Psychometric analysis in knowledge-evaluation questionnaires, identification and implication

The experience achieved using the tool “Questionnaires”, available inside the Virtual Campus of architectural engineering school in northeast Spain, is presented. “Questionnaires” is an adequate and simple instrument to evaluate the knowledge level achieved by students. This work shows and identifies the control indices of adaptation for the questionnaires, like the Facility Index, the Standard Deviation, the Discrimination Index and the Discrimination Coefficient. Derived from these parameters, the educational performances are inferred, identified and predicted. The conclusions of this work, permit to modify deficient knowledge-evaluation practices, to identify needs for specific groups or for students with particular requirements; being, in this way, feasible to apply these parameters with guarantee of success in similar evaluation processesPostprint (published version

Analysis of the maturation process of geopolymer mortars

Mechanical and maturation of geopolymers mortars based on fly ash –FA¿ (FAM), properties are studied. The values of FAM in compressive strength were lower than conventional Portland cement mortars (PCM). For geopolymers were achieved in some cases compressive strengths up to 24.42 MPa, but in another study variables an abnormal behaviour was identified with loss of compressive strengths and elastic modulus (reaching only 14.51 MPa and 1.24 GPa). This behaviour can be attributed to a possible reaction between the aggregate and the alkaline medium, which appears to increase with +age of curing. Involvement implies that the reaction impedes or disrupts the geopolymerization process of FA, causing less compressive strength.Peer ReviewedPostprint (published version

The influence of granite cutting waste on the properties of ultra-high performance concrete

This study analyzes the effect of using waste by-products generated in the process of granite cutting as part of the granular structure of Ultra High Performance Concrete (UHPC). The manufactured concrete has a compressive strength greater than 115 MPa. This study substitutes 35%, 70% and 100% of the volume of micronized quartz powder (<40 m) with granite cutting waste. This is an innovative study where the feasibility of using waste from granite quarries as a replacement for micronized quartz in UHPC has been analyzed. The results show an improvement in the workability and compressive strength of UHPC, for all substitution ratios. The flexural strength and tensile strength increase when the substitution ratio is 35%, and even the values obtained for 100% substitution are acceptable. In view of the results obtained in this study, granite cutting waste, instead of the micronized quartz powder usually used, is a viable alternative for the manufacture of expectedly more sustainable UHPC.Peer ReviewedPostprint (published version

Análisis de imágenes del concreto permeable con agregados reciclados y humo de sílice; estudio experimental de sus propiedades físicas-mecánicas

Inyectar la mayor cantidad de agua al subsuelo es de gran importancia, ya que cuando el nivel del manto freático está por debajo de su capacidad, provoca asentamientos en el terreno. Aunado a esto reciclar el concreto es una forma efectiva para eliminar escombros que contaminan nuestros suelos. Éste concreto contiene poros interconectados que permiten el paso del agua con facilidad. Se trabajó con agregados naturales (AN) y reciclados (AR) a 25 y 50% de sustitución. A los 28 días de curado se evaluó la permeabilidad, resistencia a la flexión y compresión, así como el efecto del humo de sílice en la porosidad de la interface entre la pasta y el agregado. El estudio de la porosidad fue por medio de análisis de imagen, obteniendo micrografías del Microscopio electrónico de barrido (SEM) y comparando la porosidad, el material anhidro y los productos de hidratación (PH). Los resultados están ligados entre sí, ya que el concreto menos permeable alcanzó resistencias mecánicas mayores e inversamente, por otra parte el uso de AR provocó una disminución en las propiedades mecánicas y la forma del agregado influenció, siendo el agregado triturado un material que se enlaza mejor entre la pasta y los otros agregados. El humo de sílice ayudó a disminuir la porosidad en la pasta, debido al tamaño de sus partículas. (ANGLÈS) Inject more water into the subsoil is very important, because when the ground water level is below capacity, causing settlements on the ground. Coupled with this, concrete recycling is an effective way to remove debris that pollute our soil. This concrete contains interconnected pores that allow water to pass easily. We worked with natural aggregates (NA) and recycled (AR) at 25 and 50% substitution. At 28 days of curing, the permeability, flexural strength and compression was evaluated, and the effect of silica fume in the porosity of the interface between the paste and aggregate. The study of the porosity was through image analysis, obtaining micrographs Scanning electron microscope (SEM) and comparing the porosity, the anhydrous material hydration products. The results are linked together as the less permeable concrete obtained mechanical strength greater and inversely, on the other hand the use of AR caused a decrease in mechanical properties and aggregate shape was influential, crushed aggregate material which is a better link between the paste and the other aggregates. Silica fume helped reduce porosity in the dough due to the size of its particles.Postprint (published version

Estudio físico, químico y microestructural de geopolímeros base ceniza volante

En este trabajo se analizó el comportamiento físico, químico y microestructural de la ceniza volante activada alcalinamente. Para ello fueron utilizados diferentes tamaños de partícula de ceniza volante (CV), obtenidos por molienda manual, mezcladas con NaOH y curadas durante 7, 14 y 28 días. Las técnicas de caracterización utilizadas fueron: TGA, FTIR, MEB, adsorción física de gases y pruebas de resistencia a compresión, además del software NIVision Assistant. Los resultados muestran que la disminución de tamaño de partículas, favoreció la geopolimerización del gel N-A-S-H y mejoró las propiedades cementantes en los geopolímeros, logrando resistencias a compresión hasta de 23 MPa, por otro lado, se indica mediante análisis de imagen, que los porcentajes de porosidad en cada uno de los morteros evaluados disminuyen conforme se alejan de la zona de transición interfacial (ZTI), los cuales se corroboran con los resultados de porosimetría. (ANGLÈS) In this paper was analyzed the physical, chemical and microstructural behavior of alkali activated fly ash. This comparison was used with different particle sizes of fly ash (CV), obtained by manual milling, mixed with NaOH and cured for 7, 14 and 28 days. The characterization techniques used: TGA, FTIR, SEM, physical adsorption of gases and compressive strength tests, as well NIVision Assistant software. The results show that decreasing particle size favored NASH gel Geopolymerization and improved cementitious properties in geopolymer, achieving compressive strengths up to 23 MPa. On the other hand, indicated by image analysis, the percentages of porosity in each of the mortars evaluated decrease as they move away from the interfacial transition zone (ZTI), these results are corroborated by porosimetry method.Peer ReviewedPostprint (published version

RNA interference in Lepidoptera: an overview of successful and unsuccessful studies and implications for experimental design

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Dominant Negative Mutants of Bacillus thuringiensis Cry1Ab Toxin Function as Anti-Toxins: Demonstration of the Role of Oligomerization in Toxicity

BACKGROUND:Bacillus thuringiensis Cry toxins, that are used worldwide in insect control, kill insects by a mechanism that depends on their ability to form oligomeric pores that insert into the insect-midgut cells. These toxins are being used worldwide in transgenic plants or spray to control insect pests in agriculture. However, a major concern has been the possible effects of these insecticidal proteins on non-target organisms mainly in ecosystems adjacent to agricultural fields. METHODOLOGY/PRINCIPAL FINDINGS:We isolated and characterized 11 non-toxic mutants of Cry1Ab toxin affected in different steps of the mechanism of action namely binding to receptors, oligomerization and pore-formation. These mutant toxins were analyzed for their capacity to block wild type toxin activity, presenting a dominant negative phenotype. The dominant negative phenotype was analyzed at two levels, in vivo by toxicity bioassays against susceptible Manduca sexta larvae and in vitro by pore formation activity in black lipid bilayers. We demonstrate that some mutations located in helix alpha-4 completely block the wild type toxin activity at sub-stoichiometric level confirming a dominant negative phenotype, thereby functioning as potent antitoxins. CONCLUSIONS/SIGNIFICANCE:This is the first reported case of a Cry toxin dominant inhibitor. These data demonstrate that oligomerization is a fundamental step in Cry toxin action and represent a potential mechanism to protect special ecosystems from the possible effect of Cry toxins on non-target organisms

Opuntia in México: Identifying Priority Areas for Conserving Biodiversity in a Multi-Use Landscape

BACKGROUND: México is one of the world's centers of species diversity (richness) for Opuntia cacti. Yet, in spite of their economic and ecological importance, Opuntia species remain poorly studied and protected in México. Many of the species are sparsely but widely distributed across the landscape and are subject to a variety of human uses, so devising implementable conservation plans for them presents formidable difficulties. Multi-criteria analysis can be used to design a spatially coherent conservation area network while permitting sustainable human usage. METHODS AND FINDINGS: Species distribution models were created for 60 Opuntia species using MaxEnt. Targets of representation within conservation area networks were assigned at 100% for the geographically rarest species and 10% for the most common ones. Three different conservation plans were developed to represent the species within these networks using total area, shape, and connectivity as relevant criteria. Multi-criteria analysis and a metaheuristic adaptive tabu search algorithm were used to search for optimal solutions. The plans were built on the existing protected areas of México and prioritized additional areas for management for the persistence of Opuntia species. All plans required around one-third of México's total area to be prioritized for attention for Opuntia conservation, underscoring the implausibility of Opuntia conservation through traditional land reservation. Tabu search turned out to be both computationally tractable and easily implementable for search problems of this kind. CONCLUSIONS: Opuntia conservation in México require the management of large areas of land for multiple uses. The multi-criteria analyses identified priority areas and organized them in large contiguous blocks that can be effectively managed. A high level of connectivity was established among the prioritized areas resulting in the enhancement of possible modes of plant dispersal as well as only a small number of blocks that would be recommended for conservation management

The Effects of Governmental Protected Areas and Social Initiatives for Land Protection on the Conservation of Mexican Amphibians

Traditionally, biodiversity conservation gap analyses have been focused on governmental protected areas (PAs). However, an increasing number of social initiatives in conservation (SICs) are promoting a new perspective for analysis. SICs include all of the efforts that society implements to conserve biodiversity, such as land protection, from private reserves to community zoning plans some of which have generated community-protected areas. This is the first attempt to analyze the status of conservation in Latin America when some of these social initiatives are included. The analyses were focused on amphibians because they are one of the most threatened groups worldwide. Mexico is not an exception, where more than 60% of its amphibians are endemic. We used a niche model approach to map the potential and real geographical distribution (extracting the transformed areas) of the endemic amphibians. Based on remnant distribution, all the species have suffered some degree of loss, but 36 species have lost more than 50% of their potential distribution. For 50 micro-endemic species we could not model their potential distribution range due to the small number of records per species, therefore the analyses were performed using these records directly. We then evaluated the efficiency of the existing set of governmental protected areas and established the contribution of social initiatives (private and community) for land protection for amphibian conservation. We found that most of the species have some proportion of their potential ecological niche distribution protected, but 20% are not protected at all within governmental PAs. 73% of endemic and 26% of micro-endemic amphibians are represented within SICs. However, 30 micro-endemic species are not represented within either governmental PAs or SICs. This study shows how the role of land conservation through social initiatives is therefore becoming a crucial element for an important number of species not protected by governmental PAs