The History of Galaxy Formation in Groups: An Observational Perspective

We present a pedagogical review on the formation and evolution of galaxies in groups, utilizing observational information from the Local Group to galaxies at z~6. The majority of galaxies in the nearby universe are found in groups, and galaxies at all redshifts up to z~6 tend to cluster on the scale of nearby groups (~1 Mpc). This suggests that the group environment may play a role in the formation of most galaxies. The Local Group, and other nearby groups, display a diversity in star formation and morphological properties that puts limits on how, and when, galaxies in groups formed. Effects that depend on an intragroup medium, such as ram-pressure and strangulation, are likely not major mechanisms driving group galaxy evolution. Simple dynamical friction arguments however show that galaxy mergers should be common, and a dominant process for driving evolution. While mergers between L_* galaxies are observed to be rare at z < 1, they are much more common at earlier times. This is due to the increased density of the universe, and to the fact that high mass galaxies are highly clustered on the scale of groups. We furthermore discus why the local number density environment of galaxies strongly correlates with galaxy properties, and why the group environment may be the preferred method for establishing the relationship between properties of galaxies and their local density.Comment: Invited review, 16 pages, to be published in ESO Astrophysics Symposia: "Groups of Galaxies in the Nearby Universe", eds. I. Saviane, V. Ivanov, J. Borissov

Network structure of vertebrate scavenger assemblages at the global scale: drivers and ecosystem functioning implications

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Quantitative analysis of self-association and mobility of annexin a4 at the plasma membrane

Item does not contain fulltextAnnexins, found in most eukaryotic species, are cytosolic proteins that are able to bind negatively-charged phospholipids in a calcium-dependent manner. Annexin A4 (AnxA4) has been implicated in diverse cellular processes, including the regulation of exocytosis and ion-transport; however, its precise mechanistic role is not fully understood. AnxA4 has been shown to aggregate on lipid layers upon Ca(2+) binding in vitro, a characteristic that may be critical for its function. We have utilized advanced fluorescence microscopy to discern details on the mobility and self-assembly of AnxA4 after Ca(2+) influx at the plasma membrane in living cells. Total internal reflection microscopy in combination with Forster resonance energy transfer reveals that there is a delay between initial plasma membrane binding and the beginning of self-assembly and this process continues after the cytoplasmic pool has completely relocated. Number-and-brightness analysis suggests that the predominant membrane bound mobile form of the protein is trimeric. There also exists a pool of AnxA4 that forms highly immobile aggregates at the membrane. Fluorescence recovery after photobleaching suggests that the relative proportion of these two forms varies and is correlated with membrane morphology

Selected research opportunities in soil physics Oportunidades selecionadas de pesquisa em física do solo

Selected research opportunities are discussed in order to guide soil science research, with emphasis on soil physics, with the aim of improving agricultural productivity and environmental quality.<br>Oportunidades selecionadas de pesquisa são discutidas para orientar a pesquisa em ciência do solo,com ênfase na física do solo, com o objetivo de melhorar a produtividade agrícola e a qualidade do ambiente