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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Ljusföroreningar i stadsmiljö : Hur kan ljusföroreningar förebyggas vid nybyggnation?

Sjöling, Jakob January 2015 (has links)
Light pollution in urban areas - How to prevent light pollution at construction   Jakob Sjöling   Light pollution is a relatively new but rapidly growing form of pollution. Society's increasing demand for light coupled with the pace at which lighting technology evolves is accelerating that growth. The purpose of this study was to analyse how the construction industry plan and design outdoor lighting when erecting new buildings, specifically with regards to the issue of light pollution. It also investigated how local authorities work with these issues during urban planning. In both cases special interest was placed in ways to improve the planning and use of outdoor lighting in order to minimize light pollution. To this end a series of interviews were held with people in the construction industry who are involved in the planning of lighting. Interviews were also held with local officials who manages issues of lighting and the environment within the municipality of Kungsbacka, Sweden. The interviews showed that people who work with these issues were well aware that poorly planned lighting can cause glare and disturbances. They were, however, almost totally unaware of the severe danger that light at night poses to both human health and environmental stability. To remedy this, information about the risks posed by night-time lighting must be spread from the scientific community to entrepreneurs and local officials who work with lighting. There are also several areas where changes in routines can help to avoid many of the potential pitfalls threatening to cause an, otherwise good, lighting plan to fail in regards to light pollution.
2

Determinants and methods of assessment of melatonin levels among rotating shift nurses

Grundy, Anne Louise 30 June 2008 (has links)
Background: Long-term night shift work has been associated with multiple cancer sites, including breast, prostate, colon and endometrial. The mechanism for this effect is hypothesized to include the hormone melatonin; where increased light at night exposure during shift work reduces melatonin production and decreased melatonin levels are associated with increased cancer risk. In addition, physical activity has been shown to reduce cancer risk and existing laboratory studies indicate it has the potential to influence melatonin levels. Methods: A cross-sectional study of light intensity exposure, physical activity and melatonin levels was conducted among 61 rotating shift nurses at Kingston General Hospital. Light intensity exposure was measured using a light intensity data logger and melatonin concentrations were measured from urine and saliva samples, collected over a 24-hour period. Physical activity was assessed from a study questionnaire and one-day diary. Results: A statistically significant inverse association between light exposure and urinary melatonin levels was observed; however, the relationship was no longer significant when stratified by shift group. Analysis of salivary melatonin levels demonstrated that circadian rhythms of melatonin production in night workers were not altered in timing, such that peak melatonin production occurred at night. No association between light exposure and the magnitude of salivary melatonin variation was observed. The relationship between recent physical activity and melatonin differed by shift group, with a positive association seen among day workers, while an inverse relationship was seen among night workers. There was no association between usual physical activity and melatonin in either shift group. Finally, no significant correlation was observed between sleep duration and melatonin among either day or night workers. Conclusions: While this study demonstrated an inverse relationship between light intensity and melatonin, the comparison of functional time points between day and night workers meant that differences in urinary melatonin levels between shift groups could be attributed to differences in the time of day when urine samples were collected. No consistent relationship between recent or usual physical activity and melatonin levels was observed in either shift group. Sleep duration was not correlated with urinary melatonin levels, suggesting it cannot be used as a proxy for melatonin production. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2008-06-26 08:39:21.645
3

The Influence of Shift Work, Light at Night and Clock Gene Polymorphisms on Melatonin Levels and Breast Cancer Risk

Grundy, ANNE 27 September 2012 (has links)
Background: Shift work has recently been identified as a breast cancer risk factor, where meta-analysis has indicated an approximately 50% increased risk among long-term shift workers. However, additional studies with more comprehensive methods of shift work exposure assessment are needed to capture the diversity of shift patterns. The hypothesized mechanism for this relationship involves chronodisruption (altered circadian rhythms), where increased exposure to light at night during night shifts may decrease production of the cancer-protective hormone melatonin. Further, coordination of circadian rhythms, including melatonin production, is governed by the interactions of a set of central clock genes. Recent studies have suggested that variants in clock genes are associated with cancer risk at multiple sites, including breast cancer, although few studies have considered potential interactions with shift work. Methods: This thesis examined relationships of both shift work and clock gene polymorphisms (and their interactions) with breast cancer risk in a case-control study of 1,142 cases and 1,178 controls. The association between light exposure and melatonin production was also investigated in a longitudinal biomarker study conducted among 123 nurses working a two-day, two-night rotating shift pattern. Results: In the case-control study, an association between breast cancer and ≥30 years of shift work (OR = 2.20, 95%CI = 1.13 – 4.28) was detected, although no relationship with short (0 – 14 years) or medium (15 – 29 years) term shift work was observed. As well, variants in 14 clock-related genes were not associated with breast cancer and there were no apparent interactions with shift work history. In the biomarker study, both peak melatonin levels and daily change in melatonin levels were similar when nurses were working their day and night shifts. Further, on the night shift, a slight inverse relationship between light and change in melatonin was observed (p = 0.04). Conclusions: Taken together, these results contribute to the understanding of both the association between shift work and breast cancer, and the biologic mechanisms underlying this relationship. Since shift work is required for many occupations, understanding the mechanisms through which it impacts breast cancer is important to the development of healthy workplace policy. / Thesis (Ph.D, Community Health & Epidemiology) -- Queen's University, 2012-09-26 20:59:40.209
4

Circadian Disruption by Light at Night: Implications for Mood

Bedrosian, Tracy A. 23 May 2013 (has links)
No description available.
5

Macroecological patterns of plant species and anthropogenic activities

Correa Cano, María Eugenia January 2015 (has links)
The study of macroecology not only identifies patterns in the distribution and abundance of species at large spatial and temporal scales, it also gives insight into the processes underlying those patterns. The contribution of this work is not limited to helping develop the field of ecology per se, but also provides important insights into the understanding of large scale processes like climate change, the spread of introduced species, pest control and how increasing pressure from anthropogenic activities threatens biodiversity and ecosystem services. During the first decade following its formal inception, most of the progress in macroecology was made through studies of animal species, and research into plant species continues to lag far behind. This thesis contributes to the study of the macroecology of plant species by examining some selected macroecological patterns that have been studied only for animal species and by including an important issue that might have significant effects on diverse macroecological patterns, namely anthropogenic activities. The second and third chapters of the thesis address the generalised individuals-area relationship (GIAR) and the patch individuals-area relationship (PIAR), two macroecological relationships not previously explored for plant species. I show for the first time the existence of negative GIARs at the intraspecific and interspecific levels in plant species, similar to those documented for animal species. Unlike animal species, I did not find a broadly consistent intraspecific PIAR in plant species; more than half of the tested species showed negative PIARs. The resource concentration hypothesis may help explain those positive PIARs that were observed. The fourth chapter considers the effect of past human activities on current patterns of plant species richness at a landscape scale. Using a detailed database on the historical anthropogenic activities for Cornwall, U.K., I examine the relationship between species richness and the area covered by each historical land-use at two different spatial resolutions (10km x 10km and 2km x 2km). I find that at the 10km x10km scale human activities carried out since the 17th and 19th centuries explain an important proportion of the variation in current plant species richness. In contrast, a model at 2km x 2km scale with upland woods and the total land area of a grid cell explain only 5% of the variation. The fifth and sixth chapters focus on how artificial light at night (ALAN), which has increasingly come to attention as a significant anthropogenic pressure on species, is interacting with the distributions of plant species. In the fourth chapter, I consider the plant family Cactaceae to determine the proportion of the global distribution ranges of species that is being influenced by ALAN, and how this changes with the size of these distribution ranges and over a 21-year period (1992 to 2012). I found that >80% of cacti species are experiencing ALAN somewhere in their distribution range, and that there is a significant upward trend in ALAN in the ranges of the vast majority of species. For the sixth chapter, I consider similar issues for the threatened plant species of Britain, exploiting new remote sensing imagery of nighttime lighting at a very fine spatial resolution (c.340x340m2). Only 8% of Britain is free of artificial light at night and in consequence a high number of threatened plant species have a high proportion of their range under some influence of ALAN.
6

Impact of different light sources on the responses of moth

Zhou, Yanhe January 2021 (has links)
In recent decades, the negative effects of artificial light at night on natural ecosystems have attracted the attention of ecologists. Studies have shown that artificial light at night leads to a considerable reduction in insects and has a worrying impact on terrestrial ecosystems, including nocturnal insects (e.g. Lepidoptera) such as moths. Warm white light is generally expected to have a lower ecological impact compared with cold white light which has a higher proportion of blue light (< 500 nm). The aim of this study is to investigate the impact of three light emitting diode (LED) light sources with different spectral power distributions on the responses of the greater wax moth (Galleria mellonella) under controlled experimental settings. In this experiment, three light sources with different spectral power distribution and dark condition were used and the start response time, time active, time flap wings, time flap wings / time active, main activity area and stop area of the greater wax moth were investigated. The light treatment used were: (1) darkness (n = 13); (2) warm-white light (correlated color temperature of 2675 K, n = 12); (3) white light (4070 K, n = 4); (4) cold white light (6200 K, n = 8). The experiment was performed in a rectangular light-tight box under controlled conditions. Main activity area showed significant difference between warm-white light and cold white light. With cold white light, a larger proportion of the moths were active in the area with the highest light levels, while the main activity area in the warm white light was in the zone with the lowest light levels. Other variables, however, did not show significant differences. The conclusion is that warm white light had a lower ecological impact than cold white light due to a larger proportion of moth is attracted to areas with stronger light. The results support the notion that in outdoor environments, warm white LEDs (maximum 3000 K) should be preferred compared to cold white light LEDs (over 3000 K), to reduce the impact on insects such as moths. The low correlated color temperature light sources used outdoors deserves more in-depth development and research.
7

Ecological Modelling of Lake Ecosystems: Integrating hydro-thermodynamics and biogeochemistry in a reduced complexity framework

López Moreira Mazacotte, Gregorio Alejandro 10 January 2019 (has links)
Freshwater lakes are among the most important ecosystems for both human and other biological communities. They account for about 87% of surface freshwater in the planet, thus constituting a major source of drinking water. They also provide a wide range of ecosystem services that go from the sustenance of a rich biodiversity to the regulation of hydrological extremes; from the provision of a means for recreation to the support of local economies, e.g., through tourism and fisheries, just to cite a few. Lakes are now also widely recognised as natural early warning systems, their responses potentially being effective indicators of local, regional and global scale phenomena such as acidification and climate change, respectively. This is because of their high sensitivity to environmental factors of the most diverse nature that can rapidly alter the course of their evolution. Examples of this are the observed abrupt shifts between alternative stable states in shallow lakes, which led them to become the archetype, go-to example in alternative stable state theory. Therefore, attaining a good scientific understanding of the many processes that take place within these ecosystems is fundamental for their adequate management. Among the tools that serve this purpose, ecological models are particularly powerful ones. Since their introduction in the 1960s, the development of mechanistic ecological models has been driven by their wide spectrum of potential applications. Nevertheless, these models often fall into one of the two following categories: overly simplistic representations of isolated processes, with limited potential to explain real-world observations as they fail to see the bigger picture; or overly complex and over-parameterised models that can hardly improve scientific understanding, their results being too difficult to analyse in terms of fundamental processes and controls. Moreover, it is now well known that an increased complexity in the mechanistic description of ecological processes, does not necessarily improve model accuracy, predictive capability or overall simulation results. To the contrary, a simpler representation allows for the inclusion of more links between model components, feedbacks which are usually overlooked in highly-complex models that partially couple a hydro-thermodynamic module to a biogeochemical one. However, ecological processes are now known to have the potential to significantly alter the physical response of aquatic ecosystems to environmental forcing. For example, steadily increasing concentrations of coloured dissolved organic carbon, a process known as brownification (also browning), as well as the intense phytoplankton blooms that characterise lakes undergoing severe nutrient enrichment, a process known as eutrophication, have been shown to have the potential to alter the duration of the stratified period, thermal structure and mixing regime of some lakes. In this thesis, with the aim of addressing the limitation of partially-coupled models to account for such feedbacks, we further develop a process-based model previously reported in scientific literature. Subsequent studies have already built upon this model in the last few years. In Chapter 2, we do so too by integrating hydro-thermodynamics and biogeochemistry in a reduced complexity framework, i.e., customising the model so that each version only includes the fundamental processes that, brought together, sufficiently describe the studied phenomena. Two case studies served the purpose of testing the adaptability and applicability of the developed model under different configurations and requirements. Limnological data for these two studies were measured at high spatial and temporal resolutions by means of an automated profiling system and recorded as part of two large-scale mesocosm experiments conducted in 2015 and 2016 at the IGB LakeLab in Lake Stechlin, Brandenburg, Germany. Meteorological datasets were also made available to us for both periods by the German Federal Environment Agency. The scope of the first experiment, which we describe in Chapter 3, was that of detecting any changes attributable to eutrophication and browning, in the competition for nutrients and light between four different groups of lake primary producers. These four groups are phytoplankton, periphyton, epiphyton and macrophytes. The model version for this study, therefore, includes equations for all four groups. By tailoring the model to these very specific needs with relative ease, we demonstrate its versatility and hint at its potential. The second experiment, described in Chapter 4, sought to shed light on the largely unknown effects of an increase in the diffuse luminance of the night sky that is due to artificial light at night (artificial skyglow) on lake metabolic rates, i.e., gross primary productivity, ecosystem respiration and net ecosystem productivity (the difference between the first two). For this purpose, an empirical equation for dissolved oxygen concentration was included, the parameters of which were estimated by means of a Markov Chain Monte Carlo sampling method within a Bayesian statistical framework, showing the compatibility, with these statistical methods, of our otherwise fully deterministic model. In Chapter 5, we present a theoretical study on the ecological controls of light and thermal patterns in lake ecosystems. A series of simulations were performed to determine in which cases ecological processes such as eutrophication and brownification may have an observable effect on the physical response of lakes to environmental forcing, which we assessed along a latitudinal gradient. Results show that, in general, across all examined latitudes, and consistent with previous studies, accounting for phytoplankton biomass results in higher surface temperatures during the warm-up phase, slightly lower water temperatures during the cool-down phase, and a shallower thermocline throughout the entire stratified period. This effect is relatively more important in eutrophic lakes where intense blooms are likely. This importance, however, decreases as lakes get browner. Finally, in line with the overall scope of the SMART EMJD, in Chapter 6 we illustrate the case of Ypacaraí Lake, the most important lake in landlocked Paraguay, hoping to provide an example of how interdisciplinary research and international intersectoral collaboration can help bridge the gap between science and management of freshwater ecosystems. This lake presents very special hydro-ecological conditions, such as very high turbidity that can impair phytoplankton growth despite its nutrient-based trophic state indices having consistently fallen within the hyper-eutrophic range in recent years. A strong interest in its complex functioning, through modelling, was taken early on. This led to a collaborative research line being established among several public and private institutions in Italy, Germany and Paraguay. Results so far include: • three concluded UniTN Master theses in Environmental Engineering, partly developed in Paraguay, the first two in collaboration with the “Nuestra Señora de la Asunción” Catholic University (UCNSA) and the third one with the National University of Asunción (UNA); • a collaborative UCNSA-UniTN research proposal submitted for consideration to receive funding through the PROCIENCIA Programme of the National Council of Science and Technology of Paraguay (CONACYT); and • the first multidisciplinary review that has ever been published about the case of Ypacaraí Lake, which highlights the importance of such a collaborative and integrative approach to further advance scientific knowledge and effectively manage this ecosystem.
8

Artificiellt ljus på natten : – en fenomenografisk studie om Sveriges kunskapsläge gällande ljusförorening som miljöproblem / Artificial light at night : – a phenomenographic study of Sweden’s state of knowledge regarding light pollution as an environmental problem

Ljungentorp, Robin January 2021 (has links)
Ljusförorening är ett miljöproblem vilket inbegripes som ett nytt och globalt framväxande fenomen i samband med himlaglim. Miljöproblemet i Sverige erkänns i viss mån med det nuvarande kunskapsläge. Dock saknas det en del kunskap för att komplettera ontologin för att bidra till ökad legitimitet för miljöproblemet bland allmänheten och Sveriges instanser. Studiens teoretiska analysramverket bestod av allmänningens tragedi, biogeoastronomiska natten och legitimitet, som användes till att analysera empirin härlett från studiens intervjumetod. Metoden hade en kvalitativ fenomenografisk ansats som innefattade ett strategiskt urval som var Sveriges instanser. Där uppdagades bristen på opinionsbildning i Riksdagen och Regeringen, trots att det finns motioner som har framlagts som vill att ljusförorening ska uppmärksammas, men att problemet hanteras snarare som en trafikfråga istället för miljöfråga. En del av förklaringen till varför det påverkar samverkan mellan Sveriges instanser för att motverka miljöproblemet. Ljusföroreningar påverkar ekologin och alla dess arter, varav krävs det tydligare riktlinjer för kommuner i deras belysningsplaner gällande att minska deras miljöpåverkan (särskilt för de nattaktiva arter som drabbas) för att nå målet till en mer hållbar belysning; varav ekologiska, ekonomiska och sociala aspekter vävs samman. Varav satsningar att bevara och etablera mörkerreservat är en pusselbit, vilket kan genomföras i samklang med Miljöbalkens författningar. / Light pollution is an environmental problem which is part of a new and globally emerging phenomenon in connection with skyglow. The environmental problem in Sweden is recognized to some extent with the current state of knowledge. However, there is also a lack of knowledge to complete the ontology in order to contribute to increased legitimacy for the environmental problem among the public and within its instances. The study's theoretical analytical framework consisted of the tragedy of the commons, biogeoastronomical night and legitimacy, which were used to analyze the empirical data derived from the study's interview method. The method had a qualitative phenomenographic approach that included a strategic selection of Sweden's instances. Where the lack of opinion formation was discovered in the Parliament and the Government, despite the fact that there is a proposition that has been presented that wants to light pollution to be noticed, but the problem is handled rather as a traffic issue instead of an environmental issue. Part of the explanation for why it affects the collaboration between Sweden's instances to counteract the environmental problem. Light pollution affects the ecology and all its species, which requires clearer guidelines for municipalities in their lighting plans regarding reducing their environmental impact (especially for the nocturnal species affected) in order to achieve the goal of more sustainable lighting; whereof which ecological, economic, and social aspects are woven together. In which investments to preserve and establish the dark sanctuary is a piece of the puzzle, which can be carried out in accordance with the Swedish Environmental Code constitutions.
9

Impacts of artificial light at night on space use and trophic dynamics of urban riparian mammals in Columbus, Ohio

Gilboy, Michael Joseph January 2022 (has links)
No description available.

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