932 resultados para Challenge posed by omics data to compositional analysis-paucity of independent samples (n)


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The number of remote sensing platforms and sensors rises almost every year, yet much work on the interpretation of land cover is still carried out using either single images or images from the same source taken at different dates. Two questions could be asked of this proliferation of images: can the information contained in different scenes be used to improve the classification accuracy and, what is the best way to combine the different imagery? Two of these multiple image sources are MODIS on the Terra platform and ETM+ on board Landsat7, which are suitably complementary. Daily MODIS images with 36 spectral bands in 250-1000 m spatial resolution and seven spectral bands of ETM+ with 30m and 16 days spatial and temporal resolution respectively are available. In the UK, cloud cover may mean that only a few ETM+ scenes may be available for any particular year and these may not be at the time of year of most interest. The MODIS data may provide information on land cover over the growing season, such as harvest dates, that is not present in the ETM+ data. Therefore, the primary objective of this work is to develop a methodology for the integration of medium spatial resolution Landsat ETM+ image, with multi-temporal, multi-spectral, low-resolution MODIS \Terra images, with the aim of improving the classification of agricultural land. Additionally other data may also be incorporated such as field boundaries from existing maps. When classifying agricultural land cover of the type seen in the UK, where crops are largely sown in homogenous fields with clear and often mapped boundaries, the classification is greatly improved using the mapped polygons and utilising the classification of the polygon as a whole as an apriori probability in classifying each individual pixel using a Bayesian approach. When dealing with multiple images from different platforms and dates it is highly unlikely that the pixels will be exactly co-registered and these pixels will contain a mixture of different real world land covers. Similarly the different atmospheric conditions prevailing during the different days will mean that the same emission from the ground will give rise to different sensor reception. Therefore, a method is presented with a model of the instantaneous field of view and atmospheric effects to enable different remote sensed data sources to be integrated.

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The authors would like to thank the College of Life Sciences of Aberdeen University and Marine Scotland Science which funded CP's PhD project. Skate tagging experiments were undertaken as part of Scottish Government project SP004. We thank Ian Burrett for help in catching the fish and the other fishermen and anglers who returned tags. We thank José Manuel Gonzalez-Irusta for extracting and making available the environmental layers used as environmental covariates in the environmental suitability modelling procedure. We also thank Jason Matthiopoulos for insightful suggestions on habitat utilization metrics as well as Stephen C.F. Palmer, and three anonymous reviewers for useful suggestions to improve the clarity and quality of the manuscript.

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Tässä työssä perehdytään soodakattiloiden vesikiertomallin rakentamiseen. Työn päätavoitteena on kehittää simulointimallia varten taulukkolaskentapohja, jonka avulla soodakattilan lämpövuotietoja on yksinkertaista ja nopeaa käsitellä ja siirtää Apros 6 -simulointiohjelmaan. Lisäksi tarkoituksena on pyrkiä automatisoimaan työvaiheet mahdollisimman pitkälle, jolloin vesikiertolaskennan tekeminen yksinkertaistuisi, yhtenäistyisi ja tarkentuisi. Tämä on mahdollista Excel- makrojen ja Apros 6:n uusien toimintojen avulla. Apros 6:ssa on nyt mahdollista hyödyntää SCL- komentotiedostoja, joiden avulla sujuva tiedonsiirto Aproksen ja Excelin välillä vodaan toteuttaa. Vesikiertolaskentaan käytettävän datan käsittely on aikaisemmin ollut työlästä ja sen tarkkuus on pitkälti riippunut mallintajasta. Tässä diplomityössä päästään hyödyntämään uusimpia ja realistisempia soodakattiloiden CFD- malleja, joiden avulla pystytään luomaan aikaisempaa tarkemmat lämpövuojakaumat soodakattilan lämpöpinnoille. Tämä muutos parantaa vesikiertolaskennan tarkkuutta. Työn kokeellisessa osassa uutta Excel laskentatyökalua ja uusia lämpövuoarvoja testataan käytännössä. Eräs vanha Apros- vesikiertomalli päivitetään uusilla lämpövuoarvoilla ja sen rakenteeseen tehdään muutoksia tarkkuuden parantamiseksi. Uuden mallin toimivuutta testataan myös 115 %:n kapasiteetilla ja tutkitaan kuinka kyseinen vesikiertopiiri reagoi suurempaan lämpötehoon. Näitä kolmea eri tilannetta vertaillaan toisiinsa ja tarkastellaan eroavaisuuksia niiden vesi-höyrypiireissä.

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The design of randomized controlled trials entails decisions that have economic as well as statistical implications. In particular, the choice of an individual or cluster randomization design may affect the cost of achieving the desired level of power, other things being equal. Furthermore, if cluster randomization is chosen, the researcher must decide how to balance the number of clusters, or sites, and the size of each site. This article investigates these interrelated statistical and economic issues. Its principal purpose is to elucidate the statistical and economic trade-offs to assist researchers to employ randomized controlled trials that have desired economic, as well as statistical, properties. (C) 2003 Elsevier Inc. All rights reserved.

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A microbiopsy system for fast excision and transfer of biological specimens from donor to high-pressure freezer was developed. With a modified, commercially available, Promag 1.2 biopsy gun, tissue samples can be excised with a size small enough (0.6 mm x 1.2 mm x 0.3 mm) to be easily transferred into a newly designed specimen platelet. A self-made transfer unit allows fast transfer of the specimen from the needle into the specimen platelet. The platelet is then fixed in a commercially available specimen holder of a high-pressure freezing machine (EM PACT, Leica Microsystems, Vienna, Austria) and frozen therein. The time required by a well-instructed (but not experienced) person to execute all steps is in the range of half a minute. This period is considered short enough to maintain the excised tissue pieces close to their native state. We show that a range of animal tissues (liver, brain, kidney and muscle) are well preserved. To prove the quality of freezing achieved with the system, we show vitrified ivy leaves high-pressure frozen in the new specimen platelet.

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Soil aggregation is an index of soil structure measured by mean weight diameter (MWD) or scaling factors often interpreted as fragmentation fractal dimensions (D-f). However, the MWD provides a biased estimate of soil aggregation due to spurious correlations among aggregate-size fractions and scale-dependency. The scale-invariant D-f is based on weak assumptions to allow particle counts and sensitive to the selection of the fractal domain, and may frequently exceed a value of 3, implying that D-f is a biased estimate of aggregation. Aggregation indices based on mass may be computed without bias using compositional analysis techniques. Our objective was to elaborate compositional indices of soil aggregation and to compare them to MWD and D-f using a published dataset describing the effect of 7 cropping systems on aggregation. Six aggregate-size fractions were arranged into a sequence of D-1 balances of building blocks that portray the process of soil aggregation. Isometric log-ratios (ilrs) are scale-invariant and orthogonal log contrasts or balances that possess the Euclidean geometry necessary to compute a distance between any two aggregation states, known as the Aitchison distance (A(x,y)). Close correlations (r>0.98) were observed between MWD, D-f, and the ilr when contrasting large and small aggregate sizes. Several unbiased embedded ilrs can characterize the heterogeneous nature of soil aggregates and be related to soil properties or functions. Soil bulk density and penetrater resistance were closely related to A(x,y) with reference to bare fallow. The A(x,y) is easy to implement as unbiased index of soil aggregation using standard sieving methods and may allow comparisons between studies. (C) 2012 Elsevier B.V. All rights reserved.

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In recent years, agronomical researchers began to cultivate several olive varieties in different regions of Brazil to produce virgin olive oil (VOO). Because there has been no reported data regarding the phenolic profile of the first Brazilian VOO, the aim of this work was to determine phenolic contents of these samples using rapid-resolution liquid chromatography coupled to electrospray ionisation time-of-flight mass spectrometry. 25 VOO samples from Arbequina, Koroneiki, Arbosana, Grappolo, Manzanilla, Coratina, Frantoio and MGS Mariense varieties from three different Brazilian states and two crops were analysed. It was possible to quantify 19 phenolic compounds belonging to different classes. The results indicated that Brazilian VOOs have high total phenolic content because the values were comparable with those from high-quality VOOs produced in other countries. VOOs from Coratina, Arbosana and Grappolo presented the highest total phenolic content. These data will be useful in the development and improvement of Brazilian VOO.

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Rapid adaptation and tolerance is a phenomenon experienced by a variety of organisms typically because of new and harsh environments. Mimulus guttatus, a plant commonly seen on the west coast of the United States, is a prime example as it has rapidly evolved to soil contamination by copper due to mining in California in the last 150 years. There have been two hypotheses posed by researchers as to the genetic basis of how organisms have evolved so quickly which I set out to study: 1) There is a low frequency of tolerant genotypes in the ancestral population otherwise known as standing variation or 2) new mutations occurred once exposed to a new environment. In the past, researchers found it difficult to distinguish between the two because they lacked the technology we have today for DNA analysis. I used four different populations of M. guttatus from varying locations in order to address which hypothesis was valid. I conducted both survival assays of these populations and DNA analysis of known tolerant and non-tolerant lines using a copper oxidase gene. I found that there was at least some degree of tolerance in all populations in the survival assays, supporting the hypothesis of standing variation. I also found patterns within DNA analysis suggesting the copper oxidase gene would be useful for further study to verify the standing variation hypothesis. The results from this experiment helps in understanding rapid evolution not just in the context of soil contamination by metals but also ties back to why an alarming number of species are not able to adapt to our constantly changing world.

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BACKGROUND: In 2011, a patient was admitted to our hospital with acute schistosomiasis after having returned from Madagascar and having bathed at the Lily waterfalls. On the basis of this patient's indication, infection was suspected in 41 other subjects. This study investigated (1) the knowledge of the travelers about the risks of schistosomiasis and their related behavior to evaluate the appropriateness of prevention messages and (2) the diagnostic workup of symptomatic travelers by general practitioners to evaluate medical care of travelers with a history of freshwater exposure in tropical areas. METHODS: A questionnaire was sent to the 42 travelers with potential exposure to schistosomiasis. It focused on pre-travel knowledge of the disease, bathing conditions, clinical presentation, first suspected diagnosis, and treatment. RESULTS: Of the 42 questionnaires, 40 (95%) were returned, among which 37 travelers (92%) reported an exposure to freshwater, and 18 (45%) were aware of the risk of schistosomiasis. Among these latter subjects, 16 (89%) still reported an exposure to freshwater. Serology was positive in 28 (78%) of 36 exposed subjects at least 3 months after exposure. Of the 28 infected travelers, 23 (82%) exhibited symptoms and 16 (70%) consulted their general practitioner before the information about the outbreak had spread, but none of these patients had a serology for schistosomiasis done during the first consultation. CONCLUSIONS: The usual prevention message of avoiding freshwater contact when traveling in tropical regions had no impact on the behavior of these travelers, who still went swimming at the Lily waterfalls. This prevention message should, therefore, be either modified or abandoned. The clinical presentation of acute schistosomiasis is often misleading. General practitioners should at least request an eosinophil count, when confronted with a returning traveler with fever. If eosinophilia is detected, it should prompt the search for a parasitic disease.

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In this work is presented and tested (for 106 adducts, mainly of the zinc group halides) two empirical equations supported in TG data to estimate the value of the metal-ligand bond dissociation enthalpy for adducts: <D> (M-O) = t i / g if t i < 420 K and <D> (M-O) = (t i / g ) - 7,75 . 10-2 . t i if t i > 420 K. In this empirical equations, t i is the thermodynamic temperature of the beginning of the thermal decomposition of the adduct, as determined by thermogravimetry, andg is a constant factor that is function of the metal halide considered and of the number of ligands, but is not dependant of the ligand itself. To half of the tested adducts the difference between experimental and calculated values was less than 5%. To about 80% of the tested adducts, the difference between the experimental (calorimetric) and the calculated (using the proposed equations) values are less than 15%.

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The main objective of this thesis is to show that plate strips subjected to transverse line loads can be analysed by using the beam on elastic foundation (BEF) approach. It is shown that the elastic behaviour of both the centre line section of a semi infinite plate supported along two edges, and the free edge of a cantilever plate strip can be accurately predicted by calculations based on the two parameter BEF theory. The transverse bending stiffness of the plate strip forms the foundation. The foundation modulus is shown, mathematically and physically, to be the zero order term of the fourth order differential equation governing the behaviour of BEF, whereas the torsion rigidity of the plate acts like pre tension in the second order term. Direct equivalence is obtained for harmonic line loading by comparing the differential equations of Levy's method (a simply supported plate) with the BEF method. By equating the second and zero order terms of the semi infinite BEF model for each harmonic component, two parameters are obtained for a simply supported plate of width B: the characteristic length, 1/ λ, and the normalized sum, n, being the effect of axial loading and stiffening resulting from the torsion stiffness, nlin. This procedure gives the following result for the first mode when a uniaxial stress field was assumed (ν = 0): 1/λ = √2B/π and nlin = 1. For constant line loading, which is the superimposition of harmonic components, slightly differing foundation parameters are obtained when the maximum deflection and bending moment values of the theoretical plate, with v = 0, and BEF analysis solutions are equated: 1 /λ= 1.47B/π and nlin. = 0.59 for a simply supported plate; and 1/λ = 0.99B/π and nlin = 0.25 for a fixed plate. The BEF parameters of the plate strip with a free edge are determined based solely on finite element analysis (FEA) results: 1/λ = 1.29B/π and nlin. = 0.65, where B is the double width of the cantilever plate strip. The stress biaxial, v > 0, is shown not to affect the values of the BEF parameters significantly the result of the geometric nonlinearity caused by in plane, axial and biaxial loading is studied theoretically by comparing the differential equations of Levy's method with the BEF approach. The BEF model is generalised to take into account the elastic rotation stiffness of the longitudinal edges. Finally, formulae are presented that take into account the effect of Poisson's ratio, and geometric non linearity, on bending behaviour resulting from axial and transverse inplane loading. It is also shown that the BEF parameters of the semi infinite model are valid for linear elastic analysis of a plate strip of finite length. The BEF model was verified by applying it to the analysis of bending stresses caused by misalignments in a laboratory test panel. In summary, it can be concluded that the advantages of the BEF theory are that it is a simple tool, and that it is accurate enough for specific stress analysis of semi infinite and finite plate bending problems.

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Cytomegalovirus (CMV) infection is associated with significant morbidity and mortality in transplant recipients. Resistance against ganciclovir is increasingly observed. According to current guidelines, direct drug resistance testing is not always performed due to high costs and work effort, even when resistance is suspected.

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In the present study, proxy data concerning changes in atmospheric CO2 and climatic conditions from the Late Eocene to the Early Miocene were acquired by applying palaeobotanical methods. Fossil floras from 10 well-documented locations in Saxony, Germany, were investigated with respect to (1) stomatal density/index of fossil leaves from three different taxa (Eotrigonobalanus furcinervis, Laurophyllum pseudoprinceps and Laurophyllum acutimontanum), (2) the coexistence approach (CA) based on nearest living relatives (NLR) and (3) leaf margin analysis (LMA). Whereas the results of approach (1) indicate changes in atmospheric CO2 concentration, approaches (2) and (3) provide climate data. The results of the analysis of stomatal parameters indicate that the atmospheric CO2 concentration was higher during the Late Eocene than during the Early Oligocene and increased towards the Late Oligocene. A lower atmospheric pCO2 level after the Late Eocene is also suggested by an increase in marine palaeoproductivity at this time. From the Late Oligocene onwards, no changes in atmospheric CO2 concentration can be detected with the present data. For the considered sites, the results of the coexistence approach and of the leaf margin analysis document a significant cooling event from the Late Eocene to the Early Oligocene. The pCO2 decrease from the Late Eocene to the Early Oligocene indicated by the stomatal data raised in this study was thus coupled to a temperature decrease which is reflected by the present datasets. From the Early Oligocene onwards, however, no further fundamental climate change can be inferred for the considered locations. The pCO2 increase from the Early Oligocene to the Late Oligocene, which is indicated by the present data, is thus not accompanied by a climate change at the considered sites. A warming event during the Late Oligocene is, however, recorded by marine climate archives. According to the present data, no change in pCO2 occurred during the cooling event at the Oligocene/Miocene boundary, which is also indicated by marine data. The quality and validity of stomatal parameters as sensors for atmospheric CO2 concentration are discussed.