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Many studies on Neotropical streams have reported seasonal changes in the diet of fish, although studies that evaluate the influence of these temporal differences on the entire web are very scarce. Under the hypothesis that trophic interactions and the food web structure are under seasonal influences, two forested streams (named S1 and S2) were sampled during the wet and dry periods. The samplings were conducted in August 2007 and April 2008 and included algae, macrophytes, plankton. macroinvertebrates, and fish. All heterotrophic taxa sampled were submitted to diet analysis. The similarity among samples was estimated by a cluster analysis using quantitative data of environmental variables, community attributes, and food web properties. A total of 2,250 individuals of 139 trophic species were identified. The food webs were mainly detritus-based, which resulted in a great proportion of trophic species at the first trophic level and high omnivory in all samples. All fish species were top species because they had no predators. The S1 stream, predominantly composed of a sandy substrate, presented lower abundance than the predominantly rocky S2 stream in both dry and wet periods, although richness was similar. Cluster analysis demonstrated that environmental attributes were more similar between seasons, community attributes were more similar between streams, and food web parameters were very similar (94% similarity) both between streams and seasons. Therefore, we concluded that although environmental attributes varied temporally and community attributes varied spatially, the trophic relationships and overall food web structure of these preserved streams remain similar.

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The distribution patterns of Classic Mimbres black-on-white bowls and jars were determined by instrumental neutron activation analysis to identify vessel movement between geographically defined regions and between villages within individual regions of southwestern New Mexico. The data set produced and utilized by the various multivariate statistical treatments included multielement neutron activation analysis results for 288 ceramic and clay samples from 15 sites in the Gila, Mimbres and Rio Grande valleys of southwest New Mexico. The results indicate that bowls were more frequently exchanged than jars and distribution frequencies between regions were lower than between villages. Two statistical approaches to the data were compared. In one, cluster analysis of the compositional data was used to form homogeneous groups and the distribution of those groups across sites and regions was examined. In the second, discriminant analysis was used to look for significant differences in composition between regions and sites. The significance of predetermining groups based on collection location as opposed to blind group formation from hierarchical cluster analysis was evaluated in terms of its potential to lead to different interpretations of the data.

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The purpose of this work was to analyze lead white pigment from icons of 15 th–18 th centuries, collected at the Orthodox Art Department at the Castle Museum in Łańcut, using instrumental neutron activation analysis. The results allowed to identify the concentration of trace elements in 37 samples collected. 40 elements were identified and determined. The cluster analysis using STATISTICA (StatSoft) programme was carried out to identify the similarity degree of the analyzed objects. The aforementioned comparisons indicated that the lead white used in the analyzed icon paintings, constituted a unified, very typical group that had underwent changes with time, came from sources different than lead white used in Małopolska and Silesian Polish school panel paintings.

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In the presented study, quantitative structure—retention relationships (QSRR) methodology was used to investigate the relationship between the chemical structures of steroids and phenanthrene derivatives, their physicochemical properties, and the chromatographic retention. Normal-, reversed-phase and cyano-bonded silica stationary phases were tested with five binary mobile phases (acetonitrile—water, acetonitrile—dimethyl sulfoxide (DMSO), acetonitrile— methanol, acetone—petroleum ether, and acetone—water). The study was based on multiple linear regression, and the results are presented as QSRR equations. Additionally, principal component analysis and cluster analysis were performed. They have been carried out based on retention parameters and molecular descriptors, which were calculated from the optimized structures by use of HyperChem and ChemAxon software. The high correlation coefficients (r), F-values, and low values of the standard deviation indicate that the obtained QSRR equations present well the chromatographic behavior of the tested compounds on both reversed-phase thin-layer chromatography (RP-TLC) and cyano (CN)-TLC.

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On self-explaining roads drivers automatically drive according to the expected behavior and speed. In order to create this type of roads, within a given road category the layout should be homogenous, whereas a remarkable difference should exist between road categories. Using a sample of 500 persons, the paper analyses, which road categories are identified and distinguished by road users.A picture sorting task was completed to find out how road users group 45 different road scenes, and how these groups correspond to the road categories according to current standards.In addition, an analysis of a questionnaire survey was used to determine how individual road scene images are grouped on the basis of chosen speeds, and how this grouping corresponds to road categories. For processing of speed data, cluster analysis was used.The result of both surveys show that road users can clearly distinguish only 4–5 road categories. The paper compares these results with the design guidelines of some countries.

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This study applies a method of author co-citation analysis to examine the intellectual structure of political communication study. Fifty one influential authors were selected from active members of the Political Communication Divisions of the International Communication Association (ICA), the National Communication Association (NCA), and the American Political Science Association (APSA). The results of the multidimensional scaling analysis and cluster analysis of these 51 selected authors' co-citation patterns show that intellectual fragmentation exists in political communication research; scholars with different academic backgrounds exhibit specialties using particular research approaches to study certain subjects in the field; scholars do not have much information exchange, and thus they are intellectually separate and confined within the boundaries of each fragment. The findings of this quantitative study complements and cross-validates the assessment made by other traditional qualitative reviews about the field.

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A new bibliometric method is proposed for representing links between subfields as defined by a classification scheme. The frequency of co-occurrence of articles from different subfields in selected journals is used for measuring the degree of relatedness between these subfields. The results of such quantitative analysis could be compared to the tree topology of the classification network established in a qualitative analysis. The method is applied to describe the internal links within the field of condensed matter physics using the 1984 Physics Abstracts database. A distinction is made between experimental and theoretical links on the basis of treatment codes assigned to journal articles. The links described by cluster analysis are matched against the cross-reference network of the International Classification for Physics.

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A partial sequence of a Ty1-copia retrotransposon was isolated from the genome of the rye (Secale cereale L.) inbred line L318 using degenerate primers targeted at the RNaseH sequence. Its putative 3’LTR region exhibited similarity to LTRs of known plant retrotransposons such as BARE-1, while no significant similarity to known rye retrotransposon sequences was found. A Sequence Specific Amplification Polymorphism (SSAP) protocol employing primer designed to correspond to the putative polypurine tract was developed and used for analysis of 30 rye inbred lines. Values of the parameters calculated to evaluate the efficiency of the method as well as the results of cluster analysis demonstrate that it is a powerful tool for genetic diversity analyses of rye.

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In the present paper, a simple and reliable high-performance liquid chromatography-diode array detection (HPLC-DAD) method was developed both for quantitative determination and fingerprint analysis of Agrimonia pilosa Ledeb for quality control. Under the optimized HPLC conditions, seven bioactive compounds including rutin, quercetin-3-rhamnoside, luteoloside, tiliroside, apigenin, kaempferol, and agrimonolide were determined simultaneously. For fingerprint analysis, 11 common peaks were selected as the characteristic peaks to evaluate the similarities of 16 different samples collected from different origins in China. Besides, hierarchical cluster analysis (HCA) was also performed to evaluate the variation of the raw materials. This is the first report of using a simple method for quality control of A. pilosa Ledeb through multi-component determination and chromatographic fingerprint analysis to the best of our knowledge.

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Science has traditionally been mapped on the basis of authorship and citation data. Due to publication and citation delays such data represents the structure of science as it existed in the past. We propose to map science by proxy of journal relationships derived from usage data to determine research trends as they presently occur. This mapping is performed by applying a principal components analysis superimposed with a k-means cluster analysis on networks of journal relationships derived from a large set of article usage data collected for the Los Alamos National Laboratory research community. Results indicate that meaningful maps of the interests of a local scientific community can be derived from usage data. Subject groupings in the mappings corresponds to Thomson ISI subject categories. A comparison to maps resulting from the analysis of 2003 Thomson ISI Journal Citation Report data reveals interesting differences between the features of local usage and global citation data.

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