The temperature dependence of electronic eigenenergies in the adiabatic harmonic approximation

The renormalization of electronic eigenenergies due to electron-phonon interactions (temperature dependence and zero-point motion effect) is important in many materials. We address it in the adiabatic harmonic approximation, based on first principles (e.g. Density-Functional Theory), from different points of view: directly from atomic position fluctuations or, alternatively, from Janak's theorem generalized to the case where the Helmholtz free energy, including the vibrational entropy, is used. We prove their equivalence, based on the usual form of Janak's theorem and on the dynamical equation. We then also place the Allen-Heine-Cardona (AHC) theory of the renormalization in a first-principle context. The AHC theory relies on the rigid-ion approximation, and naturally leads to a self-energy (Fan) contribution and a Debye-Waller contribution. Such a splitting can also be done for the complete harmonic adiabatic expression, in which the rigid-ion approximation is not required. A numerical study within the Density-Functional Perturbation theory framework allows us to compare the AHC theory with frozen-phonon calculations, with or without the rigid-ion terms. For the two different numerical approaches without rigid-ion terms, the agreement is better than 7 $\mu$eV in the case of diamond, which represent an agreement to 5 significant digits. The magnitude of the non rigid-ion terms in this case is also presented, distinguishing specific phonon modes contributions to different electronic eigenenergies

Response-Locked Brain Dynamics of Word Production

International audienceThe cortical regions involved in the different stages of speech production are relatively well-established, but their spatio-temporal dynamics remain poorly understood. In particular, the available studies have characterized neural events with respect to the onset of the stimulus triggering a verbal response. The core aspect of language production, however, is not perception but action. In this context, the most relevant question may not be how long after a stimulus brain events happen, but rather how long before the production act do they occur. We investigated speech production-related brain activity time-locked to vocal onset, in addition to the common stimulus-locked approach. We report the detailed temporal interplay between medial and left frontal activities occurring shortly before vocal onset. We interpret those as reflections of, respectively, word selection and word production processes. This medial-lateral organization is in line with that described in non-linguistic action control, suggesting that similar processes are at play in word production and non-linguistic action production. This novel view of the brain dynamics underlying word production provides a useful background for future investigations of the spatio-temporal brain dynamics that lead to the production of verbal responses. Citation: Riès S, Janssen N, Burle B, Alario F-X (2013) Response-Locked Brain Dynamics of Word Production. PLoS ONE 8(3): e58197

General-Purpose Monitoring during Speech Production

WOS:000289063000012International audienceThe concept of "monitoring" refers to our ability to control our actions on-line. Monitoring involved in speech production is often described in psycholinguistic models as an inherent part of the language system. We probed the specificity of speech monitoring in two psycholinguistic experiments where electro-encephalographic activities were recorded. Our focus was on a component previously reported in nonlinguistic manual tasks and interpreted as a marker of monitoring processes. The error negativity (Ne, or error-related negativity), thought to originate in medial frontal areas, peaks shortly after erroneous responses. A component of seemingly comparable properties has been reported, after errors, in tasks requiring access to linguistic knowledge (e.g., speech production), compatible with a generic error-detection process. However, in contrast to its original name, advanced processing methods later revealed that this component is also present after correct responses in visuomotor tasks. Here, we reported the observation of the same negativity after correct responses across output modalities (manual and vocal responses). This indicates that, in language production too, the Ne reflects on-line response monitoring rather than error detection specifically. Furthermore, the temporal properties of the Ne suggest that this monitoring mechanism is engaged before any auditory feedback. The convergence of our findings with those obtained with nonlinguistic tasks suggests that at least part of the monitoring involved in speech production is subtended by a general-purpose mechanism

Determining Suitability of a Fly Ash for Silica Extraction and Zeolite Synthesis

Zeolitic material is obtained from fly ash both by direct conversion of the ash or from SiO2 extracts obtained from fly ash. This study focuses on determining the suitability of a fly ash for SiO2 extraction and for zeolite synthesis by direct conversion. The SiO2 extraction experiments from different fly ashes show that the main parameters governing the SiO2 extraction are: (a) a high bulk SiO2 content (\u3e 52%, for obtaining an extraction yield of 100 g SiO2 kg-1) in the starting fly ash, (b) a high proportion (\u3e 55%) of the bulk SiO2 present in the degradable glass matrix and the highly soluble opaline fraction, and (c) a high bulk SiO2/Al2O3 ratio (\u3e2.0) of the fly ash. The results from experiments of zeolite synthesis by direct conversion demonstrate that the most important criteria for the selection of a fly ash for this process are: (a) a high content of Al2O3 and SiO2(\u3e 65%) (b) a high glass content (\u3e 63%) and (c) relatively low SiO2/Al2O3 ratio (\u3c 2.0). Multivariate analysis confirms the importance of the above-mentioned variables and shows some additional variables that have influence on ash behaviour under alkaline conditions. It quantifies the use of those variables for determining the suitability of ashes for SiO2 extraction and zeolite synthesis and is able to distinguish between the two. © 2004 Society of Chemical Industry

Educação do campo: a luta dos movimentos sociais campesinos por uma Educação Escolar específica e diferenciada / Education in the countr yside : the stru ggle of rural social movements for a specific and differentiated education

Este artigo apresenta o diálogo entre duas pesquisas do Programa de Pós-Graduação em Educação da Universidade Federal de Pernambuco, que tratam da Educação do Campo. Para este trabalho tomamos como ponto de partida dois direcionamentos: a) a compreensão dos efeitos da colonialidade na constituição da realidade, especialmente da área rural; b) a importância da mobilização dos movimentos sociais campesinos na constituição dos mecanismos legais vigentes que delineiam a política específica e diferenciada para a educação escolar ofertada em áreas rurais. As discussões foram tecidas a partir da abordagem dos Estudos Pós- Coloniais Latino-Americanos (QUIJANO, 2005; MIGNOLO, 1996, 2008; WALSH, 2008; MALDONADO-TORRES, 2007). Concluímos que as lutas dos movimentos sociais campesinos denunciam os mecanismos utilizados para forjar o silenciamento e a subalternização dos povos campesinos. Nesse sentido, esses sujeitos epistêmicos propõem contar a história a partir do rural e compreender o rural enquanto lócus de enunciação, evidenciando práticas discursivas outras, logo, práticas pedagógicas outras, diferenciadas e específicas.

Universality and scaling study of the critical behavior of the two-dimensional Blume-Capel model in short-time dynamics

In this paper we study the short-time behavior of the Blume-Capel model at the tricritical point as well as along the second order critical line. Dynamic and static exponents are estimated by exploring scaling relations for the magnetization and its moments at early stage of the dynamic evolution. Our estimates for the dynamic exponents, at the tricritical point, are $z= 2.215(2)$ and $\theta= -0.53(2)$.Comment: 12 pages, 9 figure

Genetic analysis in a familial case with high bone mineral density suggests additive effects at two loci

Osteoporosis is the most common bone disease, characterized by a low bone mineral density (BMD) and increased risk of fracture. At the other end of the BMD spectrum, some individuals present strong, fracture-resistant, bones. Both osteoporosis and high BMD are heritable and their genetic architecture encompasses polygenic inheritance of common variants and some cases of monogenic highly penetrant variants in causal genes. We have investigated the genetics of high BMD in a family segregating this trait in an apparently Mendelian dominant pattern. We searched for rare causal variants by whole-exome sequencing in three affected and three nonaffected family members. Using this approach, we have identified 38 rare coding variants present in the proband and absent in the three individuals with normal BMD. Although we have found four variants shared by the three affected members of the family, we have not been able to relate any of these to the high-BMD phenotype. In contrast, we have identified missense variants in two genes, VAV3 and ADGRE5, each shared by two of out of three affected members, whose loss of function fits with the phenotype of the family. In particular, the proband, a woman displaying the highest BMD (sum Z-score = 7), carries both variants, whereas the other two affected members carry one each. VAV3 encodes a guanine-nucleotide-exchange factor with an important role in osteoclast activation and function. Although no previous cases of VAV3 mutations have been reported in humans, Vav3 knockout (KO) mice display dense bones, similarly to the high-BMD phenotype present in our family. The ADGRE5 gene encodes an adhesion G protein-coupled receptor expressed in osteoclasts whose KO mouse displays increased trabecular bone volume. Combined, these mouse and human data highlight VAV3 and ADGRE5 as novel putative high-BMD genes with additive effects, and potential therapeutic targets for osteoporosis. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research