368 research outputs found
Massimo Donà, Misterio grande. Filosofia di Giacomo Leopardi
Massimo Donà, Misterio grande. Filosofia di Giacomo Leopardi. Milà: Bompiani, 2013, 316 pp
"La Querelle des anciens et des moderns": Leopardi i la via perduda del romanticisme alemany
El marc interpretatiu d’aquest article parteix de l’establiment de dos bàndols filosòfics: per una banda, Goethe i Leopardi, en tant que respectuosos amb el límit de la natura, i per l’altra, els romàntics i l’idealisme absolut de Hegel, en tant que irrespectuosos amb els límits de la natura. El salt teòric a partir del qual gira aquest article, consisteix a estendre l’enfrontament explícit que Giacomo Leopardi va mantenir contra el romanticisme vers l’idealisme absolut de Hegel. I és que hom es planteja el fet que ambdós moviments van en contra de la veritat en tant que revelació. La veritat leopardiana es revela mitjançant la imaginació o les il•lusions, la qual cosa el porta a depassar el conflicte entre els anciens i els modernes en tant que models. I és que no hi pot haver models perquè la veritat no és pas un objecte
Amphioxus: a peaceful anchovy fillet to illuminate Chordate Evolution (II)
The genome of the amphioxus is on the horizon. With Linda Holland and Jeremy Gibson-Brown at the forefront, with all the amphioxus community behind, and with the Joint Genome Institute, the amphioxus genome will see the light this year, 2006. Hope that it will reflect the “prototypical” preduplicative genome of vertebrates. It may answer definitively what the human genome did not: Are we vertebrates octaploid? Will it shed light on the novelties that helped non-chordates to be chordates? And more, will amphioxus, with a simpler genome, be developed to a senior “experimental model system”, allowing the testing of molecular functions in a non-duplicated genome background and allowing genetic modification to “recapitulate” evolution? Thanks to an outstanding collaboration between labs, the laboratory culture of amphioxus is underway after years of hard work in the field. 2007 looks promising for amphioxus research
Genesis and evolution of the Evx and Mox genes and the extended Hox and ParaHox gene clusters
BACKGROUND: Hox and ParaHox gene clusters are thought to have resulted from the duplication of a ProtoHox gene cluster early in metazoan evolution. However, the origin and evolution of the other genes belonging to the extended Hox group of homeobox-containing genes, that is, Mox and Evx, remains obscure. We constructed phylogenetic trees with mouse, amphioxus and Drosophila extended Hox and other related Antennapedia-type homeobox gene sequences and analyzed the linkage data available for such genes. RESULTS: We claim that neither Mox nor Evx is a Hox or ParaHox gene. We propose a scenario that reconciles phylogeny with linkage data, in which an Evx/Mox ancestor gene linked to a ProtoHox cluster was involved in a segmental tandem duplication event that generated an array of all Hox-like genes, referred to as the 'coupled' cluster. A chromosomal breakage within this cluster explains the current composition of the extended Hox cluster (with Evx, Hox and Mox genes) and the ParaHox cluster. CONCLUSIONS: Most studies dealing with the origin and evolution of Hox and ParaHox clusters have not included the Hox-related genes Mox and Evx. Our phylogenetic analyses and the available linkage data in mammalian genomes support an evolutionary scenario in which an ancestor of Evx and Mox was linked to the ProtoHox cluster, and that a tandem duplication of a large genomic region early in metazoan evolution generated the Hox and ParaHox clusters, plus the cluster-neighbors Evx and Mox. The large 'coupled' Hox-like cluster EvxHox/MoxParaHox was subsequently broken, thus grouping the Mox and Evx genes to the Hox clusters, and isolating the ParaHox cluster
Particle Density Estimation with Grid-Projected Adaptive Kernels
The reconstruction of smooth density fields from scattered data points is a
procedure that has multiple applications in a variety of disciplines, including
Lagrangian (particle-based) models of solute transport in fluids. In random
walk particle tracking (RWPT) simulations, particle density is directly linked
to solute concentrations, which is normally the main variable of interest, not
just for visualization and post-processing of the results, but also for the
computation of non-linear processes, such as chemical reactions. Previous works
have shown the superiority of kernel density estimation (KDE) over other
methods such as binning, in terms of its ability to accurately estimate the
"true" particle density relying on a limited amount of information. Here, we
develop a grid-projected KDE methodology to determine particle densities by
applying kernel smoothing on a pilot binning; this may be seen as a "hybrid"
approach between binning and KDE. The kernel bandwidth is optimized locally.
Through simple implementation examples, we elucidate several appealing aspects
of the proposed approach, including its computational efficiency and the
possibility to account for typical boundary conditions, which would otherwise
be cumbersome in conventional KDE
El petit amfiox: el miratge de l'origen dels vertebrats
L'origen dels vertebrats és un dels centres d'interès de molts científics i de la societat, i
el nostre animal favorit, el petit i amigable amfiox, fa més d'un segle que ocupa aquesta
posició privilegiada, i reflecteix en un miratge, com a fòssil vivent, el que va ocórrer en
aquell transcendental moment de l'evolució. No és només morfològicament el representant
viu de l'ancestre de tots els cordats, sinó que a més posseeix un genoma preduplicatiu,
un model en versió simple del genoma de tots els vertebrats, incloent-hi l'humà. L'anàlisi
del genoma de l'amfiox ha permès clarificar l'origen del nostre genoma propi,
alhora que l'ha situat en una posició clau per entendre l'origen i funcionament de famílies
i xarxes gèniques importants per al desenvolupament embrionari i la fisiologia. A més, els
avenços tècnics en la reproducció i experimentació permeten raonadament somiar a resoldre
els secrets dels nostres orígens i del funcionament del genoma.The little amphious: a mirage to the origen of vertebrates. The origin of vertebrates is one of the top interests for many scientists and the society, and our favorite animal has occupied this privileged position for more than a century, reflecting
in a mirage, as a living fossil, what occurred in this critical landmark of evolution.
It is not only morphologically the closest living relative of Chordates, but also possesses a
preduplicative genome, a simple model for the genome of all vertebrates, including humans.
The analysis of the amphioxus genome has served to clarify the origin of our own genome, and as showed it is in a key position to understand the origin and functioning of
gene families and gene networks critical for embryonic development and physiology. Besides,
technical advances in its reproduction and experimentation make plausible to
dream in illuminating the secrets of our origins and the functioning of the genome
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