956 resultados para SECULAR PERTURBATIONS


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This paper proposes a calculation method to determine power system response during small load perturbations or minor disturbances. The method establishes the initial value of active power transient using traditional reduction technique on admittance matrix, which incorporates voltage variations in the determination. The method examines active power distribution among generators when several loads simultaneously change, and verifies that the superposition principle is applicable for this scenario. The theoretical derivation provided in the paper is validated by numerical simulations using a 3-generator 9-bus benchmark model. The results indicate that the inclusion of voltage variation renders an independent and precise measure of active power response during transient conditions.

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Background: Durkheim’s seminal historical study demonstrated that religious affiliation reduces suicide risk, but it is unclear whether this protective effect persists in modern, more secular societies.

Aims: To examine suicide risk according to Christian religious affiliation and by inference to examine underlying mechanisms for suicide risk. If church attendance is important, risk should be lowest for Roman Catholics and highest for those with no religion; if religiosity is important, then ‘conservative’ Christians should fare best.

Method: A 9-year study followed 1 106 104 people aged 16–74 years at the 2001 UK census, using Cox proportional hazards models adjusted for census-based cohort attributes.

Results: In fully adjusted models analysing 1119 cases of suicide, Roman Catholics, Protestants and those professing no religion recorded similar risks. The risk associated with conservative Christians was lower than that for Catholics (HR = 0.71, 95% CI 0.52–0.97).

Conclusions: The relationship between religious affiliation and suicide established by Durkheim may not pertain in societies where suicide rates are highest at younger ages. Risks are similar for those with and without a religious affiliation, and Catholics (who traditionally are characterised by higher levels of church attendance) do not demonstrate lower risk of suicide. However, religious affiliation is a poor measure of religiosity, except for a small group of conservative Christians, although their lower risk of suicide may be attributable to factors such as lower risk behaviour and alcohol consumption.

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Natural ecosystems are increasingly exposed to multiple anthropogenic stressors, including land-use change, deforestation, agricultural intensification, and urbanisation, all of which have led to widespread habitat fragmentation, which is also likely to be amplified further by predicted climate change. The potential interactive effects of these different stressors cannot be determined by studying each in isolation, although such synergies have been largely ignored in ecological field studies to date. Here, we use a model system of naturally fragmented islands in a braided river network, which is exposed to periodic inundation, to investigate the interactive effects of habitat isolation and flood disturbance. Food web structure was similar across the islands during periods of hydrological stability, but several key properties were altered in the aftermath of flood disturbance, based on distance of the islands from the regional source pool of species: taxon richness and mean food chain length declined with habitat isolation after flooding, while the proportion of basal species increased. Greater species turnover through time reflected the slower process of re-colonisation on the more distant islands following disturbance. Increased variability of several food web properties over a 1-year period highlighted the reduced temporal stability of isolated habitat fragments. Many of these effects reflected the differential successes of predator and prey species at re-colonising the islands: even though larger, more mobile consumers may reach the more distant islands first, they cannot establish populations until the lower trophic levels have successfully reassembled. These results highlight the susceptibility of fragmented ecosystems to environmental perturbations. © 2013 Elsevier Ltd.

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According to the axiomatic literature on consensus methods, the best collective choice by one method of preference aggregation can easily be the worst by another. Are award committees, electorates, managers, online retailers, and web-based recommender systems stuck with an impossibility of rational preference aggregation? We investigate this social choice conundrum for seven social choice methods: Condorcet, Borda, Plurality, Antiplurality, the Single Transferable Vote, Coombs, and Plurality Runoff. We rely on Monte Carlo simulations for theoretical results and on twelve ballot datasets from American Psychological Association (APA) presidential elections for empirical results. Each of these elections provides partial rankings of five candidates from about 13,000 to about 20,000 voters. APA preferences are neither domain-restricted nor generated by an Impartial Culture. We find virtually no trace of a Condorcet paradox. In direct contrast with the classical social choice conundrum, competing consensus methods agree remarkably well, especially on the overall best and worst options. The agreement is also robust under perturbations of the preference prole via resampling, even in relatively small pseudosamples. We also explore prescriptive implications of our findings.

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This monograph demonstrates that aesthetic and ontological anxieties continue to find diverse expression within the contrived textual artifice of the bucolic space. Drawing upon expansive definitions of the Hispanic literary Baroque, (Beverley, 1980, 2008, Echevarría 1993, Ross 1993, Chemris 2008 , Egido 2009 ) the study analyses the pastoral verse of representative poets of the period to demonstrate that they re-enter an Arcadia that has been defamiliarized but is nonetheless inexorably connected to the classical origins of the mode. Pastoral, in common with other literary forms, is subject to a process of re-evaluation which was latent in its classical legacy. Within the intricacies of this literary construct, surface artistry sustains an effect of artless innocence that is vibrantly contested across the secular, sacred, parodic and colonial text.

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In this paper, we re-examine two important aspects of the dynamics of relative primary commodity prices, namely the secular trend and the short run volatility. To do so, we employ 25 series, some of them starting as far back as 1650 and powerful panel data stationarity tests that allow for endogenous multiple structural breaks. Results show that all the series are stationary after allowing for endogenous multiple breaks. Test results on the Prebisch–Singer hypothesis, which states that relative commodity prices follow a downward secular trend, are mixed but with a majority of series showing negative trends. We also make a first attempt at identifying the potential drivers of the structural breaks. We end by investigating the dynamics of the volatility of the 25 relative primary commodity prices also allowing for endogenous multiple breaks. We describe the often time-varying volatility in commodity prices and show that it has increased in recent years.

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Mortality models used for forecasting are predominantly based on the statistical properties of time series and do not generally incorporate an understanding of the forces driving secular trends. This paper addresses three research questions: Can the factors found in stochastic mortality-forecasting models be associated with real-world trends in health-related variables? Does inclusion of health-related factors in models improve forecasts? Do resulting models give better forecasts than existing stochastic mortality models? We consider whether the space spanned by the latent factor structure in mortality data can be adequately described by developments in gross domestic product, health expenditure and lifestyle-related risk factors using statistical techniques developed in macroeconomics and finance. These covariates are then shown to improve forecasts when incorporated into a Bayesian hierarchical model. Results are comparable or better than benchmark stochastic mortality models.

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The Irish and UK governments, along with other countries, have made a commitment to limit the concentrations of greenhouse gases in the atmosphere by reducing emissions from the burning of fossil fuels. This can be achieved (in part) through increasing the sequestration of CO2 from the atmosphere including monitoring the amount stored in vegetation and soils. A large proportion of soil carbon is held within peat due to the relatively high carbon density of peat and organic-rich soils. This is particularly important for a country such as Ireland, where some 16% of the land surface is covered by peat. For Northern Ireland, it has been estimated that the total amount of carbon stored in vegetation is 4.4Mt compared to 386Mt stored within peat and soils. As a result it has become increasingly important to measure and monitor changes in stores of carbon in soils. The conservation and restoration of peat covered areas, although ongoing for many years, has become increasingly important. This is summed up in current EU policy outlined by the European Commission (2012) which seeks to assess the relative contributions of the different inputs and outputs of organic carbon and organic matter to and from soil. Results are presented from the EU-funded Tellus Border Soil Carbon Project (2011 to 2013) which aimed to improve current estimates of carbon in soil and peat across Northern Ireland and the bordering counties of the Republic of Ireland.
Historical reports and previous surveys provide baseline data. To monitor change in peat depth and soil organic carbon, these historical data are integrated with more recently acquired airborne geophysical (radiometric) data and ground-based geochemical data generated by two surveys, the Tellus Project (2004-2007: covering Northern Ireland) and the EU-funded Tellus Border project (2011-2013) covering the six bordering counties of the Republic of Ireland, Donegal, Sligo, Leitrim, Cavan, Monaghan and Louth. The concept being applied is that saturated organic-rich soil and peat attenuate gamma-radiation from underlying soils and rocks. This research uses the degree of spatial correlation (coregionalization) between peat depth, soil organic carbon (SOC) and the attenuation of the radiometric signal to update a limited sampling regime of ground-based measurements with remotely acquired data. To comply with the compositional nature of the SOC data (perturbations of loss on ignition [LOI] data), a compositional data analysis approach is investigated. Contemporaneous ground-based measurements allow corroboration for the updated mapped outputs. This provides a methodology that can be used to improve estimates of soil carbon with minimal impact to sensitive habitats (like peat bogs), but with maximum output of data and knowledge.

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This paper considers the tension that can exist in the aims of religious education between the desire to encourage open-minded, critical thinking through exposure to diverse traditions, ideas and cultures and the encouragement, overt or otherwise, into uniformity whereby learners take on the values of a particular tradition, culture or ideology (say of a religion, family or school). The particular situation of teaching religious education to post-primary school pupils in Northern Ireland is considered, and evidence cited to suggest that the Northern Ireland Core Syllabus in Religious Education has tried to impose a particular non-denominational Christian uniformity on pupils and teachers through its use of religious language. This has contributed to a culture of 'avoidance' in relation to the teaching of broad Christian diversity. The article concludes that there is a need for an ongoing and meaningful dialogue to discover what kind of balance between uniformity and diversity is best in teaching religious education in Northern Ireland, and notes that this also requires the reassessment of fundamental issues such as the aims of education and the relationship between secular and religious values in publicly funded schools. © 2004 Christian Education.

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This article analyses news media coverage of the housing market. Building on theories of media influence where word of mouth is the final mechanism of opinion change but media initiate discourse, I examine the relationship between news media and the recent UK house price boom. Over 30 000 articles on the UK housing market from the period 1993 to 2008 are analysed, and it is found that media Granger-caused real house price changes, suggesting the media may have influenced opinions on the housing market. However, media sentiment on the housing market did not change with the secular increase in house prices in the 2000s, suggesting that the media did not contribute to the UK’s housing boom and may have helped constrain it.

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Conventional wisdom on party systems in advanced industrial democracies holds that modern electorates are dealigned and that social cleavages no longer structure party politics. Recent work on class cleavages has challenged this stylized fact. The analysis performed here extends this criticism to the religious-secular cleavage. Using path analysis and comparing the current electorates of the United States, Germany, and Great Britain with the early 1960s, this paper demonstrates that the religious-secular cleavage remains or has become a significant predictor of conservative vote choice. While the effects of the religious-secular cleavage on vote choice have become largely indirect, the total of the direct and indirect effects is substantial and equivalent to the effects of class and status.

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The term “culture war” has become a generic expression for secular-catholic conflicts across nineteenth-century Europe. Yet, if measured by acts of violence, anticlericalism peaked in the years between 1927 and 1939, when thousands of Catholic priests and believers were imprisoned or executed and hundreds of churches razed in Mexico, Spain and Russia. This essay argues that not only in these three countries, but indeed across Europe a culture war raged in the interwar period. It takes, as a case study, the interaction of communist and Catholic actors located in the Vatican, the Soviet Union, and Germany in the period between the beginning of the Pontificate of Pius XI in 1922 and Hitler’s appointment as chancellor of Germany in 1933. Using correspondence and reports from the Vatican archives, this essay shows how Papal officials and communist leaders each sought to mobilize the German populace to achieve their own diplomatic ends. German Catholics and communists gladly responded to the call to arms that sounded from Rome and Moscow in 1930, but they did so also to further their own domestic goals. The case study shows how national contexts inflected the transnational dynamics of radical anti-Catholicism in interwar Europe. In the end, agitation against “godlessness” did not lead to the return of a “Christian State” desired by many conservative Christians. Instead, the culture war further destabilized the republic and added a religious dimension to a landscape well suited to National Socialist efforts to reach a Christian population otherwise mistrustful of its völkisch and anticlerical elements.

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The paper addresses the possibility of the existence of a ‘hidden curriculum’ in nineteenth- and early twentieth-century National Schools by comparing working practices evident from an analysis of a sample of schools from two case study areas in the north of Ireland – Derry City and the rural area of Boho/Derrygonnelly in western County Fermanagh. The relationship between the placement of the school buildings and variations in their external appearances are examined in respect to their relationships with different churches. The possible significance of this relationship is scrutinised given that the primary aim of the National School system was joint secular education in a religiously divided society. Both the external and internal architecture of the buildings are also examined for the purposes of reconstructing aspects of the intentions and practices that governed their use. In particular, the relationship between allocated space and the categories of age and gender are studied by means of an access analysis of the floor plans of a representative sample of primary schools from both case study areas. Information derived from oral history accounts, archived material from the Public Record Office of Northern Ireland (PRONI) and school registers is used to supplement the findings obtained from the architectural analyses.

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Purpose. To investigate the robustness of single vocal cord intensity modulated radiation therapy (IMRT) treatment plans for set-up errors, respiration, and deformation. Material and methods. Four-dimensional computed tomography (4D-CT) scans of 10 early glottic carcinoma patients, previously treated with conventional techniques, were used in this simulation study. For each patient a pre-treatment 4D-CT was used for IMRT planning, generating a reference dose distribution. Prescribed PTV dose was 66 Gy. The impact of systematic set-up errors was simulated by applying shifts of ± 2 mm to the planning CT scans, followed by dose re-calculation with original beam segments, MUs, etc. Effects of respiration and deformation were determined utilizing extreme inhale and exhale CT scans, and repeat scans acquired after 22 Gy, 44 Gy, and 66 Gy, respectively. All doses were calculated using Monte Carlo dose simulations. Results. Considering all investigated geometrical perturbations, reductions in the clinical target volume (CTV) V95%, D98%, D2%, and generalized equivalent uniform dose (gEUD) were limited to 1.2 ± 2.2%, 2.4 ± 2.9%, 0.2 ± 1.8%, and 0.6 ± 1.1 Gy, respectively. The near minimum dose, D98%, was always higher than 89%, and gEUD always remained higher than 66 Gy. Planned contra-lateral (CL) vocal cord DMean, gEUD, and V40 Gy were 38.2 ± 6.0 Gy, 43.4 ± 5.6 Gy, and 42.7 ± 14.9%. With perturbations these values changed by -0.1 ± 4.3 Gy, 0.1 ± 4.0 Gy, and -1.0 ± 9.6%, respectively. Conclusions. On average, CTV dose reductions due to geometrical perturbations were very low, and sparing of the CL vocal cord was maintained. In a few observations (6 of 103 simulated situations), the near-minimum CTV-dose was around 90%, requiring attention in deciding on a future clinical protocol. 

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We study the sensitivity of a MAP configuration of a discrete probabilistic graphical model with respect to perturbations of its parameters. These perturbations are global, in the sense that simultaneous perturbations of all the parameters (or any chosen subset of them) are allowed. Our main contribution is an exact algorithm that can check whether the MAP configuration is robust with respect to given perturbations. Its complexity is essentially the same as that of obtaining the MAP configuration itself, so it can be promptly used with minimal effort. We use our algorithm to identify the largest global perturbation that does not induce a change in the MAP configuration, and we successfully apply this robustness measure in two practical scenarios: the prediction of facial action units with posed images and the classification of multiple real public data sets. A strong correlation between the proposed robustness measure and accuracy is verified in both scenarios.