Diversity patterns of herbaceous angiosperms along gradients of elevation and forest use intensity in Central Veracruz, Mexico

Terrestrial herbs are an important element in tropical forests; however, there is a lack of research on their diversity patterns and how they respond to different forest use intensities. Studying the richness and distributional patterns of this group along elevational gradients is important in order to understand the general processes that influence this distribution. Previous investigations have been done on elevational gradients and the effect of land use intensity on plant diversity, however, relevant research on herbaceous angiosperms is still scarce compared to other groups of vascular plants, such as trees. In order to bridge this gap, I studied herbaceous angiosperm distributions along gradients of elevation and disturbance. Therefore, the study of an elevational gradient proposed in this work provides an opportunity to analyze distributional patterns of herbs in a tropical area with contrasting environmental conditions. It is important to notice that this is the first study of its class on Mexico. First, we analyzed species richness and floristic composition of herbaceous angiosperms at eight elevational sites (Chapter two). We compared those patterns with respect to land use intensities at Cofre de Perote, central Veracruz, Mexico. We established an elevational transect (40 to 3,520 m) where we recorded the occurrence of terrestrial angiosperm herbs within a total of 135 plots of 20 x 20 m. We compared species richness and floristic composition between the different elevational belts and degrees of forest disturbance. We recorded a total of 264 herb species, 31 endemic to Mexico and three classified as threatened. The total number of species represents 5.7% of species of the Veracruz´ herbaceous angiosperm flora. The elevational belts with highest species richness were 2,500 m (76) and 1,500 m (52). In most cases, secondary forests showed the highest species richness along the elevational gradient, whereas old-growth forests had fewer species. The observed species richness, including endemic elements, highlights the importance of plant conservation in areas threatened by land use changes. Additionally, we suggest that environmental heterogeneity formed by mature, disturbed and secondary forests is acceptable (and unavoidable) and can even increase species richness. Second, we described the influence of elevation and forest use intensity on alpha, beta, and gamma diversity along gradients of elevation (50 m to 3500 m) and human forest use intensity (Chapter three). We analyzed species richness and floristic composition in six vegetation belts at different elevations and in different habitats. We found some general elevational trends, such as the increase in α- diversity and βb-diversity and a decline in βw-diversity. Also, γ-diversity follows a hump-shaped pattern with a peak between 2500 m and 3000 m and a decrease at the extremes of the elevational gradient. There was no effect of forest use intensity on α-diversity, only β-diversity increased depending on the change of habitat with the highest values when old-growth forest are transformed into secondary forests. Therefore, a loss of a specific forest area is compensated by the occurrence of a similar assemblage at other areas of the same location. The observed high β-diversity, including endemic elements, suggests that a mix of different habitats is needed for reaching high γ-richness of terrestrial herbs. Third, we described the deforestation and fragmentation patterns of the study area during three different time periods (1993, 2000 and 2014; Chapter four). We quantified the net change in forest area and the loss of original forest area. Our results showed a reduction in the area of the original vegetation by about 57%. The annual net forest change rate for the first period (1993-2000) was -0.44%; and increased significantly to 0.11% for the second period (2000-2014). The old-growth forests of Central Veracruz have suffered high rates of land use change throughout the last twenty years with a reduction of this process during the last decade. In the first period, forest patches increased in irregularity, isolation and size with a reduction in the dimension of the fragments that represented the destruction of natural vegetation, whereas the second period experienced a slightly recovering of forest cover (0.11%). This chapter provides a thorough analysis of the forest transformations in Central Veracruz that will increase the consciousness of stakeholders for proper planning and management to maintain biological integrity of the area. Finally, I synthesize the principal findings of this thesis and highlight the implications for conservation. Also, I suggest potential topics be studied in the future with the data obtained, related with remaining forest and alpha and beta diversity patterns of endemic herbs (Chapter five)

Sistema de Evaluación en Ingeniería del Software 2

Con la llegada del Espacio Europeo de Educación Superior (EEES), las estrategias didácticas deben cambiar para centrarse en el aprendizaje del estudiante, convirtiendo al alumno en un elemento activo dentro de su aprendizaje, incentivando su participación, de tal manera que se sienta parte activa del proceso de aprendizaje. En la asignatura de ISG2 se han incorporado un sistema de evaluación similar al ciclo de vida de un proyecto de desarrollo software, implicando a los alumnos en su propia evolución. Con este sistema, el alumno puede reflexionar acerca de sus metas, progresos, dificultades, etc. Los resultados obtenidos avalan el procedimiento llevado a cabo.Artículo revisado por pare

Gestión del conocimiento en Pymes, una exploración

Hoy en día, en un ambiente globalizado y altamente competitivo, las pequeñas y medianas empresas (PyMES) requieren optimizar sus recursos generando ventajas que impulsen su competitividad y les posibiliten crecer para permanecer en el mercado. En este contexto, el conocimiento adquiere un papel preponderante. El objetivo de esta investigación es explorar el potencial de la gestión del conocimiento (GC) para la generación de ventajas competitivas en este tipo de empresas e identificar elementos que coadyuven a este fin. Este artículo pone de manifiesto beneficios que conlleva la aplicación de la GC en este tipo de empresas, resaltando entre otros resultados la conveniencia de realizar esta gestión bajo un enfoque integrador que considere tanto el ambiente externo como el interno, así como el uso de las tecnologías de información y comunicación en los procesos de adquisición, organización y aplicación del conocimiento. El artículo se divide en seis apartados, el primero corresponde a la introducción, el segundo presenta la metodología empleada, el tercero corresponde al marco contextual, el cuarto incluye la revisión de bibliografía de estudios teóricos y empíricos, finalmente, se presentan los resultados y conclusiones

Regional analysis of climate variability at three time scales and its effect on rainfed maize production in the Upper Lerma River Basin, Mexico

Rainy season use to be from May to September and actually is from June to September. Rainy season use to be from May to September and actually is from June to September. In the region, the most determinant factor for maize crop losses is the water deficit.This study explored climate variability in the Upper Lerma River Basin, State of Mexico, Mexico, at three timescales: annual (1960–2010), monthly (1980–2010) and seasonal (1980–2010). The effects of monthly and seasonal (2003–2010) variability on rainfed maize crops were also evaluated. The variables of rainfall, maximum temperature, minimum temperature and number of hailstorms were interpolated to generate monthly spatial-temporal series. Over a period of 51 years, the climate of the region shows an accumulative annual increase of 131 mm in rainfall and an increase of 0.8 and 0.74 °C in maximum and minimum temperature, respectively. In conclusion, significant changes in the climate variables were found at the three analyzed timescales. Seasonal climate changes were found to coincide with the most vulnerable stage or flowering period of maize; particularly, a shift in the rainfall pattern generates a water deficit that impacts production yield. Hailstorms have increased in frequency, yet their phase shift results in a lesser impact to maize during its most critical stage of development.This study was financed by the Basic Science research project, SEP-CONACYT “Mesoamerican Corn and Scenarios for Local development (El maíz473 mesoamericano y sus escenarios de desarrollo local), No. 130947. The authors also wish to thank the two anonymous reviewers and their comments for improving and restructuring the manuscript in order to highlight the results of this research

Influence of Polyol/Crosslinker Blend Composition on Phase Separation and Thermo-Mechanical Properties of Polyurethane Thin Films

[EN] Polyurethanes (PUs) from Polyethylene glycol (PEG) and polycaprolactone diol (PCL) and a crosslinker, Pentaerythritol (PE), were synthetized with isophorone diisocyanate (IPDI). In this study, we investigated the effect of polyol and crosslinker composition on phase separation and thermo-mechanical properties. The properties were studied through dynamic mechanical analysis, X-ray scattering, atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The results showed changes in PUs properties, microphase structure, and separation due to the composition of polyol/crosslinker blend. So, the largest concentration of PE produced multimodal loss factor patterns, indicating segment segregation while PUs with a PEG/PCL = 1 displayed a monomodal loss factor pattern, indicating a homogeneously distributed microphase separation. Additionally, the increase of the PEG concentration enhanced the damping capacity. On the other hand, agglomeration and thread-like structures of hard segments (HS) were observed through AFM. Finally, the thermal behavior of PUs was affected by chemical composition. Lower concentration of PE reduced the crosslinking; hence, the temperature with the maximum degradation rate.This work was supported by: Universidad de La Sabana (Grant number ING-176-2016); COLCIENCIAS, today Minister of Science, Technology and Innovation of the republic of Colombia, (Grant number 808-2018); Fondo Francisco Jose de Caldas (Contract number CT22-2017). CIBER-BBN is an initiative funded by the VI National R&D & I Plan 2008-2011, "IniciativaIngenio 2010", Consolider Program. CIBER actions are financed by the "Instituto de Salud Carlos III" with assistance from the European Regional Development Fund. DocumentArevalo-Alquichire, S.; Morales-Gonzalez, M.; Navas-Gomez, K.; Diaz, LE.; Gómez-Tejedor, J.; Serrano, M.; Valero, MF. (2020). Influence of Polyol/Crosslinker Blend Composition on Phase Separation and Thermo-Mechanical Properties of Polyurethane Thin Films. Polymers. 12(3):1-13. https://doi.org/10.3390/polym12030666S113123Kim, H.-N., Lee, D.-W., Ryu, H., Song, G.-S., & Lee, D.-S. (2019). Preparation and Characterization of Isosorbide-Based Self-Healable Polyurethane Elastomers with Thermally Reversible Bonds. Molecules, 24(6), 1061. doi:10.3390/molecules24061061Arévalo-Alquichire, S., Morales-Gonzalez, M., Diaz, L., & Valero, M. (2018). Surface Response Methodology-Based Mixture Design to Study the Influence of Polyol Blend Composition on Polyurethanes’ Properties. Molecules, 23(8), 1942. doi:10.3390/molecules23081942Brzeska, J., Elert, A., Morawska, M., Sikorska, W., Kowalczuk, M., & Rutkowska, M. (2018). Branched Polyurethanes Based on Synthetic Polyhydroxybutyrate with Tunable Structure and Properties. Polymers, 10(8), 826. doi:10.3390/polym10080826Klinedinst, D. B., Yilgör, I., Yilgör, E., Zhang, M., & Wilkes, G. L. (2012). The effect of varying soft and hard segment length on the structure–property relationships of segmented polyurethanes based on a linear symmetric diisocyanate, 1,4-butanediol and PTMO soft segments. Polymer, 53(23), 5358-5366. doi:10.1016/j.polymer.2012.08.005Guazzini, T., Bronco, S., Carignani, E., & Pizzanelli, S. (2019). Tunable ionization degree in cationic polyurethanes and effects on phase separation. European Polymer Journal, 114, 298-307. doi:10.1016/j.eurpolymj.2019.02.023Ordon, K., Szlachta, M., Szatkowski, P., & Pielichowska, K. (2019). Examining the effect of starch and hydroxyapatite crosslinking on the thermal properties of polyurethane-based biomaterials. Thermochimica Acta, 682, 178414. doi:10.1016/j.tca.2019.178414Mondal, S., & Martin, D. (2012). Hydrolytic degradation of segmented polyurethane copolymers for biomedical applications. Polymer Degradation and Stability, 97(8), 1553-1561. doi:10.1016/j.polymdegradstab.2012.04.008Wang, C., Xie, J., Xiao, X., Chen, S., & Wang, Y. (2019). Development of Nontoxic Biodegradable Polyurethanes Based on Polyhydroxyalkanoate and L-lysine Diisocyanate with Improved Mechanical Properties as New Elastomers Scaffolds. Polymers, 11(12), 1927. doi:10.3390/polym11121927Li, J.-W., Lee, H.-T., Tsai, H.-A., Suen, M.-C., & Chiu, C.-W. (2018). Synthesis and Properties of Novel Polyurethanes Containing Long-Segment Fluorinated Chain Extenders. Polymers, 10(11), 1292. doi:10.3390/polym10111292Amrollahi, M., Sadeghi, G. M. M., & Kashcooli, Y. (2011). Investigation of novel polyurethane elastomeric networks based on polybutadiene-ol/polypropyleneoxide mixture and their structure–properties relationship. Materials & Design, 32(7), 3933-3941. doi:10.1016/j.matdes.2011.02.039Tan, C., Tirri, T., & Wilen, C.-E. (2017). Investigation on the Influence of Chain Extenders on the Performance of One-Component Moisture-Curable Polyurethane Adhesives. Polymers, 9(12), 184. doi:10.3390/polym9050184Imre, B., Gojzewski, H., Check, C., Chartoff, R., & Vancso, G. J. (2017). Properties and Phase Structure of Polycaprolactone-Based Segmented Polyurethanes with Varying Hard and Soft Segments: Effects of Processing Conditions. Macromolecular Chemistry and Physics, 219(2), 1700214. doi:10.1002/macp.201700214Mondal, S., & Hu, J. L. (2006). Structural characterization and mass transfer properties of nonporous segmented polyurethane membrane: Influence of hydrophilic and carboxylic group. Journal of Membrane Science, 274(1-2), 219-226. doi:10.1016/j.memsci.2005.08.016Coleman, M. M., Pehlert, G. J., & Painter, P. C. (1996). Functional Group Accessibility in Hydrogen Bonded Polymer Blends. Macromolecules, 29(21), 6820-6831. doi:10.1021/ma9604045Lei, W., Zhou, X., Fang, C., Li, Y., Song, Y., Wang, C., & Huang, Z. (2019). New approach to recycle office waste paper: Reinforcement for polyurethane with nano cellulose crystals extracted from waste paper. Waste Management, 95, 59-69. doi:10.1016/j.wasman.2019.06.003Lei, W., Fang, C., Zhou, X., Li, Y., & Pu, M. (2018). Polyurethane elastomer composites reinforced with waste natural cellulosic fibers from office paper in thermal properties. Carbohydrate Polymers, 197, 385-394. doi:10.1016/j.carbpol.2018.06.036Ma, C., Chen, E., Sun, T., Shi, S., & Fang, Q. (2012). Preparation and characterization of tetrapod-shaped ZnO whisker filled polyurethane cross-linked epoxy/polyurethane damping composites. Journal of Reinforced Plastics and Composites, 31(22), 1564-1575. doi:10.1177/0731684412446856HUDA, M., DRZAL, L., MOHANTY, A., & MISRA, M. (2006). Chopped glass and recycled newspaper as reinforcement fibers in injection molded poly(lactic acid) (PLA) composites: A comparative study. Composites Science and Technology, 66(11-12), 1813-1824. doi:10.1016/j.compscitech.2005.10.015Li, T., Zheng, T., Han, J., Liu, Z., Guo, Z.-X., Zhuang, Z., … Guo, B.-H. (2019). Effects of Diisocyanate Structure and Disulfide Chain Extender on Hard Segmental Packing and Self-Healing Property of Polyurea Elastomers. Polymers, 11(5), 838. doi:10.3390/polym11050838Cao, Q., & Liu, P. (2007). Crystalline-amorphous phase transition of hyperbranched polyurethane phase change materials for energy storage. Journal of Materials Science, 42(14), 5661-5665. doi:10.1007/s10853-006-0884-zPang, G. K. ., Baba-Kishi, K. ., & Patel, A. (2000). Topographic and phase-contrast imaging in atomic force microscopy. Ultramicroscopy, 81(2), 35-40. doi:10.1016/s0304-3991(99)00164-3Lu, X., Xu, M., Sheng, Y., Li, Z., & Li, H. (2019). Preparation of polyurethanes with broad damping temperature range and self-healing properties. Journal of Elastomers & Plastics, 52(5), 410-431. doi:10.1177/0095244319863153Schön, P., Bagdi, K., Molnár, K., Markus, P., Pukánszky, B., & Julius Vancso, G. (2011). Quantitative mapping of elastic moduli at the nanoscale in phase separated polyurethanes by AFM. European Polymer Journal, 47(4), 692-698. doi:10.1016/j.eurpolymj.2010.09.029Sui, H. L., Liu, X. Y., Zhong, F. C., Li, X. Y., & Ju, X. (2013). A study of radiation effects on polyester urethane using two-dimensional correlation analysis based on thermogravimetric data. Polymer Degradation and Stability, 98(1), 255-260. doi:10.1016/j.polymdegradstab.2012.10.003Parcheta, P., Głowińska, E., & Datta, J. (2020). Effect of bio-based components on the chemical structure, thermal stability and mechanical properties of green thermoplastic polyurethane elastomers. European Polymer Journal, 123, 109422. doi:10.1016/j.eurpolymj.2019.10942

Nucleotides in neuroregeneration and neuroprotection

AbstractBrain injury generates the release of a multitude of factors including extracellular nucleotides, which exhibit bi-functional properties and contribute to both detrimental actions in the acute phase and also protective and reparative actions in the later recovery phase to allow neuroregeneration. A promising strategy toward restoration of neuronal function is based on activation of endogenous adult neural stem/progenitor cells. The implication of purinergic signaling in stem cell biology, including regulation of proliferation, differentiation, and cell death has become evident in the last decade. In this regard, current strategies of acute transplantation of ependymal stem/progenitor cells after spinal cord injury restore altered expression of P2X4 and P2X7 receptors and improve functional locomotor recovery. The expression of both receptors is transcriptionally regulated by Sp1 factor, which plays a key role in the startup of the transcription machinery to induce regeneration-associated genes expression. Finally, general signaling pathways triggered by nucleotide receptors in neuronal populations converge on several intracellular kinases, such as PI3K/Akt, GSK3 and ERK1,2, as well as the Nrf-2/heme oxigenase-1 axis, which specifically link them to neuroprotection. In this regard, regulation of dual specificity protein phosphatases can become novel mechanism of actions for nucleotide receptors that associate them to cell homeostasis regulation.This article is part of the Special Issue entitled ‘Purines in Neurodegeneration and Neuroregeneration’

An extra virgin olive oil‐enriched diet improves maternal, placental and cord blood parameters in GDM pregnancies

Aims: To address the effect of a diet enriched in extra virgin olive oil (EVOO) on maternal metabolic parameters and placental proinflammatory markers in Gestational diabetes mellitus (GDM) patients. Methods: Pregnant women at 24-28 weeks of gestation were enrolled: 33 GDM patients which were randomly assigned or not to the EVOO-enriched group and 17 healthy controls. Metabolic parameters were determined. Peroxisome proliferator activated receptor (PPAR) γ and PPARα protein expression, expression of microRNA (miR)-130a and miR-518d (which respectively target these PPAR isoforms) and levels of proinflammatory markers were evaluated in term placentas. Matrix metalloproteinases (MMPs) activity was evaluated in term placentas and umbilical cord blood. Results: GDM patients that received the EVOO-enriched diet showed reduced pregnancy weight gain (GDM-EVOO:10.3 ± 0.9, GDM:14.2 ± 1.4, P =.03) and reduced triglyceridemia (GDM-EVOO:231 ± 14, GDM:292 ± 21, P =.02) compared to the non-EVOO-enriched GDM group. In GDM placentas, the EVOO-enriched diet did not regulate PPARγ protein expression or miR-130a expression, but prevented the reduced PPARα protein expression (P =.02 vs GDM) and the increased miR-518d expression (P =.009 vs GDM). Increased proinflammatory markers (interleukin-1β, tumour necrosis factor-α and nitric oxide overproduction) in GDM placentas were prevented by the EVOO-enriched diet (respectively P =.001, P =.001 and P =.01 vs GDM). MMPs overactivity was prevented in placenta and umbilical cord blood in the EVOO-enriched GDM group (MMP-9: respectively P =.01 and P =.001 vs GDM). Conclusions: A diet enriched in EVOO in GDM patients reduced maternal triglyceridemia and weight gain and has antiinflammatory properties in placenta and umbilical cord blood, possibly mediated by the regulation of PPAR pathways.Fil: Gomez Ribot, Dalmiro Leonardo Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; ArgentinaFil: Diaz, Esteban. Gobierno de la Ciudad Autónoma de Buenos Aires. Hospital General de Agudos Doctor Ignacio Pirovano; ArgentinaFil: Fazio, María Victoria. Gobierno de la Ciudad Autónoma de Buenos Aires. Hospital General de Agudos Doctor Ignacio Pirovano; ArgentinaFil: Gómez, Hebe Lorena. Gobierno de la Ciudad Autónoma de Buenos Aires. Hospital General de Agudos Doctor Ignacio Pirovano; ArgentinaFil: Fornes, Daiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; ArgentinaFil: Macchi, Silvia Beatriz. Gobierno de la Ciudad Autónoma de Buenos Aires. Hospital General de Agudos Doctor Ignacio Pirovano; ArgentinaFil: Gresta, Carlos Alberto. Gobierno de la Ciudad Autónoma de Buenos Aires. Hospital General de Agudos Doctor Ignacio Pirovano; ArgentinaFil: Capobianco, Evangelina Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; ArgentinaFil: Jawerbaum, Alicia Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; Argentin