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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.
181

APPLICATION OF SEISMIC MONITORING IN CAVING MINES

Abolfazlzadeh, Yousef 10 October 2013 (has links)
Comprehensive and reliable seismic analysis techniques can aid in achieving successful inference of rockmass behaviour in different stages of the caving process. This case study is based on field data from Telfer sublevel caving mine in Western Australia. A seismic monitoring database was collected during cave progression and breaking into an open pit 550 m above the first caving lift. Five seismic analyses were used for interpreting the seismic events. Interpretation of the seismic data identifies the main effects of the geological features on the rockmass behaviour and the cave evolution. Three spatial zones and four important time periods are defined through seismic data analysis. This thesis also investigates correlations between the seismic event rate, the rate of the seismogenic zone migration, mucking rate, Apparent Stress History, Cumulative Apparent Volume rate and cave behaviour, in order to determine failure mechanisms that control cave evolution at Telfer Gold mine.
182

Hydrogen induced hardening effects on alpha iron: a molecular dynamics study

Xie, Wenbo Unknown Date
No description available.
183

An Investigation of Two Modes of Plant Protection by the Biocontrol Agent Trichoderma virens

Crutcher, Frankie 2011 December 1900 (has links)
The biocontrol fungus Trichoderma virens is an avirulent symbiont with the ability to control plant disease by the production of antibiotic compounds, induction of plant resistance to pathogens, and mycoparasitism of other fungi. In this document, the analysis of a putative terpene biosynthesis gene cluster (vir cluster) in T. virens is described. The vir cluster contains genes coding for four putative cytochrome P450s, an oxidoreductase, MFS transporter, and a terpene cyclase. To determine the function of this cluster in secondary metabolism biosynthesis, a strain of T. virens with a deletion of the putative cyclase, vir4, was constructed. Deletion mutants were deficient in the synthesis of sesquiterpene volatiles and complementation of vir4 restored this loss in transformants, albeit at a lower level of production. An analysis of phenotypic characteristics between mutant and wild-type strains did not identify any differences when the strain interacted with other fungi, bacteria, or Arabidopsis seedlings. Paralogs of the gene encoding the elicitor SM1 were examined as genetic sources for potential elicitors to induce systemic resistance in plants. A search of the T. virens genome revealed the presence of three paralogs of sm1. One paralog, sm3, was found to be expressed when grown in association with plant roots and in still-culture. The Pichia pastoris protein expression system was used to generate sufficient quantities of SM3 to allow characterization of its function. The purified protein from the yeast system (picSM3) was shown to be glycosylated and to increase expression of a plant defense gene in maize seedlings. Mutant strains in which sm3 was either deleted or over-expressed were constructed to further explore the potential of sm3 as an elicitor of ISR. The differential production of SM1 and SM3 by these strains suggested that SM1 and SM3 may be co-regulated and native SM3 may be glycosylated. To further understand the role of a putative glycosylation site as a mechanism to prevent dimerization and subsequent elicitor activity, a point mutation was created in a sm1 deletion strain. Analysis of the behavior of the protein demonstrates that the putative glycosylation site is not involved in protein aggregation and deletion of this site does not prevent the protein from testing positive for glycosylation. We propose that SM1is not glycosylated but instead may interact with an oligosaccharide or other small molecule. However, the mechanism of dimerization in SM1 remains unknown.
184

Alcohol related vomiting in a New Zealand University sample: frequency, gender differences, and correlates

Blackmore, Natalie Patricia Irene January 2009 (has links)
The purpose of the study was to investigate the relationship, frequency, gender differences, situations and motivations of self-induced vomiting after drinking alcohol with disordered eating, alcohol use and psychopathology; with a nonclinical university sample of males and females in New Zealand. Participants were 102 male and 159 female university students ranging in age from 17-35 years who completed a survey designed for this study along with tests that measure eating disordered attitudes and behaviours, bulimia symptoms, depression and alcohol use. Overall, 90.04% of the sample reported that they drink alcohol and, of that subset, 57.58% of males and 42.26% of females reported having self-induced vomiting after drinking alcohol. The behaviour was related to eating pathology, depression and alcohol use with gender differences apparent. Specifically, on measures of disordered eating, females who self-induce vomiting after drinking alcohol scored higher than females who do not report the behaviour (no difference apparent for males), and overall, females scored higher than males. In terms of hazardous alcohol use, males who self-induce vomiting after drinking alcohol scored higher than males who do not with the same true for females, and overall males scored higher than females. In terms of drinking at the dependency level, individuals who reported self-induced vomiting after drinking alcohol drink at a more harmful level than those who do not (both males and females) and more males than females reported hazardous alcohol usage rates. When examining depressed symptoms, females who selfinduce vomiting after drinking alcohol reported more depressed symptoms than females who do not, with males who reported the behaviour endorsing less depressed symptoms than males who do not. Overall, females indicated more depressed symptoms than males. Persons who engaged in the behaviour were more likely to endorse it as being acceptable, with this trend being stronger for males. Females who self-induce vomiting after drinking were more likely to endorse symptoms of anorexia, bulimia and depression, whereas males who reported the behaviour were more likely to indicate harmful drinking levels, and perform the behaviour to carry on drinking. Thus, for males, self-induced vomiting after drinking alcohol was related to substance abuse whereas, for females, the behaviour may be more related to disordered eating.
185

Many-body effects in interionic interactions

Domene, Carmen January 2000 (has links)
No description available.
186

Electron-induced carbon tetrachloride Adsorption on Ice

Liu, Hanwen 06 November 2014 (has links)
Charge-induced adsorption is a subject of significance to environmental and biological systems. Ice surface is believed to get charged with potassium deposition. Compared to uncharged ice film, the work function of charged ice film is significantly reduced due to the formation of metastable delocalized excess surface electrons donated by potassium atoms on ice. This charging effect is found to be dependent on temperature. It is also reported that adsorption of carbon tetrachloride would occur drastically on charged ice surface while almost no adsorption was observed on uncharged ice surface at low temperature. In addition, the results strongly agree with the cosmic-ray-driven electron-induced reaction (CRE) model for ozone depletion.
187

Automated seismic event location by waveform coherence analysis

Grigoli, Francesco January 2014 (has links)
Automated location of seismic events is a very important task in microseismic monitoring operations as well for local and regional seismic monitoring. Since microseismic records are generally characterised by low signal-to-noise ratio, such methods are requested to be noise robust and sufficiently accurate. Most of the standard automated location routines are based on the automated picking, identification and association of the first arrivals of P and S waves and on the minimization of the residuals between theoretical and observed arrival times of the considered seismic phases. Although current methods can accurately pick P onsets, the automatic picking of the S onset is still problematic, especially when the P coda overlaps the S wave onset. In this thesis I developed a picking free automated method based on the Short-Term-Average/Long-Term-Average (STA/LTA) traces at different stations as observed data. I used the STA/LTA of several characteristic functions in order to increase the sensitiveness to the P wave and the S waves. For the P phases we use the STA/LTA traces of the vertical energy function, while for the S phases, we use the STA/LTA traces of the horizontal energy trace and then a more optimized characteristic function which is obtained using the principal component analysis technique. The orientation of the horizontal components can be retrieved by robust and linear approach of waveform comparison between stations within a network using seismic sources outside the network (chapter 2). To locate the seismic event, we scan the space of possible hypocentral locations and origin times, and stack the STA/LTA traces along the theoretical arrival time surface for both P and S phases. Iterating this procedure on a three-dimensional grid we retrieve a multidimensional matrix whose absolute maximum corresponds to the spatial and temporal coordinates of the seismic event. Location uncertainties are then estimated by perturbing the STA/LTA parameters (i.e the length of both long and short time windows) and relocating each event several times. In order to test the location method I firstly applied it to a set of 200 synthetic events. Then we applied it to two different real datasets. A first one related to mining induced microseismicity in a coal mine in the northern Germany (chapter 3). In this case we successfully located 391 microseismic event with magnitude range between 0.5 and 2.0 Ml. To further validate the location method I compared the retrieved locations with those obtained by manual picking procedure. The second dataset consist in a pilot application performed in the Campania-Lucania region (southern Italy) using a 33 stations seismic network (Irpinia Seismic Network) with an aperture of about 150 km (chapter 4). We located 196 crustal earthquakes (depth < 20 km) with magnitude range 1.1 < Ml < 2.7. A subset of these locations were compared with accurate locations retrieved by a manual location procedure based on the use of a double difference technique. In both cases results indicate good agreement with manual locations. Moreover, the waveform stacking location method results noise robust and performs better than classical location methods based on the automatic picking of the P and S waves first arrivals. / Die automatische Lokalisierung seismischer Ereignisse ist eine wichtige Aufgabe, sowohl im Bereich des Mikroseismischen Monitorings im Bergbau und von Untegrund Aktivitäten,  wie auch für die lokale und regionale Überwachung von natürlichen Erdbeben. Da mikroseismische Datensätze häufig ein schlechtes Signal-Rausch-Verhältnis haben müssen die Lokalisierungsmethoden robust gegen Rauschsignale und trotzdem hinreichend genau sein. Aufgrund der in der Regel sehr hochfrequent aufgezeichneten Messreihen und der dadurch sehr umfangreichen Datensätze sind automatische Auswertungen erstrebenswert. Solche Methoden benutzen in der Regel automatisch gepickte und  den P und S Phasen zugeordnete Ersteinsätze und Minimieren die Summe der quadratischen Zeitdifferenz zwischen den beobachteten und theoretischen Einsatzzeiten. Obgleich das automatische Picken der P Phase in der Regel sehr genau möglich ist, hat man beim Picken der S Phasen häufig Probleme, z.B. wenn die Coda der P Phase sehr lang ist und in den Bereich der S Phase hineinreicht. In dieser Doktorarbeit wird eine Methode vollautomatische, Wellenform-basierte Lokalisierungsmethode entwickelt, die Funktionen des Verhältnisses "Short Term Average / Long Term Average"  (STA/LTA) verwendet und keine Pickzeiten invertiert. Die STA/LTA charakteristische Funktion wurde für unterschiedliche Wellenform Attribute getestet, um die Empfindlichkeit für P und S Phasen zu erhöhen. Für die P Phase wird die STA/LTA Funktion für die Energie der Vertikalkomponente der Bodenbewegung benutzt, wohingegen für die S Phase entweder die Energie der horizontalen Partikelbewegung oder eine optimierte Funktion auf Basis der Eigenwertzerlegung benutzt wird. Um die Ereignisse zu lokalisieren wird eine Gittersuche über alle möglichen Untergrundlokalisierungen durchgeführt. Für jeden räumlichen und zeitlichen Gitterpunkt werden die charakteristischen Funktionen entlang der theoretischen Einsatzkurve aufsummiert. Als Ergebnis erhält man eine 4-dimensionale Matrix über Ort und Zeit des Ereignisses, deren Maxima die wahrscheinlichsten Lokalisierungen darstellen. Um die Unsicherheiten der Lokalisierung abzuschätzen wurden die Parameter der STA/LTA Funktionen willkürlich verändert und das Ereignis relokalisiert. Die Punktwolke aller möglichen Lokalisierungen gibt ein Maß für die Unsicherheit des Ergebnisses. Die neu entwickelte Methode wurde an einem synthetischen Datensatz von 200 Ereignissen getestet und für zwei beobachtete Datensätze demonstriert. Der erste davon betrifft induzierte Seismizität in einem Kohlebergbau in Norddeutschland. Es wurden 391 Mikrobeben mit Magnituden zwischen Ml 0.5 und 2.0 erfolgreich lokalisiert und durch Vergleich mit manuell ausgewerteten Lokalisierungen verifziert.Der zweite Datensatz stammt von einem Anwednung auf des Regionale Überwachungsnetz in der Region Campania-Lucania (Süditalien)  mit 33 seismischen Stationen und einer Apertur von etwa 150 km. Wir konnten 196 Erdbeben mit Tiefen < 20 km und Magnituden zwischen Ml 1.1 und 2.7 lokalisieren. Eine Untergruppe der eigenen Lokalisierungen wurde mit den Lokalisierungen einer Standard Lokalisierung sowie einer  hochgenauen Relativlokalisierung verglichen. In beiden Fällen ist die Übereinstimmung mit den manuellen Lokalisierungen groß. Außerdem finden wir, dass die Wellenform Summations Lokalisierung ronbust gegen Rauschen ist und bessere Ergebnisse liefert als die Standard Lokalisierung, die auf dem automatischen Picken von Ersteinsatzzeiten alleine basiert.
188

Allergen-induced change in airway responsiveness to direct and indirect stimuli in mild atopic asthmatics

2014 September 1900 (has links)
Methacholine (MCh) and mannitol challenges are tests used to assess airway responsiveness. It has been shown that airway responsiveness to direct bronchoconstrictors like MCh tends to increase following exposure to allergen but the response to mannitol an indirect stimuli, is not known. Furthermore, the provocative concentration causing a 20% decrease in Forced Expiratory Volume in one second (FEV1) for adenosine 5’ monophosphate (AMP) correlates better to sputum eosinophilia than MCh PC 20. Hence, we hypothesized that airway responsiveness will be greater when measured with mannitol than MCh. We studied airway responsiveness to MCh and mannitol first at 3 hours and then later at 24 hours after allergen challenge. The 3-hour study yielded results contrary to our hypothesis therefore a twenty-four hour study was undertaken. Ten mild atopic asthmatics who had a positive MCh challenge and an allergic response to allergen extracts such as cat, horse, and house dust mite completed the 3-hour study. Eleven mild atopic asthmatics with the criteria above completed the 24-hour study. Both studies were non-blinded, randomized clinical trials. Airway responsiveness to MCh was quantitated by changes in PC20. Airway responsiveness to mannitol was quantitated as PD15 in the 3-hour study and dose response ratio (DRR) in the 24-hour study. In both studies, the allergen challenges were separated by 14 days. Fractional exhaled nitric oxide measurements (FENO) were collected in both studies at varying time points to track airway inflammation. In the 3-hour study, the geometric mean MCh PC20 decreased significantly after allergen exposure from 0.88 mg/ml to 0.50 mg/ml (p = 0.02) indicating airway responsiveness to MCh increased. Conversely, the geometric mean mannitol PD15 increased significantly from 174 mg to 284 mg (p =0.02) indicating a decrease in airway responsiveness to mannitol. In the 24-hour study, the geometric mean MCh PC20 again decreased significantly from 5.9 mg/ml to 2.2 mg/ml (p= 0.01) after allergen exposure. The mannitol DRR increased significantly from 63 mg/∆%FEV1 to 158 mg/∆%FEV1 (p = 0.03). FENO levels increased significantly in MCh arm but not mannitol arm. That is pre allergen challenge versus 24 hours after allergen challenge (for MCh arm: 26 ppb pre to 55 ppb post; for mannitol arm: 31 ppb pre to 39 ppb post). In conclusion, at three and twenty-four hours after allergen challenge, a time when the airways are more responsive to MCh, there is a significant decrease in airway responsiveness to mannitol.
189

Genetic modifications of cytoplasmic thymidine kinase activity and the possible consequences on mutagen sensitivity

Dallol, Ashraf Rizk January 1999 (has links)
No description available.
190

Quantification of Vehicle-induced Turbulence on Roadways Using Computational Fluid Dynamics Simulation

Kim, Yesul 12 December 2011 (has links)
Turbulence is a significant factor in near-road air quality, as it affects the initial dilution, dispersion, and the ultimate fate of pollutants. This study used computational fluid dynamics simulations to model the turbulent kinetic energy (TKE) on roadways, focusing on vehicle-induced turbulence. TKE was shown to decay with different power-law exponents depending on vehicle types; vehicle speeds and winds affect TKE; and thermal impacts are negligible. It was found that TKE is superimposed for vehicles in series; TKE does not dissipate far laterally, and the side-by-side interactions are not significant regardless of the directions. Thus, TKE for different traffic compositions may be expressed as a sum of the contribution from each type of vehicle. Insights gained in this study may enable the quantification of TKE for various traffic scenarios based on TKE values of single vehicle of different types, and simplify the TKE estimations in regional air quality models.

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