Temperature affects the morphology and calcification of Emiliania huxleyi strains

The global warming debate has sparked an unprecedented interest in temperature effects on coccolithophores. The calcification response to temperature changes reported in the literature, however, is ambiguous. The two main sources of this ambiguity are putatively differences in experimental setup and strain-specificity. In this study we therefore compare three strains isolated in the North Pacific under identical experimental conditions. Three strains of Emiliania huxleyi type A were grown under non-limiting nutrient and light conditions, at 10, 15, 20 and 25 ºC. All three strains displayed similar growth rate versus temperature relationships, with an optimum at 20-25 ºC. Elemental production (particulate inorganic carbon (PIC), particulate organic carbon (POC), total particulate nitrogen (TPN)), coccolith mass, coccolith size, and width of the tube elements cycle were positively correlated with temperature over the sub-optimum to optimum temperature range. The correlation between PIC production and coccolith mass/size supports the notion that coccolith mass can be used as a proxy for PIC production in sediment samples. Increasing PIC production was significantly positively correlated with the percentage of incomplete coccoliths in one strain only. Generally, coccoliths were heavier when PIC production was higher. This shows that incompleteness of coccoliths is not due to time shortage at high PIC production. Sub-optimal growth temperatures lead to an increase in the percentage of malformed coccoliths in a strain-specific fashion. Since in total only six strains have been tested thus far, it is presently difficult to say whether sub-optimal temperature is an important factor causing malformations in the field. The most important parameter in biogeochemical terms, the PIC:POC, shows a minimum at optimum growth temperature in all investigated strains. This clarifies the ambiguous picture featuring in the literature, i.e. discrepancies between PIC:POC-temperature relationships reported in different studies using different strains and different experimental setups. In summary, global warming might cause a decline in coccolithophore's PIC contribution to the rain ratio, as well as improved fitness in some genotypes due to less coccolith malformations.

Experiment: changing carbonate chemistry influence on coccoliths formed by Emiliania huxleyi

The coccolithophore Emiliania huxleyi is a marine phytoplankton species capable of forming small calcium carbonate scales (coccoliths) which cover the organic part of the cell. Calcification rates of E. huxleyi are known to be sensitive to changes in seawater carbonate chemistry. It has, however, not yet been clearly determined how these changes are reflected in size and weight of individual coccoliths and which specific parameter(s) of the carbonate system drive morphological modifications. Here, we compare data on coccolith size, weight, and malformation from a set of five experiments with a large diversity of carbonate chemistry conditions. This diversity allows distinguishing the influence of individual carbonate chemistry parameters such as carbon dioxide (CO2), bicarbonate (HCO3- ), carbonate ion (CO32-), and protons (H+) on the measured parameters. Measurements of fine-scale morphological structures reveal an increase of coccolith malformation with decreasing pH suggesting that H+ is the major factor causing malformations. Coccolith distal shield area varies from about 5 to 11 µm2. Changes in size seem to be mainly induced by varying [HCO3- ] and [H+] although influence of [CO32-] cannot be entirely ruled out. Changes in coccolith weight were proportional to changes in size. Increasing CaCO3 production rates are reflected in an increase in coccolith weight and an increase of the number of coccoliths formed per unit time. The combined investigation of morphological features and coccolith production rates presented in this study may help to interpret data derived from sediment cores, where coccolith morphology is used to reconstruct calcification rates in the water column.

Results of n-alkane biomarker analyses and paleoclimate reconstruction

The current study presents quantitative reconstructions of tree cover, annual precipitation and mean July temperature derived from the pollen record from Lake Billyakh (65°17'N, 126°47'E, 340 m above sea level) spanning the last ca. 50 kyr. The reconstruction of tree cover suggests presence of woody plants through the entire analyzed time interval, although trees played only a minor role in the vegetation around Lake Billyakh prior to 14 kyr BP (<5%). This result corroborates low percentages of tree pollen and low scores of the cold deciduous forest biome in the PG1755 record from Lake Billyakh. The reconstructed values of the mean temperature of the warmest month ~8-10 °C do not support larch forest or woodland around Lake Billyakh during the coldest phase of the last glacial between ~32 and ~15 kyr BP. However, modern cases from northern Siberia, ca. 750 km north of Lake Billyakh, demonstrate that individual larch plants can grow within shrub and grass tundra landscape in very low mean July temperatures of about 8 °C. This makes plausible our hypothesis that the western and southern foreland of the Verkhoyansk Mountains could provide enough moist and warm microhabitats and allow individual larch specimens to survive climatic extremes of the last glacial. Reconstructed mean values of precipitation are about 270 mm/yr during the last glacial interval. This value is almost 100 mm higher than modern averages reported for the extreme-continental north-eastern Siberia east of Lake Billyakh, where larch-dominated cold deciduous forest grows at present. This suggests that last glacial environments around Lake Billyakh were never too dry for larch to grow and that the summer warmth was the main factor, which limited tree growth during the last glacial interval. The n-alkane analysis of the Siberian plants presented in this study demonstrates rather complex alkane distribution patterns, which challenge the interpretation of the fossil records. In particular, extremely low n-alkane concentrations in the leaves of local coniferous trees and shrubs suggest that their contribution to the litter and therefore to the fossil lake sediments might be not high enough for tracing the Quaternary history of the needleleaved taxa using the n-alkane biomarker method.

Functionalism and Caprice in Stonecutting. The Case of the Nativity Chapel in Burgos Cathedral

Starting from the inaugural text of Philibert de L'Orme, stereotomic treatises and manuscripts are subject to the opposing forces of reason and fancy. The Nativity Chapel in Burgos Cathedral provides an outstanding case study on this subject. It was built in 1571-1582 by Martín de Bérriz and Martín de la Haya, using an oval vault resting on trumpet squinches to span a rectangular bay. Bed joints and rib axes are not planar curves, as usual in oval vaults. This warping is not capricious; we shall argue that it is the outcome of a systematic tracing method. As a result of this process, the slope of the bed joints increases slightly in the first courses, but stays fairly constant after the third course; this solution prevents the upper courses from slipping. Thus, in the Nativity Chapel of Burgos Cathedral, the constraints of masonry construction fostered a singular solution verging on capriccio. It is also worthwhile to remark that the warping of the joints is not easily appreciable to the eye and that the tracing process does not seem to start from a previous conception of the resulting form. All this suggests that we should be quite careful when talking about the whimsical character of Late Gothic and Early Renaissance; in some occasions, apparent caprice is the offspring of practical thinking.

Productive performance, carcass and meat quality of intact and castrated gilts slaughtered at 106 or 122 kg BW

A total of 200 (Landrace3Large White dam3Pietrain3Large White sire) gilts of 5063 days of age (23.361.47 kg BW) were used to investigate the effects of castration (intact gilt, IG v. castrated gilt, CG) and slaughter weight (SW; 106 v. 122 kg BW) on productive performance, carcass and meat quality. Four treatments were arranged factorially and five replicates of 10 pigs each per treatment. Half of the gilts were ovariectomized at 58 days of age (8 days after the beginning of the trial at 29.861.64 kg BW), whereas the other half remained intact. The pigs were slaughtered at 106 or 122 kg BW. Meat samples were taken at Musculus longissimus thoracis at the level of the last rib and subcutaneous fat samples were taken at the tail insertion. For the entire experimental period, CG had higher ( P,0.05) BW gain and higher ( P,0.001) backfat and Musculus gluteus medius fat thickness than IG. However, IG had higher ( P,0.05) loin and trimmed primal cut yields than CG. Meat quality was similar for IG and CG but the proportion of linoleic acid in subcutaneous fat was higher ( P,0.001) for IG. Pigs slaughtered at 122 kg BW had higher ( P,0.001) feed intake and poorer feed efficiency than pigs slaughtered at 106 kg BW. An increase in SW improved ( P,0.001) carcass yield but decreased ( P,0.05) trimmed primal cut yield. Meat from pigs slaughtered at the heavier BW was redder (a*; P,0.001) and had more ( P,0.01) intramuscular fat and less thawing ( P,0.05) and cooking ( P,0.10) loss than meat from pigs slaughtered at the lighter BW. In addition, pigs slaughtered at 122 kg BW had less ( P,0.01) linoleic acid content in subcutaneous fat than pigs slaughtered at 106 kg BW. Castration of gilts and slaughtering at heavier BW are useful practices for the production of heavy pigs destined to the dry-cured industry in which a certain amount of fat in the carcass is required. In contrast, when the carcasses are destined to fresh meat production, IG slaughtered at 106 kg BW is a more efficient alternative.

The Irregular Ribbed Vault of the Sacristy of the Cathedral of Saint-Jean Baptiste in Perpignan

The vault of the sacristy of the Cathedral of Saint-Jean Baptiste in Perpignan (France), constructed by the Majorcan architect Guillem Sagrera between 1433 and 1447, is an outstanding, yet strikingly unknown, example of rib vaulting. This paper analyzes the overall construction of the form of the vault, characterized by its highly irregular perimeter, with particular attention to an isolated decorated corbel which solves the problem of the wall support of a group of six ribs and is in stark contrast with the rest of the supports, which are completely unadorned. Given the extreme rigour of Sagrera in all his works (and this one in particular), this apparent “capriccio” must be justified not only by decorative or formal requirements, but also by the constructive logic of Gothic vaulting system

Ethics and materials. Some Spanish Case Studies

In Navea, north of Spain, a medieval arch bridge shows a visible distortion (fig.1a). A stone falls down from the web of a gothic vault in a big parish church in Burgos (fig. 1b), and a voussoir falls down from the rib of another gothic vault in Oviedo (fig. 1c). An oval dome collapses in Zaragoza, though another four identical domes remain safe (fig. 1d). Sometimes the building has to support new, heavier loads. The ruin of the abandoned (since the 19th Century) monastery of Melón should be consolidated, some vaults are rebuilt and the visitors can walk over them. A Franciscan Convent is going to be turned into a Cultural Centre, the loads to be supported being multiplied by a factor of two. A little medieval bridge is asked to support the pass of heavy lorries. These are some of the cases I have studied in the last two decades, all of them referring to questions of structural safety. These are the kind of situations which often occurs in the field of Historic Structures. They require a study and an answer. This is no scholarly work (though in some cases new lines of future research will emerge). A judgement must be made by the expert and this judgement affects the safety and economy, in the last instance, of people. As there are rarely unique answers, the behaviour of the expert, then, can also be judged as "ethical", if he proposes an intervention that is necessary and adequate (or, recommends no intervention, judging the situation safe), or "non-ethical", if recommends an unnecessary or disproportionate intervention. In relation to the monument, also, the proposal can be judged ethically; any intervention damaging seriously the character of the monument may be labelled un-ethical.

The construction of sexpartite vaults in Europe

Sexpartite vaults constitute one of the most interesting chapters in European Gothic architecture. Originally, the use of the square cross-ribbed vault was limited to relatively small spaces, but when the need arose to cover spaces of considerable size, a new vault with very peculiar characteristics appeared. This new vault was a cross-ribbed vault that was reinforced in the centre by a rib that was parallel to the transverse ribs which effectively divided the vault in half. This configuration breaks the side arch into two fragments, creating a pair of windows on each side. The volumetrics of these vaults is extremely complex and the difficulties involved in their construction perhaps explain why they were abandoned in favour of the simple cross ribbed vault, now with rectangular sections. The existence of the sexpartite vault barely lasted more than fifty years, from the end of the XII century and the beginning of the XIII. Towards the end of the 19th century Viollet-le-Duc gave a succinct explanation of this type of vault. A. Choisy also, later, devotes some pages to the French sexpartite vault; since then, the subject has only been broached in a few references in later studies on Gothic architecture. However, despite its short period of existence, the sexpartite vault spread throughout Europe and was used to build important vaulting. Viollet-le-Duc's sexpartite vault could be considered to be the prototype of them all, while it is true that the studies that we have conducted so far lead us to affirm that there is a wide variety of vaults, with different volumetric spaces and different construction strategies. Therefore, we believe that this chapter of international Gothic deserves further study applying the knowledge and resources that are available today. This paper has been written to explore the most significant European sexpartite vaults. New measurement technology has led to a revolution in research into the history of construction, allowing studies to be conducted that were hitherto impossible. Thorough data collection using total station and photogrammetry has enabled us to identify the stereotomy of the voussoirs, tas-de-charges and keystones, as well as the bonding of the surfaces of the severies. A comparison of the construction techniques employed in the different vaults studied reveals common construction features and aspects that are specific to each country. Thus we are able to establish the relationship between sexpartite vaults in different European countries and their influence on each other.

Influence of castration on growth performance and carcass and meat quality of heavy female pigs

The main objetive of this Doctoral Thesis was to study the influence of female castration and pig sex on growth performance and carcass and meat quality of white pigs slaughtered at different final weights. Three experiments (Exp.) were conducted. In Exp. 1, a total of 200 (Landrace * Large White dam x Pietrain * Large White sire) gilts of 50 ± 3 days of age (23.3 ± 1.47 kg BW) was used to investigate the effects of castration (intact females, IF vs. castrated feamles, CF) and slaughter weight (106 vs. 122 kg BW) on productive performance and carcass and meat quality. There were four experimental treatments arranged as a 2 x 2 factorial and 5 replicates of 10 pigs each per treatment. Half of the gilts were ovariectomized at 58 d of age (8 days after the beginning of the trial; 29.8 ± 1.64 kg BW) whereas the other half remained intact. Meat samples were taken at m. Longissimus thoracis at the level of the last rib and subcutaneous fat samples were taken at the tail insertion. For the entire experiment period, CF had higher BW gain (P<0.05) and backfat and m. Gluteus medius (GM) fat thickness (P<0.001) than IF. However, IF had higher loin and trimmed primal cut yields (P<0.05) than CF. Meat quality was similar for IF and CF but the proportion of linoleic acid in subcutaneous fat was higher (P<0.001) for IF. Pigs slaughtered at 122 kg BW had higher (P<0.001) feed intake and poorer feed efficiency than pigs slaughtered at 106 kg BW. An increase in slaughter weight (SW) improved (P<0.001) carcass yield but decreased (P<0.05) trimmed primal cut yield. Meat from females slaughtered at the heavier BW was redder (a*; P<0.001) and had more (P<0.01) intramuscular fat and less thawing (P<0.05) and cooking (P<0.10) loss than meat from females slaughtered at the lighter BW. Also, females slaughtered at 122 kg BW had less (P<0.01) linoleic acid content in the subcutaneous fat than pigs slaughtered at 106 kg BW. Castration of gilts and slaughtering at heavier BW might be useful practices for the production of heavy pigs destined to the dry cured industry in which a certain amount of fat in the carcass is required. In contrast, when the carcasses are destined to fresh meat production, IF slaughtered at 106 kg BW are a more efficient alternative. In Exp. 2, crossbred pigs (n=240) from Pietrain*Large White sires mated to Landrace*Large White dams with an average of 100 d of age (60.5 ± 2.3 kg) were used to investigate the effects of gender and slaughter weight (SW) on growth performance and carcass and meat quality characteristics. There were 6 treatments arranged factorially with 3 genders (IF vs. CF vs.castrated males, CM) and 2 SW (114 vs. 122 kg BW). Each of the 6 combinations of treatments was replicated 4 times and the experimental unit was a pen with 10 pigs. Castrated males and CF ate more feed, grew faster and had more carcass backfat depth and fat thickness at the GM muscle, but lower loin yield than IF (P<0.05). In addition, CF and CM had more intramuscular fat (P<0.05) and less linoleic acid content in the subcutaneous fat (P<0.01) than IF. Pigs slaughtered at 122 kg BW had lower ADG (P<0.05), poor gain-to-feed ratio (P<0.05), and more GM fat than pigs slaughtered at 114 kg BW (P < 0.05). It is concluded that CF and CM had similar productive performance and meat quality characteristics when slaughtered at the same age, and that the castration of females improved daily gains and increased weight and fat content of primal cuts with respect to IF. Therefore, castration of females is recommended in pigs destined to the dry-cured industry because of the beneficial effects on the quality of the primal cuts. In Exp. 3, the effects of gender and castration of females (IF vs. CF vs. CM) on performance and carcass and meat quality were studied in crossbred pigs (Landrace x Large White dams x Duroc sires) slaughtered at 119.2 (trial 1) or 131.6 (trial 2) kg BW. Intact females had better feed conversion and less carcass fat than CF and CM. Trimmed shoulder yield was higher for CM than for CF with IF being intermediate. Primal cut yield and meat quality, however were similar for all treatments. Proportion of linoleic acid in backfat was lower for CF than for IF or CM, and the differences were significant in pigs slaughtered witn 131.6 kg BW. The higher fat content and the fatty acid profile favour the use of CF and CM over IF for the production of heavy pigs destined to the dry-cured industry.

Aspectos formales y constructivos en la obra de Guillem Sagrera: el uso de las plantillas

Los enjarjes, jarjas o jarjamentos conforman el comienzo de la bóveda de crucería, el lugar en el que todos los nervios nacen reunidos. Permiten la transición entre el muro y las dovelas que constituyen nervios, resolviendo un encuentro de gran importancia constructiva. Están compuestos por piezas de lechos horizontales que traban con el muro y que, además de conformar el arranque de los nervios, han de proporcionar apoyo a las primeras dovelas. Al construirse a la vez que el muro y antes que el resto de la bóveda, se podría decir que son los encargados de portar su ADN: en ellos queda registrado el número de nervios que tendrá la bóveda, su curvatura, desde qué altura arrancará cada uno, su perfil, etc. El objetivo de este trabajo se centra en estudio de los enjarjes en la obra de Guillem Sagrera abordando su dimensión tecnológica, constructiva y de diseño. Dos características los distinguen de otras soluciones y justifican su interés: los nervios surgen directamente del muro, sin la intermediación de capiteles, ménsulas o pilastras; y se diseñan con la intención de facilitar la aparición de intersecciones entre las molduras de sus perfiles, en algunos casos mediante el cruce de los ejes de los nervios. Sagrera nos acerca a una innovación arquitectónica en la que el esfuerzo no se centra en realizar bóvedas con muchos nervios o con trazados en planta complejos, sino en la cuidada resolución de este encuentro de nervios. En ella se adivina el trabajo minucioso con las plantillas que controlan el trazado del contorno de los lechos de las piezas y la hábil mano de los canteros que son capaces de tallar intersecciones de gran complejidad. Se ha realizado un repaso de los primeros experimentos relativos al modo de relacionarse los nervios entre sí para ilustrar el contexto y origen de las soluciones realizadas por Guillem Sagrera. Mostramos que ante ciertas dificultades, consecuencia de la reunión de nervios, los constructores fueron capaces de desarrollar nuevas soluciones, mediante la experimentación con un sistema constructivo que conocían y manejaban con destreza. Para acercarnos a la comprensión de las estrategias de diseño que permiten el proyecto de estos enjarjes y los procedimientos técnicos y constructivos necesarios para su ejecución, nos vimos en la necesidad de adentrarnos en la problemática general de los enjarjes de la bóveda de crucería. De este modo, lo que empezó siendo una introducción para poder contextualizar la obra del mallorquín acabó convirtiéndose en la primera parte de la tesis, cuyo volumen prácticamente equipara a la segunda. En ella presentamos el proceso de diseño, trazado y talla de los cuatro enjarjes llevados a cabo en el taller de cantería de la ETSAM, en los que hemos podido experimentar de manera práctica los aspectos teóricos desarrollados. Estos ensayos nos han permitido contrastar hipótesis y baremar la dificultad de ciertos procedimientos o procesos, así como acercarnos realmente al elemento constructivo. El trabajo práctico nos ha enseñado a no fiarnos siempre de las hipótesis que se desarrollan modelando con el ordenador o dibujando; a valorar el pensar con las manos. En relación con la obra de Sagrera, la presente investigación realiza aportaciones al conocimiento del cambio proyectual y constructivo llevado a cabo en los arranques de las bóvedas entre los siglos XIII y XV, cuando los nervios comienzan a surgir directamente de los soportes y se dan los primeros cruzamientos. Mostramos que ya no solamente se construyen enjarjes fruto directo de la geometría general de la bóveda, sino que se llevan a cabo cambios deliberados en relación a su resultado, en los que se advierten decisiones proyectuales que, por supuesto, no serían viables sin las posibilidades que ofrece el trabajo con plantillas. ABSTRACT The solid blocks commonly known as tas-de-charge (in Spanish enjarjes, jarjas or jarjamentos) constitute the beginning of the ribbed vault – the place from which all the ribs spring together. They facilitate a transition between the wall and the rib voussoirs, and thus solve a junction of utmost constructive importance. They consist of blocks set in horizontal courses which interlock with the wall and which, as well as constituting the springing of the ribs, serve as a support for their first voussoirs. The tas-de-charge are built simultaneously with the wall and well before the remainder of the vault – thus, they arguably carry its ‘DNA’, since they register how many ribs the vault will have as well as their curvature, their springing height or their profile. This work is focused on the study of the tas-de-charge in the works of Guillem Sagrera, and will address their technological, constructive and design aspects. Two characteristics set these apart from other solutions and justify their relevance: these are that the ribs spring directly from the wall without the mediation of capitals, corbels or pilasters; and that they are deliberately designed to force the intersection of their mouldings, in some cases by crossing the rib axes. Sagrera’s work tells a story of architectural innovation – one where the effort is not centred on creating vaults with numerous ribs or a sophisticated ground plan, but on carefully solving the rib unions, which evidence a meticulous use of templates to control the tracing of the pieces’ profiles as well as the skill of the stonemasons, able to carve highly complex intersections. An overview of the first experiments with rib relationships will illustrate the context and origin of Guillem Sagrera’s solutions. We show how, faced with difficulties arising from the convergence of ribs into the tas-de-charge, builders were able to develop new solutions by experimenting with a construction system that they were already familiar with and could control easily. In order to gain a better insight into the design strategies behind his tas-de-charge and the technical and constructive procedures required for their execution, we found ourselves facing the need to address the general subject of tas-de-charge in ribbed vaults. This, which began as an introduction meant as context for Sagrera’s work, took on a life of its own and became the first half of the thesis, with a volume practically equal to that of the second. We have devoted a chapter to experimental archaeology. It comprises the design, tracing and carving processes for the four tas-de-charge executed at the ETSAM Stonecutting Workshop, in which we have tested experimentally the theories studied in the previous chapters. These tests have allowed us to contrast hypotheses, assess the difficulty of certain procedures or processes and understand the built element as a real entity. The practical work has taught us not to always trust the hypotheses proposed through computer modelling or drawing – and to recognise the importance of coordinating the hands and the mind. After studying Sagrera’s work and contrasting it with other related or previous tas-de-charge, our research will seek to make a contribution to the study of the shift in the design and construction of vault springers that took place between the 13th and 14th centuries, when ribs began to spring directly from their support and moulding crossings began to appear. We show that, from then on, tas-de-charge would not only depend on the general vault geometry – deliberate modifications would be carried out in order to achieve the desired result. This reveals design decisions that would have been unworkable if not for the effective use of template strategies.

Nuevo concepto de elementos estructurales horizontales de vidrio : placa autoportante y pretensada en forma de pi

En los últimos años, podemos darnos cuenta de la importancia que tienen las nuevas aplicaciones de vidrio especialmente en edificios turísticos donde el vértigo juega un papel importante en la visita. Sin embargo los sistemas constructivos no tienen un especial interés porque el vidrio laminado está siempre soportado por otro elemento de acero o incluso vidrio en forma de retícula. En la presente tesis voy a desarrollar una nueva solución de elemento autoportante de vidrio de gran tamaño haciendo seguro el uso del elemento para andar en el aire. El sueño de muchos arquitectos ha sido diseñar un edificio completamente transparente y a mí me gustaría contribuir a este sueño empezando a estudiar un forjado de vidrio como elemento estructural horizontal y para ello debemos cumplir requerimientos de seguridad. Uno de los objetivos es lograr un elemento lo más transparente y esbelto posible para el uso de pasarelas en vestíbulos de edificios. Las referencias construidas son bien conocidas, pero por otro lado Universidades europeas estudian continua estudiando el comportamiento del vidrio con diferentes láminas, adhesivos, apilados, insertos, sistemas de laminado, pretensado, pandeo lateral, seguridad post-rotura y muchos más aspectos necesarios. La metodología llevada a cabo en esta tesis ha sido primeramente diseñar un elemento industrial prefabricado horizontal de vidrio teniendo en cuenta todos los conceptos aprendidos en el estado del arte y la investigación para poder predimensionar el elemento. El siguiente paso será verificar el modelo por medio de cálculo analítico, simulación de elementos finitos y ensayos físicos. Para realizar los ensayos hay un paso intermedio teniendo que cambiar la hipótesis de carga uniforme a carga puntal para realizar el ensayo de flexión a 4 puntos normalizado y además cambiar a escala 1:2 para adaptarse al espacio de ensayo y ser viable económicamente. Finalmente compararé los resultados de tensión y deformación obtenidos por los tres métodos para extraer conclusiones. Sin embargo el problema de la seguridad no ha concluido, tendré que demostrar que el sistema es seguro después de que se produzca la rotura y para ello sólo dispongo de los ensayos como medio de demostración. El diseño es el resultado de la evolución de una viga tipo “I”; cuando es pretensada para obtener más resistencia, aparece el problema de pandeo lateral y éste es solucionado con una viga con sección en “T” cuya unión es resuelta con un cajeado longitudinal en la parte inferior del elemento horizontal. Las alas de éste crecen para recoger las cargas superficiales creando a su vez un punto débil en la unión que a su vez se soluciona duplicando la sección “TT” y haciendo trabajar dicho tablero de forma tan óptima como una viga continua. Dicha sección en vidrio como un único elemento pretensado es algo inédito. Además he diseñado unas escuadras metálicas en los extremos de los nervios como apoyo y placa de pretensión, así como una hendidura curva en el centro de los nervios para alojar los tirantes de acero de modo que al pretensar el tirante la placa corrija al menos la deformación por peso propio. Realizados los cambios geométricos de escala y las simplificaciones en el laminado y el adhesivo se programan la extracción de resultados desde 3 estadios diferentes: Sin pretensión y con pretensión de 750 Kg y de 1000Kg en cada nervio. Por cada estadio y por cada uno de los métodos, cálculo, simulación y ensayos, se extraen los datos de deformación y tensión en el punto medio de un nervio con el objetivo de hacer una comparación de resultados para obtener unas conclusiones, siempre en el campo de la elasticidad. Posteriormente incrementaré la carga hasta el momento de la rotura de la placa y después hasta el colapso teniendo en cuenta el tiempo y demostrando una rotura segura. El vidrio no tendrá un comportamiento plástico pero habrá sido controlado su comportamiento frágil manteniendo una carga y una deformación aceptable. ABSTRACT Over the past few years we have realized the importance of the new technologies regarding the application of glass in new buildings, especially those touristic places were the views and the heights are the reason of the visit. However, the construction systems of these glass platforms are not usually as interesting, because the laminated glass is always held by another steel substructure or even a grid-formed glass element. Throughout this thesis I am going to develop a new solution of a self-bearing element with big dimensions made out of glass, ensuring a safe solution to use as an element to walk on the air. The dream of many architects has been to create a building completely transparent, and I would like to contribute to this idea by making a glass slab as a horizontal structural element, for which we have to meet the security requirements. One of the goals is to achieve an element as transparent and slim as possible for the use in walkways of building lobbies. The glass buildings references are well known, but on the other hand the European Universities study the behaviour of the glass with different interlayers, adhesives, laminating systems, stacking, prestressed, buckling, safety, breakage and post-breakage capacity; and many other necessary aspects. The methodology followed in this thesis has been to first create a horizontal industrial prefabricated horizontal element of glass, taking into account all the concepts learned in the state of art and the investigation to be able to predimension this element. The next step will be to verify this model with an analytic calculus, a finite element modelling simulation and physical tests. To fulfil these tests there is an intermediate step, having to change the load hypothesis from a punctual one to make the test with a four points normalized deflexion, and also the scale of the sample was changed to 1:2 to adapt to the space of the test and make it economically possible. Finally, the results of tension and deformation obtained from the three methods have been compared to make the conclusions. However, the problem with safety has not concluded yet, for I will have to demonstrate that this system is safe even after its breakage, for which I can only use physical tests as a way of demonstration. The design is the result of the evolution of a typical “I” beam, which when it is prestressed to achieve more resistance, the effect of buckling overcomes, and this is solved with a “T” shaped beam, where the union is solved with a longitudinal groove on the inferior part of the horizontal element. The boards of this beam grow to cover the superficial loads, creating at the same time a weak point, which is solved by duplicating the section “TT” and therefore making this board work as optimal as a continuous beam. This glass section as a single prestressed element is unique. After the final design of the “π” glass plate was obtained and the composition of the laminated glass and interlayers has been predimensioned, the last connection elements must be contemplated. I have also designed a square steel shoe at the end of the beams, which will be the base and the prestressed board, as well as a curved slot in the centre of the nerves to accommodate the steel braces so that when this brace prestresses the board, at least the deformation due to its self-weight will be amended. Once I made the geometric changes of the scale and the simplifications on the laminating and the adhesive, the extraction on results overcomes from three different stages: without any pretension, with a pretension of 750 kg and with a pretension of 1000 kg on each rib. For each stage and for each one of the methods, calculus, simulation and tests, the deformation datum were extracted to obtain the conclusions, always in the field of the elasticity. Afterwards, I will increase the load until the moment of breakage of this board, and then until the collapse of the element, taking into account the time spent and demonstrating a safe breakage. The glass will not have a plastic behaviour, but its brittle behaviour has been controlled, keeping an acceptable load and deflection.

Animal performance and meat characteristics in steers reared in intensive conditions fed with different vegetable oils

Enhancing the quality of beef meat is an important goal in terms of improving both the nutritional value for the consumer and the commercial value for producers. The aim of this work was to study the effects of different vegetable oil supplements on growth performance, carcass quality and meat quality in beef steers reared under intensive conditions. A total of 240 Blonde D? Aquitaine steers (average BW = 293.7 ± 38.88 kg) were grouped into 24 batches (10 steers/batch) and were randomly assigned to one of the three dietary treatments (eight batches per treatment), each supplemented with either 4% hydrogenated palm oil (PALM) or fatty acids (FAs) from olive oil (OLI) or soybean oil (SOY). No differences in growth performance or carcass quality were observed. For the meat quality analysis, a steer was randomly selected from each batch and the 6th rib on the left half of the carcass was dissected. PALM meat had the highest percentage of 16:0 ( P< 0.05) and the lowest n-6/n-3 polyunsaturated fatty acids (PUFA) ratio ( P< 0.05), OLI had the highest content of t 11-18:1 ( P< 0.01) and c 9,t 11-18:2 ( P< 0.05) and SOY showed the lowest value of monounsaturated fatty acids (MUFA) ( P< 0.001), the highest percentage of PUFA ( P< 0.01) and a lower index of atherogenicity ( P = 0.07) than PALM. No significant differences in the sensory characteristics of the meat were noted. However, the results of the principal component analysis of meat characteristics enabled meat from those steers that consumed fatty acids from olive oil to be differentiated from that of steers that consumed soybean oil.

Postgastrulation Smad2-deficient embryos show defects in embryo turning and anterior morphogenesis

SMAD2 is a member of the transforming growth factor β and activin-signaling pathway. To examine the role of Smad2 in postgastrulation development, we independently generated mice with a null mutation in this gene. Smad2-deficient embryos die around day 7.5 of gestation because of failure of gastrulation and failure to establish an anterior–posterior (A-P) axis. Expression of the homeobox gene Hex (the earliest known marker of the A-P polarity and the prospective head organizer) was found to be missing in Smad2-deficient embryos. Homozygous mutant embryos and embryonic stem cells formed mesoderm derivatives revealing that mesoderm induction is SMAD2 independent. In the presence of wild-type extraembryonic tissues, Smad2-deficient embryos developed beyond 7.5 and up to 10.5 days postcoitum, demonstrating a requirement for SMAD2 in extraembryonic tissues for the generation of an A-P axis and gastrulation. The rescued postgastrulation embryos showed malformation of head structures, abnormal embryo turning, and cyclopia. Our results show that Smad2 expression is required at several stages during embryogenesis.