952 resultados para log-ratio analysis
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The known moss flora of Terra Nova National Park, eastern Newfoundland, comp~ises 210 species. Eighty-two percent of the moss species occurring in Terra Nova are widespread or widespread-sporadic in Newfoundland. Other Newfoundland distributional elements present in the Terra Nova moss flora are the northwestern, southern, southeastern, and disjunct elements, but four of the mosses occurring in Terra Nova appear to belong to a previously unrecognized northeastern element of the Newfoundland flora. The majority (70.9%) of Terra Nova's mosses are of boreal affinity and are widely distributed in the North American coniferous forest belt. An additional 10.5 percent of the Terra Nova mosses are cosmopolitan while 9.5 percent are temperate and 4.8 percent are arctic-montane species. The remaining 4.3 percent of the mosses are of montane affinity, and disjunct between eastern and western North America. In Terra Nova, temperate species at their northern limit are concentrated in balsam fir stands, while arctic-montane species are restricted to exposed cliffs, scree slopes, and coastal exposures. Montane species are largely confined to exposed or freshwater habitats. Inability to tolerate high summer temperatures limits the distributions of both arctic-montane and montane species. In Terra Nova, species of differing phytogeographic affinities co-occur on cliffs and scree slopes. The microhabitat relationships of five selected species from such habitats were evaluated by Discriminant Functions Analysis and Multiple Regression Analysis. The five mosses have distinct and different microhabitats on cliffs and scree slopes in Terra Nova, and abundance of all but one is associated with variation in at least one microhabitat variable. Micro-distribution of Grimmia torquata, an arctic-montane species at its southern limit, appears to be deterJ]lined by sensitivity to high summer temperatures. Both southern mosses at their northern limit (Aulacomnium androgynum, Isothecium myosuroides) appear to be limited by water availability and, possibly, by low winter temperatures. The two species whose distributions extend both north and south or the study area (Encalypta procera, Eurhynchium pulchellum) show no clear relationship with microclimate. Dispersal factors have played a significant role in the development of the Terra Nova moss flora. Compared to the most likely colonizing source (i .e. the rest of the island of Newfoundland), species with small diaspores have colonized the study area to a proportionately much greater extent than have species with large diaspores. Hierarchical log-linear analysis indicates that this is so for all affinity groups present in Terra Nova. The apparent dispersal effects emphasize the comparatively recent glaciation of the area, and may also have been enhanced by anthropogenic influences. The restriction of some species to specific habitats, or to narrowly defined microhabitats, appears to strengthen selection for easily dispersed taxa.
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This study contributes to the literature on gravity analysis by explicitly incorporating both most favored nation (MFN) rates and regional trade agreement (RTA) rates. Our gravity equation considers the fact that all exporters do not necessarily utilize RTA schemes, even when exporting to their RTA partners. We apply the tariff line–level data on worldwide trade to this gravity equation. As a result, we find a significantly negative coefficient for the (log) ratio of RTA rates to MFN rates. From the quantitative point of view, we show that in the first year of the Japan–Australia Economic Partnership (i.e., 2015), exports from Australia to Japan are expected to increase by 6% compared with the exports in 2014. Furthermore, it is shown that, based on the subsequent reduction in RTA rates, the magnitude of the trade-creation effect through tariff reductions gradually rises over time.
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The complexity of modern geochemical data sets is increasing in several aspects (number of available samples, number of elements measured, number of matrices analysed, geological-environmental variability covered, etc), hence it is becoming increasingly necessary to apply statistical methods to elucidate their structure. This paper presents an exploratory analysis of one such complex data set, the Tellus geochemical soil survey of Northern Ireland (NI). This exploratory analysis is based on one of the most fundamental exploratory tools, principal component analysis (PCA) and its graphical representation as a biplot, albeit in several variations: the set of elements included (only major oxides vs. all observed elements), the prior transformation applied to the data (none, a standardization or a logratio transformation) and the way the covariance matrix between components is estimated (classical estimation vs. robust estimation). Results show that a log-ratio PCA (robust or classical) of all available elements is the most powerful exploratory setting, providing the following insights: the first two processes controlling the whole geochemical variation in NI soils are peat coverage and a contrast between “mafic” and “felsic” background lithologies; peat covered areas are detected as outliers by a robust analysis, and can be then filtered out if required for further modelling; and peat coverage intensity can be quantified with the %Br in the subcomposition (Br, Rb, Ni).
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La pomme de terre est l’une des cultures les plus exigeantes en engrais et elle se cultive généralement sur des sols légers ayant de faibles réserves en N, P, K, Ca et Mg. Ces cinq éléments sont essentiels à la croissance des plants, à l’atteinte des bons rendements et à l’obtention de bonne qualité des tubercules de pomme de terre à la récolte et à l’entreposage. La recherche d’un équilibre entre ces cinq éléments constitue l’un des défis de pratiques agricoles de précision. La collecte de 168 échantillons de feuilles de pommes de terre selon une grille de 40 m × 60 m (densité d’échantillonnage de 2,9 échantillons ha-1) dans un champ de pommes de terre de 54 ha au Saguenay-Lac-Saint-Jean et la détermination de leur teneur en N, P, K, Ca et Mg au stade début floraison, jumelée à une lecture de l’indice de chlorophylle avec SPAD-502, a permis d’établir les faits suivants : parmi tous les indicateurs de diagnostic foliaire selon les 3 approches connues VMC, DRIS et CND, le contraste logarithmique entre les deux éléments nutritifs type anioniques (N et P) vs les trois éléments type cationiques (K, Ca et Mg), noté ilr (log ratio isométrique) du coda (Compositional Data Analysis) est l’indicateur le plus fortement relié à la lecture SPAD-502 (r=0,77). L’étude géostatique spatiale appliquée au Coda a montré une grande similitude entre le CND-ilr (anions vs cations) et la lecture SPAD-502. Ce CND-ilr devrait être interprété en termes de fertilisation de démarrage (N+P), en lien avec les apports des cations sous forme d’engrais (K, Ca et Mg) ou d’amendement (Ca et Mg).
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Cotton is the most abundant natural fiber in the world. Many countries are involved in the growing, importation, exportation and production of this commodity. Paper documentation claiming geographic origin is the current method employed at U.S. ports for identifying cotton sources and enforcing tariffs. Because customs documentation can be easily falsified, it is necessary to develop a robust method for authenticating or refuting the source of the cotton commodities. This work presents, for the first time, a comprehensive approach to the chemical characterization of unprocessed cotton in order to provide an independent tool to establish geographic origin. Elemental and stable isotope ratio analysis of unprocessed cotton provides a means to increase the ability to distinguish cotton in addition to any physical and morphological examinations that could be, and are currently performed. Elemental analysis has been conducted using LA-ICP-MS, LA-ICP-OES and LIBS in order to offer a direct comparison of the analytical performance of each technique and determine the utility of each technique for this purpose. Multivariate predictive modeling approaches are used to determine the potential of elemental and stable isotopic information to aide in the geographic provenancing of unprocessed cotton of both domestic and foreign origin. These approaches assess the stability of the profiles to temporal and spatial variation to determine the feasibility of this application. This dissertation also evaluates plasma conditions and ablation processes so as to improve the quality of analytical measurements made using atomic emission spectroscopy techniques. These interactions, in LIBS particularly, are assessed to determine any potential simplification of the instrumental design and method development phases. This is accomplished through the analysis of several matrices representing different physical substrates to determine the potential of adopting universal LIBS parameters for 532 nm and 1064 nm LIBS for some important operating parameters. A novel approach to evaluate both ablation processes and plasma conditions using a single measurement was developed and utilized to determine the “useful ablation efficiency” for different materials. The work presented here demonstrates the potential for an a priori prediction of some probable laser parameters important in analytical LIBS measurement.
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It is now widely recognized that translation factors are involved in cancer development and that components of the translation machinery that are deregulated in cancer cells may become targets for cancer therapy. The eukaryotic Release Factor 3 (eRF3) is a GTPase that associates with eRF1 in a complex that mediates translation termination. eRF3a/GSPT1 first exon contains a (GGC)n expansion coding for proteins with different N-terminal extremities. Herein we show that the longer allele (12-GGC) is present in 5.1% (7/137) of the breast cancer patients analysed and is absent in the control population (0/135), corresponding to an increased risk for cancer development, as revealed by Odds Ratio analysis. mRNA quantification suggests that patients with the 12-GGC allele overexpress eRF3a/GSPT1 in tumor tissues relative to the normal adjacent tissues. However, using an in vivo assay for translation termination in HEK293 cells, we do not detect any difference in the activity of the eRF3a proteins encoded by the various eRF3a/GSPT1 alleles. Although the connection between the presence of eRF3a/GSPT1 12-GGC allele and tumorigenesis is still unknown, our data suggest that the presence of the 12-GGC allele provides a potential novel risk marker for various types of cancer.
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics
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PURPOSE: The purposes of this study are to measure the prevalence of premature ejaculation (PE) and erectile dysfunction (ED) among a population of Swiss young men and to assess which factors are associated with these sexual dysfunctions in this age-group. METHODS: For each condition (PE and ED), we performed separate analyses comparing young men suffering from the condition with those who were not. Groups were compared for substance use (tobacco, alcohol, cannabis, other illegal drugs, and medication without a prescription), self-reported body mass index, sexual orientation, physical activity, professional activity, sexual experience (sexual life length and age at first intercourse), depression status, mental health, and physical health in a bivariate analysis. We then used a log-linear analysis to consider all significant variables simultaneously. RESULTS: Prevalence rates for PE and ED were 11% and 30%, respectively. Poor mental health was the only variable to have a direct association with both conditions after controlling for potential confounders. In addition, PE was directly associated with tobacco, illegal drugs, professional activity, and physical activity, whereas ED was directly linked with medication without a prescription, length of sexual life, and physical health. CONCLUSIONS: In Switzerland, one-third of young men suffer from at least one sexual dysfunction. Multiple health-compromising factors are associated with these dysfunctions. These should act as red flags for health professionals to encourage them to take any opportunity to talk about sexuality with their young male patients.
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Nine children surviving severe adult respiratory distress syndrome were studied 0.9 to 4.2 years after the acute illness. They had received artificial ventilation for a mean of 9.4 days, with an Fio2 greater than 0.5 during a mean time of 34 hours and maximal positive end expiratory pressure levels in the range of 8 to 20 cm H2O. Three children had recurrent respiratory symptoms (moderate exertional dyspnea and cough), and two had evidence of fibrosis on chest radiographs. All patients had abnormal lung function; the most prominent findings were ventilation inequalities, as judged by real-time moment ratio analysis of multibreath nitrogen washout curves (abnormal in eight of nine patients) and hypoxemia (seven of nine). Lung volumes were less abnormal; one patient had restrictive and two had obstructive disease. A significant correlation between intensive care measures (Fio2 greater than 0.5 in hours and peak inspiratory plateau pressure) and lung function abnormalities (moment ratio analysis and hypoxemia) was found. A possibly increased susceptibility of the pediatric age group to the primary insult or respiratory therapy of adult respiratory distress syndrome is suggested.
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Is it possible to build predictive models (PMs) of soil particle-size distribution (psd) in a region with complex geology and a young and unstable land-surface? The main objective of this study was to answer this question. A set of 339 soil samples from a small slope catchment in Southern Brazil was used to build PMs of psd in the surface soil layer. Multiple linear regression models were constructed using terrain attributes (elevation, slope, catchment area, convergence index, and topographic wetness index). The PMs explained more than half of the data variance. This performance is similar to (or even better than) that of the conventional soil mapping approach. For some size fractions, the PM performance can reach 70 %. Largest uncertainties were observed in geologically more complex areas. Therefore, significant improvements in the predictions can only be achieved if accurate geological data is made available. Meanwhile, PMs built on terrain attributes are efficient in predicting the particle-size distribution (psd) of soils in regions of complex geology.
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Pro gradu -tutkielma keskittyy OKO:n yritysasiakkaiden luottoriskiluokituksessa käyttämään tunnuslukumalliin. Tutkielman tavoitteena on tutkia, miten suomalaisyritysaineistosta johdettu tunnuslukumalli luokittelee yrityksiä eri tavalla OKO:n nykyiseen malliin verrattuna. Tutkielma rakentuu kirjallisuuteen perustuvasta teoreettisesta viitekehyksestä sekä varsinaisesta empiirisestä tutkimuksesta. Tutkimuksessa käytetään kvantitatiivisia tutkimusmetodeja, joissa aineiston tarkastelun avulla pyritään tekemään järkeistettyjä päätöksiä. Tutkimusaineisto koostuu 4889 tilinpäätöksestä vuosilta 1991-2001, jotka on saatu Etlan 500 suurimman suomalaisyrityksen tilinpäätöstietokannasta. Tutkimuksessa tarkastellaan suomalaisyritysten tunnuslukujen jakautumista viidellä toimialalla sekä kahdessa ajanjaksossa. Toimialakohtaisista tunnuslukujakaumista johdetaan uuden mallin tunnuslukukohtaiset luokkarajat. Uusien luokkarajojen voidaan todeta olevan tunnusluvusta riippuen joko korkeammat tai matalammat kuin nykyisen yhdysvaltalaisaineistoon pohjautuvan tunnuslukumallin luokkarajat. Uuden ja nykyisen tunnuslukumallin antamia luokituksia verrataan 51 case-yrityksen avulla. Tutkimus osoittaa, että uusi tunnuslukumalli luokittelee yrityksiä pääasiassa parempiin tai samoihin luottoriskiluokkiin kuin nykyinen malli. Luokitusmuutoksia esiintyy useammin spekulatiivisen tason yrityksillä kuin investointitason yrityksillä
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Tutkielmassa selvitetään, voiko yrityksen taloudellista menestymistä ennustaa yritystutkimuksen avulla. Tutkielman aineistona on 30 heikon riskiluokan ja 30 hyvän riskiluokan omaavan yrityksen yritystutkimusraporttia. Konkurssista varoittavat tekijät on jaettu varhaisiin ja myöhäisiin varoittajiin. Varhaiset varoittajat liittyvät yrityksen reaaliprosessiin, esimerkkinä huono liikkeenjohto. Myöhäiset varoittajat ovat tilinpäätösanalyysiin perustuvia tunnuslukuja. Tässä tutkielmassa muuttujina käytetään toimitusjohtajan koulutusta, kokemusta, omistusosuutta sekä yrityksen kasvua strategiselta pohjalta ja reaalisesti. Tilinpäätöksen tunnusluvuista käytetään nettotulosta, rahoitustulosta, omavaraisuusastetta ja quick ratiota. Tutkielman perusteella voidaan todeta, että yrityksen taloudellista menestymistä ei voida ennustaa valituilla kvalitatiivisilla muuttujilla, mutta tilinpäätöksen tunnusluvut ennustavat yrityksen menestymistä.
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Tämän kandidaatintutkielman tavoitteena on tutkia Suomessa toimivien kiinteistösijoitusyritysten menestymistä aikavälillä 2007–2014. Tutkimuksen keskiössä ovat erityisesti toimialan suurimpien yritysten suoriutuminen suhteessa pienempiin yrityksiin. Yritysten menestymistä arvioidaan valittujen tunnuslukujen avulla. Tutkimus ajoittuu finanssikriisin, eurokriisin ja taantuman aikaan, jolloin taloudessa tapahtui merkittäviä muutoksia. Kiinteistömarkkinoiden voidaan ajatella olevan paikallisia, jolloin maailmantalouden muutokset eivät ole välttämättä paikallisesti näyttäytyneet yhtä suurina. Tutkielman teoriaosuus esittelee tunnuslukuanalyysimenetelmää sekä valitut neljä tunnuslukua: voittoprosentin, oman pääoman tuottoprosentin, omavaraisuusasteen ja current ration. Lisäksi teoriaosuudessa esitellään mittakaavaedun käsite ja luodaan pohjaa, mittakaavaetujen aiempien tutkimusten perusteella, tutkimuskysymyksen tarkasteluun. Tutkimuksen aineisto kerättiin Amadeus-tietokannasta, tutkimus toteutettiin kvantitatiivisena tutkimuksena SAS-ohjelmistolla käyttäen Mann-Whitney U-testi -menetelmää ja 5 prosentin merkitsevyystasoa. Valitut yritykset jaettiin liikevaihdon perusteella suuriin ja pieniin yrityksiin (rajana 10 miljoonaa euroa), joita vuosittain verrattiin tunnusluvuittain. Tutkimustulosten perusteella voidaan todeta, että toimiala ei reagoinut ajanjaksolla voimakkaasti maailmantalouden muutoksiin. Voittoprosentit sekä omavaraisuusasteet olivat vuosina 2007–2014 pienillä yrityksillä tilastollisesti parempia, sekä oman pääoman tuottoprosentit parempia vuosina 2008 ja 2009. Current ration arvoissa ei ryhmien välillä havaittu tilastollisesti eroja. Voittoprosentin tulosten perusteella voidaan todeta suurilla yrityksillä mittakaavahaittojen esiintymisen mahdollisuus heikomman tuloksentekokyvyn vuoksi. Omavaraisuusasteen ja oman pääoman tuoton tulosten perusteella voidaan päätellä mittakaavaetujen esiintymisen mahdollisuus mahdollisesti vieraan pääoman saatavuudessa, kustannuksissa ja vieraan pääoman vipuvaikutuksen myötä. Tutkimustulokset osoittavat lisäksi suurten yritysten olleen pieniä yrityksiä herkempiä talouden heilahteluille.
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All of the imputation techniques usually applied for replacing values below the detection limit in compositional data sets have adverse effects on the variability. In this work we propose a modification of the EM algorithm that is applied using the additive log-ratio transformation. This new strategy is applied to a compositional data set and the results are compared with the usual imputation techniques
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Los resultados financieros de las organizaciones son objeto de estudio y análisis permanente, predecir sus comportamientos es una tarea permanente de empresarios, inversionistas, analistas y académicos. En el presente trabajo se explora el impacto del tamaño de los activos (valor total de los activos) en la cuenta de resultados operativos y netos, analizando inicialmente la relación entre dichas variables con indicadores tradicionales del análisis financiero como es el caso de la rentabilidad operativa y neta y con elementos de estadística descriptiva que permiten calificar los datos utilizados como lineales o no lineales. Descubriendo posteriormente que los resultados financieros de las empresas vigiladas por la Superintendencia de Sociedades para el año 2012, tienen un comportamiento no lineal, de esta manera se procede a analizar la relación de los activos y los resultados con la utilización de espacios de fase y análisis de recurrencia, herramientas útiles para sistemas caóticos y complejos. Para el desarrollo de la investigación y la revisión de la relación entre las variables de activos y resultados financieros se tomó como fuente de información los reportes financieros del cierre del año 2012 de la Superintendencia de Sociedades (Superintendencia de Sociedades, 2012).