997 resultados para Mediterranean environments


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A systematic technique for identifying the environments of construction projects is described. It provides a method for isolating the major variables surrounding construction projects, and is briefly applied to the industries of Britain and Jamaica to illustrate its application. From this, it is inferred that the environment of a Jamaican construction project in systems terms is broadly similar to the environment of a construction project in Britain.

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The aim of this work was to couple a nitrogen (N) sub-model to already existent hydrological lumped (LU4-N) and semi-distributed (LU4-R-N and SD4-R-N) conceptual models, to improve our understanding of the factors and processes controlling nitrogen cycling and losses in Mediterranean catchments. The N model adopted provides a simplified conceptualization of the soil nitrogen cycle considering mineralization, nitrification, immobilization, denitrification, plant uptake, and ammonium adsorption/desorption. It also includes nitrification and denitrification in the shallow perched aquifer. We included a soil moisture threshold for all the considered soil biological processes. The results suggested that all the nitrogen processes were highly influenced by the rain episodes and that soil microbial processes occurred in pulses stimulated by soil moisture increasing after rain. Our simulation highlighted the riparian zone as a possible source of nitrate, especially after the summer drought period, but it can also act as an important sink of nitrate due to denitrification, in particular during the wettest period of the year. The riparian zone was a key element to simulate the catchment nitrate behaviour. The lumped LU4-N model (which does not include the riparian zone) could not be validated, while both the semi-distributed LU4-R-N and SD4-R-N model (which include the riparian zone) gave satisfactory results for the calibration process and acceptable results for the temporal validation process.

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Consumption of green leafy vegetables is associated with reduced risk of several types of cancer and cardiovascular disease. These beneficial effects are attributed to a range of phytochemicals including flavonoids and glucosinolates, both of which are found in high levels in Brassicaceous crops. Rocket is the general name attributed to cultivars of Eruca sativa and Diplotaxis tenufolia, known as salad rocket and wild rocket, respectively. We have shown that different light levels during the cultivation period of these crops have a significant impact on the levels of flavonoids present in the crop at harvest, with over 15-fold increase achieved in quercetin, isorhamnetin, and cyanidin in high light conditions. Postharvest storage further affects the levels of both flavonoids and glucosinolates, with cyanidin increasing during shelf life and some glucosinolates, such as glucoiberverin, being reduced over the same storage period. In vitro assays using human colon cell lines demonstrate that glucosinolate-rich extracts of Eruca sativa cv. Sky, but not Diplotaxis tenufolia cv. Voyager, confer significant resistance to oxidative stress on the cells, which is indicative of the chemoprotective properties of the leaves from this species. Our findings indicate that both pre and postharvest environment and genotypic selection, when developing new lines of Brassicaceous vegetables, are important considerations with the goal of improving human nutrition and health.

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Virtual learning environments (VLEs) would appear to be particular effective in computer-supported collaborative work (CSCW) for active learning. Most research studies looking at computer-supported collaborative design have focused on either synchronous or asynchronous modes of communication, but near-synchronous working has received relatively little attention. Yet it could be argued that near-synchronous communication encourages creative, rhetorical and critical exchanges of ideas, building on each other’s contributions. Furthermore, although many researchers have carried out studies on collaborative design protocol, argumentation and constructive interaction, little is known about the interaction between drawing and dialogue in near-synchronous collaborative design. The paper reports the first stage of an investigation into the requirements for the design and development of interactive systems to support the learning of collaborative design activities. The aim of the study is to understand the collaborative design processes while sketching in a shared white board and audio conferencing media. Empirical data on design processes have been obtained from observation of seven sessions with groups of design students solving an interior space-planning problem of a lounge-diner in a virtual learning environment, Lyceum, an in-house software developed by the Open University to support its students in collaborative learning.

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Mesoscale convective systems (MCSs) are relatively rare events in the UK but, when they do occur, can be associated with weather that is considered extreme with respect to climatology (as indicated by the number of such events that have been analysed as case studies). These case studies usually associate UK MCSs with a synoptic environment known as the Spanish plume. Here a previously published 17 year climatology of UK MCS events is extended to the present day (from 1998 to 2008) and these events classified according to the synoptic environment in which they form. Three distinct synoptic environments have been identified, here termed the classical Spanish plume, modified Spanish plume, and European easterly plume. Detailed case studies of the two latter, newly defined, environments are presented. Composites produced for each environment further reveal the differences between them. The classical Spanish plume is associated with an eastward propagating baroclinic cyclone that evolves according to idealised life cycle 1. Conditional instability is released from a warm moist plume of air advected northeastwards from Iberia that is capped by warmer, but very dry air, from the Spanish plateau. The modified Spanish plume is associated with a slowly moving mature frontal system associated with a forward tilting trough (and possibly cut-off low) at 500 hPa that evolves according to idealised life cycle 2. As in the classical Spanish plume, conditional instability is released from a warm plume of air advected northwards from Iberia. The less frequent European easterly plume is associated with an omega block centred over Scandinavia at upper levels. Conditional instability is released from a warm plume of air advected westwards across northern continental Europe. Unlike the Spanish plume environments, the European easterly plume is not a warm sector phenomena associated with a baroclinic cyclone. However, in all environments the organisation of convection is associated with the interaction of an upper-level disturbance with a low-level region of warm advection.

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Endorsed by the Society of Light and Lighting, this practical book offers comprehensive guidance on how colour, light and contrast can be incorporated within buildings to enhance their usability. The book provides state-of-the-art, clear guidance as well as a valuable information source for busy professionals involved in the design or management of new and existing environments. The ways colour, light and contrast are used within built environments are critical in determining how people interact with the space, and how confident, safe, and secure they will feel when doing so. They also have a major influence on a person’s sense of well-being and their ability to use the environment independently and without undue effort. Understanding how to use colour and contrast and how they are influenced by both natural and artificial lighting is vital for all those involved in the design and management of the environments and spaces we all use. In recent years there has been a considerable amount of work undertaken to further our understanding of how colour, light and contrast affect emotion and sensory abilities, and how they can assist or hinder people in their everyday lives. Other publications consider these issues individually but The Colour, Light and Contrast Manual: designing and managing inclusive built environments draws knowledge and information together to produce a unique, comprehensive and informative guide to how the three elements can work together to improve the design and management of environments for us all.

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The aim of this study is to explore the environmental factors that determine plant Community distribution in northeast Algeria. This paper provides a quantitative analysis of the vegetation-environment relationships for a study site in the Cholt El Beida wetland, a RAMSAR site in Setif, Algeria. Sixty vegetation plots were sampled and analysed using TWINSPAN and Detrended Correspondence Analysis (DCA) in order to identify the principal vegetation communities and determine the environmental gradients associated with these. 127 species belonging to 41 families and 114 genera were recorded. Six of the recorded species were endemic representing 4.7% of the total species. The richest families were Compositae, Gramineae, Cruciferae and Chenopodiaceae. Therophytes and hemicryptophytes were the most frequent life forms. the Mediterranean floristic element is dominant and is represented by 39 species. The samples were classified into four main community types. The principal DCA axes represent gradients of soil salinity, moisture and anthropogenic pressure. The use of classification in combination with ordination techniques resulted in a good discrimination between plant communities and a greater understanding of controlling environmental factors. The methodology adopted can be employed for improving baseline information on plant community ecology and distribution in often critically endangered Mediterranean wetland areas. (C) 2008 Elsevier Ltd. All rights reserved.

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Pigeonpea is grown in wide range of cropping systems and environments, both in East Africa and internationally. An important feature of adaptation to these diverse systems and environments is the timing of flowering and maturity. Most traditional cultivars grown in Tanzania are medium to late flowering types (> 150 days), although extra-early flowering cultivars are now available. The aim of the present investigation was to measure biomass (BY) and seed (SY) yield of a set of phenologically diverse cultivars to determine their adaptation to contrasting environments in Tanzania. Ten cultivars, from extra-early (60 days) to late (> 180 days) flowering, were planted at six locations varying in mean temperature, photoperiod and rainfall. Days to flowering (DTF) and maturity, and above-ground BY and SY at maturity, were measured. A stress index (ETr:ETm ratio, 100 = no stress) was computed for each site. Rainfall and the stress index at the different sites varied from 322 to 1297 mm and 57 to 89, respectively. Among cultivars, DTF varied from 55 to 320 days, the stress index from 3 to 98, BY from 700 to 25,000 kg ha(-1), and SY from 0 to 4000 kg ha(-1). The highest yielding environment was at Selian, where mean temperatures were favourable (19 degrees C) and no stress occurred. At all sites there was an optimum DTF, which for SY varied from < 100 to 150 days. The best adapted cultivars were ICP 7035, ICPL 90094, Kat 50 and QP37, which were all medium flowering (c. 150 day) types. Extra-early cultivars such as ICPL 86005 also showed considerable potential, especially in short-season environments. (c) 2004 Elsevier B.V. All rights reserved.

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The objective of the present study was to determine the optimum plant density of four pigeonpea genotypes, representing early, medium and late maturing types, grown in five contrasting environments in Tanzania. ICPL 86005 (early), Kat 50/3 and QP 37 (medium) and Local (late) were grown at four plant densities (40 000-320 000 plants/ha) in irrigated and rainfed conditions at Ilonga and under rainfed conditions at Kibaha, Selian and Ismani. At maturity, total above-ground biomass and seed yield (SY) were measured. The highest yields were obtained in the irrigated experiment at Ilonga, where the medium/late genotypes produced 25 t biomass/ha and 5 center dot 6 t seed/ha. The lowest SY were at Kibaha, 0 58 to 1 center dot 76 t/ha, where a severe drought occurred. In nearly all cases the response to density was linear or asymptotic. The response of ICPL 86005 was significantly different from the other three genotypes. The optimum density for SY varied from 37 000 to 227 000 plants/ha in ICPL 86005, compared with 3000 to 101000 plants/ha in the medium/late genotypes. The highest optimum density was at Selian and Ismani and the lowest at Ilonga and Kibaha, where drought occurred. Optimum densities therefore varied greatly with genotype (duration) and environment, and this variation needs to be considered when planning trials.

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Mediterranean landscapes comprise a complex mosaic of different habitats that vary in the diversity of their floral communities, pollinator communities and pollination services. Using the Greek Island of Lesvos as a model system, we assess the biodiversity value of six common habitats and measure ecosystemic 'health' using pollen grain deposition in three core flowering plants as a measure of pollination services. Three fire-driven habitats were assessed: freshly burnt areas, fully regenerated pine forests and intermediate age scrub; in addition we examined oak woodlands, actively managed olive groves and groves that had been abandoned from agriculture. Oak woodlands, pine forests and managed olive groves had the highest diversity of bees. The habitat characteristics responsible for structuring bee communities were: floral diversity, floral abundance, nectar energy availability and the variety of nectar resources present. Pollination services in two of our plant species, which were pollinated by a limited sub-set of the pollinator community, indicated that pollination levels were highest in the burnt and mature pine habitats. The third species, which was open to all flower visitors, indicated that oak woodlands had the highest levels of pollination from generalist species. Pollination was always more effective in managed olive groves than in abandoned groves. However, the two most common species of bee, the honeybee and a bumblebee, were not the primary pollinators within these habitats. We conclude that the three habitats of greatest overall value for plant-pollinator communities and provision of the healthiest pollination services are pine forests, oak woodland and managed olive groves. We indicate how the highest value habitats may be maintained in a complex landscape to safeguard and enhance pollination function within these habitats and potentially in adjoining agricultural areas. (c) 2005 Elsevier Ltd. All rights reserved.

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1. The habitat components determining the structure of bee communities are well known when considering foraging resources; however, there is little data with respect to the role of nesting resources. 2. As a model system this study uses 21 diverse bee communities in a Mediterranean landscape comprising a variety of habitats regenerating after fire. The findings clearly demonstrate that a variety of nesting substrates and nest building materials have key roles in organising the composition of bee communities. 3. The availability of bare ground and potential nesting cavities were the two primary factors influencing the structure of the entire bee community, the composition of guilds, and also the relative abundance of the dominant species. Other nesting resources shown to be important include availability of steep and sloping ground, abundance of plant species providing pithy stems, and the occurrence of pre-existing burrows. 4. Nesting resource availability and guild structure varied markedly across habitats in different stages of post-fire regeneration; however, in all cases, nest sites and nesting resources were important determinants of bee community structure.