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1
Steele, Matthew. "Determining Oxygen Abundance vs. Age and Iron Abundance in Halo Field Dwarfs." Bowling Green State University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1120666230.
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DEMEIO, JULIAN LAWRENCE. "Abundance of rational points." Doctoral thesis, Scuola Normale Superiore, 2021. http://hdl.handle.net/11384/109444.
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For a smooth algebraic variety X defined over a number field K, one could ask several questions
about the abundance of its rational points.
This thesis revolves, in particular, around the following three properties: Hilbert Property,
weak approximation and strong approximation. The first concerns, more or less, the question of
extending the Hilbert Irreducibility Theorem to an arbitrary X (in the sense that the parameters
of the Theorem are allowed to vary through rational points of this variety), the interesting case
being when X is non-rational, for otherwise one recovers precisely the original theorem of Hilbert.
The other two concern the question of density of rational points of X in the adelic ones (possibly
with some places removed). The adjective weak" is more commonly used when talking about
proper varieties, and the adjective strong" is used otherwise.
In the first original work that is part of this thesis, we prove that, under a technical assumption,
a proper algebraic surface X, with Zariski-dense rational points, that is endowed with two or more
genus 1 fibrations, has the Hilbert Property. This result generalizes an earlier result of Corvaja
and Zannier, who proved the Hilbert Property for the Fermat surface x4 + y4 = z4 + w4. The
technique used is similar to theirs, the main idea being that of transporting rational points around
the surface using the elliptic fibers of the various fibrations.
In the second part of the thesis, we prove that on an arbitrary homogeneous space X, under
some technical assumptions, the étale-Brauer-Manin obstruction is the only one to strong approximation.
This obstruction is obtained by applying the more classical Brauer-Manin obstruction
on all finite étale torsors over X. The proof is basically a reduction to a theorem of Borovoi
and Demarche, who proved that (again under technical assumptions) strong approximation up to
Brauer{Manin obstruction holds on homogeneous spaces with connected stabilizers.
In this part of the thesis we also prove a compatibility result, suggested to be true by work of
Cyril Demarche, between Brauer pairing and the so-called abelianization map, for homogeneous
spaces of the form G=H, with H connected and linear.
Finally, in the third and last part of the thesis, we explore the problem of "ramified descent",
or, in other words, the question of which adelic points of X may be lifted to (a desingularization
of a twist of) a fixed geometrically integral and geometrically Galois cover φ : Y --> X, with
commutative geometric Galois group (although in some parts of the work this commutativity
assumption is not needed). The case where the cover is unramified is already well-studied, and,
therefore, the interest lies in the ramified case (whence the terminology "
amified descent"). We
prove that a certain naturally defined descent set" provides an obstruction to Hasse principle
and weak approximation on X (the main difficulty in proving this lies in showing that rational
points that lie on the branch locus of ' are unobstructed).
Moreover, in analogy with the classical unramied case, we construct a subgroup B' of the
Brauer group of X such that the the descent set associated to ' lies in the Brauer{Manin set
associated to B'. Interestingly enough, the transcendental part of B' may provide a non-trivial
obstruction, contrary to what happens in the unramified case. It seems reasonable to expect that
this B' is the only obstruction to the "ramified descent" problem.
3
Jonas, Seth H. "Aluminum-26 : an abundance mechanism." Honors in the Major Thesis, University of Central Florida, 2001. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/226.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Arts and Sciences
Physics
4
Stehle, Matthias. "Abundance Tomography of Type Ia Supernovae." Diss., lmu, 2004. http://nbn-resolving.de/urn:nbn:de:bvb:19-32721.
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Tsamis, Ionnis. "Heavy element abundance in ionized nebulae." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270150.
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Akerman, Christopher John. "Chemical abundance studies, near and far." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613697.
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Armstrong, David John. "On the abundance of circumbinary exoplanets." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/72676/.
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Circumbinary planets are bodies that orbit both components in a binary star system. This thesis focuses on transits of these planets, which with the aid of the Kepler space telescope have recently led to the discovery of several such objects. First, transit timing variations - departures from strict periodicity in the transit times - are studied. These arise from both the motion of the host stars and relatively rapid precession of the planet’s orbit. Limits on the maximum possible transit timing variation are derived, and tested against N-body simulations of simulated circumbinary systems. These limits are then utilised to form a search algorithm designed to find these planets in light curves, focusing on data from the WASP and Kepler observatories. This search algorithm uses an individual transit search to identify potential transit signatures, then forms periodograms allowing for the possible timing variations. It is used to identify several new candidate planets, as well as confirm detections of previously known circumbinary systems. In addition a number of interesting multiple stellar systems are identified including the as yet unexplained KIC2856960, which display multiple eclipses, significant tidal heating or rapid orbital evolution on the timescale of the 4 year Kepler observations. In 2013 unbiased stellar radii for the eclipsing binaries of the Kepler dataset were not available. A catalogue is produced, derived from spectral energy distribution fits to data from the KIS, HES and 2MASS surveys of the Kepler field, which gives temperatures for these stars accurate to ~300K. These are then used to find calibrated stellar masses and radii. These parameters, in combination with the search algorithm, are used to study circumbinary planet rates of occurrence in the Kepler dataset. The known sample of eclipsing binaries is tested for detectability, and a Monte Carlo population synthesis used to find probability density functions for these rates. These are a function of the as yet unknown circumbinary planetary inclination distribution, and show that the rate of occurrence of circumbinary planets is consistent with that of single stars if these planets are in the majority coplanar with their host binaries. However, if they are more misaligned, to a degree greater than that implied by a 5° Gaussian distribution, their rate of occurrence becomes significantly higher. Furthermore, it is confirmed that planets of Jupiter size and greater occur less often in circumbinary configurations, and that circumbinary planets are preferentially found around binaries with periods longer than ~7 days.
8
Momal, Raphaëlle. "Network inference from incomplete abundance data Accounting for missing actors in interaction network inference from abundance data Tree‐based inference of species interaction networks from abundance data." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASM017.
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Les réseaux sont utilisés comme outils en microbiologie et en écologie pour représenter des relations entre espèces. Les modèles graphiques gaussiens sont le cadre mathématique dédié à l'inférence des réseaux de dépendances conditionnelles, qui permettent une séparation claires des effets directs et indirects. Cependant, les données observées sont souvent des comptages discrèts qui ne permettent pas l'utilisation de ce modèle. Cette thèse développe une méthodologie pour l'inférence de réseaux à partir de données d'abondance d'espèces. La méthode repose sur une exploration efficace et exhaustive de l'espace des arbres couvrants dans un espace latent des comptages observés, rendue possible par les propriétés algébriques de ces structures.Par ailleurs, il est probable que les comptages observés dépendent d'acteurs non mesurés (espèces ou covariable). Ce phénomène produit des arêtes supplémentaires dans le réseau marginal entre les espèces liées à l'acteur manquant dans le réseau complet, ce qui fausse la suite des analyses. Le second objectif de ce travail est de prendre en compte les acteurs manquants lors de l'inférence de réseau. Les paramètres du modèle proposé sont estimés par une approche variationnelle, qui fournit des éléments d'information pertinents à propos des données non observéesNetworks are tools used to represent species relationships in microbiology and ecology. Gaussian Graphical Models provide with a mathematical framework for the inference of conditional dependency networks, which allow for a clear separation of direct and indirect effects. However observed data are often discrete counts and the inference cannot be directly performed with this model. This work develops a methodology for network inference from species observed abundances. The method relies on specific algebraic properties of spanning tree structures to perform an efficient and complete exploration of the space of spanning trees. The inference takes place in a latent space of the observed counts.Then, observed abundances are likely to depend on unmeasured actors (e.g. species or covariate). This results in spurious edges in the marginal network between the species linked to the latter in the complete network, causing inaccurate further analysis. The second objective of this work is to account for missing actors during network inference. To do so we adopt a variational approach yielding valuable insights about the missing actors
9
Dockendorf, Kevin J. "Relationships between zooplankton abundance and age-0 black crappie abundance and size at three productive Florida lakes." [Gainesville, Fla.] : University of Florida, 2002. http://purl.fcla.edu/fcla/etd/UFE0000523.
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McInnes, AM, DG Allan, and G. Malan. "Key sites for the conservation of waterbirds (Aves) in Durban Bay, South Africa." Durban Museum Novitates, 2005. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001003.
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Key sites for the conservation of waterbirds (Aves) in
Durban Bay, South Africa. Durban Museum Novitates 30: 1-14. Forty-eight monthly counts of waterbirds
were conducted in Durban Bay (July 1999-June 2003). A total of 47 227 waterbirds of 79 species were
recorded. Eighteen waterbird species were significantly more abundant in summer while seven were
significantly more abundant in winter. Centre Bank supported 40.6% of all waterbirds, comprising mainly
Palearctic waders and roosting gulls and terns. Distinct species assemblages of plovers (Charadridae) and
sandpipers (Scolopacidae) were associated with the two most selected of the intertidal sites: Bayhead and
Centre Bank. The assemblage at Centre Bank included three large-bodied Palearctic species (Greenshank,
Grey Plover and Whimbrel), all of which occurred in abundance there and showed strong selection for this
site. The assemblage which showed strong site selection for Bayhead consisted of both resident and
Palearctic species, five of which are known to favour finer sediments (Ringed and Kittlitz's plovers,
Common and Terek sandpipers, and Little Stint). Bayhead had a higher number of waterbird species that
occurred at higher densities, when compared with Centre Bank, and showed the highest species-diversity
ranking of all sites. This may be a result of the more heterogenous nature of this area. Sporting Bodies-
Pelican Island had high densities of, and strong site selection by, piscivorous species and species associated
with the semi-natural shorelines of this area. This site, however, supported only 8.6% of all waterbirds
counted during the study period. Fish Wharf-Yacht Basin had the highest numbers and densities of Greyheaded
Gulls, which utilized this area when scavenging. Other waterbird species were poorly represented
here and this site had the lowest species-diversity ranking. Commercial harbour areas were the least
attractive for waterbirds in terms of species-abundance values, densities and site selection. This is largely
attributed to the artificial nature of these areas. It is recommended that Centre Bank receive highest priority
for conservation status within the Bay. Reasons for conserving this site include: (a) the high overall
abundance of waterbirds that this site supports; (b) the unique assemblage of Palearctic waders that utilizes
this area, and the overall contribution that this has to waterbird diversity in the Bay; and (c) the importance
of this site to roosting gulls and terns, particularly Kelp Gull which has regionally, and potentially globally,
significant numbers in this area.
11
Labuschagne, K., LJ Gerber, I. Espie, and S. Carpenter. "Culicoides biting midges at the National Zoological Gardens of South Africa." Onderstepoort Journal of Veterinary Research, 2007. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001257.
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Abstract
Culicoides biting midges (Diptera: Ceratopogonidae) are responsible for the transmission of a large
number of pathogens to livestock and wild animals. In this study the presence of the genus, using light
traps based at four different sites within the National Zoological Gardens of South Africa, was investigated
during 2002-2004. In total, 37species were recorded, including large numbers of Culicoides
irnicola Kieffer, 1913, which is responsible for the transmission of economically important arboviruses
in South Africa, Europe, Middle and Far East. These results are discussed with reference to the wider
Culicoides fauna in the Onderstepoort area of South Africa, their vector competence as well as biosecurity
at the National Zoological Gardens.
12
Brewer, Andrew M. "Interactions between demographic rates, population density and the environment : the spatial structure of the range of the holly leaf-miner." Thesis, University of Sheffield, 2001. http://etheses.whiterose.ac.uk/14830/.
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Generalisations about the abundance structure of species' geographic ranges may have implications within a number of areas of applied ecology. However, empirical data is largely restricted to a single taxonomic group within one geographic region. One approach to the study of range structure and its ecological consequences is to examine the relationship between demographic rates and environmental conditions. However, most studies of population processes are at small spatial scales and it is not known to what extent patterns found at these scales may be extrapolated. This thesis addresses these issues using surveying techniques to measure spatial structure in both the densities and demographic rates of the holly leaf-miner (Phytomyza ilicis Curt.) at a wide variety of spatial scales. Geostatistical tools are used to analyse the data collected. At a regional scale, spatial structure in leaf-miner densities is apparent despite considerable variation between hosts within individual habitat patches. This structure can in part be accounted for by variation in habitat and altitude. Over the entire range, broad scale trends in population density can be detected which can also, be correlated with environmental variation.' Many demographic rates components exhibit spatial structure. However, their relationships both with population density and environmental variation are more complex. Per capita mortality rates did not correlate well with population density at any spatial scale. The difficulties inherent in relating population density with demographic rates and regulation by natural enemies are discussed. The demographic approach has also been used to explain.the positive interspecific abundance-distribution relationship. Computer simulation techniques are employed to explore this model. The results indicate that the positive relationship should be extremely robust under a high degree of variation between the demographic rates. However, data from the holly leaf-miner surveys suggest that current. models of range structure make unrealistic assumptions about environmental variation. The key to understanding range structure and its consequences may lie in our ability to make. generalisations about environmental structure.
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Friesen, Trevor. "Effects of food abundance and temperature on growth, survival, development and abundance of larval and juvenile smallmouth bass." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ33299.pdf.
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Sullivan, Madsen Paul. "Effects of and Influences on Microbial Populations of Missouri Maize Fields." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7706.
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The role of individual soil microorganisms changes over the course of a plant's life - microorganisms that have no discernable role at one developmental stage may affect the plant later in its growth. Traditional analysis of the soil microbiome, which has focused principally on the relative abundances (RA) of individual organisms, may be incomplete, as underlying differences in population size cannot be addressed. We conducted a metagenomic analysis of soil microorganisms from various maize (Zea mays L.) fields at two depths, accompanied by crop yield components, to provide insight into influences of edaphic microbes on maize productivity under commercial maize production systems in Missouri. This study assesses the influence of fungi and bacteria, not only in terms of RA, but also in their estimated absolute abundances (EAA), derived by combining the results of Illumina HiSeq sequencing data and phospholipid fatty acid abundance data. Significant interactions were identified between maize yield components and soil microbes at critical developmental states. Most interactions between fungi and yield components were negative, with notable exceptions. Bacterial interactions were more complex, with most interactions during early ear development identified as positive, and most interactions during tasseling identified as negative. In addition to the effects that microbial populations have on yield, plant populations reciprocally changed the microbial community. Plant developmental state was the greatest predictor of bacteria, with the microbial communities present during the active growing season being most similar to each other, whereas the preplant microbiome and post-reproductive microbiome being most similar to each other. Fungal communities were primarily dependent on location.
15
Temple, Victoria. "Creating health and abundance with complementary currencies." [Denver, Colo.] : Regis University, 2005. http://165.236.235.140/lib/vtemple2005.pdf.
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Benisty, Hannah 1986. "Post-transcriptional determinants of RAS protein abundance." Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/668206.
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The RAS oncogenes KRAS, NRAS and HRAS are mutated in one third of human cancers where they exhibit different mutation patterns. A potential factor contributing to this mutation bias is the variation of RAS expression levels. Here, I investigate some of the determinants of RAS protein abundance. First, I examine whether codon bias among RAS genes and within other cancer gene families plays a role in cell context-specific expression. I further describe a tRNA expression program that favors oncogene translation in proliferating cells. Second, I investigate why oncogenic RAS mutants exhibit a higher protein abundance than the RAS wild type. In this context, I study the underlying mechanisms leading to this variation and more specifically how protein-protein interactions between RAS and its downstream binding partners change the protein turnover of RAS and therefore, its protein abundance. Overall, this thesis provides insight into the possible relevance of RAS protein synthesis and protein degradation as determinants of RAS mutation patterns in human cancers.Els oncogens KRAS, NRAS i HRAS estan mutats en un terç dels càncers en humans on hi exhibeixen patrons de mutació diferents. Un possible factor que contribueix a aquest biaix de mutació és la variació dels nivells d'expressió de RAS. En aquesta tesi investigo els elements determinants de l'abundància de la proteïna RAS. Primer, examino si el biaix de codó entre els gens RAS i entre gens d'altres famílies implicades en càncer contribueix a les diferències d'expressió, en funció del context cel·lular. Així mateix, descric un programa d'expressió de tRNA que facilita la traducció d'oncogens en cèl·lules proliferatives. En segon lloc, investigo per què mutants oncogènics de RAS tenen una abundància de proteïna més elevada que la RAS salvatge. Així mateix, estudio els mecanismes subjacents responsables d'aquesta variació i més concretament el paper de les interaccions de RAS amb altres proteïnes en la regulació de la seva abundància. Així doncs, aquesta tesi estudia la possible rellevància dels mecanismes de síntesi i degradació de la proteïna RAS en els patrons de mutació en càncer.
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Harris, Danielle V. "Estimating whale abundance using sparse hydrophone arrays." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3463.
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Passive acoustic monitoring has been used to investigate many aspects of marine mammal ecology, although methods to estimate absolute abundance and density using acoustic data have only been developed in recent years. The instrument configuration in an acoustic survey determines which abundance estimation methods can be used. Sparsely distributed arrays of instruments are useful because wide geographic areas can be covered. However, instrument spacing in sparse arrays is such that the same vocalisation will not be detected on multiple instruments, excluding the use of some abundance estimation methods. The aim of this thesis was to explore cetacean abundance and density estimation using novel sparse array datasets, applying existing methods where possible, or developing new approaches. The wealth of data collected by sparse arrays was demonstrated by analysing a 10-year dataset collected by the U.S. Navy's Sound Surveillance System in the north-east Atlantic. Spatial and temporal patterns of blue (Balaenoptera musculus) and fin whale (Balaenoptera physalus) vocal activity were investigated using generalised additive models. Distance sampling-based methods were applied to fin whale calls recorded by an array of Ocean Bottom Seismometers in the north-east Atlantic. Estimated call density was 993 calls/1000 km².hr⁻¹ (CV: 0.39). Animal density could not be estimated because the call rate was unknown. Further development of the call localisation method is required so the current density estimate may be biased. Furthermore, analysing a single day of data resulted in a high variance estimate. Finally, a new simulation-based method developed to estimate density from single hydrophones was applied to blue whale calls recorded in the northern Indian Ocean. Estimated call density was 3 calls/1000 km².hr⁻¹ (CV: 0.17). Again, density of whales could not be estimated as the vocalisation rate was unknown. Lack of biological knowledge poses the greatest limitation to abundance and density estimation using acoustic data.
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Brandejsová, Jana. "Abundance včelstev v krajině a úživnost katastru." Master's thesis, Česká zemědělská univerzita v Praze, 2016. http://www.nusl.cz/ntk/nusl-260588.
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Determining place thesis Abundance of bee colonies in the country and the carrying capacity of the land register. Establishing a Connection in Úvaly near Prague with three beekeepers. For these three beekeepers were required to determine reserves of pollen with three visits in the period of May, June and July. Each measurement was carried out always at the three strongest hives. Proven reserves of pollen was performed using photographs of each honeycomb in the hive. After calculating reserves of pollen, to assess the value of honey to the surrounding plants. The conclusion was to determine whether a load for the site Úvaly near Prague is present or not enough bees and suggest possible solutions.
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Tracey, John Paul. "Assessing estimators of feral goat (Capra hircus) abundance." Connect to this title online, 2004. http://cicada.canberra.edu.au/public/adt-AUC20050708.103427/.
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Vradenburg, John. "Distribution and abundance of anurans in southeast Missouri." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4258.
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Thesis (M.S.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (January 10, 2007) Includes bibliographical references.
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Tracey, John Paul, and n/a. "Assessing estimators of feral goat (Capra hircus) abundance." University of Canberra. Resource, Environmental & Heritage Management, 2004. http://erl.canberra.edu.au./public/adt-AUC20050708.103427.
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(1) Reliable measures of population abundance are essential for managing wildlife
effectively. Aerial surveys provide a rapid and efficient means of surveying large mammals
and many techniques have been developed to adjust for the inability to count all animals
within transects. The probability of detection varies according to a range of factors which
are important to consider when estimating density. Standardised survey methods developed
in flat country are not readily transferable to steep terrain due to safety, access and
difficulties delineating transect widths. Other methods have logistic constraints and must
adhere to various other assumptions.
(2) Density estimators are seldom examined using actual population size, hence their
ability to correct for true bias is unknown. Studies that compare techniques are difficult to
interpret because of the uncertainty of adherence to their respective assumptions. Factors
influencing detection probability, estimators that correct for bias, the validity of their
assumptions and how these relate to true density are important considerations for selecting
suitable methods. The aim of this study was to obtain accurate and reliable methods for
estimating the density of feral goats by improving predictions of detection probability,
investigating the assumptions of aerial surveys, and examining the accuracy of 15 density
estimators by comparing with total counts of feral goats.
(3) Group size, vegetation and observer were the most important factors influencing the
probability of observing a group of goats during aerial surveys. However, different
approaches to analysing these data influenced the significance of variables and the
predicted probabilities. Goat colour, type of helicopter, site and rear observer experience in
hours were also found to be significant (P<0.05) when using likelihood equations based on
all animals in the population rather than only those in the sample. The slope of the terrain
was also shown to significantly (P=0.014) affect the probability of detection.
(4) Indices are commonly used in wildlife management for their simplicity and
practicality, but their validity has been questioned because of variable probability of
detection. Results of this study suggest aerial survey indices are useful in monitoring a
range of medium-sized mammal species across space and time if differences in detection
probability between species, group size, vegetation and observer are considered and their
effects are standardised.
(5) An assumption of most sampling regimes that is fundamental but rarely examined is
that animals are not counted more than once. In this study the behavioural responses of
feral goats to helicopters were investigated as a basis for estimating the probability that
goats were recounted. No long-term consequences were evident in feral goat behaviour of
responses to helicopters. However, helicopter surveys were found to alter the structure of
42% of groups observed, with 28% of groups merging with others and 14% splitting into
separate groups. Therefore, group size estimated from the air should not be considered as
biologically important, and when estimating density, researchers should also avoid using
group sizes determined from independent ground observations to correct group sizes
determined from aerial surveys. Goats were also more likely to flush further when
helicopters were within 150 m, which is close to or within standard helicopter strip widths.
Substantial movement occurred between transects and 21% of goats were estimated to be
available for recounting in adjacent transects.
(6) Different detection probabilities between groups of goats may be particularly
relevant when using double-counting, where multiple observers are �capturing� and
�recapturing� animals in the same instant. Many analyses test and adjust for this �unequal
catchability� assumption in different ways, with the approaches of Huggins and Alho
allowing prediction of unique probability values for a range of co-variates. The approach of
Chao attempts to correct for skewed distributions in small samples. The Horvitz-Thompson
approach provides a useful basis for estimating abundance (or density) when detection
probability can be estimated and is known to vary between observations according to a
range of independent variables, and also avoids errors associated with averaging group size.
(7) After correcting for recounting, the Alho estimator applied to helicopter surveys
was the most accurate (Bias = 0.02) and reliable of all techniques, which suggests that
estimates were improved by taking into account unconditional detection probability and
correcting individual observations according to their characteristics. The positive bias
evident in the Chao (Bias = 0.28) and Petersen (Bias = 0.15) aerial survey estimators may
have been a result of averaging detection probability across all observations. The
inconsistency and inaccuracy of the ground-based area-count technique emphasises the
importance of other assumptions in density estimation, such as representative sampling and
availability bias. The accuracy of index-manipulation-index techniques was dependent on
the indices used. Capture-recapture estimates using mustering showed slight negative bias
(Bias = -0.08), which was likely a result of increased probability of re-capture (i.e. trap
happy). Ground-based capture-resight estimates were labour intensive and positively biased
(Bias = 0.13), likely due to underestimating the area sampled, or overestimating the number
of unmarked individuals with each sample.
(8) Helicopter survey using double-counting is recommended for estimating the density
of feral goats in steep terrain. However, consideration of recounting under intensive
sampling regimes and adjustments for the factors that influence unconditional detection
probability is required.
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Bilodeau-Goeseels, Sylvie. "Changes in RNA abundance in early bovine embryos." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq20726.pdf.
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Ecke, Frauke. "Effects of landscape patterns on small mammal abundance." Doctoral thesis, Luleå, 2003. http://epubl.luth.se/1402-1544/2003/30/index.html.
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Hansteen, Anja Pandora Ulsom. "Oil Abundance, Ethnic Minority Rule, and Civil War." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for samfunnsøkonomi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23064.
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Chandramohan, Preethi. "Causal relationships between sulphur emissions and pathogen abundance." Thesis, University of Reading, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525131.
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Gardner, M. J. "Circadian rhythms in transcript abundance in Arabidopsis thaliana." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599310.
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To characterise the circadian transcriptome, the expression profiles of transcripts in whole leaves of mature, soil grown A. thaliana plants were analysed. Circadian-regulated transcripts constituted approximately 9.5% of the transcripts detected, and were found to encode proteins involved both a well-described circadian processes and in pathways that have not been previously identified as having circadian regulation. Transcripts encoding proteins involved in core metabolic processes and stress response pathways were particularly highly representative in the dataset, which suggested a potential basis for the fitness benefits associated with the possession of a functional biological clock. To determine the correlation between rhythms in transcript abundance in whole leaves and in a single cell type, the stomatal guard cell was selected as a model system. However, assessment of two published methods of guard cell isolation, epidermal fragmentation and guard cell protoplasting, revealed that neither method was suitable for analysis of circadian rhythms in transcript abundance. Consequently, single cell analysis was not pursued. Nevertheless, bio-informatic analysis of the whole leaf circadian transcriptome and published microarray data was employed in order to characterise components of the intra-cellular circadian signalling pathway. This analysis revealed a relationship between the circadian oscillator and the regulator of [Ca2+]cyt release, cyclic adenosine disphosphate ribose (cADPR). Evidence is presented suggesting that circadian [Ca2+]cyt oscillations form a component of the oscillator that maintains the periodicity of circadian rhythms in transcript abundance. Collectively the data presented provide an overview of the biological clock in A. thaliana, and form a resource for further analysis of the structure of the clock and its role in integrating diverse cellular and physiological processes into a coherent biological programme.
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Waring, Paul. "Abundance and diversity of moths in woodland habitats." Thesis, Oxford Brookes University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277095.
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The abundance and diversity of moths and their larvae are compared in various woodland habitats within Bernwood Forest in lowland England to assess the impact of large-scale planting of introduced conifers and of conservation measures including coppicing and ride-side management. Light trap catches of moths in conifer plantations and in a recently coppiced site contained significantly fewer individuals and fewer species over the year compared with sites in adjacent overgrown coppice, but species diversity, measured by Fisher's index 0<. , was higher because cat ches in the latter were dominated by some very abundant species. Only 14 of the 431 species of macro-moths recorded from Bernwood Forest have larvae which feed on conifers but 138 species were found breeding on native weed species in the conifer plantations. Densities of larvae on individual native shrubs in conifer plantations were not significantly different from those in broadleaved stands. Mark and recapture of adult moths demonstrated considerable movement between habitats. More moths of more species were caught in rides than in adj acent woodland stands using Robinson traps. Heath traps in rides frequently did not catch more species or more moths than within woodland stands. Catches in Heath traps were generally largest in overgrown coppice. Catches at all sites were related to the abundance of larval host-plants but were also influenced by the distance over which the trap was visible and the amount of canopy shade. Three methods of cornpensat ing for differences in shade between trap-sites are explored. Heath traps at ride intersects captured on average 55% of the species at a Robinson trap per night; in woodland stands catches averaged 68% of the species. At least thirteen nationally rare species have disappeared from Bernwood since timber clearance prior to conifer planting. The implications for biological survey work and for nature conservation are discussed,
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Maudsley, Martin J. "Regional differences in the abundance of cereal aphids." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359262.
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Al-Fahmi, Mohammed M. "Controls on fracture abundance in gently deformed carbonates." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:74e221c4-6b37-46a5-bba8-7aaa458bed92.
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Fractures can profoundly affect the capacity of carbonate reservoirs to store and permeate fluids, depending on the properties and abundance of fractures. Fractures exist abundantly in carbonate outcrops; however, their abundance in subsurface carbonates is obscure because of the data shortages and uncertainties about the factors that drive fracturing in sedimentary basins. The objective of this research is twofold. The first is to study abundance of fractures in gently deformed carbonates, which were generally overlooked. The second is to address measuring fracture abundance using electrical borehole imaging, which is the mostly used method to describe reservoir fractures. Fractures were studied from areas in the gently folded and shallowly (less than 2 km depth) buried interiors of the Arabian Platform. The study areas include outcrops and reservoirs of the Late Jurassic Arab carbonates in the sprawling homocline of Central Arabia and a low-relief dome in Eastern Arabia. The Cenozoic Rus carbonates in the dome outcrops were also studied. Fracture abundance was measured from the outcrops using scanlines and from the reservoirs using core and borehole images of extended-reach drilling. Many systematic properties were drawn on mineralization, orientation, and abundance of fractures. The fractures were found to be opening mode, mostly barren, and exist with subvertical dips, and some regional trends. The fractures display significantly differing ranges of abundance that were controlled by the subtle structural bending of the dome and homocline, carbonate lithofacies, and paucity of fracture mineralization. The borehole imaging was found to significantly lower fracture abundance. The detection of fractures was subject to several factors including size of fracture widths, nature of fracture roughness, and present-day stress field. The results have implications for modeling of fracture systems and tectonic regimes. For example, finding that fracture abundance varies drastically in such gently deformed regions indicates that carbonates are very sensitive to fracturing processes. Moreover, the borehole imaging limitations influence the models of fracture abundance and orientations, which are often used to deduce paleo tectonic regimes and present-day geodynamics in carbonate reservoirs.
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Krahmer, Johanna. "Circadian abundance and modification of proteins in Arabidopsis." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/15969.
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Circadian clocks are endogenous pacemakers found in many organisms including plants, generating approximately 24h rhythms. Knowledge about the plant circadian clock plays a role for crop improvement. The plant circadian clock and its downstream outputs have been studied in detail by transcriptomics, however post-transcriptional and post-translational aspects are still to be researched. In addition, it has recently been shown that a protein modification remains rhythmic when rhythmic transcription is absent. This gives evidence for the existence of two oscillators: a transcription-translation feedback loop and a non-transcriptional oscillator. The aim of this PhD is to gain knowledge about circadian changes in abundance and phosphorylation of proteins as well as protein-protein interaction using the model plant Arabidopsis thaliana. I used high-throughput proteomics and phosphoproteomics methods to identify hundreds of phosposites that change in abundance in WT plants as well as dozens of proteins that exhibit circadian changes in their abundance. I also found significant temporal changes in protein phosphorylation in the transcriptionally arrhythmic mutant CCA1-Ox, albeit with dynamics different from the WT, demonstrating that without transcriptional rhythms, protein modification can still undergo rhythmic changes to some extent. In addition, I found reproducibly that the majority of changing phosphopeptides are most abundant at dawn and this is independent of the presence of a functional transcriptional oscillator. Roles of different kinases and affected phosphoproteins are discussed. I chose one of the rhythmically phosphorylated proteins, the bifunctional enzyme F2KP, for further functional experiments. In vitro experiments demonstrate that the rhythmic phosphosite is important for the activity of the enzyme. This is discussed in the light of circadian regulation of carbon metabolism. In addition to these studies on circadian protein abundance and modification, I investigated time-of-day dependent protein-protein interaction of the clock protein GIGANTEA (GI). Using an interaction proteomics timecourse, I identified about 100 potential new interactors of GI, some of which are candidates for links between diel timing and carbon metabolism. These results will help to generate hypotheses for explaining the surprising pleiotrophy of gi mutants.
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Kirat, Yassine. "Economic and environmental impacts of natural resources abundance." Thesis, Paris 1, 2019. http://www.theses.fr/2019PA01E056.
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Cette thèse étudie la façon dont les sociétés utilisent, entretiennent et préservent les ressources naturelles qui façonnent fondamentalement le bien-être de l'humanité, l'environnement et l'économie. Les liens entre la prospérité économique, ressources et impacts environnementaux et la protection environnementale sont complexes et variés. Cela signifie que, si toutes ces dimensions ne sont pas prises en compte dans l'élaboration des politiques publiques, tout progrès dans la réalisation des ambitions dans ces domaines peut être entravé par des conséquences négatives. Une question importante dans les études sur le développement est de savoir comment la richesse en ressources naturelles affecte la croissance économique à long terme. Dans la perspective de répondre à cette question, le premier chapitre étudie l'impact de l'exploitation des ressources non-conventionnelles sur le secteur manufacturier des États-Unis sur la période 1997-2013. Dans la même perspective, le troisième chapitre étudie l'impact de l'abondance de ressources naturelles fossiles et minérales sur l'économie en exploitant le canal de la volatilité de la rente due aux ressources naturelles sur un panel de 103 pays entre 1985-2014. Par ailleurs, l'extraction et la transformation des ressources naturelles sont souvent des activités à forte intensité énergétique qui impliquent des modifications à grande échelle des écosystèmes. Le deuxième chapitre de la thèse étudie l'impact de l'abondance des ressources naturelles sur l'intensité en CO2 dans les pays développés sur la période 1995-2014This thesis examines how societies use and sustain the natural resources that fundamentally shape human well-being, the environment and the economy. The links between economic prosperity, resources and environmental preservation are complex and diverse. This implies that, if all dimensions are not taken into account in public policy making, any progress in achieving objectives in these areas can be hindered by undesirable outcomes. A key issue in development studies is how natural resource wealth affects long-term economic growth. In order to address this question, the first chapter examines the impact of non-conventional resource development on the US manufacturing sector over the period 1997-2013. In the same veine, chapter 3 examines the impact of abundant natural resources on the economy by exploiting the volatility channel of natural resources rent on a panel of 103 countries between 1985-2014. Moreover, the extraction and processing of natural resources are often energy-intensive activities that involve large-scale ecosystem alterations. Chapter 2 of the thesis investigates the impact of natural resource abundance on CO2 intensity in developed countries over the period 1995-2014
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Gera, Geetanjali. "Motor abundance contributes to resolve multiple task constraints." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 109 p, 2009. http://proquest.umi.com/pqdweb?did=1885754581&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Ritchey, Adam M. "The Abundance of Boron in Diffuse Interstellar Clouds." Connect to full text in OhioLINK ETD Center, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1250896589.
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Dissertation (Ph.D.)--University of Toledo, 2009.Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Physics." Bibliography: leaves 113-121.
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Dennis, Emily Beth. "Development of statistical methods for monitoring insect abundance." Thesis, University of Kent, 2015. https://kar.kent.ac.uk/49079/.
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During a time of habitat loss, climate change and loss of biodiversity, efficient analytical tools are vital for population monitoring. This thesis concerns the modelling of butterflies, whose populations are undergoing various changes in abundance, range, phenology and voltinism. In particular, three-quarters of UK butterfly species have shown declines in their distribution, abundance, or both over a ten-year period. As the most comprehensively monitored insect taxon, known to respond rapidly and sensitively to change, butterflies are particularly valuable, but devising methods that can be fitted to large data sets is challenging and they can be computer intensive. We use occupancy models to formulate occupancy maps and novel regional indices, which will allow for improved reporting of changes in butterfly distributions. The remainder of the thesis focuses on models for count data. We show that the popular N-mixture model can sometimes produce infinite estimates of abundance and describe the equivalence of multivariate Poisson and negative-binomial models. We then present a variety of approaches for modelling butterfly abundance, where complicating features are the seasonal nature of the counts and variation among species. A generalised abundance index is very efficient compared to generalised additive models, which are currently used for annual reporting, and new parametric descriptions of seasonal variation produce novel and meaningful parameters relating to phenology and survival. We develop dynamic models which explicitly model dependence between broods and years. These new models will improve our understanding of the complex processes and drivers underlying changes in butterfly populations.
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Holt, Alison R. "Positive interspecific abundance occupancy relationships : a test of mechanisms." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246979.
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PALLA, MARCO. "Cosmic Chemical and Dust Evolution." Doctoral thesis, Università degli Studi di Trieste, 2022. http://hdl.handle.net/11368/3014976.
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In this Thesis, we investigate the chemical and dust evolution of the different galactic environments we encounter during the cosmic history, from the high-redshift Universe to the Milky Way. The study of the evolution of galaxies is performed by means of detailed chemical evolution models that predict the abundances of single chemical elements in the interstellar medium as well as the condensation into dust of the chemical elements.
In the first part of the Thesis, we concentrate on the study of moderate to high-redshift systems. We start focusing on high-redshift starburst galaxies, whose extreme conditions pose questions on the universality of the initial mass function (IMF) as well as on the processes regulating the ISM dust. For these reasons, we test the the impact of the IMF shape on high-redshift environments by applying the so-called Integrated Galactic IMF (IGIMF) theory in models specifically suited for starburst galaxies. In this way, we look at the interplay between the IMF and dust processes in shaping the observed gas abundance patterns as well as global dust quantities. This analysis highlights the degenerate effect of the IGIMF and dust on abundance patterns and suggests that the IGIMF can explain the dust masses observed in some high-redshift star forming objects. To get a more complete picture about dust through cosmic evolution, we also investigate how dust quantities evolve at larger volume scales. To this aim, we present a novel method to compute the redshift evolution of dust mass in galaxy clusters. This is done by integrating the predictions of chemical and dust evolution models for individual galaxies over the galaxy cluster luminosity function (LF), assuming suitable cosmological scenarios for the LF evolution. By applying this method, we reproduce the dust amounts observed in low and intermediate-redshift galaxy clusters and we answer to some questions about dust in cluster. In particular, we find that spiral galaxies are the most important dust producers within clusters and that galactic ejecta can account alone for the observed intracluster dust.
In the second part of the Thesis, instead, we focus on study of the local Universe and in particular of the MW Galaxy. We start investigating the evolution of the MW thick and thin discs by comparing MW models with recent survey data. In particular, we discuss the formation of abundance gradients in the MW and the main physical parameters influencing this process, concluding that inside-out disc formation should act together with radial gas flows and variable efficiency of star formation. Moreover, we suggest that to reproduce the observed [α/Fe] dichotomy/bimodality (i.e., the presence of two distinct data sequences in the [α/Fe] vs. [Fe/H] diagram) at different Galactocentric distances, one should assume a prolonged gap between the formation of the thick and thin discs and a chemically enriched gas accretion in the innermost thin disc. Finally, we study the impact of different Type Ia SN yields on the evolution of Fe-peak elements in our Galaxy. To this aim, we apply to our chemical models for the MW a large compilation of Type Ia SN yields from the recent literature, sampling different explosion mechanisms. The obtained results are compared with those obtained with classical Type Ia SN prescriptions adopted in previous studies. In addition, we allow combinations of of Type Ia SN yields from different progenitor classes to assess their role in terms of the chemical enrichment. We find that the chemical abundance patterns strongly depend not only on the explosion mechanism but also on other conditions. Moreover, the comparison with the observed abundance trends suggests that a combination of different classes of explosion is necessary to reproduce the data.In this Thesis, we investigate the chemical and dust evolution of the different galactic environments we encounter during the cosmic history, from the high-redshift Universe to the Milky Way. The study of the evolution of galaxies is performed by means of detailed chemical evolution models that predict the abundances of single chemical elements in the interstellar medium as well as the condensation into dust of the chemical elements. In the first part of the Thesis, we concentrate on the study of moderate to high-redshift systems. We start focusing on high-redshift starburst galaxies, whose extreme conditions pose questions on the universality of the initial mass function (IMF) as well as on the processes regulating the ISM dust. For these reasons, we test the the impact of the IMF shape on high-redshift environments by applying the so-called Integrated Galactic IMF (IGIMF) theory in models specifically suited for starburst galaxies. In this way, we look at the interplay between the IMF and dust processes in shaping the observed gas abundance patterns as well as global dust quantities. This analysis highlights the degenerate effect of the IGIMF and dust on abundance patterns and suggests that the IGIMF can explain the dust masses observed in some high-redshift star forming objects. To get a more complete picture about dust through cosmic evolution, we also investigate how dust quantities evolve at larger volume scales. To this aim, we present a novel method to compute the redshift evolution of dust mass in galaxy clusters. This is done by integrating the predictions of chemical and dust evolution models for individual galaxies over the galaxy cluster luminosity function (LF), assuming suitable cosmological scenarios for the LF evolution. By applying this method, we reproduce the dust amounts observed in low and intermediate-redshift galaxy clusters and we answer to some questions about dust in cluster. In particular, we find that spiral galaxies are the most important dust producers within clusters and that galactic ejecta can account alone for the observed intracluster dust. In the second part of the Thesis, instead, we focus on study of the local Universe and in particular of the MW Galaxy. We start investigating the evolution of the MW thick and thin discs by comparing MW models with recent survey data. In particular, we discuss the formation of abundance gradients in the MW and the main physical parameters influencing this process, concluding that inside-out disc formation should act together with radial gas flows and variable efficiency of star formation. Moreover, we suggest that to reproduce the observed [α/Fe] dichotomy/bimodality (i.e., the presence of two distinct data sequences in the [α/Fe] vs. [Fe/H] diagram) at different Galactocentric distances, one should assume a prolonged gap between the formation of the thick and thin discs and a chemically enriched gas accretion in the innermost thin disc. Finally, we study the impact of different Type Ia SN yields on the evolution of Fe-peak elements in our Galaxy. To this aim, we apply to our chemical models for the MW a large compilation of Type Ia SN yields from the recent literature, sampling different explosion mechanisms. The obtained results are compared with those obtained with classical Type Ia SN prescriptions adopted in previous studies. In addition, we allow combinations of of Type Ia SN yields from different progenitor classes to assess their role in terms of the chemical enrichment. We find that the chemical abundance patterns strongly depend not only on the explosion mechanism but also on other conditions. Moreover, the comparison with the observed abundance trends suggests that a combination of different classes of explosion is necessary to reproduce the data.
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Yimingniyazi, Wuernisha. "Relic abundance of WIMPs in non-standard cosmological scenarios." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=985383542.
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Ambroso, Stefano. "Distribution patterns and abundance of Antarctic pristine benthic communities." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/671472.
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Knowledge of the abundance, distribution patterns, and population ecology of antarctic benthic biodiversity have increased considerably during the last decades. Antarctic marine benthic biodiversity has been sampled primarily in areas close to research stations and mainly at shallow depths since more than 100 years using a range of sampling methods, including benthic sleds or trawls and grabs each of which targets a particular community or habitat. Recent technological advances and increased availability of remotely operated vehicles (ROVs), manned submersibles, and video equipped towed gears have significantly increased accessibility to mid and outer continental shelves, continental slopes, submarine canyons and seamounts, thus allowing the direct observation and quantitative study of megabenthic assemblages wthout any impact on the benthic community.
Due to the high cost and logistics of these benthic sampling, particularly in Antarctica, studies are often limited to only one biological sampling method. Results of biodiversity studies are used for a range of purposes, including taxonomy, trophic ecology, growth rates, reproductive ecology, environmental impact assessments, and predictive modelling, all of which underpin appropriate marine resource management. However, the generality of marine biodiversity patterns identified among different sampling methods is unknown.
This is one of the resons why more comparative studies are necessary to better understand the ecosystem patterns and processes in antactic regions in a context of climate change scenario.
Major regions of the Antarctic shelf appear to be undergoing rapid climate change, such as warming on the Antarctic Peninsula in the past few decades. Such climate change will affect benthic ecosystems through changes in benthic-pelagic coupling. For these porpouse this tesis pretend to generally understand the distribution and the eocological paper that benthic organisms have on the benthic ecosystem of the antarctic continental shelf. This thesis includes for chapters
In the first chapter we investigate ophiuroid assemblages in terms of the distribution and diversity patterns at three different environmental regimes and depths in the Antarctic Peninsula. In the second chapter we assessed the health status of Antarctic gorgonian assemblages in a pristine and remote area in the southernmost part of the Weddell Sea continental shelf. In the third chapter we compared the performance of two sampling gears by assessing quantitative data on the continental shelf of three oceanographically very distinct regions in Antarctic Peninsula. Finally in the fourth chapter we tried to understand the way in which a gorgonian population affects the diversity of the surrounding megafaunal species, by characterizing gorgonian assemblages dwelling on two very contrasting continental shelves.El conocimiento de la abundancia, los patrones de distribución y la ecología de población de la biodiversidad bentónica antártica ha aumentado considerablemente durante las últimas décadas. La biodiversidad bentónica marina antártica se ha muestreado principalmente en áreas cercanas a las estaciones de investigación y principalmente a poca profundidad desde hace más de 100 años utilizando una variedad de métodos de muestreo, incluidos trineos o redes de arrastre bentónicos, cada uno de los cuales se dirige a una comunidad o hábitat en particular. Los recientes avances tecnológicos y una mayor disponibilidad de vehículos operados a distancia (ROV), sumergibles tripulados y aparatos de muestreo equipados con videocámara han aumentado significativamente la accesibilidad a las plataformas continentales, taludes continentales, cañones submarinos y montañas submarinas, lo que permite la observación directa y el estudio cuantitativo de comunidades megabentónicas sin ningún impacto en la comunidad misma. Debido al alto coste y la compleja logística de estos muestreos, particularmente en la Antártida, los estudios que se generan a menudo se limitan a un solo método de muestreo biológico. Los resultados de los estudios de biodiversidad se utilizan para una variedad de propósitos, que incluyen taxonomía, ecología trófica, tasas de crecimiento, ecología reproductiva, evaluaciones de impacto ambiental y modelos predictivos, todos los cuales sustentan la gestión adecuada de los recursos marinos. Sin embargo, se desconoce la generalidad de los patrones de biodiversidad marina que se pueden identificar entre los diferentes métodos de muestreo. Esta es una de las razones por las que se necesitan más estudios comparativos para comprender mejor los patrones y procesos de los ecosistemas en las regiones antárticas en un contexto de escenario de cambio climático. Las principales regiones de la plataforma antártica parecen estar experimentando un cambio climático rápido, como el calentamiento en la Península Antártica en las últimas décadas. Dicho cambio climático afectará a los ecosistemas bentónicos a través de cambios en el acoplamiento bento-pelágico. Para estos motivos esta tesis tiene como objetivo general comprender la distribución y el papel ecológico que tienen los organismos bentónicos sobre el ecosistema bentónico de la plataforma continental antártica. Esta tesis incluye cuatro capítulos En el primer capítulo se investigan las asociaciones de ofiuras en términos de patrones de distribución y diversidad en tres regímenes ambientales y profundidades diferentes en la Península Antártica. En el segundo capítulo se evalúa el estado de salud de las poplaciones de gorgonias antárticas en un área prístina y remota en la parte más meridional de la plataforma continental del mar de Weddell. En el tercer capítulo se compara el rendimiento de dos artes de muestreo mediante la evaluación de datos cuantitativos en la plataforma continental de tres regiones oceanográficamente muy distintas en la Península Antártica. Finalmente, en el cuarto capítulo se trata de entender la forma en que una población de gorgonias afecta la diversidad de las especies de megafauna asociadas, caracterizando conjuntamente dos poblaciones de gorgonias que habitan en dos plataformas continentales muy diferentes.
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Ward, Richard Miles Peary. "Behavioral responses of lynx to declining snowshoe hare abundance." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25065.
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The behavioral responses of lynx (Lynx canadensis) to declines in snowshoe hare (Lepus americanus) abundance were examined in the southwestern Yukon. Between April 1982 and June 1984 11 lynx were radio-tagged and monitored within and near the Kluane Game Sanctuary. Lynx mean home range size increased from 13.2 to 39.2 km² concurrent with a decline in snowshoe hare abundance from 14.7 to 0.2 hares/ha. Below about 0.5 hares/ha several lynx abandoned their home ranges and became nomadic, although they remained within the general study area. Track transects through areas known to have different snowshoe hare densities indicated that, lynx concentrated their foraging efforts in areas of relatively high snowshoe hare abundance. Lynx abandoned these areas after hare abundance declined. Lynx foraging effort in terms of distance travelled per day showed a curvilinear relationship to snowshoe hare abundance. Straight-line daily travel distance remained constant at 2.2 to 2.7 km/day above 1.0 hare/ha. Below 1.0 hares/ha, straight-line daily travel distances increased rapidly, reaching 5.5 km/day at 0.2 hares/ha. Three of 7 radio-tagged lynx dispersed 250 km or more from the study area during the period of rapid decline in hare abundance in 1982. No similar long distance dispersal was recorded after hare densities stabilized at less than 1.0 hares/ha. Trapping mortality was responsible for the loss of 7 of 9 radio-tagged lynx that travelled outside the game sanctuary. One lynx died, and is believed to have starved, during the winter or spring of 1984. The high rate of trapping mortality outside the game sanctuary suggests that refugia in wilderness areas are important in maintaining lynx populations during periods of low recruitment.Science, Faculty of
Zoology, Department of
Graduate
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Tzaras, Aspasia. "The factors controlling heterotrophic flagellate abundance in temperate lakes." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/10361.
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The "microbial loop" of aquatic systems consists of picoplankton (heterotrophic and photosynthetic), nanoflagellates (heterotrophic and mixotrophic forms), and ciliates. Heterotrophic flagellates (HNAN) are considered to be the principal grazers of both photosynthetic picoplankton (PICO) and heterotrophic bacteria (HBAC). The factors controlling PICO and HBAC abundances have been studied extensively. However, the factors which regulate HNAN remain less clear. An experimental study was conducted to examine the effects of nutrients and planktivorous fish additions on HNAN in freshwater systems using large enclosures (8m in diameter) installed at both 4 m and 11 m depths in a small oligotrophic lake. In addition to obligate heterotrophs, mixotrophic flagellates (MIXO) were also examined as were their prey, HBAC and PICO. Experimental results did not demonstrate that increases in nutrient levels would lead to increases in HNAN as current empirical models imply. The relationship between HBAC and HNAN was therefore examined within the range of trophy manipulated in the enclosures. A lake survey was conducted in dimictic lakes in Ontario and Western Quebec. (Abstract shortened by UMI.)
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Simpson, Jeffrey David. "Stellar elemental abundance determination using a Fabry-Pérot Interferometer." Thesis, University of Canterbury. Department of Physics and Astronomy, 2009. http://hdl.handle.net/10092/2684.
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The Fabry-Pérot interferometer (FPI) was investigated as a potential tool for determining stellar elemental abundances. The FPI is a tunable narrow-band filter that makes it possible to obtain hundreds of stellar spectra simultaneously without the overhead associated with other multi-object spectroscopy techniques. This thesis used simulations and previously acquired data to investigate the FPI and develop data reduction techniques. Using observations of a CaII spectral line, an algorithm was created for fitting a Voigt profile to the spectrum segments. The values for radial velocity & equivalent width were compared to the values found by the group who supplied the data and found to agree well for the radial velocity values but there was some definite scatter in the equivalent width. These differences are attributed to different placement of the continuum level in the spectra. This curve-fitting script was modified to allow the fitting of synthetic spectra to simulated data. In this way it was possible to investigate how precise the abundance determination will be using the Robert Stobie Spectrograph's FPI mode. Large simulations showed that it will be possible to determine abundances to uncertainties of ±0.1 dex. This is an excellent result and should mean that future work using the FPI will give the results desired for large-scale s-process elemental abundance determination in globular cluster stars.
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Destun, Krystofer J. "Mapping stream fish distribution and abundance from riparian vegetation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ35882.pdf.
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Yang, Jeng-Feng. "Motor learning and adaptation the role of motor abundance /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 216 p, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3247585.
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Jensen, Adam G. "Updated interstellar abundance studies and implications for dust models." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3256457.
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White, T. C. R. White T. C. R. "Role of nitrogen in limiting the abundance of animals /." Title page, contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09ACD/09acdt588.pdf.
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Thesis (D.Sc.) -- University of Adelaide, Dept. of Applied and Molecular Ecology, 1999.Copy of his monograph "The inadequate environment : nitrogen and the abundance of animals" in back pocket. Includes bibliographic references.
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Nishioka, Shuichiro. "Technology, productivity and knowledge in the factor abundance model." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3273684.
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Johansson, Ulf. "Stream channelization effects on fish abundance and species composition." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-97292.
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Streams are important habitats, providing shelter and feeding opportunities for a wide range of organisms. The species depending on running waters includes a wide array of fish species, using these waters for their whole or parts of their lifecycle. Streams are also the subject of different anthropogenic impact, e.g. hydropower development. Hydropower development usually means lost connectivity, altered flow regimes and channelization. Channelization is one of the major factors causing stream habitat loss and degradation and thereby a threat to biodiversity of running waters. In the present study, the ecological impact of channelization on the fish fauna along a gradient of channelization severeness was examined. Besides channelization, stream velocity and depth were taken in to account. The study was carried out in two adjacent nemoboreal streams, Gavleån and Testeboån. The study was conducted between the 6th of June and the 10th of October 2012 at 15 sites. Sites were selected using historical maps and field observations and graded 0-3 depending on the degree of channelization. Fish community were sampled with, Nordic multi-mesh Stream Survey Net (NSSN). In all, 1.465 fish were captured, representing 15 species and seven families. The sites differed in species richness, abundance and proportion of individuals. Based on the results from rarefaction curves and ANOVA, channelization was found to be the main factor affecting the fish biota, both in abundance as well as species richness and composition. In general the rheophilic species declined along the gradient of increasing channelization severeness, while limnophilic species increased
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Morin, Antoine. "Estimation and prediction of black fly abundance and productivity." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75447.
Full textAbstract:
Sampling and analytical techniques to estimate abundance and productivity of stream invertebrates are examined for their precision and accuracy, and then utilized to develop empirical models of sampling variability, abundance, and growth rates of overwintering larvae of black flies (Diptera: Simuliidae). Sampling variability of density estimates of stream benthos increases with mean density, and decreases with sampler size. Artificial substrates do not consistently reduce sampling variability, and introduce variable bias in estimates of simuliid density. Growth rates of overwintering simuliids are mainly a function of their body size, but available data show that growth rates also increase with water temperature. Biomass of overwintering simuliids in lake outlets in Southern Quebec is positively related to chlorophyll concentration and current velocity, and negatively related to distance from the lake, water depth, and periphyton biomass. Computer simulations show that published methods fail to produce reliable confidence intervals for estimates of secondary production for highly aggregated populations, and a reliable method, based on the Bootstrap procedure and the Allen curve, is presented.
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Feldman, Richard. "Toward a theory of abundance at large spatial scales." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104707.
Full textAbstract:
Fundamentally, ecology is the study of the diversity, distribution, and abundance of organisms. Recent advances in technology coupled with expanding research goals have lead to studies of how the first two of these properties vary over large spatial scales. There has been relatively few cases documenting large scale spatial variation in abundance and very little theoretical development explaining such variation. Yet a general pattern exists: a species is abundant in very few places and rare in most places in its range. Current theory suggests that such a pattern of abundance reflects underlying spatial variation in the environment. In this thesis, I used observational, experimental, theoretical, and statistical approaches to test the type of environmental variation and how such environmental variation combines with interspecific competition to generate spatial variation in abundance. For two species of hummingbirds, I found that different environmental factors related to abundance than to occupancy. Interspecific competition altered spatial variation in abundance in different ways depending on the niche differences among competing species. Interspecific competition also mediated the effect of the environment on abundance by influencing the relative costs and benefits of different hummingbird foraging strategies. I also found that abundance data can be used to predict species' response to climate change because statistical models minimize the noise inherent in abundance datasets. Despite my findings, a theory of abundance is still in its infancy. It is not known whether there is generality in the number and identity of large scale environmental gradients that affect abundance. Similarly, more work needs to be done connecting the small scale interplay between environment, species traits, behaviour, and competition to a broader geographic context. There are also dispersal and non-niche based approaches to spatial variation in abundance that need to be reconciled with current theory. In this way, a more general theory relating macroevolutionary dynamics to macroecological patterns can be developed.L'écologie est l'étude de la diversité, des distributions et des abondances des organismes vivants. Les avancées technologiques récentes couplées à une expansion des objets de recherche ont permis à une étude approfondie de la variation de ces deux premières propriétés sur de très grandes échelles spatiales. Les variations en abondance sont, quant à elles, peu documentées aux grandes échelles spatiales et les développements théoriques correspondant restent limités. Il existe pourtant un pattern prévalent : une espèce donnée est généralement abondante dans une partie extrêmement réduite de sa zone géographique et rare partout ailleurs. Cette observation est aujourd'hui communément expliquée par une variation environnementale sous-jacente. Cette thèse s'appuie sur des approches à la fois empiriques et expérimentales, statistiques et théoriques pour tester le type de variation environnementale ainsi que les interactions entre environnement et compétition interspécifique pouvant générer les variations spatiales en abondances observées. Il est montré que présence-absence et abondance sont affectées par des facteurs environnementaux distincts. Il apparaît en outre que l'effet de la compétition interspécifique dépend des différences de niches entre espèces et module l'impact de l'environnement sur l'abondance en modifiant des coûts et bénéfices relatifs des différentes stratégies d'acquisition des ressources. Finalement, la possibilité de prédire les réponses aux changements climatiques grâce aux données d'abondance et à des modèles statistiques minimisant le bruit inhérent à ce type de données est démontrée. Pour autant, une véritable théorie des distributions d'abondance reste à développer. Le nombre, et a fortiori l'identité, des gradients environnements affectant les abondances à grande échelle spatiale sont encore mal connus. Un effort de recherche considérable est ainsi nécessaire pour améliorer la compréhension du lien entre phénomènes locaux, dont l'interaction entre environnement, traits, comportement et compétition, et patterns à grandes échelles. Par ailleurs, l'unification entre approches basées sur la dispersion, négligeant les différences de niches, avec la théorie actuelle doit encore être accomplie pour qu'une véritable théorie générale des dynamiques macro-évolutive et patterns macro-écologiques puisse voir le jour.
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Baldridge, Elita. "A data-intensive assessment of the species-abundance distribution." Thesis, Utah State University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3700756.
Full textAbstract:
The hollow curve species abundance distribution describes the pattern of large numbers of rare species and a small number of common species in a community. The species abundance distribution is one of the most ubiquitous patterns in nature and many models have been proposed to explain the mechanisms that generate this pattern. While there have been numerous comparisons of species abundance distribution models, most of these comparisons only use a small subset of available models, focus on a single ecosystem or taxonomic group, and fail to use the most appropriate statistical methods. This makes it difficult to draw general conclusions about which, if any, models provide the best empirical fit to species abundance distributions. I compiled data from the literature to significantly expand the available data for underrepresented taxonomic groups, and combined this with other macroecological datasets to perform comprehensive model comparisons for the species abundance distribution. A multiple model comparison showed that most available models for the species abundance distribution fit the data equivalently well across a diverse array of ecosystems and taxonomic groups. In addition, a targeted comparison of the species abundance distribution predicted by a major ecological theory, the unified neutral theory of biodiversity (neutral theory), against a non-neutral model of species abundance, demonstrates that it is difficult to distinguish between these two classes of theory based on patterns in the species abundance distribution. In concert, these studies call into question the potential for using the species abundance distribution to infer the processes operating in ecological systems.