Tesis sobre el tema "Extinction"
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1
Breazeale, Dorothy Elizabeth. "Extinction Events". Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1427876606.
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Powell, Eileen A. "Extinction of experience". Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1181666217/.
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Plendl, Wolfgang. "Extinction learning in mice". Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-121216.
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Золотова, Світлана Григорівна, Светлана Григорьевна Золотова, Svitlana Hryhorivna Zolotova y S. O. Gordienko. "The extinction of species". Thesis, Вид-во СумДУ, 2007. http://essuir.sumdu.edu.ua/handle/123456789/17567.
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Massive extinctions have occurred five times during the earth's history, the last one was the extinction of the dinosaurs, 65 million years ago.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/17567
5
Vurbic, Drina. "Mechanisms of Secondary Extinction". ScholarWorks @ UVM, 2010. http://scholarworks.uvm.edu/graddis/237.
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Pavlov (1927) first reported that following appetitive conditioning of multiple stimuli, extinction of one CS attenuated responding to others which had not undergone direct extinction. Four experiments with rat subjects investigated potential mechanisms of this secondary extinction effect. Experiment 1 assessed whether secondary extinction would be more likely to occur with target CSs that have themselves undergone some prior extinction. Two CSs were initially paired with shock. One CS was subsequently extinguished before the second CS was tested. The target CS was partially extinguished for half the rats and not extinguished CS for the other half. A robust secondary extinction effect was obtained with the non-extinguished target CS. Experiment 2 investigated whether secondary extinction occurs if the target CS is tested outside the context where the first CS is extinguished. Despite the context switch secondary extinction was observed. Extinction of one CS was also found to thwart renewal of suppression to a second CS when it was tested in a neutral context. Experiment 3 examined whether secondary extinction can be attributed to mediated generalization caused by association of the CSs with a common US during conditioning. Rats received conditioning with three CSs and then extinction with one of them. Secondary extinction was observed with a shock-associated CS when the extinguished CS had been associated with either food pellets or shock, suggesting that secondary extinction is not US-specific and is thus not explained by this mediated generalization mechanism. Experiment 4 examined whether intermixing trials with the two stimuli during conditioning is necessary for secondary extinction to occur. Rats were either conditioned with intermixed trials as in Experiments 1-3, or with blocked trials of each CS presented in conditioning sessions separated by a day. Secondary extinction was observed only in the former condition. The results are consistent with the hypothesis that CSs must be associated with a common temporal context for secondary extinction to occur.
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Winer, Daniel H. "The development and meaning of firefighting, 1650-1850". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 351 p, 2009. http://proquest.umi.com/pqdweb?did=1833647391&sid=8&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Barnard, Linda L. "The Effects of Conditioned Reinforcers on Extinction When Delivered on Schedules of Extinction". DigitalCommons@USU, 1990. https://digitalcommons.usu.edu/etd/5985.
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The purpose of the present research was to examine extinction of responding with regard to the rapidity and thoroughness of the process when conditioned reinforcement was available on one of five schedules during extinction. Forty-five mixed-breed pigeons served as subjects with 15 in each of three experiments. Reinforcement training schedules were as follows: Experiment 1, continuous; Experiment 2, fixed ratio 15; Experiment 3, variable-interval one-minute. After training, subjects experienced one of five extinction procedures (here called schedules of extinction) which were as follows: traditional schedule without keylight did not provide conditioned reinforcement; traditional with keylight had the keylight on continuously but withheld other conditioned reinforcement (no schedule, per se, was used); the remaining three schedules (i.e., continuous, fixed ratio 15, and variable-interval one-minute) provided the following four conditioned reinforcers: the sound of the food magazine, the hopper light, the sight of food, and the keylight. Predictions for responding were based on the discrimination hypothesis which states that the more alike training and extinction conditions are, the slower the process of extinction. In order to compare response rates among subjects, a percentage of baseline responding was computed. Four spontaneous recovery tests were conducted to measure the thoroughness of the extinction procedures. Results did not support predictions based on the discrimination hypothesis; that is, subject response rates did not appear to be affected by the similarity of the extinction condition to previous training history. The second finding was that the most rapid and thorough extinction was obtained when the extinction schedule was traditional without keylight. When conditioned reinforcement was available, the continuous extinction schedule produced the most rapid and thorough extinction. The third major finding was that the schedule of unconditioned reinforcement was more predictive of extinction responding than was the conditioned reinforcement schedule during extinction. The last finding was that a subject's pattern of responding was typical of the schedule whether it was on an unconditioned or a conditioned reinforcement schedule. It is suggested that extinction-of-a-human-intervention strategies might be more effective if conditioned reinforcement was identified and controlled.
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Gabriele, Amanda. "Multiple memory systems and extinction". Texas A&M University, 2005. http://hdl.handle.net/1969.1/2384.
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Several lines of evidence suggest that initial acquisition of learned behavior
involves multiple memory systems. In particular, lesions of the hippocampus impair the
acquisition of cognitive or relational memory, but do not impair the acquisition of
stimulus-response habits. Extinction behavior also involves new learning, and therefore
it is possible that multiple forms of memory may also underlie extinction.
We examined this hypothesis by training rats in a task in which extinction
behavior could putatively be acquired by either a cognitive or habit memory system.
Adult male Long-Evans rats were initially trained to run in a straight alley maze for food
reward. Following training they were placed into one of two extinction conditions. In
one condition rats were allowed to run to an empty goal box (i.e. response extinction). In
a second condition rats were placed into an empty goal box without making a running
response (i.e. latent or non-response extinction). Prior to each daily session of extinction
training, rats received intra-hippocampal infusions of either the local anesthetic
bupivacaine (0.75% solution/0.5 ul), or saline.
Rats receiving saline infusions displayed extinction behavior in both the response
and non-response conditions. In contrast, rats receiving intra-hippocampal infusions ofbupivacaine extinguished normally in the response condition, but did not display nonresponse
extinction. This latent extinction effect was enhanced by decreasing the amount
of time between the last extinction trial and the probe trial. Additionally, administering
extinction training and probe trials in different contexts did not appear to prevent latent
extinction, however large variability may be masking this effect. The new context
administered during extinction prevented latent extinction in some animals, but not
others. These findings suggest that, similar to initial acquisition, the learning that occurs
during extinction also involves multiple memory systems. Specifically, the hippocampus
may selectively mediate extinction under conditions in which new stimulus-response
learning is prevented.
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Kurosoy, Ersel. "Opposed jets, flames and extinction". Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402177.
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Reed, Melissa. "Computer modelling of mammoth extinction". Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297314.
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Hansford, James. "Diversity and extinction in Aepyornithidae". Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/424753/.
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The Aepyornithidae are an insular radiation of giant birds from the late Quaternary of Madagascar which have been extinct for c. 1000 years. Complex and conflicting historical taxonomic hypotheses have limited study into these charismatic megafauna and they have been subject to little modern study in comparison to other avian megafauna and the mammalian megafauna of Madagascar. This thesis is the first modern study of Aepyornithidae to quantify the diversity and biogeography of skeletal remains in comparison to putative taxonomic hypotheses. Clarifying the convoluted history of historically proposed taxa underpins a modern framework for studying these enigmatic birds. A novel chronological sequence of high-quality radiocarbon dates provides the most reliable evidence for their species-specific extinction timings. Late survival of these birds contrasts markedly with rapid extinction processes observed in avian megafauna and presents an extended period of co-occurrence with human colonists suggesting complex and poorly understood interactions. Recording and dating evidence of butchery to modern osteological standards has provided unique and extraordinary evidence of human settlement 6000 years earlier than any other evidence suggests, and is the first verifiable information on direct impacts of butchery and hunting of Aepyornithidae. Dietary analysis demonstrates that these morphologically diverse species fulfilled different ecological niches, including extensive grazing behaviour in the central highlands. This promotes the need for new discussions into the pristine landscape of Madagascar, including more expansive investigations into aepyornithid ecosystem functions and the pre-human distribution of grassland savannah versus forested regions. It is hoped that this thesis will lead to novel research into Aepyornithidae and develop understanding of their role in defining the natural state of one of the worlds most threatened ecosystems.
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Quinto, Clara. "Extinction of type II supernovae". Thesis, Uppsala universitet, Observationell astrofysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-415497.
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Bartlett, Alastair Ian. "Auto-extinction of engineered timber". Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31052.
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Engineered timber products are becoming increasingly popular in the construction industry due to their attractive aesthetic and sustainability credentials. Cross-laminated timber (CLT) is one such engineered timber product, formed of multiple layers of timber planks glued together with adjacent layers perpendicular to each other. Unlike traditional building materials such as steel and concrete, the timber structural elements can ignite and burn when exposed to fire, and thus this risk must be explicitly addressed during design. Current design guidance focusses on the structural response of engineered timber, with the flammability risk typically addressed by encapsulation of any structural timber elements with the intention of preventing their involvement in a fire. Exposed structural timber elements may act as an additional fuel load, and this risk must be adequately quantified to satisfy the intent of the building regulations in that the structure does not continue burning. This can be achieved through timber’s natural capacity to auto-extinguish when the external heat source is removed or sufficiently reduced. To address these issues, a fundamental understanding of auto-extinction and the conditions necessary to achieve it in real fire scenarios is needed. Bench-scale flammability studies were undertaken in the Fire Propagation Apparatus to explore the conditions under which auto-extinction will occur. Critical conditions were determined experimentally as a mass loss rate of 3.48 ± 0.31 g/m2s, or an incident heat flux of ~30 kW/m2. Mass loss rate was identified as the better criterion, as critical heat flux was shown by comparison with literature data to be heavily dependent on apparatus. Subsequently, full-scale compartment fire experiments with exposed timber surfaces were performed to determine if auto-extinction could be achieved in real fire scenarios. It was demonstrated that auto-extinction could be achieved in a compartment fire scenario, but only if significant delamination of the engineered timber product could be prevented. A full-scale compartment fire experiment with an exposed back wall and ceiling achieved auto-extinction after around 21 minutes, at which point no significant delamination of the first lamella had been observed. Experiments with an exposed back and side wall, and experiments with an exposed back wall, side wall, and ceiling underwent sustained burning due to repeated delamination, and an increased quantity of exposed timber respectively. Firepoint theory was used to predict the mass loss rate as a function of external heat flux and heat losses, and was successfully applied to the bench-scale experiments. This approach was then extended to the full-scale compartment fire experiment which achieved auto-extinction. A simplified approach based on experimentally obtained internal temperature fields was able to predict auto-extinction if delamination had not occurred – predicting an extinction time of 20-21 minutes. This demonstrates that the critical mass loss rate of 3.48 ± 0.31 g/m2s determined from bench-scale experiments was valid for application to full-scale compartment fire experiments. This was further explored through a series of reduced-scale compartment fire experiments, demonstrating that auto-extinction can only reliably be achieved if burnout of the compartment fuel load is achieved before significant delamination of the outer lamella takes place. The quantification of the auto-extinction phenomena and their applicability to full-scale compartment fires explored herein thus allows greater understanding of the effects of exposed timber surfaces on compartment fire dynamics.
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Knott, Stewart H. "Processes surrounding the extinction of Dentoglobigerina altispira : a case study of the 'paradox of pelagic extinction'". Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441337.
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Neshausen, Leanne. "Variability in Extended and Alternating Extinction". The University of Waikato, 2008. http://hdl.handle.net/10289/2228.
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Hens were trained to peck a square stimulus on a touch-sensitive screen under an FR5 reinforcement schedule for a maximum of 30 reinforcers (taking approximately 10 minutes). Then hens experienced extinction sessions of 40 minutes duration. For a total of six conditions, reinforcement and extinction conditions were alternated. Each condition consisted of between approximately 7 and 10 sessions. Results show that structures developed during conditioning remain in extinction, at least for the duration of previous reinforcement sessions. After approximately 10 minutes, behaviour becomes more variable. There was also an absence of any 'extinction burst'. Extended extinction conditions, and alternating extinction conditions with reinforcement conditions had little effect on the variability of behaviour, but did influence the rate of responding. Responding persisted a little longer before gradually declining across sessions in the first extinction condition. In extinction conditions 2 and 3 responding tended to occur more as 'peaks'; short periods of increased responding with periods of non-responding between peaks.
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Smith, Fraser D. M. "Case studies in biogeography and extinction". Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334231.
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Bazyan, Saloume. "Sexual selection and extinction in deer". Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-211535.
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By performing a comparative analysis and using phylogenetic relationships of the Cervidaefamily this study aimed to address whether or not sexual selection may play a role in the extinctionof species by making species more vulnerable to extinction. The role of sexual selection in makingspecies more vulnerable to extinction is largely unexplored, and several factors such as ecologicaland life history traits may increase the risk of extinction.In all species of the family Cervidae (Gilbert et al. 2006, Geist 1998,Groves and Grubb2011,Meijaardand Groves2004,Price et al. 2005, Goss 1983) sexually selected characters plays amain role in determining species status and thus potentially their probability of extinction. In thisstudy the intensity of sexual selection (measured as sexual size dimorphism, antler size and matingsystem) and the rate of extinction (IUCN classification and anthropogenic effect) were counted asfactors to determine the role of sexual selection intensity in both species-rich and species-poorclades.By using the programme MESQUITE and phylogenetic trees, the results show an associationbetween species with larger body size and dimorphism, living in open habitats and having largerantler size expanded to more than three tines; such species are mostly non-territorial and formharems during the rutting season. The small species are territorial, live in closed habitats, aremonomorphic and have small antler size limited to two tines or less. Moreover species that aremore subjected to habitat degradation and anthropogenic effects tend to become smaller in size.Extinction risk for the species-rich clades with small sized, territorial and small antler sizedspecies is lower than for those consisting of species with larger antler size, larger body size, livingin open habitats and using harems as mating system.To sum up, the intensity of sexual selection in larger species in deer family put them in risk ofextinction; but on the other site, small species are more adapted to the environment by choosingdifferent strategy in mating system, and reducing antler and body size thus diminishing theextinction risk.
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Maslanka, William Michael. "Extinction of microwave radiation in snow". Thesis, University of Reading, 2017. http://centaur.reading.ac.uk/72703/.
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Global observations of snow cover and snow water equivalent are vitally important for climatological and hydrological studies, at both global and local scales. Passive microwave remote sensing techniques have been used over the past 30 years to produce global estimations of snow water equivalent through empirical calculations. However, the uncertainties surrounding the influence of snow microstructure has led to large errors in snow water equivalent estimation. This study examined the extinction properties of the natural snowpack and produced a new extinction coefficient, for use with the semi-empirical multiple layer Helsinki University of Technology (n-HUT) snow emission model. Snow slabs from the natural snowpack were extracted and observed radiometrically upon bases of different reflectivities, as part of the Arctic Snow Microstructure Experiment (ASMEx). Snow parameters were characterised via traditional snowpit observation techniques, as well as with modern high resolution methods, such as with the SnowMicroPen and X-Ray Computer Tomography analysis. The ASMEx snow slab data were used with a flux coefficient model to calculate six flux absorption and scattering coefficients. The six flux scattering coefficients in the vertical polarization were used with a theoretical absorption coefficient model to create a new empirical extinction coefficient, eliminating the need to use subjective observations. The new extinction coefficient was compared to the original n-HUT extinction coefficient model, through the observation and simulation of snowpack brightness temperatures, obtained as part of the Sodankyl¨a Radiometer Experiment (SoRaX). The derived extinction coefficient produced more accurate simulated brightness temperatures at vertical polarizations, especially at 36.5 GHz. The ability to include snow specific surface area data within the n-HUT model has greatly increased its capability; by increasing the breadth of microstructure parameters to include objective observations of specific surface area, and by increasing the accuracy of simulations of the natural snowpack.
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Colas, Bruno. "Centaurea corymbosa : chronique d'une extinction annoncée". Tours, 1997. http://www.theses.fr/1997TOUR4028.
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Centaurea corymbosa pourret (asteraceae) est une espèce végétale endémique de seulement 3 km#2, sur le massif de la Clape, dans l'Aude. Six populations, qui occupent des falaises calcaires, distantes de 300 m a 2 km, comprennent chaque année de quelques individus reproducteurs a environ 200, pour un total de 500. Afin de comprendre le fonctionnement des populations de cette espèce, dans une perspective de conservation, une approche multi-disciplinaire a été utilisée. La synthèse de résultats démographiques, écologiques, et de génétique des populations, nous permet de mieux comprendre les causes et les conséquences de la rareté de C. Corymbosa. C. Corymbosa est probablement issue d'une espèce répandue, C. Maculosa. Isolée depuis longtemps, C. Corymbosa s'est morphologiquement différenciée de C. Maculosa, et adaptée au milieu particulier que représentent les falaises du massif de la Clape. Actuellement, la métapopulation C. Corymbosa a une dynamique très lente étant donné la faible aptitude colonisatrice de l'espèce, due à la faible dispersion des graines, à l'auto-incompatibilité, et à la monocarpie. Il y a peu de chances que ces caractéristiques évoluent étant donné la structure du paysage et la rareté des événements de fondation, bien que de nombreux sites inoccupés, à proximité des populations naturelles, semblent favorables à l'espèce, comme l'ont montré les résultats préliminaires d'une introduction expérimentale. La survie de l'espèce semble donc dépendre de la viabilité des six populations actuelles, qui échangent peu de gènes et sont de petite taille ; elles sont donc soumises à une forte dérive génétique, et les individus y sont probablement assez consanguins. Il semble que la production de graines soit un facteur clé dans les fortes variations d'effectifs observées dans les populations. La production de graines est essentiellement limitée par la disponibilité des ressources et des pollinisateurs. La prédation joue un rôle négligeable. Il est possible également que, dans les plus petites populations, de faibles taux de fécondation résultent d'une faible diversité allélique aux locus d'incompatibilité, et les forts taux d'avortement, d'un fardeau de mutation élèvé. Nous discutons des implications de ces résultats pour la conservation de C. Corymbosa.
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Renault, Olivier. "Extinction et persistance des especes rares". Paris 6, 2001. http://www.theses.fr/2001PA066211.
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Cette these s'interesse aux especes rares et aux mecanismes de leur persistance. Dans les trois premiers chapitres, nous demontrons la pertinence de la notion de processus quasi-stationnaire comme modele de la dynamique des especes rares et en tirons des consequences pour la conservation de telles especes. Nous analysons en detail le cas du crotale de willard (crotalus willardi). Cette espece bien connue des herpetologistes pour sa rarete, coexiste en plusieurs points de sa distribution avec le crotale rupestre (c. Lepidus klauberi), proche parent phylogenetique et ecologique, mais dont les effectifs sont plus importants. L'analyse de donnees de capture-marquage-recapture nous permet d'etayer l'hypothese selon laquelle c. Willardi se maintient a tres faible effectif dans un etat quasi-stationnaire et d'examiner le role de la regulation par densite-dependance dans sa persistance. Nous repondons ensuite aux questions de la reconnaissance des populations quasi-stationnaires et de la conduction de leur analyse de viabilite. En phase quasi-stationnaire, les populations declinantes s'inscrivent dans un etat de rarete conjoncturelle, que nous opposons a la rarete intrinseque qui s'en distingue par ses causes (regulation densite-dependante plutot que declin demographique) et leurs consequences (breve persistance stationnaire dans le premier cas, maintien sur de longues durees ecologiques, voire geologiques dans le deuxieme). Dans les trois chapitres suivants de cette these, l'exploration de modeles simples nous permet de brosser le premier portrait theorique d'une espece intrinsequement rare : une fecondite moyenne ou forte, une grande sensibilite a la competition intraspecifique, une forte aptitude a la dispersion et un grand rayon d'interaction. Un systeme d'appariement polygyne favoriserait egalement la persistance a long terme.
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Swinburne, Nicola Helga Margaret. "The extinction of the rudist bivalves". Thesis, Open University, 1990. http://oro.open.ac.uk/54415/.
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The rudist bivalves were one of the many and varied groups of organisms to be extinguished at the end of the Cretaceous Period. They were a group of bivalves which evolved during Late Jurassic times to dominate the carbonate shelves on the margins of the Tethys Ocean during the Cretaceous Period. Through Late Cretaceous times their diversity climbed to a peak and then entered a period of rapid decline, resulting eventually in the complete extinction of the group. Theories as to the cause of that extinction should clearly be based upon a knowledge of the detailed pattern of the decline. Most important is the question of the timing of the extinction: How long did it take from the peak of diversity to the elimination of the entire group? Is there one main extinction event - or are there several - or is the pattern a gradual decline? In answering these questions this work adopts a new approach to dating end Cretaceous strata by using strontium isotope stratigraphy. The method works by measuring the 87 Sr/86Sr of palaeo-seawater preserved in marine carbonate, such as the thick low-Mg calcite layer of rudist shells. The 87Sr/86Sr of seawater was changing fairly rapidly through time in the latest Cretaceous. The pattern of change has been established in detail using samples from Boreal sequences of which the ages are known with respect to the belemnite stratigraphy. Using this as a standard graph, Tethyan rudist samples have been dated by a comparison of the Sr isotope ratio. The use of Sr isotope stratigraphy has enabled a time axis to be established, against which the ranges of rudist bivalves and of their facies have been ploued. From these data it can be clearly seen that the ranges of many of the established biostratigraphic markers are in error and that the stage boundaries, as defined by the belemnite and planktonic foraminiferal stratigraphies, are offseL When the pattern of rudist diversity is plotted against this time scale it can be seen that, at a specific level, the rudists were at their most diverse at the Campanian/Maastrichtian boundary. Their decline lasted until I almost the end of the Maastrichtian after which the only survivors are Tertiary forms. The decline is related to the disappearance of rudist facies with the end Cretaceous regression, though that graph is slightly displaced from that of rudist diversity. This shows that the rudist extinction is not merely due to non-exposure of terminal Maastrichtian strata.
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Lilly, Bryanna R. "A Laboratory Human Operant Examination of Extinction Bursts". Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849757/.
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The present study examined operant extinction in a controlled setting using a human operant paradigm. Participants watched a preferred video. During the video, either the video or audio portion of the video was selectively removed, on average every 15 s. Participants could restore the video by pressing a force transducer. In one group, relatively low forces were required (250 g) and in the other relatively high forces were required (750 g). At the 20th and 30th minute during the session, the video or audio was removed but the participants could not restore the component for 30 s. The results showed that responding during the probe increased relative to 30-s periods prior and following the probe, characteristic of an extinction burst. The results also showed that overall we saw increases in force under high force conditions during extinction when presses no longer produced sound or video, and force changed little during the low force conditions. We conclude that extinction bursts are a robust phenomenon that can be demonstrated in humans. Additionally, the topographies, i.e. force, established during baseline and the modality of the consequence appear to be two variables determining the short-term course of extinction.
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Swanson, Timothy Michael. "The international regulation of extinction : an economic analysis of the forces causing and controlling the extinction of species". Thesis, London School of Economics and Political Science (University of London), 1993. http://etheses.lse.ac.uk/1246/.
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This thesis explains the decline of biological diversity as the result of a particular form of dynamic externality inherent within the global development process. Agricultural technology and learning have become embedded within particular species, by reason of species-specific investments, and the diffusion of these technologies has implied the adoption of these particular species as well. The decline of biological diversity has been the consequence of this development process, which carries with it the by-product of a homogenised biosphere. This theory has important implications for the regulation of diverse biological resources, and especially their extinction. It implies that the fundamental force driving extinctions is relative underinvestment in these non-specialised resources and in their ancillary resources: base resources (land) and management requirements. When particular species do not attract investment, they are subject to disinvestment by reason of "mining" (for investment of rents elsewhere), "land use conversions" (for investment of base resources elsewhere), or "overexploitation" (for investment of management resources elsewhere). Decisions concerning the conversion of diverse resources made by individual states are necessarily suboptimal. The mere existence of a range of diversity in biological resources confers global benefits, specifically insurance and informational services. No single state will take these global benefits into consideration when making its disinvestment decisions. The internalisation of these benefits, through international environmental agreements to that effect, is the means by which the decline of biological diversity might be controlled. The international regulation of extinction may take three distinct forms: 1) the creation of dynamically consistent transfer systems to compensate for reduced rates of conversion of diverse resources ("international franchise agreements"); 2) the creation of rent enhancement systems to render nonconversion a more profitable alternative ("international wildlife trade regimes"); or, 3) the creation of appropriation mechanisms that render the nonappriable appropriable ("international intellectual property right regimes").
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Woodall, Anna. "Evaluative ratings in counter-conditioning and extinction /". [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19213.pdf.
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Zhang, Huangwei. "Extinction in turbulent swirling non-premixed flames". Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/254974.
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This thesis investigates the localized and global extinction in turbulent swirling non-premixed flames with Large Eddy Simulation (LES) and sub-grid scale Conditional Moment Closure (CMC) model. The first part of this thesis describes the derivations of the three dimensional conservative CMC governing equations and their finite volume discretization for unstructured mesh. The parallel performance of the newly developed CMC code is assessed. The runtime data coupling interface between the 3D-CMC and LES solvers is designed and the different solvers developed during the course of this research are detailed. The aerodynamics of two swirling non-reacting flows from the Sydney and Cambridge burners are first simulated. The main ow structures (e.g. the recirculating zones) in both cases are correctly predicted. The sensitivity analysis about the influences of turbulent inlet boundary, computational domain and mesh refinement on velocity statistics is conducted. This analysis acts as the preparatory investigation for the following flame simulations. The Sydney swirl diluted methane flame, SMA2, is then simulated for validating the LES/3D-CMC solvers. Excellent agreements are achieved in terms of velocity and mixture fraction statistics, averaged reactive scalars in both physical and mixture fraction space. The local extinction level from the increased central fuel velocity is reasonably predicted. At the experimental blow-off point, the LES/3D-CMC modelling does not obtain the occurrence of complete extinction, but severe extinction occurs at the flame base, qualitatively in line with experimental observations. Localized extinction features of a non-premixed methane flame in the Cambridge swirl burner are investigated and it is found that the occurrence of local extinction is typically manifested by low heat release rate and hydroxyl mass fraction, as well as low or medium temperature. It is also accompanied by high scalar dissipation rates. In mixture fraction space, the CMC cells undergoing local extinction have relatively wide scatter between inert and fully burning solutions. The PDFs of reactedness at the stoichiometric mixture fraction demonstrate some extent of bimodality, showing the events of local extinction and reignition and their relative occurrence frequency. Local extinction near the bluff body in the Cambridge swirl burner is also studied. The convective wall heat loss is included as a source term in the conditionally filtered total enthalpy equation. It shows a significant influence on the mean flame structures, directly linked to the changes of the conditional scalar dissipation near the wall. Furthermore, the degree of local extinction near the bluff body surface is intensified because of the wall heat loss. However, the wall heat loss shows a relatively small influence on the statistics of lift-off height. Finally, the blow-off conditions and dynamics in the Cambridge swirl burner are investigated. The blow-off critical air bulk velocity from LES/3D-CMC is over-predicted, greater than the experimental one by at most 25%. The predicted blow-off transient lasts finitely long duration quantified by the blow-off time, in good agreement with the experimental results. The reactive scalars in both physical and mixture fraction space demonstrate different transient behaviors during blow-off process. When the current swirling flame is close to blow-off, high-frequency and high-amplitude fluctuations of the conditionally filtered stoichiometric scalar dissipation rate on the iso-surfaces of the filtered stoichiometric mixture fraction are evident. The blow-off time from the computations is found to vary with different operating conditions.
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Spash, Clive L. "Bulldozing Biodiversity: The Economics of Optimal Extinction". WU Vienna University of Economics and Business, 2015. http://epub.wu.ac.at/4450/1/sre%2Ddisc%2D2015_01.pdf.
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Many conservationists have become enamoured with mainstream economic concepts and
approaches, described as pragmatic replacements for appeals to ethics and direct regulation.
Trading biodiversity using offsets is part of the resulting push for market governance that is
promoted as a more efficient means of Nature conservation. In critically evaluationg this
position I start by explaining the assumptions behind biodiversity and ecosystem valuation
and how economic logic legitimises, rather than prevents, ongoing habitat destruction and
treats species extinction as optimal. Biodiversity offsets provide a means for operationalising
trade-offs that are in the best interests of developers and make false claims to adding
productive new economic activity. Contrary to the argument that economic logic frees
conservation from ethics, I expose the ethical premises required for economists to justify
public policy support for offsets. Finally, various issues in offset design are raised and placed
in the context of a political struggle over the meaning of Nature. The overall message is that,
if conservationists continue down the path of conceptualising the world as in mainstream
economic textbooks they will be forced from one compromise to another, ultimately losing
their ability to conserve or protect anything. They will also be abandoning the rich and
meaningful human relationships with Nature that have been their raison d'être. (author's abstract)Series: SRE - Discussion Papers
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Gaiger, Frances Jean. "Mid-Pleistocene Extinction of Deep-Sea Ostracoda?" Thesis, University of Canterbury. Geological Sciences, 2006. http://hdl.handle.net/10092/1349.
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A global extinction event has been documented in protozoan foraminifera in the late Pliocene to Pleistocene. The timing of the extinction event varied depending on location, however for Ocean Drilling Project Site 1125, disappearances occurred between 2.5 and 0.57 Ma, with the major decline approximately 1.1 Ma. In order to determine if this event affected benthic organisms other than protozoans, this study was undertaken to determine how podocopid ostracods (Crustacea) recovered Ocean Drilling Program Site 1125 responded. The present study was hindered by the small number of valves recovered; the fact that a large proportion of taxa found were undescribed and new to science; and the current state of taxonomic scheme that is under significant revision. These factors meant that a comprehensive comparison could not be achieved. Despite this, counts of ostracod valves and assessments of diversity from this study reveal a significant increase in both parameters from approximately 900-600 ka. Three possible causes were investigated to account for this increase, sediment type and sample size; affects of taphonomy, mainly dissolution; or an actual biotic 'event'. Statistical analyses showed that although sample size did have some effect, it was not the sole reason for the increase in ostracod numbers. Dissolution had an expected affect on the percentage of juveniles but no correlations were found with other sample characteristics. Sedimentation rate was investigated but this also proved unrelated. Therefore, it is suggested that the increase in total ostracod valves and diversity which occurs between 900 and 600 ka was in fact a natural, biotic 'event'. This preliminary evidence suggests that an oceanographic event that has negatively impacted on the foraminifers has had the reverse affect on the ostracod assemblage, in the sense that both population size and diversity increase during that time.
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Little, Crispin T. S. "The Pliensbachian-Toarcian (Lower Jurassic) extinction event". Thesis, University of Bristol, 1995. http://hdl.handle.net/1983/7b6dcf05-90f5-4bfd-8090-d6eb2a3eeab5.
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Giovangigli, Vincent. "Structure et extinction de flammes laminaires prémélangées". Paris 6, 1988. http://www.theses.fr/1988PA066258.
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Diverses analyses asymptotiques, numeriques ou mathematiques de flammes monoreactionnelles planes ou etirees. Plusieurs etudes numeriques de flammes etirees a cinetique chimique complexe. Limites d'extinction de ces flammes en fonction de la nature du melange gazeux reactif et de l'etirement impose par l'ecoulement
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Lennard, Christopher James. "The causes of avian extinction and rarity". Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/20042.
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Bibliography: pages 144-153.Biological extinction rates have escalated by as much as 1000 times the background extinction rate over the last 1500 years, causing concern over the long-term survival of many species. Avian extinctions since 1600 have been well documented relative to other taxa, as have current levels of avian threat. This study analyses avian extinctions post-1600 and current threats in an attempt to develop some predictive capacity about which avian taxa should be awarded the highest conservation priority. Analyses performed include examinations of the causes of avian extinction and threat, geographical location of extinct and threatened species, prehistoric and historical extinction rates, endemicity, migration, bird body size and phylogenetic diversity. An analysis dealing with historical and phylogenetic aspects of endangered and critically threatened species was performed, from which the world's most threatened species were identified. Factors which were the primary cause of historical extinctions are generally not the primary factors threatening today's extant avifauna. Whilst introduced predators and exploitation were primary causes of historical extinctions, habitat destruction poses the greatest threat to extant birds. Species predisposed to extinction typically have restricted ranges, and, compounded by habitat loss, these ranges are becoming more restricted. This has resulted in mainland-dwelling species becoming as prone to extinction as island-dwelling species have been historically. Introduced predators, however, do still threaten many of the world's most threatened species and their potential effects are highlighted in the phylogenetic analysis. Already, many extinctions may be inevitable over the next 25 years as a result of habitat loss. The magnitude of extinctions across all animal and plant species in the next few decades could be comparable with that of previous mass extinctions unless immediate conservation action is taken. However, future conservation efforts will have to be prioritized, and this study is intended as a contribution towards such a prioritization exercise.
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Bielby, Jon. "Extinction risk and population declines in amphibians". Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/4278.
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This thesis is about understanding the processes that explain the patterns of extinction risk and declines that we see in amphibians, how we can use that understanding to set conservation priorities, and how we can convert those priorities into practical, hands-on research and management. In particular, I focus on the threat posed by the emerging infectious disease, chytridiomycosis, which is caused by the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Amphibians display a non-random pattern of extinction risk, both taxonomically and geographically. In chapter two I investigate the mechanism behind the observed taxonomic selectivity and find that it is due to species biology rather than heterogeneity in either threat intensity or conservation knowledge. In chapter three I determine which biological and environmental traits are important in rendering a species susceptible to declines, focussing on susceptibility to Bd. I found that restricted range, high elevation species with an aquatic life-stage are more likely to have suffered a decline. Using these traits, I predict species and locations that may be susceptible in the future, and which should therefore be a high priority for amphibian research and conservation.
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Kostka, Markus. "Modelling extinction and reignition in turbulent flames". Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/7270.
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The presented work attempts to extend the conditional moment closure method for noon-premixed. turbulent combustion to predict extinction and reignition phenomena in turbulent flames. The conditional moment closure method is one of a class of conserved scalar modelling approaches in turbulent non-premixed combustion. where chemistry is treated as mainly dependend on the mixing of oxidizer and fuel. However. as designers of combustion devices aim for higher turbulence rates to enhance mixing and promote combustion, chemical conversion is not solely determined by the rate at which fuel and oxidizer are mixed, but kinetic effects become important. Therefore it is necessary in these cases. to consider a second variable to govern the evolution of the chemical system. This variable will parameterize the chemical conversion process from cold. mixed reactants at fixed eguivalence ratio to an eguilibrium state. Equations describing the chemical system as a function of these two variables, the conserved scalar, commonly referred to as mixture fraction and the progress variable. can be derived and constitute the doubly conditioned moment closure equations. However, solution of this set of equations is computationally expensive and key parameters describing the rate of dissipation of the progress variable, which is a reactive scalar, are not yet fully understood. By considering conditional fluctuations of the progress variable, applying simple relationships for scalar dissipation and using a pre-computed functional dependence of conditional moments on the progress variable, the effect of double conditioning on the chemical source term and on the overall chemistry predictions can be examined. The methodology is tested for its capability to predict the turbulent. piloted flames of the Sandia D-F series. These laboratory flames show an increasing degree of local extinction and reignition due to varying turbulence levels. Hence they provide an ideal benchmark for the study of models trying to predict these phenomena.
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Fritz, Susanne. "Comparative analyses of extinction risk in vertebrates". Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5275.
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Measures of current extinction risk imply that a high proportion of the world’s species are threatened with global extinction in the near future, stressing the need for thorough understanding of extinction processes. In this thesis, I investigate three aspects of current global species extinction risk, using novel phylogenetic and spatially-explicit comparative methods. First, I develop a new measure of the phylogenetic-signal strength in extinction risk, and use it to show that the nonrandomness in global mammalian extinction risk differs with threatening processes. These results imply that the biological traits which increase species’ susceptibility depend on the anthropogenic threat experienced. Secondly, I investigate the focus of current extinction risk, both spatially and in terms of biological traits increasing risk. I model regional extinction-risk correlates for mammals across the globe, finding strong geographical variation in the influence of biological traits on risk, and in trait interactions with anthropogenic impacts. I also compare biological and anthropogenic correlates of global extinction risk across and within mammals, birds and frogs. Results from this large-scale comparative study further confirm the strong heterogeneity of extinction processes, with taxon-specific traits playing a relatively large role in determining species’ fates. Finally, I estimate possible impacts of current extinction risk using three measures of global mammalian diversity: species richness, phylogenetic diversity and functional diversity. My results show that selective losses of large species will deplete functional variety in mammals, especially in the tropics. Loss of functional diversity is much higher than expected under random species loss, and there is low congruence with losses of species richness and phylogenetic diversity. The selectivity of current extinction risk means that we stand to lose a very biased sample of global diversity, with potentially severe consequences for ecosystem functioning.
34
Giovangigli, Vincent. "Structure et extinction de flammes laminaires prémélangées". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37613930q.
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Chan, Chung Kiu Jonas. "Mechanisms of the Partial Reinforcement Extinction Effect". Thesis, The University of Sydney, 2019. http://hdl.handle.net/2123/20925.
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The partial reinforcement extinction effect (PREE) is a well-known phenomenon in associative learning. It refers to the paradoxical observation that after an animal has been trained on a partial reinforcement (PRf) schedule, it exhibits greater responding in the face of extinction than an animal that was trained on a continuous reinforcement (CRf) schedule, even if it has received fewer pairings of the conditioned stimulus (CS) and the unconditioned stimulus (US). The current thesis investigated the mechanisms that produce the PREE. We showed that the PREE is eliminated when partially reinforced rats are extinguished using more trials, but not when they are extinguished using longer (but the same number of) trials. This showed that the PREE is influenced primarily by the number of trials presented during extinction. In addition, we found that the number of trials taken to extinguish responding is directly proportional to the proportion of trials reinforced during conditioning. We then investigated accounts of the PREE which suggest that the generalisation of responding during nonreinforcement from partial reinforcement to extinction produces the PREE. There was no effect of pre-exposure to nonreinforcement on the rate of acquisition to a PRf schedule and a CRf schedule, indicating that the process that produces the PREE is not symmetrical as would be expected from a generalisation account. Finally, the role of nonreinforced trials in producing extinction was examined by extinguishing responding while maintaining reinforcement at a much lower rate than during conditioning. We found a PREE despite continuing reinforcement, indicating that animals learn about both the per-trial outcome of the schedule and the expected time to reinforcement. Our results present a challenge for trial-based and time-based models of extinction and the PREE.
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Waterkotte, Megan Elizabeth. "The Role of Caffeine in Memory Extinction". Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/145094.
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Olofsson, Sven. "Extinction in Molecular Clouds : Case of Barnard 335". Doctoral thesis, Stockholms universitet, Institutionen för astronomi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-72523.
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The Bok globule B335 is a small molecular cloud in the solar neighbourhood near the galactic plane. The aim for this three-paper-study is to construct and analyze the extinction for this globule. The method we apply is to use the light from field stars behind the cloud in broadband filters ranging from UV to the mid-infrared. We have observations performed at the ESO telescopes at La Silla and Paranal as well as at the Nordic 2.5 m telescope at La Palma. Together with images and spectra from 2MASS-, ISO- and Spitzer-archives we are able to cover the wavelength range from 0.35 to 24 μm. An important tool to analyze these observations results in order to get the extinction is the grid of synthetic stellar atmospheric spectra provided by Hauschildt (2005). The extinction so received is a result in itself. From the analysis of the extinction wavelength dependence we derive properties of the dust, especially its composition and grain size distribution. By modeling the grain size distribution we are able to find the extinction from the reddening of the stars. We find that the extinction in the optical wavelength 0.35 to 2 μm range nicely follows the functional form described by Cardelli et al. (1989). Our result from the wavelength range redward of 2 μm show an extinction dependent on the part of the cloud examined. For the rim of the cloud we get an extinction similar to that reported earlier for the diffuse interstellar medium. From the central parts of the cloud, however, a higher extinction was found. Our grain size model contains a carbonaceous particle distribution and a silicate one. The result can be explained by depletion of carbon onto carbonaceous grains and also by carbon onto all grains including the silicates. Our modeling of the extinction and our classification of the background stars allow us to - determine the distance to the globule - estimate the gas column density ratio - estimate the mass of globule - get a handle on the dust conversion processes through the grain size distribution From the water- and CO-ice spectra we are able to estimate the ice column densities. We find similar ice column densities for the two ices. The estimates differ, when calculated from band strengths or from Lorenz-Mie calculations of ice mantles on the grain size distribution, by a factor of two.
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Kim, Jee Hyun Psychology Faculty of Science UNSW. "Extinction of conditioned fear in the developing rat". Publisher:University of New South Wales. Psychology, 2008. http://handle.unsw.edu.au/1959.4/41106.
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The present thesis examined extinction of conditioned fear in the developing rat. In the adult rat, the hippocampus is thought to be important for the context-specificity of extinction. Because the hippocampus is a late-maturing structure, it was hypothesised that context-modulation of extinction may be different across development. The first series of experiments investigated reinstatement of extinguished fear in the developing rat (Chapter 2). The results showed that P24 rats exhibited context-specific reinstatement. On the other hand, P17 rats did not exhibit reinstatement of extinguished fear following a US reminder treatment. The failure to see reinstatement in P17 rats was not due to the reminder treatment being ineffective in these rats because the same treatment alleviated spontaneous forgetting in rat this age. The second series of experiments then examined the renewal effect and GABAergic involvement in extinction in P24 and P17 rats (Chapter 3). It was observed that P24 rats displayed renewal whereas P17 rats did not. Also, pre-test injection of FG7142 recovered extinguished fear in P24 rats but not in P17 rats, even across a range of doses. This failure to see any FG7142 effect on extinction in P17 rats was not due to the lack of responsiveness to this drug in these rats because FG7142 was found to be effective in alleviating spontaneous forgetting in rats this age. The third series of experiments then examined the effect of temporary inactivation of the amygdala on extinction and re-extinction in the developing rat (Chapter 4). It was observed that extinction retention is impaired in both P24 and P17 rats if the amygdala is inactivated during extinction training. Interestingly, when a CS that had been previously extinguished and then re-trained was re-extinguished, re-extinction was amygdala-independent if initial extinction occurred at 24 days of age but amygdala-dependent if initial extinction occurred at 17 days of age. That is, amygdala involvement in re-extinction was dissociated across development. Taken together, these experiments provide strong evidence for fundamental differences in mechanisms underlying fear extinction across development. The implications of the findings were discussed in light of the theoretical and neural models of extinction.
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Grenyer, Richard. "Comparative approaches to the prediction of extinction risk". Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408110.
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Worsfold, Nicholas. "The consequences of extinction in experimental aquatic communities". Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489745.
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Predicting the consequences of extinction is an important goal in ecology, due to the accelerating rate of global and local species loss. Cascading extinction~ the extinction of one species as a consequence of the extinction of another, has been demonstrated in several natural ecosystems and is widely predicted by theoretical studies. Extinction may also affect the functioning of ecosystems, as functionally important species may be lost from communities and positive interactions between species may be disrupted. Investigating the consequences of extinction in natural ecosystems is difficult, as removing a species from an area of habitat is often problematic. Also, because indirect effects may take many generations to be revealed, experimental manipulations in natural ecosystems often need to last for several years. Experimental aquatic microcosms provide a new opportunity for conducting removal experiments in small, tractable, communities containing rapidly reproducing species. Here, I present the results of four experiments conducted in such microcosms that . investigated the consequences of the removal ofa species and the effect of temperature and energy on patterns ofextinction. In general, local diversity was robust to the removal of a species. No cascading extinction was observed and some positive effects of extinction for diversity were revealed. Species loss had a positive, negative or no effect on ecosystem functioning, depending upon community composition. Small changes to the identity of the species present in communities had large effects; the consequences of extinction for . . ecosystem functioning was very context-dependent and rare species were important. Temperature and chemical energy interacted to determine species diversity and extinction determinism, making it difficult to predict the consequences of changes to either temperature or chemical energy for extinction without knowledge of the other.
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Bond, David P. G. "Oceanographic changes during the Frasnian-Famennian mass extinction". Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401091.
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McCullough, Trevor. "Intracerebroventricular chlordiazepoxide and the partial reinforcement extinction effect". Thesis, University of Ulster, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284859.
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Cole, Selina R. "Phylogeny, Diversification, and Extinction Selectivity in Camerate Crinoids". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492594839778373.
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Rogers, Valerie R. "Extinction-induced variability in young children with autism /". abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1455657.
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Thesis (M.A.)--University of Nevada, Reno, 2008."May 2008." Includes bibliographical references (leaves 32-34). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2009]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
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Sripakagorn, Paiboon. "Local extinction and reignition in turbulent nonpremixed combustion /". Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/7043.
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O'Leary, S. G. "Context specificity in the extinction of learned fear". Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1462447/.
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This thesis explores the role of context in the extinction of learned fear and environmentally specific renewal of the fear response. It has clinical relevance in relapse of previously extinguished anxiety. Part 1 is a literature review that systematically examines the findings and methodologies within the behavioural field regarding the role of context in extinguished fear relapse in humans. It explores the main areas of investigation and critically appraises each study. Part 2 is an empirical paper examining the effect of contextual change on fear responses following extinction. The research is framed in relation to the wider contextual fear and neurobiological literature and presents clinical and scientific implications. Part 3 is a critical appraisal of Parts 1 and 2. It outlines the background context to the work, the methodological choices, theoretical issues, challenges that arose, and personal reflection on the significance and impact of the project.
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Arnaud, Manon. "L'extinction des conventions et accords collectifs de travail". Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTD035.
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La volonté exprimée par le législateur de renforcer la place de la norme conventionnelle au sein du droit du travail, témoigne de l’importance devant être accordée à l’acte conventionnel de sa formation à son extinction, en passant par son exécution. Cette thèse aura ainsi pour objet d’étudier la phase d’extinction et plus spécifiquement les différents mécanismes conduisant à l’anéantissement des conventions et accords collectifs de travail. L’analyse de ces derniers conduit ainsi à opérer une distinction selon l’origine du fait générateur de l’extinction. L’extinction sera dite assumée lorsqu’elle sera la conséquence directe de la volonté des parties de mettre un terme à l’acte conventionnel. Un tel choix imposera dès lors le recours à la dénonciation ou bien aux conventions et accords à durée déterminée. Par opposition, l’extinction pourra être subie. L’anéantissement de l’acte s’imposera alors aux parties en raison de la survenance d’un événement déterminé. Dans pareilles circonstances, ce sont la mise en cause et la caducité qui devront alors être mises en oeuvre. La pluralité des situations que de tels mécanismes ont vocation à régir atteste de leur pertinence et de leur intérêt. Dès lors, au-delà de leur définition, c’est un régime complet de chacun de ces différents mécanismes d’extinction de l’acte conventionnel qui sera proposé au travers de cette étudeThe decision expressed by the legislator to strengthen conventional norm’s position in labor law, shows the importance of collective bargaining agreement from their conclusion through their application to their extinction. This PhD work aims to study the extinction phase and more precisely various mechanisms which lead to the end of collective bargaining agreements. There should be a clear distinction according to the origin of the operative event. Extinction will be shouldered when it will be the direct result of the choice made by the contracting parties to put an end to collective bargaining agreement. This choice will require the use of specific mechanisms such as denunciation or fixed term collective bargaining agreement. In contrast, extinction can be induced. Extinction should be binding on the parties because of a determinate event occurrence. In such cases different mechanisms have to be used such as caducity or « mise en cause ». These several situations show their relevance and interest. Therefore, beyond their definition a comprehensive scheme for each extinction mechanism will be suggested in this study
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Valles, Rodrigo Jr. "Behavioral mechanisms underlying the extinction of cocaine self-administration". Texas A&M University, 2005. http://hdl.handle.net/1969.1/3105.
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The aim of the present series of experiments was to outline the influence of
different doses of cocaine during training, training schedule, training length and
abstinence duration to modulate subsequent extinction and reinstatement patterns.
Abram AmselÂs general theory of persistence were used to both design and explain
various aspects of these models.
For Experiment 1, rats self-administered cocaine (0.25, 0.50 or 1.00 mg/kg)
intravenously and were then tested in an extinction preparation using saline infusions (5
days) and then only the stimulus light as the reinforcer (3 days). Experiment 2 examined
schedules by magnitude interactions by training rats on two fixed-ratio (FR) schedules
(FR-1 or FR-10 using either 0.25 or 1.00 mg/kg cocaine). Animals were tested in an
extinction protocol (10 days; no stimulus light) and subsequently tested for reinstatement
(1 day) that utilized presentations of the stimulus light. Experiment 3 addressed the
effects of training length (15 or 30 days of training using either 0.25 or 1.00 mg/kg
cocaine) using the same protocol as in Experiment 2. Experiment 4 examined the modulation potential of two abstinence lengths (15 or 30 days using either 0.25 or 0.50
mg/kg cocaine) using the same conditions as Experiment 2.
Experiment 1 indicated the greatest resistance to extinction using the lowest
training dose (0.25 mg/kg). The removal of saline caused an apparent extinction burst
indicative of reward seeking. Experiment 2 showed that animals trained under partial
reinforcement schedules persisted more during extinction. Furthermore, rats trained
using 1.00 were more resistant than those trained with 0.25 mg/kg. Reinstatement of
drug seeking was more pronounced in rats trained using an FR-10 schedule. Experiment
3 indicated greater resistance to extinction in rats trained for 15 versus 30 days. Rats
trained on 0.50 mg/kg for 30 days showed less cue-induced reinstatement than those
trained for 15 days. Experiment 4 showed increased resistance to extinction when rats
were trained on 0.25 mg/kg and forced to abstain for 30 versus 15 days. Directionally
opposite effects were apparent in groups trained with 0.50 mg/kg. Reinstatement data
indicated greater responsivity to cues by animals abstaining for 30 versus 15 days.
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Yuzhe, Li. "Computational Investigations on Uncertainty-Dependent Extinction of Fear Memory". 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225756.
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Gonzalez, Andrew. "Extinction : the role of habitat fragmentation and environmental variability". Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/12032.
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