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Multivariate Statistical Analysis (multivariate + statistical_analysis)
Selected AbstractsThe use of multivariate statistics to elucidate patterns of floodplain sedimentation at different spatial scalesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2007Martin C. Thoms Abstract Floodplains are depositional features of riverine landscapes that display complex sedimentation patterns that are amenable to multi-scale approaches. We examined sedimentation in the Lower Balonne floodplain, Queensland, Australia, at three different spatial scales: the channel (103 km), floodplain process zone (10 km) and geomorphic unit (102 m) scales, and compared scale-related patterns evident from stratigraphy with those evident from quantitative multivariate analysis. Three stratigraphic sequences were found in the Lower Balonne floodplain: generally fining upward, episodic fining upward, and mud-dominated. Stratigraphical analysis revealed the detailed character of sedimentary sequences embedded within the scale patterns derived from multivariate analysis. Multivariate statistical analyses of a range of textural and geochemical data revealed different patterns of floodplain sedimentation at each scale. At the channel scale, sediment texture and geochemistry were more heterogeneous in the Culgoa River than in Briarie Creek. At the floodplain process zone scale clear patterns of sediment texture and geochemistry were observed along the upper, mid and lower floodplain process zones of Briarie Creek, but not along the Culgoa River. At the geomorphic unit scale, clear patterns of sediment texture and geochemistry were observed among the bank, buried channel and flat floodplain units of the Culgoa River, but were not as clear in Briarie Creek. Recognition of rivers as hierarchically organized systems is an emerging paradigm in river science. Our study supports this paradigm by demonstrating that different sedimentation patterns occur at different scales to reveal a hierarchically organized floodplain environment. Copyright © 2006 John Wiley & Sons, Ltd. [source] Larval fish assemblages and water mass structure off the oligotrophic south-western Australian coastFISHERIES OCEANOGRAPHY, Issue 1 2008B. A. MUHLING Abstract Larval fish assemblages were sampled using replicated oblique bongo net tows along a five-station transect extending from inshore (18 m depth) to offshore waters (1000 m depth) off temperate south-western Australia. A total of 148 taxa from 93 teleost families were identified. Larvae of Gobiidae and Blenniidae were abundant inshore, while larvae of pelagic and reef-dwelling families, such as Clupeidae, Engraulidae, Carangidae and Labridae were common in continental shelf waters. Larvae of oceanic families, particularly Myctophidae, Phosichthyidae and Gonostomatidae, dominated offshore assemblages. Multivariate statistical analyses revealed larval fish assemblages to have a strong temporal and spatial structure. Assemblages were distinct among seasons, and among inshore, continental shelf and offshore sampling stations. Inshore larval fish assemblages were the most seasonal, in terms of species composition and abundance, with offshore assemblages the least seasonal. However, larval fish assemblages were most closely correlated to water mass, with species distributions reflecting both cross-shelf and along-shore oceanographic processes and events. Similarity profile (SIMPROF) analysis suggested the presence of twelve distinct larval fish assemblages, largely delineated by water depth and season. The strength and position of the warm, southward flowing Leeuwin Current, and of the cool, seasonal, northward flowing Capes Current, were shown to drive much of the variability in the marine environment, and thus larval fish assemblages. [source] Palaeoenvironmental context of the Late-glacial woolly mammoth (Mammuthus primigenius) discoveries at Condover, Shropshire, UKGEOLOGICAL JOURNAL, Issue 4 2009J. R. M. Allen Abstract In 1986/1987 the remains of several mammoths, Mammuthus primigenius (Blumenbach), were discovered on the spoil heap of an actively working gravel pit at Condover, Shropshire, England. The discovery of the remains posed two questions that could be addressed by analyses of biological proxies. First, as none of the bones was found in situ it was necessary to confirm the stratum in which the remains occurred. Second, what was the environment in which these animals lived and died? A range of biological indicators was used to address these questions, including pollen, spore and algal, plant macrofossil, invertebrate, anuran and biological mineral analyses. Multivariate statistical analyses of palynological and Pediastrum data, along with evidence from the Coleopteran assemblages, support the attribution of the mammoth bones to a unit of dark grey clayey sandy silt, although they may have lived at the time of the overlying green detritus mud. The palaeobiological data supports the correlation of these sediments to the Devensian Late-glacial. The mammoths entered this basin at the start of the Late-glacial Interstadial (Greenland Interstadial 1e) (ca. 14,830,3930 cal. year BP; 12,300,±,110 14C year BP) and became mired in soft cohesive sediments. Palaeotemperature reconstructions, based on the Coleopteran assemblages, from the time when the mammoths actually became mired, show that the climate was temperate with mean July temperatures between 15 and 19°C and mean January temperatures between ,13 and +6°C. Biological indicators from the sediments encasing the mammoths indicate that the landscape surrounding the basin was treeless and dry, contrasting with rich vegetation within the basin itself that had possibly attracted the mammoths to the site. Evidence of sedimentary disturbance suggests that the mammoths caused large-scale bioturbation of the deposits making palaeoenvironmental interpretations difficult. Fossils of terrestrial blowflies, carcass and dung beetles show that some of the decaying corpses must have lain exposed on the land surface for sufficient time for the soft parts to have rotted away and skin and bones to have become desiccated before many of them sank into the dark grey clayey sandy silt. Copyright © 2009 John Wiley & Sons, Ltd. [source] A classification of computer security incidents based on reported attack dataJOURNAL OF INVESTIGATIVE PSYCHOLOGY AND OFFENDER PROFILING, Issue 2 2005Maria Kjaerland Abstract Previous studies of computer criminals have attempted to differentiate between offenders, but have not used data from the actual attacks. Drawing on theories from investigative psychology as well as information security, the current study differentiates 2755 computer security incidents using information about Method of Operation (MO), Impact, and Source Sector from reported attacks. Multivariate statistical analyses were applied on the data-matrix of 22 variables and showed the co-occurrences of various aspects of computer security incidents. A radex structure emerged where the high frequency variables were positioned in the centre of the data-plot. Based on a previously developed taxonomy of cyber intrusions, the results of the analysis showed that it was possible to draw inferences about the less informative category of Objective, from information about Attacker, Tools, Access, and Results. By applying the division-lines indicating the Objectives of Challenge/Status, Destruction, Political Gain and Financial Gain on the SSA-plot, it was shown how the taxonomies could be further developed by taking into account the relationships between the categories. Copyright © 2005 John Wiley & Sons, Ltd. [source] Analysis of urinary metabolites for metabolomic study by pressurized CECELECTROPHORESIS, Issue 23 2007Guoxiang Xie Abstract A new approach for the metabolomic study of urinary samples using pressurized CEC (pCEC) with gradient elution is proposed as an alternative chromatographic separation tool with higher degree of resolution, selectivity, sensitivity, and efficiency. The pCEC separation of urinary samples was performed on a RP column packed with C18, 5,,m particles with an ACN/water mobile phase containing TFA. The effects of the acid modifiers, applied voltage, mobile phase, and detection wavelength were systematically evaluated using eight spiked standards, as well as urine samples. A typical analytical trial of urine samples from Sprague Dawley (S.D.) rats exposed to high-energy diet was carried out following sample pretreatment. Significant differences in urinary metabolic profiles were observed between the high energy diet-induced obesity rats and the healthy control rats at the 6th,wk postdose. Multivariate statistical analysis revealed the differential metabolites in response to the diet, which were partially validated with the putative standards. This work suggests that such a pCEC-based separation and analysis method may provide a new and cost-effective platform for metabolomic study uniquely positioned between the conventional chromatographic tools such as HPLC, and hyphenated analytical techniques such as LC-MS. [source] Beyond six scents: defining a seventh Thymus vulgaris chemotype new to southern France by ethanol extractionFLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2009Ken Keefover-Ring Abstract The concept of plant chemotype has long been useful to describe secondary chemical phenotypes; however, the idea has practical limitations, especially when applied to ecological questions. This work reports the discovery of a new 1,8-cineole chemotype of Thymus vulgaris from a well-studied area in southern France. Multivariate statistical analysis of ethanol-extracted plant terpenes was used to describe this new chemotype and three others found at the site, and the results are used to discuss the chemotype concept. While the total amount of essential oils among these chemotypes showed no difference, the concentration of the main terpene differed significantly, with the 1,8-cineole and cis -sabinene hydrate chemotypes having the lowest amounts of their respective main components, and the linalool chemotype having the highest. The , -terpinyl acetate chemotype had intermediate levels of its main terpene. A factor analysis revealed four factors which explained almost 89% of the total variation in plant essential oils. Each factor represented a separate chemotype, including a cis -sabinene hydrate, linalool, ,- terpinyl acetate and the new 1,8-cineole chemotype. Although the concept of plant chemotype is still valid, better definitions are important when evaluating the influences of a plant's secondary chemistry on other community members. Copyright © 2009 John Wiley & Sons, Ltd. [source] Older patients and delayed discharge from hospitalHEALTH & SOCIAL CARE IN THE COMMUNITY, Issue 6 2000Christina R. Victor BA M Phil PhD Hon MFPHM Abstract Older people (those aged 65 years and over) are the major users of health care services, especially acute hospital beds. Since the creation of the NHS there has been concern that older people inappropriately occupy acute hospital beds when their needs would be best served by other forms of care. Many factors have been associated with delayed discharge (age, sex, multiple pathology, dependency and administrative inefficiencies). However, many of these factors are interrelated (or confounded) and few studies have taken this into account. Using data from a large study of assessment of older patients upon discharge from hospital in England, this paper examines the extent of delayed discharge, and analyses the factors associated with such delays using a conceptual model of individual and organisational factors. Specifically, this paper evaluates the relative contribution of the following factors to the delayed discharge of older people from hospital: predisposing factors (such as age), enabling factors (availability of a family carer), vulnerability factors (dependency and multiple pathology), and organisational/administrative factors (referral for services, type of team undertaking assessments). The study was a retrospective patient case note review in three hospitals in England and included four hundred and fifty-six patients aged 75 years and over admitted from their own homes, and discharged from specialist elderly care wards. Of the 456 patients in the sample, 27% had a recorded delay in their discharge from hospital of three plus days. Multivariate statistical analysis revealed that three factors independently predicted delay in discharge: absence of a family carer, entry to a nursing/residential home, and discharge assessment team staffing. Delayed discharge was not related to the hypothesised vulnerability factors (multiple dependency and multiple pathology) nor to predisposing factors (such as age or whether the older person lived alone). The delayed discharge of older people from hospital is a topic of considerable policy relevance. Our study indicated that delay was independently related to two organisational issues. First, entry into long-term care entailed lengthy assessment procedures, uncertainty over who pays for this care, and waiting lists. Second, the nature of the team assessing people for discharge was associated with delay (the nurse-coordinated team made the fewest referrals for multidisciplinary assessments and had the longest delays). Additionally, the absence of a family carer was implicated in delay, which underlines the importance of family and friends in providing posthospital care and in maintaining older people in the community. Our study suggests that considerable delay in discharging older people from hospital originates from administrative/organisational issues; these were compounded by social services resource constraints. There is still much to be done therefore to improve coordination of care in order to provide a truly ,seamless service'. [source] Evaluation of spatial variability in snow water equivalent for a high mountain catchmentHYDROLOGICAL PROCESSES, Issue 3 2004S. P. Anderton Abstract Multivariate statistical analysis was used to explore relationships between catchment topography and spatial variability in snow accumulation and melt processes in a small headwater catchment in the Spanish Pyrenees. Manual surveys of snow depth and density provided information on the spatial distribution of snow water equivalent (SWE) and its depletion over the course of the 1997 and 1998 melt seasons. A number of indices expressing the topographic control on snow processes were extracted from a detailed digital elevation model of the catchment. Bivariate screening was used to assess the relative importance of these topographic indices in controlling snow accumulation at the start of the melt season, average melt rates and the timing of snow disappearance. This suggested that topographic controls on the redistribution of snow by wind are the most important influence on snow distribution at the start of the melt season. Furthermore, it appeared that spatial patterns of snow disappearance were largely determined by the distribution of snow water equivalent (SWE) at the start of the melt season, rather than by spatial variability in melt rates during the melt season. Binary regression tree models relating snow depth and disappearance date to terrain indices were then constructed. These explained 70,80% of the variance in the observed data. As well as providing insights into the influence of topography on snow processes, it is suggested that the techniques presented herein could be used in the parameterization of distributed snowmelt models, or in the design of efficient stratified snow surveys. Copyright © 2003 John Wiley & Sons, Ltd. [source] A coordinated approach to cutaneous wound healing: vibrational microscopy and molecular biologyJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 5b 2008K. L. Andrew Chan Abstract The repair of cutaneous wounds in the adult body involves a complex series of spatially and temporally organized processes to prevent infection and restore homeostasis. Three characteristic phases of wound repair (inflammation, proliferation including re-epithelialization and remodelling) overlap in time and space. We have utilized a human skin wound-healing model to correlate changes in genotype and pheno-type with infrared (IR) and confocal Raman spectroscopic images during the re-epithelialization of excisional wounds. The experimental protocols validated as IR images clearly delineate the keratin-rich migrating epithelial tongue from the collagen-rich wound bed. Multivariate statistical analysis of IR datasets acquired 6 days post-wounding reveal subtle spectral differences that map to distinct spatial distributions, which are correlated with immunofluorescent staining patterns of different keratin types. Images computed within collagen-rich regions expose complementary spatial patterns and identify elastin in the wound bed. The temporal sequence of events is explored through a comparison of gene array analysis with confocal Raman microscopy. Our approach demonstrates the feasibility of acquiring detailed molecular structure information from the various proteins and their subclasses involved in the wound-healing process. [source] Performance Evaluation of the Scent Transfer UnitÔ (STU-100) for Organic Compound Collection and ReleaseJOURNAL OF FORENSIC SCIENCES, Issue 4 2006Brian A. Eckenrode Ph.D. ABSTRACT: The Scent Transfer UnitÔ (STU-100) is a portable vacuum that uses airflow through a sterile gauze pad to capture a volatiles profile over evidentiary items for subsequent canine presentation to assist law enforcement personnel. This device was evaluated to determine its ability to trap and release organic compounds at ambient temperature under controlled laboratory conditions. Gas chromatography-mass spectrometry (GC-MS) analyses using a five-component volatiles mixture in methanol injected directly into a capture pad indicated that compound release could be detected initially and 3 days after the time of collection. Additionally, 15 compounds of a 39-component toxic organic gaseous mixture (10,1000 parts per billion by volume [p.p.b.v]) were trapped, released, and detected in the headspace of a volatiles capture pad after being exposed to this mixture using the STU-100 with analysis via GC-MS. Component release efficiencies at ambient temperature varied with the analyte; however, typical values of c. 10% were obtained. Desorption at elevated temperatures of reported human odor/scent chemicals and colognes trapped by the STU-100 pads was measured and indicated that the STU-100 has a significant trapping efficiency at ambient temperature. Multivariate statistical analysis of subsequent mass spectral patterns was also performed. [source] Using multivariate statistical methods to model the electrospray ionization response of GXG tripeptides based on multiple physicochemical parametersRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2009M. A. Raji Response factors were determined for twelve GXG peptides (where G stands for glycine and X is any of alanine [A], arginine [R], asparagine [N], aspartic acid [D], glycine [G], histidine [H], leucine [L], lysine [K], phenylalanine [F], serine [S], tyrosine [Y], valine [V]) by electrospray ionization mass spectrometry (ESI-MS). The response factors were measured using a novel flow injection method. This new method is based on the Gaussian distribution of analyte concentration resulting from band-broadening dispersion experienced by the analyte upon passage through an extended volume of PEEK tubing. This method removes the need for preparing a discrete series of standard solutions to assess concentration-dependent response. Relative response factors were calculated for each peptide with reference to GGG. The observed trends in the relative response factors were correlated with several analyte physicochemical parameters, chosen based on current understanding of ion release from charged droplets during the ESI process. These include analyte properties: nonpolar surface area; polar surface area; gas-phase basicity; proton affinity; and Log D. Multivariate statistical analysis using multiple linear regression, decision tree, and support vector regression models were investigated to assess their potential for predicting ESI response based on the analyte properties. The support vector regression model was more versatile and produced the least predictive error following 12-fold cross-validation. The effect of variation in solution pH on the relative response factors is highlighted, as evidenced by the different predictive models obtained for peptide response at two pH values (pH,=,6.0 and 9.0). The relationship between physicochemical parameters and associated ionization efficiencies for GXG tripeptides is discussed based on the equilibrium partitioning model. Copyright © 2009 John Wiley & Sons, Ltd. [source] Two-dimensional gel electrophoresis-based proteomic analysis of the Medicago truncatula,rust (Uromyces striatus) interactionANNALS OF APPLIED BIOLOGY, Issue 2 2010M.Á. Castillejo A two-dimensional gel electrophoresis (2-DE) based proteomic approach has been used to study the Medicago truncatula,Uromyces striatus interaction. The 2-DE leaf protein profile of three M. truncatula genotypes displaying different phenotypes (susceptible and showing prehaustorial and posthaustorial resistance) in both noninoculated and inoculated plants have been compared. Multivariate statistical analysis identified 63 differential protein spots under the experimental conditions (genotypes/treatments). Variable spots were subjected to tandem mass spectrometry (MS, matrix-assisted laser desorption ionisation time of flight, MALDI-TOF/TOF) analysis to identify their possible functions. A total of 27 proteins were identified using a combination of peptide mass fingerprinting (PMF) and MSMS fragmentation. Most of these observed changes correspond to enzymes involved in photosynthesis, energy metabolic pathways and stress related, whose pattern expression was different in relation to susceptibility/resistance of the genotypes studied. Results obtained in this work suggest that differences observed could be related to efficiency in energy utilisation and the induction of proteins involved in defence mechanism operating during early stages of infection. [source] Quality of protein crystal structuresACTA CRYSTALLOGRAPHICA SECTION D, Issue 9 2007Eric N. Brown The genomics era has seen the propagation of numerous databases containing easily accessible data that are routinely used by investigators to interpret results and generate new ideas. Most investigators consider data extracted from scientific databases to be error-free. However, data generated by all experimental techniques contain errors and some, including the coordinates in the Protein Data Bank (PDB), also integrate the subjective interpretations of experimentalists. This paper explores the determinants of protein structure quality metrics used routinely by protein crystallographers. These metrics are available for most structures in the database, including the R factor, Rfree, real-space correlation coefficient, Ramachandran violations etc. All structures in the PDB were analyzed for their overall quality based on nine different quality metrics. Multivariate statistical analysis revealed that while technological improvements have increased the number of structures determined, the overall quality of structures has remained constant. The quality of structures deposited by structural genomics initiatives are generally better than the quality of structures from individual investigator laboratories. The most striking result is the association between structure quality and the journal in which the structure was first published. The worst offenders are the apparently high-impact general science journals. The rush to publish high-impact work in the competitive atmosphere may have led to the proliferation of poor-quality structures. [source] Assessment and Statistics of Surgically Induced AstigmatismACTA OPHTHALMOLOGICA, Issue thesis1 2008Kristian Næser Abstract. The aim of the thesis was to develop methods for assessment of surgically induced astigmatism (SIA) in individual eyes, and in groups of eyes. The thesis is based on 12 peer-reviewed publications, published over a period of 16 years. In these publications older and contemporary literature was reviewed1. A new method (the polar system) for analysis of SIA was developed. Multivariate statistical analysis of refractive data was described2,4. Clinical validation studies were performed. The description of a cylinder surface with polar values and differential geometry was compared. The main results were: refractive data in the form of sphere, cylinder and axis may define an individual patient or data set, but are unsuited for mathematical and statistical analyses1. The polar value system converts net astigmatisms to orthonormal components in dioptric space. A polar value is the difference in meridional power between two orthogonal meridians5,6. Any pair of polar values, separated by an arch of 45 degrees, characterizes a net astigmatism completely7. The two polar values represent the net curvital and net torsional power over the chosen meridian8. The spherical component is described by the spherical equivalent power. Several clinical studies demonstrated the efficiency of multivariate statistical analysis of refractive data4,9,11. Polar values and formal differential geometry describe astigmatic surfaces with similar concepts and mathematical functions8. Other contemporary methods, such as Long's power matrix, Holladay's and Alpins' methods, Zernike12 and Fourier analyses8, are correlated to the polar value system. In conclusion, analysis of SIA should be performed with polar values or other contemporary component systems. [source] Assessment of shallow landslide susceptibility by means of multivariate statistical techniquesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2001Cristina Baeza Abstract Several multivariate statistical analyses have been performed to identify the most influential geological and geomorphological parameters on shallow landsliding and to quantify their relative contribution. A data set was first prepared including more than 30 attributes of 230 failed and unfailed slopes. The performance of principal component analysis, t-test and one-way test, allowed a preliminary selection of the most significant variables, which were used as input variables for the discriminant analysis. The function obtained has classified successfully 88·5 per cent of the overall slope population and 95·6 per cent of the failed slopes. Slope gradient, watershed area and land-use appeared as the most powerful discriminant factors. A landslide susceptibility map, based on the scores of the discriminant function, has been prepared for Ensija range in the Eastern Pyrenees. An index of relative landslide density shows that the results of the map are consistent. Copyright © 2001 John Wiley & Sons, Ltd. [source] A multivariate analysis of the outcome of endodontic treatmentEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2004Dag Ørstavik In the present study, multivariate analyses were performed on clinical and treatment variables that may influence the outcome of endodontic treatment. Data collected in a previous clinical-radiographic follow-up study were used. Of 810 treated, 675 roots in 498 teeth were followed for 6 months to 4 yr. Of these, 192 (the CAP group) had pre-existing, chronic apical periodontitis and 483 (the NAP group) had not. Root canal treatment followed a standard procedure with one of three sealers chosen at random. Demographic, clinical and radiographic variables were recorded at the start of, and during treatment. The periapical index (PAI) score was used to record the outcome of treatment, and applied in two different endpoint modes (END1 and END2) as the dependent variable for multivariate statistical analyses using logistic regression and the general model. The modes reflected increasing PAI scores (END1) and conventional success/failure assessment (END2). Dropouts were largely similar to the cases followed up. A total of 10 preoperative and peroperative variables were found to be significantly associated with treatment outcome by the multivariate analyses of either the total material or the NAP or CAP subgroups. Several of these were not significant in univariate analyses (e.g. the effect of sealer). Conventional success/failure analyses (END2) identified fewer of the influential variables and had low explanatory power, whereas PAI scores on an ordinal scale (END1) were most sensitive in identifying variables of influence on the treatment outcome. [source] Use of chemical tracers to assess diet and persistent organic pollutants in Antarctic Type C killer whalesMARINE MAMMAL SCIENCE, Issue 3 2008Margaret M. Krahn Abstract Measuring chemical tracers in tissues of marine predators provides insight into the prey consumed and the predator's contaminant exposure. In this study, samples from Type C killer whales (Orcinus orca) biopsied in Antarctica were analyzed for chemical tracers (i.e., stable isotopes of carbon and nitrogen, fatty acids, and persistent organic pollutants [POPs]). Profiles of these individual tracers were very different from those of killer whale populations that have been studied in the eastern North and eastern Tropical Pacific. For example, ,13C and ,15N stable isotope values and most POP concentrations were significantly lower in the Antarctic population. In addition, multivariate statistical analyses of both fatty acid and POP profiles found distinctly different patterns for Antarctic Type C whales compared to those from whales in the other populations. Similar assays were conducted on four species of Antarctic marine fish considered potential prey for Type C killer whales. Results were consistent with a diet of fish for Type C whales, but other species (e.g., low trophic-level marine mammals or penguins) could not be eliminated as supplemental prey. [source] Biogeography of the ubiquitous marine bacterium Alteromonas macleodii determined by multilocus sequence analysisMOLECULAR ECOLOGY, Issue 18 2008ELENA IVARS-MARTÍNEZ Abstract Twenty-three isolates of the widely distributed marine bacteria Alteromonas macleodii have been analysed by multilocus sequence analysis combined with phylogenetic and multivariate statistical analyses. The strains originated from the Pacific Ocean, Mediterranean Sea, English Channel, Black Sea and Thailand. Using the nucleotide sequences of nine loci for each of the 23 isolates, a robust identification was achieved of different clades within the single species. Strains generally clustered with the depth in the water column from which the isolate originated. Strains also showed more recombination with isolates from the same vicinity, suggesting that genetic exchange plays a role in diversification of planktonic marine prokaryotes. This study thus shows for the first time for a large set of isolates of a species of planktonic marine prokaryotes that multilocus sequence analysis overcomes the problems associated with the analysis of individual marker genes or presence of extensive recombination events. It can thus achieve intraspecific identification to the level of genotypes and, by comparison with relevant environmental data, ecotypes. [source] Floristic diversity in fragmented Afromontane rainforests: Altitudinal variation and conservation importanceAPPLIED VEGETATION SCIENCE, Issue 3 2010Christine B. Schmitt Abstract Question: How does the floristic diversity of Afromontane rainforests change along an altitudinal gradient? What are the implications for conservation planning in these strongly fragmented forest areas that form part of the Eastern Afromontane Biodiversity Hotspot? Location: Bonga, southwestern Ethiopia. Methods: Based on evidence from other montane forests, we hypothesized that altitude has an effect on the floristic diversity of Afromontane rainforests in southwestern Ethiopia. To test this hypothesis, detailed vegetation surveys were carried out in 62 study plots located in four relatively undisturbed forest fragments situated at altitudes between 1600 m and 2300 m. Floristic diversity was evaluated using a combination of multivariate statistical analyses and diversity indices. Results: Ordination and indicator species analyses showed gradual variations in floristic diversity along the altitudinal gradient with a pronounced shift in species composition at ca. 1830 m. Upper montane forest (>1830 m) is characterized by high fern diversity and indicator species that are Afromontane endemics. Lower montane forest (<1830 m) exhibits a greater diversity of tree species and a higher abundance of the flagship species Coffea arabica. Conclusions: Our results provide crucial ecological background information concerning the montane rainforests of Ethiopia, which have been poorly studied until now. We conclude that both forest types identified during this study need to be considered for conservation because of their particular species compositions. Owing to the high degree of forest fragmentation, conservation concepts should consider a multi-site approach with at least two protected areas at different altitudinal levels. [source] Rapid monitoring of recombinant antibody production by mammalian cell cultures using fourier transform infrared spectroscopy and chemometricsBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2010Christopher A. Sellick Abstract Fourier transform infrared (FT-IR) spectroscopy combined with multivariate statistical analyses was investigated as a physicochemical tool for monitoring secreted recombinant antibody production in cultures of Chinese hamster ovary (CHO) and murine myeloma non-secreting 0 (NS0) cell lines. Medium samples were taken during culture of CHO and NS0 cells lines, which included both antibody-producing and non-producing cell lines, and analyzed by FT-IR spectroscopy. Principal components analysis (PCA) alone, and combined with discriminant function analysis (PC-DFA), were applied to normalized FT-IR spectroscopy datasets and showed a linear trend with respect to recombinant protein production. Loadings plots of the most significant spectral components showed a decrease in the C,O stretch from polysaccharides and an increase in the amide I band during culture, respectively, indicating a decrease in sugar concentration and an increase in protein concentration in the medium. Partial least squares regression (PLSR) analysis was used to predict antibody titers, and these regression models were able to predict antibody titers accurately with low error when compared to ELISA data. PLSR was also able to predict glucose and lactate amounts in the medium samples accurately. This work demonstrates that FT-IR spectroscopy has great potential as a tool for monitoring cell cultures for recombinant protein production and offers a starting point for the application of spectroscopic techniques for the on-line measurement of antibody production in industrial scale bioreactors. Biotechnol. Bioeng. 2010; 106: 432,442. © 2010 Wiley Periodicals, Inc. [source] Histopathological characterization of primary cutaneous melanoma using infrared microimaging: a proof-of-concept studyBRITISH JOURNAL OF DERMATOLOGY, Issue 6 2010E. Ly Summary Background, The diagnosis of malignant melanoma is based upon the histological evaluation of the lesion. As such, the morphological interpretation relies on the expertise of a dermatopathologist. Infrared microimaging is emerging as a new powerful tool to investigate tissue biochemistry. Infrared spectra probe the biochemical constitution of the sample and are real tissue-specific spectroscopic fingerprints. Objectives, To assess the potential of infrared microimaging to aid in the analysis of tissue sections from primary cutaneous melanomas. Methods, Ten samples of melanoma sections from the main histological subtypes were investigated using infrared microimaging combined with multivariate statistical analyses. Results, This methodology yielded highly contrasted colour-coded images that permitted to highlight tissue architecture without any staining. It was possible to discriminate tumour areas from normal epidermis automatically, and intratumoral heterogeneity as revealed by our approach was correlated with the aggressiveness of the tumour. Conclusions, This proof-of-concept study shows that infrared microimaging could help in the diagnosis of primary cutaneous melanoma. [source] The intratumoral distribution of nuclear ,-catenin is a prognostic marker in colon cancerCANCER, Issue 10 2009David Horst MD Abstract BACKGROUND: Most colon cancers harbor mutations of APC or ,-catenin, both of which may lead to nuclear ,-catenin accumulation in the tumor cells and constitutively activated expression of its target genes. In many colon cancers, however, nuclear ,-catenin accumulation is heterogeneous throughout the tumor and often confined to the tumor margin. Herein, the authors investigated whether the intratumoral distribution of nuclear ,-catenin can serve as a prognostic marker for survival and tumor progression of stage IIA colon cancer patients. METHODS: In total, 142 patients with primarily resected, moderately differentiated stage IIA colon cancer were included in this study. The patterning of nuclear ,-catenin expression was evaluated on immunohistochemically stained whole tissue sections of the tumors and was correlated with cancer-specific survival and disease-free survival using univariate and multivariate statistical analyses. RESULTS: Four distinct patterns of nuclear ,-catenin expression were identified, and 2 main categories comprising tumors with or without intratumoral regulation of nuclear ,-catenin were distinguished. Moreover, the results demonstrated that the patterning, and especially the regulation or absence of regulation of nuclear ,-catenin expression, was a strong predictive marker of patient survival and tumor progression. CONCLUSIONS: The current results indicated that the distribution of nuclear ,-catenin expression can be used as a good prognostic marker in patients with stage IIA colon cancer. Thus, the evaluation of nuclear ,-catenin may help to identify patients who will have a shorter than average survival and patients with a greater risk of disease progression who may be considered for adjuvant therapeutic modalities and intensified clinical aftercare in the future. Cancer 2009. © 2009 American Cancer Society. [source] Donor age and gestational age influence on growth factor levels in human amniotic membraneACTA OPHTHALMOLOGICA, Issue 6 2010Maria J. López-Valladares Acta Ophthalmol. 2010: 88: e211,e216 Abstract. Purpose:, Amniotic membrane (AM) is used as a biomaterial for reconstruction in ocular surface surgery. This study investigated the influence of interdonor variations and processing and preservation procedures applied to the AM on growth factors and protein levels. Methods:, Samples of human AM from thirteen donors were analysed. Collected donor data were age, parity and gestational age. Total protein amount was measured in extracts of intact AM nonpreserved, lyophilized and cryopreserved, at ,80°C and in liquid nitrogen. An enzyme-linked immunosorbent assay (ELISA) was used to assay growth factors protein levels for epidermal growth factor, basic fibroblast growth factor (bFGF), hepatocyte growth factor (HGF), keratinocyte growth factor (KGF), transforming growth factor beta1 (TFG-,1) and nerve growth factor (NGF). Univariate and multivariate statistical analyses were used to study the influence of the preservation method applied and interdonor variations on growth factors levels. Results:, We detected important variations in growth factors and protein concentrations between samples from different donors. Total protein amount, bFGF, HGF, KGF and TGF-,1 showed lower levels in samples from donors with higher gestational ages and donor ages, for all groups. Conclusion:, The variability in the biochemical composition of AM from different donors is considerable, and it is related with donor factors as donor age and gestational age. As AM biochemical composition has a role in its therapeutic effects, these variations could affect the clinical results of amniotic membrane transplantation and must be taken into account in donor selection processes. [source] Length of stay and procedure utilization are the major determinants of hospital charges for heart failureCLINICAL CARDIOLOGY, Issue 1 2001Edward F. Philbin M.D.Facc Abstract Background: Most of the 10 billion dollars spent annually on heart failure (HF) management in this country is attributed to hospital charges. There are widespread efforts to decrease the costs of treating this disorder, both by preventing hospital admissions and reducing lengths of stay (LOS). Methods: Administrative information on all 1995 New York State hospital discharges assigned ICD-9-CM codes indicative of HF in the principal diagnosis position were obtained. Bivariate and multivariate statistical analyses were utilized to determine those patient- and hospital-specific characteristics which had the greatest influence on hospital charges. Results: In all, 43,157 patients were identified. Mean hospital charges were $11,507 ± 15,995 and mean hospital LOS was 9.6 ± 14.5 days. With multivariate analyses, the most significant independent predictors of higher hospital charges were longer LOS, admission to a teaching hospital, treatment in an intensive care unit, and the utilization of cardiac surgery, permanent pacemakers, and mechanical ventilation. Age, gender, race, comorbidity score, and medical insurance, as well as treatment by a cardiologist and death during the index hospitalization were not among the most significant predictors. Conclusions: We conclude that LOS and procedure utilization are the major determinants of hospital charges for an acute episode of inpatient HF care. Reducing LOS and other initiatives to restructure hospital-based HF care may reduce total health care costs for HF. [source] Evaluation of malignant and benign gastric biopsy specimens by mRNA expression profile and multivariate statistical methodsCYTOMETRY, Issue 5 2007Orsolya Galamb Abstract Background: mRNA expression array and multivariate statistical analysis of gastric biopsies can yield insight into the molecular biology basis of local alterations, supporting expression-based identification of morphological alterations. Methods: From 11 patients with erosive gastritis(EG), 5 with adenocarcinoma (GC), 11 with atrophic gastritis (AG) gastric biopsies were collected, total RNA isolated, T7 amplification and expression analysis of 1047 mRNAs was performed using commercial glass arrays (Clontech, USA). After microarray quality control, applicable data were available from 7 EG, 4 GC, and 5 AG. Multivariate statistical and cell functional analysis were performed. Real-time RT-PCR and immunohistochemistry were used for validation. Results: GC was characterized by overregulated v-raf, v-erb-a, BCL2-associated- athanogene, immediate-early-response-3, Polo-like kinase, CDK-2, cyclin-C, Pin1 genes, and downregulated ADP-ribosyltransferase, sialophorin and DCC. AG cases had increased PDGF-receptor, TGF-,-receptor-3, and decreased death-associated-protein-3, ,-1-catenin, topoisomerase-1 levels. In EG upregulation of IGF-receptor-1, CD9, transferrin receptor, integrins, and underexpression of keratin-5, caspase-4 was found. Discriminant analysis could reclassify all samples correctly using four parameters. Conclusions: mRNA expression array analysis of gastric biopsies yields previously known and new data in the evaluation of local gastric alterations. © 2007 Clinical Cytometry Society [source] Prediction of fire classification for wood based products.FIRE AND MATERIALS, Issue 3 2007A multivariate statistical approach based on the cone calorimeter Abstract Wood has long traditions as a building material, and is often used in construction elements, and as interior and exterior surfaces in the Nordic countries. In most applications, there are reaction to fire requirements to products used as surfaces, e.g. in escape routes and larger public spaces. Most wood products will therefore have to be treated with fire retardant (FR) agents to fulfil the strict requirements to properties connected to heat release and flame spread. Unfortunately, FR agents usually also increase the smoke production, as they cause a more incomplete combustion of the wood. The wood product manufacturers seek to find the optimal amount of FR additives where both heat release and smoke production in the classifying test are within the requirements given in the building regulations. This paper describes models for prediction of the European reaction to fire classes of wood products. The models are based on multivariate statistical analysis, and use test results from the cone calorimeter test as input. The presented models are, with very good precision, able to predict which Euroclass and additional smoke class a wood based product would obtain if it were to be tested in the single burning item test. Copyright © 2006 John Wiley & Sons, Ltd. [source] Prediction of heat release in the single burning item testFIRE AND MATERIALS, Issue 2 2002Anne Steen Hansen This paper presents a modification of an existing mathematical model that uses cone calorimeter test results to predict heat release rate in the single burning item (SBI) test. A method for classification of cases based on multivariate statistical analysis is incorporated in the modified model. This makes it possible to determine the development of the heat release curve in the SBI test with better precision than the original version was able to. The model has been applied to 100 cases of cone calorimeter test results from 33 different products. For most of the products the predicted shape and level of the heat release curves are close to measurements in the SBI test. Using the predicted heat release results as input to calculation of FIGRA0.2MJ and THR600s within the new European system for reaction-to-fire classification, we were able to predict membership of the correct class in 90% of the analysed cases. Copyright © 2002 John Wiley & Sons, Ltd. [source] Incorporating affective customer needs for luxuriousness into product design attributesHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 2 2009Sangwoo Bahn In a highly competitive market, customers' product affection is a critical factor to product success. However, understanding customers' affective needs is difficult to grasp; product design practitioners often misunderstand what customers really want. In this study we report our experience in developing and using an affective design framework that identified critical affective features customers have on products and are systematically incorporated into product design attributes. To identify key affective features such as luxuriousness, we utilized the Kansei engineering methodology. This approach consists of three steps: (1) selecting related affective features and product design attributes through a comprehensive literature survey, expert panel opinion, and focus group interviews; (2) conducting evaluation experiments; and (3) developing Kansei models using multivariate statistical analysis and analyzing critical product design attributes. To demonstrate applicability of the proposed affective design framework, 30 customers and 30 product design practitioners participated in an evaluation experiment for car crash pads, and 44 customers and 20 designers participated in an evaluation experiment for two interior room products (wallpapers and flooring materials). The evaluation experiments were conducted via systematically developed questionnaires consisting of a 7-point semantic differential scale and a 100-point magnitude estimation scale. The results of the experiments were analyzed using principal component regression and quantification theory type I method. Using the analyzed survey data, the relationship between luxuriousness and related affective features and product design attributes were identified. This relationship indicated that there was a significant difference in the perception of luxuriousness between customers and designers. Consequently, it is expected that the results of this study could provide a foundation for developing affective products. © 2009 Wiley Periodicals, Inc. [source] Hepatitis B and C virus infection in Crohn's diseaseINFLAMMATORY BOWEL DISEASES, Issue 4 2001Dr. Livia Biancone Abstract Patients with Crohn's disease (CD) are at higher risk of hepatitis C (HCV) and B virus (HBV) infection, because of surgical and/or endoscopic procedures. However, the prevalence of HCV and HBV infection in CD is unknown. This issue may be relevant because of the growing use of immunomodulatory drugs in CD. The purpose of this study was to assess, in a multicenter study, the prevalence and risk factors of HCV and HBV infection in CD. The effect of immunomodulatory drugs for CD on the clinical course of hepatitis virus infections and of interferon-, (IFN-,) on the course of CD was examined in a small number of patients. Sera from 332 patients with CD and 374 control subjects (C) were tested for the following: hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (HBsAb), HBcAb, HBeAg, HBeAb, anti-HCV, and HCV-RNA. An additional 162 patients with ulcerative colitis (UC) were tested as a disease control group. Risk factors were assessed by multivariate statistical analysis. Infection by either HCV or HBV was detected in 24.7% of patients with CD. In the age groups younger than 50 years, HCV prevalence was higher in CD than in C (p = 0.01). HCV infection in CD was associated with surgery (OR 1.71; 95% CI 1.00,2.93; p = 0.04), blood transfusions (OR 3.39; 95% CI 1.04,11.04; p = 0.04), and age (OR 2.3; 95% CI 1.61,3.56; p < 0.001). The event CD-related surgery appeared to be the main risk factor for HCV infection in CD. HCV prevalence was higher in CD (7.4%) than in UC (0.6%) (p = 0.001). HBcAb positivity was higher in CD (10.9%) and UC (11.5%) than in C (5.1%) (CD vs. C: p = 0.016; UC vs. C: p = 0.02), associated with age (OR 2.08; 95% CI 1.37,3.17; p = 0.001) and female gender (OR 2.68; 95% CI 1.37,3.17; p = 0.001) in CD and to UC duration (OR 1.20; 95% CI 1.06,1.36; p = 0.002). Immunomodulatory drugs did not influence the course of HBV or HCV infection in seven patients with CD, and IFN-, for chronic hepatitis C did not affect CD activity in six patients with CD. It is concluded that HBV prevalence is higher in CD than in C at all ages, whereas HCV prevalence is increased in young patients with CD, because of a greater need for surgery. The higher HCV (but not HBV) prevalence in CD than in UC suggests that the host immune response may influence the risk of HCV infection. Although a relatively high proportion of patients with CD showed HBV and/or HCV infections, this should not influence treatment strategies for CD. [source] Alteration of subcellular and cellular expression patterns of cyclin B1 in renal cell carcinoma is significantly related to clinical progression and survival of patientsINTERNATIONAL JOURNAL OF CANCER, Issue 4 2006Stephen O. Ikuerowo Abstract Cyclin B1, identified as a regulator of late cell cycle, is involved in the development and progression of a variety of human malignancies. To clarify the role of cyclin B1 in the pathogenesis and prognosis of renal cell carcinoma (RCC), protein expression was compared with clinicopathological characteristics of patients as well as the long-term survival after surgical therapy. Expression analysis was carried out by immunohistochemistry and tissue microarray analysis. The microarrays that represented the primary tumors, their invasion front and normal peritumoral renal parenchyma contained 753 tissue cores obtained from 251 randomly selected nephrectomy specimens. Immunopositivity within the primary tumors was significantly associated with tumor stage (pT) (p < 0.01), lymph node status (pN) (p < 0.01) as well as the presence of systemic metastatic disease (p = 0.01). Subcellular expression in the cytoplasm of tumor cells significantly correlated with pT (p = 0.02) and pN (p = 0.03). When peritumoral tissue samples exhibited a relative amount of <10% of positively reacting epithelial cells, cyclin B positivity was identified to predict long-term survival of patients in univariate analysis (p < 0.01) whereas borderline significance was observed in multivariate statistical analysis (p = 0.05). Increased intratumoral cyclin B1 positivity and aberrant localization of signals within the cytoplasm of tumor cells is positively correlated with the tendency towards tumor progression, indicating the significant role of cyclin B1 in the development and pathogenesis of RCC. The result of uni- and multivariate statistical analysis suggests the prognostic value of cyclin B1 for RCC patients. © 2006 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||