Spelling suggestions: "subject:"del'extinction"" "subject:"d'extinction""
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Interactions between hippocampal and cerebellar theta oscillations during cerebellar theta-contingent trace eyeblink conditioning acquisition and extinction in the rabbit.Hoffmann, Loren C. 21 April 2014 (has links)
No description available.
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The Effects of Delayed Reinforcement Through a Token Economy on Treating Escape-Maintained-Problem Behavior Without Extinction.Smith, Elle McKenzie 30 August 2017 (has links)
No description available.
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Faunal Distribution Across the Ordovician-Silurian Boundary in Ohio and OntarioFuentes, Stephanie Renee 07 July 2003 (has links)
No description available.
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Evolution of conditional dispersal: a reaction-diffusion-advection approachHambrock, Richard 10 December 2007 (has links)
No description available.
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Avian Metapopulation Dynamics in an Urbanizing LandscapePadilla, Benjamin Juan 27 June 2012 (has links)
No description available.
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Atmospheric Attenuation for Lidar Systems in Adverse Weather ConditionsViklund, Johan January 2021 (has links)
In this study, the weather impact on lidar signals has been researched. A lidar system was placed with a target at approximately 90 m and has together with a weather station collected data for about a year before this study. By using the raw detector data from the lidar, the full waveform can be obtained and the amplitude of the return pulse can be calculated. Atmospheric attenuation of lidar signals is often modeled using the lidar equation, which predicts an exponential decrease in energy over the distance. The factor in the exponent is referred to as the extinction coefficient and it is the main property studied in this thesis. By utilizing models for the extinction coefficient under different weather conditions, it is possible to simulate the performance of the lidar. The extinction coefficient was calculated using different empirical models. The empirical models investigated in this thesis are the Kim and Kruse models for known visibility, the Al Naboulsi model for different types of fog with known visibility, the Carbonneau model for known precipitation amount in rainy conditions, and a similar model for snowy conditions. For the case of rain, a physical model was also used, which is derived through Mie theory. The physical model requires a particle size distribution, which is the number of particles of a certain radius per unit volume. A particle size distribution for rain was generated using the Ulbrich raindrop size distribution, using the precipitation amount recorded by the weather station. Particle size distributions for radiation and advection fog were also simulated. The measured attenuation in lidar signals was compared to the predicted attenuation that was calculated using different models for the extinction coefficient in the lidar equation. Generally, the models tend to underestimate the amplitude of the return pulse. This can partially be explained by the assumptions used to derive the lidar equation, which neglects all augmentation of the beam. The visibility models gave more accurate results compared to the precipitation models. This was expected, since visibility is defined as a measure of attenuation and precipitation amount is not. When a lidar signal is emitted, the light will be reflected from optical surfaces within the lidar and cause a pulse to be detected. This pulse is referred to as the zeropulse. In the first couple of meters of the transmission, we expect to see some backscattered light from adverse weather, since the detector has a larger solid angle at shorter distances. This returned light will be combined with the zeropulse and cause it to expand in width. By examining the zeropulse, it was possible to observe a difference between the average zeropulse under some different weather conditions. This leads to the conclusion that it may be possible to extract some information about current weather conditions from the zeropulse data, given that there is little ambient light and snowy weather conditions. By integrating the zeropulse, variations in the shape of the zeropulse could be described by a single value. Then by separating the data into low and high visibility populations, the zeropulse integral could be used to predict the visibility. The conclusion was that the zeropulse integral can accurately predict whether visibility is above or below a threshold value, given that there is little ambient light and the visibility is known to be below 19950 m.
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Statistical Uncertainty of the Ignition Time, Burning Rate, and Extinction Characteristics of Engineered Timber ProductsDavid, Jacob 01 June 2023 (has links) (PDF)
The characterization of flammability parameters such as time to ignition, mass loss rate (MLR), and extinction criteria is critical for understanding ignition and burning behavior of timber products. These parameters, often determined with bench scale experiments, have previously been presented in literature. However, standard test methods generally use relatively low trial quantities (e.g., n=3) which can potentially cause large variation in reported values. This study investigates the influence of trial quantity on observed statistical variation in key flammability metrics for timber products (e.g., ignition time, peak MLR, MLR at extinction). Using a conical heater, 100 repeat trials were conducted at incident heat exposures of 20 kW/m2, 40 kW/m2, and 50 kW/m2 on 12.7 mm thick ACX cross laminated plywood samples. Ignition time data was found to exhibit significant positive skew and 20-30 trials were required for the reduction in uncertainty with each additional trial to fall below 0.1s at each heat flux. The normalized uncertainty in ignition time was greatest at 50 kW/m2 and was 20-70% than at 20 kW/m2 and 40 kW/m2. Significant variability was observed in the extinction characteristics of samples exposed to 40 kW/m2 where 39 samples experienced self-extinction while the remainder sustained combustion until burnout. Uncertainty in MLR at extinction for these trials was nearly double that of trials exposed to 20 kW/m2. These results exhibit the significance of large trial quantities when determining flammability characteristics.
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THE EFFECTS OF USING BEHAVIORAL SKILLS TRAINING TO TEACH PARENTS TO IMPLEMENT ESCAPE EXTINCTION PROCEDURES IN THE TREATMENT OF PEDIATRIC FEEDING DISORDERSHeckers, Desiree Noelle January 2019 (has links)
The current study evaluated the effects of a Behavioral Skills Training (BST) package on parental implementation of escape extinction in a feeding clinic. Three parents of children enrolled in a clinic-based three-week intensive feeding disorder treatment program participated. The goal of the current study was to improve the already existing parent training component of the clinic’s program by utilizing BST to teach the participants critical skills needed to implement the feeding interventions at home. The BST package included verbal instruction, modeling, and role play with feedback. Generalization probes were conducted during parent-child feeding trials. A multiple baseline across behaviors design demonstrated the effectiveness of the BST package for all participants: percentage of steps implemented correctly increased to high levels for each skill. This study was limited by aspects of the experimental design and lack of generalization data. Future research should aim to close the gaps in the feeding disorder literature regarding parent training; additional research is needed in this subject area. / Applied Behavioral Analysis
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ICHNOLOGY OF THE MARINE K-PG INTERVAL: ENDOBENTHIC RESPONSE TO A LARGE-SCALE ENVIRONMENTAL DISTURBANCEWiest, Logan A. January 2014 (has links)
Most major Phanerozoic mass extinctions induced permanent or transient changes in ecological and anatomical characteristics of surviving benthic communities. Many infaunal marine organisms produced distinct suites of biogenic structures in a variety of depositional settings, thereby leaving an ichnological record preceding and following each extinction. This study documents a decrease in burrow size in Thalassinoides-dominated ichnoassemblages across the Cretaceous-Paleogene (K-Pg) boundary in shallow-marine sections along the Atlantic Coastal Plain (Walnridge Farm, Rancocas Creek, and Inversand Quarry, New Jersey) and the Gulf Coastal Plain (Braggs, Alabama and Brazos River and Cottonmouth Creek, Texas). At New Jersey sites, within a regionally extensive ichnoassemblage, Thalassinoides ichnospecies (isp.) burrow diameters (DTh) decrease abruptly by 26-29% (mean K=15.2 mm, mean Pg=11.2 mm; n=1767) at the base of the Main Fossiliferous Layer (MFL) or laterally equivalent horizons. The MFL has been previously interpreted as the K-Pg boundary based on last occurrence of Cretaceous marine reptiles, birds, and ammonites, as well as iridium anomalies and associated shocked quartz. Across the same event boundary at Braggs, Alabama, DTh of simple maze Thalassinoides structures from recurring depositional facies decrease sharply by 22% (mean K=13.1 mm, mean Pg=10.2 mm; n=26). Similarly, at the Cottonmouth Creek site, Texas, Thalassinoides isp. occurring above the previously reported negative £_13C shift and the first occurrence of Danian planktonic foraminifera are 17% smaller in diameter (mean K=21.5 mm, mean Pg=17.9 mm; n=53) than those excavated and filled prior to deposition of a cross-bedded, ejecta-bearing sandstone complex commonly interpreted as the Chicxulub ¡¥event deposit¡¦. At both of these impact-proximal regions, the Cretaceous and Paleogene burrows were preserved in similar lithologies, suggesting that a reduction in size cannot be attributed to sedimentological factors. At all localities, up-section trends in DTh are statistically significant (fÑfnf¬0.05; non-parametric Kruskal-Wallis test). Using the burrow diameter as a proxy for tracemaker body size, a reduction in DTh above the K-Pg boundary likely reflects dwarfing within the post-extinction community of decapod crustaceans. Dwarfing during the early recovery stages of the end-Cretaceous mass extinction, as recorded by ichnofossils, occurred within glauconite-producing (New Jersey), carbonate (Alabama), and siliciclastic (Texas) depositional environments and appears to be widespread. Because this ichnological signal appears to be a general phenomenon across the crisis interval, trace-fossil analysis provides a potential in-situ field method for constraining and correlating the stratigraphic position of the K-Pg and other extinction events, particularly in the absence of other macroscopic, microscopic, and geochemical indicators. Whereas overprinting of the original marine ichnofabric by morphologically similar continental traces is not a concern in lithified sections of Alabama and Texas, such an occurrence must be considered within unconsolidated sections. Within the Hornerstown Formation of New Jersey, a pervasive Thalassinoides framework contains traces of burrowing bees and wasps. Due to their penetration of up to 1 m, excavations just beyond the weathering front are insufficient for exposing the original marine ichnofabric. Insect burrow diameters (7-25 mm) are within the range of Thalassinoides traces (4-31 mm), exhibit occasional branching, and lack of ornamentation (bioglyphs) on the burrow walls. Therefore neither size nor gross morphology are adequate for distinguishing these widely diachronous and unrelated ichnites, especially when the insect burrows have been filled. However, the presence of backfill menisci and a beige clay halo help distinguish the ancient marine burrows, whereas highly oxidized fill and the occurrence of a terminal brooding chamber are diagnostic of modern insect burrows. / Geology
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Signatures of the megafrugivore extinction on palms with large fruits in MadagascarMéndez Cuéllar, Laura 05 April 2024 (has links)
Seed dispersal is crucial for plants to colonize new habitats and facilitate gene flow between populations. However, Pleistocene extinctions of large-bodied fruit-eating and seed-dispersing animals, known as ‘megafrugivores’, may have hindered the dispersal of plants with large fruits (> 4cm fruit length – ‘megafruits’). Plants with megafruits are common across the flora of Madagascar, especially within the palm (Arecaceae) family. This dissertation investigates the macro-ecological and micro-evolutionary consequences of dispersal limitation on palms with megafruits in Madagascar.
Specifically, I investigated three key aspects: (i) turnover or beta-diversity of palms on Madagascar and the distribution of their dispersal-related traits, (ii) the genetic diversity and genetic structure of three palms with megafruits compared to one palm with small fruits, and (iii) population size and migration rate changes over time of several Malagasy palm species with different ecological characteristics. To address these questions, historical ranges of extinct megafrugivores were reconstructed based on fossil sites, and data on extant frugivores, human activities, and climate were collected. Fieldwork in Madagascar provided genetic data for 12 palm species across 46 populations, from which I generated double digest restriction-site associated DNA sequencing data. Various interdisciplinary methods were employed, including redundancy analyses, variation partitioning, linear mixed effect models, species distribution models, and demographic modelling.
The findings indicate that the current turnover of palms in Madagascar is primarily influenced by extant frugivores and climate, with limited impact from extinct frugivores. Surprisingly, there is no evidence of decreased genetic diversity or increased genetic differentiation in megafruited palms due to the loss of their megafrugivore dispersers. Genetic diversity is positively associated with human population density but negatively influenced by road densities, possibly reflecting habitat fragmentation by humans. Connectivity between populations is linked to the number of shared extinct and extant (mega)frugivore species, for megafruited and small-fruited palm populations, respectively. This highlights the importance of past long-distance dispersal events by megafrugivores and human-mediated dispersal possibly maintaining connectivity for megafruited palms. Population declines are observed across palms since the Last Glacial Maximum, particularly in humid forest species rarely used by humans, while humid forest species with megafruits show recent migration disruption. In contrast, palm species with smaller fruits that are highly used by humans show less pronounced declines and more stable historical migration rates.
Overall, this dissertation illustrates that while the role of megafrugivores as seed dispersers is still evident in the genome of megafruited palms, other factors such as human-mediated dispersal and climate have an influence over the distribution, genetics and demographic histories of palms in Madagascar. It further shows how integrating genetic data with ecological data on species distributions, climate, human activities, can provide novel insights into the drivers of different facets of biodiversity of such a diverse group of plants such as palms.:Chapter 1 - General introduction ....................................................................................... 7
Background and problem statement...................................................................................... 7
Plant seed dispersal, fleshy fruits and frugivory ............................................................ 7
Megafauna and megafruits ............................................................................................ 9
Thesis scope .......................................................................................................................... 12
Madagascar as a model system .................................................................................... 12
Palms as a model system .............................................................................................. 16
Thesis aims and importance ................................................................................................. 19
Overview of methodologies used ......................................................................................... 19
Field data collection ..................................................................................................... 19
Double digest restriction-site associated DNA (ddRAD) .............................................. 21
Outline of the thesis ............................................................................................................. 22
Chapter 2 - Megafrugivores as fading shadows of the past: extant frugivores and the abiotic environment as the most important determinants of the distribution of palms in Madagascar .................................................................................................................... 25
Chapter 3 - Genomic signatures of past megafrugivore-mediated dispersal in Malagasy palms ............................................................................................................................. 39
Chapter 4 - Insights into the demographic history of Malagasy palms: exploring the role of global change and species-specific characteristics ........................................................... 57
Chapter 5 – General discussion ....................................................................................... 73
Summary and key findings.................................................................................................... 73
The fate of megafruited plants in the post-megafrugivore era ........................................... 74
Vulnerability and resilience in megafruited plants .............................................................. 76
Understanding the complex role of humans in the distribution and genetics of megafruited plants ……………………………………………………………………………………………………………………………..77
The influence of abiotic factors over the distribution and genetics of Malagasy palms ..... 78
Outlook ................................................................................................................................. 79
References ...................................................................................................................... 83
Appendix ...................................................................................................................... 101
Appendix Chapter 2 ............................................................................................................ 101
Appendix Chapter 3 ............................................................................................................ 123
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Appendix Chapter 4 ............................................................................................................ 145
Summary ...................................................................................................................... 159
Zusammenfassung ........................................................................................................ 163
Acknowledgments ........................................................................................................ 169
Curriculum Vitae ..................................................................................................................... 171
List of publications and scientific presentations .................................................................... 171
Selbstständigkeitserklärung……………………………………………………………………………………….……..168
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