Encontrado(s) 49202 resultado(s)
Encontrada(s) 4921 página(s)

The use of branch piles to assist in the restoration of degraded semiarid steppes

  • Castillo-Escrivà, Andreu
  • López Iborra, Germán M.
  • Cortina, Jordi
  • Tormo Blanes, Jaume
Desertification is a major environmental problem in arid and semiarid regions. Tree plantation has been commonly employed to foster the recovery of degraded areas. However, this technique is costly, and their outcomes are often uncertain. Therefore, we evaluated an alternative method for the restoration of degraded semiarid steppes that involved the construction of branch piles to attract frugivores as potential seed‐dispersing birds, promoting seed rain, and fostering the formation of woody patches. We measured the success of branch piles in terms of the number of bird visits and seed input compared to naturally occurring shrub patches. Generally, frugivorous birds visited branch piles less frequently than shrub patches. Yet, branch piles accumulated seeds of patch‐forming shrub species. Seed rain was higher under patches of the dominant shrub Rhamnus lycioides than under branch piles. In contrast, woody patches and branch piles did not differ in seed input of the less abundant Pistacia lentiscus shrub. Our study demonstrates that branch piles are used by frugivorous birds and accumulate seeds of patch‐forming shrubs. Branch piles may be a suitable method to promote the expansion of bird‐dispersed plant species and restore semiarid wooded steppes. However, their efficiency largely depends on pile persistence and economic cost., This project was financially supported by the Spanish Ministry of Education and Competitiveness (projects UNCROACH, CGL2011-30581-C02-01 and GRACCIE Programa Consolider-Ingenio 2010, CSD2007-00067). AC was supported by a Gerónimo Forteza contract (FPA/2014/080), Conselleria d’Educació, Cultura i Esport, Generalitat Valenciana).
Proyecto:


El desarrollo profesional de los docentes noveles de la Universidad Central del Ecuador desde la narrativa de sus protagonistas

  • Guerrero Gallardo, Héctor Iván
Este trabajo de grado tuvo como propósitos, establecer las problemáticas del profesorado novel universitario en su desarrollo profesional y determinar las perspectivas de aprendizaje en su desarrollo profesional. El enfoque de la investigación es el cualitativo, con la intención de comprender e interpretar el significado de las narrativas del profesorado novel conforme nueve cuestiones que se plantearon con anticipación y en los que gira el presente estudio. En el proceso investigativo, se emplearon tres fases con sus respectivas etapas: a) Preparatoria (Reflexiva y de diseño), b) De campo (Acceso, recopilación y análisis de datos) y c) informe final (Difusión de resultados). Se empleó como técnica la entrevista que fue dirigida a 68 docentes noveles provenientes de todas las Facultades de la Universidad Central del Ecuador. Para la interpretación de los datos, se empleó una matriz de codificación; precisando, categorías, códigos y subcódigos para cada cuestión de investigación. Para el análisis y procesamiento de los datos obtenidos, se utilizó el programa informático Aquad Seis a fin de interpretar los códigos sociodemográficos e inferenciales a la luz del marco conceptual generado. Consecutivamente, se confrontaron los hallazgos encontrados con otros estudios a fin de discutir sus coincidencias y diferencias para su comprensión. Posteriormente, se establecieron conclusiones generales respecto, a: problemáticas en sus funciones básicas, influencia de las relaciones con autoridades y compañeros para el desarrollo profesional, oportunidades de participación y responsabilidades, percepción sobre sus procesos de capacitación, necesidades para su formación profesional, decisiones de las autoridades institucionales para fortalecer el desarrollo profesional y perspectivas de aprendizaje para el desarrollo profesional del profesorado novel. Seguidamente, se propusieron dos alternativas para solucionar la problemática investigada y finalmente; se crearon, tres implicaciones con la finalidad de reflexionar y rediseñar los procesos empleados para el desarrollo profesional del profesorado novel universitario.
Proyecto:


The nitrogen regulator PipX acts in cis to prevent operon polarity

  • Cantos, Raquel
  • Labella, Jose I.
  • Espinosa, Javier
  • Contreras, Asunción
Cyanobacteria, phototrophic organisms performing oxygenic photosynthesis, must adapt their metabolic processes to important environmental challenges, like those imposed by the succession of days and nights. Not surprisingly, certain regulatory proteins are found exclusively in this phylum. One of these unique factors, PipX, provides a mechanistic link between signals of carbon/nitrogen and of energy, transduced by the signalling protein PII, and the control of gene expression by the global nitrogen regulator NtcA. Here we report a new regulatory function of PipX: enhancement in cis of pipY expression, a gene encoding a universally conserved protein involved in amino/keto acid and Pyridoxal phosphate homeostasis. In Synechococcus elongatus and many other cyanobacteria these genes are expressed as a bicistronic pipXY operon. Despite being cis‐acting, polarity suppression by PipX is nevertheless reminiscent of the function of NusG paralogues typified by RfaH, which are non‐essential operon‐specific bacterial factors acting in trans to upregulate horizontally‐acquired genes. Furthermore, PipX and members of the NusG superfamily share a TLD/KOW structural domain, suggesting regulatory interactions of PipX with the translation machinery. Our results also suggest that the cis‐acting function of PipX is a sophisticated regulatory strategy for maintaining appropriate PipX–PipY stoichiometry., The authors thank the Spanish Government (MINECO) for supporting grants BFU2012‐33364 and BFU2015‐66360‐P to A.C. and the University of Alicante for PhD fellowship (FPUUA59) to J.I.L.
Proyecto:


Connections between academic burnout, resilience, and psychological well‐being in nursing students: A longitudinal study

  • Ríos Rísquez, María Isabel
  • García-Izquierdo, Mariano
  • Sabuco-Tebar, Emiliana de los Ángeles
  • Carrillo García, César
  • Solano-Ruiz, MCarmen
Aims: The aim of this study was to explore the longitudinal associations between academic burnout and resilience and psychological well‐being, and the stability of these variables in a sample of university nursing students. Background: Nursing students frequently suffer academic burnout, which is brought on by different situations experienced during the training process and that can concern his psychological well‐being. Resilience is a personal resource that allows adverse situations to be handled in a successful way. Design: Longitudinal design. Methods: Data were collected at two moments separated by 18 months (2014–2016), with 218 students at T1 and 113 at T2. At each time a questionnaire was given to them, with questions about socioeconomic demographics and three validated scales to measure academic burnout, resilience, and psychological well‐being. Results: The three dimensions that make up academic burnout remained steady over time, while resilience increased and psychological well‐being improved. Hierarchical regression analyses revealed the longitudinal effect of emotional exhaustion at T1 and at T2 they showed the longitudinal effect of resilience on psychological well‐being at T2. The inverse hierarchical regression analyses did not reveal significant relationships for any of the variables measured at T2 in connection with psychological well‐being measured at T1. Conclusions: Emotional exhaustion was the most relevant dimension of academic burnout when predicting psychological well‐being in the analysed sample. Moreover, resilience has an important positive effect on psychological well‐being in the analysed sample. The practical implications of the results are discussed from the perspective of academic training and some recommendations are given for future research in this field., This work was supported by the College of Nursing of the Region of Murcia, Spain. [Grant number: 1221/13].
Proyecto:


Aridity preferences alter the relative importance of abiotic and biotic drivers on plant species abundance in global drylands

  • Berdugo, Miguel
  • Maestre, Fernando T.
  • Kéfi, Sonia
  • Gross, Nicolas
  • Le Bagousse-Pinguet, Yoann
  • Soliveres, Santiago
1. Disentangling the interplay between species‐specific environmental preferences and micro‐ and macroscale determinants of species abundance within plant communities remains challenging. Most existing studies addressing this issue either lack empirical data regarding species interactions and local abundances or cover a narrow range of environmental conditions. 2. We merged species distribution models and local spatial patterns to investigate the relative importance of key macro‐ (aridity) and micro(facilitation and competition)scale determinants of plant species abundance along aridity gradients in drylands world‐wide. We used information derived from the environmental niches of species to evaluate how species‐specific aridity preferences modulate the importance of such factors to drive species relative abundance. 3. Facilitation and aridity preferences were more important than competition to explain species local abundances in global drylands. The specialization of communities (i.e. their compositional shifts from species with a large range of aridity preferences towards only aridity specialists) also modulated the effect of aridity and plant–plant interactions on species abundances. The importance of facilitation to drive species abundances decreased with aridity, as species preferred arid conditions and did not need neighbours to thrive. Instead, competition showed stronger relationships with species abundances under high levels of aridity. As composition became dominated by aridity specialists, the importance of aridity in shaping dryland plant communities did not increase further from moderate to high aridity levels. 4. Synthesis. Our results showed that: (a) the degree of community specialization to aridity mediates the relative importance of plant–plant interactions in determining species abundances and (b) facilitation and competition were more strongly related to species abundance in communities dominated by generalists and specialists, respectively. We observed a shift from facilitation to competition as drivers of species abundances as aridity increases in global drylands. Our findings also pave the way to develop more robust predictions about the consequences of ongoing climate change on the assemblage of plant communities in drylands, the largest terrestrial biome., This work was funded by the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement 242658 (BIOCOM). MB was supported by a FPU fellowship from the Spanish Ministry of Education, Culture and Sports (Ref. AP2010-0759). FTM acknowledges support from a Humboldt Research Award from the Alexander von Humboldt Foundation and from the European Research Council (ERC Grant agreement 647038 [BIODESERT]). The research of SK has received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 283068 (CASCADE). Y.L.B.P was supported by a Marie Sklodowska-Curie Actions Individual Fellowship (MSCA-IF) within the European Program Horizon 2020 (DRYFUN Project 656035). SS was supported by the Spanish Government under a Ramón y Cajal contract (RYC-2016- 20604). N.G. was supported by the AgreenSkills+ fellowship programme which has received funding from the EU’s Seventh Framework Programme under grant agreement N° FP7-609398 (AgreenSkills+ contract).
Proyecto:


Influence of Blending Ratio and Polymer Matrix on the Lasing Properties of Perylenediimide Dyes

  • Muñoz-Mármol, Rafael
  • Zink-Lorre, Nathalie
  • Villalvilla Soria, José Moisés
  • Boj Giménez, Pedro
  • Quintana Arévalo, José Antonio
  • Vázquez Ferri, Carmen
  • Anderson, Alec
  • Gordon, Michael J.
  • Sastre Santos, Ángela
  • Fernández Lázaro, Fernando
  • Díaz-García, María A.
Perylenediimide (PDI) dyes dispersed in polymer films have demonstrated great success as active materials in thin-film organic lasers (TFOLs). The type of matrix used to host the dye and the dye doping rate are both crucial parameters to optimize laser performance. This work reports the study of two soluble PDIs, the comercial derivative perylene orange (PDI-O) emitting at around 580 nm, and a new dye (b-PDI-A) with substituents at the 1,7 bay positions of the PDI core emitting at around 620 nm, dispersed at different doping levels (up to 8 and 50 wt %, for PDI-O and b-PDI-A, respectively) in two widely used polymers for optoelectronics, polystyrene (PS) and poly(methyl methacrylate) (PMMA). The main goal is to determine which of these two polymers, and at which dye concentration, provides the best results for their use in TFOLs. The assessment of the active materials has been carried out through the analysis of their absorption, photoluminescence, and amplified spontaneous emission (ASE) properties. Their capability to form high-quality optical waveguides has also been studied by determining gain coefficients and waveguide losses. Results have shown that for both types of PDI derivatives PS is better than PMMA at any concentration, which means larger photoluminescence efficiency, lower ASE thresholds, longer ASE operational lifetimes, larger gain, and lower propagation waveguide losses. In addition, the onset concentration at which dye aggregation becomes significant as to negatively affect the optical properties is lower in PMMA than in PS; thus, the larger the blending ratio, the larger the superiority of PS with respect to PMMA is., Financial support from Spanish Ministerio de Economía y Competitividad (MINECO) and the European FEDER funds through Grants MAT2015-66586-R and CTQ2016-77039-R (AEI/FEDER, UE) is gratefully acknowledged. R.M-M is supported by a MINECO FPI contract (no. BES-2016-077681). M.A.D-G acknowledges support from the University of Alicante and to the Spanish Ministry of Education (grant no. PR2015-00390) to perform a sabbatical stay at UCSB.
Proyecto:


Determinants in the process of seeking help for urinary incontinence in the Chilean health system

  • Bascur-Castillo, Carolina
  • Araneda-Gatica, Valentina
  • Castro-Arias, Henry
  • Carrasco Portiño, Mercedes
  • Ruiz-Cantero, María Teresa
Objective: To analyze via the Andersen model what leads women with urinary incontinence (UI) to seek help and remain in the healthcare system. Methods: An interpretative phenomenologic study enrolling women aged 18 years or older who were diagnosed with UI at a tertiary care hospital in Chile between January and March 2016. Data were collected by semi‐structured interview. The categories explored experience with UI and reasons for seeking health care, and included the dimensions of the Andersen model. Results: Ten women were enrolled. Characteristics that eased or hindered healthcare seeking were identified to come from the women (frequency and quantity of symptoms, coping strategies, and beliefs about its causes) and from their environment (reaction of partner, family, or coworkers to her condition). Some were associated with primary care (human and/or technical resources) and some with secondary care (pelvic floor units). Conclusion: The results reflect the complexities of asking for health care for women with UI, especially in a country such as Chile with different healthcare levels. Raising awareness of this complexity and developing an approach that includes all stakeholders (institution, community, and family) is crucial for professionals who want to offer both medical therapy and wellness‐focused healthcare.
Proyecto:


Evaluating different i*-based approaches for selecting functional requirements while balancing and optimizing non-functional requirements: A controlled experiment

  • Zubcoff, Jose
  • Garrigós, Irene
  • Casteleyn, Sven
  • Mazón, Jose-Norberto
  • Aguilar Calderón, José Alfonso
  • Gomariz Castillo, Francisco José
Context: A relevant question in requirements engineering is which set of functional requirements (FR) to prioritize and implement, while keeping non-functional requirements (NFR) balanced and optimized. Objective: We aim to provide empirical evidence that requirement engineers may perform better at the task of selecting FRs while optimizing and balancing NFRs using an alternative (automated) i* post-processed model, compared to the original i* model. Method: We performed a controlled experiment, designed to compare the original i* graphical notation, with our post-processed i* visualizations based on Pareto efficiency (a tabular and a radar chart visualization). Our experiment consisted of solving different exercises of various complexity for selecting FRs while balancing NFR. We considered the efficiency (time spent to correctly answer exercises), and the effectiveness (regarding time: time spent to solve exercises, independent of correctness; and regarding correctness of the answer, independent of time). Results: The efficiency analysis shows it is 3.51 times more likely to solve exercises correctly with our tabular and radar chart visualizations than with i*. Actually, i* was the most time-consuming (effectiveness regarding time), had a lower number of correct answers (effectiveness regarding correctness), and was affected by complexity. Visual or textual preference of the subjects had no effect on the score. Beginners took more time to solve exercises than experts if i* is used (no distinction if our Pareto-based visualizations are used). Conclusion: For complex model instances, the Pareto front based tabular visualization results in more correct answers, compared to radar chart visualization. When we consider effectiveness regarding time, the i* graphical notation is the most time consuming visualization, independent of the complexity of the exercise. Finally, regarding efficiency, subjects consume less time when using radar chart visualization than tabular visualization, and even more so compared to the original i* graphical notation., Sven Casteleyn is funded under the Ramón y Cajal Program of the Spanish Government, grant number RYC-2014-16606. This work has been partially supported by the Publi@City project (TIN2016-78103-C2-2-R) from the Spanish Ministry of Economy and Competitiveness.
Proyecto:


1,3-Bis(carboxymethyl)imidazolium Chloride as a Metal-Free and Recyclable Catalyst for the Synthesis of N-Allylanilines by Allylic Substitution of Alcohols

  • Albert-Soriano, María
  • Hernández-Martínez, Laura
  • Pastor, Isidro M.
The 1,3-bis(carboxymethyl)imidazolium chloride, which is easily and in a straightforward manner prepared readily from starting materials in multigram scale, is employed as catalyst in the synthesis of N-allylanilines by allylic substitution of alcohols with anilines. This metal-free catalyst allows the reaction to be carried out under mild reaction conditions (80 °C and air open vessel) and proved to be efficient for a diversity of anilines and allylic alcohols, providing exclusively the product of N-substitution independently of the substituents in the aniline reactant. The process described is simple and effective, allowing N-allylanilines to be obtained in preparative scale [e.g., 3.30 g of N-(1,3-diphenylallyl)-4-nitroaniline]. The catalyst could be reused up to 15 cycles without loss of activity, proving its robustness., This work was financially supported by the University of Alicante (VIGROB-285) and the Spanish Ministerio de Economía y Competitividad (CTQ2015-66624-P). M.A.S. thanks the Spanish Ministerio de Educación, Cultura y Deporte for a predoctoral fellowship (FPU15/06040).
Proyecto:


White-emitting organometallo-silica nanoparticles for sun-like light-emitting diodes

  • Ezquerro, Cintia
  • Fresta, Elisa
  • Serrano, Elena
  • Lalinde, Elena
  • Garcia-Martinez, Javier
  • Berenguer, Jesús R.
  • Costa, Rubén D.
This work discloses a radically new way to prepare white-emitting hybrid nanoparticles, whose implementation in lighting devices provides encouraging proof-of-concept performances towards alternative sunlight sources. In detail, the new synthetic approach is based on the kinetic control of the formation of organometallic dots, built via the condensation of three emitting iridium(III) complexes, which are subsequently transformed into mesoporous silica nanoparticles. Our novel hybrid systems, which are exceptionally stable under harsh irradiation and thermal stress environments, show a bright white emission with a record photoluminescence quantum yield. Their remarkable performance prompted us to implement them into single-component hybrid light-emitting diodes (HLEDs), achieving a high-quality sunlight source that is stable for >2000 hours with linearly extrapolated stabilities of >10 000 h. This represents one of the most stable HLEDs reported so far, while the versatility of our synthesis approach with respect to the type of emitters opens new opportunities for the design and fabrication of white-emitting color down-converters for HLEDs in the future., C. E., E. L. and J. R. B acknowledge Spanish MINECO and AEI/FEDER (ref. CTQ2016-78463-P). C. E. also thanks Universidad de La Rioja for a grant. E. F. and R.D.C. acknowledge the program “Ayudas para la atracción de talento investigador – Modalidad 1 of the Consejería de Educación, Juventud y Deporte – Comunidad de Madrid with the reference number 2016-T1/IND-1463”. R. D. C. acknowledges Spanish MINECO for the Ramón y Cajal program (RYC-2016-20891). J.G.M. acknowledges Spanish MINECO and AEI/FEDER (ref. CTQ2014-60017-R). E.S. thanks Spanish MINECO and AEI/FEDER (ref. CTQ2015-74494-JIN) and the University of Alicante (“Ayudas para la captación de talento” program with the reference number UATALENTO16-03).
Proyecto:


Buscador avanzado