1,721,288 research outputs found
«Ne siamo certi: le sonde VIKING scoprirono laVITA su Marte!» Rivisti con nuove tecniche i dati delle sonde spaziali NASA a distanza di 36 anni: i risultati confermano l'esistenza di attività microbica
No full textIn italian language a popularization of the results published by the Author on the international Journal, IJASS, 201
PBDAY. Steering Committee Meeting. Final Draft Reports. Report from the Siena Reference Centre.
No full textAuthor presents and discusses results from the Siena Reference Center ( PBDAY study) during the Steering Committee Meeting
Nova in the Large Magellanic Cloud 2009 - Circolare Internazionale IAUC# 9024
No full textDati sperimentali di fotometria. Indicizzato sul Database Internazionale Astrophysical Data Syste
Informational polymers in the primitive Earth: Lempel-Ziv complexity and Entropy of tRNAs in anaerobic Archaea compared to computer-generated random data.
No full textIn a possible scenario for the origin of life there was a time in which informational genetic polymers played primary roles. Transfer-RNA molecules may be considered possible “fossils” of that primitive era (billions years ago). In order to test the hypothesis that the nucleotide sequences of the primitive informational polymers might not be chosen randomly, we propose a comparison of computer-generated random sequences with tRNAs nucleotide sequences present in anaerobic Archaea. Nucleotide sequence data of archaeal tRNA genes were obtained from the Institute for Genomic Research (TIGR) and the GeneBank library. Random sequence data (white noise) were obtained from the algorithm by Press and Teukolsky. Relative Lempel-Ziv complexity and Entropy of nucleotide sequences and of computer generated random represented as random walks were evaluated. Manhattan and Euclidean "fractal" dimensions of nucleotide sequences (DM, DE) were also evaluated. Nonlinear parameters obtained from the Archaea are lower than the values of randomly generated sequences (p<0.01, p<0.01). DM and DE confirm the results (p<0.01, p<0.01). The observed deviation from pure randomness should be arisen from some constraints like the secondary structure of this biologic macromolecule and/or from a “frozen” stochastic transition when informational polymers originated. The nonlinear evaluation of nucleotide sequences expressed as random walks, here presented, provides an efficient assessment of the primary structure of nucleic acid sequences
Increased entropy in in vitro activated platelets
No full textComputerized fractal analysis was used in the present work for objective characterization of the entropy of the platelet contour in in vitro stimulated platelets by low level thrombin (0.02 U/ml), collected from healthy individuals and observed by means of transmission electron microscopy. Platelet boundaries were extracted by means of automatically image analysis. Information dimension of the platelet contour (measure of the entropy of the platelet outline) was automatically evaluated. The results showed that the platelet boundary observed by electron microscopy is fractal and that, after an in vitro platelet activation test, the shape of platelets present increased entropy in comparison to the no stimulated platelets (p<0.001), with 100% correct classification. The entropy of the platelet contour observed by transmission electron microscopy provides accurate, quantitative, data to study platelet activation. The results may play important roles in the evaluation of the platelets status in pathological conditions, like as atherosclerosis and diabetes mellitus, where in in vivo activated platelets have been described
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