515 research outputs found

    The case for the return of the Parthenon Marbles

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    When we speak of the Parthenon, we are speaking about the birth of western civilisation, the birth of democracy and the symbol of Greece. The Marbles were and remain an integral part of the Parthenon as a monument to the glory of Classical Greece and the civilisation it gave to the world. Ownership might never be resolved but present intransigence attracts increasing diplomatic pressure. Surveys of British MPs reveal 66% support for the return of the Marbles. This paper will look at the legality of the ownership of the Marbles, the preservation of them and the current position. The Acropolis Museum allows Britain to show goodwill on this important cultural property issue

    Role of rock fragment cover on runoff generation and sediment yield in tilled vineyards.

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    The soil in conventional Mediterranean vineyards is an active and non-sustainable source of sediment and water. Lack of vegetation cover, small soil organic matter content and intense ploughing result in large rates of erosion in a millennia-old tillage system. There is a need for soil conservation strategies that enable sustainability of wine and grape production; therefore, it is essential to measure the rates and to investigate the processes and factors of soil erosion. This study evaluated factors that can reduce soil losses in traditional Mediterranean vineyards. The investigation was carried out with 96 rainfall simulation experiments at the pedon scale (0.24m2) to measure soil detachment and runoff yield under low frequency-high magnitude rainfall events of 1 hour at 55mmhour−1. On average, runoff was 40.6% of the rainfall, and the rate of soil erosion (i.e. amount of soil lost) was 71.5 g m−2. The key factor controlling erosion was the rock fragment cover. There was a clear decrease in soil losses with increased rock fragment cover on the soil surface, but an increase in surface runoff. The results of our study showed that rock fragments at the pedon scale reduced soil erosion in Mediterranean vineyards, but when a layer of embedded rock fragments developed, large rates of runoff were triggered

    Extended fault inversion with random slipmaps: a resolution test for the 2012 Mw 7.6 Nicoya, Costa Rica earthquake

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    Inversions for the full slip distribution of earthquakes provide detailed models of earthquake sources, but stability and non-uniqueness of the inversions is a major concern. The problem is underdetermined in any realistic setting, and significantly different slip distributions may translate to fairly similar seismograms. In such circumstances, inverting for a single best model may become overly dependent on the details of the procedure. Instead, we propose to perform extended fault inversion trough falsification. We generate a representative set of heterogeneous slipmaps, compute their forward predictions, and falsify inappropriate trial models that do not reproduce the data within a reasonable level of mismodelling. The remainder of surviving trial models forms our set of coequal solutions. The solution set may contain only members with similar slip distributions, or else uncover some fundamental ambiguity such as, for example, different patterns of main slip patches. For a feasibility study, we use teleseismic body wave recordings from the 2012 September 5 Nicoya, Costa Rica earthquake, although the inversion strategy can be applied to any type of seismic, geodetic or tsunami data for which we can handle the forward problem. We generate 10 000 pseudo-random, heterogeneous slip distributions assuming a von Karman autocorrelation function, keeping the rake angle, rupture velocity and slip velocity function fixed. The slip distribution of the 2012 Nicoya earthquake turns out to be relatively well constrained from 50 teleseismic waveforms. Two hundred fifty-two slip models with normalized L1-fit within 5 per cent from the global minimum from our solution set. They consistently show a single dominant slip patch around the hypocentre. Uncertainties are related to the details of the slip maximum, including the amount of peak slip (2–3.5 m), as well as the characteristics of peripheral slip below 1 m. Synthetic tests suggest that slip patterns such as Nicoya may be a fortunate case, while it may be more difficult to unambiguously reconstruct more distributed slip from teleseismic data

    The age of vines as a controlling factor of soil erosion processes in Mediterranean vineyards

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    Vineyards incur the highest soil and water losses among all Mediterranean agricultural fields. The state-of-the-art shows that soil erosion in vineyards has been primarily surveyed with topographical methods, soil erosion plots and rainfall simulations, but these techniques do not typically assess temporal changes in soil erosion. When vines are planted they are about 30 cm high × 1 cm diameter without leaves, the root system varies from 2 to over 40 cmdepth, and sometimes the lack of care used during transplanting can result in a field with highly erodible bare soils. This means that the time since vine plantation plays a key role in soil erosion rates, but very little attention has been paid to this by the scientific community. Thus, the main goal of this research was to estimate soil losses and assess soil erosion processes in two paired vineyard plantations of different ages. To achieve this goal, the improved stock unearthing method (ISUM) was applied to vineyards on colluvial parent materials with similar soil properties, topographical characteristics and landmanagements in the Les Alcusses Valley, southwestern Valencia province, Spain. Our findings suggested that the old vineyards showed lower erosion rates (−1.61 Mg ha−1 yr−1) than those that were recently planted (−8.16 Mg ha−1 yr−1). This is because of the damage that the plantation of the vines causes to soil. Tillage after planting (4 times per year) resulted in changes in the inter-rowand rowmorphology, promoting the development of a ridge underneath the vines that disconnected the inter-rows and reduced soil losseswith time. After the second year and until the 25th year after plantation, soil erosionwas approximately 1Mg ha−1 y−1,whichmeans thatmost of the erosion took place during the first two years after the plantation. Soil conservation strategies should be applied immediately after the plantationworks to allow sustainable grape production. That is when soil erosion most needs to be controlled

    Resolution of rupture directivity in weak events: 1-D versus 2-D source parameterizations for the 2011, M-w 4.6 and 5.2 Lorca earthquakes, Spain

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    Resolving robust source parameters of small-moderate magnitude earthquakes is still a challenge in seismology. We infer directivity from apparent source time functions (ASTFs) at regional distance and quantify the associated uncertainties. ASTFs are used for (i) modeling a propagating 1-D line source from the duration data and (ii) inverting the 2-D slip distribution from the full signals. Slip inversion is performed through a Popperian scheme, where random trial models are either falsified on account of large misfit, or else become members of the solution set of the inverse problem. We assess the resolution of rupture directivity representing centroid shifts from the solution set in a rose diagram. Using as example an event with well-studied rupture directivity, the 2011 Mw 5.2 Lorca (Spain) earthquake, 1-D and 2-D parameterizations yield similar estimates for direction (N213°E and N220°E, respectively) and asymmetry (67:33, 65:35) of rupture propagation, as well as rupture length (2.1 km, 2.7 km) and speed (3.5 km/s, 3.25 km/s). The high rupture velocity ≥ 90% vS may be held primarily responsible for the strong directivity effect of this earthquake. We show that inversion of apparent source durations is intrinsically unable to resolve highly asymmetric bilateral ruptures, while inversion of full ASTFs misses part of the signal's complexity, suggesting the presence of deconvolution artifacts. We extend the analysis to the Mw 4.6 foreshock of the Lorca earthquake, inferring similar directivity parameters and slip pattern as for the mainshock. The rupture toward SW of both earthquakes suggests that this direction could be inherent to the fault segment

    Characterisation of soluble and insoluble cell wall fractions from rye, wheat and hull-less barley endosperm flours

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    Within cereal endosperm flours, arabinoxylan and β-glucan molecules exist in either a soluble or an insoluble form. From a nutritional functionality viewpoint, soluble and insoluble forms offer different potential health advantages, so it is important to define both the features controlling solubilisation and the properties of each of the soluble and insoluble fractions. Factors known to affect the stability of arabinoxylan (AX) and β-glucan (BG) solutions include AX branching extent and type, and the ratio of cellotriose to cellotetraose units (DP3/DP4) in BG. Through studying the solubilisation of AX and BG from wheat, rye, and hull less barley endosperm under conditions that avoid the use of alkali or ethanol during the solubilisation process, we report (a) similar A/X ratios and fine structures for extracted soluble arabinoxylan and the corresponding insoluble AX within the cell walls for rye and wheat endosperm flours, (b) comparable DP3/DP4 ratios for soluble β-glucan, flour and insoluble β-glucan within the endosperm cell wall of hull less barley, and (c) evidence for enrichment of β-glucan at the exterior of residual insoluble cell walls. Therefore, the factors determining solubilisation of AX and BG from endosperm cell walls are different to those that determine the stability of aqueous solutions of the same polymers, and β-glucan may show limited solubilisation by being trapped within restraining cross-linked arabinoxylans in the cell wall

    The Contrasted Impact of Land Abandonment on Soil Erosion in Mediterranean Agriculture Fields

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    Abandonment of agricultural land results in on- and off-site consequences on soil system and there is a need to evaluate the impact on soil erosion to understand the ecosystem's changes. The aim of this research is to assess the impact of abandonment in four Mediterranean crops (vineyards, almonds, citrus and olives) on soil and water losses. To achieve this goal, 105 rainfall simulation experiments were conducted in agriculture fields (vineyards in Málaga, almonds in Murcia, and citrus and olive in Valencia) and on the paired abandoned plots. After abandonment, soil detachment decreased drastically in the olive and citrus orchards, meanwhile vineyards did not show any difference and almonds registered higher erosion rates after the abandonment. Terraced orchards of citrus and olives recovered a dense vegetation cover after the abandonment, meanwhile the sloping terrain of almonds and vineyards enhanced the development of crusts and rills and a negligible plant cover that resulted in high erosion rates. The contrasted response of the abandonment is discussed

    An economic, perception and biophysical approach to the use of oat straw as mulch in Mediterranean rainfed agriculture land

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    Soil erosion is a key cause of land degradation in agriculture lands; and it is a worldwide threat that must be solved by means of nature-based strategies to be able to achieve sustainability. The use of mulches can be a solution, but there is a lack of information on long-term effects of the use of straw. Furthermore, little is known about the perception of farmers and the economic cost on the implantation of straw as a conservation measure. Eight paired plots were selected in Sierra de Enguera on an agriculture field to determine the effect of straw cover on soil erosion. Four plots were tilled three times per year (Control) and four plots were not ploughed and 0.125 kg m−2 y−1 of oat straw cover was applied yearly (Straw). The plots were established in 2002, and runoff and sediment was continuously collected after each rainfall event from 2004 till 2014 when the two managements were applied. The results show an immediate effect of the straw mulches as in these plots the runoff (from 7.7 till 5.9%) and soil erosion (from 47 till 26 Mg ha−1 y−1) was reduced already in the first year. The combined effect of the use of straw yearly and the no-tillage strategy resulted in a reduction of the sediment yield, and 11 years later soil erosion rates were two orders of magnitude lower than in the control plot. However, the perception of the farmers on the use of straw is very negative and they claim that subsidies need to be implemented, as the cost of straw mulch is 1.9 times more expensive than traditional tillage

    Experimental energy performance assessment of a solar desiccant cooling system in Southern Europe climates

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    Solar desiccant cooling systems, SDEC, could be an effective alternative to conventional cooling systems, which mainly depend on electrical energy. The main objective of this work was to determine experimentally the seasonal coefficient of performance, SCOP, of a SDEC system composed of a desiccant wheel, an indirect evaporative cooler and a thermal solar system, to control indoor conditions in a research lab room. The dependence of coefficient of performance on outdoor air conditions and percentage of renewable energy used by the SDEC system were also analysed. Experimental tests were carried out for six weeks during spring and summer seasons in Martos, Spain. The experimental results showed that the SDEC system independently adjusted the temperature and humidity of the supply air. 75% of the energy consumed by this air handling system comes from renewable sources. A seasonal coefficient of performance of the SDEC system of 2 was obtained for the period analysed. It is shown that the higher the outdoor temperature, the higher instantaneous COPs is. These results suggest that the use of SDEC systems in hot climates, such as southern European climates, could contribute to achieve the EU's energy goals within the frame of Nearly Zero Energy Buildings
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