The use of long-term high.spatial resolution Normalized Difference vegetation Index (NDVI) to determine different environmental processes in Spain

En esta tesis doctoral se han procesado imágenes de los satélites NOAA-AVHRR de 1,1 km de resolución espacial, disponibles durante tres décadas (1981 - 2015) para obtener una base de datos del índice de vegetación NDVI, para la España peninsular y las Islas Baleares, llamada Sp_1Km_NDVI. El método incluye la calibración de la información con los coeficientes de calibración posteriores al lanzamiento de cada satélite, correcciones geométricas y topográficas, la eliminación de nubes, el filtrado temporal de las series y la obtención de compuestos semi-mensales mediante el valor máximo NDVI de las imágenes. Además, la tesis compara la nueva base de datos Sp_1km_NDVI con otras tres bases de datos NDVI. Se ha comprobado si las tendencias anuales y estacionales de la base de datos Sp_1km_NDVI y las otras tres fuentes de información muestran patrones espaciales y tendencias temporales similares. Los resultados muestran que la nueva base de datos proporciona información sobre la actividad vegetal. Es útil para investigar procesos de cambio climático y procesos relacionados con las actividades humanas, en esta región mediterránea. Y permite identificar una tendencia positiva dominante del NDVI durante el periodo de estudio. En el presente trabajo también se han estudiado la relación entre la actividad vegetal y el crecimiento de los anillos de los árboles, en distintos tipos de bosques, bajo diferentes condiciones ambientales. Para ello, la base de datos de imágenes de satélite NDVI se ha combinado con registros dendrocronológicos y datos climáticos para analizar la variabilidad interanual del crecimiento de los anillos de los árboles y la actividad vegetal en distintos biomas forestales desde 1981 y hasta 2015. Los resultados revelan la existencia de una relación positiva y significativa entre la variabilidad interanual del NDVI y el crecimiento de los anillos de los árboles. Sin embargo, esta relación depende del tipo de bosque y de las condiciones ambientales. Finalmente, se han analizado los impactos de la sequía en el NDVI, ya que la sequía es uno de los principales riesgos naturales que afectan a la actividad de la vegetación en España. En esta parte de la tesis se determinan las posibles diferencias en la sensibilidad de la vegetación a la sequía, determinada por los distintos tipos de cubiertas vegetales y por las condiciones climáticas. Y analiza las escalas de tiempo en las que la actividad vegetal está respondiendo a la severidad de la sequía. Los resultados han demostrado que, en grandes áreas de la España peninsular, la actividad vegetal está fuertemente determinada por las variaciones interanuales de la sequía. Sin embargo, existen importantes diferencias estacionales y espaciales en las que el tipo de cubierta y las condiciones de aridez juegan un papel importante. En esta tesis también se ha mostrado que la escala temporal a la que se mide la sequía es muy relevante para entender los diferentes impactos estacionales, e informa sobre la sensibilidad del NDVI a la sequía a nivel estacional y en diferentes coberturas vegetales.<br /

Influence of situational and conceptual rewording on word problem solving

Se analiza la doble naturaleza semántica y textual de la tarea de resolver un problema matemático en el aula.Background: Studies on rewording word problems can be grouped into two main groups: situational rewording, in which the situation denoted by the text is described more richly, and conceptual rewording, in which the underlying semantic relations are highlighted. Aims: Our aims are to define and distinguish these two kinds of rewording and to test empirically their relative effectiveness in two different studies. Sample: In the first study, 79 third graders, 64 fourth graders and 65 fifth graders took part; the sample for Study 2 was similar. Method: In Study 1, children were asked to solve both easy and difficult two-step change problems in three different versions: standard, situational and conceptual rewording. In Study 2, three different versions of the situational version were compared: one with only temporal elaborations, one with only causal elaborations and a "complete" version combining both elaborations. Results: In Study 1, conceptually reworded problems elicited the best results, especially among younger children and for difficult two-step problems. Neither in Study 1 nor in Study 2 did the situationally reworded problems yield better performance than standard items. Conclusion: Only conceptual rewording has proved to be useful for improving children's performance, especially among younger children and for difficult problems. The lack of impact of situational rewording cannot be explained in terms of the length of the resulting text

Analysis of teacher-student interaction in the joint solving of non-routine problems in primary education classrooms

[EN] The analysis of teacher–student interaction when jointly solving routine problems in the primary education mathematics classroom has revealed that there is scarce reasoning and little participation on students’ part. To analyze whether this fact is due to the routine nature of the problems, a sample of teachers who solved, together with their students, a routine problem involving three questions with di erent cognitive di culty levels (task 1) was analyzed, describing on which part of the problem-solving process (selection of information or reasoning) they focused their interaction. Results showed that they barely focused the interaction on reasoning, and participation of students was scarce, regardless of the cognitive di culty of the question to be answered. To check whether these results could be due to the routine nature of the problem, a nonroutine problem (task 2) was solved by the same sample of teachers and students. The results revealed an increase in both reasoning and participation of students in processes that required complex reasoning. This being so, the main conclusion of the present study is that including nonroutine problem solving in the primary education classroom as a challenging task is a reasonable way to increase students’ ability to use their own reasoning to solve problems, and to promote greater teacher–student collaboration. These two aspects are relevant for students to become creative, critical, and reflective citizens.The authors are participants in the following projects: Project Science, Innovation, and University Ministry, Spain [PGC2018–100758-B-100]; Project University of Salamanca, Spain [MODELGEO-CEI 18.K133)]; and Project Junta of Castilla-León, Spain [SA050G19

Utilizar las matemáticas para resolver problemas reales

En este trabajo de revisión se analizan las razones por las que los alumnos no son capaces de resolver problemas realistas utilizando conocimientos no matemáticos. Para ello se describen, en primer lugar, las investigaciones internacionales que han documentado estas dificultades en la resolución de problemas realistas. En segundo lugar, se describe cómo los libros de texto y la cultura del aula favorecen que los niños vayan aprendiendo de manera progresiva a resolver los problemas de matemáticas utilizando únicamente sus conocimientos matemáticos, y cómo este aprendizaje va abriendo una brecha entre las matemáticas escolares y el mundo real. En tercer lugar, se describe un estudio instruccional que ha demostrado que lograr que los alumnos resuelvan problemas realistas sin ceñirse exclusivamente a sus conocimientos matemáticos es un objetivo factible y deseable. Finalmente, se exponen una serie de consideraciones acerca del esfuerzo que supone este tipo de enseñanza de la matemática y la resolución de problemas y de los límites que marcan esta perspectiva del proceso de enseñanza y aprendizaje de las matemáticas.This paper analyses the reasons underlying children s difficulties when solving realistic wor(l)d problems in the mathematics class. In order to do so, first, international studies on these difficulties are reported. Second, we describe how characteristics of the current textbooks and classroom interaction led children to learn that mathematical problems must be solved by using only mathematical information and procedures, and not by attending to relevant real-world aspects of these problems, and how this learning process moves away the mathematics of the school from the real life. Third, an intervention study that showed how the classroom practice and culture can be successfully modified is described. Finally, some comments about the limits of these ideas are made

Multivariate analyses of soluble salts responsible for pathologies in granites of the roman aquecuct of Segovia, Spain.

8 páginas, 2 figuras, 3 tablasThe aim of this work is to characterize the main pathologies caused by salt crystallization in granitic monuments (crusts, salt efflorescence, disaggregation and disaggregation with salt efflorescence). Water soluble ions were determined quantitatively. Using the Canonical Biplot multivariate method it was determined that: a) there is a relationship between the content of water soluble salts and the different identified pathologies; b) sulphate and NO3 -, Cl-, Ca2+, Mg2+, K+ and Na+ ions are the major components of salt efflorescence; c) carbonate is a major component of the crust; and d) the disaggregated granites, with or without salt efflorescence, have a low proportion of soluble salts but no predominant ion composition.The authors are grateful for the funding received from the Town Hall of Segovia, and the National Plan project funded by the Ministry of Education and Science (CGL2007-62168BET and FEDER funds) and Ministry of Science and Innovation (MAT2010-20660)], which permitted this work to be carried out.Peer reviewe

Application of the Standardized Precipitation Evapotranspiration Index (SPEI) for drought analysis and monitoring: characteristics, recommendations and comparison with other indices

The complexity of drought quantification and analysis: • Droughts are difficult to pinpoint in time and space given different economic sectors and natural systems affected. • We identify a drought by its effects or impacts on different types of systems (agriculture, water resources, ecology, forestry, economy, etc.), but there is not a physical variable we can measure to quantify droughts. • Long-term drought objective metrics (streamflows, soil moisture, lake levels, etc.) are commonly not available. Moreover, using only objective metrics other relevant variables to determine drought severity (e.g. the atmospheric water demand) are not taken into account. • We use the so-called “DROUGHT INDICES” for drought quantification and analysis. Standardized Precipitation Evapotranspiration Index (SPEI): The SPEI uses the difference between precipitation and ETo. This represents a simple climatic water balance which is calculated at different time scales to obtain the SPEI. With a value for ETo, the difference between the precipitation (P) and PET for the month i is calculated according to: Di = Pi-EToi, The calculated D values are aggregated at different time scalesPeer Reviewe

Bark extract of Uncaria tomentosa L. for the control of strawberry phytopathogens

Gray mold (Botrytis cinerea Pers.), crown and fruit rot (Phytophthora cactorum (Lebert and Cohn) J.Schröt), and verticillium wilt (Verticillium dahliae Kleb.) are among the main diseases that affect the strawberry crop. In the study presented herein, the bark extract of Uncaria tomentosa (Willd. ex Schult.) DC, popularly known as “cat’s claw”, has been evaluated for its capability to act as a sustainable control method. The bioactive compounds present in the aqueous ammonia extract were characterized by gas chromatography–mass spectroscopy, and the antimicrobial activity of the extract—alone and in combination with chitosan oligomers (COS)—was assessed in vitro and as a coating for postharvest treatment during storage. Octyl isobutyrate (30.7%), 19α methyl-2-oxoformosanan-16-carboxylate (9.3%), tetrahydro-2-methyl-thiophene (4.7%), and α-methyl manofuranoside (4.4%) were identified as the main phytoconstituents. The results of in vitro growth inhibition tests showed that, upon conjugation of the bark extract with COS, complete inhibition was reached at concentrations in the 39–93.75 μg∙mL−1 range, depending on the pathogen. Concerning the effect of the treatment as a coating to prolong the storage life and control decay during post-harvest storage, high protection was observed at a concentration of 1000 μg∙mL−1. Because of this effectiveness, higher than that attained with conventional synthetic fungicides, the bark extracts of cat’s claw may hold promise for strawberry crop protection

A panel method based aerodynamic code for analysis of wind turbine blades

The size of commercial wind turbines has increased dramatically in the last 25 years from approximately a rated power of 50kW and a rotor diameter of 10–15m up to today’s commercially available 5MW machines with a rotor diameter of more than 120 m. This development has forced the development of reliable numerical tools which enable the prediction of steady and unsteady aerodynamic loads not only in the wind turbine blades but also in the entire wind turbine construction, including tower, drive train, rotor and control system. Within this context, this paper presents a steady-state panel method formulation based code for aerodynamic load prediction in wind turbine blades. The formulation is fully three-dimensional accounting for wake and rotational angular speed effects. A 2MW wind turbine blade has been taken as a study case to demonstrate the code capabilities.Facultad de Ingenierí

Multifunctional Nanocarriers Based on Chitosan Oligomers and Graphitic Carbon Nitride Assembly

In this study, a graphitic carbon nitride and chitosan oligomers (g-C3N4–COS) nanocarrier assembly, which was obtained by cross-linking with methacrylic anhydride (MA), was synthesized and characterized. Its characterization was carried out using infrared spectroscopy, elemental and thermal analyses, and transmission electron microscopy. The new nanocarriers (NCs), with an average particle size of 85 nm in diameter and a 0.25 dispersity index, showed photocatalytic activity (associated with the g-C3N4 moiety), susceptibility to enzymatic degradation (due to the presence of the COS moiety), and high encapsulation and moderate-high release efficiencies (>95% and >74%, respectively). As a proof of concept, the visible-light-driven photocatalytic activity of the NCs was tested for rhodamine B degradation and the reduction of uranium(VI) to uranium(IV). Regarding the potential of the nanocarriers for the encapsulation and delivery of bioactive products for crop protection, NCs loaded with Rubia tinctorum extracts were investigated in vitro against three Vitis vinifera phytopathogens (viz. Neofusicoccum parvum, Diplodia seriata, and Xylophilus ampelinus), obtaining minimum inhibitory concentration values of 750, 250, and 187.5 µg·mL−1, respectively. Their antifungal activity was further tested in vivo as a pruning wound protection product in young ‘Tempranillo’ grapevine plants that were artificially infected with the two aforementioned species of the family Botryosphaeriaceae, finding a significant reduction of the necrosis lengths in the inner woody tissues. Therefore, g-C3N4-MA-COS NCs may be put forward as a multifunctional platform for environmental and agrochemical delivery applications

Morphologic and genetic characterization of Pterygodermatites (Mesopectines) valladaresi n. sp. (Nematoda, Rictulariidae), a parasite of the mouse Mus musculus (Rodentia, Muridae) from the Canary Islands (Spain)

A new rictulariid nematode Pterygodermatites (Mesopectines) valladaresi n. sp., parasite of the house mouse Mus musculus (Rodentia: Muridae) in the Canary Islands (Spain) is described by means of light and scanning electron microscopy. The new species belongs to the subgenus Mesopectines characterized by a more or less dorsal orientation of the buccal capsule, the presence of three oesophageal teeth, the morphology of the oral denticles and the Spirurida type of arrangement of caudal papillae in males. The most discriminant characteristics between the new species and the existing species in the subgenus Mesopectines are (a) the number of cuticular projection pairs (62-64), (b) the size of right and left spicules (respectively, 62-90 µm and 123-139 µm), (c) the number of midventral fans in males (3-4), (d) the number of prevulvar/total cuticular projection pairs (38-42/63-71), (e) the posterior differentiation of combs into spines in relation to the position of the vulva and (f) the anterior position of the vulva in relation to the oesophagus-intestine junction in females. Parasitized hosts and geographical distribution are also useful criteria to distinguish P. (Me.) valladaresi n. sp. from the remaining species of the subgenus. In addition, the cox1 sequence of the new species is provided and compared with available data of related species. Keywords: Canary Islands; Muridae; Mus musculus; Pterygodermatites (Mesopectines) valladaresi n. sp.; Rictulariidae