Search results for "PCa"

A database for historical pigments through handheld instrumentation

2020

Portable instrumentation is largely used in archaeometry for in-field measurements at museums and archaeological sites. The historic evolution of pigments is closely related to the technology developments in past cultures and provides relevant clues regarding their knowledge advancement. Here, a systematic study of 26 historical powdered pigments was carried out through a combined handheld instrumentation for X-ray Fluorescence. Chemical identification was carried out through a set of instrumentation produced by different manufacturers. Their performances are compared on the same set of samples to identify best practices for the study of historical pigments. A database of organic and inorga…

Contribution à l'estimation non paramétrique des quantiles géométriques et à l'analyse des données fonctionnelles

2008

In this dissertation we study the nonparametric geometric quantile estimation, conditional geometric quantiles estimation and functional data analysis. First, we are interested to the definition of geometric quantiles. Different simulations show that Transformation-Retransformation technique should be used to estimate geometric quantiles when the distribution is not spheric. A real study shows that, data are better modelized by geometric quantiles than by marginal one's, especially when variables that make up the random vector are correlated. Then we estimate geometric quantiles when data are obtained by survey sampling techniques. First, we propose an unbaised estimator, then using lineari…

Analisi statistica tramite PCA su dati colorimetrici di tessere musive pavimentali

2010

Y hromosomas ģenētisko variāciju salīdzinājums baltu un austrumslāvu populācijās

2016

Maģistra darbs ir veltīts austrumslāvu populāciju Y hromosomas ģenētiskās struktūras īpatnību noteikšanai un iegūto rezultātu salīdzinājumam ar baltu un ziemeļaustrumu Eiropas populācijām. Pētījuma ietvaros tika noteikta Y hromosomas haplogrupu izplatība Kijevas un Novgorodas apgabala populācijās. Iegūtie rezultāti norāda, ka Kijevas apgabalā visizplatītākā haplogrupa ir R1a (39,71%), bet Novgorodas apgabalā – N1c (74,32%). Detalizējot rezultātus ar PCA un filoģenētisko Neighbour-Joining analīzi, tika noteikts, ka Novgorodas apgabala populācija ģenētiski atrodas vistuvāk somiem augstās N1c haplogrupas izplatības dēļ, savukārt, pēc R1a-M558 atzara izplatības pētītajā teritorijā, autore secin…

Detection and discrimination of organophosphorus pesticides in water by using a colorimetric probe array

2014

[EN] Detection and discrimination of several organophosphorus pesticides in water using a colorimetric probe array containing twelve dyes has been achieved. A clear discrimination for malathion, leptophos, dichlorvos, dibrom and diazinon was observed. The array was used to determine the concentration of diazinon in orange leaves

Nonlinear data description with Principal Polynomial Analysis

2012

Principal Component Analysis (PCA) has been widely used for manifold description and dimensionality reduction. Performance of PCA is however hampered when data exhibits nonlinear feature relations. In this work, we propose a new framework for manifold learning based on the use of a sequence of Principal Polynomials that capture the eventually nonlinear nature of the data. The proposed Principal Polynomial Analysis (PPA) is shown to generalize PCA. Unlike recently proposed nonlinear methods (e.g. spectral/kernel methods and projection pursuit techniques, neural networks), PPA features are easily interpretable and the method leads to a fully invertible transform, which is a desirable property…

Chemical composition of the essential oil of Cyanus adscendens (Bartl.) Soják and C. orbelicus (Velen.) Soják growing wild in Bulgaria, and PCA analy…

2022

Cyanus Mill. genus, belonging to the Asteraceae family, includes more than 50 taxa, mainly growing in Central and Southern Europe, North Africa, Asia Minor, and the Caucasus. Previous investigations on Cyanus taxa have shown that they are rich source of flavonoids and phenolic compounds but, differently from species of genus Centaurea, almost devoid of sesquiterpene lactones. In the present study, the chemical composition of the essential oils from aerial parts of Cyanus adscendens (CA) and C. orbelicus (CO), collected in Bulgaria, and not previously investigated, was evaluated by GC-MS. The main components of CA were α-bergamotene (31.3%), (Z,Z,Z)-9,12,15-octadecatrien-1-ol (14.5%) and cal…

Integrated analytical methodologies for the non-invasive study of Cultural Heritage: the case study of Renaissance Statues of Abatellis Palace

2012

Polychlorinated Biphenyls in Sediments from Sicilian Coastal Area (Scoglitti) using Automated Soxhlet, GC-MS, and Principal Component Analysis

2014

A methodology for the PAHs and PCBs congener determination in sediment samples has been revised. We determined the distributions of PAHs and PCBs in the superficial sediments of the Scoglitti (Italy) coastal area to provide data for comparison with other marine systems and to hypothesize the sources. Extraction yield, for PCB, was never less than 60% in most cases, while for PAHs, utilizing perdeuterated surrogate standard (benz[a]anthracene-d12 and anthracene-d10) was never less than 72%. The total concentration of the 16 PAHs investigated, expressed as the sum of concentrations, PAHs, varied from 1–5087 μg/kg of dry matrix, while the PCBs ranged from detection limit to 36 μg/kg of dry mat…

Estimation of the density of the protocatechuate-degrading bacterial community in soil by real-time PCR

2008

Summary The β-ketoadipate pathway is the major route for degradation of aromatic compounds by various soil microorganisms. Protocatechuate 3,4-dioxygenase, a key enzyme of this pathway and which is encoded by pcaGH genes, catalyses the ring cleavage of protocatechuate. Microorganisms harbouring pcaGH genes are widely distributed in the environment but little is known about their relative abundance within the total microflora. Hence, this paper reports the development of a real-time PCR assay to quantify the bacterial pcaH sequence that encodes the β sub-unit of the protocatechuate 3,4-dioxygenase. This real-time PCR assay was linear over seven orders of magnitude with a calculated efficienc…