Fresh concrete pumping arrest investigation for thixotropy by a CFD modelling apporach

Concrete pumping operations determine construction speed, finishing quality, durability and even structural integrity. When pumping operations cannot be continued, most problems occur due to complex time-dependent transformations. This causes significant industrial costs (e.g. material and delay). Since time-dependent aspects are currently not fully understood and cannot be predicted, a way to quantify time-dependent aspects is needed. Therefore, we make an attempt by numerical simulation by comparing thixotropic cases with different pumping arresting times. After an introduction to fresh concrete rheology and numerical modelling, ten representative thixotropy cases are analysed. Despite some unresolved numerical instabilities, the numerical framework allows to estimate pumping pressure peaks after resting time. The results evaluate a thixotropy model, which is generally applicable for less thixotropic SCC’s. It is clear that flow re-initiation after rest in concrete pumping is poorly understood. Numerical simulation could be one approach for further analysis and is potentially important for practice. Future work such as simulation of concrete mixers, pressure increase after pumping arrest, formwork pressure decay and leakage are therefore recommended

SPIRE imaging of M 82: Cool dust in the wind and tidal streams

M 82 is a unique representative of a whole class of galaxies, starbursts with superwinds, in the Very Nearby Galaxy Survey with Herschel. In addition, its interaction with the M 81 group has stripped a significant portion of its interstellar medium from its disk. SPIRE maps now afford better characterization of the far-infrared emission from cool dust outside the disk, and sketch a far more complete picture of its mass distribution and energetics than previously possible. They show emission coincident in projection with the starburst wind and in a large halo, much more extended than the PAH band emission seen with Spitzer. Some complex substructures coincide with the brightest PAH filaments, and others with tidal streams seen in atomic hydrogen. We subtract the far-infrared emission of the starburst and underlying disk from the maps, and derive spatially-resolved far-infrared colors for the wind and halo. We interpret the results in terms of dust mass, dust temperature, and global physical conditions. In particular, we examine variations in the dust physical properties as a function of distance from the center and the wind polar axis, and conclude that more than two thirds of the extraplanar dust has been removed by tidal interaction, and not entrained by the starburst wind

Structural build-up of cementitious paste under external magnetic fields

Engineering application processes of fresh concrete include transporting, pumping, formwork casting, etc. Each process is a significant factor influencing properties of fresh and hardened concrete. However, many contradicting requirements of fresh concrete performances (such as structuration rate) exist in these operation processes. Therefore, advanced techniques need to be proposed to satisfy future challenges. Actively controlling the stiffness by applying external magnetic fields would be a potential solution for the contradicting requirements, and could make the pumping and casting processes smarter and more reliable. In the present paper, the effects of magnetic field strength and magnetizing time on structural build-up of cementitious paste are discussed. The results show that higher magnetic field strengths result in higher percolation time and lower phase angle at equilibrium state. However, the application of external magnetic fields with low flux density has little effects on the viscoelastic behaviour of cementitious paste. Under high magnetic field strengths, the viscousliquid behaviour dominates the elastic-solid behaviour at early stage, while the solid-like behaviour becomes more dominant with magnetizing time

L'influence du climat familial sur l'investissement scolaire de collégiens de troisième

RESUME En s'appuyant sur les résultats d'études antérieures, nous mettons ici à l'épreuve l'influence des modes de communication et de cohésion entre les membres de la famille sur l'investissement scolaire des collégiens de 3ème générale. Concernant son travail scolaire, le jeune peut être en attente de soutien et d'encouragement de la part de ses parents. Le manque d'implication parentale à l'école contribue dès lors à un rapport à l'école plus problématique. Par ailleurs, des travaux récents soulignent combien les relations harmonieuses entre parents et adolescents ainsi qu'une bonne communication favorisent chez l'adolescent un meilleur investissement scolaire. On constate également que dans ces cas les adolescents vont rechercher le plus souvent des conseils auprès des parents quant à leur devenir scolaire et professionnel. Inversement, il n'est pas rare de trouver chez ceux dont les relations et la communication sont moins harmonieuses, des signes de démobilisation voire des attitudes de décrochage scolaire. Pour investiguer ces dimensions, nous avons soumit à 125 collégiens, garçons et filles, deux questionnaires : l'un portant sur le Climat familial de Cloutier, Champoux et Jacques (1994) et l'autre, sur le vécu et l'investissement scolaire du jeune issu de l'enquête de Prêteur, Féchant et Constans (2003). Les principaux résultats font ressortir quelques liaisons entre le climat familial et certains indicateurs du vécu et de l'investissement scolaire à l'adolescence. Les adolescents interrogés se sentent plutôt bien en famille. Bien qu'ils soient 70% à accepter l'école et son organisation, pour certains d'entre eux, ce sont surtout l'incompréhension de la part des professeurs, la difficulté des apprentissages et l'organisation des cours (emploi du temps et de cours peu intéressants), qui ressortent comme éléments explicatifs d'un vécu scolaire peu enrichissant et d'un faible investissement à l'école. Par ailleurs, le soutien parental apparaît déterminant pour faciliter le rapport à l'école à l'adolescence

DETECTION AND CHARACTERIZATION OF CIRCULATING ENDOTHELIAL CELLS IN MULTIPLE MYELOMA VERSUS MONOCLONAL GAMMAPATHY OF INDETERMINATED SIGNIFIANCE

Oral Communication presented at the ";Forum des Jeunes Chercheurs";, Brest (France) 2011

Acid/base-triggered switching of circularly polarized luminescence and electronic circular dichroism in organic and organometallic helicenes.

Electronic circular dichroism and circularly polarized luminescence acid/base switching activity has been demonstrated in helicene-bipyridine proligand 1 a and in its “rollover” cycloplatinated derivative 2 a. Whereas proligand 1 a displays a strong bathochromic shift (>160 nm) of the nonpolarized and circularly polarized luminescence upon protonation, complex 2 a displays slightly stronger emission. This strikingly different behavior between singlet emission in the organic helicene and triplet emission in the organometallic derivative has been rationalized by using quantum-chemical calculations. The very large bathochromic shift of the emission observed upon protonation of azahelicene-bipyridine 1 a has been attributed to the decrease in aromaticity (promoting a charge-transfer-type transition rather than a π–π* transition) as well as an increase in the HOMO–LUMO character of the transition and stabilization of the LUMO level upon protonation

Self-esteem in the Vietnamese adolescent: cross-cultural construction and validation of a tool

International audienceThe purpose of the present study was to develop a measure of self-esteem for adolescents. This research is now being carried out in the framework of a sound cooperation project between the psychology faculties of the Hanoi University of Social Sciences and Humanities (Vietnam), the Hanoi Institute of Psychology (Vietnam), and the Universities of Toulouse II and Nîmes (France). It respects the specific cultural aspects and has now set as its priority goal the development of measurement tools firmly anchored in the particularities of Vietnamese culture, while benefiting from the advances made in the west in this area. The creation and validation of the Vietnamese Self-Esteem Scale (EVES – Echelle Vietnamienne d'Estime de Soi) is one of the fruits of this cooperation. This study proceeded in two-step method : A cross-cultural adaptation of ETES (French scale) and thus created a new scale: EVES (Vietnamese Self-Esteem Scale) A study to validate this new instrument by an analysis of the factorial structure of the scale and of its internal consistency on an initial population of 264 adolescents, and a test-retest on 161 adolescents. Scale : The Toulouse Self-Esteem Scale (ETES-Oubrayrie et al., 1994), is a self-report measure for older children and adolescents. ETES consists of 60 items, each of which is rated on a 5-point Lickert-type scale. Cross-cultural adaptation : The cross-cultural adaptation includes a literal translation in the Vietnamese language as well as a cultural adaptation to the Vietnamese context. 4 phases : translation by qualified bilingual translators, backward translation, expert committee (child psychiatrist, psychologists and educationalist), testing. Sample : 264 adolescents (mean age = 16.57). The target population was aged from 14 to 19 years, was at high school and lived in the Ha Tay district of Hanoi city. Of the 264 adolescents, 77 were boys. Cross-cultural adaptation and construction of the Vietnamese Self-Esteem Scale (EVES) The cross-cultural adaptation includes a literal translation in the Vietnamese language as well as a cultural adaptation to the Vietnamese context. Conclusion : the Vietnamese Self-Esteem Scale (EVES) is short, simple, and easy to understand for the adolescent study group and is suitable for longitudinal use in adolescent clinical and developmental evaluation or in primary health care programs. Is a instrument to offer to the Vietnamese researcher and the Vietnamese clinician the twofold advantages of being both anchored in Vietnamese culture and of being a facilitator of international scientific exchanges. Its psychometric qualities make it a useful instrument because it evaluates a very important core aspect of the dynamics of the Vietnamese self : the three dimensions (family self, physical self, scholastic self) are indeed acknowledged as being highly important and of very great significance concerning adolescence. This Vietnamese instrument incorporates a richness of perspectives capable of giving an impetus to new studies and investigations that will provide an ever-fertile ground for scientific research

Bounds and Inequalities Relating h-Index, g-Index, e-Index and Generalized Impact Factor

Finding relationships among different indices such as h-index, g-index, e-index, and generalized impact factor is a challenging task. In this paper, we describe some bounds and inequalities relating h-index, g-index, e-index, and generalized impact factor. We derive the bounds and inequalities relating these indexing parameters from their basic definitions and without assuming any continuous model to be followed by any of them.Comment: 17 pages, 6 figures, 5 table

Frequency and Diversity of Nitrate Reductase Genes among Nitrate-Dissimilating Pseudomonas in the Rhizosphere of Perennial Grasses Grown in Field Conditions

A total of 1246 Pseudomonas strains were isolated from the rhizosphere of two perennial grasses (Lolium perenne and Molinia coerulea) with different nitrogen requirements. The plants were grown in their native soil under ambient and elevated atmospheric CO2 content (pCO2) at the Swiss FACE (Free Air CO2 Enrichment) facility. Root-, rhizosphere-, and non-rhizospheric soil-associated strains were characterized in terms of their ability to reduce nitrate during an in vitro assay and with respect to the genes encoding the membrane-bound (named NAR) and periplasmic (NAP) nitrate reductases so far described in the genus Pseudomonas. The diversity of corresponding genes was assessed by PCR-RFLP on narG and napA genes, which encode the catalytic subunit of nitrate reductases. The frequency of nitrate-dissimilating strains decreased with root proximity for both plants and was enhanced under elevated pCO2 in the rhizosphere of L. perenne. NAR (54% of strains) as well as NAP (49%) forms were present in nitrate-reducing strains, 15.5% of the 439 strains tested harbouring both genes. The relative proportions of narG and napA detected in Pseudomonas strains were different according to root proximity and for both pCO2 treatments: the NAR form was more abundant close to the root surface and for plants grown under elevated pCO2. Putative denitrifiers harbored mainly the membrane-bound (NAR) form of nitrate reductase. Finally, both narG and napA sequences displayed a high level of diversity. Anyway, this diversity was correlated neither with the root proximity nor with the pCO2 treatmen