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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.
211

Coupled sorption and transport of nonionic surfactants in natural soils

Chang, Eric Kenneth 05 1900 (has links)
No description available.
212

Site-directed mutagenesis of hydrogenase genes in Azotobacter chroococcum

Tito, Donald January 1992 (has links)
Accessory hydrogen uptake genes have been identified in a region of the Azotobacter chroococcum genome about 5 kb downstream of the hydrogenase structural genes (hupSL). DNA sequencing has revealed six genes (hupABYCDE) in this region. These genes are probably transcribed in the same direction as hupSL but are probably in a different operon. Mutational analysis had shown that disruption of the hupB, hupY, hupD and hupE genes gives a Hup$ sp-$ phenotype. In the present work additional mutational analysis, using Tn5, a Tn5 -derivative containing a promoterless lacZ gene, and a kanamycin resistance gene, confirms the direction of transcription and the separate nature of the hupABYCDE operon, and extends the region known to be necessary for Hup activity to hupA and possibly to 1.6 kb upstream of hupA.
213

Leaf Area Index in Closed Canopies: An indicator of site quality

Coker, Graham William Russell January 2006 (has links)
This study examined leaf area index (LAI) and relationships with corresponding tree growth, climate and soil characteristics across New Zealand forest plantations. The aim of this study was to determine if quick measures of projected leaf area across environmental gradients of New Zealand were an accurate indicator of site quality. Projected leaf areas of Pinus radiata D Don and Cupressus lusitanica Mills seedlings were measured using a Li-Cor LAI-2000 plant canopy analyser at 22 locations representing the soil and climatic diversity across New Zealand plantation forests. Seedlings planted at 40 000 stems per hectare were used to test treatment effects of fertiliser, site disturbance and species over a 4 year period. It was hypothesised that collected climate and soil information would explain differences in LAI development patterns across sites as the canopies approached site and seasonal maxima. Averaged across sites Cupressus lusitanica 7.28 (± 2.59 Std.) m2 m-2 had significantly (p = 0.0094) greater projected LAIs than Pinus radiata 6.47 (± 2.29) m2m-2. Maximum site LAI (LAImax) varied from 2.9 to 11.8 m2 m-2 for Pinus radiata and from 3.1 to 12.6 m2 m-2 for Cupressus lusitanica. LAImax of both species was significantly and positively correlated with vapour pressure deficit, soil carbon, nitrogen, phosphorous and CEC, but negatively with solar radiation, temperature and soil bulk density. A seasonal model of LAI across sites illustrated an 8.5% fluctuation in LAI of established canopies over the course of a year. Despite considerable variation in climate and soil characteristics across sites the combined effects of LAI at harvest and temperature were significantly correlated with site productivity (r2 = 0.84 and 0.76 for Pinus radiata and Cupressus lusitanica respectively). A national model of LAImax (r2 = 0.96) was proposed for Pinus radiata across climate and soil environments and the significance of LAImax as a component of site quality monitoring tools is discussed.
214

Assessment and optimisation of biological and physico-chemical techniques to monitor natural attenuation : application to three field sites

Budde, Eva January 2010 (has links)
Monitored natural attenuation is a cost-effective remediation strategy for the risk reduction of chemicals of concern (CoCs) in contaminated land and waters. This study considers three genuine sites in Germany, undergoing remediation. The objective was to measure a suite of physicochemical and biological parameters, and characterise the sites based on these data. The sites differed by their prevalent type of CoC, with one site impacted by polycyclic aromatic hydrocarbons (PAH), and two sites, situated in Hilden, impacted by BTEX. Sampling of microorganisms was performed using the industrial partner's newly developed matrix. This matrix was used for measurements of microbial respiration rate, ATP content, and 14C mineralisation rate, while groundwater samples were used for microbial luminescent biosensor assays (applying Escherichia coli HB101 pUCD607, Pseudomonas putida F1 Tn5, and Pseudomonas putida F1 TVA8), and for the chemical analysis of CoC, nitrate, iron, manganese, sulphate, and phosphate concentration. Microbial biosensors and respiration tests performed well in the identification of BTEX impacted wells at the Hilden sites, while the results for ATP content and 14C mineralisation were more ambiguous. Factor analysis showed a high impact of sulphate concentration. However, several strong correlations existed between measured parameters, so no single driving force, but a set of environmental influencing factors could be identified at the sites. The remediation progress could be demonstrated by the changes in cluster analyses between two time points. Sulphate and redox potential, the most influential parameters of the Hilden physico-chemical data set, were highlighted and confirmed by multiple linear regression, using a calculated attenuation rate as the dependent variable. Based on this outcome, a reduced sampling regime was proposed. This approach has the potential to reduce sampling costs and time at hydrocarbon contaminated sites, and has adequately demonstrated the use of statistical methods in assessing the remediation progress at a site.
215

Site-directed mutagenesis of yeast V-ATPase subunit d / Site directed mutagenesis of yeast vacuolar adenosine triphosphatase subunit d

Owegi, Margaret January 2005 (has links)
V-ATPases are enzymes found in all eukaryotic cells. They are organized into a peripheral membrane complex (V1) and an integral membrane complex (V0). VI is responsible for ATP hydrolysis and generates the energy used by Vo to pump protons from the cytosol into the vacuole. Subunit d is a component of Vo possibly located at the interface between V 1 and V. in the V-ATPase complex. We hypothesize that subunit d could be involved in the structural and functional coupling of VI and Vo. This was tested by generating point mutations along the open reading frame of subunit d from yeast. The mutations F94A, H128A, D173A, D217A, D261A, E317A, W325A, E328A and C329A, all in conserved regions of the protein sequence, were characterized by examining their growth phenotype and by assessing their ATPase specific activity, proton transport and V1Vo assembly in purified vacuolar membranes. The mutations E317A, W325A, E328A and C329A had reduced ATPase and proton transport activities. In addition, V1Vo assembly was compromised by the mutation W325A. Our results suggest that residues at the carboxyl-end of subunit d are important for ATPase activity, proton pumping and V1Vo assembly at the membrane. / Department of Chemistry
216

An investigation of the records kept by supervisors on construction sites

Assadi, Sami Omar Ali January 1997 (has links)
During the execution of a project constructed under the traditional contractual system, separate sets of site records are typically kept by each team of the two main parties on the construction site: the contractor, and the supervisor who looks after the client's interests. While the contractor's prime concern is to construct the project in accordance with the contract documents, one of the site supervisor's main functions is to keep a good record of what actually takes place during the construction process. Identifying the contractor's ability to complete the project on time, confirming that works are carried out correctly, and dealing with contractor's claims, are some instances where site records are likely to be used. It is therefore very important that the record-keeping system adopted by the supervising team provides detailed information in a readily-accessible format to ensure that facts can be established at any time during the construction period, or years later, when disputes may develop. This research programme studied the nature of existing site records kept by construction supervisors, to identify the types of records kept, the use made of them, and the problems and difficulties encountered in maintaining such records. It concentrated mainly on records of progress of construction works. The methodology adopted for undertaking this research, apart from reviewing the relevant literature, involved carrying out preliminary studies and conducting a national survey. The preliminary investigation comprised two studies as follows:• Studying site records kept on a project under construction. • Studying a set of site records kept on a completed project. The national survey, using mailed questionnaires, aimed at determining attitudes held and procedures currently adopted in the site record-keeping process in order that the present state of the art might be determined. The data gathered from the survey, in addition to resolving the research aims and objectives, has been used to investigate a number of assertions made regarding particular areas of construction supervisors' site records. The research findings revealed that the typical set of site records kept by construction supervisors is deficient in a number of respects. Various problems and difficulties relating to the procedures currently adopted by site staff have been identified which will typically affect the quality of these records and hence limit their value. If records are to be more useful, they must be more accessible and this suggests an increasing use of computers. With information held electronically in an organised system, the problems of accessibility should be reduced considerably. In addition to the general conclusions, a number of recommendations to improve site records have been made, including elements of quality procedures for record-keeping, and the potential use of an electronic diary software as a valuable tool for computerising one of the most important sources of site records.
217

A study on soil properties of hillside work area and topographic factors

TAKEDA, Yasuo, 竹田, 泰雄, TOMATSU, Osamu, 戸松, 修, TANAKA, Takafumi, 田中, 隆文, SAKURAI, Kiyoto, 桜井, 清人, KUMLUNG, Arunsiri, カムラン, アルンシリ 12 1900 (has links) (PDF)
農林水産研究情報センターで作成したPDFファイルを使用している。
218

Measurements of optical turbulence on the Antarctic Plateau and their impact on astronomical observations.

Travouilon, Tony, Physics, Faculty of Science, UNSW January 2005 (has links)
Atmospheric turbulence results taken on the Antarctic plateau are presented in this thesis. Covering two high sites: South Pole and Dome C, this work describes their seeing and meteorological conditions. Using an acoustic sounder to study the turbulence profile of the first kilo- metre of the atmosphere and a Differential Image Motion Monitor (DIMM) to investigate the integrated seeing we are able to deduce important at- mospheric parameters such as the Fried parameter (r0) and the isoplanatic angle (??0). It was found that at the two sites, the free atmosphere (above the first kilometer) was extremely stable and contributed between 0.2" and 0.3" of the total seeing with no evidence of jet or vortex peaks of strong turbulence. The boundary layer turbulence is what differentiates the two sites. Located on the Western flank of the plateau, the South Pole is prone to katabatic winds. Dome C on the other hand is on a local maximum of the plateau and the wind conditions are amongst the calmest in the world. Also linked to the topography is the vertical extent of the temperature in- version that is required to create optical turbulence. At the South Pole the inversion reaches 300 m and only 30 m at Dome C. This difference results in relatively poor seeing conditions at the South Pole (1.8") and excellent at Dome C (0.27"). The strong correlation between the seeing and the ground layer meteorological conditions indicates that even better seeing could be found at Dome A, the highest point of the plateau. Having most of the turbulence near the ground is also incredibly ad- vantageous for adaptive optics. The isoplanatic angle is respectively 3.3" and 5.7" for the South Pole and Dome C. This is significantly larger than at temperate sites where the average isoplanatic angle rarely exceeds 2". This means that wider fields can be corrected without the complication of conjugation to specific layers. For such purpose the potential is even more interesting. We show that ground conjugated adaptive optics would decrease the natural seeing to 0.22" for a wide field of 10 and 0.47" for a field of 1" at the South Pole. At Dome C the results are less impressive due to the already excellent seeing, but a gain of 0.1&quote can still be achieved over 1&quote. These results show that high angular resolution observations can be done better on the Antarctic plateau than any other known site.
219

The effect of limited site investigations on the design and performance of pile foundations.

Arsyad, Ardy January 2009 (has links)
The research presented in this thesis focuses on the quantification of the effect of limited site investigations on the design and performance of pile foundations. Limited site investigation is one of the main causes of structural foundation failures. Over the last 30 years, most site investigations conducted for infrastructure projects have been dictated by minimum cost and time of completion, rather than meeting the need to appropriately characterise soil properties (Institution of Civil Engineers 1991; Jaksa et al. 2003). As a result, limited site investigations remain common, resulting in a higher risk of structural foundation failure, unforeseen additional construction, and/or repair costs. Also, limited site investigations can result in over-designing foundations, leading to increased and unnecessary cost (ASFE 1996). Based on the reliability examination method for site investigations introduced by Jaksa et al. (2003) and performed by Goldsworthy (2006), this research investigated the effect of limited site investigations on the design of pile foundations. This was achieved by generating three-dimensional random fields to obtain a virtual site consisting of soil properties at certain levels of variability, and by simulating various numbers of cone penetration tests (CPTs) and pile foundations on the generated site. Once the site and the CPTs were simulated, the cone tip resistance (qc) was profiled along the vertical and horizontal axes. The simulated qc profiles yielded by the CPTs were then used to compute axial pile load capacity termed the pile foundation design based on site investigations (SI). In parallel, the axial pile load capacity of the simulated pile foundation utilising the “true” cone tip resistance along the simulated pile was also determined. This is termed “the true” design, or the benchmark pile foundation design, and referred to as pile foundation design based on complete knowledge (CK). At the end of this process, the research compared the pile foundation designs based on SI and those based on CK. The reliability of the foundation design based on SI was analysed with a probabilistic approach, using the Monte Carlo technique. The results indicated that limited site investigations have a significant impact on the design of pile foundations. The results showed that minimum sampling efforts result in a high risk of over- or under-designing piles. More intensive sampling efforts, in contrast, led to a low risk of under- or over-design. The results also indicated that the levels of spatial variability of the soil are notable factors that affect the effectiveness of site investigations. These results will assist geotechnical engineers in planning a site investigation in a more rational manner with knowledge of the associated risks. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1375097 / Thesis (M.Eng.Sc.) - University of Adelaide, School of Civil, Environmental and Mining Engineering, 2009
220

The effect of limited site investigations on the design and performance of pile foundations.

Arsyad, Ardy January 2009 (has links)
The research presented in this thesis focuses on the quantification of the effect of limited site investigations on the design and performance of pile foundations. Limited site investigation is one of the main causes of structural foundation failures. Over the last 30 years, most site investigations conducted for infrastructure projects have been dictated by minimum cost and time of completion, rather than meeting the need to appropriately characterise soil properties (Institution of Civil Engineers 1991; Jaksa et al. 2003). As a result, limited site investigations remain common, resulting in a higher risk of structural foundation failure, unforeseen additional construction, and/or repair costs. Also, limited site investigations can result in over-designing foundations, leading to increased and unnecessary cost (ASFE 1996). Based on the reliability examination method for site investigations introduced by Jaksa et al. (2003) and performed by Goldsworthy (2006), this research investigated the effect of limited site investigations on the design of pile foundations. This was achieved by generating three-dimensional random fields to obtain a virtual site consisting of soil properties at certain levels of variability, and by simulating various numbers of cone penetration tests (CPTs) and pile foundations on the generated site. Once the site and the CPTs were simulated, the cone tip resistance (qc) was profiled along the vertical and horizontal axes. The simulated qc profiles yielded by the CPTs were then used to compute axial pile load capacity termed the pile foundation design based on site investigations (SI). In parallel, the axial pile load capacity of the simulated pile foundation utilising the “true” cone tip resistance along the simulated pile was also determined. This is termed “the true” design, or the benchmark pile foundation design, and referred to as pile foundation design based on complete knowledge (CK). At the end of this process, the research compared the pile foundation designs based on SI and those based on CK. The reliability of the foundation design based on SI was analysed with a probabilistic approach, using the Monte Carlo technique. The results indicated that limited site investigations have a significant impact on the design of pile foundations. The results showed that minimum sampling efforts result in a high risk of over- or under-designing piles. More intensive sampling efforts, in contrast, led to a low risk of under- or over-design. The results also indicated that the levels of spatial variability of the soil are notable factors that affect the effectiveness of site investigations. These results will assist geotechnical engineers in planning a site investigation in a more rational manner with knowledge of the associated risks. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1375097 / Thesis (M.Eng.Sc.) - University of Adelaide, School of Civil, Environmental and Mining Engineering, 2009

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