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1
Pollard, John. "Adaptive distance sampling." Thesis, University of St Andrews, 2002. http://hdl.handle.net/10023/15176.
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We investigate mechanisms to improve efficiency for line and point transect surveys of clustered populations by combining the distance methods with adaptive sampling. In adaptive sampling, survey effort is increased when areas of high animal density are located, thereby increasing the number of observations. We begin by building on existing adaptive sampling techniques, to create both point and line transect adaptive estimators, these are then extended to allow the inclusion of covariates in the detection function estimator. However, the methods are limited, as the total effort required cannot be forecast at the start of a survey, and so a new fixed total effort adaptive approach is developed. A key difference in the new method is that it does not require the calculation of the inclusion probabilities typically used by existing adaptive estimators. The fixed effort method is primarily aimed at line transect sampling, but point transect derivations are also provided. We evaluate the new methodology by computer simulation, and report on surveys of harbour porpoise in the Gulf of Maine, in which the approach was compared with conventional line transect sampling. Line transect simulation results for a clustered population showed up to a 6% improvement in the adaptive density variance estimate over the conventional, whilst when there was no clustering the adaptive estimate was 1% less efficient than the conventional. For the harbour porpoise survey, the adaptive density estimate cvs showed improvements of 8% for individual porpoise density and 14% for school density over the conventional estimates. The primary benefit of the fixed effort method is the potential to improve survey coverage, allowing a survey to complete within a fixed time and effort; an important feature if expensive survey resources are involved, such as an aircraft, crew and observers.
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Oedekoven, Cornelia Sabrina. "Mixed effect models in distance sampling." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3618.
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Recently, much effort has been expended for improving conventional distance sampling methods, e.g. by replacing the design-based approach with a model-based approach where observed counts are related to environmental covariates (Hedley and Buckland, 2004) or by incorporating covariates in the detection function model (Marques and Buckland, 2003). While these models have generally been limited to include fixed effects, we propose four different methods for analysing distance sampling data using mixed effects models. These include an extension of the two-stage approach (Buckland et al., 2009), where we include site random effects in the second-stage count model to account for correlated counts at the same sites. We also present two integrated approaches which include site random effects in the count model. These approaches combine the analysis stages for the detection and count models and allow simultaneous estimation of all parameters. Furthermore, we develop a detection function model that incorporates random effects. We also propose a novel Bayesian approach to analysing distance sampling data which uses a Metropolis-Hastings algorithm for updating model parameters and a reversible jump Markov chain Monte Carlo (RJMCMC) algorithm for assessing model uncertainty. Lastly, we propose using hierarchical centering as a novel technique for improving model mixing and hence facilitating an RJMCMC algorithm for mixed models. We analyse two case studies, both large-scale point transect surveys, where the interest lies in establishing the effects of conservation buffers on agricultural fields. For each case study, we compare the results from one integrated approach to those from the extended two-stage approach. We find that these may differ in parameter estimates for covariates that were both in the detection and the count model and in model probabilities when model uncertainty was included in inference. The performance of the random effects based detection function is assessed via simulation and when heterogeneity in the data is present, one of the new estimators yields improved results compared to conventional distance sampling estimators.
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Marques, Tiago André. "Incorporating measurement error and density gradients in distance sampling surveys /." St Andrews, 2007. http://hdl.handle.net/10023/391.
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Marques, Tiago Andre Lamas Oliveira. "Incorporating measurement error and density gradients in distance sampling surveys." Thesis, University of St Andrews, 2007. http://hdl.handle.net/10023/391.
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Distance sampling is one of the most commonly used methods for estimating density and abundance. Conventional methods are based on the distances of detected animals from the center of point transects or the center line of line transects. These distances are used to model a detection function: the probability of detecting an animal, given its distance from the line or point. The probability of detecting an animal in the covered area is given by the mean value of the detection function with respect to the available distances to be detected. Given this probability, a Horvitz-Thompson- like estimator of abundance for the covered area follows, hence using a model-based framework. Inferences for the wider survey region are justified using the survey design. Conventional distance sampling methods are based on a set of assumptions. In this thesis I present results that extend distance sampling on two fronts. Firstly, estimators are derived for situations in which there is measurement error in the distances. These estimators use information about the measurement error in two ways: (1) a biased estimator based on the contaminated distances is multiplied by an appropriate correction factor, which is a function of the errors (PDF approach), and (2) cast into a likelihood framework that allows parameter estimation in the presence of measurement error (likelihood approach). Secondly, methods are developed that relax the conventional assumption that the distribution of animals is independent of distance from the lines or points (usually guaranteed by appropriate survey design). In particular, the new methods deal with the case where animal density gradients are caused by the use of non-random sampler allocation, for example transects placed along linear features such as roads or streams. This is dealt with separately for line and point transects, and at a later stage an approach for combining the two is presented. A considerable number of simulations and example analysis illustrate the performance of the proposed methods.
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Glennie, Richard. "Incorporating animal movement with distance sampling and spatial capture-recapture." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/16467.
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Distance sampling and spatial capture-recapture are statistical methods to estimate the number of animals in a wild population based on encounters between these animals and scientific detectors. Both methods estimate the probability an animal is detected during a survey, but do not explicitly model animal movement. The primary challenge is that animal movement in these surveys is unobserved; one must average over all possible paths each animal could have travelled during the survey. In this thesis, a general statistical model, with distance sampling and spatial capture-recapture as special cases, is presented that explicitly incorporates animal movement. An efficient algorithm to integrate over all possible movement paths, based on quadrature and hidden Markov modelling, is given to overcome the computational obstacles. For distance sampling, simulation studies and case studies show that incorporating animal movement can reduce the bias in estimated abundance found in conventional models and expand application of distance sampling to surveys that violate the assumption of no animal movement. For spatial capture-recapture, continuous-time encounter records are used to make detailed inference on where animals spend their time during the survey. In surveys conducted in discrete occasions, maximum likelihood models that allow for mobile activity centres are presented to account for transience, dispersal, and heterogeneous space use. These methods provide an alternative when animal movement causes bias in standard methods and the opportunity to gain richer inference on how animals move, where they spend their time, and how they interact.
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Alexandridis, Roxana Antoanela. "Minimum disparity inference for discrete ranked set sampling data." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1126033164.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xi, 124 p.; also includes graphics. Includes bibliographical references (p. 121-124). Available online via OhioLINK's ETD Center
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Zerbini, Alexandre N. "Improving precision in multiple covariate distance sampling : a case study with whales in Alaska /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/5391.
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Miller, David. "On smooth models for complex domains and distances." Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557819.
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Spline smoothing is a popular technique for creating maps of a spatial phenomenon. Most smoothers use the Euclidean metric to measure the distance between data. This approach is flawed since the distances between points in the domain as experienced by the objects within the domain are rarely Euclidean. For example, the movements of animals and people are subject to both physical and political boundaries (respectively) which must be navigated. Measuring distances between the objects using the incorrect (Euclidean) metric leads to incorrect inference. The first part of this thesis develops a finite area smoother which does not su↵er from this problem when the shape of the area is complex. It begins by rejecting the use of the Schwarz-Christo↵el transform as a method for morphing complex domains due to its squashing of space. From there a method based on preserving within-area distances using multidimensional scaling is developed. High dimensional projections of the data are necessary to avoid a loss of ordering in the points. To smooth reliably in high dimensions Duchon splines are used. The model developed rivals the current best finite area method in prediction error terms and fits easily into larger models. Finally, the utility of projection methods to smooth general distances is explored. The second part of the thesis concerns distance sampling, a widely used set of methods for estimating the abundance of biological populations. The work presented here introduces mixture formulation for the detection function used to model the probability of detection. The use of mixture models leads to flexible but monotonic detection functions, avoiding the unrealistic shapes which conventional methods are prone to. These new models are then applied to several existing, problematic data sets.
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Schold, Linnér Elisabeth. "Image processing on optimal volume sampling lattices : Thinking outside the box." Doctoral thesis, Uppsala universitet, Avdelningen för visuell information och interaktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-265340.
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This thesis summarizes a series of studies of how image quality is affected by the choice of sampling pattern in 3D. Our comparison includes the Cartesian cubic (CC) lattice, the body-centered cubic (BCC) lattice, and the face-centered cubic (FCC) lattice. Our studies of the lattice Brillouin zones of lattices of equal density show that, while the CC lattice is suitable for functions with elongated spectra, the FCC lattice offers the least variation in resolution with respect to direction. The BCC lattice, however, offers the highest global cutoff frequency. The difference in behavior between the BCC and FCC lattices is negligible for a natural spectrum. We also present a study of pre-aliasing errors on anisotropic versions of the CC, BCC, and FCC sampling lattices, revealing that the optimal choice of sampling lattice is highly dependent on lattice orientation and anisotropy. We suggest a new reference function for studies of aliasing errors on alternative sampling lattices. This function has a spherical spectrum, and a frequency content proportional to the distance from the origin, facilitating studies of pre-aliasing in spatial domain. The accuracy of anti-aliased Euclidean distance transform is improved by application of more sofisticated methods for computing the sub-spel precision term. We find that both accuracy and precision are higher on the BCC and FCC lattices than on the CC lattice. We compare the performance of several intensity-weighted distance transforms on MRI data, and find that the derived segmentation result, with respect to relative error in segmented volume, depends neither on the sampling lattice, nor on the sampling density. Lastly, we present LatticeLibrary, a open source C++ library for processing of sampled data, supporting a number of common image processing methods for CC, BCC, and FCC lattices. We also introduce BccFccRaycaster, a tool for visualizing data sampled on CC, BCC, and FCC lattices. We believe that the work summarized in this thesis provide both the motivation and the tools for continuing research on application of the BCC and FCC lattices in image processing and analysis.
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Barrett, Michelle L. "Comparison of estimated white-tailed deer (Odocoileus virginianus) population densities during two different seasons in the Miami University Natural Areas." Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1417016979.
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Smolensky, Nicole Limunga. "Population enumeration and the effects of oil and gas development on dune-dwelling lizards." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2848.
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Lacerda, Wagner Rafael. "Predação de plantas jovens de Euterpe edulis e invasão de lavouras de milho por Sapajus nigritus em remanescentes de floresta atlântica no sul do Brasil." Universidade Estadual do Oeste do Parana, 2013. http://tede.unioeste.br:8080/tede/handle/tede/680.
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Previous issue date: 2013-07-18The almost complete replacement of the native vegetation of the Atlantic Forest by agriculture and livestock generated an altered matrix in which are embedded fragments of different sizes and historical use and degradation. In this study, the population density of Sapajus nigritus was estimated in two forest fragments surrounded by agricultural crops in southern Brazil. We use the method of linear transect between September 2011 and January 2013, covering 344.08 km in area and 216 km in another. We recorded 119 sightings and 35, respectively. In the first area the population density of Sapajus nigritus was 92.15 individuals / km2, and 32.10 individuals / km2 for the second area. While the lowest value is within the limits found for the species throughout its geographical distribution, the value of 92.15 individuals / km2 is among the highest ever recorded. In addition to offering food crops by anthropogenic factors such as low hunting pressure and predation, as well as composition and forest structure may be related to the densities found
A quase completa substituição da vegetação nativa da Floresta Atlântica pela agricultura e pecuária gerou uma matriz alterada onde estão inseridos fragmentos de diferentes tamanhos e históricos de uso e degradação. Neste estudo, a densidade populacional de Sapajus nigritus foi estimada em dois remanescentes florestais cercados por cultivos agrícolas no sul do Brasil. Nós utilizamos o método de transecções lineares entre setembro de 2011 e janeiro de 2013, percorrendo 344,08 km em uma área e 216 km em outra. Foram registrados 119 e 35 avistamentos, respectivamente. Na primeira área a densidade populacional de Sapajus nigritus foi de 92,15 indivíduos/km2, e 32,10 indivíduos/km2 para a segunda área. Enquanto o valor mais baixo está dentro dos limites encontrados para a espécie ao longo de sua distribuição geográfica, o valor de 92,15 indivíduos/km2 está entre os mais elevados já registrados. Além da oferta de alimento de origem antrópica pelos cultivos, fatores como baixa pressão de caça e predação, além da composição e estrutura da floresta podem estar relacionados às densidades encontradas
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Eckervall, Anneli. "Comparison of plot survey and distance sampling as pellet group counts for deer in Sweden." Thesis, University of Skövde, School of Life Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-921.
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Wildlife management deals with problems concerning sustainable harvest, conservation of threatened species and adjustment of wildlife populations to levels acceptable to for instance forestry, agriculture, traffic and conservation interests. A detailed knowledge of the population is then required. It is therefore important to develop reliable and cost-efficient survey methods.
The purpose of this study was to test the distance sampling method where objects are observed while walking along a line, as a way of counting deer pellet groups and to compare the results with ordinary plot surveys.
The inventory speed for distance sampling increases with increasing amount of droppings/km2. The amount of droppings seems to have little or no effect on the inventory speed of the plot survey method. Therefore the plot survey method could be a better alternative than the distance sampling method when the densities of droppings are high and vice versa.
When comparing the two methods estimates of animal densities with data (orally) from game managers based on other surveys and flying observations and estimations in the different areas, both methods showed too low density for red deer in Valinge. This indicates that the supplementary feeding seem to have an effect on the results of red deer density for both methods.
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Pérez, J. M., M. Sarasa, G. Moço, J. E. Granados, J. P. Crampe, E. Serrano, L. Maurino, P. G. Meneguz, A. Afonso, and R. Alpizar-Jara. "The effect of data analysis strategies in density estimation of mountain ungulates using distance sampling." Bachelor's thesis, Italian Journal of Zoology, 2014. http://hdl.handle.net/10174/16907.
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Distance sampling is being extensively used to estimate the abundance of animal populations. Nevertheless, the great variety of ways in which data can be analyzed may limit comparisons due to the lack of standardization of such protocols. In this study, the influence of analytical procedures for distance sampling data on density estimates and their precision was assessed. We have used data from 21 surveys of mountain ungulates in the Iberian Peninsula, France and the Italian Alps. Data from such surveys were analyzed with the program Distance 6.0. Our analyses show that estimated density can be higher for higher levels of data truncation. We also confirm that the estimates tend to be more precise when data are analyzed without binning and without truncating. We found no evidence of size biased sampling as group size and distances were uncorrelated in most of our surveys. Despite distance sampling being a fairly robust methodology, it can be sensitive to some data analysis strategies.
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Azevedo, Francisco Pereira. "Quantas galinholas Bostrychia bocagei existem em São Tomé?: uso do Distance Sampling e do Plot Sampling para estimar a população de uma ave endémica criticamente ameaçada." Master's thesis, Universidade de Évora, 2015. http://hdl.handle.net/10174/16421.
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A galinhola Bostrychia bocageié uma ave endémica do centro e sul da ilha de São Tomé (costa oeste da África central), classificada como Criticamente em Perigo devido a um efetivo populacional presumido entre os 50 e 249 indivíduos adultos. Neste trabalho fazemos as primeiras estimativas populacionais para a espécie, com base na recolha sistemática de dados no terreno. Para tal usamos o density surfacemodelling(DSM) de observações recolhidas em amostragem por distâncias ao longo de 32 km de transectos lineares e a prospeção intensiva de 29 quadrículas de 2 ha. O DSM estimou um número total de 2965 galinholas (1922 a 4578 para um intervalo de confiança de 95%), enquanto a prospeção intensiva estimou 2361 (347 a 4374 para um intervalo de confiança de 95%). Utilizadosem simultâneo pela primeira vez em aves, estes métodos indicam que existe um efetivo populacional de galinhola superior ao presumido anteriormente. No entanto, atendendo à área restrita de ocorrência da espécie e à pressão que existe sobre a mesma e sobre o seu habitat, sugerimos que esta mantenha a sua classificação de ameaça, e que sejam reforçados os esforços para a proteger; How many dwarf olive ibises Bostrychia bocageiare there in São Tomé? Use of Distance Sampling and Plot Sampling to estimate the population of a critically endangered endemic bird
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The dwarf olive ibises Bostrychia bocageiis an endemic bird of the center and south of São Tomé island (west coast of central Africa), classified with critically endangered due to an assumed effective population between 50 and 249 mature individuals. In this paper we do the first population estimates for the species, based on systematic data collection in the field. We used density surface modeling (DSM) of observations collected in sampling distance along 32 km of linear transects and in plot sampling of 29 plots of 2 ha. The DSM estimated total number of 2965 dwarf olive ibis (1922-4578 for a 95% confidence interval), while the plot sampling estimated 2361 (347-4374 for a 95% confidence interval). In this study weapplied simultaneously for the first time in birds these methodsand resultsindicate that population of dwarf olive ibis higher than previously assumed. However, given the restricted area of occurrence of the species and the pressure that exists on it and on its habitat, we suggest that maintains its threat rating, and that efforts to protect are strengthened.
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Otto, Mitchell Lee. "ESTIMATION OF WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) POPULATION DENSITIES IN MIAMI UNIVERSITY’S NATURAL AREAS USING DISTANCE SAMPLING." Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1390821089.
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Robert, Klaus Bauer. "Development of a robust index of abundance for Atlantic bluefin tuna (Thunnus thynnus) through aerial surveys in the Northwestern Mediterranean Sea." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS042/document.
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Le déclin du thon rouge de l'Atlantique nord-est et de Méditerranée (ABFT, Thunnus thynnus) qui faisait suite à une forte surexploitation a été largement médiatisé au cours de la dernière décennie. Pour contrer cette tendance et reconstituer ce stock, d’importantes mesures de gestion ont été mises en place à partir de 2007. En dehors des difficultés liées à leur mise en œuvre et à leur contrôle, la gestion des pêcheries thonières est aussi limitée dans les capacités à suivre précisément les variations d’abondance de ces espèces dont les observations reposent principalement sur les données de pêche. Le manque d’indice d’abondance fiable fait que l’évaluation du thon rouge, comme celle des autres espèces de poissons grands pélagiques, est entachée d’importantes incertitudes. Cependant, les suivis aériens pourraient permettre de fournir un indice d’abondance du thon rouge. Ils sont en effet fréquemment utilisés pour l'évaluation de l'abondance des mammifères marins et aussi par les pêcheurs pour détecter les poissons épipélagiques, comme les thons. Dans ce contexte général, cette thèse a pour objectifs : (i) d'évaluer des facteurs qui affectent potentiellement la détectabilité des thons pendant les suivis aériens, (ii) d’analyser leur comportement horizontal et vertical et les facteurs environnementaux qui l’influencent, et (iii) d’intégrer les connaissances acquises pour développer un indice abondance robuste du thon rouge en Méditerranée Nord Occidentale. Les analyses reposent sur des suivis aériens conduits depuis 2000 dans le golfe du Lion, une zone de nourricerie importante pour le thon rouge. Une modélisation des données basée sur le « distance sampling » montre des effets significatifs des observateurs, de la taille des bancs de thons et de l'état de la mer sur l’estimation d’abondance. Cette étude confirme par ailleurs une augmentation importance des abondances entre 2003 et 2009, probablement en réponse aux mesures de gestion mises en œuvre depuis 2007 (notamment la taille minimale de débarquement de 30 kg). Pour évaluer les effets du comportement sur les estimations d'abondance, une étude a porté sur les trajectoires de thons issues du marquage électronique. Ces analyses montrent une disponibilité des thons rouge ainsi qu’une présence en surface dans la zone et la période (Août-Octobre) des suivis aériens ; résultat confortant la fiabilité de l’indice d’abondance. On note également des changements saisonniers du comportement, avec un approfondissement des thons à partir de mi-Novembre correspondant à la dé-stratification de la colonne d’eau. Le comportement de plongée profonde était particulièrement fréquent pendant les mois de forte productivité biologique (février-Mai), mais des plongées profondes ont également été observées à la fin de l'été en relation avec des fronts thermiques. La variabilité des schémas migratoires sur l’horizontale et du comportement sur la verticale indique une forte composante opportuniste, probablement liée à la disponibilité des ressources alimentaires. Les résultats obtenus durant cette thèse démontrent la faisabilité d’obtenir un indice d’abondance de thon rouge robuste à partir des suivis aériens (donc indépendants des données de pêche) et fournissent un cadre théorique et méthodologique pour une extension de ce type de suivi afin de diminuer les incertitudes autour de l’évaluation de ce stock. Outre le thon rouge, les suivis aériens ont également permis un suivi du rorqual commun (Balaenoptera physalus) et des dauphins rayés (Stenella coeruleoalba). La présence des mammifères marins semble également être liée à la productivité élevée et l'activité méso-échelle de la zone d'étude. Si les dauphins présentent une distribution spatiale en partie corrélée à celle du thon rouge, les rorquals ne présentent pas de forte co-occurrence avec le thon rouge, résultat qui confirmerait une certaine proximité des régimes alimentaires des thons et des dauphinsDeclines in Atlantic bluefin tuna stocks (ABFT, Thunnus thynnus), due to extensive over-fishing, have been widely publicized in recent decades. To counteract this trend, regulatory measures have been introduced by the fisheries managers, aiming at the rebuilding of ABFT stocks. However, apart from difficulties in controlling the implementation of these measures, fisheries management is limited in its capabilities to track their efficiency due to major uncertainties in the stock assessment. Indeed, there is a general need of reliable indicators of ABFT abundance. Aerial surveys may provide a helpful tool for the abundance monitoring of this highly exploited fish species. They are frequently used for the abundance assessment of marine mammals and also by fishermen to detect epipelagic fish, such as tunas. The aim of this thesis was to address these issues and to create a robust fishery-independent abundance index for ABFT through aerial surveys. To achieve this goal, the focus was set on (i) the assessment of factors that potentially affect the detectability of ABFT during the aerial surveys, (ii) the habitat use of ABFT, i.e. their horizontal and vertical behaviour as well as the factors driving it, and (iii) the integration of the knowledge gained through these analyses in the development of a robust index of ABFT abundance. Surveys were conducted from 2000 onwards in the Gulf of Lions, an important nursery ground for ABFT in the Northwestern Mediterranean Sea. Line transect modelling of the sighting data revealed significant effects of detectability changes on abundance estimates, related to the observer teams employed, the size of detected ABFT schools and the sea state during the aerial surveys. Derived estimates of ABFT abundance confirmed a significant increase from 2003 to 2009, likely reflecting the success of recently implemented management measures (e.g. minimum landing size of 30 kg since 2007). To assess behavioural effects on abundance estimates, auxiliary archival tagging experiments, conducted since 2007, focused on the presence and surface availability of ABFT during the aerial surveys, and aimed to identify factors influencing these variables. The data gained from these experiments demonstrated seasonal changes in the migratory behaviour of ABFT, but also a high area and surface presence of ABFT in the study zone during the survey period (August–October), supporting the reliability of the abundance index. Surface presence of ABFT decreased with the breakdown of the thermal stratification of the water column (mid-November), when the fish left the survey zone and moved South. By contrast, deep diving behaviour was particularly frequent during months of high biological productivity (February--May), although deep and unusual long spike dives were also observed during late summer in relation to thermal fronts. However, the variability in the migration patterns indicates a strong opportunistic component in both, the horizontal and vertical behaviour of ABFT, probably related to the availability of food resources. Apart from ABFT, the aerial surveys also allowed an abundance monitoring of fin whales (Balaenoptera physalus) and striped dolphins (Stenella coeruleoalba) as well as an analysis of their co-occurrence with ABFT. In fact, similar to ABFT, the presence of these species appeared to be related to the high productivity and mesoscale activity of the study zone, improving our understanding of their habitat use, essential for the conservation of these much less abundant and endangered species. Regarding the stock assessment of ABFT, the results gained through this thesis prove the feasibility to derive robust fishery independent abundance indicators for ABFT through aerial surveys, providing the theoretical and methodological background for an extension of these efforts for a more sustainable management of the stocks of this species
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Jalca, Angie, Marco Lopez, Fernando Sotelo, and Carlos Raymundo. "Adoption of snowball sampling technique with distance boundaries to assess the productivity issue faced by micro and small cocoa producers in Cusco." Springer Verlag, 2020. http://hdl.handle.net/10757/656127.
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The food supply chain has gained impulse over the past few years induced by the rising global demand for food; therefore, much emphasis is placed upon examining this class of supply chains. It also faces constant production, storage, and distribution challenges, wherein the key link for proper operation is the farmer, who engages in the agricultural sector, heavily impacted by low crop productivity, which interfer with economic development at a national level. Consequently, it is important to assess those farmers who belong to micro and small enterprises in the agricultural sector. Due to the characteristics of the population, a nonprobability sampling technique was used to assess micro and small cocoa producers in La Convención Province, Cusco, Peru. To such end, a snowball sampling model with distance boundaries was adopted because the population is unknown and hard to reach.
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Falcetto, Andrea. "Greater Galagos near Mt. Kasigau, Kenya: Population Density Estimates." TopSCHOLAR®, 2012. http://digitalcommons.wku.edu/theses/1187.
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This study examined population density and habitat use of a species of greater galago, genus Otolemur, around Mt. Kasigau, Kenya. Mt. Kasigau has a unique regional microclimate, a cloud forest, which provides many different flora and fauna a home. To examine population density, two different methods were used. The first method was using line transects and analyzing results using Distance 6.0. These surveys were conducted during both dry and wet season and results were compared after the study. The second method was to trap individuals and use mark-recapture to determine population density. When caught in a trap, individuals were also weighed and measurements were taken. Accurate weight was taken for 17 individuals; ear height, tail length, and hind foot length were recorded for 21 individuals. Mark-recapture data were analyzed using Krebs/WIN 3.0. Population density estimates using both methods were compared and provided similar results; Distance 6.0 estimated 0.62 individuals per hectare and Krebs/WIN 3.0 estimated 0.51 individuals per hectare. Morphological measurements were not consistent with published data of known species of Otolemur garnettii, which is the most common greater galago in East Africa. It is possible the Mt. Kasigau population is reproductively isolated and DNA analysis should be conducted in the future. Habitat usage of greater and lesser galagos and diurnal primates was examined to determine which tree species are commonly used by these individuals.
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Anderson, Charles Wayne. "ECOLOGY AND MANAGEMENT OF WHITE-TAILED DEER IN AN AGRICULTURAL LANDSCAPE: ANALYSES OF HUNTER EFFICIENCY, SURVEY METHODS, AND ECOLOGY." OpenSIUC, 2010. https://opensiuc.lib.siu.edu/dissertations/178.
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Current research is necessary to focus management of white-tailed deer (Odocoileus virginianus) in the agricultural Midwest, especially given the novel presence of chronic wasting disease in the region. My objectives were to: 1) examine the potential effects of weather and row-crop harvest on daily harvest of white-tailed deer by archery, and individual hunter variables (e.g., age, weapon preference, preference of hunting method) on individual hunter efficiency and success in 2 regions of Illinois (i.e., east-central and southern Illinois); 2) estimate white-tailed deer densities using direct (i.e., spotlighting deer from road transects) and indirect (i.e., counting pellet groups on randomly-placed transects) techniques across 3 study areas in the midwestern U.S.; 3) quantify sex, age, and season-specific survival and dispersal rates of white-tailed deer in east-central Illinois; and 4) assess habitat selection of white-tailed deer during the summer months in east-central Illinois. Knowledge of factors affecting hunter efficiency and success is vital given current trends in hunter attitudes and behaviors that are leading to a reduction in the efficacy of white-tailed deer hunting as a population management tool nationwide. Numerous techniques of density estimation for white-tailed deer have been developed, including aerial surveys, mark-recapture or resight methods, pellet counts, and thermal infrared imaging surveys. Distance sampling has shown great potential for estimating white-tailed deer density at a reduced cost relative to traditional survey techniques and may be useful within the agriculturally-dominated Midwest. Survival and dispersal rates are pertinent model parameters when examining chronic wasting disease (CWD) geographic spread. Structural changes in agricultural landscapes are frequent (i.e., temporally) and ecologically abrupt (i.e., spatially) due to crop harvest and rotation and human development. Providing sex-specific data on site selection would benefit agencies and private land owners by allowing compartmental focus for selective management strategies for either male or female white-tailed deer. Following the 2006 hunting season, I queried white-tailed deer hunters regarding factors potentially affecting hunter efficiency and success in east-central and southern Illinois using a mail-in survey (n = 2,000). I also examined the influence of weather and row-crop harvest progress on daily harvest of white-tailed deer by archery hunting. Hunter efficiency ( ¡À SE= 0.12 ¡À 0.01 deer/day) and hunter success (range = 1.25-1.39 deer/hunter) were similar between study areas. No relationship (r2 <0.01) was detected between respondent age and hunter efficiency, but had a weak influence (r2 = 0.006) on hunter success. Respondents that preferred shotguns, used 1 weapon, and those that preferred still hunting had 62%, 58%, and 52%, respectively, greater (P ¡Ü 0.001) mean hunter efficiency than those in the lowest group within their particular categories. There was no apparent difference (P ¡Ý 0.087) in hunter efficiency across categories of area familiarity, number of hunting methods used, and scouting hours, or categories related to access and use of reconnaissance tools. Respondents that had ¡Ý11 years of area familiarity, preferred archery hunting, used ¡Ý 3 weapons, used ¡Ý3 hunting methods, scouted ¡Ý30 hours, and preferred tree stands had 51%, 45%, 62%, 35%, 61% and 41%, respectively, greater (P ¡Ü 0.001) mean hunter success than those in the lowest group within their particular categories. Access and use of GIS did not appear to affect (P = 0.376) hunter success. Respondents that had access and used topographic maps, aerial or satellite photographs, or GPS had 35%, 34%, and 29% greater (P ¡Ü 0.049), respectively, hunter success than those in the lowest group within their particular categories. Crop harvest progress did not (P = 0.780) appear to affect daily harvest of white-tailed deer by archery hunting. Three models of weather impacts on daily harvest of white-tailed deer by archery hunting had AICc <2. The most parsimonious models¡¯ covariates were MaxWSP, MSLP, and WDSP1, with MaxWSP (¦Â = -0.005) having a negative influence and MSLP (¦Â = 0.00007) and WDSP1 (¦Â = 0.006) having a positive influence on daily harvest of white-tailed deer by archery. I compared direct- and indirect distance sampling techniques for estimating white-tailed deer densities on study areas in east-central Illinois (ECI), southern Illinois (SI, 2007 only), and northern lower peninsula of Michigan (MI) during winter 2007-08. Density estimates obtained via indirect distance sampling for MI, ECI, and SI were 6.1-12.7, 11.2-15.8, and 15.4 deer/km2, respectively. Density estimates obtained via direct distance sampling for MI, ECI, and SI were 18.3-25.2, 14.4-18.1, and 19.0 deer/km2, respectively. Upon examining confidence interval (CI) overlap between direct- and indirect distance sampling techniques by year and study area, only the MI study had non-overlapping CI values. An examination of sites used by deer in summer and quantification of their survival and dispersal rates were conducted in east-central Illinois. From December 2005 to September 2009, I monitored 105 white-tailed deer for 35,478 radiodays for survival and dispersal analysis. I used Program MARK to estimate rates of annual survival, seasonal survival, and dispersal for fawns, yearlings, and adults. I measured habitat variables at sites used by white-tailed deer in summer and random locations in east-central Illinois, examining potential differences in site selection by sex and at multiple scales. Male and female full-season (winter/spring [16 Dec¨C14 May], summer [15 May-30 Sep], fall/winter [1 Oct¨C15 Dec]) survival rate ranged from 0.56 to 0.95 and 0.84 to 0.95, respectively. Male survival was lower than that of females during the fall/winter season for a model not accounting for overdispersion. Averaging across parsimonious models, the dispersal rate for yearling and fawn males and yearling and fawn females were 0.44 ¡À 0.07 and 0.41 ¡À 0.07, respectively. Adult male dispersal rate was 0.46 ¡À 0.15 and no adult females dispersed. Slight differences were observed in habitat variables at sites used by male and female white-tailed deer, but hypotheses of sexual segregation between the sexes were not supported. Males were never observed in developed landcover. Sex differences in the use of developed landcover approached significance with females using sites with that landcover 131% more than males; they also used sites with 87% higher patch density of wetland landcover than males. Based on the best-fit AIC model, overall (i.e., both males and females) site selection of white-tailed deer was influenced by patch density of agriculture landcover, percentage of fallow field landcover, disjunct core area of the landscape, upper visual obstruction, and percentage of shrubs. Increases in upper visual obstruction and percent of shrub increased the likelihood of a site being selected. Decreases in patch density of agriculture landcover, percentage of fallow field landcover, and disjunct core area of the landscape increased the likelihood of a site being selected. This study provides updated information regarding white-tailed deer demographics, habitat use, survey methods, and hunter behavior to white-tailed deer managers in the Midwest. The data produced from mail-in surveys may provide knowledge of influences on hunter efficiency and success that may be used to manipulate deer harvest under a declining number of hunters in the U.S. Consistent estimates of density between indirect- and direct distance sampling shows utility for use of direct distance sampling within agriculturally-dominated regions of the Midwest. Fine-scale management by private landowners may benefit from my data by demonstrating a preference for a particular landscape signature by deer during the summer.
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Urbanek, Rachael Elizabeth. "ECOLOGICAL AND SOCIETAL IMPACTS OF SUBURBAN WHITE-TAILED DEER: A CASE STUDY IN THE CHICAGO METROPOLITAN AREA." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/dissertations/509.
Full textAbstract:
Many natural resource agencies are managing white-tailed deer (Odocoileus virginianus) populations in suburban areas and require information about deer populations, deer impacts on vegetation, and human preferences toward deer and deer management to support decision making. My study based in the Chicago Metropolitan Area during 2007-2011, utilized a multi-faceted approach to investigate common obstacles in suburban deer management. In my findings, I discuss the need for managers to examine suburban deer populations and management issues at a broader scale (i.e., countywide versus single community) and the promotion of proactive deer management in lieu of the conventional paradigm of beginning management only when deer populations have become overabundant. Discussion topics include practicality and costs of deer density estimation and herbivory monitoring techniques over multiple plant communities and numerous study sites. In addition, I illustrate how a comprehensive human dimensions survey can identify determinants that contribute to the public's perceptions of deer density and assess the acceptability, conflict, and beliefs regarding deer management methods. Lastly, I describe the relationship between landscape characteristics and deer density; this information can be utilized to determine suburban lands that may be prone to high deer densities and inform land management practices. My work provides suburban natural resource managers with techniques to identify management practices supported by their public constituents and information useful for managing deer populations.
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Ozdirek, Lutfiye. "Estimation Of Demography And Seasonal Habitat Use Patterns Of Anatolian Mouflon (ovis Gmelinii Anatolica) In Konya Bozdag Protection Area Using Distance Sampling." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611189/index.pdf.
Full textAbstract:
The Anatolian mouflon (Ovis gmelinii anatolica) is an endemic ungulate subspecies and of IUCN Vulnerable status that inhabits Konya-Bozdag region located in Central
Anatolia.
In this thesis, the demography and habitat use of the only natural population of Anatolian mouflon at Konya-Bozdag Provice is studied. Throughout the study, distance sampling techniques, specifically line transect sampling, are used to
estimate density, size and growth rate of this population. Sex, age and count data are used to estimate relevant parameters. Changes in population structure and seasonal
area use are monitored for two years.
Data is collected during repeated random line transects from May 2007 to July 2009. Line transect method is preferred since it requires less effort and is less expensive when compared to the complicated techniques that need animal marking or radio tagging.
In total, 78 transect lines were surveyed during the time which covers 3 lambing periods. In spite of the paratuberculosis epidemics in the fenced area which has
affected the population adversely in the previous years, a rather stable population trend is observed.
The post-breeding population size in 2007, 2008 and 2009 were estimated to be 883+-241, 939+-136, 972+-243 (average+-satndard error) and densities as 27.227, and 28.186 individuals per sq km, respectively.
Growth rate of population is found using the ratio of the population size estimates of consecutive years from 2007 to 2009, average 1.0495+-0.0203.
Habitat use patterns of the Anatolian mouflon throughout the study period are investigated according to seasons and sex groups. There is sexual segregation in the Anatolian mouflon population in Konya Bozdag Province, with the females using the western part and males using the eastern part of Bagderesi. Seasonal patterns affect on the area use of animals, group formation and compositions and the relationship between them are searched throughout the study. The movements of the individuals and groups followed seasonal patterns as centers of activities changed according to seasons.
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Örn, Henrik. "Accuracy and precision of bedrock sur-face prediction using geophysics and geostatistics." Thesis, KTH, Mark- och vattenteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171859.
Full textAbstract:
In underground construction and foundation engineering uncertainties associated with subsurface properties are inevitable to deal with. Site investigations are expensive to perform, but a limited understanding of the subsurface may result in major problems; which often lead to an unexpected increase in the overall cost of the construction project. This study aims to optimize the pre-investigation program to get as much correct information out from a limited input of resources, thus making it as cost effective as possible. To optimize site investigation using soil-rock sounding three different sampling techniques, a varying number of sample points and two different interpolation methods (Inverse distance weighting and point Kriging) were tested on four modeled reference surfaces. The accuracy of rock surface predictions was evaluated using a 3D gridding and modeling computer software (Surfer 8.02®). Samples with continuously distributed data, resembling profile lines from geophysical surveys were used to evaluate how this could improve the accuracy of the prediction compared to adding additional sampling points. The study explains the correlation between the number of sampling points and the accuracy of the prediction obtained using different interpolators. Most importantly it shows how continuous data significantly improves the accuracy of the rock surface predictions and therefore concludes that geophysical measurement should be used combined with traditional soil rock sounding to optimize the pre-investigation program.
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Ayhan, Dilber. "Multi-class Classification Methods Utilizing Mahalanobis Taguchi System And A Re-sampling Approach For Imbalanced Data Sets." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610521/index.pdf.
Full textAbstract:
Classification approaches are used in many areas in order to identify or estimate classes,
which different observations belong to. The classification approach, Mahalanobis Taguchi
System (MTS) is analyzed and further improved for multi-class classification problems under
the scope of this thesis study. MTS tries to explore significant variables and classify a new
observation based on its Mahalanobis distance (MD). In this study, first, sample size
problems, which are encountered mostly in small data sets, and multicollinearity problems,
which constitute some limitations of MTS, are analyzed and a re-sampling approach is
explored as a solution. Our re-sampling approach, which only works for data sets with two
classes, is a combination of over-sampling and under-sampling. Over-sampling is based on
SMOTE, which generates the synthetic observations between the nearest neighbors of
observations in the minority class. In addition, MTS models are used to test the performance
of several re-sampling parameters, for which the most appropriate values are sought specific
to each case. In the second part, multi-class classification methods with MTS are developed.
An algorithm, namely Feature Weighted Multi-class MTS-I (FWMMTS-I), is inspired by the
descent feature weighted MD. It relaxes adding up of the MDs for variables equally. This
provides representations of noisy variables with weights close to zero so that they do not
mask the other variables. As a second multi-class classification algorithm, the original MTS
method is extended to multi-class problems, which is called Multi-class MTS (MMTS). In
addition, a comparable approach to that of Su and Hsiao (2009), which also considers weights
of variables, is studied with a modification in MD calculation. It is named as Feature
Weighted Multi-class MTS-II (FWMMTS-II). The methods are compared on eight different
multi-class data sets using a 5-fold stratified cross validation approach. Results show that
FWMMTS-I is as accurate as MMTS, and they are better than FWMMTS-II. Interestingly,
the Mahalanobis Distance Classifier (MDC) using all the variables directly in the
classification model has performed equally well on the studied data sets.
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Macedo, Ana Luísa Vasques de Carvalho e. "Monitorização das populações de ungulados da Tapada Nacional de Mafra." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15553.
Full textAbstract:
Mestrado em Ecologia AplicadaDurante as últimas décadas tem-se verificado um declínio dramático da biodiversidade mundial, sobretudo devido a alterações climáticas e à pressão antropogénica; como tal a implementação e mecanismos de gestão com vista a garantir a sobrevivência de espécies é cada vez mais importante. Apesar de em Portugal nas últimas décadas as populações de alguns ungulados selvagens, como o veado e o javali terem aumentado torna-se necessário um acompanhamento contínuo das suas populações. O presente estudo foi desenvolvido na Tapada Nacional de Mafra com o intuito de colmatar a necessidade apresentada por esta entidade em implementar um método científico viável e uniforme ao longo dos anos para a monitorização dos ungulados aí presentes: Cervus elaphus, Dama dama e Sus scrofa. Esse trabalho teve como principais objetivos a estimativa de densidades das populações de veado, gamo e javali, da Tapada Nacional de Mafra; a estimativa de alguns parâmetros demográficos (e.g. estrutura populacional, rácio sexual, produtividade) e ainda a análise dos padrões de uso do habitat. Assim, entre novembro de 2013 e setembro de 2015 foi realizada a monitorização das populações de ungulados mencionadas anteriormente, com recurso a metodologias de observação direta; foram realizados percursos pedestres lineares com o uso da técnica complementar de amostragem de distâncias (Distance Sampling) para as populações de cervídeos, e métodos indiretos – observação de indícios de presença para o caso das populações de javali (FBII). Como resultado do trabalho efetuado, numa área aproximada de 833 hectares, foi estimada, numa primeira amostragem, a existência de: 45 veados (intervalo de confiança 95%: 23 -87 veados por km2), com um rácio sexual de 2,04:1; e de 141 gamos (intervalo de confiança 95%: 103 - 194 gamos por km2), com um rácio sexual de 1,14 machos por fêmea. Numa segunda amostragem a existência de 48 veados (intervalo de confiança 95%: 34 -69 veados por km2), com um rácio sexual de 1,86:1); e 287 gamos (intervalo de confiança 95%: 216 – 381 gamos por km2), com um rácio sexual idêntico ao da amostragem anterior. Relativamente ao uso do habitat, as áreas de sobral carvalhal foram as mais utilizadas no outono, invertendo-se essa tendência no inverno e primavera sendo utilizadas, preferencialmente, as zonas de mato. Os dados recolhidos sobre a população de javali demonstram densidades muito elevadas, superiores a 10,6 – 29,6 javalis/km2. Através da realização deste estudo foi possível verificar que na área considerada existe uma densidade elevada de gamos que afeta a população de veados, uma vez que competem não só pelo espaço, mas principalmente pelo alimento. Como tal, devem ser tomadas medidas no sentido de proteger esta última, tanto através do controlo da população de gamos como através da implementação de medidas que favoreçam esta espécie. No que concerne à população de javali, verificou-se que esta população está muito acima do expectável.
Over recent decades world biodiversity observed a significant decline, mainly due to climatic changes and anthropogenic pressure; hence implementation of management mechanisms to ensure the survival of species is increasingly important. Though in Portugal wild ungulates populations, like red deer and wild boar, has increased in the last decades, continuous monitoring is needed. This study was developed at Tapada Nacional de Mafra (TNM) in order to address the needs to implement a viable and uniform scientific monitoring of its wild ungulates: Cervus elaphus, Dama dama and Sus scrofa. The main objectives were to estimate densities of red deer, fallow deer and wild boar, to estimate demographic parameters (e. g. population structure, sex ratio and productivity) and to perform an analysis on habitat “usage” patterns. Thus, from November 2013 to September 2015, the monitoring of the wild ungulates populations aforementioned was carried out, using direct and indirect observation methodologies. For cervids, linear transects was performed and complemented by a distance sampling approach. For wild boar, the observation of presence evidences was made (FBII). In the 833 ha of TNM, for the period between November 2013 and June 2014, the results reveals the existence of 45 red deers (95% IC, 23 – 87) with a sex ratio of 2,04:1 and 141 fallow deers (95% IC, 103 - 194) with a sex ratio of 1,14:1. From September 2014 to September 2015, the results show the existence of 48 red deers (95% IC, 34 – 69) with a sex ratio of 1,86:1 and 287 fallow deers (95% IC, 216-381) with a sex ratio of 1,14:1. In the habitat use, oak forests were the most used in fall, in contrast to winter and spring, with shrublands being preferred. Data from wild boar shows very high densities, above 10,6 and 29,6 wild boars/km2. This study revealed a high density of fallow deer that may be affecting red deer population, shown by the great competition for space and food. . Therefore, management actions should be taken to protect red deer, like fallow deer population control. In the case of wild boar, its densities are very high.
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Flesch, Aaron D., Sanchez Carlos Gonzalez, and Amarillas Javier Valenzuela. "Abundance and habitat relationships of breeding birds in the Sky Islands and adjacent Sierra Madre Occidental of northwest Mexico." WILEY-BLACKWELL, 2016. http://hdl.handle.net/10150/621225.
Full textAbstract:
The Sierra Madre Occidental and neighboring Madrean Sky Islands span a large and biologically diverse region of northwest Mexico and portions of the southwestern United States. Little is known about the abundance and habitat use of breeding birds in this region of Mexico, but such information is important for guiding conservation and management. We assessed densities and habitat relationships of breeding birds across Sky Island mountain ranges in Mexico and adjacent portions of the Sierra Madre from 2009 to 2012. We estimated densities at multiple spatial scales, assessed variation in densities among all major montane vegetation communities, and identified and estimated the effects of important habitat attributes on local densities. Regional density estimates of 65% of 72 focal species varied significantly among eight montane vegetation communities that ranged from oak savannah and woodland at low elevations to pine and mixed-conifer forest at high elevations. Greater proportions of species occurred at peak densities or were relatively restricted to mixed-conifer forest and montane riparian vegetation likely because of higher levels of structural or floristic diversity in those communities, but those species were typically rare or uncommon in the Sky Islands. Fewer species had peak densities in oak and pine-oak woodland, and species associated with those communities were often more abundant across the region. Habitat models often included the effects of broadleaf deciduous vegetation cover (30% of species), which, together with tree density and fire severity, had positive effects on densities and suggest ways for managers to augment and conserve populations. Such patterns combined with greater threats to high-elevation conifer forest and riparian areas underscore their value for conservation. Significant populations of many breeding bird species, including some that are of concern or were not known to occur regionally or in mountain ranges we surveyed, highlight the importance of conservation efforts in this area of Mexico.
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Opravil, Jan. "Systém pro optické měření." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219684.
Full textAbstract:
This diploma thesis deals with the creation and testing of optical measurement system. There are basic parts of computer vision. Some ways of image preprocessing and templates matching are discussed. Everything is directed to a particular practical task. Selected methods for templates matching are the Correlation Method, the Classical and Hybrid Hausdorff Distance, Radial and Circular Sampling Space. These methods are programmed in C++ and they are compared with function for searching templates from specific library.
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Matthews, Jonathan A. "QUANTIFYING WHITE-TAILED DEER DENSITY AND ITS IMPACTS ON AGRICULTURAL SYSTEMS." UKnowledge, 2019. https://uknowledge.uky.edu/forestry_etds/47.
Full textAbstract:
White-tailed deer (Odocoileus virginianus) commonly consume row crops, with yield losses often attributed to their browsing. Deer density and field morphology may predict yield losses within local areas. We sought to 1) determine the effects of deer browsing on corn and soybean yields and investigate if deer density or field morphology correlated to yield loss in western Kentucky, and 2) compare pellet-based distance sampling to game camera surveys to determine if a distance sampling technique could accurately estimate deer density during the growing season. Overall, deer reduced corn and soybean yields on one-half of surveyed properties. Deer density did not influence yield losses in either crop; however, field morphology correlated with soybean yield losses. Pellet-based distance sampling provided statistically similar estimates as our game camera survey technique; however, at the individual farm level distance sampling estimates proved unreliable. Inaccurate model parameter (i.e., defecation rates) and inability to detect pellet groups in dense vegetation complicated the reliability of distance sampling models. Overall, yield losses from deer occur in western Kentucky and may be a localized event. Finally, game camera surveys should be used over pellet-based distance sampling during the growing season until detection issues and inaccurate model parameters are solved.
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Peterson, Thomas E. "FACTORS AFFECTING DENSITIES OF WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) IN EASTERN DECIDUOUS FOREST: THE ROLES OF AND SURROUNDING LAND USE, FOREST HABITAT EDGE, AND INVASIVE SHRUBS." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1526295117069628.
Full text
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Valente, Ana Margarida dos Santos. "Red and roe deer densities and distribution in Northeastern Portugal." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14929.
Full textAbstract:
Mestrado em Ecologia AplicadaMonitoring ungulates is a major challenge to perform management strategies, either back in the 70’s to enable their conservation that lead to their great recovery, as to manage their actual expansion. Their current wide range distribution and high den-sities across Europe promotes damages in ecosystems that need to be handled based on scientific knowledge. In Portugal ungulate monitoring and ecology is still in an early stage, however efforts have been made to gather valid information on north-eastern ungulate populations. In this work density of red and roe deer were estimated coupling line transects to perform pellet group counts with a distance sampling ap-proach. The density of red deer estimated for Montesinho Natural Park (MNP) was 3.05 ind./100 ha (95% CI: 2.05 – 4.54), splitted in two sub-areas: Serra de Mon-tesinho (SM) with 1.23 ind./100 ha and Lombada National Hunting Area (LNHA) with 5.23 ind./100 ha. Roe deer densities were estimated with recourse to a spatial methodology recently developed, the Density Surface Models (DSMs – with a dis-tance sampling framework), which enables the assessment of the relationships be-tween animal’s density and spatial variables selected according to species ecological requirements. As well roe deer densities were estimated for MNP and Serra da Nogueira (SN) with a global density of 3.01 ind./100 ha (95% CI: 2.34 – 3.87): SM with 3.74 ind./100 ha, LNHA with 1.59 ind./100 ha and SN with 3.62 ind./100ha. Furthermore this approach enables the drawing of an abundance distribution map across the study area, especially useful when communicating results to wildlife man-agers. Roe deer densities showed to increase as distance to roads increased, while surprisingly shown an increase as distance to human populations decreased. As ex-pected, cover areas shown its importance for roe deer, a prey species for Iberian wolf. The spatial analysis confirmed that DSMs represent a good approach to estimate ungulate densities, and should be encouraged in future works. Future studies are mandatory to assess red and roe deer ecological requirements and evaluate trends over the years, in order to stablish management plans to handle the damages caused by these species.
A monitorização de ungulados constitui um passo essencial no desenvolvimento de estratégias de gestão. Desde os anos 70, quando os esforços para a conservação e gestão destas espécies permitiram a sua expansão, até aos dias de hoje, a gestão de habitats e espécies tem tido um papel central na ecologia. A ampla distribuição atual dos ungulados selvagens e as suas elevadas abundâncias na Europa provocam danos nos ecossistemas, que têm que ser geridos com base em conhecimento científico. Em Portugal a monitorização das populações de ungulados, bem como o estudo da sua ecologia encontra-se ainda numa fase inicial, no entanto têm sido desenvolvidos avanços significativos no conhecimento das populações de ungulados no nordeste transmontano. Neste trabalho foram estimadas densidades de veado e corço através do distance sampling aplicado a transectos lineares com contagem de excrementos. A densidade de veado no Parque Natural de Montesinho (PNM) foi de 3.05 ind./100 ha (IC a 95%: 2.05 – 4.54) dividido em duas sub-áreas: Serra de Montesinho (SM) com 1.23 ind./100 ha e Lombada National Hunting Area (LNHA) com 5.23 ind./100 ha. As densidades de corço foram estimadas com recurso a uma metodologia espa-cial desenvolvida recentemente, os Density Surface Models (DSMs – baseados no distance sampling) que permitem relacionar as densidades populacionais com as va-riáveis espaciais escolhidas de acordo com a ecologia da espécie. As densidades de corço foram estimadas para o PNM e para a Serra da Nogueira (SN) apresentando uma densidade global de 3.01 ind./100 ha (IC a 95%: 2.34 – 3.87): SM com 3.74 ind./100 ha, LNHA com 1.59 ind./100 ha e SN com 3.62 ind./100 ha. Adicional-mente este método permite construir um mapa de distribuição de abundâncias ao longo da área de estudo, o que é particularmente útil ao comunicar os resultados aos responsáveis pela gestão das áreas protegidas. Do ponto de vista ecológico, as den-sidades de corço aumentaram à medida que a distância às estradas aumentou, mos-trando, surpreendentemente, uma redução na densidade à medida que a distância às populações humanas aumentou. Tratando-se de uma espécie-presa do lobo-ibérico, as áreas de abrigo revelaram-se importantes para o corço. A análise espacial confir-mou que os DSMs são um método robusto para estimar densidades de ungulados e analisar a sua ecologia. Estudos futuros são essenciais para identificar as necessida-des ecológicas do veado e do corço, bem como para avaliar oscilações nas densida-des ao longo dos anos, para que seja possível estabelecer planos de gestão que per-mitam mitigar os danos causados por estas espécies.
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Costa, Marina. "Abundance and distribution of delphinids in the Red Sea (Egypt)." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/6802.
Full textAbstract:
Knowledge about cetaceans in the Red Sea is limited with only a handful of sporadic or spatially-limited studies carried out to date. Funded by the Italian Cooperation through a Debt-for-Nature Swap programme and carried out in collaboration with the Egyptian NGO HEPCA, this thesis presents the results from the first ever systematic vessel-based surveys conducted in the southern Egyptian Red Sea from 2010 to 2013 using linetransect methodology. The main aims of the thesis were (a) to estimate cetacean abundance, (b) to determine distribution patterns and habitat use of the cetacean species, (c) to investigate movement patterns for species for which individual recognition techniques were suitable and (d) to identify areas of conservation concern for cetaceans with a particular focus on existing protected areas. Eight species were identified, of which five were commonly encountered (Stenella longirostris, S. attenuata, Tursiops truncatus, T. aduncus, and Grampus griseus) and three were rare (Pseudorca crassidens, Sousa plumbea, Balaenoptera edeni). Estimates of abundance using design-based line transect sampling techniques were obtained for five species: S. attenuata 10,268 (CV=0.26); S. longirostris 6,961 (CV=0.26); T. aduncus 659 (CV=0.69); T. truncatus 509 (CV=0.33), and G. griseus 367 (CV=0.37). Habitat modelling revealed that the two Stenella species were widely distributed across the study area. In contrast, T. truncatus was concentrated in waters around Ras Banas peninsula (in particular Satayah offshore reef), and T. aduncus was mainly found along the coast with possibly separate sub-populations in the northern and southern study area. G. griseus was only encountered in the southern part. The information provided in this study will allow the development of a conservation strategy for the protected areas and will serve as baseline information to carry out future survey work in the Red Sea.
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Riou-Durand, Lionel. "Theoretical contributions to Monte Carlo methods, and applications to Statistics." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLG006/document.
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La première partie de cette thèse concerne l'inférence de modèles statistiques non normalisés. Nous étudions deux méthodes d'inférence basées sur de l'échantillonnage aléatoire : Monte-Carlo MLE (Geyer, 1994), et Noise Contrastive Estimation (Gutmann et Hyvarinen, 2010). Cette dernière méthode fut soutenue par une justification numérique d'une meilleure stabilité, mais aucun résultat théorique n'avait encore été prouvé. Nous prouvons que Noise Contrastive Estimation est plus robuste au choix de la distribution d'échantillonnage. Nous évaluons le gain de précision en fonction du budget computationnel. La deuxième partie de cette thèse concerne l'échantillonnage aléatoire approché pour les distributions de grande dimension. La performance de la plupart des méthodes d’échantillonnage se détériore rapidement lorsque la dimension augmente, mais plusieurs méthodes ont prouvé leur efficacité (e.g. Hamiltonian Monte Carlo, Langevin Monte Carlo). Dans la continuité de certains travaux récents (Eberle et al., 2017 ; Cheng et al., 2018), nous étudions certaines discrétisations d’un processus connu sous le nom de kinetic Langevin diffusion. Nous établissons des vitesses de convergence explicites vers la distribution d'échantillonnage, qui ont une dépendance polynomiale en la dimension. Notre travail améliore et étend les résultats de Cheng et al. pour les densités log-concavesThe first part of this thesis concerns the inference of un-normalized statistical models. We study two methods of inference based on sampling, known as Monte-Carlo MLE (Geyer, 1994), and Noise Contrastive Estimation (Gutmann and Hyvarinen, 2010). The latter method was supported by numerical evidence of improved stability, but no theoretical results had yet been proven. We prove that Noise Contrastive Estimation is more robust to the choice of the sampling distribution. We assess the gain of accuracy depending on the computational budget. The second part of this thesis concerns approximate sampling for high dimensional distributions. The performance of most samplers deteriorates fast when the dimension increases, but several methods have proven their effectiveness (e.g. Hamiltonian Monte Carlo, Langevin Monte Carlo). In the continuity of some recent works (Eberle et al., 2017; Cheng et al., 2018), we study some discretizations of the kinetic Langevin diffusion process and establish explicit rates of convergence towards the sampling distribution, that scales polynomially fast when the dimension increases. Our work improves and extends the results established by Cheng et al. for log-concave densities
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Dénes, Francisco Voeroes. "Abundância de aves de rapina no Cerrado e Pantanal do Mato Grosso do Sul e os efeitos da degradação de hábitat: perspectivas com métodos baseados na detectabilidade." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-15012015-152016/.
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A urbanização e a expansão das fronteiras agrícolas na região Neotropical estão entre as principais forças causadoras da degradação ambiental em hábitats abertos naturais. Inferências e estimativas de abundância são críticas para quantificação de dinâmicas populacionais e impactos de mudanças ambientais. Contudo, a detecção imperfeita e outros fenômenos que causam inflação de zeros podem induzir erros de estimativas e dificultar a identificação de padrões ecológicos. Examinamos como a consideração desses fenômenos em dados de contagens de indivíduos não marcados pode informar na escolha do método apropriado para estimativas populacionais. Revisamos métodos estabelecidos (modelos lineares generalizados [GLMs] e amostragem de distância [distance sampling]) e emergentes que usam modelos hierárquicos baseados em misturas (N-mixture; modelo de Royle-Nichols [RN], e N-mixture básico, zero inflacionado, espacialmente explicito, visita única, e multiespécies) para estimar a abundância de populações não marcadas. Como estudo de caso, aplicamos o método N-mixture baseado em visitas únicas para modelar dados de contagens de aves de rapina em estradas e investigar como transformações de habitat no Cerrado e Pantanal do Mato Grosso do Sul afetaram as populações de 12 espécies em uma escala regional (>300.000 km2). Os métodos diferem nos pré-requisitos de desenho amostral, e a sua adequabilidade depender da espécie em questão, da escala e objetivos do estudo, e considerações financeiras e logísticas, que devem ser avaliados para que verbas, tempo e esforço sejam utilizados com eficiência. No estudo de caso, a detecção de todas as espécies foi influenciada pela horário de amostragem, com efeitos congruentes com expectativas baseadas no comportamentos de forregeamento e de voo. A vegetação fechada e carcaças também influenciaram a detecção de algumas espécies. A abundância da maioria das espécies foi negativamente influenciada pela conversão de habitats naturais para antrópicos, particularmente pastagens e plantações de soja e cana-de-açúcar, até mesmo para espécies generalistas consideradas como indicadores ruins da qualidade de hábitats. A proteção dos hábitats naturais remanescentes é essencial para prevenir um declínio ainda maior das populações de aves de rapina na área de estudo, especialmente no domínio do CerradoUrbanization and the expansion of agricultural frontiers are among the main forces driving the degradation of natural habitats in Neotropical open habitats. Inference and estimates of abundance are critical for quantifying population dynamics and the impacts of environmental change. Yet imperfect detection and other phenomena that cause zero inflation can induce estimation error and obscure ecological patterns. We examine how detection error and zero-inflation in count data of unmarked individuals inform the choice of analytical method for estimating population size. We review established (GLMs and distance sampling) and emerging methods that use N-mixture models (Royle-Nichols model, and basic, zero-inflated, temporary emigration, beta-binomial, generalized open-population, spatially explicit, single-visit and multispecies) to estimate abundance of unmarked populations. As a case study, we employed a single visit N-mixture approach to model roadside raptor count data and investigate how land-use transformations in the Cerrado and Pantanal domains in Brazil have affected the populations of 12 species on a regional scale (>300,000 km2). Methods differ in sampling design requirements, and their suitability will depend on the study species, scale and objectives of the study, and financial and logistical considerations, which should be evaluated to use funds, time and effort efficiently. In the case study, detection of all species was influenced by time of day, with effects that follow expectations based on foraging and flying behavior. Closed vegetation on and carcasses found during surveys also influenced detection of some species. Abundance of most species was negatively influenced by conversion of natural Cerrado and Pantanal habitats to anthropogenic uses, particularly pastures, soybean and sugar cane plantations, even for generalist species usually considered poor habitat-quality indicators. Protection of the remaining natural habitats is essential to prevent further decline of raptor populations in the study area, especially in the Cerrado domain
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Morgado, Maria de Fátima Romão. "Selecção de modelos em amostragem por distâncias." Master's thesis, Universidade de Évora, 2008. http://hdl.handle.net/10174/18339.
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A selecção do modelo que se ajuste adequadamente a um conjunto de dados é uma parte fulcral no processo da inferência estatística. O critério mais comum para seleccionar uma função de detectabilidade, que se ajuste a um conjunto de dados de distâncias, baseado na informação K-L, denomina-se critério de informação de Akaike (AIC). Para avaliar a performance da rotina da selecção de modelos implementada no programa DISTANCE, realizaram-se simulações Monte Carlo para gerar dados de duas funções densidade de probabilidade frequentemente usadas. Aplicando esta metodologia, observou-se um enviesamento substancial na selecção do modelo, sendo os estimadores dos parâmetros baseados no modelo seleccionado frequentemente enviesados. Utilizaram-se duas abordagens na estimação dos parâmetros: selecção de modelos tradicional e ponderação de modelos. Para ilustrar a metodologia da selecção de modelos usaram-se dados provenientes de um estudo controlado. ABSTRACT; The selection of a model that adequately fits a data set is an important part in the statistical inference process. The most commonly used criterion to select a detectability function that fits a distance sampling data set, is based on the K-L information, and it is known as the Akaike information criterion (AIC). ln order to evaluate the performance of the model selection routine implemented in software DISTANCE, we carried out Monte Carlo simulations generating data from two frequently used probability density functions. We found substantial model selection biases when using this methodology. We further observed that parameter estimators based on the selected model were often biased. Parameter estimation was conducted under two approaches: traditional model selection and model averaging. We used data from a controlled field experiment to illustrate the model selection methodology.
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Nold, Mariana Saskia Verfasser], Susanne [Akademischer Betreuer] [Rässler, and Georg [Akademischer Betreuer] Heinze. "Behavior of convergence in logistic regression models - Assessing the drop of the Kolmogorov distance between the sampling distribution and the asymptotic distribution of estimators and test statistics in logistic regression analysis / Mariana Saskia Nold. Betreuer: Susanne Rässler ; Georg Heinze." Bamberg : Otto-Friedrich-Universität Bamberg, 2014. http://d-nb.info/1058554395/34.
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Cao, Phuong Thao. "Approximation of OLAP queries on data warehouses." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00905292.
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We study the approximate answers to OLAP queries on data warehouses. We consider the relative answers to OLAP queries on a schema, as distributions with the L1 distance and approximate the answers without storing the entire data warehouse. We first introduce three specific methods: the uniform sampling, the measure-based sampling and the statistical model. We introduce also an edit distance between data warehouses with edit operations adapted for data warehouses. Then, in the OLAP data exchange, we study how to sample each source and combine the samples to approximate any OLAP query. We next consider a streaming context, where a data warehouse is built by streams of different sources. We show a lower bound on the size of the memory necessary to approximate queries. In this case, we approximate OLAP queries with a finite memory. We describe also a method to discover the statistical dependencies, a new notion we introduce. We are looking for them based on the decision tree. We apply the method to two data warehouses. The first one simulates the data of sensors, which provide weather parameters over time and location from different sources. The second one is the collection of RSS from the web sites on Internet.
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Cox, Martin James. "Acoustic and ecological investigations into predator-prey interactions between Antarctic krill (Euphausia superba) and seal and bird predators." Thesis, St Andrews, 2008. http://hdl.handle.net/10023/579.
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Moustafa, Harb Hassan. "Gestion efficace de données et couverture dans les réseaux de capteurs sans fil." Thesis, Besançon, 2016. http://www.theses.fr/2016BESA2020/document.
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Dans cette thèse, nous proposons des techniques de gestion de données pour économiser l’énergie dans les réseaux de capteurs périodiques basés sur l’architecture de clustering. Premièrement, nous proposons d’adapter le taux d’échantillonnage du capteur à la dynamique de la condition surveillée en utilisant le modèle de one-way ANOVA et des tests statistiques (Fisher, Tukey et Bartlett), tout en prenant en compte l’énergie résiduelle du capteur. Le deuxième objectif est d’éliminer les données redondantes générées dans chaque cluster. Au niveau du capteur, chaque capteur cherche la similarité entre les données collectées à chaque période et entre des périodes successives, en utilisant des fonctions de similarité. Au niveau du CH, nous utilisons des fonctions de distance pour permettre CH d’éliminer les ensembles de données redondantes générées par les nœuds voisins. Enfin, nous proposons deux stratégies actif/inactif pour ordonnancer les capteurs dans chaque cluster, après avoir cherché la corrélation spatio-temporelle entre les capteurs. La première stratégie est basée sur le problème de couverture des ensembles tandis que la seconde prend avantages du degré de corrélation et les énergies résiduelles de capteurs pour ordonnancer les nœuds dans chaque cluster. Pour évaluer la performance des techniques proposées, des simulations sur des données de capteurs réelles ont été menées. La performance a été analysée selon la consommation d’énergie, la latence et l’exactitude des données, et la couverture, tout en montrant comment nos techniques peuvent améliorer considérablement les performances des réseaux de capteursIn this thesis, we propose energy-efficient data management techniques dedicated to periodic sensor networks based on clustering architecture. First, we propose to adapt sensor sampling rate to the changing dynamics of the monitored condition using one-way ANOVA model and statistical tests (Fisher, Tukey and Bartlett), while taking into account the residual energy of sensor. The second objective is to eliminate redundant data generated in each cluster. At the sensor level, each sensor searches the similarity between readings collected at each period and among successive periods, based on the sets similarity functions. At the CH level, we use distance functions to allow CH to eliminate redundant data sets generated by neighboring nodes. Finally, we propose two sleep/active strategies for scheduling sensors in each cluster, after searching the spatio-temporal correlation between sensor nodes. The first strategy uses the set covering problem while the second one takes advantages from the correlation degree and the sensors residual energies for scheduling nodes in the cluster. To evaluate the performance of the proposed techniques, simulations on real sensor data have been conducted. We have analyzed their performances according to energy consumption, data latency and accuracy, and area coverage, and we show how our techniques can significantly improve the performance of sensor networks
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Lebrat, Léo. "Projection au sens de Wasserstein 2 sur des espaces structurés de mesures." Thesis, Toulouse, INSA, 2019. http://www.theses.fr/2019ISAT0035.
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Cette thèse s’intéresse à l’approximation pour la métrique de 2-Wasserstein de mesures de probabilité par une mesure structurée. Les mesures structurées étudiées sont des discrétisations consistantes de mesures portées par des courbes continues à vitesse et à accélération bornées. Nous comparons deux types d’approximations pour ces courbes continues : l’approximation constante par morceaux et linéaire par morceaux. Pour chaque méthode, des algorithmes rapides et fonctionnant pour une discrétisation fine ont été développés. Le problème d’approximation se divise en deux étapes avec leurs propres défis théoriques et algorithmiques : le calcul de la distance de Wasserstein 2 et son optimisation par rapport aux paramètres de structure. Ce travail est initialement motivé par la génération de trajectoires d’IRM en acquisition compressée, toutefois nous donnons de nouvelles applications potentielles pour ces méthodesThis thesis focuses on the approximation for the 2-Wasserstein metric of probability measures by structured measures. The set of structured measures under consideration is made of consistent discretizations of measures carried by a smooth curve with a bounded speed and acceleration. We compare two different types of approximations of the curve: piecewise constant and piecewise linear. For each of these methods, we develop fast and scalable algorithms to compute the 2-Wasserstein distance between a given measure and the structured measure. The optimization procedure reveals new theoretical and numerical challenges, it consists of two steps: first the computation of the 2-Wasserstein distance, second the optimization of the parameters of structure. This work is initially motivated by the design of trajectories in MRI acquisition, however we provide new applications of these methods
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Bringmann, Karl Verfasser], and Kurt [Akademischer Betreuer] [Mehlhorn. "Sampling from discrete distributions and computing Fréchet distances / Karl Bringmann. Betreuer: Kurt Mehlhorn." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2015. http://d-nb.info/1065669763/34.
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Hulme, Mark F. "The density and diversity of birds on farmland in West Africa." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/424.
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Amorim, Fernanda Alves de. "Densidade populacional e seleção de habitat pelo mutum-do-sudeste, Crax blumenbachii, na Reserva Natural Vale, Linhares, Espírito Santo." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-06032015-152602/.
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O mutum-do-sudeste é endêmico da Mata Atlântica de baixada e foi extinto de quase toda sua distribuição original devido ao desmatamento e a caça. Hoje é listado como ameaçado e a falta de conhecimento sobre sua ecologia dificulta o manejo da espécie. Este trabalho teve como objetivo estimar a densidade populacional do mutum-do-sudeste na Reserva Natural Vale (RNV) através do método de transecção linear. Os registros feitos durante as amostragens também foram utilizados para verificar a existência de seleção de habitat por meio da comparação de áreas onde a espécie foi registrada com áreas aleatórias onde nunca obtivemos registros. A estimativa populacional obtida mostrou a existência de uma razão sexual desviada em relação aos machos que parecia estar relacionada a diferenças de comportamento entre os sexos, devido aos poucos registros de fêmeas. Para confirmar nossos resultados, utilizamos dados de armadilhas fotográficas que foram utilizadas para estudar onças na reserva. Estes dados confirmaram um número maior de machos na população, porém menos acentuado do que o encontrado nos transectos, comprovando que o comportamento discreto das fêmeas afetou nossa amostragem. Combinando os dados dos dois métodos obtivemos a estimativa de 1.6 indivíduos/Km2. As análises de seleção de habitat confirmaram a relação positiva do mutum-do-sudeste com matas altas e sub-bosque denso, e mostraram que o mutum-do-sudeste tem menor probabilidade de ocorrência em áreas com abundância de árvores mortas em pé, troncos em decomposição e serapilheira profunda. Tal influencia negativa provavelmente se deve a aspectos relacionados à sua dieta e a baixa tolerância a habitats que sofreram distúrbio. As informações contidas neste trabalho servirão de base para guiar o manejo de populações selvagens e futuros projetos de reintrodução. Além disso, estudos futuros devem considerar as diferenças de comportamento entre os sexos para que os dados sejam analisados de forma correta, evitando assim, erros que podem afetar diretamente o manejo da espécie.The Red-billed Curassow was formerly found throughout the lowland Brazilian Atlantic Forest but is now extinct across most of its former range due to habitat loss and hunting pressure. Althought classified as globally threatened, there is still a chronic lack of information on Red-billed Curassows\' biology hindering efforts to mitigate the impacts of anthropogenic threats. We investigated population size and habitat relations of Red-billed Curassows at Vale Nature Reserve (VNR) using line transect and presence/absence method. Line transects results showed a male skewed sex ratio that appeared to be related to different behavivour between sexes as we recorded a low number of females. To evaluate any bias in the estimates of sex ratio from line transect we used data from a camera trap survey designed to monitor jaguars at the reserve. Camera trap data confirmed the existence of a male skewed sex ratio in the population but less pronounced than the one found on line transects, showing that different behavior between sexes affected our estimates. Using the sex ratio calculated with camera trap data we were able to estimate 1.6 individuals/Km2. The habitat assessment showed a positive relation of the Red-billed Curassow with taller forests and dense undergrowth. The abundance of snags, decaying log and leaf litter depth, negatively influenced Red-billed Curassows\' occurrence and appear to be related to its mainly frugivorous diet and low tolerance to habitat disturbances. Our study provides critical baseline information about an important population of Red-billed Curassows and will serve to guide management strategies and future reintroduction attempts. It also reveals that survey efforts must take into account sexual differences in behaviour to increase the reliability of modeled estimates. Failing to take these considerations into account may lead to misleading inferences from data, and impact management strategies for a seriously threatened species.
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Yngman, Gunnar. "Individualization of fixed-dose combination regimens : Methodology and application to pediatric tuberculosis." Thesis, Uppsala universitet, Institutionen för farmaceutisk biovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-242059.
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Introduction: No Fixed-Dose Combination (FDC) formulations currently exist for pediatric tuberculosis (TB) treatment. Earlier work implemented, in the software NONMEM, a rational method for optimizing design and individualization of pediatric anti-TB FDC formulations based on patient body weight, but issues with parameter estimation, dosage strata heterogeneity and representative pharmacokinetics remained. Aim: To further develop the rational model-based methodology aiding the selection of appropriate FDC formulation designs and dosage regimens, in pediatric TB treatment. Materials and Methods: Optimization of the method with respect to the estimation of body weight breakpoints was sought. Heterogeneity of dosage groups with respect to treatment efficiency was sought to be improved. Recently published pediatric pharmacokinetic parameters were implemented and the model translated to MATLAB, where also the performance was evaluated by stochastic estimation and graphical visualization. Results: A logistic function was found better suited as an approximation of breakpoints. None of the estimation methods implemented in NONMEM were more suitable than the originally used FO method. Homogenization of dosage group treatment efficiency could not be solved. MATLAB translation was successful but required stochastic estimations and highlighted high densities of local minima. Representative pharmacokinetics were successfully implemented. Conclusions: NONMEM was found suboptimal for the task due to problems with discontinuities and heterogeneity, but a stepwise method with representative pharmacokinetics were successfully implemented. MATLAB showed more promise in the search for a method also addressing the heterogeneity issue.
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Farah, Saïd. "Etude et mise en œuvre d’un banc intégré et étalonné 4 canaux pour la caractérisation temporelle de dispositifs non-linéaires hyperfréquences." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0010/document.
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Ce travail de cette thèse propose une conception et une réalisation d’un banc intégré de caractérisation temporelle des dispositifs RF non-linéaires conçu avec des récepteurs de type THA. Ce banc est une version miniaturisée, moins onéreuse et à performances comparables d’un banc similaire « éclaté » et développé au sein d’XLIM. Le banc intégré développé dans ce travail est entièrement étalonné. Il est versatile vis-à-vis des techniques de sous échantillonnage mis en œuvre pour mesurer des signaux RF sur des temps d’acquisition très différents (<50 µs ou < quelques ms). La technique CIS est utilisée pour l’acquisition périodiques de signaux RF périodiques de durée courtes. La technique DQD est utilisée pour l’acquisition périodiques ou apériodique de signaux RF périodiques ou apériodiques. Cet outil a été utilisé pour extraire, à partir des formes d’ondes temporelles mesurées à leurs accès, plusieurs paramètres caractéristiques (AM/AM- AM/PM, EVM) d’amplificateurs GaN de gamme 10 à 50 W soumis à des excitations simples ou à des signaux modulés. Ce manuscrit décrit aussi la mise en œuvre le développement, parallèlement au travail précédent, d’une plateforme de laboratoire de travaux pratiques à distance pour le projet européen TEMPUS EOLESThis work proposes the design and the realization of a 4-channel integrated and calibrated time-domain characterization system for the characterization of non-linear microwave devices. This integrated measurement system uses THA based receivers. This is a miniaturized, less expensive and comparable version of a similar laboratory available tool developed within XLIM. The integrated instrument developed in this work is fully calibrated. It is versatile with respect to sub-sampling techniques used to measure RF signals over very different acquisition times (<50 µs or < few ms). The CIS technique is used for the periodic acquisition of periodic short duration RF signals. The DQD technique is used for the periodic or aperiodic acquisition of periodic or aperiodic RF signals. This tool was used to extract, from the measured time-domain waveforms at their ports, several characteristic parameters (AM/AM-AM/PM, EVM) of GaN amplifiers operating in the 10 to 50 W range and excited with simple or modulated signals. This manuscript also describes the implementation, and the development, performed along with the previous work, of a laboratory platform for remote practical works in the context of the European project TEMPUS EOLES
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Vestin, Albin, and Gustav Strandberg. "Evaluation of Target Tracking Using Multiple Sensors and Non-Causal Algorithms." Thesis, Linköpings universitet, Reglerteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-160020.
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Today, the main research field for the automotive industry is to find solutions for active safety. In order to perceive the surrounding environment, tracking nearby traffic objects plays an important role. Validation of the tracking performance is often done in staged traffic scenarios, where additional sensors, mounted on the vehicles, are used to obtain their true positions and velocities. The difficulty of evaluating the tracking performance complicates its development. An alternative approach studied in this thesis, is to record sequences and use non-causal algorithms, such as smoothing, instead of filtering to estimate the true target states. With this method, validation data for online, causal, target tracking algorithms can be obtained for all traffic scenarios without the need of extra sensors. We investigate how non-causal algorithms affects the target tracking performance using multiple sensors and dynamic models of different complexity. This is done to evaluate real-time methods against estimates obtained from non-causal filtering. Two different measurement units, a monocular camera and a LIDAR sensor, and two dynamic models are evaluated and compared using both causal and non-causal methods. The system is tested in two single object scenarios where ground truth is available and in three multi object scenarios without ground truth. Results from the two single object scenarios shows that tracking using only a monocular camera performs poorly since it is unable to measure the distance to objects. Here, a complementary LIDAR sensor improves the tracking performance significantly. The dynamic models are shown to have a small impact on the tracking performance, while the non-causal application gives a distinct improvement when tracking objects at large distances. Since the sequence can be reversed, the non-causal estimates are propagated from more certain states when the target is closer to the ego vehicle. For multiple object tracking, we find that correct associations between measurements and tracks are crucial for improving the tracking performance with non-causal algorithms.
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Chen-Chi, Sun, and 孫政啟. "The Effect of Sampling Frequency on Digital Distance Protection." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/14668692677537596356.
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碩士國立臺灣科技大學
電機工程研究所
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To obtain a safety and reliability protection system, digital protective relay requires accurate filtering and relaying algorithms. As we know, the frequency of a power system will drift when disturbances occur. Therefore, if the sampling frequency keeps constant, it may result in unacceptable consequence. In this thesis, an adaptive sampling algorithm is proposed. The algorithm utilizes phase locked function to adjust the sampling frequency according to the system frequency. First, three filter algorithms are simulated, and their performances are analyzed. The results reveal full cycle recursive Fourier algorithm and improved half cycle recursive Fourier algorithm are appropriate approaches for filtering. Three available fault locator algorithms are slected for the simulation study. Among them, the first method is provided as an appropriate algorithm. Finally, the effect of adaptive sampling frequency algorithm on microprocessor-based digital distance protections are evaluated. The results presented in this thesis provide better accuracy which confirms the merit of adaptive sampling frequency algorithm.
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Correia, Iúri Josiane Frizado. "Estimating caribou abundance in West Greenland using distance sampling methods." Master's thesis, 2020. http://hdl.handle.net/10451/45252.
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Trabalho de projecto de mestrado, Bioestatística, Universidade de Lisboa, Faculdade de Ciências, 2020O caribu, Rangifer tarandus groenlandicus, é uma das treze subespécies de rena que habita as regiões circumpolares do hemisfério Norte, sendo nativa da Gronelândia. A maioria dos estudos de investigação feitos no passado foram, regra geral, de curta duração, limitados e frequentemente mal desenhados ou extremamente enviesados. Ao ser caçado há pelo menos 4000 anos, o caribu possui elevada importância para as populações locais. Como tal, métodos com maior eficiência e precisão precisam de ser considerados para que a informação e monitorização obtidas para esta subespécie sejam mais sólidas e robustas. Desde o início do milénio, o Instituto para os Recursos Naturais da Gronelândia (Greenland Institute for Natural Resources - GINR) tem vindo a melhorar as metodologias utilizadas no controlo e monitorização das espécies presentes na Gronelândia, sendo o caribu uma das espécies de foco. No Oeste da Gronelândia, local onde existem populações nativas de caribus, não existem predadores naturais, o que torna as próprias características populacionais inerentes desta subespécie, características do habitat e a atividade antropogénica nos principais fatores responsáveis pelo controlo da população. A partir do ano de 2000, o GINR tem feito estudos aéreos de monitorização periódica do R. t. groenlandicus. O intuito destes estudos é o de estimar a sua densidade e abundância nas regiões de interesse, obtendo assim um panorama geral da sua abundância, distribuição e relação com algumas covariáveis recolhidas. Posteriormente, os seus resultados são usados para auxiliar a gestão de outras atividades como a caça, construção, entre outras. Recorriam-se a vários métodos baseados em estudos mais antigos mas, mais recentemente, os métodos de amostragem por distâncias têm vindo a ganhar destaque na investigação ecológica, tanto pela sua aplicabilidade em múltiplas situações como pela precisão das estimativas fornecidas. Primeiramente foi feita uma análise exploratória dos dados. Esta revelou que foram detetados cerca de 5 000 caribus em grupos maioritariamente até 4 indivíduos e localizados na sub-área de Sisimiut. Também mostrou ser concordante com os resultados obtidos em estudos anteriores e sugeriu elevada precisão inerente à amostra observada. Posteriormente procedeu-se à aplicação de métodos de amostragem por distâncias e ajustamento de um modelo espacial. Os métodos de amostragem por distâncias são usados para a estimação da densidade e abundância de objetos de interesse com base na distância dos mesmos ao observador. Esse objeto de interesse pode ser um ser vivo como uma espécie de animal ou de planta, ou pistas produzidas pelos mesmos (maioritariamente em animais) como ninhos, carcaças, fezes ou até no campo quer no ar ou em alto-mar, se deslocam ao longo de um transeto ou permanecem estáticos num determinado ponto por um intervalo de tempo fixo, observando a área em redor. Sempre que um objeto de interesse, no caso deste estudo, caribus individuais ou em grupo, é detetado, as distâncias perpendiculares dos mesmos à linha central do transeto são medidas e registadas. Outras covariáveis consideradas importantes na deteção dos objetos de interesse também podem ser recolhidas no momento da amostragem e analisadas em conjunto com as distâncias osbervadas. Estas distâncias permitem depois estimar uma função de deteção, a partir da qual se pode obter uma estimativa da probabilidade de deteção dos objetos de interesse. Esta estimativa representa a proporção de objetos de interesse detetados durante a amostragem e a sua relação com a distância ao observador é expressa pela função de deteção. Posteriormente, pode-se estimar a densidade e abundância totais ou estratificadas em caso de existência de sub-áreas dentro da área em estudo, o que acontece neste projeto. Após a seleção do modelo de amostragem por distâncias mais apropriado à amostra recolhida, procedeu-se ao ajustamento de um modelo aditivo generalizado (Generalized Additive Model - GAM) para determinar o número de caribus estimado em cada quadrícula de 1.5𝑘𝑚 × 1.5𝑘𝑚, considerando a probabilidade de deteção estimada anteriormente e a influência de outras covariáveis ambientais georreferenciadas também recolhidas e de interesse a priori. As covariáveis ambientais consideradas neste projeto foram o aspeto geográfico, a elevação e o declive. Recorrendo aos resultados do GAM obtido, um modelo de densidade espacial (Density Surface Model - DSM) dos objetos de interesse foi determinado através da extrapolação para a região de estudo. Este modelo representa a distribuição dos caribus ao longo da região de estudo como função das várias covariáveis consideradas sob a forma de um mapa de gradiente de cor. Para complementar o DSM, também foi criado um segundo mapa de gradiente de cor onde cada quadrícula representa a incerteza associada a cada estimativa obtida no DSM. Relativamente à distribuição espacial estimada pelo DSM para a espécie de estudo, este prevê que o caribu se encontra maioritariamente na sub-área de Sisimiut e minoritariamente na sub-área de Angujaartorfiup Nunaa, como previsto pela especialista. De acordo com o modelo selecionado, em termos de densidade, os caribus aparentam preferir superfícies direcionadas para Sul em detrimento das direcionadas para Norte. Além disto, a espécie de estudo parece apresentar uma relação negativa com o aumento da elevação e do declive. Estes resultados são concordantes com os obtidos em estudos anteriores realizados na mesma altura do ano. Para o presente projeto, focado na região Norte do Oeste da Gronelândia, a análise de amostragem por distâncias estimou uma probabilidade de deteção média de 0.54 e uma estimativa de abundância com base no delineamento amostral de cerca de 60 469 (IC 95%: 51 932, 70 410) caribus em toda a região de estudo. A sub-área de Sisimiut apresentou o maior foco da população, seguida pelas sub-áreas Angujaartorfiup Nunaa e Sisimiut Sul, com estimativas de 46 724, 9 814 e 3 931 caribus, respetivamente. O DSM estimou uma abundância de cerca de 73 895 (IC 95%: 65 983, 82 757) caribus em toda a região Norte. É de notar que os intervalos de confiança se sobrepõem parcialmente, sugerindo que a diferença entre estas estimativas não é estatisticamente significativa. Em ambas as metodologias a incerteza associada às estimativas obtidas foi relativamente baixa, sendo um indicador de precisão e consistência dos mesmos. A diferença entre as estimativas de abundância pode ser justificada pelas características dos métodos aplicados. A amostragem por distâncias convencional é uma metodologia cuja extrapolação é design-based, o que significa que certas regiões ou características não amostradas ou mal representadas pelos transetos considerados não serão tidas em conta nas estimativas. Por outro lado, o GAM é uma abordagem model-based, considerando a informação sobre toda a região de estudo na modelação através das covariáveis ambientais fornecidas. Este segundo tipo de abordagem tem como vantagem a representação espacial da informação, permitindo assim o melhor entendimento e visualizção de possíveis padrões espaciais na abundância do caribu e, consequentemente, o afinamento das suas medidas de gestão. Outra vantagem adicional é permitir uma estimativa e respetiva incerteza associada em qualquer sub-área de interesse desde que esteja devidamente definida. Para ter uma estimativa da abundância, basta integrar sob a superfície de densidade estimada. Por fim, comparando estas as estimativas pontuais com as obtidas em estudos anteriores, as primeiras são ligeiramente menores. Apesar disso, não existe evidência estatística que indique um decréscimo estatisticamente significativo na abundância dos caribus na região Norte do Oeste da Gronelândia. Recomenda-se, para estudos futuros e se possível, uma amostragem mais rigorosa no que diz respeito à categorização de covariáveis de interesse como a claridade, a profundidade e cobertura da neve, assim como a inclusão de outras covariáveis como a vegetação. Estas covariáveis poderão fornecer informação adicional sobre a distribuição da espécie de estudo.
The barren-ground caribou, Rangifer tarandus groenlandicus, is native to the west coast of Greenland, and has always been important for the human population. Its importance spans from cultural traditions and subsistence consumption to recreational and commercial harvesting. Hence, the importance of long-term monitoring to facilitate appropriate management strategies. To accomplish a robust monitoring method and to determine caribou density, Distance Sampling methods were used. These methods are widely used techniques for density and abundane estimation of a wide variety of taxa. In this project, the data from an aerial survey for caribou conducted by the Greenland Institute of Natural Resources (GINR) in the late winter of the year of 2018 was used to estimate abundance of caribou in the surveyed area. The survey data and the shapefiles with covariates to use in the DSM were provided by GINR. Starting from a conventional distance sampling perspective, the data set was then used to create a Density Surface Model (DSM) for caribou, i.e., a model describing caribou density as a function of additional covariates collected during the survey. An introduction about the study species and the region of interest is provided as well as a brief description of the sampling design, Distance Sampling methodology and some related methods. The results were consistent with previous studies in terms of distribution throughout the study region, but the spatial distribution map obtained a previously unavailable useful insight. The estimated confidence intervals for abundance overlap with estimates from previous studies. Even though the point estimates are smaller when compared to previous point estimates, these differences are not statistically signifficant.
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Wu, Tsung-Wei, and 吳崇維. "The Study of Improving the Shared Sampling Method for Alpha Matting Based on Earth Mover's Distance." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/v5nst8.
Full textAbstract:
碩士元智大學
電機工程學系
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Image matting purposes to cut the foreground region from an image by calculating pixel’s color value and estimating alpha value. In the past ten years, lots of papers on image matting have been published. Most of them obtain lower difference by using laplacian matting model. However, those algorithms’ laplacian matrix has too many elements, it takes a lot of time to solve the linear equations. In this paper, we do not want to spend too much time in the computing process, so choosing Shared Matting as our basic algorithm because it’s low cost time. And using Earth Mover’s Distance and simple laplacian matting to find each pixels’ alpha value. The results obtained by our method have lower difference than Shared Matting, and the computing time is within our expectation.
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Němec, Petr. "Analýza a optimalizace inventarizačních metod v podmínkách tropického deštného lesa v peruánské Amazonii." Doctoral thesis, 2014. http://www.nusl.cz/ntk/nusl-177232.
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The submitted work compares results of two forest inventories conducted on the plot of 200 ha within the forestry concession in the tropical rainforest in the Peruvian Amazon. First inventory conducted in 2007 used for field data collection the common method with tapes and mechanical compasses. The second inventory conducted in 2008 used a set of electronic devices, consisting of a field computer, laser rangefinder, electronic compass, a GPS unit and a specialized software Field-Map. In both inventories the positions of all trees with a dbh bigger or equal 400 mm were mapped and following attributes were recorded: position, species, total height, trunk height and dbh. Significant differences were discovered between both methods and the inadequacies were described. The results from the comparison study show that the method conducted using electronic devices is faster and more exact in measurement of tree attributes and in navigation on the plot. However, nor use of this method encompassed to map all the trees and that is why the distance sampling method for population density estimation was used for completion of inventory results. The population map of big trees was created and used for inventory simulations using circular and belt plots of different size and different density with the aim to find most suitable variants. Results of simulated inventories were evaluated regarding their accuracy and time expenses and the variants suitable for use in the zone were suggested.
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Nemitz, Dirk. "Bewertung der Erfassungswahrscheinlichkeit für globales Biodiversitäts-Monitoring: Ergebnisse von Sampling GRIDs aus unterschiedlichen klimatischen Regionen." Master's thesis, 2008. http://hdl.handle.net/11858/00-1735-0000-0022-5F99-F.
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