Extrapolation Of Trends Research Articles

Sustainability of culture-driven population dynamics

We consider models of the interactions between human population dynamics and cultural evolution, asking whether they predict sustainable or unsustainable patterns of growth. Phenomenological models predict either unsustainable population growth or stabilization in the near future. The latter prediction, however, is based on extrapolation of current demographic trends and does not take into account causal processes of demographic and cultural dynamics. Most existing causal models assume (or derive from simplified models of the economy) a positive feedback between cultural evolution and demographic growth, and predict unlimited growth in both culture and population. We augment these models taking into account that: (1) cultural transmission is not perfect, i.e., culture can be lost; (2) culture does not always promote population growth. We show that taking these factors into account can cause radically different model behavior, such as population extinction rather than stability, and extinction rather than growth. We conclude that all models agree that a population capable of maintaining a large amount of culture, including a powerful technology, runs a high risk of being unsustainable. We suggest that future work must address more explicitly both the dynamics of resource consumption and the cultural evolution of beliefs implicated in reproductive behavior (e.g., ideas about the preferred family size) and in resource use (e.g., environmentalist stances).

Five tools to prepare for future discontinuities

PurposeBecause most observers ordinarily view the future as an extrapolation of current trends, they are unprepared for discontinuities. The paper aims to urge that leaders foster a culture of open mindedness to better imagine and prepare for discontinuity.Design/methodology/approachBased on best practice experimentation the authors suggest five “tools” that are useful for achieving a discontinuous mindset.FindingsTo achieve a discontinuous mindset, managers need not turn their back on current forecasting activities, but they do need to balance them, intellectually, with considerations of longer‐term uncertainties.Practical implicationsAlthough the authors appreciate the value of innovative planning techniques – scenario planning, diversity planning, reverse‐engineering the future, developing a 25‐year business plan and culture‐based planning – they propose that a discontinuous mindset and the five tools to develop it are the best defenses against unanticipated disruption of markets.Originality/valueThe five tools for developing a discontinuous mindset offer a fresh take on how leaders can come to grips with an uncertain future.

Prediction of Glaucomatous Visual Field Loss by Extrapolation of Linear Trends

To investigate how well short-term progression rates can predict long-term visual field outcomes in patients with glaucoma. We calculated visual field rates of progression using linear regression analysis of the Visual Field Index (VFI) for 100 consecutive patients with glaucoma having 10 or more Swedish Interactive Thresholding Algorithm standard field tests. Final VFI was predicted on the basis of linear extrapolation of the slope defined by the initial 5 field test results. Final VFI also was estimated using linear regression of all qualifying examination results for each patient. Primary outcome measures were the absolute difference and the correlation between predicted and estimated final VFI values. Patient follow-up averaged 8.2 years and 11 field examinations. Median VFI progression rate was -1.1% per year both for the initial 5 test results and also for the complete series. Seventy percent of patients had a predicted final VFI within +/-10% of the estimated final VFI, and the 2 VFI calculations had a correlation coefficient of 0.84. Linear extrapolation based on 5 initial visual field test results was a reliable predictor of future field loss in most patients. Patients in whom linear regression analysis suggests dangerously rapid rates of visual field progression may be candidates for significant alterations in therapy.

Sensitivity studies with a statistical downscaling method the role of the driving large scale model

The sensitivity of the statistical downscaling method WETTREG, which analyzes the time evolution of circulation pattern frequencies taken from results of climate model 20 th century runs and scenarios and its consequences for local climate parameters, is studied. Several results from global models runs (BCCR, CGCM, and ECHAM) and one regional model run (CCLM) are used in their pattern-generating capacity to derive the WETTREG input. Moreover, several generations and runs of the same model are analyzed. In an additional experiment, an extrapolation of the recent trends in pattern frequency into the near future and the resulting short-term temperature and precipitation trends are investigated. The results show input data .dependent distinctive features concerning the reconstruction of the current climate, albeit of small magnitude. With respect to short-term climate trends for the target time frame 2011-2030, the model-specific bandwidth is strongest in winter and weakest in summer when 2 m air temperature is concerned and rarely leaves a ± 10 % envelope when percentual change of precipitation is concerned.

A long-term view of worldwide fossil fuel prices

This paper reviews a long-term trend of worldwide fossil fuel prices in the future by introducing a new method to forecast oil, natural gas and coal prices. The first section of this study analyses the global fossil fuel market and the historical trend of real and nominal fossil fuel prices from 1950 to 2008. Historical fossil fuel price analysis shows that coal prices are decreasing, while natural gas prices are increasing. The second section reviews previously available price modelling techniques and proposes a new comprehensive version of the long-term trend reverting jump and dip diffusion model. The third section uses the new model to forecast fossil fuel prices in nominal and real terms from 2009 to 2018. The new model follows the extrapolation of the historical sinusoidal trend of nominal and real fossil fuel prices. The historical trends show an increase in nominal/real oil and natural gas prices plus nominal coal prices, as well as a decrease in real coal prices. Furthermore, the new model forecasts that oil, natural gas and coal will stay in jump for the next couple of years and after that they will revert back to the long-term trend until 2018.

The unique role of halogen substituents in the design of modern agrochemicals

The past 30 years have witnessed a period of significant expansion in the use of halogenated compounds in the field of agrochemical research and development. The introduction of halogens into active ingredients has become an important concept in the quest for a modern agrochemical with optimal efficacy, environmental safety, user friendliness and economic viability. Outstanding progress has been made, especially in synthetic methods for particular halogen-substituted key intermediates that were previously prohibitively expensive. Interestingly, there has been a rise in the number of commercial products containing 'mixed' halogens, e.g. one or more fluorine, chlorine, bromine or iodine atoms in addition to one or more further halogen atoms. Extrapolation of the current trend indicates that a definite growth is to be expected in fluorine-substituted agrochemicals throughout the twenty-first century. A number of these recently developed agrochemical candidates containing halogen substituents represent novel classes of chemical compounds with new modes of action. However, the complex structure-activity relationships associated with biologically active molecules mean that the introduction of halogens can lead to either an increase or a decrease in the efficacy of a compound, depending on its changed mode of action, physicochemical properties, target interaction or metabolic susceptibility and transformation. In spite of modern design concepts, it is still difficult to predict the sites in a molecule at which halogen substitution will result in optimal desired effects. This review describes comprehensively the successful utilisation of halogens and their unique role in the design of modern agrochemicals, exemplified by various commercial products from Bayer CropScience coming from different agrochemical areas.

Pauvreté et progrès technique en Amérique latine : une vue à long terme

This study uses a simulation model of the Latin American economy in order to project the relationship between technical progress and income distribution over the 1970-2000 period. In the basic projections—an extrapolation of the present trends—a large number of urban and rural residents tend not to have access to the benefits of development. Alternative projections simulate the effects of policies aiming at i) the acceleration of growth, ii) the modification of the nature of technical progress, iii) the transfer of consumption. The impact of the two first policies is substantial, the main contribution of technological policies being a more equitable distribution of the benefits of growth.

A EXPANSÃO DA EDUCAÇÃO A DISTÂNCIA (EAD) NO ENSINO SUPERIOR BRASILEIRO: TENDÊNCIAS PARA O INÍCIO DA PRÓXIMA DÉCADA

In this article, the expansion of distance learning (DL) in Brazil’s Higher Education is analyzed with a view to addressing the following research query: How many schools, in Brazil, will offer undergraduate studies in the DL mode over the next five years?To this effect, bibliographical data was researched and historical series of variables were compiled – number of schools, of courses and of enrolled students, among other elements – to generate comparative graphs between the in loco (classroom) and the distance modes. Thus, the evolution of both types during the period studied is presented.Furthermore, a simple linear regression was used to correlate the variables ‘number of institutions’ and ‘time’, in order to extrapolate growth trends for the 2007-2011 period. Results point to a sharp expansion of DL, in all studied variables, and indicate that this may increase even further in the future.It also became evident that the growth of distance learning will have to overcome certain challenges, including better access to computers and to the Internet and the development of qualified personnel and of specific software to deal with it.Key words: Distance learning. Distance education. Extrapolation of trends and linear regression. Future studies.

Disposition of perfluorinated acid isomers in sprague‐dawley rats; Part 2: Subchronic dose

Two major industrial synthetic pathways have been used to produce perfluorinated acids (PFAs) or their precursors: Telomerization and electrochemical fluorination (ECF). Products of telomer and ECF origin can be distinguished by structural isomer profiles. A mixture of linear and branched perfluoroalkyl isomers is associated with ECF. Telomer products characteristically consist of a single perfluoroalkyl geometry, typically linear. In biota, it is unclear if the isomer profile is conserved relative to the exposure medium and hence whether PFA isomer profiles in organisms are useful for distinguishing environmental PFA sources. A companion study suggested isomer-specific disposition following a single oral gavage exposure to rats. To confirm these findings under a more realistic subchronic feeding scenario, male and female rats were administered PFA isomers by diet for 12 weeks, followed by a 12-week depuration period. The diet contained 500 ng/g each of ECF perfluorooctanoate (PFOA, approximately 80% n-PFOA), ECF perfluorooctane sulfonate (PFOS, approximately 70% n-PFOS), and linear and isopropyl perfluorononanoate (n- and iso-PFNA). Blood sampling during the exposure phase revealed preferential accumulation of n-PFOA and n-PFNA compared to most branched isomers. Female rats depurated all isomers faster than males. Both sexes eliminated most branched perfluorocarboxylate isomers more rapidly than the n-isomer. Elimination rates of the major branched PFOS isomers were not statistically different from n-PFOS. Two minor isomers of ECF PFOA and one branched PFOS isomer had longer elimination half-lives than the n-isomers. Although extrapolation of these pharmacokinetics trends in rats to humans and wildlife requires careful consideration of dosage level and species-specific physiology, cumulative evidence suggests that perfluorocarboxylate isomer profiles in biota may not be suitable for quantifying the relative contributions of telomer and ECF sources.

A EXPANSÃO DA EDUCAÇÃO A DISTÂNCIA (EAD) NO ENSINO SUPERIOR BRASILEIRO: TENDÊNCIAS PARA O INÍCIO DA PRÓXIMA DÉCADA DOI:10.7444/fsrj.v1i1.4

Neste artigo, analisa-se a expansão da Educação a Distância (EAD) no Ensino Superior Brasileiro com o objetivo de responder a seguinte questão de pesquisa: Qual o número de escolas que ofertará graduação na modalidade Educação a Distância (EAD), no Brasil, nos próximos cinco anos? Para tanto, levantou-se dados bibliográficos e criou-se séries históricas de variáveis - número de escolas, de cursos, de alunos matriculados, entre outros - que geraram gráficos comparativos entre as modalidades presencial e a distância. Dessa forma, apresenta-se a evolução de ambas as modalidades ao longo do período estudado. Além disso, utilizou-se a regressão linear simples para correlacionar as variáveis “número de instituições” e “tempo”, visando extrapolar as tendências de crescimento no período compreendido entre 2007 e 2011. Os resultados demonstram uma acelerada expansão da EAD, em todas as variáveis estudadas, indicando que esta pode aumentar ainda mais nos próximos anos. Também se constatou que a expansão do ensino a distância precisará superar alguns desafios como, por exemplo, o aumento do acesso a computadores e Internet, e o desenvolvimento de mão de obra qualificada e softwares específicos.Palavras-chave: Ensino a Distância. Extrapolação de tendências e regressão linear. Estudos do Futuro.

Comparison of methods for the detection and extrapolation of trends in groundwater quality

Land use changes and the intensification of agriculture since the 1950s have resulted in a deterioration of groundwater quality in many European countries. For the protection of groundwater quality, it is necessary to (1) assess the current groundwater quality status, (2) detect changes or trends in groundwater quality, (3) assess the threat of deterioration and (4) predict future changes in groundwater quality. A variety of approaches and tools can be used to detect and extrapolate trends in groundwater quality, ranging from simple linear statistics to distributed 3D groundwater contaminant transport models. In this paper we report on a comparison of four methods for the detection and extrapolation of trends in groundwater quality: (1) statistical methods, (2) groundwater dating, (3) transfer functions, and (4) deterministic modeling. Our work shows that the selection of the method should firstly be made on the basis of the specific goals of the study (only trend detection or also extrapolation), the system under study, and the available resources. For trend detection in groundwater quality in relation to diffuse agricultural contamination, a very important aspect is whether the nature of the monitoring network and groundwater body allows the collection of samples with a distinct age or produces samples with a mixture of young and old groundwater. We conclude that there is no single optimal method to detect trends in groundwater quality across widely differing catchments.

Trends in obesity among adults in England from 1993 to 2004 by age and social class and projections of prevalence to 2012

Background:This study aims to project the prevalence of adult obesity to 2012 by age groups and social class, by extrapolating the prevalence trends from 1993 to 2004. Repeated cross-sectional surveys...

Reframing the climate change challenge in light of post-2000 emission trends

The 2007 Bali conference heard repeated calls for reductions in global greenhouse gas emissions of 50 per cent by 2050 to avoid exceeding the 2 degrees C threshold. While such endpoint targets dominate the policy agenda, they do not, in isolation, have a scientific basis and are likely to lead to dangerously misguided policies. To be scientifically credible, policy must be informed by an understanding of cumulative emissions and associated emission pathways. This analysis considers the implications of the 2 degrees C threshold and a range of post-peak emission reduction rates for global emission pathways and cumulative emission budgets. The paper examines whether empirical estimates of greenhouse gas emissions between 2000 and 2008, a period typically modelled within scenario studies, combined with short-term extrapolations of current emissions trends, significantly constrains the 2000-2100 emission pathways. The paper concludes that it is increasingly unlikely any global agreement will deliver the radical reversal in emission trends required for stabilization at 450 ppmv carbon dioxide equivalent (CO2e). Similarly, the current framing of climate change cannot be reconciled with the rates of mitigation necessary to stabilize at 550 ppmv CO2e and even an optimistic interpretation suggests stabilization much below 650 ppmv CO2e is improbable.

Maximum height in a conifer is associated with conflicting requirements for xylem design

Despite renewed interest in the nature of limitations on maximum tree height, the mechanisms governing ultimate and species-specific height limits are not yet understood, but they likely involve water transport dynamics. Tall trees experience increased risk of xylem embolism from air-seeding because tension in their water column increases with height because of path-length resistance and gravity. We used morphological measurements to estimate the hydraulic properties of the bordered pits between tracheids in Douglas-fir trees along a height gradient of 85 m. With increasing height, the xylem structural modifications that satisfied hydraulic requirements for avoidance of runaway embolism imposed increasing constraints on water transport efficiency. In the branches and trunks, the pit aperture diameter of tracheids decreases steadily with height, whereas torus diameter remains relatively constant. The resulting increase in the ratio of torus to pit aperture diameter allows the pits to withstand higher tensions before air-seeding but at the cost of reduced pit aperture conductance. Extrapolations of vertical trends for trunks and branches show that water transport across pits will approach zero at a heights of 109 m and 138 m, respectively, which is consistent with historic height records of 100-127 m for this species. Likewise, the twig water potential corresponding to the threshold for runaway embolism would be attained at a height of approximately 107 m. Our results suggest that the maximum height of Douglas-fir trees may be limited in part by the conflicting requirements for water transport and water column safety.

Polyacenes electronic properties and their dependence on molecular size

The closed shell singlet electronic energies, atomization energies, polarizabilities, rotational constants and geometrical parameters of linear and angular (zigzag) polyacenes have been calculated employing HF and two DFT methods (B3LYP and LSDA) in conjunction with 6-31G(d) basis set. The possible linear and asymptotic relations of molecular properties of polyacene versus number of benzene rings as well as versus total number of electrons have been investigated. It was shown that the total electronic energies, atomization energies and some components of the polarizability tensor ( α MM and α NN) linearly increase with the number of ring and number of electrons. Also, it was found that the rotational constants and geometrical parameters of polyacenes with asymptotic trend go toward plateau values. By extrapolation of linear and asymptotic trends of polyacenes’ molecular properties we can in principle predict the properties of unknown species from those of subset of smaller polyacenes. Since computational studies are not feasible for large polyacenes, this finding makes it possible to consider molecular properties of larger polyacenes at higher level computational methods.

World Economy: Forecast for the Year 2050

Forecasting long-term trends in the world economy is a necessary element of elaborating a strategy of economic development. The forecast for 2025 and 2050 has been worked out using concepts of Kondratieff long waves, catching-up pathways of development as well as modern trends in demographic processes. The estimates of changes in the geographic structure of the world economy, so derived, are compared with forecasts based on extrapolation of trends in the last 30 years of the 20th century, made up by prominent think tanks. The formation of the multi-center structure of the world economy and probable emergence of Russia as one of the global powers may imply that worldwide cooperation in securing supply of natural resources and protecting the environment will become a crucial problem of international relations.

Plate tectonics, radiogenic isotopic tracers and paleoceanography: The case of the manganese crusts in the Pacific

Hydrogenous ferromanganese crust deposits on seafloor and volcanic seamounts are archives of past isotopic compositions of the ocean. Isotopic compositions of long-life radiogenic isotopes that are dissolved in the ocean such as Nd and Pb, are mixtures of different erosion products (continents, volcanics arcs, ridges etc…) transported by oceanic currents or winds. Isotopic studies on Mn crusts are thus potential paleogeographic and paleoceanographic tracers. However, global paleogeography can drastically evolve over the period of growth of crust, as well as the latitude, longitude and water depth of the Mn crust. Thus each crust sampled a succession of geographic sites related to its spatial evolution through time. For this reason, valid information about the past ocean isotopic composition can only be extracted from Mn crust under the condition that the successive paleogeographic and paleodepth positions can be reconstructed for each Mn crust. We followed this approach for six hydrogenous Mn crusts from the Pacific Ocean that have recorded Pb and Nd isotopic signals for the past 80 Myr. The evolution of the isotopic data was considered within a proper geodynamical framework that takes into account the paleopositions of the Pacific plate and surrounding continents, of the hot spots and ridges as well as the paths of the six crusts. The differences and similarities between the Pb and Nd revealed by our analysis emphasize their complementarity as paleoceanographic tracers. The Nd isotopes are strongly influenced by the exchange between Indian and Pacific waters, specifically by the progressive closure of the Indonesian Gateway. The closed central Pacific characteristics are defined from the extrapolation of the isotopic trend. This highlights the important role played by erosion of volcanic arcs in the Nd isotopic value of seawater. Our approach also stresses the influence of local volcanic activity (ridges or active hot spot) for lead isotopes.

The impact of globalisation on teleradiology practice

Some advocates of globalisation argue that a free market with little regulation is the best approach for achieving cost-effective healthcare. Healthcare, however, is different from other business activities in that it is typically less profit-driven; instead, it often involves the goal of providing equitable care to the underprivileged. Traditionally, the government has subsidised the expenses of delivering affordable healthcare to underserved communities. Because of the many recent advances in telecommunications technology, telemedicine has gained increasing attention. Teleradiology, in particular, is by far the maturest of all telemedicine disciplines and, thus, it may serve as a pivotal indicator of whether telemedicine on a global scale is feasible or not. In this paper, a prediction of the future landscape of globalised teleradiology operations is attempted based on the extrapolation of the historical trends in teleradiology practice as well as the growing pressure on federal and local governments to reduce their regulatory power under the General Agreement on Trade in Services (GATS).

Long-Term Labour Productivity and GDP Projections for the EU25 Member States: A Production Function Framework

This paper presents the results of long run labour productivity and GDP growth rate projections (until 2050) for each of the 25 EU Member States and provides a detailed overview of the forecast methodology used. These projections were undertaken in order to provide an internationally comparable macroeconomic framework against which to assess the potential economic and fiscal effects of ageing populations. This assessment was carried out as part of the work undertaken by the EU's Economic Policy Committee, in its Ageing Working Group, to project the public expenditure implications of ageing on pensions, health care, long-term care, unemployment insurance and education. The projections presented in this paper, using a common production function methodology for all 25 countries, show the GDP growth rate effects of an assumptions-driven extrapolation of recent trends in employment and labour productivity. In overall terms, the EU25 baseline projection suggests a significant slowdown in potential growth rates in the Union as a whole, with the EU25 growth rate projected to fall from around 2½% at present to half that rate over the period 2041-2050. Finally, various sensitivity tests are carried out to check the GDP per capita impact of some additional factors. Some of the interesting conclusions that emerge from these sensitivity tests include: ....the negative effect of a change in the age-structure of the population is fairly limited, although it is accepted that the labour productivity of an individual is likely to decline after the age of 55. A very strong fall in the productivity of older workers compared with that of prime-age workers would be required to significantly depress total labour productivity. Such an outcome, on the basis of current evidence, appears rather unlikely. ....changing the TFP growth rate targets (e.g. use of the 1990's average instead of the long-term 1970-2004 average) could strongly affect the projections.

Long-term trends in dissolved organic carbon concentration: a cautionary note

Dissolved organic carbon (DOC) plays an important role in surface water chemistry and ecology and trends in DOC concentration have been also associated with shifts in terrestrial carbon pools. Numerous studies have reported long-term trends in DOC concentration; however, some studies consider changes in average measured DOC whereas other compute discharge weighted concentrations. Because of differences in reporting methods and variable record lengths it is difficult to compare results among studies and make regional generalizations. Furthermore, changes in stream discharge may impact long-term trends in DOC concentration and the potentially subtle effect of shifts in stream flow may be missed if only measured DOC concentrations are considered. In this study we compare trends in volume-weighted vs. average measured DOC concentration between 1980 and 2001 at seven headwater streams in south-central Ontario, Canada that vary in wetland coverage and DOC (22-year mean vol. wt.) from 3.4 to 10.6 mg l−1. On average, annual measured DOC concentrations were 13–34% higher than volume-weighted values, but differences of up to 290% occurred in certain years. Estimates of DOC flux were correspondingly higher using measured concentration values. Both measured and volume-weighted DOC concentrations increased significantly between 1980 and 2001, but slopes were larger in measured data (0.04–0.35 mg l−1 year−1 compared with 0.05–0.15 mg l−1 year−1) and proportional increases at the most wetland-influenced sites ranged from 32 to 43% in volume-weighted DOC and from 52 to 75% in measured DOC. In contrast, DOC flux did not change with time when estimated using either method, because of the predominant influence of stream flow on DOC export. Our results indicate that changes in stream flow have an important impact on trends in DOC concentration, and extrapolation of trend results from one region to another should be made cautiously and consider methodological and reporting differences among sites.