59 resultados para tunnel reinforcement
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In a democratic society, the media are central to the communication of risks and uncertainties to the public. This article presents 10 proposals for improving media coverage in social risk situations. The article focuses on the production logic of the media and its consequences for society. The proposals and the conclusions of this research are supported by an analysis of three Spanish cases: the risk implied by the Tarragona chemical complex (one of the biggest in Europe); the terrorist attacks on 11 March 2004 in Madrid; and the Carmel tunnel disaster in Barcelona on January 2005. The authors are participating in a research project on public perception of risk funded by the Spanish Education Ministry on public perception of risk (2004–2007 and 2007–2010).
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Coraebus undatus is the main insect pest of cork oak worldwide. The larvae tunnel in the cortical cambium filling the bark with galleries and causing the cork to break at harvest. The first objective of this study was to test the effect of purple traps in the attraction of C. undatus because this colour is attractive to other buprestid beetles. The second objective was to develop a diet in which field-collected larvae could be reared to adulthood. Pairs of purple and clear (control) sticky traps were placed in a cork oak forest in Girona, Spain in the summer of 2008
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Se ha estudiado el papel, como inhibidores de la acción feromonal, de determinados fluoroderivados, análogos estructurales del acetato de (Z)-l 1-hexadecenilo, componente principal de la feromona sexual del noctuido Sesamia nonagrioides Lef. Dichos compuestos fueron los análogos fluoroacetato (mono, di y trifluoroacetato de (Z)-l 1-hexadecenilo) y la trifluorometilcetona análoga [(Z)-1,1,1 -trifluoro-14-nonadecen-2-ona]. La acción inhibidora fue evaluada a partir de los resultados de actividad electrofisiológica (pruebas de electroantenograma, EAG), de estudios de comportamiento en pruebas de túnel de viento y de pruebas de capturas en campo. Los acetatos fluorados, especialmente el mono y el trifluoracetato, se mostraron como buenos inhibidores de la acción atrayente de la feromona en los tres tipos de pruebas realizadas, mientras que la trifluorometilcetona análoga mostró una actividad mucho menor.
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Self-organization is a growing interdisciplinary field of research about a phenomenon that can be observed in the Universe, in Nature and in social contexts. Research on self-organization tries to describe and explain forms, complex patterns and behaviours that arise from a collection of entities without an external organizer. As researchers in artificial systems, our aim is not to mimic self-organizing phenomena arising in Nature, but to understand and to control underlying mechanisms allowing desired emergence of forms, complex patterns and behaviours. Rather than attempting to eliminate such self-organization in artificial systems, we think that this might be deliberately harnessed in order to reach desirable global properties. In this paper we analyze three forms of self-organization: stigmergy, reinforcement mechanisms and cooperation. The amplification phenomena founded in stigmergic process or in reinforcement process are different forms of positive feedbacks that play a major role in building group activity or social organization. Cooperation is a functional form for self-organization because of its ability to guide local behaviours in order to obtain a relevant collective one. For each forms of self-organisation, we present a case study to show how we transposed it to some artificial systems and then analyse the strengths and weaknesses of such an approach
Resumo:
Des de la comunitat científica s’ha posat de manifest la necessitat d’avaluar els programes d’intervenció per a la millora de la parentalitat, especialment en el context de la infància i adolescència en risc. En aquesta recerca es presenten els resultats de l’avaluació del programa Límits aportant evidències d’eficàcia i efectivitat, que permeten identificar i descriure les seves fortaleses, així com també aquells elements que poden ser objecte de millora. El programa Límits és una proposta estructurada d’intervenció preventiva de caire selectiu amb grups de famílies de joves d’entre 14 i 18 anys que passen pel circuit de la justícia juvenil. El programa ha estat funcionant des del 2007, en diverses edicions, a tot el territori català aplegant una experiència i trajectòria remarcable que ha incidit en 351 persones i 245 famílies. El programa consta de vuit sessions en grup d’entre dotze i quinze participants, dinamitzat per dos monitors, en les que es treballen diferents estratègies a partir de l’abordatge de continguts relacionats amb les relacions i els lligams, la comunicació, els conflictes, l’establiment de normes i la disciplina. Per dur a terme l’avaluació del programa Límits s’ha partit d’un disseny quasi-experimental, pretest–postest aplicat a un grup programa (GP) i a grup col·laborador (GC) i de manera diferida (dos mesos després de la seva finalització) només al GP per constatar si s’han assolit els resultats previstos. Quan s’analitza l’evolució del GP s’observen millores en les habilitats d’autocontrol de les emocions, el reforç positiu i les relacions familiars. Tanmateix, des del punt de vista de les famílies no s’han observat canvis significatius en la millora de la percepció d’auto eficàcia del rol parental respecte el GC abans i després del programa. La percepció majoritària és que els objectius que planteja el programa són excessivament ambiciosos i en conseqüència, difícilment assolibles. Els responsables consideren que, en alguns casos, el perfil de famílies derivades al programa no és el més adequat perquè presenten problemàtiques molt més agudes a les desitjables per aquest tipus d’intervenció. Com a punts forts, es destaca que el programa és útil als ulls dels responsables i tècnics perquè genera una presa de consciència del problema i de la necessitat de canvi per part de les famílies. Els participants diuen transferir a la vida real algunes habilitats apreses especialment la comunicació i millora de les relacions familiars. Els tècnics aplicadors coincideixen amb la percepció de les famílies tot i declarar percentatges lleugerament inferiors. També és vist com un complement professional a la seva tasca que ajuda a fer un millor seguiment dels casos, i permet seguir treballant amb posterioritat amb les famílies.
Resumo:
Desde la comunidad científica se ha puesto de manifiesto la necesidad de evaluar los programas de intervención para la mejora de la parentalidad, especialmente en el contexto de la infancia y la adolescencia en riesgo. En esta investigación se presentan los resultados de la evaluación del programa Límites aportando evidencias de eficacia y efectividad, que permiten identificar y describir sus fortalezas, así como también aquellos elementos que pueden ser objeto de mejora. El programa Límites es una propuesta estructurada de intervención preventiva de carácter selectivo, con grupos de familias de jóvenes de entre 14 y 18 años que pasan por el circuito de la justicia juvenil. El programa ha estado funcionando desde 2007 en todo el territorio catalán, y ha incidido en un total de 351 personas y 245 familias. El programa consta de ocho sesiones en grupo en las que se trabajan contenidos relacionados con las relaciones y los vínculos, la comunicación, los conflictos, el establecimiento de normas y la disciplina. Para llevar a cabo la evaluación del programa Límites se ha partido de un diseño cuasi-experimental, pretest-postest aplicado a un grupo programa (GP) y grupo colaborador (GC) y de manera diferida (dos meses después de su finalización) sólo en el GP, para constatar si se han alcanzado los resultados previstos. Cuando se analiza la evolución del GP se observan mejoras en las habilidades de autocontrol de las emociones, el refuerzo positivo y las relaciones familiares. Sin embargo, desde el punto de vista de las familias no se han observado cambios significativos en la mejora de la percepción de auto eficacia del rol parental respecto al GC antes y después del programa. La percepción mayoritaria es que los objetivos que plantea el programa son excesivamente ambiciosos y en consecuencia, difícilmente alcanzables. Los responsables consideran que, en algunos casos, el perfil de familias derivadas al programa no es el más adecuado puesto que presenten problemáticas mucho más agudas a las deseables para este tipo de intervención. Como puntos fuertes, se destaca que el programa es útil a los ojos de los responsables y técnicos porque genera una toma de conciencia del problema y de la necesidad de cambio por parte de las familias. Los participantes dicen transferir a la vida real algunas habilidades aprendidas, especialmente la comunicación y mejora de las relaciones familiares. Los técnicos aplicadores coinciden con la percepción de las familias, a pesar de declarar porcentajes ligeramente inferiores. También es visto como un complemento profesional a su tarea que ayuda a hacer un mejor seguimiento de los casos, y permite seguir trabajando con posterioridad con las familias.
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The truncated hemoglobin N, HbN, of Mycobacterium tuberculosis is endowed with a potent nitric oxide dioxygenase (NOD) activity that allows it to relieve nitrosative stress and enhance in vivo survival of its host. Despite its small size, the protein matrix of HbN hosts a two-branched tunnel, consisting of orthogonal short and long channels, that connects the heme active site to the protein surface. A novel dual-path mechanism has been suggested to drive migration of O(2) and NO to the distal heme cavity. While oxygen migrates mainly by the short path, a ligand-induced conformational change regulates opening of the long tunnel branch for NO, via a phenylalanine (PheE15) residue that acts as a gate. Site-directed mutagenesis and molecular simulations have been used to examine the gating role played by PheE15 in modulating the NOD function of HbN. Mutants carrying replacement of PheE15 with alanine, isoleucine, tyrosine and tryptophan have similar O(2)/CO association kinetics, but display significant reduction in their NOD function. Molecular simulations substantiated that mutation at the PheE15 gate confers significant changes in the long tunnel, and therefore may affect the migration of ligands. These results support the pivotal role of PheE15 gate in modulating the diffusion of NO via the long tunnel branch in the oxygenated protein, and hence the NOD function of HbN.
High-Performance-Tensile-Strength Alpha-Grass Reinforced Starch-Based Fully Biodegradable Composites
Resumo:
Though there has been a great deal of work concerning the development of natural fibers in reinforced starch-based composites, there is still more to be done. In general, cellulose fibers have lower strength than glass fibers; however, their specific strength is not far from that of fiberglass. In this work, alpha-fibers were obtained from alpha-grass through a mild cooking process. The fibers were used to reinforce a starch-based biopolymer. Composites including 5 to 35% (w/w) alpha-grass fibers in their formulation were prepared, tested, and subsequently compared with those of wood- and fiberglass-reinforced polypropylene (PP). The term “high-performance” refers to the tensile strength of the studied composites and is mainly due to a good interphase, a good dispersion of the fibers inside the matrix, and a good aspect ratio. The tensile strength of the composites showed a linear evolution for fiber contents up to 35% (w/w). The strain at break of the composites decreased with the fiber content and showed the stiffening effects of the reinforcement. The prepared composites showed high mechanical properties, even approaching those of glass fiber reinforced composites
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One of the most relevant properties of composite materials to be considered is stiffness. Fiberglass has been used traditionally as a fibrous reinforcing element when stiff materials are required. However, natural fibers are been exploited as replacements for synthetic fibers to satisfy environmental concerns. Among the different natural fibers, wood fibers show the combination of relatively high aspect ratio, good specific stiffness and strength, low density, low cost, and less variability than other natural fibers of such those from annual crops. In this work, composites from polypropylene and stone groundwood fibers from softwood were prepared and mechanically characterized under tensile loads. The Young’s moduli of the ensuing composites were analyzed and their micromechanics aspects evaluated. The reinforcing effect of stone groundwood fibers was compared to that of conventional reinforcement such fiberglass. The Halpin-Tsai model with the modification proposed by Tsai-Pagano accounted fairly for the behavior of PP composites reinforced with stone groundwood fibers. It was also demonstrated that the aspect ratio of the reinforcement plays a role in the Young’s modulus of injection molded specimens
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A general method for instantaneous and time-dependent serviceability analysis of plane concrete frames is presented. The methodology is based in an extension of the classic matrix formulation for bars. The main aspects influencing the behaviour of the structural concrete are considered: cracking, creep, shrinkage or prestress losses. To simulate the effect of cracking a smeared model (developed in Part II) based on the modification of the tensile branch of the concrete stress-strain relationship is adopted. The general approach considered permits the application to different materials and constitutive laws. Sequential construction (sectional and structural), incorporation of reinforcement, consideration of the loads history; placing and removing shores, and restraining or releasing in boundary conditions are considered. Some examples are included to highlight the capabilities of the model
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Worldwide cultivation of corn is expanding, due in part to the increasing production of bioethanol. In consequence, huge amounts of corn stalks residues are been produced. Instead of incineration, we transformed the corn stalks into a semichemical pulp and successfully applied it as reinforcement in polypropylene composites. PP composites reinforced with 40% wt corn stalk single fibers were prepared, and their mechanical properties were evaluated. Through mechanical properties modeling of the composites, the intrinsic tensile strength of the cellulosic fibers that constitute the corn stalk have been determined
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An assortment of human behaviors is thought to be driven by rewards including reinforcement learning, novelty processing, learning, decision making, economic choice, incentive motivation, and addiction. In each case the ventral tegmental area/ventral striatum (nucleus accumbens) (VTAVS) system has been implicated as a key structure by functional imaging studies, mostly on the basis of standard, univariate analyses. Here we propose that standard functional magnetic resonance imaging analysis needs to be complemented by methods that take into account the differential connectivity of the VTAVS system in the different behavioral contexts in order to describe reward based processes more appropriately. We fi rst consider the wider network for reward processing as it emerged from animal experimentation. Subsequently, an example for a method to assess functional connectivity is given. Finally, we illustrate the usefulness of such analyses by examples regarding reward valuation, reward expectation and the role of reward in addiction.
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In the context of the evidence-based practices movement, the emphasis on computing effect sizes and combining them via meta-analysis does not preclude the demonstration of functional relations. For the latter aim, we propose to augment the visual analysis to add consistency to the decisions made on the existence of a functional relation without losing sight of the need for a methodological evaluation of what stimuli and reinforcement or punishment are used to control the behavior. Four options for quantification are reviewed, illustrated, and tested with simulated data. These quantifications include comparing the projected baseline with the actual treatment measurements, on the basis of either parametric or nonparametric statistics. The simulated data used to test the quantifications include nine data patterns in terms of the presence and type of effect and comprising ABAB and multiple baseline designs. Although none of the techniques is completely flawless in terms of detecting a functional relation only when it is present but not when it is absent, an option based on projecting split-middle trend and considering data variability as in exploratory data analysis proves to be the best performer for most data patterns. We suggest that the information on whether a functional relation has been demonstrated should be included in meta-analyses. It is also possible to use as a weight the inverse of the data variability measure used in the quantification for assessing the functional relation. We offer an easy to use code for open-source software for implementing some of the quantifications.
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Rodrigo, Chamizo, McLaren, & Mackintosh (1997) demonstrated the blocking effect in a navigational task using a swimming pool: rats initially trained to use three landmarks (ABC) to find an invisible platform learned less about a fourth landmark (X) added later than did rats trained from the outset with these four landmarks (ABCX). The aim of the experiment reported here was to demonstrate unblocking using a similar procedure as in the previous work. Three groups of rats were initially trained to find an invisible platfom in the presence of three landmarks: ABC for the Blocking and Unblocking groups and LMN for the Control group. Then, all animals were trained to find the platform in the presence of four landmarks, ABCX. In this second training, unlike animals in the Blocking group to which only a new landmark (X) was added in comparison to the first training, the animals in the Unblocking group also had a change in the platform position. In the Control group, both the four landmarks and the platform position were totally new at the beginning of this second training. As in Rodrigo et al. (1997) a blocking effect was found: rats in the Blocking group learned less with respect to the added landmark (X) than did animals in the Control group. However, rats in the Unblocking group learned about the added landmark (X) as well as did animals in the Control group. The results are interpreted as an unblocking effect due to a change in the platform position between the two phases of training, similarly to what is normal in classical conditioning experiments, in which a change in the conditions of reinforcement between the two training phases of a blocking design produce an attenuation or elimination of this effect. These results are explained within an error-correcting connectionist account of spatial navigation (McLaren, 2002).