Subsequent Principal Component Analysis Research Articles

Impact of dewatering technologies on specific methanogenic activity

Dewatering methods for recuperative thickening and final dewatering can potentially impact methanogenic activity and microbial community. This influences both the feasibility of recuperative thickening to increase solids residence time within a digester, and the utilisation of dewatered digestate as inoculum for new digesters. Thickening technology can reduce methanogenic activity through either air contact (rotary drum, DAF, or belt filter press), or by lysing cells through shear (centrifuge). To assess this, two plants with recuperative thickening (rotary drum) in their anaerobic digester, and five without recuperative thickening, had specific methanogenic activity tested in all related streams, including dewatering feed, thickened return, final cake, and centrate. All plants had high speed centrifuges for final dewatering. The digester microbial community was also assessed through 16s pyrotag sequencing and subsequent principal component analysis (PCA). The specific methanogenic activity of all samples was in the expected range of 0.2–0.4 gCOD gVS−1d−1. Plants with recuperative thickening did not have lower digester activity. Centrifuge based dewatering had a significant and variable impact on methanogenic activity in all samples, ranging between 20% and 90% decrease but averaging 54%. Rotary drum based recuperative thickening had a far smaller impact on activity, with a 0% per-pass drop in activity in one plant, and a 20% drop in another. However, the presence of recuperative thickening was a major predictor of overall microbial community (PC1, p = 0.0024). Microbial community PC3 (mainly driven by a shift in methanogens) was a strong predictor for sensitivity in activity to shear (p = 0.0005, p = 0.00001 without outlier). The one outlier was related to a plant producing the wettest cake (17% solids). This indicates that high solids is a potential driver of sensitivity to shear, but that a resilient microbial community can also bestow resilience. Sensitivity of methanogens to centrifuging does not rule out centrifuges for recuperative thickening (particularly where hydrolysis is rate-limiting), but may impose a maximum return rate to avoid digester failure.

Contents of therapeutic metabolites in Swertia chirayita correlate with the expression profiles of multiple genes in corresponding biosynthesis pathways

Swertia chirayita, an endangered medicinal herb, contains three major secondary metabolites swertiamarin, amarogentin and mangiferin, exhibiting valuable therapeutic traits. No information exists as of today on the biosynthesis of these metabolites in S. chirayita. The current study reports the expression profiling of swertiamarin, amarogentin and mangiferin biosynthesis pathway genes and their correlation with the respective metabolites content in different tissues of S. chirayita. Root tissues of greenhouse grown plants contained the maximum amount of secoiridoids (swertiamarin, 2.8% of fr. wt and amarogentin, 0.1% of fr. wt), whereas maximum accumulation of mangiferin (1.0% of fr. wt) was observed in floral organs. Differential gene expression analysis and their subsequent principal component analysis unveiled ten genes (encoding HMGR, PMK, MVK, ISPD, ISPE, GES, G10H, 8HGO, IS and 7DLGT) of the secoiridoids biosynthesis pathway and five genes (encoding EPSPS, PAL, ADT, CM and CS) of mangiferin biosynthesis with elevated transcript amounts in relation to corresponding metabolite contents. Three genes of the secoiridoids biosynthesis pathway (encoding PMK, ISPD and IS) showed elevated levels (∼57–104 fold increase in roots), and EPSPS of mangiferin biosynthesis showed an about 117 fold increase in transcripts in leaf tissues of the greenhouse grown plants. The study does provide leads on potential candidate genes correlating with the metabolites biosynthesis in S. chirayita as an initiative towards its genetic improvement.

Uniform sampling of steady states in metabolic networks: heterogeneous scales and rounding.

The uniform sampling of convex polytopes is an interesting computational problem with many applications in inference from linear constraints, but the performances of sampling algorithms can be affected by ill-conditioning. This is the case of inferring the feasible steady states in models of metabolic networks, since they can show heterogeneous time scales. In this work we focus on rounding procedures based on building an ellipsoid that closely matches the sampling space, that can be used to define an efficient hit-and-run (HR) Markov Chain Monte Carlo. In this way the uniformity of the sampling of the convex space of interest is rigorously guaranteed, at odds with non markovian methods. We analyze and compare three rounding methods in order to sample the feasible steady states of metabolic networks of three models of growing size up to genomic scale. The first is based on principal component analysis (PCA), the second on linear programming (LP) and finally we employ the Lovazs ellipsoid method (LEM). Our results show that a rounding procedure dramatically improves the performances of the HR in these inference problems and suggest that a combination of LEM or LP with a subsequent PCA perform the best. We finally compare the distributions of the HR with that of two heuristics based on the Artificially Centered hit-and-run (ACHR), gpSampler and optGpSampler. They show a good agreement with the results of the HR for the small network, while on genome scale models present inconsistencies.

Sensory Characterization of Commercial Lager Beers and Their Correlations with Iso-α-Acid Concentrations

A total of 40 commercial lager beers (6 dark, 28 pale and 6 alcohol free) were analysed by High-Performance Liquid Chromatography (HPLC) and evaluated by a descriptive sensorial panel. Discriminant Analysis was applied to 15 sensory descriptors to obtain a classification by types of beer. Cluster Analysis identified 4 clusters grouping the 15 sensory descriptors. The Correlation Matrix confirmed a correlation between them and the subsequent Principal Component Analysis. A stepwise discriminant analysis was used to eliminate the less significant descriptors, leading to 100% of the samples being correctly classified with a reduced number of variables (colour intensity, smell of caramel, smell of toasted, persistence and viscosity). The analysis of the correlations between iso-α-acid concentrations and sensory descriptors shows a good relationship with bitter taste. Thus, HPLC data can be used for predicting lager beer bitterness through the mathematical correlation developed in this paper.

Korean, Japanese, and Chinese populations featured similar genes encoding drug-metabolizing enzymes and transporters: a DMET Plus microarray assessment.

Interethnic differences in genetic polymorphism in genes encoding drug-metabolizing enzymes and transporters are one of the major factors that cause ethnic differences in drug response. This study aimed to investigate genetic polymorphisms in genes involved in drug metabolism, transport, and excretion among Korean, Japanese, and Chinese populations, the three major East Asian ethnic groups. The frequencies of 1936 variants representing 225 genes encoding drug-metabolizing enzymes and transporters were determined from 786 healthy participants (448 Korean, 208 Japanese, and 130 Chinese) using the Affymetrix Drug-Metabolizing Enzymes and Transporters Plus microarray. To compare allele or genotype frequencies in the high-dimensional data among the three East Asian ethnic groups, multiple testing, principal component analysis (PCA), and regularized multinomial logit model through least absolute shrinkage and selection operator were used. On microarray analysis, 1071 of 1936 variants (>50% of markers) were found to be monomorphic. In a large number of genetic variants, the fixation index and Pearson's correlation coefficient of minor allele frequencies were less than 0.034 and greater than 0.95, respectively, among the three ethnic groups. PCA identified 47 genetic variants with multiple testing, but was unable to discriminate ethnic groups by the first three components. Multinomial least absolute shrinkage and selection operator analysis identified 269 genetic variants that showed different frequencies among the three ethnic groups. However, none of those variants distinguished between the three ethnic groups during subsequent PCA. Korean, Japanese, and Chinese populations are not pharmacogenetically distant from one another, at least with regard to drug disposition, metabolism, and elimination.

High-throughput nucleoside phosphate monitoring in mammalian cell fed-batch cultivation using quantitative matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Current methods for monitoring multiple intracellular metabolite levels in parallel are limited in sample throughput capabilities and analyte selectivity. This article presents a novel high-throughput method based on matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOF-MS) for monitoring intracellular metabolite levels in fed-batch processes. The MALDI-TOF-MS method presented here is based on a new microarray sample target and allows the detection of nucleoside phosphates and various other metabolites using stable isotope labeled internal standards. With short sample preparation steps and thus high sample throughput capabilities, the method is suitable for monitoring mammalian cell cultures, such as antibody producing hybridoma cell lines in industrial environments. The method is capable of reducing the runtime of standard LC-UV methods to approximately 1 min per sample (including 10 technical replicates). Its performance is exemplarily demonstrated in an 8-day monitoring experiment of independently controlled fed-batches, containing an antibody producing mouse hybridoma cell culture. The monitoring profiles clearly confirmed differences between cultivation conditions. Hypothermia and hyperosmolarity were studied in four bioreactors, where hypothermia was found to have a positive effect on the longevity of the cell culture, whereas hyperosmolarity lead to an arrest of cell proliferation. The results are in good agreement with HPLC-UV cross validation experiments. Subsequent principal component analysis (PCA) clearly separates the different bioreactor conditions based on the measured mass spectral profiles. This method is not limited to any cell line and can be applied as a process analytical tool in biotechnological processes.

Amplified fragment length polymorphisms, the evolution of the land snail genusTheba(Stylommatophora: Helicidae), and an objective approach for relating fossils to internal nodes of a phylogenetic tree using geometric morphometrics

Time-trees are commonly calibrated based on fossils attributed to internal nodes, thus defining the minimum age of these nodes. However, in the absence of synapomorphies, the phylogenetic position of a fossil can only be inferred based on similarity. In this study, we objectively allocated fossil shells to internal nodes based on the reconstruction of ancestral shapes and sizes in a geometric morphometric framework. Our phylogenetic analysis of 24 (putative sub)species was based on 2524 amplified fragment length polymorphism loci. In this well-supported tree the taxa occurring in north-west Africa and on the Iberian peninsula were paraphyletic with respect to the (sub)species from the Canary and Selvagen Islands, indicating a continental origin of the genus in contrast to our earlier sequence-based account. Ancestral shell shapes and sizes were inferred based on landmark data using squared-change parsimony. In a subsequent principal component analysis, only three of 20 fossil shells could be unequivocally allocated to internal nodes. However, these fossils were all Quaternary, and thus too young to infer meaningfully narrow confidence intervals for divergence estimates that probably reach back into the Miocene or even Oligocene. The apparent failure of allocating older fossils to internal nodes and achieving a reliable tree calibration was caused by the absence of phylogenetic signal in the shells of Theba due to extensive, sometimes rapid, convergent evolution, including reversals. © 2014 The Linnean Society of London

Developing an understanding of dissolved organic matter dynamics in the giant Lake Baikal by ultrahigh resolution mass spectrometry

To elucidate the molecular characteristics of dissolved organic matter (DOM) in Lake Baikal, 3D excitation-emission matrix spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) were employed. From the linear relationship between the humic-like peak intensities (excitation/emission = 305 nm/430 nm) and dissolved organic carbon (DOC) concentrations in the water samples extending from the Selenga River mouth to offshore (central lake in the south basin), allochthonous DOM appeared to be a main contributor to the DOC concentrations. However, DOM with fewer fluorophores dominated in the South Basin of the lake at stable DOC concentrations of ca. 0.84 mg C l−1. Meanwhile, FT-ICR MS analysis and subsequent principal component analysis across the transect revealed a transition of compounds with high H-deficiency (aromatic) to compounds with low H-deficiency (aliphatic) that dominate pelagic open-lake water. We believe that this molecular change is induced by photo-degradation, which mainly alters aromatic compounds.

A Comprehensive Study on Triacylglycerols in Tobacco Leaves Using Liquid Chromatography and Atmospheric- Pressure Chemical-Ionization Mass Spectrometry

Abstract Triacylglycerols in tobacco leaves were investigated to further understand their compositional and metabolic differences among various tobacco leaves and their changes during the curing processes. Non-aqueous reverse-phase chromatography for efficient separation of triacylglycerols and atmospheric-pressure chemical-ionization mass spectrometry for their detection were selected for quantitative analysis. For measuring their absolute amounts, authentic triacylglycerols comprised of the same fatty acids were introduced to generate calibration curves and to quantify the analytes. A validation study using the combination of appropriate separation and authentic triacylglycerols produced very good results in terms of linearity (> 0.999), limit of detection (3-4 ng), limit of quantification (10-15 ng) and recovery ratio (80-120%). The quantification of triacylglycerols in tobacco leaves and a subsequent principal component analysis clarified for the first time their compositional and metabolic differences among various tobacco leaves.

Soil properties and microbial functional structure in the rhizosphere of Pinus densiflora (S. and Z.) exposed to elevated atmospheric temperature and carbon dioxide

Rhizosphere-induced changes of Pinus densiflora (S. and Z.) grown at elevated atmospheric temperature and carbon dioxide are presented based on experiments carried out in a two-compartment rhizobag system filled with forest soil in an environmentally controlled walk-in chamber with four treatment combinations: control (25°C, 500 μmol mol−1 CO2), T2 (30°C, 500 μmol mol−1 CO2), T3 (25°C, 800 μmol mol−1 CO2), and T4 (30°C, 800 μmol mol−1 CO2). Elevated temperature and atmospheric carbon dioxide resulted in higher concentration of sugars and dissolved organic carbon in soil solution, especially at the later period of plant growth. Soil solution pH from the rhizosphere became less acidic than the bulk soil regardless of treatment, while the electrical conductivity of soil solution from the rhizosphere was increased by elevated carbon dioxide treatment. Biolog EcoPlate™ data showed that the rhizosphere had higher average well color development, Shannon–Weaver index, and richness of carbon utilization compared with bulk soil, indicating that microbial activity in the rhizosphere was higher and more diverse than in bulk soil. Subsequent principal component analysis indicated separation of soil microbial community functional structures in the rhizosphere by treatment. The principal components extracted were correlated to plant-induced changes of substrate quality and quantity in the rhizosphere as plants' response to varying temperature and atmospheric carbon dioxide.

Th17 cells, pathogenic or not? TGF-β3 imposes the embargo

Th17 cells, pathogenic or not? TGF-β3 imposes the embargo

Detection and identification of salts and frozen salt solutions combining laser-induced breakdown spectroscopy and multivariate analysis methods: A study for future martian exploration

For the geochemical investigation of extraterrestrial surfaces laser-induced breakdown spectroscopy (LIBS) has been suggested as a powerful analytical tool, and is part of the payload on NASA’s rover Curiosity, which reached Mars in August 2012. Apart from soil in general, LIBS is capable of analyzing ice and salts within the soil. This study demonstrates the feasibility of LIBS for investigating and differentiating between different salts by applying three multivariate analysis (MVA) techniques. The focus was on the capability of the MVA techniques for LIBS data to discriminate between sulfates and chlorides with cations of the same kind as pure pressed pellets and in frozen salt solutions. Two data sets of LIBS spectra of eight different salts (CaCl2, CaSO4, KCl, K2SO4, MgCl2, MgSO4, NaCl, Na2SO4), pure and as frozen salt solutions, were acquired in a dedicated simulation chamber under martian atmospheric conditions. With principal components analysis (PCA) both data sets were analyzed with the aim of dividing the spectra of the ices into groups and revealing the most important lines in the spectra for discrimination and identification of the type of salt. PCA performance is improved by selecting the most relevant lines with emphasis on the sulfur and chlorine lines and additionally averaging the spectra before analysis. Moreover, a subsequent PCA with a subset of data can improve the discrimination ability for a sulfate and a chloride with the same type of cation. Soft independent modeling of class analogy (SIMCA) and partial least squares discriminant analysis (PLS-DA) were performed for both data sets. While SIMCA worked well for the pressed salt samples, its application to the spectra of the frozen salt solutions was not successful. A local PLS-DA of the LIBS spectra of salts with the same cation is capable of distinguishing sulfate and chloride.

Omega‐3 supplementation prevents intestinal inflammation by inhibiting the expansion of an intestinal pathobiont in IL10−/− mice

The human microbiome of Western populations has changed over the past century, brought on by new environmental triggers that often have a negative impact on human health. Previously we showed consumption of a diet high in saturated (anhydrous milkfat‐derived) fat (MF) but not polyunsaturated (safflower oil‐derived)‐fat (PUFA) changes the conditions for microbial assemblage and promotes expansion of a rare, immunogenic, sulfite‐reducing pathobiont, Bilophila wadsworthia. This was associated with a proinflammatory TH1 immune response and development of colitis in genetically susceptible IL‐10−/− mice in both specific pathogen free (SPF) and germ‐free environments. The current study examines whether omega‐3 supplementation can attenuate the effect of the MF diet by reducing the bacterial load of B. wadsworthia and subsequent inflammation. SPF IL10−/− mice were adapted to either a low‐fat (LF), high saturated milk‐fat (MF), fish oil supplemented (FO), or safflower oil supplemented (SO) diets. All three high fat diets were isocaloric with fat comprising 37% total kcal, with the supplemented groups representing 32% MF + 5% FO or SO. After 10wk, 454 pyrosequencing of cecal contents and subsequent principal component analysis revealed colonic bacterial communities of mice on the FO diet were significantly different than those on MF and SO diets. Particularly noticeable was the decrease in abundance of B. wadsworthia in the FO treated mice. This observation was accompanied by reduced levels of IL‐6, IL‐17, IL12p70, and IFNγ, as well as reduced histological colitis scores compared to MF and SO fed mice. Together these data suggest omega‐3 supplementation may decrease risk for inflammatory bowel diseases by suppressing pro‐inflammatatory pathobionts such as B. wadsworthia. Supported by NIH F31.Grant Funding Source : NIH

Individual Differences in the Chemical Senses: Is There a Common Sensitivity?

Taste, smell, and chemical irritation (so-called trigeminal sensation) combine in our daily experience to produce the supramodal sensation of flavor, are processed by partly overlapping neural mechanisms, and show functional interconnectivity in experiments. Given their collaboration in flavor formation and the well-established connections between these senses, it is plausible that polymodal detection mechanisms might contribute to individual differences in measured sensitivity. One would expect the existence of a general chemosensory sensitivity factor to result in associations among taste, smell, and trigeminal stimulation thresholds. Measures of 5 detection thresholds from all the chemical senses were assessed in the same group of young healthy subjects (n=57). An unbiased principal components analysis (PCA) yielded a 2-component solution. Component 1, on which taste thresholds loaded strongly, accounted for 29.4% of the total variance. Component 2, on which the odor and trigeminal lateralization thresholds loaded strongly, accounted for 26.9% of the total variance. A subsequent PCA restricted to a 3-component solution cleanly separated the 3 sensory modalities and accounted for 75% of the total variance. Thus, though there may be a common underlying factor that determines some individual differences in odor and trigeminal lateralization thresholds, a general chemical sensitivity that spans chemosensory modalities seems unlikely.

GC-MS and HPLC Metabolic Profiling Studies of Curcuma wenyujin Rhizomes Obtained at Different Harvest Times

Curcuma plants are usually considered to be antibacterial, anti-viral, and anti-tumor plants. It is of great importance to study the developmental metabolic characteristics of these plants for their rational use and in-depth development. In this work, the volatile and polar compounds of C. wenyujin collected at different harvest times were analyzed using gas chromatography-mass spectrometry and high-performance liquid chromatography. Subsequent principal components analysis (PCA) was used to identify time-related patterns. Sixty-six volatile components were identified, and no distinct phytochemical differences were found with varying harvest times. The PCA results show that the metabolic patterns of both volatile and polar extracts could reflect the metabolic characteristics of the development of C. wenyujin. Curzerene, curzerenone, germacron, and curdione, which were screened by PCA loadings plots, could be used as chemical markers for differentiation of the developmental stages of the samples. The results of this study imply that metabolic profiling of secondary metabolites may be a suitable tool for identifying the physiological states and chemical markers involved in the growth and development of C. wenyujin, as well as other Curcuma plants.

Capability of advanced spaceborne thermal emission and reflection radiometer (ASTER) on discrimination of carbonates and associated rocks and mineral identification of eastern mountain region (Saih Hatat window) of Sultanate of Oman

The present study demonstrates the capability of multi-spectral data acquired from advanced spaceborne thermal emission and reflection radiometer (ASTER) satellite to explore the areas of massive carbonate deposits and associated rock formations for geological application. The extent of interdependence among VNIR, SWIR and TIR bands of ASTER spectral regions has been studied for discrimination of rock formations and identification of minerals of eastern mountain region (Saih Hatat window) of Sultanate of Oman and processed through digital image analysis and classification. Visual interpretation techniques have been employed to discriminate major quartz-rich silicates, carbonates and mafic ophiolite rock formations on the satellite image by carrying out subsequent image enhancement technique and principal component analysis (PCA). Color composite using nine VNIR and SWIR ASTER spectral bands by exposing the results of band ratios of (band 7 + band 9)/band 8 for limestone (CaCO3); (band 6 + band 8)/band 7 for dolomite (CaMgCO3); and band 2/band 1 for mafic-rich (Fe3+) rock formations differentiated the carbonates and ophiolite formations of the study region. The band ratios of 6/8 developed for quartz-rich silicates (shale, schist, sandstone, graywackes) of autochthonous Unit ‘A’ of Late Proterozoic to Early Ordovician and Tertiary age, 9/7 for the carbonates (limestone and dolomite) of Autochthonous rock Unit ‘B’ of Late Permian to Triassic age and 1/2 for mafic ophiolites (harzburgite, harzburgite with dunite) of Samail Nappe discriminated the different rock formations and increased the visual interpretations. It has well delineated the gray limestone and yellow dolomite of Autochthonous Unit ‘A’. The subsequent PCA realized on the 6 SWIR spectral bands enables very good validation and discrimination of quartz-rich silicates, carbonates and mafic ophiolite rock formations defined on previous image rationing techniques and existing geological map, and provides information comparable to surficial formations previously not well recognized. It is capable of distinguishing the ancient and recent alluvial fans consisting of clay, silt, sand and conglomerate formations of Tertiary age from the Autochthonous Unit ‘A’. Furthermore, the ASTER TIR spectral indices have been applied for assessing the effectiveness of TIR spectral bands on identification of quartz-rich silicates, carbonates and mafic-rich minerals and to evaluate the discriminated rock formations. The results agree well with existing geological maps and other published data. The study results show that the combination of visual interpretation, previous field knowledge and digital image processing techniques applied on the ASTER spectral regions have proved beneficial in studying carbonates and associated rock formations of eastern mountain region of Sultanate of Oman and can thus be used as a powerful tool to explore massive carbonate deposits or for geological mapping of other geographical regions where similar geological questions need to be resolved.

Classification of animal dive tracks via automatic landmarking, principal components analysis and clustering

The behaviour of animals and their interactions with the environment can be inferred by tracking their movement. For this reason, biologgers are an important source of ecological data, but analysing the shape of the tracks they record is difficult. In this paper we present a technique for automatically determining landmarks that can be used to analyse the shape of animal tracks. The approach uses a parametric version of the SALSA algorithm to fit regression splines to 1-dimensional curves in N dimensions (in practice N = 2 or 3). The knots of these splines are used as landmarks in a subsequent Principal Components Analysis, and the dives classified via agglomerative clustering. We demonstrate the efficacy of this algorithm on simulated 2-dimensional dive data, and apply our method to real 3-dimensional whale dive data from the Behavioral Response Study (BRS) in the Bahamas. The BRS is a series of experiments to quantify shifts in behavior due to SONAR. Our analysis of 3-dimensional track data supports an alteration in the dive behavior post-ensonification.

Cuticular hydrocarbons as contact sex pheromone in the parasitoid Dibrachys cavus

Cuticular hydrocarbons (CHCs) cover the cuticle of virtually any insect and do not only protect them from desiccation, but also possess various communicative functions. Previous studies suggested a function as contact sex pheromones in the parasitic wasp family Pteromalidae, but further species need to be studied before more general conclusions are possible. Here, we demonstrate a contact sex pheromone in females of Dibrachys cavus (Walker) (Hymenoptera: Pteromalidae). Males of this parasitoid were arrested on cadavers of 1- to 2-day-old females, but neither on newly emerged females nor on males. Extracts from 1- to 2-day-old females and non-polar fractions were also behaviorally active suggesting a non-polar contact sex pheromone. Chemical analyses of bioactive and non-active CHC profiles by gas chromatography–mass spectrometry and subsequent principal component analysis (PCA) revealed that the bioactive profiles from 1- to 2-day-old females were clearly distinguishable from all other profiles. Among the chemicals showing the strongest impact in the PCA were the two 3-methylalkanes 3-methylnonacosane and 3-methylhentriacontane, which were absent or trace components in the inactive profiles and whose relative amounts increased in females when they became sexually attractive. The putative function of 3-methylalkanes as key components of the contact sex pheromones in Pteromalidae is discussed.

Mapping emotions into acoustic space: The role of voice production

Research on the vocal expression of emotion has long since used a “fishing expedition” approach to find acoustic markers for emotion categories and dimensions. Although partially successful, the underlying mechanisms have not yet been elucidated. To illustrate that this research can profit from considering the underlying voice production mechanism, we specifically analyzed short affect bursts (sustained/a/vowels produced by 10 professional actors for five emotions) according to physiological variations in phonation (using acoustic parameters derived from the acoustic signal and the inverse filter estimated voice source waveform). Results show significant emotion main effects for 11 of 12 parameters. Subsequent principal components analysis revealed three components that explain acoustic variations due to emotion, including “tension,” “perturbation,” and “voicing frequency.” These results suggest that future work may benefit from theory-guided development of parameters to assess differences in physiological voice production mechanisms in the vocal expression of different emotions.

Revealing the properties of oils from their dissolved hydrocarbon compounds in water with an integrated sensor array system

This paper presents a system and method developed to identify a source oil's characteristic properties by testing the oil's dissolved components in water. Through close examination of the oil dissolution process in water, we hypothesise that when oil is in contact with water, the resulting oil-water extract, a complex hydrocarbon mixture, carries the signature property information of the parent oil. If the dominating differences in compositions between such extracts of different oils can be identified, this information could guide the selection of various sensors, capable of capturing such chemical variations. When used as an array, such a sensor system can be used to determine parent oil information from the oil-water extract. To test this hypothesis, 22 oils' water extracts were prepared and selected dominant hydrocarbons analyzed with Gas Chromatography-Mass Spectrometry (GC-MS); the subsequent Principal Component Analysis (PCA) indicates that the major difference between the extract solutions is the relative concentration between the volatile mono-aromatics and fluorescent polyaromatics. An integrated sensor array system that is composed of 3 volatile hydrocarbon sensors and 2 polyaromatic hydrocarbon sensors was built accordingly to capture the major and subtle differences of these extracts. It was tested by exposure to a total of 110 water extract solutions diluted from the 22 extracts. The sensor response data collected from the testing were processed with two multivariate analysis tools to reveal information retained in the response patterns of the arrayed sensors: by conducting PCA, we were able to demonstrate the ability to qualitatively identify and distinguish different oil samples from their sensor array response patterns. When a supervised PCA, Linear Discriminate Analysis (LDA), was applied, even quantitative classification can be achieved: the multivariate model generated from the LDA achieved 89.7% of successful classification of the type of the oil samples. By grouping the samples based on the level of viscosity and density we were able to reveal the correlation between the oil extracts' sensor array responses and their original oils' feature properties. The equipment and method developed in this study have promising potential to be readily applied in field studies and marine surveys for oil exploration or oil spill monitoring.