878 resultados para POPULATION GROWTH
Resumo:
1. Management decisions regarding invasive plants often have to be made quickly and in the face of fragmentary knowledge of their population dynamics. However, recommendations are commonly made on the basis of only a restricted set of parameters. Without addressing uncertainty and variability in model parameters we risk ineffective management, resulting in wasted resources and an escalating problem if early chances to control spread are missed. 2. Using available data for Pinus nigra in ungrazed and grazed grassland and shrubland in New Zealand, we parameterized a stage-structured spread model to calculate invasion wave speed, population growth rate and their sensitivities and elasticities to population parameters. Uncertainty distributions of parameters were used with the model to generate confidence intervals (CI) about the model predictions. 3. Ungrazed grassland environments were most vulnerable to invasion and the highest elasticities and sensitivities of invasion speed were to long-distance dispersal parameters. However, there was overlap between the elasticity and sensitivity CI on juvenile survival, seedling establishment and long-distance dispersal parameters, indicating overlap in their effects on invasion speed. 4. While elasticity of invasion speed to long-distance dispersal was highest in shrubland environments, there was overlap with the CI of elasticity to juvenile survival. In shrubland invasion speed was most sensitive to the probability of establishment, especially when establishment was low. In the grazed environment elasticity and sensitivity of invasion speed to the severity of grazing were consistently highest. Management recommendations based on elasticities and sensitivities depend on the vulnerability of the habitat. 5. Synthesis and applications. Despite considerable uncertainty in demography and dispersal, robust management recommendations emerged from the model. Proportional or absolute reductions in long-distance dispersal, juvenile survival and seedling establishment parameters have the potential to reduce wave speed substantially. Plantations of wind-dispersed invasive conifers should not be sited on exposed sites vulnerable to long-distance dispersal events, and trees in these sites should be removed. Invasion speed can also be reduced by removing seedlings, establishing competitive shrubs and grazing. Incorporating uncertainty into the modelling process increases our confidence in the wide applicability of the management strategies recommended here.
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Essential hypertension is one of the most common diseases in the Western world, affecting about 26.4% of the adult population, and it is increasing (1). Its causes are heterogeneous and include genetic and environmental factors (2), but several observations point to an important role of the kidney in its genesis (3). In addition to variations in tubular transport mechanisms that could, for example, affect salt handling, structural characteristics of the kidney might also contribute to hypertension. The burden of chronic kidney disease is also increasing worldwide, due to population growth, increasing longevity, and changing risk factors. Although single-cause models of disease are still widely promoted, multideterminant or multihit models that can accommodate multiple risk factors in an individual or in a population are probably more applicable (4,5). In such a framework, nephron endowment is one potential determinant of disease susceptibility. Some time ago, Brenner and colleagues (6,7) proposed that lower nephron numbers predispose both to essential hypertension and to renal disease. They also proposed that hypertension and progressive renal insufficiency might be initiated and accelerated by glomerular hypertrophy and intraglomerular hypertension that develops as nephron number is reduced (8). In this review, we summarize data from recent studies that shed more light on these hypotheses. The data supply a new twist to possible mechanisms of the Barker hypothesis, which proposes that intrauterine growth retardation predisposes to chronic disease in later life (9). The review describes how nephron number is estimated and its range and some determinants and morphologic correlates. It then considers possible causes of low nephron numbers. Finally, associations of hypertension and renal disease with reduced nephron numbers are considered, and some potential clinical implications are discussed.
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An expanding human population and associated demands for goods and services continues to exert an increasing pressure on ecological systems. Although the rate of expansion of agricultural lands has slowed since 1960, rapid deforestation still occurs in many tropical countries, including Colombia. However, the location and extent of deforestation and associated ecological impacts within tropical countries is often not well known. The primary aim of this study was to obtain an understanding of the spatial patterns of forest conversion for agricultural land uses in Colombia. We modeled native forest conversion in Colombia at regional and national-levels using logistic regression and classification trees. We investigated the impact of ignoring the regional variability of model parameters, and identified biophysical and socioeconomic factors that best explain the current spatial pattern and inter-regional variation in forest cover. We validated our predictions for the Amazon region using MODIS satellite imagery. The regional-level classification tree that accounted for regional heterogeneity had the greatest discrimination ability. Factors related to accessibility (distance to roads and towns) were related to the presence of forest cover, although this relationship varied regionally. In order to identify areas with a high risk of deforestation, we used predictions from the best model, refined by areas with rural population growth rates of > 2%. We ranked forest ecosystem types in terms of levels of threat of conversion. Our results provide useful inputs to planning for biodiversity conservation in Colombia, by identifying areas and ecosystem types that are vulnerable to deforestation. Several of the predicted deforestation hotspots coincide with areas that are outstanding in terms of biodiversity value.
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The spatial heterogeneity in the risk of Ross River virus (family Togaviridae, genus Alphavirus, RRV) disease, the most common mosquito-borne disease in Australia, was examined in Redland Shire in southern Queensland, Australia. Disease cases, complaints from residents of intense mosquito biting exposure, and human population data were mapped using a geographic information system. Surface maps of RRV disease age-sex standardized morbidity ratios and mosquito biting complaint morbidity ratios were created. To determine whether there was significant spatial variation in disease and complaint patterns, a spatial scan analysis method was used to test whether the number of cases and complaints was distributed according to underlying population at risk. Several noncontiguous areas in proximity to productive saline water habitats of Aedes vigilax (Skuse), a recognized vector of RRV, had higher than expected numbers of RRV disease cases and complaints. Disease rates in human populations in areas which had high numbers of adult Ae. vigilax in carbon dioxide- and octenol-baited light traps were up to 2.9 times those in areas that rarely had high numbers of mosquitoes. It was estimated that targeted control of adult Ae. vigilax in these high-risk areas could potentially reduce the RRV disease incidence by an average of 13.6%. Spatial correlation was found between RRV disease risk and complaints from residents of mosquito biting. Based on historical patterns of RRV transmission throughout Redland Shire and estimated future human population growth in areas with higher than average RRV disease incidence, it was estimated that RRV incidence rates will increase by 8% between 2001 and 2021. The use of arbitrary administrative areas that ranged in size from 4.6 to 318.3 km2, has the potential to mask any small scale heterogeneity in disease patterns. With the availability of georeferenced data sets and high-resolution imagery, it is becoming more feasible to undertake spatial analyses at relatively small scales.
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allard's introductory chapter reviews the lively debate concerning the introduction of sweet potato into Oceania and its role in debates concerning population growth, population density, and their relationship to agricultural intensification and socio- economic and political change, particularly in New Guinea. Other forms of proxy data include archaeological evidence for cropping and agricultural technology (Coil and Kirch); temporal data indicative of shifts in landscape use and changing agricultural practices (Bayliss-Smith et al.; Haberle and Atkin; Wallin et al.); and data from legends, ethnohistoric documents, and ethnographic studies providing evidence for the timing of the introduction, and the importance of the crop in various Oceanic societies (Allen; Dunis; Wallin et al.).
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Wilbur Zelinsky formulated a Hypothesis of Mobility Transition in 1971,in which he tried to relate all aspects of mobility to the Demographic Transition and modernisation. This dissertation applies the theoretical framework, proposed by Zelinsky and extended to encompass a family of transitions, to understand migration patterns of city regions. The two city regions, Brisbane and Stockholm, are selected as case studies, representing important city regions of similar size, but drawn from contrasting historical settings. A comparison of the case studies with the theoretical framework aims to determine how the relative contributions of net migration, the source areas of migrants, and the migration intensity change with modernisation. In addition, the research also aims to identify aspects of modernisation affecting migration. These aspects of migration are analysed with a "historical approach" and a "multivariate approach". An extensive investigation into the city regions' historical background provides the source, from which evidence for a relationship between migration and modernisation is extracted. With this historical approach, similarities and differences in migration patterns are identified. The other research approach analyse multivariate data, from the last two decades, on migration flows and modernisation. Correlations between migration and key aspects of modernisation are tested with multivariate regression, based on an alternative version of a spatial interaction model. The project demonstrates that the changing functions of cities and the structural modernisation are influential on migration. Similar patterns are found, regarding the relative contributions of net migration and natural increase to population growth. The research finds links between these changes in the relative contribution of net migration and demographic modernisation. The findings on variations in urban and rural source areas of migrants to city regions do not contradict the expected pattern, but data limitations prevent definite conclusion to be drawn. The assessment of variations in migration intensity resulted in the expected pattern not being supported. Based on Swedish data, the hypothesised increase in migration intensity is rejected. Interactional migration data also show patterns different from those derived from the theoretical framework. The findings, from both research approaches, suggested that structural modernisation affected migration flows more than demographic modernisation. The findings lead to a formulation of hypothesised patterns for migration to city regions. The study provides an important research contribution by applying the two research approaches to city regions. It also combines the study of internal and international migration to address the research objectives within a framework of transitional change.
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O município de Rio Grande da Serra está situado em uma região Grande ABC paulista reconhecida nacionalmente por seu desenvolvimento econômico e industrial e pelas lutas políticas e sindicais. Paradoxalmente, se configura, social e territorialmente falando, por uma região de periferia urbana. Resultado da forma como a urbanização, na sociedade moderna, conforma o espaço em regiões centrais e periféricas. Localizado no caminho que ligava Santos à Mogi das Cruzes (século XIX) povoado de Geribatiba decorrente das transformações urbanas ocorridas em toda a região, conquistaria, nos anos 1960, sua autonomia político-administrativa. Nas décadas seguintes testemunhou intenso crescimento populacional, resultado do processo migratório, principalmente de mineiros e nordestinos que tinham as cidades, e indústrias, de São Paulo e Grande ABC como destino. Esse deslocamento de pessoas, e as redes formadas em seu em torno, contribuiu para o desenvolvimento de seu campo religioso. Atualmente, com uma população, em torno, de 46 mil habitantes, possui aproximadamente 180 locais de cerimônias religiosas. Nesse contexto, a tese analisa a inserção regional socioeconômica e religiosa de Rio Grande da Serra, a partir de dados comparativos com os demais municípios, e discute como o regionalismo tem contribuído para seu desenvolvimento econômico. Realiza a caracterização das periferias urbanas, discutindo aspectos que lhes são inerentes, como segregação e vulnerabilidade social. Nesse sentido, a investigação possibilitou a identificação do perfil socioeconômico (renda e escolaridade) dos participantes dos grupos religiosos (católicos, evangélicos, kardecistas e umbandistas), permitindo, também, identificar desigualdades sociais no interior de seu território, constatando que determinados bairros são mais vulneráveis do que outros. Considerando que esse estudo examina a capacidade das redes sociais e religiosas, de aumentar o capital social de seus participantes, foi realizado o mapeamento e etnografia das diversas práticas associativas, mais ou menos formais e estruturadas, de forma a analisar os elementos materiais e simbólicos por elas produzidos. Constatou-se, apoiado na aplicação de questionários, entrevistas e observação participativa, que, a partir do habitus religioso de cada grupo, as redes possibilitam no âmbito econômico questões como emprego e renda ou auxílio em necessidades básicas de sobrevivência, através de campanhas e trabalhos sociais. No âmbito simbólico, as redes propiciam questões importantes à existência humana, como a crença na salvação ou evolução da alma, socialização, autoestima, prestígio ou ainda a expectativa de cura ou tratamento de dependência química. Pôde-se aferir que, a despeito das diferentes formas como cada grupo, e seus participantes, se apropriam do capital social, as redes sociais e religiosas, no município, funcionam como redes de proteção, especialmente à população em situação alta de vulnerabilidade social.
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Industrial development, accompanying human population growth, has had a major role in creating the situation where bio-diverse materials and services essential for sustaining business are under threat. A major contributory factor to biodiversity decline comes from the cumulative impacts of extended supply chain business operations. However, within Corporate Responsibility (CR) reporting impacts on biodiversity due to supply chain operations have not traditionally been given equal weighting with other environmental issues. This paper investigates the extent of CR reporting in managing and publicising company biodiversity supply chain issues by reviewing a cross-sector sample of publicly available CR reports. The report contents were examined for suggestions of industrial sectorial trends in the level of biodiversity consideration. The reporting of environmental management system use within company supply chain management is assessed in the samples and is considered as a mechanism for responsible supplier partnership working.
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In the face of global population growth and the uneven distribution of water supply, a better knowledge of the spatial and temporal distribution of surface water resources is critical. Remote sensing provides a synoptic view of ongoing processes, which addresses the intricate nature of water surfaces and allows an assessment of the pressures placed on aquatic ecosystems. However, the main challenge in identifying water surfaces from remotely sensed data is the high variability of spectral signatures, both in space and time. In the last 10 years only a few operational methods have been proposed to map or monitor surface water at continental or global scale, and each of them show limitations. The objective of this study is to develop and demonstrate the adequacy of a generic multi-temporal and multi-spectral image analysis method to detect water surfaces automatically, and to monitor them in near-real-time. The proposed approach, based on a transformation of the RGB color space into HSV, provides dynamic information at the continental scale. The validation of the algorithm showed very few omission errors and no commission errors. It demonstrates the ability of the proposed algorithm to perform as effectively as human interpretation of the images. The validation of the permanent water surface product with an independent dataset derived from high resolution imagery, showed an accuracy of 91.5% and few commission errors. Potential applications of the proposed method have been identified and discussed. The methodology that has been developed 27 is generic: it can be applied to sensors with similar bands with good reliability, and minimal effort. Moreover, this experiment at continental scale showed that the methodology is efficient for a large range of environmental conditions. Additional preliminary tests over other continents indicate that the proposed methodology could also be applied at the global scale without too many difficulties
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Abstract Two species of mangrove trees of Indo- Pacific origin have naturalized in tropical Atlantic mangrove forests in South Florida after they were planted and nurtured in botanic gardens. Two Bruguiera gymnorrhiza trees that were planted in the intertidal zone in 1940 have given rise to a population of at least 86 trees growing interspersed with native mangrove species Rhizophora mangle, Avicennia germinans and Laguncularia racemosa along 100 m of shoreline; the population is expanding at a rate of 5.6% year-1. Molecular genetic analyses confirm very low genetic diversity, as expected from a population founded by two individuals. The maximumnumber of alleles at any locus was three, and we measured reduced heterozygosity compared to native-range populations. Lumnitzera racemosa was introduced multiple times during the 1960s and 1970s, it has spread rapidly into a forest composed of native R. mangle, A. germinans, Laguncularia racemosa and Conocarpus erectus and now occupies 60,500 m2 of mangrove forest with stem densities of 24,735 ha-1. We estimate the population growth rate of Lumnitzera racemosa to be between 17 and 23% year-1. Populations of both species of naturalized mangroves are dominated by young individuals. Given the long life and water-dispersed nature of propagules of the two exotic species, it is likely that they have spread beyond our survey area. We argue that the species-depauperate nature of tropical Atlantic mangrove forests and close taxonomic relatives in the more species-rich Indo-Pacific region result in the susceptibility of tropical Atlantic mangrove forests to invasion by Indo-Pacific mangrove species.
Resumo:
Two species of mangrove trees of Indo- Pacific origin have naturalized in tropical Atlantic mangrove forests in South Florida after they were planted and nurtured in botanic gardens. Two Bruguiera gymnorrhiza trees that were planted in the intertidal zone in 1940 have given rise to a population of at least 86 trees growing interspersed with native mangrove species Rhizophora mangle, Avicennia germinans and Laguncularia racemosa along 100 m of shoreline; the population is expanding at a rate of 5.6% year-1. Molecular genetic analyses confirm very low genetic diversity, as expected from a population founded by two individuals. The maximumnumber of alleles at any locus was three, and we measured reduced heterozygosity compared to native-range populations. Lumnitzera racemosa was introduced multiple times during the 1960s and 1970s, it has spread rapidly into a forest composed of native R. mangle, A. germinans, Laguncularia racemosa and Conocarpus erectus and now occupies 60,500 m2 of mangrove forest with stem densities of 24,735 ha-1. We estimate the population growth rate of Lumnitzera racemosa to be between 17 and 23% year-1. Populations of both species of naturalized mangroves are dominated by young individuals. Given the long life and water-dispersed nature of propagules of the two exotic species, it is likely that they have spread beyond our survey area. We argue that the species-depauperate nature of tropical Atlantic mangrove forests and close taxonomic relatives in the more species-rich Indo-Pacific region result in the susceptibility of tropical Atlantic mangrove forests to invasion by Indo-Pacific mangrove species.
Resumo:
The most fundamental and challenging function of government is the effective and efficient delivery of services to local taxpayers and businesses. Counties, once known as the “dark continent” of American government, have recently become a major player in the provision of services. Population growth and suburbanization have increased service demands while the counties' role as service provider to incorporated residents has also expanded due to additional federal and state mandates. County governments are under unprecedented pressure and scrutiny to meet citizens' and elected officials' demands for high quality, and equitable delivery of services at the lowest possible cost while contending with anti-tax sentiments, greatly decreased state and federal support, and exceptionally costly and complex health and public safety problems. ^ This study tested the reform government theory proposition that reformed structures of county government positively correlate with efficient service delivery. A county government reformed index was developed for this dissertation comprised of form of government, home-rule status, method of election, number of government jurisdictions, and number of elected officials. The county government reform index and a measure of relative structural fragmentation were used to assess their impact on two measures of service output: mean county road pavement condition and county road maintenance expenditures. The study's multi-level design triangulated results from different data sources and methods of analysis. Data were collected from semi-structured interviews of county officials, secondary archival sources, and a survey of 544 elected and appointed officials from Florida's 67 counties. The results of the three sources of data converged in finding that reformed Florida counties are more likely than unreformed counties to provide better road service and to spend less on road expenditures. The same results were found for unfragmented Florida counties. Because both the county government reform index and the fragmentation variables were specified acknowledging the reform theory as well as elements from the public-choice model, the results help explain contradicting findings in the urban service research. ^ Therefore, as suggested by the corroborated findings of this dissertation, reformed as well as unfragmented counties are better providers of road maintenance service and do so in a less costly manner. These findings hold although the variables were specified to capture theoretical arguments from the consolidated as well as the public-choice theories suggesting a way to advance the debate from the consolidated-fragmented dichotomy of urban governance. ^
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Lepidocaryum tenue Mart. (Arecaceae) is a small, understory palm of terra firme forests of the western and central Amazon basin. Known as irapai, it is used for roof thatch by Amazonian peoples who collect its leaves from the wild and generate income from its fronds and articles fabricated from them. Increasing demand has caused local concern that populations are declining. Cultivation attempts have been unsuccessful. The purpose of this study was to investigate market conditions and quantify population dynamics and demographic responses of harvested and unharvested irapai growing near Iquitos, Peru. ^ Ethnobotanical research included participant surveys to determine movement of thatch tiles, called crisnejas, through Moronacocha Port. I also conducted a seed germination trial, and for four years studied five populations growing in communities with similar topography and soils but different land tenure and management strategies. Stage, survival, leaf production, and reproductive transitions were used to calculate ramet demographic rates and develop population projection matrices. ^ Weavers made an average of 20–30 crisnejas per day (90–130 leaves each), and earned US$0.09 to 0.70 each (US$1.80 to 21.00 per day). Average crisnejas per month sold per vendor was 2,955 with a profit range of US$0.05 to 0.32 per crisneja. Wholesalers worked with capital outlay from US$100 to 400, and an estimated ten to twenty vendors could be found at a given time. Consumers paid between US$0.23 to 1.20 per crisneja. Although differences in demographic rates by location existed, most were not significant enough to attribute to management. ^ After 60 months, mean seed germination rate was 19.5% in all media (37.9% in peat). Seedling survival was less than two percent after twelve months. Annual palm mortality was three percent, and occurred disproportionately in small (<50 cm) palms. Small palms grew more in height. Unharvested palms grew less than harvested palms. Large palms (≥50 cm) produced more leaves, were more likely to reproduce, and collectors harvested them more frequently. Reproductive potentials (sexual and asexual) were low. Population growth rates were greater than or not significantly different from 1.0, indicating populations maintained or increased in size. Current levels of irapai harvest appear sustainable. DNA analysis of stems and recruits is recommended to understand population composition and stage-specific asexual fecundity. ^
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This study describes the case of private higher education in Ohio between 1980 and 2006 using Zumeta's (1996) model of state policy and private higher education. More specifically, this study used case study methodology and multiple sources to demonstrate the usefulness of Zumeta's model and illustrate its limitations. Ohio served as the subject state and data for 67 private, 4-year, degree-granting, Higher Learning Commission-accredited institutions were collected. Data sources for this study included the National Center for Education Statistics Integrated Postsecondary Data System as well as database information and documents from various state agencies in Ohio, including the Ohio Board of Regents. ^ The findings of this study indicated that the general state context for higher education in Ohio during the study time period was shaped by deteriorating economic factors, stagnating population growth coupled with a rapidly aging society, fluctuating state income and increasing expenditures in areas such as corrections, transportation and social services. However, private higher education experienced consistent enrollment growth, an increase in the number of institutions, widening involvement in state-wide planning for higher education, and greater fiscal support from the state in a variety of forms such as the Ohio Choice Grant. This study also demonstrated that private higher education in Ohio benefited because of its inclusion in state-wide planning and the state's decision to grant state aid directly to students. ^ Taken together, this study supported Zumeta's (1996) classification of Ohio as having a hybrid market-competitive/central-planning policy posture toward private higher education. Furthermore, this study demonstrated that Zumeta's model is a useful tool for both policy makers and researchers for understanding a state's relationship to its private higher education sector. However, this study also demonstrated that Zumeta's model is less useful when applied over an extended time period. Additionally, this study identifies a further limitation of Zumeta's model resulting from his failure to define "state mandate" and the "level of state mandates" that allows for inconsistent analysis of this component. ^
Resumo:
In their discussion - Fast-Food Franchises: An Alternative Menu for Hotel/Casinos - by Skip Swerdlow, Assistant Professor of Finance, Larry Strate, Assistant Professor of Business Law, and Francis X. Brown, Assistant Professor of Hotel Administration at the University of Nevada, Las Vegas, their preview reads: Hotel/casino food service operations are adding some non-traditional fare to their daily offerings in the form of fast-food franchises. The authors review aspects of franchising and cite some new Las Vegas food ideas.” The authors offer that the statewide food and beverage figures, according to the Nevada Gaming Abstract of 1985, exceeded $1.24 billion. Most of that figure was generated in traditional coffee shops, gourmet dining rooms, and buffets. With that kind of food and beverage figure solidly on the table, it was inevitable that fast-food franchises would move into casinos to garner a share of the proceeds. In a March 1986 review of franchising, Restaurant Business reported the following statistics: “Over 60 percent of all restaurants are franchisee owned. This relationship is also paralleled in dollar sales, which has exceeded $53 billion.” “Restaurant franchising expansion has grown at an annual rate of 12 percent per year for the past five years.” The beginning of the article is dedicated to describing, in general, the franchise phenomenon; growth has been spectacular the authors inform you. “The franchise concept has provided an easy method of going into business for the entrepreneur with minimal business experience, but a desire to work hard to make a profit,” say professors Swerdlow, Strate, and Brown. Lured by tourist traffic, and the floundering Chapter 11 afflicted, Riviera Hotel and Casino in Las Vegas, Burger King saw an attractive opportunity for an experiment in non-traditional outlet placement, say the authors. Although innately transient, the tourist numbers were way too significant to ignore. That tourist traffic, the authors say, is ‘round-the-clock. Added to that figure is the 2000-3000 average employee count for many of the casinos on the ‘Vegas strip. Not surprisingly, the project began to look very appealing to both Burger King and the Riviera Hotel/Casino, the authors report. In the final analysis, the project did work out well; very well indeed. So it is written, “The successful operation of the Burger King in the Riviera has sparked interest by other existing hotel/casino operations and fast-food restaurant chains. Burger King's operation, like so many other industry leadership decisions, provides impetus for healthy competition in a market that is burgeoning not only because of expansion that recognizes traditional population growth, but because of bold moves that search for customers in non-traditional areas.” The authors provide an Appendix listing Las Vegas hotel/casino properties and the restaurants they contain.