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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Comparaison de deux méthodes de mesure de la vitamine D en post chirurgie bariatrique malabsorptive de type dérivation bilio-pancréatique / Comparison of two methods for measuring 25-OH vitamin D in the follow-up of patients after bilio-pancreatic diversion bariatric surgery

Chouiali, Ahlem January 2017 (has links)
Introduction: La prévalence de l'hypovitaminose D peut atteindre 90% chez les patients après une chirurgie bariatrique type dérivation bilio-pancréatique (DBP) malgré la supplémentation avec des méga-doses de vitamine D. Notre hypothèse est que la méthode de dosage immuno-compétitive courante de Roche pourrait ne pas reconnaître de façon équimolaire les deux formes de la 25-OH vitamine D (25-OH-D2 et 25-OH-D3), surestimant ainsi la prévalence du déficit en vitamine D et exposant ces patients, et plus particulièrement ceux supplémentés en D2, à un risque de toxicité à la vitamine D. Objectif: Notre objectif était de comparer deux méthodes de dosage sérique de la vitamine 25-OH-D totale : la méthode ECLIA de Roche et la méthode LC-MS/MS chez la population ayant eu une chirurgie bariatrique. Méthode: Il s’agit d’une étude transversale et corrélationnelle avec dosage sérique de la 25-OH-D dans trois groupes : un groupe contrôle de 48 sujets apparemment sains choisis aléatoirement au laboratoire de biochimie clinique et deux groupes de patients post-dérivation bilio-pancréatique un supplémenté en vitamine D3 (n=44) et l’autre en vitamine D2 (n=30). Les patients ont été recrutés au cours de leur visite de suivi à la clinique de l'obésité au CHUS et à l’IUCPQ. Le nombre d'échantillons par groupe a été établi selon les recommandations du Clinical and Laboratory Standard Institute (EPO9-A2-IR). L'étude comparative (régression linéaire, régression de Deming et le graphique des différences de Bland-Altman) a été réalisée en utilisant le logiciel Analyse-it en considérant p <0,05 comme statistiquement significatif. Résultats: La corrélation entre les deux méthodes était acceptable dans le groupe contrôle de sujets apparemment sains et dans le groupe post-DBP supplémenté en vitamine D3 avec des biais moyens respectifs de -1.7% et -9.2%. Cependant, cette corrélation était inacceptable dans le groupe post-DBP supplémenté en vitamine D2 avec un biais moyen de -45.3%. La méthode LC-MS/MS nous a permis de détecter quatre patients (13%) avec excès ou intoxication en vitamine D dans le groupe post-DBP supplémenté en D2, pour lesquels il était nécessaire d'arrêter la supplémentation en vitamine D. Conclusion : Malgré la bonne corrélation apparente entre la méthode Roche et la méthode LC-MS/MS dans le groupe contrôle de sujets apparemment sains et dans le groupe de patients post-DBP supplémenté en vitamine D3, un biais considérable semble exister, en particulier en présence de la 25-OH-D2. La méthode Roche sous-estime la 25-OH-D totale sérique jusqu’à 95.7% et la spectrométrie de masse a conduit à un ajustement posologique pour plus d’un patient sur quatre. La méthode LC-MS/MS est donc la méthode la plus appropriée pour le suivi sécuritaire de la population bariatrique post-DBP supplémentée en vitamine D2. Il est à noter que nos résultats pourraient être généralisés à tous les types de chirurgie bariatrique et autres patients tels que les insuffisants rénaux. Ils permettraient également la mise à jour des recommandations du suivi post-chirurgie bariatrique et le changement des pratiques en optimisant le choix de suppléments en vitamine D (D2 vs D3) en fonction de la méthode de dosage disponible et d’orienter les laboratoires pour le choix de méthodes de dosage dépendamment de la clientèle servie. / Abstract : Introduction: The prevalence of hypovitaminosis D may reach 90 % in patients after BPD despite supplementation with mega doses of vitamin D. Although LC-MS/MS is the gold standard for vitamin D measurements, it is not routinely use in clinical practice. Our hypothesis is that methods of assays currently used in laboratories of Medical Biochemistry for evaluation of serum 25-hydroxyvitamin D may not recognize equimolarly the two forms of 25-OH-D (D2 and D3) thus overestimating the prevalence of vitamin D deficiency supplemented with D2 and exposing patients to the risk of toxicity. Objective: Our objective was to compare the ECLIA from Roche versus the LC-MS/MS method for quantitation of serum 25-hydroxy-vitamin D in patients who have undergone bariatric surgery. Design and methods: Cross-sectional and correlational study was performed on three different groups for the 25-OH-D levels quantitated by both methods. The control group of apparently healthy subjects (n=48) was randomly selected in a clinical chemistry laboratory. Test groups were patients who had undergone bilio-pancreatic diversion (BPD) and were supplemented either with vitamin D2 (n=30) or with vitamin D3 (n=44). Patients were recruited during their follow-up visit to the obesity clinics at the CHUS and at the IUCPQ. The number of samples per group was established according to the Clinical and Laboratory Standard Institute recommendation protocol (EPO9-A2-IR). The study comparing methods (linear regression, Deming and Bland-Altman bias) was performed using the Analyse-it software program considering p < 0.05 as statistically significant. Results: The agreement of LC-MS/MS with the Roche method was acceptable in the apparently healthy subjects group and in the post-BPD D3-supplemented group with an average bias of -1.7% and -9.2%, respectively. However, this agreement was unacceptable in the post-BPD D2-supplemented group with an average bias of -45.3%. The LC-MS/MS enabled us to detect four patients (13%) who had excess vitamin D or intoxication with vitamin D for which it was necessary to stop the supplementation with vitamin D in the D2 -supplemented group. Conclusion: Despite the apparent good agreement between the Roche method and LCMS/MS in the healthy subjects group and in the post-DBP D3-supplemented patient group, a considerable bias seems to exist, particularly in the presence of D2. Results showed that the routine method underestimated total vitamin D ad 95.7% in patients post BPD supplemented with D2. The LC-MS/MS method is therefore the most accurate method to follow the vitamin D2-supplemented bariatric population. This study could generalize the results to all types of bariatric surgeries and other patients such as renal impairment. The study could also update the recommendations of the postbariatric surgery monitoring, and suggest making changes to the clinical practices so as to optimize the choices of vitamin D supplements (D2 vs D3) depending on the assay method available. It could also guide laboratories in choosing methods depending on dosage of clients served.
192

The perceptions of diverted female youth sex offenders regarding the factors that contributed to their offending

Da Costa, Gloria Elizabeth January 2014 (has links)
A comprehensive literature review indicated that there is a dearth of research focusing on female youth sex offenders and even less is known about the perceptions of female youth sex offenders regarding the factors that contributed to their offending. This study explores the perceptions of female youth sex offenders regarding their reasons for offending. The female youth sex offenders in this study indicated that various factors as discussed below contributed to their offending. The empirical findings of this study confirmed that female youth sex offenders are of the opinion that certain problems within their families possibly contributed to their offending behaviour. Some of these characteristics include factors such as divorce, poor parenting skills, domestic violence, substance abuse and lack of basic care and safety, just to mention a few. Female youth sex offenders’ lack of assertiveness, low self-esteem and identity issues were other factors that most probably contributed to their sexual offending. When taking into account that the majority of the participants’ parents were unemployed, poverty was another factor that most likely played a contributory role. Due to poverty in the household some of these youth were forced to relocate to Girls’ Homes, change schools or drop out of school. In order to curb female youth sex offending one would need to address these factors in a multidisciplinary and holistic manner. This study reports an in-depth qualitative understanding of the perceptions of female youth sex offenders regarding factors that contributed to their offending. In addition the last objective of this study will be the formulation of recommendations to address female youth sex offending more effectively. / Dissertation (MA)--University of Pretoria, 2014. / gm2014 / Social Work and Criminology / Unrestricted
193

Bariatric Surgery for Obesity: A Systematic Review and Meta-analysis

Alobaid, Abdulhakeem M. January 2013 (has links)
Obesity is the fifth leading cause of global deaths. The efficacy and safety of obesity treatment is still controversial. The objective of the thesis is to evaluate the efficacy and safety of bariatric surgery, through a systematic review of the current evidence and meta- analysis of important outcomes. Nineteen (19) randomized controlled trials (RCTs) with 1346 participants were included. Bariatric surgery resulted in greater weight loss when compared to non-surgical treatment. Weight loss was also associated with resolution and/or improvement of obesity related comorbidites such as diabetes, hypertension, hyperlipidemia, and sleep apnea. Weight loss and safety varied across the surgical procedures. Biliopancreatic diversion/duodenal switch had the greatest weight loss, followed by sleeve gastrectomy and Roux-en-Y gastric bypass, purely restrictive procedures such as vertical banded gastroplasty and adjustable gastric banding resulted in the least weight loss. Long term, high quality, and adequately powered trials are still needed to support the available evidence
194

Design and operation criteria for urine-diversion ecological sanitation systems with particular reference to public health

Austin, Lorimer Mark 31 January 2008 (has links)
SANITATION, PUBLIC HEALTH AND THE ENVIRONMENT The approach to sanitation worldwide should be ecologically sustainable, i.e. concerned with protection of the environment. This means that sanitation systems should neither pollute ecosystems nor deplete scarce resources. It further implies that sanitation systems should not lead to degrading water or land and should, where possible, ameliorate existing problems caused by pollution. More research and better designs are needed. Human excreta can be rendered harmless, and toilet designs that do this in harmony with agricultural and social customs hold promise for the future. Problems with conventional sanitation systems have been shown to include inadequate institutional capacity to deal with the sanitation process, a fixation with providing either a full waterborne system or a VIP toilet, the social acceptability of various systems, and the perception that dry, on-site sanitation systems are inherently inferior. The basic purpose of any sanitation system is to contain human excreta (chiefly faeces) and prevent the spread of infectious diseases, while avoiding damage to the environment. An alternative sanitation technology known as urine-diversion (UD) performs these functions with fewer operational and maintenance problems than those associated with conventional VIP toilets, (for example, it is a major and expensive operation to desludge full pits, which is not the case with UD toilets as the vaults can be quickly and easily emptied using hand tools) and also provides a free, easily accessible and valuable agricultural resource for those who wish to use it. This technology represents one aspect of an approach, or philosophy, termed “ecological sanitation” or “ecosan.” Key features of ecosan are prevention of pollution and disease caused by human excreta, treatment of human excreta as a resource rather than as waste, and recovery and recycling of the nutrients. In nature, excreta from humans and animals play an essential role in building healthy soils and providing valuable nutrients for plants. Conventional approaches to sanitation misplace these nutrients, dispose of them and break this cycle. UD systems have been successfully implemented in many countries, including South Africa where more than 60 000 of these toilets have been built since 1997. However, despite much research having been carried out internationally and locally, various questions still remain, particularly on the health aspects of operation, maintenance, and excreta use or disposal. Not enough is known about the dehydrating processes taking place inside the faeces vault, and there is still disagreement on safe retention periods and microbiological stability of the final product. The roles of dryness, pH, temperature and time in pathogen destruction also need to be further clarified. In addition, it is critically important that toilet users are able to operate and maintain their systems easily and safely, particularly while emptying the vaults and recycling or otherwise dealing with the contents. Engineers need to understand and take all these issues into consideration before they can properly design and implement sustainable UD sanitation systems. It is therefore important to develop guidelines for sanitation practitioners that set out best practices for construction and operation of UD toilets. Construction recommendations are important because good construction facilitates easy operation, and also promotes rapid pathogen destruction. Easy operation in turn directly influences the health risks associated with removing faecal material from the vaults. Handling of faecal material is an aspect inherent in the operation of UD ecological sanitation systems, because emptying of the vault is usually done using hand tools. If the faecal material is also used for agricultural purposes then further handling must of necessity take place. As such, there is a health concern, both for the person(s) handling the material and for the wider public who may be consumers of the fertilised crops. It is therefore necessary that these health concerns be quantified, in order that proper regulation may take place. <b<CONCLUSIONS FROM THE LITERATURE REVIEW The primary aim of sanitation is to prevent the transmission of excreta-related diseases. However, with all sanitation systems there is a risk of disease transmission related to the handling or use of the end product. Therefore, even a well functioning system could enhance pathogen survival and lead to an increased risk of disease transmission for those handling the end products or consuming crops fertilised with them. A greater understanding of pathogen die-off in dry sanitation systems is required where handling and/or use of excreta are expected. Pathogen destruction in dry sanitation systems, particularly in the vaults of urine-diversion (UD) toilets, is mainly dependent on storage time, pH, temperature, humidity, moisture content, organic content of the faecal material, and type of bulking agent added. It is of utmost importance to ensure that the material is safe to handle. This implies that the primary treatment in the vault should, as far as possible, ensure the required level of safety. While much research has been carried out internationally into pathogen destruction in the vaults of UD toilets, the same cannot be said of South Africa. There is also a wide range of results and conclusions, with recommended storage times varying from six months to two years. Construction and operational guidelines are required in order to assist practitioners in these and other respects. Sound management practices could play an important role in reducing the health risks involved in emptying the vaults of UD toilets and the disposal or further use of faecal material. From the public health viewpoint, it is necessary to reduce, as far as possible, the risk of handling faecal material. To do this, a better understanding of the factors influencing pathogen die-off in the vaults is required. FOCUS OF THIS THESIS The primary aim of this thesis is to investigate the efficacy of various methods aimed at enhancing pathogen destruction in the vaults of UD toilets, with the aim of (a) establishing the best combination of factors/methods, in particular the vault storage period required, and (b) producing guidelines for the construction, operation and regulation of these systems. The overall purpose of the research is to establish safety criteria for handling of faecal material from UD toilets. FIELD TRIALS: MICROBIOLOGICAL EFFECTS ON FOOD CROPS FERTILISED WITH FAECAL MATERIAL FROM URINE-DIVERSION TOILETS Recycling excreta to soils reduces the need for chemical fertilisers; however, pathogens are recycled to humans if improper agricultural practices are followed. Concerns about using faecal material include higher pathogenic content in developing countries compared to that in developed countries. This material, as well as that from other sanitation alternatives in small-scale systems, demands more personal involvement from the users (including handling), which constitutes a higher human exposure level compared to that from conventional piped systems. Nevertheless, it is considered that where the material can improve agricultural productivity, it can contribute to improving the nutritional status of the population, thus improving public health. Although ecosan technology is spreading all over the world, and with it the recycling of excreta to soils, only a few researchers have addressed the problems associated with the revalorization practice or documented the pathogen die-off. Moreover, little data about the microbial quality of ecosan faecal material from developing countries (where the health risks are the highest) are available. The objective of this research was thus to investigate the potential health risks of using faecal material in agriculture by determining the pathogen uptake on the surfaces of the edible portions of the crops. Faecal material of between one and three months old was extracted from a number of UD toilets in the eThekwini (Durban) municipal area. This was used primarily for the experimental work described in the next section, but for the purposes of this particular experiment it was first left in a heap in the open air for a further four months. Thereafter it was used as a soil amendment in the cultivation of spinach and carrots. Detailed microbiological tests were conducted on this material as well as on the in situ soil before sowing and after harvesting, on the irrigation water, and on the harvested crops. Applying different rates of material to spinach and carrots, two common edible crops, it was found that the bacteria and fungi content were only noticeable for the higher application rates (>35t/ha), while the helminth ova content varied, both in leaves and stems, depending on the quantity of material applied. Helminth ova content was, for both crops, more prevalent in leaves, suggesting that the ova adhere preferentially to plants rather than soil. It was thus illustrated that there is a health implication involved in growing edible crops in soils amended with ecosan biosolids. Even if in this case the spinach and carrots were cooked before consumption, normal handling of the crops during harvesting and preparation could have caused infection if personal hygiene was unsatisfactory. It is therefore important that crop growers and consumers, as well as proponents of biosolids use, are aware of the storage and treatment requirements for ecosan biosolids before these are applied to soils where crops are grown. DETAILED INVESTIGATION INTO VAULT PROCESSES It is hypothesised that the most advantageous approach to pathogen destruction in a UD toilet vault is to maximise the effects of various environmental factors, e.g. high pH, high temperature, low moisture, type of bulking agent and storage time. In order to quantify these effects a field experiment was set up consisting of 12 UD toilet vaults, each with a different combination of faeces and bulking agent (soil, ash, wood shavings, NaOH or straw), ventilation (ventpipe / no ventpipe) and vault lid material (concrete, metal or perspex). Faecal material was obtained from UD toilets in the eThekwini area, as described above. Temperature probes, which were connected to a data logger, were inserted in the heaps and the logger monitored over a period of nearly 10 months. This enabled a number of graphs to be drawn illustrating the effect of the above parameters on heap temperature over the experimental period. During the coldest week in winter the mean heap temperatures averaged 16,8°C, while the minimum and maximum averaged 14,8°C and 18,8°C respectively. During the warmest week in summer mean heap temperatures averaged 27,6°C, while the minimum and maximum averaged 25,6°C and 29,3°C respectively. In addition, samples were taken at various intervals from each vault as well as from the main heap of faecal material that was left exposed to the elements. The samples were subjected to microbiological testing in order to quantify the pathogen die-off over time for each vault as well as for the main heap. In the vaults, total coliform reduced by 3 log10 (99,9%) at between 130 and 250 days, faecal coliform between 100 and 250 days, and faecal streptococci from 125 days and longer. In the main heap, these times varied from 115 days for both total and faecal coliform to 140 days for faecal streptococci. Viable Ascaris ova were reduced to zero between 44 and 174 days in the vaults and by 44 days in the main heap. The conclusions drawn from the xperimentation were the following: <ul> <li>Influence of ventpipe Ventilation of the vault by means of a ventpipe does not result in any meaningful difference in either the vault temperature or rate of pathogen die-off.</li> <li>Influence of vault lid material The lid material, and by inference also the material of the vault walls, has no significant effect on the temperature of the heap or the associated pathogen die-off.</li> <li>Type of bulking agent While the type of bulking agent used does not significantly influence the temperature of the faecal material, it does have an effect on the rate of pathogen die-off. The ordinary soil mix was seen to give the best results, and this was ascribed to the effect of competing microorganisms in the soil itself.</li> <li>Influence of sunshine and rain The main heap of material (faeces/soil mix) that was exposed to the elements performed among the best in terms of pathogen die-off. Apart from the influence of competing microorganisms in the soil on the pathogens as described above, this good performance was also ascribed to the effect of UV radiation and alternate wetting/drying and heating/cooling cycles, which suggests that open-air exposure is likely to provide the best treatment.</li></ul> Comparing the results of this research with other local and international research, it appears that there is a great deal of convergence in the results. It is concluded that vaults of UD toilets should be sized for a storage period of 12 months from last use. RECOMMENDATIONS FOR CONSTRUCTION, OPERATION AND REGULATION OF URINE-DIVERSION TOILETS The standard of UD toilets in South Africa varies greatly. While there are many good examples of the technology, there are also many that have been ill-conceived and are badly built and poorly operated. Project implementers are responsible for the quality of sanitation schemes and should be equipped with the necessary information to oversee the process. The guidelines are aimed at providing implementers with, firstly, the necessary technical information to build good quality UD toilets and, secondly, the basic operation and maintenance tasks that should be conveyed to the toilet owners. Basic regulatory guidelines for the responsible authorities are also given. The guidelines are intended to be a stand-alone document and some repetition of information from earlier chapters is thus unavoidable. The technology of urine diversion is introduced, followed by basic design and construction guidelines, including drawings, for the superstructure and vault of a UD toilet. Both single- and double-vault toilets are discussed. A number of photographs are also provided, illustrating good and bad building practices. Further aspects discussed are requirements for urine pipes and ventilation. Operation and maintenance of UD toilets are subsequently covered. Topics discussed are dehydration, odour, fly control, cleaning of the pedestal, disposal of anal cleansing material, urine collection and disposal, clearing of blockages in urine pipes, and faeces management. The above guidelines are aimed at designers, builders and toilet users. However, organisations responsible for administering public and environmental health, such as Departments of Health, Environmental Affairs, etc, as well as the local and regional authorities that actually implement the sanitation schemes, should become actively involved in regulating the operation of UD toilets, particularly the removal and disposal of faecal material. Some regulatory guidelines are therefore also included to assist these organisations to set uniform (high) standards in their respective jurisdictions. RECOMMENDATIONS FOR FURTHER RESEARCH RELATED TO THIS THESIS It is deemed important that the field trials conducted in the various vaults as described earlier are repeated in other climatic areas, for example a hot and dry area, as it is likely that different results regarding recommended minimum storage periods will be obtained. This should be supplemented by trials involving co-composting of the faeces mix with other organic material, in order to compare the efficacy of this method with the dehydration process. Further, vault lids made of PVC should be tested for enhancing heat gain in the vaults. Finally, long-tem measurements of heap pH should be made in order to ascertain if high pH amendments (wood ash, lime, etc) do in fact maintain their initial pH level. Additional field trials, similar to those described earlier for spinach and carrots, should be undertaken with a view to making recommendations regarding maximum application rates of faecal material. These should consist of food crops where the edible portions are either in or near to the soil, such as beetroot, onion, potatoes, tomatoes, etc. Trials involving urine should also be considered in order to determine the most advantageous application rate for the various crops. Another important topic is recommended for further research on the subject of UD toilets. At present, virtually all the UD toilets built in the country have been for communities on the lower end of the income scale and who previously had no formal sanitation facility at all or, at best, an unimproved pit toilet. Research carried out by CSIR in a number of communities has revealed people’s resistance to handling their faecal material, while in others it has not been a problem. There is often a general viewpoint in a village that “the municipality must take the faeces away.” However, willingness has also been expressed in some villages to pay for a faeces removal service. For instance, this has borne fruit in an area of Kimberley with UD toilets where householders pay a local resident to remove the faecal material on a regular basis. This is done by means of a wheelbarrow, and the material is stockpiled at a nearby approved facility from where it is destined for co-composting with other municipal waste. However, this has not yet been attempted on a large scale in an area with hundreds, or even thousands, of UD toilets. While a theoretical desktop study has been carried out on the feasibility of setting up a large-scale faeces collection concern, such an enterprise does not yet exist in the country. It is suggested that one be set up utilising a horse- or donkey-drawn cart in a village, or group of villages, with sufficient UD toilets available to ensure that a viable business can be conducted. The cooperation of the particular local authority will be required. If successful faeces collection/disposal services could be established in areas with UD toilets it would greatly enhance the social acceptability, and therefore the viability, of this sanitation technology. / Thesis (PhD(Civil Engineering))--University of Pretoria, 2008. / Civil Engineering / unrestricted
195

Survey of U.S. Undergraduate Self-Reported Opioid Diversion and Heroin use, Motives, Sources, and Collective Efficacy as Mediating Factors

Plaushin, Mark Francis 01 January 2019 (has links)
Epic morbidity and mortality, and intractability make prescription opioid diversion a wicked problem. Meanwhile, college undergraduates are vulnerable to opioid misuse and its consequences. The purpose of this quantitative study was to assess U.S. undergraduate students' opioid misuse and the relationship between mediating factors. The study's theoretical framework rested on Wakeland's et al. opioid system model and Shaw and McKay's social disorganization theory. This study bridged the gap, measuring collective efficacy and testing its relationship to undergraduate decisions to regulate misuse. Thus, research questions focused on gauging the problem's scope and assessing relationships between factors that drive or potentially regulate diversion. The Campus Opioid Diversion Survey, designed for this study, was administered to a nonrandom, undergraduate survey panel (N = 434), revealing past year opioid misuse at 6.9% and heroin use at 2.9%. While a chi-square test revealed no significant relationship between motives and sources for misuse, significant relationships were found between filling a prescription for opioids and misuse, between opioid and heroin use, and between observing the negative consequences of misuse and social action. An independent samples t-test showed a significant relationship between collective efficacy and social action. Findings show campus diversion remains an emerging health and safety issue, but that collective efficacy indicates a capacity for regulation. Anticipating misuse, public safety stakeholders should complement responses to diversion schemes with continuous assessment, communications that empower student-citizens, and focused promotion of social cohesion that will fuel mitigation via social action aimed at social change.
196

Revitalizace rybníka v katastrálním území Skalička u Hranic / Revitalization of the Small Water Reservoir in the Skalička u Hranic Cadastral Area

Majkus, Martin January 2022 (has links)
The aim of this paper is to propose a comprehensive revitalization of the side pond in the cadastral area of Skalička. As part of revitalization measures, the removal of mud from the pond, fortification of the banks and other modifications in connection with functional structures are proposed. In order to take water into the pond, a concrete diversion structure in the Hlubocky stream bed is designed, connected with pond via open canal with 2 pools, which will substitute the existing supply pipeline. As part of stabilization of the streambed and to overcome height difference, a boulder chute with stilling basin and related modifications are designed. The introductory part is a summary of knowledge from the issue and it explains important terms, historical context and description of basic principles. The next part describes the current situation and conditions in the surveyed locality. The following is a description of the methods and programs that were used for this work. The design part presents the proposed revitalization measures. An essential part of the work is also the varification of the proposed modification in the streambed, using 3D digital terrain model in Atlas DMT and subsequent 1D flow simulation in HEC-RAS.
197

Benthic Community Structure Response to Flow Dynamics in Tropical Island and Temperate Continental Streams

Gorbach, Kathleen R. January 2012 (has links)
No description available.
198

Evaluating The Impact Of Oocea's Dynamic Message Signs (dms) On Travelers' Experience Using A Pre And Post-deployment Survey

Flick, Jason 01 January 2008 (has links)
The purpose of this thesis was to evaluate the impact of dynamic message signs (DMS) on the Orlando-Orange County Expressway Authority (OOCEA) toll road network using a Pre and Post-Deployment DMS Survey (henceforth referred to as "pre and post-deployment survey") analysis. DMS are electronic traffic signs used on roadways to give travelers information about travel times, traffic congestion, accidents, disabled vehicles, AMBER alerts, and special events. The particular DMS referred to in this study are large rectangular signs installed over the travel lanes and these are not the portable trailer mount signs. The OOCEA have been working over the past two years to add several fixed DMS on their toll road network. At the time of the pre-deployment survey, only one DMS was installed on the OOCEA toll road network. At the time of the post-deployment survey, a total of 30 DMS were up and running on the OOCEA toll road network. Since most of the travelers on the OOCEA toll roads are from Orange, Osceola, and Seminole counties, this study was limited to these counties. This thesis documents the results and comparisons between the pre and post-deployment survey analysis. The instrument used to analyze the travelers' perception of DMS was a survey that utilized computer aided telephone interviews. The pre-deployment survey was conducted during early November of 2006, and the post-deployment survey was conducted during the month of May, 2008. Questions pertaining to the acknowledgement of DMS on the OOCEA toll roads, satisfaction with travel information provided on the network, formatting of the messages, satisfaction with different types of messages, diversion questions (Revealed and Stated preferences), and classification/socioeconomic questions (such as age, education, most traveled toll road, county of residence, and length of residency) were asked to the respondents. The results of both the pre and post-deployment surveys are discussed in this thesis, but it should be noted that the more telling results are those of the post-deployment survey. The results of the post-deployment survey show the complete picture of the impact of DMS on travelers' experience on the OOCEA toll road network. The pre-deployment results are included to show an increase or decrease in certain aspects of travel experience with relation to DMS. The results of the pre-deployment analysis showed that 54.4% of the OOCEA travelers recalled seeing DMS on the network, while a total of 63.93% of the OOCEA travelers recalled seeing DMS during the post-deployment analysis. This showed an increase of almost 10% between the two surveys demonstrating the people are becoming more aware of DMS on the OOCEA toll road network. The respondents commonly agreed that the DMS were helpful for providing information about hazardous conditions, and that the DMS are easy to read. Also, upon further research it was found that between the pre and post-deployment surveys the travelers' satisfaction with special event information provided on DMS and travel time accuracy on DMS increased significantly. With respect to formatting of the DMS, the following methods were preferred by the majority of respondents in both the pre and post-deployment surveys: ● Steady Message as a default DMS message format ● Flashing Message for abnormal traffic information (94% of respondents would like to be notified of abnormal traffic information) ● State road number to show which roadway (for Colonial - SR 50, Semoran - SR 436 and Alafaya - SR 434) ● "I-Drive" is a good abbreviation for International Drive ● If the distance to the international airport is shown on a DMS it thought to be the distance to the airport exit The results from the binary logit model for "satisfaction with travel information provided on OOCEA toll road network" displayed the significant variables that explained the likelihood of the traveler being satisfied. This satisfaction model was based on respondents who showed a prior knowledge of DMS on OOCEA toll roads. With the use of a pooled model (satisfaction model with a total of 1775 responses - 816 from pre-deployment and 959 from post-deployment), it was shown that there was no statistical change between the pre and post-deployment satisfaction based on variables thought to be theoretically relevant. The results from the comparison between the pre and post-deployment satisfaction models showed that many of the coefficients of the variables showed a significant change. Although some of the variables were statistically insignificant in one of the two survey model results: Either the pre or post-deployment model, it was still shown that every variable was significant in at least one of the two models. The coefficient for the variable corresponding to DMS accuracy showed a significantly lower value in the post-deployment model. The coefficient for the variable "DMS was helpful for providing special event information" showed a significantly higher value in the post-deployment model. The final post-deployment diversion model was based on a total of 732 responses who answered that they had experienced congestion in the past 6 months. Based on this final post-deployment diversion model, travelers who had stated that their most frequently traveled toll road was either SR 408 or SR 417 were more likely to divert. Also, travelers who stated that they would divert in the case of abnormal travel times displayed on DMS or stated that a DMS influenced their response to congestion showed a higher likelihood of diversion. These two variables were added between the pre and post-deployment surveys. It is also beneficial to note that travelers who stated they would divert in a fictitious congestion situation of at least 30 minutes of delay were more likely to divert. This shows that they do not contradict themselves in their responses to Revealed Preference and Stated Preference diversion situations. Based on a comparison between pre and post-deployment models containing similar variables, commuters were more likely to stay on the toll road everything else being equal to the base case. Also, it was shown that in the post-deployment model the respondents traveling on SR 408 and SR 417 were more likely to divert, but in the pre-deployment model only the respondents traveling on SR 408 were more likely to divert. This is an expected result since during the pre-deployment survey only one DMS was located on SR 408, and during the post-deployment survey there were DMS located on all toll roads. Also, an interesting result to be noted is that in the post-deployment survey, commuters who paid tolls with E-pass were more likely to stay on the toll road than commuters who paid tolls with cash. The implications for implementation of these results are discussed in this thesis. DMS should be formatted as a flashing message for abnormal traffic situations and the state road number should be used to identify a roadway. DMS messages should pertain to information on roadway hazards when necessary because it was found that travelers find it important to be informed on events that are related to their personal safety. The travel time accuracy on DMS was shown to be significant for traveler information satisfaction because if the travelers observe inaccurate travel times on DMS, they may not trust the validity of future messages. Finally, it is important to meet the travelers' preferences and concerns for DMS.
199

Connectionless Approach: A Localized Scheme To Mobile Ad Hoc Networks

Ho, Yao 01 January 2009 (has links)
According to a Gartner Group (www.gartner.com) report in September 2008, the worldwide telecommunications market is on pace to reach $2 trillion in 2008. Gartner predicts that by 2012, the ratio of mobile to fixed connections will exceed 4-to-1. The North American mobile data market grew to 141.1 million connections in 2007, with a compound annual growth rate of 41.7 percent. It is believed that a large portion will be ad hoc and multi-hop connections, which will open many opportunities for Mobile Ad hoc NETwork (MANET) applications and Wireless Mesh Network (WMN) applications. A MANET is a self-organizing multi-hop wireless network where all nodes participate in the routing and data forwarding process. Such a network can be easily deployed in situations where no base station is available, and a network must be build spontaneously. In applications such as battlefield communications, national crises, disaster recovery, and sensor deployment, a wired network is not available and ad hoc networks provide the only feasible means of communications and information access. Ad hoc networks have also become commonplace for gaming, conferencing, electronic classrooms, and particularly vehicle-to-vehicle communications. A Wireless mash network (WMN) is collection of mesh clients and mesh nodes (routers), with mesh nodes forming the backbone of the network and providing connection to the Internet and other network. Their rapid deployment and ease of maintenance are suitable for on-demand network such as disaster recovery, homeland security, convention centers, hard-to-wire buildings and unfriendly terrains. One important problem with MANET is the routing protocol that needs to work well not just with a small network, but also sustain efficiency and scalability as the network gets expanded and the application transmits data in greater volume. In such an environment, mobility, channel error, and congestion are the main causes for packet loss. Due to mobility of mobile hosts, addressing frequent and unpredictable topology changes is fundamental to MANET research. Two general approaches have been considered: connection-oriented approach and connectionless-oriented approach. In the former, the emphasis is on how to reconnect quickly with low overhead when a broken link occurs. Examples of this approach includes includes [5], [9], [10], [16], [26], [28], [29], [34], [44], and [45]. In contrast, connectionless-oriented approach focuses on minimizing the occurrence of broken links. We proposed one such scheme called Connectionless Approach (CLA) and . In CLA, the network area is divided into non-overlapping grid cells, each serving as a virtual router. Any physical router (i.e., mobile host), currently inside a virtual router, can help forward the data packet to the next virtual router along the virtual link. This process is repeated until the packet reaches its final destination. Since a virtual link is based on virtual routers which do not move, it is much more robust than physical links used in the connection-oriented techniques. Simulation results in our previous works and , based on GloMoSim , indicate that CLA performs significantly better than connection-oriented techniques (i.e., AODV, DSR, LAR, GRID, TMNR, and GPSR). The contribution of this work consists of investigating and developing new Connectionless-Oriented Approach for Mobile Ad Hoc Network. Two of the greatest impacts of this research are as follows. First, the new approach is targeted towards robustly support high mobility and large scale environment which has been adapted for vehicle-to-vehicle environment in . Second, the detailed simulations which compare eight representative routing protocols, namely AODV, DSR, LAR, GRID, TMNR, GPSR, CBF, and CLA, under high-mobility environments. As many important emergent applications of the technology involved high-mobility nodes, very little is known about the existing routing methods perform relative to each other in high-mobility environments. The simulation results provide insight into ad hoc routing protocols and offer guidelines for mobile ad hoc network applications. Next, we enhanced and extend the connectionless-oriented approach. The current connectionless-oriented approach, however, may suffer from packet drops since traffic congestion is not considered in the packet forwarding policy. We address this weakness by considering the connectionless-oriented approach with a collision avoidance routing technique. After that, we investigate techniques to enforce collaboration among mobile devices in supporting the virtual router functionality. Many works have been published to combat such problem - misbehaving nodes are detected and a routing algorithm is employed to avoid and penalize misbehaving nodes. These techniques, however, cannot be applied to the connectionless-oriented approach since any node in the general direction towards the destination node can potentially help forward the data packets. To address the security and cooperation issues for connectionless-oriented approach, we introduce a cooperation enforcement technique called 3CE (3-Counter Enforcement). In addition, wireless mesh networks have become increasingly popular in recent years. Wireless mash network (WMNs) are collection of mesh clients and mesh nodes (routers), with mesh nodes forming the backbone of the network and providing connection to the Internet and other network. We propose a paradigm that combines virtual routers and mesh nodes to create a hybrid network call VR-Mesh Network. This hybrid network can reduce number of mesh node needed without decrease the performance of the network.
200

Endovascular Treatment of Intracranial Aneurysms in Small Peripheral Vessel Segments—Efficacy and Intermediate Follow-Up Results of Flow Diversion With the Silk Vista Baby Low-Profile Flow Diverter

Schüngel, Marie-Sophie, Quäschling, Ulf, Weber, Erik, Struck, Manuel Florian, Maybaum, Jens, Bailis, Nikolaos, Arlt, Felix, Richter, Cindy, Hoffmann, Karl-Titus, Scherlach, Cordula, Schob, Stefan 27 March 2023 (has links)
Background and Purpose: Low-profile flow diverter stents (FDS) quite recently amended peripheral segments as targets for hemodynamic aneurysm treatment; however, reports on outcomes, especially later than 3 months, are scarce. This study therefore reports our experience with the novel silk vista baby (SVB) FDS and respective outcomes after 8 and 11 months with special respect to specific adverse events. Materials and Methods: Forty-four patients (mean age, 53 years) harboring 47 aneurysms treated with the SVB between June 2018 and December 2019 were included in our study. Clinical, procedural, and angiographic data were collected. Follow-ups were performed on average after 3, 8, and 11 months, respectively. Treatment effect was assessed using the O’Kelly Marotta (OKM) grading system. Results: Overall, angiographic follow-ups were available for 41 patients/45 aneurysms. Occlusion or significant reduction in aneurysmal perfusion (OKM: D1, B1–B3 and A2–A3) was observed in 98% of all aneurysms after 8 months. Only 2% of the treated aneurysms remained morphologically unaltered and without an apparent change in perfusion (OKM A1). Adverse events in the early post-interventional course occurred in seven patients; out of them, mRS-relevant morbidity at 90 days related to FDS treatment was observable in two patients. One death occurred in the context of severe SAH related to an acutely ruptured dissecting aneurysm of the vertebral artery. Conclusion: The SVB achieves sufficient occlusion rates of intracranial aneurysms originating from peripheral segments, which are comparable to prior established conventional FDS with acceptably low complication rates. However, alteration of a hemodynamic equilibrium in distal localizations requires special attention to prevent ischemic events.

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