2,332 research outputs found
The effect of school quality on educational attainment and wages
The paper examines the effects of school pupil-teacher ratios and type of school on educational attainment and wages using the British National Child Development survey (NCDS). The NCDS is a panel survey which has followed a cohort of individuals born in March 1958, and has a rich set of background variables recorded throughout the individual's life. The results suggest that, once we control for ability and family background, the pupil-teacher ratio has no impact on educational qualifications or on male wages. It has an impact on women's wages at the age of 33, particularly those of low ability. We also find evidence that those who attend selective schools have better educational outcomes and, in the case of men, higher wages at the age of 33. The impact is higher for the type of individuals who are less likely not to attend selective schools, but for whom a comparison group does exist among those attending.
Enrichment of rare genetic variants in astrocyte gene enriched co-expression modules altered in postmortem brain samples of schizophrenia
The transcriptome profiles of the cingulate gyrus region from the postmortem brain tissues of a set of well-characterized patients with schizophrenia (SCZ) and matched controls were investigated using an integrated approach that analyzed both the alterations in transcription expression pattern and rare genetic variants in expressed genes. We demonstrated increased expression of astrocyte-related genes using spatiotemporal co-expression modules that have previously been established for developing human brain, and showed these results are independent of medication dosage. The relationship between genetic variants and expression pattern in the context of neurodevelopment was further investigated, and we identified an enrichment of rare genetic variants in a set of signature genes that were specific to astrocytes and up-regulated in the patients with SCZ. Our result suggested the involvement of astrocyte malfunction in SCZ pathophysiology. In addition, our approach indicated a novel strategy of narrowing down genetic variants that might contribute to the pathophysiology in the patients with SCZ to a subset of genes that are highly expressed in an affected brain regionThis work was partially supported by a National Alliance for Research in Schizophrenia and Depression (NARSAD) Young Investigator Award (to B.X.)S
The skewness of scientific productivity
This paper exploits a unique 2003-2011 large dataset, indexed by Thomson & Reuters, consisting of
17.2 million disambiguated authors classified into 30 broad scientific fields, as well as the 48.2
million articles resulting from a multiplying strategy in which any article co-authored by two or more
persons is wholly assigned as many times as necessary to each of them. The dataset is characterized
by a large proportion of authors who have their oeuvre in several fields. We measure individual
productivity in two ways that are uncorrelated: as the number of articles per person, and as the mean
citation per article per person in the 2003-2011 period. We analyze the shape of the two types of
individual productivity distributions in each field using size- and scale-independent indicators. For
productivity inequality, we use the coefficient of variation. To assess the skewness of productivity
distributions we use a robust index of skeweness, as well as the Characteristic Scores and Scales
approach. For productivity inequality, we use the coefficient of variation. In each field, we study two
samples: the entire population, and what we call “successful authors”, namely, the subset of
scientists whose productivity is above their field average. The main result is that, in spite of wide
differences in production and citation practices across fields, the shape of field productivity
distributions are very similar across fields. The parallelism of the results for the population as a
whole and for the subset of successful authors when productivity is measured as mean citation per
article per person, reveals the fractal nature of the skewness of scientific productivity in this case.
These results are essentially maintained when any article co-authored by two or more persons is
fractionally assigned to each of them.Ruiz-Castillo also acknowledges financial help from the Spanish MEC through
grant ECO2010-19596
Individual and Field Citation Distributions in 29 Broad Scientific Fields
Using a large unique dataset consisting of 35.1 million authors and 105.3 million articles
published in the period 2000-2016, which are classified into 29 broad scientific fields, we search for
regularities at the individual level for very productive authors with citation distributions of a certain
size, and for the existence of a macro-micro relationship between the characteristics of a scientific field
citation distribution and the characteristics of the individual citation distributions of the authors
belonging to the field. Our main results are the following three. Firstly, although the skewness of
individual citation distributions varies greatly within each field, their average skewness is of a similar
order of magnitude in all fields. Secondly, as in the previous literature, field citation distributions are
highly skewed and the degree of skewness is very similar across fields. Thirdly, the skewness of field
citation distributions is essentially explained in terms of the average skewness of individual authors, as
well as individuals’ differences in mean citation rates and the number of publications per author. These
results have important conceptual and practical consequences: to understand the skewness of field
citation distributions at any aggregate level we must simply explain the skewness of the individual
citation distributions of their very productive authors.This is the second version of a paper with the same title published in this series
in January 2018. J. Ruiz-Castillo acknowledges financial support from the Spanish MEC through grants
ECO2014-55953-P and MDM 2014-0431, as well as grant MadEco-CM (S2015/HUM-3444) from the
Comunidad AutĂłnoma de Madrid. Research assistantship by Patricia Llopis, as well as conversations
with Ricardo Mora, and especially Vincent Traag, are gratefully acknowledged. All remaining
shortcomings are the authors’ sole responsibility
Heterogeneity of collaboration and its relationship with research impact in a biomedical field
This paper analyses existing trends in the collaborative structure of the Pharmacology and Pharmacy field in Spain and explores its relationship with research impact. The evolution in terms of size of the research community, the typology of collaborative links (national, international) and the scope of the collaboration (size of links, type of partners) are studied by means of different measures based on co-authorship. Growing heterogeneity of collaboration and impact of research are observed over the years. Average journal impact (MNJS) and citation score (MNCS) normalised to world average tend to grow with the number of authors, the number of institutions and collaboration type. Both national and international collaboration show MNJS values above the country’s average, but only internationally co-authored publications attain citation rates above the world’s average. This holds at country and institutional sector levels, although not all institutional sectors obtain the same benefit from collaboration. Multilateral collaboration with high-level R&D countries yields the highest values of research impact, although the impact of collaboration with low-level R&D countries has been optimised over the years. Although scientific collaboration is frequently based on individual initiative, policy actions are required to promote the more heterogeneous types of collaboration.Peer reviewe
Crushing analysis and multi-objective crashworthiness optimization of GFRP honeycomb-filled energy absorption devices
[Abstract:] Fuel efficiency and occupant safety are two of the most important concerns in the automotive industry nowadays. Encouraged by the importance of this field of study, this research attempts an improvement in the crashworthiness of a vehicle crash absorber. This component consists in a square hollow steel tube filled with a honeycomb structure made of glass-fiber reinforced polyamide. Surrogate-based optimization techniques are used. The three objective functions chosen — mass, absorbed energy and peak load — are approximated by two different models: multivariate adaptive regression splines and Gaussian process (kriging). The thickness of both parts, the shape of the honeycomb and its height are selected as design variables. Two preliminary analyses of the specimen are performed: the computation of the interaction effect and a comparison of a hollow tube with the specimen. From the results of multi-objective crashworthiness optimization two Pareto frontiers are obtained, one for the absorbed energy and mass, and another one for the absorbed energy and peak load. The results achieved show great improvements on all objective functions compared to the original design. The peak load is reduced by 37% on a specimen with similar mass and absorbed energy, and the specific energy absorbed is increased by 39.5% for a specimen with a similar peak load to the one from the initial model.Xunta de Galicia. INCITE09; 09DPI01118PRXunta de Galicia. INCITE09; GRC2013-05
Size and shape optimization of aluminum tubes with GFRP honeycomb reinforcements for crashworthy aircraft structures
[Abstract:] Crashworthiness optimization of aircraft and automotive structures has become one the main research targets for their respective leading industries. The following research proposes a new design of an aircraft’s vertical strut. The design consists of a hollow aluminum square tube with a glass-fiber reinforced polymer honeycomb-shaped inner structure. Size and shape surrogate-based optimization techniques are used, with the thicknesses of both materials, cell size and cell shape as design variables. The objective function chosen for the single-objective optimization is the specific energy absorption, while the metrics for the multi-objective optimization are the peak force, mass, absorbed energy and the specific energy absorption. An improvement of 22% of the specific energy absorption with low peak force values is obtained from the single-objective optimization by significantly changing all design variables. Two Pareto fronts have been obtained from the multi-objective optimization confronting, the specific energy absorption against the peak force and the mass against the energy absorbed. When compared to the baseline model, the optimized models show substantial improvement, increasing the specific energy absorption by 65% or reducing the peak force by over 55%. It has been observed an important effect of the cell shape on the model’s performance.Ministerio de EconomĂa y Competitividad. MINECO; DPI2013-41893-
New records of Tachybaptus dominicus (Linnaeus, 1766) (Aves, Podicipedidae) south of its currently known distribution in Argentina
We report on 4 records of the Least Grebe, Tachybaptus dominicus (Linnaeus, 1766), to the south of its theoretical distributional limit in CĂłrdoba Province, Argentina. In recent years, these records and others uploaded to citizen science platforms suggest that this species’ distribution extends south of its currently known range.Fil: Castillo, Santiago. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto Multidisciplinario de BiologĂa Vegetal. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas FĂsicas y Naturales. Instituto Multidisciplinario de BiologĂa Vegetal; ArgentinaFil: Costas, Santiago. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto Multidisciplinario de BiologĂa Vegetal. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas FĂsicas y Naturales. Instituto Multidisciplinario de BiologĂa Vegetal; ArgentinaFil: Toledo, Javier MartĂn. Universidad Nacional de CĂłrdoba; ArgentinaFil: Giaquinta, Adrián. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto Multidisciplinario de BiologĂa Vegetal. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas FĂsicas y Naturales. Instituto Multidisciplinario de BiologĂa Vegetal; Argentin
Oligomerization and Cell-Binding Properties of the Avian Reovirus Cell-Attachment Protein Ď‚C
AbstractAvian reovirus protein Ď‚C, the viral cell-attachment protein, is a minor component of the outer-capsid shell of the viral particle that is synthesized in small amounts in infected cells. We cloned the Ď‚C-encoding ORF in vector pIL-2f, expressed it in Escherichia coli, and partially purified the resulting recombinant protein from inclusion bodies. Rabbit polyclonal antibodies raised against the recombinant protein specifically recognized the viral polypeptide in ELISA, immunoprecipitation, and Western blotting. To study the oligomerization capacity and cell-binding affinity of protein Ď‚C, the Ď‚C-encoding ORF was also expressed in chicken embryo fibroblasts (CEFs) and in reticulocyte lysates. In all three systems protein Ď‚C is expressed as a multimer with identical electrophoretic mobility to the naturally occurring protein. Cell-binding experiments show that both in vitro and in vivo expressed protein Ď‚C display affinity for CEF receptors, and this property is exclusively associated with the oligomeric form of the protein. The fact that incubation of CEF cells with the recombinant protein expressed in bacterial cells completely blocks the binding of purified reovirions indicates both that binding of this protein to cells is specific and saturable, and that reovirions and protein Ď‚C bind to the same class of cell receptor. Saturation binding experiments, performed with the recombinant protein expressed in E. coli and with purified reovirions, showed that the number of cellular receptor sites (CRSs) for avian reovirus S1133 is 1.8 Ă— 104 per CEF cell, whereas the number of cellular receptor units (CRUs) for Ď‚C is 2.2 Ă— 105 per CEF cell. These results are consistent with previous reports on the binding of mammalian reoviruses
IC-Tagging and Protein Relocation to ARV muNS Inclusions: A Method to Study Protein-Protein Interactions in the Cytoplasm or Nucleus of Living Cells
Background: Characterization of protein-protein interactions is essential for understanding cellular functions. Although there are many published methods to analyze protein-protein interactions, most of them present serious limitations. In a different study we have characterized a novel avian reovirus muNS-based protein tagging and inclusion targeting method, and demonstrated its validity to purify free an immobilized protein. Methodology/Principal Findings: Here we present a method to identify protein-protein interactions inside living eukaryotic cells (tested in primate and avian cells). When p53 was tagged with Intercoil (IC; muNS residues 477–542), it not only got integrated into muNS cytoplasmic inclusions, but also attracted its known ligand SV40 large T antigen (TAg) to these structures. We have also adapted this system to work within the cell nucleus, by creating muNS-related protein chimeras that form nuclear inclusions. We show that nuclear muNS-derived inclusions are as efficient as cytoplasmic ones in capturing IC-tagged proteins, and that the proteins targeted to nuclear inclusions are able to interact with their known ligands. Conclusions/Significance: Our protein redistribution method does not present the architectural requirement of reconstructing a transcription factor as any of the two-hybrid systems do. The method is simple and requires only cell transfection and a fluorescence microscope. Our tagging method can be used either in the cytoplasm or the nucleus o
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