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Parada A.,Bernardo OHiggins University | Pardinas U.F.J.,Centro Nacional Patagonico | Salazar-Bravo J.,Texas Tech University | D'Elia G.,Austral University of Chile | Palma R.E.,Bernardo OHiggins University
Molecular Phylogenetics and Evolution | Year: 2013

With about 400 living species and 82 genera, rodents of the subfamily Sigmodontinae comprise one of the most diverse and more broadly distributed Neotropical mammalian clades. There has been much debate on the origin of the lineage or the lineages of sigmodontines that entered South America, the timing of entrance and different aspects of further diversification within South America. The ages of divergence of the main lineages and the crown age of the subfamily were estimated by using sequences of the interphotoreceptor retinoid binding protein and cytochrome b genes for a dense sigmodontine and muroid sampling. Bayesian inference using three fossil calibration points and a relaxed molecular clock estimated a middle Miocene origin for Sigmodontinae (∼12. Ma), with most tribes diversifying throughout the Late Miocene (6.9-9.4. Ma). These estimates together results of analyses of ancestral area reconstructions suggest a distribution for the most recent common ancestor of Sigmodontinae in Central-South America and a South American distribution for the most recent common ancestor of Oryzomyalia. © 2012 Elsevier Inc. Source


Von Dassow P.,Bernardo OHiggins University | Montresor M.,Stazione Zoologica Anton Dohrn
Journal of Plankton Research | Year: 2011

Life cycles of phytoplankton species have been selected over a long evolutionary history and represent a key element for our understanding of their ecology and natural history and for improving our comprehension of ocean functioning. A species can alternate in its life cycle between four distinct major phases: growth, sex, quiescence and cell death. This implies that the population of a phytoplankton species found in any particular water sample will contain cells that undergo different fates, have strong differentiation in physiology and have different functional roles even if they are genetically identical. The factors regulating transitions among the different phases are still largely unknown but have direct impacts on the ecological distribution of species and on their biogeochemical function. Focused research efforts in recent years have begun to reveal emerging patterns in the variability of phytoplankton life cycle traits. This research has relied both on careful observations in culture and at sea and on making use of new genomics- and transcriptomics-based tools. The study of phytoplankton in the context of their life cycle characteristics opens up new opportunities to address fundamental questions about the physiology and cell biology of these important organisms and creates a new evolutionary and ecological framework for defining phytoplankton functional groups. © The Author 2010. Published by Oxford University Press. All rights reserved. Source


Mackenzie R.,CSIC - Institute of Marine Sciences | Pedros-Alio C.,CSIC - Institute of Marine Sciences | Diez B.,Bernardo OHiggins University
Extremophiles | Year: 2013

Seasonal shifts in bacterial diversity of microbial mats were analyzed in three hot springs (39-68 °C) of Patagonia, using culture-independent methods. Three major bacterial groups were detected in all springs: Phyla Cyanobacteria and Bacteroidetes, and Order Thermales. Proteobacteria, Acidobacteria and Green Non-Sulfur Bacteria were also detected in small amounts and only in some samples. Thermophilic filamentous heterocyst-containing Mastigocladus were dominant Cyanobacteria in Porcelana Hot Spring and Geyser, and Calothrix in Cahuelmó, followed by the filamentous non-heterocyst Leptolyngbya and Oscillatoria. Bacteroidetes were detected in a wide temperature range and their relative abundance increased with decreasing temperature in almost all samples. Two Meiothermus populations with different temperature optima were found. Overall, fingerprinting analysis with universal bacterial primers showed high similarities within each hot spring despite differences in temperature. On the other hand, Cahuelmó Hot Spring showed a lower resemblance among samples. Porcelana Hot Spring and Porcelana Geyser were rather similar to each other, possibly due to a common geological substrate given their geographic proximity. This was even more evident with specific cyanobacterial primers. The different geological substrate and the seawater influence in Cahuelmó might have caused the differences in the microbial community structure with the other two hot springs. © 2012 Springer Japan. Source


Birbaumer N.,University of Tubingen | Ruiz S.,University of Tubingen | Ruiz S.,Bernardo OHiggins University | Sitaram R.,University of Tubingen | And 2 more authors.
Trends in Cognitive Sciences | Year: 2013

Self-regulation and voluntary control of circumscribed brain regions using real-time functional MRI (rt-fMRI) allows the establishment of a causal functional link between localized brain activity and behavior and cognition. A long tradition of research has clearly shown the brain's ability to learn volitional control of its own activity and effects on behavior. Yet, the underlying neural mechanism of self-regulation is still not fully understood. Here, we propose that self-regulation of brain activity is akin to skill learning and thus may depend on an intact subcortical motor system. We elaborate on the critical role of the basal ganglia in skill learning and neurofeedback, and clarify that brain-self-regulation need not be an explicit and conscious process as often mistakenly held. © 2013. Source


Wheeler J.C.,University of Texas at Austin | Johnson V.,University of Texas at Austin | Clocchiatti A.,Bernardo OHiggins University
Monthly Notices of the Royal Astronomical Society | Year: 2015

The shape of the light-curve peak of radioactive-powered core-collapse 'stripped-envelope' supernovae constrains the ejecta mass, nickel mass and kinetic energy by the brightness and diffusion time for a given opacity and observed expansion velocity. Late-time light curves give constraints on the ejecta mass and energy, given the gamma-ray opacity. Previous work has shown that the principal light-curve peaks for SN IIb with small amounts of hydrogen and for hydrogen/helium-deficient SN Ib/c are often rather similar near maximum light, suggesting similar ejecta masses and kinetic energies, but that late-time light curves show a wide dispersion, suggesting a dispersion in ejecta masses and kinetic energies. It was also shown that SN IIb and SN Ib/c can have very similar late-time light curves, but different ejecta velocities demanding significantly different ejectamasses and kinetic energies. We revisit these topics by collecting and analysing well-sampled single-band and quasi-bolometric light curves from the literature. We find that the late-time light curves of stripped-envelope core-collapse supernovae are heterogeneous. We also show that the observed properties, the photospheric velocity at peak, the rise time and the late decay time, can be used to determine the mean opacity appropriate to the peak. The opacity determined in thisway is considerably smaller than common estimates. We discuss how the small effective opacity may result from recombination and asymmetries in the ejecta. © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Source

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