Our results therefore support cognitive models that posit a shared substrate between auditory short-term memory capacity and speech comprehension ability. The method applied here will be particularly useful for modelling structure–function relationships within other complex cognitive domains
Eimeria species occurrence varies between geographic regions and poultry production systems and may influence parasite genetic diversity
Coccidiosis is one of the biggest challenges faced by the global poultry industry. Recent studies have highlighted the ubiquitous distribution of all Eimeria species which can cause this disease in chickens, but intriguingly revealed a regional divide in genetic diversity and population structure for at least one species, Eimeria tenella. The drivers associated with such distinct geographic variation are unclear, but may impact on the occurrence and extent of resistance to anticoccidial drugs and future subunit vaccines. India is one of the largest poultry producers in the world and includes a transition between E. tenella populations defined by high and low genetic diversity. The aim of this study was to identify risk factors associated with the prevalence of Eimeria species defined by high and low pathogenicity in northern and southern states of India, and seek to understand factors which vary between the regions as possible drivers for differential genetic variation. Faecal samples and data relating to farm characteristics and management were collected from 107 farms from northern India and 133 farms from southern India. Faecal samples were analysed using microscopy and PCR to identify Eimeria occurrence. Multiple correspondence analysis was applied to transform correlated putative risk factors into a smaller number of synthetic uncorrelated factors. Hierarchical cluster analysis was used to identify poultry farm typologies, revealing three distinct clusters in the studied regions. The association between clusters and presence of Eimeria species was assessed by logistic regression. The study found that large-scale broiler farms in the north were at greatest risk of harbouring any Eimeria species and a larger proportion of such farms were positive for E. necatrix, the most pathogenic species. Comparison revealed a more even distribution for E. tenella across production systems in south India, but with a lower overall occurrence. Such a polarised region- and system-specific distribution may contribute to the different levels of genetic diversity observed previously in India and may influence parasite population structure across much of Asia and Africa. The findings of the study can be used to prioritise target farms to launch and optimise appropriate anticoccidial strategies for long-term control
Preponderance of the oncogenic V599E and V599K mutations in B-raf kinase domain is enhanced in melanoma cutaneous/subcutaneous metastases
BACKGROUND: Downstream of Ras, the serine/threonine kinase B-raf has been reported to be mutated, among other carcinomas, in a substantial subset of primary melanomas with a preponderance of mutations within the kinase domain including the activating V599E and V599K transitions. METHODS: We here investigated a representative series of 60 resection specimens of cutaneous and subcutaneous melanoma metastases for the presence of mutations within the activation segment (exon 15) of the B-raf kinase domain by polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) gel electrophoresis. RESULTS: Sequencing of cloned PCR-SSCP amplicons resulted in 24 (40%) samples harbouring somatic mutations which is not exceeding the mutation frequency in recently investigated primary melanomas. The activating mutation T1796A was present in 24/60 (40%) resection specimens, followed in frequency by the oncogenic g1795A mutation in 8/60 (13%) cases. As to the B-raf protein sequence, the acidic amino acid transitions V599E and V599K were predicted in 19/60 (32%) and 6/60 (10%) cases, resepectively, but were not associated with enhanced risk for subsequent metastasis in patients' follow up. In comparison to the primary melanomas that we recently investigated, the spectrum of predicted B-raf protein mutations narrowed significantly in the cutaneous/subcutaneous metastases. Unexpectedly, V599 and V599E mutations were absent in cutaneous/subcutaneous metastases derived from acrolentiginous melanomas as preceding primary tumours. CONCLUSION: During transition from primary melanomas towards cutaneous/subcutaneous metastases, the spectrum of predicted B-raf mutations narrows significantly. Focusing on the V599E and V599K, these oncogenic mutations are likely to affect melanocyte-specific pathways controlling proliferation and differentiation
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