67 resultados para Index of losses


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Prior literature showed that Felder and Silverman learning styles model (FSLSM) was widely adopted to cater to individual styles of learners whether in traditional or Technology Enhanced Learning (TEL). In order to infer this model, the Index of Learning Styles (ILS) instrument was proposed. This research aims to analyse the soundness of this instrument in an Arabic sample. Data were integrated from different courses and years. A total of 259 engineering students participated voluntarily in the study. The reliability was analysed by applying internal construct reliability, inter-scale correlation, and total item correlation. The construct validity was also considered by running factor analysis. The overall results indicated that the reliability and validity of perception and input dimensions were moderately supported, whereas processing and understanding dimensions showed low internal-construct consistency and their items were weakly loaded in the associated constructs. Generally, the instrument needs further effort to improve its soundness. However, considering the consistency of the produced results of engineering students irrespective of cross-cultural differences, it can be adopted to diagnose learning styles.

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P>1. The development of sustainable, multi-functional agricultural systems involves reconciling the needs of agricultural production with the objectives for environmental protection, including biodiversity conservation. However, the definition of sustainability remains ambiguous and it has proven difficult to identify suitable indicators for monitoring progress towards, and the successful achievement of, sustainability. 2. In this study, we show that a trait-based approach can be used to assess the detrimental impacts of agricultural change to a broad range of taxonomic groupings and derive a standardised index of farmland biodiversity health, built around an objective of achieving stable or increasing populations in all species associated with agricultural landscapes. 3. To demonstrate its application, we assess the health of UK farmland biodiversity relative to this goal. Our results suggest that the populations of two-thirds of 333 plant and animal species assessed are unsustainable under current UK agricultural practices. 4. We then explore the potential benefits of an agri-environment scheme, Entry Level Stewardship (ELS), to farmland biodiversity in the UK under differing levels of risk mitigation delivery. We show that ELS has the potential to make a significant contribution to progress towards sustainability targets but that this potential is severely restricted by current patterns of scheme deployment. 5.Synthesis and applications: We have developed a cross-taxonomic sustainability index which can be used to assess both the current health of farmland biodiversity and the impacts of future agricultural changes relative to quantitative biodiversity targets. Although biodiversity conservation is just one of a number of factors that must be considered when defining sustainability, we believe our cross-taxonomic index has the potential to be a valuable tool for guiding the development of sustainable agricultural systems.

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In Mediterranean areas, conventional tillage increases soil organic matter losses, reduces soil quality, and contributes to climate change due to increased CO2 emissions. CO2 sequestration rates in soil may be enhanced by appropriate agricultural soil management and increasing soil organic matter content. This study analyzes the stratification ratio (SR) index of soil organic carbon (SOC), nitrogen (N) and C:N ratio under different management practices in an olive grove (OG) in Mediterranean areas (Andalusia, southern Spain). Management practices considered in this study are conventional tillage (CT) and no tillage (NT). In the first case, CT treatments included addition of alperujo (A) and olive leaves (L). A control plot with no addition of olive mill waste was considered (CP). In the second case, NT treatments included addition of chipped pruned branches (NT1) and chipped pruned branches and weeds (NT2). The SRs of SOC increased with depth for all treatments. The SR of SOC was always higher in NT compared to CT treatments, with the highest SR of SOC observed under NT2. The SR of N increased with depth in all cases, ranging between 0.89 (L-SR1) and 39.11 (L-SR3 and L-SR4).The SR of C:N ratio was characterized by low values, ranging from 0.08 (L-SR3) to 1.58 (NT1-SR2) and generally showing higher values in SR1 and SR2 compared to those obtained in SR3 and SR4. This study has evaluated several limitations to the SR index such as the fact that it is descriptive but does not analyze the behavior of the variable over time. In addition, basing the assessment of soil quality on a single variable could lead to an oversimplification of the assessment. Some of these limitations were experienced in the assessment of L, where SR1 of SOC was the lowest of the studied soils. In this case, the higher content in the second depth interval compared to the first was caused by the intrinsic characteristics of this soil's formation process rather than by degradation. Despite the limitations obtained SRs demonstrate that NT with the addition of organic material improves soil quality.

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We describe the use of bivariate 3d empirical orthogonal functions (EOFs) in characterising low frequency variability of the Atlantic thermohaline circulation (THC) in the Hadley Centre global climate model, HadCM3. We find that the leading two modes are well correlated with an index of the meridional overturning circulation (MOC) on decadal timescales, with the leading mode alone accounting for 54% of the decadal variance. Episodes of coherent oscillations in the sub-space of the leading EOFs are identified; these episodes are of great interest for the predictability of the THC, and could indicate the existence of different regimes of natural variability. The mechanism identified for the multi-decadal variability is an internal ocean mode, dominated by changes in convection in the Nordic Seas, which lead the changes in the MOC by a few years. Variations in salinity transports from the Arctic and from the North Atlantic are the main feedbacks which control the oscillation. This mode has a weak feedback onto the atmosphere and hence a surface climatic influence. Interestingly, some of these climate impacts lead the changes in the overturning. There are also similarities to observed multi-decadal climate variability.

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The East Asian Winter Monsoon (EAWM) and Siberian High (SH) are inherently related, based on prior studies of instrumental data available for recent decades (since 1958). Here we develop an extended instrumental EAWM index since 1871 that correlates significantly with the SH. These two indices show common modes of variation on the biennial (2-3 year) time scale. We also develop an index of the pressure gradient between the SH and the Aleutian Low, a gradient which critically impacts EAWM variability. This difference series, based on tree-ring reconstructions of the SH and the North Pacific Index (NPI) over the past 400 years, shows that the weakening of this gradient in recent decades has not been unusual in a long-term context. Correlations between the SH series and a tree-ring reconstruction of the El Nino-Southern Oscillation (ENSO) suggest a variable tropical-higher latitude teleconnection.

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Why are humans musical? Why do people in all cultures sing or play instruments? Why do we appear to have specialized neurological apparatus for hearing and interpreting music as distinct from other sounds? And how does our musicality relate to language and to our evolutionary history? Anthropologists and archaeologists have paid little attention to the origin of music and musicality — far less than for either language or ‘art’. While art has been seen as an index of cognitive complexity and language as an essential tool of communication, music has suffered from our perception that it is an epiphenomenal ‘leisure activity’, and archaeologically inaccessible to boot. Nothing could be further from the truth, according to Steven Mithen; music is integral to human social life, he argues, and we can investigate its ancestry with the same rich range of analyses — neurological, physiological, ethnographic, linguistic, ethological and even archaeological — which have been deployed to study language. In The Singing Neanderthals Steven Mithen poses these questions and proposes a bold hypothesis to answer them. Mithen argues that musicality is a fundamental part of being human, that this capacity is of great antiquity, and that a holistic protolanguage of musical emotive expression predates language and was an essential precursor to it. This is an argument with implications which extend far beyond the mere origins of music itself into the very motives of human origins. Any argument of such range is bound to attract discussion and critique; we here present commentaries by archaeologists Clive Gamble and Iain Morley and linguists Alison Wray and Maggie Tallerman, along with Mithen's response to them. Whether right or wrong, Mithen has raised fascinating and important issues. And it adds a great deal of charm to the time-honoured, perhaps shopworn image of the Neanderthals shambling ineffectively through the pages of Pleistocene prehistory to imagine them humming, crooning or belting out a cappella harmonies as they went.

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Heat-treated animal bone char (ABC) has not previously been evaluated for its potential as a phosphorus (P) fertilizer. ABC, Gafsa phosphate rock (GPR) and triple superphosphate fertilizer (TSP) were incubated in 12 soils. Dissolved-P was assessed by extraction with NaOH and bioavailability with the Olsen extractant. The rate of P dissolution from ABC was described almost equally well by the Elovich and Power equations. After 145 days, the fraction of P dissolved ranged from 0 to 73% and to 56% for ABC and GPR, respectively. The most important soil properties determining P dissolution from ABC were pH and P sorption. P dissolution was not significant at soil pH > 6.1 (ABC) and > 5 (GPR) and the lower the pH, the greater the Dissolved-P. Dissolved-P also correlated positively and significantly with inorganic P sorption, measured by the Freundlich isotherm and the P sorption index of Bache and Williams (1971). Soil pH and P sorption index could be combined in multiple regression equations that use readily measured soil properties to predict the potential for ABC dissolution in a soil. Dissolution of P from GPR correlated with soil pH and exchangeable acidity. In comparison with GPR, ABC was a better source of available P, assessed by Olsen-P. In most soils, ABC increased Olsen-P immediately after application, including soils of relatively high pH in which GPR was ineffective. ABC is a P fertilizer of solubility intermediate between GPR and TSP.

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A simplified general circulation model has been used to investigate the chain of causality whereby changes in tropospheric circulation and temperature are produced in response to stratospheric heating perturbations. Spinup ensemble experiments have been performed to examine the evolution of the tropospheric circulation in response to such perturbations. The primary aim of these experiments is to investigate the possible mechanisms whereby a tropospheric response to changing solar activity over the 11-yr solar cycle could be produced in response to heating of the equatorial lower stratosphere. This study therefore focuses on a stratospheric heating perturbation in which the heating is largest in the tropics. For comparison, experiments are also performed in which the stratosphere is heated uniformly at all latitudes and in which it is heated preferentially in the polar region. Thus, the mechanisms discussed have a wider relevance for the impact of stratospheric perturbations on the troposphere. The results demonstrate the importance of changing eddy momentum fluxes in driving the tropospheric response. This is confirmed by the lack of a similar response in a zonally symmetric model with fixed eddy forcing. Furthermore, it is apparent that feedback between the tropospheric eddy fluxes and tropospheric circulation changes is required to produce the full model response. The quasigeostrophic index of refraction is used to diagnose the cause of the changes in eddy behavior. It is demonstrated that the latitudinal extent of stratospheric heating is important in determining the direction of displacement of the tropospheric jet and storm track.

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Seventeen-month-old infants were presented with pairs of images, in silence or with the non-directive auditory stimulus 'look!'. The images had been chosen so that one image depicted an item whose name was known to the infant, and the other image depicted an image whose name was not known to the infant. Infants looked longer at images for which they had names than at images for which they did not have names, despite the absence of any referential input. The experiment controlled for the familiarity of the objects depicted: in each trial, image pairs presented to infants had previously been judged by caregivers to be of roughly equal familiarity. From a theoretical perspective, the results indicate that objects with names are of intrinsic interest to the infant. The possible causal direction for this linkage is discussed and it is concluded that the results are consistent with Whorfian linguistic determinism, although other construals are possible. From a methodological perspective, the results have implications for the use of preferential looking as an index of early word comprehension.

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We demonstrate that a new geomagnetic index of solar variability exhibits stronger correlations with atmospheric circulation variations than conventional measures. The circulation anomalies are particularly enhanced over the North Atlantic / Eurasian sector, where there are large changes in the occurrence of blocking and the winter mean surface temperature differs by several degrees between high- and low-solar terciles. The relationship is also simpler, being largely linear between high- and low-solar winters. While the circulation anomalies strongly resemble the North Atlantic Oscillation they also extend deeper into Eurasia, in a distinct signature which may be useful for the detection and attribution of observed changes and also the identification of dynamical mechanisms.

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A longitudinal study of sero-conversion of youngstock to the tick-borne pathogens Theileria parva, T mutans, Anaplasma marginale, Babesia bigemina and B. bovis was conducted over two years on smallholder dairy farms in Tanga region, Tanzania. There was evidence of maternal antibodies to all tick-borne pathogens in animals less than 18 weeks of age. Seroprevalence increased as expected with age in animals older than this but seroprevalence profiles underestimated the force of infection due to waning antibody levels between samplings. By the end of the 2-year study, less than 50% of study animals had seroconverted to each of the tick-borne pathogens investigated, consistent with the low levels of tick attachment observed on the study animals. Some associations between seroconversion to tick-borne pathogens, and counts of their known tick vectors on the animals, were identified as expected. However, some were not, suggesting that counts of some tick species may act as an index of rates of attachment of other vector species. Variation in acaricide treatment frequencies was not associated with variations in tick-borne pathogen seroprevalence suggesting that acaricides may be used more frequently than necessary on many farms. Most animals were zero-grazed, a management system associated with a significantly lower likelihood that animals seroconverted to any tick-borne pathogen exceptA. marginale. Seroprevalence varied locally with farm location (particularly for Babesia spp.) but was not well predicted by indices of ecological conditions. Our findings suggest that attempts to achieve a state of 'endemic stability' for tick-bome pathogens may be unreasonable on the smallholder dairy farms studied but reductions in the frequency of use of acaricides may be possible following prospective studies of effects on mortality and morbidity due to tick-bome pathogens. (c) 2005 Elsevier B.V. All rights reserved.

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The interactions among the multiple factors regulating predator-prey relationships make predation a more complex process than previously thought. The degree to which substandard individuals are captured disproportionately seems to be better a function of the difficulty of prey capture than of the hunting techniques (coursing vs. ambushing predators). That is, when the capture and killing of a prey species is easy, substandard individuals will be predated in proportion to their occurrence in the prey population. In the present study, we made use of eagle owls Bubo bubo and their main prey, the rabbit Oryctolagus cuniculus: (a) the brightness of the white tails of rabbits seems to be correlated with the physical condition of individuals, (b) by using the tails of predated rabbits as an index of individual condition, we found that eagle owls seem to prefer substandard individuals (characterized by duller tails), and (c) by using information from continuous radiotracking of 14 individuals, we suggest that the difficulty of rabbit capture could be low. Although the relative benefits of preying on substandard individuals should considerably decrease when a predator is attacking an easy prey, we hypothesise that the eagle owl preference for substandard individuals could be due to the easy detection of poor individuals by a visual cue, the brightness of the rabbit tail. Several elements allow us to believe that this form of visual communication between a prey and one of its main predators could be more widespread than previously thought. In fact: (a) visual signalling plays a relevant role in intraspecific communication in eagle owls and, consequently, visual signals could also play a role in interspecific interactions, and (b) empirical studies showed that signals may inform the predator that it has been perceived, or that the prey is in a sufficiently healthy state to elude the predator.

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Hunting foxes with hounds has been a countryside pursuit in Britain since the 17th Century, but its effect nationally on habitat management is little understood by the general public. A survey questionnaire was distributed to 163 mounted fox hunts of England and Wales to quantify their management practices in woodland and other habitat. Ninety-two hunts (56%), covering 75,514 km(2), returned details on woodland management motivated by the improvement of their sport. The management details were verified via on-site visits for a sample of 200 woodlands. Following verification, the area of woodlands containing the management was conservatively estimated at 24,053 (+/- 2241) ha, comprising 5.9% of woodland area within the whole of the area hunted by the 92 hunts. Management techniques included: tree planting, coppicing, felling, ride and perimeter management. A case study in five hunt countries in southern England examined, through the use of botanical survey and butterfly counts, the consequences of the hunt management on woodland ground flora and butterflies. Managed areas had, within the last 5 years, been coppiced and rides had been cleared. Vegetation cover in managed and unmanaged sites averaged 86% and 64%, respectively, and managed areas held on average 4 more plant species and a higher plant diversity than unmanaged areas (Shannon index of diversity: 2.25 vs. 1.95). Both the average number of butterfly species (2.2 vs. 0.3) and individuals counted (4.6 vs. 0.3) were higher in the managed than unmanaged sites.

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We have studied growth and estimated recruitment of massive coral colonies at three sites, Kaledupa, Hoga and Sampela, separated by about 1.5 km in the Wakatobi Marine National Park, S.E. Sulawesi, Indonesia. There was significantly higher species richness (P<0.05), coral cover (P<0.05) and rugosity (P<0.01) at Kaledupa than at Sampela. A model for coral reef growth has been developed based on a rational polynomial function, where dx/dt is an index of coral growth with time; W is the variable (for example, coral weight, coral length or coral area), up to the power of n in the numerator and m in the denominator; a1……an and b1…bm are constants. The values for n and m represent the degree of the polynomial, and can relate to the morphology of the coral. The model was used to simulate typical coral growth curves, and tested using published data obtained by weighing coral colonies underwater in reefs on the south-west coast of Curaçao [‘Neth. J. Sea Res. 10 (1976) 285’]. The model proved an accurate fit to the data, and parameters were obtained for a number of coral species. Surface area data was obtained on over 1200 massive corals at three different sites in the Wakatobi Marine National Park, S.E. Sulawesi, Indonesia. The year of an individual's recruitment was calculated from knowledge of the growth rate modified by application of the rational polynomial model. The estimated pattern of recruitment was variable, with little numbers of massive corals settling and growing before 1950 at the heavily used site, Sampela, relative to the reef site with little or no human use, Kaledupa, and the intermediate site, Hoga. There was a significantly greater sedimentation rate at Sampela than at either Kaledupa (P<0.0001) or Hoga (P<0.0005). The relative mean abundance of fish families present at the reef crests at the three sites, determined using digital video photography, did not correlate with sedimentation rates, underwater visibility or lack of large non-branching coral colonies. Radial growth rates of three genera of non-branching corals were significantly lower at Sampela than at Kaledupa or at Hoga, and there was a high correlation (r=0.89) between radial growth rates and underwater visibility. Porites spp. was the most abundant coral over all the sites and at all depths followed by Favites (P<0.04) and Favia spp. (P<0.03). Colony ages of Porites corals were significantly lower at the 5 m reef flat on the Sampela reef than at the same depth on both other reefs (P<0.005). At Sampela, only 2.8% of corals on the 5 m reef crest are of a size to have survived from before 1950. The Scleractinian coral community of Sampela is severely impacted by depositing sediments which can lead to the suffocation of corals, whilst also decreasing light penetration resulting in decreased growth and calcification rates. The net loss of material from Sampela, if not checked, could result in the loss of this protective barrier which would be to the detriment of the sublittoral sand flats and hence the Sampela village.

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The rheological properties of dough and gluten are important for end-use quality of flour but there is a lack of knowledge of the relationships between fundamental and empirical tests and how they relate to flour composition and gluten quality. Dough and gluten from six breadmaking wheat qualities were subjected to a range of rheological tests. Fundamental (small-deformation) rheological characterizations (dynamic oscillatory shear and creep recovery) were performed on gluten to avoid the nonlinear influence of the starch component, whereas large deformation tests were conducted on both dough and gluten. A number of variables from the various curves were considered and subjected to a principal component analysis (PCA) to get an overview of relationships between the various variables. The first component represented variability in protein quality, associated with elasticity and tenacity in large deformation (large positive loadings for resistance to extension and initial slope of dough and gluten extension curves recorded by the SMS/Kieffer dough and gluten extensibility rig, and the tenacity and strain hardening index of dough measured by the Dobraszczyk/Roberts dough inflation system), the elastic character of the hydrated gluten proteins (large positive loading for elastic modulus [G'], large negative loadings for tan delta and steady state compliance [J(e)(0)]), the presence of high molecular weight glutenin subunits (HMW-GS) 5+10 vs. 2+12, and a size distribution of glutenin polymers shifted toward the high-end range. The second principal component was associated with flour protein content. Certain rheological data were influenced by protein content in addition to protein quality (area under dough extension curves and dough inflation curves [W]). The approach made it possible to bridge the gap between fundamental rheological properties, empirical measurements of physical properties, protein composition, and size distribution. The interpretation of this study gave indications of the molecular basis for differences in breadmaking performance.