Xylem biomechanics, water storage, and density within roots and shoots of an angiosperm tree species.

Xylem is a complex tissue that forms the bulk of tree bodies and has several functions, including to conduct water, store water and nutrients, and biomechanically support the plant body. We examined how xylem functional traits varied at different positions within 9-year-old Populus balsamifera subsp. trichocarpa. Whole trees were excavated, and xylem samples were collected at 1-m increments along the main root-to-shoot axis of six trees, from root tip to shoot tip. We examined biomechanical and water-storage traits of the xylem, including using a non-invasive imaging technique to examine water content within long, intact branches (high-resolution computed tomography; microCT). Xylem density, strength, and stiffness were greater in shoots than roots. Along the main root-to-shoot axis, xylem strength and stiffness were greatest at shoot tips, and the tissue became linearly weaker and less stiff down the plant and through the root. Roots had greater water storage with lower biomechanical support, and shoots had biomechanically stronger and stiffer xylem with lower water storage. These findings support trade-offs among xylem functions between roots and shoots. Understanding how xylem functions differ throughout tree bodies is important in understanding whole-tree functioning and how terrestrial plants endure numerous environmental challenges over decades of growth.

Aqueous-soluble bipyridine cobalt(ii/iii) complexes act as direct redox mediators in photosystem I-based biophotovoltaic devices.

Sustainable energy production is critical for meeting growing worldwide energy demands. Due to its stability and reduction potential, photosystem I (PSI) is attractive as the photosensitizer in biophotovoltaic devices. Herein, we characterize aqueous and organic solvent soluble synthetic bipyridine-based cobalt complexes as redox mediators for PSI-based biophotovoltaics applications. Cobalt-based complexes are not destructive to protein and have appropriate midpoint potentials for electron donation to PSI. We report on PSI stability in organic solvents commonly used in biophotovoltaics. We also show the effects of a mixed organic solvent phase on PSI reduction kinetics, slowing reduction rates approximately 8-38 fold as compared to fully aqueous systems, with implications for dye regeneration rates in PSI-based biophotovoltaics. Further, we show evidence of direct electron transfer from cobalt complexes to PSI. Finally, we report on photocurrent generation from Co mediator-PSI biophotovoltaic devices. Taken together, we discuss the development of novel Co complexes and our ability to fine-tune their characteristics via functional groups and counteranion choice to drive interaction with a biological electron acceptor on multiple levels from redox midpoints, spectral overlap, and solvent requirements, among others. This work suggests that fine-tuning of redox active species for interaction with a biological partner is possible for the creation and improvement of low cost, carbon-neutral energy production in the future.

Compasión, celos y envidia: emociones sociales y cyberbullying entre adolescentes / Compassion, jealousy and envy: social emotions and cyberbullying among adolescents

Las emociones cumplen un papel fundamental en la capacidad de acción de los seres humanos, razón por la cual es indispensable estudiarlas para entender los fenómenos sociales contemporáneos en los que participan los adolescentes. Esta investigación tiene como objetivo comprender las experiencias de la compasión, los celos y la envidia de los adolescentes implicados en situaciones de cyberbullying en los roles de espectadores y agresores. Se trata de una investigación con diseño cualitativo en la que se entrevistó a 31 adolescentes entre los 12 y 17 años (M=15,23, DS=1,6) que participaron de situaciones de cyberbullying como espectadores y/o agresores. Los resultados indican que la compasión adquiere la forma de tristeza y rabia, especialmente entre los espectadores de cyberbullying. Por otra parte, los celos son un motivo que justifica la agresión a otros a través de Internet, y una forma de gestionar las tensiones en los vínculos sexo-afectivos. El uso de redes sociales digitales y la participación en escenarios presenciales en los que se disputan posiciones a nivel académico favorece el proceso de comparación social vinculado a la envidia que está en la base del cyberbullying. Finalmente, este estudio es una invitación para padres, docentes e institucionales estatales a que acompañen a los adolescentes a gestionar sus conflictos sin que las agresiones presenciales y online medien en sus interacciones

Emotions play a fundamental role in the capacity for action of human beings, which is why it is essential to study them in order to understand contemporary social phenomena in which adolescents participate. This research aims to understand the experiences of compassion, jealousy and envy of adolescents involved in cyberbullying situations in the roles of bystanders and aggressors. This is a qualitative design research in which 31 adolescents between the ages of 12 and 17 (M=15.23, SD=1.6) who participated in cyberbullying situations as bystanders and aggressors were interviewed. The results indicate that compassion takes the form of sadness and anger, especially among cyberbullying bystanders. On the other hand, jealousy is a motive that justifies aggression to others through the Internet, and a way of managing tensions in sex-affective bonds. The use of digital social networks and participation in face-to-face scenarios in which positions are disputed at the academic level, favours the process of social comparison linked to envy that is at the basis of cyberbullying. Finally, this study is an invitation for parents, teachers and state institutions to accompany adolescents in managing their conflicts without face-to-face and online aggressions mediating their interactions.