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Multivariate Statistics (multivariate + statistics)
Selected AbstractsApplied Multivariate Statistics for the Social Sciences, Fifth Edition by James P. StevensINTERNATIONAL STATISTICAL REVIEW, Issue 3 2009Andreas Rosenblad No abstract is available for this article. [source] The Contribution of Jürgen Läuter to Multivariate StatisticsBIOMETRICAL JOURNAL, Issue 6 2005Siegfried Kropf No abstract is available for this article. [source] Metabolites from cerebrospinal fluid in aneurysmal subarachnoid haemorrhage correlate with vasospasm and clinical outcome: a pattern-recognition 1H NMR studyNMR IN BIOMEDICINE, Issue 1 2005Victoria G. Dunne Abstract Following subarachnoid haemorrhage the most significant complication is sustained cerebral vascular contraction (vasospasm), which may result in terminal brain damage from cerebral infarction. Despite this, the biochemical cause of vasospasm remains poorly understood. In this study, the global high-concentration metabolite composition of CSF has been correlated with patient outcome after subarachnoid haemorrhage using multivariate statistics and 1H NMR spectroscopy. In total, 16 patients with aneurysmal subarachnoid haemorrhage (aSAH) were compared with 16 control patients who required a procedure where CSF was obtained but did not have aSAH. Multivariate statistics readily distinguished the aSAH group from the heterogeneous control group, even when only those controls with blood contamination in the CSF were used. Using principal components analysis and orthogonal signal correction, vasospasm was correlated to the concentrations of lactate, glucose and glutamine. These pattern recognition models of the NMR data also predicted Glasgow Coma Score (54% within ±,1 of the actual score on a scale of 1,15 for the whole patient group), Hunt and Hess SAH severity score (88% within ±,1 of the actual score on a scale of 1,5 for the aSAH group) and cognitive outcome scores (78% within ±,3 of the actual score on a 100% scale for the whole patient group). Thus, the approach allowed the prediction of outcome as well as confirming the presence of aSAH. Copyright © 2004 John Wiley & Sons, Ltd. [source] Are the gorillas in Bwindi Impenetrable National Park "true" mountain gorillas?AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2010Alison A. Elgart Abstract The gorillas that inhabit Bwindi Impenetrable National Park in Uganda are the least known of the eastern gorillas. Because they are an allopatric population living a minimum of 25 km from the well-studied population of mountain gorillas (Gorilla beringei beringei) in Rwanda and have certain morphological and ecological differences from these gorillas, their taxonomic status has been in question in recent years. This study presents new craniodental metrics from Bwindi individuals and compares them to Virunga individuals as well as to eastern lowland gorillas, G. gorilla graueri. Multivariate statistics, including MANCOVA, least-squares, regression, and principal components analyses, were used to evaluate how closely the Bwindi crania resemble the Virunga crania and how both relate to G. g. graueri. Results indicate that the Bwindi gorillas have generally smaller crania than the Virunga gorillas, but when metrics are log-transformed, the only variable that distinguishes the Bwindi individuals is a longer face. When both populations are compared to G. g. graueri, they cluster together separately from the eastern lowland gorillas, sharing such features as higher rami, wider bigonia, longer mandibles, and wider and shorter mandibular symphyses in relation to G. g. graueri. Functional morphological explanations for these differences are discussed, but lacking measurements of the physical properties of G. g. graueri, they cannot fully be explained. Results clearly indicate that at least pertaining to the cranium, upon which most gorilla taxonomy is based, the Bwindi gorillas are proper mountain gorillas (G. b. beringei). Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Morphological variation of the five vole species of the genus Microtus (Mammalia, Rodentia, Arvicolinae) occurring in GreeceACTA ZOOLOGICA, Issue 3 2009Stella E. Fraguedakis-Tsolis Abstract Morphometric data for the five vole species of the genus Microtus living in Greece are old, sparse, poor and insufficiently analysed. This work aims to give the first comprehensive morphometric analysis of body and skull inter- and intraspecific variation for M. (M.) guentheri, M. (M.) rossiaemeridionalis, M. (Terricola) subterraneus, M. (T.) felteni and M. (T.) thomasi, applying multivariate statistics to 28 linear morphometric variables. It was based on ample material (202 adult individuals) using samples from localities that adequately cover the entire distributional range of each species in Greece. The five species and the two subgenera (Microtus and Terricola) were morphometrically clearly distinguished and discriminating variables were revealed. However, morphometrics did not provide robust criteria to infer phylogenetic relations among species. Furthermore, three species, M. (M.) guentheri, M. (M.) rossiaemeridionalis and M. (T.) thomasi, exhibited considerable intraspecific size or shape variation, which was mostly random and not associated with geographical proximity. Comparisons with data in the literature, mainly concerning populations of these species from adjacent areas, indicate that the Greek M. (M.) guentheri, M. (M.) rossiaemeridionalis and M. (T.) thomasi tend to be smaller than their conspecifics, while M. (T.) subterraneus and M. (T.) felteni are about equal in size to their Balkan relatives. [source] The 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] Effects of plant diversity, plant productivity and habitat parameters on arthropod abundance in montane European grasslandsECOGRAPHY, Issue 4 2005Jörg Perner Arthropod abundance has been hypothesized to be correlated with plant diversity but the results of previous studies have been equivocal. In contrast, plant productivity, vegetation structure, abiotic site conditions, and the physical disturbance of habitats, are factors that interact with plant diversity, and that have been shown to influence arthropod abundance. We studied the combined effect of plant species diversity, productivity and site characteristics on arthropod abundance in 71 managed grasslands in central Germany using multivariate statistics. For each site we determined plant species cover, plant community biomass (productivity), macro- and micronutrients in the soil, and characterized the location of sites with respect to orographic parameters as well as the current and historic management regimes. Arthropods were sampled using a suction sampler and classified a priori into functional groups (FGs). We found that arthropod abundance was not correlated with plant species richness, effective diversity or Camargo's evenness, even when influences of environmental variables were taken into account. In contrast, plant community composition was highly correlated with arthropod abundances. Plant community productivity influenced arthropod abundance but explained only a small proportion of the variance. The abundances of the different arthropod FGs were influenced differentially by agricultural management, soil characteristics, vegetation structure and by interactions between different FGs of arthropods. Herbivores, carnivores and detritivores reacted differently to variation in environmental variables in a manner consistent with their feeding mode. Our results show that in natural grassland systems arthropod abundance is not a simple function of plant species richness, and they emphasize the important role of plant community composition for the abundance patterns of the arthropod assemblages. [source] Structural diversity of bacterial communities in a heavy metal mineralized granite outcropENVIRONMENTAL MICROBIOLOGY, Issue 3 2006Deirdre Gleeson Summary This laboratory study of a variably mineralized and hydrothermally altered granite outcrop investigated the influences of rock-surface chemistry and heavy metal content on resident bacterial populations. Results indicated that elevated heavy metal concentrations had a profound impact on bacterial community structure, with strong relationships found between certain ribotypes and particular chemical/heavy metal elements. Automated ribosomal intergenic sequence analysis (ARISA) was used to assess the nature and extent of bacterial diversity, and this was combined with chemical analysis and multivariate statistics to identify the main geochemical factors influencing bacterial community structure. A randomization test revealed significant changes in bacterial structure between samples, while canonical correspondence analysis (CCA) related each individual ARISA profile to linear combinations of the chemical variables (mineralogy, major element and heavy metal concentrations) revealing the geochemical factors that correlated with changes in the ARISA data. anova was performed to further explore interactions between individual ribotypes and chemical/heavy metal composition, and revealed that a high proportion of ribotypes correlated significantly with heavy metals. [source] Critical reappraisal of referrals to electromyography and nerve conduction studies,EUROPEAN JOURNAL OF NEUROLOGY, Issue 2 2005S. Podnar A large number of examinees referred to electromyographic (EMG) laboratories do not have symptoms or signs suggestive of a peripheral nervous system disorder, and the aim of the present study was to check this. All examinees evaluated by the author in a ,general' EMG laboratory in the first 4 months of 2002 were included. Data on examinees, referral physicians and diagnoses, clinical symptoms and signs, and electrodiagnostic findings were statistically evaluated. Three hundred examinees, 42% men, were included. A neurological diagnosis was provided in 55% of referrals. Electrodiagnostic abnormalities were found in 45% of examinees. Using multivariate statistics, a positive effect of neurological referral diagnosis, history of paraesthesias and of weakness and sensory loss on examination, and a negative effect of history of pain on pathological electrodiagnostic findings were found. Except 20 patients with carpal tunnel syndrome, no patient with normal clinical examination had abnormal electrodiagnostic findings. Our study confirmed the inappropriateness of referrals to electrodiagnostic examination to screen patients for peripheral nervous disorders. We propose electrodiagnostic examination mainly of patients with unequivocal clinical signs of a peripheral nervous system lesion and of patients with typical symptoms of the carpal tunnel syndrome. [source] Sulfate-reducing bacterial community response to carbon source amendments in contaminated aquifer microcosmsFEMS MICROBIOLOGY ECOLOGY, Issue 1 2002Jutta Kleikemper Abstract Microbial sulfate reduction is an important metabolic activity in many reduced habitats. However, little is known about the sulfate-reducing communities inhabiting petroleum hydrocarbon (PHC)-contaminated freshwater aquifer sediments. The purpose of this study was to identify the groups of sulfate-reducing bacteria (SRB) selectively stimulated when sediment from a PHC-contaminated freshwater aquifer was incubated in sulfate-reducing aquifer microcosms that were amended with specific carbon sources (acetate, butyrate, propionate, lactate, and citrate). After 2 months of incubation, the SRB community was characterized using phospholipid fatty acid (PLFA) analysis combined with multivariate statistics as well as fluorescence in situ hybridization (FISH). Molybdate was used to specifically inhibit SRB in separate microcosms to investigate the contribution of non-SRB to carbon source degradation. Results indicated that sulfate reduction in the original sediment was an important process but was limited by the availability of sulfate. Substantially lower amounts of acetate and butyrate were degraded in molybdate treatments as compared to treatments without molybdate, suggesting that SRB were the major bacterial group responsible for carbon source turnover in microcosms. All of the added carbon sources induced changes in the SRB community structure. Members of the genus Desulfobulbus were present but not active in the original sediment but an increase of the fatty acids 15:1,6c and 17:1,6c and FISH results showed an enrichment of these bacteria in microcosms amended with propionate or lactate. The appearance of cy17:0 revealed that bacteria affiliated with the Desulfobacteriaceae were responsible for acetate degradation. Desulfovibrio and Desulfotomaculum spp. were not important populations within the SRB community in microcosms because they did not proliferate on carbon sources usually favored by these organisms. Metabolic, PLFA, and FISH results provided information on the SRB community in a PHC-contaminated freshwater environment, which exhibited stimulation patterns similar to other (e.g. marine) environments. [source] Reorganization of a large marine ecosystem due to atmospheric and anthropogenic pressure: a discontinuous regime shift in the Central Baltic SeaGLOBAL CHANGE BIOLOGY, Issue 6 2009CHRISTIAN MÖLLMANN Abstract Marine ecosystems such as the Baltic Sea are currently under strong atmospheric and anthropogenic pressure. Besides natural and human-induced changes in climate, major anthropogenic drivers such as overfishing and anthropogenic eutrophication are significantly affecting ecosystem structure and function. Recently, studies demonstrated the existence of alternative stable states in various terrestrial and aquatic ecosystems. These so-called ecosystem regime shifts have been explained mainly as a result of multiple causes, e.g. climatic regime shifts, overexploitation or a combination of both. The occurrence of ecosystem regime shifts has important management implications, as they can cause significant losses of ecological and economic resources. Because of hysteresis in ecosystem responses, restoring regimes considered as favourable may require drastic and expensive management actions. Also the Baltic Sea, the largest brackish water body in the world ocean, and its ecosystems are strongly affected by atmospheric and anthropogenic drivers. Here, we present results of an analysis of the state and development of the Central Baltic Sea ecosystem integrating hydroclimatic, nutrient, phyto- and zooplankton as well as fisheries data. Our analyses of 52 biotic and abiotic variables using multivariate statistics demonstrated a major reorganization of the ecosystem and identified two stable states between 1974 and 2005, separated by a transition period in 1988,1993. We show the change in Baltic ecosystem structure to have the characteristics of a discontinuous regime shift, initiated by climate-induced changes in the abiotic environment and stabilized by fisheries-induced feedback loops in the food web. Our results indicate the importance of maintaining the resilience of an ecosystem to atmospherically induced environmental change by reducing the anthropogenic impact. [source] Receptor architecture of human cingulate cortex: Evaluation of the four-region neurobiological modelHUMAN BRAIN MAPPING, Issue 8 2009Nicola Palomero-Gallagher Abstract The structural and functional organization of the human cingulate cortex is an ongoing focus; however, human imaging studies continue to use the century-old Brodmann concept of a two region cingulate cortex. Recently, a four-region neurobiological model was proposed based on structural, circuitry, and functional imaging observations. It encompasses the anterior cingulate, midcingulate, posterior cingulate, and retrosplenial cortices (ACC, MCC, PCC, and RSC, respectively). For the first time, this study performs multireceptor autoradiography of 15 neurotransmitter receptor ligands and multivariate statistics on human whole brain postmortem samples covering the entire cingulate cortex. We evaluated the validity of Brodmann's duality concept and of the four-region model using a hierarchical clustering analysis of receptor binding according to the degree of similarity of each area's receptor architecture. We could not find support for Brodmann's dual cingulate concept, because the anterior part of his area 24 has significantly higher AMPA, kainate, GABAB, benzodiazepine, and M3 but lower NMDA and GABAA binding site densities than the posterior part. The hierarchical clustering analysis distinguished ACC, MCC, PCC, and RSC as independent regions. The ACC has highest AMPA, kainate, ,2, 5-HT1A, and D1 but lowest GABAA densities. The MCC has lowest AMPA, kainate, ,2, and D1 densities. Area 25 in ACC is similar in receptor-architecture to MCC, particularly the NMDA, GABAA, GABAB, and M2 receptors. The PCC and RSC differ in the higher M1 and ,1 but lower M3 densities of PCC. Thus, multireceptor autoradiography supports the four-region neurobiological model of the cingulate cortex. Hum Brain Mapp, 2009. © 2008 Wiley-Liss, Inc. [source] Short-term spatial and temporal patterns of suspended sediment transfer in proglacial channels, small River Glacier, CanadaHYDROLOGICAL PROCESSES, Issue 9 2004John F. Orwin Abstract Alpine glacial basins are a significant source and storage area for sediment exposed by glacial retreat. Recent research has indicated that short-term storage and release of sediment in proglacial channels may control the pattern of suspended sediment transfer from these basins. Custom-built continuously recording turbidimeters installed on a network of nine gauging sites were used to characterize spatial and temporal variability in suspended sediment transfer patterns for the entire proglacial area at Small River Glacier, British Columbia, Canada. Discharge and suspended sediment concentration were measured at 5 min intervals over the ablation season of 2000. Differences in suspended sediment transfer patterns were then extracted using multivariate statistics (principal component and cluster analysis). Results showed that each gauging station was dominated c. 80% of days by diurnal sediment transfer patterns and ,low' suspended sediment concentrations. ,Irregular' transfer patterns were generally associated with ,high' sediment concentrations during snowmelt and rainfall events, resulting in the transfer of up to 70% of the total seasonal suspended sediment load at some gauging stations. Suspended sediment enrichment of up to 600% from channel storage release and extrachannel inputs occurred between the glacial front and distal proglacial boundary. However, these patterns differed significantly between gauging stations as determined by the location of the gauging station within the catchment and meteorological conditions. Overall, the proglacial area was the source for up to 80% of the total suspended sediment yield transferred from the Small River Glacier basin. These results confirmed that sediment stored and released in the proglacial area, in particular from proglacial channels, was controlling suspended sediment transfer patterns. To characterize this control accurately requires multiple gauging stations with high frequency monitoring of suspended sediment concentration. Accurate characterization of this proglacial control on suspended sediment transfer may therefore aid interpretation of suspended sediment yield patterns from glacierized basins. Copyright © 2004 John Wiley & Sons, Ltd. [source] Spatio-temporal climatic change of rainfall in East Java IndonesiaINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 4 2008Edvin Aldrian Abstract Spatial and temporal rainfall analysis of the Brantas Catchment Area (DAS Brantas), East Java, from 1955 to 2005 based on 40 rainfall stations with monthly rainfall data derived from daily rainfall data has been performed. To identify the climatic trend and annual changes in the area over the last five decades, we use the empirical orthogonal function (EOF) method based on multivariate statistics, followed by the fast Fourier transform (FFT) method for the power density spectrum analysis, the non-parametric Mann-Kendall trend test and the wavelet transform method. With EOF, we found the monsoonal rainfall pattern as the most dominant in this area, which explains about 72% of all variances. Without the annual signal, the leading EOF shows significant ENSO-modulated inter-annual and seasonal variabilities, especially during the second transitional period. We found a common and significant negative trend of accumulated rainfall and a negative trend of the monsoonal strength and dominance. This finding leads to changes in the annual pattern, which are increase in the ratio of rainfall during the wet season and increase of the dry spell period or the imbalance of the annual pattern. The increased ratio of the rainfall in the wet season has led to an increased threat of drought in the dry season and extreme weather in the wet season in recent decades. The role of the orographic effect had been detected from the decadal pattern, in which the high-altitude areas have greater rainfall amount all year round. From the decadal isohyets in December/January/February (DJF) and June/July/August (JJA), the rainfall amount decreased significantly during the last five decades as shown by a persistent increase of areas with low rainfall amount. By comparing the time series of rainfall data in two locations, the mountain and coastal areas, we discovered that the dry periods have increased, mainly in the low altitude area. Copyright © 2007 Royal Meteorological Society [source] Analysis of the interaction of substituted coumarins with the DPPH free radical by means of multivariate statisticsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2004Demetris Vrakas The interaction of some substituted coumarin derivatives with the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical was analysed by means of multivariate statistics using a variety of molecular descriptors. The compounds contain a conjugated double bond system, which was considered to be an essential structural characteristic for the free-radical scavenging activity. Partial least-square analysis led to an adequate two-component model based on bulk descriptors and the electronic properties concerning atoms involved or next to the double-bond system. [source] Characterizing diversity in composition and pasting properties of tuber flour in yam germplasm (Dioscorea spp.) from Southern EthiopiaJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2008Muluneh Tamiru Abstract BACKGROUND: Studies on composition and functional properties in germplasm collections are important in determining their diversity and suitability for food and non-food applications. The diversity in 65 yam accessions collected from Southern Ethiopia and belonging largely to a yet unknown species and to Dioscorea bulbifera L. (aerial yam) was analyzed based on protein, starch and amylose contents, and pasting properties of tuber flour, applying descriptive and multivariate statistics. RESULT: Starch content varied from 65.2% to 76.6% dry matter, while the protein content range was 6.4,13.4% dry matter. Amylose represented between 7.1% and 30.6% of the starch fraction, and was negatively correlated (P < 0.01) with starch content. UPGMA clustering and principal component analysis clearly distinguished aerial yam from those accessions with underground tubers. The first four principal components accounted for 78% of the total variability, and were highly correlated with pasting parameters. CONCLUSION: The extent of diversity detected among accessions studied showed scope for improving the crop through selection of landraces with desirable characteristics. Similar investigations on tubers grown under different environmental conditions and additional data on physicochemical properties of isolated starch will be useful in evaluating the potential of yam for food and non-food applications. Copyright © 2008 Society of Chemical Industry [source] Detection of inverted beet sugar adulteration of honey by FTIR spectroscopyJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2001S Sivakesava Abstract A combination of Fourier transform infrared (FTIR) spectroscopy and multivariate statistics as a screening tool for the determination of beet medium invert sugar adulteration in three different varieties of honey is discussed. Honey samples with different concentrations of beet invert sugar were scanned using the attenuated total reflectance (ATR) accessory of the Bio-Rad FTS-6000 Fourier transform spectrometer. The spectral wavenumber region between 950 and 1500,cm,1 was selected for partial least squares (PLS) regression to develop calibration models for beet invert sugar determination in honey samples. Results from the PLS (first derivative) models were slightly better than those obtained with other calibration models. Predictive models were also developed to classify beet sugar invert in three different varieties of honey samples using discriminant analysis. Spectral data were compressed using the principal component method, and linear discriminant and canonical variate analyses were used to detect the level of beet invert sugar in honey samples. The best predictive model for adulterated honey samples was achieved with canonical variate analysis, which successfully classified 88,94 per cent of the validation set. The present study demonstrated that Fourier transform infrared spectroscopy could be used for rapid detection of beet invert sugar adulteration in different varieties of honey. © 2001 Society of Chemical Industry [source] Geography of morphological differentiation in Asellus aquaticus (Crustacea: Isopoda: Asellidae)JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 2 2009S. Prevor Abstract We implemented a detailed morphometry and multivariate statistics to establish a general, large-scale racial differentiation in Asellus aquaticus (L.) sensu Racovitza. We ascertained that in surface populations a set of 11 morphometric characters might equivalently be represented by the pleopod respiratory area size alone. The analyses resulted in a distinct distribution pattern, with the large respiratory area populations disposed mainly along the Dinaric karst between southern Slovenia and western Macedonia and surrounded by the medium respiratory area morph, spatially irregularly substituted by the small area morph. This pattern is in contradiction with the distribution pattern of molecularly defined clades (as shown by Verovnik et al. 2005). We could find no ecological, hydrographical or paleogeographical explanations for such distribution pattern either. The only hypothetical explanation would be a preservation of the large respiratory area as a plesiomorphic character in the comparatively sheltered karst habitats, while throughout the easier accessible parts of the species range it was replaced by the ,modern' smaller area size. While a diminution of the respiratory area functionally means an increased sclerotization , hardening of pleopod IV,V exopodites, endopodites of pleopods III,V remain less sclerotized, probably respiratory and osmoregulatory functional. Zusammenfassung Die globale Rassendifferenzierung von Asellus aquaticus (L.) sensu Racovitza wurde anhand eingehender Morphometrie und multivariater Statistik untersucht. Es stellte sich heraus, dass der gesamte Satz von 11 morphometrischen Merkmalen allein durch das Merkmal ,Flächengröße der Pleopoden-Respirationsfläche' ersetzt werden kann. Die Analysen ergaben ein deutliches Muster, in dem Populationen mit großen Respirationsflächen überwiegend im Dinarischen Karst zwischen Süd-Slowenien und West-Makedonien verbreitet sind, von Morphen mit mittelgroßen Respirationsflächen umgeben werden, welche wiederum räumlich zerstreut von Morphen mit kleinen Respirationsflächen ersetzt werden. Dieses Muster widerspricht der Verbreitung von molekular-systematisch ermittelten Gruppen (Verovnik et al. 2005). Wir konnten keine ökologische, hydrographische oder paläogeographische Erklärung dafür finden. Die einzige hypothetische Erklärung könnte eine Erhaltung der großen Respirationsflächen als eines plesiomorphen Merkmals in vergleichsweise isolierten Karstgebieten sein, während sie in leichter besiedelbaren Gebieten von den ,modernen' kleineren Respirationsflächen ersetzt wurden. Es muss betont werden, dass eine Verkleinerung der Respirations-Area mit der Sklerotisierung der Exopoditen an den Pleopoden IV-V verbunden ist, während die Endopoditen der Pleopoden III-V ihre geringe Sklerotisierung beibehalten und somit wahrscheinlich atmungs- und osmoregulatorisch aktiv bleiben. [source] Metabolites from cerebrospinal fluid in aneurysmal subarachnoid haemorrhage correlate with vasospasm and clinical outcome: a pattern-recognition 1H NMR studyNMR IN BIOMEDICINE, Issue 1 2005Victoria G. Dunne Abstract Following subarachnoid haemorrhage the most significant complication is sustained cerebral vascular contraction (vasospasm), which may result in terminal brain damage from cerebral infarction. Despite this, the biochemical cause of vasospasm remains poorly understood. In this study, the global high-concentration metabolite composition of CSF has been correlated with patient outcome after subarachnoid haemorrhage using multivariate statistics and 1H NMR spectroscopy. In total, 16 patients with aneurysmal subarachnoid haemorrhage (aSAH) were compared with 16 control patients who required a procedure where CSF was obtained but did not have aSAH. Multivariate statistics readily distinguished the aSAH group from the heterogeneous control group, even when only those controls with blood contamination in the CSF were used. Using principal components analysis and orthogonal signal correction, vasospasm was correlated to the concentrations of lactate, glucose and glutamine. These pattern recognition models of the NMR data also predicted Glasgow Coma Score (54% within ±,1 of the actual score on a scale of 1,15 for the whole patient group), Hunt and Hess SAH severity score (88% within ±,1 of the actual score on a scale of 1,5 for the aSAH group) and cognitive outcome scores (78% within ±,3 of the actual score on a 100% scale for the whole patient group). Thus, the approach allowed the prediction of outcome as well as confirming the presence of aSAH. Copyright © 2004 John Wiley & Sons, Ltd. [source] Exploring Romano,British finds assemblagesOXFORD JOURNAL OF ARCHAEOLOGY, Issue 4 2002H. E. M. Cool This paper presents a synthesis of current approaches to the comparison of archaeological assemblages. It draws its data from Roman Britain but the methodology discussed is equally applicable to other periods and places. Different types of assemblages including those of small finds, broken vessels and animal bones are discussed, and the problems relating to quantification are considered. The different sorts of questions that may be asked of data of varying quality are examined, and it is shown that even ,poor quality' data can provide useful insights into past societies. It is argued that to explore the full richness of the data available, multivariate statistics are an invaluable tool and this is illustrated by exploration of two groups of assemblages using Correspondence Analysis. Finally, attitudes within the archaeological community which may prove a barrier to further advances are examined. [source] Geographic variation in loud calls of sportive lemurs (Lepilemur ssp.) and their implications for conservationAMERICAN JOURNAL OF PRIMATOLOGY, Issue 9 2008Maria Méndez-Cárdenas Abstract Bioacoustical studies in nonhuman primates have shown that loud calls can be reliably used as a noninvasive diagnostic tool for discriminating cryptic taxa, for their monitoring in the field as well as for the reconstruction of their phylogeny. To date, it is unknown, whether loud calls can be used for these purposes in sportive lemurs, for which current genetic studies suggest the existence of at least 24 cryptic species. The aim of this study was to compare the structure of loud calls of populations of sportive lemurs to characterize informative acoustic traits for taxa discrimination and to establish a phylogenetic tree based on acoustic structure. We have based our study on Inter-River-Systems (IRSs) as operational taxonomic units. Samples were collected from nine different localities of four IRSs along a transect from northwestern to northern Madagascar. Two call types, the ouah and the high-pitched call, were present in almost all IRSs. Six temporal and eight spectral parameters were measured in 196 calls of the best quality given by 21 different males. Variation within and between IRSs was assessed by multivariate statistics. Loud calls differed significantly among the different IRSs. The IRSs varied most in spectral parameters, whereas temporal parameters were less variable. Phylogenetic analysis using parsimony yielded 11 out of 17 acoustic characters as phylogenetically informative. The acoustic tree had an average branch support of 78%. Its topology coincided less with geographic distances than with genetic tree topology. Altogether our findings revealed that loud calls separated geographically isolated populations of sportive lemurs specifically. Based on these results, noninvasive tools for diagnosis and monitoring of cryptic species in nature can be developed for conservation management. Am. J. Primatol. 70:828,838, 2008. © 2008 Wiley-Liss, Inc. [source] Biogeography and diversity among montane populations of mouse shrew (Soricidae: Myosorex) in TanzaniaBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2010WILLIAM T. STANLEY We assess variation in morphological and molecular characters among three species of Myosorex (the mouse shrew) ,Myosorex geata, Myosorex kihaulei, and Myosorex zinki, as a means to test previously proposed biogeographic hypotheses for Tanzanian ,sky islands' and systematic hypotheses for Tanzanian mouse shrews. We analyse 17 cranial and dental variables using multivariate statistics and perform phylogenetic and phylogeographic analyses on sequences of mitochondrial and nuclear DNA; samples are drawn from every known Tanzanian population of Myosorex. Morphometric and phylogenetic analyses reveal that M. zinki is distinct, but that currently isolated populations of M. geata and M. kihaulei are relatively similar to one another, and may not have been isolated over geological time scales. Analyses of molecular variance identify statistically significant, but limited, genetic variation within and between isolated populations of M. geata and M. kihaulei. Between two putative regional biogeographic boundaries, greater genetic variation is explained by grouping populations on either side of the Ruaha River than by grouping populations on either side of the Makambako Gap. Our results are in agreement with recent studies illustrating the close relationship between faunas of the Southern Highlands and southern Eastern Arc Mountains, diminishing the apparent importance of the Makambako Gap as a historical biogeographic barrier. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 669,680. [source] Modeling with a view to target identification in metabolic engineering: A critical evaluation of the available toolsBIOTECHNOLOGY PROGRESS, Issue 2 2010Jo Maertens Abstract The state of the art tools for modeling metabolism, typically used in the domain of metabolic engineering, were reviewed. The tools considered are stoichiometric network analysis (elementary modes and extreme pathways), stoichiometric modeling (metabolic flux analysis, flux balance analysis, and carbon modeling), mechanistic and approximative modeling, cybernetic modeling, and multivariate statistics. In the context of metabolic engineering, one should be aware that the usefulness of these tools to optimize microbial metabolism for overproducing a target compound depends predominantly on the characteristic properties of that compound. Because of their shortcomings not all tools are suitable for every kind of optimization; issues like the dependence of the target compound's synthesis on severe (redox) constraints, the characteristics of its formation pathway, and the achievable/desired flux towards the target compound should play a role when choosing the optimization strategy. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] | ||||||||||||||||||||||||||||