Hidden Structure and Function in the Lexicon

How many words are needed to define all the words in a dictionary? Graph-theoretic analysis reveals that about 10% of a dictionary is a unique Kernel of words that define one another and all the rest, but this is not the smallest such subset. The Kernel consists of one huge strongly connected component (SCC), about half its size, the Core, surrounded by many small SCCs, the Satellites. Core words can define one another but not the rest of the dictionary. The Kernel also contains many overlapping Minimal Grounding Sets (MGSs), each about the same size as the Core, each part-Core, part-Satellite. MGS words can define all the rest of the dictionary. They are learned earlier, more concrete and more frequent than the rest of the dictionary. Satellite words, not correlated with age or frequency, are less concrete (more abstract) words that are also needed for full lexical power.Comment: 11 pages, 5 figures, 2 table

Mapping the discipline history of education

International audienceInaugurated in 2013, this collective research programme aims to construct an international mapping of the history of education that accounts for recent devel-opments in the field. Our goal is to create a current and retrospective assessment of the discipline's institutional grounding and of the knowledge produced by its practitioners, stretching across national and cultural borders. Ultimately, the pro-gramme will help to increase interactions among scholars and facilitate the crea-tion of collaborative research agendas, thereby augmenting the standing and visibility of the discipline. This text will briefly introduce the programme's conceptual basis, explaining the methodological steps taken to ensure the comparability of data gathered and the transnational and transcontinental character of the study's design. In the second section, we will zoom in on doctoral students' dissertations, which are the opti-mal way to study a discipline's development and potential. Doctoral students and recent graduates are part of a tradition, a school of thought, and yet they constitute that tradition's replacement and renewal. Therefore, as graduate stu-dents carry forth the disciplinary torch, they hold the future of the field in their hands

Grounding Abstract Word Definitions In Prior Concrete Experience

Longman’s Dictionary of Contemporary English (LDOCE) and Cambridge International Dictionary of English (CIDE) have a defining vocabulary of 2000 words from which most but not all of the words are defined. We developed an algorithm, applicable to any dictionary, for recursively deleting words not used in any definition until the corpus is reduced to a subset – a grounding kernel – from which all the words of the complete dictionary are reachable by definition alone. We compared LDOCE’s and CIDE’s defining vocabulary (DV) and grounding kernel (GK) against the rest of its words, on (1) concreteness, (2) imagery and (3) age of acquisition based on the MRC psycholinguistic database [Wilson 1988]. Both GK and DV proved significantly higher on all three scales (p<0.001) for all but 2 of the 12 comparisons (no difference in concreteness in LDOCE for either GK or DV). The difference was also consistently greater using our automatically computed GK than using the DV defined by the compilers of LDOCE and CIDE

Meromorphic solutions of higher order Briot-Bouquet differential equations

For differential equations $P(y^{(k)},y)=0,$ where $P$ is a polynomial, we prove that all meromorphic solutions having at least one pole are elliptic functions, possibly degenerate

Grounding Abstract Word Definitions In Prior Concrete Experience

Longman’s Dictionary of Contemporary English (LDOCE) and Cambridge International Dictionary of English (CIDE) have a defining vocabulary of 2000 words from which most but not all of the words are defined. We developed an algorithm, applicable to any dictionary, for recursively deleting words not used in any definition until the corpus is reduced to a subset – a grounding kernel – from which all the words of the complete dictionary are reachable by definition alone. We compared LDOCE’s and CIDE’s defining vocabulary (DV) and grounding kernel (GK) against the rest of its words, on (1) concreteness, (2) imagery and (3) age of acquisition based on the MRC psycholinguistic database [Wilson 1988]. Both GK and DV proved significantly higher on all three scales (p&lt;0.001) for all but 2 of the 12 comparisons (no difference in concreteness in LDOCE for either GK or DV). The difference was also consistently greater using our automatically computed GK than using the DV defined by the compilers of LDOCE and CIDE

Hierarchies in Dictionary De

A dictionary defines words in terms of other words. Definitions can tell you the meanings of words you don't know, but only if you know the meanings of the defining words. How many words do you need to know (and which ones) in order to be able to learn all the rest from definitions? We reduced dictionaries to their "grounding kernels" (GKs), about 10% of the dictionary, from which all the other words could be defined. The GK words turned out to have psycholinguistic correlates: they were learned at an earlier age and more concrete than the rest of the dictionary. But one can compress still more: the GK turns out to have internal structure, with a strongly connected "kernel core" (KC) and a surrounding layer, from which a hierarchy of definitional distances can be derived, all the way out to the periphery of the full dictionary. These definitional distances, too, are correlated with psycholinguistic variables (age of acquisition, concreteness, imageability, oral and written frequency) and hence perhaps with the ``mental lexicon" in each of our heads

LKB1 interacts with and phosphorylates PTEN: a functional link between two proteins involved in cancer predisposing syndromes

Germline mutations of the LKB1 (STK11) tumor suppressor gene lead to Peutz-Jeghers syndrome (PJS) and predisposition to cancer. LKB1 encodes a serine/threonine kinase generally inactivated in PJS patients. We identified the dual phosphatase and tumor suppressor protein PTEN as an LKB1-interacting protein. Several LKB1 point mutations associated with PJS disrupt the interaction with PTEN suggesting that the loss of this interaction might contribute to PJS. Although PTEN and LKB1 are predominantly cytoplasmic and nuclear, respectively, their interaction leads to a cytoplasmic relocalization of LKB1. In addition, we show that PTEN is a substrate of the kinase LKB1 in vitro. As PTEN is a dual phosphatase mutated in autosomal inherited disorders with phenotypes similar to those of PJS (Bannayan-Riley-Ruvalcaba syndrome and Cowden disease), our study suggests a functional link between the proteins involved in different hamartomatous polyposis syndromes and emphasizes the central role played by LKB1 as a tumor suppressor in the small intestin

Comparison of the dipeptidyl peptidase-4 gene methylation levels between severely obese subjects with and without the metabolic syndrome

Background : The dipeptidyl peptidase-4 (DPP4) enzyme is a novel adipokine potentially involved in the development of the metabolic syndrome (MetS). Previous observations demonstrated higher visceral adipose tissue (VAT) DPP4 gene expression in non-diabetic severely obese men with (MetS+) vs. without (MetS−) MetS. DPP4 mRNA abundance in VAT correlated also with CpG site methylation levels (%Meth) localized within and near its exon 2 (CpG94 to CpG102) in non-diabetic severely obese women, regardless of their MetS status. The actual study tested whether DPP4 %Meth levels in VAT are different between MetS− and MetS+ non-diabetic severely obese subjects, whether variable metabolic and plasma lipid profiles are observed between DPP4 %Meth quartiles, and whether correlation exists in DPP4 %Meth levels between VAT and white blood cells (WBCs). Methods : DNA was extracted from the VAT of 26 men (MetS−: n=12, MetS+: n=14) and 79 women (MetS−: n=60; MetS+: n=19), as well as from WBCs in a sub-sample of 17 women (MetS−: n=9; MetS+: n=8). The %Meth levels of CpG94 to CpG102 were assessed by pyrosequencing of sodium bisulfite-treated DNA. ANOVA analyses were used to compare the %Meth of CpGs between MetS− and MetS+ groups, and to compare the metabolic phenotype and plasma lipid levels between methylation quartiles. Pearson correlation coefficient analyses were computed to test the relationship between VAT and WBCs CpG94-102 %Meth levels. Results : No difference was observed in CpG94-102 %Meth levels between MetS− and MetS+ subjects in VAT (P=0.67), but individuals categorized into CpG94-102 %Meth quartiles had variable plasma total-cholesterol concentrations (P=0.04). The %Meth levels of four CpGs in VAT were significantly correlated with those observed in WBCs (r=0.55−0.59, P≤0.03). Conclusions : This study demonstrated that %Meth of CpGs localized within and near the exon 2 of the DPP4 gene in VAT are not associated with MetS status. The actual study also revealed an association between the %Meth of this locus with plasma total-cholesterol in severe obesity, which suggests a link between the DPP4 gene and plasma lipid levels