273 research outputs found
Evaluación y seguimiento de la restauración ecológica desarrollada en los montes del municipio turolense de La Zoma tras el incendio de 2009
Los incendios forestales pueden degradar drásticamente los ecosistemas, especialmente plantaciones forestales, provocando una pérdida de servicios ambientales a la sociedad. Tras el incendio de Aliaga de 2009, la empresa Aquabona/Coca-Cola, en colaboración con la fundación Ecología y Desarrollo, la DGA y la universidad de Zaragoza, está desarrollando el proyecto “Plantando Agua” en el cual se aborda la restauración ecológica de 1.230 ha pertenecientes en su mayoría al término municipal de La Zoma (Teruel). El objetivo del presente trabajo fin de grado consistió en evaluar la supervivencia –tras el paso del primer periodo estival– y el crecimiento –de julio de 2015 a febrero de 2016– de la plantación inicial realizada en el invierno 2014-15. Para ello, se muestrearon tres rodales repoblados con Acer monspessulanum, Quercus faginea, Quercus ilex, Pinus sylvestris y Sorbus domestica, en diferentes unidades ambientales, principalmente áreas exportadoras e importadoras. Los resultados, tras un primer año climáticamente benigno, dieron unas tasas de supervivencia medias-altas, tanto para el conjunto de la plantación (72,7 %), como para cada una de las especies de estudio. En lo que se refiere al crecimiento, se observó un incremento generalizado del diámetro basal en todas las especies (desde 0,64 mm hasta 0,99 mm), pero los resultados de las mediciones de altura del tallo presentaron un comportamiento irregular. Prácticamente no se observaron diferencias de supervivencia y crecimiento entre especies en las distintas escalas espaciales de estudio (conjunto de la plantación, rodales y unidades ambientales)
Efecto de rizobacterias promotoras del crecimiento vegetal en plantas sometidas a estrés hídrico: un enfoque desde la fisiología vegetal
RESUMEN
La sequía afecta significativamente el estado fisiológico de las plantas y, en consecuencia, la producción agrícola. El cambio climático supone un reto mayor para la agricultura, ya que las proyecciones indican la disminución del agua disponible para los cultivos en varias regiones del mundo. En este sentido, es necesario buscar estrategias que permitan la viabilidad de la producción sin provocar los daños que la agricultura intensiva convencional trae al equilibrio planetario. En este trabajo se abordan, desde un enfoque fisiológico, los impactos que tiene la sequía sobre las plantas y que afectan negativamente su productividad. Asimismo, se revisan los diferentes mecanismos de resistencia que han desarrollado las plantas para enfrentar la falta de agua para así comprender las características que presentan las rizobacterias promotoras del crecimiento vegetal y que, de diversas maneras, refuerzan o inducen resistencia ante el estrés hídrico en las plantas con las que se asocian, convirtiéndolas en una opción de interés para la adaptación de los cultivos ante condiciones de baja disponibilidad de agua. Asimismo, se plantea la importancia de transitar hacia la concepción de los ecosistemas rizosféricos como un sistema complejo y favorecer prácticas agrícolas basadas en el profundo entendimiento de los procesos ecológicos que se llevan a cabo entre el microbioma y la planta para coadyuvar a generar agroecosistemas productivos y resilientes ante los embates del cambio climático, reduciendo las afectaciones al ambiente y la salud humana.
ABSTRACT
Drought is a stressor that significantly affects the physiological state of plants and, consequently, agricultural production. Climate change possess a major challenge to agriculture as projections indicate a decrease in water availability for crops in various world regions. Therefore, it is necessary to seek strategies that enable viable production without causing the damage associated with conventional intensified agriculture which disrupts the planetary balance. This review focuses on the physiological impacts of drought on plants which negatively affect productivity. It also examines the different resistance mechanisms that plants have developed to cope with water scarcity, aiming to understand the characteristics of plant growth promoting rhizobacteria. These bacteria, in various ways, reinforce or induce resistance to water stress in the plants they associated with, making them an interesting option for adapting crops to conditions of low water availability. Additionally, we highlight the importance of viewing rhizospheric ecosystems as complex systems that favor agricultural practices based on a deep understanding of the ecological processes occurring between the microbiome and the plant. The creation of productive and resilient agroecosystems in the face of climate change will likely reduce negative effects on the environment and human health
Crystallization of a human galectin-3 variant with two ordered segments in the shortened N-terminal tail
Among members of the family of adhesion/growth-regulatory galectins, galectin-3 (Gal-3) bears a unique modular architecture. A N-terminal tail (NT) consisting of the N-terminal segment (NTS) and nine collagen-like repeats is linked to the canonical lectin domain. In contrast to bivalent protoand tandem-repeat-type galectins, Gal-3 is monomeric in solution, capable to self-associate in the presence of bi-to multivalent ligands, and the NTS is involved in cellular compartmentalization. Since no crystallographic information on Gal-3 beyond the lectin domain is available, we used a shortened variant with NTS and repeats VII-IX. This protein crystallized as tetramers with contacts between the lectin domains. The region from Tyr101 (in repeat IX) to Leu114 (in the CRD) formed a hairpin. The NTS extends the canonical beta-sheet of F1-F5 strands with two new beta-strands on the F face. Together, crystallographic and SAXS data reveal a mode of intramolecular structure building involving the highly flexible Gal-3's NT
Nonlinear and delayed impacts of climate on dengue risk in Barbados: A modelling study
Background: Over the last 5 years (2013–2017), the Caribbean region has faced an unprecedented crisis of co-occurring epidemics of febrile illness due to arboviruses transmitted by the Aedes sp. mosquito (dengue, chikungunya, and Zika). Since 2013, the Caribbean island of Barbados has experienced 3 dengue outbreaks, 1 chikungunya outbreak, and 1 Zika fever outbreak. Prior studies have demonstrated that climate variability influences arbovirus transmission and vector population dynamics in the region, indicating the potential to develop public health interventions using climate information. The aim of this study is to quantify the nonlinear and delayed effects of climate indicators, such as drought and extreme rainfall, on dengue risk in Barbados from 1999 to 2016. Methods and findings: Distributed lag nonlinear models (DLNMs) coupled with a hierarchal mixed-model framework were used to understand the exposure–lag–response association between dengue relative risk and key climate indicators, including the standardised precipitation index (SPI) and minimum temperature (Tmin). The model parameters were estimated in a Bayesian framework to produce probabilistic predictions of exceeding an island-specific outbreak threshold. The ability of the model to successfully detect outbreaks was assessed and compared to a baseline model, representative of standard dengue surveillance practice. Drought conditions were found to positively influence dengue relative risk at long lead times of up to 5 months, while excess rainfall increased the risk at shorter lead times between 1 and 2 months. The SPI averaged over a 6-month period (SPI-6), designed to monitor drought and extreme rainfall, better explained variations in dengue risk than monthly precipitation data measured in millimetres. Tmin was found to be a better predictor than mean and maximum temperature. Furthermore, including bidimensional exposure–lag–response functions of these indicators—rather than linear effects for individual lags—more appropriately described the climate–disease associations than traditional modelling approaches. In prediction mode, the model was successfully able to distinguish outbreaks from nonoutbreaks for most years, with an overall proportion of correct predictions (hits and correct rejections) of 86% (81%:91%) compared with 64% (58%:71%) for the baseline model. The ability of the model to predict dengue outbreaks in recent years was complicated by the lack of data on the emergence of new arboviruses, including chikungunya and Zika. Conclusion: We present a modelling approach to infer the risk of dengue outbreaks given the cumulative effect of climate variations in the months leading up to an outbreak. By combining the dengue prediction model with climate indicators, which are routinely monitored and forecasted by the Regional Climate Centre (RCC) at the Caribbean Institute for Meteorology and Hydrology (CIMH), probabilistic dengue outlooks could be included in the Caribbean Health-Climatic Bulletin, issued on a quarterly basis to provide climate-smart decision-making guidance for Caribbean health practitioners. This flexible modelling approach could be extended to model the risk of dengue and other arboviruses in the Caribbean region
Modeling spectral correlations of photon-pairs generated in liquid-filled photonic crystal fiber
The generation of photon-pairs with controllable spectral correlations is crucial in quantum photonics. Here we present the design of a photonic
crystal fiber to generate widely-spaced four-wave mixing bands with spectral correlations that can be tuned through the thermo-optic effect after being infiltrated
with heavy water. We present a theoretical study of the purity of the signal (idler)
photon generated as a function of temperature, pump spectral linewidth and the
length of the fiber.511-6/18-8876CIIC155/2019APN-624TEC2016- 76664-C2-1-RPROMETEO/2019/04
Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis
The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conventional (Ti-6Al-4V), and hyperelastic (Ti-Nb-Zr). A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP) transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone
Controlled transdermal release of antioxidant ferulate by a porous Sc(III) MOF
The Sc(III) MOF-type MFM-300(Sc) is demonstrated in this study to be stable under physiological conditions (PBS), biocompatible (to human skin cells), and an efficient drug carrier for the long-term controlled release (through human skin) of antioxidant ferulate. MFM-300(Sc) also preserves the antioxidant pharmacological effects of ferulate while enhancing the bio-preservation of dermal skin fibroblasts, during the delivery process. These discoveries pave the way toward the extended use of Sc(III)-based MOFs as drug delivery systems (DDSs)
Dark Matter Candidates: A Ten-Point Test
An extraordinarily rich zoo of non-baryonic Dark Matter candidates has been
proposed over the last three decades. Here we present a 10-point test that a
new particle has to pass, in order to be considered a viable DM candidate: I.)
Does it match the appropriate relic density? II.) Is it {\it cold}? III.) Is it
neutral? IV.) Is it consistent with BBN? V.) Does it leave stellar evolution
unchanged? VI.) Is it compatible with constraints on self-interactions? VII.)
Is it consistent with {\it direct} DM searches? VIII.) Is it compatible with
gamma-ray constraints? IX.) Is it compatible with other astrophysical bounds?
X.) Can it be probed experimentally?Comment: 29 pages, 12 figure
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