1,720,960 research outputs found
GeneWeb: A WWW hypertext concerning genetics and molecular biology
No full textAutomatic techniques for DNA sequencing are yielding a huge amount of gene and protein sequences and as a consequence the number of biological databanks is more and more increasing, presently exceeding 120. In order to be accessible, all information should be organized in databases, several Gigabytes large, which cannot be managed with a personal computer or workstation. A possible solution is to make available these databases through the international computer network Internet. To facilitate the work of biology researchers our group created GeneWeb, an on-line hypertext making accessible a great amount of information and tools concerning genetics and molecular biology. Users willing to connect to GeneWeb need a direct access to the WWW (World Wide Web) and have to set a browser such as Mosaic or Netscape at the URL (Uniform Resource Locator) http://dns.unife.it/geneweb. GeneWeb makes accessible many different types of databases among which sequence and structure (e.g. GenBank, SWISS-P..
Correlation between age and DNA damage detected by FADU in human peripheral blood lymphocytes
No full textFluorometric analysis of DNA unwinding (FADU) is a fast and reliable method for detecting single strand DNA breaks as an index of DNA damage induced by clastogenic agents. A study of damage detected by FADU was conducted on DNA extracted from peripheral blood lymphocytes of 128 healthy nonsmoking regular donors (ranging in age from 19 to 67 years) and from 5 umbilical cord blood samples. DNA damage was measured as percentage of unwound DNA after alkalinization. Statistical analyses, both parametric (Pearson r correlation coefficient, b regression coefficient, ANOVA) and nonparametric (Kruskal-Wallis H test, Spearman r(s) rank correlation coefficient), support a significant correlation between age of donors and amount of DNA damage. The same results are found when adult donors are divided in four age classes and the ANOVA test performed among the mean percentages of unwound DNA of each class. Furthermore, donors of the same age belonging to different blood groups (A, B, AB and O) do not show any difference in DNA damage detected by FADU
Isolation by distance in Germany
No full textThe isonymy structure of Germany has been studied by using the surname distributions in private telephone users. Germany was subdivided in 50 adjacent rectangles having side 115x80 kms; at least the largest town in the rectangle was selected and the private telephone users in its district were included in the analysis.
The number of different surnames found in the whole analysis was 462,580. Lasker's distance was found to be linearly and significantly correlated with the geographic distance, with r=0.51±0.010. A dendrogram was built with the matrix of isonymy distance, using the UPGMA method. It separates the German towns in two main clusters, one in the southern half of the country and the other in the northern. The two main clusters correspond fairly well to the north-south division of german sublanguages (Nieder and Mitteldeutsch in the North vs. Frankish-Alemannisch in the South). The other clusters are related to minor sublanguages.
Comparisons with the results of a previous analysis, show that isolation by distance in Germany is less strong than in Switzerland and indicate that this Country has a fairly homogeneous isonymy structure
Correlations between Isonymy Parameters
No full textSeveral parameters of genetic and anthropological interest are commonly estimated in the analysis of the surnames' distribution in human populations. Among these parameters, the most important for population structure is unbiased Isonymy, equivalent to 4 times the value of Fst, the random component of inbreeding in a group. Fisher's α estimates the wealth of surnames in a group, and Karlin-McGregorv is considered proportional to migration rates. Recently, other parameters like Entropy and Redundance of the surname's distribution were introduced in the analysis and estimated. In the present work, the parameters obtained through isonymy analysis of 759,500 telephone users in 379 Communes of Sicily are correlated with variables such as sample size, population size and density, and number of surnames in the Commune. In Sicily, the parameters or their logarithm are Gammadistributed. It is observed that the number of surnames is strongly correlated with most parameters or with their logarithm, and that it is in turn strongly correlated with sample size
Isonymy and isolation by distance in Germany
No full textThe isonymy structure of Germany was studied using the surname distributions of 5,150,310 private telephone users selected from 39,000,000 users registered in a 1996 commercial CD-ROM, which contains all telephone users in the country. The users were distributed in 106 towns selected on a geographic basis. Germany was subdivided into 50 adjacent rectangles, each 115 x 80 km, and at least the largest town in the rectangle was selected for study; the private telephone users in that district were downloaded from the CD-ROM and included in the analysis. The shortest distance between nearest neighbor towns was 10.7 km (Travemunde and Lübeck), and the largest distance was 69.8 km (Meppen and Osnabruck). The number of different surnames found in the whole analysis was 462,526. Lasker's distance, the negative value of the logarithm of isonymy between localities, was found to be linearly and significantly correlated with geographic distance (r = 0.51 +/- 0.010). A dendrogram was built with the matrix of isonymy distances, using UPGMA. This method separates the German towns into two main clusters, one in the southern half of the country and the other in the northern half. Within each cluster small subclusters with specific geographic distributions could be delimited. The two main clusters correspond fairly well to the north-south division of German sublanguages (Nieder- and Mitteldeutsch in the north vs. Frankisch-Alemannisch in the south). The other clusters are related to minor sublanguages. Comparisons with the results of a previous analysis of Switzerland's structure are given. From the present analysis isolation by distance emerges clearly, although it is less strong than in Switzerland and indicates that Germany has a fairly homogeneous isonymy structure. The random component of inbreeding estimated from isonymy indicates that eastern Germany is on average more inbred than western Germany
Isonymy and the genetic structure of Switzerland .1. The distributions of surnames
No full textThe surname distribution of the population of Switzerland was studied using a sample of 1,702,000 private users registered for the year 1994 in the Helvetic Telephone Directory. These users were distributed in four linguistic areas, in 26 Cantons and 271 Communes of the Confederation. Estimates of unbiased random isonymy, of Fisher's alpha, an indicator of abundance of surnames converging to the allele effective number in standard genetic polymorphisms, and of Karlin-McGregor's v, an indicator of immigration rates, were calculated for each Commune, each Canton, each linguistic area and for the whole Confederation. The Commune with the highest value of alpha was Geneva (alpha = 5312) followed by Versoix (3713) and by the Communes of Vaud on the north shore of Lake Leman, Chavannes (3381), Montreux (3200), Nyon (3114) and Lausanne (3109). The Italian-speaking Communes of the Ticino were next. The lowest value (alpha = 29) was observed in Poschiavo, south of the Berninapass; alpha = 39 was observed in Einsiedeln (Schwyz); then Mels and Widnau (62 and 67, Canton of St Gallen), Frutingen in Bern (72), and Appenzell (80). Accordingly, the highest consanguinity values were observed in the Grisons and in the nucleus of the founding Cantons, while the lowest were observed in the Cantons of Geneva and Vaud, preferential areas of immigration to Switzerland from abroad. The effect of subdivision on isonymy is large at the Commune level, and decreases in Cantons and linguistic groups. French and Italian languages indicate minor, German and Romanisch major inbreeding
Isonymy and the genetic structure of Switzerland. II. Isolation by distance
No full textIsolation by distance in Switzerland was detected comparing the surname distributions between Cantons. The decay of isonymy with geographic distance between Cantons was consistent with Malecot's exponential decay of kinship. Lasker's distance was defined as the negative value of the logarithm of isonymy between localities, and it was found that it is linearly and significantly correlated with the log of geographic distance, both within and between languages. The peculiar geographic and linguistic structure of the Confederation, where mountain barriers exist at short distances separating different languages, might explain the rapid changes in surname similarity. It was predicted that the frequency of markers linked to the Y chromosome would show a similar association with distance in Switzerland
Phylogeny inferred from codon usage pattern in 31 organisms
No full textWe employed the Codonusage database to analyze the codon usage pattern in 31 organisms from all the main biological taxa. We tested the similarity in codon usage pattern between each organism and all the others by the Pearson linear correlation coefficient. The 465 values obtained were located in a 31 x 31 triangular matrix from which a correlation distance matrix was calculated. An evolutionary dendrogram was then constructed from these distances. The results showed a fair correlation between codon usage patterns and phylogenetic relationships, at least for organisms which diverged in rather recent times (end of Jurassic--beginning of Cretaceous)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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