Dissertations / Theses on the topic 'Systems of exposure'
To see the other types of publications on this topic, follow the link: Systems of exposure.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Systems of exposure.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Berdiñas, Torres Verónica J. "Exposure systems and dosimetry of large-scale in vivo studies /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17429.
Full text
2
Wollman, Lila Buls, and Lila Buls Wollman. "Plasticity of Brainstem Motor Systems in Response to Developmental Nicotine Exposure." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/626307.
Full textAbstract:
Developmental nicotine exposure (DNE) is known to cause abnormal development of multiple brain regions and results in impaired control of breathing and altered behaviors that rely on proper coordination of the muscles of the tongue. The adverse effects of nicotine are presumably caused by its actions on nicotinic acetylcholine receptors (nAChRs), which modulate fast-synaptic transmission and play a prominent role during brain development. Previous work has shown that DNE alters nAChR function in multiple brainstem regions (Pilarski et al., 2012, Wollman et al, 2016). Moreover, DNE causes multiple changes to XIIMNs, which innervate the muscles of the tongue (Powell et al., 2016, Powell et al., 2015, Pilarski et al., 2011). These changes likely reflect both altered development as a primary outcome of the chronic presence of nicotine, as well as, homeostatic adjustments made in an attempt to maintain normal motoneuron output. With the experiments described here, we tested the hypothesis that DNE alters the development of fast-synaptic transmission to XIIMNs, which, along with intrinsic properties of these neurons, is a main determinant of motor output to the muscles of the tongue. Additionally, we tested the hypothesis that DNE alters the function of nAChRs located on multiple brainstem neurons, including those that modulate fast-synaptic transmission to XIIMNs. For these experiments, we used whole cell patch clamp recordings from XIIMNs in a transverse slice of the medulla, and extracellular recordings from the 4th cervical ventral root in the brainstem spinal cord, split bath preparation. All preparations were obtained from control or DNE neonatal rats in the first week of life. Overall, the results of these experiments show that DNE alters fast-synaptic transmission to XIIMNs, which likely reflects appropriate homeostatic adjustments aimed at maintaining normal motor output at rest. However, these results also show that nAChR function is significantly altered by DNE, indicating fast-synaptic transmission may not be appropriately modulated in response to increased release of acetylcholine (ACh), the endogenous neurotransmitter for nAChRs.
3
Weighman, Kristi Kay. "Mapping dynamic exposure: constructing GIS models of spatiotemporal heterogeneity in artificial stream systems." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1555337508685485.
Full text
4
Neal, Alexandra Elyse. "Changes in Behavior as A Result of Exposure to Naproxen: Mimicking Natural Systems." Bowling Green State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1460035559.
Full text
5
De, Hoogh Cornelis. "Estimating exposure to traffic-related pollution within a GIS environment." Thesis, University of Northampton, 1999. http://nectar.northampton.ac.uk/2816/.
Full textAbstract:
This thesis applies, evaluates and compares methods for estimating exposure to traffic-related pollution within a GIS environment. The methods were used in two contrasting case studies; Greater London and Sheffield, where they were selected on basis of data availability and resolution. The methods used in this research were CALINE3, DMRB, ADMS-Urban and ISC3 (air pollution dispersion models), kriging and co-kriging (spatial interpolation), SAVIAH (regression method) and traditional exposure indicators. Calculated estimates were validated by comparing them to monitored NO2 data. In the Sheffield case study the best methods were then used to analyse relationships between traffic-related pollution and respiratory health. Evaluation of the performance of the various methods found that none of the methods used in Greater London worked very well, although ISC3 and kriging tended to give more reliable results. In Sheffield DMR.B and SAVIAH gave the best estimates of monitored pollution levels. Traditional exposure indicators were only used in Sheffield of which ‘density of main roads within 150 metres’, ‘traffic flow within 150 metres’ and ‘HGV flow within 150 metres’ provided the most reliable estimates. In general, the quality of all exposure measures was highly dependent on the quality of input data. This is largely due to the fact that most variation of traffic-related pollution occurs close to main roads. In Greater London the quality of data was clearly inadequate. In Sheffield, where data was of a higher quality, results were better. No substantial or significant associations were found between the exposure measures and health outcome in the Sheffield case study. In Sheffield, this research also showed that passive sampling of NO2 provided a reliable measure of relative levels of air pollution across an urban area. It also showed that none of the models were able to detect raised NO2 concentrations due to accumulation of pollution from the city, as a result of wind direction. The results of this research show that, although the methods used here can help in the investigation of relationships between traffic-related pollution and health, there is a major need to improve methods for modelling exposure to air pollution. An important development could be to link different models together within a GIS environment, in order to improve the ability to use available information and exploit the different capabilities of the models. In order to detect the effects of traffic-related pollutants on chronic health, estimates are needed across large populations. Linkage of the methods applied here, would be particularly useful to model spatial and temporal variations in these types of studies
6
Gulliver, John. "Space-time modelling of exposure to air pollution using GIS." Thesis, University of Northampton, 2002. http://nectar.northampton.ac.uk/2810/.
Full textAbstract:
This thesis develops, tests and applies methods for space-time modelling of exposure to air pollution using GIS. This involves linkage of five main sub-models: a traffic model, a model of urban air pollution - combining local and ‘background’ pollution models - a network analysis tool for modelling exposure during journeys, and a time-activity model. The model can provide exposure estimates for individuals or population groups. The study took place entirely within Northampton, UK. The model used to estimate hourly PM10 concentrations at outdoor locations gave a moderate fit to monitored data. Results were shown to be comparable with the best results from other studies. This research also found a strong, linear relationship between concentrations of PM10 during simultaneous monitoring of walking and in-car concentrations. This relationship was used to calibrate modelled outdoor pollution levels to give in-car concentrations. Modelled journey- time exposures for walking performed equally with predictions made using a fixed- site monitor located close to journey routes. The model did not perform as well as the fixed-site monitor in predicting in-car exposures. The application of the model to a walk-to-school policy, in which modelled local traffic levels were reduced by 20%, demonstrated that the benefits of the reduction were not spread evenly across a sample of schoolchildren, but varied depending on the route used to school and the location of homes and schools. For those switching between car and walk there may be positive or negative effects of the policy in terms of savings in average hourly exposures, depending on their specific journey and time activity patterns. The results from this research showed that, although the model worked reasonably well in estimating exposures, a number of improvements are needed. These include better models of background concentrations, more detailed models of in-car conditions, and extending exposure modelling to include dose-response estimates
7
Inderbitzin-Köhler, Silvio. "Effects of prenatal benzodiazepine exposure on opioid systems of the male rat brain /." [S.l.] : [s.n.], 1995. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=11070.
Full text
8
Knaup, Kaprice J. "Evaluation of systems for measuring employee exposure to ultrasonic sound at Company XYZ." Online version, 2008. http://www.uwstout.edu/lib/thesis/2008/2008knaupk.pdf.
Full text
9
Elgethun, Kai. "Global positioning system (GPS) tracking to characterize children's exposure to pesticides /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/8474.
Full text
10
Kim, Jeong Ah. "The role of legislation in driving good occupational health and safety management systems: A comparison of prescriptive based legislation." Queensland University of Technology, 2004. http://eprints.qut.edu.au/15966/.
Full textAbstract:
Countries seek to control exposure to hazardous substances and environments by the enactment of legislation. In the past thirty years, two major different approaches to occupational health and safety legislation have been devleoped by countries around the world. The performance-based legislative approach has been linked with the emergence of occupational health and safety management systems but no research has previously been done to determine whether or not the legislative approach taken by government influences the introduction or form of occupational health and safety management systems used by organisations. Similarly, although the reasons why Australia and other countries have moved to performance-based legislation have been explained in terms of social, political and economic factors that influenced the change, little research has been done on the effectiveness of this approach compared with the prescriptive approach of countries such as Korea. -I- The overall aim of this research is to develop a conprehensive understanding of the management of expusre to heavy metals in selected industries in Korea and Australia. The specific objectives of the study are to determine: The effectiveness of heavy metal exposure management in the fluorescent lamp manufacturing industry in Korea, and an Oral Health Service, and lead-risk workplaces in Queensland, Australia; The management of the legislative arrangements for health surveillance in Korea and Queensland, Australia; The characteristics of the occupational health and safety management systems that are in use in the heavy metal industries in Korea in Australia; and The effectiveness of prescriptive and performance based legislative systems in protecting the health and safety of workers in heavy metal based industries. Secondary analysis of biological monitoring data from 6 fluorescent lamp manufacturing companies (8 workplaces) in Korea was used to examine the extent of mercury exposure and the effectiveness of the health surveillance system in that country. A survey of dental workers in an oral health service in Queensland provided data on the extent of mercury exposure to the workforce and workers' attitudes to the management of occupational risks. The efficiency of the lead health surveillance in Queensland was examined by way of a questionnaire survey of lead designated doctors in the state. A survey of registered lead-risk companies and the oral health servies in Queensland, and 5 of the fluorescent lamp manufacturing companies in Korea provided data on the occupational health and safety management systems in place in these organisations. The health surveillance system for mercury exposed workers in Korea was found to have reduced the incidence of workers with biological levels of mercury above the Baseline Level from 14% in 1994 to 7% in 1999. Bilogical testing of dental workers in Queensland discovered no workers with biological levels of mercury approaching the Baseline Level and air monitoring failed to locate any areas where workers were likely to be exposed to levels approaching the Workplace Exposure Standard. The staff of the Oral Health Service were generally aware of the occupational health and safety management systems in place but only 43% felt that mercury management in the workplace effectively prevented exposure. The lead surveillance system in Queensland was found to be inadequately managed with approximately 37% of registered doctors no longer practicing in the field and their being no way for the government to collect reliable data on the extent of lead exposure in workplaces. The occupational health and safety management systems in the companies surveyed in Queensland and Korea were found to be influenced by the legislative arrangements in place in each of the locations. The Korean systems were more geared to meeting the regulatory requirements whereas the Queensland systems were geared more towards a risk management approach. However substantial differences were also noted depending on the size of the organisation in each case. Legislative arrangements in Korea and Queensland were found to provide reasonable protection from heavy metal exposure to workers however improvements in both systems are needed. The legislation was also found to influence the occupational health and safety management systems in place with performance-based legislation producing systems having a wide risk management focus while a narrower regulatory based focus was noted in Korea where more prescriptive legislation is in force. A confounding factor in the nature of the occupational health and safety management system in place is the size of the organisation and particular attention needs to be paid to this when legislative approaches are considered.
11
Kim, Jeong-Ah. "The role of legislation in driving good occupational health and safety management systems: A comparison of prescriptive based legislation." Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/15966/1/Jeong-ah_Kim_Thesis.pdf.
Full textAbstract:
Countries seek to control exposure to hazardous substances and environments by the enactment of legislation. In the past thirty years, two major different approaches to occupational health and safety legislation have been devleoped by countries around the world. The performance-based legislative approach has been linked with the emergence of occupational health and safety management systems but no research has previously been done to determine whether or not
the legislative approach taken by government influences the introduction or form of occupational health and safety management
systems used by organisations. Similarly, although the reasons why Australia and other countries have moved to performance-based
legislation have been explained in terms of social, political and economic factors that influenced the change, little research has been
done on the effectiveness of this approach compared with the prescriptive approach of countries such as Korea.
-I-
The overall aim of this research is to develop a conprehensive
understanding of the management of expusre to heavy metals in selected industries in Korea and Australia.
The specific objectives of the study are to determine:
The effectiveness of heavy metal exposure management in the fluorescent lamp manufacturing industry in Korea, and an Oral Health Service, and lead-risk workplaces in Queensland, Australia; The management of the legislative arrangements for health surveillance in Korea and Queensland, Australia;
The characteristics of the occupational health and safety management systems that are in use in the heavy metal industries in Korea in Australia; and The effectiveness of prescriptive and performance based legislative systems in protecting the health and safety of workers in heavy metal based industries.
Secondary analysis of biological monitoring data from 6 fluorescent lamp manufacturing companies (8 workplaces) in Korea was used to examine the extent of mercury exposure and the effectiveness of the health surveillance system in that country. A survey of dental workers in an oral health service in Queensland provided data on the extent of mercury exposure to the workforce and workers' attitudes to the management of occupational risks. The efficiency of the lead health surveillance in Queensland was examined by way of a questionnaire survey of lead designated doctors in the state. A survey of registered lead-risk companies and the oral health servies in Queensland, and 5 of the fluorescent lamp manufacturing companies in Korea provided data on the occupational health and safety management systems in place in these organisations.
The health surveillance system for mercury exposed workers in Korea was found to have reduced the incidence of workers with biological
levels of mercury above the Baseline Level from 14% in 1994 to 7% in 1999. Bilogical testing of dental workers in Queensland discovered no
workers with biological levels of mercury approaching the Baseline Level and air monitoring failed to locate any areas where workers were likely to be exposed to levels approaching the Workplace Exposure Standard. The staff of the Oral Health Service were generally aware of the occupational health and safety management systems in place but only 43% felt that mercury management in the workplace effectively prevented exposure.
The lead surveillance system in Queensland was found to be inadequately managed with approximately 37% of registered doctors
no longer practicing in the field and their being no way for the government to collect reliable data on the extent of lead exposure in workplaces. The occupational health and safety management systems in the companies surveyed in Queensland and Korea were found to be influenced by the legislative arrangements in place in each of the locations. The Korean systems were more geared to meeting the regulatory requirements whereas the Queensland systems were geared more towards a risk management approach. However
substantial differences were also noted depending on the size of the organisation in each case.
Legislative arrangements in Korea and Queensland were found to provide reasonable protection from heavy metal exposure to workers however improvements in both systems are needed. The legislation was also found to influence the occupational health and safety management systems in place with performance-based legislation producing systems having a wide risk management focus while a narrower regulatory based focus was noted in Korea where more
prescriptive legislation is in force. A confounding factor in the nature of
the occupational health and safety management system in place is the size of the organisation and particular attention needs to be paid to this
when legislative approaches are considered.
12
Ferreira, Martins Vânia. "Air quality in subway systems: particulate matter concentrations, chemical composition, sources and personal exposure." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/399787.
Full textAbstract:
Air quality sampling campaigns both on platforms and inside trains of three European subway systems (Barcelona, Athens and Oporto) were conducted in order to characterise PM, investigating its variability, to better understand the main factors controlling it, and therefore the way to improve air quality.
PM concentrations varied among the European subway platforms, and also within the same underground system, mainly associated to differences in the design of the stations and tunnels; system age; train frequency; ventilation and air-conditioning systems; passenger densities; power system (catenary vs. third rail); composition of wheels, rail tracks, brake pads and power supply materials; rail tracks geometry (curved vs. straight and sloped vs. levelled); and outdoor air quality. PM concentrations displayed clear diurnal patterns among the three European subway platforms, depending largely on the operation and frequency of the trains and the ventilation system.
In the Barcelona subway system, the new stations showed on average lower PM concentrations than those in the old conventional stations, mainly related to the stations design (with platform screen door systems), but also due to the lower train frequency and more advanced ventilation setup. Furthermore, PM concentrations on the platforms in the colder period were higher than in the warmer period, mainly due to weaker ventilation during the colder period. In Athens, the mean PM concentrations in a new station located in the periphery of the line were lower than in a central station, attributed not only to the age and location of the station, but also to the lower train frequency.
Measurements carried out in the three subway systems performed on stations with similar platform design were compared. The highest PM concentrations were observed in the Oporto subway station because the line is composed by curved and/or sloping rail tracks (resulting in a higher emission of rail wear particles) and it has a higher train frequency. Furthermore, mechanical forced ventilation is inexistent in this subway system.
The use of air-conditioning inside the trains was an effective approach to reduce exposure levels, being more efficient removing coarser particles. Having the carriage windows open promotes the entrance of polluted air from tunnels and platforms into
the trains. Nevertheless, even when the carriage windows are closed and the air conditioning system is switched on, the PM concentrations inside the trains continue to be greatly affected by the surrounding air quality conditions.
Despite the lower PM2.5 (PM with aerodynamic diameter <2.5 µm) concentrations with respect to those on station platforms, the highest dose was observed inside the trains due to the longer exposure time. Overall, during a subway commuting travel, roughly 80% of the inhaled mass of subway PM2.5 was deposited in the respiratory tract. The dose, and its distribution on the different regions of the respiratory tract, is mainly dependent on the particle size and exposure concentrations.
Chemically, subway PM2.5 on the platforms is comprised of iron, total carbon, crustal matter, secondary inorganic compounds, insoluble sulphate, halite and trace elements. Fe was the most abundant element in PM2.5 found on the platforms, with relative contribution to the bulk PM2.5 ranging from 19 to 46%, which is generated mainly from mechanical wear and friction processes at rail-wheel-brake interfaces. The trace elements with highest enrichment in the subway PM2.5 were Ba, Cu, Mn, Zn, Cr, Sb, Sr, Ni, Sn, As, Co and Zr. Differences in metal concentrations in PM among the stations and subway systems might be associated to the different chemical composition of wheels, rails, brakes, and power supply materials.
A source apportionment analysis allowed the identification of outdoor (sea salt, fuel oil combustion and secondary) and subway sources on platforms, the latter including all emissions generated within the subway system.
13
Boudalia, Mohamed. "Effect of Early Exposure to Technology on Student Satisfaction with Online Education." ScholarWorks, 2018. https://scholarworks.waldenu.edu/dissertations/5166.
Full textAbstract:
U.S. student enrollment in online classes in the higher education sector has grown rapidly since 2001. Researchers have found that student satisfaction often leads to higher student retention, yet more research was needed to understand reasons for student satisfaction with online education. The purpose of this nonexperimental study was to examine the relationship between students' early exposure to technology (i.e., before college) and their satisfaction with online education in college. The unified theory of acceptance and use of technology were the theoretical framework. A convenience sample of 103 participants from the population of online students at colleges and universities in the United States took a survey on their past exposure to information and communication technology (ICT); their expectations for, and willingness to continue using ICT; and their satisfaction with online education. Several statistical tests, such as ANOVA, Spearman Rho correlation, and t-tests were conducted to analyze collected responses. Results indicated there was an indirect relationship between the early exposure to technology and student satisfaction based on the statistically significant correlation found between the early exposure to technology and effort expectancy, then between effort expectancy and use behavior and finally between use behavior and student satisfaction. By implementing study findings, educators and managers may be better able to bring positive social changes necessary to prepare all students and workers for the technology-driven education and the workplace regardless of their socioeconomic status.
14
Jiang, Xiaoshan. "A strategy to study pathway cross-talks of cells under repetitive exposure to stimuli." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/42523.
Full textAbstract:
In each individual cell, there are many signaling pathways that may interact or cross talk with each other. Especially, some can sense the same signal and go through different pathways but eventually converge at some points. Therefore repetitive signal stimulations may result in intricate cell responses, among which the priming effect has been extensively studied in monocytes and macrophages as it plays an unambiguously crucial role in immunological protection against pathogen infection. Priming basically describes the phenomena that host cells can launch a dramatically enhanced response to the second higher dose of stimulus if cells have been previously treated with a lower dose of identical stimulus. It was reported to be associated with many human immune diseases (such as rheumatoid arthritis and hepatitis) that are attracting more and more researches on the priming effect. It is undoubtable that many genes are involved in this complicated biological process. Microarray is one of the standard techniques that are applied to do the transcriptome profiling of cells under repetitive stimuli and reveal gene regulatory networks. Therefore a well-established pipeline to analyze microarray data is of special help to investigate the underlying mechanism of priming effect. In this research, we aimed to design a strategy that can be used to interpret microarray data and to propose gene candidates that potentially participate in priming effect. To confirm our analysis results, we used a detailed mathematical model to further demonstrate the mechanism of a specific case of priming effect in a computational perspective.Master of Science
15
Hitt, Lauren R., and Lars Tomanek. "ACUTE NITRATE EXPOSURE CAUSES PROTEOMIC CHANGES CONSISTENT WITH THE REGULATION OF REACTIVE OXYGEN AND NITROGEN SPECIES." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/95.
Full textAbstract:
Nitrate is the most common ionic form of nitrogen in aquatic ecosystems. Although nitrate is known to affect ecosystems at high levels through eutrophication, hypoxia and loss of biodiversity, it is considered to be physiologically inert to the individual aquatic organism. To test the physiological effects of nitrate on aquatic life, we exposed gill tissue of the Pacific oyster, Crassostrea gigas, to nitrate and characterized changes in protein expression, using a gel-based proteomics approach. Of the 642 protein spots detected, we found that 24 proteins (15 identified) changed expression in response to a 6-hour exposure to nitrate concentrations ranging from 0-73 mg/L, values that characterize highly contaminated surface and ground waters. Proteins changing expression included the oxidative stress proteins thioredoxin and cavortin (a member of the superoxide dismutase family) as well as proteins that are involved in G-protein signaling (Rho-GDI, ADP-ribosylation factor, G-protein ß-subunit), protein homeostasis (heat shock protein 70, prohibitin, calreticulin, and proteasome &#;-type 4 subunit), glycolysis (enolase), transport of hydrophobic molecules (lipocalin) and cytoskeletal arrangements (intermediate filaments and a gelsolin-like adseverin). The most parsimonious explanation for these changes in protein expression assumes that C. gigas reduces nitrate to nitrite and nitric oxide, which reacts with superoxide anions to form the very reactive peroxynitrite. We propose that part of the cellular response to reactive nitrogen species,phagocytic hemocytes inhibit the production of reactive oxygen species, potentially compromising the immune response of oysters to invading pathogens.
16
Henderson, Deborah E. J. "Predicting human exposure to air pollution in Scotland, using land regression and geographic information systems." Thesis, University of Strathclyde, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501670.
Full textAbstract:
The aims of the research presented in this thesis were to de develop a model to predict long-term human exposures to traffic-related air pollutants in Central Scotland and to assess whether the patterns of exposure were stable over time, using geographic information systems (GIS) and multiple regression methods. The main part of the project examined nitrogen dioxide (NO2) concentrations in the Greater Glasgow region from 1998 to 2004. Regression models calculated for each year predicted 51 - 84% of variation in annual average NO2 concentrations using predictor variables nrprcsenting the emission, advection and dispersion of air pollution. The spatial patterns of air pollution did not change greatly from year to year, with a maximum of 13% of sites (n = 39) changing concentration quintile from one year to the next. The exposure estimates for 1999 were applied to a cohort in an epidemiological study, mvcstigating the effects of long-term exposure to air pollutants on respiratory function. The modelling techniques developed would be useful for local air quality management (LAQM), as they use readily available and relatively simple data and software.
17
Gunaselvam, A. J. M. (Ariyamalar Jessica Miriam). "The use of seating systems to reduce whole body vibration exposure in the SA industry." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50197.
Full textAbstract:
Thesis (MScEng)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: The purpose of this study was to investigate the specification and use of appropriate seating systems to reduce whole-body vibration exposure in typical vehicles used in South African industry. As part of this study six suspension seats, which the manufacturers claim satisfy the requirements in ISO 7096 (2000), were tested. Six test subjects, three light and three heavy as specified in ISO 7096, were used to estimate the seat transmissibility functions in the vertical direction of the six different suspension seats. Transmissibility functions were measured in the laboratory using two excitation levels, 1m/s2 and 2 m/s2 r.m.s., of broadband frequency vibration and a spectrum approximating the EM5 spectral class in ISO 7096. SEA T values were calculated for operational vibration data measured in an articulated dump truck and a three-wheeled logger. It was shown that SEAT values for the EM1 spectral class could not be reliably estimated from seat transmissibility functions and need to be measured directly in the time-domain. The measurement procedures and seat selection criteria developed in this research project were used to compile a set of "Design Guidelines for Seat Selection for Whole-Body Vibration Control in Industrial Vehicles". These guidelines will provide manufacturers with an easy-to-implement methodology to control whole-body vibration transmitted to the operators of industrial vehicles and to comply with international regulations for whole-body vibration transmission.
AFRIKAANSE OPSOMMING: Die doel van die studie was om die spesifikasies en gebruike van geskikte sitplek stelsels van uit Suid Afrikaanse industriële voertuie, wat heel-liggaam vibrasies verminder, te ondersoek. Ses suspensiesitplekke, wat deur die vervaardigers voorgeskryf word, is getoets om te sien of hulle aan die ISO 7096 (2000) vereistes voldoen. Ses persone, waarvan drie lig en drie swaar is, soos in ISO 7096 voorgeskryf, is gebruik om die sitplek oordragsfunksies in die vertikale rigting vir die ses verskillende suspensiesitplekke te skat. Die oordragsfunksies is in die laboratorium gemeet deur twee opwekkingsvlakke, 1m/s2 en 2m/s2 w.g.k., van wyeband frekwensie vibrasie en n spektrum beraam tot die EMS spektrum soos in ISO 7096. 'SEA T' waardes was vanaf operationele vibrasie data wat in ge-artikuleerde vragmotors en driewiel- 'loggers' gemeet is bereken. Daar is gewys dat betroubare 'SEAT waardes vir die EM1 spektrum nie van sitplek oordragsfunksies geskat kan word nie, maar dat dit eerder direk van die tyd-gebied afgelees moet word. Die metings prosedures en die sitplek keuse vereistes wat in die navorsingsprojek ontwikkel is, is gebruik om "Ontwerp Riglyne vir Sitplek Keuse Vereistes vir Heel- Liggaam Vibrasie in Industriële Voertuie" saam te stel. Hierdie riglyne sal vervaardigers met maklik toepasbare metodes toerus om heel-liggaam vibrasie, wat oorgedra word na industriële voertuig operateurs, te beheer en om aan internasionale regulasies t.o.v. heel-liggaam vibrasie oordrag te kan voldoen.
18
Kandia, Effrosyni <1979>. "Evaluation of Human Exposure to Magnetic Fields Generated by Electric Power Systems in Complex Configurations." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/6101/1/PhD_Thesis_-_KANDIA.Pdf.
Full textAbstract:
The international growing concern for the human exposure to magnetic fields generated by electric power lines has unavoidably led to imposing legal limits. Respecting these limits, implies being able to calculate easily and accurately the generated magnetic field also in complex configurations. Twisting of phase conductors is such a case. The consolidated exact and approximated theory regarding a single-circuit twisted three-phase power cable line has been reported along with the proposal of an innovative simplified formula obtained by means of an heuristic procedure. This formula, although being dramatically simpler, is proven to be a good approximation of the analytical formula and at the same time much more accurate than the approximated formula found in literature. The double-circuit twisted three-phase power cable line case has been studied following different approaches of increasing complexity and accuracy. In this framework, the effectiveness of the above-mentioned innovative formula is also examined. The experimental verification of the correctness of the twisted double-circuit theoretical analysis has permitted its extension to multiple-circuit twisted three-phase power cable lines. In addition, appropriate 2D and, in particularly, 3D numerical codes for simulating real existing overhead power lines for the calculation of the magnetic field in their vicinity have been created. Finally, an innovative ‘smart’ measurement and evaluation system of the magnetic field is being proposed, described and validated, which deals with the experimentally-based evaluation of the total magnetic field B generated by multiple sources in complex three-dimensional arrangements, carried out on the basis of the measurement of the three Cartesian field components and their correlation with the field currents via multilinear regression techniques. The ultimate goal is verifying that magnetic induction intensity is within the prescribed limits.
19
Kandia, Effrosyni <1979>. "Evaluation of Human Exposure to Magnetic Fields Generated by Electric Power Systems in Complex Configurations." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/6101/.
Full textAbstract:
The international growing concern for the human exposure to magnetic fields generated by electric power lines has unavoidably led to imposing legal limits. Respecting these limits, implies being able to calculate easily and accurately the generated magnetic field also in complex configurations. Twisting of phase conductors is such a case. The consolidated exact and approximated theory regarding a single-circuit twisted three-phase power cable line has been reported along with the proposal of an innovative simplified formula obtained by means of an heuristic procedure. This formula, although being dramatically simpler, is proven to be a good approximation of the analytical formula and at the same time much more accurate than the approximated formula found in literature. The double-circuit twisted three-phase power cable line case has been studied following different approaches of increasing complexity and accuracy. In this framework, the effectiveness of the above-mentioned innovative formula is also examined. The experimental verification of the correctness of the twisted double-circuit theoretical analysis has permitted its extension to multiple-circuit twisted three-phase power cable lines. In addition, appropriate 2D and, in particularly, 3D numerical codes for simulating real existing overhead power lines for the calculation of the magnetic field in their vicinity have been created. Finally, an innovative ‘smart’ measurement and evaluation system of the magnetic field is being proposed, described and validated, which deals with the experimentally-based evaluation of the total magnetic field B generated by multiple sources in complex three-dimensional arrangements, carried out on the basis of the measurement of the three Cartesian field components and their correlation with the field currents via multilinear regression techniques. The ultimate goal is verifying that magnetic induction intensity is within the prescribed limits.
20
Campoli, Andrea. "MECHANCIAL PROPERTIES OF ELASTIC THREAD FORCE SYSTEMS IN CANINE EXPOSURES AND APPLICATION OF FORCE." Master's thesis, Temple University Libraries, 2019. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/591232.
Full textAbstract:
Oral BiologyM.S.
Objectives: To investigate differences in the modulus of elasticity, tensile strength, and load at breakage for elastic thread alone and elastic thread with gold chain in combination used in force application of palatally impacted and exposed maxillary canines. Methods: Two groups with n=6 in each were tested. A circular portion of elastic thread was cut, tied and measured to the nearest hundredth of a millimeter and recorded. Five links of a gold chain were cut and an elastic thread was tied to the fifth link opposite the bondable eyelet. The length of the elastic thread and the total apparatus was measured to the hundredth of a millimeter and recorded. An Instron with a ramp speed of 100 mm/min was used for all testing. Results: The addition of the gold chain, as compared to the elastic thread alone, increased the modulus from 8.8 MPa (SD 3.7) to 17.0 MPa (SD 5.03), (p< 0.04) and significantly decreased the maximum tensile stress at breakage from 92.1N (SD 5.0) to 84.1N (SD 1.6), (p<0.004) and the tensile stress at maximum load from 107.8 N (SD 6.7) to 93.8N (SD 4.8), (p<0.002). The stress-strain curve for both groups demonstrated an initial linear behavior followed by non-linear behavior, partially obeying Hooke’s Law, due to the inherent nature of the elastic thread. The addition of the gold chain introduced a rigid element by reducing the of length of the elastic thread by one-half, altering the properties of the assembly. Conclusions: The modulus of elasticity (stiffness) increases and the toughness and resiliency decreases when a gold chain is added to the assembly and compared to elastic thread alone. This could indicate that in the gold chain group, more initial force/strain is delivered to the tooth and there is less stress relaxation over time due to the decrease in the amount of elastic thread. Therefore, the elastic thread alone delivers a more constant and continuous force to the tooth. The use of elastic thread alone may provide a biomechanically more efficient approach to orthodontic movement of impacted and open exposed teeth.
Temple University--Theses
21
Wentling, II William A. II. "Economic Effects on Radiopharmacy Systems| The Impact of the Nuclear Regulatory Commission's Proposed Radiation Exposure Limits." Thesis, Robert Morris University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3629877.
Full textAbstract:
In the spring of 2012, based on recommendations from the International Commission on Radiological Protection (ICRP), the Nuclear Regulatory Commission (NRC) proposed three amendments to reduce current radiation exposure limits for radiation workers. The NRC proposals have caused some concern within the radiopharmaceutical industry. The regulatory changes may affect the ability of radiopharmacy workers to remain on the job, thereby inflicting additional costs to radiopharmacies if they are required to replace workers who have reached their yearly exposure limits.
This research sought to determine whether or not the new regulatory proposals will in fact have a financial impact on the radiopharmaceutical industry. This research was a retrospective case study that analyzed four radiopharmaceutical production facilities and their employee radiation exposure reports. Results of the study suggest that the NRC's proposed amendments to reduce radiation levels will not have a great adverse effect, either financially or from an employee exposure standpoint, on the current radiopharmacy system. The research demonstrated that existing as low as reasonably achievable (ALARA) standards have resulted in radiopharmacy workers receiving exposures well below the current limits, and within the NRC proposed limits. Of 77 employees studied over a 10 year period, only seven employees (9 %) would have been removed from the production process for overexposure to any one of the NRC's proposed limits. However, this research reviewed small a subset of four radiopharmacies and did not examine other industries and professions utilizing ionizing radiation.
22
Lança, Luís Jorge Oliveira Carrasco. "Radiological imaging in digital systems: the effect of exposure parameters in diagnostic quality and patient dose." Doctoral thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/3950.
Full textAbstract:
Doutoramento em Tecnologias da SaúdeEsta tese pretende contribuir para o estudo e análise dos factores relacionados com as técnicas de aquisição de imagens radiológicas digitais, a qualidade diagnóstica e a gestão da dose de radiação em sistema de radiologia digital. A metodologia encontra-se organizada em duas componentes. A componente observacional, baseada num desenho do estudo de natureza retrospectiva e transversal. Os dados recolhidos a partir de sistemas CR e DR permitiram a avaliação dos parâmetros técnicos de exposição utilizados em radiologia digital, a avaliação da dose absorvida e o índice de exposição no detector. No contexto desta classificação metodológica (retrospectiva e transversal), também foi possível desenvolver estudos da qualidade diagnóstica em sistemas digitais: estudos de observadores a partir de imagens arquivadas no sistema PACS. A componente experimental da tese baseou-se na realização de experiências em fantomas para avaliar a relação entre dose e qualidade de imagem. As experiências efectuadas permitiram caracterizar as propriedades físicas dos sistemas de radiologia digital, através da manipulação das variáveis relacionadas com os parâmetros de exposição e a avaliação da influência destas na dose e na qualidade da imagem. Utilizando um fantoma contrastedetalhe, fantomas antropomórficos e um fantoma de osso animal, foi possível objectivar medidas de quantificação da qualidade diagnóstica e medidas de detectabilidade de objectos. Da investigação efectuada, foi possível salientar algumas conclusões. As medidas quantitativas referentes à performance dos detectores são a base do processo de optimização, permitindo a medição e a determinação dos parâmetros físicos dos sistemas de radiologia digital. Os parâmetros de exposição utilizados na prática clínica mostram que a prática não está em conformidade com o referencial Europeu. Verifica-se a necessidade de avaliar, melhorar e implementar um padrão de referência para o processo de optimização, através de novos referenciais de boa prática ajustados aos sistemas digitais. Os parâmetros de exposição influenciam a dose no paciente, mas a percepção da qualidade de imagem digital não parece afectada com a variação da exposição. Os estudos que se realizaram envolvendo tanto imagens de fantomas como imagens de pacientes mostram que a sobreexposição é um risco potencial em radiologia digital. A avaliação da qualidade diagnóstica das imagens mostrou que com a variação da exposição não se observou degradação substancial da qualidade das imagens quando a redução de dose é efectuada. Propõe-se o estudo e a implementação de novos níveis de referência de diagnóstico ajustados aos sistemas de radiologia digital. Como contributo da tese, é proposto um modelo (STDI) para a optimização de sistemas de radiologia digital.
In the present study an attempt has been made to contribute for the analysis of the factors related with the technical acquisition, the quality of the diagnostic image and dose management in digital detector systems for projection radiography. The thesis methodology is organized in two components. The observational component is based on a retrospective and transversal design. The data collected from CR and DR systems allowed the evaluation of exposure parameters from digital images, absorbed dose and exposure index to the detector. Under this classification (retrospective and transversal design) it was also possible to develop diagnostic quality evaluations from digital radiographic images: observer performance studies from digital images stored in the PACS. Under the experimental component of this thesis several experiments using phantoms were performed in order to evaluate the relation between dose and image quality. The experiments allowed the characterization of physical properties of digital image systems and manipulation of variables such as those related to exposure parameters and evaluation of its influence in dose and image quality. Using a contrast-detail phantom, anthropomorphic phantoms and an animal bone phantom it was possible to provide objective measures concerning the quantification of diagnostic quality and measures of object detectability. According to the research undertaken several conclusions could be highlighted. Quantitative measures of DR and CR detectors performance provide a basis for optimization, allowing to measure and determinate the physical properties of digital radiology image systems. Exposure parameters being used in digital radiography shows that current routine radiographic practice does not comply with European guidelines concerning exposure techniques. There is a need to evaluate, improve and establish a baseline reference aiming exposure optimization and provide new guidelines for current digital systems. Exposure parameters influence patient dose in digital radiology but image quality perception seems not to be affected with exposure variation. Studies performed both with phantoms and patients showed that overexposure is a potential risk when working with digital systems. Evaluation of diagnostic quality of digital images when a variation of exposure parameters is provided showed no substantial decrease in image quality when dose reduction is achieved. New dose reference levels should be studied and implemented according to the digital system characteristics and performance. A conceptual framework (STDI) is proposed as an attempt to provide a practical method to optimize digital radiology systems.
FCT/PROTEC
23
Masutomi, Naoya. "Evaluation of endocrine active chemicals on endocrine/reproductive systems following transplacental and lactational exposure in rats." Kyoto University, 2004. http://hdl.handle.net/2433/147783.
Full text
24
Ek, Caroline. "Towards understanding stable isotope signatures in stressed systems." Doctoral thesis, Stockholms universitet, Institutionen för miljövetenskap och analytisk kemi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-134967.
Full textAbstract:
Stable isotope analysis (SIA) is a valuable tool in ecotoxicology because δ13C and δ15N may provide insights into the trophic transfer of contaminants in a food web. The relationship between a species’ trophic position (TP, determined from δ15N) and internal concentration of biomagnifying contaminants can be established and used for regulatory purposes. However, the exposure of organisms to xenobiotics incurs physiological costs, and the stable isotope signature of a consumer reflects not only diet but also a physiological state. The latter raises questions regarding the interpretation of stable isotope signatures in contaminated areas. Therefore, the aim of this Thesis was to evaluate the behaviour of consumers’ stable isotope signatures in stressed systems, with a primary focus on the effects of environmental contaminants. In paper I, the physiological costs of chemical exposure were found to alter incorporation rates of dietary nitrogen and carbon in a consumer by influencing both growth and metabolic turnover, with resulting changes in isotope signatures relative to a control system. In paper II, the diet-consumer discrimination factors for 15N and 13C were confirmed to increase under chemical exposure mediated via increased metabolic costs. However, the physiological response was low and translated into only minor shifts in the δ13C and δ15N. The predictability of exposure effects on the stable isotope signature was demonstrated in paper III, in which animals exposed to a chemical with a known mode of action presented expected effects on elemental composition, body size, biomarkers of oxidative stress and the stable isotope signatures. Moreover, consumers’ oxidative balance was found to be related to their δ15N values, thus providing evidence of the kinetic isotope effect on the oxidative status. However, despite the alterations in stable isotope signatures observed in laboratory settings (papers I-III), the effect of xenobiotics on the TP estimates was nil or minor in the field-collected animals. Moreover, the TP values were not significantly different between the animals in the contaminated and the reference habitats because of the high overall uncertainties in the TP estimates (paper IV). Also, the TP estimates based on δ15N in bulk material were more similar between the contaminated and the reference systems than TP estimates based on δ15N values in amino acids. Therefore, the latter method appears more sensitive towards xenobiotics (and, possibly, other environmental stressors) and thus less suitable for TP assessment in contaminated areas. This Thesis improved the overall understanding of the applicability of SIA in stressed systems by establishing relationships between various exposure regimes, physiological responses and the stable isotope signatures in consumers. In model species at low trophic levels, the exposure to xenobiotics was found to significantly affect δ13C and δ15N values, which can be expected whenever physiological responses are detected. However, because of the overall high uncertainty in TP estimates, no significant differences between contaminated and control systems were detected, although the estimated TP were consistently higher in the contaminated systems. Future research should focus on higher trophic levels, in which effects of a greater magnitude can be expected. Moreover, the effects in entire food webs should be addressed rather than single prey–consumer relationships as well as other environmental variables that may contribute to the stable isotope variability in and among systems under various environmental pressures.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.
25
Pickard, Amy Elizabeth. "Assessing the photoreactivity of peatland derived carbon in aquatic systems." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28774.
Full textAbstract:
Northern peatlands are a globally important soil carbon (C) store, and aquatic systems draining peatland catchments receive a high loading of dissolved and particulate forms of C from the surrounding terrestrial environment. Once incorporated into the aquatic environment, internal processes occur to modify the C pool. Of these, photo-processing preferentially targets terrestrially derived C and therefore might have a significant effect on the C budget of peatland draining aquatic systems. The overarching aim of this study was to investigate photochemical processing of C in Scottish peatland draining aquatic systems in order to determine the importance of this pathway in aquatic biogeochemical cycles. For initial laboratory experiments, water samples from a peatland headwater stream (Auchencorth Moss, SE Scotland) were collected. Laboratory based irradiation experiments were conducted at a range of temperatures, and different filtration treatments, including unfiltered samples, were employed to understand the fraction of C most susceptible to photo-processing. UV irradiation and temperature had a significant effect on DOC and gas headspace concentrations, with Q10 values of ~1.42 and ~1.65 derived for CO2 and CO photoproduction in unfiltered samples, respectively. However, filtration treatment did not induce significant changes in gaseous C production between light and dark samples, indicating that the experimental conditions favoured breakdown of DOC rather than POC to CO2 and CO. In all light treatments a small but significant increase in CH4 concentration was detected. These data were compared to results from experiments conducted in ambient light and temperature conditions. DOC normalised CO2 photoproduction was an order of magnitude lower than in laboratory conditions, although relative abundances of C species within overall budgets were similar and these experiments demonstrated that ambient exposure is sufficient to generate photo-processing of aquatic peatland C. Overall these data show that peatland C, particularly the < 0.2 μm fraction, is highly photoreactive and that this process is temperature sensitive. Further laboratory irradiation experiments were conducted on filtered water samples collected over a 13-month period from two contrasting aquatic systems. The first was the headwater stream draining Auchencorth Moss peatland with high DOC concentrations. The second was a low DOC reservoir (Loch Katrine, C Scotland) situated in a catchment with a high percentage peat cover. Samples were collected monthly from May 2014 to May 2015 and from the stream system during two rainfall events. Significant variation was seen in the photochemical reactivity of DOC between the two systems, with total irradiation induced change typically two orders of magnitude greater and DOC normalised CO2 production a factor of two higher in the headwater stream samples. This is attributed to longer water residence times in the reservoir rendering a higher proportion of the DOC recalcitrant to photo-processing. Overall the magnitude of photo-induced C losses was significantly positively correlated with DOC concentration in the headwater stream, which varied seasonally with highest concentrations detected in late autumn and winter. Rainfall events were identified as important in replenishing the stream system with photoreactive material, with lignin phenol data indicating mobilisation of fresh DOC from woody vegetation in the upper catchment during a winter rainfall event. Whilst these data clearly demonstrate that peatland catchments generate significant volumes of photoreactive DOC, the degree to which it is processed in the aquatic environment is unclear. Field investigations were undertaken to address this uncertainty. In-situ experiments with unfiltered water samples in light and dark conditions were conducted in two contrasting open water peatland pool systems. At the high DOC site (Red Moss of Balerno, SE Scotland), DOC concentrations in surface light exposed samples decreased by 18% compared to dark controls over 9 days and light treatments were enriched in CO2 and CH4. Photochemical processing was evident in δ13C-DOC and δ13C-DIC signatures of light exposed samples, which were enriched and depleted, respectively, relative to dark controls (+0.23 ‰ and -0.38 ‰) after 9 days of surface exposure. At the low DOC site (Cross Lochs, Forsinard, N Scotland) net production of DOC occurred in both light and dark samples over the experiment duration, in part due to POC breakdown. δ13C-DIC signatures indicated photolysis had occurred in light exposed samples (-1.98 ‰), whilst δ13C-DOC data suggest an absence of photo-processing, as the signatures in both treatments were similar. Accounting for light attenuation through the water column, 46 ± 4.9 and 8.7 ± 0.5 g C-CO2 eq m−2 yr−1 was processed by photochemical and microbial activity in peatland pools within the catchments at the high and low DOC sites, respectively. At both sites, light driven processing was responsible for a considerable percentage (34 and 51%) of gaseous C production when compared to equivalent estimates of microbial C processing and thus should be considered a key driver of peatland pool biogeochemical cycles. It is clear from this study that temperature, seasonal cycles, rainfall events and water residence time provide strong controls on the photoreactivity of aquatic C in Scottish peatland systems. The photo-processing pathway has the potential to alter the C balance of peatland catchments with a high percentage coverage of aquatic systems. Under climate change scenarios where light, temperature and rainfall conditions are expected to change, this process may become increasingly important in aquatic C cycling, particularly if the upward trend in DOC concentrations in northern aquatic systems continues.
26
Gust, Kurt A., Bindu Nanduri, Arun Rawat, Mitchell S. Wilbanks, Choo Y. Ang, David R. Johnson, Ken Pendarvis, et al. "Systems toxicology identifies mechanistic impacts of 2-amino-4, 6-dinitrotoluene (2A-DNT) exposure in Northern Bobwhite." BioMed Central Ltd, 2015. http://hdl.handle.net/10150/610284.
Full textAbstract:
BACKGROUND: A systems toxicology investigation comparing and integrating transcriptomic and proteomic results was conducted to develop holistic effects characterizations for the wildlife bird model, Northern bobwhite (Colinus virginianus) dosed with the explosives degradation product 2-amino-4,6-dinitrotoluene (2A-DNT). A subchronic 60d toxicology bioassay was leveraged where both sexes were dosed via daily gavage with 0, 3, 14, or 30 mg/kg-d 2A-DNT. Effects on global transcript expression were investigated in liver and kidney tissue using custom microarrays for C. virginianus in both sexes at all doses, while effects on proteome expression were investigated in liver for both sexes and kidney in males, at 30 mg/kg-d. RESULTS: As expected, transcript expression was not directly indicative of protein expression in response to 2A-DNT. However, a high degree of correspondence was observed among gene and protein expression when investigating higher-order functional responses including statistically enriched gene networks and canonical pathways, especially when connected to toxicological outcomes of 2A-DNT exposure. Analysis of networks statistically enriched for both transcripts and proteins demonstrated common responses including inhibition of programmed cell death and arrest of cell cycle in liver tissues at 2A-DNT doses that caused liver necrosis and death in females. Additionally, both transcript and protein expression in liver tissue was indicative of induced phase I and II xenobiotic metabolism potentially as a mechanism to detoxify and excrete 2A-DNT. Nuclear signaling assays, transcript expression and protein expression each implicated peroxisome proliferator-activated receptor (PPAR) nuclear signaling as a primary molecular target in the 2A-DNT exposure with significant downstream enrichment of PPAR-regulated pathways including lipid metabolic pathways and gluconeogenesis suggesting impaired bioenergetic potential. CONCLUSION: Although the differential expression of transcripts and proteins was largely unique, the consensus of functional pathways and gene networks enriched among transcriptomic and proteomic datasets provided the identification of many critical metabolic functions underlying 2A-DNT toxicity as well as impaired PPAR signaling, a key molecular initiating event known to be affected in di- and trinitrotoluene exposures.
27
Murugan, Nirosha J. "PHYSICAL AND CHEMICAL CHANGES IN PLANARIAN AND NON-LIVING AQUEOUS SYSTEMS FROM EXPOSURE TO TEMPORALLY PATTERNED MAGNETIC FIELDS." Thesis, Laurentian University of Sudbury, 2013. https://zone.biblio.laurentian.ca/dspace/handle/10219/2125.
Full textAbstract:
Planarian maintained in spring water and exposed for two hours to temporally patterned, weak (1 to 5 μT) magnetic field in the dark displayed diminished mobility that simulated the effects of morphine and enhanced this effect at concentrations associated with receptor subtypes. A single (5 hr) exposure to this same pattern following several days of exposure to a very complex patterned field in darkness dissolved the planarian and was associated with an expansion of their volume. Spectral power density analyses of direct measurements of the spring water only following exposure to this field in darkness showed emission spectra that were displayed from control conditions by ~10 nm and associated with an energy increment of ~10-20 J. This value is an intrinsic solution for the physical properties of the water molecule. “Shielding” the exposed water with plastic, aluminum foil or copper foil indicated that only the latter eliminated a powerful spike in photon emission around 280 nm. Continuous measurement of pH indicated that the slow shift towards alkalinity over 12 hours of exposure was associated with enhanced transient pH shifts of .02 units with typical durations between 20 and 40 ms. These results indicate that the appropriately patterned and amplitude of magnetic field that affects water directly could mediate some of the powerful effects displayed by biological aquatic systems.
28
Harrigan, Kristen M. "Scaling to the Organism: An Innovative Model of Dynamic Toxic Hotspots in Stream Systems." Bowling Green State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu149019827523479.
Full text
29
Lam, Yee-man, and 林綺雯. "GIS in aircraft noise exposure assessment, Tsuen Wan district, Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29961324.
Full text
30
Liu, XiaoTong. "Privacy exposure on WeChat from users' perspective : A study among the university students in China." Thesis, Linnéuniversitetet, Institutionen för informatik (IK), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-80610.
Full textAbstract:
In 21st century, social media has become one necessary part in people’s life, different kinds of social media emerge in endlessly. In younger generation, it is popular to use social media as a communication tool to get closer to each other. During using social media, it is important to have awareness to protect their personal information. Comparing with Western countries, the topic of privacy is not often discussed in China and some privacy issues might be ignored due to people have not enough knowledge in this area. In this study, the focus is to investigate Chinese university students’ perception of privacy risks and WeChat personal information exposure. Based on this, this study also explores the users’ attitudes toward WeChat and how it influences the future usage of it. The adopted research method is qualitative research method, by doing interviews with 15 students from different school, city and major. From the study, eight essential concepts are used to answer two research questions. Though analysis, the situation of the privacy perception can be found, the reasons and attitudes toward WeChat are also figured out. At the end of the thesis, the contribution of this study and suggestions to future research are shown.
31
Kennedy, Laura J. (Laura Jane). "Quantitation of 8-oxoG and strand breaks in pUC19 plasmid DNA after exposure to oxygen radical generating systems." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/38379.
Full text
32
Hutchens, Steven Jason. "Modeled sulfur dioxide exposure from a proposed coal fired power plant, using geographic information systems and air dispersion modeling." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3376.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains xii, 161 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 132-137).
33
Lahman, Sara Elisabeth. "The Ecotoxicological Impacts of Copper in Aquatic Systems." Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1427119997.
Full text
34
Sher, Rabnawaz Jan. "Classification of a Sensor Signal Attained By Exposure to a Complex Gas Mixture." Thesis, Linköpings universitet, Statistik och maskininlärning, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-172769.
Full textAbstract:
This thesis is carried out in collaboration with a private company, DANSiC AB This study is an extension of a research work started by DANSiC AB in 2019 to classify a source. This study is about classifying a source into two classes with the sensitivity of one source higher than the other as one source has greater importance. The data provided for this thesis is based on sensor measurements on different temperature cycles. The data is high-dimensional and is expected to have a drift in measurements. Principal component analysis (PCA) is used for dimensionality reduction. “Differential”, “Relative” and “Fractional” drift compensation techniques are used for compensating the drift in data. A comparative study was performed using three different classification algorithms, which are “Linear Discriminant Analysis (LDA)”, “Naive Bayes classifier (NB)” and “Random forest (RF)”. The highest accuracy achieved is 59%,Random forest is observed to perform better than the other classifiers.This work is done with DANSiC AB in collaboration with Linkoping University.
35
Liu, Ying. "The impact of physical and biological factors on intracellular uptake, trafficking and gene transfection after ultrasound exposure." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43626.
Full textAbstract:
We used megahertz pulsed ultrasound and studied gene transfection with a human prostate cancer cell line. We first studied the compromise of cell viability and uptake efficiency and found out that increasing sonication temperature or changing US contrast agents could improve drug/gene delivery mediated by US exposure. We also found that accounting for cell debris after sonication was important to correctly determine cell viability.
Next, we verified the capability of US to deliver DNA into the cell nuclei, which is necessary for successful gene transfection. Under the optimal sonication conditions, ~ 30% of cells showed DNA uptake right after US exposure and most had a portion of DNA already localized in the cell nuclei. The maximum transfection efficiency was ~ 12% at 8 h post US exposure. From the DNA perspective, ~ 30% of DNA was localized in the cell nuclei immediately after US exposure and ~ 30% was in the autophagosomes/ autophagolysosomes with the rest ¡°free¡± in the cytoplasm. At later time up to 24 h, DNA continued to be distributed ~ 30% in the nuclei and most or all of the rest in autophagosomes/autophagolysosomes. Our results showed that US was able to deliver DNA into the cell nuclei shortly after the treatment and that the rest of DNA was mostly cleared by autophagosomes/autophagolysosomes.
To further increase transfection efficiency, we then studied the differences between live cells with DNA uptake and those with successful gene transfection post US exposure using cell sorting, cell cycle and microarray analysis. Cells with gene transfection were found to accumulate at the G1 phase of cell cycle and associate with the up-regulation of 32 genes (e.g., GADD45¦Á) and the down-regulation of 46 genes (e.g., TOP2¦Á). Drugs that regulate the expression levels of GADD45¦Á and TOP2¦Á were found to further enhance the transfection mediated by US. A maximun increase of ~ 2 fold in transfection efficiency was observed when cells were sonicated with 0.6 mg/mL ethyl methanesulfonate to up-regulate GADD45¦Á. These results suggestted that using drugs that regulate certain introcellular processes could further enhance US-mediated gene transfection.
Over a broad range of US conditions, the integrity of three common gene delivery vectors, plasmid DNA, siRNA and adeno-associated virus, were not affected by US exposure. This thesis verified that US was able to delivery DNA into the cell nuclei to facilitate rapid gene transfection, and provided a proof of princible that by modulating certain intracellular processes, the efficiency of US-mediated gene transfection could be further increased. US could potentially be a safe and efficient method for gene therapy.
36
Fourie, Jade Melissa. "The relationship between social support, self-esteem and exposure to community violence on adolescent's perceptions of well-being." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_3937_1331889850.
Full textAbstract:
Violence is considered to be one of the most critical and threatening global problems plaguing the world today, leaving a trail of devastating consequences to societies, economies, cultures, families and individuals (Desjarlais &
Kleinman, 1997). Adolescents who grow up in a context of violence learn distorted ways of thinking, acting, living and interacting. Aggressive tendencies and violent behaviour become internalised and adopted as acceptable ways to resolve conflict situations. Chronic, continuous exposure to violence results in physical, psychological and emotional disturbances, such as depression, anxiety, lowered self-confidence, sleep disturbances, decreased attention and concentration spans. This study addressed the form of violence known as community violence, i.e. violence that children experience within their communities (either as witnesses or as victims). This study investigated the effects of this negative environmental experience and investigated potential mediating and moderating variables that could influence the harmful effects of such experiences. The variables considered as mediating and/or moderating variables were social support and self-esteem. The theoretical framework adopted for this study was Bronfennbrenner&rsquo
s Bioecological Systems theory.
37
Nalepa, Lauren Elizabeth. "Quantitative assessment of the impact of the previous cycle's core exposure on the transient response of boiling water reactor systems." [Gainesville, Fla.] : University of Florida, 2008. http://purl.fcla.edu/fcla/etd/UFE0022859.
Full text
38
Willett, Evan James. "PREFERENTIAL PATHWAYS FOR VAPOR INTRUSION: SITE SCREENING AND FIELD SAMPLING OF SEWERS TO ASSESS INHALATION EXPOSURE RISKS." UKnowledge, 2018. https://uknowledge.uky.edu/ce_etds/64.
Full textAbstract:
Hazardous waste sites and aging wastewater infrastructure are common in the United States. There are hundreds of thousands of contaminated sites and more than a million miles of sewer pipes. Populations living close to hazardous waste sites often suffer from increased risk of adverse health effects due to exposure to contaminated environmental media. Vapor intrusion is one process by which nearby populations can be exposed to volatile organic compounds (VOCs). Aging wastewater infrastructure is important for vapor intrusion site assessments because sewer pipes can serve as preferential vapor transport pathways. Near contaminated sites, pipe deterioration allows migration of contaminants into sewers and potential accumulation of chemical vapors in sewer gas and nearby buildings. The objectives of this study are to develop a screening-level method to identify contaminated sites where additional evaluation of vapor intrusion is necessary, and then conduct field sampling at these sites to investigate sewers as potential vapor intrusion pathways. Sampling was conducted at four study sites, which consist of former and current dry cleaning facilities located in Lexington, Kentucky. The results of this study demonstrate that preferential vapor intrusion pathways such as sewers can facilitate the spread of vapor intrusion exposure risks beyond source areas of contamination.
39
Fourie, Jade Melissa. "The relationship between social support, self-esteem and exposure to community violence on adolescentʹs perceptions of well-being." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_1944_1331890691.
Full textAbstract:
Violence is considered to be one of the most critical and threatening global problems plaguing the world today, leaving a trail of devastating consequences to societies, economies, cultures, families and individuals (Desjarlais &
Kleinman, 1997). Adolescents who grow up in a context of violence learn distorted ways of thinking, acting, living and interacting. Aggressive tendencies and violent behaviour become internalised and adopted as acceptable ways to resolve conflict situations. Chronic, continuous exposure to violence results in physical, psychological and emotional disturbances, such as depression, anxiety, lowered self-confidence, sleep disturbances, decreased attention and concentration spans. This study addressed the form of violence known as community violence, i.e. violence that children experience within their communities (either as witnesses or as victims). This study investigated the effects of this negative environmental experience and investigated potential mediating and moderating variables that could influence the harmful effects of such experiences. The variables considered as mediating and/or moderating variables were social support and self-esteem. The theoretical framework adopted for this study was Bronfennbrenner&rsquo
s Bioecological Systems theory.
40
Tran, Lily H., Serena A. Allen, Hannah V. Oakes, Russell W. Brown, and Brooks B. Pond. "Dopaminergic Effects of major Bath Salt Constituents 3, 4-methylenedioxypyrovalerone (MDPV), Mephedrone, and Methylone are Enhanced Following Co-exposure." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/139.
Full textAbstract:
An unprecedented rise in the availability of new synthetic drugs of abuse has been observed in the recent years. One of the most noted cases is that of a popularized designer drug mixture known as ‘bath salts’. Commonly obtained from various shops and on the internet, “bath salts” often contain the synthetic cathinones 3,4 methylenedioxypyrovalerone (MDPV), mephedrone, and methylone in diverse combinations. Individually, the synthetic cathinones are known to have similar pharmacology to controlled psychostimulants such as cocaine and the amphetamines, increasing the levels of dopamine (DA) in the synaptic cleft. DA is an important neurotransmitter that regulates a variety of behaviors and functions; neurons within the mesolimbic DA pathway (ventral tegmental area to nucleus accumbens) are involved in reward and motivation and are activated by these drugs of abuse. Additionally, psychostimulant-induced increases in DA in the nigrostriatal pathway (substantia nigra to corpus striatum) lead to increases in locomotor behavior. However, the majority of preclinical investigations have only assessed the effects of individual bath salt constituents and have provided little information regarding the possibility of significant drug interactions with the co-exposure of MDPV, mephedrone, and methylone. This study sought to evaluate and compare the effects of individual versus combined MDPV, mephedrone, and methylone on dopamine (DA) levels in discrete brain regions as well as motor stimulant responses in mice. Male adolescent Swiss-Webster mice received intraperitoneal injections of saline, MDPV, mephedrone, methylone (1.0 or 10.0 mg/kg), or the cathinone cocktail (MDPV + mephedrone + methylone at 1.0, 3.3, or 10 mg/kg). The effect of each treatment on DA and DA metabolite levels in mesolimbic and nigrostriatal brain tissue was quantified 15 min after a single exposure utilizing high pressure liquid chromatography with electrochemical detection (HPLC-ECD). Additionally, locomotor activity was recorded in mice after acute (day 1) and chronic intermittent (day 7) dosing. The results demonstrate that MDPV, mephedrone, and methylone produce dose-related increases in the mesolimbic and nigrostriatal DA levels that are significantly enhanced following their co-administration. Additionally, a decrease in locomotor activity on day 1 that was exacerbated by day 7 was noted in mice treated with the cathinone cocktail and was not observed with any of the single agents. The decrease in locomotor activity was accompanied by an increase in stereotypic-like behavior including excessive grooming and even self-mutilation. Our findings demonstrate a significantly enhanced effect of MDPV, mephedrone, and methylone on both DA and its metabolites resulting in significant alterations in locomotor activity. This work provides insight into the potential enhanced risk of the use of these combination synthetic cathinone products.
41
Qureshi, Muhammad Rafaqat Ali. "Theoretical and numerical evaluations of electromagnetic waves energy deposition within the human body due to exposure to existent and emerging wireless technologies." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/36697.
Full textAbstract:
In this thesis, a comprehensive investigation of the state-of-the-art guidelines for the conducted schemes in the near vicinity of the human body has been provided. The primary objectives of this work have been mainly focused on the electromagnetic (EM) wave exposure at both the microwave and millimetre-wave (mm-wave) frequency bands, along with their thorough analyses for a number of wireless technologies, such as the smart meters (SMs) and multiple-input multiple-output (MIMO) antennas. This work has undertaken a detailed theoretical and numerical modelling, as well as experimental measurements to propose the frameworks for the exposure conditions regarding the advanced wireless systems and applications. The employed numerical methods have been validated using the finite integration technique (FIT)-based simulations. The specific absorption rate (SAR) distributions have been determined using the anatomically realistic human models at various frequency bands. In this regard, each human model is assigned with the age- and frequency-dependent (AFD) dielectric properties, based on the novel expressions. This has then resulted in the representation of dispersive and age-dependent dielectric properties, in order to potentially improve the accuracy of the current assessment methods. Moreover, a number of generalised exposure conditions involving the standing and sleeping postures have been assessed for the home area network operating at the microwave band. The obtained results on the study on the SMs have been partly used by the Public Health England to provide the practical guidelines for the improvement of the services provided for the public. Furthermore, an assessment of the MIMO mobile handset has been performed in two exposure conditions, involving calling and body worn postures. Some aspects of this MIMO study has shown higher absorption levels in comparison with the basic restriction limits. A new SAR estimation approach has also been adopted to address the compliance assessment issues at the mm-wave bands. Finally, this work has identified a number of key factors that cause the high absorption levels in the human body and has provided insight into the efficient techniques in order to reduce such effects.
42
Shipman, Matthew Richard. "Proteomics and systems biology analysis of the response of monocytes to infection by Coxiella burnetii and exposure to innate immune adjuvants." Diss., Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/shipman/ShipmanM0810.pdf.
Full textAbstract:
Coxiella burnetii is an obligate intracellular pathogen that infects human monocytes, specifically inhabiting the phagolysosome. C. burnetii is a potential bioterror agent and is classified by the National Institute for Allergies and Infectious Diseases (NIAID) as a category B pathogen. This bacterium is remarkably infectious, requiring as little as one bacterium to cause infection. We used phase II C. burnetii, an avirulent laboratory strain that acts as a model for wild type phase I strains. Our research was directed towards a deeper understanding of the monocyte proteome in response to a) infection by phase II C. burnetii, and b) exposure to immune adjuvants known to increase monocyte resistance to infection by C. burnetii. Monomac I cells were infected with phase II C. burnetii and aliquots were taken at 24, 48, and 96 hours postinfection. Experiments with immune adjuvants that increase monocyte killing of C. burnetii, involved Monomac I cells treated with Securinine, E. coli lipopolysaccharide (LPS), and monophosphoryl lipid A (MPL). Securinine is a GABA A receptor antagonist that is being developed at Montana State University for biodefense purposes, and triggers an innate immune response that differs from classic Toll-like receptor (TLR) stimulation of innate immunity represented by LPS and MPL. We employed multiplex 2D gel electrophoresis (m2DE) using ZDyes, a new generation of covalent fluorescent protein dyes being developed at Montana State University, coupled with MS/MS analysis and bioinformatics to determine the proteome changes in Monomac I cells in response to the conditions described above, and to develop a preliminary mechanistic model using a systems biology approach to account for the observed changes and propose multiple testable hypotheses to focus downstream research efforts. We also tested the effects on Monomac I cells infected with phase II C. burnetii +/- Securinine. We observed a high proportion of cell death in the + Securinine samples, using a dosage of Securinine higher than the optimal effective dosage. The information derived from this experiment will be useful in monitoring the tendency towards cell death in Securinine treated samples both from C. burnetii infected monocytes and other cell types (e.g. neurons) that contain GABA A receptors.
43
Stojanovic, Bojan. "Lifetime Performance Assessment of Thermal Systems : Studies on Building, Solar and Disctrict Heating Applications." Doctoral thesis, KTH, Byggvetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10967.
Full textAbstract:
The main questions today concerning thermal systems are their economical and environmental impacts. These entities are generally, at present, assessed on the basis of operation performances of newly installed/designed systems, during an assumed lifetime period. While this is the common way of perceiving thermal systems, performance-over-time will change as an effect of degradation, and not solely of different operation scenarios. How and to what extent is the question that needs assessing in order to evaluate if these changes will jeopardise the intended system performance requirement, hence service life (SL). The lack of knowledge/approaches and tools for assessing durability and performance-over-time of thermal systems complicates the task of incorporating these aspects in engineering. In turn, this pro-active assessment and analysis is in line with today’s performance based directives, laws and regulations; of which the working life is an essential part. The durability of materials, components and systems is not a topic that is an end in itself, but becomes a vital part in a comprehensive perspective as sustainability. The lifetime performance assessment of thermal systems, as presented in this thesis, shows that it is a vital part of the R&D in the quest of sustainable energy/thermal systems and energy use. This thesis gives knowledge to the thermal (energy) system/technology R&D and engineering sector, regarding durability and lifetime performance assessment methodologies; but also to the durability of construction works sector, regarding the needs for assessing lifetime performance of materials and components in relation to system performance. It also presents descriptions of requirements on construction works. Specifically, the studies presented in the thesis show how durability and lifetime performance assessment of thermal systems may be sought, with knowledge on: methodologies, exposure test set-ups, modelling and the attainment and use of adequate tools. The main focus is on performance-over-time modelling, tying material/component degradation to altered thermal performance, thereby attaining performance-over-time assessment tools to be used in order to incorporate these aspects when engineering thermal systems; hence enabling the forecasting of SL. The presented work was predominantly done in association to the EU project ENDOHOUSING. The project developed a solar-assisted heat pump system solution, with heat storage, to provide the thermal energy to meet space heating, cooling and hot water requirements for domestic houses in different regions of the EU. The project constituted the platform for the work presented in this thesis, thereby outlining the main context with studies on durability and lifetime performance of: flat plate solar collectors ground heat sources/storages and interaction with a heat pump system evaluation of the ENDOHOUSING solar-assisted heat pump system The thesis also presents a study of SL prediction and estimation of district heating distribution networks (an additional thermal system application). In this particular context, the Factor Method is proposed as a methodology. The main issue of lifetime performance of thermal systems is how and to what extent performance reduction in individual materials or components influence the overall system performance, as the essence of energy/thermal system sustainability is system performance.QC 20100810
44
White, David Albert. "The behavioral and neurochemical effects of prenatal stress on stress responsive systems in rats." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=1049.
Full textAbstract:
Thesis (Ph. D.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains xiv, 223 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 187-220).
45
Bourdon, Julie A. "Use of Systems Biology in Deciphering Mode of Action and Predicting Potentially Adverse Health Outcomes of Nanoparticle Exposure, Using Carbon Black as a Model." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23105.
Full textAbstract:
Nanoparticles (particles less than 100 nm in at least one dimension) exhibit chemical properties that differ from their bulk counterparts. Furthermore, they exhibit increased potential for systemic toxicities due to their deposition deep within pulmonary tissue upon inhalation. Thus, standard regulatory assays alone may not always be appropriate for evaluation of their full spectrum of toxicity. Systems biology (e.g., the study of molecular processes to describe a system as a whole) has emerged as a powerful platform proposed to provide insight in potential hazard, mode of action and human disease relevance. This work makes use of systems biology to characterize carbon black nanoparticle-induced toxicities in pulmonary and extra-pulmonary tissues (i.e., liver and heart) in mice over dose and time. This includes investigations of gene expression profiles, microRNA expression profiles, tissue-specific phenotypes and plasma proteins. The data are discussed in the context of potential use in human health risk assessment. In general, the work provides an example of how toxicogenomics can be used to support human health risk assessment.
46
Kidd, Ian V. "Object Dependent Properties of Multicomponent Acrylic Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1404912862.
Full text
47
Uban, Kristina Andrea. "Effects of prenatal alcohol exposure on interactions between stress and dopamine systems : a potential pathway to increased vulnerability to substance use disorders." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43832.
Full textAbstract:
Effects of prenatal alcohol exposure (PAE) on central nervous system function include an increased prevalence of substance use disorders (SUDs). Dopaminergic systems provide a key neurobiological substrate for SUDs. The hypothalamic-pituitary-adrenal (HPA) axis and dopamine systems have overlapping neurocircuitries, with stress altering dopamine pathways implicated in drug-related reinforcement and motivation, and conversely drug exposure activating stress systems, enhancing sensitivity to subsequent stressors. PAE alters both HPA and dopaminergic regulation, resulting in increased HPA tone and an overall reduction in tonic dopamine activity. Thus, alterations in HPA-dopamine interactions in PAE subjects may provide a neurobiological mechanism underlying enhanced vulnerability to SUDs. Adult Sprague- Dawley offspring from PAE, pair-fed, and ad libitum-fed control groups were examined. In Chapter 2, the effects of PAE and stress on basal regulation of stress and dopamine systems are discussed. Subjects were subjected to either chronic variable stress (CVS) or no stress conditions, and corticotropin releasing hormone (CRH) mRNA, as well as glucocorticoid and dopamine receptor expression, were measured under basal conditions. In the hippocampus, glucocorticoid receptor (MR) mRNA levels were lower in PAE than control females under non- CVS conditions, while CVS resulted in broader upregulation of MR in PAE compared to control males. A decrease in dopamine receptors was observed following CVS exposure in control but not in PAE subjects. Overall, PAE enhanced sensitivity to CVS and attenuated the effects of chronic stress on basal dopamine receptor expression, and did so in a sexually-dimorphic manner. In Chapter 3, repeated exposure to d-amphetamine (AMPH) induced behavioral sensitization in PAE but not control subjects, and this behavioral measure is positively correlated with vulnerability to SUDs. The current study also assessed cross-sensitization between AMPH and stress, and indeed PAE facilitated cross-sensitization between AMPH and stress, and did so in a sexually dimorphic manner. PAE altered AMPH-stress interactions, and did so in a manner consistent with increased neurobiological vulnerability to SUDs. Together, the present results enhance our understanding of PAE effects on the cross-talk between dopamine and stress systems, and provide insight into underlying mechanisms influencing the increased prevalence of SUDs among individuals with an FASD.
48
Swan, Timothy Willliam. "The use of higher plant cell suspension cultures in the development and assessment of in vitro biomarker systems to detect xenobiotic exposure." Thesis, University of Derby, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411967.
Full text
49
Masey, Nicola. "Development and evaluation of portable passive and real-time measurement systems, and dispersion models, to estimate exposure to traffic-related air pollutants." Thesis, University of Strathclyde, 2018. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=29435.
Full textAbstract:
This research developed efficient applications of portable measurement systems to assess human exposure to traffic-related air pollution through direct measurement, and evaluation of exposure models. Passive NO2 samplers are deployed at large numbers of sites in epidemiological studies to estimate typical concentrations over 1-4 weeks. I found that deployment time could be reduced to 2 days with limited impact on the accuracy and precision of exposure estimates. This shorter measurement time enabled observation of wind-speed effects leading to overestimation of ambient concentrations by passive samplers. Through development of a post-processing technique and/or inclusion of a membrane I improved sampler accuracy. Portable sensors can provide detailed estimates of personal exposures to air pollution. Many sensor-based monitors have not been subject to rigorous testing procedures to quantify their accuracy. I observed that the most accurate estimates of concentrations from NO2 and O3 sensor-based monitors required regular, intermittent calibration against reference analysers under similar environmental conditions to field measurements. I also found deterioration in BC monitor accuracy and precison when the attenuation of the collection filter exceeded 40 and no improvement in monitor accuracy was observed when filter darkness correction algorithms were applied. Portable sensors can be used to identify locations with higher concentrations, which may require more detailed monitoring. I established that repeated 6-minute measurements of BC and particle number concentrations estimated similar spatial trends to 1-week NO2 measurements using passive samplers. Dispersion models can be used to estimate pollution exposure at multiple locations over a study area. I found that initial user parameterisation in a weather model had limited effect on pollution estimates from a dispersion model. I evaluated a new GIS-based dispersion model (5 x 5 m NO2 estimates for a 3,500 km2 area, with model run times of under 10 minutes). I demonstrated that inclusion of discrete street canyon models and geospatial surrogates (accounting for urban morphology) improved model accuracy. The measurement and modelling evaluation research in this thesis complimented each other by providing efficient ways to directly measure population exposures.
50
Ratti, James A. "INVESTIGATING SMOKE EXPOSURE AND CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) WITH A CALIBRATED AGENT BASED MODEL (ABM) OF IN VITRO FIBROBLAST WOUND HEALING." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5441.
Full textAbstract:
COPD is characterized by tissue inflammation and impaired remodeling that suggests fibroblast maintenance of structural homeostasis is dysregulated. Thus, we performed in vitro wound healing experiments on normal and diseased human lung fibroblasts and developed an ABM of fibroblasts closing a scratched monolayer using NetLogo to evaluate differences due to COPD or cigarette smoke condensate exposure. This ABM consists of a rule-set governing the healing response, accounting for cell migration, proliferation, death, activation and senescence rates; along with the effects of heterogeneous activation, phenotypic changes, serum deprivation and exposure to cigarette smoke condensate or bFGF. Simulations were performed to calibrate parameter-sets for each cell type using in vitro data of scratch-induced migration, viability, senescence-associated beta-galactosidase and alpha-smooth muscle actin expression. Parameter sensitivities around each calibrated parameter-set were analyzed. This model represents the prototype of a tool designed to explore fibroblast functions in the pathogenesis of COPD and evaluate potential therapies.