3d numerical model of a confined fracture tests in concrete

The paper deals with the numerical simulation of a confined fracture test in concrete. The test is part of the experimental work carried out at ETSECCPB-UPC in order to elucidate the existence of a second mode of fracture under shear and high compression, and evaluate the associated fracture energy. The specimen is a short cylinder with also cylindrical coaxial notches similar the one proposed by Luong (1990), which is introduced in a largecapacity triaxial cell, protected with membranes and subject to different levels of confining pressure prior to vertical loading. In the experiments, the main crack follows the preestablished cylindrical notch path, which is in itself a significant achievement. The loaddisplacement curves for various confining pressures also seem to follow the expected trend according to the underlying conceptual model. The FE model developed includes zerothickness interface elements with fracture-based constitutive laws, which are pre-inserted along the cylindrical ligament and the potential radial crack plane. The results reproduce reasonably well the overall force-displacement curves of the test for various confinement levels, and make it possible to identify the fracture parameters including the fracture energies in modes I and IIa

Ordering in the dilute weakly-anisotropic antiferromagnet Mn(0.35)Zn(0.65)F2

The highly diluted antiferromagnet Mn(0.35)Zn(0.65)F2 has been investigated by neutron scattering in zero field. The Bragg peaks observed below the Neel temperature TN (approximately 10.9 K) indicate stable antiferromagnetic long-range ordering at low temperature. The critical behavior is governed by random-exchange Ising model critical exponents (nu approximately 0.69 and gamma approximately 1.31), as reported for Mn(x)Zn(1-x)F2 with higher x and for the isostructural compound Fe(x)Zn(1-x)F2. However, in addition to the Bragg peaks, unusual scattering behavior appears for |q|>0 below a glassy temperature Tg approximately 7.0 K. The glassy region T<Tg corresponds to that of noticeable frequency dependence in earlier zero-field ac susceptibility measurements on this sample. These results indicate that long-range order coexists with short-range nonequilibrium clusters in this highly diluted magnet.Comment: 7 pages, 5 figure

GOVERNANCE OF TECHNOLOGICAL INNOVATION IN THE TROPICAL FRUIT COMMODITY CHAINS IN LATIN AMERICA

N° ISBN - 978-2-7380-1284-5International audienceThe analyses mobilized costs conventional benefits for the evaluation ex ante of the feasibility of technical innovations in the agri-foodstuffs chains are criticized in their capacity to integrate the economic and environmental externalities that structure the development of the innovations. This communication proposes to undergo a methodology that puts in complementariness diagnoses, participating analyses multicriterion and investigations with actors of chains for the evaluation ex-ante of the feasibility of technical innovations different. The application is realised in different chains from processing of fruits in Latin America (Brazil, Costa Rica, Ecuador, Mexico). The results allow to characterize that the conditions of supplying in matera premium (fresh fruit) and the conditions of organization of the chains in the implementation of interactions between different actors; they are strategic elements of the feasibility. On the other hand they show the necessity to improve the methodologic picture proposed to activate “systems of chain innovations” that improve the processes of gobernancia of the technological directions in relation to their environmental impacts and social

Ductus venosus agenesis and fetal malformations: what can we expect? - a systematic review of the literature

Background: The ductus venosus agenesis (DVA) is a rare condition with a variable prognosis that relies partly on the presence of associated conditions. The purpose of our study was to analyze the literature regarding the postnatal outcome of fetuses with DVA associated with fetal malformations, in order to discuss the best management options for couples. Methods: We performed a systematic review of the literature of MEDLINE and SCOPUS electronic databases in a 25-year period from 1992 to September 2017. Results: We found 340 cases of DVA associated with fetal abnormalities. The most common chromosomal abnormalities were: monosomy X (12/48, 25%), trisomy 21 (11/48, 22.9%) and trisomy 18 (6/48, 12.5%). From the 340 cases with DVA, in 31 cases the umbilical venous shunt type was not reported. Of the fetuses, 60.8% (188/309) had an extrahepatic umbilical venous drainage while 39.2% (121/309) presented an intrahepatic connection. The DVA was associated in 71 cases (23.0%) with cardiac abnormalities, in 82 cases (26.5%) with extracardiac abnormalities and in 85 cases (27.5%) with both cardiac and extracardiac abnormalities. Conclusion: DVA associated with both cardiac and extracardiac malformations may confer a poorer fetal outcome, a clinically relevant fact that should clarify what can be expected from this entity and help prenatal counseling

Fingerprinting the magnetic behavior of antiferromagnetic nanostructures using remanent magnetization curves

Antiferromagnetic (AF) nanostructures from Co3O4, CoO and Cr2O3 were prepared by the nanocasting method and were characterized magnetometrically. The field and temperature dependent magnetization data suggests that the nanostructures consist of a core-shell structure. The core behaves as a regular antiferromagnet and the shell as a two-dimensional diluted antiferromagnet in a field (2d DAFF) as previously shown on Co3O4 nanowires [Benitez et al., Phys. Rev. Lett. 101, 097206 (2008)]. Here we present a more general picture on three different material systems, i.e. Co3O4, CoO and Cr2O3. In particular we consider the thermoremanent (TRM) and the isothermoremanent (IRM) magnetization curves as "fingerprints" in order to identify the irreversible magnetization contribution originating from the shells. The TRM/IRM fingerprints are compared to those of superparamagnetic systems, superspin glasses and 3d DAFFs. We demonstrate that TRM/IRM vs. H plots are generally useful fingerprints to identify irreversible magnetization contributions encountered in particular in nanomagnets.Comment: submitted to PR

Fine-scale genetic mapping of a hybrid sterility factor between Drosophila simulans and D. mauritiana: the varied and elusive functions of "speciation genes"

<p>Abstract</p> <p>Background</p> <p>Hybrid male sterility (HMS) is a usual outcome of hybridization between closely related animal species. It arises because interactions between alleles that are functional within one species may be disrupted in hybrids. The identification of genes leading to hybrid sterility is of great interest for understanding the evolutionary process of speciation. In the current work we used marked <it>P</it>-element insertions as dominant markers to efficiently locate one genetic factor causing a severe reduction in fertility in hybrid males of <it>Drosophila simulans </it>and <it>D. mauritiana</it>.</p> <p>Results</p> <p>Our mapping effort identified a region of 9 kb on chromosome 3, containing three complete and one partial coding sequences. Within this region, two annotated genes are suggested as candidates for the HMS factor, based on the comparative molecular characterization and public-source information. Gene <it>Taf1 </it>is partially contained in the region, but yet shows high polymorphism with four fixed non-synonymous substitutions between the two species. Its molecular functions involve sequence-specific DNA binding and transcription factor activity. Gene <it>agt </it>is a small, intronless gene, whose molecular function is annotated as methylated-DNA-protein-cysteine S-methyltransferase activity. High polymorphism and one fixed non-synonymous substitution suggest this is a fast evolving gene. The gene trees of both genes perfectly separate <it>D. simulans </it>and <it>D. mauritiana </it>into monophyletic groups. Analysis of gene expression using microarray revealed trends that were similar to those previously found in comparisons between whole-genome hybrids and parental species.</p> <p>Conclusions</p> <p>The identification following confirmation of the HMS candidate gene will add another case study leading to understanding the evolutionary process of hybrid incompatibility.</p

Dynamics of a thin spherically symmetric radiating shells and collapsed astronomical objects

In ref. [1] it studied the dynamics of a thin dust radiating shell, endowed with spherical symmetry moving in the gravitational field of a central body. We used the General Relativity Theory; in our formalism the shell is a three-dimensional (two space like dimensions, one time like dimension) singular hypersurface [1, 2], with a Schwarzschild metric inside and Vaidya [3] metric outside. We used the model to study the detection of relativistic effects in novae and supernovae, and reach to the conclusion that, using these astronomical objects General Relativity effect will be very difficult to detect. In ref. [3] Hamity and Spinosa considering also a Vaidya metric in the interior of the shell, used this new model to study planetary nebula. In the present work we have used this last model to study different astronomical object: X-ray bursters, and Gamma-ray bursters.Asociación Argentina de Astronomí

Low-Energy Fragmentation Dynamics at Copahue Volcano (Argentina) as Revealed by an Infrasonic Array and Ash Characteristics

Ash-rich eruptions represent a serious risk to the population living nearby as well as at thousands of kilometers from a volcano. Volcanic ash is the result of extensive magma fragmentation during an eruption, and it depends upon a combination of magma properties such as rheology, vesicularity and permeability, gas overpressure and the possible involvement of external fluids during magma ascent. The explosive process generates infrasonic waves which are directly linked to the outflow of the gas-particle mixture in the atmosphere. The higher the overpressure in the magma, the higher should be the exit velocity of the ejected material and the acoustic pressure related to this process. During violent eruptions, fragmentation becomes more efficient and is responsible for the extensive production of ash which is dispersed in the atmosphere. We show that the phase of intense ash emission that occurred during March 2016 at Copahue volcano (Argentina) generated a very low (0.1 Pa) infrasonic amplitude at 13 km, raising a number of questions concerning the links among acoustic pressure, gas overpressure and efficiency of magma fragmentation. Infrasound and direct observations of the eruptive plume indicate that the large quantity of ash erupted at Copahue was ejected with a low exit velocity. Thus, it was associated with eruptive dynamics driven by a low magma overpressure. This is more evident when infrasonic activity at Copahue is compared to the moderate explosive activity of Villarrica (Chile), recorded by the same array, at a distance of 193 km. Our data suggest a process of rigid fragmentation under a low magma overpressure which was nearly completely dissipated during the passage of the erupting mixture through the granular, ash-bearing crater infilling. We conclude that ash released into the atmosphere during low-energy fragmentation dynamics can be difficult to monitor, with direct consequences for the assessment of the related hazard and management of eruptive crises.Fil: Hantusch, Marcia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Lacanna, Giorgio. Università degli Studi di Firenze; ItaliaFil: Ripepe, Maurizio. Università degli Studi di Firenze; ItaliaFil: Montenegro, Verónica Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Valderrama, Oscar. Servicio Nacional de Geologia y Mineria (SERNAGEOMIN); ChileFil: Farias, Camila Belen. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; ArgentinaFil: Caselli, Alberto Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Gabellini, Pietro. Università degli Studi di Firenze; ItaliaFil: Cioni, Raffaello. Università degli Studi di Firenze; Itali

Gestión de adaptación al cambio climático en la actividad lechera: un aporte reflexivo: Gestão de adaptação às mudanças climáticas na atividade leiteira: uma contribuição reflexiva

Los sistemas de producción lechera se enfrentan al desafío de producir combinando la rentabilidad con la protección al medio ambiente, la salud humana y el bienestar animal; y además, satisfacer las demandas de los transformadores y de los consumidores. En estas condiciones, los productores de leche han venido tomando una serie de medidas para adaptarse al cambio climático y producir en armonía con el medio ambiente. Este asunto se convirtió en prioridad nacional y con el apoyo de varias instituciones y organizaciones, públicas y privadas, ha ocurrido que en Costa Rica exista una Estrategia Nacional de Ganadería Baja en Carbono (EGBC), un Programa de Investigación y Transferencia de Tecnología Agropecuaria de&nbsp;Ganadería (PITTA-Ganadería) y un NAMA-Ganadería (Acciones de Mitigación Nacionalmente Apropiadas, NAMA&nbsp;por sus siglas en inglés). Todos estos instrumentos son soluciones viables con las situaciones productivas y el bienestar social de una población importante de pequeños productores que dependen de esta actividad