Search results for "Principal Component Analysis"

Fruit physical, chemical and aromatic attributes of early, intermediate and late apricot cultivars.

2010

BACKGROUND: In order to reach good fruit quality, apricots require a balance of sugars and acids as well as a strong apricot aroma. In this study, fruit quality of early, intermediate and late apricot cultivars was evaluated by measuring physical, chemical and olfactory attributes. Multivariate analysis of quality and aroma attributes was used to identify groups of similar cultivars and association with ripening season. RESULTS: Physical, chemical and aromatic attributes showed great variation amongcultivars but no relation to ripening season. Aromatic profiles (34 volatiles) of fruit tissues indicated qualitative and quantitative differences among cultivars. Ninfa and Mandorlon were riches…

Metabolic flux understanding of Pichia pastoris grown on heterogenous culture media

2014

[EN] Within the emergent field of Systems Biology, mathematical models obtained from physical chemical laws (the so-called first principles-based models) of microbial systems are employed to discern the principles that govern cellular behaviour and achieve a predictive understanding of cellular functions. The reliance on this biochemical knowledge has the drawback that some of the assumptions (specific kinetics of the reaction system, unknown dynamics and values of the model parameters) may not be valid for all the metabolic possible states of the network. In this uncertainty context, the combined use of fundamental knowledge and data measured in the fermentation that describe the behaviour…

Eggshell types and their evolutionary correlation with life-history strategies in squamates

2015

The eggshell is an important physiological structure for the embryo. It enables gas exchange, physical protection and is a calcium reserve. Most squamates (lizards, snakes, worm lizards) lay parchment-shelled eggs, whereas only some gekkotan species, a subgroup of lizards, have strongly calcified eggshells. In viviparous (live-bearing) squamates the eggshell is reduced or completely missing (hereafter “shell-less”). Recent studies showed that life-history strategies of gekkotan species differ between species with parchment- and rigid-shelled eggshells. Here we test if the three different eggshell types found in the squamates are also associated with different life-history strategies. We fir…

Two-step principal component analysis (PCA) as a method for separating auditory N1 and N250 elicited from 9-year-old children using a dense electrode…

2008

Detection of damage in civil engineering structures by PCA on enviromental vibration data

2018

The dynamic behavior of civil engineering structures are usually studied by means of ambient vibration observations and their performance is analyzed by Peak Picking and/or Operational Modal Analysis methods. This paper reports the first results of a statistical multivariate approach, specifically Principal Component Analysis, to detect a suspected structural damage on a sicilian highway bridge. Furthermore, the damage simulated in a simple structural model made it possible to understand the characteristics of the method consisting in comparing the observed data on an undamaged structure with those coming from a damaged one.

Reconstructing the free-energy landscape of Met-enkephalin using dihedral principal component analysis and well-tempered metadynamics

2013

Well-Tempered Metadynamics (WTmetaD) is an efficient method to enhance the reconstruction of the free-energy surface of proteins. WTmetaD guarantees a faster convergence in the long time limit in comparison with the standard metadynamics. It still suffers however from the same limitation, i.e. the non trivial choice of pertinent collective variables (CVs). To circumvent this problem, we couple WTmetaD with a set of CVs generated from a dihedral Principal Component Analysis (dPCA) on the Ramachadran dihedral angles describing the backbone structure of the protein. The dPCA provides a generic method to extract relevant CVs built from internal coordinates. We illustrate the robustness of this …

Investigation of protein folding by coarse-grained molecular dynamics with the UNRES force field.

2010

Coarse-grained molecular dynamics simulations offer a dramatic extension of the time-scale of simulations compared to all-atom approaches. In this article, we describe the use of the physics-based united-residue (UNRES) force field, developed in our laboratory, in protein-structure simulations. We demonstrate that this force field offers about a 4000-times extension of the simulation time scale; this feature arises both from averaging out the fast-moving degrees of freedom and reduction of the cost of energy and force calculations compared to all-atom approaches with explicit solvent. With massively parallel computers, microsecond folding simulation times of proteins containing about 1000 r…

7keto-stigmasterol and 7keto-cholesterol induce differential proteome changes to intestinal epitelial (Caco-2) cells

2015

Abstract Recent studies have expanded the appreciation of the roles of oxysterols triggering inflammatory, immune cytotoxic and apoptotic processes, but have not been considered for proteome analysis. A comparative proteomic study in intestinal epithelial cell cultures incubated (60 μM/24 h) with 7keto-cholesterol or 7keto-stigmasterol was performed. The influence of both compounds was studied following the nLC-TripleTOF analysis. Findings were compared to results for control cultures. In the principal component analysis (PCA) of proteome patterns, two components were extracted accounting for 99.8% of the variance in the protein expression. PCA analysis clearly discriminated between the per…

Transport of high molecular mass lignin material in the receiving water system of a mechanical pulp mill

1998

High molecular mass material (HMM) of water samples collected from the receiving water system of a mechanical pulp mill was characterized applying cupric oxide oxidation combined with GC and HPLC analysis of the oxidation products. This qualitative method was used to follow the transport of organic HMM discharged by the mill. The interpretation of results was complicated by degradation reactions of HMM in the water system and the assimilation of HMM produced by the mill to natural humic compounds. The analytical data was subjected to the principal component analysis (PCA) to verify the results obtained.

PCA and PLS methods applied to ecotoxicological data: Ecobalance project

1996

Within a case study ‘Ecobalance’, the fate and effects of various chlorinated and non-chlorinated organic compounds and some heavy metals discharged from pulp and paper mills into water, sediment and aquatic animals were studied in a recipient area of southern Lake Saimaa, SE Finland. The main aim of the project was to find an empirical link between chemical emission parameters and ecotoxicological effects expressed in the ecosystem. As part of the \‘Ecobalance’ project, principal component analysis (PCA) and partial least squares (PLS) methods were used to interpret the data of the lake area. The PLS method was used to estimate the lake area affected by mill effluents and to calculate the …