Cambios en la estructura, patrones de reclutamiento y mortalidad en dos bosques secundarios netropicales durante la segunda fase de sucesión.

Se estudiaron los cambios en el proceso de formación de dos bosques secundarios tropicales en diferentes sitios y condiciones de formación. Uno de los bosques, denominado Jari, se ubica en el Estado de Amapá, en Ia Amazonia dei Brasil. EI otro bosque, denominado Tirimbina, se ubica en Ia provincia de Heredia, Costa Rica. Los bosques fueron talados en régimen de tala rasa y Ia sucesión, evaluada a partir de un inventario forestal continuo. En los dos sitios, Ias abundancias de Ias especies heliófitas efímeras alcanzaron un nivel máximo durante el período estudiado, para luego decaer marcadamente. Los patrones de abundancia de Ias especies heliófitas durables fueron muy diferentes a los de Ias heliófitas efímeras. En los primeros anos dei estudio Ias especies heliófitas durables Goethalsia meiantha y Caseiria arborea, en Tirimbina, y Casearia pitumba, Inga capitata, Goupia glabra, Laetia procera, Xylopia aromatica y X. nitida en Jari, tuvieron una baja representación. Posteriormente, hubo un aumento en Ia abundancia de estas especies en cada sitio. Los cambios en Ia abundancia y área basal de estos bosques secunda rios neotropicales en Ia segunda fase de sucesión fueron muy semejantes, variando en cuanto aios patrones temporales. La similitud en los patrones de cambios en Ia abundancia es uno de los indicadores de que Ias poblaciones presentes en el proceso de sucesión de bosques secundarios neotropicales son aproximadamente coetáneas. La tas a de crecimiento de los bosques se relaciona directamente con el grupo ecológico dominante. EI patrón de Ias variaciones en Ias tasas de mortalidad y reclutamiento entre los bosques fue muy semejante. La tasa de mortalidad fue influenciada por Ias condiciones en que se encuentran los gremios ecológicos dominantes en el sitio y por Ia longevidad de estos gremios. Las especies agrupadas en los diferentes gremios ecológicos presentaron comportamientos muy semejantes en Ia segunda fase de sucesión, con diferencias marcadas entre gremios

Exploring cycling induced crystallographic change in NMC with X-ray diffraction computed tomography

This study presents the application of X-ray diffraction computed tomography for the first time to analyze the crystal dimensions of LiNi0.33Mn0.33Co0.33O2 electrodes cycled to 4.2 and 4.7 V in full cells with graphite as negative electrodes at 1 μm spatial resolution to determine the change in unit cell dimensions as a result of electrochemical cycling. The nature of the technique permits the spatial localization of the diffraction information in 3D and mapping of heterogeneities from the electrode to the particle level. An overall decrease of 0.4% and 0.6% was observed for the unit cell volume after 100 cycles for the electrodes cycled to 4.2 and 4.7 V. Additionally, focused ion beam-scanning electron microscope cross-sections indicate extensive particle cracking as a function of upper cut-off voltage, further confirming that severe cycling stresses exacerbate degradation. Finally, the technique facilitates the detection of parts of the electrode that have inhomogeneous lattice parameters that deviate from the bulk of the sample, further highlighting the effectiveness of the technique as a diagnostic tool, bridging the gap between crystal structure and electrochemical performance

Targeting the MAPK7/MMP9 axis for metastasis in primary bone cancer

Metastasis is the leading cause of cancer-related death. This multistage process involves contribution from both tumour cells and the tumour stroma to release metastatic cells into the circulation. Circulating tumour cells (CTCs) survive circulatory cytotoxicity, extravasate and colonise secondary sites effecting metastatic outcome. Reprogramming the transcriptomic landscape is a metastatic hallmark, but detecting underlying master regulators that drive pathological gene expression is a key challenge, especially in childhood cancer. Here we used whole tumour plus single-cell RNA-sequencing in primary bone cancer and CTCs to perform weighted gene co-expression network analysis to systematically detect coordinated changes in metastatic transcript expression. This approach with comparisons applied to data collected from cell line models, clinical samples and xenograft mouse models revealed mitogen-activated protein kinase 7/matrix metallopeptidase 9 (MAPK7/MMP9) signalling as a driver for primary bone cancer metastasis. RNA interference knockdown of MAPK7 reduces proliferation, colony formation, migration, tumour growth, macrophage residency/polarisation and lung metastasis. Parallel to these observations were reduction of activated interleukins IL1B, IL6, IL8 plus mesenchymal markers VIM and VEGF in response to MAPK7 loss. Our results implicate a newly discovered, multidimensional MAPK7/MMP9 signalling hub in primary bone cancer metastasis that is clinically actionable

Polychaetoid/ZO-1 strengthens cell junctions under tension while localizing differently than core adherens junction proteins

During embryonic development, dramatic cell shape changes and movements reshape the embryonic body plan. These require robust but dynamic linkage between the cell–cell adherens junctions and the force-generating actomyosin cytoskeleton. Our view of this linkage has evolved, and we now realize linkage is mediated by mechanosensitive multiprotein complexes assembled via multivalent connections. Here we combine genetic, cell biological, and modeling approaches to define the mechanism of action and functions of an important player, Drosophila polychaetoid, homologue of mammalian ZO-1. Our data reveal that Pyd reinforces cell junctions under elevated tension, and facilitates cell rearrangements. Pyd is important to maintain junctional contractility and in its absence cell rearrangements stall. We next use structured illumination microscopy to define the molecular architecture of cell–cell junctions during these events. The cadherin–catenin complex and Cno both localize to puncta along the junctional membrane, but are differentially enriched in different puncta. Pyd, in contrast, exhibits a distinct localization to strands that extend out from the region occupied by core junction proteins. We then discuss the implications for the protein network at the junction–cytoskeletal interface, suggesting different proteins localize and function in distinct ways, perhaps in distinct subcomplexes, but combine to produce robust connections

The Job Search Intensity Supply Curve: How Labor Market Conditions Affect Job Search Effort

During the Great Recession of 2007, unemployment reached nearly 10 percent and the ratio of unemployment to open positions (as measured by the Help Wanted OnLine Index) more than tripled. The weak labor market prompted an unprecedented extension in the length of time in which a claimant can collect unemployment insurance (UI) to 99 weeks, at an expense to date of $226.4 billion. While many claim that extending UI during a recession will reduce search intensity, the effect of weak labor market conditions on search remains a mystery. As a result, policymakers are in the dark as to whether UI extensions reduce already low search effort during recessions or perhaps decrease excessive search, which causes congestion in the labor market. At the same time, modelers of the labor market have little empirical justification for their assumptions on how search intensity changes over the business cycle. This paper develops a search model where the impact of macro labor market conditions on a worker’s search effort depends on whether these two factors are substitutes or complements in the job search process. Parameter estimates of the structural model using a sample of unemployment spells from the National Longitudinal Survey of Youth 1997 indicate that macro labor market conditions and individual search effort are complements and move together over the business cycle. The estimation also reveals that more risk-averse and less wealthy individuals exhibit less search effort

Manejo da floresta secundária em agricultura migratória no Peru, Brasil e Nicarágua.

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