Relationships between population spatial occupation and population dynamics

Population dynamics is commonly described non-spatially using parameters of population demography and vital traits. Population spatial organisation is therefore considered implicit and its importance in the population dynamics ignored. The present study evidences on a variety of stocks correlation between population spatial distribution indices, population abundance, recruitment and mortality. Series of research fisheries monitoring surveys were considered for a range of different stocks (cod, herring, anchovy, hake, mullet) in different regions of the North East Atlantic and Mediterranean (North Sea, Barents Sea, Baltic Sea, Bay of Biscay, Tyrrhenian Sea, Ionian Sea and Aegean Sea). For each population, each age and each year, 9 spatial indices were computed that characterised the spatial distribution in their centre of gravity, inertia, anisotropy, extension areas, number of patches and microscale structure. For each population and age, spatial indices were linearly regressed on the abundance, on the following recruitment, and on the mortality residuals (as a constant mortality has been fitted on cohort curves). A metaanalysis table was constructed that showed the number of times that correlations were significant. The result is that spatial indices provide additional indicators for assessing population status and could be helpful in the context of stock decline and habitat loss

The Virgo data acquisition system

International audienc

The gravitational wave detector VIRGO

International audienc

Influence of Defects on the Stability and Hydrogen‐Sorption Behavior of Mg‐Based Hydrides

This review deals with the destabilization methods for improvement of storage properties of metal hydrides. Both theoretical and experimental approaches were used to point out the influence of various types of defects on structure and stability of hydrides. As a case study, Mg, and Ni based hydrides has been investigated. Theoretical studies, mainly carried out within various implementations of DFT, are a powerful tool to study mostly MgH 2 based materials. By providing an insight on metal-hydrogen bonding that governs both thermodynamics and hydrogen kinetics, they allow us to describe phenomena to which experimental methods have a limited access or do not have it at all: to follow the hydrogen sorption reaction on a specific metal surface and hydrogen induced phase transformations, to describe structure of phase boundaries or to explain the impact of defects or various additives on MgH 2 stability and hydrogen sorption kinetics. In several cases theoretical calculations reveal themselves as being able to predict new properties of materials, including the ways to modify Mg or MgH 2 that would lead to better characteristics in terms of hydrogen storage. The influence of ion irradiation and mechanical milling with and without additives has been discussed. Ion irradiation is the way to introduce a well-defined concentration of defects (Frankel pairs) at the surface and sub-surface layers of a material. Defects at the surface play the main role in sorption reaction since they enhance the dissociation of hydrogen. On the other hand, ball-milling introduce defects through the entire sample volume, refine the structure and thus decrease the path for hydrogen diffusion. Two Severe Plastic Deformation techniques were used to better understand the hydrogenation/dehydrogenation kinetics of Mg- and Mg 2 Ni-based alloys: Equal-Angular-Channel-Pressing and Fast-Forging. Successive ECAP passes leads to refinement of the microstructure of AZ31 ingots and to instalment therein of high densities of defects. Depending on mode, number and temperature of ECAP passes, the H-sorption kinetics have been improved satisfactorily without any additive for mass H-storage applications considering the relative speed of the shaping procedure. A qualitative understanding of the kinetic advanced principles has been built. Fast-Forging was used for a “quasi-instantaneous” synthesis of Mg/Mg 2 Ni-based composites. Hydrogenation of the as-received almost bi-phased materials remains rather slow as generally observed elsewhere, whatever are multiple and different techniques used to deliver the composite alloys. However, our preliminary results suggest that a synergic hydrogenation / dehydrogenation process should assist hydrogen transfers from Mg/Mg 2 Ni on one side to MgH 2 /Mg 2 NiH 4 on the other side via the rather stable a-Mg 2 NiH 0.3 , acting as in-situ catalyser. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimThis is the peer reviewed version of the following article: Grbović Novaković, J., Novaković, N., Kurko, S., Milošević Govedarović, S., Pantić, T., Paskaš Mamula, B., ... & Skryabina, N. (2019). Influence of Defects on the Stability and Hydrogen‐Sorption Behavior of Mg‐Based Hydrides. ChemPhysChem., which has been published in final form at [http://dx.doi.org/10.1002/cphc.201801125]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions

Additive manufacturing of an Fe–Cr–Co permanent magnet alloy with a novel approach of in-situ alloying

Additive manufacturing has become increasingly important in the production of magnetic materials in recent years due to the great demands for miniaturization and complex-shaped magnet parts. In this study, the laser beam-powder bed fusion process (LPBF) has been used to develop an in-situ alloying process for the additive manufacturing of a permanent magnet material of the Fe–Cr–Co system. This novel method allows for the production of complex alloys with a chemical composition suited to each specific case of application, achieved by using elemental powders or simpler commercial alloy powders as base materials. The core focus of this study has been on the development and characterization of the printing process using a Fe-30.5Cr-15Co-1.5Mo alloy. The in-situ alloying process has been developed by performing melt pool tests on the two main component powders Fe and Cr and by conducting parameter studies using two different powder mixtures with different sphericity of their components. The influence of different printing parameters and post-printing treatments on the chemical homogeneity and magnetic properties has been studied for selected samples. In addition, magnetic measurements at different temperatures have been performed to investigate the temperature stability of the magnetic properties of the 3D printed material. Impact Statement As by today, the current amount of research done on the additive manufacturing of magnetic materials is rather low. Most of research is focused on rare- earth containing magnetic materials. In this work therefore, we are taking another direction in which we will show that LPBF combined with in- situ alloying is an ideal method for the production of a great variety of different rare- earth free magnetic materials. The positive results of our work can both have an influence on the the scientific community, as further research in the field on different promising rare- earth free magnetic materials is to be expected. Furthermore, a positiv economic impact may occur since the production of rare- earth free magnetic materials is dependent on different raw material sources which are both more cost- effectiv and less critical in terms of their supply chain. This effect is also accompanied by a positive environmental impact, since the mining of rare- earth metals usually comes with considerable environmental pollution

La radiothérapie induit-elle une agressivité accrue des cellules tumorales du glioblastome ?

International audienceGlioblastoma multiform is the most common and aggressive brain tumor with a worse prognostic. Ionizing radiation is a cornerstone in the treatment of glioblastome with chemo-radiation association being the actual standard. As a paradoxal effect, it has been suggested that radiotherapy could have a deleterious effect on local recurrence of cancer. In vivo studies have studied the effect of radiotherapy on biological modification and pathogenous effect of cancer cells. It seems that ionizing radiations with photon could activate oncogenic pathways in glioblastoma cell lines. We realized a review of the literature of photon-enhanced effect on invasion and migration of glioblastoma cells by radiotherapy