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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.
1

Kant- och barriäreffekter på älgar och älgbete nära viltstängsel : En studie om hur älgar uppehåller sig och betar nära viltstängslen vid väg E4 mellan Sävar och Bygdeå i Västerbotten

Bergman, Tobias January 2020 (has links)
The aim of this study was to see what effect game fences along road E4 have on moose browsing. I wanted to know if moose browsing escalates close to the game fences or not. I also wanted to know if there is considerable difference in browsing between the east and west side of road E4 in my study area. To test these questions, I performed counts of 60 measurements where I measured moose browsing damage. The measurements were executed 50 to 3000 meters from the fences and were located on both the east and west side of E4. Then I analysed my dataset with correlation analysis to see the relationship between distance from the road and moose browsing. I also compared the amount of browsing damage between the west and east side and used t-test to test the differences in moose browsing. My results showed that moose browsing increased with decreasing distance to the road both measured as percentage damaged and counts of damaged pine trees within each sample. My results also showed that there was significantly more browsing damage on the east side of the road than the west side. The game fences seem to concentrate moose near the fences, and this can result in greater browsing pressure. This should be considered when planning infrastructure and forest management.
2

Μελέτη σύνθετων διακένων αέρα-διηλεκτρικού με καταπόνηση σε κρουστική τάση

Έξαρχος, Σωτήρης 30 April 2014 (has links)
Η παρούσα διπλωματική εργασία πραγματεύεται την επίδραση που επιφέρουν στην τάση διάσπασης διακένου αέρα, διάφορα μονωτικά φύλλα (διαφράγματα) τοποθετούμενα κάθετα προς τον κεντρικό άξονα μεταξύ της διάταξης των ηλεκτροδίων του διακένου και σε διαφορετικές θέσεις μεταξύ της απόστασης αυτών. Η διερεύνηση της επίδρασης των διαφραγμάτων στην διηλεκτρική συμπεριφορά των διακένων είναι γνωστή γενικά και ως το Φαινόμενο του Διαφράγματος (Barrier Effect). Η διάταξη που χρησιμοποιήθηκε για την εκπόνηση της παρούσας εργασίας ήταν διάκενο αέρα ακίδας-πλάκας μήκους 6 cm, και στο ενδιάμεσο των ηλεκτροδίων τοποθετήθηκε το διάφραγμα (Σχήμα 1). Σχήμα 1) Διάταξη διακένου ακίδας-πλακάς με διάφραγμα. Χρησιμοποιήθηκαν 3 διαφορετικά υλικά ως διαφράγματα, ως προς το πάχος τους, με αποτέλεσμα τα σύνθετα διάκενα αέρα-διηλεκτρικού που προκύπτουν να είναι τα εξής: 1) Διάκενο αέρα “ακίδας-πλάκας” με διάφραγμα πάχους 0,2 mm. 2) Διάκενο αέρα “ακίδας-πλάκας” με διάφραγμα πάχους 0,19 mm. 3) Διάκενο αέρα “ακίδας-πλάκας” με διάφραγμα πάχους 0,125 mm. Η καταπόνηση του κάθε σύνθετου διακένου αέρα-διηλεκτρικού έγινε με θετικές κρουστικές τάσεις χειρισμών υπό ατμοσφαιρική πίεση. Για το διάκενο αέρα “ακίδας-πλάκας” μήκους 6 cm με διαφράγματα polyfilm πάχους 0,125 mm και 0,19 mm, διερευνήθηκε η συμπεριφορά αυτών για τρείς διαφορετικές θέσεις ξ=x/D, του διαφράγματος στο διάκενο (x=1, x=2, x=3) και με δύο διαφορετικές περιπτώσεις καταπόνησης για την κάθε θέση ξ του διαφράγματος στο διάκενο. Στην πρώτη περίπτωση το διάφραγμα διατηρήθηκε το ίδιο για κάθε στάθμη τάσεως καταπόνησης του και στη δεύτερη άλλαζε για κάθε στάθμη. Για το διάκενο αέρα “ακίδας-πλάκας” με διαφράγματα τύπου nomex πάχους 0,2 mm, διερευνήθηκε η συμπεριφορά του για έξι διαφορετικές θέσεις ξ του διαφράγματος στο διάκενο. / The aim of this thesis is to investigate the effect of different insulation materials (barriers) into the breakdown voltage of air-gaps, created by two electrodes. The barrier is placed between these electrodes and crosses their central axes perpendicularly, at various locations along this axes. The system used for this work was an air-gap ‘’needle-plate’’, which had a width of 6cm and a barrier placed between the electrodes (figure1). Figure 1) Schematic diagram of ‘’needle-plate’’ air gap with barrier. There were 3 barriers used,of different thicknesses. The resulting air-dielectric gaps formed are as follows: 1) needle plate air-gap, with a 2mm thick barrier. 2) needle plate air-gap, with a 0,19 mm thick barrier. 3) needle plate air-gap, with a 0,125 mm thick barrier. The stress of each air-dielectric gap composite was accomplished using positively impulsed voltage, at atmospheric pressure. In the 6cm wide air gap of the needle plate, a polyfilm barrier was used with a thickness of 0.125 or 0.19mm. The barrier was placed at three different positions between the plates (ξ=x/d; x=1,2,3). At each location, two cases were investigated: 1) the same barrier was kept still and a voltage of various levels was applied and 2) the barrier was varied at each different level of voltage applied. The behaviour/response/efficiency of the air gap needle plate, having a nomex type barrier of 0.2 mm thickness, was investigated, when the barrier was placed at 6 different locations, ξ, between the electrodes.
3

An Agent based Model to Study the Barrier Effect on an Urban Neighborhood

Doucette, Cheri C. 08 May 2012 (has links)
This study asks the question: If we take a small neighborhood and introduce a barrier, how will the neighborhood change? Will it be better protected and flourish, or will it decay and die or perhaps will there be no change at all? What determines the outcome? This work tries to answer these questions by creating an Agent-Based Model (ABM) to test different scenarios and observe the results. Urban environments, both natural and built, are complex systems, containing a multitude of people, landscapes and buildings. Simple changes in street-lighting and sidewalks, the addition of trees and green scapes or the enforcement of “broken-window” policies impact local neighborhoods [1]. Measuring behavior changes on a neighborhood level are difficult to quantify, but by using ABM methods we can build our neighborhood, populate it with a variety of actors and watch their interaction with each other, and with introduced stimuli. Our simulation introduces a barrier (highway) with varying permeability into a mixed use neighborhood loosely based on Richmond’s Jackson Ward. Several metrics (such as property value, crime rates, etc.) were used to determine if the neighborhood was under duress, or thriving. In real-world terms we built a roadway though the neighborhood and observed the “severance effect” as our actors’ adapted to reduced mobility and remained within their accessible range.
4

Barrier Effects Of Roads And Traffic On Animal Occurrence, Space Use, And Movements

Chen, Hsiang Ling January 2015 (has links)
Habitat fragmentation and destruction caused by linear infrastructure, including roads, railways, and power line corridors, are recognized as major threats to biodiversity around the world. Roads can act as barriers by impeding animal movement and restricting animal space use. An understanding of factors that influence barrier effects is important to discern the impacts of habitat fragmentation and to develop appropriate mitigation. The barrier effects of roads are driven by several distinct but not mutually exclusive mechanisms that include traffic, edge, and gap avoidance. We used an endangered forest obligate, the Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis), as our study organism to assess effects of traffic noise on animal occurrence and demonstrated that traffic noise had spatially extensive and negative effects on site occupancy after accounting for effects of distance from roads and the environment. We investigated barrier effects of forest roads and assessed effects of traffic, road edges, and canopy gaps on space use of Mt. Graham red squirrels and compared to the response of introduced, edge-tolerant Abert's squirrels (Sciurus aberti). Forest roads acted as partial barriers for red squirrels regardless of traffic volume likely due to avoidance of canopy gap created by roads, whereas Abert's squirrels showed no avoidance of roads. Therefore, roads restricted movement and space use of a native forest-dependent species while creating habitat preferred by an introduced, edge-tolerated species. Through a meta-analysis of studies that quantified road crossing behavior by mammals, we found that all types of roads, from major highways to narrow forest roads, can impede movement for certain species of mammals. Magnitude of barrier effects of roads decreased as species body mass increased, and was affected positively by increasing road width. We suggest that the species-specific magnitude of barrier effects of roads may be anticipated with basic information from life history traits and road characteristics that are readily accessed through open resources or easily measured.
5

Rodovias atuam como barreira para o fluxo gênico de roedores subterrâneos? : o caso de Ctenomys minutus (Ctenomyidae)

Esperandio, Isadora Beraldi January 2014 (has links)
Rodovias podem fragmentar populações por dois mecanismos, mortalidade e evitamento. Como espécies que evitam rodovias são raramente atropeladas por veículos e, então, não são detectadas em monitoramentos de fauna atropelada, outras abordagens são necessárias para identificar se eles estão sendo afetados. Ctenomys minutus (tuco-tuco) é um roedor subterrâneo que habita campos arenosos nas margens de rodovias e são raramente registrados em monitoramentos de fauna atropelada. Buscamos identificar se as rodovias são uma barreira para o fluxo gênico de tuco-tuco baseado em nove loci de microssatélite. Coletamos amostras de tecido epitelial de indivíduos de quatro populações: duas com a presença (Weber e Amaral) e, como controle, duas com a ausência de rodovia (Maribo I e Maribo II). Mensuramos diversidade genética, diferenciação genética (estatística F) e acessamos estrutura genética (agrupamento bayesiano). Não observamos redução na variabilidade genética e encontramos um baixo nível de isolamento entre Weber e Amaral e um isolamento ainda menor entre Maribo I e Maribo II. O método bayesiano separou os indivíduos em dois grupos, onde Maribo I e Maribo II são um grupo consistente e Weber e Amaral possuem fracas diferenciações. Os resultados nos indicam que um efeito de barreira entre as populações separadas pela rodovia está em processo e que é necessário mais tempo para observarmos de forma mais clara o isolamento. São necessários mais estudos genéticos e comportamentais para certificar este padrão. Sob aspectos práticos, seria adequado monitorar as populações afetadas e, eventualmente, aplicar alguma medida de mitigação na estrada pra proporcionar conectividade. Por fim, a abordagem genética se mostrou muito interessante para avaliar este impacto. / Roads can fragment populations by two mechanisms, mortality and avoidance behavior. Since species that avoid roads are rarely killed by vehicles and thus cannot be detected in roadkill surveys, other approaches are necessary to identify whether they are affected. Ctenomys minutus (tuco-tuco) is a subterranean rodent who inhabits sand fields including at the margins of roads, however is rarely recorded on roadkill surveys. We aimed to identify if roads are a barrier to the gene flow of tuco-tuco based on nine microsatellite loci. We collected tissue samples from individuals of four populations: a pair with the presence (Weber and Amaral) and, as control, a pair with absence of a road (Maribo I and Maribo II). We measured the genetic diversity, the genetic differentiation (F-statistics), and assessed the genetic structure (Bayesian clustering). We observed no reduction in genetic variability and a low isolation level in pairwise comparison of Weber and Amaral, which was even lower between Maribo I and Maribo II. The Bayesian method separated individuals into 2 clusters, where Maribo I and Maribo II are one consistent cluster and Weber and Amaral present weak differentiations. The results indicate that a barrier effect between populations separated by roads is in process. More genetic and behavioral studies are needed to confirm this pattern. Under practical aspects, it would be appropriate to monitor the affected populations and possibly apply some mitigation measure on the road to provide connectivity. Finally, genetic approach proved very interesting to evaluate this impact.
6

Rodovias atuam como barreira para o fluxo gênico de roedores subterrâneos? : o caso de Ctenomys minutus (Ctenomyidae)

Esperandio, Isadora Beraldi January 2014 (has links)
Rodovias podem fragmentar populações por dois mecanismos, mortalidade e evitamento. Como espécies que evitam rodovias são raramente atropeladas por veículos e, então, não são detectadas em monitoramentos de fauna atropelada, outras abordagens são necessárias para identificar se eles estão sendo afetados. Ctenomys minutus (tuco-tuco) é um roedor subterrâneo que habita campos arenosos nas margens de rodovias e são raramente registrados em monitoramentos de fauna atropelada. Buscamos identificar se as rodovias são uma barreira para o fluxo gênico de tuco-tuco baseado em nove loci de microssatélite. Coletamos amostras de tecido epitelial de indivíduos de quatro populações: duas com a presença (Weber e Amaral) e, como controle, duas com a ausência de rodovia (Maribo I e Maribo II). Mensuramos diversidade genética, diferenciação genética (estatística F) e acessamos estrutura genética (agrupamento bayesiano). Não observamos redução na variabilidade genética e encontramos um baixo nível de isolamento entre Weber e Amaral e um isolamento ainda menor entre Maribo I e Maribo II. O método bayesiano separou os indivíduos em dois grupos, onde Maribo I e Maribo II são um grupo consistente e Weber e Amaral possuem fracas diferenciações. Os resultados nos indicam que um efeito de barreira entre as populações separadas pela rodovia está em processo e que é necessário mais tempo para observarmos de forma mais clara o isolamento. São necessários mais estudos genéticos e comportamentais para certificar este padrão. Sob aspectos práticos, seria adequado monitorar as populações afetadas e, eventualmente, aplicar alguma medida de mitigação na estrada pra proporcionar conectividade. Por fim, a abordagem genética se mostrou muito interessante para avaliar este impacto. / Roads can fragment populations by two mechanisms, mortality and avoidance behavior. Since species that avoid roads are rarely killed by vehicles and thus cannot be detected in roadkill surveys, other approaches are necessary to identify whether they are affected. Ctenomys minutus (tuco-tuco) is a subterranean rodent who inhabits sand fields including at the margins of roads, however is rarely recorded on roadkill surveys. We aimed to identify if roads are a barrier to the gene flow of tuco-tuco based on nine microsatellite loci. We collected tissue samples from individuals of four populations: a pair with the presence (Weber and Amaral) and, as control, a pair with absence of a road (Maribo I and Maribo II). We measured the genetic diversity, the genetic differentiation (F-statistics), and assessed the genetic structure (Bayesian clustering). We observed no reduction in genetic variability and a low isolation level in pairwise comparison of Weber and Amaral, which was even lower between Maribo I and Maribo II. The Bayesian method separated individuals into 2 clusters, where Maribo I and Maribo II are one consistent cluster and Weber and Amaral present weak differentiations. The results indicate that a barrier effect between populations separated by roads is in process. More genetic and behavioral studies are needed to confirm this pattern. Under practical aspects, it would be appropriate to monitor the affected populations and possibly apply some mitigation measure on the road to provide connectivity. Finally, genetic approach proved very interesting to evaluate this impact.
7

Rodovias atuam como barreira para o fluxo gênico de roedores subterrâneos? : o caso de Ctenomys minutus (Ctenomyidae)

Esperandio, Isadora Beraldi January 2014 (has links)
Rodovias podem fragmentar populações por dois mecanismos, mortalidade e evitamento. Como espécies que evitam rodovias são raramente atropeladas por veículos e, então, não são detectadas em monitoramentos de fauna atropelada, outras abordagens são necessárias para identificar se eles estão sendo afetados. Ctenomys minutus (tuco-tuco) é um roedor subterrâneo que habita campos arenosos nas margens de rodovias e são raramente registrados em monitoramentos de fauna atropelada. Buscamos identificar se as rodovias são uma barreira para o fluxo gênico de tuco-tuco baseado em nove loci de microssatélite. Coletamos amostras de tecido epitelial de indivíduos de quatro populações: duas com a presença (Weber e Amaral) e, como controle, duas com a ausência de rodovia (Maribo I e Maribo II). Mensuramos diversidade genética, diferenciação genética (estatística F) e acessamos estrutura genética (agrupamento bayesiano). Não observamos redução na variabilidade genética e encontramos um baixo nível de isolamento entre Weber e Amaral e um isolamento ainda menor entre Maribo I e Maribo II. O método bayesiano separou os indivíduos em dois grupos, onde Maribo I e Maribo II são um grupo consistente e Weber e Amaral possuem fracas diferenciações. Os resultados nos indicam que um efeito de barreira entre as populações separadas pela rodovia está em processo e que é necessário mais tempo para observarmos de forma mais clara o isolamento. São necessários mais estudos genéticos e comportamentais para certificar este padrão. Sob aspectos práticos, seria adequado monitorar as populações afetadas e, eventualmente, aplicar alguma medida de mitigação na estrada pra proporcionar conectividade. Por fim, a abordagem genética se mostrou muito interessante para avaliar este impacto. / Roads can fragment populations by two mechanisms, mortality and avoidance behavior. Since species that avoid roads are rarely killed by vehicles and thus cannot be detected in roadkill surveys, other approaches are necessary to identify whether they are affected. Ctenomys minutus (tuco-tuco) is a subterranean rodent who inhabits sand fields including at the margins of roads, however is rarely recorded on roadkill surveys. We aimed to identify if roads are a barrier to the gene flow of tuco-tuco based on nine microsatellite loci. We collected tissue samples from individuals of four populations: a pair with the presence (Weber and Amaral) and, as control, a pair with absence of a road (Maribo I and Maribo II). We measured the genetic diversity, the genetic differentiation (F-statistics), and assessed the genetic structure (Bayesian clustering). We observed no reduction in genetic variability and a low isolation level in pairwise comparison of Weber and Amaral, which was even lower between Maribo I and Maribo II. The Bayesian method separated individuals into 2 clusters, where Maribo I and Maribo II are one consistent cluster and Weber and Amaral present weak differentiations. The results indicate that a barrier effect between populations separated by roads is in process. More genetic and behavioral studies are needed to confirm this pattern. Under practical aspects, it would be appropriate to monitor the affected populations and possibly apply some mitigation measure on the road to provide connectivity. Finally, genetic approach proved very interesting to evaluate this impact.
8

Charakterisierung, Modellierung und Optimierung der Barriereeigenschaften von OP-Textilien

Aibibu, Dilibaier 26 October 2006 (has links) (PDF)
Durch die systematischen und umfangreichen experimentellen Untersuchungen werden in dieser Arbeit erstmalig die Einflüsse der textiltechnologischen Parameter des Garn- und Gewebebildungsprozesses auf die Porenstruktur und die davon abhängige Barrierewirkung von marktrelevanten OP-Geweben grundlegend analysiert. Daraus resultiert der Schwerpunkt der Arbeit – die Erarbeitung von Modellen – mit denen die Zusammenhänge zwischen strukturbedingten Einflussgrößen von Geweben und deren Barrierewirkung gegenüber kontaminierten Flüssigkeiten charakterisiert werden kann. Aufgrund des maßgeblichen Einflusses der Mikrostruktur auf das makroskopische Materialverhalten wird ein hierarchisches Strukturmodell eingeführt, welches zwischen der Makro-, Meso- und Mikroebene unterscheidet. Diese Strukturebenen erfassen die Gewebestruktur in unterschiedlichen Modellierungsniveaus. Die Systematisierungskriterien Garnfeinheit, Gewebebindung und Fadendichte beschreiben die Mesoebene. Die Filamentfeinheit und der Filamentquerschnitt sind wesentliche Kenngröße der Mikroebene. Das anhand des Darcy-Gesetzes entwickelte Modell für die Beschreibung der Mesoebene ist anschaulicher und beinhaltet den Einfluss der Bindung und der Formänderungen der Filamentgarne bei der Gewebeherstellung. Bei der Analyse der Porenstruktur werden mit Hilfe der optischen Methode – Bildanalyse – systematische Untersuchungen an der Morphologie des Gewebes durchgeführt, die bisher noch nicht realisierbar waren. Hier besteht die Möglichkeit, in das Gewebeinnere „hineinzusehen“ und sich nicht nur auf die funktionalen Parameter zu beschränken. Um die Transportmechanismen von Mikroorganismen unter praxisrelevanten Bedingungen zu simulieren, wird ein Verfahren entwickelt. Die Entwicklung erstreckt sich auf die Simulation des Drucks und der Reibung sowie die Simulation der im OP-Saal vorhandenen Flüssigkeiten mit synthetischem Blut und mit Mikrokugeln kontaminiertem Wasser. Das Verfahren ergänzt die optischen Untersuchungen und trägt zur Interpretation bei. Die qualitativen mikroskopischen Untersuchungen durch die Betrachtung der Gewebeoberfläche und -querschnitte unterstützen die Lokalisierung der Partikel im und auf dem Gewebe. Sie liefern interessante Aussagen und Informationen über die Durchgangsmechanismen von partikelbeladenen Flüssigkeiten durch das Gewebe. Der experimentelle Teil befasst sich mit der kritischen Auswahl und Charakterisierung repräsentativer OP-Textilien. Die wissenschaftlichen Fragestellungen werden an 6 repräsentativen PES-Filamentgeweben von 23 marktrelevanten PES-Filamentgeweben für OP-Textilien untersucht und beantwortet. Diese werden hinsichtlich des Einflusses der textiltechnologischen Parameter – Filamentfeinheit, -querschnitt, und Filamentgarnfeinheit sowie der webtechnischen Parameter – auf die strukturbedingte Barrierewirkung anhand der entwickelten Modelle und des Penetrationsversuches evaluiert. Auf diesen Ergebnissen aufbauend werden die Ansätze für die Optimierung der Gewebestruktur hinsichtlich der Barrierewirkung erstellt. Durch die Kombination von feinen Garnen mit hoher Fadendichte unter Ausnutzung von technologischen Möglichkeiten werden Mustergewebe aus PES-Mikrofilamentgarnen mit hoher Barrierewirkung hergestellt. Die experimentelle Untersuchung der am Institut für Textil- und Bekleidungstechnik entwickelten Mustergewebe und die theoretischen Modellrechnungen bestätigen das vorhandene textiltechnische Potenzial zur Optimierung von Mikrofilamentgeweben, d. h., einer weiteren Erhöhung der Widerstandsfähigkeit gegenüber partikelbeladenen Flüssigkeiten. Die Porenweiten in der Mesoebene können wirkungsvoll durch den Einsatz von feinen Filamentgarnen und das Erreichen der hohen Fadendichten in beiden Fadensystemen um die 50 % reduziert werden. Im Vergleich zu marktrelevanten OP-Geweben weisen die Mustergewebe eine erheblich hohe Barrierewirkung gegenüber synthetischem Blut und mit Mikrokugeln kontaminiertem Wasser auf. Diese Arbeit zur grundlegenden Analyse der strukturbedingten Barriereeigenschaften bietet Grundlagen für künftig notwendige Entscheidungen in der Produktentwicklung, Produktion, Produktnormung sowie Produktevaluierung. Sie kann in unterschiedliche Richtung fortgesetzt werden und die Optimierung flüssigkeits- und partikeldichter Gewebe im Gesundheitswesen, Reinraumtechnik im Speziellen oder von Schutztextilien im Allgemeinen, aber auch die Konkretisierung und Übertragung der Modellansätze betreffen.
9

Charakterisierung, Modellierung und Optimierung der Barriereeigenschaften von OP-Textilien

Aibibu, Dilibaier 02 November 2005 (has links)
Durch die systematischen und umfangreichen experimentellen Untersuchungen werden in dieser Arbeit erstmalig die Einflüsse der textiltechnologischen Parameter des Garn- und Gewebebildungsprozesses auf die Porenstruktur und die davon abhängige Barrierewirkung von marktrelevanten OP-Geweben grundlegend analysiert. Daraus resultiert der Schwerpunkt der Arbeit – die Erarbeitung von Modellen – mit denen die Zusammenhänge zwischen strukturbedingten Einflussgrößen von Geweben und deren Barrierewirkung gegenüber kontaminierten Flüssigkeiten charakterisiert werden kann. Aufgrund des maßgeblichen Einflusses der Mikrostruktur auf das makroskopische Materialverhalten wird ein hierarchisches Strukturmodell eingeführt, welches zwischen der Makro-, Meso- und Mikroebene unterscheidet. Diese Strukturebenen erfassen die Gewebestruktur in unterschiedlichen Modellierungsniveaus. Die Systematisierungskriterien Garnfeinheit, Gewebebindung und Fadendichte beschreiben die Mesoebene. Die Filamentfeinheit und der Filamentquerschnitt sind wesentliche Kenngröße der Mikroebene. Das anhand des Darcy-Gesetzes entwickelte Modell für die Beschreibung der Mesoebene ist anschaulicher und beinhaltet den Einfluss der Bindung und der Formänderungen der Filamentgarne bei der Gewebeherstellung. Bei der Analyse der Porenstruktur werden mit Hilfe der optischen Methode – Bildanalyse – systematische Untersuchungen an der Morphologie des Gewebes durchgeführt, die bisher noch nicht realisierbar waren. Hier besteht die Möglichkeit, in das Gewebeinnere „hineinzusehen“ und sich nicht nur auf die funktionalen Parameter zu beschränken. Um die Transportmechanismen von Mikroorganismen unter praxisrelevanten Bedingungen zu simulieren, wird ein Verfahren entwickelt. Die Entwicklung erstreckt sich auf die Simulation des Drucks und der Reibung sowie die Simulation der im OP-Saal vorhandenen Flüssigkeiten mit synthetischem Blut und mit Mikrokugeln kontaminiertem Wasser. Das Verfahren ergänzt die optischen Untersuchungen und trägt zur Interpretation bei. Die qualitativen mikroskopischen Untersuchungen durch die Betrachtung der Gewebeoberfläche und -querschnitte unterstützen die Lokalisierung der Partikel im und auf dem Gewebe. Sie liefern interessante Aussagen und Informationen über die Durchgangsmechanismen von partikelbeladenen Flüssigkeiten durch das Gewebe. Der experimentelle Teil befasst sich mit der kritischen Auswahl und Charakterisierung repräsentativer OP-Textilien. Die wissenschaftlichen Fragestellungen werden an 6 repräsentativen PES-Filamentgeweben von 23 marktrelevanten PES-Filamentgeweben für OP-Textilien untersucht und beantwortet. Diese werden hinsichtlich des Einflusses der textiltechnologischen Parameter – Filamentfeinheit, -querschnitt, und Filamentgarnfeinheit sowie der webtechnischen Parameter – auf die strukturbedingte Barrierewirkung anhand der entwickelten Modelle und des Penetrationsversuches evaluiert. Auf diesen Ergebnissen aufbauend werden die Ansätze für die Optimierung der Gewebestruktur hinsichtlich der Barrierewirkung erstellt. Durch die Kombination von feinen Garnen mit hoher Fadendichte unter Ausnutzung von technologischen Möglichkeiten werden Mustergewebe aus PES-Mikrofilamentgarnen mit hoher Barrierewirkung hergestellt. Die experimentelle Untersuchung der am Institut für Textil- und Bekleidungstechnik entwickelten Mustergewebe und die theoretischen Modellrechnungen bestätigen das vorhandene textiltechnische Potenzial zur Optimierung von Mikrofilamentgeweben, d. h., einer weiteren Erhöhung der Widerstandsfähigkeit gegenüber partikelbeladenen Flüssigkeiten. Die Porenweiten in der Mesoebene können wirkungsvoll durch den Einsatz von feinen Filamentgarnen und das Erreichen der hohen Fadendichten in beiden Fadensystemen um die 50 % reduziert werden. Im Vergleich zu marktrelevanten OP-Geweben weisen die Mustergewebe eine erheblich hohe Barrierewirkung gegenüber synthetischem Blut und mit Mikrokugeln kontaminiertem Wasser auf. Diese Arbeit zur grundlegenden Analyse der strukturbedingten Barriereeigenschaften bietet Grundlagen für künftig notwendige Entscheidungen in der Produktentwicklung, Produktion, Produktnormung sowie Produktevaluierung. Sie kann in unterschiedliche Richtung fortgesetzt werden und die Optimierung flüssigkeits- und partikeldichter Gewebe im Gesundheitswesen, Reinraumtechnik im Speziellen oder von Schutztextilien im Allgemeinen, aber auch die Konkretisierung und Übertragung der Modellansätze betreffen.
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The use of highway crossings to maintain landscape connectivity for moose and roe deer

Olsson, Mattias January 2007 (has links)
<p>Increasingly wildlife managers and land managers are challenged to maintain the viability and connectivity among large mammal populations. Thus, it is important that effective highway crossings are identified and optimized with respect to construction cost, facilitation of ungulate movements, and ability to reduce wildlife-vehicle collisions. The use of exclusion fencing to reduce ungulate-vehicle collisions is commonly installed along Swedish highways. However, exclusion fences may pose a threat to the viability of wildlife populations because they serve as barriers to individual movements and may limit accessibility to resources. Various types of wildlife crossings intended to reduce road-kills and increase habitat connectivity across fenced highways have been constructed throughout the world. Previous studies have evaluated the importance of structure design and size for many ungulate species, but few studies involved moose (Alces alces) which is the target species for most large ungulate mitigations in Sweden. The results of the studies are intended to facilitate the development of wildlife crossings and conventional road passages to meet ungulate demands.</p><p>We monitored moose fitted with GPS radio collars and characterized their space and habitat use patterns in southwestern Sweden. Moose had seasonal differences in habitat selection within their home range, and generally preferred clear-cuts and early successional forest, boreal forest, and glades, but avoided agricultural areas and open water. We used infrared remote cameras, track surveys, and GPS telemetry to monitor the use of wildlife crossings and conventional road passages by moose and roe deer (Capreolus capreolus). The upgrading of a non-fenced road to a fenced highway with three wildlife crossings decreased the moose movements across the highway by 67-89 %. Overpass use by moose and roe deer declined with increased traffic volume on the highway and both species walked during periods of low highway traffic volumes and shifted to trotting as traffic intensity increased. Low rates of human disturbances and proximity to forest edges increased use of highway underpasses by roe deer. Moose used large underpasses to a higher degree than small.</p>

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