942 resultados para Turf and dirt tracks
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Traction is recognised as an important component of the overall playability and safety of a sportsfield. It relates to the "grip", or footing, provided through an athlete's shoe when in contact with the surface, and is normally measured by the torque generated when a weighted studded disc apparatus is dropped onto the turf and twisted manually. This paper describes the development of an automated traction tester, which mechanises the dropping and twisting of the weighted studded disc. By standardising these operational stages, more repeatable and reliable results can be expected than from the original hand-operated design where positioning of the disc and speed of rotation are controlled manually and so can vary from one measurement to the next. As well as measuring the maximum torque reached during rotation of the studded disc, the automated traction tester generates a profile of torque showing changes over time and calculates the angle through which the studded disc moved before reaching maximum torque. These aspects are now covered by a utility patent (PAT/AU/2004270767). Use of the automated traction tester is illustrated by comparative data for a range of warm-season turfgrasses, by comparisons of traction under different surface conditions generated by wear on Cynodon dactylon cultivars, and by the effects of environment, management and playing patterns on traction across a multi-use sports stadium.
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Two sympatric populations of “transient” (mammal-eating) killer whales were photo-identified over 27 years (1984–2010) in Prince William Sound and Kenai Fjords, coastal waters of the northern Gulf of Alaska (GOA). A total of 88 individuals were identified during 203 encounters with “AT1” transients (22 individuals) and 91 encounters with “GOA” transients (66 individuals). The median number of individuals identified annually was similar for both populations (AT1=7; GOA=8), but mark-recapture estimates showed the AT1 whales to have much higher fidelity to the study area, whereas the GOA whales had a higher exchange of individuals. Apparent survival estimates were generally high for both populations, but there was a significant reduction in the survival of AT1 transients after the Exxon Valdez oil spill in 1989, with an abrupt decline in estimated abundance from a high of 22 in 1989 to a low of seven whales at the end of 2010. There was no detectable decline in GOA population abundance or survival over the same period, but abundance ranged from just 6 to 18 whales annually. Resighting data from adjacent coastal waters and movement tracks from satellite tags further indicated that the GOA whales are part of a larger population with a more extensive range, whereas AT1 whales are resident to the study area.
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The position and structure of the North Atlantic Subtropical Front is studied using Lagrangian flow tracks and remote sensing (AVHRR imagery: TOPEX/POSEIDON altimetry: SeaWiFS) in a broad region ( similar to 31 degree to similar to 36 degree N) of marked gradient of dynamic height (Azores Current) that extends from the Mid-Atlantic Ridge (MAR), near similar to 40 degree W, to the Eastern Boundary ( similar to 10 degree W). Drogued Argos buoy and ALACE tracks are superposed on infrared satellite images in the Subtropical Front region. Cold (cyclonic) structures, called storms, and warm (anticyclonic) structures of 100-300 km in size can be found on the south side of the Subtropical Front outcrop, which has a temperature contrast of about 1 degree C that can be followed for similar to 2500 km near 35 degree N. Warmer water adjacent to the outcrop is flowing eastward (Azores Current) but some warm water is returned westward about 300 km to the south (southern Counterflow). Estimates of horizontal diffusion in a Storm (D=2.2t10 super(2) m super(2) s super(-1)) and in the Subtropical Front region near 200 m depth (D sub(x)=1.3t10 super(4) m super(2) s super(-1), D sub(y)=2.6t10 super(3) m super(2) s super(-1)) are made from the Lagrangian tracks. Altimeter and in situ measurements show that Storms track westwards. Storms are separated by about 510 km and move westward at 2.7 km d super(-1). Remote sensing reveals that some initial structures start evolving as far east as 23 degree W but are more organized near 29 degree W and therefore Storms are about 1 year old when they reach the MAR (having travelled a distance of 1000 km). Structure and seasonality in SeaWiFS data in the region is examined.
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For the last twenty years, the consumption of poultry meat has boomed in Vietnam as in the rest of the developing world. Capital-intensive production has grown rapidly to satisfy this demand. Based on a few numbers of genetically uniform strains, these systems threaten biodiversity. In Vietnam, both rural and urban households still keep indigenous chickens as part of a diversified livelihood portfolio. In line with the national in situ conservation strategy, this study approached the context of local poultry keeping in two rural and one suburban districts of Northern Vietnam. It aimed at understanding households’ willingness, constraints and opportunities for practice improvement, including breeds’ management. As the Ri chicken constitutes the large majority of backyard flocks, two particular objectives of this study are the morpho-biometric characterisation of phenotypic diversity among individuals classified as Ri by farmers and an assessment of their productive potential. Chicken was found to hold a different place in livelihoods of the three districts with consequences on the management of genetic resources. The most favourable conditions for improvement of the Ri breed was found in the rural district of Luong-Son, due to market integration. In the more remote district of Ky-Son, living standards were lower and much would be gained from Ri conservation. Ri breed was the most threatened in the suburban Gia-Lam district, where poultry was a minor side-activity, lacking incentive for genetic management. From motives and constraints, tracks about breeding goals are suggested. Further considerations about conservation, improvement, market integration and livelihoods are proposed.
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A high-resolution textural study has been made of laminated and banded estuarine silts exposed intertidally at representative localities and horizons in the Holocene deposits of the Severn Estuary Levels. The laminae, on a submillimetre to millimetre scale, are sharp-based, graded couplets formed of a lower silty part overlain by a finer-textured clayey element. The centimetre- to decimetre-scale banding is formed of laminae in alternating, gradually intergrading sets of relatively coarse and relative fine-grained examples. At outcrop in the field, the banding is recognizable because the coarse sets prove to be recessive to varying degrees under the influence of weathering and current action. Independent evidence at two localities points toward an annual origin for the banding; at a third it arose during part of what appears to have been a relatively short period. Quantified physical arguments suggest that the textural banding is a response of suspended fine sediment to marked seasonal changes in sea temperature and windiness. The banded silts occur in four distinct stratigraphical contexts and record high deposition rates (order 0.01-0.1 m/yr). Because physical factors determine their textures, the silts potentially afford insights in all contexts into aspects of changing Holocene climatic conditions. In one context, the thickness of the bands points to high (order 0.01-0.1 m/yr) but comparatively short-lived (order 10s-100s yrs) rates of relative water-level rise. In the others, however, the banding has no implications for sea-level behaviour, and simply records gross environmental disequilibrium, for example, the recovery of mudflats/marshes after an erosional episode. Similarly, because on account of their rapid accumulation the banded silts preserve animal and human tracks and trackways especially well, they provide an archive of animal and human behaviour in the area during the Holocene.
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Climate change is expected to increase winter rainfall and flooding in many extratropical regions as evaporation and precipitation rates increase, storms become more intense and storm tracks move polewards. Here, we show how changes in stratospheric circulation could play a significant role in future climate change in the extratropics through an additional shift in the tropospheric circulation. This shift in the circulation alters climate change in regional winter rainfall by an amount large enough to significantly alter regional climate change projections. The changes are consistent with changes in stratospheric winds inducing a change in the baroclinic eddy growth rate across the depth of the troposphere. A change in mean wind structure and an equatorward shift of the tropospheric storm tracks relative to models with poor stratospheric resolution allows coupling with surface climate. Using the Atlantic storm track as an example, we show how this can double the predicted increase in extreme winter rainfall over Western and Central Europe compared to other current climate projections
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The occurrence of wind storms in Central Europe is investigated with respect to large-scale atmospheric flow and local wind speeds in the investigation area. Two different methods of storm identification are applied for Central Europe as the target region: one based on characteristics of large-scale flow (circulation weather types, CWT) and the other on the occurrence of extreme wind speeds. The identified events are examined with respect to the NAO phases and CWTs under which they occur. Pressure patterns, wind speeds and cyclone tracks are investigated for storms assigned to different CWTs. Investigations are based on ERA40 reanalysis data. It is shown that about 80% of the storm days in Central Europe are connected with westerly flow and that Central European storm events primarily occur during a moderately positive NAO phase, while strongly positive NAO phases (6.4% of all days) account for more than 20% of the storms. A storm occurs over Central Europe during about 10% of the days with a strong positive NAO index. The most frequent pathway of cyclone systems associated with storms over Central Europe leads from the North Atlantic over the British Isles, North Sea and southern Scandinavia into the Baltic Sea. The mean intensity of the systems typically reaches its maximum near the British Isles. Differences between the characteristics for storms identified from the CWT identification procedure (gale days, based on MSLP fields) and those from extreme winds at Central European grid points are small, even though only 70% of the storm days agree. While most storms occur during westerly flow situations, specific characteristics of storms during the other CWTs are also considered. Copyright © 2009 Royal Meteorological Society
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Insect diversity may be declining even more rapidly than in plants and vertebrates, particularly in areas where indigenous habitats are replaced by an anthropogenic one. The most common component of anthropogenic greenspace is the ornamental lawn. Intensively managed and offering limited habitat opportunities for both plants and insects, lawns are biodiversity poor and ecologically insensitive. An alternative lawn format that positively influences biodiversity and reduces management requirements would be a useful tool in eco-friendly urban greenspace management. In investigating the potential for a forb-only alternative to the grass lawn we sampled both trial grass-free lawn formats and turf lawns to identify any influence that lawn composition and grass-free lawn specific mowing regimes might have on the abundance and diversity of insect families. In addition to the mowing regimes, both the composition and origin of lawn flora were found to significantly influence insect abundance and diversity and these factors rarely interacted. Native-only and mixed origin grass-free lawns hosted greater numbers of adult insects than found in turf and an equivalent diversity of insect families, however the mowing regime applied was distinct from traditional turf lawn management by being substantially less intensive and our results suggest that there is the potential for even greater abundance and diversity via the grass-free format that may offer additional resources to insectivorous garden species such as birds. When the composition of grass-free lawns included native forbs the diversity of insect families was found be sufficiently different from turf lawns to form distinct assemblages and in so doing contribute to beta diversity within urban greenspace. In sum, grass-free lawns may be a useful and aesthetically appropriate tool for adding value to the generally biodiversity poor urban lawnscape.
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We study the effect of clouds on the atmospheric circulation response to CO2 quadrupling in an aquaplanet model with a slab-ocean lower boundary. The cloud effect is isolated by locking the clouds to either the control or 4xCO2 state in the shortwave (SW) or longwave (LW) radiation schemes. In our model, cloud-radiative changes explain more than half of the total poleward expansion of the Hadley cells, midlatitude jets, and storm tracks under CO2 quadrupling, even though they cause only one-fourth of the total global-mean surface warming. The effect of clouds on circulation results mainly from the SW cloud-radiative changes, which strongly enhance the Equator-to-pole temperature gradient at all levels in the troposphere, favoring stronger and poleward-shifted midlatitude eddies. By contrast, quadrupling CO2 while holding the clouds fixed causes strong polar amplification and weakened midlatitude baroclinicity at lower levels, yielding only a small poleward expansion of the circulation. Our results show that (a) the atmospheric circulation responds sensitively to cloud-driven changes in meridional and vertical temperature distribution, and (b) the spatial structure of cloud feedbacks likely plays a dominant role in the circulation response to greenhouse gas forcing. While the magnitude and spatial structure of the cloud feedback are expected to be highly model-dependent, an analysis of 4xCO2 simulations of CMIP5 models shows that the SW cloud feedback likely forces a poleward expansion of the tropospheric circulation in most climate models.
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TIGGE was a major component of the THORPEX (The Observing System Research and Predictability Experiment) research program, whose aim is to accelerate improvements in forecasting high-impact weather. By providing ensemble prediction data from leading operational forecast centers, TIGGE has enhanced collaboration between the research and operational meteorological communities and enabled research studies on a wide range of topics. The paper covers the objective evaluation of the TIGGE data. For a range of forecast parameters, it is shown to be beneficial to combine ensembles from several data providers in a Multi-model Grand Ensemble. Alternative methods to correct systematic errors, including the use of reforecast data, are also discussed. TIGGE data have been used for a range of research studies on predictability and dynamical processes. Tropical cyclones are the most destructive weather systems in the world, and are a focus of multi-model ensemble research. Their extra-tropical transition also has a major impact on skill of mid-latitude forecasts. We also review how TIGGE has added to our understanding of the dynamics of extra-tropical cyclones and storm tracks. Although TIGGE is a research project, it has proved invaluable for the development of products for future operational forecasting. Examples include the forecasting of tropical cyclone tracks, heavy rainfall, strong winds, and flood prediction through coupling hydrological models to ensembles. Finally the paper considers the legacy of TIGGE. We discuss the priorities and key issues in predictability and ensemble forecasting, including the new opportunities of convective-scale ensembles, links with ensemble data assimilation methods, and extension of the range of useful forecast skill.
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Intense extra-tropical cyclones are often associated with strong winds, heavy precipitation and socio-economic impacts. Over southwestern Europe, such storms occur less often, but still cause high economic losses. We characterise the largescale atmospheric conditions and cyclone tracks during the top-100 potential losses over Iberia associated with wind events. Based on 65 years of reanalysis data,events are classified into four groups: (i) cyclone tracks crossing over Iberia on the event day (“Iberia”), (ii) cyclones crossing further north, typically southwest of the British Isles (“North”), (iii) cyclones crossing southwest to northeast near the northwest tip of Iberia (“West”), and (iv) so called “Hybrids”, characterised by a strong pressure gradient over Iberia due to the juxtaposition of low and high pressure centres. Generally, “Iberia” events are the most frequent (31% to 45% for top-100 vs.top-20), while “West” events are rare (10% to 12%). 70% of the events were primarily associated with a cyclone. Multi-decadal variability in the number of events is identified. While the peak in recent years is quite prominent, other comparably stormy periods occurred in the 1960s and 1980s. This study documents that damaging wind storms over Iberia are not rare events, and their frequency of occurrence undergoes strong multi-decadal variability.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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[EN]A range of factors may affect the composition and abundance of macroalgae on subtidal rocky reefs. We experimentally determined the interactive effect of the occurrence of the long-spine sea urchin, Diadema antillarum, depth and sedimentation levels on macroalgal assemblage structure on eastern Atlantic rocky reefs. Specifically, we manipulated sea urchin densities (removal of all individuals vs. untouched controls at natural densities) on rocky reefs devoid of erect vegetation, and predicted (1) that removal of sea urchins would differently affect macroalgal assemblage structure between deep (16-18 m) and shallow (8-9 m) reef strata, and that (2) the effect of sea urchin removal on macroalgae would be altered under different scenarios of sedimentation (ambient vs. enhanced). Experimental circular plots (2 m in diameter) were set up at 3 locations at Gran Canaria (Canarian Archipelago), and were maintained and monitored every 4 wk for 1 y. At the end of the experimental period, the structure of the algal assemblages differed between urchin treatments and depth strata, with a larger cover of turf and bushlike algae where urchins were removed and at the shallow reef stratum. More important, differences in algal assemblage structure between urchin treatments were irrespective of sedimentation levels, but shifted from the shallow to the deep stratum. This interactive effect was, in turn, observed for bushlike algae, as a result of a larger magnitude of response (i.e., larger cover) in the shallow stratum relative to the deep stratum, but was not detected for either turf or crustose coralline algae. These results highlight the importance of sorne physical conditions (here, differences in depth) to interact with biotic processes (here, urchin abundance) to create patterns in the organization of subtidal and benthic assemblages
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No tenemos conocimiento de ninguna red de caminos prerromanos que sirvieran como base de una posible malla territorial de España. Sin embargo, una sociedad prerromana sin caminos, por muy fragmentada y aislada que fuera, es algo improbable y mucho menos en la Edad del Hierro. Por eso en época prerromana existían infinidad de caminos, muchos de los cuales hoy han desaparecido y otros han sobrevivido, casi siempre con sus recorridos mejorados. Los pueblos prerromanos aprovecharon vías naturales de comunicación (ríos, vados, valles, puertos naturales, llanuras, etc.) para tender sus caminos. En sus orígenes no siguieron pautas concretas, si no que los caminos se originaban por el tránsito (de personas, ganados, mercancías, etc.) de un lugar a otro. De este modo la red viaria prerromana era caótica y anárquica: todo camino tenía numerosos ramales y variantes, según las necesidades. Pendientes excesivas, anchuras variables, etc., en decir eran vías espontáneas, surgidas sin ninguna planificación aparente. Los recorridos en general eran cortos, aunque algunas investigaciones actuales están demostrando que algunas de las cañadas ganaderas más importantes, como la Galiana, y de largo recorrido, eran de origen prerromano. En el caso de la península Ibérica, y más concretamente en el caso de la Meseta, el territorio estaba fragmentado en diversos pueblos y tribus, agrupados según criterios étnicos y culturales y con contactos con los pueblos próximos que motivan la preponderancia de caminos de recorrido cortos. Solo la necesidad de llevar los rebaños (de cabras y ovejas sobre todo) desde las serranías en verano a las llanuras en invierno, motivaría viajes más largos en los que algunas cañadas ganaderas jugarían un papel más importante. Con la llegada de los romanaos, se implantó en Hispania una densa red viaria, cuya construcción se prolongó durante toda la dominación romana, siendo reparadas muchas calzadas y vías en varias ocasiones. En época romana la red caminera era variada y estaba constituida por “las calzadas” que comunicaban puntos importantes, eran muy transitadas, de ahí que la administración romana las mantuviera siempre en buen estado, para asegurar el intercambio comercial entre zonas distintas, cobro de impuestos, etc. “Los caminos de tierra (viae terrenae)” que además de las calzadas, que podemos asemejar a las actuales carreteras de primer y segundo orden, constituían la infinidad de caminos locales y comarcales. Los trazados se realizaron unos en época romana, y otros muchos apoyándose en los caminos de la época prerromana, éstas vías no se realizaban buscando el recorrido más corto entre dos puntos, ni tampoco el más cómodo y con un firme estructural de menor importancia que en las calzadas. Tampoco estaban hechos para un tipo concreto de transporte, por lo que nos encontraríamos algunos que por su anchura permitían el paso de carros, y otros que sólo permitirían el paso a pie, a caballo o en burro. Solían ser, como hemos indicado, caminos de tierra con acabados en zahorras y recorridos en su mayor parte cortos y medianos. Dentro de la malla territorial de España las calzadas constituirían las denominadas “viae publicae” que constituían la red principal y esqueleto vertebrador de Hispania. Los caminos de tierra constituirían los denominados “actus” caminos de carácter regional que configuraban la mayor parte de la red. Muchas de las “viae publicae” y de los “actus” tendrían su origen en las “viae militares” que habrían sido los primeros construidos, apoyándose en muchas ocasiones en los caminos prerromanos, por los romanos para realizar la conquista de Hispania y que luego con la Paz romana habrían tenido otro tipo de uso. Dentro de estas “viae militares” tuvieron una importancia relevancia aquellas que se utilizaron en la conquista de la Celtiberia, culminada con la caída de Numantia. Dentro de ellas tuvo una importancia fundamental la vía romana del río Alhama, objeto de esta Tesis, que facilitaría el desplazamiento de los ejércitos romanos desde Graccurris, primera ciudad romana fundada en el Ebro medio, hasta Numantia. Desde la época Augusta, la vía romana del río Alhama, pasaría a formar parte de los denominados “actus” formando parte de la malla territorial de la Península Ibérica como vía de comunicación entre la Meseta y el Ebro Medio. We do not have knowledge of any network of ways prerromanos that were serving as base of a possible territorial mesh of Spain. Nevertheless, a company prerromana without ways, for very fragmented and isolated that was, is something improbable and great less in the Age of the Iron. Because of it in epoch prerromana existed infinity of ways, many of which today have disappeared and others have survived, almost always with his improved tours. The people prerromanos took advantage of natural routes of communication (rivers, fords, valleys, natural ports, plains, etc.) to stretch his ways. In his origins concrete guidelines did not continue, if not that the ways were originating for the traffic (of persons, cattle, goods, etc.) to and from. Thus the network viaria prerromana was chaotic and anarchic: all way had numerous branches and variants, according to the needs. Excessive slopes, variable widths, etc., in saying were spontaneous routes arisen without no apparent planning. The tours in general were short, though some current investigations are demonstrating that some of the most important cattle glens, as the Galiana, and of crossed length, were of origin prerromano. In case of the Iberian Peninsula, and more concretely in case of the Plateau, the territory was fragmented in diverse peoples and tribes, grouped according to ethnic and cultural criteria and with contacts with the near peoples that motivate the prevalence of short ways of tour. Only the need to take the flocks (of goats and sheeps especially) from the mountainous countries in summer to the plains in winter, would motivate longer trips in which some cattle glens would play a more important paper. With the arrival of the romanos, a dense network was implanted in Roman Spain viaria, whose construction extended during the whole Roman domination, being repaired many causeways and routes in several occasions. In Roman epoch the pertaining to roads network was changed and constituted by " the causeways " that were communicating important points, they were very travelled, of there that the Roman administration was supporting always in good condition, to assure the commercial exchange between different zones, collection of taxes, etc. "The dirt tracks (viae terrenae)" that besides the causeways, which we can make alike to the current roads of the first and second order, were constituting the infinity of local and regional ways. The tracings were realized some in Roman epoch, and great others resting on the ways of the epoch prerromana, these routes were not realized looking for the most short tour neither between points, two nor neither most comfortable and with a structural road surface of minor importance that in the causeways. They were not also done for a concrete type of transport, for what some of us would think that for his width they were allowing the step of cars, and others that only would allow the step afoot, astride or in donkey. They were in the habit of being, since we have indicated, dirt tracks with ended in zahorras and tours in his most short and medium. Inside the territorial mesh of Spain the causeways would constitute the called ones "viae publicae" that constituted the principal network and skeleton vertebrador of Roman Spain. The dirt tracks would constitute the "actus” called ways of regional character that were forming most of the network. Many of "viae publicae" and of the "actus" they would have his origin in " viae military" that would have been the first ones constructed, resting on many occasions on the ways prerromanos, for the Romans to realize the conquest of Roman Spain and that then with the Roman Peace they would have had another type of use. Inside these "viae military" had an importance relevancy those that were in use in the conquest of the Celtiberia, reached with Numantia's fall. Inside them a fundamental importance had the Roman route of the river Alhama, object of this Thesis, which would facilitate the displacement of the Roman armies from Graccurris, the first Roman city been founded on the average Ebro, up to Numantia. From the August epoch, the Roman route of the river Alhama, would happen to form a part of the "actus” forming a part of the territorial mesh of the Iberian Peninsula as road link between the Plateau and the Average Ebro.