• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 41
  • 5
  • 4
  • Tagged with
  • 51
  • 51
  • 51
  • 10
  • 10
  • 10
  • 10
  • 10
  • 9
  • 8
  • 7
  • 7
  • 7
  • 7
  • 6
  • 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

A conceptual model for sustainability (John Berger)

Wanden-Hannay (nee Witten-Hannah), Shalema January 2005 (has links)
The ideas of Berger are used in this thesis to explore humankind's struggle to achieve greater sustainability. In his descriptions of the peasantry and modern high-energy cultures of progress Berger insightfully crystallises and represents graphically the observation made by many authors writing in different contexts and from within various disciplines that there have been two fundamentally different systems of beliefs and values in history. His conception of ‘ cultures of survival’ and ‘cultures of progress ’ is used in this thesis to develop a conceptual model for sustainability. The basic idea underlying the conceptual model for sustainability is that cultural systems self-regulate or self-correct as they strive to achieve balance in their relationship to higher systems levels of the biosphere, while improving quality of life. Over large time scales self-regulation takes the form of quite radical transformations in cultural system's key defining beliefs and values. The model holds that the process of self-regulation results in societies moving back and forth along a cultural continuum of beliefs and values, represented at one end by Berger's cultures of survival and at the other by his cultures of progress. This system of self-regulation is fraught with risks arising from factors like the inherently conservative nature of cultural systems, which reduce the fit or alignment between systems of beliefs and values and their context and in doing so generate un-sustainability. The model suggests that over large spans of time movement back and forth along the cultural continuum creates the dynamic balance needed to achieve greater sustainability, at least if irreversible degradation of the biosphere's life-supporting systems and extinction can be avoided. This conceptual model for sustainability demonstrates the validity of the central hypothesis of the thesis, which is that Berger's ideas in the ‘Historical Afterword’ to ‘Pig Earth’ are important and have a valuable contribution to make to the discourse on sustainability. / Subscription resource available via Digital Dissertations only.
2

A conceptual model for sustainability (John Berger)

Wanden-Hannay (nee Witten-Hannah), Shalema January 2005 (has links)
The ideas of Berger are used in this thesis to explore humankind's struggle to achieve greater sustainability. In his descriptions of the peasantry and modern high-energy cultures of progress Berger insightfully crystallises and represents graphically the observation made by many authors writing in different contexts and from within various disciplines that there have been two fundamentally different systems of beliefs and values in history. His conception of ‘ cultures of survival’ and ‘cultures of progress ’ is used in this thesis to develop a conceptual model for sustainability. The basic idea underlying the conceptual model for sustainability is that cultural systems self-regulate or self-correct as they strive to achieve balance in their relationship to higher systems levels of the biosphere, while improving quality of life. Over large time scales self-regulation takes the form of quite radical transformations in cultural system's key defining beliefs and values. The model holds that the process of self-regulation results in societies moving back and forth along a cultural continuum of beliefs and values, represented at one end by Berger's cultures of survival and at the other by his cultures of progress. This system of self-regulation is fraught with risks arising from factors like the inherently conservative nature of cultural systems, which reduce the fit or alignment between systems of beliefs and values and their context and in doing so generate un-sustainability. The model suggests that over large spans of time movement back and forth along the cultural continuum creates the dynamic balance needed to achieve greater sustainability, at least if irreversible degradation of the biosphere's life-supporting systems and extinction can be avoided. This conceptual model for sustainability demonstrates the validity of the central hypothesis of the thesis, which is that Berger's ideas in the ‘Historical Afterword’ to ‘Pig Earth’ are important and have a valuable contribution to make to the discourse on sustainability. / Subscription resource available via Digital Dissertations only.
3

A conceptual model for sustainability (John Berger)

Wanden-Hannay (nee Witten-Hannah), Shalema January 2005 (has links)
The ideas of Berger are used in this thesis to explore humankind's struggle to achieve greater sustainability. In his descriptions of the peasantry and modern high-energy cultures of progress Berger insightfully crystallises and represents graphically the observation made by many authors writing in different contexts and from within various disciplines that there have been two fundamentally different systems of beliefs and values in history. His conception of ‘ cultures of survival’ and ‘cultures of progress ’ is used in this thesis to develop a conceptual model for sustainability. The basic idea underlying the conceptual model for sustainability is that cultural systems self-regulate or self-correct as they strive to achieve balance in their relationship to higher systems levels of the biosphere, while improving quality of life. Over large time scales self-regulation takes the form of quite radical transformations in cultural system's key defining beliefs and values. The model holds that the process of self-regulation results in societies moving back and forth along a cultural continuum of beliefs and values, represented at one end by Berger's cultures of survival and at the other by his cultures of progress. This system of self-regulation is fraught with risks arising from factors like the inherently conservative nature of cultural systems, which reduce the fit or alignment between systems of beliefs and values and their context and in doing so generate un-sustainability. The model suggests that over large spans of time movement back and forth along the cultural continuum creates the dynamic balance needed to achieve greater sustainability, at least if irreversible degradation of the biosphere's life-supporting systems and extinction can be avoided. This conceptual model for sustainability demonstrates the validity of the central hypothesis of the thesis, which is that Berger's ideas in the ‘Historical Afterword’ to ‘Pig Earth’ are important and have a valuable contribution to make to the discourse on sustainability. / Subscription resource available via Digital Dissertations only.
4

A conceptual model for sustainability (John Berger)

Wanden-Hannay (nee Witten-Hannah), Shalema January 2005 (has links)
The ideas of Berger are used in this thesis to explore humankind's struggle to achieve greater sustainability. In his descriptions of the peasantry and modern high-energy cultures of progress Berger insightfully crystallises and represents graphically the observation made by many authors writing in different contexts and from within various disciplines that there have been two fundamentally different systems of beliefs and values in history. His conception of ‘ cultures of survival’ and ‘cultures of progress ’ is used in this thesis to develop a conceptual model for sustainability. The basic idea underlying the conceptual model for sustainability is that cultural systems self-regulate or self-correct as they strive to achieve balance in their relationship to higher systems levels of the biosphere, while improving quality of life. Over large time scales self-regulation takes the form of quite radical transformations in cultural system's key defining beliefs and values. The model holds that the process of self-regulation results in societies moving back and forth along a cultural continuum of beliefs and values, represented at one end by Berger's cultures of survival and at the other by his cultures of progress. This system of self-regulation is fraught with risks arising from factors like the inherently conservative nature of cultural systems, which reduce the fit or alignment between systems of beliefs and values and their context and in doing so generate un-sustainability. The model suggests that over large spans of time movement back and forth along the cultural continuum creates the dynamic balance needed to achieve greater sustainability, at least if irreversible degradation of the biosphere's life-supporting systems and extinction can be avoided. This conceptual model for sustainability demonstrates the validity of the central hypothesis of the thesis, which is that Berger's ideas in the ‘Historical Afterword’ to ‘Pig Earth’ are important and have a valuable contribution to make to the discourse on sustainability. / Subscription resource available via Digital Dissertations only.
5

A conceptual model for sustainability (John Berger)

Wanden-Hannay (nee Witten-Hannah), Shalema January 2005 (has links)
The ideas of Berger are used in this thesis to explore humankind's struggle to achieve greater sustainability. In his descriptions of the peasantry and modern high-energy cultures of progress Berger insightfully crystallises and represents graphically the observation made by many authors writing in different contexts and from within various disciplines that there have been two fundamentally different systems of beliefs and values in history. His conception of ‘ cultures of survival’ and ‘cultures of progress ’ is used in this thesis to develop a conceptual model for sustainability. The basic idea underlying the conceptual model for sustainability is that cultural systems self-regulate or self-correct as they strive to achieve balance in their relationship to higher systems levels of the biosphere, while improving quality of life. Over large time scales self-regulation takes the form of quite radical transformations in cultural system's key defining beliefs and values. The model holds that the process of self-regulation results in societies moving back and forth along a cultural continuum of beliefs and values, represented at one end by Berger's cultures of survival and at the other by his cultures of progress. This system of self-regulation is fraught with risks arising from factors like the inherently conservative nature of cultural systems, which reduce the fit or alignment between systems of beliefs and values and their context and in doing so generate un-sustainability. The model suggests that over large spans of time movement back and forth along the cultural continuum creates the dynamic balance needed to achieve greater sustainability, at least if irreversible degradation of the biosphere's life-supporting systems and extinction can be avoided. This conceptual model for sustainability demonstrates the validity of the central hypothesis of the thesis, which is that Berger's ideas in the ‘Historical Afterword’ to ‘Pig Earth’ are important and have a valuable contribution to make to the discourse on sustainability. / Subscription resource available via Digital Dissertations only.
6

Bioconversion of paper mill lignocellulosic materials to lactic acid using cellulase enzyme complex and microbial cultures

Mukhopadhyay, Achira January 1900 (has links)
Master of Science / Department of Grain Science and Industry / Praveen V. Vadlani / Paper mill sludge is a solid waste generated from the paper-making industry. Cellulose in the sludge can be hydrolyzed into glucose using a cellulase enzyme complex, which can then be fermented to produce value added chemicals, such as lactic acid. The enzyme requirement for hydrolysis of the cellulose in paper sludge was benchmarked against paper pulp. Enzymatic requirements for complete conversion of cellulose in paper pulp was found to be 12 fpu cellulase, supplemented with 5 egu of beta-glucosidase per gram of cellulose. However, beta-glucosidase supplementation had to be increased to 38 egu to obtain a similar level of hydrolysis in the case of paper sludge indicating a decrease in enzyme activity due to sludge components. Response Surface Methodology (RSM) was used to study the lactic acid yield from paper sludge using enzyme dosage and temperature as parameters and operating in simultaneous saccharification and fermentation (SSF) mode. Maximum lactic acid yield of 0.75 g/g glucose was obtained within 36 hours using 10 fpu cellulase supplemented with 32 egu beta-glucosidase at a temperature of 39 degree C. Using the optimization function of the software, the optimal operational conditions for paper sludge hydrolysis were found to be 9 fpu cellulase, 12.5 egu beta-glucosidase at 40 degree C which resulted in a lactic acid yield of 0.58 g /g glucose. Lactic acid producing microbial cultures, Lactobacillus plantarum and Rhizopus oryzae were evaluated for fermentation of the pulp and sludge hydrolyzate at 125-ml shake flask and 2-L fermenter levels. In paper pulp media, the yields obtained by bacterial and fungal fermentations were 0.89 and 0.36 g/g glucose, respectively. In the case of paper sludge, the yield remained same, but inhibition of bacterial growth occurred. This resulted in lower substrate uptake and productivity than those obtained in paper pulp. On the other hand, fungal growth rate was enhanced due to the high solids content of paper sludge. The yield of lactic acid from paper sludge using L. plantarum and R. oryzae was 0.88 and 0.72 g/g glucose, respectively. Microbial cultures native to the sludge were isolated and evaluated for their performance of lactic acid production.
7

Crop model review and sweet sorghum crop model parameter development

Perkins, Seth A. January 1900 (has links)
Master of Science / Department of Biological and Agricultural Engineering / Kyle Douglas-Mankin / Opportunities for alternative biofuel feedstocks are widespread for a number of reasons: increased environmental and economic concerns over corn production and processing, limitations in the use of corn-based ethanol to 57 billion L (15 billion gal) by the Energy Independence and Security Act (US Congress, 2007), and target requirements of 136 billion L (36 billion gal) of renewable fuel production by 2022. The objective of this study was to select the most promising among currently available crop models that have the potential to model sweet sorghum biomass production in the central US, specifically Kansas, Oklahoma, and Texas, and to develop and test sweet sorghum crop parameters for this model. Five crop models were selected (CropSyst, CERE-Sorghum, APSIM, ALMANAC, and SORKAM), and the models were compared based on ease of use, model support, and availability of inputs and outputs from sweet sorghum biomass data and literature. After reviewing the five models, ALMANAC was selected as the best suited for the development and testing of sweet sorghum crop parameters. The results of the model comparison show that more data are needed about sweet sorghum physiological development stages and specific growth/development factors before the other models reviewed in this study can be readily used for sweet sorghum crop modeling. This study used a unique method to calibrate the sweet sorghum crop parameter development site. Ten years of crop performance data (Corn and Grain Sorghum) for Kansas Counties (Riley and Ellis) were used to select an optimum soil water (SW) estimation method (Saxton and Rawls, Ritchie et al., and a method that added 0.01 m m [superscript]-1 to the minimum SW value given in the SSURGO soil database) and evapotranspiration (ET) method (Penman-Montieth, Priestley-Taylor, and Hargraeves and Samani) combination for use in the sweet sorghum parameter development. ALMANAC general parameters for corn and grain sorghum were used for the calibration/selection of the SW/ET combination. Variations in the harvest indexes were used to simulate variations in geo-climate region grain yield. A step through comparison method was utilized to select the appropriate SW/ET combination. Once the SW/ET combination was selected the combination was used to develop the sweet sorghum crop parameters. Two main conclusions can be drawn from the sweet sorghum crop parameter development study. First, the combination of Saxton and Rawls (2006) and Priestley-Taylor (1972) (SR-PT) methods has the potential for wide applicability in the US Central Plains for simulating grain yields using ALMANAC. Secondly, from the development of the sweet sorghum crop model parameters, ALMANAC modeled biomass yields with reasonable accuracy; differences from observed biomass values ranged from 0.89 to 1.76 Mg ha [superscript]-1 (2.8 to 9.8%) in Kansas (Riley County), Oklahoma (Texas County), and Texas (Hale County). Future research for sweet sorghum physiology, Radiation Use Efficiency/Vapor Pressure Deficit relationships, and weather data integration would be useful in improving sweet sorghum biomass modeling.
8

Atrazine best management practices: impact on water quality

Steele, Kelsi Lynne January 1900 (has links)
Master of Science / Department of Biological & Agricultural Engineering / Philip L. Barnes / Wichita, Kansas water supply is derived from multiple sources. Unfortunately, these sources are not expected to meet the future needs of the population. This predicted water shortage led to the development of the Equus Beds Recharge Project, to investigate artificial recharge as a solution to meet future water demands. This project focuses on the Little Arkansas River as a source of this recharge water. The Kansas Department of Health and Environment set a daily 3[Mu]g/L standard for the recharged water as opposed to surface waters used directly for drinking water which can't exceed a yearly average atrazine concentration of 3[Mu]g/L. During 2005, five sub-watersheds within the Little Arkansas River watershed were instrumented to collect water quality samples and measure flow rate to calculate daily contaminant loadings. Three of the sub-watersheds used atrazine best management practices (BMPs) applied to grain sorghum while the remaining two sub-watersheds maintained existing farm practices. During 2007, monitoring continued and additional atrazine BMPs were applied to corn grown in the treated sub-watersheds. During both 2006 and 2007, water quality monitoring was used to examine water quality parameters throughout the entire watershed. Watershed-scale monitoring allowed for pollutant transport patterns to emerge both spatially and temporally and indicated potential sources of the pollutants. In this particular study, atrazine and sediment loss were the two most important water quality parameters. Results from this study showed that by using BMPs the concentration of atrazine was decreased by greater than 40% in 2006 when compared to the atrazine concentration from those areas without BMPs. A 5% reduction was seen in 2007, which was due to differences in precipitation and runoff between the two years. There was no reduction in sediment losses between the treated and untreated watersheds during 2006, leading to the conclusion that additional practices would be needed to reduce sediment losses as well as any pollutants associated with sediment loss (ex nutrients absorbed to the sediments). During 2007, sediment, nitrogen, and phosphorus were 66%, 60%, and 55% lower respectively in the treated versus untreated sub-watershed. These 2007 differences were related to rainfall pattern differences in the sub-watersheds.
9

Hydrogeochemical and mineralogical evaluation of groundwater arsenic contamination in Murshidabad district, West Bengal, India

Neal, Andrew W. January 1900 (has links)
Master of Science / Department of Geology / Saugata Datta / More than 75 million people in the Bengal Delta of eastern India and Bangladesh are exposed to drinking water with dangerously high arsenic (As) concentrations; the worst case of environmental poisoning in human history. Despite recognition of dangers posed to chronic exposure to drinking water with elevated As, its biogeochemical cycle is inadequately constrained in groundwater flow systems due to its complex redox chemistry and microbially-mediated transformations. Arsenic concentrations in Bengal Delta sediments are comparable to global averages, but its highly heterogeneous spatial distribution (on scales of meters to kilometers) in sediments and groundwaters is poorly understood. Though many research efforts have targeted understanding this heterogeneity in Bangladesh, less work has been done in eastern India. Murshidabad (23°56.355‘N, 88°16.156‘E), an eastern district in West Bengal, India, where groundwaters are highly As-affected (~4000 μg/l), was chosen as our study area. Research objectives were: (1) characterize sediment cores (mineralogically, geochemically) and groundwaters (hydrochemically, isotopically) in areas with contrasting As concentrations—west (low-As) and east (high-As) of river Bhagirathi, a major distributary of Ganges flowing through the heart of Murshidabad; (2) describe and understand the extent of spatial variability, laterally and vertically, of dissolved As concentrations in shallow (< 60 m) aquifers, comparing sediment core chemistry to water chemistry; (3) identify source(s) of aquifer recharge and (4) role(s) of inorganic carbon within the aquifer to understand the bioavailability and mobilization of As from sediments to groundwaters. Mineralogical differences between high-As (grey) and low-As (orange-brown) sediments, were the presence of greater amounts of micas, Fe- and Mg-rich clays, amphiboles, carbonates, and apatite in high-As sediments; these were virtually absent from low-As sediments. In high-As areas, As was associated with amorphous and poorly-crystalline Fe-oxyhydroxide phases and labile (specifically-sorbed) phases, especially where Fe(II):Fe[subscript]T was high in the sediments. High-As groundwaters had high As(III):As[subscript]T, iron, bicarbonate, phosphate, and ammonium, and low concentrations of chloride and sulfate. Dry season precipitation was probably the main source of aquifer recharge; lighter values of [superscript]13C in dissolved inorganic carbon resulted from oxidation of natural organic matter. This study points to an idea that both microbially-mediated oxidation-reduction and competitive ion-exchange processes occurring in shallow aquifers of Murshidabad drive As mobilization and sequestration by aquifer sediments.
10

A climatology of air pollution in the Kansas City metropolitan area.

Sando, Thomas Roy January 1900 (has links)
Master of Arts / Department of Geography / Douglas G. Goodin / My thesis characterizes the temporal and spatial behavior of ozone and fine particulate matter in the Kansas City metropolitan area. I also investigate the capability of a synoptic weather typing scheme, the Spatial Synoptic Classification, to characterize and explain the behavior of ozone and fine particulate matter in the Kansas City area. Daily maximum ozone concentrations from nine active ozone monitoring stations and daily average particulate concentrations six active PM2.5 monitoring stations were compared to daily SSC weather type records from 2004-2010. Analysis of Variance (ANOVA) tests were conducted on the ozone and PM2.5 data to analyze temporal and spatial behavior. A non-parametric recursive partitioning technique was used to create a conditional inference tree-based regression model to analyze the association between the different SSC weather types and the selected pollutants. The ANOVA results showed significant seasonal trends with both pollutants. In general, ozone concentrations are typically lower in the spring and autumn months and higher during the summer months. PM2.5 concentrations were not as dependent on the season, however, they did tend to be higher in the late summer months and lower in the autumn months. The results also showed significant differences for both pollutants in average concentration depending on location. The ozone concentrations generally tended to be higher in the areas that are located downwind of Kansas City and lowest at the station located in the middle of the urban area. Fine particulates also seemed to be highest in the downwind portion of the urban area and lowest in the region upwind of the city. The conditional inference tree showed that higher concentrations of both pollutants are associated with tropical air masses and lower concentrations are associated with polar air masses.

Page generated in 0.1093 seconds