Drift of Colomesus asellus (Teleostei : Tetraodontidae) larvae in the Amazon river

#Colomesus asellus est le seul #Tetraodontidae du bassin amazonien, ce qui rend possible l'identification des larves et l'étude de leur transport par le fleuve. Durant un an, nous avons échantillonné le cours de l'Amazone et le long des berges. Nous observons une dérive durant la crue, lorsque les larves sont transportées passivement vers les lacs de la plaine inondée. Le long des berges, la densité des larves est significativement plus importante que dans le milieu du fleuve, mais elle n'est pas homogène, ce qui laisse supposer que la ponte se réalise dans des sites spécifiques, près de la berge. La stratégie de reproduction de #C. asellus diffère de celle des autres poissons d'eau douce de colonisation secondaire (#Scianenidae, #Engraulidae$ et autres) et des autres tétraodontes d'eau douce, mais elle se rapproche de la stratégie des Characiformes et Siluriformes ainsi que de celle des tétraodontes marins. (Résumé d'auteur

Cytocompatibility, biofilm assembly and corrosion behavior of Mg-HAP composites processed by extrusion

This work has been supported by the Regional Government of Madrid through the S2013/MIT-2862-MULTIMAT-CHALLENGE Program. R del Campo thanks to the Universidad Carlos III de Madrid for the support

What do we learn from Resonance Production in Heavy Ion Collisions?

Resonances with their short life time and strong coupling to the dense and hot medium are suggested as a signature of the early stage of the fireball created in a heavy ion collision \cite{rap00,lut01,lut02}. The comparison of resonances with different lifetimes and quark contents may give information about time evolution and density and temperature of during the expanding of fireball medium. Resonances in elementary reactions have been measured since 1960. Resonance production in elementary collisions compared with heavy ion collisions where we expect to create a hot and dense medium may show the direct of influence of the medium on the resonances. This paper shows a selection of the recent resonance measurements from SPS and RHIC heavy ion colliders.Comment: 10 pages, 8 figures, HotQuarks 2004 conference proceeding

Resonance production in heavy ion collisions

Recent results of resonance production from RHIC at $\sqrt{s_{\rm NN}} =$ 200 GeV and SPS at $\sqrt{s_{\rm NN}} =$ 17 GeV are presented and discussed in terms of the evolution and freeze-out conditions of a hot and dense fireball medium. Yields and spectra are compared with thermal model predictions at chemical freeze-out. Deviations in the low transverse momentum region of the resonance spectrum of the hadronic decay channel, suggest a strongly interaction hadronic phase between chemical and kinetic freeze-out. Microscopic models including resonance rescattering and regeneration are able to describe the trend of the data. The magnitude of the regeneration cross sections for different inverse decay channels are discussed. Model calculations which include elastic hadronic interactions between chemical freeze-out and thermal freeze-out based on the K(892)/K and $\Lambda$(1520)/$\Lambda$ ratios suggest a time between two freeze-outs surfaces of $\Delta \tau>$ 4 fm/c. The difference in momentum distributions and yields for the $\phi$(1020) resonance reconstructed from the leptonic and hadronic decay channels at SPS energy are discussed taking into account the impact of a hadronic phase and possible medium modifications.Comment: 8 pages, 4 figures, conference proceedings (SQM2004

Occurrence of polycyclic aromatic hydrocarbons, microplastics and biofilms in Alqueva surface water at touristic spots

Freshwater pollution is a huge concern. A study aiming to evaluate physico chemical characteristics, microbiota, occurrence of two groups of persistent environmental pollutants with similar chemical properties polycyclic aromatic hydrocarbons PAHs and microplastics MPs in Alqueva s surface water was performed during 2021. Water samples were collected at three spots related to touristic activities two beaches and one marina during the Winter, Spring, Summer and Autumn seasons. In addition, the presence of biofilms on plastic and natural materials stone, wood vegetal materials were assessed and compared. Water quality based on physicochemical parameters was acceptable with a low eutrophication level. PAHs concentration levels were lower than the standard limits established for surface waters by international organizations. However, carcinogenic compounds were detected in two sampling locations, which can pose a problem for aquatic ecosystems. PAHs profiles showed significant differences when comparing the dry seasons with the rainy seasons, with a higher number of different compounds detected in Spring. Low molecular weigh compounds, usually associated with the atmospheric deposition and petroleum contamination, were more prevalent. MPs were detected in all samples except one during the Winter season. The polymers detected were poly methyl 2 methylpropenoate , polystyrene, polyethylene terephthalate, polyamide, polypropylene, styrene butadiene, polyvinyl chloride and low high density polyethylene with the last being the most frequent. Biofilms were more often detected on plastics than on natural materials. In addition, biofilms detected on plastics were more complex with higher microbial diversity e.g., bacteria, fungi yeast and phytoplancton organisms and richer in extrapolymeric material. Based on morphological analysis a good agreement between microbiota and microorganism present in the biofilms was found. Among microbiota were identified microorganisms previously linked to plastic and PAHs detoxification suggesting the need for further studies to evaluate the viability of using biofilms as part of a green bioremediation strategy to mitigate water pollutio

Crescimento inicial de espécies florestais em solo sob diferentes preparos.

Pesquisas sobre práticas de manejo do solo, como forma de gerar informações sobre seu uso correto têm sido um desafio para os estudiosos neste assunto. O objetivo deste trabalho foi avaliar o crescimento inicial de espécies florestais em função de sistemas de preparo do solo