369 research outputs found

    Aportaciones al estudio de la orfebrería medieval en la diócesis de Sigüenza: una cruz procesional inédita del siglo XIV en Ribarredonda (Guadalajara)

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    [ES] Este artículo presenta el hallazgo de una cruz procesional gótica de bronce dorado en la localidad de Ribarredonda (Guadalajara). El estudio formal, iconográfico y estilístico de la misma no solo consigue aproximarnos a su datación, caracterización e interpretación, sino que además nos invita a esbozar por primera vez una propuesta evolutiva para esta tipología artística dentro del contexto medieval guadalajareño.[EN] This paper presents the discovery of a gothic processional cross of gilded bronze in the village of Ribarredonda (Guadalajara). Its formal, iconographic, and stylistic study not only manages to approximate its dating, characterization, and interpretation, but also invites us to carry out for the first time an evolutionary proposal for this artistic typology within the medieval context of Guadalajara

    Assessing the ability of novel ecosystems to support animal wildlife through analysis of diurnal raptor territoriality

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    Novel ecosystems have emerged through human intervention and are rapidly expandingaround the world. Whether they can support animal wildlife has generated considerable controversy.Here we developed a new approach to evaluate the ability of a novel forest ecosystem,dominated by the exotic tree species Eucalyptus globulus, to support animal wildlife inthe medium and long term. To evaluate this ability, we took advantage of the fact that speciesterritory size decreases with increasing habitat quality, and we used territoriality of araptor guild composed of Northern Goshawk (Accipiter gentilis), Eurasian Sparrowhawk(A. nisus) and Common Buzzard (Buteo buteo) as indicator. We compared the territorialityof these species in the novel ecosystem with that in other ecosystems found in the literature.Average distances between con-specifics in the novel ecosystem were similar, or evenshorter, than those in other ecosystems. Average distances between Goshawk con-specificswere among the shortest described in the literature. All three species nested preferably in mixed stands abundant in large exotic trees, with high structural complexity and abundance of native species within the stand. Key factors supporting this diverse and dense raptor community were the special forest management system implemented in the study area and the agricultural matrix located close to forest plantations that complements the supply of prey. Our results suggest that forest management that promotes a complex and suitable forest structure can increase the ability of novel forest ecosystems to support wildlife biodiversity, particularly a diverse nesting community of forest-dwelling raptors and their preys. The results further suggest the suitability of territoriality for assessing this potential of novel ecosystemsMinisterio de Ciencia y TecnologíaUniversidad de AlcaláMinisterio de Educación y Cienci

    Higher reproductive success of small males and greater recruitment of large females could explain the strong reversed sexual dimorphism (RSD) in the northern goshawk

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    Abstract Reversed sexual dimorphism (RSD), whichoccurs when the female of a species is larger than the male,is the rule for most birds of prey but the exception amongother bird and mammal species. The selective pressuresthat favour RSD are an intriguing issue in animal ecology.Despite the large number of hypotheses proposed to explainthe evolution of RSD, there is still no consensus about themechanisms involved and whether they act on one or bothsexes, mainly because few intrapopulation studies havebeen undertaken and few raptor species have been investigated.Using the strongly size-dimorphic northern goshawk(Accipiter gentilis L.) as a model, we studied a populationwith one of the highest densities of breeding pairs reportedin the literature in order to understand selective pressuresthat may favour RSD. We evaluated life-history processes,including recruitment of adult breeders and reproductivesuccess, and we explored the mechanisms thought to act oneach sex, including hunting efficiency, diet, body conditionand mate choice. We found that smaller males producedmore fledglings than larger ones, but there was no relationshipbetween size and reproductive success for femalesMinisterio de Educación y Cienci

    Spatial relationships and mechanisms of coexistence between dominant and subordinate top predators

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    Most forest ecosystems contain a diverse community of top-level predators. How these predator species interact, and howtheir interactions infl uence their spatial distribution is still poorly understood.Here we studied interactions among top predators in a guild of diurnal forest raptors in order to test the hypothesisthat predation among competing predators (intraguild predation) signifi cantly aff ects the spatial distribution of predatorspecies, causing subordinate species to nest farther away from the dominant ones.Th e study analyzed a guild in southwestern Europe comprising three raptor species. For 8 years we studied the spatialdistribution of used nests, breeding phenology, intraguild predation, territory occupancy, and nest-builder species andsubsequent nest-user species.Th e subordinate species (sparrowhawk Accipiter nisus ) nested farther away from the dominant species (goshawk A. gentilis), which preyed on sparrowhawks but not on buzzards Buteo buteo , and closer to buzzards, with which sparrowhawks donot share many common prey. Th is presumably refl ects an eff ort to seek protection from goshawks. Th is potential positiveeff ect of buzzards on sparrowhawks may be reciprocal, because buzzards benefi t from old sparrowhawk nests, which buzzardsused as a base for their nests, and from used sparrowhawk nests, from which buzzards stole prey. Buzzards occasionallyoccupied old goshawk nests.Universidad de Alcalá de Henare

    Territoriality in diurnal raptors: relative roles of recent evolution, diet and nest site

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    Animal territoriality, defined here as defence of well-delimited breeding areas to exclude competitors, has beenwidely studied. However, the phylogenetic and ecological characteristics influencing the variation in the expressionof this behaviour are poorly understood. We evaluated the effect of phylogeny and key ecological factors on territorialbehaviour and territory size in diurnal raptors from the western Palearctic and New World. To our knowledge, ourwork is the first comparative analysis of raptor territorial behaviour and territory size that accounts for phylogeneticrelationships. One important finding is that territorial behaviour has not been strongly conserved across evolutionarytime, but differences in territoriality of diurnal raptors have been influenced by recent evolution, which has ledto variations of this behaviour in response to changes in climate and habitat. Raptor current ecology is also associatedwith the expression of these traits. Species that capture more agile prey and nest in more protected sites weremost likely to be territorial. Additionally, territorial species that are bigger and capture more agile and bigger preydefended larger territories than species feeding on more vulnerable and smaller prey. We discuss potential mechanismsfor these patterns and the implications of our findings for future research on avian territoriality.Comisión Interministerial de Ciencia y Tecnología-CICYTREMEDINALMinisterio de Educación y Cienci

    Prey preferences and recent changes in diet of a breeding population of the Northern Goshawk Accipiter gentilis in Southwestern Europe

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    Capsule: Northern Goshawk Accipiter gentilis diet has changed significantly since the 1980s,probably due to changes in populations of preferred prey species.Aims and methods: To assess changes to the breeding season diet of the Northern Goshawk insouthwest Europe over three decades. We examined prey remains at and around nests andassessed avian prey availability using point count surveys.Results: During 2008&#-11, Goshawks mainly ate birds, with Feral Pigeons Columba livia f. domesticabeing the most important prey species. Goshawks preferred prey of 100&;8722#400 g and forest preyspecies to non-forest species. Goshawk diet has changed significantly over recent decades: 22%of current prey items belong to species that were not part of the diet in the 1980s. We suggestthat these dietary changes reflect changes in the abundance of prey species of the preferredsize caused by changes in land use leading to an increase in forest cover, new prey speciescolonization and changes in the abundance and management of domestic prey.Conclusion: This study emphasizes that major transformations occurring in agroforestry systemsare affecting the main preferred prey of important forest predators, which may haveconsequences for conservation of both the predators and their prey

    Sustainable solutions for thermal energy saving in hospital operating theatres

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    Heating, ventilating and air conditioning systems in hospital operating theatres consume high amounts of energy, operate for long periods of time and provide high performance. For this reason, it is necessary to study their energy consumption and determine sustainable solutions that optimize their operation and improve their performance. In this paper, annual thermal energy consumption of a conventional operating theatre is evaluated. Potential energy savings is evaluated by maintaining an adequate indoor environmental quality for these rooms. In addition, how to minimize energy consumption depending on the air renewal flow rate used and installing a sensible heat recovery system was studied. Results show that energy demand of an operating room is reduced by 24.1% by recirculating 25% of air flow extracted from the room. Energy cost decreases 44.31% by increasing the recirculated air flow rate to 50% of the air flow extracted from the room

    Breeding habitat preferences and reproductive success of Northern Goshawk (Accipiter gentilis) in exotic Eucalyptus plantations in southwestern Europe

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    With ongoing degradation of natural forests and spread of forest plantations, plantations must play an increasinglyimportant role in biodiversity conservation. Study of habitat selection and reproductive success ofsurrogate species in plantations can guide forest management decisions for increasing biodiversity. In this paperwe studied the suitability of exotic Eucalyptus plantations managed at low intensity in northwestern Spain asbreeding habitat for Northern Goshawk (Accipiter gentilis), a top predator frequently considered a surrogatespecies in conservation.Goshawks showed high breeding density, high reproductive success and a regular spatial distribution ofnesting territories. Territoriality was the most important determinant of habitat selection. Goshawks selectedextra-mature Eucalyptus trees in areas of high structural complexity (high tree density, tree species richness, andnumber of tree strata) in the most heterogeneous forest stands (old-mixed Eucalyptus). Reproductive successdecreased with increasing local density of breeding pairs, but reproductive success was not related to structuralcharacteristics of nest stands.The studied plantations provided a suitable breeding habitat for Goshawks. The birds preferred to nest inlarge Eucalyptus trees with appropriate structure in their immediate surroundings. The strong preference ofGoshawks for structurally mature forest patches may make them useful as a surrogate species for assessing theability of forest management practices to promote overall biodiversity in exotic Eucalyptus plantations exploited at low intensity.Comisión Interministerial de Ciencia y Tecnología-CICYTMinisterio de Educación y CienciaMinisterio de Economía y CompetitividadREMEDINALUniversidad de Alcal

    Atlantic Europe in the First Millennium BC. Crossing the Divide

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    Tom Moore and Xosê-Lois Armada (eds).-- Moore, Tom et al.European first millennium BC studies have witnessed an increasing theoretical divide between the approaches adopted in different countries. Whilst topics such as ethnicity, identity, and agency have dominated many British studies, such themes have had less resonance in continental approaches. At the same time, British and Iberian first millennium BC studies have become increasingly divorced from research elsewhere in Europe. While such divergence reflects deep historical divisions in theory and methodology between European perspectives, it is an issue that has been largely ignored by scholars of the period. This book addresses these issues. Initial chapters introduce major themes (landscape studies, social organisation, historiography, dynamics of change, and identity), providing overviews on the history of approaches to these areas, personal perspectives on current problems, and possible future research directions. Subsequent chapters develop these topics, presenting case studies and in-depth discussions of particular issues relating to the first millennium BC in the Atlantic realm of Western Europe.Peer Reviewe

    Celulosa y microcelulosa de residuos del cultivo de caña de azúcar (Saccharum spp.)

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    Objective: To characterize the structure, texture and thermal properties of cellulose and cellulose microfibers (MFC) of three sugarcane crops and the development of a biocomposite. Design / methodology / approach: The celluloses were extracted by the Kraft method and the MFCs of the cultures MEX-69-290, CP-72-2086 and MEX-68-P23, using oxidative and mechanical processes; for its characterization spectroscopic, microscopic and thermal techniques were used; and were analyzed with a completely randomized design, where the treatments were cellulose and CFM extracted from the three cultivars of sugarcane; In addition to the fusion processing of a biocomposite from polylactic acid and CMF. Results: Cellulose and CFM were obtained from the straw of the three crops, the similar quality, the percentage of moisture in the straw and the cellulose having the same behavior, the chemical composition of the cellulose is of high purity. The results of XRD and FTIR have characteristic bands and similar amounts of cellulose in the crystalline phase. TGA indicates that cellulose decomposes at higher temperatures of polylactic acid (PLA), which supports melt mixing processes. Limitations of the study / implications: The varieties of sugarcane pajamas have different characteristics in the cellulose phase and in the CFM phase; but similar between cultivars. Findings / conclusions: The crystallinity by XRD and the identification of functional groups by FTIR show us characteristic bands of the cell in the crystalline phase and how the amorphous part of the straw is lost without treatment, becoming more crystalline when it becomes cellulose and mostly in microcellulose; as well as the similarity that exists in the three cultivars of said components and in similar quantities. The resistance properties of the biocomposite will be affected when the CFMs are added to the polylactic acid.Objetivo: Caracterizar la estructura, textura y propiedades térmicas de celulosas y microfibras de celulosa (MFC) de tres cultivares de caña de azúcar y la elaboración de un biocompuesto. Diseño/metodología/aproximación: Las celulosas fueron extraídas por el método Kraft y las MFC de los cultivares MEX-69-290, CP-72-2086 y MEX-68-P23, utilizando procesos oxidativos y mecánicos; para su caracterización se emplearon técnicas espectroscópicas, microscópicas y térmicas; y fueron analizadas con un diseño completamente al azar, donde los tratamientos fueron la celulosa y MFC extraídas de los tres cultivares de caña de azúcar; además de la elaboración por fusión de un biocompuesto a partir de ácido poliláctico y las MCF. Resultados: Se obtuvieron celulosa y MFC de la paja de los tres cultivares, la cual presentó similitud, teniendo el mismo comportamiento el porcentaje de humedad en la paja y la celulosa, la composición química de la celulosa es de alta pureza. Los resultados de XRD y FTIR presentan bandas características y cantidades similares de celulosa en fase cristalina. TGA indica que la celulosa se descompone a temperaturas más altas de ácido poliláctico (PLA), lo que apoya los procesos de mezcla en fusión. Limitaciones del estudio/implicaciones: Las variedades de paja de caña de azúcar presentan características diferentes en la fase de celulosa y en fase de MFC; pero similar entre cultivares. Hallazgos/conclusiones: La cristalinidad mediante XRD y la identificación de grupos funcionales por FTIR nos muestran bandas características de celulosa en fase cristalina y cómo se va perdiendo la parte amorfa de la paja sin tratamiento, volviéndose más cristalina al convertirse en celulosa y mayormente en microcelulosa; así como también la similitud que existe en las tres cultivares de dichos componentes y en cantidades semejantes. Las propiedades de resistencia del biocompuesto se vieron afectadas cuando las MFC´s se agregaron al ácido poliláctico
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